US20170182371A1 - Golf ball - Google Patents
Golf ball Download PDFInfo
- Publication number
- US20170182371A1 US20170182371A1 US15/362,208 US201615362208A US2017182371A1 US 20170182371 A1 US20170182371 A1 US 20170182371A1 US 201615362208 A US201615362208 A US 201615362208A US 2017182371 A1 US2017182371 A1 US 2017182371A1
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- Prior art keywords
- golf ball
- preferably equal
- equal
- less
- dimples
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0004—Surface depressions or protrusions
- A63B37/0019—Specified dimple depth
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0004—Surface depressions or protrusions
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0004—Surface depressions or protrusions
- A63B37/0017—Specified total dimple volume
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0004—Surface depressions or protrusions
- A63B37/0018—Specified number of dimples
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0004—Surface depressions or protrusions
- A63B37/0021—Occupation ratio, i.e. percentage surface occupied by dimples
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0023—Covers
- A63B37/0029—Physical properties
- A63B37/0031—Hardness
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0023—Covers
- A63B37/0029—Physical properties
- A63B37/0033—Thickness
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0038—Intermediate layers, e.g. inner cover, outer core, mantle
- A63B37/004—Physical properties
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0038—Intermediate layers, e.g. inner cover, outer core, mantle
- A63B37/004—Physical properties
- A63B37/0043—Hardness
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0038—Intermediate layers, e.g. inner cover, outer core, mantle
- A63B37/004—Physical properties
- A63B37/0043—Hardness
- A63B37/0044—Hardness gradient
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0038—Intermediate layers, e.g. inner cover, outer core, mantle
- A63B37/004—Physical properties
- A63B37/0045—Thickness
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/005—Cores
- A63B37/006—Physical properties
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/005—Cores
- A63B37/006—Physical properties
- A63B37/0062—Hardness
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/005—Cores
- A63B37/006—Physical properties
- A63B37/0062—Hardness
- A63B37/00621—Centre hardness
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/005—Cores
- A63B37/006—Physical properties
- A63B37/0062—Hardness
- A63B37/00622—Surface hardness
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/005—Cores
- A63B37/006—Physical properties
- A63B37/0062—Hardness
- A63B37/0063—Hardness gradient
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/005—Cores
- A63B37/006—Physical properties
- A63B37/0064—Diameter
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/007—Characteristics of the ball as a whole
- A63B37/0072—Characteristics of the ball as a whole with a specified number of layers
- A63B37/0076—Multi-piece balls, i.e. having two or more intermediate layers
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/007—Characteristics of the ball as a whole
- A63B37/0077—Physical properties
- A63B37/008—Diameter
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/007—Characteristics of the ball as a whole
- A63B37/0077—Physical properties
- A63B37/0092—Hardness distribution amongst different ball layers
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- A—HUMAN NECESSITIES
- A63—SPORTS; GAMES; AMUSEMENTS
- A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
- A63B37/00—Solid balls; Rigid hollow balls; Marbles
- A63B37/0003—Golf balls
- A63B37/0004—Surface depressions or protrusions
- A63B37/002—Specified dimple diameter
Definitions
- the present invention relates to golf balls. Specifically, the present invention relates to golf balls that include a core having a two-layer structure, a mid layer, and a cover and further have a plurality of dimples on the surface thereof.
- the greatest interest to golf players concerning golf balls is flight distance.
- golf players place importance on flight distances upon shots with a driver.
- the initial speed, the spin rate, and the launch angle of a golf ball when the golf ball is hit with a golf club are referred to as three initial elements.
- the flight distance of the golf ball is influenced by the three initial elements. The higher the initial speed of the ball is, the larger the flight distance is.
- An appropriate spin rate and an appropriate launch angle also contribute to flight distance.
- JPH11-206920 discloses a golf ball including an inner core and an outer core. Such golf balls having two core layers are also disclosed in JP2003-190331 (US2003/0130065), JP2006-289065 (US2006/0229143), JP2007-190382 (US2007/0259739), JPH10-328326 (U.S. Pat. No. 6,468,169), JPH10-328328 (U.S. Pat. No. 6,248,027), JP2000-60997 (U.S. Pat. No. 6,251,031), and JP2009-219871 (US2008/0161132).
- the dimples disturb the air flow around the golf ball during flight to cause turbulent flow separation. This phenomenon is referred to as “turbulization”. Due to the turbulization, separation points of the air from the golf ball shift backwards leading to a reduction of drag. The turbulization promotes the displacement between the separation point on the upper side and the separation point on the lower side of the golf ball, which results from the backspin, thereby enhancing the lift force that acts upon the golf ball. Excellent dimples efficiently disturb the air flow. The excellent dimples produce a long flight distance.
- JP2009-172192 discloses a golf ball on which dimples are randomly arranged.
- the dimple pattern of the golf ball is referred to as a random pattern.
- the random pattern can contribute to the flight performance of the golf ball.
- JP2012-10822 also discloses a golf ball having a random pattern.
- JP2007-175267 discloses a dimple pattern in which the number of units in a high-latitude region is different from the number of units in a low-latitude region.
- JP2007-195591 discloses a dimple pattern in which the number of the types of dimples in a low-latitude region is larger than the number of the types of dimples in a high-latitude region.
- JP2013-153966 discloses a dimple pattern having a high dimple density and small variation in dimple size.
- An object of the present invention is to provide a golf ball having excellent flight performance upon hitting with a driver.
- a golf ball according to the present invention includes an inner core, an outer core positioned outside the inner core, a mid layer positioned outside the outer core, and a cover positioned outside the mid layer.
- the golf ball has a plurality of dimples on a surface thereof.
- the dimples include a plurality of small dimples each having an area of less than 8.0 mm 2 and a plurality of large dimples each having an area of equal to or greater than 8.0 mm 2 .
- a ratio PS of a sum of the areas of the small dimples relative to a surface area of a phantom sphere of the golf ball is less than 2.0%.
- a ratio PL of a sum of the areas of the large dimples relative to the surface area of the phantom sphere is equal to or greater than 79.0%.
- a degree of uniformity G of the areas (mm 2 ) of the large dimples is equal to or less than 1.15.
- the spin rate is low, and the initial speed of the ball is high. Furthermore, with the golf ball, turbulization is promoted by the dimples. By the appropriate three initial elements and the appropriate aerodynamic characteristic, with the golf ball, a large flight distance is obtained upon a shot with a driver.
- the golf ball meets the following mathematical formula.
- the golf ball meets the following mathematical formula.
- the golf ball meets the following mathematical formula.
- the ratio PS is equal to or greater than 0.7%.
- a number NS of the small dimples is equal to or greater than 6 but equal to or less than 20.
- a ratio (NS/N) of a number NS of the small dimples relative to a total number N of the dimples is equal to or greater than 0.01 but equal to or less than 0.07.
- a depth of a deepest part of each dimple from a surface of the phantom sphere is equal to or greater than 0.10 mm but equal to or less than 0.65 mm.
- a total volume of the dimples is equal to or greater than 450 mm 3 but equal to or less than 750 mm 3 .
- the ratio PL is equal to or greater than 79.5%, and the degree of uniformity G is equal to or less than 1.10.
- the ratio PL is equal to or greater than 80.0%, and the degree of uniformity G is equal to or less than 1.05.
- FIG. 1 is a cross-sectional view of a golf ball according to one embodiment of the present invention.
- FIG. 2 is an enlarged front view of the golf ball in FIG. 1 ;
- FIG. 3 is a back view of the golf ball in FIG. 2 ;
- FIG. 4 is a plan view of the golf ball in FIG. 2 ;
- FIG. 5 is a bottom view of the golf ball in FIG. 2 ;
- FIG. 6 is a left side view of the golf ball in FIG. 2 ;
- FIG. 7 is a right side view of the golf ball in FIG. 2 ;
- FIG. 8 is a partially enlarged cross-sectional view of the golf ball in FIG. 1 ;
- FIG. 9 is a front view of a golf ball according to Example 1 of the present invention.
- FIG. 10 is a plan view of the golf ball in FIG. 9 .
- a golf ball 2 shown in FIG. 1 includes a spherical inner core 4 , an outer core 6 positioned outside the inner core 4 , a mid layer 8 positioned outside the outer core 6 , and a cover 10 positioned outside the mid layer 8 .
- the golf ball 2 has a plurality of dimples 12 on the surface thereof. Of the surface of the golf ball 2 , a part other than the dimples 12 is a land 14 .
- the golf ball 2 includes a paint layer and a mark layer on the external side of the cover 10 although these layers are not shown in the drawing.
- the golf ball 2 may include another layer between the outer core 6 and the mid layer 8 .
- the golf ball 2 may include another layer between the mid layer 8 and the cover 10 .
- the golf ball 2 preferably has a diameter of equal to or greater than 40 mm but equal to or less than 45 mm. From the standpoint of conformity to the rules established by the United States Golf Association (USGA), the diameter is particularly preferably equal to or greater than 42.67 mm. In light of suppression of air resistance, the diameter is more preferably equal to or less than 44 mm and particularly preferably equal to or less than 42.80 mm.
- the golf ball 2 preferably has a weight of equal to or greater than 40 g but equal to or less than 50 g. In light of attainment of great inertia, the weight is more preferably equal to or greater than 44 g and particularly preferably equal to or greater than 45.00 g. From the standpoint of conformity to the rules established by the USGA, the weight is particularly preferably equal to or less than 45.93 g.
- the inner core 4 is formed by crosslinking a rubber composition.
- base rubbers for use in the rubber composition include polybutadienes, polyisoprenes, styrene-butadiene copolymers, ethylene-propylene-diene copolymers, and natural rubbers. In light of high initial speed of the ball, polybutadienes are preferable.
- the polybutadiene is a principal component. Specifically, the proportion of the polybutadiene to the entire base rubber is preferably equal to or greater than 50% by weight and particularly preferably equal to or greater than 80% by weight. A polybutadiene in which the proportion of cis-1,4 bonds is equal to or greater than 80% is particularly preferable.
- the rubber composition of the inner core 4 preferably includes a co-crosslinking agent.
- co-crosslinking agents in light of high initial speed of the ball are monovalent or bivalent metal salts of an ⁇ , ⁇ -unsaturated carboxylic acid having 2 to 8 carbon atoms.
- preferable co-crosslinking agents include zinc acrylate, magnesium acrylate, zinc methacrylate, and magnesium methacrylate. In light of resilience performance, zinc acrylate and zinc methacrylate are particularly preferable.
- the rubber composition may include a metal oxide and an ⁇ , ⁇ -unsaturated carboxylic acid having 2 to 8 carbon atoms. They both react with each other in the rubber composition to obtain a salt.
- the salt serves as a co-crosslinking agent.
- preferable ⁇ , ⁇ -unsaturated carboxylic acids include acrylic acid and methacrylic acid.
- preferable metal oxides include zinc oxide and magnesium oxide.
- the amount of the co-crosslinking agent per 100 parts by weight of the base rubber is preferably equal to or greater than 10 parts by weight and particularly preferably equal to or greater than 15 parts by weight. In light of low spin rate upon a shot with a driver, this amount is preferably equal to or less than 40 parts by weight and particularly preferably equal to or less than 35 parts by weight. As described in detail later, a low spin rate can achieve a large flight distance upon a shot with a driver.
- the rubber composition of the inner core 4 includes an organic peroxide.
- the organic peroxide serves as a crosslinking initiator.
- the organic peroxide contributes to the resilience performance of the golf ball 2 .
- suitable organic peroxides include dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and di-t-butyl peroxide.
- An organic peroxide with particularly high versatility is dicumyl peroxide.
- the amount of the organic peroxide per 100 parts by weight of the base rubber is preferably equal to or greater than 0.1 parts by weight, more preferably equal to or greater than 0.3 parts by weight, and particularly preferably equal to or greater than 0.5 parts by weight. In light of low spin rate, this amount is preferably equal to or less than 3.0 parts by weight, more preferably equal to or less than 2.8 parts by weight, and particularly preferably equal to or less than 2.5 parts by weight.
- the rubber composition of the inner core 4 includes an organic sulfur compound.
- Organic sulfur compounds include naphthalenethiol compounds, benzenethiol compounds, and disulfide compounds.
- naphthalenethiol compounds include 1-naphthalenethiol, 2-naphthalenethiol, 4-chloro-1-naphthalenethiol, 4-bromo-1-naphthalenethiol, 1-chloro-2-naphthalenethiol, 1-bromo-2-naphthalenethiol, 1-fluoro-2-naphthalenethiol, 1-cyano-2-naphthalenethiol, and 1-acetyl-2-naphthalenethiol.
- benzenethiol compounds include benzenethiol, 4-chlorobenzenethiol, 3-chlorobenzenethiol, 4-bromobenzenethiol, 3-bromobenzenethiol, 4-fluorobenzenethiol, 4-iodobenzenethiol, 2,5-dichlorobenzenethiol, 3,5-dichlorobenzenethiol, 2,6-dichlorobenzenethiol, 2,5-dibromobenzenethiol, 3,5-dibromobenzenethiol, 2-chloro-5-bromobenzenethiol, 2,4,6-trichlorobenzenethiol, 2,3,4,5,6-pentachlorobenzenethiol, 2,3,4,5,6-pentafluorobenzenethiol, 4-cyanobenzenethiol, 2-cyanobenzenethiol, 4-nitrobenzenethiol, and 2-
- disulfide compounds include diphenyl disulfide, bis(4-chlorophenyl)disulfide, bis(3-chlorophenyl)disulfide, bis(4-bromophenyl)disulfide, bis(3-bromophenyl)disulfide, bis(4-fluorophenyl)disulfide, bis(4-iodophenyl)disulfide, bis(4-cyanophenyl)disulfide, bis(2,5-dichlorophenyl)disulfide, bis(3,5-dichlorophenyl)disulfide, bis(2,6-dichlorophenyl)disulfide, bis(2,5-dibromophenyl)disulfide, bis(3,5-dibromophenyl)disulfide, bis(2-chloro-5-bromophenyl)disulfide, bis(
- the amount of the organic sulfur compound per 100 parts by weight of the base rubber is preferably equal to or greater than 0.1 parts by weight and particularly preferably equal to or greater than 0.2 parts by weight. In light of low spin rate, this amount is preferably equal to or less than 1.5 parts by weight, more preferably equal to or less than 1.0 parts by weight, and particularly preferably equal to or less than 0.8 parts by weight. Two or more organic sulfur compounds may be used in combination.
- the rubber composition of the inner core 4 may include a filler for the purpose of specific gravity adjustment and the like.
- suitable fillers include zinc oxide, barium sulfate, calcium carbonate, and magnesium carbonate.
- the amount of the filler is determined as appropriate so that the intended specific gravity of the inner core 4 is accomplished.
- the rubber composition may include various additives, such as sulfur, a carboxylic acid, a carboxylate, an anti-aging agent, a coloring agent, a plasticizer, a dispersant, and the like, in an adequate amount.
- the rubber composition may include crosslinked rubber powder or synthetic resin powder.
- the inner core 4 preferably has a diameter D1 of equal to or greater than 15.0 mm. With the golf ball 2 that includes the inner core 4 having a diameter D1 of equal to or greater than 15.0 mm, spin upon a shot with a driver is suppressed.
- the diameter D1 is more preferably equal to or greater than 18.0 mm and particularly preferably equal to or greater than 20.0 mm. From the standpoint that the outer core 6 can have a sufficient thickness, the diameter D1 is preferably equal to or less than 32.0 mm, more preferably equal to or less than 29.0 mm, and particularly preferably equal to or less than 27.0 mm.
- the inner core 4 preferably has a volume V1 of equal to or greater than 1700 mm 3 .
- the volume V1 is more preferably equal to or greater than 3000 mm 3 and particularly preferably equal to or greater than 4200 mm 3 .
- the volume V1 is preferably equal to or less than 17000 mm 3 , more preferably equal to or less than 13000 mm 3 , and particularly preferably equal to or less than 10300 mm 3 .
- the inner core 4 has a weight of preferably equal to or greater than 10 g but equal to or less than 30 g.
- the temperature for crosslinking the inner core 4 is equal to or higher than 140° C. but equal to or lower than 180° C.
- the time period for crosslinking the inner core 4 is equal to or longer than 10 minutes but equal to or shorter than 60 minutes.
- the difference De1 between a hardness H1o at the central point of the inner core 4 and a boundary inside hardness H1in of the inner core 4 is great.
- the inner core 4 having the great difference De1 has a so-called outer-hard/inner-soft structure.
- an appropriate trajectory height and appropriate flight duration are required.
- the run after landing is short.
- the golf ball 2 that achieves a desired trajectory height and desired flight duration at a high launch angle the run after landing is long.
- the golf ball 2 that achieves a desired trajectory height and desired flight duration at a high launch angle is preferable.
- the inner core 4 having an outer-hard/inner-soft structure can contribute to a high launch angle and a low spin rate as described above.
- the golf ball 2 including the inner core 4 has excellent flight performance.
- the difference De1 is preferably equal to or greater than 5, more preferably equal to or greater than 8, and particularly preferably equal to or greater than 10.
- the difference De1 is preferably equal to or less than 40 and particularly preferably equal to or less than 30.
- the hardness gradually increases from the central point thereof toward the surface thereof.
- the central hardness H1o is preferably equal to or greater than 40, more preferably equal to or greater than 45, and particularly preferably equal to or greater than 50.
- the hardness H1o is preferably equal to or less than 80, more preferably equal to or less than 75, and particularly preferably equal to or less than 70.
- the hardness H1o is measured with a Shore C type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss für Anlagenbau GmbH).
- the hardness scale is pressed against the central point of the cross-section of a hemisphere obtained by cutting the golf ball 2 .
- the measurement is conducted in the environment of 23° C.
- the boundary inside hardness H1in is preferably equal to or greater than 60, more preferably equal to or greater than 65, and particularly preferably equal to or greater than 70.
- the hardness H1in is preferably equal to or less than 85, more preferably equal to or less than 80, and particularly preferably equal to or less than 78.
- the hardness H1in is measured with a Shore C type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss für Anlagenbau GmbH).
- the hardness scale is pressed against a cross-section of the golf ball 2 that has been cut into two halves.
- the hardness scale is pressed against a point separated by 1 mm radially inward from the boundary between the inner core 4 and the outer core 6 .
- the measurement is conducted in the environment of 23° C.
- a value Va calculated by the following mathematical formula exceeds 600 and is less than 1000.
- the inner core 4 meets the following mathematical formula (3).
- the value Va is approximate to the integral of a hardness distribution of the inner core 4 .
- the spin rate upon a shot with a driver is low.
- the golf ball 2 that includes the inner core 4 having a value Va of less than 1000 the initial speed of the ball upon a shot with a driver is high.
- the low spin rate and the high initial speed of the ball achieve a large flight distance.
- the golf ball 2 more preferably meets the following mathematical formula.
- the value Va preferably exceeds 700 and is less than 900.
- the outer core 6 is formed by crosslinking a rubber composition.
- the composition can include the base rubber described above for the inner core 4 .
- the rubber composition of the outer core 6 preferably includes a co-crosslinking agent.
- co-crosslinking agents in light of high initial speed of the ball are monovalent or bivalent metal salts of an ⁇ , ⁇ -unsaturated carboxylic acid having 2 to 8 carbon atoms.
- preferable co-crosslinking agents include zinc acrylate, magnesium acrylate, zinc methacrylate, and magnesium methacrylate. In light of high initial speed of the ball, zinc acrylate and zinc methacrylate are particularly preferable.
- the rubber composition may include a metal oxide and an ⁇ , ⁇ -unsaturated carboxylic acid having 2 to 8 carbon atoms. They both react with each other in the rubber composition to obtain a salt.
- the salt serves as a co-crosslinking agent.
- preferable ⁇ , ⁇ -unsaturated carboxylic acids include acrylic acid and methacrylic acid.
- preferable metal oxides include zinc oxide and magnesium oxide.
- the amount of the co-crosslinking agent per 100 parts by weight of the base rubber is preferably equal to or greater than 25 parts by weight, more preferably equal to or greater than 30 parts by weight, and particularly preferably equal to or greater than 35 parts by weight. In light of feel at impact, this amount is preferably equal to or less than 55 parts by weight, more preferably equal to or less than 50 parts by weight, and particularly preferably equal to or less than 45 parts by weight.
- the rubber composition of the outer core 6 includes an organic peroxide.
- the organic peroxide serves as a crosslinking initiator.
- the organic peroxide contributes to the resilience performance of the golf ball 2 .
- the rubber composition of the outer core 6 can include the organic peroxide described above for the inner core 4 .
- the amount of the organic peroxide per 100 parts by weight of the base rubber is preferably equal to or greater than 0.1 parts by weight, more preferably equal to or greater than 0.3 parts by weight, and particularly preferably equal to or greater than 0.5 parts by weight. In light of feel at impact, this amount is preferably equal to or less than 3.0 parts by weight, more preferably equal to or less than 2.8 parts by weight, and particularly preferably equal to or less than 2.5 parts by weight.
- the rubber composition of the outer core 6 includes an organic sulfur compound.
- the rubber composition can include the organic sulfur compound described above for the inner core 4 .
- the amount of the organic sulfur compound per 100 parts by weight of the base rubber is preferably equal to or greater than 0.1 parts by weight and particularly preferably equal to or greater than 0.2 parts by weight. In light of feel at impact, this amount is preferably equal to or less than 1.5 parts by weight, more preferably equal to or less than 1.0 parts by weight, and particularly preferably equal to or less than 0.8 parts by weight.
- the rubber composition of the outer core 6 may include a filler for the purpose of specific gravity adjustment and the like.
- suitable fillers include zinc oxide, barium sulfate, calcium carbonate, and magnesium carbonate.
- the amount of the filler is determined as appropriate so that the intended specific gravity of the outer core 6 is accomplished.
- the rubber composition may include various additives, such as sulfur, a carboxylic acid, a carboxylate, an anti-aging agent, a coloring agent, a plasticizer, a dispersant, and the like, in an adequate amount.
- the rubber composition may include crosslinked rubber powder or synthetic resin powder.
- the outer core 6 preferably has a diameter D2 of equal to or greater than 37.0 mm.
- the golf ball 2 that includes the outer core 6 having a diameter D2 of equal to or greater than 37.0 mm has a high initial speed upon a shot with a driver.
- the diameter D2 is more preferably equal to or greater than 37.5 mm and particularly preferably equal to or greater than 38.0 mm.
- the diameter D2 is preferably equal to or less than 40.5 mm, more preferably equal to or less than 40.0 mm, and particularly preferably equal to or less than 39.5 mm.
- the outer core 6 preferably has a volume V2 of equal to or greater than 18000 mm 3 .
- the golf ball 2 that includes the outer core 6 having a volume V2 of equal to or greater than 18000 mm 3 has a high initial speed upon a shot with a driver.
- the volume V2 is more preferably equal to or greater than 19500 mm 3 and particularly preferably equal to or greater than 21000 mm 3 .
- the volume V2 is preferably equal to or less than 29000 mm 3 , more preferably equal to or less than 27000 mm 3 , and particularly preferably equal to or less than 26000 mm 3 .
- the volume V2 is calculated by subtracting the volume of the inner core 4 from the volume of a sphere consisting of the inner core 4 and the outer core 6 .
- the outer core 6 has a weight of preferably equal to or greater than 10 g but equal to or less than 30 g.
- the temperature for crosslinking the outer core 6 is equal to or higher than 140° C. but equal to or lower than 180° C.
- the time period for crosslinking the outer core 6 is equal to or longer than 10 minutes but equal to or shorter than 60 minutes.
- the difference De2 between a surface hardness H2s and a boundary outside hardness H2out of the outer core 6 is preferably equal to or greater than ⁇ 2 but equal to or less than 2.
- a hardness distribution of the outer core 6 is close to being flat.
- the golf ball 2 that includes the outer core 6 has a high initial speed upon a shot with a driver.
- the outer core 6 can contribute to the flight performance of the golf ball 2 .
- the difference De2 is preferably equal to or greater than ⁇ 1 but equal to or less than 1.
- the difference De2 may be zero.
- the difference between a Shore C hardness at a point having a highest hardness and a Shore C hardness at a point having a lowest hardness in the zone from the boundary between the inner core 4 and the outer core 6 to the surface of the outer core 6 is preferably equal to or less than 5, more preferably equal to or less than 4, and particularly preferably equal to or less than 3.
- the boundary outside hardness H2out is preferably equal to or greater than 60, more preferably equal to or greater than 70, and particularly preferably equal to or greater than 75.
- the hardness H2out is preferably equal to or less than 90, more preferably equal to or less than 87, and particularly preferably equal to or less than 85.
- the hardness H2out is measured with a Shore C type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss für Anlagenbau GmbH).
- the hardness scale is pressed against a cross-section of the golf ball 2 that has been cut into two halves.
- the hardness scale is pressed against a point separated by 1 mm radially outward from the boundary between the inner core 4 and the outer core 6 .
- the measurement is conducted in the environment of 23° C.
- the surface hardness H2s is preferably equal to or greater than 70, more preferably equal to or greater than 72, and particularly preferably equal to or greater than 74. In light of durability of the golf ball 2 , the hardness H2s is preferably equal to or less than 90, more preferably equal to or less than 88, and particularly preferably equal to or less than 86.
- the hardness H2s is measured with a Shore C type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss für Anlagenbau GmbH).
- the hardness scale is pressed against the surface of the outer core 6 .
- the measurement is conducted in the environment of 23° C.
- a core having a small difference De2 can be obtained by a two-stage crosslinking process. Specifically, in a first crosslinking process, a rubber composition is crosslinked at a predetermined temperature. In a second crosslinking process, the rubber composition is crosslinked at a temperature higher than the temperature in the first crosslinking process.
- the ratio (V2/V1) between the volume V2 of the outer core 6 and the volume V1 of the inner core 4 meets the following mathematical formula (1).
- the ratio (V2/V1) exceeds 1.0 and is less than 7.0.
- the golf ball 2 having a ratio (V2/V1) of exceeding 1.0 has a high initial speed upon a shot with a driver.
- the golf ball 2 having a ratio (V2/V1) of less than 7.0 has a low spin rate upon a shot with a driver.
- the high initial speed and the low spin rate of the ball achieve a large flight distance.
- the golf ball 2 more preferably meets the following mathematical formula.
- the golf ball 2 particularly preferably meets the following mathematical formula.
- the hardness difference De2 in the outer core 6 and the hardness difference De1 in the inner core 4 meet the following mathematical formula (2).
- both a high initial speed and a low spin rate are achieved upon a shot with a driver.
- the golf ball 2 more preferably meets the following mathematical formula.
- the golf ball 2 particularly preferably meets the following mathematical formula.
- the mid layer 8 is positioned between the outer core 6 and the cover 10 .
- the mid layer 8 is formed from a thermoplastic resin composition.
- the base polymer of the resin composition include ionomer resins, polyesters, polyamides, polyurethanes, polyolefins, and polystyrenes. Ionomer resins are particularly preferable. Ionomer resins are highly elastic.
- the golf ball 2 that includes the mid layer 8 including an ionomer resin has excellent resilience performance upon a shot with a driver.
- an ionomer resin and another resin may be used in combination.
- the ionomer resin is included as the principal component of the base polymer.
- the proportion of the ionomer resin to the entire base polymer is preferably equal to or greater than 50% by weight, more preferably equal to or greater than 70% by weight, and particularly preferably equal to or greater than 85% by weight.
- preferable ionomer resins include binary copolymers formed with an ⁇ -olefin and an ⁇ , ⁇ -unsaturated carboxylic acid having 3 to 8 carbon atoms.
- a preferable binary copolymer includes 80% by weight or more but 90% by weight or less of an ⁇ -olefin, and 10% by weight or more but 20% by weight or less of an ⁇ , ⁇ -unsaturated carboxylic acid.
- the binary copolymer has excellent resilience performance.
- Examples of other preferable ionomer resins include ternary copolymers formed with: an ⁇ -olefin; an ⁇ , ⁇ -unsaturated carboxylic acid having 3 to 8 carbon atoms; and an ⁇ , ⁇ -unsaturated carboxylate ester having 2 to 22 carbon atoms.
- a preferable ternary copolymer includes 70% by weight or more but 85% by weight or less of an ⁇ -olefin, 5% by weight or more but 30% by weight or less of an ⁇ , ⁇ -unsaturated carboxylic acid, and 1% by weight or more but 25% by weight or less of an ⁇ , ⁇ -unsaturated carboxylate ester.
- the ternary copolymer has excellent resilience performance.
- preferable ⁇ -olefins are ethylene and propylene, while preferable ⁇ , ⁇ -unsaturated carboxylic acids are acrylic acid and methacrylic acid.
- a particularly preferable ionomer resin is a copolymer formed with ethylene and acrylic acid.
- Another particularly preferable ionomer resin is a copolymer formed with ethylene and methacrylic acid.
- some of the carboxyl groups are neutralized with metal ions.
- metal ions for use in neutralization include sodium ion, potassium ion, lithium ion, zinc ion, calcium ion, magnesium ion, aluminum ion, and neodymium ion.
- the neutralization may be carried out with two or more types of metal ions.
- Particularly suitable metal ions in light of resilience performance and durability of the golf ball 2 are sodium ion, zinc ion, lithium ion, and magnesium ion.
- ionomer resins include trade names “Himilan 1555”, “Himilan 1557”, “Himilan 1605”, “Himilan 1706”, “Himilan 1707”, “Himilan 1856”, “Himilan 1855”, “Himilan AM7311”, “Himilan AM7315”, “Himilan AM7317”, “Himilan AM7329”, and “Himilan AM7337”, manufactured by Du Pont-MITSUI POLYCHEMICALS Co., Ltd.; trade names “Surlyn 6120”, “Surlyn 6910”, “Surlyn 7930”, “Surlyn 7940”, “Surlyn 8140”, “Surlyn 8150”, “Surlyn 8940”, “Surlyn 8945”, “Surlyn 9120”, “Surlyn 9150”, “Surlyn 9910”, “Surlyn 9945”, “Surlyn AD8546”, “HPF1000”, and “HPF2000”, manufactured by E.I.
- IOTEK 7010 du Pont de Nemours and Company
- IOTEK 7030 trade names “IOTEK 7510”, “IOTEK 7520”, “IOTEK 8000”, and “IOTEK 8030”, manufactured by ExxonMobil Chemical Corporation.
- Two or more ionomer resins may be used in combination.
- the resin composition of the mid layer 8 may include a styrene block-containing thermoplastic elastomer.
- the styrene block-containing thermoplastic elastomer includes a polystyrene block as a hard segment, and a soft segment.
- a typical soft segment is a diene block.
- Examples of compounds for the diene block include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. Butadiene and isoprene are preferable. Two or more compounds may be used in combination.
- styrene block-containing thermoplastic elastomers examples include styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), styrene-isoprene-butadiene-styrene block copolymers (SIBS), hydrogenated SBS, hydrogenated SIS, and hydrogenated SIBS.
- hydrogenated SBS include styrene-ethylene-butylene-styrene block copolymers (SEBS).
- hydrogenated SIS examples include styrene-ethylene-propylene-styrene block copolymers (SEPS).
- SIBS styrene-ethylene-ethylene-propylene-styrene block copolymers
- the content of the styrene component in the styrene block-containing thermoplastic elastomer is preferably equal to or greater than 10% by weight, more preferably equal to or greater than 12% by weight, and particularly preferably equal to or greater than 15% by weight.
- the content is preferably equal to or less than 50% by weight, more preferably equal to or less than 47% by weight, and particularly preferably equal to or less than 45% by weight.
- styrene block-containing thermoplastic elastomers include an alloy of an olefin and one or more members selected from the group consisting of SBS, SIS, SIBS, SEBS, SEPS, and SEEPS.
- the olefin component in the alloy is presumed to contribute to improvement of compatibility with another base polymer.
- the alloy can contribute to the resilience performance of the golf ball 2 .
- An olefin having 2 to 10 carbon atoms is preferable.
- suitable olefins include ethylene, propylene, butene, and pentene. Ethylene and propylene are particularly preferable.
- polymer alloys include trade names “RABALON T3221C”, “RABALON T3339C”, “RABALON SJ4400N”, “RABALON SJ5400N”, “RABALON SJ6400N”, “RABALON SJ7400N”, “RABALON SJ8400N”, “RABALON SJ9400N”, and “RABALON SR04”, manufactured by Mitsubishi Chemical Corporation.
- styrene block-containing thermoplastic elastomers include trade name “Epofriend A1010” manufactured by Daicel Chemical Industries, Ltd., and trade name “SEPTON HG-252” manufactured by Kuraray Co., Ltd.
- the proportion of the styrene block-containing thermoplastic elastomer to the entire base polymer is preferably equal to or greater than 1% by weight and particularly preferably equal to or greater than 2% by weight.
- the proportion is preferably equal to or less than 15% by weight, more preferably equal to or less than 10% by weight, and particularly preferably equal to or less than 5% by weight.
- the resin composition of the mid layer 8 may include a polyamide.
- a polyamide With the golf ball 2 that includes the mid layer 8 including a polyamide, the spin upon a shot with a driver is suppressed.
- Specific examples of polyamides include polyamide 6, polyamide 11, polyamide 12, polyamide 66, and polyamide 610. In light of versatility, polyamide 6 is preferable.
- the proportion of the polyamide to the entire base polymer is preferably equal to or greater than 5% by weight, more preferably equal to or greater than 10% by weight, and particularly preferably equal to or greater than 15% by weight.
- the proportion is preferably equal to or less than 50% by weight, more preferably equal to or less than 45% by weight, and particularly preferably equal to or less than 40% by weight.
- the resin composition of the mid layer 8 may include a filler for the purpose of specific gravity adjustment and the like.
- suitable fillers include zinc oxide, barium sulfate, calcium carbonate, and magnesium carbonate.
- the resin composition may include powder of a metal with a high specific gravity. Specific examples of metals with a high specific gravity include tungsten and molybdenum. The amount of the filler is determined as appropriate so that the intended specific gravity of the mid layer 8 is accomplished.
- the resin composition may include a coloring agent, crosslinked rubber powder, or synthetic resin powder. When the hue of the golf ball 2 is white, a typical coloring agent is titanium dioxide.
- the mid layer 8 preferably has a hardness Hm of equal to or greater than 55.
- the golf ball 2 that includes the mid layer 8 having a hardness Hm of equal to or greater than 55 has a low spin rate upon a shot with a driver.
- the mid layer 8 can contribute to the flight performance of the golf ball 2 .
- the hardness Hm is more preferably equal to or greater than 58 and particularly preferably equal to or greater than 61.
- the hardness Hm is preferably equal to or less than 80, more preferably equal to or less than 75, and particularly preferably equal to or less than 72.
- the hardness Hm of the mid layer 8 is measured according to the standards of “ASTM-D 2240-68”.
- the hardness Hm is measured with a Shore D type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss für Anlagen GmbH).
- a sheet that is formed by hot press is formed from the same material as that of the mid layer 8 , and has a thickness of about 2 mm is used. Prior to the measurement, a sheet is kept at 23° C. for two weeks. At the measurement, three sheets are stacked.
- the mid layer 8 has a thickness Tm of preferably equal to or greater than 0.3 mm but equal to or less than 2.5 mm.
- the golf ball 2 that includes a mid layer 8 having a thickness Tm of equal to or greater than 0.3 mm has a low spin rate upon a shot with a driver.
- the thickness Tm is more preferably equal to or greater than 0.5 mm and particularly preferably equal to or greater than 0.8 mm.
- the golf ball 2 that includes the mid layer 8 having a thickness Tm of equal to or less than 2.5 mm has excellent feel at impact.
- the thickness Tm is more preferably equal to or less than 2.0 mm and particularly preferably equal to or less than 1.8 mm.
- the thickness Tm is measured at a position immediately below the land 14 .
- the golf ball 2 may include two or more mid layers 8 positioned between the outer core 6 and the cover 10 .
- the thickness of each mid layer 8 preferably falls within the above range.
- the cover 10 is the outermost layer except the mark layer and the paint layer.
- the cover 10 is formed from a resin composition.
- the base polymer of the resin composition include polyurethanes, ionomer resins, polyesters, polyamides, polyolefins, and polystyrenes.
- a preferable base polymer in light of controllability upon hitting with a short iron is a polyurethane.
- the proportion of the polyurethane to the entire base polymer is preferably equal to or greater than 50% by weight, more preferably equal to or greater than 60% by weight, and particularly preferably equal to or greater than 70% by weight.
- the polyurethane has a urethane bond within the molecule.
- the urethane bond can be formed by reacting a polyol with a polyisocyanate.
- a chain-lengthening reaction may be carried out.
- the chain-lengthening reaction can be carried out by a polyamine or a polyol having a low molecular weight.
- polyurethane examples include
- (A1) a polyurethane including a polyisocyanate component and a high-molecular-weight polyol component
- (A2) a polyurethane including a polyisocyanate component, a high-molecular-weight polyol component, and a low-molecular-weight polyol,
- (A3) a polyurethane including a polyisocyanate component, a high-molecular-weight polyol component, and a polyamine component, and
- (A4) a polyurethane including a polyisocyanate component, a high-molecular-weight polyol component, a low-molecular-weight polyol component, and a polyamine component.
- the polyol as a material for the urethane bond, has a plurality of hydroxyl groups. Low-molecular-weight polyols and high-molecular-weight polyols can be used.
- low-molecular-weight polyols examples include diols, triols, tetraols, and hexaols.
- diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2,3-dimethyl-2,3-butanediol, neopentyl glycol, pentanediol, hexanediol, heptanediol, octanediol, and 1,6-cyclohexanedimethylol.
- triols include glycerin, trimethylol propane, and hexanetriol.
- tetraols include pentaerythritol and sorbitol.
- high-molecular-weight polyols examples include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG); condensed polyester polyols such as polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA); lactone polyester polyols such as poly-s-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols. Two or more polyols may be used in combination.
- PEG polyoxyethylene glycol
- PPG polyoxypropylene glycol
- PTMG polytetramethylene ether glycol
- condensed polyester polyols such as polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA)
- lactone polyester polyols such as
- the high-molecular-weight polyol has a number average molecular weight of preferably equal to or greater than 400 and more preferably equal to or greater than 1000.
- the number average molecular weight is preferably equal to or less than 10000.
- Particularly preferably polyols are diols.
- the polyisocyanate as a material for the urethane bond, has two or more isocyanate groups.
- polyisocyanates include aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates. Two or more types of polyisocyanates may be used in combination.
- aromatic polyisocyanates examples include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture (TDI) of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3′-bitolylene-4,4′-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI).
- MDI 4,4′-diphenylmethane diisocyanate
- NDI 1,5-naphthylene diisocyanate
- TODI 3,3′-bitolylene-4,4′-diisocyanate
- XDI
- alicyclic polyisocyanates examples include 4,4′-dicyclohexylmethane diisocyanate (H 12 MDI), 1,3-bis(isocyanatomethyl)cyclohexane (H 6 XDI), isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate (CHDI).
- H 12 MDI 4,4′-dicyclohexylmethane diisocyanate
- H 6 XDI 1,3-bis(isocyanatomethyl)cyclohexane
- IPDI isophorone diisocyanate
- CHDI trans-1,4-cyclohexane diisocyanate
- HDI hexamethylene diisocyanate
- aromatic polyisocyanates are preferable.
- TMXDI, XDI, HDI, H 6 XDI, IPDI, H 12 MDI, and NBD are preferable, and H 12 MDI is particularly preferable.
- H 12 MDI is excellent in both scuff resistance and weather resistance.
- the polyamine for the chain-lengthening reaction has two or more amino groups.
- polyamines include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and piperazine; and aromatic polyamines.
- an amino group is bonded to an aromatic ring.
- the amino group may be bonded directly to the aromatic ring.
- the amino group may be bonded indirectly to the aromatic ring via a lower alkylene group.
- Aromatic polyamines include monocyclic aromatic polyamines and polycyclic aromatic polyamines. In a monocyclic aromatic polyamine, two or more amino groups are bounded to one aromatic ring. A polycyclic aromatic polyamine has two or more aminophenyl groups. In each of the aminophenyl groups, one or more amino groups are bonded to one aromatic ring.
- monocyclic aromatic polyamines examples include polyamines in which an amino group is bonded directly to an aromatic ring, and polyamines in which an amino group is bonded to an aromatic ring via a lower alkylene group.
- monocyclic aromatic polyamines in which an amino group is bonded directly to an aromatic ring include phenylenediamine, toluenediamine, diethyltoluenediamine, and dimethylthiotoluenediamine.
- monocyclic aromatic polyamines in which an amino group is bonded to an aromatic ring via a lower alkylene group examples include xylylenediamine.
- polycyclic aromatic polyamines examples include poly(aminobenzene) in which two or more aminophenyl groups are bonded directly to each other, and polyamines in which two or more aminophenyl groups are bonded to each other via a lower alkylene group or an alkylene oxide group.
- Diaminodiphenylalkanes in which two aminophenyl groups are bonded to each other via a lower alkylene group are preferable, and 4,4′-diaminodiphenylmethane and derivatives thereof are particularly preferable.
- the cover 10 may include a thermoplastic polyurethane, or may include a thermosetting polyurethane. In light of productivity, the thermoplastic polyurethane is preferable.
- the thermoplastic polyurethane includes a polyurethane component as a hard segment, and a polyester component or a polyether component as a soft segment.
- the thermoplastic polyurethane is flexible.
- the cover 10 in which the polyurethane is used has excellent scuff resistance.
- thermoplastic polyurethane examples include trade names “Elastollan NY80A”, “Elastollan NY82A”, “Elastollan NY84A”, “Elastollan NY85A”, “Elastollan NY86A”, “Elastollan NY88A”, “Elastollan NY90A”, “Elastollan NY92A”, “Elastollan NY95A”, “Elastollan NY97A”, “Elastollan NY585”, “Elastollan KP016N”, and “Elastollan 1190ATR”, manufactured by BASF Japan Ltd.; and trade names “RESAMINE P4585LS” and “RESAMINE PS62490”, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.
- the resin composition of the cover 10 may include a coloring agent, a filler, a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent material, a fluorescent brightener, and the like in an adequate amount.
- a typical coloring agent is titanium dioxide.
- the cover 10 has a Shore D hardness Hc of preferably equal to or greater than 15, more preferably equal to or greater than 18, and particularly preferably equal to or greater than 20.
- the hardness Hc is preferably equal to or less than 40, more preferably equal to or less than 37, and particularly preferably equal to or less than 34.
- the hardness Hc of the cover 10 is measured according to the standards of “ASTM-D 2240-68”.
- the hardness Hc is measured with a Shore D type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss für Anlagen GmbH).
- a sheet that is formed by hot press is formed from the same material as that of the cover 10 , and has a thickness of about 2 mm is used. Prior to the measurement, a sheet is kept at 23° C. for two weeks. At the measurement, three sheets are stacked.
- the cover 10 has a thickness Tc of preferably equal to or greater than 0.1 mm, more preferably equal to or greater than 0.3 mm, and particularly preferably equal to or greater than 0.4 mm.
- the thickness Tc is preferably equal to or less than 2.0 mm, more preferably equal to or less than 1.5 mm, and particularly preferably equal to or less than 1.0 mm.
- the thickness Tc is measured at a position immediately below the land 14 .
- the cover 10 For forming the cover 10 , known methods such as injection molding, compression molding, and the like can be used. When forming the cover 10 , the dimples 12 are formed by pimples formed on the cavity face of a mold.
- the golf ball 2 may include a reinforcing layer between the mid layer 8 and the cover 10 .
- the reinforcing layer firmly adheres to the mid layer 8 and also to the cover 10 .
- the reinforcing layer suppresses separation of the mid layer 8 from the cover 10 .
- the reinforcing layer is formed from a resin composition. Examples of a preferable base polymer of the reinforcing layer include two-component curing type epoxy resins and two-component curing type urethane resins.
- the golf ball 2 preferably has an amount of compressive deformation Sb of equal to or greater than 2.0 mm but equal to or less than 3.5 mm.
- the golf ball 2 having an amount of compressive deformation Sb of equal to or greater than 2.0 mm has excellent feel at impact.
- the amount of compressive deformation Sb is preferably equal to or greater than 2.2 mm and particularly preferably equal to or greater than 2.3 mm.
- the golf ball 2 having an amount of compressive deformation Sb of equal to or less than 3.5 mm has a high initial speed upon a shot with a driver.
- the amount of compressive deformation Sb is more preferably equal to or less than 3.2 mm and particularly preferably equal to or less than 3.0 mm.
- a YAMADA type compression tester For measurement of the amount of compressive deformation Sb, a YAMADA type compression tester is used. In the tester, the golf ball 2 is placed on a hard plate made of metal. Next, a cylinder made of metal gradually descends toward the golf ball 2 . The golf ball 2 , squeezed between the bottom face of the cylinder and the hard plate, becomes deformed. A migration distance of the cylinder, starting from the state in which an initial load of 98 N is applied to the golf ball 2 up to the state in which a final load of 1274 N is applied thereto, is measured. A moving speed of the cylinder until the initial load is applied is 0.83 mm/s. A moving speed of the cylinder after the initial load is applied until the final load is applied is 1.67 mm/s.
- a value Vb calculated by the following mathematical formula exceeds 620 and is less than 900.
- the golf ball 2 meets the following mathematical formula (4).
- the golf ball 2 having a value Vb of exceeding 620 and less than 900, both desired flight performance and desired controllability are achieved.
- the golf ball 2 more preferably meets the following mathematical formula.
- the mathematical formula (4) can be met.
- each dimple 12 is circular.
- the golf ball 2 has dimples A each having a diameter of 4.50 mm; dimples B each having a diameter of 4.40 mm; dimples C each having a diameter of 4.30 mm; dimples D each having a diameter of 4.20 mm; and dimples E each having a diameter of 3.00 mm.
- the number of types of the dimples 12 is five.
- the golf ball 2 may have non-circular dimples instead of the circular dimples 12 or together with circular dimples 12 .
- the number of the dimples A is 80; the number of the dimples B is 74; the number of the dimples C is 62; the number of the dimples D is 96; and the number of the dimples E is 12.
- the total number of the dimples 12 is 324.
- a dimple pattern is formed by these dimples 12 and the land 14 .
- FIG. 8 shows a cross section of the golf ball 2 along a plane passing through the central point of the dimple 12 and the central point of the golf ball 2 .
- the top-to-bottom direction is the depth direction of the dimple 12 .
- a chain double-dashed line 16 indicates a phantom sphere.
- the surface of the phantom sphere 16 is the surface of the golf ball 2 when it is postulated that no dimple 12 exists.
- the diameter of the phantom sphere 16 is equal to the diameter of the golf ball 2 .
- the dimple 12 is recessed from the surface of the phantom sphere 16 .
- the land 14 coincides with the surface of the phantom sphere 16 .
- the cross-sectional shape of each dimple 12 is substantially a circular arc.
- the cross-sectional shape may be a curved line of which the curvature changes.
- an arrow Dm indicates the diameter of the dimple 12 .
- the diameter Dm is the distance between two tangent points Ed appearing on a tangent line Tg that is drawn tangent to the far opposite ends of the dimple 12 .
- Each tangent point Ed is also the edge of the dimple 12 .
- the edge Ed defines the contour of the dimple 12 .
- a double ended arrow Dp1 indicates a first depth of the dimple 12 .
- the first depth Dp1 is the distance between the deepest part of the dimple 12 and the surface of the phantom sphere 16 .
- a double ended arrow Dp2 indicates a second depth of the dimple 12 .
- the second depth Dp2 is the distance between the deepest part of the dimple 12 and the tangent line Tg.
- the diameter Dm of each dimple 12 is preferably equal to or greater than 2.0 mm but equal to or less than 6.0 mm.
- the dimple 12 having a diameter Dm of equal to or greater than 2.0 mm contributes to turbulization.
- the diameter Dm is more preferably equal to or greater than 2.5 mm and particularly preferably equal to or greater than 2.8 mm.
- the dimple 12 having a diameter Dm of equal to or less than 6.0 mm does not impair a fundamental feature of the golf ball 2 being substantially a sphere.
- the diameter Dm is more preferably equal to or less than 5.5 mm and particularly preferably equal to or less than 5.0 mm.
- the first depth Dp1 of each dimple 12 is preferably equal to or greater than 0.10 mm, more preferably equal to or greater than 0.13 mm, and particularly preferably equal to or greater than 0.15 mm.
- the first depth Dp1 is preferably equal to or less than 0.65 mm, more preferably equal to or less than 0.60 mm, and particularly preferably equal to or less than 0.55 mm.
- the area S of the dimple 12 is the area of a region surrounded by the contour line of the dimple 12 when the central point of the golf ball 2 is viewed at infinity. In the case of a circular dimple 12 , the area S is calculated by the following mathematical formula.
- each dimple A is 15.9 mm 2 ; the area of each dimple B is 15.2 mm 2 ; the area of each dimple C is 14.5 mm 2 ; the area of each dimple D is 13.9 mm 2 ; and the area of each dimple E is 7.1 mm 2 .
- the ratio of the sum of the areas S of all the dimples 12 relative to the surface area of the phantom sphere 16 is referred to as an occupation ratio.
- the occupation ratio is preferably equal to or greater than 80%, more preferably equal to or greater than 81%, and particularly preferably equal to or greater than 82%.
- the occupation ratio is preferably equal to or less than 95%.
- the total area of the dimples 12 is 4712.8 mm 2 .
- the surface area of the phantom sphere 16 of the golf ball 2 is 5728.0 mm 2 , so that the occupation ratio is 82.3%.
- the total number N of the dimples 12 is preferably equal to or greater than 250, more preferably equal to or greater than 280, and particularly preferably equal to or greater than 300. From the standpoint that each dimple 12 can contribute to turbulization, the total number N of the dimples 12 is preferably equal to or less than 450, more preferably equal to or less than 400, and particularly preferably equal to or less than 380.
- the “volume of the dimple” means the volume of a portion surrounded by the surface of the phantom sphere 16 and the surface of the dimple 12 .
- the total volume of all the dimples 12 is preferably equal to or greater than 450 mm 3 , more preferably equal to or greater than 480 mm 3 , and particularly preferably equal to or greater than 500 mm 3 .
- the total volume is preferably equal to or less than 750 mm 3 , more preferably equal to or less than 730 mm 3 , and particularly preferably equal to or less than 710 mm 3 .
- the dimples 12 each having an area of less than 8.0 mm 2 is referred to as “small dimples 12 S”.
- the dimples E are small dimples 12 S.
- the number NS of the small dimples 12 S is 12.
- the dimples 12 each having an area of equal to or greater than 8.0 mm 2 is referred to as “large dimples 12 L”.
- the dimples A to D are large dimples 12 L.
- the number NL of the large dimples 12 L is 312. The sum of the number NS and the number NL is equal to the total number N.
- bias of the land 14 tends to occur on the surface of the phantom sphere 16 .
- the bias is referred to as distortion.
- the small dimples 12 S suppresses distortion.
- the small dimples 12 S promote turbulization. With the golf ball 2 , a large flight distance is obtained upon a shot with a driver.
- the ratio PS of the sum of the areas of the small dimples 12 S relative to the surface area of the phantom sphere 16 is preferably equal to or greater than 0.7%, more preferably equal to or greater than 0.9%, and particularly preferably equal to or greater than 1.0%.
- the ratio PS is preferably less than 2.0%, more preferably equal to or less than 1.8%, and particularly preferably equal to or less than 1.7%.
- the ratio PS is 1.5%.
- the number NS of the small dimples 12 S is preferably equal to or greater than 6, more preferably equal to or greater than 8, and particularly preferably equal to or greater than 10.
- the number NS is preferably equal to or less than 20, more preferably equal to or less than 18, and particularly preferably equal to or less than 16.
- the ratio (NS/N) of the number NS of the small dimples 12 S relative to the total number N of the dimples 12 is preferably equal to or greater than 0.01, more preferably equal to or greater than 0.02, and particularly preferably equal to or greater than 0.03.
- the ratio (NS/N) is preferably equal to or less than 0.07, more preferably equal to or less than 0.06, and particularly preferably equal to or less than 0.05.
- the ratio (NS/N) is 0.04.
- the presence of the small dimples 12 S is essential. Meanwhile, the degree of contribution of the small dimples 12 S to turbulization is lower than that of the large dimples 12 L.
- the dimple pattern in which an appropriate number of small dimples 12 S are present and a sufficient number of large dimples 12 L are present has excellent flight performance.
- the ratio PL of the sum of the areas of the large dimples 12 L relative to the surface area of the phantom sphere 16 is preferably equal to or greater than 79.0%, more preferably equal to or greater than 79.5%, and particularly preferably equal to or greater than 80.0%.
- the ratio PL is preferably equal to or less than 90%. In the golf ball 2 shown in FIGS. 2 to 7 , the ratio PL is 80.8%.
- a degree of uniformity G of the areas of the large dimples 12 L is preferably equal to or less than 1.15, more preferably equal to or less than 1.10, and particularly preferably equal to or less than 1.05.
- the degree of uniformity G is preferably equal to or greater than 0.50.
- the degree of uniformity G is the standard deviation of the areas (mm 2 ) of the large dimples 12 L. In the golf ball 2 shown in FIGS. 2 to 7 , the average of the areas of the large dimples 12 L is 14.9 mm 2 .
- the degree of uniformity G of the golf ball 2 is calculated on the basis of the following mathematical formula.
- the degree of uniformity G of the golf ball 2 is 0.801.
- a rubber composition (b) was obtained by kneading 100 parts by weight of a high-cis polybutadiene (trade name “BR-730”, manufactured by JSR Corporation), 26.0 parts by weight of zinc diacrylate, 5 parts by weight of zinc oxide, an appropriate amount of barium sulfate, 0.5 parts by weight of diphenyl disulfide, and 0.7 parts by weight of dicumyl peroxide.
- This rubber composition (b) was placed into a mold that includes upper and lower mold halves each having a hemispherical cavity, and heated at 170° C. for 15 minutes to obtain an inner core with a diameter D1 of 24 mm. The amount of barium sulfate was adjusted such that a predetermined ball weight is obtained.
- a rubber composition (d) was obtained by kneading 100 parts by weight of a high-cis polybutadiene (trade name “BR-730”, manufactured by JSR Corporation), 41.5 parts by weight of zinc diacrylate, 5 parts by weight of zinc oxide, an appropriate amount of barium sulfate, 0.1 parts by weight of an antioxidant (H-BHT), 0.5 parts by weight of diphenyl disulfide, and 0.7 parts by weight of dicumyl peroxide.
- Half shells were formed from this rubber composition (d). The inner core was covered with two of these half shells.
- the inner core and the half shells were placed into a mold that includes upper and lower mold halves each having a hemispherical cavity, and a core consisting of the inner core and an outer core was formed by a first crosslinking process and a second crosslinking process.
- the crosslinking temperature was 140° C.
- the crosslinking time period was 20 minutes.
- the crosslinking temperature was 160° C.
- the crosslinking time period was 10 minutes.
- the diameter of the core was 38.5 mm.
- a resin composition (M2) was obtained by kneading 50 parts by weight of an ionomer resin (the aforementioned “Surlyn 8150”), 50 parts by weight of another ionomer resin (the aforementioned “Himilan AM7329”), and 4 parts by weight of titanium dioxide with a twin-screw kneading extruder.
- the core was covered with this resin composition (M2) by injection molding to form a mid layer with a thickness of 1.6 mm.
- a paint composition (trade name “POLIN 750LE”, manufactured by SHINTO PAINT CO., LTD.) including a two-component curing type epoxy resin as a base polymer was prepared.
- the base material liquid of this paint composition includes 30 parts by weight of a bisphenol A type epoxy resin and 70 parts by weight of a solvent.
- the curing agent liquid of this paint composition includes 40 parts by weight of a modified polyamide amine, 55 parts by weight of a solvent, and 5 parts by weight of titanium dioxide.
- the weight ratio of the base material liquid to the curing agent liquid is 1/1.
- This paint composition was applied to the surface of the mid layer with a spray gun, and kept at 23° C. for 12 hours to obtain a reinforcing layer with a thickness of 10 ⁇ m.
- a resin composition (C2) was obtained by kneading 100 parts by weight of a thermoplastic polyurethane elastomer (the aforementioned “Elastollan NY84A”), 0.2 parts by weight of a light stabilizer (trade name “TINUVIN 770”), 4 parts by weight of titanium dioxide, and 0.04 parts by weight of ultramarine blue with a twin-screw kneading extruder.
- Half shells were obtained from this resin composition (C2) by compression molding. The sphere consisting of the inner core, the outer core, the mid layer, and the reinforcing layer was covered with two of the half shells.
- FIG. 9 is a front view of this golf ball
- FIG. 10 is a plan view of this golf ball.
- Examples 2 to 9 and Comparative Examples 1 to 7 were obtained in the same manner as Example 1, except the specifications of the inner core, the outer core, the mid layer, the cover, and the dimples were as shown in Tables 7 to 10 below.
- the specifications of the inner core and the outer core are shown in detail in Tables 1 and 2 below.
- the specifications of the mid layer are shown in detail in Table 3 below.
- the specifications of the cover are shown in detail in Table 4 below.
- the specifications of the dimples are shown in detail in Tables 5 and 6 below.
- the dimple pattern of the golf ball according to Comparative Example 3 is the same as the dimple pattern of the golf ball according to Comparative Example 4 in JP2006-20820.
- the dimple pattern of the golf ball according to Comparative Example 4 is the same as the dimple pattern of the golf ball according to Example 2 in JP2005-137692.
- a driver (trade name “Z745”, manufactured by DUNLOP SPORTS CO. LTD., shaft hardness: S, loft angle: 8.5°) was attached to a swing machine manufactured by Golf Laboratories, Inc.
- a golf ball was hit under a condition of a head speed of 50 m/sec, and the initial speed, the spin rate, and the flight distance of the golf ball were measured.
- the flight distance is the distance between the point at the hit and the point at which the ball stopped.
- Tables 7 to 10 The average value of data obtained by 12 measurements is shown in Tables 7 to 10 below.
- FIG. 9 Plan view FIG. 4
- FIG. 10 Number 324 338 270 372 Occupation ratio (%) 82.3 82.0 78.8 84.6 Total volume (mm 3 ) 576 562 599 552 NS 12 12 12 18 NL 312 326 258 354 PS (%) 1.5 1.5 1.6 1.6 PL (%) 80.8 80.5 77.2 83.0 G 0.801 0.946 2.343 1.816
- the golf ball of each Example has excellent flight performance upon a shot with a driver. From the results of evaluation, advantages of the present invention are clear.
- the golf ball according to the present invention is suitable for, for example, playing golf on golf courses and practicing at driving ranges.
- the above descriptions are merely illustrative examples, and various modifications can be made without departing from the principles of the present invention.
Abstract
1.0<V2/V1<7.0
De2−De1<0
600<(H1o*H1in)*(D1/2)/2<1000
620<Tc*Hc*Hm/Tm<900
Description
- This application claims priority on Patent Application No. 2015-251371 filed in JAPAN on Dec. 24, 2015. The entire contents of this Japanese Patent Application are hereby incorporated by reference.
- Field of the Invention
- The present invention relates to golf balls. Specifically, the present invention relates to golf balls that include a core having a two-layer structure, a mid layer, and a cover and further have a plurality of dimples on the surface thereof.
- Description of the Related Art
- The greatest interest to golf players concerning golf balls is flight distance. In particular, golf players place importance on flight distances upon shots with a driver. The initial speed, the spin rate, and the launch angle of a golf ball when the golf ball is hit with a golf club are referred to as three initial elements. The flight distance of the golf ball is influenced by the three initial elements. The higher the initial speed of the ball is, the larger the flight distance is. An appropriate spin rate and an appropriate launch angle also contribute to flight distance.
- There are various proposals for improvement of flight performance that focuses on the three initial elements. JPH11-206920 discloses a golf ball including an inner core and an outer core. Such golf balls having two core layers are also disclosed in JP2003-190331 (US2003/0130065), JP2006-289065 (US2006/0229143), JP2007-190382 (US2007/0259739), JPH10-328326 (U.S. Pat. No. 6,468,169), JPH10-328328 (U.S. Pat. No. 6,248,027), JP2000-60997 (U.S. Pat. No. 6,251,031), and JP2009-219871 (US2008/0161132).
- Golf balls have a large number of dimples on the surfaces thereof. The dimples disturb the air flow around the golf ball during flight to cause turbulent flow separation. This phenomenon is referred to as “turbulization”. Due to the turbulization, separation points of the air from the golf ball shift backwards leading to a reduction of drag. The turbulization promotes the displacement between the separation point on the upper side and the separation point on the lower side of the golf ball, which results from the backspin, thereby enhancing the lift force that acts upon the golf ball. Excellent dimples efficiently disturb the air flow. The excellent dimples produce a long flight distance.
- There have been various proposals for dimples. JP2009-172192 (US2009/0191982) discloses a golf ball on which dimples are randomly arranged. The dimple pattern of the golf ball is referred to as a random pattern. The random pattern can contribute to the flight performance of the golf ball. JP2012-10822 (US2012/0004053) also discloses a golf ball having a random pattern.
- JP2007-175267 (US2007/0149321) discloses a dimple pattern in which the number of units in a high-latitude region is different from the number of units in a low-latitude region. JP2007-195591 (US2007/0173354) discloses a dimple pattern in which the number of the types of dimples in a low-latitude region is larger than the number of the types of dimples in a high-latitude region. JP2013-153966 (US2013/0196791) discloses a dimple pattern having a high dimple density and small variation in dimple size.
- Golf players' requirements for flight distance have been escalated. An object of the present invention is to provide a golf ball having excellent flight performance upon hitting with a driver.
- A golf ball according to the present invention includes an inner core, an outer core positioned outside the inner core, a mid layer positioned outside the outer core, and a cover positioned outside the mid layer. A diameter D1 (mm), a volume V1 (mm3), a hardness H1o (Shore C) at a central point, a boundary inside hardness H1in (Shore C), and a difference De1 between the hardness H1in and the hardness H1o of the inner core; a volume V2 (mm3) and a difference De2 between a surface hardness H2s (Shore C) and a boundary outside hardness H2out (Shore C) of the outer core; a thickness Tm (mm) and a hardness Hm (Shore D) of the mid layer; and a thickness Tc (mm) and a hardness Hc (Shore D) of the cover meets the following mathematical formulas (1) to (4).
-
1.0<V2/V1<7.0 (1) -
De2−De1<0 (2) -
600<(H1o+H1in)*(D1/2)/2<1000 (3) -
620<Tc*Hc*Hm/Tm<900 (4) - The golf ball has a plurality of dimples on a surface thereof. The dimples include a plurality of small dimples each having an area of less than 8.0 mm2 and a plurality of large dimples each having an area of equal to or greater than 8.0 mm2. A ratio PS of a sum of the areas of the small dimples relative to a surface area of a phantom sphere of the golf ball is less than 2.0%. A ratio PL of a sum of the areas of the large dimples relative to the surface area of the phantom sphere is equal to or greater than 79.0%. A degree of uniformity G of the areas (mm2) of the large dimples is equal to or less than 1.15.
- When the golf ball according to the present invention is hit with a driver, the spin rate is low, and the initial speed of the ball is high. Furthermore, with the golf ball, turbulization is promoted by the dimples. By the appropriate three initial elements and the appropriate aerodynamic characteristic, with the golf ball, a large flight distance is obtained upon a shot with a driver.
- Preferably, the golf ball meets the following mathematical formula.
-
2.0<V2/V1<6.0 - Preferably, the golf ball meets the following mathematical formula.
-
700<(H1o+H1in)*(D1/2)/2<900 - Preferably, the golf ball meets the following mathematical formula.
-
640<Tc*Hc*Hm/Tm<800 - Preferably, the ratio PS is equal to or greater than 0.7%. Preferably, a number NS of the small dimples is equal to or greater than 6 but equal to or less than 20. Preferably, a ratio (NS/N) of a number NS of the small dimples relative to a total number N of the dimples is equal to or greater than 0.01 but equal to or less than 0.07.
- Preferably, a depth of a deepest part of each dimple from a surface of the phantom sphere is equal to or greater than 0.10 mm but equal to or less than 0.65 mm.
- Preferably, a total volume of the dimples is equal to or greater than 450 mm3 but equal to or less than 750 mm3.
- Preferably, the ratio PL is equal to or greater than 79.5%, and the degree of uniformity G is equal to or less than 1.10.
- Preferably, the ratio PL is equal to or greater than 80.0%, and the degree of uniformity G is equal to or less than 1.05.
-
FIG. 1 is a cross-sectional view of a golf ball according to one embodiment of the present invention; -
FIG. 2 is an enlarged front view of the golf ball inFIG. 1 ; -
FIG. 3 is a back view of the golf ball inFIG. 2 ; -
FIG. 4 is a plan view of the golf ball inFIG. 2 ; -
FIG. 5 is a bottom view of the golf ball inFIG. 2 ; -
FIG. 6 is a left side view of the golf ball inFIG. 2 ; -
FIG. 7 is a right side view of the golf ball inFIG. 2 ; -
FIG. 8 is a partially enlarged cross-sectional view of the golf ball inFIG. 1 ; -
FIG. 9 is a front view of a golf ball according to Example 1 of the present invention; and -
FIG. 10 is a plan view of the golf ball inFIG. 9 . - The following will describe in detail the present invention based on preferred embodiments with appropriate reference to the drawings.
- A
golf ball 2 shown inFIG. 1 includes a sphericalinner core 4, anouter core 6 positioned outside theinner core 4, amid layer 8 positioned outside theouter core 6, and acover 10 positioned outside themid layer 8. Thegolf ball 2 has a plurality ofdimples 12 on the surface thereof. Of the surface of thegolf ball 2, a part other than thedimples 12 is aland 14. Thegolf ball 2 includes a paint layer and a mark layer on the external side of thecover 10 although these layers are not shown in the drawing. Thegolf ball 2 may include another layer between theouter core 6 and themid layer 8. Thegolf ball 2 may include another layer between themid layer 8 and thecover 10. - The
golf ball 2 preferably has a diameter of equal to or greater than 40 mm but equal to or less than 45 mm. From the standpoint of conformity to the rules established by the United States Golf Association (USGA), the diameter is particularly preferably equal to or greater than 42.67 mm. In light of suppression of air resistance, the diameter is more preferably equal to or less than 44 mm and particularly preferably equal to or less than 42.80 mm. Thegolf ball 2 preferably has a weight of equal to or greater than 40 g but equal to or less than 50 g. In light of attainment of great inertia, the weight is more preferably equal to or greater than 44 g and particularly preferably equal to or greater than 45.00 g. From the standpoint of conformity to the rules established by the USGA, the weight is particularly preferably equal to or less than 45.93 g. - The
inner core 4 is formed by crosslinking a rubber composition. Examples of preferable base rubbers for use in the rubber composition include polybutadienes, polyisoprenes, styrene-butadiene copolymers, ethylene-propylene-diene copolymers, and natural rubbers. In light of high initial speed of the ball, polybutadienes are preferable. When a polybutadiene and another rubber are used in combination, it is preferred if the polybutadiene is a principal component. Specifically, the proportion of the polybutadiene to the entire base rubber is preferably equal to or greater than 50% by weight and particularly preferably equal to or greater than 80% by weight. A polybutadiene in which the proportion of cis-1,4 bonds is equal to or greater than 80% is particularly preferable. - The rubber composition of the
inner core 4 preferably includes a co-crosslinking agent. Preferable co-crosslinking agents in light of high initial speed of the ball are monovalent or bivalent metal salts of an α,β-unsaturated carboxylic acid having 2 to 8 carbon atoms. Examples of preferable co-crosslinking agents include zinc acrylate, magnesium acrylate, zinc methacrylate, and magnesium methacrylate. In light of resilience performance, zinc acrylate and zinc methacrylate are particularly preferable. - The rubber composition may include a metal oxide and an α,β-unsaturated carboxylic acid having 2 to 8 carbon atoms. They both react with each other in the rubber composition to obtain a salt. The salt serves as a co-crosslinking agent. Examples of preferable α,β-unsaturated carboxylic acids include acrylic acid and methacrylic acid. Examples of preferable metal oxides include zinc oxide and magnesium oxide.
- In light of high initial speed of the ball, the amount of the co-crosslinking agent per 100 parts by weight of the base rubber is preferably equal to or greater than 10 parts by weight and particularly preferably equal to or greater than 15 parts by weight. In light of low spin rate upon a shot with a driver, this amount is preferably equal to or less than 40 parts by weight and particularly preferably equal to or less than 35 parts by weight. As described in detail later, a low spin rate can achieve a large flight distance upon a shot with a driver.
- Preferably, the rubber composition of the
inner core 4 includes an organic peroxide. The organic peroxide serves as a crosslinking initiator. The organic peroxide contributes to the resilience performance of thegolf ball 2. Examples of suitable organic peroxides include dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and di-t-butyl peroxide. An organic peroxide with particularly high versatility is dicumyl peroxide. - In light of high initial speed of the ball, the amount of the organic peroxide per 100 parts by weight of the base rubber is preferably equal to or greater than 0.1 parts by weight, more preferably equal to or greater than 0.3 parts by weight, and particularly preferably equal to or greater than 0.5 parts by weight. In light of low spin rate, this amount is preferably equal to or less than 3.0 parts by weight, more preferably equal to or less than 2.8 parts by weight, and particularly preferably equal to or less than 2.5 parts by weight.
- Preferably, the rubber composition of the
inner core 4 includes an organic sulfur compound. Organic sulfur compounds include naphthalenethiol compounds, benzenethiol compounds, and disulfide compounds. - Examples of naphthalenethiol compounds include 1-naphthalenethiol, 2-naphthalenethiol, 4-chloro-1-naphthalenethiol, 4-bromo-1-naphthalenethiol, 1-chloro-2-naphthalenethiol, 1-bromo-2-naphthalenethiol, 1-fluoro-2-naphthalenethiol, 1-cyano-2-naphthalenethiol, and 1-acetyl-2-naphthalenethiol.
- Examples of benzenethiol compounds include benzenethiol, 4-chlorobenzenethiol, 3-chlorobenzenethiol, 4-bromobenzenethiol, 3-bromobenzenethiol, 4-fluorobenzenethiol, 4-iodobenzenethiol, 2,5-dichlorobenzenethiol, 3,5-dichlorobenzenethiol, 2,6-dichlorobenzenethiol, 2,5-dibromobenzenethiol, 3,5-dibromobenzenethiol, 2-chloro-5-bromobenzenethiol, 2,4,6-trichlorobenzenethiol, 2,3,4,5,6-pentachlorobenzenethiol, 2,3,4,5,6-pentafluorobenzenethiol, 4-cyanobenzenethiol, 2-cyanobenzenethiol, 4-nitrobenzenethiol, and 2-nitrobenzenethiol.
- Examples of disulfide compounds include diphenyl disulfide, bis(4-chlorophenyl)disulfide, bis(3-chlorophenyl)disulfide, bis(4-bromophenyl)disulfide, bis(3-bromophenyl)disulfide, bis(4-fluorophenyl)disulfide, bis(4-iodophenyl)disulfide, bis(4-cyanophenyl)disulfide, bis(2,5-dichlorophenyl)disulfide, bis(3,5-dichlorophenyl)disulfide, bis(2,6-dichlorophenyl)disulfide, bis(2,5-dibromophenyl)disulfide, bis(3,5-dibromophenyl)disulfide, bis(2-chloro-5-bromophenyl)disulfide, bis(2-cyano-5-bromophenyl)disulfide, bis(2,4,6-trichlorophenyl)disulfide, bis(2-cyano-4-chloro-6-bromophenyl)disulfide, bis(2,3,5,6-tetrachlorophenyl)disulfide, bis(2,3,4,5,6-pentachlorophenyl)disulfide, and bis(2,3,4,5,6-pentabromophenyl)disulfide.
- In light of high initial speed of the ball, the amount of the organic sulfur compound per 100 parts by weight of the base rubber is preferably equal to or greater than 0.1 parts by weight and particularly preferably equal to or greater than 0.2 parts by weight. In light of low spin rate, this amount is preferably equal to or less than 1.5 parts by weight, more preferably equal to or less than 1.0 parts by weight, and particularly preferably equal to or less than 0.8 parts by weight. Two or more organic sulfur compounds may be used in combination.
- The rubber composition of the
inner core 4 may include a filler for the purpose of specific gravity adjustment and the like. Examples of suitable fillers include zinc oxide, barium sulfate, calcium carbonate, and magnesium carbonate. The amount of the filler is determined as appropriate so that the intended specific gravity of theinner core 4 is accomplished. The rubber composition may include various additives, such as sulfur, a carboxylic acid, a carboxylate, an anti-aging agent, a coloring agent, a plasticizer, a dispersant, and the like, in an adequate amount. The rubber composition may include crosslinked rubber powder or synthetic resin powder. - The
inner core 4 preferably has a diameter D1 of equal to or greater than 15.0 mm. With thegolf ball 2 that includes theinner core 4 having a diameter D1 of equal to or greater than 15.0 mm, spin upon a shot with a driver is suppressed. In this respect, the diameter D1 is more preferably equal to or greater than 18.0 mm and particularly preferably equal to or greater than 20.0 mm. From the standpoint that theouter core 6 can have a sufficient thickness, the diameter D1 is preferably equal to or less than 32.0 mm, more preferably equal to or less than 29.0 mm, and particularly preferably equal to or less than 27.0 mm. - The
inner core 4 preferably has a volume V1 of equal to or greater than 1700 mm3. With thegolf ball 2 that includes theinner core 4 having a volume V1 of equal to or greater than 1700 mm3, spin upon a shot with a driver is suppressed. In this respect, the volume V1 is more preferably equal to or greater than 3000 mm3 and particularly preferably equal to or greater than 4200 mm3. From the standpoint that theouter core 6 can have a sufficient volume V2, the volume V1 is preferably equal to or less than 17000 mm3, more preferably equal to or less than 13000 mm3, and particularly preferably equal to or less than 10300 mm3. - The
inner core 4 has a weight of preferably equal to or greater than 10 g but equal to or less than 30 g. The temperature for crosslinking theinner core 4 is equal to or higher than 140° C. but equal to or lower than 180° C. The time period for crosslinking theinner core 4 is equal to or longer than 10 minutes but equal to or shorter than 60 minutes. - In the
golf ball 2, the difference De1 between a hardness H1o at the central point of theinner core 4 and a boundary inside hardness H1in of theinner core 4 is great. Theinner core 4 having the great difference De1 has a so-called outer-hard/inner-soft structure. When thegolf ball 2 including theinner core 4 is hit with a driver, the spin rate is low. When thegolf ball 2 including theinner core 4 is hit with a driver, a high launch angle is obtained. - Upon a shot with a driver, an appropriate trajectory height and appropriate flight duration are required. With the
golf ball 2 that achieves a desired trajectory height and desired flight duration at a high spin rate, the run after landing is short. With thegolf ball 2 that achieves a desired trajectory height and desired flight duration at a high launch angle, the run after landing is long. In light of flight distance, thegolf ball 2 that achieves a desired trajectory height and desired flight duration at a high launch angle is preferable. Theinner core 4 having an outer-hard/inner-soft structure can contribute to a high launch angle and a low spin rate as described above. Thegolf ball 2 including theinner core 4 has excellent flight performance. - In light of flight performance, the difference De1 is preferably equal to or greater than 5, more preferably equal to or greater than 8, and particularly preferably equal to or greater than 10. In light of ease of producing the
inner core 4, the difference De1 is preferably equal to or less than 40 and particularly preferably equal to or less than 30. Preferably, in theinner core 4, the hardness gradually increases from the central point thereof toward the surface thereof. - In light of high initial speed of the ball, the central hardness H1o is preferably equal to or greater than 40, more preferably equal to or greater than 45, and particularly preferably equal to or greater than 50. In light of low spin rate, the hardness H1o is preferably equal to or less than 80, more preferably equal to or less than 75, and particularly preferably equal to or less than 70.
- The hardness H1o is measured with a Shore C type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss Prüfgerätebau GmbH). The hardness scale is pressed against the central point of the cross-section of a hemisphere obtained by cutting the
golf ball 2. The measurement is conducted in the environment of 23° C. - In light of low spin rate, the boundary inside hardness H1in is preferably equal to or greater than 60, more preferably equal to or greater than 65, and particularly preferably equal to or greater than 70. In light of durability of the
golf ball 2, the hardness H1in is preferably equal to or less than 85, more preferably equal to or less than 80, and particularly preferably equal to or less than 78. - The hardness H1in is measured with a Shore C type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss Prüfgerätebau GmbH). The hardness scale is pressed against a cross-section of the
golf ball 2 that has been cut into two halves. The hardness scale is pressed against a point separated by 1 mm radially inward from the boundary between theinner core 4 and theouter core 6. The measurement is conducted in the environment of 23° C. - In the
inner core 4, a value Va calculated by the following mathematical formula exceeds 600 and is less than 1000. -
Va=(H1o+H1in)*(D1/2)/2 - In other words, the
inner core 4 meets the following mathematical formula (3). -
600<(H1o+H1in)*(D1/2)/2<1000 (3) - The value Va is approximate to the integral of a hardness distribution of the
inner core 4. With thegolf ball 2 that includes theinner core 4 having a value Va of exceeding 600, the spin rate upon a shot with a driver is low. With thegolf ball 2 that includes theinner core 4 having a value Va of less than 1000, the initial speed of the ball upon a shot with a driver is high. The low spin rate and the high initial speed of the ball achieve a large flight distance. In this respect, thegolf ball 2 more preferably meets the following mathematical formula. -
700<(H1o+H1in)*(D1/2)/2<900 - In other words, the value Va preferably exceeds 700 and is less than 900.
- The
outer core 6 is formed by crosslinking a rubber composition. The composition can include the base rubber described above for theinner core 4. - The rubber composition of the
outer core 6 preferably includes a co-crosslinking agent. Preferable co-crosslinking agents in light of high initial speed of the ball are monovalent or bivalent metal salts of an α,β-unsaturated carboxylic acid having 2 to 8 carbon atoms. Examples of preferable co-crosslinking agents include zinc acrylate, magnesium acrylate, zinc methacrylate, and magnesium methacrylate. In light of high initial speed of the ball, zinc acrylate and zinc methacrylate are particularly preferable. - The rubber composition may include a metal oxide and an α,β-unsaturated carboxylic acid having 2 to 8 carbon atoms. They both react with each other in the rubber composition to obtain a salt. The salt serves as a co-crosslinking agent. Examples of preferable α,β-unsaturated carboxylic acids include acrylic acid and methacrylic acid. Examples of preferable metal oxides include zinc oxide and magnesium oxide.
- In light of high initial speed of the ball, the amount of the co-crosslinking agent per 100 parts by weight of the base rubber is preferably equal to or greater than 25 parts by weight, more preferably equal to or greater than 30 parts by weight, and particularly preferably equal to or greater than 35 parts by weight. In light of feel at impact, this amount is preferably equal to or less than 55 parts by weight, more preferably equal to or less than 50 parts by weight, and particularly preferably equal to or less than 45 parts by weight.
- Preferably, the rubber composition of the
outer core 6 includes an organic peroxide. The organic peroxide serves as a crosslinking initiator. The organic peroxide contributes to the resilience performance of thegolf ball 2. The rubber composition of theouter core 6 can include the organic peroxide described above for theinner core 4. - In light of high initial speed of the ball, the amount of the organic peroxide per 100 parts by weight of the base rubber is preferably equal to or greater than 0.1 parts by weight, more preferably equal to or greater than 0.3 parts by weight, and particularly preferably equal to or greater than 0.5 parts by weight. In light of feel at impact, this amount is preferably equal to or less than 3.0 parts by weight, more preferably equal to or less than 2.8 parts by weight, and particularly preferably equal to or less than 2.5 parts by weight.
- Preferably, the rubber composition of the
outer core 6 includes an organic sulfur compound. The rubber composition can include the organic sulfur compound described above for theinner core 4. - In light of high initial speed of the ball, the amount of the organic sulfur compound per 100 parts by weight of the base rubber is preferably equal to or greater than 0.1 parts by weight and particularly preferably equal to or greater than 0.2 parts by weight. In light of feel at impact, this amount is preferably equal to or less than 1.5 parts by weight, more preferably equal to or less than 1.0 parts by weight, and particularly preferably equal to or less than 0.8 parts by weight.
- The rubber composition of the
outer core 6 may include a filler for the purpose of specific gravity adjustment and the like. Examples of suitable fillers include zinc oxide, barium sulfate, calcium carbonate, and magnesium carbonate. The amount of the filler is determined as appropriate so that the intended specific gravity of theouter core 6 is accomplished. The rubber composition may include various additives, such as sulfur, a carboxylic acid, a carboxylate, an anti-aging agent, a coloring agent, a plasticizer, a dispersant, and the like, in an adequate amount. The rubber composition may include crosslinked rubber powder or synthetic resin powder. - The
outer core 6 preferably has a diameter D2 of equal to or greater than 37.0 mm. Thegolf ball 2 that includes theouter core 6 having a diameter D2 of equal to or greater than 37.0 mm has a high initial speed upon a shot with a driver. In this respect, the diameter D2 is more preferably equal to or greater than 37.5 mm and particularly preferably equal to or greater than 38.0 mm. From the standpoint that themid layer 8 and thecover 10 can have sufficient thicknesses, the diameter D2 is preferably equal to or less than 40.5 mm, more preferably equal to or less than 40.0 mm, and particularly preferably equal to or less than 39.5 mm. - The
outer core 6 preferably has a volume V2 of equal to or greater than 18000 mm3. Thegolf ball 2 that includes theouter core 6 having a volume V2 of equal to or greater than 18000 mm3 has a high initial speed upon a shot with a driver. In this respect, the volume V2 is more preferably equal to or greater than 19500 mm3 and particularly preferably equal to or greater than 21000 mm3. From the standpoint that themid layer 8 and thecover 10 can have sufficient thicknesses, the volume V2 is preferably equal to or less than 29000 mm3, more preferably equal to or less than 27000 mm3, and particularly preferably equal to or less than 26000 mm3. In the present embodiment, the volume V2 is calculated by subtracting the volume of theinner core 4 from the volume of a sphere consisting of theinner core 4 and theouter core 6. - The
outer core 6 has a weight of preferably equal to or greater than 10 g but equal to or less than 30 g. The temperature for crosslinking theouter core 6 is equal to or higher than 140° C. but equal to or lower than 180° C. The time period for crosslinking theouter core 6 is equal to or longer than 10 minutes but equal to or shorter than 60 minutes. - In the
golf ball 2, the difference De2 between a surface hardness H2s and a boundary outside hardness H2out of theouter core 6 is preferably equal to or greater than −2 but equal to or less than 2. A hardness distribution of theouter core 6 is close to being flat. In theouter core 6, the energy loss upon hitting with a driver is low. Thegolf ball 2 that includes theouter core 6 has a high initial speed upon a shot with a driver. Theouter core 6 can contribute to the flight performance of thegolf ball 2. In light of flight performance, the difference De2 is preferably equal to or greater than −1 but equal to or less than 1. The difference De2 may be zero. - The difference between a Shore C hardness at a point having a highest hardness and a Shore C hardness at a point having a lowest hardness in the zone from the boundary between the
inner core 4 and theouter core 6 to the surface of theouter core 6 is preferably equal to or less than 5, more preferably equal to or less than 4, and particularly preferably equal to or less than 3. - In light of high initial speed of the ball, the boundary outside hardness H2out is preferably equal to or greater than 60, more preferably equal to or greater than 70, and particularly preferably equal to or greater than 75. In light of feel at impact, the hardness H2out is preferably equal to or less than 90, more preferably equal to or less than 87, and particularly preferably equal to or less than 85.
- The hardness H2out is measured with a Shore C type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss Prüfgerätebau GmbH). The hardness scale is pressed against a cross-section of the
golf ball 2 that has been cut into two halves. The hardness scale is pressed against a point separated by 1 mm radially outward from the boundary between theinner core 4 and theouter core 6. The measurement is conducted in the environment of 23° C. - In light of spin suppression upon a shot with a driver, the surface hardness H2s is preferably equal to or greater than 70, more preferably equal to or greater than 72, and particularly preferably equal to or greater than 74. In light of durability of the
golf ball 2, the hardness H2s is preferably equal to or less than 90, more preferably equal to or less than 88, and particularly preferably equal to or less than 86. - The hardness H2s is measured with a Shore C type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss Prüfgerätebau GmbH). The hardness scale is pressed against the surface of the
outer core 6. The measurement is conducted in the environment of 23° C. - A core having a small difference De2 can be obtained by a two-stage crosslinking process. Specifically, in a first crosslinking process, a rubber composition is crosslinked at a predetermined temperature. In a second crosslinking process, the rubber composition is crosslinked at a temperature higher than the temperature in the first crosslinking process.
- The ratio (V2/V1) between the volume V2 of the
outer core 6 and the volume V1 of theinner core 4 meets the following mathematical formula (1). -
1.0<V2/V1<7.0 (1) - In other words, the ratio (V2/V1) exceeds 1.0 and is less than 7.0. The
golf ball 2 having a ratio (V2/V1) of exceeding 1.0 has a high initial speed upon a shot with a driver. Thegolf ball 2 having a ratio (V2/V1) of less than 7.0 has a low spin rate upon a shot with a driver. The high initial speed and the low spin rate of the ball achieve a large flight distance. In this respect, thegolf ball 2 more preferably meets the following mathematical formula. -
2.0<V2/V1<6.0 - The
golf ball 2 particularly preferably meets the following mathematical formula. -
2.5<V2/V1<5.0 - In the
golf ball 2, the hardness difference De2 in theouter core 6 and the hardness difference De1 in theinner core 4 meet the following mathematical formula (2). -
De2−De1<0 (2) - With the
golf ball 2 that meets the above mathematical formula, both a high initial speed and a low spin rate are achieved upon a shot with a driver. In this respect, thegolf ball 2 more preferably meets the following mathematical formula. -
De2−De1<−5 - The
golf ball 2 particularly preferably meets the following mathematical formula. -
De2−De1<−10 - The
mid layer 8 is positioned between theouter core 6 and thecover 10. Themid layer 8 is formed from a thermoplastic resin composition. Examples of the base polymer of the resin composition include ionomer resins, polyesters, polyamides, polyurethanes, polyolefins, and polystyrenes. Ionomer resins are particularly preferable. Ionomer resins are highly elastic. Thegolf ball 2 that includes themid layer 8 including an ionomer resin has excellent resilience performance upon a shot with a driver. - An ionomer resin and another resin may be used in combination. In this case, in light of resilience performance, the ionomer resin is included as the principal component of the base polymer. The proportion of the ionomer resin to the entire base polymer is preferably equal to or greater than 50% by weight, more preferably equal to or greater than 70% by weight, and particularly preferably equal to or greater than 85% by weight.
- Examples of preferable ionomer resins include binary copolymers formed with an α-olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms. A preferable binary copolymer includes 80% by weight or more but 90% by weight or less of an α-olefin, and 10% by weight or more but 20% by weight or less of an α,β-unsaturated carboxylic acid. The binary copolymer has excellent resilience performance. Examples of other preferable ionomer resins include ternary copolymers formed with: an α-olefin; an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms; and an α,β-unsaturated carboxylate ester having 2 to 22 carbon atoms. A preferable ternary copolymer includes 70% by weight or more but 85% by weight or less of an α-olefin, 5% by weight or more but 30% by weight or less of an α,β-unsaturated carboxylic acid, and 1% by weight or more but 25% by weight or less of an α,β-unsaturated carboxylate ester. The ternary copolymer has excellent resilience performance. For the binary copolymer and the ternary copolymer, preferable α-olefins are ethylene and propylene, while preferable α,β-unsaturated carboxylic acids are acrylic acid and methacrylic acid. A particularly preferable ionomer resin is a copolymer formed with ethylene and acrylic acid. Another particularly preferable ionomer resin is a copolymer formed with ethylene and methacrylic acid.
- In the binary copolymer and the ternary copolymer, some of the carboxyl groups are neutralized with metal ions. Examples of metal ions for use in neutralization include sodium ion, potassium ion, lithium ion, zinc ion, calcium ion, magnesium ion, aluminum ion, and neodymium ion. The neutralization may be carried out with two or more types of metal ions. Particularly suitable metal ions in light of resilience performance and durability of the
golf ball 2 are sodium ion, zinc ion, lithium ion, and magnesium ion. - Specific examples of ionomer resins include trade names “Himilan 1555”, “Himilan 1557”, “Himilan 1605”, “Himilan 1706”, “Himilan 1707”, “Himilan 1856”, “Himilan 1855”, “Himilan AM7311”, “Himilan AM7315”, “Himilan AM7317”, “Himilan AM7329”, and “Himilan AM7337”, manufactured by Du Pont-MITSUI POLYCHEMICALS Co., Ltd.; trade names “Surlyn 6120”, “Surlyn 6910”, “Surlyn 7930”, “Surlyn 7940”, “Surlyn 8140”, “Surlyn 8150”, “Surlyn 8940”, “Surlyn 8945”, “Surlyn 9120”, “Surlyn 9150”, “Surlyn 9910”, “Surlyn 9945”, “Surlyn AD8546”, “HPF1000”, and “HPF2000”, manufactured by E.I. du Pont de Nemours and Company; and trade names “IOTEK 7010”, “IOTEK 7030”, “IOTEK 7510”, “IOTEK 7520”, “IOTEK 8000”, and “IOTEK 8030”, manufactured by ExxonMobil Chemical Corporation. Two or more ionomer resins may be used in combination.
- The resin composition of the
mid layer 8 may include a styrene block-containing thermoplastic elastomer. The styrene block-containing thermoplastic elastomer includes a polystyrene block as a hard segment, and a soft segment. A typical soft segment is a diene block. Examples of compounds for the diene block include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. Butadiene and isoprene are preferable. Two or more compounds may be used in combination. - Examples of styrene block-containing thermoplastic elastomers include styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), styrene-isoprene-butadiene-styrene block copolymers (SIBS), hydrogenated SBS, hydrogenated SIS, and hydrogenated SIBS. Examples of hydrogenated SBS include styrene-ethylene-butylene-styrene block copolymers (SEBS). Examples of hydrogenated SIS include styrene-ethylene-propylene-styrene block copolymers (SEPS). Examples of hydrogenated SIBS include styrene-ethylene-ethylene-propylene-styrene block copolymers (SEEPS).
- In light of resilience performance of the
golf ball 2, the content of the styrene component in the styrene block-containing thermoplastic elastomer is preferably equal to or greater than 10% by weight, more preferably equal to or greater than 12% by weight, and particularly preferably equal to or greater than 15% by weight. In light of feel at impact, the content is preferably equal to or less than 50% by weight, more preferably equal to or less than 47% by weight, and particularly preferably equal to or less than 45% by weight. - In the present invention, styrene block-containing thermoplastic elastomers include an alloy of an olefin and one or more members selected from the group consisting of SBS, SIS, SIBS, SEBS, SEPS, and SEEPS. The olefin component in the alloy is presumed to contribute to improvement of compatibility with another base polymer. The alloy can contribute to the resilience performance of the
golf ball 2. An olefin having 2 to 10 carbon atoms is preferable. Examples of suitable olefins include ethylene, propylene, butene, and pentene. Ethylene and propylene are particularly preferable. - Specific examples of polymer alloys include trade names “RABALON T3221C”, “RABALON T3339C”, “RABALON SJ4400N”, “RABALON SJ5400N”, “RABALON SJ6400N”, “RABALON SJ7400N”, “RABALON SJ8400N”, “RABALON SJ9400N”, and “RABALON SR04”, manufactured by Mitsubishi Chemical Corporation. Other specific examples of styrene block-containing thermoplastic elastomers include trade name “Epofriend A1010” manufactured by Daicel Chemical Industries, Ltd., and trade name “SEPTON HG-252” manufactured by Kuraray Co., Ltd.
- In light of feel at impact, the proportion of the styrene block-containing thermoplastic elastomer to the entire base polymer is preferably equal to or greater than 1% by weight and particularly preferably equal to or greater than 2% by weight. In light of spin suppression upon a shot with a driver, the proportion is preferably equal to or less than 15% by weight, more preferably equal to or less than 10% by weight, and particularly preferably equal to or less than 5% by weight.
- The resin composition of the
mid layer 8 may include a polyamide. With thegolf ball 2 that includes themid layer 8 including a polyamide, the spin upon a shot with a driver is suppressed. Specific examples of polyamides includepolyamide 6, polyamide 11,polyamide 12, polyamide 66, and polyamide 610. In light of versatility,polyamide 6 is preferable. - In light of spin suppression, the proportion of the polyamide to the entire base polymer is preferably equal to or greater than 5% by weight, more preferably equal to or greater than 10% by weight, and particularly preferably equal to or greater than 15% by weight. In light of feel at impact, the proportion is preferably equal to or less than 50% by weight, more preferably equal to or less than 45% by weight, and particularly preferably equal to or less than 40% by weight.
- The resin composition of the
mid layer 8 may include a filler for the purpose of specific gravity adjustment and the like. Examples of suitable fillers include zinc oxide, barium sulfate, calcium carbonate, and magnesium carbonate. The resin composition may include powder of a metal with a high specific gravity. Specific examples of metals with a high specific gravity include tungsten and molybdenum. The amount of the filler is determined as appropriate so that the intended specific gravity of themid layer 8 is accomplished. The resin composition may include a coloring agent, crosslinked rubber powder, or synthetic resin powder. When the hue of thegolf ball 2 is white, a typical coloring agent is titanium dioxide. - The
mid layer 8 preferably has a hardness Hm of equal to or greater than 55. Thegolf ball 2 that includes themid layer 8 having a hardness Hm of equal to or greater than 55 has a low spin rate upon a shot with a driver. Themid layer 8 can contribute to the flight performance of thegolf ball 2. In this respect, the hardness Hm is more preferably equal to or greater than 58 and particularly preferably equal to or greater than 61. In light of feel at impact, the hardness Hm is preferably equal to or less than 80, more preferably equal to or less than 75, and particularly preferably equal to or less than 72. - The hardness Hm of the
mid layer 8 is measured according to the standards of “ASTM-D 2240-68”. The hardness Hm is measured with a Shore D type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss Prüfgerätebau GmbH). For the measurement, a sheet that is formed by hot press, is formed from the same material as that of themid layer 8, and has a thickness of about 2 mm is used. Prior to the measurement, a sheet is kept at 23° C. for two weeks. At the measurement, three sheets are stacked. - The
mid layer 8 has a thickness Tm of preferably equal to or greater than 0.3 mm but equal to or less than 2.5 mm. Thegolf ball 2 that includes amid layer 8 having a thickness Tm of equal to or greater than 0.3 mm has a low spin rate upon a shot with a driver. In this respect, the thickness Tm is more preferably equal to or greater than 0.5 mm and particularly preferably equal to or greater than 0.8 mm. Thegolf ball 2 that includes themid layer 8 having a thickness Tm of equal to or less than 2.5 mm has excellent feel at impact. In this respect, the thickness Tm is more preferably equal to or less than 2.0 mm and particularly preferably equal to or less than 1.8 mm. The thickness Tm is measured at a position immediately below theland 14. - The
golf ball 2 may include two or moremid layers 8 positioned between theouter core 6 and thecover 10. In this case, the thickness of eachmid layer 8 preferably falls within the above range. - The
cover 10 is the outermost layer except the mark layer and the paint layer. Thecover 10 is formed from a resin composition. Examples of the base polymer of the resin composition include polyurethanes, ionomer resins, polyesters, polyamides, polyolefins, and polystyrenes. A preferable base polymer in light of controllability upon hitting with a short iron is a polyurethane. When a polyurethane and another resin are used in combination for thecover 10, the proportion of the polyurethane to the entire base polymer is preferably equal to or greater than 50% by weight, more preferably equal to or greater than 60% by weight, and particularly preferably equal to or greater than 70% by weight. - The polyurethane has a urethane bond within the molecule. The urethane bond can be formed by reacting a polyol with a polyisocyanate. In addition to the reaction for the urethane bond, a chain-lengthening reaction may be carried out. The chain-lengthening reaction can be carried out by a polyamine or a polyol having a low molecular weight.
- Examples of the polyurethane include
- (A1) a polyurethane including a polyisocyanate component and a high-molecular-weight polyol component,
- (A2) a polyurethane including a polyisocyanate component, a high-molecular-weight polyol component, and a low-molecular-weight polyol,
- (A3) a polyurethane including a polyisocyanate component, a high-molecular-weight polyol component, and a polyamine component, and
- (A4) a polyurethane including a polyisocyanate component, a high-molecular-weight polyol component, a low-molecular-weight polyol component, and a polyamine component.
- The polyol, as a material for the urethane bond, has a plurality of hydroxyl groups. Low-molecular-weight polyols and high-molecular-weight polyols can be used.
- Examples of low-molecular-weight polyols include diols, triols, tetraols, and hexaols. Specific examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2,3-dimethyl-2,3-butanediol, neopentyl glycol, pentanediol, hexanediol, heptanediol, octanediol, and 1,6-cyclohexanedimethylol. Aniline diols or bisphenol A diols may be used. Specific examples of triols include glycerin, trimethylol propane, and hexanetriol. Specific examples of tetraols include pentaerythritol and sorbitol.
- Examples of high-molecular-weight polyols include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG); condensed polyester polyols such as polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA); lactone polyester polyols such as poly-s-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols. Two or more polyols may be used in combination. In light of feel at impact of the
golf ball 2 upon a shot with a driver, the high-molecular-weight polyol has a number average molecular weight of preferably equal to or greater than 400 and more preferably equal to or greater than 1000. The number average molecular weight is preferably equal to or less than 10000. Particularly preferably polyols are diols. - The polyisocyanate, as a material for the urethane bond, has two or more isocyanate groups. Examples of polyisocyanates include aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates. Two or more types of polyisocyanates may be used in combination.
- Examples of aromatic polyisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture (TDI) of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3′-bitolylene-4,4′-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI).
- Examples of alicyclic polyisocyanates include 4,4′-dicyclohexylmethane diisocyanate (H12MDI), 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI), isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate (CHDI).
- One example of aliphatic polyisocyanates is hexamethylene diisocyanate (HDI).
- In light of scuff resistance, aromatic polyisocyanates are preferable. In light of weather resistance, TMXDI, XDI, HDI, H6XDI, IPDI, H12MDI, and NBD are preferable, and H12MDI is particularly preferable. H12MDI is excellent in both scuff resistance and weather resistance.
- The polyamine for the chain-lengthening reaction has two or more amino groups. Examples of polyamines include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and piperazine; and aromatic polyamines.
- In an aromatic polyamine, an amino group is bonded to an aromatic ring. The amino group may be bonded directly to the aromatic ring. The amino group may be bonded indirectly to the aromatic ring via a lower alkylene group.
- Aromatic polyamines include monocyclic aromatic polyamines and polycyclic aromatic polyamines. In a monocyclic aromatic polyamine, two or more amino groups are bounded to one aromatic ring. A polycyclic aromatic polyamine has two or more aminophenyl groups. In each of the aminophenyl groups, one or more amino groups are bonded to one aromatic ring.
- Examples of monocyclic aromatic polyamines include polyamines in which an amino group is bonded directly to an aromatic ring, and polyamines in which an amino group is bonded to an aromatic ring via a lower alkylene group. Specific examples of monocyclic aromatic polyamines in which an amino group is bonded directly to an aromatic ring include phenylenediamine, toluenediamine, diethyltoluenediamine, and dimethylthiotoluenediamine. Specific examples of monocyclic aromatic polyamines in which an amino group is bonded to an aromatic ring via a lower alkylene group include xylylenediamine.
- Examples of polycyclic aromatic polyamines include poly(aminobenzene) in which two or more aminophenyl groups are bonded directly to each other, and polyamines in which two or more aminophenyl groups are bonded to each other via a lower alkylene group or an alkylene oxide group. Diaminodiphenylalkanes in which two aminophenyl groups are bonded to each other via a lower alkylene group are preferable, and 4,4′-diaminodiphenylmethane and derivatives thereof are particularly preferable.
- The
cover 10 may include a thermoplastic polyurethane, or may include a thermosetting polyurethane. In light of productivity, the thermoplastic polyurethane is preferable. The thermoplastic polyurethane includes a polyurethane component as a hard segment, and a polyester component or a polyether component as a soft segment. The thermoplastic polyurethane is flexible. Thecover 10 in which the polyurethane is used has excellent scuff resistance. - Specific examples of the thermoplastic polyurethane include trade names “Elastollan NY80A”, “Elastollan NY82A”, “Elastollan NY84A”, “Elastollan NY85A”, “Elastollan NY86A”, “Elastollan NY88A”, “Elastollan NY90A”, “Elastollan NY92A”, “Elastollan NY95A”, “Elastollan NY97A”, “Elastollan NY585”, “Elastollan KP016N”, and “Elastollan 1190ATR”, manufactured by BASF Japan Ltd.; and trade names “RESAMINE P4585LS” and “RESAMINE PS62490”, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.
- The resin composition of the
cover 10 may include a coloring agent, a filler, a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent material, a fluorescent brightener, and the like in an adequate amount. When the hue of thegolf ball 2 is white, a typical coloring agent is titanium dioxide. - In light of durability of the
cover 10, thecover 10 has a Shore D hardness Hc of preferably equal to or greater than 15, more preferably equal to or greater than 18, and particularly preferably equal to or greater than 20. In light of controllability ofgolf ball 2, the hardness Hc is preferably equal to or less than 40, more preferably equal to or less than 37, and particularly preferably equal to or less than 34. - The hardness Hc of the
cover 10 is measured according to the standards of “ASTM-D 2240-68”. The hardness Hc is measured with a Shore D type hardness scale mounted to an automated hardness meter (trade name “digi test II” manufactured by Heinrich Bareiss Prüfgerätebau GmbH). For the measurement, a sheet that is formed by hot press, is formed from the same material as that of thecover 10, and has a thickness of about 2 mm is used. Prior to the measurement, a sheet is kept at 23° C. for two weeks. At the measurement, three sheets are stacked. - In light of controllability, the
cover 10 has a thickness Tc of preferably equal to or greater than 0.1 mm, more preferably equal to or greater than 0.3 mm, and particularly preferably equal to or greater than 0.4 mm. In light of spin suppression upon a shot with a driver, the thickness Tc is preferably equal to or less than 2.0 mm, more preferably equal to or less than 1.5 mm, and particularly preferably equal to or less than 1.0 mm. The thickness Tc is measured at a position immediately below theland 14. - For forming the
cover 10, known methods such as injection molding, compression molding, and the like can be used. When forming thecover 10, thedimples 12 are formed by pimples formed on the cavity face of a mold. - The
golf ball 2 may include a reinforcing layer between themid layer 8 and thecover 10. The reinforcing layer firmly adheres to themid layer 8 and also to thecover 10. The reinforcing layer suppresses separation of themid layer 8 from thecover 10. The reinforcing layer is formed from a resin composition. Examples of a preferable base polymer of the reinforcing layer include two-component curing type epoxy resins and two-component curing type urethane resins. - The
golf ball 2 preferably has an amount of compressive deformation Sb of equal to or greater than 2.0 mm but equal to or less than 3.5 mm. Thegolf ball 2 having an amount of compressive deformation Sb of equal to or greater than 2.0 mm has excellent feel at impact. In this respect, the amount of compressive deformation Sb is preferably equal to or greater than 2.2 mm and particularly preferably equal to or greater than 2.3 mm. Thegolf ball 2 having an amount of compressive deformation Sb of equal to or less than 3.5 mm has a high initial speed upon a shot with a driver. In this respect, the amount of compressive deformation Sb is more preferably equal to or less than 3.2 mm and particularly preferably equal to or less than 3.0 mm. - For measurement of the amount of compressive deformation Sb, a YAMADA type compression tester is used. In the tester, the
golf ball 2 is placed on a hard plate made of metal. Next, a cylinder made of metal gradually descends toward thegolf ball 2. Thegolf ball 2, squeezed between the bottom face of the cylinder and the hard plate, becomes deformed. A migration distance of the cylinder, starting from the state in which an initial load of 98 N is applied to thegolf ball 2 up to the state in which a final load of 1274 N is applied thereto, is measured. A moving speed of the cylinder until the initial load is applied is 0.83 mm/s. A moving speed of the cylinder after the initial load is applied until the final load is applied is 1.67 mm/s. - In the
golf ball 2, a value Vb calculated by the following mathematical formula exceeds 620 and is less than 900. -
Vb=Tc*Hc*Hm/Tm - In other words, the
golf ball 2 meets the following mathematical formula (4). -
620<Tc*Hc*Hm/Tm<900 (4) - According to the finding by the present inventor, with the
golf ball 2 having a value Vb of exceeding 620 and less than 900, both desired flight performance and desired controllability are achieved. In this respect, thegolf ball 2 more preferably meets the following mathematical formula. -
640<Tc*Hc*Hm/Tm<800 - In the
golf ball 2 that includes thecover 10 having a low hardness Hc and a small thickness Tc, the mathematical formula (4) can be met. - As shown in
FIGS. 2 to 7 , the contour of eachdimple 12 is circular. Thegolf ball 2 has dimples A each having a diameter of 4.50 mm; dimples B each having a diameter of 4.40 mm; dimples C each having a diameter of 4.30 mm; dimples D each having a diameter of 4.20 mm; and dimples E each having a diameter of 3.00 mm. The number of types of thedimples 12 is five. Thegolf ball 2 may have non-circular dimples instead of thecircular dimples 12 or together withcircular dimples 12. - The number of the dimples A is 80; the number of the dimples B is 74; the number of the dimples C is 62; the number of the dimples D is 96; and the number of the dimples E is 12. The total number of the
dimples 12 is 324. A dimple pattern is formed by thesedimples 12 and theland 14. -
FIG. 8 shows a cross section of thegolf ball 2 along a plane passing through the central point of thedimple 12 and the central point of thegolf ball 2. InFIG. 8 , the top-to-bottom direction is the depth direction of thedimple 12. InFIG. 8 , a chain double-dashedline 16 indicates a phantom sphere. The surface of thephantom sphere 16 is the surface of thegolf ball 2 when it is postulated that nodimple 12 exists. The diameter of thephantom sphere 16 is equal to the diameter of thegolf ball 2. Thedimple 12 is recessed from the surface of thephantom sphere 16. Theland 14 coincides with the surface of thephantom sphere 16. In the present embodiment, the cross-sectional shape of eachdimple 12 is substantially a circular arc. The cross-sectional shape may be a curved line of which the curvature changes. - In
FIG. 8 , an arrow Dm indicates the diameter of thedimple 12. The diameter Dm is the distance between two tangent points Ed appearing on a tangent line Tg that is drawn tangent to the far opposite ends of thedimple 12. Each tangent point Ed is also the edge of thedimple 12. The edge Ed defines the contour of thedimple 12. InFIG. 8 , a double ended arrow Dp1 indicates a first depth of thedimple 12. The first depth Dp1 is the distance between the deepest part of thedimple 12 and the surface of thephantom sphere 16. InFIG. 8 , a double ended arrow Dp2 indicates a second depth of thedimple 12. The second depth Dp2 is the distance between the deepest part of thedimple 12 and the tangent line Tg. - The diameter Dm of each
dimple 12 is preferably equal to or greater than 2.0 mm but equal to or less than 6.0 mm. Thedimple 12 having a diameter Dm of equal to or greater than 2.0 mm contributes to turbulization. In this respect, the diameter Dm is more preferably equal to or greater than 2.5 mm and particularly preferably equal to or greater than 2.8 mm. Thedimple 12 having a diameter Dm of equal to or less than 6.0 mm does not impair a fundamental feature of thegolf ball 2 being substantially a sphere. In this respect, the diameter Dm is more preferably equal to or less than 5.5 mm and particularly preferably equal to or less than 5.0 mm. - In light of suppression of rising of the
golf ball 2 during flight, the first depth Dp1 of eachdimple 12 is preferably equal to or greater than 0.10 mm, more preferably equal to or greater than 0.13 mm, and particularly preferably equal to or greater than 0.15 mm. In light of suppression of dropping of thegolf ball 2 during flight, the first depth Dp1 is preferably equal to or less than 0.65 mm, more preferably equal to or less than 0.60 mm, and particularly preferably equal to or less than 0.55 mm. - The area S of the
dimple 12 is the area of a region surrounded by the contour line of thedimple 12 when the central point of thegolf ball 2 is viewed at infinity. In the case of acircular dimple 12, the area S is calculated by the following mathematical formula. -
S=(Dm/2)2*π - In the
golf ball 2 shown inFIGS. 2 to 7 , the area of each dimple A is 15.9 mm2; the area of each dimple B is 15.2 mm2; the area of each dimple C is 14.5 mm2; the area of each dimple D is 13.9 mm2; and the area of each dimple E is 7.1 mm2. - In the present invention, the ratio of the sum of the areas S of all the
dimples 12 relative to the surface area of thephantom sphere 16 is referred to as an occupation ratio. In light of flight distance upon a shot with a driver, the occupation ratio is preferably equal to or greater than 80%, more preferably equal to or greater than 81%, and particularly preferably equal to or greater than 82%. The occupation ratio is preferably equal to or less than 95%. In thegolf ball 2 shown inFIGS. 2 to 7 , the total area of thedimples 12 is 4712.8 mm2. The surface area of thephantom sphere 16 of thegolf ball 2 is 5728.0 mm2, so that the occupation ratio is 82.3%. - From the standpoint that a sufficient occupation ratio is achieved, the total number N of the
dimples 12 is preferably equal to or greater than 250, more preferably equal to or greater than 280, and particularly preferably equal to or greater than 300. From the standpoint that eachdimple 12 can contribute to turbulization, the total number N of thedimples 12 is preferably equal to or less than 450, more preferably equal to or less than 400, and particularly preferably equal to or less than 380. - In the present invention, the “volume of the dimple” means the volume of a portion surrounded by the surface of the
phantom sphere 16 and the surface of thedimple 12. In light of suppression of rising of thegolf ball 2 during flight, the total volume of all thedimples 12 is preferably equal to or greater than 450 mm3, more preferably equal to or greater than 480 mm3, and particularly preferably equal to or greater than 500 mm3. In light of suppression of dropping of thegolf ball 2 during flight, the total volume is preferably equal to or less than 750 mm3, more preferably equal to or less than 730 mm3, and particularly preferably equal to or less than 710 mm3. - In the present invention, the
dimples 12 each having an area of less than 8.0 mm2 is referred to as “small dimples 12S”. In thegolf ball 2 shown inFIGS. 2 to 7 , the dimples E are small dimples 12S. In thegolf ball 2, the number NS of the small dimples 12S is 12. - In the present invention, the
dimples 12 each having an area of equal to or greater than 8.0 mm2 is referred to as “large dimples 12L”. In thegolf ball 2 shown inFIGS. 2 to 7 , the dimples A to D are large dimples 12L. In thegolf ball 2, the number NL of the large dimples 12L is 312. The sum of the number NS and the number NL is equal to the total number N. - In a dimple pattern having only large dimples 12L, bias of the
land 14 tends to occur on the surface of thephantom sphere 16. In the present specification, the bias is referred to as distortion. In thegolf ball 2 according to the present invention, the small dimples 12S suppresses distortion. In thegolf ball 2, the small dimples 12S promote turbulization. With thegolf ball 2, a large flight distance is obtained upon a shot with a driver. - In a pattern in which an excessive number of small dimples 12S are present, variation in the sizes of the
dimples 12 is great. With the pattern having the great variation, turbulization is insufficient. With thegolf ball 2 having an appropriate number of small dimples 12S, sufficient turbulization is obtained. With thegolf ball 2 having an appropriate number of small dimples 12S, a large flight distance is obtained upon a shot with a driver. - In light of flight distance upon a shot with a driver, the ratio PS of the sum of the areas of the small dimples 12S relative to the surface area of the
phantom sphere 16 is preferably equal to or greater than 0.7%, more preferably equal to or greater than 0.9%, and particularly preferably equal to or greater than 1.0%. In light of flight distance upon a shot with a driver, the ratio PS is preferably less than 2.0%, more preferably equal to or less than 1.8%, and particularly preferably equal to or less than 1.7%. In thegolf ball 2 shown inFIGS. 2 to 7 , the ratio PS is 1.5%. - In light of flight distance upon a shot with a driver, the number NS of the small dimples 12S is preferably equal to or greater than 6, more preferably equal to or greater than 8, and particularly preferably equal to or greater than 10. In light of flight distance upon a shot with a driver, the number NS is preferably equal to or less than 20, more preferably equal to or less than 18, and particularly preferably equal to or less than 16.
- In light of flight distance upon a shot with a driver, the ratio (NS/N) of the number NS of the small dimples 12S relative to the total number N of the
dimples 12 is preferably equal to or greater than 0.01, more preferably equal to or greater than 0.02, and particularly preferably equal to or greater than 0.03. In light of flight distance upon a shot with a driver, the ratio (NS/N) is preferably equal to or less than 0.07, more preferably equal to or less than 0.06, and particularly preferably equal to or less than 0.05. In thegolf ball 2 shown inFIGS. 2 to 7 , the ratio (NS/N) is 0.04. - As described above, in light of suppression of distortion of the dimple pattern, the presence of the small dimples 12S is essential. Meanwhile, the degree of contribution of the small dimples 12S to turbulization is lower than that of the large dimples 12L. The dimple pattern in which an appropriate number of small dimples 12S are present and a sufficient number of large dimples 12L are present has excellent flight performance.
- In light of flight performance upon a shot with a driver, the ratio PL of the sum of the areas of the large dimples 12L relative to the surface area of the
phantom sphere 16 is preferably equal to or greater than 79.0%, more preferably equal to or greater than 79.5%, and particularly preferably equal to or greater than 80.0%. The ratio PL is preferably equal to or less than 90%. In thegolf ball 2 shown inFIGS. 2 to 7 , the ratio PL is 80.8%. - With a pattern having great variation in the sizes of the
dimples 12, turbulization is insufficient. From the standpoint that sufficient turbulization is obtained, a degree of uniformity G of the areas of the large dimples 12L is preferably equal to or less than 1.15, more preferably equal to or less than 1.10, and particularly preferably equal to or less than 1.05. The degree of uniformity G is preferably equal to or greater than 0.50. - The degree of uniformity G is the standard deviation of the areas (mm2) of the large dimples 12L. In the
golf ball 2 shown inFIGS. 2 to 7 , the average of the areas of the large dimples 12L is 14.9 mm2. The degree of uniformity G of thegolf ball 2 is calculated on the basis of the following mathematical formula. -
G=(((15.9−14.9)2*80+(15.2−14.9)2*74+(14.5−14.9)2*62+(13.9−14.9)2*96)/312)1/2 - The degree of uniformity G of the
golf ball 2 is 0.801. - A rubber composition (b) was obtained by kneading 100 parts by weight of a high-cis polybutadiene (trade name “BR-730”, manufactured by JSR Corporation), 26.0 parts by weight of zinc diacrylate, 5 parts by weight of zinc oxide, an appropriate amount of barium sulfate, 0.5 parts by weight of diphenyl disulfide, and 0.7 parts by weight of dicumyl peroxide. This rubber composition (b) was placed into a mold that includes upper and lower mold halves each having a hemispherical cavity, and heated at 170° C. for 15 minutes to obtain an inner core with a diameter D1 of 24 mm. The amount of barium sulfate was adjusted such that a predetermined ball weight is obtained.
- A rubber composition (d) was obtained by kneading 100 parts by weight of a high-cis polybutadiene (trade name “BR-730”, manufactured by JSR Corporation), 41.5 parts by weight of zinc diacrylate, 5 parts by weight of zinc oxide, an appropriate amount of barium sulfate, 0.1 parts by weight of an antioxidant (H-BHT), 0.5 parts by weight of diphenyl disulfide, and 0.7 parts by weight of dicumyl peroxide. Half shells were formed from this rubber composition (d). The inner core was covered with two of these half shells. The inner core and the half shells were placed into a mold that includes upper and lower mold halves each having a hemispherical cavity, and a core consisting of the inner core and an outer core was formed by a first crosslinking process and a second crosslinking process. In the first crosslinking process, the crosslinking temperature was 140° C., and the crosslinking time period was 20 minutes. In the second crosslinking process, the crosslinking temperature was 160° C., and the crosslinking time period was 10 minutes. The diameter of the core was 38.5 mm.
- A resin composition (M2) was obtained by kneading 50 parts by weight of an ionomer resin (the aforementioned “Surlyn 8150”), 50 parts by weight of another ionomer resin (the aforementioned “Himilan AM7329”), and 4 parts by weight of titanium dioxide with a twin-screw kneading extruder. The core was covered with this resin composition (M2) by injection molding to form a mid layer with a thickness of 1.6 mm.
- A paint composition (trade name “POLIN 750LE”, manufactured by SHINTO PAINT CO., LTD.) including a two-component curing type epoxy resin as a base polymer was prepared. The base material liquid of this paint composition includes 30 parts by weight of a bisphenol A type epoxy resin and 70 parts by weight of a solvent. The curing agent liquid of this paint composition includes 40 parts by weight of a modified polyamide amine, 55 parts by weight of a solvent, and 5 parts by weight of titanium dioxide. The weight ratio of the base material liquid to the curing agent liquid is 1/1. This paint composition was applied to the surface of the mid layer with a spray gun, and kept at 23° C. for 12 hours to obtain a reinforcing layer with a thickness of 10 μm.
- A resin composition (C2) was obtained by kneading 100 parts by weight of a thermoplastic polyurethane elastomer (the aforementioned “Elastollan NY84A”), 0.2 parts by weight of a light stabilizer (trade name “TINUVIN 770”), 4 parts by weight of titanium dioxide, and 0.04 parts by weight of ultramarine blue with a twin-screw kneading extruder. Half shells were obtained from this resin composition (C2) by compression molding. The sphere consisting of the inner core, the outer core, the mid layer, and the reinforcing layer was covered with two of the half shells. These half shells and the sphere were placed into a final mold that includes upper and lower mold halves each having a hemispherical cavity and having a large number of pimples on its cavity face, and a cover was obtained by compression molding. The thickness of the cover was 0.5 mm. Dimples having a shape that is the inverted shape of the pimples were formed on the cover.
- A clear paint including a two-component curing type polyurethane as a base material was applied to this cover to obtain a golf ball of Example 1 with a diameter of about 42.7 mm and a weight of about 45.6 g. Dimple specifications D2 of this golf ball are shown in detail in Tables 5 and 6 below.
FIG. 9 is a front view of this golf ball, andFIG. 10 is a plan view of this golf ball. - Golf balls of Examples 2 to 9 and Comparative Examples 1 to 7 were obtained in the same manner as Example 1, except the specifications of the inner core, the outer core, the mid layer, the cover, and the dimples were as shown in Tables 7 to 10 below. The specifications of the inner core and the outer core are shown in detail in Tables 1 and 2 below. The specifications of the mid layer are shown in detail in Table 3 below. The specifications of the cover are shown in detail in Table 4 below. The specifications of the dimples are shown in detail in Tables 5 and 6 below. The dimple pattern of the golf ball according to Comparative Example 3 is the same as the dimple pattern of the golf ball according to Comparative Example 4 in JP2006-20820. The dimple pattern of the golf ball according to Comparative Example 4 is the same as the dimple pattern of the golf ball according to Example 2 in JP2005-137692.
- [Flight Test]
- A driver (trade name “Z745”, manufactured by DUNLOP SPORTS CO. LTD., shaft hardness: S, loft angle: 8.5°) was attached to a swing machine manufactured by Golf Laboratories, Inc. A golf ball was hit under a condition of a head speed of 50 m/sec, and the initial speed, the spin rate, and the flight distance of the golf ball were measured. The flight distance is the distance between the point at the hit and the point at which the ball stopped. The average value of data obtained by 12 measurements is shown in Tables 7 to 10 below.
-
TABLE 1 Composition of Core (parts by weight) a b c d Polybutadiene 100 100 100 100 Zinc diacrylate — 26.0 31.5 41.5 Magnesium oxide 35 — — — Methacrylic acid 28 — — — Zinc oxide — 5 5 5 Barium sulfate * * * * H-BHT — — — 0.1 2-naphthalenethiol — — 0.2 — Diphenyl disulfide — 0.5 — 0.5 Pentabromodiphenyl disulfide — — 0.3 — Dicumyl peroxide 0.9 0.7 0.8 0.7 * Appropriate amount -
TABLE 2 Specifications of Core I II III IV Inner Composition a b b b layer Crosslinking temperature (° C.) 170 170 170 170 Crosslinking time period (min) 20 15 15 15 Diameter D1 (mm) 15 24 27 20 Outer Composition c d d d layer First crosslinking 150 140 140 140 temperature (° C.) First crosslinking 20 20 20 20 time period (min) Second crosslinking — 160 160 160 temperature (° C.) Second crosslinking — 10 10 10 time period (min) -
TABLE 3 Specifications of Mid Layer (parts by weight) M1 M2 M3 M4 Surlyn 8150 — 50 25 32.5 Surlyn 9150 — — — 32.5 Polyamide 6— — — 35 Himilan 1605 47 — 25 — Himilan AM7329 50 50 50 — RABALON T3221C 3 — — — Titanium dioxide 4 4 4 4 Hardness Hm (Shore D) 63 68 66 72 -
TABLE 4 Specifications of Cover (parts by weight) C1 C2 C3 Elastollan NY82A 100 — — Elastollan NY84A — 100 — Elastollan NY90A — — 100 TINUVIN 770 0.2 0.2 0.2 Titanium dioxide 4 4 4 Ultramarine blue 0.04 0.04 0.04 Hardness Hc (Shore D) 29 31 38 -
TABLE 5 Specifications of Dimples Dm Dp2 Dp1 Radius Volume Area Number (mm) (mm) (mm) (mm) (mm3) (mm2) D1 A 80 4.50 0.135 0.2539 18.82 2.012 15.9 B 74 4.40 0.135 0.2487 17.99 1.884 15.2 C 62 4.30 0.135 0.2435 17.19 1.763 14.5 D 96 4.20 0.135 0.2385 16.40 1.648 13.9 E 12 3.00 0.135 0.1878 8.40 0.663 7.1 D2 A 60 4.40 0.135 0.2487 17.99 1.884 15.2 B 158 4.30 0.135 0.2435 17.19 1.763 14.5 C 72 4.15 0.135 0.2361 16.01 1.592 13.5 D 36 3.90 0.135 0.2242 14.15 1.336 11.9 E 12 3.00 0.135 0.1878 8.40 0.663 7.1 D3 A 132 4.95 0.137 0.2809 22.42 2.693 19.2 B 78 4.50 0.139 0.2579 18.28 2.044 15.9 C 36 4.20 0.137 0.2405 16.16 1.661 13.9 D 12 3.90 0.132 0.2212 14.47 1.318 11.9 E 12 3.10 0.130 0.1863 9.31 0.702 7.5 D4 A 66 4.55 0.135 0.2566 19.24 2.079 16.3 B 24 4.35 0.130 0.2411 18.26 1.786 14.9 C 60 4.25 0.125 0.2310 18.13 1.633 14.2 D 132 4.05 0.125 0.2213 16.47 1.421 12.9 E 72 3.70 0.125 0.2053 13.75 1.101 10.8 F 18 2.55 0.125 0.1631 6.57 0.417 5.1 -
TABLE 6 Specifications of Dimples D1 D2 D3 D4 Front view FIG. 2 FIG. 9 — — Plan view FIG. 4 FIG. 10 — — Number 324 338 270 372 Occupation ratio (%) 82.3 82.0 78.8 84.6 Total volume (mm3) 576 562 599 552 NS 12 12 12 18 NL 312 326 258 354 PS (%) 1.5 1.5 1.6 1.6 PL (%) 80.8 80.5 77.2 83.0 G 0.801 0.946 2.343 1.816 -
TABLE 7 Results of Evaluation Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 1 Core II II II II Inner core D1 (mm) 24.0 24.0 24.0 24.0 V1 (mm3) 7238 7238 7238 7238 H1o (Shore C) 60 60 60 60 H1in (Shore C) 74 74 74 74 De1 = H1in − H1o 14 14 14 14 Outer core D2 (mm) 38.5 38.5 39.1 38.1 V2 (mm3) 22642 22642 24061 21720 H2out (Shore C) 82 82 82 82 H2s (Shore C) 82 82 82 82 De2 = H2s − H2out 0 0 0 0 Mid layer M2 M2 M2 M2 Hm (Shore D) 68 68 68 68 Tm (mm) 1.6 1.6 1.3 1.8 Cover C2 C2 C2 C2 Hc (Shore D) 31 31 31 31 Tc (mm) 0.5 0.5 0.5 0.5 Dimple D2 D1 D2 D2 V2/V1 3.1 3.1 3.3 3.0 De2 − De1 −14 −14 −14 −14 Va 804 804 804 804 Vb 659 659 811 586 Sb (mm) 2.3 2.3 2.4 2.2 Initial speed (m/s) 73.7 73.7 73.5 73.8 Spin (rpm) 2500 2500 2400 2700 Flight distance (yd) 291 290 291 289.5 -
TABLE 8 Results of Evaluation Ex. 4 Ex. 5 Ex. 6 Ex. 7 Core III IV II II Inner core D1 (mm) 27.0 20.0 24.0 24.0 V1 (mm3) 10306 4189 7238 7238 H1o (Shore C) 60 60 60 60 H1in (Shore C) 74 74 74 74 De1 = H1in − H1o 14 14 14 14 Outer core D2 (mm) 38.5 38.5 38.5 38.5 V2 (mm3) 19574 25691 22642 22642 H2out (Shore C) 82 82 82 82 H2s (Shore C) 82 82 82 82 De2 = H2s − H2out 0 0 0 0 Mid layer M2 M2 M3 M4 Hm (Shore D) 68 68 66 72 Tm (mm) 1.6 1.6 1.6 1.6 Cover C2 C2 C2 C2 Hc (Shore D) 31 31 31 31 Tc (mm) 0.5 0.5 0.5 0.5 Dimple D2 D2 D2 D2 V2/V1 1.9 6.1 3.1 3.1 De2 − De1 −14 −14 −14 −14 Va 905 670 804 804 Vb 659 659 639 698 Sb (mm) 2.3 2.3 2.3 2.2 Initial speed (m/s) 73.6 73.7 73.7 73.7 Spin (rpm) 2500 2550 2550 2450 Flight distance (yd) 290.5 290.5 290.5 291.5 -
TABLE 9 Results of Evaluation Comp. Comp. Ex. 8 Ex. 2 Ex. 9 Ex. 3 Core II II II II Inner core D1 (mm) 24.0 24.0 24.0 24.0 V1 (mm3) 7238 7238 7238 7238 H1o (Shore C) 60 60 60 60 H1in (Shore C) 74 74 74 74 De1 = H1in − H1o 14 14 14 14 Outer core D2 (mm) 38.5 38.5 38.3 38.5 V2 (mm3) 22642 22642 22179 22642 H2out (Shore C) 82 82 82 82 H2s (Shore C) 82 82 82 82 De2 = H2s − H2out 0 0 0 0 Mid layer M2 M2 M2 M2 Hm (Shore D) 68 68 68 68 Tm (mm) 1.6 1.6 1.6 1.6 Cover C3 C1 C2 C2 Hc (Shore D) 38 29 31 31 Tc (mm) 0.5 0.5 0.6 0.5 Dimple D2 D2 D2 D3 V2/V1 3.1 3.1 3.1 3.1 De2 − De1 −14 −14 −14 −14 Va 804 804 804 804 Vb 808 616 791 659 Sb (mm) 2.3 2.3 2.3 2.3 Initial speed (m/s) 73.7 73.6 73.7 73.7 Spin (rpm) 2350 2600 2600 2500 Flight distance (yd) 292.5 289.5 290 286 -
TABLE 10 Results of Evaluation Comp. Comp. Comp. Comp. Ex. 4 Ex. 5 Ex. 6 Ex. 7 Core II II II I Inner core D1 (mm) 24.0 24.0 24.0 15.0 V1 (mm3) 7238 7238 7238 1767 H1o (Shore C) 60 60 60 62 H1in (Shore C) 74 74 74 65 De1 = H1in − H1o 14 14 14 3 Outer core D2 (mm) 38.5 39.7 38.5 39.7 V2 (mm3) 22642 25524 22642 30995 H2out (Shore C) 82 82 82 71 H2s (Shore C) 82 82 82 85 De2 = H2s − H2out 0 0 0 14 Mid layer M2 M2 M1 M2 Hm (Shore D) 68 68 63 68 Tm (mm) 1.6 1.0 1.6 1.0 Cover C2 C2 C2 C1 Hc (Shore D) 31 31 31 29 Tc (mm) 0.5 0.5 0.5 0.5 Dimple D4 D2 D2 D2 V2/V1 3.1 3.5 3.1 17.5 De2 − De1 −14 −14 −14 11 Va 804 804 804 476 Vb 659 1054 610 986 Sb (mm) 2.3 2.5 2.4 2.3 Initial speed (m/s) 73.7 73.2 73.3 73.4 Spin (rpm) 2500 2400 2550 2500 Flight distance (yd) 285 287 286 287 - As shown in Tables 7 to 10, the golf ball of each Example has excellent flight performance upon a shot with a driver. From the results of evaluation, advantages of the present invention are clear.
- The golf ball according to the present invention is suitable for, for example, playing golf on golf courses and practicing at driving ranges. The above descriptions are merely illustrative examples, and various modifications can be made without departing from the principles of the present invention.
Claims (15)
1.0<V2/V1<7.0 (1).
2.0<V2/V1<6.0.
De2−De1<0 (2).
600<(H1o+H1in)*(D1/2)/2<1000 (3).
700<(H1o+H1in)*(D1/2)/2<900.
620<Tc*Hc*Hm/Tm<900 (4).
640<Tc*Hc*Hm/Tm<800.
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US20200070008A1 (en) * | 2018-08-31 | 2020-03-05 | Sumitomo Rubber Industries, Ltd. | Golf ball |
Citations (44)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5957786A (en) * | 1997-09-03 | 1999-09-28 | Acushnet Company | Golf ball dimple pattern |
US6213898B1 (en) * | 1999-09-16 | 2001-04-10 | Callaway Golf Company | Golf ball with an aerodynamic surface on a polyurethane cover |
US6224499B1 (en) * | 1999-09-16 | 2001-05-01 | Callaway Golf Company | Golf ball with multiple sets of dimples |
US6241627B1 (en) * | 1998-07-30 | 2001-06-05 | Bridgestone Sports Co., Ltd. | Dimpled golf ball |
US20010005700A1 (en) * | 1999-12-21 | 2001-06-28 | Atsuki Kasashima | Golf Ball |
US20030050138A1 (en) * | 2001-08-24 | 2003-03-13 | Bridgestone Sports Co., Ltd. | Multi-piece solid golf ball |
US20030153403A1 (en) * | 2001-10-23 | 2003-08-14 | Seiichiro Endo | Three-piece solid golf ball |
US20030232667A1 (en) * | 2002-04-17 | 2003-12-18 | Bridgestone Sports Co., Ltd. | Golf ball |
US20040029649A1 (en) * | 2002-08-12 | 2004-02-12 | Takashi Sasaki | Golf ball |
US20040132549A1 (en) * | 2003-01-06 | 2004-07-08 | Steven Aoyama | Golf ball with improved flight performance |
US20050130768A1 (en) * | 2003-12-10 | 2005-06-16 | Sumitomo Rubber Industries, Ltd. | Golf ball |
US20060025244A1 (en) * | 2004-07-29 | 2006-02-02 | Sri Sports Limited | Golf ball |
US20060025240A1 (en) * | 2004-07-29 | 2006-02-02 | Sri Sports Limited | Golf ball |
US20070026972A1 (en) * | 2005-07-27 | 2007-02-01 | Sri Sports Limited | Golf ball |
US20070149321A1 (en) * | 2005-12-28 | 2007-06-28 | Sri Sports Limited | Golf ball |
US20070173354A1 (en) * | 2006-01-24 | 2007-07-26 | Sri Sports Limited | Golf ball |
US7384351B2 (en) * | 2005-11-22 | 2008-06-10 | Bridgestone Sports Co., Ltd. | Golf ball |
US20090082137A1 (en) * | 2007-09-25 | 2009-03-26 | Sri Sports Limited | Golf ball |
US20090247326A1 (en) * | 2008-03-25 | 2009-10-01 | Keiji Ohama | Golf ball |
US7683128B2 (en) * | 2006-01-10 | 2010-03-23 | Sri Sports Limited | Telechelic ionomer composition for golf ball and golf ball using the same |
US20100160084A1 (en) * | 2004-06-23 | 2010-06-24 | Sullivan Michael J | Multilayer core golf ball having hardness gradient within and between each core layer |
US20100173726A1 (en) * | 2007-07-03 | 2010-07-08 | Sullivan Michael J | Golf ball having reduced surface hardness |
US20100227707A1 (en) * | 2007-07-03 | 2010-09-09 | Sullivan Michael J | Multilayer core golf ball having hardness gradient within and between each core layer |
US20110275456A1 (en) * | 2007-11-14 | 2011-11-10 | Sullivan Michael J | Dual core golf ball having positive-hardness-gradient thermoplastic inner core and shallow negative-hardness-gradient outer core layer |
US20110306443A1 (en) * | 2010-06-09 | 2011-12-15 | Yoshiko Matsuyama | Golf ball |
US20110319193A1 (en) * | 2010-06-29 | 2011-12-29 | Kazuhiko Isogawa | Golf ball |
US20120004053A1 (en) * | 2010-06-30 | 2012-01-05 | Hyoungchol Kim | Designing method for dimple pattern of golf ball |
US20120043686A1 (en) * | 2010-08-20 | 2012-02-23 | Nike, Inc. | Golf Balls including Multiple Dimple Types and/or Multiple Layers of Different Hardnesses |
US20120088604A1 (en) * | 2010-10-07 | 2012-04-12 | Yoshiko Matsuyama | Golf ball |
US20120122610A1 (en) * | 2007-11-14 | 2012-05-17 | Sullivan Michael J | Golf ball having a thermoplastic positive hardness gradient inner core layer and a thermoset shallow positive hardness gradient outer core layer |
US20120165131A1 (en) * | 2010-12-24 | 2012-06-28 | Hirotaka Nakamura | Golf ball |
US20120165132A1 (en) * | 2010-12-24 | 2012-06-28 | Hirotaka Nakamura | Golf ball |
US20120264542A1 (en) * | 2011-04-18 | 2012-10-18 | Yoshiko Matsuyama | Golf ball |
US20130005509A1 (en) * | 2011-06-29 | 2013-01-03 | Hirotaka Nakamura | Golf ball |
US20130029789A1 (en) * | 2007-07-03 | 2013-01-31 | Acushnet Company | Multilayer core golf ball having hardness gradient within and between each core layer |
US20130157781A1 (en) * | 2007-07-03 | 2013-06-20 | Acushnet Company | Golf ball with single layer core having specific regions of varying hardness |
US20130196791A1 (en) * | 2012-01-30 | 2013-08-01 | Dunlop Sports Co. Ltd. | Golf ball |
US8777779B2 (en) * | 2010-12-28 | 2014-07-15 | Sri Sports Limited | Golf ball |
US20140295995A1 (en) * | 2007-11-14 | 2014-10-02 | Acushnet Company | Golf Ball Having A Thermoplastic Positive Hardness Gradient Inner Core Layer And A Thermoset Shallow Positive Hardness Gradient Outer Core Layer |
US20140364252A1 (en) * | 2013-01-09 | 2014-12-11 | Acushnet Company | Golf ball having a hollow center |
US20150038268A1 (en) * | 2013-08-05 | 2015-02-05 | Acushnet Company | Multi-layer core golf ball |
US20150038267A1 (en) * | 2013-08-05 | 2015-02-05 | Acushnet Company | Multi-layer core golf ball |
US20150141166A1 (en) * | 2012-09-12 | 2015-05-21 | Acushnet Company | Golf balls having a foam center |
US20150238823A1 (en) * | 2013-08-05 | 2015-08-27 | Acushnet Company | Multi-layer core golf ball |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3981809B2 (en) * | 2001-12-28 | 2007-09-26 | ブリヂストンスポーツ株式会社 | Golf ball |
JP5322571B2 (en) * | 2008-10-16 | 2013-10-23 | ダンロップスポーツ株式会社 | Golf ball |
JP6068003B2 (en) * | 2012-05-30 | 2017-01-25 | ダンロップスポーツ株式会社 | Golf ball |
-
2015
- 2015-12-24 JP JP2015251371A patent/JP6690228B2/en active Active
-
2016
- 2016-11-28 US US15/362,208 patent/US20170182371A1/en not_active Abandoned
Patent Citations (44)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5957786A (en) * | 1997-09-03 | 1999-09-28 | Acushnet Company | Golf ball dimple pattern |
US6241627B1 (en) * | 1998-07-30 | 2001-06-05 | Bridgestone Sports Co., Ltd. | Dimpled golf ball |
US6213898B1 (en) * | 1999-09-16 | 2001-04-10 | Callaway Golf Company | Golf ball with an aerodynamic surface on a polyurethane cover |
US6224499B1 (en) * | 1999-09-16 | 2001-05-01 | Callaway Golf Company | Golf ball with multiple sets of dimples |
US20010005700A1 (en) * | 1999-12-21 | 2001-06-28 | Atsuki Kasashima | Golf Ball |
US20030050138A1 (en) * | 2001-08-24 | 2003-03-13 | Bridgestone Sports Co., Ltd. | Multi-piece solid golf ball |
US20030153403A1 (en) * | 2001-10-23 | 2003-08-14 | Seiichiro Endo | Three-piece solid golf ball |
US20030232667A1 (en) * | 2002-04-17 | 2003-12-18 | Bridgestone Sports Co., Ltd. | Golf ball |
US20040029649A1 (en) * | 2002-08-12 | 2004-02-12 | Takashi Sasaki | Golf ball |
US20040132549A1 (en) * | 2003-01-06 | 2004-07-08 | Steven Aoyama | Golf ball with improved flight performance |
US20050130768A1 (en) * | 2003-12-10 | 2005-06-16 | Sumitomo Rubber Industries, Ltd. | Golf ball |
US20100160084A1 (en) * | 2004-06-23 | 2010-06-24 | Sullivan Michael J | Multilayer core golf ball having hardness gradient within and between each core layer |
US20060025244A1 (en) * | 2004-07-29 | 2006-02-02 | Sri Sports Limited | Golf ball |
US20060025240A1 (en) * | 2004-07-29 | 2006-02-02 | Sri Sports Limited | Golf ball |
US20070026972A1 (en) * | 2005-07-27 | 2007-02-01 | Sri Sports Limited | Golf ball |
US7384351B2 (en) * | 2005-11-22 | 2008-06-10 | Bridgestone Sports Co., Ltd. | Golf ball |
US20070149321A1 (en) * | 2005-12-28 | 2007-06-28 | Sri Sports Limited | Golf ball |
US7683128B2 (en) * | 2006-01-10 | 2010-03-23 | Sri Sports Limited | Telechelic ionomer composition for golf ball and golf ball using the same |
US20070173354A1 (en) * | 2006-01-24 | 2007-07-26 | Sri Sports Limited | Golf ball |
US20100227707A1 (en) * | 2007-07-03 | 2010-09-09 | Sullivan Michael J | Multilayer core golf ball having hardness gradient within and between each core layer |
US20130029789A1 (en) * | 2007-07-03 | 2013-01-31 | Acushnet Company | Multilayer core golf ball having hardness gradient within and between each core layer |
US20100173726A1 (en) * | 2007-07-03 | 2010-07-08 | Sullivan Michael J | Golf ball having reduced surface hardness |
US20130157781A1 (en) * | 2007-07-03 | 2013-06-20 | Acushnet Company | Golf ball with single layer core having specific regions of varying hardness |
US20090082137A1 (en) * | 2007-09-25 | 2009-03-26 | Sri Sports Limited | Golf ball |
US20110275456A1 (en) * | 2007-11-14 | 2011-11-10 | Sullivan Michael J | Dual core golf ball having positive-hardness-gradient thermoplastic inner core and shallow negative-hardness-gradient outer core layer |
US20140295995A1 (en) * | 2007-11-14 | 2014-10-02 | Acushnet Company | Golf Ball Having A Thermoplastic Positive Hardness Gradient Inner Core Layer And A Thermoset Shallow Positive Hardness Gradient Outer Core Layer |
US20120122610A1 (en) * | 2007-11-14 | 2012-05-17 | Sullivan Michael J | Golf ball having a thermoplastic positive hardness gradient inner core layer and a thermoset shallow positive hardness gradient outer core layer |
US20090247326A1 (en) * | 2008-03-25 | 2009-10-01 | Keiji Ohama | Golf ball |
US20110306443A1 (en) * | 2010-06-09 | 2011-12-15 | Yoshiko Matsuyama | Golf ball |
US20110319193A1 (en) * | 2010-06-29 | 2011-12-29 | Kazuhiko Isogawa | Golf ball |
US20120004053A1 (en) * | 2010-06-30 | 2012-01-05 | Hyoungchol Kim | Designing method for dimple pattern of golf ball |
US20120043686A1 (en) * | 2010-08-20 | 2012-02-23 | Nike, Inc. | Golf Balls including Multiple Dimple Types and/or Multiple Layers of Different Hardnesses |
US20120088604A1 (en) * | 2010-10-07 | 2012-04-12 | Yoshiko Matsuyama | Golf ball |
US20120165132A1 (en) * | 2010-12-24 | 2012-06-28 | Hirotaka Nakamura | Golf ball |
US20120165131A1 (en) * | 2010-12-24 | 2012-06-28 | Hirotaka Nakamura | Golf ball |
US8777779B2 (en) * | 2010-12-28 | 2014-07-15 | Sri Sports Limited | Golf ball |
US20120264542A1 (en) * | 2011-04-18 | 2012-10-18 | Yoshiko Matsuyama | Golf ball |
US20130005509A1 (en) * | 2011-06-29 | 2013-01-03 | Hirotaka Nakamura | Golf ball |
US20130196791A1 (en) * | 2012-01-30 | 2013-08-01 | Dunlop Sports Co. Ltd. | Golf ball |
US20150141166A1 (en) * | 2012-09-12 | 2015-05-21 | Acushnet Company | Golf balls having a foam center |
US20140364252A1 (en) * | 2013-01-09 | 2014-12-11 | Acushnet Company | Golf ball having a hollow center |
US20150038268A1 (en) * | 2013-08-05 | 2015-02-05 | Acushnet Company | Multi-layer core golf ball |
US20150038267A1 (en) * | 2013-08-05 | 2015-02-05 | Acushnet Company | Multi-layer core golf ball |
US20150238823A1 (en) * | 2013-08-05 | 2015-08-27 | Acushnet Company | Multi-layer core golf ball |
Non-Patent Citations (5)
Title |
---|
DuPont, Hardness Conversion, uploaded 10/24/17, DuPont, 1 page * |
Examiner Stanczak, Examiner's Calc - version #2, uploaded 5/2/18, Excel Spreadsheet, 1 page * |
Examiner Stanczak, Examiner's Calculations 3, uploaded 4/1/19, Excel Spreadsheet, 1 page * |
Examiner Stanczak, Examiner's Calculations, uploaded 10/24/17, Excel Spreadsheet, 1 page * |
Rick White, Thermal Tech Equipment Shore Durometer Conversion Chart, uploaded 10/24/17, Thermal Tech, 1 page * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20200070008A1 (en) * | 2018-08-31 | 2020-03-05 | Sumitomo Rubber Industries, Ltd. | Golf ball |
Also Published As
Publication number | Publication date |
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JP6690228B2 (en) | 2020-04-28 |
JP2017113255A (en) | 2017-06-29 |
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