WO2001039704A1

WO2001039704A1 - Cooling pad

Info

Publication number: WO2001039704A1
Application number: PCT/US1999/028261
Authority: WO
Inventors: Lonnie Liddell Bryant, Jr.; Hsiang-Kuen Mao
Original assignee: The Procter & Gamble Company
Priority date: 1999-11-30
Filing date: 1999-11-30
Publication date: 2001-06-07
Also published as: WO2001039705A1; AU1804101A; AU2350300A; WO2001039704A9; WO2001039704A8; WO2001039705A8

Abstract

Disclosed is a cooling article (10) comprising a cooling pad (20) and a phase change material (30). The cooling pad (20) includes a cooling composition capable of generating a cold temperature for a period of time. The phase change material (30) prolongs the period of time during which the cold temperature is generated.

Description

COOLING PAD

FIELD

The present invention relates to a cooling article. In particular, it relates to a cooling or refreshing pad for body and face that provides a prolonged cooling sensation without extreme cold.

BACKGROUND

As is known, cooling or refreshing bags and/or pads have been widely used to cool down individuals during heat stress and/or to treat disorders, injury, and fatigue. Such bags and/or pads generally contain chemical components. Cold compresses of cloth or the like soaked with water or an evaporating chemical are also known. When used for these purposes, such cooling bags and pads are directly applied to the body. Recently, particularly during hot climate season, consumers tend to use such cooling bags to cool down their body rather than to treat their health such as a fever.

A variety of products to be used for the above purposes are known in the art. These products include cooling pillows, cooling packs, coolant compositions, and so on. Such products are generally prepared as impermeable bags or packages filled with cooling compositions such as ice cubes, cold water, a heat- storing antifreeze solution, or a polymeric cold-retaining agent. These products are mainly classified into two groups; reusable and disposable products. For example, cooling pillows filled with ice cubes or polymeric agent are reusable products. Products that contain chemically reactive materials, e.g., endothermic reaction components, are usually disposable products. Recently, disposable- type products have become popular to provide cooling for the body in hot climates or during the hot season.

Cooling bags filled with ice such as cooling pillows, immediately generate extremely low temperature to the body during use and require that the ice be replenished when it melts, making it necessary to have a constant supply of ice available. Cold packs containing water, antifreeze solution, or a polymeric cold- retaining agent tend to approach body temperature within a short time, so that the cooling action persists only for a short time. Therefore, chemically reactive materials have become popular as a source of cooling materials.

Such chemically reactive cooling components, which cause an endothermic reaction when dissolved in water, are known in the art. See unexamined Japanese publications (Kokai) S62-112678, Yamazaki, et al., issued May 23, 1987; H1 -230689, Kosuge et al., issued September 14, 1989; H7- 322041 , Koiso et al., issued December 12, 1995; H8-34975, Koiso et al., issued February 2, 1996; H9-100468, Nakagawa et al., issued April 15, 1997; and H9- 272862, Emori et al., issued October 21 , 1997.

However, such cooling compositions also tend to become extremely cold as soon as an endothermic reaction is generated; at the time when the reaction is started, the composition become too cold to be comfortably applied to body areas. In addition, cold temperatures generated by the above endothermic reactions generally have a shorter cooling period than the period desired or expected by the most users and rise in temperature approaching body temperature within a short period.

Based on the foregoing, there is a need for a cooling article that provides a pleasant cooling feel without extreme cold and that further provides an extended period of cooling, as well as desirable flexibility in order to be fixed or fitted to various body areas. None of the existing art provides all of the advantages and benefits of the present invention.

SUMMARY This need is met by the present invention wherein articles having superior cooling properties to body are proposed. The present invention is directed to a cooling article comprising a cooling pad and a phase change material. The cooling pad includes a cooling composition that generates a cold temperature for a period of time. The phase change material prolongs the period of time during the cold temperature is generated.

These and other features, aspects, and advantages of the present invention will become better understood from a reading of the following description, and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming the invention, it is believed that the invention will be better understood from the following description of preferred embodiments which is taken in conjunction with the accompanying drawings and which like designations are used to designate substantially identical elements, and in which:

Figures 1A and 1 B are sectional views of a preferred embodiment of a cooling article of the present invention comprising a cooling pad and a phase change material; Figure 2 is a perspective view of a stretchable band comprising a cooling article of the present invention;

Figure 3 is a sectional view of the stretchable band of Figure 2 in its closed position;

Figure 4 is a perspective view of a sun-visor comprising a cooling pad and a phase change material according to the present invention.

Figure 5 is a perspective cutaway view of a cooling eye-mask according to the present invention; and

Figure 6 is a graph showing temperature profiles of a cooling article with phase-changing material of the present invention, and cooling article without a phase-changing material.

DETAILED DESCRIPTION

All percentages and ratios used hereinafter are by weight of total composition, unless otherwise indicated. All percentages, ratios, and levels of ingredients referred to herein are based on the actual amount of the ingredient, and do not include solvents, fillers, or other materials with which the ingredient may be combined as a commercially available product, unless otherwise indicated.

All publications, patent applications, and issued patents mentioned herein are hereby incorporated in their entirety by reference. Citation of any reference is not an admission regarding any determination as to its availability as prior art to the claimed invention.

Herein, "comprising" means that other steps and other ingredients which do not affect the end result can be added. This term encompasses the terms "consisting of and "consisting essentially of. All ingredients such as actives and other ingredients useful herein may be categorized or described by their cosmetic and/or therapeutic benefit or their postulated mode of action. However, it is to be understood that the active and other ingredients useful herein can, in some instances, provide more than one cosmetic and/or therapeutic benefit or operate via more than one mode of action. Therefore, classifications herein are made for the sake of convenience and are not intended to limit an ingredient to the particularly stated application or applications listed. A. Cooling Article The topical cooling article comprises a cooling pad and a phase change material. Herein, "cooling article," means an article which extends a period of time during which a cold temperature exists through the use of a phase change material, the cooling effect being released from a cooling pad. The cooling article of the present invention preferably has a suitable flexibility so that it can be applied to the human body or to an animal body. Herein, the cooling article of the present invention is described primarily in terms of human use, but it should be understood that the cooling effects and benefits herein can be used with equal advantages for animals. Thus, it should be understood that the present invention is not limited to human use. Herein, "cooling pad," refers to a pad which contains a cooling composition capable of generating a cold temperature for a period of time. Herein, "phase change material," refers to a material which prevent extreme cold feel and prolongs the cooling effect supplied from the cooling pad. For example, when used for the human body, the phase change material of the present invention adjusts to the cooling pads. Therefore, cold temperature generated from the cooling pad is absorbed into the phase change material. Such generated cold temperature from cooling composition is generally from about 5 to about 10 deg C or lower. It is believed that such absorption controls the cold temperature to levels appropriate for the body. The absorbed cold temperature is then released from the phase change material. It is also believed that because of the characteristic of the phase change material, the release of the temperature from the material tends to be slower than when the cooling pads contacts with the body directly. Presence of the material also physically prevents extreme chill feeling. The phase change material is preferably positioned between the body and the cooling pads. The cooling article of the present invention provides a pleasant cooling feel without extreme cold and that further provides an extended period of cooling.

Preferably, the temperature generated from the cooling article is less than about

30°C for at least about 3 hours, more preferably 4 hours after the cold temperature is generated.

In another aspect, the temperature generated from the cooling article is less than about 30°C for at least twice as long as without the phase change material after the cold temperature is generated.

In one embodiment, the cooling article further comprises at least one flexible material. Herein, "flexible material" means a material which allows the user to comfortably fix or fit both the phase change material and the cooling pad to the body.

The particular configuration or shape of flexible material naturally depends upon the desired end usage, e.g., common body-wear products such as caps, sun-visors, head-bands, eye masks and any clothes. Types of the flexible material also varies as long as both the cooling pads and the phase change materials are adjusted to the body. For example, various cords and bandages are useful to adjust the cooling articles to the body surface by encircling the cooling article to the body including head, shoulders, knees, ankles, etc., and then tying the end of cords, bands, or hock and lap materials such as Velcro™. The flexible materials may further contain an elongate bag, made of a cloth or meshed polymer, in which the cooling article is contained.

Preferably, flexible materials are made of any of materials to impart a soft feel, for example, clothes, a woven fabric, a nonwoven fabric, an elastic film which is typically a synthetic resin film having strength sufficient to handling during use and transport, and the like. Examples of the synthetic films include polyethylene, polypropylene, polyester, nylon, polyvinyl chloride, polyvinylidene chloride, polyisocyanate and other synthetic resins. Composite and laminate films of these materials are also available. Polyester, nylon, polyethylene, polypropylene, and composite films, blends, or laminates of these materials are preferred. The flexible material of the present invention may further include a fastener member to securely fasten both the cooling pad and the phase change material.

The flexible material used herein may further have stretchability of material in order to improve fitness of the cooling article to the body. The stretchable area must be limited to areas other than areas at which the phase change material is located. For example, if the flexible material also has stretchability of the area where the cooling pad and phase change material are located, this pad and phase material may be broken by the stretching of the flexible material. Both cooling compositions and fluid packed in pads and phase change materials, respectively, may be flowing from these packages on skin.

Referring now to the drawings, there is shown a preferred embodiment of the present invention, which provides a cooling article 10 comprising a cooling pad 20 and a phase change material 30, shown in Figure 1. Figure 1A shows the cooling article containing one cooling pad and one phase change material. In this embodiment, the surface of phase change material contacts the body surface. The cooling article of Figure 1 B contains one cooling pad located between two phase change materials. B. Cooling pad A variety of the size or shape of the cooling pad 20 is available as long as it is capable of providing sufficient coldness. Some commercially available cooling pads can be used in the cooling article of the present invention. Preferably, the size of the cooling pad useful herein is slightly smaller than that of the area of the phase change material portion to prevent the cooling pad directly contacting to body surface.

The cooling pad useful herein contains a cooling composition filled in a bag or other such receptacle. A wide variety of suitable cooling compositions are known and may be used herein. It is necessary that the cooling composition useful herein is non-toxic and safe materials to human and has pleasant odor because these are applied to human body even if these are not directly in contact with the body. Preferably, such cooling compositions are selected from the group consisting of ice cubes, cold-water, heat-storing antifreeze solution, polymeric cold-retaining agents, and endothermic agents, and are packed in a water-impermeable bag or other such receptacle. Water-based compositions such as ice cubes and cold-water are, of course, re-useable. For example, such water-based compositions can be refrigerated after the previous use.

The endothermic ingredient, upon combining with water, generates endothermic reaction. Water may be supplied in a separate package which when broken begins the endothermic reaction. A variety of endothermic ingredients are useful herein as long as it slowly absorbs heat when dissolved in water. The endothermic ingredient useful herein includes inorganic salt or inorganic hydrates of ammonia, alkali metals, calcium, urea, simple saccharides and mixtures thereof. Nonlimiting examples of suitable inorganic salt are crystalline phosphates, sulfates, carbonates, nitrates, and the like. Sodium phosphate salts, sodium ammonium phosphate salts, and ammonium phosphate salts are generally preferred due to their relatively high heat absorption and ability to maintain fine crystal morphology despite repeated dissolving and re- precipitation of crystals. Examples of sodium phosphate salts are disodium hydrogen phosphate, sodium dihydrogen phosphate, trisodium phosphate, and hydrates thereof. Examples of sodium ammonium phosphate salts and ammonium phosphate salts are sodium ammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, triammonium phosphate, and hydrates thereof. These salts may be used singly or in combinations of two or more; preferably, the combination of at least one sodium phosphate salt and at least one sodium ammonium phosphate salt or ammonium phosphate salt.

Examples of inorganic salts other than phosphates are sodium carbonate, sodium hydrogen carbonate, potassium sodium carbonate, sodium chromium carbonate, sodium scandium carbonate, sodium cerium carbonate, sodium sulfate, and hydrates of the above. These may be used alone, but preferably are used with the phosphates listed above for the purpose of controlling crystal precipitation and dissolving temperature.

In one embodiment, endothermic reactions need not be limited to the dissolution of endothermic ingredients in water. Endothermic reactions occur when a reaction requires more energy to break the bonds of the reactants than energy given off in forming new bonds. As the reaction progresses, energy is absorbed from the surroundings and a decrease in temperature is observed. Thus, solid/solid chemical reactions can occur which are endothermic. Examples of ingredients used for such reaction would involve hydrated inorganic salts in their solid form reacting with selected solid ammonium salts. A more specific example would be the reaction of barium hydroxide octahydrate with ammonium chloride. As the reaction begins the eight hydrated water bonds begin to break. Water is not involved in further bond breaking or making, so the net overall energy balance requires that heat be absorbed from the surroundings, thus an endothermic reaction.

Solid/solid endothermic reactions involving hydrates may be further prolonged by the presence of one or more endothermic ingredients mentioned above. Firstly, as the two solid portions combine bonds of hydrated water are broken and water is released, initiating an endothermic reaction. Secondly, the presence of liquid water provides a solvent for a second or third endothermic ingredient to dissolve, thus prolonging the duration of the cooling and/or lowering the temperature further. Preferably, the cooling composition of the present invention is packed in a water-impermeable film. Such film is typically a synthetic resin film having strength sufficient to support handling during use and transport. Examples of the synthetic films include polyethylene, polypropylene, polyester, nylon, polyvinyl chloride, polyvinylidene chloride, polyisocyanate and other synthetic resins. Composite films and blends of these materials are also available. Polyester, nylon, polyethylene, polypropylene, and composite films, blends, or laminates of these materials are preferred.

To prevent agglomeration, provide fine crystal morphology, and impart a soft feel, the cooling composition may further include polymeric humectants, thickeners, polymeric flocculants, or other crystal modifiers. These can be also employed to improve safety by preventing the liquid from spilling over the body if and when the film is broken. These compounds may be used singly or in combinations of two or more. C. Phase change material It is preferred that the phase change material of the present invention undergoes a phase transition at a temperature of from about 3 to about 25°C. This is because the cooling article of the present invention avoids the exposure to users of extreme cold temperature, e.g. 5 to 10°C, and provides a cool but comfortable temperature to users. Preferably, the phase change material is in the form of fluid or gel.

Examples of phase changing materials which fall into the above category are numerous and their reactivity, cost, availability, and toxicological properties vary widely. Examples include pivaldehyde, 3-bromoacetophenone, acrylic acid, adiponitrile, 2-nitroanisole, 3-chlorobenzaldehyde, benzene, ortho- dichlorobenzene, 3,3'-dimethylbiphenyl, 3,3-dimethyl-2-butanol, 1-hexadecene para-cresol, cylcooctane, 1-decanol, diethylsulfoxide, 1 ,4-dioxane, ethanolamine, formic acid, 1-heptadecene, 1-hexadecyne, methyl laurate, nonanoic acid, olelyl alcohol, 1-pentadecene, methacrylic acid, pyruvic acid, methyl sorbate, tetradecane, pentadecane, among others. Examples of preferred phase change material is selected from the group consisting of liquid, linear or branched hydrocarbon oils, C₁₀-18 liquid fatty alcohols or derivatives, and mixtures thereof.

When a material undergoes a phase transition, there is a change in the enthalpy of the material. The phase change of the phase changing materials of the present invention all involve the freezing / melting phase transition and the enthalpy changes for this transition are often referred to as "enthalpy of melting" or "enthalpy of fusion". Enthalpy changes at a particular temperature are generally given as

ΔH = KA/m (1 )

wherein ΔH is the change in enthalpy, K is a calibration constant of the differential scanning calorimeter (DSC), A is the area of the curve of the phase transition, and m is the mass of the sample undergoing phase transition. Preferably the enthalpy of melting of the phase changing material is greater than 20 Joules/gram at its melting temperature. Using a phase changing material having at greater than 20 Joules/gram allows an efficient use of the phase changing material; use of a phase changing material with a lower enthalpy of melting value will require use of additional mass of the material to achieve the overall effect and will add unneeded bulk, weight and expense to the product. Any materials which have the above properties can be used as the phase change material herein. Preferably, the phase change material useful herein is non-toxic and safe to human and has pleasant odor. Even though there is no direct exposure to human skin with this invention, such phase change materials are preferred because should there accidentally be a puncture in the package, there will be no extraordinary harm.

The phase change material of the present invention is contained in a flexible pouch. Preferably the pouch useful herein can have a plurality of pockets in order to prepare flexibility of the pouch.

Figures 2 and 3 show a band-type product for the body comprising a cooling article 10 packed into a flexible material 40, wherein the cooling pad 20 is located adjacent the phase change material 30. The flexible material 40 has a upper wall 42 and a bottom wall 44. Both of the upper walls 42 have a closing means in order to fasten or stitch both upper walls of the flexible material 40 to form a tube-like envelope into which the cooling article 10 is packed. Preferably, the cooling article in the flexible material 40 can be attached by a belt-like configuration or packed in a cloth or mesh-like bag stitched to the inside of the flexible material 40 so as to fix it to the flexible material during use.

To apply the cooling article 10 contained in the flexible material 40, two elastic bands 50 are connected to both side walls of the flexible material 40. One preferred use for the band is as a headband, which is placed on the forehead of a wearer. Other preferred uses for the band include products which have a similar structure to that shown in Figure 2, but having different sizes. Such may be used for cooling other areas of the body, e.g., the back of neck, shoulders, arms, knees, and legs. Figure 4 is one embodiment applying the cooling article of the present invention which shows a sun visor 70. A cooling article (not shown in Figure 4) is enveloped in a forehead portion 72 of the sun visor 70. The sun visor 70 has an opening 74 at the top of the forehead portion 72.

Figure 5 is another preferred embodiment showing an eye mask. Cooling pads are enveloped between a body of the flexible material 62 and a cover welded at the bottom portions 68. After the cooling pads are enveloped, the upper portions 66 of both the body 62 and cover 64 of the flexible material are sealed with hook and lap material such as Velcro™ or snaps.

EXAMPLES

The following examples further describe and demonstrate embodiments within the scope of the present invention. The examples are given solely for the purpose of illustration and are not to be construed as limitations of the present invention, as many variations thereof are possible without departing from the spirit and scope of the invention. Preparation of Cooling Article

A 25 g portion of sodium sulfate decahydrate is placed in an aluminum foil pouch and sealed. This pouch is placed in a polyethylene/nylon laminate wrap containing 40g of a urea/ammonium chloride mixture (60/40) and the plastic wrap was heat sealed to prepare a cooling pad. This cooling pad is activated by breaking the inner foil pouch and shaking the solid contents.

To prepare cooling article-A, the cooling pad and a phase changing material packet containing 3g of tetradecane in a 4 x 17 cm² sealed polyethylene/nylon laminate pouch is placed into a band-like material which is similar to that depicted in Figure 2. Cooling article-B is similarly prepared by the above method, except that the phase changing material is omitted. Test Method

The temperature profile of both articles (A and B) are measured on a metal tray by the method below.

Evaluation of the cooling pads with and without the presence of various phase changing materials was performed with a Mettler DL70ES titrator equipped with a Mettler RS232C interface and a Pt 100 thermal sensor which had been previously calibrated with ice water. Simulation of human skin temperatures employed a metal tray set inside a thermostated (35°C) oil bath. The thermal sensor was attached to the cooling pad before activation and the unactivated pad was allowed to warm to the elevated temperature. After this, the pad was activated and once again set on the tray within the thermostated oil bath. The temperature of the packet was measured at 5 minute intervals until the temperature reached or exceeded 30°C. Similar measurements were made with the combination of endothermic packet with selected types and amounts of phase changing materials.

As shown in Table 1 , the cooling article of the present invention provides desirable cooling properties. For example, the minimum temperature of the cooling article of the present invention is achieved at 17.5°C by 30 minutes from the start of cooling sensation. Such minimum temperature is still higher than one which is measured with regard to a cooling pad itself without support of a phase change material. Thus, it can be seen that an uncomfortably cold temperature at the outside of use is avoided. The temperature of the cooling article at 4 hours from the time of generated the cold temperature remains less than 30°C. The cooling article of the present invention show that the bitter cold temperature of the endothermic packet is moderated with the use of the phase change material. The behavior makes the overall product, whether in the form of headband, wrap, sun visor, etc., more comfortable to wear. When used in the form of headband, wrap, sun visor, etc., this invention allows complete mobility in movement while extending the time period for comfortable use.

It is understood that the examples and embodiments desired herein are for illustration purposes only and for various modifications or changes in light there of will be suggested to one of ordinary skill in the art without departing from the scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A cooling article comprising:

(1 ) a cooling pad including a cooling composition capable of generating a cold temperature for a period of time; and

(2) a phase change material, which prolongs the period of time during which the cold temperature is generated.

2. The cooling article according to Claim 1 , wherein the phase change material has a phase transition temperature from about 3 to about 25°C.

3. The cooling article according to Claim 1 , wherein the phase change material is selected from the group consisting of liquid hydrocarbon oils, C-ιo-18 liquid fatty alcohols or derivatives, and mixtures thereof.

4. The cooling article according to Claim 1 , wherein the article further comprises a flexible material to fix the phase change material with the cooling composition to body, wherein the one surface of the phase change material faces to the body.

5. The cooling article according to Claim 1 , wherein the cooling pad comprises a cooling composition selected from the group consisting of ice cubes, cold-water, heat-storing antifreeze solution, a polymeric cold- retaining agents, and endothermic ingredients.

6. The cooling article according to Claim 5, wherein the cooling composition is a endothermic ingredient, such that, upon combining with water, an endothermic reaction is generated.

7. The cooling article according to Claim 6, wherein the endothermic ingredient is selected from the group consisting of inorganic salts or inorganic hydrates of ammonia, alkali metals, calcium, urea, and mixtures thereof.

8. The cooling article according to Claim 1 , wherein the temperature of the cooling article is less than about 30°C for at least twice as long as without the phase change material after the cold temperature is generated.

9. The cooling article according to Claim 1 , wherein the temperature of the cooling article is less than about 30°C for at least about 3 hours after the cold temperature is generated.

10. A method for cooling a human or an animal body comprising the step of contacting the body with the cooling article of Claim 1.