US3912154A

US3912154A - Container end closure attachment

Info

Publication number: US3912154A
Application number: US320695A
Authority: US
Inventors: Joseph L Godar
Original assignee: American Can Co
Current assignee: Rexam Beverage Can Co
Priority date: 1973-01-03
Filing date: 1973-01-03
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14
Also published as: JPS49102482A; JPS6050655B2; CA993816A; GB1443986A

Abstract

An improved means for attaching a metal end closure to a container body having an upstanding straight marginal edge portion wherein the end closure is provided with a peripheral channel defined by inner and outer depending straight wall portions, the inner depending straight wall portion merging with the central panel of the end closure, and said channel including said inner and outer depending straight wall portions being bonded to the upstanding straight marginal edge portion of said container body by means of a suitable thermoplastic adhesive.

Description

United @tates Patent [191 Godar CONTAINER END CLOSURE ATTACHMENT [75] Inventor: Joseph L. Godar, Wauconda, Ill.

[73] Assignee: American Can Company,

Greenwich, Conn.

22 Filed: Jan. 3, 1973 21 Appl. No.: 320,695

[52] US. Cl. 229/55; 156/69; 156/331; 156/334; 220/67; 260/857 UN; 260/876 B;

[51] Int. CI. B65D 3/10; B65D 7/42 [58] Field of Search 229/55, 5.6; 220/66, 67, 220/81 R; l61/102,105,106,107,125, 139,

B, 876 B, 857 UN, 18 N, 24; 156/334, 69;

117/132 BE, 132 C, 155 R, 155 UA, 75

[56] References Cited UNITED STATES PATENTS 2,467,182 4/1949 Beattie 229/5.5 X 3,251,708 5/1966 Schmetterer. 1 17/132 BE X 3,303,954 2/1967 Beaudet 161/186 X 3,322,318 5/1967 Felton et al 229/56 X 3,406,891 l0/l968 Buchner et a1.

3,427,269 2/1969 Davis et a1. 3,430,805 3/1969 Buchner et al. 220/66 3,448,178 6/1969 Flanagan 260/897 B 3,497,466 2/1970 Markulin et al. 1 17/75 X 3,615,106 10/1971 Flanagan et al 260/897 B X 3,630,980 12/1971 Russell 260/93.3 X 3,635,861 l/1972 Russell 260/93.3 X 3,645,822 2/1972 Widiger et a1 161/256 X 3,703,434 11/1972 Schaff 161/186 X 3,722,732 2/1973 Edlund 229/55 X 3,736,281 5/1973 Russell 260/876 B X OTHER PUBLICATIONS Cagle, Charles V., Handbook of Adhesive Bonding, pp. 81 to 8-5 relied on.

Primary Examiner-George F. Lesmes Assistant ExaminerAlan T. McDonald Attorney, Agent, or FirmRobert P. Auber; Ernestine C. Bartlett; Joseph J. Orlando ABSIRACT An improved means for attaching a metal end closure to a container body having an upstanding straight marginal edge portion wherein the end closure is provided with a peripheral channel defined by inner and outer depending straight wall portions, the inner depending straight wall portion merging with the central panel of the end closure, and said channel including said inner and outer depending straight wall portions being bonded to the upstanding straight marginal edge portion of said container body by means of a suitable thermoplastic adhesive.

5 Claims, 2 Drawing Figures US. Patent Oct. 14, 1975 (3 wwwwwwmmwi i i ii i i Iii! xvv dv/il fl AV v CONTAINER END CLOSURE ATTACHMENT The present invention relates generally to a means for attaching metallic end closures to container bodies. More particularly, the present invention relates to an improved means for attaching metallic end closures to container bodies having upstanding straight marginal edge portions wherein the structure of the end closure in cooperation with suitable bonding agents produces a container adapted for containing liquids under pressure.

There are at the present time several different methods of attaching metal end closures to container bodies, whether the container body be formed of metal, of a composite material, or of plastic. Usually such end closures are attached to the container body by means of some form of mechanical engagement between the end closure and the marginal edge portion of the container body. In fact, without some form of mechanical engagement of the end closure to the container body it has generally been impossible to contain a pressurized product within a container. Furthermore, it has been found necessary to use sealing compounds in the end seams for the purpose of hermetically sealing the containers and preventing leakage of the contents therefrom.

Over the years many attempts have been made to improve end seaming techniques primarily for the purpose of economy and secondarily to improve the aesthetic appearance of the containers thereby making the containers more appealing to the consuming public. Exampples of such attempted improvements are illustrated by U.S. Pat. No. 2,467,182, to Beattie, granted Apr. 12, 1949, U.S. Pat. No. 2,303,322, to Bigger,

granted Dec. 1, 1942, and U.S. Pat. No. 2,801,648, to Anderson et al., granted Aug. 5, 1957. The Beattie patent discloses an end attachment means wherein the metallic end closure comprises a peripheral channel defined by inner and outer depending straight wall portions, the inner depending straight wall portion merging at its lowest edge with the central panel of the end closure. Sealing compound covers the interior of the channel which is positioned about the upstanding straight marginal edge portion of the container body and the depending straight walls defining the channel are crimped to mechanically engage the upstanding edge portion of the container body. The Bigger patent discloses a somewhat similar end seam construction wherein the mechanical engagement of the marginal edge portion of the side wall of the container body by the metallic end closure is accomplished by providing a hemmed curl in the outer depending straight wall of the channel portion which is pressed into the side wall of the container body at the marginal edge thereof in order to lock the end closure thereon. The sealing compound or adhesive is applied in the Bigger patent along the inside of the inner depending straight wall portion and the bottom of the channel portion in order to aid in securing the end closure onto the container body. It is to be noted that in both the Beattie and Bigger patents it is mechanical means that is primarily used to secure the end closure onto the container body while the sealing compound or adhesive is used in the end seam for the secondary purpose of hermetically sealing the container used, to a much less extent, in securing the end closure onto the container body. With respect to the Anderson et al. patent, a lap seam is shown which is formed solely by means ofa bonding agent which securely bonds the depending skirt or wall portion of a metallic end closure to the upstanding straight marginal edge portion of the side wall of the metal container body. It is to be pointed out that a major disadvantage of this construction is that the raw metal edge at the marginal edge portion of the side wall of the container body, which is usually susceptible to attack, is exposed to the contents of the container since the bonding agent is applied only to the outer surface of the marginal edge portion of the side wall of the container body. In addition, with respect to the Anderson et al. construction, the bonding agent employed with this end seaming technique must necessarily be very strong and therefore expensive because of the limited area over which the bonding agent is used. Still, the Anderson et al. patent does not disclose that such a construction will contain a pressurized product.

Yet another purpose of improved end seaming techniques is to minimize the effect of the end seam thickness. Relatively thick end seams, usually termed chimes, result in container abuse problems as well as packaging difficulties. Thus, a recent innovation in this area is the necked-in metal container wherein the marginal edge portion of the container body is necked-in thereby resulting in an end seam which does not extend beyond the diameter of the container. However, the production of necked-in containers is relatively expensive, requiring a higher working of the metal in the side wall of the container, and, furthermore, as the body wall thickness is made smaller and less resistant to vertical pressures, the necked-in configuration provides a ready site for beginning the collapse of the body wall when subjected to vertical pressures.

It is, therefore, a primary object of the present invention to provide an improved means for attaching a metalllic end closure to a container body which eliminates any mechanical attaching means and is economical, simple in design, and as effective as prior art end closure attaching means and also minimizes the effect of end seam chimes.

The above object, as well as others which will hereinafter become apparent, is accomplished according to the present invention by providing improved means for the attachment of metallic end closures to container bodies, whether of metallic, composite, or plastic construction, wherein the end closure is provided with a peripheral channel defined by inner and outer depending straight wall portions, the inner depending straight wall portion merging with the central panel of the end closure, and said channel including said inner and outer depending straight wall portions being bonded to the straight marginal edge portion of said container body by means of a thermoplastic adhesive.

The present invention will be described and understood more readily when considered together with the embodiment shown in the accompanying drawing, in which:

FIG. 1 is a perspective view of a container having an end closure attached thereto in accordance with the present invention; and

FIG. 2 is an enlarged partial cross-sectional view of the container of FIG. 1 taken along line 22 of FIG. 1.

Referring now to the drawing, there is shown in FIG. 1 a container, generally designated 10, which, although shown to be a fiber or composite type container, may

also be a thin walled container constructed of metal, plastic, etc. Container is comprised of a container body, generally designated 12, which, if constructed of a fibrous material, is formed by helically winding a sheet of composite material into the cylindrical shape shown having a spiral seam, generally designated 14. The open ends of container body 12 are covered by a pair of metallic end closures, generally designated 16 and 18, which are joined to container body 12 at

end seams

20 and 22, respectively.

As clearly seen in FIGS. 1 and 2, end closure 16, which may be constructed identically with end closure 18, is formed having a generally planar central panel, designated 24, surrounded by a peripheral reinforcing groove, generally designated 26. Reinforcing groove 26 merges at its outer edge, designated 28, into an upwardly depending substantially straight inner wall portion, generally designated 30, the upper end of which merges with an outwardly extending flange, designated 32. Flange 32 merges with a downwardly depending substantially straight outer wall portion 34, which is formed parallel with depending inner wall portion 30. Inner and outer depending straight wall portions and 34 define a channel, generally designated 36, which peripherally surrounds the end closure.

End seam 20, which joins end closure 16 to contaianer body 12, and which may be identical to end seam 22 which joins end closure 18 to container body 12, is formed by the girdling of the upstanding straight marginal edge portion, generally designated 38, of the open end of container body 12 by channel 36 defined by the inner and outer depending

straight wall portions

30 and 34. As can readily be seen in FIG. 2, the thickness of chime of the end seam 20 is relatively small, amounting to only three thicknesses of material and only a single thickness of material beyond the side wall of container body 12.

The main feature of the invention is the provision of an adhesive, generally designated 40, in channel 36 which adhesively bonds end closure 16 to container 12. As seen in FIG. 2, the adhesive 40, which bonds the surface 42 of depending straight inner wall portion 30 facing channel 36 to the inner surface 44 of the upstanding straight marginal portion of container body 12, is subjected to shear stress produced by the internal forces within the-container rather than peel stress. It is to be appreciated in this context that the peel strength of most adhesives is very weak in comparison to the shear strength of the adhesives, thus, the present construction takes full advantage of this material property of adhesives. This form of construction, wherein the inner depending straight wall portion 30 is substantially straight thereby decreasing the peel stress to which adhesive is subjected, increases the buckle resistance of the end closuure at the reinforcing groove 26. In addition, adhesive 40 bonds surface 46, which faces channel 36, of downwardly depending outer wall 34 to outer surface 48 of upstanding straight marginal edge portion 38 of container body 12. Thus, the surface area of container body 12 bonded to end closure 16 is relatively large, being the inner and

outer surfaces

44 and 48 of marginal edge portin 38.

It is to be noted that the surfaces of the end closure and container body which are bonded together are protectively coated, by

coating materials

50 and 52 respectively, in order to insulate the materials from which the container is formed from the contained product, which,

in the usual case, is corrosive. It is therefore necessary that the adhesive chosen to attach end closure 16 to container body 12 be coordinated with the coating materials applied to the surfaces of the end closure and the container body. Thus, heat activated adhesives, based on an ethylene-acetate terpolymer, a butadienestyrene-block copolymer, and a polyamide polymer have successfully been utilized in attaching coated end closures to coated fiber or metallic container bodies. The

protective coatings

50 and 52 which are utilized with the above identified .thermoplastic adhesives are, with respect to a metallic end closure, a modified epoxy type coating and, with respect to a metallic container body, a vinyl type coating over a modified epoxy type base coating, and with respect to a composite body, a modified epoxy type coating together with slip compound, all of which are commonly used in the industry for the purposes of protecting thecontainer materials from corrosion, etc. The slip compound utilized in the coating for the composite container body is specifically for the purpose of lubrication between the container body being formed and the mandrel with which the body is formed.

The ethylene-vinyl-acetate acid terpolymer based adhesive is produced by mixing 65 parts by weight of an ethylene-vinyl-acetate organic acid terpolymer with 35 parts by weight of a polyterpene resin, this is then dissolved in 200 parts by weight of a heated solvent, such as an aromatic petroleum hydrocarbon. When the solution cools it becomes a hard gel which may be stored until use. When the adhesive is to be applied it is reheated to about 150 F., the channel 36 of end closure 16 or the straight marginal edge portion 38 is lined with the adhesive and then heated at 200 F. to drive off the solvent. The adhesive lined ends or container bodies may then be stored until ready for attachment at which time the adhesive is reactivated by heating to 300 F. The reactivated adhesive is then ready to adhesively bond the end closures to the container bodies. The ethylene-vinyl-acetate organic acid terpolymer preferably has a 20 percent by volume vinyl acetate content with an acid number of six. An example of a preferred ethylenevinyl-acetate organic acid terpolymer is manufactured by E. I. DUPONT DE NEMOURS and Company and designated EP-3656-9.

The butadiene-styrene-block copolymer based adhesive is produced by mixing 56.71 parts by weight of a styrene-butadiene-block copolymer, having 25 percent by volume of the styrene molecule and percent by volume of the butadiene molecule, with 21.22 parts by weight of a polyterpene resin, 21.22 parts by weight of a commarone-indene resin, and 0.85 parts by weight of an anti-oxidant. This is dissolved in 200 parts by weight of a heated solvent, such as an aromatic petroleum hydrocarbon. When the solution cools it thickens slightly and can be applied without the necessity of reheating. Like the ethylene-vinyl-acetate acid terpolymer based adhesive it can be stored until ready for use and the application and results are also similar. Examples of a commercially available styrene-butadiene-block copolymer suitable for such use are Kraton l 101 and l 102 as produced by the Shell Chemical Company.

The polyamide copolymer based adhesive is pro-' duced by mixing 75 parts by weight of a polyamide, having a meltindex range of 6 to 15 at 401 F. and which also must be soluble and remain a liquid solution at room temperature, with 25 parts by weight ofa polyterpene resin. This is then dissolved in heated solvents comprising 200 parts by weight of an aromatic petroleum hydrocarbon, 60 parts by weight of an acetone free diacetone alcohol and 60 parts by weight of an isopropyl alcohol. The solvents are heated to about 150 F. in order to effect a good solution of the ingredients. The adhesive remains a homogenous liquid mixture when cooled to room temperature and can be applied anytime as such and heated to drive off the solvents. The adhesive can then be reactivated and the ends applied to the container bodies by heating the adhesive to about 400 F. Examples of commercially available polyamides suitable for such use are Milvex 1000 and Milvex 4000 produced by General Mills Inc.

It is to be noted that adhesive 40, as clearly seen in FIG. 2, fully protects the raw edge, generally designated 54, of the marginal edge portion 38 of container body 12. Thus, it is impossible for the contents of container to contact edge 54 which would corrode in the case of a metallic container body 12 or deteriorate in the case of a composite container body 12 due to wicking.

It is understood that the foregoing general and detailed descriptions are merely explanatory of the present invention and are not to be interpreted as restrictive of the scope of the following claims.

What is claimed is:

l. A container, suitable for containing liquids under pressure, comprising:

a body portion having an upstanding marginal edge portion and a metallic end closure seamed to and covering at least one open end of said body portion, at least the portions of the surfaces within the seam having an epoxy-resin or vinyl-resin coating or combinations thereof applied thereto;

said end seam being derived in the absence of mechanical locking of the end closure to the body portion and comprising (a) a channel surrounding the periphery of the central panel of said end closure and defined by inner and outer depending straight wall portions wherein the inner depending straight wall porption merges into the central panel of said end closure and the outer depending straight wall portion is parallel to the inner wall portion and merges with an outwardly extending flange and b) a thermoplastic adhesive bonding the inner surfaces of the channel to the inner and outer surface of the upstanding marginal edge portion of the body; said thermoplastic adhesive being selected from those derived from the group of:

l. a mixture consisting essentially of about 65 parts by weight of an ethylene-vinyl acetate-organic acid terpolymer having a 20 percent by volume vinylacetate content and an acid number of 6 and about 35 parts by weight of a polyterpene resin;

2. a mixture consisting essentially of about 56 parts by weight of a styrenebutadiene block copolymer having about 25 percent by volume styrene and about percent by volume butadiene, about 21 parts by weight of a polyterpene resin and about 21 parts by weight of a coumaroneindene resin; and

3. a mixture consisting essentially of about 75 parts by weight of a polyamide having a melt index range of from about 6 to about 15 at 401F and about 25 parts by weight of a polyterpene resin.

2. The container as defined in claim 1 wherein said thermoplastic adhesive is derived from a mixture consisting essentially of about65 parts by weight of an ethylene-vinyl acetate-organic acid terpolymer having a 20 percent by volume vinylacetate content and an acid number of 6 and about 65 parts by weight of a polyterpene resin.

3. The container as defined in claim 1 wherein said thermoplastic adhesive is derived from a mixture consisting essentially of about 56 parts by weight of a styrenebutadiene block copolymer having about 25 percent by volume styrene and about 75 percent by volume butadiene, about 21 parts by weight of a polyterpene resin and about 21 parts by weight of a coumaroneindene resin. 4. The container as defined in claim 1 wherein said thermoplastic adhesive is derived from a mixture consisting essentially of about 75 parts by weight of a polyamide having a melt index range of from about 6 to about 15 at 401F and about 25 parts by weight of a polyterpene resin.

5. The container as defined in claim 1 wherein said body portion comprises fibrous material.

Claims

1. A MIXTURE CONSISTING ESSENTIALLY OF ABOUT 65 PARTS BY WEIGHT OF AN ETHYLENE-VINYL ACETATE-ORGANIC ACID TER-

1. A CONTAINER, SUITABLE FOR CONTAINING LIQUIDS UNDER PRESSURE, COMPRISING: A BODY PORTION HAVING AN UPSTANDING MARGINAL EDGE PORTION AND A METALLIC END CLOSURE SEAMED TO AND COVERING AT LEAST ONE OPEN END OF SAID BODY PORTION, AAT LEAST THE PORTIONS OF THE SURFACES WITHIN THE SEAM HAVING AN EPOXY-RESIN OR VINYL-RESIN COATING OF COMBINATIONS THEREOF APPLIED THERETO, SAID END SEAM BEING DRIVED IN THE ABSENCE OF MECHANICAL LOCKING OF THE END CLOSURE TO THE BODY PORTION AND COMPRISING (A) A CHANNEL SURROUNDING THE PERIPHERY OF THE CENTRAL PANEL OF SAID END CLOSURE AND DEFINED BY INNER AND OUTER DEPENDING STRAIGHT WALL PORTIONS WHEREIN THE INNER DEPENDING STRAIGHT WALL PORPTIONS MERGES INTO THE CENTRAL PANEL OF SAID END CLOSURE AND THE OUTER DEPENDING STRAIGHT WALL PORTION IS PARALLEL TO THE INNER WALL PORTION AND MERGES WITH AN OUTWARDLY EXTENDING FLANGE AND B) A THERMOPLASTIC ADHESIVE BONDING THE INNER SURFACES OF THE CHANNEL TO THE INNER AND OUTER SURFACE OF THE UPSTANDING MARGINAL EDGE PORTION OF THE BODY, SAID THERMOPLASTIC ADHESIVE BEING SELECTED FROM THOSE DERIVED FROM THE GROUP OF:

2. a mixture consisting essentially of about 56 parts by weight of a styrenebutadiene block copolymer having about 25 percent by volume styrene and about 75 percent by volume butadiene, about 21 parts by weight of a polyterpene resin and about 21 parts by weight of a coumaroneindene resin; and

2. A MIXTURE CONSISTING ESSENTIALLY OF ABOUT 56 PARTS BY WEIGHT OF A STYRENEBUTADIENE BLOCK COPLYMER HAVING ABOUT 25 PERCENT BY VOLUME STYRENE AND ABOUT 75 PERCENT BY VOLUME BUTABIENE, ABOUT 21 PARTS BY WEIGHT PF A POLYTERPENE RESIN AND ABOUT 21 PARTS BY WEIGHT OF A COUMARONEINDENE RESIN, AND

3. The container as defined in claim 1 wherein said thermoplastic adhesive is derived from a mixture consisting essentially of about 56 PARTS by weight of a styrenebutadiene block copolymer having about 25 percent by volume styrene and about 75 percent by volume butadiene, about 21 parts by weight of a polyterpene resin and about 21 parts by weight of a coumaroneindene resin.

3. A MIXTURE CONSISTING ESSENTIALLY OF ABOUT 75 PARTS BY WEIGHT OF A POLYMIDE HAVING A MELT INDEX RANGE OF FROM ABOUT 6 TO ABOUT 15 AT 401*F AND ABOUT 25 PARTS BY WEIGHT OF A POLTERPENE RESIN.

3. a mixture consisting essentially of about 75 parts by weight of a polyamide having a melt index range of from about 6 to about 15 at 401*F and about 25 parts by weight of a polyterpene resin.

4. The container as defined in claim 1 wherein said thermoplastic adhesive is derived from a mixture consisting essentially of about 75 parts by weight of a polyamide having a melt index range of from about 6 to about 15 at 401*F and about 25 parts by weight of a polyterpene resin.