EP0015272A1

EP0015272A1 - Containers for beverages and the like

Info

Publication number: EP0015272A1
Application number: EP79900616A
Authority: EP
Inventors: Kazuaki Fukuoka
Original assignee: Norton Simon Inc
Current assignee: Norton Simon Inc
Priority date: 1978-05-24
Filing date: 1979-12-17
Publication date: 1980-09-17
Also published as: DE2950514A1; CA1133837A; BE876506A; SE8000539L; IT7968101A0; IT1192775B; GB2036684A; WO1979001113A1; AU4711079A; BR7908695A; AU525365B2; EP0015272A4; NL7903812A

Abstract

Un recipient (12) pour materiaux coulants y compris des liquides tels que jus de fruits et autres boissons comprend un corps tubulaire (14) compose de cinq plis relies entre eux, le premier, le troisieme et le cinquieme plis (16) (18) (20), chacun etant forme d'une polyolefine allongee enroulee en spirale dont les bords sont recouverts et lies par ceux des replis adjacents pour former une couche cylindrique. Le second et le quatrieme plis sont formes d'un materiau en feuille de papier pour gobelet, allongee et enroulee en spirale qui est plus epais que le materiau en feuille de polyolefine et dont les bords sont en accoles avec les replis adjacents pour former une couche cylindrique. Dans un autre recipient (50), le corps tubulaire (52) se compose d'un premier (le plus a interne) pli (58) d'un materiau en feuille de polyolefine ayant des replis recouverts, un second pli (60) d'une feuille d'aluminium dont les deux faces sont laminees avec du papier fin (61) (63), un troisieme pli (68) de papier d'emballage fort ayant des replis en accoles et un quatrieme pli (66) d'un materiau en feuille de polyolefine ayant des replis recouverts. Dans un autre recipient (80), le corps tubulaire (82) se compose d'au moins deux couches, la couche la plus interne (94) etant formee avec une feuille de resine synthetique ayant des replis imbriques et ayant un joint ou soudure continue (98) le long de la partie imbriquee et un second joint (100) adjacent au premier de maniere a former et a definir une partie molle (104) du chevauchement ou imbrication prevue pour le rattrapage en reponse a une pression negative dans le recipient. Le corps tubulaire du recipient est hermetiquement ferme avec des fermetures aux extremites (84) (85) dont l'une au moins peut etre formee d'un materiau en feuille rigide ayant une flexibilite suffisante et une partie deformee ballonnee initialement vers l'exterieur de maniere a ce que la partie deformee puisse s'incurver vers l'interieur en vue de reduire la pression negative interieure, comme celle quiA container (12) for flowable materials including liquids such as fruit juices and other drinks comprises a tubular body (14) composed of five plies connected together, the first, the third and the fifth ply (16) (18) (20), each being the form of an elongated polyolefin wound in a spiral, the edges of which are covered and linked by those of the adjacent folds to form a cylindrical layer. The second and fourth plies are formed from a sheet paper material for a beaker, elongated and spirally wound which is thicker than the polyolefin sheet material and whose edges are joined with the adjacent folds to form a layer cylindrical. In another container (50), the tubular body (52) consists of a first (innermost) ply (58) of a polyolefin sheet material having covered folds, a second ply (60) d '' a sheet of aluminum, the two sides of which are laminated with thin paper (61) (63), a third ply (68) of strong wrapping paper having folded edges and a fourth ply (66) of a polyolefin sheet material having covered folds. In another container (80), the tubular body (82) consists of at least two layers, the innermost layer (94) being formed with a sheet of synthetic resin having overlapping folds and having a joint or continuous weld. (98) along the nested part and a second joint (100) adjacent to the first so as to form and define a soft part (104) of the overlap or nesting provided for catching up in response to negative pressure in the container. The tubular body of the container is hermetically closed with closures at the ends (84) (85) at least one of which may be formed from a rigid sheet material having sufficient flexibility and a deformed part initially bloated outwardly. so that the deformed part can curve towards the inside in order to reduce the internal negative pressure, like that which

Description

DESCRIPTION

CONTAINERS FOR BEVERAGES AND THE LIKE

Technical Field

This invention relates to containers for flow- able materials including liquids such as fruit juices and the like, and to a method of canning such materials in sealable containers wherein the materials are heat treated and packaged. More particularly, it relates to tubular wall members for forming tubular containers in which flowable materials, e.g., a beverage such as fruit juice, are sealed and packaged for long-term storage. In addi- tion, the invention has to do with a cap or closure member for hermetically sealing the aforesaid containers, and which is capable of alleviating internal negative pres¬ sure.

Background Art

Heretofore, containers or "cans" for packaging flowable or pourable materials including liquids, par¬ ticularly beverages such as fruit juice and other food- stuffs, have been generally formed of glass, tinplate, aluminum and the like. Although these materials are satisfactory from the standpoint of airtightness and strength, difficulty is often encountered in disposing of these materials after use, in a manner consistent with environmental considerations, and a long-felt need has therefore existed for a container which can be so readily disposed of. From the standpoint of economy of resources, it is also desirable that containers be made of inexpen¬ sive substitutes for increasingly expensive conventional materials.

OMPI In addition, the laws in many jurisdictions require that, in the processing of certain foodstuffs such as fruit or fruit juice, the product be heated or pasteurized at or above a certain temperature before being put in containers and sealed. However, some food¬ stuffs, for example, beverages, when processed in this manner will often contract upon cooling in the container, thereby creating negative pressure, i.e., a pressure below atmospheric. If such containers are formed of materials having little rigidity such as thin aluminum, synthetic resins or plastics, the negative pressure must be relieved without breaking the seal in order to avoid the buildup of unwanted stress on the container and consequent strain leading to unsightly deformation of the container wall, structural damage or even failure of the unit. Alter¬ natively, if the container is made of laminated paper, kraft paper, cup paper or other like sheet material, it may not only be deformed but also, due to the pressure differential between the interior and the exterior of the container, may rupture at the seal between the lid and . side wall, thereby exposing the contents to infection by infiltration from without, e.g., by bacteria, mal¬ odorants and the like, with resulting curtailment of shelf storage life. For this reason, it has been cus- tomary to use materials of such lower rigidity only for containers intended, e.g., for non-pasteurized or car¬ bonated beverages and the like which provide a neutral or positive pressure within the container.

In the past, tinplate has been the material of choice in making blanks for "tin cans" designed to with¬ stand the aforementioned negative pressure due to its greater rigidity, and for airtightness. However, tinplate is relatively expensive compared to cup paper and the newer synthetic resins and the like and also requires

O greater effort in its disposal after use. Furthermore, even in the case of tinplate, some deformation of the can or container as a result of negative pressure cannot be avoided. In the past, ways of coping with this problem have included the means shown in FIG. 1 of the drawings. In particular, end-closure 2_ of can body _1_ is not flat¬ tened but rather, is provided with, say, two concentric convex circular ribs 3_ and to provide flexibility and permit the closure to deform in response to the internal negative pressure and decrease the latter, thereby prevent¬ ing container wall J5 from being dented. The small degree of deformation permitted in closure cover 2_ limits reduc¬ tion in the negative pressure but is enough in the case of containers made of conventional tinplate. However, in the case of containers or cans made of thin aluminum, plastics, cellulose-based sheet material and the like, this approach has not proven satisfactory and does not contribute to a solution of the problem. Therefore, containers designed for packaging materials which nor- mally tend to develop substantial internal negative pressures have not heretofore been made successfully of these materials. Other previous attempts at solving the foregoing problems, as exemplified in U.S. Pat. Nos. 1,963,795; 1,987,817; 2,012,213; 2,027,430; 2,115,340; 2,623,681; 2,982,457; 3,089,630; 3,105,765; 3,160,302; 3,247,869; 3,400,853; 3,457,130; 3,687,351; and 3,716,435, have likewise not proven adequate for their solution.

Accordingly, it is an object of the present invention to provide a tubular member or element which defines the wall of a fully airtight and easily disposable container for sealingly packaging flowable materials including beverages and other foodstuffs for long-term storage. Another object is to provide an improved tubula container wall member or element which effectively protects the contents of the container from impregnation by offensive odors and infectious organisms from without, and which is made of relatively inexpensive and easily disposable materials.

Another object is to provide an improved tubula container and a process for hermetically sealing therein flowable material such as a beverage or other foodstuff, - e.g., fruit juice, which are adapted to respond to and relieve internal negative or sub-atmospheric pressure without breaking the seal.

Another object is to provide a container cover or closure member adapted to respond to and relieve internal negative pressure created, for example, by thermal contraction of the contents of the container, without breaking the seal.

Another object is to provide a container cover or closure member designed so that internal negative pressure created, for example, by thermal contraction within the container, causes the closure cover to become depressed inwardly to an extent not exceeding the degree of thermal contraction, thereby substantially relieving such negative pressure.

Yet another object is to provide fully airtight and easily disposable liquid containers made of materials such as thin aluminum, plastic or synthetic resins, laminated paper, kraft paper, cup paper and the like, which containers are defined by a tubular wall member and by two cover or end-closure members at least one of which end-closure members is adapted to relieve negative pres¬ sure generated within the container. These and other objects of the invention as well as a fuller understanding of the advantages thereof can be had by reference to the following description, drawings and claims.

Summary Of The Invention

The foregoing objects are achieved according to the present invention by the discovery of a novel container for flowable materials including liquids such as fruit juices and other non-carbonated beverages. Broadly, the container comprises a tubular side-wall member her¬ metically sealed at both ends, preferably with at least one deformable end-closure described in greater detail hereinbelow. The tubular side-wall member is preferably cylindrical, i.e., having a circular cross-section. Alternatively, the tubular wall member can have a poly¬ gonal or elliptical cross-section.

According to one aspect of the invention, the tubular wall member of the tubular container comprises a tubular element composed of five plies bonded together, preferably with an adhesive. For descriptive purposes the. plies can be visualized as being numbered from 1 to 5, starting from the inner surface of the tubular element. The first, third and fifth plies are each formed of an elongated helically wound polymeric resin sheet material, preferably polyolefin, e.g., polypropylene. The upper and lower edges of the convolutions of each of the first, third and fifth plies are overlapped with those of'the adjacent convolutions and the overlapped portions are bonded to each other, preferably with an adhesive, to form a tubular layer or ply. The second and fourth plies are formed of a helically wound elongated cellulosic sheet material, preferably cup paper, having abutted convolu- tions and which is desirably thicker than the polymeric sheet material of the first, third and fifth plies. In particular, the first, third and fifth plies each desira has a thickness of between about 0.08 and about 0.12 mm, and preferably about 0.1 mm; and the second and fourth plies each desirably has a thickness of between about 0. and about 0.30 mm, and preferably about 0.25 mm. Very good results are obtained with a container whose side-wa member has a total thickness of about 0.8 mm.

In another aspect of the invention, a tubular container wall member is provided having a novel con¬ figuration which permits the use of inexpensive kraft paper liner sheet material as a substantial constituent the tubular element in applications where such material would otherwise be ineffective for preventing the odor o the container's contents from permeating the container wall and escaping or for preventing an offensive odor from infiltrating the container contents from without. such circumstances, it would have been impossible prior the^*present" invention to use an inexpensive kraft liner paper which, although providing sufficient mechanical strength, would tend to emit or impart to the container contents an offensive odor. .For this reason, the use of cup paper sheet material has heretofore been mandatory. In the present invention, the tubular wall member has a bonded multilayer tubular element comprising, starting from the inner wall surface, a first ply of polymeric sheet material, preferably polyolefin; a second ply of aluminum sheet material both sides of which are laminate by thin paper; a third ply of kraft liner sheet material and a fourth ply of polymeric sheet material, preferably polyolefin. The third ply of kraft liner sheet is desir ably formed of a plurality of layers of such material, preferably two layers. The various plies are preferably bonded to each other, preferably with adhesive. The first, second and fourth plies of the tubular element are preferably each formed of a helically wound elongated sheet material having overlapping convolu¬ tions, the overlapped portions of said convolutions being bonded to each other, preferably with adhesive, to form a tubular ply. Each layer of the second ply is formed of a helically wound elongated sheet material, which is prefer¬ ably thicker that each of the first, third and fourth plies. Further, the edges of adjacent convolutions of each layer of the second ply are in abutment rather than overlapped, to form a tubular layer. The first and second plies each desirably has a thickness of between about 0.08 and 0.12 mm, and preferably about 0.1 mm; each of the kraft liner paper sheets or layers constituting the third ply has a thickness of between about 0.2 and about 0.4 mm, and preferably about 0.3 mm, and the fourth ply has a thickness of between about 0.05 and about 0.1 mm, and preferably about 0.07 mm.

The container of the invention can be her¬ metically sealed at one or both ends with a sealing or closure member according to the present invention after being charged with filler, e.g., a heated liquid. Such closure is formed of rigid sheet material of sufficient flexibility and is provided with an outwardly bulged dish-shaped portion before sealing, whereby said bulged portion is capable of undergoing inward deflection by the negative pressure created in the container due to thermal contraction of its contents. The dish-shaped portion of the closure is desirably bulged to such an outward extent that the volume by which the container is reduced by inward deflection of said portion does not exceed the degree of thermal contraction, but rather corresponds substantially to the thermal contraction of the contents of the container or can, thereby substan- tially relieving such negative pressure. Suitable materials for forming the end-closure include aluminum, plastic, cup paper and the like, with aluminum sheet material beinq especially preferred.

In reference to the above-described sealing or closure member, the bulged portion is formed in the end-closure so as to be inwardly deflected in preference to any deflection or deformation of the side wall by the negative pressure generated in the container. Such end-closure must therefore be designed to initially withstand the negative pressure to a lesser degree than the side wall of the container body. This requires the end-closure to be thinner than would normally be the case with more conventional non-deformable end-closures, and since the heat of the heated container contents tends to lessen the strength of the container body, the end-closure must also be thin enough to compensate for such reduction in strength. On the other hand, a hermetic seal between the end-closure and the container body is usually achieved by folding their peripheries in a -manner which is apparent to those skilled in the container art. Accordingly, with the thinner end-closure of the present invention it may be somewhat difficult to obtain proper hermetic sealing of the container. For instance, when the container wall is of a composite structure made according to the present invention of materials such as cup paper, laminated cup paper sheet and the like and synthetic resin paper, it is difficult to form a lap seam relying on plastic defor- mation of such elements, since these materials, in con¬ trast to metal, have neither malleability nor plasticity. Consequently, the container body is sealed by the end- closure in such a way that the metal end-closure material is adapted to have its periphery folded to rigidly hold the periphery of the container body. However, if the end-closure is made thinner this not only weakens its

OMP clamping force and makes it difficult to obtain a satis¬ factory lap seam but also it requires specially designed sealing apparatus other than those which are conventional and desirable. For these reasons the end-closure cannot be thinned beyond a certain limit and in such cases it is difficult to make an end-closure capable of being optimally inwardly depressed in response to the negative pressure created in the container. In such cases, the container cannot relieve the negative pressure completely. Upon consideration of the foregoing, it follows that aluminum is preferred for use as the end-closure material; however, aluminum is more expensive than the tinplates conven¬ tionally used for container end-closures, thereby increas¬ ing overall cost.

These potential problems are avoided in a further aspect of the invention which provides a process or method of canning goods in a sealable container and an end-closure used for such purpose whereby the negative pressure created,in the container can be sufficiently relieved and a bonding of the container body and the end-closure is fully ensured. In particular, the ini¬ tially outwardly bulged portion of the top end-closure is inwardly depressed by a press or the like as opposed to the previously described aspect of the invention wherein the bulged portion is depressed by the negative pressure created in the container. This avoids the necessity of making the end-closure thinner and facilitates the forma¬ tion of a hermetical lap seam between the open end of the container and the flange of the end-closure. Further, t e sealing apparatus can be of conventional design thereby reducing production cost, while the substantial inward depression of the end-closure affords the desired avoid¬ ance of any buildup in negative pressure. Furthermore, the end-closure of this embodiment of the invention is not

OMPI WIPO - limited to the use of aluminum and the like, but rather, can be formed of conventional tinplate blanks thereby substantially reducing the cost (to about half as much as aluminum) of manufacturing the end-closure.

Although this embodiment has been described with reference to a container whose top end-closure is provided with the bulged portion, it is not limited to this particular construction. For example, the bulged portion can be formed in the bottom end-closure and/or th top-end closure.

In the case where only one end of the container is fitted with the above-described sealing closure, the other end can be fitted with any other suitable conventional closure such as an easy-open top of the pilfer or pull-up tab type which are well-known in the beverage art. Such end-closure can be made of any convenient material, e.g., aluminum, and. is joined to the container body before the latter is charged with filler.

In containers of the invention described hereinabove where the volume of the contents is on the order of 250 ml or less, the surface area of the pressure responsive end-closure is sufficiently large relative to the total surface area of the container that good results are insured. However, in the case of containers having volumes as large as 500 ml, 1000 ml, or more, the use of single pressure responsive end-closure or even two such end-closures may be insufficient to compensate for or alleviate negative internal pressure to the degree desire This problem is solved according to another aspect of the invention in the form of a tubular element which is itsel adapted to inhibit deformation of the sealed tubular container of large as well as small volume in which a

O negative pressure is developed and which provides good airtightness. In accordance with this aspect of the present invention, the innermost ply or layer of the tubular element of the tubular wall member is provided with means adapted to be inflated inwardly in response to negative pressure developed in the container, thereby decreasing the negative pressure so as to protect the container wall from deformation, improve airtightness, and preserve the shelf-life of the contents.

10

In particular, the tubular wall member of this aspect of the invention has a bonded multilayer tubular element comprising a plurality of plies, the innermost ply being formed of a helically wound elongated polymer-

15 containing sheet material, preferably a polyolefin, having overlapping convolutions, the overlapped portions being bonded, preferably with adhesive. The overlapped portion of the convolutions of this innermost ply is provided with a continuous bond along the seam and at least one addi-

20. tional and preferably continuous bond adjacent to and substantially parallel with the first bond and defining together with the first bond a slack portion therebetween along the overlapped portion of the convolutions of the innermost ply. The slack portion functions by virtue its

25 capacity to be taken up or inflated inwardly in response to negative pressure in the container. Preferably, the tubular element comprises three plies bonded together with adhesive, the middle ply, i.e., the second ply from the innermost ply, being formed of a helically wound elongated

30 cellulosic sheet material, preferably one or more layers of kraft liner paper, which is thicker than either the first or third ply. The edges of the adjacent convolut¬ ions of the middle ply are in abutment to form a tubular layer. The third or outermost ply is preferably formed of

35 a helically wound elongated cellulos-ic sheet material. preferably kraft liner paper, having overlapping convolu¬ tions, the overlapped portions of which are bonded to eac other, preferably by means of adhesive, to form a tubular layer or ply. The first ply has a thickness of desirably between about 0.08 and about 0.12 mm, and preferably abou 0.1 mm. The second ply has a thickness of desirably between about 0.2 and about 0.4 mm, and preferably about 0.3 mm.

Brief Description Of The Drawings

The present invention will now be further described with reference to the accompanying drawings wherein:

FIG. 1 is a side view of a conventional foodstuff container shown in partial cross-section to emphasize the details of its construction;

FIG. 2 is a side view in partial cross-section of a beverage container having an end-closure and cylind¬ rical wall member or element according to one embodiment^' of the present invention;

FIG. 3 is a partial transverse cross-sectional view of the cylindrical wall member of the container of FIG. 2;

FIG. 4 is a representation of the structures of the first, third, and fifth plies forming the cylindrical wall member of the container of FIG. 2;

FIG. 5 is a representation of the structures of the second and fourth plies forming the cylindrical wall member of the container of FIG. 2; FIG. 6 is a fragmentary longitudinal cross- section of the cylindrical wall member of the container of FIG. 2;

FIG. 7 is a longitudinal cross-sectional view of the top-end closure prior to being joined to the cylindrical wall member of the container of FIG. 2;

FIG. 8 is a side view partially broken away of a sealed cylindrical container according to a second embodiment of the invention;

FIG. 9 is a longitudinal cross-sectional view of a portion of the cylindrical wall member of the container of FIG. 8;

FIG. 10 is a representation of the formation of the first, second and fourth plies forming the cylindrical wall member of the container of FIG. 8;

FIG. 11A is a top plan view of one form of an end-closure according to the present invention suitable for use in forming the container of FIG. 8;

FIG. 11B is an enlarged orthographic projection of the end-closure depicted in FIG. 11A shown partially in section;

FIG. 11C is an enlarged cross-sectional view of a peripheral portion of the end-closure of FIG. 11A;

FIG. 12A is -an orthographic projection, partially in section, of one form of a bottom end-closure suitable for use with the cylindrical wall member and top end-closure of the present invention in forming the container of FIG. 8; and FIG. 12B is a bottom plan view of the end- closure depicted in FIG. 12A;

FIG. 13 is a side view, partially broken away, of a sealed cylindrical container according to a third embodiment of the invention;

FIG. 14 is a longitudinal cross-sectional view of a portion of the cylindrical wall member of the con- tainer of FIG. 13;

FIG. 15 is a side view, partially broken away, of the outermost layer of the cylindrical wall member of the container of FIG. 13; and

FIG. 16 is a side view, partially broken away, of the second layer of the cylindrical wall member of the container of FIG. 13.

Description Of Preferred Embodiments

The following examples are provided for the purpose of illustrating, without limitation, the present invention and the advantages thereof.

Example 1

Referring to FIG. 2, there is shown a container 12 according to the present invention for containing a liquid, e.g., a beverage such as fruit juice. Container _1_2- includes top end-closure or cover JjO joined to the upper edge or flange of cylindrical body member or element 14, and bottom end-closure or cover _5 joined to the bottom edge or flange of the cylindrical body member.

OM The container body J_4 can be formed of any suitable material such as aluminum, synthetic resin or plastic, and cup paper insofar as they provide the desired permeability and airtightness. In this e bodi- ment, container body J_4 comprises a laminated composite of five plies as shown in FIG. 3. The first, third, and fifth plies _1_ , J_8, and 2^ are each composed of elongated polymeric resin sheet material helically wound as shown in FIG. 4. The second and fourth plies 22_ and _24 are each composed of elongated cup paper sheet material helically wound between the adjacent plies J_6_^, _1_8_^ and 2Q_ as shown in FIG. 5. The upper edge _2<3 and lower edge §_ of one convolution 26B of each of the polymeric plies respec¬ tively overlaps and is overlapped by adjacent convolutions 26A and 26C at their respective associated lower and upper edges, the overlapped portions being bonded or glued to each other by an adhesive therebetween to form a cylind¬ rical layer. A preferred example of the polymeric resin sheet material is sold commercially by Toyo Tafuper Co., Ltd. under the trademark "Tafuper" a polyolefin containing much inorganic substance. An example of a suitable adhesive for the overlapping portions of convolutions 26A, 26B and 26C is sold commercially by Gisuke Konishi & Co. , Ltd. under the trademark "KU-820". As^' shown in FIG. 5, the second and fourth plies 22_ and 2Λ_ are helically wound; however, convolution 32B of each ply is butted at its upper and lower edges to adjacent convolutions 32A and 32C instead of being overlapped.

In the manufacture of container body _1_4, de¬ picted in its various parts in FIGS. 2 through 6, the sheet for first ply _1_6 is initially wrapped about a cylindrical mandrel (not shown) of a desired diameter. Next, sheets for the second, third, fourth, and fifth plies _22, J_8, 2Λ_ and 20. ^a^^e successively wrapped around the mandrel, preferably in the same direction, to form an elongated cylindrical member. The convolutions of the wound sheets are overlapped or butted, as the case may be, and the sheets are joined to each other by a suitable adhesive, e.g., of the type sold by Koatsu Gas Kogyo Co., Ltd. under the trademark "Pegarl 21OP". This cylindrical member is then cut to a desired length to obtain container body 14.

The first-, third, and fifth plies J_6, J_8, and

20 impart the requisite airtightness to container body 14 while effectively containing any odor emanating from the cup paper used for the second and fourth plies 22_ and 24. The second and fourth plies _^2 and 2_4 impart adequate mechanical strength to cylindrical body element 14.

The sheets of polymeric resin and cup paper can be.employed in various thicknesses consistent with the foregoing disclosure. In the present preferred embodiment, the sheet material used for the first, third and fifth plies _6_, Jj^, and 2Q_ is about 0.1mm thick, and the sheet material used for the second and fourth plies _22 and 2Λ_ is about 0.25mm thick. The average total thickness of all the plies of container body J_4 is about 0.8 mm. A double seam 4_1_ is formed as shown in FIG. 2 in order to provide airtightness between container body J_4 and top end-closure J_0 and likewise between the container body and bottom end-closure JJ5. It has been found, how¬ ever, that such double seams become increasingly difficult to form if the container body _H is substantially thicker than about 0.8 mm. On the other hand, if the container body is substantially thinner than about 0.8 mm, it tends to have less than desired strength. The bottom end- closure V5_. i^s conventional and can take the form of an easy-open end such as a pilfer or pull-up tab well-known

O in the beverage packaging art. The bottom end-closure J_5 in this instance is made of aluminum and is joined to container body J_4 before the container J_2 is filled. Incidentally, it should be noted that the terms "top-end closure" and "bottom end-closure" are used herein with reference to the drawings; in the context of actual use of the container in the upright position, the "bottom end- closure" would normally become the top and vice versa.

The top-end closure YQ_ is formed with the con¬ figuration .shown in FIG. 7, and has an initially convex or dish-shaped bulge portion 2_, an inclined side A Q_, an an¬ nular shoulder _36. adapted to be fitted into the interior of container body _1_4, and a flange 3_8_^ which is adapted to be double-seamed by conventional means (not shown) to the upper flange of the container body. Top end-closure J_0 is hermetically joined to the upper edge of the container body immediately after the filler, e.g., fruit juice which has been heated to a predetermined temperature (normally at least about 90°C), has been charged to the container body and bottom-end closure assembly. After being fully sealed, the beverage-filled container is allowed to stand at ambient temperature or is placed in a refrigerator.. In such circumstances the pressure of the fluid- within the container decreases, thereby producing a negative pressure. As a result, the dish-shaped bulge 2_ is in¬ wardly deflected or "popped" to form a concavity or "dent" in top-end closure _1_0 as shown in FIG. 2. The extent to which the volume of container J_2 is thereby reduced is defined by the disc-shaped bulge 42 shown by the dotted line and the concavity shown by the solid line in FIG. 2, and is enough to compensate for the thermal contraction of the filler, thereby substantially relieving the negative pressure in the container. It is, of course, desirable to that top end-closure 10 be formed in such a manner that the degree to which the volume of the can is reduced by inward deflection of bulge . corresponds to the degree o thermal contraction of the contents in the can so that th negative pressure is essentially reduced to zero, i.e., neutralized. However, if desired, top-end closure J_0 can be dimensioned so that some negative pressure is left in container J_2 after the dent is formed in bulge _42_^ so long as it does not affect the strength or airtightness of the container. Very good results are obtained by forming the above-described end-closure from H-24 0.20 MT aluminum sheet material sold by Kito Sangyo and Shibazeki Susakasg Co. under the name "Flexiend".

Example 2

Referring to FIG. 8, a sealed fruit juice con¬ tainer S0_ is formed by applying top-end closure _^4 and bottom end-closure _56_ to the upper and lower edges of cylindrical container body 52.

As is apparent from the longitudinal cross- section depicted in FIG. 9, cylindrical member 52_. is composed of a plurality of plies. Specifically, cylind¬ rical member j^2 comprises, starting from the inside (right-hand of FIG. 9), layer 5%_ (first ply) of polyolefi resin sheet material; aluminum sheet layer 6Q_ (second ply both sides of which are laminated with thin paper sheets 61 and S3_; kraft liner paper sheet layer J5J3 (third ply) having respectively inner and outer layers _62_^ and A_ of kraft liner paper, and a further layer j56> (fourth ply) of polyolefin resin sheet material. Although the container body is preferably formed using aluminum as the second pl 60, the present invention can also be applied to tinplate particularly thinner tinplates than those conventionally used, thereby effecting substantial cost savings.

O The first, second and fourth plies _5J3, _6 , and

66 shown in FIG. 9 are helically wound as shown in FIGS. 8 and 10. The upper edge ]_0_ of one convolution overlaps the lower edge 72_^ of the adjacent convolution and the thus- overlapped portions of the convolutions are bonded together to form a cylindrical ply. The inner layer 6^2 and the outer layer jv4 of the third ply 8 are, as apparent from FIG. 9, respectively made by spirally winding an elongated sheet of kraft liner paper without overlapping, but rather, by abutting the edges of the convolutions.

The first, second, third and fourth plies _58 J5JD, •$%_ and 66 and the inner and outer layers 2_ and j4 of the third ply are bonded to each other, preferably by adhesive.

In practice, container body _52, is formed by wrapping or winding the sheet for the first ply about a mandrel (not shown) of a desired diameter. Next the sheets for the second, third (inner and outer layers), and fourth plies are successively wrapped or wound about the mandrel to form an elongated cylindrical member. The convolutions of the sheets are overlapped or abutted, as the case may be, and the sheets are joined to each other by application of an adhesive between successive windings. The thus-formed cylindrical member is then cut to a desired length to obtain container body 52.

The first ply 58_ of polyolefin resin serves to fully prevent the fruit juice from permeating the wall of the container, although an acceptable loss through abεorp- tion by the first ply of some product aroma may be in¬ evitable. The second ply ^0 of aluminum laminated by thin paper sheets J5_1_ and S3_, serves to fully prevent the aroma of the fruit juice from escaping further. The kraft liner paper of the third ply 68_ (both inner and outer layers >2_ and 64 are not mandatory; either a single layer or a

OMPI W multiplicity of layers can be used) provides sufficient strength to resist internal - external pressure dif¬ ferences and corresponding tensile or compressive forces in the axial direction. In this connection, it has been found that, although kraft liner paper has more strength than the cup paper used in the embodiment of Example 1 and FIGS. 1-7, it is somewhat less desirable due to its odor. According to the present embodiment, aluminum sheet layer _6 is employed as the second ply to inhibit any offensive odor of kraft liner paper from infiltrating the contents of the container so that such paper can be advantageously used as the th^'ird ply. Finally, polyolefin resin sheet layer S _ is applied as the fourth ply out¬ wardly of the kraft liner paper j5_8 to fully prevent moisture entering from without.

The materials listed below are especially suitable for use as the first, second, third, and fourth plies for container body 5_2_ of container _5_0 of FIGS. 8 through 10. The container J5JD typically has an outer diameter of 56 mm, a height of 137 mm, and a side-wall thickness of 0.87 mm, an arrangement which has been found to be particularly satisfactory for packaging fruit juices. First ply: "Tafuper", -FR 0.1 mm-, manufactured by Toyo Tafuper Co. , Ltd. ; Second ply: "Thin paper laminate aluminum sheet", -35 g, 0.1 mm-, anu- factured by Mitsubishi-Aluminum

Co. , Ltd. ; Third ply: "Kraft liner paper" ("K-Liner")

-A 220 g, 0.3 mm - manufactured by Tohoku Paper Mills Co., Ltd. (both layers); and

^U EΛ

OMPI Fourth ply : "Taf uper " , - OMT 0 . 07 mm- , manufactured by Toyo Tafuper Co. , Ltd.

Incidentally, the material "Tafuper (OMT)" used as the fourth ply is characterized in that it accepts conventional printing materials directly on its surface and therefore can be conveniently used as the outermost layer.

The following adhesives are especially suitable for bonding adjacent plies to one another and for bonding the overlapped portions of the convolutions of the first, second and fourth plies: "Tafuper" to "Tafupef": "Kϋ-820" manufactured by Gisuke Konishi & Co., Ltd.

"Tafuper" to laminate aluminum; kraft liner paper to "Tafuper": "G 6000" manufactured by Gisuke Konoshi & Co., Ltd. Laminate aluminum to kraft liner paper; kraft liner paper to kraft liner p'aper: "Pegarl 21OP" manufactured by Koatsu Gas Kogyo Co. , Ltd.

Referring to FIGS. 11A, 11B and 11C, end-closure _5_4 has a convexity or bulge portion 74 formed in the center. Bulge portion 1 _ is adapted to be inwardly deflected to reduce the volume of the container and thereby increase (i.e., relieve) the internal negative pressure which results, e.g., when the temperature of the sealed contents decreases. In this way, compressive stress generated on the cylindrical wall member of the con¬ tainer is reduced. For example, when bulge portion _74 is about 3.4 cm 3, the volume of the sealed container

3 will be reduced by about 7 cm through inward deflection. These parameters have been found to work very well for an end-closure 5A_ having an outside diameter of 52.0 mm and a bulge portion J having a diameter of 24 mm.

Referring now to FIGS. 12A and 12B, bottom. end-closure _56_ is provided with a conventional so-called "pull-top" which is opened by outwardly pulling tab 76 to tear off a portion of the closure defined by line 78 so that the flowable contents of the container such as fruit juice 'can be poured or drunk from the resulting opening. A suitable pull-top end-closure is manufactured and sold by Hokkai Seikan. An accelerated stability test establishes that liquids such as fruit juice can be stored and preserved in the sealed container formed according to the present invention for at least seven months without deterioration. After use the container can readily be disposed of, since the polyolefin resin sheet material, typically "Tafuper" and the kraft liner paper will burn at about 700° - 720°C with liberation of 5000 - 7000 calories per gram without generating noxious gas and excessive smoke.

Example 3

Referring to FIG. 13, a sealed fruit juice container _^0_ is formed by applying top end-closure J34 and bottom end-closure _8_5 to the upper and lower edges respectively of cylindrical tubular container body 80.

As is apparent from the partial cross-sectional view in FIG. 14, cylindrical body _82_^ consists of four layers or plies. Outermost layer ^ is, as shown in FIG. 15, made by spirally winding an elongated sheet of water¬ proof paper, the upper and lower edges of each convolution 90 overlapping and being overlapped by the edges of the adjacent upper and lower convolutions, respectively, the

Olvf . W overlapped edges being glued or otherwise bonded to each other to form a cylindrical layer. A suitable water-proof paper for use in forming outermost layer j38> is sold by ϋnichica Co. Ltd. under the name "UPO". Second layer ^6 and third layer JT7 are each made as shown in FIG. 16 by spirally winding an elongated sheet of kraft liner paper of relatively greater thickness than outer layer ^8, the edges of each convolution being in abutment to each other to form a cylindrical layer. Innermost layer 9 _ is also made by spirally winding an elongated sheet of polymeric resin and overlapping the edges 96_ of each convolution with those of the adjacent convolutions in a manner similar to outermost layer j3j^; here, however, the attach¬ ment of overlapped edges 96_ is effected in the manner shown in FIG. 14; that is, along the overlapped edge portions, there are provided two continuous elongated welds or bonds 98_ and 100 which are spaced apart from each other. Between the welds some slack 104 is left. These welds can be formed by heat-welding, supersonic welding, and the like and the above four layers or plies are bonded to each other, in the manner described above. In a pre¬ ferred embodiment, the bond between the polymeric resin^' sheet of innermost layer 9_4 and the kraft liner paper of third layer 81_ is advantageously strengthened by the application of corona discharge to the polymeric resin sheet to form a roughness on the surface thereof prior to bonding.

Innermost layer 9 _ serves to prevent liquid material from permeating the container and to provide airtightness. For this purpose, "Fresckfil " sold by Takigawa Chemical Kogyo Co., Ltd. is used as the mate¬ rial of innermost layer 9_4 and has been found to be particularly satisfactory. "Fresckfilm" consists of the following four layers: polyethylene (about

O PI 40 microns), polyester (about 12 microns), evaporated aluminum (less than several microns), nylon (about 15 microns) and polyethylene (about 40 microns).

The kraft liner paper of the second and third layers 3j5 and 8J_ provides mechanical strength to container body j h In the embodiment illustrated in FIG. 14, the second and third layers are made of kraft liner paper "A 220 g, 0.3 mm" manufactured by Tohoku Pape Mills Co., Ltd. Insofar as achieving the necessary mechanical strength to resist internal pressure and resulting compressive forces in the axial direction is concerned, it is possible to use a single layer of kraft liner paper in place of the two layers illustrated in thi example.

Conventional closure means, e.g., aluminum covers, can be used as the upper and lower end-closures 84 and _8^ in conjunction with the container body member j^ of this embodiment; however, in large volume container in which substantially greater negative pressures are developed, it is preferable to use at least one end- closure of the present invention described hereinabove as a closure means. The bottom, conventional end-closure is advantageously provided with opening means such as the so-called pull-top described hereinabove. Even if nega¬ tive internal pressure develops after container _8 equipped with conventional end-closures is sealed, the slack 104 in innermost layer _ is taken up inwardly in response to the negative pressure, thereby substantially lowering or relieving the negative pressure.

Incidentally, although in the present embodi¬ ment, the overlapped portion of the innermost layer is provided with two welds or bonds 98 and 100, three or mor

Q welds can be formed so as to form any desired number of slacks 104. Furthermore, both of the welds or bonds j3 and 100 are formed continuously along the overlapped portion of innermost layer 94_; however since the airtight- ness of the layer is maintained by the first continuous weld, the second weld need not necessarily be formed continuously as long as some slack in the inner sheet is left between the first and second welds. Furthermore, although innermost layer ^4 illustrated above is formed by spirally winding an elongated sheet, it is not limited as such; for example, it can be formed by making a wide width sheet into a circle to form a.cylindrical layer. Further¬ more, the tubular container bodies of this invention are not limited to those having a cylindrical (circular cross-section) configuration, but rather, can be formed, e.g., with a polygonal, elliptical or other non-circular cross-section.

Example 4

Referring again to FIGS. 2 and 7 a further embodiment of the invention will be described in which container V2_ is manufactured according to a method of the invention.

The container Y2_ can be manufactured by the steps of heating and charging a beverage such as fruit juice in container body J_4 in the form of cylindrical container, to which a bottom end-closure J5 has been joined, and joining a top end-closure JJD formed of desired material such as tinplate to the upper end of the body member. The top end-closure J_0 is formed into a dish shape as shown and is provided substantially centrally thereof with an outwardly bulged portion _42 before being joined to the container body.

OMPI _ After covering container body with the top end-closure JJD, flange _3J3 of the top end-closure and the upper end of the container body are overlapped and then folded to form a so-called "double-seam" _4J by means of a sealer or sealing apparatus (not shown) whereby the container is closed and sealed.

Next, the initially outwardly bulged portion 42 of the top end-closure J_0 is urged by a press (not shown) toward the interior of the container body, thereby reversing the bulge and inwardly deflecting or "popping" it to form a concavity as shown in FIG. 2. This pressing step should be performed prior to lowering the temperature of the contents in the container otherwise the drop in temperature and consequent thermal contraction of air within the container will create an unrelieved nega¬ tive pressure which tends to inwardly deform the wall of the container. Preferably, the top-end closure bulges outwardly to such an extent that reduction in volume of the container will be approximately equal to the volume of the "thermal contraction of the container contents.

Industrial Applicability

As described above, the present invention pro¬ vides a composite container for liquids which can function fully as a substitute for conventional containers made of glass, tinplate and the like. It also provides a closure member for hermetically sealing a container after it has been filled with a heated beverage and is characterized by a dish-shaped portion which is outwardly bulged before sealing and which undergoes inward deflection by the negative pressure created by thermal contraction in the container after sealing and upon cooling. In this way, the negative pressure in the container is substantially relieved so that the container can be made of inexpensive materials with lesser rigidity than would be otherwise necessary, such as plastics, cup paper and the like, instead of the tinplate now widely used. It is a feature of the invention that, even if the container is formed of cup paper or the like, it is possible to store it at room temperature for extended periods since differences in pressure between the exterior and interior of the can will not prejudice airtightness and imperviousness to microorganisms. A further advantage is that the container can be made of materials which can be readily disposed of e.g. , by burning.

O PI

Claims

1 Claims

1. A tubular wall member of a tubular container for flowable materials including liquids such as fruit juice

5 and the like, having a bonded multilayer tubular element comprising five plies bonded to each other, including first, second, third, fourth, and fifth plies as viewed from the inside out, said first, third and fifth plies being each formed of a helically wound elongated polymeri

10 sheet material having overlapping convolutions, the overlapped portions of said convolutions being bonded to each other to form a tubular layer, and said second and fourth plies being each formed of a helically wound elongated cellulosic sheet material thicker than said

15 polymeric sheet material, the convolutions of each of said second and fourth plies being in abutment to form a tubular layer.

2. A tubular wall member according to claim 1 wherein: 20 the tubular element is a cylinder having a circular cross-section; the polymeric sheet material of the first, third and fifth plies is a polyolefin; and the cellulosic sheet material of the 25 second and fourth plies is cup paper.

3. A tubular wall member according to claim 2 wherein the first, third and fifth plies each has a thickness of between about 0.08 and 0.12 mm, and the second and

30 fourth plies each has a thickness of between about 0.20 and about 0.30 mm.

4. A tubular wall member according to claim 1, 2, or 3 wherein:

^• 35

O the first, third and fifth plies each has a thickness of about 0.1 mm, and the second and fourth plies each has a thickness of about 0.25 mm; the polymeric sheet material of the first, third and fifth plies is "Tafuper"; and the plies constituting the tubular element are bonded by adhesive and the overlapped portions of the convolutions of the first, third and fifth plies are bonded by adhesive.

5. A tubular wall member of a tubular container for flowable materials including liquids such as fruit juice and the like, having a bonded multilayer tubular element comprising a first ply of polymeric sheet material, a second ply of aluminum sheet both sides of which are laminated by thin paper, a third ply of kraft liner paper sheet, and a fourth ply of polymeric sheet material, said first ply being the innermost ply.

6. A tubular wall member according to claim 5 wherein: the tubular element is a cylinder having a circular cross-section; the polymeric sheet material of the first and fourth plies is a polyolefin; and the third ply is formed of a plurality of kraft liner paper sheets.

7. A tubular wall member according to claim 5 wherein: the first, second and fourth plies are each formed of a helically wound elongated sheet material having overlapping convolu¬ tions, the overlapped portions of said convolutions being bonded to each other to form a tubular layer; and the second ply is formed of a helically wound elongated sheet material thicker than each of the first, third and fourth plies, the edges of adjacent convolutions of said second ply being in abutment to form a tubular layer.

8. A tubular member according to claim 6 wherein the first and second plies each has a thickness of between about 0.08 and about 0.12 mm, each of the kraft liner paper sheets of the third ply has a thickness of between about 0.2 and about 0.4 mm, and the fourth ply has a thickness of between about 0.05 and about 0.1 mm.

9. A tubular member according to claim 5, 6, 7, or 8 wherein: the first and second plies each has a thickness of about 0.1 mm, each of the kraft liner paper sheets of the third ply has a thickness of about 0.3 mm, and the fourth ply has a thickness of about 0.07 mm; the polymeric sheet material of the first and fourth plies is "Tafuper"; and the plies constituting the tubular element are bonded by adhesive and the overlapped portions of the convolutions of the first, second and fourth plies are bonded by adhesive.

10. A tubular wall member of a tubular container for flowable materials including liquids such as fruit juice and the like, having a bonded multilayer tubular element comprising a plurality of plies, the innermost ply being formed of a helically wound elongated polymer- containing sheet material having overlapping convolutions, the overlapped portion of said convolutions being provide with a continuous bond therealong and a second bond

O ^■ adjacent said first bond and defining together with said first bond a slack portion therebetween along the over¬ lapped portion of the convolutions of the innermost ply, said slack portion being adapted to be taken up inwardly in response to negative pressure in the container.

11. A tubular wall member according to claim 10 wherein the second bond extends continuously and substantially parallel to the first continuous bond.

12. A tubular wall member according to claim.11 wherein one or more additional bonds is formed along the over¬ lapped portion of the convolutions of the innermost ply and extends continuously and substantially parallel to the first and second bonds and defines an additional slack portion along said overlapped portion adapted to be taken up inwardly in response to negative pressure in the container.

13. A tubular wall member according to claim 12 wherein the tubular element comprises three plies, the second ply from the innermost ply being formed of a helically wound elongated cellulosic sheet material thicker than each of the first and third plies, the edges of adjacent convolu- tions of said second ply being in abutment to form a tubular layer, and the third outermost ply being formed of a helically wound elongated cellulosic sheet material having overlapping convolutions, the overlapped portion of said convolutions being bonded to each other to form a tubular layer.

14. A tubular wall member according to claim 13 wherein: the tubular element is a cylinder having a circular cross-section;

OMPI v „ WIPO the polymeric sheet material of the first ply is composed of a polyolefin; and the cellulosic sheet material of the second and third plies is kraft liner paper.

15. A tubular wall member according to claim 14 wherei the second ply is formed of a plurality of kraft liner paper sheets.

16. A tubular wall member according to claim 15 wherei the first ply has a thickness of between about 0.08 and about 0.12 mm, and the second ply has a thickness of between about 0.2 and about 0.4 mm.

17. A tubular wall member according to claim 13, 14, 15 or 16 wherein: the first ply has a thickness of about 0.1 mm, and the second ply has a thickness of about 0.3 mm; the polymer-containing sheet material of the innermost ply is "Fresckfilm"; and the plies constituting the tubular element are bonded by adhesive and the overlapped portions of the convolutions of the first and third plies are bonded by adhesive.

18. A closure for hermetically sealing a container after the container has been filled with heated flowable material, said closure being formed of rigid sheet mate- rial of sufficient flexibility and provided with an outwardly bulged dish-shaped portion before sealing, whereby said portion is adapted to be inwardly deflected to^' substantially relieve the negative pressure created in the container due to thermal contraction of its con- tents.

19. A closure according to claim 18, wherein the out¬ wardly bulged dish-shaped portion is adapted to be in¬ wardly deflected in response to said negative pressure.

20. A closure according to claim 18, wherein the out¬ wardly bulged dish-shaped portion is adapted to be in¬ wardly deflected after the container has been sealed and before thermal contraction of the heated contents.

21. A closure according to claims 19 or 20 wherein the dish-shaped portion of the closure is outwardly bulged to such an extent that the volume by which the container is reduced by inward deflection of said portion substantially corresponds to the degree of thermal contraction of the contents of the container.

22. A closure according to claim 19 wherein said closure is formed of aluminum.

23. A closure according to- claim 20 wherein said closure is formed of tin plate.

24. A tubular container for flowable materials including liquids such as fruit juices and the like, comprising:

(a) a tubular wall member having a multi¬ layer bonded tubular element comprising of five plies bonded to each other, including first, second, third, fourth and fifth plies as viewed from the inside out, said first, third and fifth plies being each formed of a helically wound elongated polymeric sheet material having overlapping convolutions, the overlapped portions of said convolutions being bonded to each other to form a tu^'bular layer, and said second and fourth plies being formed of a helically wound elongated cellulosic sheet material thicker than said polymeric sheet material, the edges of adjacent convolutions of each of said second and fourth plies being in abutment to form a tubular layer; and

(b) a closure member for hermetically sealing the container after said container has been filled with heated liquid, said closure being formed of rigid sheet material of suf¬ ficient flexibility and provided with an out¬ wardly bulged dish-shaped portion before seal¬ ing, whereby said portion is adapted to be inwardly deflected by negative pressure created in the container due to thermal contraction of its contents.

25. A tubular container according to claim 24 wherein: the .tubular element is a cylinder having a circular cross-section; the polymeric sheet material of the first, third and fifth plies is a polyolefin; and the cellulosic sheet material of the second and fourth plies is cup paper.

26. A tubular wall member according to claim 25 wherei the first, third and fifth plies each has a thickness of between about 0.08 and 0.12 mm, and the second and fourth plies each has a thickness of between about 0.20 and about 0.30 mm.

27. A tubular wall member according to claim 24, 25 or wherein:

^ J R O the first, third and fifth plies each has a thickness of about 1 mm, and the second and fourth plies each has a thickness of about 0.25 mm; the polymeric sheet material of the first, third and fifth plies is "Tafuper"; and the plies constituting the. tubular element are bonded by adhesive and the overlapped portions of the convolutions of the first, third and fifth plies are bonded by adhesive.

28. A tubular container according to claim 27 wherein the dish-shaped portion of the closure is outwardly bulged to such an extent that the volume by which the container is reduced by inward deflection of said portion substantially corresponds to the degree of thermal contraction of the contents of the container.

29. A tubular container according to claim 28 wherein the closure is formed of aluminum.

30. A tubular container for flowable materials including liquids such as fruit juices and the like, comprising:

(a) a tubular wall member having a bonded multilayer tubular element comprising a first ply of polymeric sheet material, a second ply of aluminum sheet both sides of which are laminated by thin paper, a third ply of kraft liner sheet, and a fourth ply of polymeric sheet material, said first ply being the innermost ply; and

(b) . a closure member for hermetically sealing a container after the container has been

O PI filled with heated liquid, said closure being formed of rigid sheet material of sufficient flexibility and provided with an outwardly bulged dish-shaped portion before sealing, whereby said portion is adapted to be inwardly deflected by negative pressure created in the container due to thermal contraction of its contents.

31. A tubular container according to claim 30 wherein: the tubular element is a cylinder having a circular cross-section; the polymeric sheet material of the first and fourth plies is a polyolefin; and the third ply is formed of a plurality of kraft liner paper sheets.

32. A tubular container according to claim 30 wherein: the first, second and fourth plies are -each formed of a helically wound elongated sheet material having overlapping convolu¬ tions, the overlapped portions of said convolutions being bonded to each other to form a tubular layer; and the second ply is formed of a helically would elongated sheet material thicker than each of the first, third and fourth plies, the edges of adjacent convolutions of said second ply being in abutment to form a tubular layer.

33. A tubular container according to claim 31 wherein t first and second plies each has a thickness of between about 0.08 and about 0.12 mm, each of the kraft liner pa sheets of the third ply has a thickness of between about 0.2 and about 0.4 mm, and the fourth ply has a thickness of between about 0.05 and about 0.1 mm.

-£t

34. A tubular container according to claim 30, 31, 32 or 33 wherein: the first and second plies each has a thickness of about 0.1 mm, each of the kraft liner paper sheets of the third ply has a thickness of about 0.3 mm, and the fourth ply has a thickness of about 0.07 mm; the polymeric sheet material of the first and fourth plies is "Tafuper"; and the plies constituting the tubular element are bonded by adhesive and the overlapped portions of the convolutions of the first, second and fourth plies are bonded by adhesive.

35. A tubular container according to claim 34 wherein the dish-shaped portion of the closure is outwardly bulged to such an extent that the volume by which the container is reduced by inward deflection of said portion substantially corresponds to the degree of thermal con- traction of the contents of the container.

36. A tubular container according to claim 35 wherein the closure is formed of aluminum.

37. A tubular container for flowable materials including liquids such as fruit juice and the like, comprising:

(a) a tubular wall member having a bonded multilayer tubular element comprising of a plurality of plies, the innermost ply being formed of a helically wound elongated polymer-containing sheet material having overlapping convolutions, the overlapped portion of said convolutions being provided with a continuous bond therealong and a second bond adjacent said first bond and

OMPI defining together with said first bond a slack portion therebetween along the overlapped portion of the convolutions of the innermost ply, said slack portion being adapted to be taken up inwardly in response to negative pressure in the container; and

(b) a closure member for hermetically sealing the container after the container has been filled with heated liquid, said closure being formed of rigid sheet material of suf¬ ficient flexibility and provided with an out¬ wardly bulged dish-shaped portion before seal¬ ing, whereby said portion is adapted to be inwardly deflected by negative pressure created in the container due to thermal contraction of its contents.

38. A tubular wall member according to claim 37 wherein the second bond extends continuously and substantially parallel to the first continuous bond.

39. A tubular container according to claim 38 wherein one or more additional bonds is formed along the over- lapped portion of the convolutions of the innermost ply and extends continuously and substantially parallel to th first and second bonds and defines an additional slack portion along said overlapped portion adapted to be taken up inwardly in response to negative pressure in the container.

40. A tubular container according to claim 39 wherein the tubular element comprises three plies, the second ply from the innermost ply being formed of a helically wound elongated cellulosic sheet material thicker than each of

O ■ the first and third plies, the edges of adjacent convolu¬ tions of said second ply being in abutment to form a tubular layer, and the third outermost ply being formed of a helically wound elongated cellulosic sheet material having overlapping convolutions, the overlapped portion of said convolutions being bonded to each other to form a tubular layer.

41. A tubular container according to Claim 40 wherein: the tubular element is a cylinder having a circular cross-section; the polymeric sheet material of the first ply is composed of a polyolefin; and the cellulosic sheet material of the second and third plies is kraft liner paper.

42. A tubular container according to claim 41 wherein the second ply is formed of a plurality of kraft liner paper sheets.

43. A tubular container according to claim 42 wherein the first ply has a thickness of between about 0.08 and about 0.12 mm, and the second ply has_. a thickness of between about 0.2 and about 0.4 mm.

44. A tubular wall member according to claim 40, 41, 42 or 43 wherein: the first ply has a thickness of about 0.1 mm, and the second ply has a thickness of about 0.3 mm; the polymer-containing sheet material of the innermost ply is "Fresckfilm"; and the plies constituting the tubular element are bonded by adhesive and the overlapped portions of the convolutions of the first and third plies are bonded by adhesive.

O PI ^r°

45. A tubular container according to claim 44, wherein the dish-shaped portion of the closure is outwardly bulg to such an extent that the volume by which the container is reduced by inward deflection of said portion substan¬ tially corresponds to the degree of thermal contraction of the contents of the container.

46. A tubular container according to claim 45 wherein t closure is formed of aluminum.

47. A method of packaging heated flowable materials in sealable container wherein a container body having an op end is charged with the heated material and a top end- closure is joined to the open end of said container body comprising the steps of: forming an outwardly convex bulged portion in said top end-closure before sealing said container body, and mechanically depressing said bulged portion of said end-closure inwardly of said container before the thermal contraction of the contents, air and the like within the sealed container has developed after sealing said container.

48. A method according to claim 47 wherein the step of depressing the bulged portion is characterized in tha said bulged portion is depressed to the extent that reduction in interior volume of the sealed container thereby is substantially equal to the extent of the thermal contraction of the container contents.

OM