GB2191730A - A method of forming the head of a thermoplastic container - Google Patents

Abstract

A molten disc (17) is applied to seal the end of a tubular element (1) and, while the disc is still in a moldable state, it is formed into a head using either a fluid pressure, a vacuum, or both on opposite sides. A sealing head (37) on an internal sealing mandrel (35) has a first shoulder (39) thereabout which is complementary with a second shoulder (73) about a mold cavity, which trap the periphery of the disc, and the head is formed in a configuration conforming to the mold cavity by fluid pressure injected through the internal sealing mandrel, through a vacuum pulled through the mold form containing the cavity, or by use of both said fluid pressure and said vacuum. <IMAGE>

Description

SPECIFICATION Method of forming thermoplastic headed tubular containers Background of the invention The present invention relates to a method of for ming thermoplastic tubular containers and, more specifically, to a methodforforming a head on a tubular sleeve to provide a neck portion of a thermoplastictubularcontainer.

Thermoplastic tubular containers, especially col- lapsible or squeezable containers, have continued to take over an increasing share of the container market from metallic tubes. Such thermoplastictubular containers are extensively used in packaging of cosmetics, medicinal preparations, shampoos and other products. With the increased development of multilayer or laminated tubes having oxygen barrier properties, that resist oxygen permeation,further in- creases in packaging of pharmaceutical products and of foodstuffs in thermoplastictubes are occurring.

An advantageous methodforforming such containers involves the extruding of a hollowtube and then cutting the tube to desired lengths and forming a head or neck portion to close one end of the resulting tube. The other end is retained in an open condi tionforfillingthecontainerwiththegoodstobe packaged, followed by sealing of the open end to provide an integral sealed tubular container.

A known method for forming collapsible plastic tubes with neck portions, known as the "Downs" process, is described in U.S. 3,047,910, the contents of which are incorporated by reference herein. As described therein, thermoplastictubular containers are fabricated by placing a thermoplastictubular member, or hollowtube, into aforming collarand forcing a cut, molten disc into an open end ofthe tubular member. The latent heat of the molten disc is sufficient to weld the peripheral edge of the disc to theinnerwall ofthetubularmemberandthusform an end closureforthetubularcontainer. As described, pressure is exerted through the interior of the tubular container to the sealed end closure to shape the latterto a desired contour.The preferred means for applying pressure to the sealed end closure is through the use of a mandrel that is inserted through the open end of the tubular member. Air pressure, or vacuum, are not suggested for forming the contour ofthe sealed end closure, although it is suggested thatairundersuitablepressureora reciprocableflat end mandrel may be admitted interiorly ofthetubing to assure that a flat end-closure is not distorted upon cooling and remains desirably flat.

While the above-described process has been suitableforforming headed portions or necks on collapsibletubularcontainers, complicated tooling is required to force the plastic disc to conform to a mold cavity, necessitating high tooling costs and subsequent upkeep. Also, with the use ofcompres- sion moulding of the headed portions, massive hydraulic equipment is used, adding to capital cost and maintenance costs. In addition, relativeiythick discs are needed where compression molding is used which increases costs and adds to scrap produced. Not only are cost considerations prevelant with the use of such a process, but the process is limited with respect to the type or shape of head produced bysuch a compression molding system.Such a process is not, for example, readily adaptable to formation of heads on tubes where the heads have multiple orifices orcomplex/head configurations.

One modification ofthe above-described process for use in forming multi-layer or laminated collaps iblethermoplastictubularcontainers is described in U.S. 3,962,006. In that process, a laminated film is used to form a thermoplastic sleeve having an impermeable layer, and a molten disc also having an impermeablelayerisweldedtotheinteriorwall of the laminated thermoplastic sleeve. A pressing operation is used to form a head member on thetube, the pressing operation using a female mold and a core which interiorly supports the laminated thermoplastic sleeve.

It is an object of the present invention to provide an improved method for forming a thermoplastic tubularcontainerwherebya head can be readily formed which has a predetermined complex head configuration.

It is another object of the present invention to provide a methodforformingathermoplastictubular containerthatusesa molten disctosealtheendofa tubular sleeve but does not require the massive hydraulics presently used to compression mold a head on the tube.

It is a further object of the present invention to pro videamethodforforming athermoplastictubular container that uses a molten disc to seal the end of thetubularsleevewhich enables the use of a thinner shoulder, relative to compression molded heads, thus increasing manufacturing speed, lowering material costs, and reducing scrap.

Summary of the invention Amethodforforming athermoplastictubularcon- tainer, wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element, with the latent heat ofthe molten disc welding the disc to the innerwall ofthe hollow tubular element to seal the same, includes the use of an internal sealing mandrel to seal only a shoulder thereof, and then forming the thermoplastic disc, while still in a moldable state, to a mold configuration. The internal sealing mandrel, having a sealing head on the end thereof, is inserted into the other open end of the hollow tubular member, the sealing head having a first shoulderwhich trapsthe periphery ofthe disc between said first shoulder and a second shoulder aboutthe periphery of a mold cavity.Pressure on the sealing mandrel is applied only to form a seal ofthermoplastic material between the first and second shoulders, and forming of the thermoplastic disc, while in a moldable state and while only the seal ofthermoplasticisin contact with the sealing head, is effected by either applying a fluid pressure against the surface of the thermoplastic disc confronting the sealing head, or applying a vacuum to the surface of the thermoplastic disc opposite the surface thereof confronting the sealing head, or both. So forming of the disc, while in a moldable state, causes the disc to conform to the predetermined shape of a mold cavity to form a closed end wall on the tubular container having said predetermined shaped.

Brief description ofthe drawings In the drawings: Figure 1, containing figures 1 Athrough 1 F, illustrate the conventional process for formation of a head on a tubular element by an internal forming mandrel, such as described in U.S. 3,047,910; Figure2 shows a sealing mandrel usable in the present method within a hollow tubular element having one end, closed with a disc, positioned adjacent a mold cavity; Figure 3 illustrates the application of pressure to the sealing mandrel with insertion of the lower portion ofthe hollowtubular element and the moldable disc within the mold cavity and application offluid pressure therein to form a head; Figure $shows a sealing mandrel within a hollow tubular element having an end, closed with a disc, positioned adjacent a mold cavity for use with application of a vacuum to form a head;; Figure 5 illustrates the application of pressure to the sealing mandrel with insertion ofthe lower portion hollow tubular element and the moldable disc with the mold cavity and application of a vacuum to form a head; Figure 6shows a sealing mandrel usable in the present method within a hollowtubular element, having one end closed with a disc, positioned above a mold cavity priorto application of both fluid pressure and vacuum to form a head; Figure 7 illustrates the application of pressure to the sealing mandrel with insertion of the lower portion ofthe hollowtubular element and the moldable discwithinthe mold cavity and the application of both fluid pressure and vacuum thereto to form a head; Figure 8shows a tubular element and disoposi- tioned adjacent a mold cavityforformation of a bulbous head;; Figure 9 illustrates the application of fluid pressure to form a bulbous head; Figure 10 illustrates a container having a bulbous head,formable by the present method; Figure 11 illustrates the application of fluid pressure to form an applicator4ype head according to the present method; Figure 12 illustrates a container having an applicator head, formable bythe present method; Figure 13 illustrates the application offluid pressure to form a novelty head in the shape of a clown's head according to the present method; Figure 14 illustrates a container having a novelty head, such as a clown's head, formable by the present method; Figure 15 ill ustrates the application offluid pressure to form a twist-off head according to the present method; and Figure 16 illustrates a container having a twist-off head formable by the present method.

Detailed description The present method is an improvement over conventional processes forforming a head or closed end tubular container, and enables the formation of unconventional heads of various shapes. As is known, conventional processes, such as the "Downs" pro cessdescribed in U.S. 3,047,910 usethe latent heat of a molten thermoplastic disc to seal the periphery of the disc to the inner circumferential wall of a tube to close the end thereof, Figures 1A through 1 F illustrate such a conventional process. As illustrated therein, a hollowtubularelement 1, orsleeve, ofa thermoplastic material is formed, such as by extruding a tube of thermoplastic material and cutting desired lengths, as illustrated in Figure 1A.The hollow tubular element 1 is then conveyed to a punch station (Figure 1 B), having punches 3, while supported on a forming mandrel 5 that has a support member7, head portion 9, and protrusion 11 thereon. The supported hollow tubular element is positioned above a molten strip orfilm 13 of a thermoplastic material supported on a base 15. Upon activation at the punch station, the punch 3, such as by lowering the same as indicated by the arrow in Figure 1 C, mechanically outs through the molten thermoplastic strip 1 forming and picking up a circular slug or disc 17.The moltenthermoplasticdisc 17 is then in contactwith the bottom edge of the hollowtubular element 1, where the latent head from the disc 17 then partially melts the mating edge ofthe hollowtubularelement 1, forming a natural weld 19 between the peripheral edge 21 ofthe disc 17 and inner circumferential wall 23 of the tubular element 1 to seal the same (Figure 1 D), to provide a preform 25 forsubsequentforming.

The preform 25 (Figure 1 D) is then transported to a molding station where hydraulic pressure is applied totheforming mandrel ina moldform.Asillustrated in Figure 1 E, the preform 25 supported bythefor- ming mandrel 5, is positioned above a mold form 27 having a cavity 29, with walls 31 thereabout. The mandrel 5, upon pressure being applied thereto, as indicated by the arrow (Figure 1 F) compresses the molten disc 17 against the walls 31 of the cavity 29 in the mold form 27, forcing thethermoplasticto conform to a head 33 in the shape ofthe mold space between the forming mandrel head 9 and protrusion 11 and the walls 31 ofthe mold cavity 29.The ex- ternal tooling is constantly cooled so that, as the formed disc 17 is compressed into the desired shape, the thermoplastic "sets up", thus permanentlyfor- ming the shape ofthethermoplastic tube head.

This prior art process, as illustrated in Figure 1 has been very successful in forming thermoplastic tubular containers, but contains some drawbacks.

The forming mandrel must be capable offorcing the thermoplastic disc into the required shape and thus limits the shapes that can be produced. Tooling costs and subsequent upkeep costs are high, while manufacturing speeds are not as high as are desirable.

Massive hydraulic systems are also required in order to provide the compression forces necessary to mold the head. In addition, exotic shaped heads or novelty shaped heads are not readily produced using such a compression type forming mandrel.

By use ofthe present method, these disadvantages are removed. The present method uses eitherfluid pressure, vacuum, or a combination of fluid pressure and vacuum to form heads on tubes where an internal sealing mandrel is used onlyto provide a seal about the periphery ofthe head formed.

Referring now to Figures 2 and 3, one embodiment of the present process is illustrated wherein fluid pressure alone is used to form a head. A hollow tubularelementorsleeve 1 hasa molten disc 17, with the peripheral edge 21 thereof welded to the inner circumferential wall 23 ofthe hollowtubular member, and an internal sealing mandrel 35 is inserted therein, the internal sealing mandrel 35 having a sealing head 37 on the end thereof said sealing head having a first shoulder 39 about the surface thereof confronting said disc, and a conduit 41 thereon which communicates with a passageway 43 that ex- tends through the sealing head 37.The hollow tubular element 1, with the disc 17 still in a moldable state, is positioned adjacent a mold form 27 which may be an integral unit orformed of mating sections 27a and 27b, having a cavity 29, with walls 31 about the cavity, with one section 45 of the wall 31 having a second shoulder 47 that is complementa ry with the first shoulder 39 on the sealing head 37 of the seal ing mandrel 39. A source of pressurized fluid, such as air 49 is provided which communicates with the conduit 41 ofthesealing mandrel through line 51.In forming of a head 53, as illustrated in Figure 3, the hollow tubular element 1 with disc 17 in a moldable state, is positioned within the mold cavity 29 of mold form 27, and pressure is applied, as indicated by the dashed arrow, to the sealing head 35 only to form a seal of thermoplastic material, indicated at 55, between the first shoulder 39 on the sealing head and the complementary second shoulder47 of the mold cavity wall.After formation ofthe seal ofthermo- plastic material 55, air from the source 49 is injected through the conduit41 of the sealing mandrel 35 which forces the portion of the thermoplastic disc surrounded by sealed portion 55, while still in a moldable state, into contact with the exposed wall 31 of the mold form, such as the threaded form illustrated,to form the head ofthetube produced. The injection oftheairagainstthethermoplasticdiscthus causes the portion thereof, which is not between the complementary first and second sealing shoulders 39 and 47 to conform in shape to the predetermined shape, such as the cylindrical thread-like shape illustrated, to form a closed end wall on the thermoplastic tubular container of a predetermined shape.

Another embodiment of the present method isil- lustrated in Figures 4 and 5, wherein a vacuum is applied to the disc, while in a moldable state, rather than the fluid pressure application embodiment of Figures 2 and 3. As illustrated, a sealing mandrel 57, similarto sealing mandrel 35 is provided, except that theconduitorextension may be a solid rod-like element 59 having a sealing head 61 on the end thereof. The sealing head 61 has a first shoulder63 thereon about the surface thereof confronting the disc 17.The hollowtubularelement 1,with the disc 17 still in a moldable state, is positioned adjacent a mold form 65,which may be an integralunitor formed of mating sections 65a and 65b, that has a cavity 67 therein with walls 69 about the cavity, and one section 71 ofthe wall 69 having a second shoulder 73 that is complementary with the first shoulder 63 on the sealing head 61 of the sealing mandrel 57.

The mold form 65, in the area surrounded by the second shoulder73 thereof, has a plurality of apertures 75 therein which extend from the wall 69 of the cavity 67 to the exterior surface 77 of the mold form 65.Asource of vacuum 79 is provided which com municateswith the pluralityofapertures 75 by means of line 81 and branch lines 83.In forming of the head 53 using vacuum, as illustrated in Figures, the hollowtubularelement 1 with moldable disc 17 is positioned within the mold cavity 67, and pressure is applied, as indicated by the dashed arrow, to the sealing head 61 only to form a seal ofthermoplastic material, indicated as 85, between the first shoulder 63 on the sealing head and the complementary second shoulder 73 ofthe mold cavity wall. Afterformation of the seal of thermoplastic material 85, a vacuum is applied from source 79 and through line 81, branch lines 83, and apertures 75, which draws the portion ofthe moldable thermoplastic disc, surrounded by sealed portion 85, into contact with the exposed wall 69 of the mold form, such as the thread form illustrated, to form the head ofthe tube produced. The application of the vacuum causes the portion of the disc that is not between the complementary first and second sealing shoulders 63 and 73to conform in shapeto the predetermined shape, to form a closed end wall on the thermoplastictubular container.

In the embodiment ofthe present invention illustrated in Figures 6 and 7, the application offluid pressure, such as air, in combination with the application of a vacuum, to form a head are used. A hollow tubular element 1 ,with the disc 17 welded to the inner circumferential wall thereof, has an internal sealing mandrel 35 inserted therein, the sealing mandrel having a sealing head 37 on the end thereof.

The sealing mandrel has a first shoulder39 about the surface confronting the disc, and conduit 41 therein communicating with passageway 43 that extends through the sealing head 3.Asource of air49 com- municatesthrough line 51 with conduit41.

The hollowtubularelement on sealing mandrel 35 is positioned adjacent a mold form 65 having a cavity 67, with walls 69 about the cavity. The sealing head 37 has a first shoulder 39 about the surface thereof confronting the disc, whilethe wall 69 of cavity 67 in the mold form 65 has a second shoulder 73 that is complementary with said first shoulder 39. The area of mold form 65 surrounded by second shoulder73 has a plurality of apertures 75 therein, extending from wall 69 to the exterior surface 77 thereof, and a source of vacuum 79 communicates with said aper tures 75 through line 81 and branch lines 83.

Figure 7 illustrates formation of a threaded head using both fluid pressure and vacuum. The hollow tubular element 1 ,with disc 17 still in a moldable state, is positioned in mold cavity 67, and pressure applied, as indicated by the dashed arrow, to the sealing line 37 only to form a seal 87 cfthermoplastic material between first shoulder 39 on the sealing head 37 and the complementary second shoulder 73 in the mold form 65. Afterthe seal 87 isformed, vacuum is applied through line 81, branch lines 83, and apertures 73 to the surface 89 ofthe discfacing the mold cavity wall 69, while at the same time, air from source 49 is injected through the conduit 41 of the sealing mandrel 35 againstthe surface 91 of the disc facing the sealing head 37.Application of both vacuum to one side of the disc surrounded by shoulder 73 and fluid pressure to the other side ofthe disc surrounded by shoulder 39 forces that exposed area of the disc to conform to the shape, such asthethrea- ded head shape illustrated.

As aforedescribed, the application of afluid pressure, application of a vacuum, or both are made whilethethermoplastic disc is still in a moldable state. The thermoplastic material of the disc is no longer in a purely molten state or above its melting point after the latent heat thereof has welded the disc to the tubular element wall, but must still be above the glass transition temperature ofthethermoplastic so that the disc is soft and flexible and moldable to the desired shape.

Whentheapplication of pressure is usedtoform the head, pressures between about 5 to 140 pounds per square inch are used. When a vacuum is applied to form the head, a vacuum of about 10 to 30 inches are used. Thethermoplastic tubular container formed according to the present method will normally have a tubular wall section of between about 0.010 to 0.040 inch in wall thickness, while the head portion formed thereon will have a thickness of about 0.010 to 0.080 inch in wall thickness.

The present method is also usable to form thermoplastic containers of laminated or layered thermoplastic materials. Such laminates comprise layers of a thermoplastic material and a barrier layer such as aluminum foil, orthe like, or layers of varient plastic materials which may be co-extruded in layers to form a multi-layerthermoplatic material. In form ation of such laminated tubular thermoplastic containers, the tubularwall section and plastic disc are formed from laminated plastic material and then sealed together and molded as would be a thermoplastic tubular container of a single thermoplastic material.Such a laminate ofthree layers, in the disc and hollowtubularelement,would,forexample have inner and outer layers of a material such as polyethylene, or other thermoplastic, while an intermediate layer, such as an oxygen impermeable layer, would be of a polyamide such as nylon, or ethylene polyvinyl alcohol, or the like. Or, a five layer composite could be used having successive layers of an outer thermoplastic resin, adhesive, intermediate impermeable layer, adhesive, and an innerthermoplastic resin.The thermoplastic resin can comprise polyethylene, polypropylene, a polyester such as polyethylene terephthalate, or the like, while the intermediate impermeable layer can comprise an oxygen impermeable material such as nylon, ethylene polyvinyl alcohol, polyvinylidene chloride, orthe like, with the two adhesive layers supplied to bond the intermediate layer to each of the inner and outer layers.

The production of various embodiments of com piex heads that may be formed according to the present method, and not readily by the original Down's process, is illustrated in Figures 8 through 16.

Figures 8 through 10 illustrate formation of a bulblike head on a hollowtubular element. Figure 8 illustrates a hollowtubular element 1, with a welded disc 17 secured thereto, and with the sealing mandrel removed, positioned adjacent a mold form 27, formed of matable mold form sections 27a and 27b. The mold cavity 29 is in the form of a spherical cavity.

Figure 9 illustrates the application offluid pressure from the sealing mandrel 35, through conduit 41 that communicates with passageway 43 in the sealing head 37, to form the disc, while in a moldable state, into conformity with the walls 31 of the mold cavity 29, to form a bulbous head 93 on the end ofthe hollowtubularelement as illustrated in Figure 10.

Such a bulbous head would not readily be formed using a forming mandrel since the same would not be able to pass the constrictive portion 95 between the tubular element 1 and the bulbous head 93.

Figures 11 and 12 illustrate formation of another complex head embodiment according to the present method that is in the form of an applicator head for application of ointments orthe like, over a larger area than would be provided by a single tube outlet.

The applicator head 97 has a plurality of protrusions 99 through which orifices would be formed such that the contents of the finished and packed tube would be exudable through the plurality of apertures over a large surface area.

Figures 13 and 14 illustrate formation of a novelty type head 101, in the shape of a clown's head, with a constricted portion 103forming a neckforthe clown and with a cap 105, later applied, covering the orifice (notshown) for dispersing the product being in the form of a hat forthe clown.

Figures 15 and 16 illustrate formation ofatwist-off orampoule-like head 107 for a hollowtubularelement, where a very narrow constriction 109 is provided between the body of the tubular contour 111 and a gripable head portion 113. By grasping the gripable head portion 113 and twisting the same, a break at constrictive portion 109 would occur, with access to the contents of the body 111 ofthetubular container effected.

It should be noted that in Figures 8through 16, the application of fluid pressure is illustrated, while equally effective would be the application of vacuum through a mold form, as previously described, as well as application of both fluid pressure and vacuum, as also previously described herein in accordance with the present method.

The present method enables the production of complex head designs that are not readily produced using compression molding as effected in the prior art, will enablethe use ofathinnerdisc in theformation of heads on tubular elements, and provides an efficient and economical means for forming heads on thermoplastic tubes.

Claims (20)

1. In a methodofforming athermoplastictubular container wherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element and allowing the latent heat of the molten plastic disc to weld the peripheral edge ofthe disc to the inner circumferential wall ofthe tubular element to seal the same, the improvement wherein:: an internal sealing mandrel is inserted into the other end ofthe hollowtubular member, the internal sealing mandrel having a sealing head on the end thereof, the sealing head having a first shoulder thereabout; positioning the hollow tubular element and disc within a mold cavity defining a predetermined shape, with a second shoulder about the periphery of the mold cavity complementary with said first shoulder; applying pressure on said sealing head onlyto form a seal of thermoplastic material between said first and second shoulders; and forming said thermoplastic disc, while the same is in a moldable state, and while only the seal of thermoplastic material is in contact with said sealing head, to cause the same, to conform in shape to the predetermined shape of said mold cavity to form a closed end wall on said thermoplastictubularcontainer having said predetermined shape.

2. The method as defined in Claim 1 wherein said internal sealing mandrel has means for injecting a fluid therethrough, and wherein the forming of said thermoplastic disc is effected by injecting a fluid through said fluid injecting means against the surface of said disc confronting said internal sealing mandrel.

3. The method as defined in Claim 2 wherein said meansforinjecting fluid through said internal sealing mandrel comprises an internal sealing mandrel having a sealing head with an axial passageway therethrough, and means communicating with said passageway to inject fluid therethrough.

4. The method as defined in Claim 3 wherein said fluid is pressurized air.

5. The method as defined in Claim 3 wherein, while said forming of said thermoplastic disc is effected by injecting a fluid through said internal sealing mandrel, a vacuum is applied to the surface of said disc opposite the surface confronting said internal sealing mandrel.

6. The method as defined in Claim 1 wherein said forming of said thermoplastic disc is effected by applying a vacuum to the surface of said disc opposite the surface confronting said internal sealing mandrel.

7. The method as defined in Claim 6 wherein said vacuum is in an amount of between about 10to30 inches.

8. The method as defined in Claim 2 wherein said fluid is air at a pressure of between about 5 to 140 pounds per square inch.

9. The method as defined in Claim 5 wherein said fluid is injected through said internal sealing mandrel at a pressure of between about 5 to 140 pounds per square inch and said vacuum is in an amountof between 10 to 30 inches.

10. The method as defined in Claim 9 wherein said fluid is air.

11. The method as defined in Claim 1 wherein said hollowtubular element and said disc comprise a laminate of a plurality of layers of material.

12. The method as defined in Claim 11 where at least one of said layers is a barrier material.

13. The method as defined in Claim 12 wherein said barrier material is comprised of an oxygen impermeable material.

14. In a method of forming a thermoplastic tubular containerwherein a molten plastic disc is secured within the confines of an open end of a hollow tubular element and allowing the latent heat ofthe molten plastic disc to weld the peripheral edge of the disc to the inner circumferential wall of the tubular elementto seal the same, the improvement wherein:: an internal sealing mandrel is inserted into the other end of the hollowtubular member, the internal sealing mandrel having a sealing head on the end thereof, the sealing head having a firstshoulder thereabout; positioning the hollow tubular element and disc within a mold cavity defining a predetermined shape, with a second shoulder about the periphery of the mold cavity complementary with said first shoulder; applying pressure on said sealing head only to form a seal of thermoplastic material between said first and second shoulders; and applying a fluid pressure against the surface of said disc confronting said internal sealing mandrel, while atthe same time applying a vacuum to the surface of said disc opposite the surface confronting said internal sealing mandrel, while the disc is in a moldable state, a nd while only the seal ofthe thermoplastic material is in contact with said sealing head, to cause the same to conform in shape to the predetermined shape of said mold cavity to form a closed end wall on saidthermoplastictubularcontainer having said predetermined shape.

15. The method as defined in Claim 14wherein said hollowtubularelementand said disc comprisea laminate of a plurality of layers of material.

16. The method as defined in Claim 15 where at least one of said layers is a barrier material.

17. The method asdefined in Claim l6wherein said barrier material is comprised of an oxygen impermeable material.

18. A Method of forming a thermoplastictubular container substantially as herein described with reference to the accompanying drawings.

19. Atubularcontainerwhenevermadebya method according to any one of the preceding claims.

20. Any novel feature or combination offeatures disclosed herein.