CA1198064A - Hot filled container and seal assembly and method - Google Patents

Abstract

ABSTRACT

A container body made of thermoplastic materials, after being filled with a hot liquid, is then sealed by a flat closure disc adhesively contacting a peripheral lip formed around the top of the body. The bottom of the container body is formed with annular grooves to define a diaphragm which flexes inwardly with the closure disc upon cooling of the hot filled liquid to substantially dissipate the high internal vacuum which is formed on the container head space. The bottom of the container body has a reinforced pedestal base formed with stacking ledges to facilitate nesting of empty bodies for shipment and storage.

Description

This invention relates to the Fi]ling and hermetic séal-ng of plastic-bodied containers with hot liquid or semi-liquid prod~cts, and in par-ticular to improvements in the methods and structures for accomplishing same without deforrnation -to the side wall of the container or prema-ture breaking of the seal.
Recen-tly there has been a demand for a thermoplastic container for s-toring jams which must be heated -to a liquid or serni-liquid state at temperatures of up to about l90 F to facili-tate filling into -the container, and must -then be hermetically sealed with a heat sealed peelable closure disc. This container can be used to package foods commonly classified as hot fillable, such as jams, fruit juices, and o-thers. By ho-t-filling at a temperature of 190F the container and conten-ts are sterilized and do no-t require additional preservatives. The higher the tem-peratures that must be used, -the grea-ter the likelihood of creat-ing stresses on the container and/or seal because of high in-ternal vacuums developed upon subsequent cooling of the produc-t, pri-marily because of the condensation of steam in the head space of the sealed container. I-t is important tha-t the side wall of the container be kep-t free of deformation or paneling while at -the same time maintaining the herme-tic seal to prevent spoilage of the produc-t during shipping and storage.
In the past it has been known to construct a -thermo-plastic-bodied container for s-toring motor oils wi-th a flexible bot-tom so that depletion of gaseous componen-ts causing a change in the internal pressure can be compensated for by -the flexing action on the bottom as described in U.S. Patent No. 3,409,167 -to Blanchclrd. The con-tainer of that patent was formed wi-th a rela-tively thick side wall and a relatively -thin bottom wall to pre-vent paneling to -the side wall while permit-ting flexing of the bottom wall, as set for-th in column 4, lines 3 to lO thereof, for example. ~

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~ he present invention provides a hermetical.ly sealed thermoplas-tic bodied container whi.ch is capable of holding hot filled produc-ts,such as jams or the like, and which can be easily opened by simply pee]ing the container closure from the container body.
The presen-t invention also provides such a container construc-tion which permi-ts the use of a peelable closure having a peel s-tren~th which is sufficiently low to permit easy opening by the consumer, and yet high enough to prevent rupture of the seal 10 when subjected to -the conditions under which the container is filled and sealed.
The present invention again provides such a container which is provided with flexible top and bot-tom portions which are adapted to move inwardly as the hot filled product cools to thus prevent paneling of the side wall of the container and rupture of its hermetic seal.
The present inven-tion also improves -the wall construc-tion of herme-tically sealed thermoplastic containers.
According to the present inven-tion there is provided a 20 hot-filled hermetically sealed gas barrier multi-layer plas-tic container with a side wall free of deformation having therein a headspace whi.ch includes moisture vapor, a sterilized ho-t-fillable food product and a subs-tantial partial internal vacuum, said food produc-t in the container having a measurable vapor pressure when hot filled into the container a-t a tempera-ture of up to abou-t 190 F to a level ].eaving a headspace and under conditions suf-ficient -that there develops measurable moisture vapor pressure in the container after it is hermetically sealed, and upon cooling of and consequent condensa-tion of the moisture vapor of the food 30 product, there develops said substan-tail partial internal vacuum in the container comprising, an open-top plastic body of mul-ti-layer construction which includes a gas barrier layer substantially impervlous to oxygen, said body having: (l) an annular sealing sur-face about the open top, (2) a bottom wall having a transverse cross-sectiona] configuration defining means which permits dia-phragma-tic fl.exing thereof inwardly of said body, (3) a side wall free of paneling or deformation notwi-ths-tanding said internal vacuum upon cooling of -the herme-tically sealed hot food product, (4) said bo-t-tom wall being disposed in an inwardly flexed posi-tion due -to internal vacuum, and having gradually rnoved to said flexed position from a more outward unflexed substantially planar initial lO position located substantially within -the axial leng-th of said plastic body prior to hot filling and sealing while having coopera-tively gradually and subs-tan-tially reduced -the substan-tial or high in-ternal vacuum as it was developing while the hot food product was cooling, a gas barrier impervious flexibl.e closure disc her-metically sealed -to the sealing surface by adhesive means defining with said closure disc and body -the hermetic seal, which withstands the high internal vacuum which gradually develops upon cooling of and consequen-t condensation of -the moisture vapor of the product, withs-tands the subsequent subs-tantially reduced internal vacuum, 20 and yet allows easy peel removal of the disc from the sealing surface, said closure disc also being disposed in an inwardly flexed posi-tion due to in-ternal vacuum as allowed by the headspace, and having gradually moved -to said flexed position from a more outward unflexed initial position of a subs-tantially flat plane across said sealing surface while also having cooperatively gradu-ally and substantially reduced the high internal vacuum as it was developing, a s-terilized hot-fillable food product in -the con--tainer, said food produc-t having a measurable vapor pressure when hot-filled lnto the container at a temperature of up to about 30 190F after the container is hermetically sealed, and, a head-space i.n said con-tainer between said food produc-t and the said closure disc when hermetically sealed, said adhesive means, and .'',i~i said cooperative inwardly flexed positions of said closure disc and in-tegral bottom wa]l together having coopera-tively substantial]y reduced or dissipated the high internal' vacuum, and together co-operatively maintaining -the subs-tantially reduced in-ternal vacuum in -the container, said side wall unpaneled, said hermetic seal unruptured, and said closure disc easily peelable. Suitably one of said layers is a bulk layer formed at least in part from reground scrap materials of said o-ther layers. PreEerably said adhesive seal for said closure disc has a T-peel streng-th of from about 3 10 to 5 pounds. Desirab]y said body includes an e-thylene vinyl alcohol copolymer as a barrier layer. Suitably said closure disc includes an e~hylene vinyl alcohol copolymer as a barrier layer.
Desirably said side wall is of tapering frustoconical configura-tion throughou-t a major portion of the axial extent thereof and merging into a generally cylindrical and substantially vertically extending rigid pedestal wall of lesser diameter, said pedes-tal wal] merging in-to said bot-tom wall. Preferably said pedes-tal wall ` is connected to -the frus-toconical side wall by means of an up-; wardly and ou-twardly angularly extending reinforcing wall, said 20 reinforcing wall ex-tending at an angle of about 45 to -the con-tainer longitudinal axis and wherein further said frustoconical side wall includes at its lower end a downwardly and inwardly curving rounded corner merging into said reinforcing wall. More preferably the container Eurther includes stacking format~on in said side wall and permits easily separable nes-ting of a plurality of empty said plastic bodes.
:[n accordance with -the present invention a uniformly thick -thermoformed container body made of thermoplas-tic materials having a plurality of layers including a barrier layer is formed 30 with a lip portion around its periphery to facilitate sealing wi-th an easily peelable heat-sealed closure disc made of a flexible flat sheet material after -the con-tainer has been filled wi-th a ho-t a, liquld. The bo-ttom wall and the top closure disc of the container are formed to effect diaphragmatic flexing to relieve the in-ternal vacuum resultin~ from subsequen-t cooling of the liquid and thus prevent rupture of the seal or paneling of -the side wall.
The present invention also provides a method for provid-ing a h.igh gas barrier multilayer plastic conta.iner having a food product therein and he.rmetically sealed by a high gas barrier easily peel-openable :Elexible closure, the food product having been hot--filled at from about 180F to about 190F, the con-tainer being 10 adapted to preven-t the development of high in-ternal vacuum -therein upon cooling of -the produc-t, hold a reduced internal vacuum and prevent paneling of the container side walll comprising the steps of: providing an open--top plas-tic con-tainer body of multilayer construction which includes a high gas barrier layer, the body having a side wall extending from its top where it has an annular ~ sealing surface to its bottom where it joins with an in-tegral bot-; tom wall, the side wall being adapted to resist paneling in res-ponse to internal vacuum in the con-tainer, and the bottom wall being adapted co flex inwardly in response to an internal vacuum 20 to prevent the side wall from paneling, providing a flexible high gas barrier closure disc -to close the container, filling the con-tainer with a hot foods-tuff which is a-t a tempera-ture of from about 180F to about 190F and has a substan-tial vapor pressure, to a level. which leaves an unfilled volume in the container, promptly herme-tically sealing the open top by bonding the closure disc to -the seal:Lng surEace in a subs-tan-tially fla-t plane across.
the surface, said disc beiny adapted to :Elex from said plane -to a more inward pos:ition in response -to an in-ternal vacuum to preven-t the side wall Erom paneling, said inward flexings of both the bot-tom wall and closure disc being cooperative -to prevent development of high internal vacuum upon cooling of -the food product, and co-opera-tive with the paneling resistant side wall, thereby -to preven-t - 4a -inward panel:Lng of the side wall, said sealing of the closure disc being effected by using an adhesive selected to provide a seal which is hermetic, will withs-tand -the potentially high internal vacuum developed in -the container and the inward flexing of the closure disc, withstand the reduced partial internal vacuurn which exists subsequent -to the flexings, and ye-t provide easy peel-opening of the closure disc from the container. Suitably the method includes the step of providing a bullc layer as one of said layers with said bulk layer formed at least in part from reground scrap from materials of said other layers. Desirably the me-thod includes the step of bonding the the closure disc to the sealing surface-to provide a T-peel strength of from aboub 3 to 5 pounds per inch. Preferably the method includes the step of pro-viding an ethylene vinyl alcohol co~1ymer as a barrier layer.
The presen-t invention in one further aspect thereof pro-vides a method for providing a high gas barrier multilayer plas-tic con-tainer having a food product therein and being hermetically sealed by a high gas barrier easily peel-openable flexible clo-sure, the food product having been filled at a -temperature up to abou-t 190F under condi-tions sufficien-t -to develop a high moisture 20 vapor pressure in the sealed con-tainer, -the container being adap--ted to prevent the development of high internal vacuum -therein upon condensation of the mois-ture vapor of the produc-t, hold a reduced internal vacuum and prevent paneling of the container side wall, comprising -the s-teps of: providing an open--top plastic con-tainer body of mul-tilayer cons-truc-tion which includes a high gas barrier layer, the body having a side wall extendin~ frmi-ts top where i-t has an annular sealing surface to i-ts bottom where it joins with an integral bottom wall, the side wa:ll being adapted to resist paneling in response to internal vacuum in the container, and -the 30 bottom wall being adapted -to flex inwardly in response to an inter-nal vacuum to prevent the side wall from paneling, providing a flexible high gas barrier closure disc -to close said container, - 4b -filling the container w:i.th a foodstuff to a level which leaves an unfilled volume in the container, under condi-tions sufficient -to develop high moisture vapor pressure in the con-tainer, promp-tly herme-tically sealing -the open top by bonding -the closure disc to the sealing surface in a substantially fla-t plane across the sur-face, said disc being adapted -to flex from said plane to a more inward position in response to an internal vacuum to prevent the side wall from paneling, said inward flexings of the bot-tom wall and closure disc being cooperative -to prevent development of high internal vacuurn upon cooling of -the food product, and cooperative with the paneling resis-tan-t side wall, -thereby -to prevent inward paneling of the side wall, said sealing of the closure disc being effected by using an adhesive selected to provide a seal which is hermetic, will wi-thstand the potentially high internal vacuum developed in the con-tainer and the inward flexing of the closure disc, wi-ths-tand the reduce par-tial internal vacuum which exists subsequent to the flexings, and yet provide easy peel-opening of the closure disc.from -the con-tainer. Suitably-the method includes the ~-tep of providing a bulk layer as one of said layers with said bulk layer 20 formed at least in part from reground scrap from materials of said other layers~ Desirably-the me-thod includes-the step of bonding the closure disc .to-the sealing surface with a T-peel streng-th of from about 3 -to 5 pounds per inch. Preferably-the method includes the step of providing an ethylene vinyl alcohol copolymer as a barrier layer.
The present invention will be further illus-trated by way of the accompanying drawi.ngs, in which:-Figure 1 is a side elevational view of a pair of con-tainer bodies emboclying the principles of -the instan-t invention, the bodies being shown in nested posi-tion with the outer body 30 sectioned to ill.ustrate certain details of construction;
Figure 2 is a top view of Figure l;
Figure 3 is an enlarged vertical cross-sectional view , ; ~ ., . - 4c -3t~
-taken through the curled l1p formed around the periphery of a Eilled container body, the view also showing por-tions of -the peel-able closure disc and a heated sealing plate adap-ted to heat-seal the disc onto the curled lip;
Figure 4 is an enlarged ver-tical cross-sectiona] view taken -through the multiple layer wall of the container body;
Figure 5 is an enlarged vertical cross-sectional view taken through a bottom corner por-tion of the container body; and Figure 6 is a schematic cross-sectional view of -the filled and sealed container after the -top closure disc and the bottom wall of the sealed container have flexed inwardly as the resul-t of the in-ternal vacuum created by the cooling of the hot filled produc-t.
Referring to the drawings and in particular -to Figure 1, there is shown a plurality of one piece thermoformed con-tainer bodies 10 embodying the principles of the instant inven-tion and disposed in stacked and nes-ted relationship. Each container body 10 has a cup shape and is formed with a tapered main or side wall 12 which at its bo-ttom end merges in-to a pedestal base, generally indicated by the numeral 14, which forms the bottom end portion of the container. The base 14 includes a rounded corner portion 15 which connects the base 14 and the side wall 12, and an in-wardly and downwardly angled reinforcing wall 16 which is disposed at abou-t a 45 angle. The angled wall 16 merges in-to a shor-t ver--tical wall 18 which in turn connects with a horizon-tal or trans-verse bottom wall 20 which is formed with a plurality of annu:Lar grooves or corrugatic)ns 22 which cross-sectional configura-tion de-fines means which permit diaphragma-tic flexing of the wall 20, as will be hereinafter explained. As best seen in Fig.s 5 and 6, the bottom wall 20 be-tween the outermos-t annular groove 22 thereof and the pedestal base wall 14 includes a downwardly extending annular bead which provides a seating surface for the container.

,~ - 4d -A plurality of spaced, vertical, inwardly extending indentat:Lons 24 which at their upper ends create inwardly ex-tending ledge por-tions 25 which faciIi-tate non-wedging nes-ting of -the container bodies 10 and which also strengthen the bottom por-tion of -the con-tainer body and help -to reinforce it against deformation, are formed in the pedestal base 14.
As best shown in Figure 3, the -top of container body 10 is formed with a peripheral curled lip 26 having a top portion 28. The -top portion 28 provides an annular sealing surface which 10 is impor-tant from the standpoint of ensuring proper sealing of the container as will become more apparent hereinafter. A flat annular lip, rim or flange or combination thereof wi-th a curled portion may also be used.
The materials used in -the construction of container body 10 comprise multiple layers including an inner polyolefin layer 32 made preferably of polyethylene or polypropylene or blends thereof, an adhesive layer 34 made preferably of a compa-tible material such as a modified polypropylene or a modified polyethylene, a barrier layer 36 made of a plastic material such as ethylene vinyl 20 alcohol copolymer, saran, e-tc. which is substantially impervious -to oxygen, another compatible adhesive layer 38 similar or iden-ti-cal to the layer 34, a bulk layer 40 preferably bu-t no-t neces-sarily consisting of reground scrap genera-ted during manufacture of -the bodies 10, and an outer polyolefin layer 42 preferably similar or identical in composition -to the inner polyolefin layer 32. It will be appreciated that the barrier layer 36 serves pri-marily to prevent oxygen from pene-trating the container af-ter fil-ling and sealing, although i-t may also serve as a barrier for other gases or fluids. The layer 40 functions primarily to add bulk and 30 strength to the - 4e -body at low cost. The thicknesses of the various body layers can be varied as desired and required, but it has been found that cup shaped bodies constructed from these mult;ple layers should have a total thickness of at least 15 mils and preferably of about 20 mils.
In accordance with the invention the container body 10 is filled with a hot liquid product such as jam 50 which has been heated to a temperature up to about 190F. AFter filling, the container is sealed with a flat imperforate and impervious closure disc 5S which is preferably made of aluminum foil 56 provided on its undersurface a heat sealable adhesive layer 57 capable of adhering to top portion 28 of the curled lip 26 of the body 10. If desired, a suitable oxygen-impervious thermoplastic material such as ethylene vinyl alcohol copolymer (EVOH) or saran may be substituted for the aluminum foil 56.
The closure disc 55 may be a laminate in which the aluminum foil 56 is laminated on one or both sides to a suitable layer of a protective plastic material such as a nylon, a polyester or a polyoleFin, one of which may function as the adhesive 57 which adheres the disc 55 to the annular body portion 28. Preferably, the hot melt adhesive 57 is chosen to provide a peel strength sufficiently low in magnitude to permit easy peeling of the disc 55 from the body 10 when it is desired to open the container. It has been found that T-peel strengths (ASTM D 1876-72) on the order of about three pounds per inch are ideal for the present purpose, since they permit easy opening of the container while at the same time providing sufficient strength to maintain the integrity of the seal during normal processing and handling of the container, as will be more fully described. Substantially hiyher T-peel strengths than the ideal peel strength such as greater than five pounds per inch will provide thle resistance necessary to maintain the seal integrity, but they prevent easy peelability of the closure disc.

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The cover di.sc 55 is preferably formed wi.th a small, integral, radially projec-ting opening -tab 58 and may be applied in any suitable manner as by a flat heated sealing ring or plate 59 which engages -the upper layer 60 of the closure disc 55 and presses its peripheral edge por-tion against the -top surface 28, while at the same time heating the disc 55 sufficiently to sof-ten the adhesive 57 and cause it to heat-seal -to the top annul.ar sur-face 28. The contacting surface of -the sealing plate 59 may be coated with Teflon or the li.ke -to prevent the upper surface of the 10 closure disc 55 from sticking to it.
It will be appreciated that upon subsequent cooling of the hot filled product 50, the closure disc 55 and bot-tom wall 20 are pressed inwardly by atmospheric pressure as a subsantial par-tial vacuum, is formed wi-thin the sealed con-tainer due primarily to condensation of moisture vapor which is present in the head space 62 of -the filled and sealed container. For a completely rigid container, the vacuum formed upon cooling would be about 20 inches of mercury. The purpose of this container is for use with liquids -that have a measurable vapor pressure when hot-filled such 20 that upon cooling, a vacuum is generated. For commercial filling operations, head space 62 is desireable to prevent over-filling of the containers and spilling the contents jus-t prior to the heat sealing operation. It will be fur-ther appreciated -that because of this inward flexing of the closure disc 55 and bo-ttom wall 20, the partial vacuum is substantially reduced and the s-tresses on the closure seal and the side wall relieved so that the container seal is maintained and deformation or paneling of the side wall 12 of the container is prevented, as seen illustratively in Fig. 6 and wherein the side wall is free of deformation or paneling -through-:30 out its periphery. Annular grooves 22 provide -the means for the flexing motion of bo-ttom wall 20. Because -the diameter of the pedes-tal wa]l 14 as defined is -the minimum diameter of the con-..'~

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tainer slde, the stifEness ~t the junction between the pedestal wall 14 and slde wall 12 is stiffened. 'rha-t s-tiffness is essen-tial -to permi-t the -Elexure at the annular grooves 22 and -to prevent deforma-tion at - 6a -,- :

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the juncture o~` the pedestal and side wall 12. It should be understood that the high internal vacuum formed within the sealed container also subjects the pedestal base 14 to a high pressure differential, and unless some provision is made to prevent it, could cause it to partially deform inwardly before or at the same time as the bottom wall 20 i.s being flexed inwardly. This undes;rable result is prevented by the reinforcing wall 16 which supports the pedestal base 14 at the area of its greatest vulnerability, and thus limits the inward movement of the body 10 to the inward flexing of the bottom wall 20.
After cooling, and in the proper case solidification of the product 50, the container may be easily opened by having the user grasp the opening tab 59 and pull upwardly on it, thus breaking the adhesive bond and peeling the closure disc 55 from the top sealing surface 28.

Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A hot-filled hermetically sealed gas barrier multi-layer plastic container with a side wall free of deformation hav-ing therein a headspace which includes moisture vapor, a sterilized hot-fillable food product and a substantial partial internal vacuum, said food product in the container having a measurable vapor pressure when hot filled into the container at a temperature of up to about 190°F to a level leaving a headspace and under con-ditions sufficient that there develops measurable moisture vapor pressure in the container after it is hermetically sealed, and upon cooling of and consequent condensation of the moisture vapor of the food product, there develops said substantial partial in-ternal vacuum in the container comprising, an open-top plastic body of multilayer construction which includes a gas barrier layer substantially impervious to oxygen, said body having: (1) an annu-lar sealing surface about the open top, (2) a bottom wall having a transverse cross-sectional configuration defining means which per-mits diaphragmatic flexing thereof inwardly of said body, (3) a side wall free of paneling or deformation notwithstanding said internal vacuum upon cooling of the hermetically sealed hot food product, (4) said bottom wall being disposed in an inwardly flexed position due to internal vacuum, and having gradually moved to said flexed position from a more outward unflexed substantially planar initial position located substantially with the axial length of said plastic body prior to hot filling and sealing while having cooperatively gradually and substantially reduced the sub-stantial or high internal vacuum as it was developing while the hot food product was cooling, a gas barrier impervious flexible closure disc hermetically sealed to the sealing surface by adhe-sive means defining with said closure disc and body the hermetic sea], which withstands the high internal vacuum which gradually develops upon cooling of and consequent condensation of the moisture vapor of the product, withstands the subsequent substan-tially reduced internal vacuum, and yet allows easy peel removal of the disc from the sealing surface, said closure disc also being disposed in an inwardly flexed position due to internal vacuum, as allowed by the headspace, and having gradually moved to said flexed position from a more outward unflexed initial position of a substantially flat plane across said sealing surface while also having coperatively gradually and substantially reduced the high internal vacuum as it was developing, a sterilized hot-fillable food product in the container, said food product having a measur-able vapor pressure when hot-filled into the container at a tem-perature of up to about 190°F after the container is hermetically sealed, and, a headspace in said container between said food pro-duct and the said closure disc when hermetically sealed, said ad-hesive means, and said cooperative inwardly flexed positions of said closure disc and integral bottom wall together having co-operatively substantially reduced or dissipated the high internal vacuum, and together cooperatively maintaining the substantially reduced internal vacuum in the container, said side wall unpaneled, said hermetic seal unruptured, and said closure disc easily peel-able.

2. The container of claim 1, wherein one of said layers is a bulk layer formed at least in part from reground scrap materials of said other layers.

3. The container of claim 1, wherein said adhesive seal for said closure disc has a T-peel strength of from about 3 to 5 pounds.

4. The container of claim 1, wherein said body includes an ethylene vinyl alcohol copolymer as a barrier layer.

5. The container of claim 1, wherein said closure disc includes an ethylene vinyl alcohol copolymer as a barrier layer.

6. The container of claim 1, wherein said body and said closure disc each include an ethylene vinyl alcohol copolymer as a barrier layer.

7. The container of claim 1, wherein said side wall is of tapering frustoconical configuration throughout a major portion of the axial extent thereof and merging into a generally cylindri-cal and substantially vertically extending rigid pedestal wall of lesser diameter, said pedestal wall merging into said bottom wall.

8. A container according to claim 7, wherein said pedes-tal wall is connected to the frustoconical side wall by means of an upwardly and outwardly angularly extending reinforcing wall, said reinforcing wall extending at an angle of about 45° to the container longitudinal axis and wherein further said frustoconical side wall includes at its lower end a downwardly and inwardly curving rounded corner merging into said reinforcing wall.

9. The container of claim 1, further including stack-ing formations in said side wall and permitting easily separable nesting of a plurality of empty said plastic bodies.

10. A method for providing a high gas barrier multi-layer plastic container having a food product therein and hermeti-cally sealed by a high gas barrier easily peel-openable flexible closure, the food product having been hot-filled at from about 180°F to about 190°F, the container being adapted to prevent the development of high internal vacuum therein upon cooling of the product, hold a reduced internal vacuum and prevent paneling of the container side wall, comprising the steps of: providing an open-top plastic container body of multilayer construction which includes a high gas barrier layer, the body having a side wall extending from its top where it has an annular sealing surface to its bottom where it joins with an integral bottom wall, the side wall being adapted to resist paneling in response to internal vacuum in the container, and the bottom wall being adapted to flex inwardly in response to an internal vacuum to prevent the side wall from paneling, providing a flexible high gas barrier closure disc to close the container, filling the container with a hot foodstuff which is at a temperature of from about 180°F to about 190°F and has a substantial vapor pressure, to a level which leaves an un-filled volume in the container, promptly hermetically sealing the open top by bonding the closure disc to the sealing surface in a substantially flat plane across the surface, said disc being adap-ted to flex from said plane to a more inward position in response to an internal vacuum to prevent the side wall from paneling, said inward flexings of both the bottom wall and closure disc being cooperative to prevent development of high internal vacuum upon cooling of the food product, and cooperative with the paneling resistant side wall, thereby to prevent inward paneling of the side wall, said sealing of the closure disc being effected by using an adhesive selected to provide a seal which is hermetic, will withstand the potentially high internal vacuum developed in the container and the inward flexing of the closure disc, with-stand the reduced partial internal vacuum which exists subsequent to the flexings, and yet provide easy peel-opening of the closure disc from the container.

11. The method of claim 10, further including the step of providing a bulk layer as one of said layers with said bulk layer formed at least in part from reground scrap from materials of said other layers.

12. The method of claim 10, further including the step of bonding the closure disc to the sealing surface to provide a T-peel strength of from about 3 to 5 pounds per inch.

13. The method of claim 10, including the step of pro-viding an ethylene vinyl alcohol copolymer as a barrier layer.

14. A method for providing a high gas barrier multi-layer plastic container having a food product therein and being hermetically sealed by a high gas barrier easily peel-openable flexible closure, the food product having been filled at a tem-perature up to about 190°F under conditions sufficient to develop a high moisture vapor pressure in the sealed container, the container being adapted to prevent the development of high internal vacuum therein upon condensation of the moisture vapor of the pro-duct, hold a reduced internal vacuum and prevent paneling of the container side wall, comprising the steps of: providing an open-top plastic container body of multilayer construction which in-cludes a high gas barrier layer, the body having a side wall extending from its top where it has an annular sealing surface to its bottom where it joins with an integral bottom wall, the side wall being adapted to resist paneling in response to internal vacuum in the container, and the bottom wall being adapted to flex inwardly in response to an internal vacuum to prevent the side wall from paneling, providing a flexible high gas barrier closure disc to close said container filling the container with a foodstuff to a level which leaves an unfilled volume in the container, under conditions sufficient to develop high moisture vapor pressure in the container, promptly hermetically sealing the open top by bond-ing the closure disc to the sealing surface in a substantially flat plane across the surface, said disc being adapted to flex from said plane to a more inward position in response to an inter-nal vacuum to prevent the side wall from paneling, said inward flexings of the bottom wall and closure disc being cooperative to prevent development of high internal vacuum upon cooling of the food product, and cooperative with the paneling resistant side wall, thereby to prevent inward paneling of the side wall, said sealing of the closure disc being effected by using an adhesive selected to provide a seal which is hermetic, will withstand the potentially high internal vacuum developed in the container and the inward flexing of the closure disc, withstand the reduced partial internal vacuum which exists subsequent to the flexings, and yet provide easy peel-opening of the closure disc from the container.

15. The method of claim 14, further including the step of providing a bulk layer as one of said layers with said bulk layer formed at least in part from reground scrap from materials of said other layers.

16. The method of claim 14, further including the step of bonding the closure disc to the sealing surface with a T-peel strength of from about 3 to 5 pounds per inch.

17. The method of claim 14, including the step of pro-viding an ethylene vinyl alcohol copolymer as a barrier layer.