US3454158A - Vacuum package and container therefor - Google Patents

Description

July 8, 1969 R. A. TIGNER 3,454,158

1 VACUUM PACKAGE AND CONTAINER THEREFOR F1198 May 17, 1967 Sheet' of s INVENTOR.

. Ruen l9. Tyne! Mam .JQTTOR/VfYj v y 3, 1969 v 'R. A. TIGNER 3,454,153

VACUUM PACKAGE AND CONTAINER THEREFOR Filed May 17, 1967 Sheet '3 of s INYENTOR. Ruben 9. 7/9/00 United States Patent ()7 U.S. Cl. 206-78 47 Claims ABSTRACT OF THE DISCLOSURE A vacuumpackage having a generally flat base formed of a film and foam laminate, a product supported on the base, and a self-supporting cover preformed to product shape such that when fitted over the product and hermetically sealed to the base a generally intimate contact is obtained between the container and product. The base is characterized by its self-supporting yet relatively pliant or deformable nature, and when deformed is substantially stress free such that upon creating a vacuum environment within the package, the base can freely deform or distort to self-adjust the inner volume of the container to that necessary to snugly engage the product contained therewithin.

This invention relates generally to a vacuum package wherein the container portion thereof is self-supporting but deformable by vacuum pressures such as normally incurred in luncheon meat and the like vacuum or gas flush packages.

Vacuum packages of this type have been used with various degrees of success by the packaging industries for some time. The self-supporting container construction is especially advantageous in providing storage and reclosability features after initial opening. For these reasons, they are often preferred over containers formed either solely or partly of a non-self-supporting type film for the vacuum packaging of perishables which oftentimes would not be consumed at one sitting, and which would require storage after the initial opening.

The prior containers employed in packages of this sort have generally included a relatively stiff or rigid base portion to support a product, and a self-supporting but generally less rigid cover preformed to product shape such that when fitted over the product and sealed to the base, an intimate contact is obtained between the container and product. Intimate contact enables the product to at least partially support and prevent distortion of the container from vacuum pressures of the degree normally encountered in vacuum packaging operations. Obtaining and maintaining a hermetic seal in this type vacuum package can be troublesome since variations do occur in product height or transverse dimensions which affect the fit and intimate contact between the preformed cover and product such that, under vacuum pressures, a stress and possibly even a distortion can be caused in the joining or sealing portions of the container resulting in a weakening or rupturing of the hermetic seal.

A weakening of the hermetic seal resulting from the above conditions can be even further aggravated by product and container volume changes incurred during the subjection of the package to the variety of temperature environments encountered in its normal progression through initial filling, distribution, storage, sale, and consumer handling. Especially so vulnerable is a hermetic seal of the type employing a permanently soft tack adhesive to provide resealability features. I-Iere even relatively minor stress forces incurred over a period of time can cause the seal to creep and eventually rupture. To

Patented July 8, 1969 lessen the criticalness of dimensional fit between the preformed cover and product, therefore, some selfsupporting containers, such as that shown in US. Patent No. 3,087,823, have been equipped with an outwardly extending hollow bead or rib in the body portion thereof designed to absorb excess product volume. While it is true that the use of such beads has somewhat lessened the fit tolerances between the preformed cover and product, they have generally not been entirely satisfactory. One problem is that they can form voids which usually accumulate the remaining air in the package. The oxygen in the trapped air thus becomes concentrated in one area and often causes a quick discoloring of a contained meat product or the like, thereby reducing package shelf life. Also, the use of such means relies on deformation and absorption of the excess product into the fixed volume provided by the hollow bead, and consequently can even further adversely effect the degree of fit in instances where the product dimensions are less than those of the preformed cover.

Accordingly, it is an object of the present invention to provide a self-supporting container for a vacuum package, which container is self-adjustable to compensate for variances in the volume of the individual units of the product being packaged, and also to provide a vacuum package employing such a container.

It is another object of the present invention to provide a container for vacuum packaging having an especially effective and simple mechanical locking feature between the joining or sealing portions thereof to facilitate reclosing after initial opening, and also to provide a vacuum package employing such a container.

It is another object of the invention to provide a container for vacuum packages of such construction as will result in considerable savings of material therein, and also to provide a vacuum package employing such a container.

Another object of the present invention is to provide a container for vacuum packaging of an especially convenient hinged construction, and also to provide a vacuum package employing such a container.

Yet another object of the invention is to provide a vacuum package having an especially tough, relatively stress free hermetic seal, which package can be especially easily opend by the ultimate consumer, and which can serve as an effective storage means after the initial opening.

Still another object of the invention is to provide a vacuum package which can be hermetically sealed by a permanently soft tack adhesive such that the package can be rescaled after the initial opening thereof to better protect the remaining unused portion of the product.

Briefly then, the invention comprises a vacuum package including a container preferably having a generally flat self-supporting base formed from a plastic film and plastic foam laminate, and a preformed cover of a selfsupporting nature, preferably pressure formed from a plastic web material and generally marginally secured to the base. The plastic film and foam laminated base, it was found, possessed the particularly advantageous characteristics of being self-supporting to furnish effective package reclosability features, and yet being relatively pliant or deformable, and when deformed, relatively stress free. This latter characteristic, as will be explained more fully hereinafter, permits self-adjustment of the container inner volume to substantially that of the product, and also advantageously permits especially easy initial package accessibility or opening. The base and cover can be of hinged construction for storage convenience if desired, and are preferably hermetically sealed together by means of a permanently soft tack adhesive such that the package can be rescaled closed after initial opening to better protect the product from contamination and dehydration during the period of consumption. The invention further contemplates special mating closure designs between the joining or sealing portions of the base and cover. In one of these, the cover books into and pressure seats in a marginally disposed base groove to obtain a mechanical locking feature. Another is disposed considerably outwardly of the main body of the package to be remote from and even less affected by possible stresses created therein. Yet another has a unique tongue and groove arrangement which can be especially advantageously employed in combination with a container of hinged construction.

Yet additional objects and advantages of the present invention will be even more apparent from the ensuing description taken with the accompanying drawings where in like characters of reference designate corresponding material and parts throughout the several views thereof, in which:

FIGURE 1 is a plan view of a vacuum package constructed according to the principles of the present invention;

FIGURE 2 is an enlarged cross-sectional view, with portions broken away, taken along reference line 2-2 of FIGURE 1;

FIGURE 3 is a plan view of another vacuum package constructed according to the principles of the present invention;

FIGURE 4 is an enlarged fragmentary cross-sectional view taken along reference line 4-4 of FIGURE 3 showing the joining or sealing configuration employed;

FIGURE 5 is a view like FIGURE 4 only showing a modified form thereof;

FIGURE 6 is a plan view of a hinged vacuum package constructed according to the principles of the present invention; and

FIGURE 7 is an enlarged cross-sectional view, with portions broken away, taken along reference line 77 of FIGURE 6.

Referring now more particularly to the drawings, there is shown in FIGURES 1 and 2 a vacuum package 10 of shallow generally rectangular configuration, basically comprising a product 12 such as luncheon meat, cheese, frankfurters, chile and the like, vacuum packed within a hermetically sealed self-supporting container 14.

Container 14 includes a generally flat self-supporting yet relatively pliant or deformable base 18 and a plastic cover 20, preformed to product shape and peripherally mateable with base 18. In other words, cover 20 has a configuration in substantial conformance with the configuration of the product 12 contained therewithin be it fiowable like chili, in individual parts like a plurality of frankfurters, or solid like cheese, whereby a generally intimate contact between the cover 20 and the product 12 is obtained. The base 18 comprises a film and foam laminated structure and is preferably pressure formed from a sheet of such laminate material to provide an upper ply 22 of plastic film and a lower ply 24 of plastic foam. The material employed can be laminated prior to the preferred pressure forming step such as by adhesives, heat laminating or other well known or applicable techniques, or simultaneously therewith such as by a process like that illustrated in US. Patent 3,039,911. Essentially the film ply 22 provides a barrier to the passage of air and vapor to better maintain the vacuum environment within package 10. Film ply 22, however, also benefically imputes extra tensile characteristics to base 18 to allow better endurance to repeated opening and reclosing operations by lessening the possibility of premature splitting or cracking of the generally tensilely less hardy foam. Preferred films having both sufiicient barrier and tensile characteristics and which can be advantageously employed in the present invention include saran and polyvinyl chloride and variously modified homopolymers and copolymers thereof. Other films or multilayered combinations of films having barrier and tensile characteristics generally similar to the above specifically enumerated films also are intended to be within the scope of the present invention. The exact thickness employed will vary as to the specific film or multilayered film used and the degree of characteristics desired. For saran a thickness about 0.5 mil is sufiicient While 2.5 mils will provide exceptionally excellent tensile and impervious characteristics. Foam ply 24 preferably comprises an expanded polystyrene which is of a relatively low material cost and advantageously imputes base 18 with self-supporting, but relatively freely pliant or deformable characteristics of the general nature previously discussed. Benefically, foam densities of about 3 to 12 lbs. per/cu. ft. and thicknesses of between about 10 to mils can be employed with the optimum choice varying considerably with different package sizes, dimensions, and weights, and conceivably lying outside the above perimeters as to a particular package. Other foams, however, having self-supporting yet pliant characteristics like polystyrene foam, such as polyethylene foam, can be employed to practice the present invention if desired.

Base 18 includes a generally flat portion 26 to receive and support product 12, and a marginal groove 28 peripherally integral with flat portion 26 and adapted to securely receive cover 20. Groove 28 has a skirt or inner wall 30 extending generally downwardly from flat portion 26 and defining a horizontal shoulder 32 therewith, and a tubular shaped outer wall 34 necking inwardly at its upper portion to provide an inner pocket or undercut wall portion 38. Base 18 also beneficially includes a circular support rib 40 integrally formed with and protruding downwardly from flat portion 26 inwardly of groove 28, and a peripherally continuous tab or lip 36 extending outwardly of outer wall 32 of groove 28. Rib 40 is especially advantageously employed on the relatively large vacuum packages of the invention where heavy product weight might otherwise tend to bow or deform the base 18.

Cover 20 encloses product 12 and is preferably preformed from a plastic web of material by usual pressure forming techniques, the web employed being of sufiicient thickness to provide both adequate air and vapor barrier characteristics and a self-supporting structure of preferably more rigidity as formed than base 18. A polyvinyl chloride web material is preferred because of both relatively excellent barrier and rigidity characteristics, but other plastics or multilayered combinations thereof having properties like polyvinyl chloride such as saran or a saran coated polystyrene, can be utilized to form cover 20.

Most advantageously cover 20 is transparent to allow free viewing and inspection of product 12 and includes a top 42, and a sidewall 44 peripherally integral with and depending downwardly and outwardly therefrom to engage groove 28 of base 18. Sidewall 44 defines a horizontal shoulder 46 which beneficially mates with shoulder 32 of base 18 and ends in groove 28 in an upwardly and outwardly curving hook 48 pressure seated against the relatively soft foam backed undercut wall portion 38 of groove 28 to mechanically lock base 18 and cover 20. Sidewall 44 also includes a skirt portion 45 depending generally downwardly from shoulder 46 and merging with hook 48. Optionally, skirt 45 can be sloped inwardly or reverse sloped (not shown) such as to allow convenient stacking of a plurality of covers 20 prior to use or dispensing.

Vacuumization of package 10 can be had by assembly in a sealed vacuum chamber of a similar type to that employed in US. Patent No. 3,087,823, or by other well known and suitable vacuumizing techniques such as by the insertion of a hollow needle and the drawing of a vacuum therethrough followed by a patching or sealing step. Preferably a hermetic seal is obtained by means of a soft tack adhesive which is placed in groove 28 and which remains in a soft or tac-ky state to permit the resealing of package after initial opening. A variety of suitable adhesives having the above general characteristics are well known to the prior art and can be employed in the practice of the present invention, as for example, a copolymer of 50% styrene and 50% butadiene applied in latex form and later solidified to form an adhesive layer. However, heat sealing where materials are compatible or other well known and applicable sealing techniques, such as sealing by heat sensitive adhesives can be employed if desired, and especially if resealability features are relatively unimportant. Heat scaling is especially advantageously employed where a tough biaxiallyorientated film comprises film ply 22. Here, upon application of the heat seal, the film ply 22 in the vicinity of the seal becomes randomly orientated, losing much of its original tensile strength and in effect forming a weakened tear line upon which package 10 can be readily opened. Another advantageous application of a heat seal is at horizontal shoulders 46 and 32 in combination with a tack adhesive in groove 28. In this sealing arrangement possible creep of the soft tack adhesive seal is negated while still allowing for package resealability.

Especially advantageous features of package 10 are easy accessibility combined with positive package reclosability after the initial opening, in part discussed above in regard to preferred sealing arrangements. In the relatively rigid base prior art self-supporting vacuum packages, the whole of the sealing area would generally be broken simultaneously when initial opening the package requiring a maximum of separation force. In contrast, the package of the present invention can be opened by merely peeling the base 18 from the preferably more rigid cover 20, the force employed being minimal and only a relatively small tab 36 being conveniently provided as a gripping area. Despite the peeling deformation incurred by the foam and film base 18 upon the initial opening, the base has been found to be structurally capable of recovering sufficiently to afford excellent reclosability features. Thus, package 10 can be simply reclosed by rolling base 18 forward with hook 48 being reseated against the undercut wall portion 38 of groove 28 to mechanically lock the unused portion of product 12 within the protective confines of container 14. Additionally, assuming a tack adhesive had been originally employed to seal package 10, a resealing of the packagecan advantageously be obtained in the same manner.

Another particularly advantageous aspect of package 10 is the capability of container 14 to adjust in internal volume to compensate for variances which can occur in the individual units of product 12 being packaged. Particularly important to this aspect of the invention is the character of base 18 which, despite being of a self-supporting structure, is relatively pliant or deformable and when deformed is relatively free of internal stress. Thus, when a vacuum is created within package 10, base 18 can relatively freely deform to snugly engage the product 12 thereby adjusting the inner volume of container 14 to compensate for variances in product volume. Additionally, the base 18 has been found capable of relatively freely following slight inwardly or outwardly movement of the sidewall 44 of cover 20, Without setting up a serious counteracting stress force which, in the more rigid base packages, would attempt to transverse the movement of the sidewall 44, and consequently often create a significant stress in the hermetic seal.

The base 18 is bendable in any direction while the cover 20 substantially resists bending along transverse lines extending from opposite sidewalls. When joined together with the hook 48 sealed in groove 28, the base 18 and cover 20 complement one another so that the package 10 substantially resists bending in every direction. A substantially warp-free sturdy package is thereby obtained.

An advantageous variation in the present invention is vacuum package 50 employing a modified and especially stress resistant hermetic seal and illustrated in FIGURES 3 and 4.

Package 50 is of similar shape to and constructed of materials like those of package 10, and thus basically includes a generally flat base 52 to receive product 12, and a selfsupporting cover '54 substantially preformed to and enclosing product 12 and hermetically sealed to base 52. Base 52 comprises an upwardly pointing groove or ridge 56 (best illustrated in FIGURE 4) running along and within the periphery thereof, a relatively flat portion 58 extending inwardly of ridge 56, and a lip 60 extending outwardly of the ridge 56 and in spaced and horizontally planar relationship with flat portion 58. Cover 54 of package 50 includes a top 62,rand a sidewall 64 depending downwardly and outwardly therefrom to engage base 52. Sidewall 64 includes a flange 66 extending generally outwardly therefrom adjacent flat portion 58, a hollow upwardly pointing groove or ridge 68 depending from flange 66 and mated over ridge 56 of base 52, and a lip 70 extending outwardly of ridge 68 in superimposed relationship with lip 60 of the base 52.

Package 50 is preferably sealed between mating ridges 56 and 68 by means of a permanently soft tack adhesive of the general type and quality previously discussed. This type sealing arrangement is particularly facilitated by having ridges 56 and 68 lying generally outwardly of the main body of package 50, well removed from and le alfected by any stresses created therein, and consequently providing a relatively stress free seal area. If desired, however, a variety of other sealing means can be employed, such as those previously discussed with regard to package 10. Additionally, a particular advantageous combination sealing arrangement, if such is desired, could employ the above mentioned tack adhesive seal between ridges 56 and 68 and a heat or hot melt adhesive seal between the flange 66 and base 52 to negate possible seal creep while still retaining package resealability features.

Sidewall 64 also includes a horizontal shoulder 72 defined generally intermediate of top 62 and flange 66, which can advantageously be employed with a modified base 74 as illustrated in FIGURE 5. Base 74 is similar to previously described base '52, but additionally includes a horizontal shoulder 76 between a raised flat portion 77 and a flange 79 which beneficially mates with shoulder 72 of sidewall 64. The horizontal and vertical mating obtained thereby further deters a shift between the j ining portions of cover 54 and base 74 and resulting creep in the hermetic seal.

Another advantageous embodiment of the invention is vacuum package 80 illustrated in FIGURES 6 and 7 and employing a container 82 of hinged construction, the container 82 being constructed of materials similar to that previously discussed herein.

Container 82 includes a mateable cover 86 and base 84 having corresponding and opposed rear hinging flaps 88, 89 and frontal tabs 90, 91. Flaps 88, 89 are preferably secured by mechanical means, such as the staples 92 shown in FIGURE 6, or can be secured by heat sealing where compatible, or by adhesives, solvents or other Well known and applicable techniques. Cover 86 is preferably scored along a line 94 on flap 88 (best illustrated in FIG- URE 6) to provide a relatively free and smooth hinging motion. Tabs 90, 91 are employed to provide convenient gripping surfaces for peeling or otherwise separating the base" 84 from cover 86 and mos-t advantageously includes a concentrally disposed aperture 96 which allows package'80 to be attractively displayed on a pronged rack or other equally suitable means. Preferably, tabs 90, 91 are lightly secured such as by heat sealing, adhesives or other applicable means with tab of cover 86 being provided with an approximately thumb-sized cut-out 98 to facilitate the initial separating action.

Flaps 88, 89 and tabs 90, 91 can be advantageously employed in combination with a tongue and groove-type mating engagement between the cover 86 and base 84 (as illustrated in FIGURE 7). Here base 84 includes a generally peripherally disposed groove 100, and a lip 102 integral with groove 100 and extending outwardly therefrom, lip 102 being merged with flap 89 and tab 91 at the respective front and rear portions of base 84. Cover 86 correspondingly includes a tongue portion 106 in substantial conformance to and in mating engagemet with groove 100 of base 84, and a lip 108 extending outwardly of tongue 106 adjacent to and superimposed upon lip 102 of base 84, the lip 108 merging with flap 88 and tab 90 at the respective front and rear portions of cover 86.

Although the present invention has been described with particularity as regards a rectangular package, other geometrical package configurations, such as a cylindrical package, can readily employ the principles thereof and are intended to be within the scope of the invention.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention.

I claim:

1. A package that can support a vacuum environment comprising a product secured within a hermetically sealed container, said container including a base upon which the product is supported, said base comprising at least plastic foam, a plastic cover enclosing the product and hermetically sealed to said base, said cover having a configuration substantially conforming to the configuration of the product it encloses, the foam comprising said base being selfsupporting yet pliant to a degree that the base can relatively freely deform to self-adjust the inner volume of the container to that necessary to snugly engage the product when subjected to the pressure difference between the external atmosphere and the vacuum pressure within the package.

2. The package of claim 1 wherein said base structure comprises at least two layers of material including a layer of plastic.

3. The package of claim 2 wherein said layer of plastic is located above said plastic foam.

4. The packg-ae of claim 3 wherein said layer of plastic is located adjacent to said cover.

5. The package of claim 2 wherein said plastic foam has a thickness in the range of from about mils to about 100 mils.

6. The package of claim 2 wherein said plastic foam has a density in the range of from about 3 lb./ cu. ft. to about 12 lbs./cu. ft.

7. The package of claim 2 wherein said plastic foam includes polystyrene foam.

8. The package of claim 2 wherein said layer of plastic has a thickness in the range of from about .5 mil to about 2.5 mils.

9. The package of claim 2 wherein said layer of plastic includes saran.

10. The package of claim 1 wherein said base and said cover are heat scalable and wherein said container includes a heat seal between the cover and the base.

11. The package of claim 10 wherein said heat se al securing said cover to said base comprises a hermetic seal.

12. The package of claim 1 wherein an adhesive secures said cover to said base.

13. The package of claim 12 wherein said adhesive is permanently tacky to allow the cover to be resecured to the base after initial opening of the package.

14. The package of claim 12 wherein said adhesive securing said cover to said base comprises a hermetic seal.

15. The package of claim 1 wherein said container includes a double hermetic seal between said cover and said base.

16. The package of claim 15 wherein said base and said cover are heat scalable and wherein one of said hermetic seals comprises a heat seal between the cover and the base.

17. The package of claim 15 wherein one of said hermetic seals comprises an adhesive securing said cover to said base.

18. The package of claim 17 wherein said adhesive is permanently tacky to allow the cover to be resecured to the base after initial opening of the package.

19. The package of claim 1 wherein the base includes a generally flat portion to receive and support the product, and an outer wall merged with the lower periphery of flat portion and receiving said cover.

20. The package of claim 19 wherein said groove comprises an inner wall depending from said flat portion and defining a generally horizontal shoulder therewith, and an outer wall merged with the lower periphery of said inner wall and necking inwardly at its upper portion to define an inner pocket within said groove.

21. The package of claim 20 wherein said cover ends in said groove in an upwardly curving hook pressure seated against the inner pocket of said groove.

22. The package of claim 20 wherein said cover includes a shoulder in mating engagement with the horizontal shoulder defined by said fiat portion and the inner wall of said groove.

23. The package of claim 19 wherein a lip extends generally outwardly from said groove which can be grasped to peel said base from said cover.

24. The package of claim 19 wherein said cover includes a tongue portion received in said groove, said tongue portion being generally configured to fit the contour of the groove.

25. The package of claim 24 wherein said base includes a lip extending generally outwardly of said groove and wherein said cover includes a lip integral with said tongue and in superposed relationship to the lip of said base.

26. The package of claim 1 wherein said base includes a relatively fiat portion, an upwardly pointed ridge generally peripherally about said fiat portion, and wherein said cover includes an upwardly pointed and hollow ridge mated over said ridge of said base.

27. The package of claim 26 wherein a skirt extends generally downwardly of said flat portion, and a flange extends generally outwardly of the lower periphery of said skirt and merging with the ridge of said base, said skirt and said flat portion defining a generally horizontal located shoulder.

28. The package of claim 27 wherein said cover includes a shoulder matingly engaged with the horizontal shoulder of said base.

29. The package of claim 1 wherein said base includes a generally downwardly extending rib to better prevent bowing of the base due to the weight of the product supported thereon.

30. The package of claim 1 wherein said cover is hingedly affixed along a portion thereof to said base to facilitate reclosing of the package.

31. The package of claim 1 wherein said cover is of sufficient thickness to be characterized as self-supporting.

32. The package of claim 31 wherein said cover comprises at least two layers of plastic and wherein at least one of said layers is thermoplastic material.

33. The package of claim 32 wherein said layer of thermoplastic material comprises saran.

34. The package of claim 32 wherein said layer of thermoplastic material comprises polystyrene.

35. The package of claim 32 wherein said layer of thermoplastic material comprises polyvinyl chloride.

36. A container that can be employed for the vacuum packaging of a product including a base to receive and support the product, said base comprising at least plastic foam, a preformed self-supporting plastic cover to fit over and enclose the product, said cover being generally peripherally matable with said base, the foam comprising said base being self-supporting yet pliant to a degree that when the container is vacuumized with a product therewithin the base can relatively freely deform to self-adjust 9 the inner volume of the container to that necessary to snugly engage the product.

37. The container of claim 36 wherein said base comprises at least two layers of material including a layer of plastic.

38. The container of claim 37 wherein said layer of plastic comprises the uppermost layer of said base and wherein said plastic foam of said base is a thickness in the range of about 10 to 100 mils and a density of about 3 pounds per cubic foot to about 12 pounds per cubic foot.

39. The container of claim 38 wherein said uppermost layer of plastic is heat scalable to said cover.

40. The container of claim 36 wherein said base includes a generally flat portion to receive and support the product, and a groove located generally peripherally about said flat portion to receive said cover.

41. The container of claim 40 wherein said groove comprises an inner wall depending from said flat portion and defining a generally horizontal shoulder therewith, and an outer wall merged with the lower periphery of said inner wall and necking inwardly at its upper portion to define an inner pocket within said groove, and wherein said cover ends in an upwardly and outwardly curving hook, said cover receivable in said groove with the hook of the cover pressure seating against the inner pocket to mechanically secure together the'cover and the base.

42. The container of claim 40 wherein said cover includes a tongue portion receivable in said groove, said tongue portion being generally configured to fit the contour of the groove,

43. The container of claim 36 wherein said base includes a relatively flat portion, an upwardly pointed ridge located generally peripherally about said flat portion, and wherein said cover includes an upwardly pointed and hollow ridge matable over said ridge of the base.

44. The container of claim 36 wherein said base includes a generally downwardly extending rib to better prevent bowing of the base due to the weight of the product supported thereon.

45. The container of claim 36 wherein said cover is hingedly aflixed along a portion thereof to said base.

46. The package of claim 31 wherein said cover is preformed and includes a top wall and a side wall continuous about the periphery of said top wall and extending generally downwardly therefrom.

47. The package of claim 46 wherein said cover as formed is generally more rigid than said base.

References Cited UNITED STATES PATENTS 2,621,129 12/ 1952 Ramsbottom et al. 20646 X 2,893,877 7/ 1959 Nickolls 99174 3,070,446 12/ 1962 Seiferth et a1. 99-174 X 3,154,898 11/1964 Engles 2068O 3,172,768 3/1965 Joosten et al. 206-4534 X 3,229,810 l/ 1966 Goller et al. 206-4534 DONALD F. NORTON, Primary Examiner.

US. Cl. X.R. 99l74 23 33 UNITED STATES PATENT OFFKIE CERTKFICATE 0F CORRECTION Patent No. 3, -5 I-,l58 Dated July 8, 1969 Inventor 5/) Ruben A I'igner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

T Column 8, line 9, strike out "an outer wall merged with the- -lower periphery of" and insert a groove located generally peripherally about said SIGNED ANU SEALED SEP 3 01969 Attest:

EawuaM. Fletcher, Ir. WILLIAM E. comm, A i Offi Domissioner of Pete:

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