US3467244A - Evacuated package with semirigid shell and flexible closure - Google Patents

Description

Sept. 16, 1969 MAHAFFY ETAL 3,467,244

EVACUATED PACKAGE WITH SEMIRIGID SHELL AND FLEXIBLE CLOSURE Filed March 10, 1967 I l0 INVENTORS I4 34 Redd A.Ma/za/' Joel .A. Jfamito [9 L14 ATTORNE United States Patent 3,467,244 EVACUATED PACKAGE WITH SEMIRIGID SHELL AND FLEXIBLE CLOSURE Reid A. Mahatfy, Montclair, and Joel A. Hamilton, Garfield, N.J., assignors to Mahalfy & Harder Engineering Company, Totowa, NJ.

Filed Mar. 10,, 1967, Ser. No. 622,362

Int. Cl. B65d 73/00, 75/00 US. Cl. 206-4534 20 Claims ABSTRACT OF THE DISCLOSURE A composite evacuated package comprising a cup-like shell made of thick semirigid plastic and a closure member of thin flexible plastic film sealed to the shell around the opening thereof, the film being stretched down into the shell between the packaged article and the side walls of the shell a distance suflicient to engage both the central portion of the shell and the side edges of the packaged articles, as to produce a package which automatically adjusts to the size of the packaged articles along at least three transverse surfaces thereof.

This invention relates to the packaging of articles, such as food in evacuated containers. More particularly, this invention relates to composite packages of the type comprising a semirigid cup with a top of flexible and stretchable material which is force-fitted by atmospheric pressure tightly against the article in the semirigid cup.

Copending application Ser. No. 672,146, filed Oct. 2, 1967 by Reid A. Mahaffy and Joel A. Hamilton, discloses apparatus for making packages of the type comprising a semirigid cup and a corresponding top of flexible film extending down into the cup a distance sufficient to engage the packaged articles. The particular package disclosed in that application has many advantages, being especially suited for use with articles of uniform size such as stacks of sliced luncheon meat. It has been found, however, that improved results can be obtained with a new package arrangement to be described hereinbelow. This new arrangement is especially advantageous for products of non-uniform size, such as bacon, but it also may be used with advantage for various other types of products.

One object of this invention is to provide improved vacuum packaging techniques employing semirigid receptacles with flexible closures. A more specific object of this invention is to provide a semirigid package configuration with reduced voids within the package interior. Other objects, aspects and advantages of the invention will in part be pointed out in, and in part apparent from, the following description considered together with the accompanying drawings in which:

FIGURES l and 2 are perspective views of a package in accordance with the teachings of this invention;

FIGURES 3 and 4 illustrate the formation of the pack- FIGURE 5 is a cross-section taken along line 5-5 of FIGURE 4; and

FIGURE 6 is a cross-section view showing a stack of packages.

Referring now to FIGURE 1, the completed package includes an inverted cup-like receptacle 10 made of heavygauge clear plastic to form a semirigid shell. This shell has a trapezoidal cross-section particularly adapted to serve as a receptacle for sliced bacon 12, as disclosed in copending application Ser. No. 484,284, filed Sept. 1, 1965, by R. A. Mahaffy et al.

The shell 10 comprises a central portion 14 (including in this embodiment the three angularly-related upper surfaces) serving as a display window, and two side wall por- Ice tions 16 defining opposite boundaries of a planar opening into the shell. Around this opening and coplanar therewith are marginal portions 18. To close oil? the opening of the shell, there is provided a closure member 20 in the form of a film of thin flexible plastic which is heat-sealed to the marginal portions 18. The hermetically-sealed container thus formed is evacuated, so that the central face 22 of the film 20 is pressed firmly by atmospheric pressure against the bacon slices which in turn are pressed against the display window 14.

Adjacent the sides of the shell 10 the film 20 is stretched interiorly to engage the side wall portions '16, the central display window portion 14, and the side edges of the packaged article, i.e., the ends of the bacon slices. Atmospheric pressure thus not only forces the bacon up against the display window 14 but also form-fits the stretched plastic film tightly against the ends of the bacon. This arrangement substantially reduces the development of voids (empty spaces) along the sides of the packaged article, and assures that the packaged article is held firmly in place.

The package of FIGURE 1 preferably is made by a prestretching technique illustrated in FIGURES 3 and 4. There it will be seen that the thin flexible plastic film 20, which initially was in flat sheet form, has been stretched at two sides so as to develop depending ears 30. This stretching is carried beyond the elastic limit of the film, to minimize creep-back towards the original non-stretched condition. As is conventional, the film may first be heated to enhance its stretchability, and preferably is cooled while still in its stretched state and before application to the semirigid shell, as taught in the above-mentioned copending application Ser. No. 672,146.

Stretching of the film 20 may be effected by vacuumforming. For example, the film may be drawn by vacuum into a die (not shown), having the shape of the shell 10. (Dies of such shape are used as package-forming trays in the apparatus disclosed in the above-mentioned copending application Ser. No. 484,284.) The differential stretching, i.e. the localized stretching at the sides to form the ears 30, may be produced by placing in the interior of the die a filler block (illustrated in outline at 32) having a con figuration somewhat comparable to that of the articles to be packaged. Thus in the case of bacon, the filler block will occupy most of the die cavity, but provide spaces at the sides for the film to be stretched down into the die to form the ears 30.

The vacuum-formed film 20 is positioned over the opening of the shell 10 and heat-sealed to the marginal portions 18 to enclose the packaged article 12, i.e. the bacon. Thereafter the package is evacuated, by known techniques, so that atmospheric pressure forces the central face 22 of the film against the ,bacon and thereby presses the bacon against the display window 14. Atmospheric pressure also forces the stretched ears 30 interiorly of the shell to engage the side wall portions 16, outer border regions of the display window 14, and the side edges 33 of the bacon.

It may be noted that the film material is force-fitted about the irregular ends of the bacon, so as to follow closely the contour thereof. This is particularly beneficial because it minimizes the development of voids in this region. This result may advantageously be achieved by pre-stretching the ears 30 to a depth greater than the depth of the side wall portions 16, as by using a forming die deeper than the shell 10. The excess material of the ears thus produced will provide a good tight fit around the ends of the bacon.

It may also be noted that, by virtue of the differential stretching of the film (i.e., by stretching the film primarily in the side areas thereof) so as to form side ears 30 which extend alongside the ends of the packaged article,

the size of the evacuated container automatically adjusts to the size of the packaged article. This is especially useful for articles such as bacon, the dimensions of which are relatively non-uniform. This self-regulation of the package size is achieved without losing the protection afforded by the semirigid cup-like shell 10. Thus a unique combination of advantageous features is obtained by the novel package configuration disclosed.

The final package also desirably is provided with a flat panel member 34 of reltively stiff paperboard heat-sealed to the shell together with the flexible film 14. This panel member serves as a protective shield and is pre-cut along side lines 36 to permit the interior section of the panel to be flexed up against the film as shown in FIG- URE 5. This construction provides for eflicient stacking of the packages, as shown in FIGURE 6, and thus minimizes required shipping and storage space.

The panel 34 may be formed at one corner of the package with a tab (not shown) adapted to be gripped between thumb and forefinger. By holding the package with the shell 10 down, as in FIGURE 2, this tab can be pulled upwardly to strip the film and panel away from the shell along the front and two sides. The package then may be inverted to the position shown in FIGURE 1 and the shell pivoted upwards along a line 38 of the panel.

To accommodate this pivoting of the shell 10, the panel 34 is partially perforated along line 38 to create a hinge line. After removing the desired amount of bacon, the shell may be pivoted back into normal position covering the remaining bacon, and the package can be returned to refrigeration. The stiffness of the paperboard 34 permits the package to be handled without difficulty after the vacuum seal has been broken.

Preferably the film 20 is opaque, or at least translucent, so as to minimize the transmission of light through the border regions of the display window 14, i.e., through the areas where the film ears 30 engage the surface of the shell 10. Such opaque border tends to assure that the customer can give full attention to the displayed articles without distraction, and thus can more readily make a desired selection. To this same end, the film 20 can also be colored to provide a suitable contrast with the coloring of the displayed articles, thereby to accentuate the appearance of certain aspects of the articles.

Alhough a preferred embodiment of the invention has been described in considerable detail hereinabove, it is desired to make clear that this is to illustrate and not to limit the invention, it being understood that the invention may be embodied in various package configurations and packaging techniques. For example, the semirigid shell need not be of the particular shape disclosed. Also, 21- though the film in the disclosed embodiment is differentiall stretched in regions at opposite sides of the package, it will be understood that other arrangements may be used, depending on the basic configuration of the package which in turn will depend on the shape of the packaged articles. Thus many modifications and different embodiments will be apparent to those skilled in the art. Accordingly, the invention should not be considered limited except as required by the prior art.

We claim:

1. A composite evacuated package comprising a relatively thick semirigid cup-like shell member of oxygenimpermeable material and having a central portion and side wall portions defining boundaries of a planar opening into said shell member, said shell member further including flanges around said opening and coplanar therewith, at least part of said central portion being parallel to said opening and defining the region of maximum depth of the shell member; a product in said package, said product having a plan configuration which is similar geometrically to the plan configuration of said shell member but slightly smaller in lateral dimensions than said opening so as to provide a relatively close fit; a closure member of stretchable and oxygen-impermeable 4 plastic sheet extending across said opening and heatsealed to' said shell member flanges, said closure member having a central face which is at least approximately planar and generally parallel to said opening, said central face being forced down into said shell member against the upper surfaces of the packaged product by atmospheric pressure so as to press said product against said central shell portion, said closure member further being formed with elongate elements stretched down into said shell between said side wall portions and the closely adjacent side edges of the packaged product at least substantially down to said maximum depth part of said central portion, said elements being forced by atmospheric pressure inwardly against the side edges of said product and outwardly against said side wall portions of said shell member.

2. A package as claimed in claim 1, wherein said central portion is made of transparent plastic to define a display window for the packaged article, said closure member being formed of opaque film adapted to present a contrasting margin adjacent the displayed article.

3. A package as claimed in claim 1, wherein said shell member has a generally rectangular outline, said closure sheet being sealed to said flanges, said elongated elements being stretched down into said shell member along two opposite side wall portions thereof to provide a selfregulating package enclosure which automatically adjusts to the dimension of the packaged product between said two side wall portions.

4. A package as claimed in claim 1, wherein said central face of said closure member is within said shell member interiorly of the plane of said opening.

5. A composite evacuated package comprising a relatively thick semirigid cup-like shell member of oxygenimpermeable material and having a central portion and side Wall portions defining boundaries of a planar opening into said shell member; a product in said package having its upper surfaces located below the plane of said opening; a closure member of stretchable oxygen-impermeable plastic sheet material extending across said opening and sealed to the periphery of said shell member, said closure member having a central face generally parallel to said opening but offset therefrom down in said shell member and forced inwardly against the upper surfaces of the packaged article by atmospheric pressure; and a relatively stiff planar panel board sealed to said shell at the periphery thereof and in the plane of said opening, out-board of said closure member central face; said panel board having reduced-thickness regions along a line near one edge of said shell member opening to permit said shell member to be swung back away from the packaged product, along the hinge axis defined by said line, after the seal has been broken around the remaining portions of said shell opening.

6. A package as claimed in claim 5, wherein said shell is formed with flanges around said opening, and coplanar therewith, said closure member being sealed to said flanges and said panel board being sealed to said closure member in the flange seal area.

7. A composite evacuated package comprising a rela-- tively thick semirigid cup-like shell member of oxygenimpermeable material and having a central portion and side wall portions defining boundaries of a planar opening into said shell member; a product in said package having its upper surfaces located below the plane of said opening; a closure member of stretchable oxygen-impermeable plastic sheet material extending across said opening and sealed to the periphery of said shell member, said closure member having a central face generally parallel to said opening but offset therefrom down in said shell member and forced inwardly against the upper surfaces of the packaged article by atmospheric pressure; and a relatively stiff planar panel board sealed to said shell at the periphery thereof and in the plane of said opening, out-board of said closure member central face; said panel board being formed with elongate apertures extending part way along said side wall portions closely adjacent thereto to permit the panel section intermediate said apertures to be flexed inwardly towards said central face by bending the nonapertured portions of said panel board adjacent said side wall portions, thereby to provide for effective nesting of stacked packages.

8. A package as claimed in claim 7, wherein said shell member is of a generally rectangular configuration, said elongate apertures comprising slit-like openings parallel to two opposite side walls of the shell member, the panel board being bendable inwardly along the non-apertured portions adjacent the remaining two side walls.

9. The method of vacuum packaging comprising the steps of: placing a product to be packaged in a semirigid cup, the product having a plan con-figuration which is geometrically similar to the plan outline of the cup, but slightly smaller in lateral dimensions so as to present a small gap between sides of the product and corresponding side walls of the cup; preforming a plastic film to provide for said cup a planar cover top sized to overlap the periphery of the cup, the preforming of said cover top including stretching localized marginal portions thereof immediately adjacent at least two opposite edges to provide ear-like elements extending generally perpendicularly away from the plane of the cover top a distance substantially equal to the depth of the cup; sealing saidfcover to the periphery of the cup toform a hermetically sealed and evacuated package and with said ear-like elements disposed opposite corresponding gaps between the product and the side walls of the cup; and forcing said elements into said gaps by atmospheric pressure such that the film of said elements presses both inwardly againt the product and outwardly against the cup side walls. L,

10. The method of: claim 9, wherein said ear-like elements are pre-stretched a distance greater than the depth of the cup. i

11. The method of claim 9, wherein the cup has a generally rectangular plan outline.

12. The method of claim--11, wherein the film is prestretched in two areas at opposite ends of the rectangular cup.

13. The method of claim 9, wherein said cup is formed of transparent material and saidfilm is non-transparent, to provide a visual contrast at the margins of the cup.

14. A composite evacuated package 'comprising a semirigid cup-like shell member formed er, relatively thick oxygen-impermeable material and having a central base portion with side wall portions extending transversely away from the central base portion, the'remote ends of said side wall portions defining the boundaries 'of a planar opening into said shell member, said shell member further including integral flanges extending outwardly away from said side Wall portions and lying in a common plane parallel to said planar opening, at least part of saidbase portion being parallel to said opening and defining the region of maximum depth of the shell member; a product in said package, said product having a plan outline which is at least approximately similar geometrically to the plan configuration of said shell member opening but slightly smaller in lateral dimensions so as to provide a relatively close fit presenting a small gap between at least part of said side wall portions and the adjacent side edges of the packaged product; a closure member of stretchable and oxygen-impermeable plastic sheet extending across said shell member opening, said closure member having peripheral portions sealed to said shell member flanges completely around said opening to hermetically seal the package interior from outside atmosphere, said interior being evacuated to a reduced pressure level, said closure member further having an interior central face the effective plane of which is parallel to said opening, said central face being forced by atmospheric pressure against the upper surfaces of the packaged product so as to press said product against said central base portion of said shell member, said closure member being formed between its central face and peripheral portions with stretched elongate elements extending down a substantial distance into said gap between said part of said side Wall portions and the adjacent side edges of the packaged product, the interior ends of said elongate elements reaching at least substantially to said maximum depth part of said central base portion, said elements being forced by atmospheric pressure inwardly against said side edges of said product, at least substantially along the entire extent of the side edge dimension thereof, and outwardly against said side wall portions of said shell member.

15. A package as claimed in claim 14, wherein said stretched elongate elements extend into said shell member a distance equal to the depth of the cup-like container, so as to engage the entire side edge region of the product.

16. A package as claimed in claim 14, wherein said closure member is formed of non-transparent material.

17. A package as claimed in claim 16, wherein said shell member is formed of relatively transparent material so that said elongate elements of said closure member present a visual contrast when viewed through the central base portion serving as a product display face.

18. A package as claimed in claim 17, wherein said elongate elements extend down in said shell member a distance sufficient to engage and press against said central base portion.

19. A package as claimed in claim 14, wherein said shell member has a generally rectangular plan configuration and comprises four side walls extending away from central 'base portion.

20. A package as claimed in claim 19, wherein two opposite side walls of said shell member extend away from said central base portion at approximately right angles with respect thereto, said elongate elements extending down into gaps between said two side walls and the adjacent side edges of the packaged product.

References Cited UNITED STATES PATENTS 2,290,095 7/1942 Crandall 206-4534 2,335,914 12/ 1943 Buttery.

2,796,979 6/ 1957 Buttery.

3,153,505 10/1964 Bessett.

3,246,745 4/ 1966 Stoker 206-65 3,349,985 10/ 1967 Salway.

3,371,848 3/1968 Ward et al.

v WILLIAM T. DIXSON, JR., Primary Examiner US. Cl. X.R.

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