US3522879A

US3522879A - Sealed vacuum package and article

Info

Publication number: US3522879A
Application number: US695827A
Authority: US
Inventors: William E Young
Original assignee: Individual
Current assignee: Viskase Corp
Priority date: 1967-12-22
Filing date: 1967-12-22
Publication date: 1970-08-04
Anticipated expiration: 1987-08-04

Description

Aug. 4, 1970 I w. E. YOUNG 3,522,879

SEALED VACUUM PACKAGE AND ARTICLE Original Filed Nov. 18, 1964 2 Sheets-Sheet 1 K E X 07 WT W65?"m7" 'J! a J% [M|1HH "QM U s I NVENTOR. ML UAW f. yam/6 ATTORNEYS W. E. YOUNG SEALED VACUUM PACKAGE AND ARTICLE Aug. 4, 1970 2 Sheets-Sheet 2 Filed Dec. 22. 1967 All it. i

I N\ EN TOR. MAL/AM E. Vow/G United States Patent 3,522,879 SEALED VACUUM PACKAGE AND ARTICLE William E. Young, 52 Sea Beach Drive, Stamford, Conn. 06902 Continuation-impart of application Ser. No. 662,838,

June 29, 1967, which is a continuation of application Ser. No. 412,063, Nov. 18, 1964. This application Dec. 22, 1967, Ser. No. 695,827

Int. Cl. B65d 73/00 U.S. Cl. 206-78 28 Claims ABSTRACT OF THE DISCLOSURE The package blank is formed as shown with a peripheral support to hold a thin flimsy piece of film smoothly and evenly in the sealing area adjacent its periphery despite the rush of evacuated air past all the side edges of the film and is constructed with a barrier film which is stretch-formable so as to conveniently form a pocket portion for containing foodstuffs as in the final package.

This application is a continuation-in-part of copending application, Ser. No. 662,838, filed June 29, 1967, now abandoned which is a continuation of copending application, Ser. No. 412,063, filed November 18, 1964, now abandoned.

This invention relates to a package blank especially suited to be used in practicing the method disclosed and claimed in copending patent application, Ser. No. 650,- 038, filed June 29, 1967, now abandoned. and to a novel vacuum package using the blank of the invention for enclosing and protecting foodstuffs in a sealed container. The package blank is used in and as a part of the method of producing a vacuum package by forming a seal around the periphery of top and bottom package portions through the steps of affixing top and bottom barrier film portions to rigid supports and thereafter using said rigid supports to hold the barrier film in position during forming of a film portion, during evacuation of the package area, during the subsequent closing of the package and while a seal is effected between the films, and the invention ineludes the provision of a package portion that makes possible an optimal practice of the method, and which can itself be easily and economically manufactured.

Vacuum packaging of cheese, processed meats and other items is a generally well-developed art. According to one general practice, the vacuum packages are formed of a top and a bottom piece, each of which includes or comprises a plastic film barrier. One of these pieces is typically preformed into a cup to receive the foodstuff or simply draped over and then tucked around the foodstuff. The outer circumference and perimeter areas of these top and bottom pieces are then placed opposite to one another and the air evacuated from between them. The circumference areas are then pressed together and a seal formed. One problem has been to position and maintain the circumference area of one thin film in a flat, aligned and wrinkle-free condition next to the other film or support during the period in which sealing is effected.

The difficulty of holding the film wrinkle-free during forming of a film and during the evacuation of air within the package to an absolute pressure of 525 mm. Hg can be appreciated when it is realized that the sheets of film are only about .0O2-.003 inch thick. The present solution of this problem is to provide packaging equipment which has means for positioning the barrier film without wrinkling and then holding it in this position during forming, evacuation and during the subsequent closing of the package halves and sealing. In practice, these means are complicated and expensive.

Moreover, the present vacuum packaging means are 3,522,879 Patented Aug. 4, 1970 not completely reliable in achieving a tight seal around the entire circumference of the yacuum package. It is of the utmost importance to form a perfect seal since even a minute opening will allow air to leak in and cause the packaged foodstuffs to deteriorate. This presents a health hazard since there is a risk that this deterioration will be undetected in the home before the foodstuffs are consumed. Even in those cases for which the deterioration is detected, there is an unfavorable consumer relation which makes it important to the manufacturer to insure that a perfect seal is obtained every time.

In brief summary and according to one example of the present invention, a bottom package portion is made of paperboard covered with a barrier material that may be adhered either as a coating or as a film lamina. In view of the present disclosure it will be apparent to men skilled in the art that any rigid support material, such as, for an example, a self-supporting plastic, may be used as the equivalent of paperboard, either covered with or comprising a barrier material.

A top package portion includes a paperboard having an opening in its central portion. Another support material may be substituted. A barrier film is placed over the opening and adhered to the paperboard circumference area around the opening. The barrier film is applied in a flat sheet as from a roll to the flat paperboard, and a smooth flat circumference area of the film is thus achieved and maintained by the paperboard support. The barrier film may be thermally stretch-formed through the central opening of the paperboard to form a cup portion to eventually receive the foodstuff to be packaged. The paperboard adhered to the circumference of the film will maintain the barrier film in a smooth, unwrinkled condition during this forming and afterwards while the film is being transported, positioned and held for sealing against the circumference area of the bottom barrier material.

The package blank and package of the invention allows a simple and reliable method for vacuum packaging to be utilized in packaging of foodstuffs. For example, the method is capable of being practiced by relatively simple vacuum packaging equipment which does not have to provide any means for positioning and holding a flimsy piece of barrier film in a flat and unwrinkled position around its circumference area while at the same time evacuating the air from within the film and past this circumference area.

By means of the invention, it is feasible to evacuate air from the package past all four sides simultaneously and to then seal the four sides simultaneously. The desirability of this simultaneous four-sided evacuation and sealing has been suggested in the past but the difiiculties of maintaining the film in an aligned and unwrinkled condition have heretofore made it practically impossible to achieve these advantages in actual commercial operation.

Further objects will be apparent from the following detailed description and drawings in which:

FIG. 1 is a front elevation of a bottom package portion;

FIG. 2 is a plan view of a top package portion;

FIG. 3 is a front sectional elevational taken generally along line 3-3 in FIG. 2;

FIG. 4 is a front sectional elevation of a top package portion after it has been preformed;

FIG. 5 is a plan view of an alternative top package portion;

FIG. 6 is a plan view of the alternative top package portion shown in FIG. 5 after it has been preformed;

FIG. 7 is an end sectional elevation of the alternative top package portion after it has been preformed;

FIG. 8 is a schematic drawing of method steps for constructing a package according to the invention and as they may be practiced by a machine.

The invention may be practiced in the following manner. For convenience of reference, the two package portions will be arbitrarily referred to as top and bottom package portions.

A bottom piece for the package is prepared with a relatively stiff board layer 1 dimensioned to the approximate size of the finished package. This rigid board may be made of paperboard or any other non-toxic and suitable material may serve as an equivalent. The board is rigid as compared to a plastic barrier film, but it should be understood that it may be flexible as compared, for example, to heavy cardboard.

A barrier film 2 is adhered to the paperboard over one surface thereof. This barrier film which by definition in this context is substantially impermeable to the passage of air or oxygen may be laminated or coated on the board and it may be made of a material such as vinylidene chloride, aluminum foil, or other material such as nylon having sufficient barrier properties to serve in preserving the particular foodstuff or other material to be packaged. If the barrier material film is laminated to the board rather than applied as a coating, it may be affixed to the paperboard with a solvent or other type of liquid adhesive. A sealant or adhesive material 3 is applied over the barrier element 2 by any convenient method. This sealant material is required only about the outer circumference area of the bottom barrier film but for convenience the entire bottom area may be covered with a laminated or coated layer of sealant material such as polyethylene. It should be understood that if a barrier film is used which itself has, or includes a lamination which has, sealant properties, it is unnecessary to apply a separate sealant layer.

A blank 5 for the top piece of the vacuum package is prepared with a rigid board 6 having an outer circumference portion with a central opening 7. This board may be made of the same material as that used for the bottom package portion or it may be made of a different and, for example, a lighter or heavier piece of material. This top board may also be dimensioned to the approximate size of the finished package. A barrier film 9, that is, a film which is substantially impermeable to the passage of air or oxygen by definition as understood in the food packaging art, is juxtaposed and passed over the opening 7 and adhered to this paperboard support. The barrier film may be adhered or glued to the paperboard only in the circumference area adjacent to its outer periphery 8 which is to form the seal and need not be adhered to the board immediately adjacent to the opening 7. This barrier film 9 may be constructed of a substance of nylon, polyester or other formable material. If the foodstuffs to be packaged require a better barrier to preserve the foodstuffs against spoiling by oxygen, the film 9 may include a coating or lamina of a material such as Saran which may be on the side of the film away from the board. The film 9 may optionally carry a sealant coating of a material such as polyethylene. The barrier film 9 need not extend to the outer perimeter of the paperboard 6 but may be set back from that edge for economy in the use of the film material. The barrier film material 9 may also be used as the film for the bottom package portion but it may be preferable to use a cheaper barrier coating since the bottom board may serve as a substrate.

It has been found that the barrier film portion of the package blank prepared as described may be preformed with conventional vacuum and heat forming equipment so that the barrier film 9 forms a cup portion 10 that extends through the paperboard support opposite to the side to which the film is adhered, as shown in FIG. 4. It is to be understood that a preformed piece may also be used for the bottom package portion.

According to another embodiment of the invention, the paperboard 6 for the blank to be used in making the package top piece may be formed as shown in FIG. 5 with a side flap portion 10 and end flap portions 11. Alternatively, flap portions may be used on all four sides.

The

flaps

10 and 11 provide additional stiffening and support for the paperboard piece 6 during its handling and they make possible a serviceably rigid construction of that piece with a smaller outer circumference edge portion than would otherwise be feasible with lightweight paperboard. This, in turn, achieves a more compact package. The flaps are set at an angle to the circumference edge when the barrier film is formed into a cup which is open and accessible and then function adjacent the cup portion to help support it.

It is a further development and part of this invention to provide a rounded bearing surface along the edges of the opening of the top support member portion on the side toward the barrier film. This rounded surface can be provided by various manufacturing techniques, but according to a preferred teaching of this invention, the rounded edge is formed not only on the edge but also for a short distance on opposite sides of the edge by bending of a flap which extends into the opening and which is integral with the top support member upwardly. When this flap is formed of paperboard or equivalent material, the flexing takes place in the area of the juncture and also extends slightly past the juncture in each direction so that the radius of curvature of the bearing surface is actually larger than the radius of curvature which could be provided within the thickness of the paperboard support without the use of flaps. Moreover, the radius of curvature is flared slightly at each end. Preferably, this curved bearing surface is provided along each edge so that it will protect the barrier film from being torn during handling or flexing of the finished package or product. It is particularly important that the curved bearing surface be provided along each edge past which the barrier film is formed as the forming of the barrier film past such edges is particularly critical. According to one embodiment, the rounded bearing surface is provided about the entire sides of the opening on all the edge surfaces and the pocket in the barrier film is formed by pulling the barrier film material uniformly past and by these edges. Alternatively, it is possible to form the pocket by flexing the barrier film most against such edges as are provided with a rounded bearing surface, and leaving the less critical areas of the edge exposed.

In other words, it is to be understood that as the flaps are bent during formation of the cup, they provide a rounded edge about which the barrier film can be formed. The flap material at the junction of the flaps and the remainder of the board assumes a rounded shape in contrast to the sharp and often jagged edge left by conventional forming of openings, as by die-cutting. The rounded edges do not impede the formation of the barrier film into the cup as might a sharp edge nor is there tearing of the barrier film at the edge during forming. It should be understood that in heat forming, this critical edge portion-when the film is adjacent the paperboard supportis most diflicult to heat to the ideal temperature due to stretching of the film or in subsequent flexing as may be incurred during handling.

In order to facilitate the bending of the flaps during formation of the barrier film into a cup, and in order to satisfactorily bend small flaps, the flaps can be precreased along the line about which the flaps are bent.

Preferably, the barrier film that forms the cup portion next to the

angled flaps

10 and 11 is adhered to the flaps for added strength and support. It is most convenient if this can be done before forming, when the

flaps

10 and 11 are flat and the film 9 is adhered to the circumference edge portion of the similarly flat package piece 6. This method, however, encounters the problem that at least some portion of the film, particularly in the vicinity of the ends of the flaps, must move relative to the rigid flaps during the forming of the cup. It is possible to adhere the film to the flaps only in an area set back from their ends, but this requires control and alignment of the area in which the adhesive is applied and it achieves only partial support of the cup portion in the finished package. For a preferable procedure, it has been found that the adhesive may be applied over the entire surface of the piece 6 without alignment if a heat sensitive vinyl emulsion type glue is used. This glue allows a satisfactory creep between flap and film as the cup portion is formed and thereafter provides good support between them. Also, a glue or adhesive which is pressure sensitive can be usedi.e. a glue which will hold and support the film on the flap against these pressures encountered in handling but which, under the extraordinary pressure in forming, will let go and allow relative movement between film and flap. Further, any other glue or adhesive of a type which is relatively low in shear so as to permit relative sliding between flap and film can also be used.

It has been found possible to use glues or adhesives which do not allow the barrier film and flap to move with respect to each other during formation of the cup provided only one flap or two non-adjacent flaps are used. In this practice, it is the film which is not restrained against movement relative to the flap which is stretched to form the cup. Alternatively, in view of this teaching, it will be apparent to men skilled in the art that the flaps can be spaced apart from each other at their adjacent edges so that there is a gap between them which permits free deformation and stretching of the film during the forming of the pockets.

It is a further teaching of the invention to provide a burstable blank which is formed as described and of a paperboard piece 6 with flaps except that the joints 12 between the side and end flaps 10 and 11, respectively, are not cut entirely through but instead are partially cut or weakened to leave, for example, one or more narrow bridges of paperboard across the joints to connect the ends of the flaps together. Such a construction will provide greater and more rigid support to the blank during its handling and up to the time that the cup portion is preformed on the molding equipment. At this time, and under the pressure of the vacuum or other forming, it has been found that the ends will burst apart allowing the cup to be formed as though they had been separated from the beginning. As before, the barrier film may be adhered to the

flaps

10, 11 an adequate distance back from the divisions 12 so that a free and unsupported portion of the film will be available for stretching between the flap ends when they separate as the cup portion is formed. Alternatively and according to a further teaching of the invention, a heat sensitive vinyl emulsion type glue may be used as described above.

One method for making packages, if the top and bottom package portions have been prepared as separate fiat sheets according to one embodiment of the present invention, is shown schematically in FIG. 8. An advantage of carrying out this method with the bottom package portion being on the bottom and transported horizontally is that the food product can be maintained in position on this portion by gravity. By this method, a bottom package portion 4 is delivered to a loading area from storage means as shown at 15. The foodstuffs to be packaged and, for example, shingled bacon 16 is then placed on the central portion of this bottom piece as shown at 19.

A blank 5 for the top portion is supplied from a storage means or a magazine as shown at 17. The paperboard support member is used to position the film that passes under the opening 7 under a vacuum and stretch forming mold at 18 which forms cup portion 10 of film 9 upwardly through the paperboard opening. For the further invention, the molding heat softens a vinyl emulsion type glue to permit relative movement between the film and flaps during the forming process and molding pressure bursts paperboard flaps apart and sets them at an angle to the edge portion of the package piece to form and provide support for a portion of the cup. This preformed top piece is then placed over the foodstuff and onto the bottom piece as shown at 26. The words top and bottom are used illustratively; the top foodstuff and the bottom package portion could be supplied on top.

Both package portions are then placed in a chamber at 21, the paperboard support being used to align and position the top and bottom barrier films opposite to one another. A tack seal may be made to hold the supports and film in aligned position for subsequent handling and during evacuation for final sealing. These seals should be made in as small an area as will serve this purpose so as to leave the substantial circumference of the package open for evacuation. The seals may, for example, be in two spot locations located in the middle of two opposite sides of the package, the seal being made, for example by pressing a spot heater bar against the paperboard support carrying the film barrier with sealant. A tack seal allows the relative alignment of the top and bottom blanks to be subsequently maintained, for example, while the aligned blanks are handled prior to the peripheral sealing into a package. The chamber is evacuated and air is simultaneously drawn out from between the top and bottom package portions past each of the four sides to give an absolute pressure of between 525 mm. Hg within the chamber and package for most food products. After evacuation, an inert or preservative gas may be introduced into the package. It should be understood that this introduction of gas does not alter the basic method of packaging and reference to vacuum evacuation is intended to refer to and include not only vacuum evacuating but also vacuum evacuating and then gas-filling. The paperboard supports are then relied upon to hold the circumference areas of the barrier films smooth and flat while a seal is simultaneously made at the four sides within the vacuum chamber as by pressing a heater means against the paperboard support carrying the film barrier with sealant. The chamber is then opened and the completed package is delivered as at 22.

While one method of making the package of the invention has been described above, it is noted that other methods can also be used to make the package. For example, where the top and bottom package blanks are prepared as above with a barrier film of a material which is stretch-formable without the application of heat, the use of heat forming equipment can be avoided in forming the package.

The invention has been described above for the production of top and bottom package portions of individual sheets of material. It is to be understood that in commercial practice, long sheets or rolls of paperboard and film may be laminated together to provide the package portions, each having a smoothly and evenly supported circumference area of barrier film material that will form the peripheral and circumferential seal areas in the finished package. After preparation, the long sheets and rolls are cut into lengths as is necessary so that one package portion may be positioned over the next package portion in manufacture of the separate packages.

The invention is further pointed out in the following claims.

What is claimed is:

1. A half package part of blank construction for use in making a gas-tight package comprising a substantially flat support member having a circumferential edge area, an opening within said edge area and a flat stretch-formable barrier film adhered over said opening and completely around said circumferential edge area whereby the periphery of said barrier film is maintained in a smooth unwrinkled condition during formation of a gas-tight package said barrier film being substantially impermeable to the passage of air and oxygen, and at least one flap integrally secured on said support member, said flap extending inwardly of said edge area into the aperture in overlying relation to said barrier film to stiffen the package blank during handling.

2. A blank as set forth in claim 1 in which said flap is adhered to said barrier film.

3. A blank as set forth in claim 2 wherein a creepable glue adheres said flap to said barrier film.

4. A blank as set forth in claim 1 wherein said barrier film has a cup-shaped pocket portion extending through the aperture of said support member past the opposite surface thereof whereby said pocket portion is adapted to cover a foodstuff to be packaged.

5. A blank as set forth in claim 4 wherein said fiap extends inwardly of and at an angle to said edge area into the aperture in supporting relation with a portion of said pocket portion of said barrier film.

6. A blank as set forth in claim 5 wherein said barrier film is thermally stretch-formable and which further comprises a heat softenable glue between said flap and barrier film for permitting relative movement between said barrier film and flap during formation of said pocket portion of said barrier film.

7. A blank as set forth in claim 5 wherein said cup portion is open and accessible for insertion of foodstuffs thereinto.

8. A blank as set forth in claim -1 wherein said support member has at least two flaps thereon projecting into said opening, each said flap being attached along a side edge of said edge area adjacent said opening and being affixed to an adjacent flap at at least one end thereof in a perforated-like burstable construction whereby a cup portion may be formed by bursting said flap ends apart, and bending said flaps at an angle and, stretching said barrier film.

9. A blank as set forth in claim 1 wherein said flap is precreased along said edge area.

10. A package blank construction including a barrier film for use in the manufacture of a package having a circumferential seal formed between the barrier film and another package part that comprises a support member; said support member having a circumferential edge area and an opening within said edge area; at least two flaps attached to the circumferential edge area of said support member and extending into the opening, said flaps being adjoined by being attached to one another at their ends by a weak burstable construction; a barrier film of stretch-formable material adhered over said support member and flaps and over the opening within said edge area, a layer of glue between said flaps and said barrier film characterized in that it will permit relative movement therebetween in vacuum forming procedures, so as to provide a package blank construction having a rigidity for handling that is contributed to by adjoining flaps which may be used to provide a cup portion formed through said opening under vacuum forming procedures by bursting said flap ends apart and stretching and moving said barrier film relative to the flap and into the cup portion shape that remains supported and adhered to said flap after said forming.

11. A package blank construction for use in forming one half of a gas-tight package that comprises a substantially flat board support member, said support member having a circumferential edge area, an opening located within said edge area and at least one flap attached along one inner side edge of said circumferential edge area and extending into the opening, a stretch-formable barrier film positioned over said edge portion, said flap and the opening, said barrier film being afiixed to said support member completely around said circumferential edge portion, a layer of glue between said flap and a portion of said barrier film, said glue holding the flap and film adjacent to one another, whereby the package blank which is a bonded together unit for handling is adapted to be formed into a pocket shaped package part having said flap formed at an angle to said circumferential edge portion of said film formed into an enclosing pocket a portion of which lies adjacent to said flap and is supported by the flap.

12. A package blank construction as set forth in claim 11 wherein said glue is of a type having a low resistance to shear so as to permit relative sliding movement between said film and said flap.

13. A package blank construction as set forth in claim 11 wherein said glue is a heat sensitive glue which is softenable under heat of conventional vacuum forming procedures to allow the relative movement between said film and said flap during forming of the pocket shaped package part.

14. A package blank construction as set forth in calim 11 having a flap secured to each of the inner edges of said circumferential edge area.

15. A package blank as set forth in claim 14 wherein each said fiap is spaced from an adjacent flap by a gap.

16. A gas-tight package for food comprising a substantially flat bottom portion, a barrier coating adhered to said bottom portion, a top support having an opening therein, a stretch-formed barrier film substantially impermeable to the passage of oxygen adhered to the top support and extending upwardly through said opening to form a pocket portion to receive the food, said barrier film and said barrier coating being sealed together around the package circumference to form a gas-tight package, and at least one flap on said top support extending at an angle inwardly of said opening, said flap being in protective relation with said pocket portion of said barrier film.

17. A gas-tight package as set forth in claim 16, with a flap on each inside edge of the opening and at least one of said flaps forming a rounded corner with said top support at the juncture of said flap with said top support so that the film forming the pocket portion is protected from sharp edges.

18. A gas-tight package as set forth in claim 16 wherein a glue is adhered between and to said flap and barrier film to permit a relative movement therebetween during forming of said pocket portion.

-19. A gas-tight package as set forth in claim 18 wherein said glue is a heat sensitive vinyl emulsion type glue.

20. A gas-tight package as set forth in claim 16 further comprising an inert gas within said pocket portion.

21. A gas-tight package as set forth in claim 16 whereing a vacuum exists in said pocket portion.

22. A gas-tight package as set forth in claim 16 further comprising a sealant coating on the peripheral area of said barrier film about said opening for forming a circumferential seal about the package periphery.

23. A gas-tight package as set forth in claim 16 wherein said barrier film is a vinylidene chloride polymer.

24. A gas-tight package as set forth in claim 16 wherein said flap is precreased along a line about which said fiap extends from said top support.

25. A gas-tight package for food comprising a bottom package portion and a top package portion in sealed relation to each other about the peripheries thereof; at least said top package portion having an opening therein, a thin flexible stretch-formed barrier film substantially impermeable to the passage of oxygen adhered to said support and extending upwardly through said opening to form a pocket portion receiving the food, and a rounded edge bearing surface on at least one edge of said top package portion about said opening in supporting relation with said barrier film to protect said barrier film.

26. A gas-tight package as set forth in claim 25 further comprising at least one flap secured to at least one edge of said top package portion, said rounded edge bearing surface being formed at the juncture of said flap with said top package portion, said flap extending along said pocket portion in supporting relation therewith.

27. A gas-tight package as set forth in claim 26 further comprising a glue between said flap and said pocket portion, securing said flap to said pocket portion, said glue extending at least partially over the surface of said flap facing said pocket portion.

28. A gas-tight package as set forth in claim 26 wherein said bottom package portion comprises a self-support- 9 10 ing board and a barrier coating across the surface of said 3,036,705 5/ 1962 Haecker 206-78 board facing said top package portion. 3,075,329 1/ 1963 Swezey et a1.

References Cited 3,154,215 10/1964 Vesconte 206-46 X 3,173,540 3/1965 Lapides 20678 UNITED STATES PATENTS 5 3,183,100 5/1965 Bonini 99174 X 2,621,129 12/1952 Ramsbottom et a1. 2,623,826 12/ 1952 Grinstead 99-174 DONALD F. NORTON, Primary Examiner 2,945,586 7/1960 Mackes 206-78