US3388827A - Sealed reclosable food package - Google Patents

Description

June 18, 1968 A. s. THANHAUSER ETAL 3,388,827

SEALED RECLOSABLE FOOD PACKAGE Filed March 50, 1967 2 Sheets-Sheet 1 INVENTORS A. S. THANHAUSER H. R. WE/SJ A 77'0RNEY June 1958 A. s THANHAUSER ETAL. 3388,27

SEALED RBCLOSABLE FOOD PACKAGE Filed March 30, 1967 2 Sheets=$heet Mil/6N5 A. s. THANHAUSER H- R. was: V

United States Patent 0 3,388,827 SEALED RECLOSABLE FOOD PACKAGE Albert S. Thanhauser, Stamford, Conn., and Hugh R.

Weiss, Montclair, N.J., assignors to The Pantasote Company of New York, Inc., New York, N.Y., a corporation of New York Filed Mar. 30, 1967, Ser. No. 627,624 20 Claims. (Cl. 220-60) ABSTRACT OF THE DISCLGSURE Molded plastic, reclosable container for margarine, etc., the walls of which have a lateral offset with an upright rim, which forms a peri heral groove at their top portions, and a semi-rigid snap-in-cover having a marginal flange with an upstanding portion which fits into said groove and has a portion resting on said offset. Both the container and the cover have outwardly extending flanges at their extreme outer edges, the flange of the container being wider than that of the cover and having a depressed portion to receive the narrower flange of the cover. A narrow, peelable sealing strip is adhered to the upper surfaces of said outstanding flanges to prevent air leakage.

This invention relates to a sealed plastic container for margarine, gelatin and other foods, and more particularly to a container molded from thin sheets of thermoplastic material which may be sealed to permit vacuum packing or gas packing of foods and which may readily be opened and rescaled.

Prior to this invention, various types of margarine containers have been made with lids intended to seal the contents of the container. These food containers have not been satisfactory for vacuum packing, for example, and the seals have not been reliable, particularly when the containers were stacked. Also, it has been a problem to mass produce margarine containers with effective seals because of the variation in the thickness of the plastic sheets being molded and the difiiculty of maintaining close tolerances.

The present invention overcomes the difficulties mentioned above and provides a food container which can be mass-produced at low cost and will provide effective sealing, even where there is substantial variation in the gauge or thickness of the plastic sheet material. The container of this invention is satisfactory for vacuum packing and for extended storage of food and provides an effective seal after the package is opened and reclosed.

The container of this invention comprises a semi-rigid cup or tub having circumscribing walls with a lateral offset and an upright rim portion which defines a pcripheral groove for receiving a snap-in cover. Such cover has a rim flange which fits in said groove and has a narrow outwardly extending portion which fits in a peripheral depression in an outwardly extending flange of the tub, whereby the upper surfaces of the tub and cover flanges are substantially flush. The container may be sealed by placing a narrow sealing strip over the marginal edge of the cover flange and adhering it to the tub flange and the cover flange so that it provides an air-tight seal but may be readily peeled off to permit opening of the container.

The upright rim portion of the tub, which defines the peripheral groove, and the rim flange of the cover, which fits in the groove, are so shaped as to provide a pcripheral air space and to create sealing pressure on opposite sides of such space that effects an air lock and provides a very effective seal throughout the periphery of the tub even where there is substantial variation in the thickness of the plastic sheets used to form the tub and 3,388,827 Patented June 18, 1968 the cover. Also, the central portions of the cover are shaped to assist in maintaining an even sealing pressure around the margin and in preventing distortion which could break the seals.

The cover of the lid and the bottom portion of the tub may be specially shaped to facilitate proper stacking of the containers, to reduce the chances of damage to the container, and to facilitate lifting of the cover.

In a modified form of the invention the upper parts of the rim flanges of the tub and the cover are specially shaped to obtain an effective seal without a separate sealmg strip (see FIGURES 8 to 14). This makes possible additional air locks and provides more effective sealing after the container is opened and reclose-d. When massproduced, the modified form also provides effective sealmg in spite of substantial variation in the thickness of the plastic sheets.

An object of the present invention is to provide a simple, inexpensive food container which is sufiiciently reliable for vacuum packing of food and which may be readily reclosed by the housewife to reseal the container and prevent spoilage.

Another object of the present invention is to provide a sealed food container which can be mass-produced from plastic sheets whose thickness varies considerably.

Another object of the invention is to provide a more 1etgective means for sealing margarine containers and the These and other objects, uses and advantages of the invention will become apparent to those skilled in the art from the following description and claims and from the drawings in which:

FIGURE 1 is a top plan view on a reduced scale shOW- ing an open-top margarine tub constructed according to the present invention with the cover removed;

FIGURE 2 is a side elevational view of the tub of FIG- URE 1 on the same scale;

FIGURE 3 is an end elevational view of the tub;

FIGURE 4 is a fragmentary vertical sectional view taken on the line 4-4 of FIGURE 1 but showing the tub on a larger scale with the cover in place and sealed at the margin;

FIGURE 5 is a fragmentary vertical sectional view taken on the line 55 of FIGURE 1 and on the same scale as FIGURE 4 showing the sealed Container with the cover in place;

FIGURE 6 is a vertical sectional view showing the snap-in cover for the tub of FIGURE 1;

FIGURE 7 is a fragmentary vertical sectional view showing the bottom portion of the tub of FIGURE 1;

FIGURE 8 is a top plan view similar to FIGURE 1 showing a modified form of margarine tub constructed according to the present invention with the cover removed;

FIGURE 9 is a side elevational view of the tub of FIGURE 8;

FIGURE 10 is an end elevational view of the tub;

FIGURE 11 is a top plan view of a snap-in cover for the tub of FIGURES 8 to 10;

FIGURE 12 is a fragmentary vertical sectional view of the assembled container taken substantially on the line 1212 of FIGURE 8 and on a larger scale;

FIGURE 13 is a fragmentary longitudinal vertical sectional view taken on the line 13-13 of FIGURE 11; and

FIGURE 14 is a fragmentary lateral sectional view taken on the line of 14-14 of FIGURE 11.

Referring more particularly to the drawings, in which like parts are identified by the same numerals throughout the several views, FIGURES 1 to 3 show a tapered cup or tub I of generally polygonal shape having oppositely disposed upright side walls 4 and 5, each of said walls having an integral lateral offset 6 which extends horizontally and an upright rim portion 7 integrally connected to the offset by a rounded bottom portion 8. The portions 7 are generally fiat and inclined to the vertical so that the portions 6 and 7 define a peripheral groove near the top of the tub for receiving the circumscrioing upright rim flange 9 of the snap-in cover 2.

The continuous rim flange 9 has an upwardly extending portion 10 of generally polygonal horizontal cross sectionwhich fits in said peripheral groove and conforms to the shape of the circumscribing rim portions 7 of the tub so that there is a large area of contact between the portions 7 and 10 to effect sealing. This feature is shown in FIGURES 4 and 5, which are drawn substantially to scale. The rim flange 9 of the cover has a narrow outwardly extending horizontal portion 11 integrally joined to the portion 10 by a rounded edge portion 12 and has a rounded edge portion 13 integrally joining the portion 10 to the horizontal marginal portion 14 of the bottom wall which seats on the lateral offset 6. Said marginal portion 14 is integrally connected to a generally fiat raised central portion 15 of polygonal shape by an upright portion 23 that preferably slopes inwardly as shown in FIG- URE 6.

The tub 1 has a continuous outwardly directed flange portion 16 with its peripheral edge located a short distance outwardly of the peripheral edge of the rim flange 9 and preferably generally parallel to or uniformly spaced from said peripheral edge. Said rim flange has a narrow circumferentially continuous horizontal depressed portion 17 which is preferably offset from the outer marginal portion of the flange 16 a distance corresponding to the thickness of the cover portion 11, whereby the portion 17 supports the cover portion 11 with its upper surface flush with the upper surface of the flange 9 as shown in FIGURE 5, for example.

The narrow depression above the portion 17 extends around the periphery of the tub 1 as shown in FIGURE 1, and a recess may be formed at one corner of the tub by an inclined portion 17a located adjacent a finger tab 18. The cover is provided with a finger tab 19 that extends over such recess and may readily be lifted by inserting a fingernail under the tab after the strip 3 has been peeled off.

The narrow space 20 at the peripheral edge of the portion 11, which extends around the periphery of the container A, may be sealed by covering it with a continuous sealing strip 3 formed of a thin flexible plastic material. Such sealing strip preferably extends throughout the length of the space 20 and throughout the periphery of the container so as to completely close and seal the container. As the container is air tight when using the strip 3, spoiling of the margarine, gelatin or other food in the container may be prevented by use of vacuum packing or gas packing using conventional procedures.

The strip 3 is adhered to the upper surfaces of the container on opposite sides of the groove 20 so as to provide an effective seal throughout the periphery of the container while at the same time permitting the strip 3 to be peeled off when the container is to be opened. This is in the nature of a temporary adhesion rather than a permanent weld. The temperature used to effect the sealing or bonding should be below the melting point of the plastic materials used to form the tub and the cover. The strip 3 may be adhered by using conventional pressure-sensitive adhesives or by using conventional heat sealing methods. It may, for example, be adhered to the flanges 11 and 16 by a continuous layer of a well known heat-activated pressure-sensitive adhesive or a heat sealing paint or varnish. The strip 3 is preferably made of a thermoplastic material, particularly when employing heat sealing, but thermo-setting plastics may also be used.

The strip 3 is preferably relatively thin and may have a thickness which is a small fraction of the thickness of the tub 5, but ordinarily the thickness of the strip 3 is in the neighborhood of .002 to .010 inch. Excellent results may be obtained, for example, using sealing strips with a thickness of .003 to .006 inch.

The tub 1 or 1a and the cover 2 or 2a are preferably vacuum formed or otherwise molded from thin, flat sheets of a plastic material. Such material is preferably a thermoplastic resin such as polvinylchloride, polyethylene, polypropylene or the like and is preferably shaped by vacuum molding after softening the plastic sheet by heat.

The thickness of the plastic sheets used to form the tub I or 1a and the cover 2 or 2a may vary considerably. It is preferable to avoid excessive thickness in order to minimize the cost and also to obtain suflicient flexibility for easy assembly and disassembly. In general, the thickness of the tub and the coveris preferably about 0.010 to 0.030 inch. It is usually preferable to employ thicknesses in the neighborhood of 0.015 to 0.025 inch. In mass production of the container of this invention, the sheets used to form the tub or the cover have thicknesses which may vary one thousandth of an inch or so. The container of this invention is so shaped that a single mold can produce satisfactory tubs or covers in spite of such variations in the thickness of the plastic sheets. It is not necessary to employ selective assembly in order to obtain satisfactory sealing with the container of this invention because of the particular shape of the portions of the tub and cover which fit together to effect proper sealing in spite of such variations.

As shown in FIGURES 4 and 5 of the drawings, the rim flange 9 and the horizontal marginal portion 14 of the cover 2 are wedged in the peripheral groove between the upright rim portion 7 and the lateral offset 6. When the parts are shaped as shown in the drawings, such wedging action maintains an effective sealing pressure between the portions 7 and 10 and also between the portions 6 and 14. This, in connection with the peripheral air space 21, provides a circumscribing air lock which is highly effective in preventing leakage of air into or out of the container.

As indicated in FIGURES 4 and 5, which are drawn substantially to scale, the tub has peripheral portions 8 and 26 at the top and bottom of the upright rim portion 7 providing the upper portion of the tub with an S-shaped vertical cross section which is preferably uniform substantially throughout the periphery of the container. Likewise, the cover 2 has rounded peripheral portions 12 and 13 at the top and bottom of the upwardly extending portion 10 providing the cover with an S-shaped vertical cross section which is preferably uniform substantially throughout the periphery of the cover.

The centers of curvature of the portions 8 and 13 are spaced apart to provide a peripheral air chamber 21 of substantial volume between the cover and the tub adjacent the junction of the offset 6 and the rim portion 6.

A similar peripheral air chamber 25 of substantial volume is provided adjacent the junction of the rim portion 7' and the flange portion 16. This air space is obtained by flattening the vertical upper portion 26 so that it is spaced from the rounded portion 12 of the cover. The circumscribing air space 25 and the similar air space 21 are particularly effective when margarine, grease or other flowable material is present on the engaging surfaces of the tub and the lid. The wedging action of the parts is such as to squeeze the margarine, for example, into the peripheral spaces 21 and 25 and provide a better seal at opposite sides of each of said spaces.

The cover 2 has a flat central raised portion 15 and a flat marginal portion 14 integrally connected to said raised portion by a narrow upright intermediate portion 23 of generally polygonal shape. Said marginal portion 14 preferably has a generally uniform width throughout the periphery of the cover 2 as shown, for example, in FIGURE 1 and said intermediate portion also has a uniform width. This arrangement tends to prevent uneven distortion of the cover and enables the portion of the cover to apply an even sealing pressure even when both the tub and the cover have thicknesses greater than intended. The same is true of the container of FIGURES 8 to 14.

The intermediate portion 23 has a vertical width greater than that of the rim flange 9, whereby the raised portion is located in a plane parallel to and above the upper surface of the portion 11. The tub 1 preferably has a flat central horizontal raised portion 22 parallel to the portion 15 of the cover and adapted to fit over the portion 15 of an underlying identical container A in a stack, whereby the containers A may easily be stacked vertically. In such a stack, the narrow upright portion 24 of the bottom wall at the margin of the portion 22 may engage the intermediate portion 23 of an underlying cover throughout the periphery thereof to hold the underlying container A in place, the portion 22 having substantially the same size and shape as the portion 15. In order to lock the containers together in the stack and to facilitate lifting of the covers with the fingers, it is preferable to shape the cover so that the intermediate portion slopes radially outwardly as shown in FIGURE 6, whereby the external dimensions of the portion 15 are slightly greater than the internal dimensions of the marginal portion 14. If desired, the portion 24 may be similarly sloped.

FIGURES 8 through 14 show a modified form of margarine tray A according to this invention having a tapered tub 1a of generally polygonal shape and a snap-in lid or cover 2a. The tub has upright side walls 4a and 5a, each of said walls having an integral lateral offset 6a which extends horizontally and an upright rim portion 7a integrally connected to the said offset by a rounded bottom portion 8a. The portions 7a are shaped to fit the circumscribing upright rim flange 9a of the snap-in cover 2a. The tub 1a is shaped generally like the tub 1 and has a bottom raised portion 22a similar to the portion 22 of the tub 1.

The cover 2a has a horizontal marginal portion 14a which seats on the later-a1 oflset 6a. Said marginal portion is integrally connected to a generally flat raised central portion 15a by an upright portion 28 having a height less than that of the rim portion 7a. In order to facilitate removal of the cover, a rounded finger-receiving portion 29 is provided on each side of the central portion 15a, said portion 29 sloping inwardly as shown in FIGURE 14 to facilitate gripping of the cover with the thumb and one finger of one hand.

The container A preferably has substantialy the same cross section throughout its periphery as shown, for example, in FIGURE 12, except that the radially outer portions of the tub and cover are preferably shaped to provide finger tabs or the like near one corner of the tray and the cover is preferably provided with a series of dencsting bumps 30 to prevent the covers from sticking tofiether when they are stacked. As shown in FIGURE 11, the bumps 30 are located near the corners of the cover, said bumps having rounded corners 31.

As shown in FIGURES 8 and 11, the margin of the tub 1a has portions 32 and 33 which gradually increase in width toward one corner of the tub and the cover 2a has similar portions 34 and 35 which overlie the portions 32 and 33. Embossing 36 is preferably provided at said corner to facilitate gripping of the corner when the cover is to be removed.

The novel construction of the interfitting tub rim portion 7a and lid rim flange 9a will be apparent from FIG- URE 12 which is drawn substantiarly to scale. The rim 7a comprises in seriatim a botton circumscribing vertical portions 37, an inclined inwardly projecting portion 38, an intermediate vertical portion 39, an outwardy extending portion 40, an upper circumscribing vertical portion 41, a narrow upper horizontal portion 42, an outer vertical portion 43, and a narrow marginal horizontal portion 44, the junctions of said integral portions being rounded. The rim flange 9a has a similar shape and comprises in seriatim a narrow vertical portion 45, an inclined inwardly projecting portion 46, an intermediate vertical portion 47, an outwardly extending portion 48, an upper vertical portion 49, an upper horizontal portion 50, and a downwardly extending circumscribing marginal portion 51.

The outermost portions of the marginal portion 14a and the peripheral portions and 46 of the rim flange 9a are wedged in the peripheral groove of the tub formed between the lateral offset 6a and the peripheral portion 38 and conform substantially to the shape of such groove. The wedging action tends to maintain an effective sealing pressure between the portions 38 and 46 throughout the periphery of the container and also between the portions 6a and 140. This, in connection with the circumscribing air chamber 21a, provides a circumscribing air.

lock. Other circumscribing air chambers 25a, 52 and 53 are also provided. These have substantial volume and may, if desired, be partially filled with margarine, grease or the like to improve the seal.

The rim flange 9a of the cover and the rim portion 7a of the tub may be shaped to provide a sealing pressure between the portions 41 and 49 throughout the periphery of the container. Also, the top portion 50 preferably presses against the underlying portion 42 throughout the periphery to maintain an effective seal. If desired, the portions 42 and 50 may be temporarily adhered throughout the periphery of the container by conventional heat sealing or by a conventional heat-activated adhesive, but this is not essential.

It is to be understood that the above description is by way of illustration rather than limitation and that, in accordance with the provisions of the patent statutes, variations and modifications of the specific containers disclosed. herein may be made without departing from the spirit of the invention.

Having described our invention, we claim:

1. A sealed reclosable container for margarine or other foods comprising a semi-rigid tub molded from a single sheet of plastic having polygonally arranged and oppositely disposed side walls, each of said walls having an integral lateral offset with an integral upright rim portion at the .top portion of the tub which defines a peripheral groove, and a semi-rigid snap-in cover for said tub having a continuous marginal rim flange with an upwardly extending portion of generaly polygonal horizontal cross section which fits in said peripheral groove and conforms substantially to the shape of the rim portions of said tub, said cover having a horizontal marginal portion resting on said offset, said rim flange having a narrow substantially fiat outwardly extending portion forming the periphery of said cover, the periphery of said tub being formed by a continuous outwardly directed flange portion having its circumscribing peripheral edge outwardly of the peripheral edge of said rim flange and having a narrow depression of a size to receive said narrow portion of said rim flange, whereby said flange portion of said tub supports said narrow portion of said rim flange with its upper surface substantially flush with the upper surface of said flange portion outwardly of said depression, a narrow peelable sealing strip, and means for adhering said strip to said last-named upper surfaces substantially throughout the periphery of the cover to prevent air leakage while permitting ready removal of said strip by peeling from said upper surfaces.

2. A sealed reclosable container as defined in claim 1 wherein said rim flange and said horizontal marginal portion of said cover are wedged in said peripheral groove between said upright rim portion and said lateral offset to maintain an effective sealing pressure against said rim portion and said offset.

3. A sealed reclosable container as defined in claim 2 wherein a peripheral air chamber of substantial size is located between said cover and said tub to provide an air lock adjacent the junction of said offset and said rim portion.

4. A sealed reclosable container as defined in claim 3 wherein a peripheral air chamber of substantial size is provided between said cover and said tub adjacent the junction of said rim portion and said outwardly directed flange portion of said tub.

5. A sealed reclosable container as defined in claim 4 wherein said tub has rounded peripheral portions at the top and bottom of said upright rim portion providing the upper portion of the tub with a generally uniform S- shaped vertical cross section and said cover has rounded peripheral portions at the top and bottom of said upwardly extending portion.

6. A sealed reclosable container as defined in claim 1 wherein said upwardly extending portion of said rim flange and said upright rim portion are inclined at substantially the same angle relative to the vertical and are wedged together to provide a seal throughout the periphery of the container.

7. A sealed reclosable container as defined in claim 6 wherein the upper portion of said tub has a generally S- shaped vertical cross section substantially throughout the periphery and said upright rim portion has a truncated generally pyramidoidal outer surface held in tight engagement with a truncated generally pyramidoidal surface of said peripheral groove substantially throughout the periphery of said container.

8. A sealed reclosable container as defined in claim 7 wherein the upper portion of said tub is generally rectangular in horizontal cross section with rounded corners, said outwardly directed flange portion of said tub has a finger tab at one corner of the tub with a recess therein having a depth greater than that of said narrow depression, and said rim flange of said cover has a finger tab above the finger tab of said tub and above said recess, said recess facilitating insertion of a fingernail between said tabs to remove said cover.

9. A reclosable container as defined in claim 1 wherein said cover has a central raised portion (15) and a horizontal marginal portion (14) integrally connected to said raised portion by a narrow upright intermediate portion (23) of generally polygonal shape, said marginal portion (14) seating on said lateral otfset (6) throughout the periphery of the tub.

10. A reclosable container as defined in claim 9 wherein said narrow intermediate portion (23) has a vertical width greater than that of said rim flange (9) and said raised portion (15) is located generally in a plane parallel to and above the upper surface of said narrow outwardly extending portion (11) of said cover.

11. A reclosable container as defined in claim 9 wherein said intermediate portion (23) slopes radially outwardly so that the external dimensions of said raised portion are slightly greater than the internal dimensions of said horizontal marginal portion (14).

12. A reclosable container as defined in claim 9 wherein said tub has a bottom wall with a central horizontal raised portion (22) adapted to fit over the central raised 8 portion (22) for engaging the periphery of the narrow intermediate portion (23) of said identical container.

13. A sealed reclosable container as defined in claim 1 wherein said sealing strip is formed of a thermoplastic material and is heat sealed throughout the periphery of said tub to prevent leakage of air into or out of said tub.

14. A sealed reclosable container as defined in claim 1 wherein said sealing strip is held on said tub by a layer of a pressure-sensitive adhesive.

15. A sealed reclosable container as defined in claim 1 wherein the interior of the container is filled with food and maintained at a subatmospheric pressure.

cover portion (15) of an identical container and has a so narrow upright portion (27) at the margin of said central 16. A reclosable container for margarine or other foods comprising a semi-rigid tub (1a) molded from a single sheet of plastic having polygonally arranged and oppositely disposed side walls (4a and 5a), each of said walls having an integral lateral otfset (6a) with an integral upright rim portion (7a) at the top portion of the tub which defines a peripheral groove, and a semi-rigid snapin cover (2a) for said tub having a continuous marginal rim flange (9a) with an upwardly extending portion of generally polygonal horizontal cross section which fits in said peripheral groove and conforms substantially to the shape of the rim portions of said tub, said cover having a horizontal marginal portion (15a) resting on said offset, said rim portion having a generally S-shaped cross section above said peripheral groove including a radially ontwardly extending portion (40), a circumscribing upwardly extending portion (41), and a generally horizontal top portion (42), said rim flange (9a) having a radially outwardly extending portion (48), an upwardly extending portion (49) sealingly engaging the upwardly extending portion of said rim portion, and an outwardly extending top portion (50) resting on said horizontal top portion (42) of said tub.

17. A container as defined in claim 16 wherein a peripheral air chamber (21a) of substantial volume is provided between said cover and said tub at the junction of said rim portion (7a) and said lateral ofiset (6a).

18. A container as defined in claim 17 wherein a peripheral air chamber (53) of substantial volume is provided at the junction of said upwardly extending portion (41) and said top portion (42).

19. A container as defined in claim 18 wherein a peripheral air chamber (52) is provided at the junction of said outwardly extending portion (40) and said upwardly extending portion (41).

20. A container as defined in claim 16 wherein said tub has a circumscribing downwardly extending portion (43) near its outer edge and said cover has a circumscribing downwardly extending portion (51) adjacent said lastnamed portion (43).

References Cited UNITED STATES PATENTS 3,307,739 3/1967 Cloyd et a1. 229-43 3,344,974 10/1967 Bostram 229-43 THERON E. CONDON, Primary Examiner. G. T. HALL, Assistant Examiner.

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