CLOSURE FOR FOOD CONTAINER

Abstract

A closure for a preformed food container such as an sandwich wedge comprises a one-piece blank including an aperture (4) into which the food container is inserted. The blank is foldable about a predetermined line (6) to form a front wall (8) overlying a back wall (9) and trapping between the front and back walls a projecting lip extending from a rim of the container. The front (8) and back (9) walls are sealed together, thereby closing the container.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority from Provisional Application U.S. Application 61/723,112, filed Nov. 6, 2012, incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a closure system which is used for the heat seal or self-seal of pre-formed plastics-based or cardboard-based containers for use with food products.

BACKGROUND OF THE INVENTION

Plastic and cardboard sandwich wedges and other food containers have been around for many years. The plastics-based containers are usually sealed with a film, whereas the cardboard-based products are sealed by melting a PE (polyethylene) coating to form a seal.

SUMMARY OF THE INVENTION

We provide a method of sealing a food container such as an “open sandwich wedge” by the use of a cut and creased and folded piece of board with an applied film window.

The “Open sandwich wedge board closure” is coated by either a polypropylene- or glue-based laminate on one side which, either via heat and pressure or just pressure, seals to itself.

The open wedge (open wedge material can be paper, board or an oil-based derivative) is inserted into an aperture in the Open sandwich wedge board closure. The Open sandwich wedge board closure is then folded in half allowing the two inner sides of the Open sandwich wedge board closure to meet.

When pressure (with glue only) or heat and pressure (with a polypropylene or similar laminate) are applied, adhesion occurs which seals the two inner sides of the Open sandwich wedge board closure together, thus securing and sealing the open wedge to the Open sandwich wedge board closure and ensuring the product packed stays fresh and securing the product for counter display.

A window made from a clear film on the opposite side to the aperture allows the product to be seen for display purposes.

According to a first aspect of the present invention we provide a closure for a preformed food container comprising:

(a) a one-piece blank foldable about a predetermined line to form a front wall overlying a back wall and trapping a portion of the container between the front and back walls; and

(b) a seal between the front and back walls of the blank.

Preferably but without limitation, the container includes an open cavity to receive at least one food item and a projecting lip extending from a rim of the cavity; the closure includes an aperture in the back wall adapted to receive the food container with the lip overlying the back wall; and in use the lip of the food container is trapped between the front and back walls of the blank.

Preferably, in use the contents of the food container are visible through the front wall of the blank, for example by incorporating a transparent window in the front wall of the blank.

According to another aspect of the present invention we provide a method of closing a preformed food container by means of a one-piece blank foldable about a predetermined line to form a front wall overlying a back wall, wherein the container includes an open cavity to receive at least one food item and a projecting lip extending from a rim of the cavity, and the method includes the steps of:

(a) inserting the food container through an aperture in the back wall of the blank so that the lip overlies the back wall;

(b) folding the front wall of the blank over the back wall so as to trap the lip of the food container between the front and back walls of the blank; and

(c) sealing together the front and back walls of the blank.

The seal may be formed by application of heat or pressure or any combination of heat and pressure.

Preferably, the seal is tamper-proof, that is the closed container cannot be opened without leaving visible evidence of access. The seal may be demountable, in which case it should not be resealable, or a user may gain access to the contents of the container by cutting or tearing the container or closure, for example by means of a tear strip.

Preferably, at least a significant proportion of the closure is made of biodegradable material such as cardboard.

It will be appreciated that the terms “front wall” and “back wall” do not necessitate any particular orientation but are convenient labels to distinguish between the two layers of the blank after they are folded one over the other.

Accordingly, in the first aspect of the present invention, the blank is produced from one piece of cardboard wherein the closure comprises:

an aperture in the “back wall” that fits around and under a container's body and lip;

a window which is formed by the application of a transparent film closing an aperture on the opposite panel (the “front wall”)

an application of self-adhesive glue or a polyethylene (PE) coating; and

a crease along the centre of the blank allowing the folding of the present invention to secure the container and seal the open cavity thereof.

In a preferred embodiment, the back wall of the blank will include an aperture that would be suitable for all sizes and shapes of containers.

In a preferred embodiment, the front wall of the blank would have an aperture which would be covered with a clear plastic material to allow the contents of the food item to be viewed.

As indicated above, the one piece blank is cut and folded, with two cut-outs, one to hold a container and the other to have clear film plastic applied to form a window. A PE coating laminated to the cardboard will seal the front and back walls together using heat and pressure. An alternative to the PE coating is an applied adhesive which on contact with adhesive on an opposite surface forms a seal without the use of heat, only pressure.

This invention enables the closure of a preformed food container. By folding the blank in half the opposed faces of the blank touch and so a seal can be formed, trapping the lip of the container between the two pieces of cardboard and closing the container.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will be further described with reference to the following drawings in which:

FIG. 1 shows a plan of a blank according to the present invention;

FIG. 2 shows an elevation of the sealing mechanism in the closed position from the rear;

FIG. 3 shows an elevation of the sealing mechanism in the closed position from the front;

FIG. 4 shows an elevation of the sealing mechanism with arrow 10 showing the insertion direction of the food container and arrow 11 showing the folding of the blank.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As FIG. 1 shows, the closure blank is formed from a single piece of cardboard. The blank consists of a front wall 8, which is rectangular in shape. One of the long edges of the front wall connects to a back wall 9, also rectangular in shape, via a crease 6; this could be also a perforation or score.

In the back wall, an aperture 4 allows the insertion of the container (not shown) to be sealed. This aperture will be produced to the correct size to fit the container's dimensions.

In the front wall 8, there is an aperture 5, which allows the application of a clear plastic film window 7 to allow the contents of the container to be viewed.

As FIG. 2 shows, the blank is folded and sealed. The aperture 4, which would hold the container, is clear to see and the aperture 5, which has a plastic clear film to form a window 7, on the opposite panel can be seen. The lip of the container would be now sandwiched between front wall 8 and back wall 9.

As FIG. 3 shows, the blank is folded and sealed, the aperture 5, with the clear plastic film window 7, is visible; the lip of the container placed into the aperture would now be sandwiched between the front wall 8 and the back wall (not visible under front wall 8).

As FIG. 4 shows, the arrow 10 shows the direction of placement of the container to be sealed; arrow 11 shows the folding of the blank which would then sandwich the container into place, thereby trapping the lip of the container between front wall 8 and back wall 9.

Claims

1. A closure for a preformed food container comprising:

a one-piece blank configured to fold about a predetermined line to form a front wall overlying a back wall and to trap a portion of the container between the front and back walls; and

a seal disposed between the front and back walls of the blank.

2. A closure for a preformed food container having an open cavity configured to receive at least one food item and a projecting lip extending from a rim of the cavity, the closure comprising:

a one-piece blank configured to fold about a predetermined line to form a front wall overlying a back wall; and

a seal disposed between the front and back walls of the blank,

wherein the back wall comprises an aperture configured to receive the food container with the lip overlying the back wall such that, in use, the lip of the food container is trapped between the front and back walls of the blank.

3. The closure as claimed in claim 2, wherein, in use, contents of the food container are visible through the front wall of the blank.

4. The closure as claimed in claim 2, wherein the front wall comprises a transparent window.

5. The closure as claimed in claim 2, wherein the seal is formed by application of heat.

6. The closure as claimed in claim 2, wherein the seal is formed by application of pressure.

7. The closure as claimed in claim 2, wherein the seal is demountable.

8. The closure as claimed in claim 2, wherein the seal is tamper-proof.

9. The closure as claimed in claim 2, wherein the closure is substantially made of a biodegradable material.

10. The closure as claimed in claim 9, wherein the biodegradable material is cardboard.

11. A one-piece blank configured to form a closure for a preformed food container comprising:

a portion foldable about a predetermined line to form a front wall overlying a back wall and to trap a portion of the container between the front and back walls; and

a seal disposed between the front and back walls of the blank.

12. A one-piece blank adapted to form a closure for a preformed food container having an open cavity configured to receive at least one food item and a projecting lip extending from a rim of the cavity, the blank comprising:

a portion foldable about a predetermined line to form a front wall overlying a back wall; and

a seal disposed between the front and back walls of the blank,

wherein the back wall comprises an aperture configured to receive the food container with the lip overlying the back wall such that, in use, the lip of the food container is trapped between the front and back walls of the blank.

13. A method of closing a preformed food container via a one-piece blank configured to fold about a predetermined line to form a front wall overlying a back wall, wherein the food container includes an open cavity configured to receive at least one food item and a projecting lip extending from a rim of the cavity, the method comprising the steps of:

inserting the food container through an aperture in the back wall of the blank such that the lip overlies the back wall;

folding the front wall of the blank over the back wall to trap the lip of the food container between the front and back walls of the blank; and

sealing together the front and back walls of the blank.

14. The method as claimed in claim 13, wherein the sealing comprises forming a seal by application of heat, pressure, or a combination thereof.