Paper food container with injection molded top rim structure and method of manufacturing same

Abstract

A food container in the form of a paper cup having a top edge and a plastic rim structure which is injection molded to the edge so as to seal the edge and be firmly be adhered thereto. The rim structure exhibits a flat annular upper surface to which a heat sealable closure made of metal foil with heat sealable plastic underlayer can be attached after filling the container with a suitable food product.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a food container manufactured in accordance with the present invention;

FIG. 2 is a side view in section of a first embodiment of the invention;

FIG. 3 is a side view in section of a paper cup of FIG. 2 being inserted into a mold;

FIG. 4 is a side view in section of the paper cup of FIG. 3 after insertion into the mold and injection molding a rim structure;

FIG. 5 is a side view in section of the open mold with the cup of FIG. 2 being removed from the mold;

FIG. 6 is a perspective view of a representative mold showing how multiple articles incorporating the principals of the present invention are simultaneously formed;

FIG. 7 is a perspective view of a second embodiment of a cup before injection molding the rim;

FIG. 8 is a side view, in section, of the cup of FIG. 7 after molding the rim structure;

FIG. 9 shows a molding step associated with the manufacture of still another embodiment of the invention;

FIG. 10 shows a further molding step for the embodiment of FIG. 9;

FIG. 11 is a perspective view of the embodiment made by the molds shown in FIGS. 9 and 10; and

FIG. 12 is a sectional side view of the embodiment of FIG. 11.

Claims

1. A food container comprising: a cup-shaped paper container having an open top terminating in an annular edge;a plastic rim structure injection-molded in sealing relationship to and over the edge and providing a substantially flat annular upper surface.

2. The food container article of claim 1, further including an impermeable coating material on the interior of the cup selected from the group consisting of polyolefins, polyurethane, and polyethylene.

3. The food container article of claim 1 further including a heat-sealed foil cover.

4. A food container as defined in claim 1 wherein the edge of the paper cup is rolled.

5. A food container as defined in claim 1 wherein the edge of the cup is straight and a plurality of circumferentially spaced holes are formed in the cup below the edge such that the plastic rim structure fills said holes.

6. A food container as defined in claim 1, wherein the cup edge is straight, and the rim structure comprises a first wall extending down and overlying the outside surface of the cup, and a thin but relatively rigid annular top rim overlying the cup edge but of greater outer diameter than the cup.

7. A food container as defined in claim 6 wherein the rim structure extends sealingly over the edge and into the interior of the cup.

8. A method of manufacturing a food container comprising the steps of: forming a cup shaped paper container having a top edge and a side seam;placing the paper container into a mold;injection molding a plastic rim structure around the top edge so as to adhere to and substantially encapsulate the edge while providing a substantially flat annular upper surface; andremoving the cup-shaped paper container with the injection molded plastic rim structure adhered thereto from the mold.

9. The method of claim 8 further including the step of enhancing the mechanical attachment of the rim structure to the cup.

10. The method of claim 8 including the further step of sealing the inside edge of the side seam.

11. A method of packaging a food product comprising the steps of: (a) manufacturing a container according to the steps of claim 8 and, thereafter,(b) filling the container with a food product; and(c) applying a heat-sealable cover to the flat annular upper surface of the injection molded rim structure.