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.

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; and   removing 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.