Microwaveable vacuum skin package

Abstract

The present invention relates to a self-venting microwaveable package of food product comprising a) a rigid or semi-rigid, flat or shaped, support member; b) a food product loaded onto the support a), and c) a flexible thermoplastic film enclosing the food product on the support member, said flexible film being draped over the food product, by vacuum and/or air pressure, in a vacuum skin packaging arrangement, substantially conforming to the shape of the food product and being sealed to the support member outside the periphery of the food product; said package being characterized in that the support member a) as well as the flexible film c) are of microwaveable thermoplastic materials and the peel strength between the support member a) and the flexible film c) is comprised between about 2.0 and about 4.0 N/25.4 mm. The invention also relates to a method of thawing and/or cooking, or re-heating a food product in a microwave oven comprising the step of packaging the food product in a VSP package where the food product is enclosed between a microwaveable rigid or semi-rigid support member and a microwaveable top skin web wherein the peel strength between the support member and the top skin web is comprised between about 2.0 and about 4.0 N/25.4 mm, and placing the package into the microwave oven to cause the radiant energy of the microwave oven to thaw and/or cook, or re-heat the food product as desired, without the need of creating or setting free a venting hole in the package and without removing or loosening the top skin film before putting the package into the oven.

1 - 5 . (canceled) 
   
   
       6 . A method of thawing and/or cooking, or re-heating a food product in a microwave oven comprising:
 packaging the food product in a vacuum skin package where the food product is enclosed between a microwaveable rigid or semi-rigid support member and a microwaveable top skin web wherein the support member and the top skin web are sealed together over a wide area corresponding to the whole support surface not occupied by the product and the peel strength between the support member and the top skin web is between about 2.0 and about 4.0 N/25.4 mm, and   placing the package into the microwave oven to cause the radiant energy of the microwave oven to thaw and/or cook, or re-heat the food product as desired, without making a venting hole in the package before putting the package into the oven and without removing or loosening the top skin web before putting the package into the oven, with the top skin web rising over the product by pressure from vapor released from the product during heating, with a channel being created between the top skin web and the support member to vent off excess vapor.   
   
   
       7 . The method of  claim 6  wherein the peel strength between the support member and the top skin web is between about 2.0 and about 3.5 N/25.4 mm. 
   
   
       8 . The method of  claim 7  wherein the peel strength between the support member and the top skin web is between about 2.0 and about 3.0 N/25.4 mm. 
   
   
       9 . A blend of from about 30 to about 70 wt. % of an EVA copolymer containing from more than 40 to about 80 wt. % vinyl acetate, from about 15 to about 50 wt. % of a polybutylene, and from about 15 to about 50 wt. % of an optionally neutralized ethylene-acrylic or methacrylic acid copolymer. 
   
   
       10 . The method according to  claim 6 , wherein the support member or the top skin web has a seal layer, or a layer adjacent to a seal layer, comprising a resin blend of low cohesive strength. 
   
   
       11 . The self-venting microwaveable package according to  claim 10 , wherein the resin blend having low cohesive strength comprises a blend of:
 (a) ethylene/acrylic acid copolymer and/or ethylene/methacrylic acid copolymer;   (b) a modified ethylene/vinyl acetate copolymer; and   (c) polybutylene.   
   
   
       12 . The method according to  claim 11 , wherein the resin blend of low cohesive strength comprises a blend of from about 30 to about 70 weight percent of an EVA copolymer containing from more than 40 to about 80 weight percent vinyl acetate, from about 15 to about 50 weight percent of a polybutylene, and from about 15 to about 50 weight percent of an optionally neutralized ethylene-acrylic or methacrylic acid copolymer. 
   
   
       13 . The method according to  claim 10 , wherein the resin blend of low cohesive strength is present in a layer adjacent the sealing layer of the support member, and the sealing layer has a thickness of from about 1 μm to about 7 μm. 
   
   
       14 . The method according to  claim 13 , wherein the sealing layer of the support member has a thickness of from about 1 μm to about 6 μm. 
   
   
       15 . The method according to  claim 14 , wherein the sealing layer has a thickness of from about 1 μm to about 5 μm. 
   
   
       16 . The method according to  claim 10 , wherein the peel strength between the support member and the flexible thermoplastic film is obtained by providing the top skin web with a thin seal layer and a layer of low cohesive strength adjacent the thin seal layer, with the layer of low cohesive strength comprising the resin blend of low cohesive strength. 
   
   
       17 . The method according to  claim 6 , wherein the peel strength between the support member and the flexible thermoplastic film is achieved between a seal layer of the support member and a seal layer of the flexible film, by providing these seal layers with resins or resin blends of a sufficiently different chemical nature. 
   
   
       18 . The method according to  claim 6 , wherein the peel strength between the support member and the flexible thermoplastic film is achieved by using in at least one of the support member and the flexible thermoplastic film, a thin sealing layer and an adjacent layer of a thermoplastic material suitably selected so that a bond between the sealing layer and the adjacent layer is low.