PURPOSE: To generate a backseamed skin by providing a heat sealing layer containing a blend of a specific wt.% of a copolymer based on propylene and a specific wt.% of a uniform ethylene/α-olefin copolymer having specific density to perform molding.

CONSTITUTION: A thermoplastic film fitted to cook-in packaging has an inner sealing layer, a food contact layer, a nylon layer and an outside layer or an inner sealing layer, a food contact layer, a nylon layer, a barrier layer and an outside layer. The heat sealing layer of the inner sealing layer and the contact layer comprises a blend consisting of about 50-95 wt.% a copolymer based on propylene and about 5-50 wt.% of a uniform ethylene/α-olefin copolymer having a density of below about 0.9 g/cc. Since the thermoplastic film is biaxially oriented, it shrinks during cooking to be closely fitted to food and elastic recovery characteristics are applied by the nylon layer.