Patent ID: 6391410
Filing Date: 2002-05-21
Classification: B32B,Y10S,Y10T

Abstract:
A method of impeding the flow of the gases H2O, N2, CO2, He or flavors through the packaging of a foodstuff, comprising packaging the foodstuff with a transparent, biaxially oriented polyester film comprising:(A) a base layer, at least 80% by weight of which is composed of a thermoplastic polyester; (B) at least one outer layer, wherein the outer layer is composed of a polymer or of a mixture of polymers comprising at least 40% by weight of ethylene 2,6-naphthalate units; optionally up to 40% by weight of ethylene terephthalate units; and optionally up to 60% by weight of units from aliphatic diols, cycloaliphatic diols, aromatic diols, aliphatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, aromatic dicarboxylic acids, or a combination thereof, wherein the glass transition temperature (Tg2 value) of the polyester film is above the Tg2 value of the base layer but below the Tg2 value of the outer layer, and wherein the transparent, biaxially oriented polyester film impedes the flow of the gases H2O, N2, CO2, He or flavors.