Patent ID: 6428882
Filing Date: 2002-08-06
Classification: B32B,Y10S,Y10T

Abstract:
A biaxially oriented polyester film having a base layer of at least 80% by weight based on the total weight of the base layer of at least one thermoplastic polyester, and having a cover layer and, located on the cover layer, a layer functioning as an O2 barrier, wherein said cover layer is about 0.2 to about 4.5 &mgr;m thick and includes a polymer which comprises at least 40% by weight of ethylene 2,6-naphthalate units; and ethylene terepthalate units at greater than 0% up to 40% by weight; and if desired, 0% up to 60% by weight of units from other aliphatic, cycloaliphatic or aromatic diols and/or aliphatic, cycloaliphatic or aromatic dicarboxylic acids; with the proviso that the Tg2 value of the polyester film is above the Tg2 value of the base layer but below the Tg2 value of the cover layer; and wherein said base layer includes at least 90 mol percent of a component selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, and a combination thereof.