Patent ID: 6872461

Claim:
A coextruded, biaxially oriented polyester film comprising, as flame retardant, an organophosphorus compound soluble in the polyester, where the film has a matt outer layer which comprises a mixture or a blend or a mixture and a blend made from two components I and II, where component I is a polyethylene terephthalate homopolymer or polyethylene terephthalate copolymer or a mixture made from polyethylene terephthalate homo- or copolymer, and component II is a condensation product of the following monomers or of their derivatives capable of forming polymers or of the following monomers and of their derivatives capable of forming polymers: A) from about 65 to about 95 mol % of isophthalic acid, B) from 0 to about 30 mol % of at least one aliphatic dicarboxylic acid of the formula HOOC—(CH 2 ) n —COOH where n is from 1 to 11; C) from about 5 to about 15 mol % of at least one sulfomonomer containing an alkali metal sulfonate group on the aromatic moiety of an aromatic dicarboxylic acid; D) an aliphatic or cycloaliphatic glycol having from 2 to 11 carbon atoms, in the amount necessary to form about 100 mol % of condensate; where each of the percentages given is based on the total amount of the monomers forming component II.