COPOLYESTER AND POLYESTER FILM HAVING SAID COPOLYESTER AS SUBBING LAYER

摘要

There are disclosed a copolyester which comprises at least four components of: (A) terephthalic acid and/or its ester forming derivative (terephthalic acid component) and isophthalic acid and/or its ester forming derivative (isophthalic acid component) with a molar ratio of 30/70 to 70/30; (B) 5 to 15 mole % of a dicarboxylic acid having sulfonate group and/or its ester forming derivative based on the all dicarboxylic acid components; (C) an alicyclic dicarboxylic acid and/or its ester forming derivative; and (D) 50 mole % or more of ethylene glycol based on the all glycol components; and a polyester film which comprises a subbing layer containing the copolyester provided on at least one side of a polyester film base.