BIAXIALLY ORIENTED POLYETHYLENE NAPHTHALATE COPOLYMER FILM

摘要

A biaxially oriented polyethylene naphthalate copolymer film, characterized by: (1) being substantially made from a polyethylene naphthalate copolymer which comprises ethylene naphthalate units in an amount of 92 to 99.5 mole % based on the total amount of the repeating units and contains at least one comonomer component selected from the group consisting of the following components (a) to (d) in an amount of 0.5 to 8 mole % based on the total amount of the dicarboxylic acid components: (a) glycols having a fluorene skeleton in the molecule, (b) p-hydroxymethylbenzoic acid, (c) p-hydroxyethoxybenzoic acid, and (d) p-hydroxyethoxybenzoic acid, (2) having moduli of longitudinal elasticity and transverse elasticity of each 500 kg/mm<2> or above, and (3) exhibiting delamination resistance in terms of rate of fold whitening of 10 % or below. The film has excellent delamination resistance, anticurling properties, mechanical strengths, color, hue and transparency, thus being valuable as a base film for photographic films.