Biaxially oriented polyethylene-2,6-naphthalate film containing another polyester resin and process for its production

A biaxially oriented polyethylene-2,6-naphthalate film, which comprises a blended mixture of

• 1. a polyethylene-2,6-naphthalate resin having a unit derived from not more than 10 mol % of a polyester-forming component other than a polyethylene-2,6-naphthalate-forming component, and (2) 0.5 to 10% by weight, based on the polyethylene-2,6-naphthalate resin (1), of a polyester resin other than the polyethylene-2,6-naphthalate resin (1) which contains at least 90 mol % of units derived from a dicarboxylic acid component selected from the group consisting of terephthalic acid, isophthalic acid, adipic acid, oxalic acid, succinic acid, naphthalene-2, 6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, 4,4'-tetramethylene diphenyl dicarboxylic acid and lower alkyl ester functional derivatives of these acids, and a glycol component selected from the group consisting of ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol and functional derivatives of these glycols, in which the amount of the homopolyester unit is at least 90 mol %,
• said film having a softening point at least 1.degree.C. higher than its equilibrium softening point.