BIAXIALLY STRETCHED POLYESTER FILM FOR MOLDING

摘要

PROBLEM TO BE SOLVED: To obtain a polyester film for a transfer foil useful as a base film for an in-mold transfer foil excellent in deep drawing processability. SOLUTION: This biaxially stretched polyester film for molding is characterized in that the film is obtained by mixing and extruding polyethylene terephthalate(PET) with a modified PBT prepared by copolymerizing 70-95 mass% of polybutylene terephthalate(PBT) with 30-5 mass% of a polytetramethylene glycol(PTMG) having 600-4,000 molecular weight so as to provide (70/30) to (95/5) (mass ratio) of the PET/modified PBT and stretching the extruded mixture and the minimum value (SMIN) and the maximum value (SMAX) of the omnidirectional tensile breaking elongation and the minimum value (KMIN) and the maximum value (KMAX) of the omnidirectional tensile strength satisfy a specific relationship.