Stretched polyester film from a polymer blend

摘要

A transparent polyester film having excellent printability, flexing resistance and pinhole resistance and further excellent interlaminar strength, which is made from a polymer mixture or blend comprising (i) a polyester consisting essentially of a residue of dibasic acids wherein at least 80 % by mol is terephthalic acid and a residue of at least one glycol and (ii) a block copolyester consisting of a crystalline polyester (hard) segment having a high melting point and a soft polymer segment having a low melting point and a number average molecular weight of 400 to 8,000, said soft polymer segment having a low melting point being contained in an amount of 0.5 to 10 % by weight on the basis of the whole weight of the polymer mixture or blend, and said crystalline polyester segment having a melting point of at least 170 DEG C when a polymer is produced by the monomers composing the segment alone and said soft polymer segment having a melting or softening point of 100 DEG C or lower.