FORMING METHOD FOR POLYETHYLENE NAPHTHALATE FILM

摘要

This invention describes the method of producing polyethylene naphthalate film to be used a high density magnetic recording medium, wherein the film has the tensile stress of 15-25 kg/mm2 while the coefficient of expansion remains 5 % at any directions, and the coefficient of thermal contraction is less than 2.0 % and the Young's modulus is 600-900 kg/mm2 while their deviation is less than 10 %.