FORMING METHOD FOR POLYESTER FILM

摘要

Method according to the invention consists of step stretching lengthwise the sheets cooled rapidly in the temperature range of 20-25 ; the step loosing the sheets in the temperature of Tg+10 Tr Ts+30 (Tg : the glass transition temperature of biaxial stretching sheet, Tr : the loosing temperature, Ts : the preheating temperature); the step stretching the sheets widthwise. The keeping time of longitude stretching is not more than 0.1 second. The longitude-stretching rate is the range of 0.5-20deg. C.