| 摘要 |
PURPOSE:To manufacture a polyester film, in which the bleed-out of an oligomer is reduced extremely, even when the film is exposed at a high temperature for a prolonged term by bringing a biaxially oriented polyester film into contact with a roll once, thermally treating the film further thermally treating the film by a tenter for holding both end sections. CONSTITUTION:A polyester film casted is heated by a roll, oriented by approximately 2.5-7 times at one stage or multistages in the longitudinal direction, cooled once, gripped by clips again and heated in a tenter, and oriented by approximately 2.5-6 times in the cross direction. A cross orientation temperature TTD or higher is used as a roll heat treatment temperature, and a temperature range of TTD+80 deg. or lower, preferably TTD+50 deg.C or lower is favorable. Accordingly, a film, which has excellent thermal dimensional stability and quality of which is equalized in the cross direction, is obtained. |
