| 摘要 |
PURPOSE:To obtain a polyester film having superior glassy transparency and thick film thickness, by specifying a kind of a polycondensation catalyst, diethylene glycol (DEG) content and a polymerization degree of polymer. CONSTITUTION:As a polycondensation catalyst of polyester a soluble germanium compound is used for ethylene glycol as at least a kind of a catalyst. As this is the polyester, whose peculiar viscosity is 0.5-0.8 and DEG content is 1-5mol%, making polyethylene terephthalate to be obtained through polycondensation by making use of the catalyst into a main ingredient and, moreover the polyester whose elongation percentage of a molded plate is less than 30% and having thickness of 4mm. obtained through injection molding by a mold cooled by a coolant of a temperature of 10 deg.C+ or -1 deg.C is made into raw materials, a high-transparency polyester film having a thickness of 25-600mum whose elongation percentage per 100mum in thickness of the film is less than 4%, a surface orientation index is more than 40X10<-3>, and orientated at least in a uniaxial direction can be obtained. |
