| 摘要 |
PURPOSE:To improve the impact resistance, by using a polyester having a particular high-melting crystalline segment to form a polyester blocking copolymer, of a polyalkylene glycol, having a predetermined low-melting soft polymer segment. CONSTITUTION:Dimethyl terephthalate, ethylene glycol, a polyalkylene glycol having a mol.wt. of not less than 200, an antioxidant, and a polycondensation catalyst are heated in an autoclave with stirring to conduct polycondensation, thereby preparing a polyester block copolymer comprising a high-melting crystalline segment of a polyester, having an m.p. of 200 deg.C or above, of a dibasic acid residue and a glycol residue; and a low-melting soft polymer segment of a polyalkylene glycol, having an m.p. or a softening point of 80 deg.C or below. The polymer is dried in vacuum and extruded into an unstretched film which is then biaxially stretched about 1.5 to 10 times at about 0 to 130 deg.C to prepare a soft polyester film having a tensile modulus of elasticity (20 deg.C) of 0.01 to 100kg/mm<2>. |
