| 摘要 |
<p>PURPOSE:To increase tear propagation resistance and reduce irregularity of thickness by a method wherein an unoriented film composed of polyester of a specific structure is stretched in one direction, at a specific temperature and at a specific magnification. CONSTITUTION:Polyether ester having ethylene-alpha,beta-bis(2-chlorophenoxy)ethane 4,4'-dicarboxylate as the principal repetition unit and melting viscosities of 500- 20,000 poise is extruded by a melting extruder in a sheet form, cooled and hardened to form an unoriented film. This unoriented film is stretched by 3.0-5.0 times in one direction and then by 3.0-6.0 times at the cold crystallization temperature of polymer Tcc-Tcc+40 deg.C in the direction rectangular to said direction to obtain polyether ester film. Additionally, it is preferable for higher Young's modulus to stretch this film in one more direction at least.</p> |
