| 摘要 |
PURPOSE:To decrease bowing rate without causing the fusion of films by giving a first step heat-treatment to biaxial-oriented films at specific temperature, after that, giving a second step heat-treatment thereto at specific temperature by making air interpose between both films separated by cutting and opening both ends and then winding them up. CONSTITUTION:Biaxial orientation means 10 serve to extend a crystalline thermpolastic resin film 1. First heating means 20 by a tubular method is made at contraction commencement temperature of the film 1 or higher and a first step heat treatment is given thereto at a temperature 20 deg.C below the melting point of the film 1 or lower. Triming means 30 act to cut and open both ends of the film 1 in order to split it into two sheets of film 1A, 1B. Next, at means 40, they are superimposed while interposing air between both films 1A, 1B and then the superimposed films 1A, 1B are subjected to a heat-treatment while grasping both ends thereof by means of a tenter 50 at a temperature of the first step heat-treatment temperature or higher and at a temperature of the melting point of the film or lower. Finally, the films 1A, 1B are wound up by means of winding up means 70. |
