| 摘要 |
PURPOSE:To obtain a biaxially oriented polyamide film which is free from a bowing distortion, by a method wherein after a film is stretched within a range of a stretching rate E1 of 5-20% in a widthwise direction of the film, the film is held for at least one second at it is kept at a fixed width and the treated film is slackened within a range of slackening rate E2 of 0% to E1+5% in a widthwise direction of the film. CONSTITUTION:An oriented film is heated, temperature-raised and stretched within a range of a stretching rate E1 of 5-20% in a widthwise direction of the film under a temperature condition within a range of Tm-55 deg.C (provided that the Tm is the melting point of the oriented film). Then after the film is held for at least one second under a temperature condition within a range of Tm-25 deg.C to Tm-5 deg.C as the film is kept at a fixed width, the film is slackened within a range of a slackening rate E2 of 0% to E1+5% in a widthwise direction of the film and a desired biaxially oriented polyamide film is obtained. |
