| 摘要 |
PURPOSE:To obtain the polyoxymethylene polymer film having high rigidity and high dimensional stability by specifying the degree of crystallinity of the film as well as the degree of orientation of the crystal thereof. CONSTITUTION:The biaxially orientated film is formed by employing polyoxymethylene polymer, in which the principal part of the backbone chain thereof is constituted of the repeated unit of oxymethylene base-(CH2-O). The degree of crystallinity of the film, which is measured by density method, is 75-95% and the degree of orientation of crystal, which is measured by X-ray deffractometry from two directions of end and edge, is 85-95% respectively. When the degree of crystallinity is less than 75%, the rigidity and dimensional stability are reduced. When the same exceeds 95%, formation of the film is very hard. When the degree of orientation of crystal is less than 85%, the orientation of the crystal is insufficient and the high rigidity of the film can not be obtained, however, when the same exceeds 95%, the formation of the film is very hard. Accordingly, the polymerized film, satisfying these important conditions, may obtain the tensile elasticity of 550kg/mm<2> or more in respective directions of axes respectively. |
