There is disclosed a biaxially oriented film formed of film forming composition comprising a polyoxymethylene polymer in which the major constituent of the main chains of said polymer each of consists substantially of repeating units of oxymethylene group (̵ CH2-0 )̵. said film being characterized in that, when said film is remelted at a temperature above the melting point of said film and the resulting melt is recrystallized isothermally at 140°C into a solid in film form, the number of polyoxymethylene spherulites in the crystal structure at the surface of the resulting film would be at least 50 per 0.1 mm2 area of the resulting film surface, as measured with a polarizing microscope through cross-polarizers, and a process for manufacturing the same.
本发明公开了一种双向拉伸薄膜,该薄膜由包含聚氧化亚甲基聚合物的成膜组合物形成,其中所述聚合物主链的主要成分基本上都由氧化亚甲基基团(̵
CH2-0 )̵的重复单元组成。所述薄膜的特征在于,当所述薄膜在高于所述薄膜熔点的温度下重熔,所得熔体在 140℃下等温重结晶成膜状固体时,用偏光显微镜通过交叉偏振器测量,所得薄膜表面晶体结构中的
聚氧亚甲基球状体的数量至少为每 0.1 平方毫米所得薄膜表面积 50 个。