| 摘要 |
PURPOSE:To obtain the subject film excellent in tear strength by placing an optically anisotropic dope of a para-configulating aromatic polyamide on the surface of a substrate in a film shape, then converting the anisotropic nature to isotropic nature, coagulating the film-shaped dope, removing the solvent, subsequently immersing the coagulated film into an organic solvent and drying. CONSTITUTION:An optically anisotropic dope composed of a p-configulating polyamide (e.g. poly-p-benzamide) having >=2.5 logarithmic viscosity number and a solvent selected from concentrated sulfuric acid, chlorosulfuric acid and fluorosulfuric acid respectively having >=96 wt.% concentration is formed into a film on the surface of a substrate while keeping the optical anisotropy. The anisotropic nature of the above mentioned dope is converted to isotropic nature by moisture absorption and/or heating and the solvent is removed after coagulation to obtain a film. The resultant film if subsequently immersed into an organic solvent miscible with water and then dried at <=300 deg.C while controlling shrinkage, thus obtaining the objective film having <=1.35 g/cm<3> density, >=700 kg/mm<2> Young's modulus and >=30 kg/mm<2> tear strength/thickness. |
