| 摘要 |
PURPOSE:To provide a p-phenylene terephthalamide (PPTA) film with improved tear performance by a method wherein a crystal orientation angle by X-rays incident normal to the surface of the film and the ratio of minimum intensity to maximum intensity in the angular distribution of the intensity of fluorescent radiation by polarized parallel rays incident normal to the surface of the film are specified. CONSTITUTION:In a polyamide film, the logarithmic viscosity number of which is 3.5 or more and which substantially consists of PPTA, a crystal orientation angle with respect to the peak in case of 2theta 23 deg. by X-rays incident normal to the surface of the film is 70 deg. or more. If the crystal orientation angle in case of 2theta 23 deg. is smaller than 70 deg., the balance of the properties in longitudinal direction and in lateral direction of the film is lost. The ratio is minimum intensity to maximum intensity in the angular distribution of the intensity of fluorescent radiation by polarized parallel rays incident normal to the surface of the film lies within the range of 0.7-1.0. The solvent suitable for preparing the dope for forming a PPTA film is sulfuric acid with the concentration of 95wt% or more. The way to obtain a transparent film with excellent mechanical properties is to invert the dope from its optical anisotropic property to its optical isotropic property before its solidification after the dope is cast onto a supporting surface. |
