| 摘要 |
PURPOSE:To obtain wrinkle-free film which is excellent in light transmission, heat resistance and mechanical properties, by a method wherein the title polymer having a high polymerization degree and a specific melt viscosity is melted and extruded in the form of film and then is stretched biaxially and heat-treated under specific conditions. CONSTITUTION:Polyphenylene sulfide having a high degree of polymerization wherein the content of repeating units of farmula I is 90mol% or more and the specific melt viscosity muO ranges 300-100,000 poise at a temperature of 300 deg.C and at a shear rate of 200/sec is melted, extruded in the form of film and then is stretched biaxially so that the degree of double refraction of the stretched film satisfies equations II and III (wherein ngamma, nbeta are refractive indexes in the major and minor axial directions on a section parallel to the film surface of an optical indicatrix, nalpha is a refractive index in the direction of thickness and the density rho satisfier equation IV (where rhoO is an amorphous density). Then, heat-treatment is conducted under such conditions that dimensional changes in length and breadth do not exceed + or -15% and equation V be satisfied. |
