| 摘要 |
PROBLEM TO BE SOLVED: To simplify a film making process by a method wherein the coefficient of planar orientation of a film is set to be within the specified range. SOLUTION: Thermoplastic resin is thermally fused and guided to a mouth piece so as to be melt-extruded and quenched and solidified in order to obtain a cast film. In a process as just mentioned above, the coefficient of planar orientation fn of the film is set to be within the range of 10×10<-3> <=fn<=200×10<-3> . Further, in a sheet-like film, which is obtained by being quenched and solidified after being melt-extruded with a flat die, the birefringenceΔn of the film it set to be with in the range of 10×10<-3> <=Δn<=120×10<-3> . By produce producing a molecular orientation in the direction within the surface of the film at the stage of the cast film, the following orientation giving process can be omitted or simplified. |
