| 摘要 |
PROBLEM TO BE SOLVED: To obtain an effect for improving quality of yield or a film by suppressing generation of foreign substances, modified polymers, etc., caused by thermal deterioration of the resin and decreasing defects caused by foreign substances when a film is formed and to prevent the film from being broken during drawing of a film and to decrease amt. of oligomer in the film by suppressing regeneration of the oligomer in the resin. SOLUTION: A method for extruding a thermoplastic resin wherein after the thermoplastic resin is melted by heating it at least at the melting completing temp, it is cooled under an atmosphere at least at the crystallization starting temp. of the resin in decreasing temp. and then, temp. of the flow path for the resin is set at a higher temp. than the cooling temp. to perform extrusion is provided and a biavisally oriented thermoplastic resin film is obtd, by performing extrusion by using this method for extrusion and molding it into a sheet and performing thereafter biaxial orientation. |
