| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a polyester film, by which a polyester film exhibiting good durability under high-temperature and high-humidity conditions can be obtained with good productivity.SOLUTION: The method for producing a biaxially oriented polyester film comprises a process of melt-extruding a polyester resin composition A, molding it into a sheet, and thereafter stretching the sheet in two axial directions, i.e., a longitudinal direction and a width direction. The polyester resin composition A contains a polyester resin composition α in an amount of 5-50 mass% inclusive based on the polyester resin composition A. The polyester resin composition α has an alkali metal element content WA of 165 to 850 ppm inclusive and a phosphorus element content WP of 330 to 2,000 ppm inclusive, and WA/WP is 0.3 to 0.8 inclusive. |
