摘要 |
The present invention relates to a process for producing a polyester film containing a incompatible polymer, comprising: using a vented twin-screw extruder having a material feed port and vents in the cylinder, and melt-extruding a substantially undried polyester together with a polymer incompatible with said polyester, which melt-extruding is conducted under the condition that the content of said incompatible polymer is not less than 1 wt% based on the total output based on unit time (kg/hr), and the total output Q, extruder screw speed N (rpm) and cylinder bore D (mm) satisfy the following formula. <MATH> f |