| 摘要 |
PROBLEM TO BE SOLVED: To prepare a polyester film low in oligomer, small in reduction of intrinsic viscosity when subjected to extrusion molding, little in the asperities of the surface and high in elastic property, and to provide a production method of a polyester film capable of largely reducing a filtrating pressure, shearing heat and extrusion torque without reforming any traditional film-producing apparatus by exceedingly reducing a melting viscosity of a polyester raw material with a high intrinsic viscosity when subjected to melting extrusion. SOLUTION: This polyester film comprises (A) a polyester and (B) a styrene- based polymer having an average molecular weight of 1,000 to 20,000. The film is obtained by melt-extruding the polymer A by an extruder 1 and then adding 0.05 to 10 wt.% of the styrene-based polymer B in advance of filtrating the polyester A with a filter 4, followed by conducting a film-forming. |
