| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a polyester film having a small metal element/ phosphorus element ratio with good productivity. SOLUTION: In the case of manufacturing a cast film by close contact cooling to solidify a polyester resin on a cooling medium after the resin is molten, a surface temperature of the medium at a position immediately before the molten polyester is grounded is held at a glass transition point Tg to a melting point Tm of the resin and the resin satisfies a formula 0.4<=(m/2+N+L)/P<=1.2, wherein m is number of moles of an alkali metal per 1 ton of the resin, N is number of moles of an alkali earth metal per 1 ton of the resin, L is number of moles of a metal element selected from Mn, Co and Zn per 1 ton of the resin, and P is number of moles of a phosphorus element per 1 ton of the resin. |
