Abstract: A polyester film includes a polyester (A) composed mainly of polybutylene terephthalate and a polyester (B) composed mainly of polyethylene terephthalate, wherein a mass ratio (A/B) between the polyesters (A) and (B) is 70/30 to 55/45, a dry heat shrinkage rate (B) through heat treatment at 200° C. for 15 minutes is 35% or less in any of four directions (0°, 45° 90° and 135°) on the film surface, a difference between a maximum value and a minimum value of these dry heat shrinkage rates is 5% or less, a thickness variation in the four directions is 10% or less, and a crystallization index shown in DSC measurement is 25 to 55 J/g.

Abstract: [Problem] To provide a method for producing a polyamide resin film by using a poi amide resin obtained through polymerization of a regenerated monomer used as a recycled material. [Solution] Provided is a method for producing a polyamide resin film, including: a step of producing a monomer from a raw material (A) for depolymerization, (2) a step of producing a polyamide resin (B) through polymerization using a raw material containing the monomer, (3) a step of refining the polyamide resin (B), and (4) a step of producing an unstretched film using a starting material containing the refined polyamide resin (B), and stretching the unstretched film.

Abstract: To provide a method for producing a polyamide resin film by using a polyamide resin obtained through polymerization of a regenerated monomer used as a recycled material. Provided is a method for producing a polyamide resin film, including: (1) a step of producing a monomer from a raw material (A) for depolymerization, (2) a step of producing a polyamide resin (B) through polymerization using a raw material containing the monomer. (3) a step of refining the polyamide resin (B), and (4) a step of producing an unstretched film using a starting material containing the refined polyamide resin (B), and stretching the unstretched film.