COPOLYESTER, PROCESS FOR PRODUCING THE SAME, AND POLYESTER FILM

摘要

The cost of producing a polyester resin or film excellent in transparency, flexibility, etc. is reduced, and a flexible polyester film producible at a low cost and a flexible polyester resin suitable for the production are provided. The resin is a copolyester synthesized from an acid ingredient comprising either an oligomerized fatty acid comprising 15-95 wt.% fatty acid dimer and 5-85 wt.% fatty acid trimer or a derivative thereof and a glycol ingredient, and has a melt viscosity as measured at 250°C of 1,000-3,000 P. The flexible polyester film is obtained from this copolyester by melt formation.