Processes for producing transparent copolyester films.

摘要

A process for producing a transparent film having high transparency and good mechanical properties includes forming a melt from a copolyester having structural units represented by the formulae I and II: wherein R represents groups which may be the same or different and which are each selected from the groups: and the molar ratio II : I+II is between 0.02 and 0.20; forming the molten copolyester into a film, rapidly quenching the molten film, ageing the solidified film at 60 DEG C or below and then heat-treating the aged film at a temperature between the copolyester s glass transition point (Tg) and no greater than 2 DEG C below its melting point (Tm).