| 摘要 |
A process for producing a transparent film includes forming a melt from a copolyester having structural units represented by the following formulas I and II, respectively: ( I ) ( II ) wherein R groups may be the same or different from each other are each selected from the group consisting of -CH2CH2,-CH2CH2OCH2CH2-, -CH-CH2- , and , and the molar fraction ration of the structural units of formula II to the total structural units of formulas I and II is between 0.02 to 0.20, which process comprises the steps of forming a melt of the copolyester into a film, rapidly quenching the molten film to solidify the copolyester and impart low crystallinity thereto, aging the solidified film at a temperature of 60 degree centigrade or below and then heat-treating the aged film at a temperature between the glass transition point (Tg) of the copolyester and no greater than 2.degree.C below the melting point of the copolyester minus 2.
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