| 摘要 |
PURPOSE:To produce a polyester which can form a film excellent in transparency, flatness, slidability and electrical properties, by adding a phosphorous compound and a specified amount of fine particles to the reaction mixture during polycondensation reaction. CONSTITUTION:In the production of a polyester consisting mainly of repeating units of ethylene terephthalate, 0.05-5wt% phosphorus compound of a MW >=300 and 0.005-2wt% fine particles of an average particle diameter of 0.03-3mum are added to the reaction mixture during the reaction from the time before the start of esterification or transesterification to the time of completion of polycondensation reaction. As the phosphorus compounds, those containing a phenolic hydroxyl group of the formula (wherein R1 and R2 are each a 1-10C alkyl, R3 is a 2-24C phosphinate or phosphonate group and n is 0-5) are desirable. As said fine particles, those of e.g., calcium carbonate, silicon dioxide, etc., are used.
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