| 摘要 |
PURPOSE:To obtain an ethylene terephthalate-based polyester of excellent particle dispersibility and electrostatic cohesion by a direct polymerization process, by adding each of a Mg compound, an alkali metal compound, a P compound and an inert fine powder at a specified point during the reaction. CONSTITUTION:In producing a polyester containing an ethylene terephthalate unit as the main repeating unit by a direct polymerization process, both a Mg compound and Na and/or K compounds in amounts which simultaneously satisfy the relationships I , wherein Mg is an amount of the compound (ppm, in terms of Mg) based on polyester, and II, wherein M is an amount of the compound (ppm, in terms of metal) based on polyester, are added at an arbitrary point before completion of the precondensation reaction; a P compound in an amount which satisfies the relationship III (wherein Mg/P is an atomic ratio of both metals) is added at a certain point during a period of from a degree of esterification of 91% to the completion of the precondensation reaction; and 0.001-2.0wt% inert substance of an averge particle diameter of 0.01-5.0mu is added simultaneously with or after the addition of the alkali metal compounds. It is possible to obtain a polyester having excellent particle dispersibility and improved electrostatic cohesion.
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