| 摘要 |
PURPOSE:To obtain a polyester freed of coarse particles and containing uniform fine particles, by adding a slurry formed by uniformly dispersing fine CaCO3 particles in a glycol in the presence of fine MgCO3 particles to the production system of the polyester. CONSTITUTION:A glycol slyrry is produced by uniformly and finely dispersing fine calcium carbonate particles of an average-particle diameter <=5mum in a glycol (e.g., ethylene glycol) in the presence of magnesium carbonate. This slurry is added to the production system in an arbitrary stage before completion of the polycondensation in producing a polyester by the esterification and polycondensation of an aromatic dicarboxylic acid (esterifiable derivative), e.g., terephthalic acid, and a glycol. Because the obtained polyester contains a number of uniformly dispersed fine calcium carbonate particles, a film obtained by molding it can show excellent surface smoothness, etc.
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