| 摘要 |
PURPOSE:To obtain a polyester suitable for magnetic tapes to be used in computers with outstanding slipperiness, wear resistance, etc. and few coarse asperities, by adding inert particles of specific size in the form of a slurry to the reaction system to carry out polymerization. CONSTITUTION:First, a slurry is prepared by adding (A) inert particles (e.g., titanium dioxide, talc) with an average size determined by observation with a scanning electron microscope 0.05-5.0mum and area rate to circumscribed circle of equation >=60% to (B) ethylene glycol followed by adding pref. 0.04-20wt.% based on the component A, of phosphoric acid and phosphorous acid alkali metal salts to the system to effect fine dispersion using e.g. a high- pressure type homogenizer. The resulting slurry is added to a reaction system comprising (C) a dicarboxylic acid component (e.g., terephthalic acid) and (D) a glycol (e.g., ethylene glycol), pref. prior to a point when the intrinsic viscosity of the reaction system reaches 0.2, thus obtaining the objective polyester.
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