PURPOSE: To prepare an aromatic polyester composed of specific constituent unit, in powdery form, by reversing the rotation of the stirring blades of a vertical polymerizer during the polymerization, thereby changing the shear force applied to the polymer.
CONSTITUTION: A powdery aromatic polyester consisting of the constituent units of formula I, formula II and formula III (X is hydrocarbon group, O, SO2, S, or CO; m is 0 or 1; n is 0 or 1; the substituent groups of the aromatic ring are para- or meta-positions each other) wherein the ratio of the component I to the component II is 1:0W1:10, and that of the component II to the component III is 9:10W10:9, can be prepared using a vertical polymerizer furnished with stirring blades, by starting the polymerization rotating the stirring blades horizontally to a direction, and when the reaction system becomes viscous by the progress of polymerization, reversing the rotation of the blades, and repeating the reversion at regular intervals, thereby changing the shearing force applied to said polymer.
SUGIMOTO HIROAKI
HANATA MAKOTO
WATANABE KEIICHIROU
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