SAPONIFICATION PRODUCT OF VINYL ESTER/ETHYLENICALLY UNSATURATED CARBOXYLIC ACID ESTER COPOLYMER AND PROCESS FOR PRODUCING THE SAME

摘要

The present invention provides a saponification product of a vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer having superior tolerance of the aqueous thickening liquid against mechanical shear. More specifically, the present invention provides a saponification product of a vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer having the superior tolerance, by polymerizing a mixture where the molar ratio of the vinyl ester/ethylenically unsaturated carboxylic acid ester is from 8/2 to 3/7, and saponifying the obtained copolymer in a mixed solvent where the mass composition ratio of an aqueous organic solvent/water mixture solvent is from 3/7 to 8/2.

主权项

1. A saponification product of a vinyl ester/ethylenically unsaturated carboxylic acid ester copolymer having a viscosity retention of 70% or higher when a 1 mass %-aqueous thickening liquid is stirred for 20 minutes at 5 m/s of blade tip peripheral velocity.