| 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. |
