PREPARATION OF AQUEOUS POLYMER DISPERSION, POLYMER DISPERSION PREPARED THEREBY, USE THEREOF, AND SOLID DRUG DOSAGE FORM PREPARED THEREWITH

摘要

PROBLEM TO BE SOLVED: To obtain a polymer dispersion having a low monomer content and excellent storage stability by adjusting the pH of a starting aqueous dispersion by adding at least two basic reagents thereto in a plurality of stages in the course of polymerizing a free-radical-polymerizable ethylenically unsaturated monomer in an aqueous system in the presence of a polymerization initiator. SOLUTION: At least one free-radical-polymerizable ethylenically unsaturated monomer is polymerized in the presence of an acidic polymerization initiator in an aqueous system whose pH has been adjusted at a constant value in the range of 1-7.5 by the addition of a reagent 1 being a salt of an acid selected from the group consisting of carbonic acid, boric acid, acetic acid, citric acid, and phosphoric acid. After the polymerization initiator is consumed, the polymerization is continued in the presence of a redox catalyst, and reagent 1 is further added to the aqueous dispersion to buffer it. The aqueous dispersion is adjusted to a pH of 6-10 by the addition of a reagent 2 being a base selected from the group consisting of an alkali (alkaline earth) metal hydroxide, ammonia, and a primary to tertiary amine to obtain an aqueous polymer dispersion having a residual monomer content of 100 ppm or below.