Process for producing an aqueous liquid dispersion of polymers

Abstract

One or more polymeric peroxides and vinyl type monomers containing vinyl type unsaturated carboxylic acid monomers are subjected to copolymerization, followed by neutralizing more than 50 mole percent of the carboxylic acid groups in the resultant product, thereby obtaining copolymers having peroxy bonds therein which are soluble in water or a mixed solution of water and anaqueous organic solvent (represented as solvent D in this disclosure). The said copolymers having peroxy bonds therein and vinyl type monomers are subjected to block-copolymerization, in the presence of solvent D, whereby the said copolymers having peroxy bonds in the molecule thereof are cleavaged at the peroxy bonds thereof, obtaining block copolymers with high efficiency. Combining order of the vinyl type monomers employed in the first copolymerization and the ones employed in the second copolymerization may be reversely employed. The neutralization of the carboxylic acid groups may be carried out after the second block copolymerization. The said block copolymer consists of polymer parts which are soluble in solvent D and other polymer parts which are insoluble in solvent D. When it is mixed with solvent D, the polymer parts which are soluble in solvent D are elongated and the other polymer parts which are insoluble in solvent D are coagulated to become particles in solvent D, with the result that the resultant mixture of the block copolymer and the solvent, becomes to be in the state of dispersion in the solvent.