PRODUCTION OF CARBOXYL-MODIFIED BUTADIENE-BASED COPOLYMER LATEX

PURPOSE:To produce a copolymer latex without remarkable generation of gels under an excellent emulsion polymerization stability by polymerizing raw materials composed of butadiene, an ethylenebased unsaturated carboxylic acid and copolymerizable monomers according to a specified two-stage polymerization method. CONSTITUTION:In production of the copolymer latex composed of (A) 10 to 80 pts.wt. butadiene, (B) 0.3 to 10 pts.wt. ethylene-based unsaturated carboxylic acid, (C) 10 to 89.7 pts.wt. other monomers copolymerizable therewith, 50 to 90wt.% of the whole monomers is initially polymerized at 40 to 60 deg.C. The remainder monomers corresponding to 10 to 50wt.% of the whole monomers are then added thereto at a point of time of >=60wt.% conversion and polymerized at 60 to 110 deg.C. Acrylic acid, maleic acid, etc., is used as the component (B) and methyl methacrylate, styrene, etc., can be used as the component (C). In addition, the solid matter content of the objective copolymer latex is preferably 45 to 55wt.%.