PURPOSE: To obtain a highly water-resistant polymer latex of large particle size, by carrying out an emulsion polymerization of monomer(s) in the presence of a specific amount of an inorganic electrolyte by incorporating water, etc. at the initiation, and by further adding a required amount of water when reached a point of a specific conversion before continuing the polymerization.
CONSTITUTION: An emulsion polymerization is carried out, pref. at 40W90°C, by adding to (A) 100pts.wt. of monomer(s) (pref. consisting mainly of styrene and/ or butadiene) (B) 0.1W1.0pt.wt. of an inorganic electrolyte (e.g., sodium chloride) and, at the initiation, (C) 10W50pts.wt. of water, (D) an initiator (e.g., potassium persulfate), an emulsifier (e.g., beef tallow-based fatty acid potassium salt), etc. When reached a point of a conversion of 5%, a required amount (pref. 20W 250pts.wt.) of water is incorporated in the system to continue the polymerization, thus obtaining the objective latex.
TAGAMI EIJIROU
KASAI KIYOSHI
MAKAWA OSAMU
