| 摘要 |
PROBLEM TO BE SOLVED: To provide a latex type paint composition that can form paint layers showing excellent weather resistance, in other words, good resistance to water, gloss retention, crack resistance, blister resistance and yellowing resistance as well as high resistance to solvents and the like. SOLUTION: In the first step polymerization, a vinyl monomer bearing a cycloalkyl group (a) and, when necessary, a vinyl monomer bearing no cycloalkyl group (b-A) are emulsion-polymerized in an aqueous system by using a polymeric peroxide as a polymerization initiator until the degradation rate of the peroxy bonds becomes in the range of from 20 to 80% to form a polymer bearing peroxy bonds in the molecular chains. In the following second step polymerization, a vinyl monomer bearing no cycloalkyl group (b-B) is added to the product of the first step polymerization and the emulsion polymerization is carried out at the temperature at which the peroxy bonds of the remaining polymerization initiator can decompose whereby the objective latex type paint composition including block copolymer is prepared.
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