| 摘要 |
PROBLEM TO BE SOLVED: To obtain a vinyl acetate polymer suppressing the generation (deposition) of scale on the inner wall of a reactor in polymerization by reacting vinyl acetate monomer, or the like, in a solvent in the presence of two kinds of polymerization catalysts having different half-life periods. SOLUTION: The objective polymer is produced by reacting (A) vinyl acetate monomer and (B) optionally other monomers in the presence of (C) 0.001-0.2 pt.wt. (based on 100 pts.wt. of the component A) of two kinds of polymerization catalysts having different half-life periods [measured in toluene (azo compound), benzene, or the like, at 60 deg.C] in (D) 1-80 pts.wt. (based on 100 pts.wt. of the component A) of a solvent (e.g. methanol). The component C is selected to satisfy the half-life period ratio (n/m) of preferably >=10, more preferably >=30, especially preferably >=50 wherein (n) is the half-life period of the polymerization catalyst having longer half-life period and (m) is the half-life period of the polymerization catalyst having shorter half-life period. The component C is t-butyl peroxypivalate, acetyl peroxide, or the like.
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