| 摘要 |
PURPOSE:To obtain PVC having a large average particle diameter, a high porosity and excellent absorption of a plasticizer and an excellent rate of dissolution and scarcely forming fish eyes, by suspension-polymerizing vinyl chloride in the presence of specified two kinds of PVA's. CONSTITUTION:To an aqueous medium vinyl chloride and 0.01-5wt% PVA, as a polymerization aid, having an average degree of polymerization <=500 and a degree of saponification >=60mol% are added, and the suspension polymerization of this mixture is started at 40-70 deg.C in the presence of an oil-soluble radical polymerization catalyst (e.g., benzoyl peroxide). When the polymer conversion reaches 5-40%, 0.02-1wt%, based on the vinyl chloride, PVA having an average degree of polymerization >=700 and a degree of polymerization >=75mol%, and the polymerization is brought to completion. EFFECT:It is possible to obtain PVC having an average particle diameter of about 200mu and a particle diameter distribution in the range of 40-100 mesh.
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