| 摘要 |
The invention relates to a process for preparing vinyl chloride polymers by suspension polymerization in a polymerization reactor of vinyl chloride, optionally in combination with at most 30% (wt) of one or more monomers copolymerizable therewith, with monomer-soluble, radical-forming initiators and optionally in the presence of primary suspending agents. The improvement comprises the addition of an aqueous dispersion of at least one polyvinyl ester with a degree of solvolysis in respect of the dry substance lower than 70 moles % to the polymerization reactor before or during said polymerization, which polyvinyl ester is chosen from the polymeric vinyl esters of aliphatic and/or aromatic carboxylic acids, the amount of the aqueous dispersion supplied being such that after this addition the reaction mixture contains 0.01-0.5 part by weight of the polyvinyl ester per 100 parts by weight of the starting monomer.
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