| 摘要 |
An improvement is proposed for the suspension polymerization of vinyl chloride to give a resin powder having an increased bulk density and containing a decreased amount of fish eyes. The improvement can be obtained by using, as the suspending agent, three kinds of water-soluble polymers in combination, of which the first two, which are dissolved in the aqueous suspension medium already at the start of the polymerization eaction, are a specific partially saponified polyvinyl alcohol and a specific hydroxypropyl methyl cellulose and the third polymer, which is introduced into the polymerization mixture ata specified moment during proceeding of the polymerization reacion, is also a specific partially saponified polyvinyl alcohol different from the first partially saponified polyvinyl alcohol, each polymer being added in a specified amount.
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