| 摘要 |
PURPOSE:To obtain the titled resin of a high bulk density and a low fish eye content at an excellent production rate, by polymerizing a vinyl chloride monomer by controlling the amount of water so that the water/monomer ratios at the time of initial charge and at the end of the polymerization may fall within specified ranges, respectively. CONSTITUTION:A vinyl chloride monomer or a mixture thereof with other copolymerizable monomers and water are placed in a polymerization reaction vessel equipped with a reflux condenser in its vapor phase or outside it so that the water/monomer ratio may be 0.8-1.0; a polymerization initiator (e.g., di-2-ethylhexyl peroxydicarbonate) and a suspending agent (e.g., partially saponified PVA) are added to the vessel; the polymerization is started at 40-75 deg.C; this suspension polymerization is continued while water in an amount not exceeding the volume shrinkage accompanying the progress of polymerization is added continuously or intermittently during the course of polymerization so that the water/monomer ratio at the end of polymerization may fall within the range of 1.0-1.4. In this way, the titled resin is obtained.
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