| 摘要 |
<p>The invention provides an improved method for the suspension polymerization of vinyl chloride to give a polyvinyl chloride resin having excellent properties such as high bulk density, small number of fish-eyes, rapid plasticizer absorption and easy monomer releasability with a decreased amount of polymer scale deposition on the reactor walls. The inventive method characteristically comprises the successive steps of: introducing water as the suspension medium at an elevated temperature of 40 DEG C or higher, introducing the monomer under agitation to be dispersed into monomer droplets, introducing a partially saponified polyvinyl alcohol, which satisfies several specific physical and chemical requirements, in the form of an aqueous solution and, within 3 minutes thereafter, introducing a monomer-dsoluble polymerization initiator. By this means, the undesirable adsorption of the suspending agent on to the surface of the monomer droplets can be minimized so as to exhibit the suspending effect with a small amount of the suspending agent without being adsorbed on the monomer droplets.</p> |
