| 摘要 |
In the suspension polymerization of vinyl chloride the monomer is homogenized in an aqueous dispersion also containing a suspension agent and catalyst, polymerization is initiated with agitation, agitation is stopped before polymerization reaches 15% and recommenced on reaching 20-40% and then maintained until polymerization is complete. A comonomer may be present, in one example vinyl acetate is added, also mentioned are vinyl ethers, (meth) acrylic acids and their alkyl esters, maleic and fumaric acids, their anhydrides and alkyl esters, vinylidene halide, other vinyl halides, olefins and vinyl aromatics. The suspending agent is polyvinylalcohol, methyl cellulose, polyvinylpyrrolidone, polyvinylmethylether, maleic anhydride-vinyl acetate copolymer, starch, gelatin, gum tragacanth or gum arabic. Specified catalysts are lauroyl peroxide, benzoyl peroxide, 2,4 - dichlorobenzoyl peroxide, t-butyl peroxypivalate, diisopropylperoxydicarbonate and azobisisobutyronitrile. Also present may be a solid or a surface-active agent to assist suspension or an alcohol, chlorohydrocarbon or hydrocarbon solvent to adjust the molecular weight. |
