| 摘要 |
Ethylenically unsaturated compounds are polymerized in aqueous medium in the presence or absence of a dispersing agent and in the presence of a catalyst system comprising a haloformic acid ester of formula RO.CO.X where X is chlorine or bromine and R is alkyl, aryl, cycloalkyl, aralkyl, alkaryl or a heterocyclic radical, an inorganic peracid or an alkali metal or alkaline earth metal salt thereof, and optionally an acid binding agent. Reducing agents such as sodium sulphite, bisulphite, sulphoxylate or chlorite, and compounds of iron, cobalt, copper and silver may also be present. Specified unsaturated compounds are styrene, ethylene, propylene, butylene, butadiene, methyl butadiene, chloroprene, acrylic and methacrylic acids, esters, amides and nitriles, vinyl esters, halogen substituted ethylene, vinyl ketones, acrolein, vinyl heterocyclic compounds, vinylidene cyanide, vinyl phosphonic acid and esters thereof. Specified dispersing agents are alkali metal alkyl sulphates and sulphonates, quaternary ammonium compounds, glycerol esters of long chain fatty acids, polyvinyl alcohol, gelatin and methyl cellulose. Monomers such as styrene are preferably polymerized in an acid medium. Many suitable haloformic acid esters are specified. The peracid may be permonosulphuric, perpercarbonic or perphosphoric acid, and the acid binding agent may be alkali metal bicarbonates or phosphates, pyridine or quinoline. Examples describe the polymerization of vinyl chloride in aqueous media containing alkyl sulphonate, potassium permonosulphate, sodium bicarbonate and (2) methyl chloroformate, (3) ethyl chloroformate, and (4) isopropyl chloroformate; of vinyl chloride and difluoro vinylidene chloride in aqueous medium containing alkyl sulphonate, potassium permonosulphate, sodium bicarbonate and (5) ethyl chloroformate; and of vinyl acetate in aqueous media containing potassium permonosulphate, sodium bicarbonate, alkyl sulphonate, sodium vinyl sulphonate, and (6) ethyl chloroformate, or (7) methyl chloroformate; and vinyl acetate in aqueous medium containing polyvinyl alcohol, potassium permonosulphate, sodium bicarbonate, and (8) ethyl chloroformate. Specification 1,009,303 is referred to. |
