| 摘要 |
Aqueous dispersions of vinyl ester polymers are prepared by a process which comprises polymerizing a vinyl ester of an aliphatic carboxylic acid and/or vinyl benzoate in the presence of an emulsifier mixture, said mixture consisting of 1 to 20 parts by weight of a graft polymer of a vinyl ester on a poly-1,2-alkylene glycol and 1 to 15 parts by weight of a polyvinyl alcohol, modified polyvinyl alcohol or vinyl alcohol modified polyalkylene glycol, a 10% aqueous solution of which has a turbidity point of at least 90 DEG C., said parts being based on 100 parts of the monomer. Specified vinyl esters are vinyl acetate, propionate, butyrate, valerate, caproate and stearate, which may be copolymerized with esters of unsaturated acids, e.g. acrylic, methacrylic, maleic, fumaric and itaconic esters of alkanols containing 1 to 8 carbon atoms. The emulsifiers may be graft polymers of vinyl acetate on polyethylene glycol, and partially or completely hydrolysed polyvinyl acetate, oxyethylated polyvinyl alcohols or hydrolysed vinyl acetate/polyethylene glycol graft polymers. Polymerization may be effected in the presence of water soluble peroxides, e.g. hydrogen peroxide and alkali metal persulphates and perborates, optionally together with reducing agents and activators, e.g. sodium formaldehyde sulphoxylate, ferrous ammonium sulphate and cobaltous acetate. The dispersions may be compounded with plasticizers, coalescing agents and other conventional ingredients to give emulsion paints. Examples describe the polymerization of (1-7) vinyl acetate in aqueous dispersion in the presence of polyvinyl alcohol, a vinyl acetate/polyethylene glycol graft polymer and hydrogen peroxide; and the copolymerization of (10) vinyl acetate and dibutyl maleate in the presence of polyvinyl alcohol, a vinyl acetate/polyethylene glycol graft polymer, sodium dodecyl sulphate and potassium persulphate, and of (II) vinyl acetate and butyl acrylate in the presence of polyvinyl alcohol, a vinyl acetate/polyethylene glycol graft polymer, a nonyl phenol/ethylene oxide condensate and ammonium persulphate.- Specifications 922,457 922,458, 922,459, 975,245, 981,501 and 983,587 are referred to. |
