| 摘要 |
1,133,867. Preparation of vinyl acetate copolymer emulsions. CELANESE CORP. 26 May, 1966 [4 June, 1965], No. 23553/66. Heading C3P. Vinyl acetate copolymer emulsions - are obtained by initially polymerizing vinyl acetate with minor amounts of one or more ethylenically unsaturated comonomers in an aqueous medium containing a surfactant comprising a major proportion of a polyether having at least four ether linkages, starch or a water-soluble cellulose derivative as protective colloid and a water-soluble free-radical polymerization catalyst, and continuing the polymerization by introducing additional monomer and catalyst until an emulsion containing more than 55% of polymer is formed, an additional quantity of surfactant being added before the last addition of monomer, and a further quantity of catalyst alone is finally added and the catalyst-containing emulsion is maintained at an elevated temperature until a reduction in viscosity of the emulsion is achieved. The emulsions may be incorporated in paint compositions. In the examples vinyl acetate, ethyl acrylate and di-(2- ethylhexyl)-maleate or dioctyl maleate are copolymerized using a surfactant mixture comprising nonylphenylpolyethylene glycol ether and nonylphenoxypoly (ethyleneoxy) ethanol, hydroxyethyl cellulose and a defoamer blend, the initiators being potassium persulphate, hydrogen peroxide, sodium chlorate, sodium persulphate and ammonium persulphate. In Example VI a composition is prepared comprising a vinyl acetate-ethyl acrylate-dioctyl maleate copolymer emulsion, methyl cellulose, 2,2,4 - trimethylpentanediol - monoisobutyrate, potassium tripolyphosphate, TiO 2 , CaCO 3 , water, propylene glycol, and phenyl mercuric acetate. |
