| 摘要 |
In a process for the manufacture of watersoluble polyvinyl alcohols of which aqueous solutions of 4% strength have a viscosity higher than 100 c.p. at 20 DEG C., a vinyl ester of a fatty acid containing 2 to 8 carbon atoms is copolymerized with an ether of vinyl alcohol and an aliphatic alcohol containing between 6 and 18 carbon atoms wherein the weight of the ester is at least 51% calculated on the total weight of the monomer, in the presence of a peroxide as catalyst, and the copolymer so obtained is completely or partially hydrolysed to yield a water-soluble product. Esters specified are vinyl acetate and propionate. As ethers are specified the vinyl ether of montanol and vinyl octyl, dodecyl and octadecyl ethers. Copolymerzation can be effected in suspension, emulsion or solution. As catalysts dibenzoyl, diacetyl or dilauryl peroxides can be used. Acid or alkaline hydrolysis can be used. In one example the ammonium salt of a copolymer of styrene with maleic anhydride is present in the polymerization mixture. The products are suitable for thickening dyestuff pastes or glues or can be converted to polyvinyl acetals. |
