| 摘要 |
1289194 Preparation of polyvinyl alcohols; vinyl ester copolymers BORDEN Inc 7 July 1970 32968/70 Heading C3P Polyvinyl alcohols are produced in a process which comprises suspension polymerizing a vinyl ester in the presence of 0À1 to 2À5% by weight, based on the vinyl ester, of a conditioning agent which is a mono- or di-C 1-8 alkyl ester of itaconic or fumaric acid or a mixture thereof, and hydrolysing the resultant polyvinyl ester in a high solids content solution to at least 60%, and drying the resultant polyvinyl alcohol product. Vinyl esters specified are vinyl formate, vinyl acetate, vinyl propionate and vinyl butyrate. Conditioning agents specified are dimethyl itaconate, dibutyl itaconate, diethyl fumarate, dihexyl fumarate, di-2-ethyl hexyl itaconate, monomethyl fumarate, monoethyl itaconate and monohexyl itaconate. Solvents in which the polyvinyl ester may be hydrolysed are alkanols such as methanol, or methanol/methyl acetate mixtures or methanol/hexane mixtures. Alkali or acid hydrolysing agents may be used. In the examples polyvinyl acetate is produced in the presence of the above conditioning monomers and hydrolysed in methanol with NaOH. Chain transfer agents such as perchloroethylene and acetaldehyde may be used in the polymerization. |
