| 摘要 |
A modified polyvinyl alcohol is prepared by subjecting a copolymer of a vinyl ester of a saturated carboxylic acid and an olefinically-unsaturated phosphonic acid dialkyl ester to alcoholysis with methanol and a mixture of methanol and methyl acetate, in the presence of 0 to 15 % water (calculated on the weight of copolymer) at 15 to 90 DEG C. until at least 80% of the ester groups are converted into vinyl alcohol groups. More than one ester may be present in the copolymer and the formate, propionate, butyrate, stearate and acetate are specified while other comonomers e.g. vinyl chloride, ethylene, isobutylene, and acrylic, methacrylic, maleic and fumaric esters. The phosphoric acid esters may be diesters of ethene-, propene-, or allyl-phosphonic acid. An alcoholysis catalyst e.g. sodium hydroxide, and alkali metal alcoholates or hydrochloric, perchloric, sulphuric, trichloroacetic and dodecyl benzenesulphonic acid may preferably be present. |
