| 摘要 |
1408361 Vinyl ester copolymer powders HOECHST AG 4 May 1973 [5 May 1972] 21355/73 Heading C3P A water dispersible powdered copolymer is prepared by copolymerizing a vinyl ester and an acrylamide of the formula in which X is H or -CH 3 , Y is H or -CH 2 OZ, and Z is H, alkyl or acyl, each having up to 4 carbon atoms, in an emulsifier-free aqueous dispersion, and subsequently drying the dispersion to form a powder. Ethylene may be additionally copolymerized. Drying may be effected by freeze-drying, drum drying or fluidized bed spray granulation. The latter method may utilize air or nitrogen as the drying gas, which may be passed into the drying tower at a temperature of 90-110‹ C. A filler may be added before, during, or after drying. Specified monomers are: vinyl acetate, -laurate, -stearate, -butyrate and -propionate; and acrylamide, methacrylamide, N-methylol (meth) acrylamide, and (meth)acrylamide-N-methylolmethyl ether. In the example, vinyl acetate, acrylamide and ethylene are copolymerized in the absence of emulsifier, and spray dried. |
