PROCESS FOR PRODUCING STABLE WATER-IN-OIL EMULSIONS OF HYDROLYSED POLYMERS OF N-VINYL AMIDES AND THEIR USE

摘要

A process for the production of stable water-in-oil emulsions of hydrolysed polymers of n-vinyl amide of formula (I) in which R, R<1> = H or C1-C6 alkyl, by the polymerisation of compounds of formula (I) alone or mixed with other ethylenically unsaturated monomers in the presence of polymerisation initiators and emulsifiers in the form of water-in-oil emulsions to form water-in-oil polymer emulsions followed by the hydrolysis of the polymers in the form of the water-in-oil polymer emulsions in the presence of acids or bases and 1 to 30 wt % in relation to the polymers of emulsifiers, in which the emulsifiers used are mixtures of (a) 5 to 95 wt % of a block or graft copolymer of the structure (A-B)m, (A)nB or (B)nA in which A is a hydrophobic homo or copolymer with a degree of polymerisation of at least 3, B is a hydrophilic homo or copolymer with a degree of polymerisation of at least 3, m >/= 1 and n >/= 2, and (b) 5 to 95 wt % of another water-in-oil emulsifier with a molar mass of under 1000 g/mol. The polymer emulsions thus obtained may be used as retention and flocculation agents in paper production, to purify waste water and sludges in purification plants, as a dispersant and protective colloid for drilling muds and as a cement additive.