Water-soluble copolymers useful in drilling fluids

摘要

The water-soluble copolymer comprises 5-90% by weight of groups of the formula <IMAGE> I in which R1 is hydrogen or methyl, R2 is C2-C10-alkylene, and Me is ammonium or an alkali metal, 5-90% by weight of groups of the formula -CH=CH-CH2-N+R3R4-CH2-CH=CH- X-II in which X is a halogen, R3 and R4, independently of one another, are C1-C6-alkyl, 0-60% by weight of groups of the formula <IMAGE> III in which R5 and R6 together are a propylene group which with inclusion of the radical <IMAGE> forms a pyrrolidone radical, and 0-30% by weight of groups of the formula -CHR7-CHR8-IV in which R7 is hydrogen or methyl and R8 is CONH2, CON(CH3)2, cyano, SO3H, SO3Me, C6H4SO3H, C6H4SO3Me, CH2SO3H, CH2SO3Me, COOH, COOMe, or carboxy-C1-C15-alkyl, and Me is an ammonium cation or an alkali metal cation, and the order of components I to IV can be as desired. The copolymer is used as water-binding additive for suspensions of solids, preferably for cement slurries, gypsum slurries, mortars, drilling muds or pigment suspensions, or as water-binding additive for aqueous salt solutions.