Water-soluble copolymers useful in drilling fluids

Abstract

The water-soluble copolymer comprises 5-90% by weight of groups of the formula ##STR1## in which R.sup.1 is hydrogen or methyl, R.sup.2 is C.sub.2 -C.sub.10 -alkylene, and Me is ammonium or an alkali metal, 5-90% by weight of groups of the formula --CH.dbd.CH--CH.sub.2 --N.sup.+ R.sup.3 R.sup.4 --CH.sub.2 --CH.dbd.CH-- X.sup.- II in which X is a halogen, R.sup.3 and R.sup.4, independently of one another, are C.sub.1 -C.sub.6 -alkyl, 0-60% by weight of groups of the formula ##STR2## in which R.sup.5 and R.sup.6 together are a propylene group which with inclusion of the radical ##STR3## forms a pyrrolidone radical, and 0-30% by weight of groups of the formula --CHR.sup.7 --CHR.sup.8 -- IV in which R.sup.7 is hydrogen or methyl and R.sup.8 is CONH.sub.2, CON(CH.sub.3).sub.2, cyano, SO.sub.3 H, SO.sub.3 Me, C.sub.6 H.sub.4 SO.sub.3 H, C.sub.6 H.sub.4 SO.sub.3 Me, CH.sub.2 SO.sub.3 H, CH.sub.2 SO.sub.3 Me, COOH, COOMe, or carboxy-C.sub.1 -C.sub.15 --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.

Dependencies are inferred from the claim text.