Hoechst Aktiengesellschaft

Clariant International Ltd

Clariant Finance (bvi) Limited

Jürgen Tonhauser

Ulrich Riegel

Fritz Engelhardt

Martin Hille

Christoph Kayser

Dirk Fischer

Karl Heinz Heier

Heinz Wittkus

Gernold Botthof

Claudia Diemel

Michael Schäfer

This invention relates to water-soluble or water-swellable polymers, containing a) 25-35 mol. % of one or more recurrent structural units of formula (1), where Rand Rrepresent hydrogen, methyl or ethyl, A represents a linear or branched C-C-alkylene, and Qstands for NH, Li, Na, K, &#xbd; Ca, &#xbd; Mg, &#xbd; Zn, &#x2153; Al, or organic ammonium ions of the formula [HNRRR], b) 3 to 8 mol. % of one or more recurrent structural units of formula (2), where Rrepresents hydrogen, methyl, or ethyl, Xstands for H, NH, Li, Na, K, &#xbd; Ca, &#xbd; Mg, &#xbd; Zn, &#x2153; Al, or organic ammonium ions of the formula [HNRRR], B is a linear or branched alkylene group with 1 to 6 carbon atoms, and n is a whole number between 0 and 5, and c) 57 to 72 mol. % of a (meth)acrylamide.

Water-soluble or water-swellable polymers as water loss reducers in cement slurries

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

Water-soluble copolymers useful in drilling fluids

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Oestrich-Winkel, Germany

Jürgen Tonhauser