Byk-chemie Gmbh

Holger Heilmann

Karlheinz Haubennestel

Stefan Moessmer

Karl-Heinz Haubennestel

Baerbel Gertzen

Sascha Huebers

Andreas Diez

The invention relates to a polymeric urea-urethane obtainable by first reacting a diisocyanate with a polyol to form a doubly NCO-terminated urethane prepolymer. Further reaction is subsequently carried out with a mixture of a primary monoamine and a primary diamine. After the second reaction the polymeric urea-urethane present is substantially free of isocyanate and of the monoamine and diamine used. It can be used as an agent for controlling the rheology of liquid polymers or polymer solutions.

Polymeric urea-urethane rheology control agents and a process for their preparation

Hydroxyfunctional carboxamide compounds of formula I ##STR1## are included in thixotropic formulations containing highly disperse silica as a thickening or thixotroping component in order to activate the silica or enhance its effect, to amerliorate any tendency of the silica to settle and/or to prevent weakening of the thixotroping effect of SiO.sub.2 in formulations which themselves form relatively strong hydrogen bonds. The compounds of formula I may be added to silica-containing thixotropic liquid formulations to improve the thixotropy, or highly disperse silica may be coated with such compounds for later incorporation into liquid systems to render them thixotropic.

Thixotropic formulations, use of polycarboxylic acid amides to produce

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Wesel, Germany

Holger Heilmann