Branched polyurethanes, formulations comprising them, and their use for thickening aqueous systems

A branched polyurethane obtainable by reacting

• A) one or more aliphatic and/or aromatic isocyanates having a functionality of at least three with
• B) from 90.0 to 99.8 eq. % of one or more polyethers of structure
• RO(SO)w(BO)x(PO)y(EO)zH
• and
• C) from 0.2 to 10.0 eq. % of at least one of the compounds from the following group:
• polyethers of structure
• HO(SO)w′(BO)x′(PO)y′(EO)z′H
• b. polyether polydimethylsiloxane diols of structure
• HO(SO)w′(BO)x′(PO)y′(EO)z′Z-PDMS-Z(EO)z′(PO)y′(BO)x′(SO)w′OH
• c. polyester polydimethylsiloxane diols of structure
• H—(OC5H10CO—)y′—Z-PDMS-Z—(CO—C5H10O—)y′-H
• d. polydimethylsiloxane diols of structure
• HO—Y-PDMS-Y—OH
• e. polydimethylsiloxane diamines of structure
• R′NH—Y-PDMS-Y—HNR′
• f. polyether diamines of structure
• R′HN—(PO)y′(EO)z′-X-(EO)z′(PO)y′-NHR′
• in which
• R is a hydrocarbon radical of 1 to 50 carbon atoms which is optionally substituted or functionalized,
• R′ is a hydrocarbon radical of 1 to 8 carbon atoms which is optionally substituted or functionalized,
• SO=styrene oxide,
• BO=butylene oxide,
• PO=propylene oxide,
• EO=ethylene oxide,
• PDMS=polydimethylsiloxane
• w=0 to 5,
• x=0 to 5,
• y=0 to 20,
• z=50 to 200,
• w′=0 to 5,
• x′=0to 5,
• y′=0to 10,
• z′=1 to 49,
• Z=—CnH2nO— or —CH2—CH2—O—O—CnH2nO—, where
• n=2to 12;
• X=—CnH2n— or —C6H4—, where
• n=2 to 12;
• Y=—CmH2m, in which
• m=1 to 8.