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

1. 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 about 90.0 to about 99.8 eq. % of one or more polyethers of structure

RO(SO)w(BO)x(PO)y(EO)zH

 and

C) from about 0.2 to about 10.0 eq. % of at least one of the compounds from the following group:

a. 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—(OC 5 H 10 CO-)y′-Z-PDMS-Z-(CO—C 5 H 10 O-)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 hydrogen or a hydrocarbon radical which is optionally substituted or functionalized,

R′ is hydrogen or a hydrocarbon radical 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′=0 to 5,

y′=0 to 10,

z′=1 to 49,

Z=—C n H 2n O— or —CH 2 —CH 2 O—C n H 2n O—, where n=2to 12;

X=—C n H 2n — or —C 6 H 4 —, where n=2 to 12;

Y=—C m H 2m , in which m=1 to 8.

2. 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—(OC 5 H 10 CO-)y′-Z-PDMS-Z-(CO—C 5 H 10 O-)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 hydrogen or a hydrocarbon radical of 1 to 50 carbon atoms which is optionally substituted or functionalized,

R′ is hydrogen or 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=—C n H 2n O— or —CH 2 —CH 2 —O—O—C n H 2n O—, where n=2to 12;

X=—C n H 2n — or —C 6 H 4 —, where n=2 to 12;

Y=—C m H 2m , in which m=1 to 8.

3. The polyurethane as claimed in claim 1 , wherein R is an unsubstituted or substituted hydrocarbon radical having from 8 to 22 carbon atoms.

4. The polyurethane as claimed in claim 1 , wherein R is an unsubstituted or substituted hydrocarbon radical having from 10 to 18 carbon atoms.

5. The polyurethane as claimed in claim 2 , wherein R is an unsubstituted or substituted hydrocarbon radical having from 16 to 18 carbon atoms.

6. The polyurethane as claimed in claim 2 , wherein the indices have the following values:

w=0 to 2,

x=0 to 3,

y=0 to 10,

z=50 to 200.

7. The polyurethane as claimed in claim 2 , wherein the indices have the following values:

w=0,

x=0,

y=0,

z=80 to 150.

8. The polyurethane as claimed in claim 2 , wherein the indices have the following values:

w′=0 to 2,

x′=0 to 2,

y′=0 to 10,

z′=5 to 30.

9. The polyurethane as claimed in claim 2 , wherein the index n in Z is from 2 to 6.

10. The polyurethane as claimed in claim 2 , wherein the index m in Y is from 3 to 6.

11. The polyurethane as claimed in claim 1 , wherein R′ is hydrogen or a methyl or ethyl group.

12. The polyurethane as claimed in claim 1 , wherein R′ is hydrogen.

13. The polyurethane as claimed in claim 1 , in which the aliphatic and/or aromatic isocyanates having a functionality of at least 3 is a derivative of hexamethylene diisocyanate or of tolylene diisocyanate or of isophorone diisocyanate.

14. The polyurethane as claimed in claim 1 , in which the aliphatic and/or aromatic isocyanates having a functionality of at least 3 is a derivative of isophorone diisocyanate.

15. A formulation comprising from about 10 to about 40 parts by weight of a polyurethane as claimed in claim 1 , from 0 to about 80 parts by weight of water, from 0 to about 30 parts by weight of cosolvent and from about 10 to about 80 parts by weight of emulsifier of the general structure

R″(SO)w″(BO)x″(PO)y″(EO)z″H,

where

R″ is an optionally substituted hydrocarbon radical

SO=styrene oxide,

BO=butylene oxide,

PO=propylene oxide,

EO=ethylene oxide,

w″=1 to 5,

x″=0 to 5,

y″=0 to 5,

z″=3 to 30.

16. A formulation comprising from 10 to 40 parts by weight of a polyurethane as claimed in claim 2 , from 0 to 80 parts by weight of water, from 0 to 30 parts by weight of cosolvent and from 10 to 80 parts by weight of emulsifier of the general structure

R″(SO)w″(BO)x″(PO)y″(EO)z″H,

where

R″ is an optionally substituted hydrocarbon radical

SO=styrene oxide,

BO=butylene oxide,

PO=propylene oxide,

EO=ethylene oxide,

w″=1 to 5,

x″=0 to 5,

y″=1 to 5,

z″=3 to 30.

17. The formulation as claimed in claim 16 , wherein the indices have the following values:

w″=1 to 3,

x″=0,

y″=0 to 2,

z″=5 to 30.

18. The formulation as claimed in claim 16 , wherein the radical R″ contains from 4 to 12 carbon atoms.

19. A method for thickening an aqueous system which comprises adding a thickening amount of a polyurethane according to claim 1 .

20. A method for thickening an aqueous coating system which comprises adding a thickening amount of a formulation according to claim 15 .

21. A method for thickening an aqueous, dispersion based coating system which comprises adding a thickening amount of a formulation according to claim 15 .

22. An aqueous system comprising, as a thickener, a polyurethane according to claim 1 .

23. An aqueous coating system comprising, as a thickener, a formulation according to claim 15 .

24. A paint or a printing ink which comprises a pigment and, as a thickener, a polyurethane according to claim 1 .

25. A paint or a printing ink which comprises a pigment and, as a thickener, a formulation according to claim 15 .