Aqueous coating composition and preparation thereof

1. A process for the preparation of a thixotropic aqueous coating composition

comprising the steps of:

i) providing an aqueous binder system comprising a dispersion of a polymer binder and a

carbonyl-hydrazide crosslinking system; and

ii) reacting in the aqueous binder system an ether amine with a tris(isocyanate) isocyanurate to form a polyurea sag control agent.

2. The process of claim 1 wherein the polymer binder comprises at least one of a carbonyl functional group and a hydrazide functional group, and optionally the aqueous binder system comprises a crosslinker having at least one of a carbonyl functional group and a hydrazide functional group for reaction with the functional groups of the polymer binder to give crosslinking.

3. The process of claim 1 wherein the ether amine is selected from a group consisting of (cyclo)alkoxy(cyclo)alkyl monoamines, mono(cyclo)alkoxy arene amines, poly(cyclo)alkoxy arene amines, areneoxy(cyclo)alkoxy amines, aryloxy(cyclo)alkyl amines, areneoxyarene amines, and aryloxyaryl amines.

4. The process of claim 1 wherein the tris(isocyanate) isocyanurate has the chemical formula of trimeric derivatives of one or more diisocyanates containing 5-14 carbon atoms.

5. The process of claim 4 , wherein the tris(isocyanate) isocyanurate has the chemical formula of the trimeric derivative of hexamethylene diisocyanate.

6. The process of claim 1 wherein the tris(isocyanate) isocyanurate has the

general formula:

wherein R is alkyl.

7. The process of claim 1 wherein the tris(isocyanate) isocyanurate comprises hydrophilic groups.

8. The process of claim 1 wherein the reaction of the ether amine with the tris(isocyanate) isocyanurate is carried out in the range of 5 to 80° C.

9. The process of claim 1 wherein the aqueous binder system comprises a polymer binder having carbonyl functional groups and a crosslinker having hydrazide functional groups.

10. The process of claim 1 wherein the polymer binder has a number average molecular weight in the range of 500 and 250000.

11. The process of claim 1 , wherein the polymeric binder has a number average molecular weight in the range of 2000 to 20000.

12. An aqueous coating composition obtained by the process of claim 1 , comprising:

a) an aqueous binder system comprising a dispersion of a polymer binder and a carbonyl and hydrazide crosslinking system;

b) a polyurea sag control agent; and

c) water;

wherein the polyurea sag control agent is a polyurea adduct of an ether amine and a tris(isocyanate) isocyanurate.

13. The aqueous coating composition according to claim 12 comprising 0.01% to

30% by weight of the polyurea sag control agent.

14. The aqueous coating composition according to claim 12 , comprising 0.15% to 3% by weight of the polyurea sag control agent.

15. The aqueous coating composition according to claim 12 , wherein the coating composition is suitable for implementation in at least one of a paint formulation and a wood stain formulation.

16. A paint formulation comprising an aqueous coating composition comprising:

a) an aqueous binder system comprising a dispersion of a polymer binder and a carbonyl and hydrazide crosslinking system;

b) a polyurea sag control agent that is a polyurea adduct of an ether amine and

a tris(isocyanate) isocyanurate;

c) water;

d) a pigment; and

e) optionally at least one of coating additives and organic solvents.

17. The process of claim 6 wherein the tris(isocyanate) isocyanurate has the chemical formula of trimeric derivatives of one or more diisocyanates selected from: methylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, cyclohexyl-1,4-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, dicyclohexyldimethylmethane-4,4′-diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane-4,4′-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate (isophorone diisocyanate).