Aqueous pigmented coating composition with improved open time comprising crosslinkable oligomer(s) and dispersed polymer(s)

1. An aqueous coating composition with an improved open time comprising:

a) 1 to 35 wt % of a crosslinkable water-dispersible oligomer(s);

b) 4 to 50 wt % of a dispersed polymer(s);

c) 3 to 75 wt % of at least one pigment with an oil absorption number ≦25 g oil/100 g pigment;

d) 0 to 10 wt % of at least one Newtonian-like thickener;

e) 0 to 10 wt % of at least one thixotropic thickener;

f) 0 to 20 wt % of co-solvent;

g) 10 to 80 wt % of water;

where a)+b)+c)+d)+e)+f)+g)=100%; wherein

the weight ratio of a):b) is in the range of from 10:90 to 60:40; and wherein

d)+e)=0.1 to 10 wt % and impart a shear ratio to the composition which is in the range of from 1 to 20 at a shear rate of 10 s −1 and 1,000 s −1 , and wherein

the composition when drying to form a coating has a tack-free time of ≦24 hours.

2. An aqueous composition according to claim 1 wherein the crosslinkable oligomer(s) is a self-crosslinkable oligomer(s).

3. An aqueous composition according to claim 1 wherein the crosslinkable oligomer(s) is selected from a group consisting of polyurethane oligomer(s), vinyl oligomer(s), polyamide oligomer(s), polyether oligomer(s), polysiloxane oligomer(s), polyester oligomer(s), hyperbranched oligomer(s) and/or mixtures thereof.

4. An aqueous composition according to claim 1 wherein the crosslinkable oligomer(s) has an acid value in the range of from 0 to 80 mg KOH/g.

5. An aqueous composition according to claim 1 wherein the crosslinkable oligomer(s) has a measured weight average molecular weight in the range of from 1,000 to 100,000 Daltons.

6. An aqueous composition according to claim 1 wherein the crosslinkable oligomer(s) is less than 70% by weight soluble in water throughout a pH range of from 2 to 10.

7. An aqueous composition according to claim 1 wherein the crosslinkable oligomer(s) has a measured Tg in the range of from −120 to 250° C.

8. An aqueous composition according to claim 1 wherein the dispersed polymer(s) has a measured weight average molecular weight ≦110,000 Daltons.

9. An aqueous composition according to claim 1 wherein the dispersed polymer(s) has an average particle size in the range of from 25 to 1000 nm.

10. An aqueous composition according to claim 1 wherein the dispersed polymer(s) has a measured Tg in the range of from −50 to 300° C.

11. An aqueous composition according to claim 1 wherein the dispersed polymer(s) is a vinyl polymer.

12. An aqueous composition according to claim 11 wherein the dispersed vinyl polymer has 10 to 50 wt % of a soft part with a measured Tg in the range of from −30 to 20° C. and 50 to 90 wt % of a hard part with a measured Tg in the range of from 60 to 110° C.

13. An aqueous composition according to claim 11 wherein the dispersed vinyl polymer(s) comprises:

I. 15 to 80 wt % of styrene and/or α-methylstyrene;

II. 0 to 50 wt % of one or more of methyl (meth)acrylate, ethyl (meth)acrylate, cyclohexyl (meth)acrylate and n-butyl (meth)acrylate;

III. 0 to 7 wt % of a vinyl monomer(s) containing a carboxylic acid group(s);

IV. 0 to 10 wt % of a vinyl monomer(s) containing a non-ionic water-dispersing group(s);

V. 5 to 40 wt % of a vinyl monomer(s) other than as in I to IV, VI and VII;

VI. 0 to 5 wt % of a vinyl monomer(s) containing wet adhesion promoter or crosslinker groups (excluding any within the scope of III and VII); and

VII. 0 to 8 wt % of a polyethylenically unsaturated vinyl monomer, wherein I)+II) add up to at least 50% and I+II+III+IV+V+VI+VII add up to 100%.

14. An aqueous composition according to claim 1 wherein the pigment volume concentration is in the range of from 1 to 48 wt %.

15. An aqueous composition according to claim 1 wherein the pigment(s) has a water absorption number ≦40 cm 3 /100 g pigment.

16. An aqueous composition according to claim 1 wherein the composition comprises 0.1 to 10 wt % of d) the Newtonian-like thickener.

17. An aqueous composition according to claim 1 wherein the composition comprises 0.1 to 10 wt % of e) the thixotropic thickener.

18. An aqueous composition according to claim 1 wherein the ratio of Newtonian-like to thixotropic thickener is in the range of from 95:5 to 30:70.

19. An aqueous composition according to claim 1 wherein the co-solvent to water ratio is below 0.8.

20. An aqueous composition according to claim 1 wherein the improved open time is at least 3 minutes longer than a reference formulation which comprises similar amounts of components a), b), f) and g), a pigment with an oil absorption number >32 g oil/100 g pigment, and a pseudoplastic thickener.

21. An aqueous composition according to claim 1 wherein the open time is at least 9 minutes.

22. An aqueous composition according to claim 1 wherein said composition has an equilibrium viscosity ≦500 Pa·s, during the first 10 minutes of drying when measured using any shear rate in the range of from 0.01±0.005 to 900±5 s −1 and at 23+/−2° C.

23. A coating obtained from an aqueous composition according to claim 1 .

24. A method for coating a substrate using an aqueous composition according to claim 1 .

25. A substrate coated with an aqueous composition according to claim 1 .