Aqueous vinyl polymer coating compositions

1. An aqueous coating composition comprising an ambient temperature self-crosslinkable water-dispersible vinyl oligomer(s) having a measured weight average molecular weight in the range of from 1,000 to 80,000 Daltons and dispersed vinyl polymer(s) and 0 to 25% of co-solvent by weight of the composition where the ratio of said self-crosslinkable vinyl oligomer(s) to the dispersed vinyl polymer(s) is in the range of from 90:10 to 10:90 and said dispersed vinyl polymer(s) has a measured weight average molecular weight ≧90,000 Daltons and wherein said composition when drying at ambient temperature crosslinks to form a coating that has the following properties:

i) an open time of at least 20 minutes at 23+/−2° C.;

ii) a wet edge time of at least 10 minutes at 23+/−2° C.;

iii) a tack-free time of ≦20 hours at 23+/−2° C.; and

iv) an equilibrium viscosity of ≦3,000 Pa.s, at any solids content when drying in the range of from 20 to 55% by weight of the composition, using any shear rate in the range of from 9±0.5 to 90±5 s −1 and at 23±2° C.; and

wherein said self-crosslinkable water-dispersible vinyl oligomer(s) is ≦60% by weight soluble in water throughout a pH range of from 2 to 10.

2. An aqueous coating composition according to claim 1 wherein said self-crosslinkable water-dispersible vinyl oligomer(s) has a solution viscosity ≦150 Pa·s, as determined from a 80% by weight solids solution of said self-crosslinkable water-dispersible vinyl oligomer(s) in at least one of the solvents selected from the group consisting of N-methylpyrrolidone, n-butylglycol and mixtures thereof, using a shear rate of 90±5 s −1 and at 50±2° C.

3. An aqueous coating composition according to claim 1 wherein said self-crosslinkable water-dispersible vinyl oligomer(s) has a solution viscosity ≦250 Pa·s, as determined from a 70% by weight solids solution of said self-crosslinkable water-dispersible vinyl oligomer(s) in a solvent mixture consisting of:

i) at least one of the solvents selected from the group consisting of N-methylpyrrolidone, n-butylglycol and mixtures thereof;

ii) water and

iii) N,N-dimethylethanolamine;

where i), ii) and iii) are in weight ratios of 20/7/3 respectively, using a shear rate of 90±5 s −1 and at 23±2° C.

4. An aqueous composition according to any one of claims 1 , 2 or 3 wherein said composition has an equilibrium viscosity ≦5,000 Pa·s when measured using any shear rate in the range of from 0.09±0.005 to 90±5 s −1 , and an equilibrium viscosity of ≦3,000 Pa·s when measured using any shear rate in the range of from 0.9±0.05 to 90±5 s −1 , and an equilibrium viscosity of ≦1,500 Pa·s when measured using any shear rate in the range of from 9±0.5 to 90±5 s −1 , at any solids content when drying in the range of from 20 to 55% by weight of the composition and at 23±2° C.

5. An aqueous composition according to any one of claims 1 , 2 or 3 wherein said composition has an equilibrium viscosity ≦5,000 Pa·s when measured using any shear rate in the range of from 0.09±0.005 to 90±5 s −1 after a 12% increase of the solids content by weight of the composition when drying.

6. An aqueous composition according to any one of claims 1 , 2 or 3 wherein the self-crosslinkable water-dispersible vinyl oligomer(s) has a PDi≦15.

7. An aqueous composition according to any one of claims 1 , 2 or 3 wherein the self-crosslinkable water-dispersible vinyl oligomer(s), when a precursor vinyl oligomer(s), has a measured Tg in the range of from −90 to 100° C.

8. An aqueous coating composition according to any one of claims 1 , 2 or 3 comprising:

i) 15 to 40% of a crosslinkable oligomer(s) by weight of total binder solids of which at least 52 wt % is said self-crosslinkable water-dispersible vinyl oligomer(s);

ii) 0 to 10% of a non-crosslinkable oligomer(s) by weight of total binder solids;

iii) 50 to 85% of dispersed vinyl polymer(s) by weight of total binder solids;

where i)+ii)+iii)=100%.

9. An aqueous coating composition according to any one of claims 1 , 2 or 3 additionally comprising a pigment.

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

11. An aqueous composition according to claim 1 wherein the dispersed vinyl polymer(s) has an acid value below 160 mgKOH/g.

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

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

14. An aqueous coating composition according to claim 1 comprising:

i) 0 to 15% co-solvent by weight of total binder solids;

ii) 35 to 65% of said self-crosslinkable water-dispersible vinyl oligomer by weight of total binder solids; wherein the self-crosslinkable water-dispersible vinyl oligomer(s) comprises 45 to 75 wt % of fatty acid groups; and wherein said dispersed vinyl polymer(s) has an acid value below 20 mgKOH/g.

15. An aqueous coating composition according to claim 1 comprising:

i) 3 to 26% of a crosslinkable oligomer(s) by weight of the composition of which at least 52 wt % is said self-crosslinkable water-dispersible vinyl oligomer(s);

ii) 0 to 6.5% of a non-crosslinkable oligomer(s) by weight of the composition;

iii) 10 to 56% of dispersed vinyl polymer(s) by weight of the composition;

iv) 0 to 15% of co-solvent by weight of the composition; and

v) 5 to 65% of water by weight of the composition;

where i)+ii)+iii)+iv)+v)=100%.

16. An aqueous composition comprising an ambient temperature self-crosslinkable water-dispersible vinyl oligomer(s) having a measured weight average molecular weight in the range of from 1,000 to 80,000 Daltons and a dispersed vinyl polymer(s) and 0 to 25% of co-solvent by weight of the composition where the ratio of said self-crosslinkable water-dispersible vinyl oligomer(s) to said dispersed vinyl polymer(s) is in the range of from 90:10 to 10:90 and wherein said composition when drying at ambient temperature crosslinks to form a coating having the following properties:

i) an open time of at least 20 minutes at 23+/−2° C.;

ii) a wet edge time of at least 10 minutes at 23+/−2° C.;

iii) a tack-free time of ≦20 hours at 23+/−2° C.; and

iv) an equilibrium viscosity of ≦3,000 Pa·s, at any solids content when drying in the range of from 20 to 55% by weight of the composition, using any shear rate in the range of from 9±0.5 to 90±5 s −1 and at 23±2° C.; and

wherein said self-crosslinkable water-dispersible vinyl oligomer(s) is ≦60% by weight soluble in water throughout a pH range of from 2 to 10 and wherein the dispersed vinyl polymer(s) has a measured weight average molecular weight ≦90,000 Daltons with the proviso that the dispersed vinyl polymer(s) has a solution viscosity >150 Pa·s, as determined from a 80% by weight solids solution of the dispersed vinyl polymer(s) in at least one of the solvents selected from the group consisting of N-methylpyrrolidone, n-butylglycol and mixtures thereof, using a shear rate of 90±5 s −1 and at 50±2° C.

17. An aqueous coating composition according to claim 1 or claim 16 wherein said self-crosslinkable water-dispersible vinyl oligomer is self-crosslinkable by autooxidation, Schiff-base crosslinking or a combination thereof.

18. A coating obtained from an aqueous composition according to any one of claims 1 , 2 or 3 .

19. A method of coating a substrate which comprises coating the substrate with an aqueous coating composition according to any one of claims 1 , 2 or 3 .