Aqueous polyester coating compositions

1. An aqueous coating composition comprising an ambient temperature crosslinkable water-dispersible polyester oligomer(s) and a dispersed polymer(s) having a measured weight average molecular weight ≧120,000 Daltons where the ratio of crosslinkable polyester oligomer(s) to the dispersed polymer(s) is in the range of from 90:10 to 20:80, and from 0 to 25% of co-solvent by weight of the composition, and wherein said composition when drying to form a coating 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 thumb hard time of ≦48 hours at 23±20° C.;

iv) a tack-free time of ≦20 hours at 23±2° C.; and

v) 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 the crosslinkable polyester oligomer(s) is ≦80% by weight soluble in water throughout a pH range of from 2 to 10, and has an acid value in the range of from 0 to 90 mg KOH/g.

2. An aqueous coating composition comprising:

i) 3 to 26% of a crosslinkable oligomer(s) by weight of the composition of which at least 52 wt % is an ambient temperature crosslinkable water-dispersible polyester oligomer(s);

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

iii) 10 to 56% of dispersed polymer(s) by weight of the composition, said dispersed polymer(s) having a measured weight average molecular weight ≧120,000 Daltons;

iv) 0 to 25% of co-solvent by weight of the composition;

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

where i)+ii)+iii)+iv)+v)=100%; and

wherein said composition when drying to form a coating 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 thumb hard time of ≦48 hours at 23±2° C.;

iv) a tack-free time of ≦20 hours at 23±2° C.; and

v) 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 the crosslinkable polyester oligomer(s) is 80% by weight soluble in water throughout a pH range of from 2 to 10; and has an acid value in the range of from 0 to 90 mg KOH/g.

3. An aqueous coating composition according to claim 1 or claim 2 wherein said polyester oligomer(s) has a solution viscosity ≦250 Pa.s, as determined from a 70% by weight solids solution of the crosslinkable polyester 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 coating composition according to claim 1 or claim 2 wherein said polyester oligomer(s) has a solution viscosity ≦150 Pa.s, as determined from a 80% by weight solids solution of the crosslinkable polyester 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.

5. An aqueous composition according to any one of claim 1 or 2 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.

6. An aqueous composition according to any one of claim 1 or 2 wherein said composition has an equilibrium viscosity ≦5,000 Pa.s when measured using a 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.

7. An aqueous composition according to any one of claim 1 or 2 wherein the crosslinkable polyester oligomer(s) has a measured weight average molecular weight in the range of from 1,000 to 100,000 Daltons.

8. An aqueous composition according to any one of claim 1 or 2 wherein the crosslinkable polyester oligomer(s) has a PDi≦30.

9. An aqueous composition according to any one of claim 1 or 2 wherein the crosslinkable polyester oligomer(s) has a measured Tg in the range of from −90 to 100° C.

10. An aqueous composition according to any one of claim 1 or 2 wherein the crosslinkable water-dispersible polyester oligomer(s) is self-crosslinkable.

11. An aqueous composition according to any one of claim 1 or 2 wherein the crosslinkable water-dispersible polyester oligomer(s) is crosslinkable by autoxidation optionally in combination with Schiff base crosslinking.

12. An aqueous composition according to claim 11 wherein the crosslinkable water-dispersible polyester oligomer(s) contains autoxidisable groups and carbonyl functional groups.

13. An aqueous composition according to any one of claim 1 or 2 wherein the crosslinkable water-dispersible polyester oligomer(s) is crosslinkable by Schiff base crosslinking optionally in combination with silane condensation.

14. An aqueous composition according to any one of claim 1 or 2 wherein the crosslinkable water-dispersible polyester oligomer(s) is crosslinkable by silane condensation optionally in combination with autoxidation.

15. An aqueous composition according to claim 1 or claim 2 wherein the dispersed polymer(s) has particle size in the range of from 25 to 1000 nm.

16. An aqueous composition according to claim 1 or claim 2 wherein the dispersed polymer(s) has an acid value below 150 mgKOH/g.

17. An aqueous composition according to claim 1 or claim 2 wherein the dispersed polymer(s) is a vinyl polymer.

18. An aqueous composition according to claim 17 wherein the dispersed polymer(s) has a measured Tg in the range of from −50 to 300° C.

19. An aqueous coating composition according to claim 1 or claim 2 comprising:

i) 0 to 15% co-solvent by weight of crosslinkable oligomer(s), non-crosslinkable oligomer(s) and dispersed polymer(s);

ii) 35 to 65% of crosslinkable polyester oligomer(s) by weight of crosslinkable oligomer(s), non-crosslinkable oligomer(s) and dispersed polymer(s); wherein the crosslinkable polyester oligomer(s) comprises 45 to 75 wt % of fatty acid groups; and wherein the dispersed polymer(s) has an acid value below 20 mgKOH/g.

20. An aqueous coating composition according to any one of claim 1 or 2 additionally comprising a pigment.

21. A substrate having a coating obtained from an aqueous composition according to any one of claim 1 or 2 .

22. An aqueous coating composition comprising an ambient temperature crosslinkable water-dispersible polyester oligomer(s) and a dispersed polymer(s) having a measured weight average molecular weight <120,000 Daltons where the ratio of crosslinkable polyester oligomer(s) to the dispersed polymer(s) is in the range of from 90:10 to 20:80, and from 0 to 25% of co-solvent by weight of the composition, and wherein said composition when drying to form a coating 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 thumb hard time of ≦48 hours at 23±2° C.;

iv) a tack-free time of ≦20 hours at 23±2° C.; and

v) 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 the crosslinkable polyester oligomer(s) is ≦80% by weight soluble in water throughout a pH range of from 2 to 10, and has an acid value in the range of from 0 to 90 mg KOH/g with the proviso that the dispersed polymer(s) is a vinyl polymer and has a solid viscosity >150 Pa.s, as determined from an 80% by weight solids solution of the dispersed 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 ate of 90±5 s −1 and at 50±2° C.

23. An aqueous coating composition comprising an ambient temperature crosslinkable water-dispersible polyester oligomer(s) and a dispersed polymer(s) having a measured weight average molecular weight <120,000 Daltons where the ratio of crosslinkable polyester oligomer(s) to the dispersed polymer(s) is in the range of from 90:10 to 20:80, and from 0 to 25% of co-solvent by weight of the composition, and wherein said composition when drying to form a coating 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 thumb hard time of ≦48 hours at 23±2° C.;

iv) a tack-free time of ≦20 hours at 23±2° C.; and

v) 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 the crosslinkable polyester oligomer(s) is ≦80% by weight soluble in water throughout a pH range of from 2 to 10, and has an acid value in the range of from 0 to 90 mg KOH/g with the proviso that the dispersed polymer(s) has a solution viscosity ≧250 Pa.s, as determined from an 80% by weight solids solution of the dispersed 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. and with the further proviso that the crosslinkable water-dispersible polyester oligomer(s) is selected from the group consisting of such polyester oligomer(s) that are self-crosslinkable, crosslinkable by autooxidation, crosslinkable by Schiff base crosslinking or crosslinkable by silane condensation and with the further proviso that said polyester oligomer(s) has a solution viscosity ≦150 Pa.s, as determined from a 80% by weight solids solution of the crosslinkable polyester 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.

24. An aqueous coating composition comprising:

i) 14 to 40% of ambient temperature crosslinkable water-dispersible oligomer(s) by weight of crosslinkable oligomer(s), non-crosslinkable oligomer(s) and dispersed polymer(s) of which at least 52 wt % is crosslinkable polyester oligomer(s);

ii) 0 to 10% of a non-crosslinkable oligomer(s) by weight of crosslinkable oligomer(s), non-crosslinkable oligomer(s) and dispersed polymer(s);

iii) 50 to 85% of dispersed polymer(s) by weight of crosslinkable oligomer(s), non-crosslinkable oligomer(s) and dispersed polymer(s); said dispersed polymer(s) having a measured weight average molecular weight ≧120,000 Daltons and

where i)+ii)+iii)=100%, and

iv) 0 to 25% of co-solvent by weight of the composition, said composition when drying 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 thumb hard time of ≦48 hours at 23±2° C.;

iv) a tack-free time of ≦20 hours at 23±2° C.; and

v) 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 the crosslinkable polyester oligomer(s) is ≦80% by weight soluble in water throughout a pH range of from 2 to 10, and has an acid value in the range of from 0 to 90 mg KOH/g.

25. An aqueous coating composition comprising:

i) 3 to 26% of a crosslinkable oligomer(s) by weight of the composition of which at least 52 wt % is an ambient temperature crosslinkable water-dispersible polyester oligomer(s);

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

iii) 10 to 56% of dispersed polymer(s) by weight of the composition, said dispersed polymer(s) having a measured weight average molecular weight <120,000 Daltons;

iv) 0 to 25% of co-solvent by weight of the composition;

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

where i)+ii)+iii)+iv)+v)=100%; and

wherein said composition when drying to form a coating 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 thumb hard time of ≦48 hours at 23±2° C.;

iv) a tack-free time of ≦20 hours at 23±2° C.; and

v) 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 the crosslinkable polyester oligomer(s) is 80% by weight soluble in water throughout a pH range of from 2 to 10, and has an acid value in the range of from 0 to 90 mg KOH/g with the proviso that the dispersed polymer(s) is vinyl polymer and has a solution viscosity >150 Pa.s, as determined from an 80% by weight solids solution of the dispersed 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.

26. An aqueous coating composition comprising:

i) 3 to 26% of a crosslinkable oligomer(s) by weight of the composition of which at least 52 wt % is an ambient temperature crosslinkable water-dispersible polyester oligomer(s);

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

iii) 10 to 56% of dispersed polymer(s) by weight of the composition, said dispersed polymer(s) having a measured weight average molecular weight ≧120,000 Daltons;

iv) 0 to 25% of co-solvent by weight of the composition;

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

where i)+ii)+iii)+iv)+v)=100%; and

wherein said composition when drying to form a coating 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 thumb hard time of ≦48 hours at 23±2° C.;

iv) a tack-free time of ≦20 hours at 23±2° C.; and

v) 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 the crosslinkable polyester oligomer(s) is ≦80% by weight soluble in water throughout a pH range of from 2 to 10, and has an acid value in the range of from 0 to 90 mg KOH/g with the proviso that the dispersed polymer(s) has a solution viscosity ≧250 Pa.s, as determined from an 80% by weight solids solution of the dispersed 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. and with the further proviso that the crosslinkable water-dispersible polyester oligomer(s) is selected from the group consisting of such polyester oligomer(s) that are self-crosslinkable, crosslinkable by autooxidation, crosslinkable by Schiff base crosslinking or crosslinkable by silane condensation and with the further proviso that said polyester oligomer(s) has a solution viscosity ≦150 Pa.s, as determined from a 80% by weight solids solution of the crosslinkable polyester 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.