Aqueous polymer compositions

• US 20030055171A1
• Filed: 08/28/2002
• Published: 03/20/2003
• Est. Priority Date: 03/09/2000
• Status: Active Grant

• Current Assignee: DSM IP Assets BV (DSM-Firmenich AG)
• Original Assignee: Avecia Limited
• Inventors: Overbeek, Gerardus Cornelis, Tennebroek, Ronald, Nabuurs, Tijs, Steenwinkel, Pablo
• Granted Patent: US 6,730,733 B2
• Time in Patent Office: Days
• US Class Current: 525/192
• CPC Class Codes: C08G 18/0823 containing carboxylate salt groups or groups forming them
• CPC Class Codes: C08G 18/0828 containing sulfonate groups or groups forming them
• CPC Class Codes: C08G 18/12 using two or more compounds having active hydrogen in the first polymerisation step
• CPC Class Codes: C08G 18/3231 Hydrazine or derivatives thereof
• CPC Class Codes: C08G 18/672 Esters of acrylic or alkyl acrylic acid having only one group containing active hydrogen
• CPC Class Codes: C09D 175/16 having terminal carbon-to-carbon unsaturated bonds

Abstract

Aqueous polymer composition suitable for coating which comprises the following components dispersed in water: (1) a combination of an acrylic polymer(s) A and an acrylic polymer(s) B where polymer(s) A has a Tg of not more than 30° C. and polymer(s) B has a Tg of at least 35° C., more preferably at least 45° C., which is at least 25° C. higher than the Tg of polymer(s) A, and wherein one or both of polymers A and B bear crosslinker functional groups capable of imparting ambient-temperature crosslinkability to component (1) in a coating formed from the composition via the formation of non-radically-formed covalent bonds; and (2) a self-dispersible, ionically stabilised polymer having olefinically unsaturated bond functionality capable of imparting radiation-curability (preferably uv-radiation curability) thereto in a coating formed from the composition.

Claims

1. Aqueous polymer composition suitable for coating which comprises the following components dispersed in water:

(1) a combination of an acrylic polymer(s) A and an acrylic polymer(s) B where polymer(s) A has a Tg of not more than 30°

C. and polymer(s) B has a Tg of at least 35°

C., more preferably at least 45°

C., which is at least 25°

C. higher than the Tg of polymer(s) A, and wherein one or both of polymers A and B bear crosslinker functional groups capable of imparting ambient-temperature crosslinkability to component (1) in a coating formed from the composition via the formation of non-radically-formed covalent bonds; and

(2) a self-dispersible, ionically stabilised polymer having olefinically unsaturated bond functionality capable of imparting radiation-curability (preferably uv-radiation curability) thereto in a coating formed from the composition.

2. Composition according to claim 1 wherein one or both of polymers A and B of component (1) bear crosslinker functional groups for reaction with an already present or subsequently added external cross-linking agent having 2 or more groups which are reactable with the crosslinker groups on one or both of polymers A and B to form crosslinking covalent bonds (Embodiment X).

3. Composition according to claim 2 wherein the crosslinker functional groups on one or both of polymers A and B are carbonyl groups and the groups of the external crosslinking agent reactable therewith are carbonyl-reactive amino groups.

4. Composition according to claim 3 wherein said carbonyl-reactive amino groups are provided by —

NH₂ or —

NH—

groups which are bound only to a carbon atom(s), or carbonyl-reactive groups derived therefrom.

5. Composition according to claim 3 wherein said carbonyl-reactive amino groups are provided by hydrazine functional groups, preferably as part of acid hydrazide groups or semi-carbazide groups, or carbonyl-reactive groups derived therefrom.

6. Composition according to claim 2 wherein the crosslinker functional groups on one or both of polymers A and B are carboxyl groups and the groups of the external crosslinking agent reactable therewith are selected from aziridine, carbodiimide, cycloaliphatic polyepoxide and epoxy silane groups.

7. Composition according to claim 1 wherein one or both of polymers A and B of component (1) bear crosslinker groups capable of donating lone pairs of electrons to acceptor shells of metal ions of an already present or subsequently added metal compound, acting as an external crosslinking agent, thereby forming coordinate crosslinking bonds (Embodiment X).

8. Composition according to claim 7 wherein said crosslinker groups are carboxyl groups and the metal ions are zinc ions.

9. Composition according to claim 1 wherein each of polymers A and B of component (1) bear different crosslinker functional groups which are reactable with each other (co-reactable) to form crosslinking covalent bonds (Embodiment Y).

10. Composition according to claim 9 wherein the co-reactable groups are carbonyl groups and carbonyl-reactive amino groups.

11. Composition according to claim 10 wherein the carbonyl-reactive amino groups are provided by amino ester groups, preferably derived by iminating a precursor polymer bearing carboxyl groups.

12. Composition according to claim 1 wherein one or both of the acrylic polymers A and B of component (1) bear crosslinker functional groups which are reactable to form non-radically formed covalent crosslinking bonds with the olefinically unsaturated bonds of the polymer of component (2) (Embodiment Z).

13. Composition according to claim 12 wherein the crosslinker functional groups on one or both of acrylic polymers A and B of component (1) are primary or secondary amino groups.

14. Composition according to claim 13 wherein said amino groups are provided by amino ester groups, preferably derived by iminating a precursor polymer bearing carboxyl groups.

15. Composition according to claim 1 wherein one or both of polymers (A) and (B) bear crosslinker groups, and the radiation-curable polymer of component (2) also bears crosslinker groups, these not being the olefinically unsaturated bonds of the polymer of component (2), and preferably being the same as those of polymer A and/or B, said crosslinker groups being for reaction with an already present or subsequently added external crosslinking agent having 2 or more groups which are reactable with said crosslinker groups on polymer (A) and/or (B) and on the polymer of component (2) to form crosslinking covalent bonds (Embodiment Q).

16. Composition according to claim 15 wherein the crosslinker groups on one or both of polymer (A) and (B) and on the polymers of component (2) are carboxyl groups, and the groups of the external crosslinking agent reactive therewith are aziridine groups or metal ions.

17. Composition according to any one of the preceding claims wherein said radiation-curable polymer of component (2) has an olefinically unsaturated bond functionally of at least 0.25 mmoles C═

C/gram polymer, more preferably 0.5 to 3 mmoles C═

C/gram polymer.

18. Composition according to any one of the preceding claims wherein the ionic stabilisation of said radiation-curable polymer of component (2) is provided by internal anionic dispersing groups, preferably carboxylate anion groups or sulphonate anion groups.

19. Composition according to claim 18 wherein said polymer of component (2) additionally has nonionic internal dispersing groups.

20. Composition according to any one of the preceding claims wherein said radiation-curable polymer of component (2) is a uv-curable polyurethane.

21. Composition according to claim 20 wherein the olefinically unsaturated bonds of the polymer of component (2) are provided by an acryloyl or methacryloyl functional monool or polyol employed in the urethane synthesis.

22. Composition according to either claim 20 or claim 21 wherein the ionic stabilisation of said polyurethane is provided by employing in the synthesis thereof a dihydroxy alkanoic acid of formula.

23. Composition according to any one of claims 20 to 22 wherein said polyurethane is the chain-extended reaction product of an aqueous dispersed isocyanate-terminated urethane prepolymer and an active hydrogen chain-extending compound.

24. Composition according to any one of the preceding claims wherein the acrylic polymers A and B of component (1) have been formed by a sequential polymerisation procedure.

25. Composition according to any of the preceding claims wherein polymer B of component (1) has a Tg which is at least 40°

C. higher than that of polymer A, more preferably at least 50°

C. higher.

26. Composition according to any one of the preceding claims wherein the weight ratio of polymer A to polymer B in component (1) is within the range of from 30/70 to 90/10, more preferably from 40/60 to 80/20.

27. Composition according to any one of the preceding claims wherein the weight ratio of the polymers of component (1) to the polymer of component (2) is within the range of from 20/80 to 97/3, preferably 45/55 to 90/10.

28. Method of coating a substrate using an aqueous composition according to any one of the preceding claims.

29. Method according to claim 28 wherein the substrate is wood.

30. Method according to claim 29 wherein the substrate is provided by a door or window frame.

31. Coating obtainable or derived from an aqueous composition according to any one of claims 1 to 27.

32. Substrate having a coating obtainable or derived from an aqueous composition according to any one of claim 1 to 27.