Crosslinkable coating compositions containing polyurethane
View Patent ↗An aqueous crosslinkable coating composition that includes a PU polymer and a vinyl polymer bearing carbonyl groups (i.e., a carbonyl-functional vinyl polymer) and/or latex polymer. The composition also preferably includes carbonyl-reactive amine and/or hydrazine functional groups.
1. An aqueous crosslinkable coating composition comprising:
water;
a water-dispersible polyurethane polymer, comprising:
a plurality of urethane linkages;
a plurality of cycloaliphatic groups incorporated into the polyurethane polymer through cyclohexane diacid, non-isocyanate compounds, wherein at least one of the plurality of cycloaliphatic groups comprises a structure X-Z-X, and wherein: Z is the cyclohexane ring structure; and each X is an ester group, wherein at least one of the X groups is a divalent linkage group attaches the cyclohexane ring structure to another portion of the polyurethane polymer;
a plurality of salt or salt-forming groups; and
a plurality of air-curable ethylenically unsaturated groups; and
a carbonyl-functional vinyl polymer, wherein the amount of carbonyl functional groups in the vinyl polymer is 3-500 milliequivalents per 100 grams polymer; and
carbonyl-reactive amine and/or hydrazine functional groups.
2. The composition of claim 1 wherein the carbonyl-reactive amine and/or hydrazine functional groups are incorporated within the vinyl polymer.
3. The composition of claim 2 wherein the amine and/or hydrazine content of the vinyl polymer is 10 to 300 milliequivalents per 100 grams polymer.
4. The composition of claim 1 wherein the carbonyl-reactive amine and/or hydrazine functional groups are in a crosslinker distinct from the vinyl polymer and the polyurethane polymer.
5. The composition of claim 4 wherein the crosslinker is a multi-functional amine comprising 2 to 10 primary amino groups per molecule.
6. The composition of claim 4 wherein the crosslinker is a multi-functional hydrazine.
7. The composition of claim 4 wherein the level of crosslinker in the composition is that which provides at least 0.2 equivalent amine and/or hydrazine groups per mole of carbonyl functional groups present in the composition.
8. The composition of claim 1 comprising an aqueous dispersion of polymer particles comprising the carbonyl-functional vinyl polymer.
9. The composition of claim 1 wherein the polyurethane polymer includes at least 3 wt-% of cycloaliphatic-group-containing compound having the X-Z-X structure, based on the total dry weight of the polyurethane polymer.
10. The composition of claim 1 wherein Z comprises a closed six-member ring.
11. The composition claim 1 wherein at least a portion of the air-curable ethylenically unsaturated groups are provided by a fatty acid.
12. A method of preparing an aqueous crosslinkable coating composition, the method comprising:
providing an aqueous dispersion comprising a water-dispersible polyurethane polymer, comprising:
a plurality of urethane linkages;
a plurality of cycloaliphatic groups incorporated into the polyurethane polymer through cyclohexane diacid, non-isocyanate compounds, wherein at least one of the plurality of cycloaliphatic groups comprises a structure X-Z-X, and wherein: Z is the cyclohexane ring structure; and each X is an ester group, wherein at least one of the X groups is a divalent linkage group attaches the cyclohexane ring structure to another portion of the polyurethane polymer;
a plurality of salt or salt-forming groups; and
a plurality of air-curable ethylenically unsaturated groups; and
providing an aqueous dispersion of polymer particles comprising a carbonyl-functional vinyl polymer;
providing carbonyl-reactive amine and/or hydrazine functional groups in a crosslinker distinct from either the polyurethane polymer or the carbonyl-functional vinyl polymer and/or incorporated within the carbonyl-functional vinyl polymer;
combining the aqueous dispersion of the polyurethane polymer and the carbonyl-functional vinyl polymer to form a mixture; and
if a distinct crosslinker is used, combining the mixture with the distinct crosslinker.
13. The method of claim 12 wherein providing carbonyl-reactive amine and/or hydrazine functional groups comprises providing a crosslinker comprising the carbonyl-reactive amine and/or hydrazine functional groups, and the method comprises combining the mixture with the crosslinker.
14. A method of preparing an aqueous crosslinkable coating composition, the method comprising:
providing a carbonyl-functional vinyl polymer, wherein the amount of carbonyl functional groups in the vinyl polymer is 3-500 milliequivalents per 100 grams polymer;
preparing a water-dispersible polyurethane polymer in the presence of the carbonyl-functional vinyl polymer and combining the mixture with water, wherein the water-dispersible polyurethane comprises:
a plurality of urethane linkages;
a plurality of cycloaliphatic groups incorporated into the polyurethane polymer through cyclohexane diacid, non-isocyanate compounds, wherein at least one of the plurality of cycloaliphatic groups comprises a structure X-Z-X, and wherein: Z is the cyclohexane ring structure; and each X is an ester group, wherein at least one of the X groups is a divalent linkage group attaches the cyclohexane ring structure to another portion of the polyurethane polymer;
a plurality of salt or salt-forming groups; and
a plurality of air-curable ethylenically unsaturated groups; and
providing carbonyl-reactive amine and/or hydrazine functional groups in a crosslinker distinct from either the polyurethane polymer or the carbonyl-functional vinyl polymer and/or incorporated within the carbonyl-functional vinyl polymer; and
if a distinct crosslinker is used, combining the aqueous dispersion of the polyurethane polymer and the carbonyl-functional vinyl polymer with the distinct crosslinker.
15. A method of preparing an aqueous crosslinkable coating composition, the method comprising:
providing an aqueous dispersion of polymer particles comprising a carbonyl-functional vinyl polymer;
preparing a water-dispersible polyurethane prepolymer;
combining the water-dispersible polyurethane prepolymer with the aqueous dispersion of polymer particles comprising a carbonyl-functional vinyl polymer; and
forming a water-dispersible polyurethane polymer from the polyurethane prepolymer in the presence of the polymer particles comprising a carbonyl-functional vinyl polymer, wherein the water-dispersible polyurethane comprises:
a plurality of urethane linkages;
a plurality of cycloaliphatic groups incorporated into the polyurethane polymer through cyclohexane diacid, non-isocyanate compounds, wherein at least one of the plurality of cycloaliphatic groups comprises a structure X-Z-X, and wherein: Z is the cyclohexane ring structure; and each X is an ester group, wherein at least one of the X groups is a divalent linkage group attaches the cyclohexane ring structure to another portion of the polyurethane polymer;
a plurality of salt or salt-forming groups; and
a plurality of air-curable ethylenically unsaturated groups; and
providing carbonyl-reactive amine and/or hydrazine functional groups in a crosslinker distinct from either the polyurethane polymer or the carbonyl-functional vinyl polymer and/or incorporated within the carbonyl-functional vinyl polymer; and
if a distinct crosslinker is used, combining the aqueous dispersion of the polyurethane polymer and the carbonyl-functional vinyl polymer with the distinct crosslinker.
16. A method of preparing an aqueous crosslinkable coating composition, the method comprising:
providing a latex polymer;
preparing a water-dispersible polyurethane prepolymer;
combining the latex polymer and the polyurethane prepolymer; and
forming a water-dispersible polyurethane polymer from the polyurethane prepolymer in the presence of the latex polymer, wherein the water-dispersible polyurethane comprises:
a plurality of urethane linkages;
a plurality of cycloaliphatic groups incorporated into the polyurethane polymer through cyclohexane diacid, non-isocyanate compounds, wherein at least one of the plurality of cycloaliphatic groups comprises a structure X-Z-X, and wherein: Z is the cyclohexane ring structure; and each X is an ester group, wherein at least one of the X groups is a divalent linkage group attaches the cyclohexane ring structure to another portion of the polyurethane polymer;
a plurality of salt or salt-forming groups; and
a plurality of air-curable ethylenically unsaturated groups.
17. An aqueous crosslinkable coating composition preparable by the method of claim 13 .
18. An aqueous crosslinkable coating composition comprising:
a latex polymer; and
a water-dispersible polyurethane polymer, comprising:
a plurality of urethane linkages;
a plurality of cycloaliphatic groups incorporated into the polyurethane polymer through cyclohexane diacid, non-isocyanate compounds, wherein at least one of the plurality of cycloaliphatic groups comprises a structure X-Z-X, and wherein: Z is the cyclohexane ring structure; and each X is an ester group, wherein at least one of the X groups is a divalent linkage group attaches the cyclohexane ring structure to another portion of the polyurethane polymer;
a plurality of salt or salt-forming groups; and
a plurality of air-curable ethylenically unsaturated groups.
19. A method of coating a substrate, the method comprising applying an aqueous crosslinkable coating composition of claim 1 , and removing the water.
20. A coated substrate preparable by the method of claim 19 .