Methods and compositions for coating substrates

Patent metadata

Field	Value
Publication number	US-9522413-B2
Application number	US-201414479517-A
Country	US
Kind code	B2
Filing date	Sep 8, 2014
Priority date	Feb 28, 2013
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

A method for applying a multilayer coating comprising a basecoat and a clearcoat is disclosed. The basecoat is a curable aqueous composition comprising (1) polymeric particles prepared from ethylenically unsaturated compounds including a multi-ethylenically unsaturated monomer and a keto or aldo-functional monomer, and (2) a polyhydrazide. A hydrophobic polyester is present in the aqueous composition to improve its humidity resistance.

First claim

What is claimed is:

1. A method of applying a multilayer coating to a substrate comprising:
(a) applying a color-imparting, pigment-containing basecoat composition to a substrate to form a curable color-imparting basecoat layer, and
(b) applying a curable unpigmented coating composition to the basecoat layer to form a clear or transparent coating layer over the basecoat layer, wherein the basecoat layer is formed by depositing a polyhydrazide-containing curable aqueous composition comprising:
(i) a continuous phase comprising water, and
(ii) a dispersed phase comprising:
(A) polymeric particles prepared from the polymerization of a mixture of ethylenically unsaturated monomer compounds, including ethylenically unsaturated monomers comprising:
(1) a multi-ethylenically unsaturated monomer and
(2) an aldo or keto group-containing ethylenically unsaturated monomer; and

(B) a hydrophobic polyester prepared from polymerizing the following mixture of monomers:
(I) a polyacid component comprising a dimer fatty acid and a tricarboxylic acid; and
(II) a polyol component comprising a diol and a diol with carboxylic acid groups.

2. The method of claim 1 in which the basecoat layer is dehydrated and cured at a temperature within the range of 50 to 100° C. by reaction of the polyhydrazide with the keto or aldo groups.

3. The method of claim 1 in which the mixture of ethylenically unsaturated compounds includes an ethylenically unsaturated polyurethane.

4. The method of claim 3 in which the ethylenically unsaturated polyurethane is prepared from reacting an organic polyisocyanate with a polyol containing carboxylic acid functionality and a hydroxyalkyl (meth)acrylate such that the ethylenically unsaturated polyurethane is free of NCO groups.

5. The method of claim 1 wherein upon curing of the basecoat layer, it demonstrates a T g less than 25° C.

6. The method of claim 1 in which the multi-ethylenically unsaturated monomer is present in amounts of 2 to 30 percent by weight based on total weight of the ethylenically unsaturated monomers.

7. The method of claim 1 in which the keto group-containing ethylenically unsaturated monomer is present in amounts of at least 30percent by weight based on total weight of ethylenically unsaturated monomers.

8. The method of claim 1 in which the ethylenically unsaturated monomers comprise from 4 to 30 percent by weight of an alkyl ester of (meth)acrylic acid having at least 6 carbon atoms in the alkyl group; the percentage by weight being based on total weight of the ethylenically unsaturated monomers.

9. The method of claim 3 in which the ethylenically unsaturated polyurethane comprises from 30 to 60 percent by weight of the mixture of ethylenically unsaturated compounds and the ethylenically unsaturated monomers comprise from 40 to 70 percent by weight of the mixture of ethylenically unsaturated compounds; the percentages by weight being based on total weight of the mixture of ethylenically unsaturated compounds.

10. The method of claim 1 in which the polyhydrazide is a bishydrazide of a dicarboxylic acid having from 2 to 16 carbon atoms.

11. The method of claim 1 in which the equivalent ratio of hydrazide to aldo or keto is from 0.5 to 1.5:1.

12. The method of claim 1 in which the mixture of ethylenically unsaturated compounds contains at least one compound containing carboxylic acid functionality that is at least partially neutralized with an amine.

13. The method of claim 12 in which the amine is a volatile amine.

14. The method of claim 1 wherein the polyhydrazide-containing curable aqueous composition additionally contains (C) a polycarbodiimide.

15. The method of claim 14 in which the equivalent ratio of carbodiimide to carboxylic acid is from 0.5 to 1.5:1.

16. The method of claim 1 wherein the dimer fatty acid is hydrogenated.

17. The method of claim 1 wherein the tricarboxylic acid is trimellitic acid.

18. The method of claim 1 wherein the weight ratio of dimer fatty acid to tricarboxylic acid is in the range of 1 to 0.5:1.

19. The method of claim 1 wherein the diol of the polyol component comprises cyclohexane dimethanol.

20. The method of claim 1 wherein the weight ratio of diol without carboxylic acid groups to diol with carboxylic acid groups is in the range of 1to 0.15:1.

21. The method of claim 1 wherein the weight average molecular weight of the hydrophobic polyester is from 10,000 to 100,000.

22. The method of claim 1 wherein the hydroxyl value of the hydrophobic polyester is from 75 to 25.

23. The method of claim 1 wherein the acid value of the hydrophobic polyester is from 50 to 20.

24. The method of claim 1 wherein the hydrophobic polyester is present in the dispersed phase in an amount of 2 to 30 percent by weight based on weight of resin solids in the aqueous dispersion.

25. The method of claim 1 in which the curable unpigmented coating composition comprises an active hydrogen-containing polymer and a polyisocyanate curing agent.

26. An aqueous thermosetting coating composition comprising:
(i) a continuous phase comprising water, and
(ii) a dispersed phase comprising:
(A) polymeric particles prepared from the polymerization of a mixture of ethylenically unsaturated compounds including ethylenically unsaturated monomers comprising from:
(1) 2 to 30 percent by weight of a multi-ethylenically unsaturated monomer and
(2) at least 30 percent by weight of an aldo or keto group-containing ethylenically unsaturated monomer,
the percentages by weight being based on total weight of the ethylenically unsaturated monomers;

(B) a hydrophobic polyester prepared from polymerizing the following mixture of monomers:
(I) a polyacid component comprising a dimer fatty acid and a tricarboxylic acid; and
(II) a polyol component comprising a diol and a diol with carboxylic acid groups;

(C) a polyhydrazide; and
(D) pigment(s).

27. The composition of claim 26 in which the mixture of ethylenically unsaturated compounds includes an ethylenically unsaturated polyurethane.

28. The composition of claim 27 in which the ethylenically unsaturated polyurethane is prepared from reacting an organic polyisocyanate with a polyol containing carboxylic acid functionality and a hydroxyalkyl (meth)acrylate such that the ethylenically unsaturated polyurethane is free of isocyanate groups.

29. The composition of claim 26 in which the ethylenically unsaturated monomers in (A) comprise from 4 to 30 percent by weight of an alkyl ester of (meth)acrylic acid having at least 6 carbon atoms in the alkyl group; the percentages by weight being based on total weight of the ethylenically unsaturated monomers.

30. The composition of claim 28 in which the ethylenically unsaturated polyurethane comprises from 30 to 60 percent by weight of the mixture of ethylenically unsaturated compounds and the ethylenically unsaturated monomers in (A) comprise from 40 to 70 percent by weight of the mixture of ethylenically unsaturated compounds; the percentages by weight being based on total weight of the ethylenically unsaturated compounds.

31. The composition of claim 26 in which the polyhydrazide is a bishydrazide of a dicarboxylic acid containing from 2 to 16 carbon atoms.

32. The composition of claim 26 wherein upon curing of the aqueous th

Assignees

• Ppg Ind Ohio Inc

Inventors

• Swarup Shanti
• Sadvary Richard J

Classifications

• B05D2202/10

  based on Fe · CPC title

• B05D7/534

  the first layer being let to dry at least partially before applying the second layer (B05D7/538 takes precedence) · CPC title

• C08K5/16

  Nitrogen-containing compounds {(C08K5/0091 takes precedence)} · CPC title

• C08G18/4854

  Polyethers containing oxyalkylene groups having four carbon atoms in the alkylene group · CPC title

• C09D175/16

  having terminal carbon-to-carbon unsaturated bonds · CPC title