POLYURETHANE COATING COMPOSITION
Methods of making a two-component composition that can be applied to a substrate and cured to provide a coating that demonstrates minimal solvent pop at the dry film thickness limit of the coating are provided. A cured coating made from the two-component composition demonstrates minimal solvent pop, minimal air entrapment, and optimal dry spray and overspray acceptance. Coated articles made using the methods described herein are also provided
1 . A method, comprising:
providing a first component of a coating composition;
providing a reaction mixture including
two or more solvents; and
a catalyst;
combining the first component with the reaction mixture;
obtaining a two-component composition by mixing the combination of the first component and the reaction mixture with a second component; and
applying the composition to a substrate and drying at temperatures of from room temperature 25° C. up to about 160° C. to form a cured coating,
wherein the cured coating demonstrates minimal solvent pop at the dry film thickness limit of the cured coating.
2 . A method, comprising:
providing a first component of a coating composition, including a reaction mixture comprising:
two or more solvents; and
a catalyst;
providing a second component of the coating composition, wherein the second component is capable of reacting with the first component;
combining the first and second components to obtain the coating composition; and
applying the composition to a substrate and drying at temperatures of 25° C. up to about 160° C. to form a cured coating,
wherein the cured coating demonstrates minimal solvent pop at the dry film thickness limit of the cured coating.
3 . The method of claim 1 , wherein the first component includes at least one polyol.
4 . The method of claim 1 , wherein the second component includes at least one polyisocyanate.
5 . The method of claim 1 , wherein the mixture of one or more solvents includes water.
6 . The method of claim 1 , wherein the mixture of one or more solvents includes at least one compound with at least one alpha-hydrogen.
7 . The method of claim 1 , wherein the mixture of one or more solvents includes at least one compound that is a bidentate ligand capable of chelation with a metal catalyst or metal-containing species.
8 . The method of claim 1 , wherein the mixture of one or more solvents includes at least one compound selected from beta-dicarbonyl compounds, alpha-hydroxy ketones, fused aromatic beta-hydroxy ketones, beta-hydroxy nitrogen-heterocyclic fused aromatics, and mixtures or combinations thereof.
9 . The method of claim 1 , wherein the mixture of one or more solvents includes at least one beta-dicarbonyl compound.
10 . The method of claim 9 , wherein the at least one beta-dicarbonyl compound is a beta-diketo ester of a carboxylic acid.
11 . The method of claim 10 , wherein the beta-diketo ester is an acetoacetate compound selected from methyl acetoacetate, ethyl acetoacetate, alpha-methyl ethyl acetoacetate, alpha-n-butyl ethylacetoacetate, alpha-see-butyl ethyl acetoacetate, alpha ethyl methyl acetoacetate, and alpha-ethyl ethyl acetoacetate
12 . The method of claim 1 , wherein the mixture of one or more solvents includes at least one compound having the structure of a compound of formula (I):
wherein R1 and R2 are each independently H, C1-C10 alkyl, C1-C10 alkoxy, substituted C1-C10 alkyl, substituted C1-C10 alkoxy, and combinations thereof.
13 . The method of claim 1 , wherein the catalyst is selected from metal, metal alkoxide, metal salts of aliphatic carboxylic acids, metal salts of alicyclic carboxylic acids, and combinations thereof.
14 . The method of claim 13 , wherein the catalyst is selected from tin salts, zinc salts, lithium salts, and combinations thereof.
15 . The method of claim 14 , wherein the catalyst is a tin compound.
16 . The method of claim 14 , wherein the catalyst is a zinc compound.
17 . The method of claim 1 , wherein the one or more solvents in the reaction mixture is present at about 20% by weight, based on the total weight of the composition.
18 . The method of claim 1 , wherein the cured coating is substantially free of solvent pop at the dry film thickness limit of the coating of about 168 μm (6.6 mil).
19 . A coated article, comprising:
a substrate; and
a cured coating applied thereon, wherein the coating is obtained by the method of claim 1 .
20 . The article of claim 19 , wherein the substrate is a metal substrate.