High performance aqueous coating compositions
View Patent ↗This invention relates to coating compositions that include water; a latex polymer and a silane coupling agent. The latex polymer preferably comprises acetoacetoxy functionality, or is a multistage latex, or is an acetoacetoxy functional multistage latex. The silane coupling agent is preferably a functionalized silane coupling agent (more preferably an epoxy-functional silane coupling agent). The compositions may be used to coat a variety of substrates, including wood, cement and fiber cement. Articles having the coating applied thereto are also provided.
1. A coating composition, comprising:
water;
a multistage latex polymer having acetoacetoxy functionality; and
at least about 0.25 weight % and less than about 10 weight %, based on the weight of the latex polymer solids, of an epoxy-functional silane coupling agent that improves adhesion of the coating composition to a cementitious substrate.
2. The composition of claim 1 , wherein the multistage latex polymer comprises at least one soft stage having a Tg between about −65 and 30° C. and at least one hard stage having a Tg between about 30 and 230° C.
3. The composition of claim 1 , wherein the multistage latex polymer comprises 50 to 90 weight % soft stage polymer morphology having a Tg between about −5 and 25° C. and 10 to 50 weight % hard stage polymer morphology having a Tg between about 30 and 105° C., based on total polymer weight.
4. The composition of claim 1 , wherein the multistage latex polymer has a gradient Tg.
5. The composition of claim 1 , wherein the composition comprises at least 10 weight % multistage latex polymer, based on total composition solids.
6. The composition of claim 1 , wherein the multistage latex polymer is made using 2-(acetoacetoxy) ethyl methacrylate, t-butyl acetoacetate, diketene, or combination thereof.
7. The composition of claim 1 , wherein the multistage latex polymer is made using from 0.5 to 10 weight % acetoacetoxy functional monomer based on the total weight of the multistage latex polymer solids.
8. The composition of claim 1 , wherein the composition includes less than 10 weight % volatile organic compounds.
9. The composition of claim 1 , wherein the composition further comprises a low VOC coalescent in an amount of at least 1 weight %.
10. The composition of claim 1 , wherein the silane coupling agent has the formula:
R 1 Si(R 2 ) 3-n (OR 3 ) n
where n is 1, 2 or 3;
the R 1 group is alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, or phenylalkyl, wherein R 1 contains at least one epoxy functional group and can optionally include a silane oligomer;
each R 2 group is independently hydrogen, alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, phenylalkyl, or a silane oligomer, wherein each R 2 group can optionally include OR 3 groups or an epoxy functional group; and
each R 3 group is independently hydrogen, alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, or phenylalkyl.
11. The composition of claim 1 , wherein the epoxy-functional silane coupling agent is β-(3,4 epoxycyclohexyl)-ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 5,6-epoxyhexyltriethoxysilane, a hydrolyzate of the above or a mixture thereof.
12. The composition of claim 1 , wherein the silane coupling agent is present in an amount of from 0.25 to 5 weight percent based on the weight of latex polymer solids.
13. The composition of claim 1 , wherein the silane coupling agent is present in an amount of from 0.5 to 2 weight percent based on the weight of latex polymer solids.
14. The composition of claim 1 , wherein the composition is applied to a wood or porous substrate.
15. The composition of claim 1 , wherein the composition is applied to a cementitious substrate.
16. The composition of claim 15 , wherein the composition partially penetrates the cementitious substrate.
17. A coating composition, comprising:
water;
a latex polymer having acetoacetoxy functionality;
at least about 0.25 weight % and less than about 10 weight %, based on the weight of the latex polymer solids, of an epoxy-functional silane coupling agent that improves adhesion of the coating composition to a cementitious substrate; and
less than 10 weight % volatile organic compounds based upon the total composition weight.
18. The composition of claim 17 , wherein the latex polymer is made using from about 2 to about 7.5 weight % acetoacetoxy functional monomer based on the total weight of the latex polymer solids.
19. The composition of claim 17 , wherein the silane coupling agent has the formula:
R 1 Si(R 2 ) 3-n (OR 3 ) n
where n is 1, 2 or 3;
the R 1 group is alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, or phenylalkyl, wherein R 1 contains at least one epoxy functional group and can optionally include a silane oligomer;
each R 2 group is independently hydrogen, alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, phenylalkyl, or a silane oligomer, wherein each R 2 group can optionally include OR 3 groups or an epoxy functional group; and
each R 3 group is independently hydrogen, alkyl, cycloalkyl, phenyl, cycloalkylalkyl, alkenylcycloalkyl, alkenylphenyl, or phenylalkyl.
20. The composition of claim 17 , wherein the epoxy-functional silane coupling agent is β-(3,4 epoxycyclohexyl)-ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 5,6-epoxyhexyltriethoxysilane, a hydrolyzate of the above or a mixture thereof.