No-rinse pretreatment methods and compositions
View Patent ↗Conversion and passivation coatings and methods for metal surfaces such as steel and aluminum are disclosed. The coating compositions comprise an aqueous sol of cerium oxide and/or silica particles and a ureido silane compound. The methods of the invention comprise contacting the requisite metal surface with the coating composition.
1. An aqueous sol-containing coating composition, said coating composition consisting essentially of:
(a) colloidal cerium oxide particles in an amount of from 0.001 to 36% by total weight of the composition;
(b) at least one ureido silane having the structure:
and/or condensation product thereof wherein each R is independently hydrogen or alkyl group of from 1 to 4 carbon atoms, in an amount of from about 0.01 to 80% by total weight of the composition; and,
(c) water in an amount to provide the remainder of the total weight of the composition
wherein the coating composition is a conversion or passivation coating composition.
2. The coating composition as recited in claim 1 wherein colloidal cerium oxide particles (a) are selected from the group consisting of colloidal cerium oxide nitrate particles and colloidal cerium oxide acetate particles.
3. The coating composition as recited in claim 1 wherein colloidal cerium oxide particles (a) have a particle size of less than 100 nm.
4. The coating composition as recited in claim 1 wherein said ureido silane (b) is γ-ureidopropyltrimethoxysilane.
5. The coating composition as recited in claim 1 being substantially free of chromium and phosphate.
6. An aqueous sol-containing coating composition, said composition consisting essentially of:
(a) colloidal cerium oxide particles in an amount of from 0.001 to 36% by total weight of the composition;
(b) at least one ureido silane having the structure:
and/or condensation product thereof wherein each R is independently hydrogen or alkyl group of from 1 to 4 carbon atoms, in an amount of from 0.01 to 80% by total weight of the composition;
(c) stabilizing agent in an amount of from 1 to 20% by total weight of the composition; and,
(d) water in an amount to provide the remainder of the total weight of the composition;
wherein the coating composition is a conversion or passivation coating composition.
7. The coating composition as recited in claim 6 wherein stabilizing agent (c) is at least one member selected from the group consisting of glycols, glycol ethers, alcohols and polyether silanes.
8. The coating composition as recited in claim 6 wherein colloidal cerium oxide particles (a) are at least one member selected from the group consisting of colloidal cerium oxide nitrate particles and colloidal cerium oxide acetate particles.
9. The coating composition as recited in claim 6 wherein colloidal cerium oxide particles (a) have a particle size of less than 100 nm.
10. The coating composition as recited in claim 6 wherein said ureido silane (b) is γ-ureidopropyltrimethoxysilane.
11. The coating composition as recited in claim 6 being substantially free of chromium and phosphate.
12. A coated article comprising a metal coated with the coating composition of claim 1 .
13. A coated article comprising a metal coated with the coating composition of claim 6 .
14. The coated article of claim 12 wherein the metal is steel.
15. The coated article of claim 13 wherein the metal is steel.
16. An aqueous sol-containing composition for treating steel metal surfaces to form a conversion or passivation coating thereon, said composition consisting essentially of:
(a) colloidal cerium oxide particles selected from the group consisting of colloidal cerium oxide nitrate particles and colloidal cerium oxide acetate particles in an amount of from 0.001 to 10% by total weight of the composition;
(b) at least one ureido silane having the structure:
and/or condensation product thereof wherein each R is independently hydrogen or alkyl group of from 1 to 4 carbon atoms, in an amount of from about 0.01 to 60% by total weight of the composition; and,
(c) water in an amount to provide the remainder of the total weight of the composition.
17. The aqueous sol-containing composition for treating steel metal surfaces to form a conversion or passivation coating thereon of claim 16 , wherein the steel metal surfaces are cold rolled steel, electrogalvanized steel or hot dipped galvanized steel.