Patent EA-001588-B1 (EA)
Title: Method of preventing corrosion of metals using silanes
Inventor: VAN OOIJ WIM J
IPC: B05D7/16
Filed: 1998-01-08
Abstract: 1. A method of treating a metal substrate, comprising the steps of: (a) providing a metal substrate; (b) applying a coating of a first treatment solution directly onto the surface of said metal, said first treatment solution comprising at least 0.1% by volume of at least one silane, wherein the silane consists only of multi-functional silane having at least two trisubstituted silyl groups wherein the substituents are individually chosen from the group consisting of alkoxy and acetoxy, wherein said multi-functional silane has been at least partially hydrolyzed, and wherein said first treatment solution has a pH of less than 7. 2. A method of treating a metal substrate, comprising the steps of: (a) providing a metal substrate; (b) applying at least one coating of a first treatment solution directly onto the surface of said metal to afford a coated metal surface, said first treatment solution comprising at least 0.1% by volume of at least one multi-functional silane having at least two trisubstituted silyl groups wherein the substituents are individually chosen from the group consisting of alkoxy and acetoxy, wherein said multi-functional silane has been at least partially hydrolyzed, and wherein said first working solution has a pH of less than about 7; and (c) applying a polymer coating onto the coated metal surface. 3. The method of Claim 2, wherein the polymer coating is selected from the group consisting of paints, adhesives or rubber coatings. 4. The method of any of Claims 1 to 3, wherein said at least one multi-functional silane comprises:   wherein X is selected from the group consisting of either a bond, an aliphatic or aromatic group; each R is an alkyl or acetyl group, and n is 2 or 3. 5. The method of Claim 4, wherein each R is individually chosen from the group consisting of: ethyl, methyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, ter-butyl and acetyl. 6. The method of Claim 5, wherein X is chosen from the group consisting of: a bond, C1-C6 alkyl, C2-C6-alkenyl, C1-C6-alkyl substituted with at least one amino group, C2-C6-alkenyl substituted with at least one amino group, benzyl, and benzyl substituted with C1-C6-alkyl. 7. The method of Claim 6, wherein said multi-functional silane is 1,2-bis-(triethoxysilyl)ethane. 8. The method of Claim 6 or Claim 7, wherein said metal is chosen from the group consisting of: cold-rolled steel, aluminum and aluminum alloy. 9. The method of any of Claim 1-8, further comprising the step of curing said coating after step (b), at a temperature of between 60 degree C and 250 degree C for between one minute and 2 hours. 10. The method of Claim 9, further comprising the step of applying a second coating after step (b) of said first treatment solution after said curing step. 11. The method of Claim 10, further comprising the step of curing said second coating. 12. The method of any of Claims 1 to 10 further comprising the step of applying a second coating after step (b) comprising a second treatment solution after application of said first treatment solution, said second treatment solution containing at least one organofunctional silane which has been at least partially hydrolyzed. 13. The method of Claim 12, wherein said at least one organofunctional silane has one trisubstituted silyl group, wherein the substituents are individually chosen from the group consisting of alkoxy and acetoxy, and at least one organofunctional group. 14. The method of Claim 13, wherein said organofunctional group is chosen from the group consisting of: amino, vinyl, ureido, epoxy, mercapto, cyanato, methacrylato, and vinylbenzyl. 15. The method of Claim 14, wherein said at least one organofunctional silane is chosen from the group consisting of: γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-ureidopropyltrialkoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltriacetoxysilane. 16. The method of any of Claims 4 to 7, wherein said metal is preheated to a temperature of between 60 degree C and 250 degree C prior to application of the first treatment solution. 17. A method of any of Claim 1 to 16, wherein the metal substrate is selected from aluminum or aluminum alloy. 18. The method of Claim 17, wherein the total concentration of multi-functional silanes in said working solution is greater than 0.2 % by volume, based upon the total volume of treatment solution components. 19. The method of Claim 18, wherein the total concentration of multi-functional silanes in said treatment solution is between 2% and 5%. 20. The method of Claim 12, further comprising the step of applying a final coating of a solution after step (b) containing at least one organofunctional silane which has been at least partially hydrolyzed. 21. A method of pretreating cold-rolled steel, comprising the steps of: (a) providing a first treatment solution consisting essentially of at least one multifunctional silane which has been at least partially hydrolyzed, wherein said multi-functional silane has at least two trialkoxysilyl groups; (b) providing a second treatment solution comprising at least one organofunctional silane which has been at least partially hydrolyzed; (c) applying a coating of said first treatment solution directly onto the surface of the steel; and (d) thereafter applying a coating of said second treatment solution onto said steel. 22. The method of Claim 21, wherein the total concentration of multi-functional silanes in said first treatment solution is between 0.1% and 10% by volume, based upon the total volume of first treatment solution components, and wherein the total concentration of organofunctional silanes in said second treatment solution is between 0.1% and 10% by volume, based upon the total volume of second treatment solution components. 23. The method of Claim 21 or Claim 22, wherein said at least one organofunctional silane is γ-aminopropyltriethoxysilane, and the total concentration of multi-functional silanes in said treatment solution is between 1% and 5% by volume. 24. A treatment solution composition comprising in an aqueous alcohol solution at least 0.1% by volume of at least one silane, wherein the silane is a multi-functional silane having at least two trisubstituted silyl groups wherein the substituents are individually chosen from the group consisting of alkoxy and acetoxy, wherein the concentration range of alcohol to water is in the ratio of 1:99 to 99:1, more preferably in the ratio of 5:95 to 95:5, and wherein the total concentration of multi-functional silanes in said treatment solution is between 2% and 5% by volume, based upon the total volume of said treatment solution components. 25. The composition of Claim 24, wherein an amount of a weak acid, preferably acetic acid is added to the solution to adjust the pH.