Sol-gel coating method and composition

Patent metadata

Field	Value
Publication number	US-9334407-B2
Application number	US-201314078624-A
Country	US
Kind code	B2
Filing date	Nov 13, 2013
Priority date	Nov 9, 2006
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

A coating composition and a method for coating metallic substrates, such as aircraft components exposed to elevated temperatures and/or oxidative conditions. The coating composition includes an aqueous mixture having about 2 vol % to about 50 vol % organosilane, about 0.3 to about 25 vol % metal alkoxide, and about 0.1 to about 30 vol % organic complexing agent. The coating composition may be deposited on a metallic substrate and cured to form a sol-gel coating on the surface of the substrate that is adherent to the substrate, and oxidation and discoloration resistant.

First claim

The invention claimed is:

1. An aqueous sol-gel coating composition for coating a metallic aircraft component comprising:
an organosilane,
a metal alkoxide; and
an organic complexing agent;
wherein the metal alkoxide is a compound having the general formula Zr(R—O) 4 ; wherein R is a lower linear or branched aliphatic, alicyclic or aryl moiety having 2 to 8 carbon atoms;
wherein the complexing agent is selected from the group consisting of acetic acid, oxalic acid, citric acid, acetylacetonates, glycols, ethoxyethanol, ethanolamine, and combinations thereof;
wherein a ratio of metal alkoxide to organic complexing agent is about 2:1 by volume percent; wherein the coating composition is devoid of pigment and the total volume percent of the components in the aqueous composition is less than about 50% and the composition forming an adherent bond to metallic substrates when cured and providing a cured coating structure resistance to oxidation and discoloration.

2. The composition of claim 1 , wherein the organosilane is selected from the group consisting of 3-glycidoxyproplytrimethoxysilane, tetraethylorthosilicate, 3-aminopropyltriethoxysilane, 3-glycidoxy-propyltriethoxysilane, p- or m-aminophenylsilane, allyltrimethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyldiisopropylethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, n-phenylaminopropyltrimethoxysilane, vinylmethyldiethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane and combinations thereof.

3. The composition of claim 1 , wherein the organosilane comprises 3-glycidoxyproplytrimethoxysilane.

4. The composition of claim 1 , wherein the alkoxide is zirconium n-propoxide (70% in propanol).

5. The composition of claim 1 , wherein the complexing agent is acetic acid.

6. The composition of claim 1 , wherein mixture comprises less than about 50 vol % total organosilane and alkoxide.

7. The composition of claim 1 , wherein the composition further comprises a surfactant.

8. The composition of claim 1 , wherein water is present in an amount more than any other component in the composition.

9. The composition of claim 8 , wherein the water is deionized water.

10. The composition of claim 1 , wherein the composition includes water and at least one additional solvent.

11. The composition of claim 1 , wherein molar ratio of Zr to Si in the coating composition is about 1:1 to about 1:10.

12. The composition of claim 1 , wherein molar ratio of Zr to Si in the coating composition is about 1:3.5.

13. The composition of claim 1 , wherein the adherent bond formed when the composition is cured includes covalent bonding between the metallic substrate and the metal alkoxide.

14. The composition of claim 1 , wherein the cured coating structure is resistant to both oxidation and discoloration at temperature up to about 700° F.

15. An aqueous sol-gel coating composition for coating a metallic aircraft component comprising:
3-glycidoxyproplytrimethoxysilane,
zirconium n-propoxide (70% in propanol); and
an organic complexing agent;

wherein a ratio of zirconium n-propoxide to organic complexing agent is about 2:1 by volume percent; wherein the coating composition is devoid of pigment and the total volume percent of the components in the aqueous composition is less than about 50% and the composition forming an adherent bond to metallic substrates when cured and providing a cured coating structure resistance to oxidation and discoloration.

16. An aqueous sol-gel coating composition for coating a metallic aircraft component comprising:
about 11.21 vol % 3-glycidoxypropyltrimethoxysilane,
about 5.61 vol % zirconium n-propoxide (70% in propanol),
about 2.52 vol % glacial acetic acid,
about 0.56 vol % BL-240 surfactant and the balance essentially deionized water;
wherein the coating composition is devoid of pigment and the composition forming an adherent bond to metallic substrates when cured and providing a cured coating structure resistance to oxidation and discoloration.

Assignees

• Boeing Co

Inventors

• Blohowiak Kay Y
• Grob Jacob W
• Osborne Joseph H

Classifications

• C09D183/00 Primary

  Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers · CPC title

• B32B27/283

  comprising polysiloxanes · CPC title

• C09D5/086

  Organic or non-macromolecular compounds · CPC title

• C23C18/1254

  Sol or sol-gel processing · CPC title

• C09D4/00 Primary

  Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond {; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16} · CPC title