Anodized aluminum having protective coating

• US 5,439,747 A
• Filed: 11/22/1993
• Issued: 08/08/1995
• Est. Priority Date: 03/19/1993
• Status: Expired due to Fees

• Current Assignee: PPG Industries Incorporated (Nouryon BV)
• Original Assignee: PPG Industries Incorporated (Nouryon BV)
• Inventors: Sturdevant, Shelley D., Ryan, Edward T., Connelly, Bruce A.
• Primary Examiner(s): Bleutge, John C.
• Assistant Examiner(s): MOORE, MARGARET G
• Application Number:
  US08/156,350
• Time in Patent Office: 624 Days
• Field of Search: 525/443, 525/446, 525/106, 427/387, 427/388.1, 428/447, 428/450
• US Class Current: 428/447
• CPC Class Codes: B05D 2202/25 based on Al
• CPC Class Codes: B05D 2350/00 Pretreatment of the substrate
• CPC Class Codes: B05D 7/16 using synthetic lacquers or varnishes
• CPC Class Codes: B05D 7/51 One specific pretreatment, e.g. phosphatation, chromatation, in combination with one specific coating pretreatment of metallic substrates C23C; pretreatment before coating in general B05D3/00
• CPC Class Codes: C08G 18/5015 having fluorine atoms
• CPC Class Codes: C08G 18/837 by silicon containing compounds
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 2666/28 Non-macromolecular organic substances
• CPC Class Codes: C08L 61/20 Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen with aminophenols C08L61/04
• CPC Class Codes: C09D 133/06 of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
• CPC Class Codes: C09D 167/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C09D167/06 takes precedence
• CPC Class Codes: C25D 11/18 After-treatment, e.g. pore-sealing
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane

Abstract

A coating composition and method for protecting anodized aluminum, and the coated product are disclosed, wherein the coating comprises a crosslinking agent; a film-forming resin selected from the group consisting of polyester polymers, thermosetting acrylic polymers, and mixtures thereof; and an epoxy silane. The combination provides exceptional adhesion of the coating to anodized surfaces as well as good hardness.

Claims

1. Anodized aluminum having a clear coating in which the coating comprises:

the thermosetting reaction product of a crosslinking agent and a film-forming resin component consisting of a member selected from the group consisting of polyester polymers, thermosetting acrylic polymers, and mixtures thereof; and

silane having the structure;

##STR2## where R represents an epoxy terminated group, n is 1 to 10, and X represents a readily hydrolyzable group selected from the group consisting of;

Cl, OCH₃, OC₂ H₅, and OC₂ H₄ OCH₃.

2. The coated product of claim 1 wherein the film-forming resin includes a thermosetting acrylic polymer which is an acrylic/acrylamide copolymer.

3. The coated product of claim 2 wherein the acrylic/acrylamide copolymer is further characterized as a copolymer of ethyl acrylate, styrene, N-butoxymethyl acrylamide, and methacrylic acid.

4. The coated product of claim 3 further including polyester polymer as a modifying resin.

5. The coated product of claim 1 wherein the film-forming resin includes polyester further characterized as being the reaction product of trimethylpentanediol, adipic acid, and isophthalic acid.

6. The coated product of claim 1 wherein the crosslinking agent is melamine.

7. The coated product of claim 6 wherein the melamine is methoxylated melamine.

8. The coated product of claim 1 wherein the silane is selected from the group consisting of gamma-glycidoxypropyltrimethoxysilane and beta-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane.

9. A method for protecting anodized aluminum comprising applying to the anodized surface a clear coating comprising:

a crosslinking agent;

a film-forming resin component consisting of a member selected from the group consisting of polyester polymers, thermosetting acrylic polymers, and mixtures thereof; and

silane having the structure;

##STR3## where R represents an epoxy terminated group, n is 1 to 10, and X represents a readily hydrolyzable group selected from the group consisting of;

Cl, OCH₃, OC₂ H₅, and OC₂ H₄ OCH₃.

10. The coated product of claim 9 wherein the film-forming resin includes a thermosetting acrylic polymer which is an acrylic/acrylamide copolymer.

11. The coated product of claim 10 wherein the acrylic/acrylamide copolymer is further characterized as a copolymer of ethyl acrylate, styrene, N-butoxymethyl acrylamide, and methacrylic acid.

12. The method of claim 11 further including polyester polymer as a modifying resin.

13. The method of claim 9 wherein the film-forming resin includes polyester further characterized as being the reaction product of trimethylpentanediol, adipic acid, and isophthalic acid.

14. The method claim 9 wherein the crosslinking agent is melamine.

15. The method of claim 14 wherein the melamine is methoxylated melamine.

16. The method of claim 9 wherein the silane is selected from the group consisting of gamma-glycidoxypropyltrimethoxysilane and beta-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane.