Corrosion and alkali-resistant compositions and methods for using the same

• US 7,141,619 B2
• Filed: 06/30/2004
• Issued: 11/28/2006
• Est. Priority Date: 11/06/2002
• Status: Expired due to Term

• Current Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Original Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Inventors: Pawlik, Michael J., Nugent, Richard M Jr., Jones, Dennis W., Le Disert, Yves, Deronne, Laurent, Gray, Ralph C.
• Primary Examiner(s): SELLERS, ROBERT E
• Application Number:
  US10/880,942
• Publication Number:
  US 20050020733A1
• Time in Patent Office: 881 Days
• Field of Search: 528/108, 528/398, 428/413, 428/418, 427/386
• US Class Current: 523/402
• CPC Class Codes: C08G 59/1488 containing phosphorus
• CPC Class Codes: C08G 59/4071 phosphorus containing compounds
• CPC Class Codes: C08L 2666/16 Addition or condensation polymers of aldehydes or ketones according to C08L59/00 - C08L61/00; Derivatives thereof
• CPC Class Codes: C08L 2666/40 Phosphorus-containing compounds
• CPC Class Codes: C09D 163/00 Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• CPC Class Codes: C09D 5/08 Anti-corrosive paints
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/31511 Of epoxy ether
• CPC Class Codes: Y10T 428/31515 As intermediate layer
• CPC Class Codes: Y10T 428/31522 Next to metal
• CPC Class Codes: Y10T 428/31529 Next to metal
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

A corrosion resistant, alkali resistant coating composition is disclosed. The composition comprises a binder comprising a reaction product of an epoxy-containing material and a phosphorus-containing material together with a curing agent. Aminoplasts, especially melamine-based aminoplasts, are particularly suitable curing agents. A source of silicon can optionally be included. The compositions also provide excellent adhesion and can be used with or without a weldable primer. The compositions are applied to and cured on a metal substrate.

Claims

1. An aqueous-based composition comprising:

a) the reaction product of one or more epoxy-containing materials and phosphoric acid; and

b) a curing agent, and

c) water,

wherein the composition has a volatile organic compound content of less than 2.4 as determined by Method 24,

wherein the equivalent ratio of the phosphoric acid to epoxy-containing material is between 1.6;

1 and 5;

1,

wherein the composition comprises <

1 weight percent of conductive pigment, and

wherein the composition is capable of producing a coating layer on a substrate, wherein the layer has (i) a thickness of less than or equal to 2.2 microns, and (ii) 10 percent or less coating removal when tested according to ASTM E643 or ASTM D2794-93.

2. The composition of claim 1, wherein the epoxy-containing material is a polyglycidyl ether of a polyhydric phenol.

3. The composition of claim 2, wherein the polyhydric phenol is Bisphenol A.

4. The composition of claim 1, wherein the number average molecular weight of the epoxy-containing material is 220 to 25,000, as determined by multiplying the epoxy equivalent by the epoxy functionality.

5. The composition of claim 4, wherein the molecular weight of the epoxy-containing material is 220 to 4500.

6. The composition of claim 1, wherein the equivalent ratio of the phosphoric acid to epoxy-containing material is between 1.6:

1 and 3.5;

1.

7. The composition of claim 1, wherein the curing agent is selected from the group consisting of aminoplast resins, polyisocyanates, polyacids, organometallic complexed materials, polyamines, and polyamides.

8. The composition of claim 7, wherein the curing agent is an aminoplast.

9. The composition of claim 8, wherein the aminoplast is a melamine-formaldehyde condensate.

10. The composition of claim 9, wherein the melamine-formaldehyde condensate comprises at least 40 weight percent of imino groups.

11. The composition of claim 1, wherein the number average molecular weight of a) is from 1000 to 5000.

12. The composition of claim 1, wherein the weight percent of (b) is from 5 to 25, based on the total weight of (a) and (b).

13. The composition of claim 1, further comprising one or more corrosion resistant pigments.

14. The composition of claim 1, wherein said composition is aqueous-based.

15. The composition of claim 1, wherein said composition is solvent-based.

16. A process for coating a metal substrate comprising:

a) applying the composition of claim 1 to the metal substrate, wherein the composition is at a temperature of 10°

C. to 85°

C.;

b) curing the coating composition on the metal sheet.

17. The process of claim 16, wherein the metal substrate is selected from the group comprising ferrous metals, non-ferrous metals, and combinations thereof.

18. The process of claim 16, wherein the metal substrate is galvanized before application of the composition.

19. A metal substrate coated by the process of claim 16.

20. A coating layer combination comprising an anti-corrosion layer formed from the composition of claim 1, directly adjacent to a weldable coating layer comprising an electroconductive pigment and a binder.

21. The composition of claim 1, further comprising (c) an amine.

22. The composition of claim 8, wherein the pH of the composition is at least about 7.0.

23. The composition of claim 22, wherein the pH of the composition is from 7.0 to 12.0.

24. The composition of claim 22, further comprising (c) ammonia.

25. The composition of claim 1, wherein the epoxy-containing material and the phosphoric acid are reacted together by the reverse phosphatization reaction in which the epoxy-containing material is added to the phosphoric acid.