Two-step pretreatment system and method

Patent metadata

Field	Value
Publication number	US-11725286-B2
Application number	US-201816639327-A
Country	US
Kind code	B2
Filing date	Feb 9, 2018
Priority date	Aug 12, 2016
Publication date	Aug 15, 2023
Grant date	Aug 15, 2023

Abstract

Disclosed is a system for treating a surface of a multi-metal article. The system includes first and second and/or third conversion compositions for contacting at least a portion of the surface. The first conversion composition includes phosphate ions and zinc ions and is substantially free of fluoride. The second conversion composition includes a lanthanide series metal cation and an oxidizing agent. The third conversion composition includes an organophosphate compound, an organophosphonate compound, or combinations thereof that optionally may include at least one transition metal. Methods of treating a multi-metal article using the system also are disclosed. Also disclosed are substrates treated with the system and method.

First claim

We claim:

1. A system for treating a multi-metal article comprising:
(a) a first conversion composition for treating at least a portion of a non-aluminum metal surface of the multi-metal article, the first conversion composition comprising phosphate ions and zinc ions and being substantially free of fluoride; and
(b) a second conversion composition for treating at least a portion of an aluminum metal surface of the multi-metal article, the second conversion composition comprising a lanthanide series metal cation and an oxidizing agent; and/or
(c) a third conversion composition for treating at least a portion of the aluminum surface, the third conversion composition comprising an organophosphate compound, an organophosphonate compound, or combinations thereof;
wherein the multi-metal article comprises (1) an article that comprises the non-aluminum metal surface and the aluminum metal surface, (2) a first article comprises the non-aluminum metal surface and a second article comprises the aluminum metal surface, or (3) both (1) and (2); and
wherein the first conversion composition does not deposit on the aluminum metal surface.

2. The system of claim 1 , further comprising an activating rinse for contacting at least a portion of the surface prior to the contacting with the first conversion composition, the activating rinse comprising a dispersion of metal phosphate particles having a D90 particle size of no greater than 10 μm, wherein the metal phosphate comprises divalent or trivalent metals or combinations thereof.

3. The system of claim 2 , wherein the metal phosphate particles have a D90 particle size of no more than 1 μm.

4. The system of claim 1 , further comprising an activating rinse for contacting at least a portion of the surface prior to the contacting with the first conversion composition, the activating rinse comprising colloidal titanium-phosphate particles.

5. The system of claim 1 , wherein the lanthanide series metal cation is present in the second conversion composition in an amount of 50 ppm to 500 ppm (calculated as metal cation) based on total weight of the second conversion composition.

6. The system of claim 1 , wherein the third conversion composition has a solids content of 0.5% to 15% based on total composition.

7. The system of claim 1 , wherein the third conversion composition has a pH of 3 to 7.

8. The system of claim 1 , wherein the third conversion composition is substantially free of transition metal.

9. The system of claim 1 , wherein the third conversion composition comprises a transition metal cation present in an amount of 50 ppm to 500 ppm based on total weight of the third conversion composition.

10. The system of claim 1 , wherein the organophosphate compound comprises a phosphatized epoxy.

11. The system of claim 1 , wherein the system is substantially free of fluoride.

12. The system of claim 1 , wherein the second conversion composition and/or the third conversion composition is substantially free of copper.

13. A method for treating a multi-metal article comprising:
(a) contacting at least a portion of a non-aluminum metal surface of the multi-metal article with a first conversion composition comprising phosphate ions and zinc ions and being substantially free of fluoride; and
(b) contacting at least a portion of an aluminum metal surface of the multi-metal article with a second conversion composition comprising a lanthanide series metal cation and an oxidizing agent; and/or
(c) contacting at least a portion of the aluminum surface with a third conversion composition comprising an organosphosphonate compound, an organophosphate compound, or combinations thereof;
wherein the multi-metal article comprises (1) an article that comprises the non-aluminum metal surface and the aluminum metal surface, (2) a first article comprises the non-aluminum metal surface and a second article comprises the aluminum metal surface, or (3) both (1) and (2); and
wherein the first conversion composition does not deposit on the aluminum metal surface.

14. The method of claim 13 , further comprising contacting at least a portion of the surface with an activating rinse prior to contacting the surface with the first conversion composition, wherein the activating rinse comprises a dispersion of metal phosphate particles having a D90 particle size of no greater than 10 um, wherein the metal phosphate comprises divalent or trivalent metals or combinations thereof.

15. The method of claim 13 , wherein the contacting with the second conversion composition results in a level of the lanthanide series metal cation on the treated substrate surface of at least 100 counts greater than on a surface of a substrate that is not contacted with the first and second conversion compositions as measured by X-ray fluorescence (as measured using X-Met 7500, Oxford Instruments; operating parametrs 60 second timed assay, 15 Kv, 45 μA, filter 3, T(p)= 1 . 5 μs for lanthanide).

Assignees

• Ppg Ind Ohio Inc

Inventors

• Lemon Steven J
• Martin Justin J
• Sylvester Kevin T
• Votruba-Drzal Peter L
• Post Gordon L

Classifications

• C23C22/66 Primary

  Treatment of aluminium or alloys based thereon · CPC title

• C09D5/12

  Wash primers · CPC title

• C23C22/12

  containing zinc cations · CPC title

• C23C22/361

  containing titanium, zirconium or hafnium compounds · CPC title

• C23C22/56 Primary

  Treatment of aluminium or alloys based thereon · CPC title