METAL SURFACE TREATMENT

Abstract

The instant invention concerns the use of at least one polymer P obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) methacrylic acid; and (iii) at least one 2-hydroxyethyl methacrylate phosphate for treating a metallic surface intended to be coated by a paint, a varnish or an adhesive. The invention also concerns methods of coatings making use of this polymer P, compositions comprising the polymer P and useful for these methods, and the obtained coated materials.

Claims

1. A method, comprising treating a metallic surface intended to be coated by a paint, a varnish or an adhesive with at least one polymer P obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) methacrylic acid; and (iii) at least one 2-hydroxyethyl methacrylate phosphate of Formula (a) below: ##STR00002## wherein n is 0, 1 or 2.

2. The method of claim 1, wherein the polymer P is obtained by radical copolymerization of a mixture having the following molar ratio, based on the total quantity of acrylic acid, methacrylic acid and 2-hydroxyethyl methacrylate phosphates of formula (a): acrylic acid : from 80 to 90% methacrylic acid: 5 to 15% 2-hydroxyethyl methacrylate phosphates: 2 to 6%.

3. The method of claim 1, wherein the polymer P has a molecular weight of at least 7,500 Da.

4. The method according to claim 1, wherein the metal surface is a surface comprising a metal selected from aluminum, steel, zinc, magnesium and their alloys.

5. The method according to claim 4, wherein the metal surface is a surface of aluminum or aluminum alloy.

6. The method according to claim 1, wherein a conversion composition a is applied on the metallic surface for forming a conversion coating thereon, and wherein: said conversion composition include all or part of the polymer P as an additive; and/or the conversion coating is applied on the metallic surface, and then all or part of the polymer P is applied on the conversion coating.

7. The method according to claim 1, wherein all or part of the polymer P is present in a paint, a varnish or a coating applied on the surface.

8. A process for coating a metal surface with a paint, a varnish or an adhesive, comprising a step of treating said surface with at least one composition including at least one polymer P, wherein polymer P is obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) methacrylic acid; and (iii) at least one 2-hydroxyethyl methacrylate phosphate of Formula (a) below: ##STR00003## wherein n is 0, 1 or 2.

9. The process according to claim 8, wherein the process is for coating a metallic surface with a paint.

10. The process according to claim 8, wherein the composition comprising the polymer P is: a conversion composition including a polymer P; and/or a solution or a dispersion of the polymer P; and/or the paint, varnish or adhesive, that comprise a polymer P.

11. A conversion composition, paint, varnish or adhesive composition including at least one polymer P, wherein polymer P is obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) methacrylic acid; and (iii) at least one 2-hydroxyethyl methacrylate phosphate of Formula (a) below: ##STR00004## wherein n is 0, 1 or 2.

12. (canceled)

13. A material comprising a metal surface which is in all or part (i) treated with at least one polymer P and (ii) covered by a paint, a varnish or an adhesive: wherein polymer P is obtained by radical copolymerization of a mixture of (i) acrylic acid; (ii) methacrylic acid; and (iii) at least one 2-hydroxyethyl methacrylate phosphate of Formula (a) below: ##STR00005## wherein n is 0, 1 or 2.

14. The method of claim 3, wherein the polymer P has a molecular weight of 10 kDa to 1500 kDa.

15. The method according claim 7, wherein all or part of the polymer P is present in a paint, a varnish or a coating applied on the surface after application of a conversion coating on the metal surface.

16. The process according to claim 10, wherein the composition comprising the polymer P is a solution or a dispersion of the polymer P applied on the surface after having applied a conversion coating on the surface to be treated.

17. The material according to claim 13, wherein the said material is a material having a metal surface in all or part covered by: at least one coating comprising at least one polymer P; and/or a layer comprising a reaction product of at least one polymer P with a metal of the treated surface or another compound present in the layer.

Description

EXAMPLE

[0048] MIRAPOL® 8801 has been tested in this example, which has been compared to ACUMER 1510.

[0049] Tests have been performed on aluminum alloy panels (AA5005, from Q-Panel), with usual lab equipment (beakers, oven, . . . ), a powder coating installation (GEMA 2C from Industrie Systemes) and a corrosion chamber (Q-FOG CRH 600L, from QFOG).

[0050] In each test, the following protocol has been applied:

[0051] Cleaning and Etching [0052] It was made by dipping each pannel to be tested in a combined cleaning-etching bath, which was a 1L bath is typically made by diluting a commercially available formulation, DBT ALU 200, available from Chemtec Aertec (5 g of DBT ALU 200 into 995 g of water). The pannel was dipped in the cleaning-etching bath for 3 min under light stirring (200 rpm) at 50° C. The pannel was then rinsed with 1 L of de-ionized water.

[0053] Treatment [0054] It was performed by dipping the panel obtained after the cleaning/etching of the previous step in a treatment bath, which was a1L bath made by diluting in water: [0055] zirconium hexafluoride H.sub.2ZrF.sub.6 at a concentration of 200 ppm active (0.02 wt %); and [0056] the additive to be tested (MIRAPOL® 8801 according to the invention; or ACUMER™ 1510 in the comparative examples), at concentrations from 50 ppm active (0.005 wt %) up to 1,000 ppm (0.1 wt %) given in the tables below: [0057] The panel was immerged for 2 min in the treatment bath at 25° C. It was not rinsed. The excess of bath solution was flushed away from the surface with compressed air. The panel was then dried for 30 min in an oven at 60° C.

[0058] Painting: [0059] Each panel was then painted with a polyester white powder paint from RIPOL (BIANCO RAL 9010).

Tests

[0060] Each Panel was then tested according to protocols similar to those described in the following standards listed below: [0061] Acetic acid salt spray: T=35(+/−2)° C., [NaCl]=50(+/−5)g/L, pH=3.1-3.3 (ISO 9227) [0062] Scribing protocol: as described in ISO 17872 [0063] Degree of rusting quoted as described in ISO 4628-3 [0064] Degree of blistering quoted as described in ISO 4628-2

Rusting Results

[0065] (assessed according to ISO 4628-3)

TABLE-US-00001 Polymer ACUMER ™ 1510 Comparative MIRAPOL ® 8801 exposure time 308 h 564 h 758 h 308 h 564 h 758 h 0.005 wt % R1 R3 R3 R1 R1 R3 0.010 wt % R1 R2 R3 R1 R1 R3 0.020 wt % R1 R3 R3 R0 R0 R2 0.100 wt % R1 R2 R2 R0 R1 R2
Whatever the concentration, rusting appears faster with the comparative example.

Blistering Results

[0066] (assessed according to ISO 4628-2)

TABLE-US-00002 Polymer ACUMER ™ 1510 Comparative MIRAPOL ® 8801 exposure time 308 h 564 h 758 h 308 h 564 h 758 h 0.005 wt % 1S1 1S1 1S1 1S1 1S1 2S2 2S1 1S2 2S1 1S1 0.010 wt % 1S1 1S1 2S1 1S1 1S1 2S1 2S1 2S1 2S1 2S1 0.020 wt % 1S1 2S1 3S1 0 0 0 3S1 3S1 0.100 wt % 0 1 little 2S1 1S1 1S1 3S1 blister 2S1 2S1 2S1 3S1
Here again, the results are better with the polymer according to the invention.