Use of an adhesion promoter obtainable as a reaction product of a di- or poly amine with α,β-unsaturated carboxylic acid derivatives for metal surface treatment

Abstract

The invention relates to use of an adhesion promoting organic compound comprising at least one tertiary amine group, bonded via a bridge-constituting divalent radical, with the carbonyl carbon atom of an amide group, wherein the bridge-constituting divalent radical comprises two carbon atoms as bridge atoms, for anticorrosion pretreatment of metallic materials before painting and to aqueous compositions containing the adhesion promoting organic compound which generate conversion layers based on the elements Zr, Ti and/or Si. The present invention further comprises a process for anticorrosion coating of components at least partly manufactured from metallic materials comprising a pretreatment using acidic aqueous compositions according to the invention and subsequent painting. In a further aspect, the invention relates to a metallic substrate having a mixed organic/inorganic coating consisting of oxides, hydroxides and/or oxyfluorides of the elements Zr, Ti and/or Si and of the adhesion promoting organic compounds.

Claims

1. An acidic aqueous composition for the anti-corrosion pretreatment of metal surfaces, containing (A) at least one water-soluble compound of the elements Zr, Ti and/or Si; (B) at least one source of fluoride ions; and (C) at least one adhesion promoter comprising an organic compound having at least one tertiary amine group that is linked via a bridge-forming divalent functional group to the carbonyl carbon atom of an amide group, wherein the bridge-forming divalent functional group has two carbon atoms as bridge atoms, wherein at least 0.005 g/kg, but no more than 5 g/kg of organic compounds that are adhesion promoters according to component (C) are contained as component (C); wherein the adhesion promoter according to component (C) additionally comprises at least one secondary amine group which is linked via at least one bridge-forming divalent functional group to a carbonyl carbon atom of an amide group, the bridge-forming divalent functional group having two carbon atoms as bridge atoms.

2. The composition according to claim 1, wherein the adhesion promoter according to component (C) additionally comprises at least one primary amine group.

3. The composition according to claim 1, wherein the molar ratio of total number of primary and secondary amine groups to number of tertiary amine groups with respect to total of the adhesion promoters according to component (C) is less than 5, but more than 0.75.

4. The composition according to claim 1, wherein the two carbon atoms of the bridge-forming functional group are in turn substituted, independently of one another, with functional groups selected from hydrogen, branched or unbranched aliphatic compounds having no more than 6 carbon atoms, alkylcarboxylic acids having no more than 5 carbon atoms, or with divalent aliphatic functional groups having at least 3, but no more than 5, carbon atoms that interlink the two bridge atoms.

5. The composition according to claim 1, wherein the molecular weight of the adhesion promoter according to component (C) is greater than 200 g/mol.

6. The composition according to claim 1, wherein the total quantity of all of the adhesion promoters according to component (C) contained in the composition has a weight-average molar mass greater than 500 g/mol.

7. The composition according to claim 1, wherein the adhesion promoter is a reaction product of a quantity of one or more di- and/or polyamines with a quantity of an α, β-unsaturated carboxylic acid, ester or amide thereof, reacted in a one-pot reaction wherein the quantity of di- and/or polyamines is provided first and the quantity of the α, β-unsaturated carboxylic acid, ester or amide thereof is added gradually.

8. The composition according to claim 7, wherein the molar ratio of the di- and/or polyamines to the α, β-unsaturated carboxylic acid, ester, or amide thereof, is no more than 2, but no less than 0.5.

9. The composition according to claim 7, wherein the one or more di- and/or polyamines are selected from one or more alkylene diamines having no more than 12 carbon atoms and one or more polyalkylene amines having no more than 12 carbon atoms between neighboring amine groups and combinations thereof; and the α, β-unsaturated carboxylic acid, ester, or amide thereof, are selected from (meth)acrylic acid methyl ester and (meth)acrylic acid ethyl ester and combinations thereof.

10. The composition according to claim 1, wherein a total of at least 0.005 g/kg, but no more than 1 g/kg of water-soluble compounds of the elements Zr, Ti and/or Si calculated as Zr are contained as component (A).

11. The composition according to claim 1, wherein a weight ratio of component (A) calculated as Zr to component (C) is no less than 0.2, but no more than 10.

12. A method for an anti-corrosion coating of components made at least in part of metal materials, comprising steps of i) contacting at least some surfaces of a component with an aqueous composition according to claim 1, the at least some surfaces being made of metal materials; and then ii) painting at least some of the surfaces contacted with the aqueous composition in step i).

13. A painted metal substrate comprising a mixed organic/inorganic intermediate layer consisting of oxides, hydroxides and/or oxyfluorides of the elements Zr, Ti and/or Si and organic compounds having at least one tertiary amine group that is linked via a bridge-forming divalent functional group to the carbonyl carbon atom of an amide group, wherein the bridge-forming divalent functional group has two carbon atoms as bridge atoms and at least one secondary amine group which is linked via at least one bridge-forming divalent functional group to a carbonyl carbon atom of an amide group, the bridge-forming divalent functional group having two carbon atoms as bridge atoms.

14. A method of improving paint adhesion to metal surfaces comprising pretreating the metal surfaces before painting with a pretreatment comprising an adhesion promoter selected from organic compounds having at least one tertiary amine group that is linked via a bridge-forming divalent functional group to the carbonyl carbon atom of an amide group, the bridge-forming divalent functional group having two carbon atoms as bridge atoms, and at least one secondary amine group which is linked via at least one bridge-forming divalent functional group to a carbonyl carbon atom of an amide group, the bridge-forming divalent functional group having two carbon atoms as bridge atoms; wherein the adhesion promoter is present in an amount of at least 0.005 g/kg, but no more than 5 g/kg; wherein the organic compounds have a weight-average molar mass that is greater than 500 g/mol.

15. An acidic aqueous composition for the anti-corrosion pretreatment of metal surfaces, containing (A) at least one water-soluble compound of the elements Zr, Ti and/or Si; (B) at least one source of fluoride ions; and (C) at least one adhesion promoter comprising an organic compound having at least one tertiary amine group that is linked via a bridge-forming divalent functional group to the carbonyl carbon atom of an amide group, wherein the bridge-forming divalent functional group has two carbon atoms as bridge atoms, wherein at least 0.005 g/kg, but no more than 5 g/kg of organic compounds that are adhesion promoters according to component (C) are contained as component (C); the composition further comprising at least a source of copper ions.

16. The composition according to claim 15, wherein the source of copper ions is a water-soluble salt.

17. The composition according to claim 15, further comprising at least 0.1 g/kg of zinc ions.

18. The composition according to claim 17, further comprising an inorganic nitrogen compound.

19. The composition according to claim 18, wherein the inorganic nitrogen compound is a water-soluble nitrate salt.

20. A method of improving paint adhesion to metal surfaces comprising pretreating the metal surfaces before painting with a pretreatment according to claim 15.

21. A painted metal substrate made according to the method of claim 20.

Description

PRACTICAL EXAMPLES

(1) Sheets of different metal materials were cleaned, pretreated and electrocoated according to the following sequence. A. Alkaline degreasing at pH 10.5: 1 wt. % BONDERITE® C-AK 1561 (Henkel) in deionized water (κ<1 μScm.sup.−1); Application by spraying at 60° C. for 180 seconds at 1.5-2.0 bar B. Step of rinsing with deionized water (κ<1 μScm.sup.−1) at 20° C. C. Alkaline immersion cleaning at pH 11.5-11.7: 4 wt. % BONDERITE® C-AK 2011 (Henkel) 0.4 wt. % BONDERITE® C-AD 1580 (Henkel) in deionized water (κ<1 μScm.sup.−1); Application by dipping at 56° C. for 180 seconds D. Step of rinsing with deionized water (κ<1 μScm.sup.−1) at 20° C. E. Conversion treatment with acidic aqueous composition according to exemplary formulations E1-E7 in table 2: Application by dipping at 35° C. F. Step of rinsing with deionized water (κ<1 μScm.sup.−1) at 20° C. G. Cathodic electrocoating (CathoGuard 800, BASF Coatings): Layer thickness of 20-22 μm after drying in the stoving oven at 180° C. for 35 minutes
Preparation of an Aqueous Concentrate of Adhesion Promoter C1:

(2) 210.34 parts by weight of 1,2-diaminoethane were first provided in a glass flask having a stirring system. 301.44 parts by weight of methyl acrylate were then added in a dropwise manner, with stirring, according to the intended molar ratio of 1:1 between the reactants. The internal temperature rose and was kept at 65 to 70° C. in the reaction mixture during the dropwise addition by applying external cooling and adjusting the drop rate.

(3) After the addition of the quantity of methyl acrylate, the condensation phase was initiated by heating the reaction mixture to above 120° C. within half an hour at a constant heating rate, but only to the jacket temperature at which the formation of a condensate became clearly visible under the prevailing reflux conditions (initial temperature of condensation). After the initial temperature was reached, the jacket temperature was maintained for another 90 minutes under reflux conditions. During this time, the temperature of the reaction mixture dropped to approximately 90° C. The reflux conditions were then eliminated, and a switch was made to distillation mode. The jacket temperature was increased gradually for this purpose to 165° C. while the methanol was being removed, and was kept at this maximum temperature for 30 minutes. The entire condensation phase lasted for 285 minutes.

(4) The reaction mixture was then cooled to 100° C., and a quantity of water (κ<1 μScm.sup.1) was added with vigorous stirring that was such that a 10 wt. % aqueous concentrate of the relevant adhesion promoter was obtained.

(5) Table 1 shows the preparation conditions of the other adhesion promoters C2-C5 on the basis of which the cited concentrates C2-C5 were obtained, the application solutions were formulated according to examples E1-E7 (see table 2), and sheets of cold-rolled steel (CRS), hot-dip galvanized (HDG) steel and aluminum were pretreated and electrocoated according to the process sequence defined above. The results with respect to the anti-corrosion effect are shown in table 3.

(6) TABLE-US-00001 TABLE 1 Preparation of aqueous concentrates containing adhesion promoters C1-C5 C1 C2 C3 C4 C5 Acrylate.sup.1 MA EA EA EA EA Molar ratio.sup.2 1 1 0.5 0.75 1.5 Duration.sup.3/minutes 285 325 325 335 290 .sup.1methyl acrylate (MA); ethyl acrylate (EA): initial temperature 140° C. .sup.2ethylene diamine:acrylate .sup.3duration of the condensation phase

(7) TABLE-US-00002 TABLE 2 Application solutions for pretreatment according to process step E E1 E2 E3 E4 E5 E6 E7 Zr.sup.1/mgkg.sup.−1 150 150 150 150 150 150 150 Adhesion promoter.sup.2 — C1 C2 C3 C4 C5 C1 Cu.sup.3/mgkg.sup.−1 20 20 20 20 20 20 25 Zn.sup.4/mgkg.sup.−1 600 600 600 600 600 600 600 NO.sub.3/mgkg.sup.−1 6000 6000 6000 6000 6000 6000 6000 Fluoride.sup.5/mgkg.sup.−1 25 25 25 25 25 25 25 pH 4.2 4.2 4.2 4.2 4.2 4.2 4.5 Duration/seconds 180 180 180 180 180 180 600 Zr thickness.sup.6/mgm.sup.−2 119 70 88 100 86 72 178 Cu thickness.sup.7/mgm.sup.−2 48 16 20 36 20 8 57 .sup.1source: H.sub.2ZrF.sub.6 .sup.2in each case 100 mgkg.sup.−1 .sup.3source: Cu(NO.sub.3).sub.2 .sup.4source: Zn(NO.sub.3).sub.2 .sup.5as free fluoride directly in application solution determined by means of ion-selective electrode with calibrated potentiometric combination electrode (WTW, inoLab ®, pH/IonLevel 3) .sup.6,7determined by means of an X-ray fluorescence analyzer (Thermo Fisher Scientific, Niton ® XL3t 900)
Anti-Corrosion Results:

(8) First of all, at least equivalent corrosion results were always able to be achieved on all substrates in comparison with the base formulation E1. The improvement of the corrosion values manifests itself clearly in the presence of adhesion promoters C1-C5 on the substrate CRS, in particular for adhesion promoters in which the molar ratio of acrylate to amine is above 0.5 and below 1.5 (E2, E3 and E5). For these examples according to the invention, a significant improvement in the corrosive disbonding on steel was observed. Another significant aspect is that of ensuring good adhesion values even after a comparatively long 10-minute pretreatment on steel (E3 vs. E7).

(9) TABLE-US-00003 TABLE 3 Anti-corrosion results after paint coat build-up Corrosive delamination.sup.* at the intersection after storage in the alternating climate test VW according to PV1210: E1 E2 E3 E4 E5 E6 E7 on CRS Corrosion/mm 1.2 0.9 0.8 1.6 0.7 1.4 1.1 Delamination/mm 3.5 0.9 0.8 2.6 0.7 1.4 1.3 Stone impact 5.0 2.5 2.5 5.0 2.5 5.0 3.7 on HDG Corrosion/mm 2.8 3.0 2.8 2.6 3.3 3.1 5.4 Delamination/mm 2.8 3.0 2.8 2.6 3.3 3.1 5.4 Stone impact 5.0 5.0 5.0 4.8 5.0 5.0 4.5 Filiform test.sup.# after storage according to DIN EN 3665: Maximum thread length 1.0 1.5 0.6 1.0 0.9 0.9 1.2 Average thread length 0.1 0.1 0.1 0.1 0.1 0.1 0.1 .sup.*corrosion and delamination according to DIN EN ISO 4628-8; stone impact test according to DIN EN ISO 20567-1 .sup.#thread lengths in mm according to Daimler PAPP PWT 3002