Metal pretreatment compositions comprising silanes and organophosporus acids

Patent metadata

Field	Value
Publication number	US-10106689-B2
Application number	US-201615015577-A
Country	US
Kind code	B2
Filing date	Feb 4, 2016
Priority date	Aug 6, 2013
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

The object of the underlying invention consists of an acidic aqueous metal pretreatment solution that comprises amino-functional organosilanes and organophosphorus acids. These types of metal pretreatment solutions effectively reduce temporary corrosion when applied to metal surfaces and in addition confer good adhesion properties for subsequently coated organic lacquers. The invention consequently also encompasses a process for the treatment of metal substrates, especially selected from zinc and zinc-coated steel substrates, wherein metal pretreatment solutions of this invention are applied.

First claim

The invention claimed is:

1. An acidic aqueous metal pretreatment solution with a pH in the range from 2.5 to 5.5 comprising:
a) more than 0.2 wt.-% calculated with respect to the element Si of at least one organosilane with at least one hydrolyzable substituent and one to three non hydrolyzable substituents, wherein at least one of the non hydrolyzable substituents carries at least one amino group, and wherein the total number of substituents at each silicon atom of the organosilanes is four;
b) at least one organophosphorus acid; and
c) at least one complex anion of the elements B, Zr, Hf and/or Si;
wherein c) is present in an amount such that a molar ratio of a total amount of organosilanes calculated with respect to the element Si to a total amount of complex anions of the elements B, Zr, Ti, Hf and/or Si calculated with respect to the elements B, Zr, Ti, Hf and/or Si is in a range from 80 to 500.

2. The metal pretreatment solution according to claim 1 , wherein the fraction of organophosphorus acids based on the total amount of oxyacids of phosphorus is at least 60 mol-% calculated with respect to the element P.

3. The metal pretreatment solution according to claim 1 , wherein the organophosphorus acids are selected from α-aminophosphonic acids that accord with the general formula (II):

wherein n is an integer number of at least 1, but not more than 5; wherein m is an integer number of at least 1, but not more than 5; wherein the substituent Y is selected from —P(═O)(OX) 2 , —OH or —NH 2 ; wherein the residues X are independently from each other are selected from hydrogen, aliphatic groups with not more than 4 carbon atoms, alkaline metal cations, ammonium or quaternary ammonium cations; and wherein at least one residue X is selected from hydrogen.

4. The metal pretreatment solution according to claim 1 , wherein the molar ratio of the amount of organosilanes calculated with respect to the element Si to organophosphorus acids calculated with respect to the element P is at least 0.5:1 and not more than 5:1.

5. The metal pretreatment solution according to claim 1 , further comprising other organosilanes different from a) wherein said other organosilanes comprise d) organosilanes having at least one hydrolyzable substituent and one to three non hydrolyzable substituents, wherein at least one of the non-hydrolyzable substituents carries at least one hydroxyl or oxirane functional group; wherein the total amount of organosilanes calculated with respect to the element Si is not more than 10 wt.-% and
wherein the fraction of organosilanes according to compound a) calculated with respect to the element Si based on the total amount of organosilanes calculated with respect to the element Si is at least 30 mol-%; and the fraction of organosilanes according to compound d) calculated with respect to the element Si based on the total amount of organosilanes is at least 20 mol-%.

6. The metal pretreatment solution according to claim 1 , wherein the at least one organosilane according to component a) is selected from compounds according to the following general structure (I):
(H 2 N−[(CH 2 ) m NH] n (CH 2 ) p ) y —Si—X (4-y)   (I)

wherein the hydrolyzable substituents X are independently from each other selected from alkoxy groups with not more than 4 carbon atoms;
wherein m and p each independently from another are integer numbers in the range from 1 to 4; wherein n is an integer number in the range from 0 to 8; and wherein y is an integer number in the range from 1 to 3.

7. The metal pretreatment solution according to claim 1 additionally comprising organosilanes different from component a) that are selected from organosilanes with at least one hydrolyzable substituent and one to three non hydrolyzable substituents, wherein at least one of the non hydrolyzable substituents carries at least one hydroxyl or oxirane functional group.

8. The metal pretreatment solution according to claim 7 , wherein the fraction of organosilanes with at least one hydrolyzable substituent and one to three non hydrolyzable substituents, wherein at least one of the non hydrolyzable substituents carries at least one hydroxyl or oxirane functional group, calculated with respect to the element Si based on the total amount of organosilanes calculated with respect to the element Si is at least 10 mol-%.

9. The metal pretreatment solution according to claim 1 , wherein the at least one complex anion is selected from oxyfluoroanions or fluoroanions of the elements B, Zr, Ti, Hf and/or Si.

10. The metal pretreatment solution according to claim 1 , wherein the molar ratio of the total amount of organosilanes calculated with respect to the element Si to the total amount of complex anions of the elements B, Zr, Ti, Hf and/or Si calculated with respect to the elements B, Zr, Ti, Hf and/or Si is in a range from 100 to 400.

11. The metal pretreatment solution according to claim 9 , wherein the total amount of complex anions of the elements Zr, Ti, Hf and/or Si calculated with respect to the elements Zr, Ti, Hf and/or Si is not more than 0.05 wt.-%.

12. The metal pretreatment solution according to claim 1 , wherein the amount of acids with a pK A value of above 3.5 for the first deprotonation step is below 0.05 wt.-%.

13. The metal pretreatment solution according to claim 1 , containing less than 0.01 wt.-% of organic polymers, wherein the pH of the aqueous acidic composition is in the range from 2.5 to 4.0.

14. The metal pretreatment solution according to claim 1 additionally comprising at least one organic polymer selected from the group consisting of acrylic polymers, urethane polymers, and a combination thereof.

15. A process for a corrosion-resistant treatment of metals, wherein a metal substrate is brought into contact with a metal pretreatment solution as defined in claim 1 .

16. The process according to claim 15 , wherein the metal substrate is selected from the group consisting of zinc, zinc-coated steel, and a combination thereof.

17. The metal pretreatment solution according to claim 14 wherein the at least one organic polymer comprises a urethane polymer which is a silane-functional urethane polymer that is a reaction product of a diisocyanate, a polyol and the amino-functional organosilane according to component a).

18. An acidic aqueous metal pretreatment solution with a pH in the range from 2.5 to 5.5 and comprising reaction products of a reaction mixture comprising:
a) more than 0.2 wt.-% calculated with respect to the element Si of at least one organosilane with at least one hydrolyzable substituent and one to three non hydrolyzable substituents, wherein at least one of the non hydrolyzable substituents carries at least one amino group, and wherein the total number of substituents at each silicon atom of the organosilanes is four;
b) an aqueous solution of at least one selected from α-aminophosphonic acid and salts thereof; and
c) other organosilanes, different from a), wherein a total amount of organosilanes does not exceed 10 wt.-% and the organosilanes according to a) comprise at least 30 mol-% of the total amount of organosilanes, each calculated with respect to the element Si;
with the proviso that the acidic aqueous metal pretreatment solution contains less than 0.03 wt. % of reaction products that are alcohols released upon the condensation and hydrolyzation of the at least one hydrolyzable substituent on the organosilane.

Assignees

• Henkel Ag & Co Kgaa

Inventors

• Wolpers Michael
• Stodt Juergen
• Sundermeier Uta
• Zhang Qi
• Wan Junjun

Classifications

• C23C2222/20

  Use of solutions containing silanes · CPC title

• C23C22/361

  containing titanium, zirconium or hafnium compounds · CPC title

• C23C22/34

  containing fluorides or complex fluorides · CPC title

• C23C22/07

  containing phosphates · CPC title

• C09D5/086 Primary

  Organic or non-macromolecular compounds · CPC title