Low bake autodeposition coatings

Patent metadata

Field	Value
Publication number	US-11426762-B2
Application number	US-201816021954-A
Country	US
Kind code	B2
Filing date	Jun 28, 2018
Priority date	Dec 31, 2015
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

Autodeposition coating compositions that deposit uncured coatings, on metallic surfaces of a substrate, which are curable at oven temperatures of less than 130° C., are provided as well as autodeposition methods, compositions and components for depositing such autodeposition coatings. More particularly, the invention relates to autodeposition coatings that cure at temperatures lower than conventional autodeposition coatings, while achieving chemical and corrosion performance comparable to higher temperature cure autodeposition coatings, as well as being directed to autodeposition coating compositions possessing improved storage stability and coating thermal stability, and articles of manufacture having cured and uncured autodeposited coatings deposited thereon.

First claim

We claim:

1. An autodeposition coating process comprising steps of:
(a) contacting an article having an active metal surface with an autodepositing liquid bath composition comprising water and:
(A) dispersed or both dispersed and dissolved film forming polymer comprising active hydrogens present in a concentration of at least 1.0% of the composition;
(B) a surfactant component present in sufficient quantity to emulsify component (A);
(C) a curing component comprising at least one latent cross-linking agent chemically reactive with the active hydrogens of component (A) at temperatures of 129° C. or less and stable at pH ranges of 1.5 to about 6 comprising at least one isocyanate; and
(D) a dissolved accelerator component;
wherein the autodepositing liquid bath composition is capable of depositing on an active metal surface and curing upon heating by cross-linking at temperatures of 129° C. or less, for a sufficient time to form an uncured autodeposited coating on the metal surface,

(b) removing the article from contact with the autodepositing liquid bath composition,
(c) rinsing the uncured autodeposited coating, wherein the rinsing step (c) comprises rinsing with water followed by a post-catalysis step comprising applying an aqueous catalyst solution to the uncured autodeposited coating, wherein the aqueous catalyst solution comprises a catalyst for a urethane-type reaction of the isocyanate with the active hydrogens comprising at least one of a cyclic amidine, a tertiary amine, a quinuclidine, a triazine, an imidazole, or a combination thereof; and
(d) heating the uncured autodeposited coating to a temperature of at least 55° C. and no more than 129° C. for a time sufficient to thereby form a cured autodeposited coating.

2. The autodeposition coating process according to claim 1 , wherein the at least one latent cross-linking agent comprises an isocyanate blocked with a pyrazole, a malonate, or a combination thereof.

3. The autodeposition coating process according to claim 2 , wherein the isocyanate comprises an aromatic isocyanate and/or aliphatic isocyanate.

4. The process according to claim 2 , wherein the pyrazole comprises 3,5-dimethyl pyrazole (DMP) or the malonate comprises diethyl malonate (DEM).

5. The process according to claim 4 , wherein the isocyanate comprises at least one of methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), derivatives thereof, or combinations thereof.

6. The autodeposition coating process according to claim 1 , wherein the autodepositing liquid bath composition of step (a) further comprises a component of solvent, other than materials that constitute any part of any of the preceding components, selected from propylene carbonate, butyl benzoate, butylene carbonate, butoxyethanol acetate, 2,2,4-trimethyl-1,3-pentanediol mono(2-methylpropanoate) or a combination thereof.

7. The autodeposition coating process according to claim 1 , wherein the rinsing step (c) comprises rinsing with water followed by a post-treatment step.

8. The autodeposition coating process according to claim 7 , wherein the post-treatment step comprises rinsing the uncured autodeposited coating with an aqueous post-treatment solution comprising at least one water-soluble compound of zirconium or titanium and/or sodium acetylacetonate hydrate present in a range of 0.001 g/l to about 10.0 g/l.

9. The autodeposition coating process according to claim 8 , wherein the heating step (d) has a final heating temperature in a range of at least 60° C. to about 129° C., for a time of about 3 to about 60 minutes.

10. The autodeposition coating process according to claim 1 , wherein concentration of a total of the catalyst present is about 0.1 g/l to about 10.0 g/l.

11. The process of claim 1 , wherein the film-forming polymer is a dispersed epoxy-acrylate having a particle size of 300 nm or less.

12. An autodeposition coating process comprising steps of:
(a) contacting an article having an active metal surface with an autodepositing liquid bath composition comprising water and:
(A) dispersed or both dispersed and dissolved film forming polymer comprising active hydrogens present in a concentration of at least 1.0% of the composition;
(B) a surfactant component present in sufficient quantity to emulsify component (A);
(C) a curing component comprising at least one latent cross-linking agent chemically reactive with the active hydrogens of component (A) at temperatures of 129° C. or less and stable at pH ranges of 1.5 to about 6 comprising at least one isocyanate; and
(D) a dissolved accelerator component;
wherein the autodepositing liquid bath composition is capable of depositing on an active metal surface and curing upon heating by cross-linking at temperatures of 129° C. or less, for a sufficient time to form an uncured autodeposited coating on the metal surface,

(b) removing the article from contact with the autodepositing liquid bath composition,
(c) rinsing the uncured autodeposited coating, wherein the rinsing step (c) comprises rinsing with water followed by a post-catalysis step comprising applying an aqueous catalyst solution to the uncured autodeposited coating, wherein the aqueous catalyst solution comprises a catalyst for a urethane-type reaction of the isocyanate with the active hydrogens, wherein the catalyst comprises at least one of 1,3,5-tris(3(dimethylamino)propyl)-hexahydro-s-triazine, 1,8-diazabicyclo[5.4.0]undec-7-ene, dicyandiamide, 1,2-dimethylimidazole, or combinations thereof; and

(d) heating the uncured autodeposited coating to a temperature of at least 55° C. and no more than 129° C. for a time sufficient to thereby form a cured autodeposited coating.

Assignees

• Henkel Ag & Co Kgaa

Inventors

• Du Libin
• Ahmed Bashir M
• Harkal Umesh D
• Abu-Shanab Omar Lutfi

Classifications

• C09D4/06

  {Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond} in combination with a macromolecular compound other than an unsaturated polymer of groups C09D159/00 - C09D187/00 · CPC title

• C08F283/10

  on to polymers containing more than one epoxy radical per molecule {(C08F283/004 takes precedence)} · CPC title

• B05D3/0254

  After-treatment · CPC title

• C09D163/00

  Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins · CPC title

• C09D5/08

  Anti-corrosive paints · CPC title