Aqueous binder dispersions intended for cathodic electrocoat materials and comprising a crosslinker based on 2,2-dimethyl-1,3-dioxolane-4-methanol-blocked polyisocyanates

Patent metadata

Field	Value
Publication number	US-10501646-B2
Application number	US-201515514406-A
Country	US
Kind code	B2
Filing date	Jul 31, 2015
Priority date	Sep 26, 2014
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

The present invention relates to aqueous binder dispersions for cationic electrocoat materials, comprising as binders amine-modified, hydroxy-functional epoxy resins and comprising as crosslinker at least one fully blocked polyisocyanate blocked at least partly with 2,2-dimethyl-1,3-dioxolane-4-methanol, and also to the use of such cationic electrocoat materials for producing coating systems and to the use of crosslinkers based on polyisocyanates blocked with 2,2-dimethyl-1,3-dioxolane-4-methanol in aqueous binder dispersions.

First claim

What is claimed is:

1. An aqueous binder dispersion for a cathodic electrocoat material, the aqueous binder dispersion comprising
at least one amine-modified hydroxy-functional epoxy resin as a binder, and
at least one fully blocked polyisocyanate blocked at least partly with 2,2-dimethyl-1,3-dioxolane-4-methanol as a crosslinker.

2. The aqueous binder dispersion of claim 1 , wherein, based on the isocyanate groups originally present in the fully blocked polyisocyanate, 50 to 100 mol % of the isocyanate groups are blocked with 2,2-dimethyl-1,3-dioxolane-4-methanol.

3. The aqueous binder dispersion of claim 2 , wherein 90 to 100 mol % of the isocyanate groups are blocked with 2,2-dimethyl-1,3-dioxolane-4-methanol.

4. The aqueous binder dispersion of claim 3 , wherein 100 mol % of the isocyanate groups are blocked with 2,2-dimethyl-1,3-dioxolane-4-methanol.

5. The aqueous binder dispersion of claim 1 , wherein the polyisocyanate is an aromatic polyisocyanate.

6. The aqueous binder dispersion of claim 1 , wherein the polyisocyanate is an oligomeric polyisocyanate.

7. The aqueous binder dispersion of claim 1 , wherein the polyisocyanate has an NCO functionality of 2.4 to 4.

8. The aqueous binder dispersion of claim 1 , wherein the polyisocyanate is based on 4,4′-diphenylmethane diisocyanate.

9. The aqueous binder dispersion of claim 1 , wherein the polyisocyanate is an oligomeric 4,4′-diphenylmethane diisocyanate having an NCO functionality of 2.4 to 4.

10. The aqueous binder dispersion of claim 1 , wherein the blocked polyisocyanate is used in an amount of 5 to 50 wt %, based on the binder.

11. The aqueous binder dispersion of claim 1 , wherein the epoxy resin is prepared in the presence of the crosslinker.

12. A process for cathodic electrocoating of an electrically conductive substrate, the process comprising:
1) immersing the electrically conductive substrate into an aqueous electrocoat material comprising the aqueous binder dispersion of claim 1 and at least one cathodically depositable binder,
2) connecting the electrically conductive substrate as cathode,
3) depositing a coating film on the electrically conductive substrate with direct current, thereby obtaining a coated substrate,
4) removing the coated substrate from the electrocoat material, and
5) baking the deposited coating film.

13. The process of claim 12 , wherein the electrically conductive substrate is an automobile body or a part thereof.

14. An electrocoat material, comprising the aqueous binder dispersion of claim 1 .

Assignees

• Basf Coatings Gmbh

Inventors

• Ott Guenther
• Oberhoff Markus
• Przybilla Silke
• Grosse Brinkhaus Karl-Heinz
• Stoll Dominik

Classifications

• C09D163/00

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

• C09D5/4442

  Binder characterised by functional groups · CPC title

• C09D5/4453 Primary

  characterised by the nature of the curing agent · CPC title

• C25D13/22

  Servicing or operating {apparatus or multistep processes} · CPC title

• C09D5/4438

  Binder based on epoxy/amine adducts, i.e. reaction products of polyepoxides with compounds containing amino groups only · CPC title