Method for manufacturing a cationic electrodeposition coating composition

Patent metadata

Field	Value
Publication number	US-10316200-B2
Application number	US-201715426128-A
Country	US
Kind code	B2
Filing date	Feb 7, 2017
Priority date	Feb 8, 2016
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

An object of the present invention is to find a method for producing a cationic electrodeposition coating composition that is excellent in storage stability, low-temperature curability, finished appearance, and corrosion resistance, and to provide a coated article excellent in these properties. The method for producing a cationic electrodeposition coating composition comprises mixing three components, i.e., an aqueous dispersion of an amino group-containing epoxy resin (A), an aqueous dispersion of a blocked polyisocyanate compound (B), and a pigment dispersion paste (C), wherein the aqueous dispersion of a blocked polyisocyanate compound (B) comprises a blocked polyisocyanate compound (b) and an emulsifier.

First claim

The invention claimed is:

1. A method for producing a cationic electrodeposition coating composition, comprising mixing an aqueous dispersion of an amino group-containing epoxy resin (A), an aqueous dispersion of a blocked polyisocyanate compound (B), and a pigment dispersion paste (C), wherein the aqueous dispersion of the blocked polyisocyanate compound (B) comprises a blocked polyisocyanate compound (b) and an emulsifier.

2. The method for producing a cationic electrodeposition coating composition according to claim 1 , wherein the emulsifier is present in an amount of 0.01 to 40 mass % based on the resin solids content of the aqueous dispersion (B).

3. The method for producing a cationic electrodeposition coating composition according to claim 2 , wherein the emulsifier is a cationic emulsifier.

4. The method for producing a cationic electrodeposition coating composition according to claim 2 , wherein the blocked polyisocyanate compound (b) is obtained by reacting an isocyanate compound (b-1) with a blocking agent (b-2), and wherein the emulsifier has an active hydrogen group content of 50 mol % or less based on the isocyanate group content in the polyisocyanate compound (b-1).

5. The method for producing a cationic electrodeposition coating composition according to claim 1 , wherein the blocked polyisocyanate compound (b) is obtained by reacting an isocyanate compound (b-1) with a blocking agent (b-2), and wherein the blocking agent (b-2) is at least one member selected from the group consisting of pyrazole compounds, active methylene compounds, oxime compounds, phenol compounds, lactam compounds, and alcohol compounds.

6. The method for producing a cationic electrodeposition coating composition according to claim 1 , wherein a gel fraction using the cationic electrodeposition coating composition produced by the method is 90% or more, wherein the gel fraction is measured as follows:
the cationic electrodeposition coating composition is applied to a metal plate by electrodeposition to provide a film thickness after cure of 20 μm, and a resulting film is heated at 120° C. for 30 minutes to obtain a cured coating film (Wa);
the mass of the cured coating film (Wa) is measured;
the cured coating film (Wa) is immersed in acetone and heated under reflux for 5 hours;
after the immersion in acetone, the coating film (Wa) is dried at 110° C. for 1 hour to obtain a coating film (Wb), and the mass of the coating film (Wb) is measured; and
the gel fraction is determined according to the following equation:
Gel fraction (%)=( Wb/Wa )×100.

7. A method for forming a coating film, comprising applying the cationic electrodeposition coating composition obtained by the method according to claim 1 to a metal substrate by electrodeposition to form a coating film and baking the film at a temperature of 160° C. or less.

8. A method for forming a coating film, comprising applying the cationic electrodeposition coating composition obtained by the method according to claim 1 to a metal substrate by electrodeposition to form a coating film and baking the film at a temperature of 80 to 130° C.

Assignees

• Kansai Paint Co Ltd

Inventors

• Iijima Hideki
• Hanaoka Toshiyuki

Classifications

• C09D5/4453 Primary

  characterised by the nature of the curing agent · CPC title

• C25D13/16

  Wires; Strips; Foils · CPC title

• C09D5/4438

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

• C09D5/4457

  containing special additives, e.g. pigments, polymeric particles · CPC title

• C25D13/04

  with organic material · CPC title