Method for forming multilayer coating film

Patent metadata

Field	Value
Publication number	US-12097532-B2
Application number	US-202017766030-A
Country	US
Kind code	B2
Filing date	Sep 10, 2020
Priority date	Oct 3, 2019
Publication date	Sep 24, 2024
Grant date	Sep 24, 2024

Abstract

This invention provides a method for forming a multilayer coating film, comprising applying a base paint (X) having a solids content ratio of 30 to 62 mass % to a substrate to form a base coating film having a cured film thickness of 6 to 45 μm; applying an effect pigment dispersion (Y) having a solids content ratio of 0.1 to 10 mass % to the base coating film to form an effect coating film having a cured film thickness of 0.1 to 5.0 μm; applying a two-component clear paint (Z) containing a hydroxy-containing resin and a polyisocyanate compound to the effect coating film to form a clear coating film; and heating the base coating film, the effect coating film, and the clear coating film to simultaneously cure these coating films; wherein the base paint (X) contains a polyurethane resin (A), an alcohol (B) containing 6 to 12 carbon atoms, and an organic solvent (C) having an HLB of 7 to 9, and the effect pigment dispersion (Y) contains water, a flake-effect pigment (P), a resin emulsion (Q), and cellulose nanofibers (R).

First claim

The invention claimed is:

1. A method for forming a multilayer coating film, comprising the following steps (1) to (4):
(1) applying a base paint (X) having a solids content ratio of 30 to 62 mass % to a substrate to form a base coating film having a cured film thickness of 6 to 45 μm;
(2) applying an effect pigment dispersion (Y) having a solids content ratio of 0.1 to 10 mass % to the base coating film formed in step (1) to form an effect coating film having a cured film thickness of 0.1 to 5.0 μm;
(3) applying a two-component clear paint (Z) containing a hydroxy-containing resin and a polyisocyanate compound to the effect coating film formed in step (2) to form a clear coating film; and
(4) heating the uncured base coating film, the uncured effect coating film, and the uncured clear coating film formed in steps (1) to (3) to simultaneously cure these coating films; wherein

the base paint (X) contains a polyurethane resin (A), an alcohol (B) containing 6 to 12 carbon atoms, and an organic solvent (C) having an HLB of 7 to 9, and
the effect pigment dispersion (Y) contains water, a flake-effect pigment (P), a resin emulsion (Q), and cellulose nanofibers (R).

2. The method for forming a multilayer coating film according to claim 1 , wherein the mass ratio of the content of the alcohol (B) to the content of the organic solvent (C) of (B)/(C) is 0.7 to 3.0.

3. The method for forming a multilayer coating film according to claim 1 , wherein the organic solvent (C) is at least one member selected from the group consisting of propylene glycol monomethyl ether, ethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, diethylene glycol monobutyl ether, and tripropylene glycol monomethyl ether.

4. The method for forming a multilayer coating film according to claim 1 , wherein the base paint (X) further contains a polyester resin (D) having a number average molecular weight of 1500 to 10000.

5. The method for forming a multilayer coating film according to claim 1 , wherein the base paint (X) further contains a nonionic-hydrophilic-group-containing blocked polyisocyanate compound (E).

6. The method for forming a multilayer coating film according to claim 1 , wherein the effect pigment dispersion (Y) further contains a wetting agent (S).

Assignees

• Kansai Paint Co Ltd

Inventors

• Sakai Kenji

Classifications

• C09D175/04

  Polyurethanes · CPC title

• C09D17/00

  Pigment pastes, e.g. for mixing in paints (artists' paints C09D5/06) · CPC title

• B05D5/06

  to obtain multicolour or other optical effects (B05D5/02 takes precedence) · CPC title

• C08G63/20

  Polyesters having been prepared in the presence of compounds having one reactive group or more than two reactive groups · CPC title

• C08G63/918

  Polycarboxylic acids and polyhydroxy compounds in which at least one of the two components contains aliphatic unsaturation · CPC title