Method for forming multilayer coating film

Patent metadata

Field	Value
Publication number	US-9404010-B2
Application number	US-201314423525-A
Country	US
Kind code	B2
Filing date	Jun 24, 2013
Priority date	Sep 20, 2012
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

An object of the present invention is to provide a method for forming a multilayer coating film, capable of achieving excellent curability under low-temperature, short-time conditions, and forming a multilayer coating film having excellent chipping resistance and an excellent finished appearance. This method comprises sequentially applying an aqueous first colored coating composition (X), an aqueous second colored coating composition (Y), and a clear coating composition (Z) to a substrate, and simultaneously bake-curing the resulting multilayer coating film. In this method, the aqueous first colored coating composition (X) comprises an aqueous film-forming resin (A) and a specific blocked polyisocyanate compound (B), and the clear coating composition (Z) comprises a hydroxy-containing acrylic resin (K) having a hydroxy value in a specific range, a polyisocyanate compound (L), and an organometallic catalyst (M) containing a metal compound (M1) selected from a specific range and an amidine compound (M2).

First claim

The invention claimed is:

1. A method for forming a multilayer coating film, the method comprising:
applying an aqueous first colored coating composition (X) to a substrate to form a first colored coating film;
applying an aqueous second colored coating composition (Y) to the uncured first colored coating film to form a second colored coating film;
applying a clear coating composition (Z) to the uncured second colored coating film to form a clear coating film; and
simultaneously curing the uncured first colored coating film, the uncured second colored coating film, and the uncured clear coating film,

wherein the aqueous first colored coating composition (X) comprises an aqueous film-forming resin (A) and a blocked polyisocyanate compound (B) having at least one blocked isocyanate group selected from blocked isocyanate groups represented by Formula (I) below:

wherein R 1 represents isopropyl, R 2 , R 4 , and R 5 each independently represent C 1-12 hydrocarbon, and R 3 represents linear or branched C 1-12 alkylene,
blocked isocyanate groups represented by Formula (II) below:

wherein R 2 , R 3 , R 4 , and R 5 are as defined above, and
blocked isocyanate groups represented by Formula (III) below:

wherein R 2 , R 3 , R 4 , and R 5 are as defined above, and R 6 represents isopropyl, and wherein the clear coating composition (Z) comprises a hydroxy-containing acrylic resin (K) having a hydroxy value of 85 to 215 mg KOH/g, a polyisocyanate compound (L), and an organometallic catalyst (M) containing a metal compound (M1) containing one or more metals selected from the group consisting of zinc, tin, zirconium, bismuth, lead, cobalt, manganese, titanium, aluminum, and molybdenum, and an amidine compound (M2).

2. The method for forming a multilayer coating film according to claim 1 , wherein the blocked polyisocyanate compound (B) is obtainable by reacting a blocked polyisocyanate compound (b3-1) having a blocked isocyanate group represented by Formula (IV) below:

wherein each R 1 is as defined above, and are identical or different,
with a secondary alcohol (b4) represented by Formula (VI) below:

wherein R 2 , R 3 , R 4 , and R 5 are as defined above.

3. The method for forming a multilayer coating film according to claim 1 , wherein the blocked polyisocyanate compound (B) is obtainable by reacting a blocked polyisocyanate compound (b3-2) having a blocked isocyanate group represented by Formula (V) below:

wherein R 6 is as defined above, and R 7 represents C 1-12 hydrocarbon, with a secondary alcohol (b4).

4. The method for forming a multilayer coating film according to claim 1 , wherein the blocked polyisocyanate compound (B) is a blocked polyisocyanate compound (B′) having a hydrophilic group.

5. The method for forming a multilayer coating film according to claim 1 , wherein the hydroxy-containing acrylic resin (K) comprises a secondary hydroxy-containing polymerizable unsaturated monomer (k1-1) in an amount of 50 to 100 mass %, based on the total mass of hydroxy-containing polymerizable unsaturated monomer (k1).

6. The method for forming a multilayer coating film according to claim 1 , wherein the hydroxy-containing acrylic resin (K) has a weight average molecular weight in the range of 2,000 to 50,000.

7. The method for forming a multilayer coating film according to claim 1 , wherein the metal compound (M1) is a carboxylic acid metal salt compound.

8. The method for forming a multilayer coating film according to claim 1 , wherein the organometallic catalyst (M) is used in an amount of 0.05 to 5 mass %, based on the total mass of the hydroxy-containing acrylic resin (K) and the polyisocyanate compound (L).

9. An article having a multilayer coating film formed by the method for forming a multilayer coating film of claim 1 .

10. An article having a multilayer coating film formed by the method for forming a multilayer coating film of claim 2 .

11. An article having a multilayer coating film formed by the method for forming a multilayer coating film of claim 3 .

12. An article having a multilayer coating film formed by the method for forming a multilayer coating film of claim 4 .

13. An article having a multilayer coating film formed by the method for forming a multilayer coating film of claim 5 .

14. An article having a multilayer coating film formed by the method for forming a multilayer coating film of claim 6 .

15. An article having a multilayer coating film formed by the method for forming a multilayer coating film of claim 7 .

16. An article having a multilayer coating film formed by the method for forming a multilayer coating film of claim 8 .

Assignees

• Kansai Paint Co Ltd

Inventors

• Iwata Naoyuki
• Yamashita Fumio
• Ishikura Minoru
• Nakayabu Takashi
• Konishi Kazushi
• Morita Toshiaki
• Kobata Masami

Classifications

• B05D2401/20

  Aqueous dispersion or solution · CPC title

• C09D5/00

  Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced {(electrically insulating plastics, resins or waxes H01B3/30)}; Filling pastes · CPC title

• C08G18/792

  formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates · CPC title

• C08G18/2825

  having at least 6 carbon atoms · CPC title

• C08G18/4833

  Polyethers containing oxyethylene units · CPC title