Method for forming multilayer coating film

• US 10,639,672 B2
• Filed: 12/10/2015
• Issued: 05/05/2020
• Est. Priority Date: 01/29/2015
• Status: Active Grant

• Current Assignee: Kansai Paint Company Limited
• Original Assignee: Kansai Paint Company Limited
• Inventors: Takayama, Daisuke, Tonomura, Hironori, Matsushima, Naoto, Nakahara, Shuichi
• Primary Examiner(s): Fletcher, III, William P
• Application Number:
  US15/546,384
• Publication Number:
  US 20180021810A1
• Time in Patent Office: Days
• Field of Search: 524140, 4274071, 427409
• CPC Class Codes: B05D 1/36 Successively applying liquids or other fluent materials, e.g. without intermediate treatment
• CPC Class Codes: B05D 2202/10 based on Fe
• CPC Class Codes: B05D 2401/10 Organic solvent B05D2401/21 takes precedence
• CPC Class Codes: B05D 2401/20 Aqueous dispersion or solution
• CPC Class Codes: B05D 2451/00 Type of carrier, type of coating (Multilayers)
• CPC Class Codes: B05D 5/068 achieved by multilayers B05D5/066 takes precedence
• CPC Class Codes: B05D 7/14 to metal, e.g. car bodies involving a chemical reaction between the metal and the coating C23
• CPC Class Codes: B05D 7/24 for applying particular liquids or other fluent materials
• CPC Class Codes: B05D 7/572 all layers being cured or baked together
• CPC Class Codes: B32B 15/082 comprising vinyl resins; comprising acrylic resins
• CPC Class Codes: B32B 15/085 comprising polyolefins
• CPC Class Codes: B32B 15/088 comprising polyamides
• CPC Class Codes: B32B 15/09 comprising polyesters
• CPC Class Codes: B32B 15/092 comprising epoxy resins
• CPC Class Codes: B32B 15/095 comprising polyurethanes
• CPC Class Codes: B32B 15/18 comprising iron or steel B32B15/011, B32B15/012 and B32B15/013 take precedence
• CPC Class Codes: B32B 15/20 comprising aluminium or copper B32B15/016 and B32B15/017 take precedence
• CPC Class Codes: B32B 2255/06 on metal layer
• CPC Class Codes: B32B 2255/10 on synthetic resin layer or on natural or synthetic rubber layer
• CPC Class Codes: B32B 2255/26 Polymeric coating
• CPC Class Codes: B32B 2255/28 : Multiple coating on one surface
• CPC Class Codes: B32B 2307/4023 : on the layer surface, e.g. ink
• CPC Class Codes: B32B 2307/7265 : Non-permeable
• CPC Class Codes: B32B 2457/00 : Electrical equipment
• CPC Class Codes: B32B 2509/00 : Household appliances
• CPC Class Codes: B32B 2605/00 : Vehicles
• CPC Class Codes: B32B 27/18 : characterised by the use of special additives
• CPC Class Codes: B32B 27/302 : comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/304 : comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
• CPC Class Codes: B32B 27/308 : comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 : comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/34 : comprising polyamides
• CPC Class Codes: B32B 27/365 : comprising polycarbonates
• CPC Class Codes: B32B 27/38 : comprising epoxy resins
• CPC Class Codes: B32B 27/40 : comprising polyurethanes

Abstract

The problem to be solved by the present invention is to provide a method for forming a multilayer coating film using a 3-coat 1-bake process, the method comprising sequentially applying an aqueous first colored coating composition, an aqueous second colored coating composition, and a clear coating composition to a substrate and simultaneously heat-curing the resulting three layers to form a multilayer coating film having an excellent finished appearance, such as smoothness and distinctness of image, as well as metallic feel and no metallic mottling when the composition comprises an effect pigment, and exhibiting excellent coating film performance, such as water resistance. The present invention provides a method for forming a multilayer coating film by a 3-coat 1-bake process comprising sequentially applying an aqueous first colored coating composition, an aqueous second colored coating composition, and a clear coating composition to a substrate, and simultaneously heat-curing the resulting three layers to form a multilayer coating film, wherein the aqueous second colored coating composition contains (A) a film-forming resin and (B) a phosphoric acid compound represented by a specific formula.

Claims

1. A method for forming a multilayer coating film, comprising subjecting a substrate to the following steps (1) to (4) in order:

step (1);

applying an aqueous first colored coating composition (X) to form a first colored coating film,

step (2);

applying an aqueous second colored coating composition (Y) to the first colored coating film formed in step (1) to form a second colored coating film,

step (3);

applying a clear coating composition (Z) to the second colored coating film formed in step (2) to form a clear coating film; and

step (4);

simultaneously bake-curing the first colored coating film, the second colored coating film, and the clear coating film formed in steps (1) to (3),

wherein an aqueous coating composition comprising (A) a film-forming resin and (B) a phosphoric acid compound is applied as the aqueous second colored coating composition (Y), the phosphoric acid compound being represented by the Formula;

2. The method for forming a multilayer coating film according to claim 1, wherein the phosphoric acid compound (B) is a phosphoric acid compound represented by Formula (1) wherein n is an integer of 1 to 20.

3. The method for forming a multilayer coating film according to claim 1, wherein the phosphoric acid compound (B) is a phosphoric acid compound represented by Formula (1) wherein each oxyalkylene unit (R²O) is an oxyethylene group.

4. The method for forming a multilayer coating film according to claim 1, wherein the phosphoric acid compound (B) is a phosphoric acid compound represented by Formula (1) wherein R¹ is a substituted or unsubstituted hydrocarbon group having 4 to 20 carbon atoms.

5. The method for forming a multilayer coating film according to claim 4, wherein the phosphoric acid compound (B) is a phosphoric acid compound represented by Formula (1) wherein R¹ is a substituted or unsubstituted hydrocarbon group having 7 to 20 carbon atoms.

6. The method for forming a multilayer coating film according to claim 1, wherein the phosphoric acid compound (B) is a phosphoric acid compound represented by Formula (1) wherein n is an integer of 1 to 20 and having an HLB of 3 to 17.

7. The method for forming a multilayer coating film according to claim 1, wherein the phosphoric acid compound (B) has a number average molecular weight of 100 to 3000.

8. The method for forming a multilayer coating film according to claim 1, wherein the phosphoric acid compound (B) is a mixture of a phosphoric acid compound represented by Formula (1) wherein n is 0 and a phosphoric acid compound represented by Formula (1) wherein n is an integer of 1 to 20.

9. The method for forming a multilayer coating film according to claim 1, wherein the aqueous second colored coating composition (Y) further comprises a crosslinking agent (C).

10. The method for forming a multilayer coating film according to claim 1, wherein the film-forming resin (A) comprises acrylic resin particles (A1).

11. The method for forming a multilayer coating film according to claim 1, wherein the substrate is an electrocoated steel plate.

12. An article coated by the method for forming a multilayer coating film according to claim 1.