Water-borne coating composition and method of forming multilayer coating film

• US 20020077410A1
• Filed: 09/04/2001
• Published: 06/20/2002
• Est. Priority Date: 09/01/2000
• Status: Active Grant

• Current Assignee: Nippon paint automotive coatings co., ltd. (Rainbow Light Limited)
• Original Assignee: Nippon Paint Company Limited (Rainbow Light Limited)
• Inventors: Murayama, Masaru, Harakawa, Tsuyoshi, Seo, Shinnji, Tsuji, Naohiro
• Granted Patent: US 6,716,909 B2
• Time in Patent Office: Days
• US Class Current: 524/507
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 33/00 Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 75/04 Polyurethanes
• CPC Class Codes: C09D 133/064 containing anhydride, COOH or COOM groups, with M being metal or onium-cation
• CPC Class Codes: C09D 175/04 Polyurethanes
• CPC Class Codes: Y10T 428/31551 Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers

Abstract

The present invention provides a water-borne coating composition excellent in smoothness and film appearance.

A water-borne coating composition comprising:

an emulsion resin obtained by emulsion polymerization of an α,β-ethylenically unsaturated monomer mixture

and a urethane compound represented by the general formula (1) or (2):

wherein the content of said urethane compound is 0.01 to 20% by weight on the solid basis relative to the resin solid in the coating composition.

A method of forming a multilayer coating film comprising: applying a water-borne base coating to an article to be coated and then applying a clear coating thereonto, followed by curing by heating,

wherein said water-borne base coating is the above-mentioned water-borne coating composition.

Claims

1. A water-borne coating composition comprising

an emulsion resin obtained by emulsion polymerization of an α

,β

-ethylenically unsaturated monomer mixture comprising not less than 65% by weight of a (meth)acrylate ester whose ester-forming moiety contains 1 or 2 carbon atoms and having an acid value of 3 to 50 and

a urethane compound represented by the general formula (1) or (2);

 

in formulas, R¹, R², R³, R⁴ and R⁵ may be the same or different and each represents a hydrocarbon group, R¹ represents a hydrocarbon group which may optionally have a urethane bond, R³ represents a branched or secondary hydrocarbon group, n is a number not less than 2, j is a number not less than 1 in the general formula (1) or a number not less than 2 in the general formula (2) and k and m each is a number within the range of 1 to 500,

wherein the content of said urethane compound is 0.01 to 20% by weight on the solid basis relative to the resin solid in the coating composition;

3. The water-borne coating composition according to claim 1 or 2,

wherein, in the general formula (1) or (2), R² and R⁵ may be the same or different and each is an alkylene group containing 2 to 4 carbon atoms or a phenylethylene group.

4. The water-borne coating composition according to any of claims 1 to 3,

wherein, in said general formula (1) or (2), R³ is a branched or secondary alkyl group containing 8 to 36 carbon atoms.

5. The water-borne coating composition according to any of claims 1 to 4,

which comprises a color component.

6. The water-borne coating composition according to any of claims 1 to 5,

which comprises a polyether polyol having not less than 0.02, on average, of a primary hydroxyl group per molecule, a number average molecular weight of 300 to 3,000 and a water tolerance value of not less than 2.0.

7. The water-borne coating composition according to claim 6,

wherein said polyether polyol has at least one primary hydroxyl group per molecule and a hydroxyl value of 30 to 700.

8. The water-borne coating composition according to claim 6 or 7,

wherein said polyether polyol has at least 3 hydroxyl groups per molecule.

9. The water-borne coating composition according to any of claims 1 to 8,

which comprises a polyester resin and/or an alkyd resin.

10. A method of forming a multilayer coating film comprising:

applying a water-borne base coating to an article to be coated and then applying a clear coating thereonto, followed by curing by heating,

wherein said water-borne base coating is the water-borne coating composition according to any of claims 5 to 9.

11. The method of forming a multilayer coating film according to claim 10,

wherein said color component is a color pigment and/or a luster color pigment.

12. The method of forming a multilayer coating film according to claim 10 or 11,

wherein said water-borne base coating has an application viscosity at 25°

C. of 500 to 5000 mPa·

s as determined on a single cylindrical rotational viscometer at 6 rpm.

13. A multilayer coating film obtainable by the method according to any of claims 9 to 12.

2. A water-borne coating composition comprising

a water-borne resin resulting from dissolving or dispersing a resin having an acid value of 10 to 100, a hydroxyl value of 30 to 200 and a weight average molecular weight of 4,000 to 2,000,000 in an aqueous medium by means of a neutralizing base and

a urethane compound represented by the general formula (1) or (2):

 

in formulas, R¹, R², R³, R⁴ and R⁵ may be the same or different and each represents a hydrocarbon group, R¹ represents a hydrocarbon group which may optionally have a urethane bond, R³ represents a branched or secondary hydrocarbon group, n is a number not less than 2, j is a number not less than 1 in the general formula (1) or a number not less than 2 in the general formula (2) and k and m each is a number within the range of 1 to 500,

wherein the content of said urethane compound is 0.01 to 20% by weight on the solid basis relative to the resin solid in the coating composition.