An aqueous coating composition comprising an acrylic resin dispersion (A) having a core/shell structure and a melamine resin (B) comprising a hydrophobic melamine resin, wherein the acrylic resin dispersion (A) is a dispersion of a solution-polymerization product of a core part preparation monomer (a-1) and a shell part preparation monomer (a-2), wherein the shell part preparation monomer (a-2) comprises an acid group-containing polymerizable monomer. The aqueous coating composition exhibits a small viscosity change and can form a coating film having a superior coating film appearance, even when the amount of the solvent contained in the aqueous coating composition is reduced due to changes in the coating environment.

Provided is a multilayer coating film including a metallic base coating film and a transparent colored coating film that contains a blue pigment and that is disposed on the metallic base coating film, wherein the value of hue angle h in an L*C*h color space diagram of the multilayer coating film is within the range of 225° to 300°, and when X=C*45/L*45 and Y=[(L*15).sup.2+(C*15).sup.2)].sup.1/2+[(L*25).sup.2+(C*25).sup.2)].sup.1/2, X is 2 to 20 and Y is 50 to 250, provided that C*15, C*25, and C*45 each represent a chroma of the multilayer coating film calculated from a spectral reflectance of light illuminated at an incident angle of 45° with respect to the multilayer coating film and received at angles of 15°, 25°, and 45° deviated from specular reflection light, and that L*15, L*25, and L*45 each represent a lightness of the multilayer coating film calculated from a spectral reflectance of light illuminated at an incident angle of 45° with respect to the multilayer coating film and received at angles of 15°, 25° and 45° deviated from specular reflection light.

Provided is a method for forming a multilayer coating film, the method being capable of forming a multilayer coating film having excellent chipping resistance, adhesion, and finished appearance. The method for forming a coating film uses a 3-coat and 1-bake system in which a three-layered multilayer coating film obtained by sequentially applying a first coloring paint (X), a second coloring paint (Y), and a clear coating paint (Z) onto an object to be coated is heated and cured at the same time, wherein the first coloring paint (X) and the second coloring paint (Y) contain a hydroxyl group-containing resin, and the clear coating paint (Z) contains a hydroxyl group-containing acrylic resin (a) and an aliphatic triisocyanate compound (b1) having a molecular weight within a specific range.

To provide a paint composition capable of forming a coating film having a small graininess, having high flip-flop property, and having excellent chipping resistance and adhesion. According to the present invention, there is provided a paint composition including a hydroxy group-containing acrylic resin (A), a hydroxy group-containing polyester resin (B), an amino resin (C), and a titanium oxide-coated light interference pigment (D), which has an L*15 value of 100 or more and an L*110 value of 65 or less, wherein the solid content of the hydroxy group-containing acrylic resin (A) is in the range of 20 to 60 parts by mass, the solid content of the hydroxy group-containing polyester resin (B) is in the range of 10 to 50 parts by mass, the solid content of the amino resin (C) is in the range of 5 to 40 parts by mass, and the solid content of the titanium oxide-coated light interference pigment (D) is in the range of 3 to 25 parts by mass, relative to 100 parts by mass of the total solid content of the hydroxy group-containing acrylic resin (A), the hydroxy group-containing polyester resin (B), and the amino resin (C).

Disclosed is a method for forming a multilayer coating film, including applying a first and second aqueous base coat, and a clear coat to an object, and thereafter simultaneously heating and curing the three-layer coating film. The first aqueous base coat includes a water-soluble or water-dispersible polyurethane resin having a glass transition temperature of −20° C. or below and a weight average molecular weight of 30,000 to 500,000, and a crosslinkable resin having a weight average molecular weight of 600 or more. The first aqueous base coat-coated film has a breaking strength of 2050 N/cm2 or more and a loss tangent (tan δ) at −20° C. of 0.075 or more. The migration amount of a melamine resin from the second aqueous base coat-coated film layer to the first aqueous base coat-coated film layer is within 3% by mass of a total resin solid content of the first aqueous base coat.

Multi-layer coatings comprising polymerization reaction products of 1,1-di-activated vinyl compounds are described. Also provided are processes for coating substrates with curable compositions comprising 1,1-di-activated vinyl compounds. Also provided are articles coated with this composition.

Provided is a method for forming a multilayer coating film, the method being capable of forming a high-brightness white multilayer coating film which is excellent in terms of brilliant feeling, smoothness, and weather resistance and with which white stains are suppressed. In this method for forming a multilayer coating film to form a brilliant coating film, a white multilayer coating film is formed by: sequentially applying a first coloring paint (P1), a second aqueous coloring paint (P2), a third aqueous coloring paint (P3), and a clear coat paint (P4) on a cured electrodeposition coating film formed on a steel sheet; and forming a first colored coating film, a second colored coating film, a third colored coating film, and a clear coat coating film which each have a particular composition, brightness, film thickness, and the like.

A multi-layer coating system includes: (a) a first basecoat layer formed from a first coating composition including a free polyisocyanate and hydroxyl functional polymeric core-shell particles; (b) a second basecoat layer applied over at least a portion of the first basecoat layer, the second basecoat layer formed from a second coating composition including carboxylic acid functional polymeric core-shell particles; and (c) a topcoat layer applied over at least a portion of the second basecoat layer, the topcoat layer formed from a coating composition including least one free polyisocyanate having a weight average molecular weight of less than 600 g/mol and at least one film-forming resin in which an amount of free polyisocyanate having a weight average molecular weight of less than 600 g/mol is greater than 5 weight %, based on the total resin solids of the coating composition that forms the topcoat layer.

A high-solid-content coating composition includes: (A) a hydroxy group-containing acrylic resin having a glass transition temperature (Tg) in a range of 20 C. to 70 C. and a weight average molecular weight in a range of 3,000 to 10,000; (B) a hydroxy group-containing polyester resin being a reaction product of a polyfunctional compound (b-1) having a carboxy group and a hydroxy group in total of three or more in one molecule, a monoepoxide compound (b-2) having a hydrocarbon group having 4 or more carbon atoms, and a caprolactone compound (b-3); and (C) a polyisocyanate compound, in which a solid content at the time of coating is 50 mass % or more.

Described herein is a process for producing a multilayer coating onto a fiber-reinforced composite material Also described herein is a fiber-reinforced composite material coated with a multilayer coating obtainable by this process.