Toyota Jidosha Kabushiki Kaisha

Kansai Paint Company, Ltd.

Nippon Paint Automotive Coatings Co., Ltd

Masako Hase

Keiji Ambo

Yoshinori Narita

Hiroshi Mitsuishi

Kazuki Matsubara

Masahiko Ishii

Koji Morita

Naoya Yabuuchi

Hirofumi Yamashita

Hironori Tonomura

Yukihiro Ikeura

Akira Yamazaki

Yasunori Miwa

Yoshinari Matsuura

Takayuki Ono

Katsuhiko Sugimoto

Takayuki Kawabata

Hiroshi Nishinaka

A method for forming a multilayer coating film which includes forming an uncured coating film by applying a first aqueous base coating composition, forming an uncured coating film by applying a second aqueous base coating composition, forming an uncured coating film by applying a clear coating composition, and simultaneously heat curing the obtained coating films. The first aqueous base coating composition contains a carbodiimide compound, the clear coating composition contains a hydroxyl group-containing acrylic resin (A) having a hydroxyl value of 120 to 160 mgKOH/g and an acid value of 5 to 10 mgKOH/g, a polyisocyanate compound (B), and a polycarbonate diol compound (C). The component (A) has a hydroxyl group-containing alkyl moiety having 3 or less carbon atoms, and the ratio of the numbers of moles of the isocyanate functional groups of the component (B) and the hydroxyl group functional groups of the component (A) is 1.15 to 1.35.

Method for forming multilayer coating film

A method for forming a multilayer coated film includes step (1) of applying an aqueous intermediate coating composition (A), step (2) of applying an aqueous base coating composition (B), step (3) of applying a clear coating composition (C), and step (4) of heat-curing the coated films. The coating composition (A) contains a specific hydroxyl group-containing acrylic resin (a1), a specific polyurethane resin (a2), a specific hydroxyl group-containing polyester resin (a3), a melamine resin (a4), and an active methylene-blocked polyisocyanate compound (a5). A ratio of the resin (a1) to the resin (a2) falls within a specific range. The heat-cured coated film of the coating composition (A) has a specific elongation at break, Young's modulus and Tukon hardness. The coating composition (C) contains a hydroxyl group-containing acrylic resin (c1) and an allophanate group-containing polyisocyanate compound (c2).

Method for forming multilayer coated film

The coating film formed on an automobile body has softness during a film formation even on a thermally expandable/shrinkable base, and the cured film has an excellent appearance. Provided is a method for forming a multilayer coating film, the method comprises: applying an aqueous intermediate coating composition and preheating the applied composition at 60 to 90&#xb0; C. to form an uncured film; preheating to form an uncured base coating film and a clear coating film; and baking and curing these uncured films to form a multilayer coating film, wherein the aqueous intermediate coating composition comprises (a) an acrylic resin emulsion having a specific properties, and (b) a film formation auxiliary agent that is a fatty acid diester compound having a boiling point of 280&#xb0; C. to 350&#xb0; C., and a cured film comprising (a) and (b) at a mass ratio of 3:1 has a rupture elongation of 1% or more.

A method for forming a multilayer coated film on an electrodeposition-coated alloyed hot-dip galvanized steel plate include step (1) of applying an aqueous intermediate coating composition (X), step (2) of applying an aqueous base coating composition (Y), step (3) of applying a clear coating composition (Z) containing an epoxide, and step (4) of heat-curing each coated film. The coating composition (X) contains a hydroxyl group-containing acrylic resin (A), a polyurethane resin (B), a hydroxyl group-containing polyester resin (C), a melamine resin (D), and an active methylene-blocked polyisocyanate compound (E). The ratio of (A) to (B) is controlled to a specific range, and an elongation at break, Young's modulus and Tukon hardness of the coated film of the coating composition (X) are controlled to specific ranges.

The present disclosure provides a jet-black multilayer coating film having excellent properties in high appearance, water resistance, and humidity resistance and comprising a base coating film and a clear coating film formed by a coating composition containing a plant-derived aliphatic polyester mainly and a method for forming the same. A jet-black multilayer coating film comprising a base coating film layer formed by a base coating composition which contains a polyester polyol (A-1) containing a polyol having three or more functions and lactic acid as a consisting component of 80 mol % or more and having a hydroxyl value of 140 to 240 mgKOH/g wherein 70 mol % or more of the hydroxyl groups are secondary hydroxyl groups, an acrylic resin (A-2) with a hydroxyl value of 30 to 80 mgKOH/g and a glass transition point of 40 to 80&#xb0; C., and a polyisocyanate (A-3), and a clear coating film layer formed on said base coating film layer by a clear coating composition which contains a polyester polyol (B-1) obtained by polymerization of a raw composition of a polyol having three or more functions, sebacic acid, and a diol and having a hydroxyl value of 140 to 240 mgKOH/g, an acrylic resin (B-2) with a hydroxyl value of 120 to 220 mgKOH/g, and a polyisocyanate (B-3).

Jet-black multilayer coating film and forming method thereof

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Toyota, Japan

Masako Hase