Nippon Paint Compnay, Ltd.

Tasaburo Ueno

Akimitsu Uenaka

Koichi Tsutsui

Yuji Toyoda

Kouichi Tsutsui

Masahiro Yamamoto

Hisaki Tanabe

Masayuki Maruta

Yoshio Eguchi

Naoya Yabuuchi

Katsuaki Kida

Ryozo Takagawa

Hideki Ichimura

Harunori Gohji

An electrostatic powder coating method of forming an undercoating film having a volume specific resistivity of not more than 10.sup.13 .OMEGA..multidot.cm and a thickness of not more than 200 .mu.m on a metal surface and forming an overcoating layer on the undercoating film by electrostatic powder coating. The undercoating film is composed of a plurality of layers with only the top layer containing a conductive material.

Electrostatic powder coating method

A powder coating comprising a thermosetting resinous composition comprising a base resin having 2 or more oxirane groups in its molecule and a hardener for epoxy resin, which is characterized by further containing 0.5 to 10% by weight based on the base resin weight of a vinyl resin containing 1 to 10% by weight of at least one aliphatic dicarboxylic acid selected from thiomalic acid, maleic acid, fumaric acid and itaconic acid and having a number average molecular weight of 1000 to 8000 and a glass transition temperature of -40.degree. to 100.degree. C. The coating obtained is excellent in smoothness, gloss and image clarity.

Powder coating composition

A resinous composition for powder coating, comprising (A) an acrylic resin and (B) a hardener, the acrylic resin being composed of (a) t-butyl methacrylate and/or t-butyl acrylate, (b) an ethylenically unsaturated monomer having a reactive functional group and (c) other ethylenically unsaturated monomer(s) than the said (a) and (b) which is (are) non-reactive with the functional group of (b), the reactive functional group content being 0.0010-0.0046 mol/g of resin, the glass transition temperature being 30-110.degree. C. and the number average molecular weight being 1,000-20,000, and the hardener having in its molecule 2 or more functional groups which are reactive with the reactive functional group possessed by the acrylic resin. The powder coating based on the present resinous composition is useful for the coating of construction material, auto-mobile and the like and is excellent in low temperature curing properties, storage stability and can result an excellent film even when used a stored powder.

Resinous composition for powder coating

A powder coating comprising, as main components. (A) a carboxyl group containing resin having a number average molecular weight of 1000-30000, an acid value of 5-200 KOH mg/g and a glass transition temp. of 20.degree.-120.degree. C., and (B) a polyglycidyl compound obtained by addition of a polyester oligomer having 2 or more carboxyl groups and a number average molecular weight of 200-1200, with an epoxy compound of the formula: ##STR1## , the ratio of carboxyl groups in (A) to glycidyl groups in (B) being, in terms of equivalent ratio, 0.5 to 2.0. This powder coating may result a coating with excellent processability, impact strength and the like and is excellent in storage stability, hardening properties either at high or low temperature and even when used a stored powder may result a coating with excellent processability.

The invention concerns a coating powder composition comprising (A) a carboxyl group containing polyester resin having a number average molecular weight of 1,000.about.20,000, an acid value of 10.about.100, a glass transition temperature of 35.degree.-120.degree. C. and an SP value of 9.8.about.11.5, and (B) glycidyl trimellitate, wherein the equivalent weight ratio of carboxyl the groups of said (A) to the glycidyl groups of said (B) is 1:2 to 2:1. The coating powder composition is specifically suitable for a high-temperature-short time baking and capable of resulting in a coating having excellent film properties including bending and processability and which coating is highly-crosslinked.

Coating powder composition

The invention relates to a composite particle comprising 2 to 98% by weight of a base resin having softending point of -10.degree. to 120.degree. C. and a number average molecular weight of 600 or more and 98 to 2% by weight of an anisotropic crystalline polymer having a phase transition point of 60.degree. to 230.degree. C. and a number average molecular weight of 600 to 10,000 and capable for forming an anisotropic molten phase, the polymer having the specific structure in which a repeating unit of the formula:

Composite particle

The invention concerns powder coatings comprising thermoplastic or thermosetting type resin powder particles, each particle carrying at least on the surface thereof, a number of microparticles having an average diameter of 0.001 to 10.mu. of such resin as having a glass transition temperature of 50.degree. to 150.degree. C. and a SP value of 9 to 15, said microparticle optionally containing UV absorber or antioxidant or hardening catalyst, the weight ratio of said microparticles to the total weight of the powder coatings being 0.05 to 30% by weight. The present powder coatings are excellent in blocking resistance and capable of forming a coating with excellent stain resistance, coating appearance and other desired properties.

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Osaka, Japan

Tasaburo Ueno