Kansai Paint Company, Ltd.

Nippon Kokan Kabushiki Kaisha

Nkk Corporation

Yoshiaki Miyosawa

Masaaki Yamashita

Takahiro Kubota

Tadashi Nishimoto

Takeshi Adaniya

Norio Nikaido

Kazuhiko Ozawa

Sueo Umemoto

Akira Enatsu

Tsutomu Watanabe

A first characteristic of the invention is present in forming a chromate film on the surface of a zinc or a zinc alloy plated steel sheet, and a resin composition film at a coating amount of 0.3 to 5.0 g/m.sup.2 on said chromate fim, said resin composition film comprising an organic solvent soluble epoxy resin and hydrophobic silica in a ratio of 80:20 to 50:50 by weight of epoxy resin:hydrophobic resin, said epoxy resin having a glass transition temperature of 293.degree. to 342.degree. K. A second characteristic of the invention is present in forming a chromate film on the surface of a zinc or zinc alloy plated steel sheet, and a resin composition film at a coating amount of 0.3 to 5.0 g/m.sup.2 on said chromate film, and resin composition film comprising an organic solvent soluble epoxy resin having glass transition temperature of 293.degree. to 342.degree. K. and hydrophobic silica and sparingly water soluble Cr compound in a ratio of 80:20 to 50:50 by weight of epoxy resin:(hydrophobic silica+sparingly water soluble Cr compound), and in a ratio 37:3 to 20:20 by weight of hydrophobic silica:sparingly water soluble Cr compound.

Multi-layered steel sheets

This invention relates to a highly corrosion-resistant, multi-layer coated steel sheet, and includes an undercoat film obtained by galvanization or zinc-alloy plating and a chromate coated film thereon, on which a resin-composition film is further applied, comprising an organic high-molecular weight resin having a glass transision temperature of 343.degree. to 423.degree. K. and soluble in organic solvent and hydrophobic silica. For the purpose of improvement of corrosion preventiveness, a sparingly water soluble Cr compound may be contained in this resin composition film. Together with this sparingly water soluble Cr compound, a di- or tri-alkoxysilane compound may be also contained in the resin composition film.

Highly corrosion-resistant, multi-layer coated steel sheets

The present invention relates to a highly corrosion resistant surface-treated steel plate. The steel plate of the invention comprises a zinc deposition or zinc alloy deposition film as the undercoat deposition layer, a chromate film formed on the undercoat deposition layer and a film of a resin composition formed on the chromate film. This resin composition comprises a substrate resin formed by adding at least one basic nitogen atom and at least two primary hydrogen groups to terminal of an epoxy resin, silica and sparingly water soluble Cr compound. The resin composition may comprise a polyisocyanate compound as the curing agent. Moreover, the resin composition may comprise a silane compound as the crosslinking agent for the substrate resin and silica.

Highly corrosion-resistant surface-treated steel plate

The present invention relates to a highly corrosion-resistant surface-treated steel plate. The steel plate of the present invention comprises a zinc deposition or zinc alloy deposition film as the undercoat deposition layer, a chromate film formed on the undercoat deposition layer and a film of a resin composition formed on the chromate film. This resin composition comprises a base resin formed by adding at least one basic nitrogen atom and at least two primary hydroxyl groups to terminals of an epoxy resin. The resin composition may comprise a polyisocyanate compound as the curing agent. Furthermore, the resin composition may comprise silica or a hardly soluble chromium compound as the additive for improving the corrosion resistance. Moreover, the resin composition may comprise a silane compound as the crosslinking agent for the base resin and silica.

A silica complex composition suitable for the surface treatment of metals is disclosed, which comprises a water dispersible silica, an organic polymer soluble or dispersible in water and a di- or trialkoxy (or alkoxy-alkoxy) silane compound.

Aqueous dispersion for metal coating from colloidal silica, alkoxy

A coating composition for electrodeposition contains water soluble or water dispersible resin and at least one water soluble oxy-acid salt being selected from the group consisting of stannates, molybdates, tungstates, vanadates and borates, or a mixture of said water soluble oxy-acid salts. The coating formed from said composition on a metallic surface by electrodeposition is excellent in the adhesiveness and anti-corrosive property.

Process for electrocoating

A hardenable coating composition which forms an excellent coating film having good properties of transparency, flexibility, hardness and noncombustibility and comprises an aqueous dispersion of silica-polyvinyl alcohol complex prepared by the reaction between colloidal silica dispersion and polyvinyl alcohol solution at a temperature above 50.degree. C. Said reaction can be accelerated by accelerators di- or tri-alkoxy silane accelerators and the properties of the obtained coating film can be improved by the addition of curing agents such as alkoxides and water soluble metallic salts.

Hardenable coating composition

A coating process for articles made of aluminum or aluminum alloy to form a composite coating which is excellent in adherent and anti-corrosive properties, in which the articles are treated in an aqueous solution of water-soluble oxyacid salts selected from the group consisting of silicates, borates, phosphates, chromates, molybdates, vanadates and permanganates with applying electric current to form a conversion coating layer on the aluminum surface, and are further treated with a water-soluble or water-dispersible coating composition to form a finish coat on the conversion coating layer particularly by dipping or electrodeposition.

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Hiratsuka, Japan

Yoshiaki Miyosawa