Abstract: A surface-treated steel sheet includes a chemical conversion coating with a thickness of 3.0 ?m or less, the chemical conversion coating being placed on a surface of a hot-dip Zn—Al alloy coated steel sheet including a hot-dip Zn—Al alloy coating film containing Al: more than 1.0 mass % and 15 mass % or less, a balance being Zn and inevitable impurities. The chemical conversion coating contains AlH2P3O10.2H2O and a compound containing one or more elements selected from Mg, Ca, and Sr such that a sum of contents of AlH2P3O10.2H2O and the compound is 3.0 mass % to 50 mass %.

Abstract: Disclosed is a method of producing a surface-treated steel sheet for organic resin coating comprising: applying, to a surface of a zinc or zinc alloy coated or plated steel sheet, a surface-treatment solution containing a resin compound having a specific bisphenol skeleton, a cationic urethane resin emulsion, a silane coupling agent having a specific reactive functional group, an organic titanium chelate compound, a tetravalent vanadium compound, a molybdate compound, a fluorine compound, and water in a specific ratio and with a pH of 4 to 5 to form a surface-treatment layer such that a coating weight of the surface-treatment layer per surface after drying of the surface-treatment solution is 0.005 g/m2 to 1.8 g/m2.

Abstract: A steel sheet has a hot-dip Zn—Al—Mg-based coating film, the coating film containing 1 mass % to 22 mass % of Al and 0.1 mass % to 10 mass % of Mg on a surface of the steel sheet, in which an X-ray diffraction peak intensity ratio of a Mg—Zn compound phase in the coating film, that is, MgZn2/Mg2Zn11, is 0.2 or less.

Abstract: A surface-treated steel sheet includes a chemical conversion coating with a thickness of 3.0 ?m or less, the chemical conversion coating being placed on a surface of a hot-dip Zn—Al alloy coated steel sheet including a hot-dip Zn—Al alloy coating film containing Al: more than 1.0 mass % and 15 mass % or less, a balance being Zn and inevitable impurities. The chemical conversion coating contains AlH2P3O10.2H2O and a compound containing one or more elements selected from Mg, Ca, and Sr such that a sum of contents of AlH2P3O10.2H2O and the compound is 3.0 mass % to 50 mass %.

Abstract: Disclosed is a surface-treatment solution for producing a zinc or zinc alloy coated steel sheet with a surface-coating layer that does not contain a chromium compound in the surface-coating layer and that is excellent in all of heat discoloration resistance, heat cracking resistance, planar part anti-corrosion property, corrosion resistance after alkali degreasing, blackening resistance, stack blackening resistance, anti-water stain property, solvent resistance, perspiration resistance, coating adhesion property, and storage stability. The disclosed surface-treatment solution contains a glycidyl group-containing silane coupling agent (A), a tetraalkoxysilane (B), a zirconium carbonate compound (C), and an anionic polyurethane resin (D) having a glass transition temperature (Tg) of 80° C. to 130° C., a vanadium compound (E), a molybdic acid compound (F), and water, the surface-treatment solution having a pH of 8.0 to 10.0, and the amount of each component satisfying a predetermined relationship.

Abstract: A steel sheet has a hot-dip Zn—Al—Mg-based coating film, the coating film containing 1 mass % to 22 mass % of Al and 0.1 mass % to 10 mass % of Mg on a surface of the steel sheet, in which an X-ray diffraction peak intensity ratio of a Mg—Zn compound phase in the coating film, that is, MgZn2/Mg2Zn11, is 0.2 or less.

Abstract: Disclosed is a surface-treatment solution for producing a zinc or zinc alloy coated steel sheet with a surface-coating layer that does not contain a chromium compound in the surface-coating layer and that is excellent in all of heat discoloration resistance, heat cracking resistance, planar part anti-corrosion property, corrosion resistance after alkali degreasing, blackening resistance, stack blackening resistance, anti-water stain property, solvent resistance, perspiration resistance, coating adhesion property, and storage stability. The disclosed surface-treatment solution contains a glycidyl group-containing silane coupling agent (A), a tetraalkoxysilane (B), a zirconium carbonate compound (C), and an anionic polyurethane resin (D) having a glass transition temperature (Tg) of 80° C. to 130° C., a vanadium compound (E), a molybdic acid compound (F), and water, the surface-treatment solution having a pH of 8.0 to 10.0, and the amount of each component satisfying a predetermined relationship.

Abstract: An aqueous surface-treatment liquid is a treatment liquid containing a water-soluble zirconium compound, water-dispersive particulate silica, a silane coupling agent, a vanadic acid compound, a phosphoric acid compound, a nickel compound, and an acrylic resin emulsion in particular proportions. A surface-treated galvanized steel sheet produced using the treatment liquid is a galvanized steel sheet having a surface-treatment coating on a surface thereof, and the coating contains a zirconium compound, particulate silica, a silane-coupling-agent-derived component, a vanadic acid compound, a phosphoric acid compound, a nickel compound, and an acrylic resin in particular proportions. The amount of coating on a zirconium basis is 10 to 200 mg/m2. This surface-treated galvanized steel sheet is chromate-free and has superior flat-portion corrosion resistance, blackening resistance, and appearance and corrosion resistance after press forming.

Abstract: The surface-treated steel sheet has a zinc-based plated steel sheet, a surface-treatment coating being formed on the surface of the zinc-based steel sheet by applying and drying a surface treatment coating composition thereon, and a top coating being formed by applying and drying a coating composition for top coating on the surface-treatment coating. The surface treatment coating composition contains a water-epoxy resin dispersion, a silane coupling agent, and phosphoric acid and/or a hexafluorometal acid. The coating composition for top coating contains a high molecular weight epoxy group-containing resin having number average molecular weights ranging from 6000 to 20000.

Abstract: A surface-treated galvanized steel sheet includes a steel sheet, a zinc coating disposed on the steel sheet, and a film disposed on the zinc coating. The film has a thickness in the range of 0.01 to 3 ?m and contains certain amounts of resin compound having a particular chemical structure, cationic urethane resin, vanadium compound, zirconium compound, compound having a phosphate group, and acid compound. The surface-treated galvanized steel sheet contains no hexavalent chromium in the film and is excellent in terms of corrosion resistance, alkali resistance, and solvent resistance.

Abstract: The present invention provides a surface treated steel sheet including a steel sheet; a plating layer containing at least one metal selected from the group consisting of zinc and aluminum on a surface of the steel sheet; and a film on the plating layer, the film containing at least one metal selected from the group consisting of Al, Mg, and Zn, a tetravalent vanadium compound, and a phosphoric acid group. This surface treated steel sheet exhibits excellent corrosion resistance and excellent surface appearance without containing hazardous substances, such as hexavalent chromium, in the film.

Abstract: An aqueous surface-treatment liquid is a treatment liquid containing a water-soluble zirconium compound, water-dispersive particulate silica, a silane coupling agent, a vanadic acid compound, a phosphoric acid compound, a nickel compound, and an acrylic resin emulsion in particular proportions. A surface-treated galvanized steel sheet produced using the treatment liquid is a galvanized steel sheet having a surface-treatment coating on a surface thereof, and the coating contains a zirconium compound, particulate silica, a silane-coupling-agent-derived component, a vanadic acid compound, a phosphoric acid compound, a nickel compound, and an acrylic resin in particular proportions. The amount of coating on a zirconium basis is 10 to 200 mg/m2. This surface-treated galvanized steel sheet is chromate-free and has superior flat-portion corrosion resistance, blackening resistance, and appearance and corrosion resistance after press forming.

Abstract: A surface-treated galvanized steel sheet includes a steel sheet, a zinc coating disposed on the steel sheet, and a film disposed on the zinc coating. The film has a thickness in the range of 0.01 to 3 ?m and contains certain amounts of resin compound having a particular chemical structure, cationic urethane resin, vanadium compound, zirconium compound, compound having a phosphate group, and acid compound. The surface-treated galvanized steel sheet contains no hexavalent chromium in the film and is excellent in terms of corrosion resistance, alkali resistance, and solvent resistance.

Abstract: The surface-treated steel sheet has a zinc-based plated steel sheet, a surface-treatment coating being formed on the surface of the zinc-based steel sheet by applying and drying a surface treatment coating composition thereon, and a top coating being formed by applying and drying a coating composition for top coating on the surface-treatment coating. The surface treatment coating composition contains a water-epoxy resin dispersion, a silane coupling agent, and phosphoric acid and/or a hexafluorometal acid. The coating composition for top coating contains a high molecular weight epoxy group-containing resin having number average molecular weights ranging from 6000 to 20000.

Abstract: A surface-treated steel sheet includes a steel sheet; a plating layer containing at least one metal selected from zinc and aluminum; a first layer film containing (?) 1 to 2000 mg/m2 of silica in terms of SiO2, (?) a total of 1 to 1000 mg/m2 of phosphoric acid groups in terms of P, (?) a total of 0.5 to 800 mg/m2 of at least one metal selected from Mg, Mn, and Al, and (?) 0.1 to 50 mg/m2 of a tetravalent vanadium compound; and a second layer film formed to a thickness of 0.1 to 5 ?m on the first layer film and containing a resin (A) having at least one type of functional group selected from OH and COOH groups, and at least one rust-proofing additive (B) selected from (a) a phosphate, (b) Ca ion-exchanged silica, (c) a molybdate, (d) silicon oxide, and (e) at least one organic compound selected from triazoles, thiols, thiadiazoles, thiazoles, and thiurams.

Abstract: A surface-treated steel sheet has a zinc-based or an aluminum-based plated steel sheet, a surface-treatment coating being formed on the surface of the zinc-based or aluminum-based steel sheet by applying and drying a surface treatment coating composition thereon, and a top coating being formed by applying and drying a coating composition for top coating on the surface-treatment coating. The surface treatment coating composition contains a water-epoxy resin dispersion, a water dispersed polyurethane resin, a silane coupling agent, and phosphoric acid and/or a hexafluorometal acid. The coating composition for a top coating contains a high molecular weight epoxy group-containing resin average molecular weight of 6,000 to 20,000.

Abstract: The present invention provides a surface treated steel sheet including a steel sheet; a plating layer containing at least one metal selected from the group consisting of zinc and aluminum on a surface of the steel sheet; and a film on the plating layer, the film containing at least one metal selected from the group consisting of Al, Mg, and Zn, a tetravalent vanadium compound, and a phosphoric acid group. This surface treated steel sheet exhibits excellent corrosion resistance and excellent surface appearance without containing hazardous substances, such as hexavalent chromium, in the film.

Abstract: The present invention provides a surface-treated steel sheet including a steel sheet; a plating layer provided on at least one of the surfaces of the steel sheet, the plating layer containing at least one metal selected from the group consisting of zinc and aluminum; a first layer film provided on the surface of the plating layer and containing (?) 1 to 2000 mg/m2 of silica in terms of SiO2, (?) a total of 1 to 1000 mg/m2 of phosphoric acid groups in terms of P, (?) a total of 0.5 to 800 mg/m2 of at least one metal selected from the group consisting of Mg, Mn, and Al in terms of a metal element, and (?) 0.1 to 50 mg/m2 of a tetravalent vanadium compound in terms of V; and a second layer film formed to a thickness of 0.

Abstract: The surface-treated steel sheet has a zinc-based plated steel sheet, a surface-treatment coating being formed on the surface of the zinc-based steel sheet by applying and drying a surface treatment coating composition thereon, and a top coating being formed by applying and drying a coating composition for top coating on the surface-treatment coating. The surface treatment coating composition contains a water-epoxy resin dispersion, a silane coupling agent, and phosphoric acid and/or a hexafluorometal acid. The coating composition for top coating contains a high molecular weight epoxy group-containing resin having number average molecular weights ranging from 6000 to 20000.

Abstract: The invention is to provide a surface-treated steel sheet of good white rust resistance with no chromium in its surface treatment film, and it has realized a surface-treated steel sheet of higher-level corrosion resistance by forming a reaction layer of plating metal with a barrier layer effective for anticorrosion not in a two-layered film but in a single-layered film.