Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/08—Anti-corrosive paints
  • C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
  • C09D5/084—Inorganic compounds
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
  • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
  • C23C18/1204—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds
  • C23C18/1208—Oxides, e.g. ceramics
  • C23C18/1216—Metal oxides
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
  • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
  • C23C18/1229—Composition of the substrate
  • C23C18/1241—Metallic substrates
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
  • C23C18/12—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of inorganic material other than metallic material
  • C23C18/125—Process of deposition of the inorganic material
  • C23C18/1262—Process of deposition of the inorganic material involving particles, e.g. carbon nanotubes [CNT], flakes
  • C23C18/127—Preformed particles
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
  • C23C2222/20—Use of solutions containing silanes

Definitions

• the present invention relates to a metal surface treatment composition, a metal surface treatment method and a galvanized steel plate.
• Galvanized steel plates to which zinc plating or zinc alloy plating is applied, are used as steel materials having the high corrosion resistance.
• a zinc plating layer is oxidized through contact with air to form white color rust. Therefore, it is necessary to prevent oxidation by applying surface treatment.
• galvanized steel plates are used without being coated after being processed. In such a case, it is important that the galvanized steel plate has a rust-preventive property in an uncoated condition.
• metal surface treatment agents for galvanized steel plates which contain metal salt compounds (cf. Japanese Kokai Publication Hei-9-241856, Japanese Kokai Publication 2001-172771 and Japanese Kokai Publication 2001-247977, for instance).
• galvanized steel plates, surface treated with such the treatment agents did not have sufficient properties of a rust-preventive property, adhesion to a film and the like.
• a chemical conversion treatment solution for galvanized steel plates which contains oxyacid salts of metals selected from molybdenum, vanadium, tungsten, niobium and tantalum, manganese compounds, titanium compounds and phosphoric acid or phosphates, is disclosed (cf. Japanese Kokai Publication 2002-105659, for instance).
• oxyacid salts of metals selected from molybdenum, vanadium, tungsten, niobium and tantalum, manganese compounds, titanium compounds and phosphoric acid or phosphates is disclosed (cf. Japanese Kokai Publication 2002-105659, for instance).
• Japanese Kokai Publication 2002-105659 Japanese Kokai Publication 2002-105659, for instance).
• it is necessary to use a manganese compound since the manganese compound also requires a great deal of burden for the disposal of its waste water, it is preferred not to use it.
• a rust-preventive component used for a metal surface treatment composition water-dispersible silica is used.
• water-dispersible silica is used alone, it did not have an adequate rust-preventive property and the metal surface treatment composition could not attain an adequate rust-preventive property in providing the rust-preventive property for such a galvanized steel plate.
• the present invention provides a metal surface treatment composition comprising niobium oxide colloidal particles,
• the niobium oxide colloidal particle has an average particle diameter of 100 nm or less.
• the niobium oxide colloidal particle has a content of 1 mass % or more relative to the total nonvolatile matter in the metal surface treatment composition when Nb contained in the niobium oxide colloidal particle is converted to equivalent Nb 2 O 5 .
• the metal surface treatment composition comprises
• the water-borne resin is at least one kind selected from the group consisting of acrylic resin, polyolefinic resin, polyurethane resin, epoxy resin, olefin-acrylic acid copolymer resin, phenolic resin, polyester resin, alkyd resin, melamine resin, polycarbonate resin, polyacrylic acid and copolymers or block polymers thereof.
• the metal surface treatment composition comprises
• the metal surface treatment composition comprises
• the metal surface treatment composition comprises
• the metal surface treatment composition comprises
• pH is 6 to 11.
• the concentration of the nonvolatile matter is 3 to 50 mass % on the mass of the nonvolatile matter basis.
• the present invention provides a metal surface treatment method comprising
• the present invention provides a coated galvanized steel plate obtained by the metal surface treatment method.
• a metal surface treatment composition of the present invention comprises a niobium oxide sol which is formed by dispersing niobium oxide colloidal particles highly stabilized with citric acid or salts thereof in an aqueous medium.
• the niobium oxide colloidal particles more preferably have a smaller average particle diameter because when the average particle diameter is small, a more stable and dense treated coat of the niobium oxide is formed and therefore the niobium oxide colloidal particles can provide a rust-preventive property stably for an article to be treated.
• the metal surface treatment composition does not need to contain components, requiring a burden of waste water treatment, such as chromium and manganese.
• the niobium oxide colloidal particle to be used in the present invention refers to one which is formed by niobium oxide dispersing in fine particle form in water.
• a substance, which is present in intermediate region between niobium hydroxide and niobium oxide and becomes an amorphous state without becoming complete niobium oxide, may be used.
• the metal surface treatment composition of the present invention can be prepared by using a niobium oxide sol made by a method publicly known.
• the niobium oxide sol is not particularly limited, and for example, a substance made by a publicly known method, which is described in Japanese Patent No. 2849799 and the like, can be given. Further, niobium oxide sol made by Taki Chemical Co., Ltd. may be employed.
• An example of a method of producing the niobium oxide sol may include a method in which niobium oxide is dissolved in hydrofluoric acid and the dissolved solution is added to aqueous ammonia and then the mixture is filtered and washed to yield niobium hydroxide in slurry form, and oxalate dihydrate is added to the slurry of niobium hydroxide and then water is added, and after a uniform solution composed of niobium oxide colloidal particles is obtained by allowing the reaction of this mixture to proceed under stirring in a condition of refluxing, then citric acid or salt thereof was added to the solution and the resulting mixture is stirred.
• niobium oxide sol In order to adjust the obtained niobium oxide sol to a desired level of pH, a basic compound such as ammonia may be added to the sol as required. In order to identify that the reaction has been completed, that is, a uniform solution of niobium oxide colloidal particles has been obtained before adding citric acid, color of the slurry solution can be utilized and when the slurry exhibits blue color, it is assumed to be in a uniform state.
• the niobium oxide sol which can be used for the metal surface treatment composition of the present invention, is formed by making the niobium oxide sol solution stabilized with oxalic acid further contain citric acid and highly stabilizing it.
• the metal surface treatment composition of the present invention can be prepared by diluting the niobium oxide sol to a required concentration or by adding another component as required and is stable over the long term without causing thickening, gelation or precipitation even after the preparation.
• An essential point is that the niobium oxide sol to be used in the metal surface treatment composition of the present invention is in a state highly stabilized with citric acid or salt thereof, and an amount of oxalic acid or salt thereof, which is mixed in producing the niobium oxide sol, is not particularly limited.
• the niobium oxide sol is preferred in that thereby, the stability of niobium oxide colloidal particles is not degraded in being mixed with another components, which is contained in the metal surface treatment composition of the present invention, such as a water-borne resin, water-dispersible silica, vanadium compounds, zirconium compounds, titanium compounds, silane coupling agents and the phosphate compounds.
• a water-borne resin such as a water-borne resin, water-dispersible silica, vanadium compounds, zirconium compounds, titanium compounds, silane coupling agents and the phosphate compounds.
• An amount of citric acid or salts thereof added to the metal surface treatment composition of the present invention is preferably within a range of 0.02 (lower limit) to 1.0 (upper limit) by a mole ratio relative to Nb in the metal surface treatment composition.
• the amount of citric acid or salts thereof to be added is less than 0.02 by a mole ratio, the stability in adding another components becomes insufficient, and when it exceeds 1.0 by a mole ratio, it is not possible any longer to attain an effect of stabilization corresponding to the amount to be added and hence it is uneconomical.
• the niobium oxide colloidal particles preferably have an average particle diameter of 100 nm or less. When the average particle diameter is small, the niobium oxide colloidal particles can provide a rust-preventive property stably for an article to be treated because a more stable and dense treated coat of the niobium oxide is formed.
• the average particle diameter of the niobium oxide colloidal particles can be measured using a particle size distribution analyzer based on dynamic scattering light, for example, NICOMP MODEL-370 type (manufactured by PACIFIC SCIENTIFIC INSTRUMENTS Co.).
• the metal surface treatment composition of the present invention preferably contains the niobium oxide colloidal particles in an amount of 1 mass % or more relative to the total nonvolatile matter in the metal surface treatment composition when Nb in the colloidal particles is converted to equivalent Nb 2 O 5 .
• the content is less than 1 mass %, it is not preferred since a sufficient rust-preventive property cannot be attained.
• the lower limit of the content is more preferably 2 mass %, furthermore preferably 3 mass %.
• the upper limit is preferably 30 mass %, more preferably 15 mass %.
• the metal surface treatment composition of the present invention preferably comprises a water-borne resin.
• a water-borne resin used herein is one containing a water-soluble resin and a water-dispersible resin.
• the water-borne resin is not particularly limited, and examples thereof may include acrylic resins, polyolefinic resins, polyurethane resins, epoxy resins, olefin-acrylic acid copolymer resins, phenolic resins, polyester resins, alkyd resins, melamine resins, polycarbonate resins and polyacrylic acid, and another thermally crosslinking type and thermoplastic type resins.
• water-borne resins may be used alone or in combination of two or more species, or in the form of copolymers or block polymers thereof.
• a leveling agent, a wetting agent and an antifoaming agent may be used in order to improve a film forming property and form a more uniform and smooth film.
• the content of the water-borne resin is preferably within a range of 5 mass % (lower limit) to 90 mass % (upper limit) relative to the total nonvolatile matter in the metal surface treatment composition.
• the content exceeds 90 mass %, it is not preferred since the adding effect will saturate in this range and the addition becomes uneconomical.
• it is less than 5 mass %, it is not preferred since the rust-preventive property may deteriorate.
• the lower limit is more preferably 10 mass %, furthermore preferably 20 mass %.
• the upper limit is more preferably 80 mass %, furthermore preferably 70 mass %.
• the metal surface treatment composition of the present invention further comprises water-dispersible silica in order to improve the rust-preventive property of a surface treatment film.
• the water-dispersible silica cannot attain an adequate rust-preventive property when it is used alone, but it can improve the rust-preventive property multiplicatively by being used in combination with the niobium oxide colloidal particles.
• the water-dispersible silica is not particularly limited, and examples thereof may include spherical silica, chain silica and aluminum-modified silica, which have fewer impurities such as sodium and the like.
• the spherical silica is not particularly limited, and examples thereof may include colloidal silica such as “SNOWTEX N”, “SNOWTEX O”, “SNOWTEX OXS” and “SNOWTEX UP” (each made by Nissan Chemical Industries, Ltd.) and fumed silica such as “AEROSIL” (made by Nippon Aerosil Co., Ltd.).
• the chain silica is not particularly limited, and examples thereof may include silica sol such as “SNOWTEX PS-M” and “SNOWTEX PS-MO” (each made by Nissan Chemical Industries, Ltd.).
• Examples of the aluminum-modified silica may include commercially available silica gel such as “ADELITE AT-20A” (made by Asahi Denka Co., Ltd.)
• the content of SiO 2 in the metal surface treatment composition is preferably 80 mass % or less relative to the total nonvolatile matter in the metal surface treatment composition.
• the upper limit is more preferably 60 mass %, furthermore preferably 30 mass %.
• the metal surface treatment composition of the present invention further comprises at least one compound selected from the group consisting of vanadium compounds, zirconium compounds and titanium compounds in order to improve the rust-preventive property of a surface treatment film. It is possible to further improve the rust-preventive property by using the niobium oxide colloidal particles in combination with the at least one compound selected from the group consisting of vanadium compounds, zirconium compounds and titanium compounds. It is more preferred to use four, five or six components of the niobium oxide colloidal particles, the water-borne resin, the water-dispersible silica, and the at least one compound selected from the group consisting of vanadium compounds, zirconium compounds and titanium compounds in combination.
• the vanadium compound, zirconium compound and titanium compound are not particularly limited as long as they are water-soluble or water-dispersible compounds, and specific examples thereof are as follows.
• the vanadium compound is not particularly limited, and examples thereof may include vanadyl compounds, vanadium pentoxide, vanadates, burned polyvanadic acid, heteropoly vanadic acid and mixtures thereof. Specific examples thereof may include vanadium (II) compounds such as vanadium (II) oxide, and vanadium (II) hydroxide; vanadium (III) compounds such as vanadium (III) oxide (V 2 O 3 ); vanadium (IV) compounds such as vanadium (IV) oxide (V 2 O 4 ), and vanadyl halides (VOX 2 ); vanadium (V) compounds such as vanadium (V) oxide (V 2 O 5 ); vanadates such as various orthovanadates, metavanadates or pyrovanadates, vanadyl halides (VOX 3 ); or mixtures thereof.
• vanadium (II) compounds such as vanadium (II) oxide, and vanadium (II) hydroxide
• Vanadates are not particularly limited, and examples thereof may include ammonium salt, alkaline metal salts, alkaline earth metal salts (for example, magnesium, calcium), metal salts of another typical elements (for example, aluminum, tin) and transition metal salts (for example, manganese, cobalt, iron, nickel).
• alkaline earth metal salts, zinc salt, manganese salt, and cobalt salt are preferred. These may be obtained by burning oxides of vanadium and oxides, hydroxides or carbonates of various metals together at a temperature of 600° C. or more.
• the zirconium compound is not particularly limited, and examples thereof may include fluorozirconic acid (H 2 ZrF 6 ); ammonium, lithium, sodium, or potassium salts of fluorozirconic acid; ammonium zirconate oxycarbonate ((NH 4 ) 2 ZrO (CO 3 ) 2 ); zirconate compounds such as zirconium hydroxide, zirconium carbonate, zirconium borate, zirconium oxalate, zirconium sulfate, zirconium nitrate, zirconyl nitrate, and zirconium fluoride; organic zirconate compounds such as dibutylzirconium dilaurate, dibutylzirconium dioctate, zirconium naphthenate, zirconium octylate, and acetylacetone zirconium; or mixtures thereof.
• fluorozirconic acid H 2 ZrF 6
• the titanium compound is not particularly limited, and examples thereof may include fluorine-titanium compounds such as fluorotitanic acid, ammonium fluorotitanate, sodium fluorotitanate, potassium fluorotitanate, fluorotitanic acid, alkaline metal fluorotitanate, and titanium fluoride; organic titanium compounds such as titanium potassium oxalate, titanium isopropoxide, isopropyl titanate, titanium ethoxide, titanium 2-ethyl 1-hexanolate, tetraisopropyl titanate, tetran-butyl titanate, butyltitanate dimer, titanium lactate, and titanium triethanolaminate; or mixtures thereof.
• fluorine-titanium compounds such as fluorotitanic acid, ammonium fluorotitanate, sodium fluorotitanate, potassium fluorotitanate, fluorotitanic acid, alkaline metal fluorotitanate, and titanium fluoride
• the content of the compounds is preferably within a range of 0.1 mass % (lower limit) to 30 mass % (upper limit) on the V, Zr or Ti basis relative to the total nonvolatile matter in the metal surface treatment composition.
• the content exceeds 30 mass %, it is not preferred since the adding effect will saturate in this range and the addition becomes uneconomical.
• it is less than 0.1 mass %, it is not preferred since the rust-preventive property may deteriorate.
• the lower limit is more preferably 0.5 mass %, furthermore preferably 1.0 mass %.
• the upper limit is more preferably 15 mass %, furthermore preferably7.5 mass %.
• some kinds of compounds to be used may cause the gelation and thickening of the metal surface treatment composition and the solution stability may deteriorate, it is necessary to blend the compounds within a preferred range.
• the metal surface treatment composition of the present invention further contains a silane coupling agent. It is preferred in that by containing the silane coupling agent, the adhesion of a coat to a metal surface can be improved and the silane coupling agent has an action as a crosslinking agent of the water-borne resin and thereby the corrosion resistance can be improved.
• the silane coupling agent is not particularly limited, and examples thereof may include vinylmethoxysilane, vinyltrimethoxysilane, vinylethoxysilane, vinyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propane amine, N,N′-bis[3-(trimethoxysilyl)propyl]ethylenediamine, (N- ⁇ -aminoethyl)- ⁇ -aminopropylmethyldimethoxysilane, (N- ⁇ -aminoethyl)- ⁇ -aminopropyltrimethoxysilane, ⁇ -aminopropyltrimethoxysilane, ⁇ -
• examples of the particularly preferred silane coupling agent may include vinylmethoxysilane, vinylethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane and N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propane amine, N,N′-bis[3-(trimethoxysilyl)propyl]ethylenediamine.
• the silane coupling agent may be used alone or in combination of two or more species.
• the content of the silane coupling agent in the metal surface treatment composition is preferably within a range of 0.5 mass % (lower limit) to 30 mass % (upper limit) relative to the total nonvolatile matter in the metal surface treatment composition.
• the content of the silane coupling agent is less than 0.5 mass %, it is not preferred since the effect of improving corrosion resistance and adhesion to a chromium-free rust-preventive coating agent may be insufficient, and when it exceeds 30 mass %, it is not preferred since the adding effect will saturate in this range and the addition becomes uneconomical, and in addition the gelation and thickening of the composition may arise and the solution stability may deteriorate.
• the lower limit is more preferably 1 mass % and the upper limit is more preferably 20 mass %.
• the metal surface treatment composition of the present invention preferably contains a phosphate compound.
• the phosphate compound contained in the metal surface treatment composition of the present invention has a function of further improving the rust-preventive property of a surface treatment film by eluting metal, being a material to be treated, and forming a metal salt of phosphate on the surface of the material to be treated.
• the phosphate compound is not particularly limited as long as it is a compound capable of forming phosphate ions in water, and examples thereof may include phosphorous acid, hypophosphorous acid, organic phosphoric acids, organic phosphorous acids, phosphoric acid; phosphate salts such as Na 3 PO 4 , Na 2 HPO 4 and NaH 2 PO 4 ; and polyphosphoric acid such as polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid and ultraphosphoric acid, and salts thereof.
• the content of the phosphate compound in the metal surface treatment composition is preferably within a range of 0.1 mass % (lower limit) to 20 mass % (upperlimit) relative to the total solid matter in the metal surface treatment composition.
• the content is less than 0.1 mass %, it is not preferred since the effect of improving the corrosion resistance may be insufficient, and when it exceeds 20 mass %, it is not preferred since this may cause excessive etching on a galvanized steel plate or the gelation of the composition.
• the lower limit is more preferably 0.5 mass % and the upper limit is more preferably 10 mass %.
• the metal surface treatment composition of the present invention preferably has pH within a range of 6 (lower limit) to 11 (upper limit).
• the pH is less than 6, the stability in mixing the niobium oxide sol may deteriorate and the solution stability of the whole compositions may deteriorate, and in addition this pH may cause excessive etching on a galvanized steel plate to lead to a defective appearance.
• it exceeds 11 it is not preferred since this pH may cause excessive etching on a galvanized steel plate to lead to a defective appearance.
• the lower limit is more preferably 7 and the upper limit is more preferably 10.
• the pH of the metal surface treatment composition is preferably adjusted within the range by adding a basic compound. Particularly, it is more preferred to use volatile compounds such as ammonia and amines as the basic compound.
• the metal surface treatment composition of the present invention preferably contains nonvolatile matter within a range of 3 mass % (lower limit) to 50 mass % (upper limit) on-the mass of the nonvolatile matter basis.
• concentration of the nonvolatile matter is less than 3 mass %, it is not preferred since it may be impossible to attain an sufficient film thickness for maintaining the rust-preventive property in applying the metal surface treatment composition.
• it exceeds 50 mass % it is not preferred since this may cause the gelation of the composition.
• the lower limit is more preferably 10 mass % and the upper limit is more preferably 30 mass %.
• the niobium oxide colloidal particles highly stabilized by the citric acid or salts thereof to be used in the present invention also has the excellent stability in mixing with such electrolyte components as described above. Therefore, the metal surface treatment composition of the present invention, which comprises the respective components described above, is superior in the stability, so that it can perform the surface treatment of a galvanized steel plate with stability.
• a method of producing the metal surface treatment composition of the present invention is not particularly limited, and it can be obtained, for example, by charging the niobium oxide colloidal particles, the water-borne resin, the water-dispersible silica, at least one compound selected from the group consisting of vanadium compounds, zirconium compounds and titanium compounds, the silane coupling agent and the phosphate compound to a container in this order and by stirring the resulting mixture so as to become uniform.
• the metal surface treatment method of the present invention is a method in which a galvanized steel plate is treated with the metal surface treatment composition.
• a galvanized steel plate, which can be treated in the metal surface treatment method of the present invention is not particularly limited, and examples thereof may include steel plates, which are plated with zinc or a zinc-based alloy through electroplating, hot dipping and vacuum evaporation coating, such as a galvanized steel plate, a steel plate plated with a zinc-nickel alloy, a steel plate plated with a zinc-iron alloy, a steel plate plated with a zinc-chromium alloy, a steel plate plated with a zinc-aluminum alloy, a steel plate plated with a zinc-titanium alloy, a steel plate plated with a zinc-magnesium alloy and a steel plate plated with a zinc-manganese alloy.
• the galvanized steel plate degreased as required is treated with the metal surface treatment composition.
• the treating method with the metal surface treatment composition is not particularly limited, and examples thereof may include roller coating, shower coating, air-spray coating, airless-spray coating, curtain flow coating, brush coating and immersion coating, which are commonly used.
• the metal surface treatment composition of the present invention is applied in an application rate of 0.1 g/m 2 (lower limit) to 10.0 g/m 2 (upper limit) as amass of the nonvolatile matter in a coat.
• this application rate is less than 0.1 g/m 2 , there may be cases where the ability to be processed deteriorates or the rust-preventive property is not adequately attained due to insufficient thickness.
• it exceeds 10.0 g/m 2 there may be cases where it is economically disadvantageous since there is not an increase in the effect of increasing a film thickness or winding becomes difficult due to the increased thickness.
• the lower limit is more preferably 0.2 g/m 2 , and furthermore preferably 0.3 g/m 2 .
• the upper limit is more preferably 5.0 g/m 2 , and furthermore preferably 3.0 g/m 2 .
• a temperature, at which the drying is conducted, is preferably within a range of 50° C. (lower limit) to 250° C. (upper limit). When it is less than 50° C., drying efficiency may become worse due to a low evaporation rate of water. When it exceeds 250° C., formed components in a coat may be decomposed due to elevated temperatures. More preferably, the lower limit is 60° C. and the upper limit is 150° C. Drying time is preferably in a rage of 1 second (lower limit) to 300 seconds (upper limit), and more preferably in a rage of 3 seconds (lower limit) to 60 seconds (upper limit).
• the present invention also provides a galvanized steel plate obtained by the metal surface treatment method. Since the galvanized steel plate of the present invention is one on which a good surface treatment coat is formed, it has an excellent rust-preventive property and does not form white color rust.
• the metal surface treatment composition of the present invention is one which comprises the niobium oxide colloidal particles having the excellent stability and provides the galvanized steel plate with the good rust-preventive property and adhesion equal to a chromate-treatment agent without requiring a burden of waste water treatment.
• the metal surface treatment composition it is possible to provide the method of metal surface treatment, which can apply a good metal surface treatment to a galvanized steel plate. Further, by using the method of metal surface treatment of the present invention, it is possible to provide a galvanized steel plate which has the excellent rust-preventive property and adhesion.
• the metal surface treatment composition of the present invention includes the niobium oxide colloidal particles highly stabilized with citric acid or salts thereof, it has the excellent solution stability and provides the good rust-preventive property and adhesion for a film to be obtained. Further, since the metal surface treatment composition of the present invention does not contain components such as chromium and manganese as an essential component, it does not require an excessive burden of waste water treatment.
• a metal surface treatment composition having the composition shown in Table 1 was prepared by following the same procedure as in Example 15 except for changing the niobium oxide colloidal particles to K 2 NbF 7 (made by Morita Chemical Industries Co., Ltd.), which is a soluble niobium compound.
• a concentration of the nonvolatile matter and pH of the obtained metal surface treatment composition is shown in Table 2.
• niobium oxide colloidal particles The niobium oxide colloidal particles, the water-borne resins, the water-dispersible silica, the vanadium compounds, the zirconium compounds, the titanium compounds, the silane coupling agents and the phosphate compounds used in Table 1 were as follows.
• PC 2200 ethylene-acrylic acid copolymer resin, concentration of nonvolatile matter: 30%, made by SHOEI CHEMICAL CO., LTD.
• SUPERFLEX 420 polyurethane resin, concentration of nonvolatile matter: 32%, made by DAI-ICHI KOGYO SEIYAKU CO., LTD.
• JURYMERAC-10L polyacrylic acid, concentration of nonvolatile matter: 40%, made by NIHON JUNYAKU CO., LTD.
• ADELITE AT-20A SiO 2 : 20%, made by Asahi Denka Co., Ltd.
• V ammonium metavanadate
• V vanadium pentoxide (V: 56.0%, reagent)
• Zircosol AC-7 zirconium ammonium carbonate, Zr: 74.0% (on the solid matter basis), made by DAIICHI KIGENSO KAGAKU KOGYO CO., LTD.
• Sila-Ace S-510 ( ⁇ -glycidoxypropyltrimethoxysilane, concentration of nonvolatile matter: 100%, made by CHISSO CORPORATION)
• the resulting test panels were evaluated according to the following methods. The results of measurements are shown in Table 2. The application rate was given by analyzing metal elements in the composition using “XRF-1700” (X-ray fluorescence spectrometer manufactured by Shimadzu Corp.) to yield the contents by mass % of metal elements relative to total nonvolatile matter and converting the content.
• XRF-1700 X-ray fluorescence spectrometer manufactured by Shimadzu Corp.
• a flat portion of each test panel and an end face and a rear face of a formed portion, which was extruded by 8 mm by an Erichsen tester, in each test panel were sealed with a tape and 5% salt water was sprayed to the coated surface of the test panel at 35° C. After a lapse of 72 hours since salt water spray, a rate of the surface area where white color rust was generated was evaluated according to the following criteria.
• the metal surface treatment compositions obtained in Examples 1 to 16 were superior in the solution stability and the films obtained by applying the metal surface treatment compositions had the high corrosion resistance and the good appearances.
• the metal surface treatment compositions obtained in Comparative Examples 1 and 2 could not attain chemical conversion coats which had excellent rust-preventive property, they could not obtain good galvanized steel plates.
• the metal surface treatment composition obtained in Comparative Example 3 was not good in the solution stability and the appearance of the obtained film was inferior to that of Examples.
• the metal surface treatment composition of Comparative Example 4 not containing the niobium oxide colloidal particles, exhibited thickening of solution by secular changes and the appearance and the corrosion resistance of the obtained film were not satisfactory.

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