Formation method for chemical conversion film

Abstract

The purpose of the present invention is to provide a formation method for a chemical conversion film, the method capable of forming a film having excellent corrosion resistance and having excellent coating adhesion under severe conditions, in chemical conversion treatment at normal temperature. This formation method for a chemical conversion film includes a step for bringing a chemical conversion treatment agent into contact with or onto a surface of a metal material, the chemical conversion treatment agent containing a mixture consisting of at least a supply source A of ions containing zirconium, a supply source B of ions containing aluminum, a supply source C of ions containing copper, and a water-soluble or water-dispersible polymer or a salt D thereof having 90% or more of a structural unit represented by formula (i) in terms of mol. The chemical conversion treatment agent addresses the problem by configuring a zirconium elemental concentration, an aluminum elemental concentration, a copper elemental concentration, and a solid content mass concentration of the polymer or the salt D thereof to be in specific ranges, and by satisfying the relationship of formula (1). Formula (1): 900 ≤ t × FF / pH ≤ 4800

Description

Method for forming a chemical conversion coating

[0001] The present invention relates to a method for forming a chemical conversion coating on or over a metal surface.

[0002] Conventionally, treatment liquids for metal surface treatment that can form a chemical conversion coating having excellent corrosion resistance and good adhesion have been developed. For example, Patent Document 1 discloses a treatment liquid for metal surface treatment containing at least one metal (A) selected from the group consisting of copper, tin and cobalt, at least one metal (B) selected from the group consisting of zirconium and titanium, and a predetermined water-soluble resin (C).

[0003] Japanese Patent No. 5643484

[0004] Products to be coated such as home appliances and automobiles are required to have resistance to corrosion and rust (corrosion resistance), and are also required to have sufficient adhesion that prevents the coating film from peeling off even when deformed by impact during processing after coating or use. Conventional chemical conversion treatment methods generally perform treatment in a temperature range higher than room temperature, and chemical conversion coatings formed when treatment is performed in a temperature range around room temperature cannot achieve sufficient corrosion resistance and adhesion. In particular, when a galvanized steel sheet (GI material) is used as the target member, sufficient coating film adhesion cannot be obtained. An object of the present invention is to provide a method for forming a chemical conversion coating that can form a chemical conversion coating excellent in corrosion resistance and coating film adhesion under severe conditions even when the chemical conversion treatment is performed at room temperature.

[0005] As a result of intensive studies conducted by the present inventors to solve the above problems, the present invention has been completed. The inventors have found that a method for forming a chemical conversion coating including a step of bringing a surface treatment agent into contact on or over a surface of a metal material can form a chemical conversion coating excellent in corrosion resistance and coating film adhesion under severe conditions even when the chemical conversion treatment is performed at room temperature, provided that the surface treatment agent satisfies predetermined parameters. The surface treatment agent is formulated with a supply source A of zirconium-containing ions, a supply source B of aluminum-containing ions, a supply source C of copper-containing ions, and a specific water-soluble or water-dispersible polymer or a salt D thereof.

[0006] The present invention includes the following: [1] A method for forming a chemical conversion film, comprising the step of contacting a chemical conversion agent, which comprises at least a source A of zirconium-containing ions, a source B of aluminum-containing ions, a source C of copper-containing ions, and a water-soluble or water-dispersible polymer or salt D thereof having 90% or more of the structural units represented by the following formula (i) on a molar basis, wherein the chemical conversion agent has a zirconium element concentration of 10 mg / L or more and 300 mg / L or less, an aluminum element concentration of 1 mg / L or more and 2000 mg / L or less, a copper element concentration of 1 mg / L or more and 100 mg / L or less, and a solid content mass concentration of the polymer or salt D thereof of 1 mg / L or more and satisfies the relationship of the following formula (1). 900 ≤ t × FF / pH ≤ 4800 ... Equation (1) (In Equation (1), t is the Kelvin temperature (K) and is between 283 and 308, FF is the free fluoride ion concentration (mg / L) in the chemical treatment agent and is between 15 and 100, and pH is between 3.5 and 6.0.) [2] The method for forming a chemical conversion film according to [1], wherein the chemical conversion treatment agent further comprises an amino group-containing silane coupling agent E. [3] The method for forming a chemical conversion film according to [2], wherein the ratio (EC / DC) of the silicon element concentration EC to the solid content mass concentration DC of the water-soluble or water-dispersible polymer or its salt D is 0.02 or more and 1 or less. [4] The method for forming a chemical conversion film according to any one of [1] to [3], wherein the metal material is selected from iron, zinc or zinc-based plated material, aluminum, aluminum alloy material, aluminum-based plated material, magnesium material, and magnesium alloy material.

[0007] According to the present invention, it is possible to provide a method for forming a chemical conversion coating that can form a chemical conversion coating with excellent corrosion resistance and adhesion under harsh conditions, even when chemical conversion treatment is performed at room temperature. In particular, the present invention can provide a chemical conversion coating that exhibits good coating adhesion even to GI materials, for which sufficient coating adhesion could not be obtained with conventional chemical conversion treatment at room temperature.

[0008] This diagram illustrates the evaluation criteria for assessing adhesion in the examples.

[0009] A method for forming a chemical conversion film according to one embodiment of the present invention is described below. In the numerical ranges described in stages in this specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples.

[0010] (Chemical Conversion Agent) The chemical conversion agent used in this embodiment is obtained by blending a predetermined amount of an ion source A containing at least zirconium, an ion source B containing aluminum, an ion source C containing copper, and a water-soluble or water-dispersible polymer or salt thereof D having 90% or more of the structural unit represented by formula (i) on a molar basis, in an aqueous medium. By using this chemical conversion agent, a chemical conversion film with excellent corrosion resistance and adhesion under harsh conditions can be formed on or on the surface of a metal material. The chemical conversion agent used in this embodiment may consist only of ion sources A, B, C, and the predetermined polymer or salt thereof D blended in an aqueous medium, or other components may be further blended.

[0011] (Source of fluoride ions) Since the chemical treatment agent used in this embodiment contains fluoride ions, a source of fluoride ions may be included. The source of fluoride ions is not particularly limited as long as it is a compound that can supply fluoride ions when incorporated into the chemical treatment agent (hereinafter referred to as "fluorine-containing compound"), and fluoride ions may be supplied by sources A to C described later. Examples of fluorine-containing compounds include, but are not limited to, hexafluorozirconium acid, hexafluorotitanium acid, hexafluorohafnium acid, hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, germanium fluoride, potassium fluoride, potassium hydrogen fluoride, iron fluoride, hydrosilicate, sodium fluoride, sodium hydrogen fluoride, etc.

[0012] Compounds containing zirconium and fluorine, such as hexafluorozirconium acid, can supply both zirconium-containing ions and fluorine ions. Furthermore, each fluorine-containing compound may be blended individually or in combination of two or more. While there are no particular limitations on the amount of fluorine-containing compound used, the free fluorine ion concentration in the chemical treatment agent, as measured by a fluorine ion meter (e.g., IM55G manufactured by Toa Denpa Kogyo Co., Ltd.), is typically between 15 mg / L and 100 mg / L. Keeping the free fluorine ion concentration within this range optimizes the reaction rate between the metal material and the chemical treatment agent. This, in turn, optimizes the amount of film formed.

[0013] (Source A) The chemical treatment agent used in this embodiment contains Source A. Source A is not particularly limited as long as it is a compound that can supply zirconium-containing ions (hereinafter referred to as "zirconium-containing ions") when incorporated into the chemical treatment agent. Therefore, the chemical treatment agent contains zirconium-containing ions. Examples of zirconium-containing ions include zirconium metal ions; zirconium-containing complex ions; zirconium oxide ions; and the like.

[0014] Specific examples of source A include hexafluorozirconium acid, zirconium nitrate, zirconium oxonitrate, zirconium carbonate, zirconium hydroxide, and zirconium oxide. Furthermore, if these can take the form of a salt, that salt may be used. Source A may be blended individually or in combination of two or more. The zirconium-containing ion concentration in the chemical treatment agent is not particularly limited, but the zirconium element concentration in the chemical treatment agent is usually between 10 mg / L and 300 mg / L, and preferably between 20 mg / L and 200 mg / L. By keeping the zirconium element concentration in the chemical treatment agent within the above range, an effective amount of zirconium can be used in the chemical conversion coating, resulting in good coating adhesion. If the zirconium element concentration in the chemical treatment agent exceeds 300 mg / L, the coating adhesion to the GI material tends to decrease.

[0015] (Source B) The chemical treatment agent used in this embodiment contains Source B. Source B is not particularly limited as long as it is a compound that can supply aluminum-containing ions (hereinafter referred to as "aluminum-containing ions") when incorporated into the chemical treatment agent. Therefore, the chemical treatment agent contains aluminum-containing ions. Examples of aluminum-containing ions include aluminum metal ions; aluminum-containing complex ions; aluminum oxide ions; and the like.

[0016] Specific examples of aluminum-containing ion source B include, but are not limited to, aluminum hydroxide, aluminum nitrate, aluminum sulfate, aluminum carbonate, and aluminum oxide. Furthermore, if these substances can exist in the form of salts, those salts may be used. These sources may be blended individually or in combination of two or more. The concentration of aluminum-containing ions in the chemical treatment agent is not particularly limited, but the concentration of aluminum element in the chemical treatment agent is usually between 1 mg / L and 2000 mg / L. By keeping the aluminum element concentration within the above range, the concentration of free fluoride ions in the chemical treatment agent can be maintained within an appropriate range.

[0017] (Source C) The chemical treatment agent used in this embodiment contains Source C. Source C is not particularly limited as long as it is a compound that can supply copper-containing ions (hereinafter referred to as "copper-containing ions") when blended with the chemical treatment agent. Therefore, the chemical treatment agent contains copper-containing ions. Examples of copper-containing ions include copper metal ions; copper-containing complex ions; copper oxide ions; and the like.

[0018] Specific examples of copper-containing ion source C include, but are not limited to, copper hydroxide, copper nitrate, copper sulfate, copper carbonate, and copper oxide. Furthermore, if these substances can take the form of salts, those salts may be used. These sources may be blended individually or in combination of two or more. The concentration of copper-containing ions in the chemical conversion agent is not particularly limited, but the copper element concentration in the chemical conversion agent is usually 1 mg / L or more, preferably 2 mg / L or more, more preferably 5 mg / L or more, and usually 100 mg / L or less, preferably 60 mg / L or less, and more preferably 40 mg / L or less. By keeping the copper element concentration within the above range, the reaction rate between the metal material and the chemical conversion agent during chemical conversion treatment at room temperature becomes favorable. This results in the formation of a chemical conversion film with excellent corrosion resistance and coating adhesion.

[0019] (Water-soluble or water-dispersible polymer or its salt D) The chemical treatment agent used in this embodiment contains a water-soluble or water-dispersible polymer or its salt D (hereinafter simply referred to as "polymer D"). Polymer D is a polymer having 90% or more of the structural unit represented by formula (i) on a molar basis. Specifically, polymer D can be described as diallylamine polymer; salts of diallylamine polymers such as diallylamine hydrochloride polymer, diallylamine sulfate polymer, and diallylamine acetate polymer; and other polydiallylamines.

[0020] The weight-average molecular weight of polymer D is not particularly limited, but is usually 1,000 or more, preferably 5,000 or more. The upper limit is not particularly limited, but is usually 1,000,000 or less, may be 500,000 or less, or 100,000 or less. The weight-average molecular weight is measured by GPC (gel permeation column chromatography) and converted to polystyrene equivalent. The content of polymer D in the chemical treatment agent is usually 1 mg / L or more and 300 mg / L or less as a solid mass concentration. By keeping the content of polymer D within the above range, the corrosion resistance and coating adhesion of the chemical coating film are improved.

[0021] (Aqueous medium) The chemical treatment agent used in this embodiment may contain an aqueous medium. The aqueous medium is not particularly limited as long as it is water or a mixture of water and a water-miscible organic solvent (containing 50% or more water by volume based on the volume of the aqueous medium). The water-miscible organic solvent is not particularly limited as long as it is miscible with water, and examples include ketone solvents such as acetone and methyl ethyl ketone; amide solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol solvents such as methanol, ethanol and isopropanol; ether solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone. One of these water-miscible organic solvents may be mixed with water, or two or more may be mixed with water.

[0022] (Other components) Other additives may be added to the chemical treatment agent used in this embodiment, as long as they do not hinder the effects of the present invention. Specifically, examples include amino group-containing silane coupling agent E, organic acid, oxidizing agent, metal ion sources other than sources A, B, and C, metal alkoxides, water-soluble resins other than polymer D or water-dispersible resins, surfactants, pH adjusters, etc. Furthermore, only one of these other components may be added, or two or more may be added.

[0023] (Amino group-containing silane coupling agent E) The amino group-containing silane coupling agent E (hereinafter simply referred to as "coupling agent E") is not particularly limited as long as it is a silane coupling agent having an amino group in its chemical structure. Coupling agent E may have a primary amino group, a secondary amino group, or a tertiary amino group, or it may have multiple amino groups. Specifically, examples include N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyldimethylmethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyldiethylethoxysilane, N-2-(aminoethyl)-3-aminopropylethyldiethoxysilane, 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyldiethylethoxysilane, and 3-aminopropylethyldiethoxysilane. Furthermore, the coupling agent E in the chemical treatment agent may be in its original form, in the form of a hydrolyzed product obtained by hydrolysis of the coupling agent E, in the form of a condensed polymer obtained by condensation polymerization of the hydrolyzed product, in the form of a copolymer obtained by copolymerization of each hydrolyzed product (alternating copolymer, random copolymer, block copolymer, graft copolymer, etc.), or a mixture of multiple forms may be present.

[0024] When a coupling agent E is incorporated, the ratio (EC / DC) of the silicon element concentration (EC) derived from the coupling agent E in the chemical conversion agent to the solid content mass concentration (DC) of polymer D is preferably 0.02 or more and 1 or less. Here, the silicon element concentration (EC) derived from the coupling agent E means the sum of the mass concentrations (mg / L) of the silicon element in each of the above forms derived from the coupling agent E, and when two or more types of coupling agents E are incorporated into the chemical conversion agent, it means the sum of the silicon element concentrations derived from them. When EC / DC is within the above range, the corrosion resistance and coating adhesion of the chemical conversion film are further improved.

[0025] (Organic Acids) Examples of organic acids include, but are not limited to, organic sulfonic acids, aliphatic carboxylic acids, and aromatic carboxylic acids. Organic sulfonic acids are organic compounds having at least one sulfo group, and examples include methanesulfonic acid, ethanesulfonic acid, and benzenesulfonic acid. Aliphatic carboxylic acids are compounds in which at least one hydrogen atom of a saturated or unsaturated hydrocarbon is substituted with a carboxyl group, and examples include acetic acid, lactic acid, oxalic acid, and citric acid. Aromatic carboxylic acids are hydrocarbon compounds having an aromatic ring in which at least one hydrogen atom on the aromatic ring is substituted with a carboxyl group, and examples include benzoic acid and phthalic acid. Organic acids may be included individually or in combination of two or more types.

[0026] (Oxidizing agent) Examples of oxidizing agents include hydrogen peroxide, nitrates, nitrites, permanganates, chlorates, bromates, persulfates, nitro group-containing compounds, hypochlorous acid, and organic peroxides. Hydrogen peroxide, nitrates, and nitrites are preferred, but the product is not limited to these. Only one oxidizing agent may be included, or two or more may be included.

[0027] (Sources of metal ions other than sources A, B, and C) Examples of sources of metal ions other than sources A, B, and C include compounds containing iron, manganese, magnesium, nickel, cobalt, zinc, tungsten, molybdenum, etc., but are not limited to these. Only one source of metal ions other than sources A, B, and C may be included, or two or more may be included.

[0028] (Metal Alkoxides) Examples of metal alkoxides include, but are not limited to, zirconium alkoxides such as zirconium tetrapropoxide, zirconium tetraisopropoxide, zirconium tetran-propoxide, and zirconium tetran-butoxide; titanium alkoxides such as titanium methoxide, titanium ethoxide, titanium tetraisopropoxide, titanium tetran-butoxide, titanium butoxide dimer, and titanium tetra-2-ethylhexoxide; vanadium alkoxides such as triisopropoxyvanadium(V) oxide, vanadium butoxide, and triethoxyvanadium(V) oxide; and aluminum alkoxides such as aluminum isopropoxide and aluminum-tert-butoxide. Metal alkoxides may be blended individually or in combination of two or more types.

[0029] Furthermore, the metal alkoxides in the chemical treatment agent may be in their original form, in the form of hydrolyzed metal alkoxides, in the form of condensed polymers obtained by condensation polymerization of the hydrolyzed metal alkoxides or hydrolyzed organic silane compounds, in the form of copolymers (alternating copolymers, random copolymers, block copolymers, graft copolymers, etc.) obtained by copolymerization of each hydrolyzed product or hydrolyzed organic silane compound, or a mixture of multiple forms may be present. The metal alkoxide containing zirconium is also source A, and the metal alkoxide containing aluminum is also source B.

[0030] (Water-soluble resins or water-dispersible resins other than polymer D) Examples of water-soluble resins or water-dispersible resins other than polymer D include, but are not limited to, poly(meth)acrylic acid resins, urethane resins, acrylic resins, epoxy resins, phenolic resins, and amine resins that do not contain the structural unit represented by formula (i). Only one water-soluble resin or water-dispersible resin other than polymer D may be blended into the chemical treatment agent, or two or more may be blended.

[0031] (Surfactants) Examples of surfactants include nonionic surfactants and ionic surfactants such as cationic, anionic, or amphoteric surfactants. Examples of nonionic surfactants are not particularly limited, but include polyethylene glycol-type nonionic surfactants such as polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene-polyoxypropylene-block polymer; polyhydric alcohol-type nonionic surfactants such as sorbitan fatty acid ester; and amide-type nonionic surfactants such as fatty acid alkylolamide. Examples of cationic surfactants are not particularly limited, but include amine salt-type cationic surfactants such as higher alkylamine salts and polyoxyethylene higher alkylamines; and quaternary ammonium salt-type cationic surfactants such as alkyltrimethylammonium salt. Examples of anionic surfactants are not particularly limited, but include higher alkyl ether sulfate ester salts to which ethylene oxide has been added. The HLB value (calculated by the Griffin method) of the above surfactants is not particularly limited, but is preferably 6 to 18, and more preferably 10 to 14. The above-mentioned surfactant may be included in the chemical treatment agent by one or more types. By including the above-mentioned surfactant in the chemical treatment agent, it becomes possible to perform chemical treatment and degreasing treatment simultaneously in a single step.

[0032] (pH adjusters) Examples of pH adjusters include acidic and alkaline components. Acidic components are not particularly limited, but examples include hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, sodium hydrogen fluoride, ammonium salts, and organic acids. Alkaline components are not particularly limited, but examples include lithium hydroxide, potassium hydroxide, sodium hydroxide, magnesium hydroxide, barium hydroxide, alkali metal salts, ammonia, and amines. Only one pH adjuster may be included, or two or more may be included.

[0033] (pH of the chemical conversion agent) The pH of the chemical conversion agent used in this embodiment is usually in the range of 3.5 to 6.0, and more preferably in the range of 4.0 to 5.6. Here, the pH value in this specification refers to the value measured at 25°C using a pH meter. When a metal material is brought into contact with a chemical conversion agent within the above pH range, a pH increase occurs due to the dissolution reaction of the metal material, and a uniform chemical conversion film is formed on or on the surface of the metal material. If the pH falls below 3.5, the dissolution reaction of the metal material becomes excessive, and the uniformity of the chemical conversion film tends to be impaired. Also, if the pH exceeds 6.0, the film components in the chemical conversion agent become unstable, and the stability of the chemical conversion agent tends to be impaired.

[0034] (Method for producing the chemical treatment agent) The above chemical treatment agent can be produced by mixing a predetermined amount of at least supply source A, supply source B, supply source C, and a predetermined polymer or its salt D into an aqueous medium.

[0035] (Method for forming a chemical conversion coating) The method for forming a chemical conversion coating on the surface of a metal material according to this embodiment includes the step of bringing the chemical conversion treatment agent into contact with the surface of the metal material. This forms a chemical conversion coating on the surface of the metal material. The method for bringing the chemical conversion treatment agent into contact with the metal material includes, but is not limited to, conventional contact methods such as immersion treatment, spray treatment, pouring treatment, or combinations thereof.

[0036] The contact temperature in the above contact process is usually within the range of 10°C to 35°C, as it is performed at room temperature. The contact time is preferably within the range of 30 seconds to 480 seconds, and more preferably within the range of 60 seconds to 300 seconds, but is not limited to these times.

[0037] (Values ​​of specific parameters) The chemical conversion agent used in this embodiment satisfies the following formula (1): 900 ≤ t × FF / pH ≤ 4800 ... formula (1) In formula (1), t is the Kelvin temperature (K) and is between 283 and 308. FF is the free fluoride ion concentration (mg / L) in the chemical conversion agent and is between 15 and 100. pH is between 3.5 and 6.0. The value of formula (1) is preferably between 1400 and 4000, more preferably between 1700 and 3500. When the value of formula (1) is within the above range, the reaction rate between the metal material and the chemical conversion agent is optimized during chemical conversion treatment at room temperature. This results in the formation of a chemical conversion film with excellent corrosion resistance and coating adhesion. The value of FF is preferably between 20 and 85, more preferably between 20 and 70.

[0038] Furthermore, a pretreatment step may be performed before the step of contacting the chemical treatment agent. Examples of pretreatment steps include: pickling; degreasing; alkaline cleaning; chromate chemical treatment; phosphate chlorination treatment using phosphates such as zinc phosphate and iron phosphate; bismuth substitution plating; iron substitution plating; zirconium chemical treatment; titanium chemical treatment; hafnium chemical treatment; vanadium chemical treatment. Note that these pretreatment steps may be performed individually, or two or more steps may be combined and performed sequentially. Examples of combinations of two or more steps include a phosphate chlorination treatment step and a combination of a chromate chemical treatment step, bismuth substitution plating step, iron substitution plating step, zirconium chemical treatment step, titanium chemical treatment step, hafnium chemical treatment step, or vanadium chemical treatment step. The zirconium chemical treatment step performed as a pretreatment step may use the chemical treatment agent according to this embodiment, or a chemical treatment agent different from the chemical treatment agent according to this embodiment may be used. Furthermore, when performing the various pretreatment steps described above, a water rinsing step may be performed after each pretreatment step. When performing multiple pretreatment steps, a water rinsing step may be performed after each step, or after some of the steps. In addition, if a water rinsing step is performed, a drying step may be performed afterward to dry the surface of the metal material.

[0039] Furthermore, a post-treatment step may be performed after the step of contacting the material with the chemical treatment agent. Examples of post-treatment steps include alkaline washing, water washing, chromate chemical treatment, zinc phosphate chemical treatment, bismuth substitution plating, iron substitution plating, iron phosphate chemical treatment, zirconium chemical treatment, titanium chemical treatment, hafnium chemical treatment, and drying. One of these post-treatment steps may be performed, or two or more steps may be combined and performed sequentially. The chemical treatment step performed as a post-treatment step may use the chemical treatment agent according to this embodiment, or a different chemical treatment agent may be used. When performing any of the above post-treatment steps, a water washing step may be performed after each post-treatment step. When performing multiple post-treatment steps, a water washing step may be performed after each step, or after some of the steps. Furthermore, if a water washing step is performed, a drying step may be performed afterward to dry the surface of the metal material.

[0040] Furthermore, a painted metal material having a chemical conversion coating and a coating can also be manufactured by forming a coating on the surface of a metal material or on a chemical conversion coating formed by a method for forming a chemical conversion coating on a surface according to this embodiment. In this case, after the formation of the chemical conversion coating, a coating formation process such as a painting process and a drying process (which may include a baking process and a hardening process, etc.) for drying the paint on the surface of the painted metal material may be performed to form the coating. Before the painting process, a water washing process may be performed to wash the surface of the metal material that has been in contact with the chemical conversion treatment agent according to this embodiment. Alternatively, a drying process may be performed to dry the surface of the metal material that has been in contact with the chemical conversion treatment agent, or the surface of the metal material that has undergone the water washing process. Furthermore, one or more of the above post-treatment processes may be performed after the contact process and before the painting process. When performing the above various post-treatment processes, a water washing process may be performed after each of the post-treatment processes. When performing multiple post-treatment processes, a water washing process may be performed after each process, or after some of the processes. Furthermore, if a water washing process is performed, a drying process may be carried out afterward to dry the surface of the metal material.

[0041] The coating step described above is performed on the surface of the metal material with the chemical conversion coating using a coating material. The coating method is not particularly limited, and conventionally known methods can be applied, for example, methods such as roll coating, electrodeposition coating (e.g., cationic electrodeposition coating, anionic electrodeposition coating, etc.), spray coating, hot spray coating, airless spray coating, electrostatic (powder) coating, roller coating, curtain flow coating, brush coating, bar coating, fluidized dipping method, etc.

[0042] Examples of the coating material include known coating materials such as oil-based coatings, cellulose derivative coatings, phenolic resin coatings, alkyd resin coatings, aminoalkyd resin coatings, urea resin coatings, unsaturated resin coatings, vinyl resin coatings, acrylic resin coatings, epoxy resin coatings, polyurethane resin coatings, silicone resin coatings, fluororesin coatings, anti-rust paints, antifouling coatings, powder coatings, cationic electrodeposition coatings, anionic electrodeposition coatings, water-based coatings, solvent-based coatings, and the like. In the coating step, one coating operation may be performed, or two or more coating operations may be performed using various same or different coating materials.

[0043] A known method can be applied for the cationic electrodeposition coating described above. For example, a method may be mentioned in which a cationic electrodeposition coating containing an amine-added epoxy resin as a coating component and a blocked polyisocyanate curing agent as a curing component is used, and the metal material with a chemical conversion coating is immersed in this coating. Cationic electrodeposition coating is performed, for example, by maintaining the temperature of the coating at a predetermined temperature, stirring the coating, and applying a voltage using a rectifier with the metal material with the chemical conversion coating as a cathode. A coating film can be formed on the chemical conversion coating by washing the metal material subjected to cationic electrodeposition coating as described above with water and baking it. Baking is performed for a certain period of time within a predetermined temperature range. For example, an embodiment in which baking is performed at 170°C for 20 minutes may be mentioned. When applying a cationic electrodeposition coating method using a cationic electrodeposition coating, it is preferable to perform the water washing step using water having a sodium ion concentration of less than 500 ppm by mass.

[0044] As a coating method using powder coating, such as spray coating, electrostatic powder coating, and fluidized dipping, known methods can be applied. Examples of powder coatings include those containing a polyester resin and, as a curing agent, a blocked isocyanate curing agent, a β-hydroxyalkylamide curing agent (see, for example, Japanese Patent Laid-Open No. 2011-88083), or triglycidyl isocyanurate. Baking is performed for a certain period of time within a predetermined temperature range. For example, an embodiment in which baking is performed for 20 minutes within a range of 130°C or higher and 250°C or lower can be mentioned.

[0045] As a coating method using the above solvent-based coating, such as spray coating, electrostatic coating, and bar coating, known methods can be applied. Examples of solvent-based coatings include those containing a resin such as melamine resin, acrylic resin, urethane resin, or polyester resin, and an organic solvent such as thinner. Baking is performed for a certain period of time within a predetermined temperature range. For example, an embodiment in which baking is performed at 130°C for 20 minutes can be mentioned.

[0046] The above drying step is a treatment of drying and curing the applied coating. Examples of drying methods for curing the applied coating include natural drying, reduced pressure drying, convective heat drying (e.g., natural convection heat drying, forced convection heat drying), radiation drying (e.g., near-infrared drying, far-infrared drying), UV curing drying, electron beam curing drying, and vapor cure. One of these drying methods may be carried out, or two or more thereof may be carried out in combination.

[0047] The coating film obtained by the coating step may be a single layer or a multi-layer. In the case of a multi-layer, the coating for forming each coating film, the coating method using the coating, the drying method for the coated metal material, etc. may each be the same or different.

[0048] Examples of metal materials include iron (e.g., cold-rolled steel sheets, hot-rolled steel sheets, high-tensile steel sheets, tool steel, alloy tool steel, spheroidized graphite cast iron, gray cast iron, etc.); plating materials, for example, zinc and zinc-based plating materials (e.g., electroplating, hot-dip galvanizing, hot-dip zinc-aluminum plating, hot-dip zinc-aluminum-magnesium plating, alloyed hot-dip galvanizing, electroplating, etc.); aluminum and aluminum alloy materials (e.g., 1000 series aluminum alloy materials, 2000 series aluminum alloy materials, 3000 series aluminum alloy materials, 4000 series aluminum alloy materials, 5000 series aluminum alloy materials, 6000 series aluminum alloy materials, 7000 series aluminum alloy materials, 8000 series aluminum alloy materials, aluminum castings, aluminum alloy castings, die-cast materials, etc.); aluminum-based plating materials; and magnesium and magnesium alloy materials (e.g., AZ91, AZ61, AZ31, etc.).

[0049] The chemical conversion coating formed by the chemical conversion coating formation method according to this embodiment has a zirconium content of 5 mg / m² per unit area. ２ Preferably, it is 10 mg / m² or more. ２ It is more preferable that the amount be greater than or equal to 20 mg / m². ２ It is even more preferable that the value be greater than or equal to the above. The upper limit is not particularly limited, but is 800 mg / m². ２ The following is preferable. The mass of zirconium in this chemical conversion film can be measured, for example, using an X-ray fluorescence analyzer.

[0050] A metal material having a chemical conversion coating formed by the chemical conversion coating formation method according to this embodiment may have one or more of the above-mentioned coatings (for example, a chromate chemical conversion coating, a phosphate chloride conversion coating, a bismuth substitution plating coating, an iron substitution plating coating, etc.) on or below the chemical conversion coating obtained by contacting it with the chemical conversion treatment agent according to this embodiment.

[0051] A painted metal material having a chemical conversion coating and a coating can be manufactured by forming a coating on the surface of a metal material or on a chemical conversion coating formed by a method for forming a chemical conversion coating on a surface according to this embodiment. The painted metal material may have a coating on the surface of a metal material having a chemical conversion coating according to this embodiment, or it may have a coating on the surface of one or more of the above-mentioned coatings (e.g., chromate conversion coating, phosphate chlorine conversion coating, bismuth substitution plating coating, iron substitution plating coating, vanadium conversion coating, etc.) further formed on the chemical conversion coating. The coating may consist of one layer or two or more layers. The thickness of the coating is not particularly limited and is set appropriately according to the intended use of the painted metal material. The uses of the painted metal material are not particularly limited, but it can be used in various applications such as automobile bodies and automobile parts.

[0052] The effects of the present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited by the following examples. <Metal materials> The metal materials were prepared by cutting each of the following to a size of 70 mm in length x 150 mm in width: cold-rolled mild steel sheet conforming to the standard of JIS G3141:2011 (SPCC: thickness 0.8 mm), alloyed hot-dip galvanized steel sheet conforming to the standard of JIS G3302:2012 (GA: thickness 0.8 mm), hot-dip galvanized steel sheet conforming to the standard of JIS G3302:2012 (SGCC: thickness 0.8 mm), and aluminum alloy sheet conforming to the standard of JIS H4000:2014 (A6061: thickness 0.8 mm).

[0053] The components used in the preparation of the chemical treatment agent are listed below. (Source A) A1: Hexafluorozirconium acid (Source B) B1: Aluminum nitrate notahydrate B2: Aluminum sulfate (Source C) C1: Copper(II) nitrate trihydrate C2: Copper(II) sulfate pentahydrate (Polymer compounds) D1: Diallylamine hydrochloride copolymer (100% of formula (i)) D2: Diallylamine hydrochloride / acrylamide copolymer (90% of formula (i)) d3: Allylamine hydrochloride / diallylamine hydrochloride copolymer (50% of formula (i)) d4: Polyacrylic acid D5: Polydiallylamine (average molecular weight: 200,000) D6: Polydiallylamine (average molecular weight: 40,000) D7: Polydiallylamine (average molecular weight: 20,000) (Silane coupling agent) E1: N-2-(aminoethyl)-3-aminopropyltriethoxysilane E2: 3-aminopropyltriethoxysilane e3: tetraethoxysilane

[0054] <Preparation of Chemical Treatment Agents> As shown in Table 1, after mixing predetermined amounts of each component with water so that each component reaches the predetermined concentration, the chemical treatment agents for Examples 1 to 138 and Comparative Examples 1 to 57 were prepared by adjusting the pH and free fluorine concentration with sodium hydroxide and sodium hydrogen fluoride.

[0055] <Manufacturing of Metal Materials with Chemical Conversion Coatings> As shown in the chemical conversion treatment conditions in Table 1, various metal materials were treated to produce metal materials with chemical conversion coatings. Specifically, various metal materials were dissolved in water with a degreasing agent (FC-E2093; Nippon Parkerizing Co., Ltd.; concentration of agent A 13 g / L, agent B 11 g / L), and CO2 was used. ２ The metal materials were immersed in an alkaline solution (pH adjusted to 11.5 using gas) at 43°C for 120 seconds. Afterward, they were spray-washed at 25°C for 30 seconds. Subsequently, the degreased and spray-washed metal materials were immersed in various chemical conversion agents (chemical conversion agents from Examples 1-138 and Comparative Examples 1-57) at the temperatures shown in Table 1 for 180 seconds to form a chemical conversion film on the surface of the metal materials. The surface of the metal materials with the resulting chemical conversion film was washed at 25°C with tap water and then deionized water. The test pieces for corrosion resistance and adhesion tests were not dried and were subjected to the painting described later. The test pieces for chemical conversion appearance evaluation were dried at 40°C for 10 minutes.

[0056] (Comparative Example 58) A metal material having a chemical conversion coating according to Comparative Example 58 was produced in the same manner as described above, except that the chemical conversion agent described in Example 2 of Patent Document 1 was used, and the chemical conversion treatment conditions described in Example 2 of Patent Document 1 (immersion of various metal materials at 50°C for 120 seconds) were used. The chemical conversion agent described in Example 2 of Patent Document 1 contained hydrofluoric acid: 28 mmol / L, copper nitrate: 0.16 mmol / L (copper element concentration: 10 mg / L), zirconium oxonitrate: 2.10 mmol / L (zirconium element concentration: 192 mg / L), ammonium nitrate: 300 mmol / L, zinc nitrate: 30 mmol / L, aluminum nitrate: 7.4 mmol / L (aluminum element concentration: 197 mg / L), and polydiallylamine (average molecular weight: 200,000): 50 mg / L, and the pH was adjusted to 3.0 using ammonia water. The measured free fluorine concentration was 4 mg / L. Furthermore, the value of equation (1) was 431.

[0057] (Comparative Example 59) A metal material having a chemical conversion coating according to Comparative Example 59 was produced in the same manner as described above, except that the chemical conversion agent described in Example 4 of Patent Document 1 was used, and the chemical conversion treatment conditions described in Example 4 of Patent Document 1 (immersion of various metal materials at 40°C for 60 seconds) were used. The chemical conversion agent described in Example 4 of Patent Document 1 contains hydrofluoric acid: 300.7 mmol / L, copper nitrate: 1.58 mmol / L (copper element concentration: 100 mg / L), hexafluorozirconium acid: 0.55 mmol / L (zirconium element concentration: 50 mg / L), ammonium nitrate: 60 mmol / L, zinc sulfate: 15.3 mmol / L, aluminum nitrate: 74 mmol / L (aluminum element concentration: 1997 mg / L), and polydiallylamine (average molecular weight: 40000): 150 mg / L, and the pH was adjusted to 4.0 using ammonia water. The measured free fluorine concentration was 68 mg / L. Furthermore, the value of equation (1) was 5321.

[0058] (Comparative Example 60) A metal material having a chemical conversion coating according to Comparative Example 60 was produced in the same manner as described above, except that the chemical conversion agent described in Example 7 of Patent Document 1 was used and the chemical conversion treatment conditions described in Example 7 of Patent Document 1 (immersion of various metal materials at 45°C for 90 seconds) were used. The chemical conversion agent described in Example 7 of Patent Document 1 contains acidic ammonium fluoride: 81.5 mmol / L, copper sulfate: 0.79 mmol / L (copper element concentration: 50 mg / L), zirconium oxonite: 2.19 mmol / L (zirconium element concentration: 200 mg / L), ammonium nitrate: 100 mmol / L, zinc sulfate: 15.2 mmol / L, aluminum nitrate: 74 mmol / L (aluminum element concentration: 1997 mg / L), polydiallylamine (average molecular weight: 20000): 500 mg / L, and hydroxyethylidene diphosphonic acid: 50 mg / L, and the pH was adjusted to 4.0 using ammonia water. The measured free fluorine concentration was 2 mg / L. The value of equation (1) was 159.

[0059] (Comparative Example 61) A metal material having a chemical conversion coating according to Comparative Example 61 was produced by performing a chemical conversion treatment in the same manner as in Comparative Example 58, except that the chemical conversion treatment conditions were immersion at 25°C for 180 seconds. The value of formula (1) at this time was 397.

[0060] (Comparative Example 62) A metal material having a chemical conversion coating according to Comparative Example 62 was produced by performing a chemical conversion treatment in the same manner as in Comparative Example 59, except that the chemical conversion treatment conditions were immersion at 25°C for 180 seconds. The value of formula (1) at this time was 5066.

[0061] (Comparative Example 63) A metal material having a chemical conversion coating according to Comparative Example 63 was produced by performing a chemical conversion treatment in the same manner as in Comparative Example 60, except that the chemical conversion treatment conditions were immersion at 25°C for 180 seconds. The value of formula (1) at this time was 149.

[0062]

[0063]

[0064]

[0065]

[0066] <Manufacturing of Metal Materials with Coatings> After painting a chemical conversion coating formed on the surface of various metal materials, the coating was baked to produce metal materials with coatings. The details of the painting method and baking conditions are shown below.

[0067] (Cationic Electrodeposition Coating) A coating film was formed by electrolysis using a cationic electrodeposition paint (KG-400; manufactured by Kansai Paint Co., Ltd.) with a metal material having various chemical conversion coatings as the cathode. The electrolysis was carried out at an applied voltage of 180V and a temperature of 30.0±0.5℃. The amount of electricity was adjusted during electrolysis so that the coating film thickness was 15.0±1.0μm. After cationic electrodeposition, the surface of the coating film was washed with deionized water and baked at 170℃ for 20 minutes to produce metal materials (each test piece) with a coating film.

[0068] <Corrosion Resistance Test (VDA Method)> Using a utility knife, a single scratch reaching the metal substrate was made in the center of the coating surface of each test piece with a coating, and a corrosion cycle test according to VDA test 621-415 was performed for 6 cycles. The width of the coating blister from the scratch (cut) part of the test piece (maximum blister width on one side) was measured. Corrosion resistance was evaluated according to the following evaluation criteria. <Evaluation Criteria - Cut Part> S: Blister width on one side is less than 4.0 mm A: Blister width on one side is 4.0 mm or more and less than 6.0 mm B: Blister width on one side is 6.0 mm or more and less than 8.0 mm C: Blister width on one side is 8.0 mm or more and less than 10.0 mm D: Blister width on one side is 10.0 mm or more

[0069] <Adhesion Test> In a DuPont impact test based on JIS K 5600-5-3, the weight was dropped onto the center of the coated surface of each test piece with a coating, at a height of 500 mm, a weight mass of 1000 g, a spherical radius SR of the impact point of 6.35 mm, and a receiving base hole diameter of φ9.52 mm. After dropping the weight, the tape was peeled off the convex part of the test piece using commercially available tape (Scotch Tape®; manufactured by Nichiban Co., Ltd.), and the degree of coating remaining was evaluated according to the following evaluation criteria. Examples of each evaluation are shown in Figure 1. <Evaluation Criteria> SS: 100% of the coating area remains S: 95% or more and less than 100% of the coating area remains A: 85% or more and less than 95% of the coating area remains B: 65% or more and less than 85% of the coating area remains C: 35% or more and less than 65% of the coating area remains D: Less than 35% of the coating area remains

[0070] <Stability of the chemical treatment agent> The liquid stability of the chemical treatment agent in each example and comparative example was visually determined 24 hours after preparation. <Evaluation criteria> S: No precipitate D: Precipitate present

[0071] <Appearance of Chemical Conversion Coatings> The appearance of the chemical conversion coatings on test specimens obtained in each example and comparative example was visually evaluated. <Evaluation Criteria> S: No unevenness in the appearance of the test specimen D: Unevenness in the appearance of the test specimen The results of each evaluation test are shown in Table 2. In all evaluations, C or higher was considered a passing level.

[0072]

[0073]

[0074]

[0075]

[0076] The present invention will be described in detail with reference to specific examples, but it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

Claims

1. A method for forming a chemical conversion film, comprising the step of contacting a chemical conversion agent, which comprises at least a source A of zirconium-containing ions, a source B of aluminum-containing ions, a source C of copper-containing ions, and a water-soluble or water-dispersible polymer or salt D thereof having 90% or more of the structural units represented by the following formula (i) on a molar basis, wherein the chemical conversion agent has a zirconium element concentration of 10 mg / L or more and 300 mg / L or less, an aluminum element concentration of 1 mg / L or more and 2000 mg / L or less, a copper element concentration of 1 mg / L or more and 100 mg / L or less, and a solid content mass concentration of the polymer or salt D thereof of 1 mg / L or more and satisfies the relationship of the following formula (1). 900 ≤ t × FF / pH ≤ 4800 ... Equation (1) (In Equation (1), t is the Kelvin temperature (K) and is between 283 and 308, FF is the free fluoride ion concentration (mg / L) in the chemical treatment agent and is between 15 and 100, and pH is between 3.5 and 6.0.) 2. The method for forming a chemical conversion film according to claim 1, wherein the chemical conversion treatment agent further comprises an amino group-containing silane coupling agent E.

3. The method for forming a chemical conversion film according to claim 2, wherein the chemical conversion agent has a ratio (EC / DC) of the silicon element concentration EC to the solid content mass concentration DC of the water-soluble or water-dispersible polymer or its salt D of 0.02 or more and 1 or less.

4. The method for forming a chemical conversion film according to any one of claims 1 to 3, wherein the metal material is selected from iron, zinc or zinc-plated material, aluminum, aluminum alloy, aluminum-plated material, magnesium, and magnesium alloy.

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