Method for forming chemical conversion films

Abstract

This invention provides a chemical conversion coating method that enables the formation of a coating with excellent corrosion resistance and coating adhesion under harsh conditions during chemical conversion treatment at room temperature. [Solution] A method for forming a chemical conversion film, comprising the step of contacting a chemical conversion agent, which comprises at least a zirconium-containing ion source A, an aluminum-containing ion source B, a copper-containing ion source C, and a water-soluble or water-dispersible polymer or salt thereof D (for example, salts of diallylamine polymers such as diallylamine polymer, diallylamine hydrochloride polymer, diallylamine sulfate polymer, diallylamine acetate polymer, and polydiallylamines), onto the surface of a metal material, wherein the chemical conversion agent has a zirconium element concentration, an aluminum element concentration, a copper element concentration, and a solid content mass concentration of the polymer or salt thereof D within a specific range.

Description

[Technical Field]

[0001] The present invention relates to a method for forming a chemical conversion coating on or at the surface of a metal. [Background Art]

[0002] Conventionally, treatment liquids for metal surface treatment capable of forming 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). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent No. 5643484 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] Products to be coated such as home appliances and automobiles are required to have resistance to the occurrence of corrosion and rust (corrosion resistance), and also required to have sufficient adhesion that prevents the coating film from peeling off due to deformation caused by processing after coating or impact during use. Conventional chemical conversion treatment methods generally perform treatment in a temperature range higher than normal temperature, and when treatment is performed in a temperature range around normal temperature, the resulting chemical conversion coating cannot obtain 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 chemical conversion coating forming method capable of forming a chemical conversion coating excellent in corrosion resistance and coating film adhesion under severe conditions even when the chemical conversion treatment is performed at normal temperature. [Means for Solving the Problems]

[0005] As a result of diligent research to solve the above problems, the present inventors have found that a method for forming a chemical conversion coating, comprising the step of contacting a surface treatment agent containing a zirconium-containing ion source A, an aluminum-containing ion source B, a copper-containing ion source C, and a specific water-soluble or water-dispersible polymer or its salt D, with the surface treatment agent, and that by satisfying predetermined parameters, a chemical conversion coating with excellent corrosion resistance and adhesion to harsh conditions can be formed even with chemical conversion treatment at room temperature, thus completing the present invention.

[0006] This 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, onto the surface of a metal material, A method for forming a chemical conversion film, 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 the solid content mass concentration of the polymer or its salt D is 1 mg / L or more and 300 mg / L or less, and satisfies the relationship of the following formula (1). 900≦t×FF / pH≦4800...Equation (1) (In formula (1) above, 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 3. (It is between 5 and 6.0.) [ka] [2] The method for forming a chemical coating according to [1], further comprising the chemical treatment agent E containing an amino group. [3] The chemical conversion treatment agent has a ratio (EC / DC) of the silicon element concentration EC to the solid content mass concentration DC of the polymer D of 0.02 or more and 1 or less, the method for forming a chemical conversion film according to [2]. [4] A 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-plated material, aluminum, aluminum alloy material, aluminum-plated material, magnesium material, and magnesium alloy material. [Effects of the Invention]

[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. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the evaluation criteria for assessing adhesion in the examples. [Modes for carrying out the invention]

[0009] The following describes a method for forming a chemical conversion film according to one embodiment of the present invention. Furthermore, in numerical ranges described in stages within 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 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 treatment agent) The chemical conversion agent used in this embodiment comprises 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, blended 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. When the source of fluoride ions is added to the chemical treatment agent... The fluorine-containing compound is not particularly limited as long as it can supply fluorine ions (hereinafter referred to as "fluorine-containing compound"), and fluorine ions may be supplied by supply 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, hydrosilicon fluoride, sodium fluoride, sodium hydrogen fluoride, etc.

[0012] Furthermore, compounds containing zirconium and fluorine, such as hexafluorozirconium acid, can supply both zirconium-containing ions and fluorine ions. Additionally, each fluorine-containing compound may be included individually or in combination of two or more. The blending amount of the fluorine-containing compound is not particularly limited, but the free fluorine ion concentration in the chemical conversion treatment agent measured with a fluorine ion meter (for example, IM55G manufactured by Toa Densi Kogyo Co., Ltd.) is usually 15 mg / L or more and 100 mg / L or less. Setting the free fluorine ion concentration within the above range makes the reaction rate between the metal material and the chemical conversion treatment agent suitable. This results in a suitable amount of the formed coating film.

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

[0014] Specific examples of Supply Source A include hexafluorozirconic acid, zirconium nitrate, zirconium oxonitrate, zirconium carbonate, zirconium hydroxide, zirconium oxide, and the like. In addition, when these can take the form of a salt, they may be the salt. Only one type of Supply Source A may be blended, or two or more types may be blended. The concentration of zirconium-containing ions in the chemical conversion treatment agent is not particularly limited, but the concentration of zirconium element in the chemical conversion treatment agent is usually 10 mg / L or more and 300 mg / L or less, preferably 20 mg / L or more and 200 mg / L or less. By setting the concentration of zirconium element in the chemical conversion treatment agent within the above range, the amount of zirconium in the chemical conversion coating can be made effective, and the coating adhesion is improved. If the concentration of zirconium element in the chemical conversion treatment agent exceeds 300 mg / L, the coating adhesion to GI materials tends to decrease.

[0015] (Supply Source B) The chemical conversion treatment agent used in the present embodiment contains source B. Source B is not particularly limited as long as it is a compound capable of supplying aluminum-containing ions (hereinafter referred to as "aluminum-containing ions") when blended into the chemical conversion treatment agent. Therefore, the chemical conversion treatment agent contains aluminum-containing ions. Examples of the aluminum-containing ions include metal ions of aluminum; complex ions containing aluminum; oxide ions of aluminum; and the like.

[0016] Specific examples of source B for aluminum-containing ions include, but are not limited to, aluminum hydroxide, aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum oxide, and the like. Further, when these can take the form of a salt, they may be such salts. Only one type of these sources may be blended, or two or more types may be blended. The concentration of aluminum-containing ions in the chemical conversion treatment agent is not particularly limited, but the aluminu m element concentration in the chemical conversion treatment agent is usually 1 mg / L or more and 2000 mg / L or less. By setting the aluminum element concentration within the above range, the free fluorine ion concentration in the chemical conversion treatment agent can be maintained in an appropriate range.

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

[0018] Specific examples of source C for copper-containing ions include, but are not limited to, copper hydroxide, copper nitrate, copper sulfate, copper carbonate, copper oxide, and the like. Further, when these can take the form of a salt, they may be such salts. Only one type of these sources may be blended, or two or more types may be blended. The concentration of copper-containing ions in the chemical treatment agent is not particularly limited, but the concentration of copper elements in the chemical treatment 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, 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 treatment agent during chemical conversion treatment at room temperature becomes optimal. 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 includes polydiallylamines such as diallylamine polymers; salts of diallylamine polymers such as diallylamine hydrochloride polymers, diallylamine sulfate polymers, and diallylamine acetate polymers. [ka]

[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 polymer D content in the chemical conversion agent is typically between 1 mg / L and 300 mg / L as a solid mass concentration. Keeping the polymer D content within this range improves the corrosion resistance and adhesion of the chemical conversion coating.

[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 ingredients) The chemical treatment agent used in this embodiment may contain other additives, provided they do not hinder the effects of the present invention. Specifically, examples include amino group-containing silane coupling agent E, organic acids, oxidizing agents, sources of metal ions other than sources A, B, and C, metal alkoxides, water-soluble resins other than polymer D or water-dispersible resins, surfactants, pH adjusters, and the like. In addition, these other components may be included individually or in groups of two or more.

[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 coupling agent E is incorporated, the ratio (EC / DC) of the silicon element concentration (EC) derived from 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 coupling agent E refers to the sum of the mass concentrations (mg / L) of each of the above forms of silicon element derived from coupling agent E, and when two or more types of coupling agent E are incorporated into the chemical conversion agent, it refers to the total concentration of silicon elements 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 acid) Examples of organic acids include organic sulfonic acids, aliphatic carboxylic acids, and aromatic carboxylic acids. Examples include, but are not limited to, these. Organic sulfonic acids are organic compounds having at least one sulfo group, such as 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, such as 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, such as benzoic acid and phthalic acid. Organic acids may be included in a single formulation or in a formulation of two or more.

[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 metal ion sources other than sources A, B, and C include, but are not limited to, compounds containing iron, manganese, magnesium, nickel, cobalt, zinc, tungsten, and molybdenum. Only one type of metal ion source other than sources A, B, and C may be included, or two or more types 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. Metal alkoxides containing zirconium are also source A, and metal alkoxides containing aluminum are also source B.

[0030] (Water-soluble resins or water-dispersible resins other than polymer D) Examples of water-soluble 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 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. Nonionic surfactants are not particularly limited, but examples include polyethylene glycol-type nonionic surfactants such as polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene-polyoxypropylene-block polymers; polyhydric alcohol-type nonionic surfactants such as sorbitan fatty acid esters; and amide-type nonionic surfactants such as fatty acid alkylolamides. Cationic surfactants are not particularly limited, but examples 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 salts. Anionic surfactants are not particularly limited, but examples include higher alkyl ether sulfate salts to which ethylene oxide has been added. The HLB value (calculated by the Griffin method) of the above surfactant is not particularly limited, but is preferably between 6 and 18, and more preferably between 10 and 14. The above surfactant may be included in the chemical treatment agent by one type only, or by two or more types. By including the above surfactant in the chemical treatment agent, it becomes possible to perform the chemical treatment and degreasing treatment simultaneously in a single step.

[0032] (pH adjuster) 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 chemical treatment agent) The pH of the chemical treatment agent used in this embodiment is typically 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. Furthermore, 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 of manufacturing chemical treatment agents) The above-mentioned chemical treatment agent can be manufactured 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 film) 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. Methods for contacting the metal material with the chemical conversion treatment agent include, but are 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. Furthermore, the contact time is preferably within the range of 30 seconds to 480 seconds. It is more preferable that the time be between 60 and 300 seconds, but it is not limited to these times.

[0037] (Value of a specific parameter) The chemical treatment agent used in this embodiment satisfies the following formula (1). 900≦t×FF / pH≦4800...Equation (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 treatment agent and is between 15 and 100. The pH is between 3.5 and 6.0. The value of formula (1) is preferably between 1400 and 4000, and more preferably between 1700 and 3500. Having the value of formula (1) within this range allows for a favorable reaction rate between the metal material and the chemical treatment agent during chemical conversion treatment at room temperature. This results in the formation of a chemical conversion film with excellent corrosion resistance and coating adhesion. Furthermore, the value of FF is preferably between 20 and 85, and more preferably between 20 and 70.

[0038] Furthermore, a pretreatment step may be performed before the step of contacting the material with the chemical treatment agent. Examples of pretreatment steps include pickling, degreasing, alkaline cleaning, chromate treatment, phosphate chloride treatment using phosphates such as zinc phosphate and iron phosphate, bismuth substitution plating, iron substitution plating, zirconium treatment, titanium treatment, hafnium treatment, and vanadium treatment. Note that these pretreatment steps may be performed individually or in combination of two or more steps. Examples of combinations of two or more steps include a phosphate chlorination treatment step and a chromate conversion treatment step, a bismuth substitution plating step, an iron substitution plating step, a zirconium conversion treatment step, a titanium conversion treatment step, a hafnium conversion treatment step, or a vanadium conversion treatment step. The zirconium conversion treatment step performed as a pretreatment step may use a conversion treatment agent according to this embodiment, or a different conversion treatment agent may be used. When performing any of the above pretreatment steps, 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. Furthermore, 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. Note that one of these post-treatment steps may be performed, or two or more steps may be performed sequentially in combination. The chemical treatment step performed as a post-treatment step may use a chemical treatment agent according to this embodiment, or a chemical treatment agent different from the one according to this embodiment. When performing the above various 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 the metal material according to this embodiment or on a chemical conversion coating formed by a method for forming a chemical conversion coating on a surface. In this case, after the formation of the chemical conversion coating, a coating formation process may be performed, such as a painting process and a drying process (which may include a baking process and a hardening process, etc.) to dry the paint on the surface of the painted metal material, in order to form the coating. Furthermore, a water washing step may be performed before the painting step, in which the surface of the metal material that has been in contact with the chemical conversion agent according to this embodiment is washed with water. Alternatively, a drying step may be performed to dry the surface of the metal material that has been in contact with the chemical conversion agent, or the surface of the metal material that has undergone the water washing step. In addition, one or more of the above post-treatment steps may be performed after the contact step and before the painting step. Furthermore, when performing the various post-processing steps described above, a water rinsing step may be performed after each post-processing step. When performing multiple post-processing 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.

[0041] The above painting process is performed on the surface of the metal material with the chemical conversion coating using paint. The painting method is not particularly limited, and conventionally known methods such as rolling, electrodeposition (e.g., cationic electrodeposition, anionic electrodeposition, etc.), spray painting, hot spray painting, airless spray painting, electrostatic (powder) coating, roller coating, curtain flow coating, brush painting, bar coating, and fluid immersion method can be applied.

[0042] Examples of the above-mentioned paints include known paints such as oil-based paints, cellulose derivative paints, phenolic resin paints, alkyd resin paints, amino alkyd resin paints, urea resin paints, unsaturated resin paints, vinyl resin paints, acrylic resin paints, epoxy resin paints, polyurethane resin paints, silicone resin paints, fluororesin paints, rust-inhibiting paints, antifouling paints, powder coatings, cationic electrodeposition paints, anionic electrodeposition paints, water-based paints, and solvent-based paints. The painting process may involve one painting using the same or different types of paints, or two or more paintings may be performed.

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

[0044] Known coating methods such as spray coating, electrostatic powder coating, and fluid immersion can be applied using powder coatings. Examples of powder coatings include those containing a polyester resin and a curing agent such as a blocked isocyanate curing agent, a β-hydroxyalkylamide curing agent (see, for example, Japanese Patent Application Publication No. 2011-88083), or triglycidyl isocyanurate. Baking is performed for a certain period of time within a predetermined temperature range. For example, baking can be performed for 20 minutes within a range of 130°C to 250°C.

[0045] Known methods can be applied to coating methods such as spray coating, electrostatic coating, and bar coating using the above-mentioned solvent-based paint. Examples of solvent-based paints include those containing resins such as melamine resin, acrylic resin, urethane resin, and polyester resin, and organic solvents such as thinner. Baking is performed for a certain period of time within a predetermined temperature range. For example, baking can be performed at 130°C for 20 minutes.

[0046] The above drying process is the process of drying and hardening the applied paint. Drying methods for hardening the applied paint include, for example, natural drying, reduced-pressure drying, and convection-type heat drying (for example, Drying methods include natural convection drying, forced convection drying, radiant drying (e.g., near-infrared drying, far-infrared drying), ultraviolet curing, electron beam curing, and vapor curing. These drying methods may be used individually or in combination of two or more.

[0047] The coating obtained by the painting process may be a single layer or multiple layers. In the case of multiple layers, the paints used to form the various coatings, the painting method using the paints, and the drying method for the painted metal material may be the same or different.

[0048] Examples of metallic 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. [Examples]

[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 include cold-rolled mild steel sheets (SPCC: 0.8mm thick) conforming to JIS G3141:2011 standards, alloyed hot-dip galvanized steel sheets (GA: 0.8mm thick) conforming to JIS G3302:2012 standards, hot-dip galvanized steel sheets (SGCC: 0.8mm thick) conforming to JIS G3302:2012 standards, and JIS H4000:2014 standards. Aluminum alloy sheets (A6061: 0.8mm thick) that meet the specifications were cut to the size of 70mm x 150mm and prepared.

[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 compound) D1: Diallylamine hydrochloride copolymer (100% content of formula (i)) D2: Diallylamine hydrochloride / acrylamide copolymer (containing 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, the chemical treatment agents for Examples 1 to 138 and Comparative Examples 1 to 57 were prepared by mixing predetermined amounts of each component with water so that each component reached a predetermined concentration, and then 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 a chemical conversion coating. Specifically, each metal material was immersed in a degreasing agent (FC-E2093; Nippon Parkerizing Co., Ltd.; an alkaline solution prepared by dissolving agent A at a concentration of 13 g / L and agent B at 11 g / L in water and adjusting the pH to 11.5 with CO2 gas) at 43°C for 120 seconds. After that, it was spray-washed with water at 25°C for 30 seconds. Subsequently, the degreased and spray-washed metal materials were immersed in various chemical conversion treatment agents (chemical conversion treatment agents for Examples 1-138 and Comparative Examples 1-57) at the temperatures shown in Table 1 for 180 seconds to form a chemical conversion coating on the surface of the metal material. The surface of the resulting metal materials with the chemical conversion coating was washed with tap water and then deionized water at 25°C. Test pieces for corrosion resistance and adhesion tests were not dried and were subjected to the painting described later. The test specimens for chemical 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 manufactured by the same method 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 followed. The chemical conversion agent described in Example 2 of Patent Document 1 consisted of: hydrofluoric acid: 28 mmol / L, copper nitrate: 0.16 mmol / L (copper element concentration: 10 mg / L), zirconium oxonite: 2.10 mmol / L (zirconium element concentration: 192 mg / L), ammonium nitrate: 300 mmol / L, zinc nitrate: 30 mmol / L, aluminum nitrate: The solution contained 7.4 mmol / L (aluminum element concentration: 197 mg / L) and 50 mg / L of polydiallylamine (average molecular weight: 200,000), and its pH was adjusted to 3.0 using aqueous ammonia. The measured free fluorine concentration was 4 mg / L. 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 by the same method 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 followed. 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 by the same method 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 followed. 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 oxonate: 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 its 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] [Table 1-1]

[0063] [Table 1-2]

[0064] [Table 1-3]

[0065] [Table 1-4]

[0066] <Manufacturing of metal materials with coatings> After applying paint to a chemical conversion coating formed on the surface of various metal materials, the coating was baked to produce metal materials with a coated film. The painting method and baking conditions are detailed below.

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

[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 specimen, and a corrosion cycle test according to VDA test 621-415 was performed for 6 cycles. The width of the coating blister (maximum blister width on one side) from the scratch (cut) area of ​​the test specimen was measured. Corrosion resistance was evaluated according to the following evaluation criteria. <Evaluation Criteria - Cut Section> S: Swelling width on one side is less than 4.0 mm A: The swelling on one side is between 4.0 mm and less than 6.0 mm. B: Swelling width on one side is 6.0 mm or more but less than 8.0 mm C: Swelling width on one side is 8.0 mm or more but less than 10.0 mm D: Swelling 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 specimen, with 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 protruding part of the test specimen was peeled off using commercially available tape (Scotch Tape®; manufactured by Nichiban Co., Ltd.), and the degree of coating film 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: Remaining paint film area is between 95% and less than 100% A: The remaining paint film area is between 85% and 95%. B: The remaining paint film area is between 65% and 85%. C: The remaining paint film area is 35% or more but less than 65%. D: Less than 35% of the coating remains.

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

[0071] <Chemical appearance> The appearance of the chemical conversion coating on the test specimens obtained in each example and comparative example was visually determined. <Evaluation Criteria> S: No inconsistencies in the appearance of the test specimen. D: The appearance of the test specimen is uneven. The results of each evaluation test are shown in Table 2. In all evaluations, a score of C or higher was considered a passing grade.

[0072] [Table 2-1]

[0073] [Table 2-2]

[0074] [Table 2-3]

[0075] [Table 2-4]

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 of zirconium-containing ions A, a source of aluminum-containing ions B, a source of copper-containing ions C, and a water-soluble or water-dispersible polymer or salt thereof D having 90% or more of the structural units represented by the following formula (i) on a molar basis, onto the surface of a metal material, A method for forming a chemical conversion film, 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 the solid content mass concentration of the polymer or its salt D is 1 mg / L or more and 300 mg / L or less, and satisfies the relationship of the following formula (1). 900≦t×FF / pH≦4800...Formula (1) (In formula (1) above, 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.) 【Chemistry 1】

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 silicon element concentration EC to solid content mass concentration DC of the polymer 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.

Images