Chemical conversion coating method

Abstract

Provided is a method for forming a chemical conversion film that can form a film that has excellent corrosion resistance and paint film adhesion under severe conditions in a chemical conversion treatment at room temperature. [Solution] A method for forming a chemical conversion coating includes a step of contacting the surface or surfaces of a metal material with a chemical conversion treatment agent containing 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 a salt thereof D (for example, a diallylamine polymer, a diallylamine hydrochloride polymer, a diallylamine sulfate polymer, a diallylamine acetate polymer, or other diallylamine polymer salt, or a polydiallylamine). The chemical conversion treatment agent has specific ranges for the zirconium element concentration, aluminum element concentration, copper element concentration, and solids mass concentration of the polymer or salt thereof D.

Description

[Technical Field]

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

[0002] Conventionally, metal surface treatment solutions capable of forming chemical conversion coatings with excellent corrosion resistance and good adhesion have been developed. For example, Patent Document 1 discloses a metal surface treatment solution 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 specified water-soluble resin (C). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5643484 Summary of the Invention [Problem to be solved by the invention]

[0004] Painted products such as home appliances and automobiles require resistance to corrosion and rust (corrosion resistance) as well as sufficient adhesion to prevent the coating from peeling off even when deformation occurs due to processing after painting or impact during use. Conventional chemical conversion treatment methods generally involve treatment at temperatures higher than room temperature, and chemical conversion films formed when treated at temperatures near room temperature do not provide sufficient corrosion resistance or adhesion. In particular, when galvanized steel sheets (GI materials) are used as target components, sufficient coating adhesion cannot be obtained. The present invention aims to provide a chemical conversion coating formation method that can form a chemical conversion coating that has excellent corrosion resistance and coating adhesion under severe conditions, even when chemical conversion treatment is performed at room temperature. [Means for solving the problem]

[0005] As a result of extensive research into solving the above-mentioned problems, the inventors of the present invention have discovered a method for forming a chemical conversion coating, which includes a step of contacting the surface or surface of a metal material with a surface treatment agent containing a combination of 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 a salt thereof D, and which has been found to be capable of forming a chemical conversion coating that has excellent corrosion resistance and paint adhesion under severe conditions, even when chemically treated at room temperature, by using a surface treatment agent that satisfies certain parameters. This discovery led to the completion of the present invention.

[0006] The present invention includes the following. [1] A method for forming a chemical conversion coating, comprising a step of contacting a surface or surfaces of a metal material with a chemical conversion treatment agent containing 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 having 90% or more, in terms of moles, of a structural unit represented by the following formula (i): The chemical conversion treatment 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, and a copper element concentration of 1 mg / L or more and 100 mg / L or less, and the polymer or salt thereof D has a solids mass concentration of 1 mg / L or more and 300 mg / L or less, and the chemical conversion treatment agent satisfies the relationship of the following formula (1): 900≦t×FF / pH≦4800...Equation (1) (In the above formula (1), t is the Kelvin temperature (K) and is 283 to 308, FF is the free fluorine ion concentration (mg / L) in the chemical conversion treatment agent and is 15 to 100, and pH is 3. 5 or greater and 6.0 or less.) [ka] [2] The method for forming a chemical conversion coating according to [1], wherein the chemical conversion treatment agent further contains an amino group-containing silane coupling agent E. [3] The method for forming a chemical conversion coating according to [2], wherein the ratio (EC / DC) of the silicon element concentration EC to the solid mass concentration DC of the polymer D in the chemical conversion treatment agent is 0.02 or more and 1 or less. [4] The method for forming a chemical conversion coating according to any one of [1] to [3], wherein the metal material is selected from iron materials, zinc or zinc-based plated materials, aluminum materials, aluminum alloy materials, aluminum-based plated materials, magnesium materials, and magnesium alloy materials. [Effects of the Invention]

[0007] The present invention provides a method for forming a chemical conversion coating that can form a chemical conversion coating that has excellent corrosion resistance and adhesion even under severe 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 paint adhesion even on GI materials, which previously did not have sufficient paint adhesion when chemical conversion treatment was performed at room temperature. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating the evaluation criteria for adhesion evaluation in Examples. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] (chemical conversion treatment agent) The chemical conversion treatment agent used in this embodiment is obtained by blending, in predetermined amounts, 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, which has, on a molar basis, at least 90% of a structural unit represented by formula (i), in an aqueous medium. By using this chemical conversion treatment agent, a chemical conversion coating that exhibits excellent corrosion resistance and adhesion under severe conditions can be formed on or above the surface of a metal material. The chemical conversion treatment agent used in this embodiment may be one in which only source A, source B, source C, and the predetermined polymer or salt thereof D are blended in an aqueous medium, or one in which other components are further blended.

[0011] (source of fluoride ions) Since the chemical conversion treatment agent used in this embodiment contains fluorine ions, a source of fluorine ions may be blended therein. The source of fluorine ions is a source of fluorine ions that, when blended into the chemical conversion treatment agent, There are no particular limitations on the compound as long as it is capable of supplying fluorine ions (hereinafter referred to as "fluorine-containing compound"), and fluorine ions may be supplied by the below-described sources A to C. Examples of fluorine-containing compounds include, but are not limited to, hexafluorozirconic acid, hexafluorotitanic acid, hexafluorohafnic acid, hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, germanium fluoride, potassium fluoride, potassium hydrogen fluoride, iron fluoride, hydrosilicic acid, sodium fluoride, and sodium hydrogen fluoride.

[0012] In addition, compounds containing zirconium and fluorine, such as hexafluorozirconic acid, can supply both zirconium ions and fluorine ions. In addition, various fluorine-containing compounds may be blended singly or in combination of two or more. The 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 (e.g., IM55G manufactured by Toa Denpa Kogyo Co., Ltd.), is usually 15 mg / L or more and 100 mg / L or less. By keeping the free fluorine ion concentration within this range, the reaction rate between the metal material and the chemical conversion treatment agent becomes optimal, and the amount of the coating formed becomes optimal.

[0013] (Source A) The chemical conversion treatment agent used in this embodiment contains a supply source A. There are no particular limitations on supply source A, as long as it is a compound that can supply ions containing zirconium (hereinafter referred to as "zirconium-containing ions") when added to the chemical conversion treatment agent. Therefore, the chemical conversion treatment agent contains zirconium-containing ions. Examples of zirconium-containing ions include metal ions of zirconium, complex ions containing zirconium, and oxide ions of zirconium.

[0014] Specific examples of Source A include hexafluorozirconic acid, zirconium nitrate, zirconium oxonitrate, zirconium carbonate, zirconium hydroxide, and zirconium oxide. When these can be in the form of a salt, the salt may be used. Only one type of 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 zirconium element concentration in the chemical conversion treatment agent is usually 10 mg / L or more and 300 mg / L or less, and preferably 20 mg / L or more and 200 mg / L or less. By setting the zirconium element concentration in the chemical conversion treatment agent within the above range, an effective amount of zirconium can be obtained in the chemical conversion coating, resulting in good paint adhesion.If the zirconium element concentration in the chemical conversion treatment agent exceeds 300 mg / L, paint adhesion to GI materials tends to decrease.

[0015] (Source B) The chemical conversion treatment agent used in this embodiment contains a supply source B. There are no particular limitations on the supply source B, as long as it is a compound that can supply ions containing aluminum (hereinafter referred to as "aluminum-containing ions") when added to the chemical conversion treatment agent. Therefore, the chemical conversion treatment agent contains aluminum-containing ions. Examples of aluminum-containing ions include aluminum metal ions, aluminum-containing complex ions, and aluminum oxide ions.

[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 can take the form of a salt, the salt may be used. Only one of these sources may be blended, or two or more may be blended. The concentration of aluminum-containing ions in the chemical conversion treatment agent is not particularly limited. The aluminum element concentration is usually between 1 mg / L and 2000 mg / L. By keeping the aluminum element concentration within the above range, the free fluorine ion concentration in the chemical conversion treatment agent can be maintained within an appropriate range.

[0017] (Source C) The chemical conversion treatment agent used in this embodiment contains a supply source C. There are no particular limitations on the supply source C, as long as it is a compound that can supply copper-containing ions (hereinafter referred to as "copper-containing ions") when added to the chemical conversion treatment agent. Therefore, the chemical conversion treatment agent contains copper-containing ions. Examples of copper-containing ions include copper metal ions, copper-containing complex ions, and copper oxide ions.

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

[0019] (Water-soluble or water-dispersible polymer or its salt D) The chemical conversion treatment agent used in this embodiment contains a water-soluble or water-dispersible polymer or salt thereof D (hereinafter simply referred to as "polymer D"). Polymer D is a polymer having 90% or more, in terms of moles, of structural units represented by formula (i). Specific examples of polymer D include polydiallylamines such as diallylamine polymers; and 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, and preferably 5,000 or more. The upper limit is not particularly limited, but is usually 1,000,000 or less, and may be 500,000 or less, or may be 100,000 or less. The weight-average molecular weight is measured by GPC (gel permeation column chromatography) and converted into polystyrene. The content of polymer D in the chemical conversion treatment agent is typically 1 mg / L or more and 300 mg / L or less in terms of solid mass concentration. By keeping the content of polymer D within this range, the corrosion resistance and paint film adhesion of the chemical conversion coating are improved.

[0021] (aqueous medium) The chemical conversion 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 by volume of water 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 thereof include ketone-based solvents such as acetone and methyl ethyl ketone; amide-based solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol-based solvents such as methanol, ethanol, and isopropanol; ether-based solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone-based solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone. One or more of these water-miscible organic solvents may be mixed with water.

[0022] (Other ingredients) The chemical conversion treatment agent used in this embodiment may contain other additives as long as they do not impair the effects of the present invention. Specific examples include amino group-containing silane coupling agent E, organic acid, oxidizing agent, metal ion source other than sources A, B, and C, metal alkoxides, water-soluble or water-dispersible resin other than polymer D, surfactant, pH adjuster, etc. These other components may be used alone or in combination 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 be one having a primary amino group, one having a secondary amino group, one having a tertiary amino group, or one having multiple amino groups. Specific 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 conversion treatment agent may be in the form of an unmodified hydrolysate obtained by hydrolyzing the coupling agent E, or in the form of a condensation polymer obtained by condensation polymerizing the hydrolysate, or in the form of a copolymer obtained by copolymerizing the respective hydrolysates (an alternating copolymer, a random copolymer, a block copolymer, a graft copolymer, etc.), or a mixture of multiple forms may be present.

[0024] When coupling agent E is blended, the ratio (EC / DC) of the silicon element concentration (EC) derived from coupling agent E in the chemical conversion treatment agent to the solids 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 means the total mass concentration (mg / L) of each of the above forms of silicon derived from coupling agent E, and when two or more types of coupling agent E are blended in the chemical conversion treatment agent, it means the total concentration of silicon element derived from them. When EC / DC is within the above range, the corrosion resistance and coating adhesion of the chemical conversion coating 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, organic sulfonic acids, which 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 carboxy 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 carboxy group, such as benzoic acid and phthalic acid. The organic acid may be blended either alone or in combination 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, with hydrogen peroxide, nitrates, and nitrites being preferred, but not limited to these. Only one type of oxidizing agent may be blended, or two or more types may be blended.

[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, molybdenum, etc. Only one type of metal ion source other than Sources A, B, and C may be blended, or two or more types may be blended.

[0028] (Metal alkoxides) Examples of metal alkoxides include, but are not limited to, zirconium alkoxides such as zirconium tetrapropoxide, zirconium tetraisopropoxide, zirconium tetranormal propoxide, and zirconium tetranormal butoxide; titanium alkoxides such as titanium methoxide, titanium ethoxide, titanium tetraisopropoxide, titanium tetranormal 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 singly or in combination of two or more.

[0029] Furthermore, the metal alkoxides in the chemical conversion treatment agent may be in the form of an unmodified metal alkoxide, a hydrolyzate obtained by hydrolyzing the metal alkoxides, a condensation polymer obtained by condensation polymerization of the hydrolyzate or the hydrolyzate of an organosilane compound, a copolymer obtained by copolymerization of each hydrolyzate or the hydrolyzate of an organosilane compound (an alternating copolymer, a random copolymer, a block copolymer, a graft copolymer, etc.), or a mixture of a plurality of forms may be present. Zirconium-containing metal alkoxides are also Source A, and aluminum-containing metal alkoxides are also Source B.

[0030] (Water-soluble resin or water-dispersible resin 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, amine resins that do not contain a structural unit represented by formula (i), etc. Only one type of water-soluble or water-dispersible resin other than Polymer D may be blended into the chemical conversion treatment agent, or two or more types may be blended.

[0031] (surfactant) Examples of the surfactant include nonionic surfactants and ionic surfactants such as cationic, anionic or amphoteric surfactants. The nonionic surfactant is not particularly limited, but examples thereof 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. The cationic surfactant is not particularly limited, but examples thereof 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. The anionic surfactant is not particularly limited, but examples thereof include higher alkyl ether sulfate salts to which ethylene oxide is added. The HLB value (calculated by the Griffin method) of the surfactant is not particularly limited, but is preferably from 6 to 18, and more preferably from 10 to 14. The chemical conversion treatment agent may contain only one type of surfactant, or two or more types of surfactants. By including the surfactant in the chemical conversion treatment agent, it becomes possible to carry out chemical conversion treatment and degreasing treatment simultaneously in one step.

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

[0033] (pH of chemical conversion treatment agent) The pH of the chemical conversion treatment 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 means the value measured at 25°C using a pH meter. When a metal material is brought into contact with a chemical conversion treatment agent having a pH within the above range, the pH rises as the metal material dissolves, forming a uniform chemical conversion coating on the surface of the metal material. If the pH is below 3.5, the dissolution reaction of the metal material becomes excessive, which tends to impair the uniformity of the chemical conversion coating. If the pH is above 6.0, the coating components in the chemical conversion treatment agent become unstable, which tends to impair the stability of the chemical conversion treatment agent.

[0034] (Method of manufacturing chemical conversion treatment agent) The chemical conversion treatment agent can be produced by mixing predetermined amounts of at least Source A, Source B, Source C, and a predetermined polymer or salt thereof D as raw materials in an aqueous medium.

[0035] (Method for forming chemical conversion coating) The method for forming a chemical conversion coating on or at the surface of a metal material according to this embodiment includes a step of contacting the above-described chemical conversion treatment agent with or at the surface of the metal material. This results in the formation of a chemical conversion coating on or at the surface of the metal material. The method for contacting the chemical conversion treatment agent with the metal material includes, but is not limited to, conventional contact methods, such as immersion treatment, spray treatment, pouring treatment, or a combination thereof.

[0036] The contact temperature in the contact step is usually in the range of 10°C to 35°C since the contact step is carried out at room temperature. The contact time is preferably in the range of 30 seconds to 480 seconds. It is more preferable that the time is within the range of 60 seconds or more and 300 seconds or less, but the time is not limited to these ranges.

[0037] (value of specific parameter) The chemical conversion 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 equal to or greater than 283 and equal to or less than 308. FF is the free fluorine ion concentration (mg / L) in the chemical conversion treatment agent and is equal to or greater than 15 and equal to or less than 100. pH is equal to or greater than 3.5 and equal to or less than 6.0. The value of formula (1) is preferably 1400 or more and 4000 or less, more preferably 1700 or more and 3500 or less. When the value of formula (1) is within the above range, the reaction rate between the metal material and the chemical conversion treatment agent during chemical conversion treatment at room temperature becomes favorable. This results in the formation of a chemical conversion coating with excellent corrosion resistance and paint film adhesion. The FF value is preferably 20 or more and 85 or less, and more preferably 20 or more and 70 or less.

[0038] Furthermore, a pretreatment step may be carried out before the step of contacting with a chemical conversion treatment agent. Examples of pretreatment steps include an acid pickling step, a degreasing step, an alkali cleaning step, a chromate conversion treatment step, a phosphate conversion treatment step using a phosphate such as zinc phosphate or iron phosphate, a bismuth immersion plating step, an iron immersion plating step, a zirconium conversion treatment step, a titanium conversion treatment step, a hafnium conversion treatment step, and a vanadium conversion treatment step. Note that, of these pretreatment steps, only one step may be carried out, or two or more steps may be combined and carried out sequentially. Examples of combinations of two or more steps include a combination of a phosphate conversion treatment step with 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 carried out as a pretreatment step may use the chemical conversion treatment agent according to the present embodiment, or may use a chemical conversion treatment agent different from the chemical conversion treatment agent according to the present embodiment. When the above-mentioned various pretreatment steps are carried out, a water washing treatment step may be carried out after each of the various pretreatment steps. When multiple various pretreatment steps are carried out, a water washing treatment step may be carried out after each of the various pretreatment steps or after some of the steps. Furthermore, when a water washing treatment step is carried out, a drying step may be carried out thereafter to dry the surface of the metal material.

[0039] Furthermore, a post-treatment step may be carried out after the step of contacting with the chemical conversion treatment agent. Examples of post-treatment steps include an alkali washing step, a water washing step, a chromate conversion treatment step, a zinc phosphate conversion treatment step, a bismuth immersion plating step, an iron immersion plating step, an iron phosphate conversion treatment step, a zirconium conversion treatment step, a titanium conversion treatment step, a hafnium conversion treatment step, and a drying step. Note that, as these post-treatment steps, only one step may be carried out, or two or more steps may be combined and carried out sequentially. The chemical conversion treatment step carried out as the post-treatment step may use the chemical conversion treatment agent according to this embodiment, or may use a chemical conversion treatment agent different from the chemical conversion treatment agent according to this embodiment. When the various post-treatment steps described above are carried out, a water washing treatment step may be carried out after each of the various post-treatment steps. When a plurality of various post-treatment steps are carried out, a water washing treatment step may be carried out after each of the steps or after some of the steps. Furthermore, when a water washing treatment step is carried out, a drying step may be carried out thereafter to dry the surface of the metal material.

[0040] Furthermore, a coated metal material having a chemical conversion coating and a coating can be produced by forming a coating on the surface of a metal material according to the present embodiment or on a chemical conversion coating formed by the 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 such as a painting step and a drying step (which may include a baking step, a curing step, etc.) for drying the paint on the surface of the coated metal material to form a coating can be carried out. Before the painting step, a water-washing step may be carried out in which the surface of the metal material that has been contacted with the chemical conversion treatment agent according to this embodiment is washed with water. A drying step may also be carried out in which the surface of the metal material that has been contacted with the chemical conversion treatment agent or the surface of the metal material that has been subjected to the water-washing step is dried. Furthermore, after the contacting step and before the painting step, one or more of the above post-treatment steps may be carried out. When the above-mentioned various post-treatment steps are performed, a water-washing treatment step may be performed after each of the various post-treatment steps. When a plurality of various post-treatment steps are performed, a water-washing treatment step may be performed after each of the steps or after some of the steps. Furthermore, when a water-washing treatment step is performed, a drying step for drying the surface of the metal material may be performed thereafter.

[0041] The coating process is carried out on the surface of the metal material with the chemical conversion coating using a paint. The coating method is not particularly limited, and conventionally known methods such as rolling 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, and fluidized bed coating can be applied.

[0042] Examples of the paint include known paints such as oil-based paints, cellulose derivative paints, phenolic resin paints, alkyd resin paints, aminoalkyd 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-preventive paints, antifouling paints, powder paints, cationic electrodeposition paints, anionic electrodeposition paints, water-based paints, solvent-based paints, etc. In the painting process, one coating may be performed or two or more coatings may be performed using the same or different paints.

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

[0044] Known methods can be used for applying powder coatings, such as spray coating, electrostatic powder coating, and fluidized bed dipping. Examples of powder coatings include those containing polyester resin and, as a curing agent, a blocked isocyanate curing agent, a β-hydroxyalkylamide curing agent (see, for example, JP 2011-88083 A), or triglycidyl isocyanurate. Baking is performed for a certain period of time within a predetermined temperature range. For example, baking can be performed within a temperature range of 130°C to 250°C for 20 minutes.

[0045] Known methods can be used for applying the solvent-based paint, such as spray painting, electrostatic painting, and bar coating. Examples of solvent-based paints 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, baking can be performed at 130°C for 20 minutes.

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

[0047] The coating film obtained by the coating process may be a single layer or multiple layers. In the case of multiple layers, the paints for forming the various coating films, the coating method using the paints, the method for drying the coated metal material, etc. may be the same or different.

[0048] Examples of metal materials include iron (e.g., cold-rolled steel plate, hot-rolled steel plate, high-tensile steel plate, tool steel, alloy tool steel, spheroidized graphite cast iron, gray cast iron, etc.); plated materials, such as zinc and zinc-based plated materials (e.g., electrogalvanized, hot-dip galvanized, hot-dip zinc-aluminum plated, hot-dip zinc-aluminum-magnesium plated, alloyed hot-dip galvanized, electrogalvanized, 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 plated materials; and magnesium and magnesium alloy materials (e.g., AZ91, AZ61, AZ31, etc.).

[0049] The chemical conversion coating formed by the method for forming a chemical conversion coating according to this embodiment has a mass of zirconium contained in the chemical conversion coating of 5 mg / m per unit area. 2 It is preferable that the concentration is 10 mg / m or more. 2 More preferably, it is 20 mg / m or more. 2 The upper limit is not particularly limited, but is preferably 800 mg / m 2 It is preferable that the mass of zirconium in the chemical conversion coating is not more than 100%. The mass of zirconium in the chemical conversion coating can be measured, for example, by using an X-ray fluorescence analyzer.

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

[0051] A coated metal material having a chemical conversion coating and a coating can be produced by forming a coating on the surface of a metal material according to this embodiment or on a chemical conversion coating formed by the method for forming a chemical conversion coating on a surface. The coated metal material may have a coating on the surface of a metal material having a chemical conversion coating according to this embodiment, or may have a coating on the surface of one or more of the above-mentioned various coatings (e.g., chromate chemical conversion coating, phosphate conversion coating, bismuth immersion plating coating, iron immersion plating coating, vanadium chemical conversion coating, etc.) further formed on the chemical conversion coating. The coating may consist of a single layer or two or more layers. The thickness of the coating is not particularly limited and can be appropriately determined depending on the intended use of the coated metal material. The intended use of the coated metal material is not particularly limited, and it can be used for a variety of purposes, such as automobile bodies and automobile parts. [Example]

[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 to the following examples. <Metal materials> The metal materials are cold-rolled mild steel plate (SPCC: thickness 0.8 mm) conforming to the JIS G3141:2011 standard, alloyed hot-dip galvanized steel plate (GA: thickness 0.8 mm) conforming to the JIS G3302:2012 standard, hot-dip galvanized steel plate (SGCC: thickness 0.8 mm) conforming to the JIS G3302:2012 standard, and galvanized steel plate (SGCC: thickness 0.8 mm) conforming to the JIS H4000:2014 standard. Aluminum alloy plates (A6061: thickness 0.8 mm) suitable for the test were prepared by cutting them into sizes of 70 mm length x 150 mm width.

[0053] The components used in preparing the chemical conversion treatment agent are shown below. (Source A) A1: Hexafluorozirconate (Source B) B1: Aluminum nitrate nonahydrate B2: Aluminum sulfate (Source C) C1:Copper(II) nitrate trihydrate C2:Copper(II) sulfate pentahydrate (polymer compound) D1: Diallylamine hydrochloride copolymer (formula (i) content: 100%) D2: Diallylamine hydrochloride-acrylamide copolymer (formula (i) content: 90%) 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 conversion treatment agent> As shown in Table 1, the chemical conversion treatment agents of Examples 1 to 138 and Comparative Examples 1 to 57 were prepared by mixing a predetermined amount of each component with water so that each component had a predetermined concentration, and then adjusting the pH and free fluorine concentration to the predetermined values ​​with sodium hydroxide and sodium hydrogen fluoride.

[0055] <Manufacturing metal materials with chemical conversion coatings> Various metal materials were treated under the chemical conversion treatment conditions shown in Table 1 to produce metal materials with chemical conversion coatings. Specifically, the various metal materials were immersed in a degreasing agent (FC-E2093; Nihon Parkerizing Co., Ltd.; an alkaline solution prepared by dissolving agent A in water to a concentration of 13 g / L and agent B in water to a concentration of 11 g / L and adjusting the pH to 11.5 with CO2 gas) at 43°C for 120 seconds. The metal materials were then spray-washed at 25°C for 30 seconds. The degreased and spray-washed metal materials were then immersed in various chemical conversion treatment agents (chemical conversion treatment agents of Examples 1 to 138 and Comparative Examples 1 to 57) at the temperatures shown in Table 1 for 180 seconds to form chemical conversion coatings on the surfaces of the metal materials. The surfaces of the resulting metal materials with chemical conversion coatings were washed with tap water and then deionized water at 25°C. The test specimens for the corrosion resistance test and adhesion test were not dried and were subjected to the coating process described below. The test pieces for evaluating the appearance of the chemical conversion film were dried at 40°C for 10 minutes.

[0056] (Comparative Example 58) Metal materials having a chemical conversion coating according to Comparative Example 58 were produced in the same manner as described above, except that the chemical conversion treatment agent described in Example 2 of Patent Document 1 was used and the treatment was carried out under the chemical conversion treatment conditions described in Example 2 of Patent Document 1 (various metal materials were immersed at 50°C for 120 seconds). The chemical conversion treatment agent described in Example 2 of Patent Document 1 contained 28 mmol / L hydrofluoric acid, 0.16 mmol / L copper nitrate (elemental copper concentration: 10 mg / L), 2.10 mmol / L zirconium oxonitrate (elemental zirconium concentration: 192 mg / L), 300 mmol / L ammonium nitrate, 30 mmol / L zinc nitrate, and 10 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 the 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) Metal materials having chemical conversion coatings according to Comparative Example 59 were produced using the same method as described above, except that the chemical conversion treatment agent described in Example 4 of Patent Document 1 was used and the chemical conversion treatment conditions (various metal materials were immersed at 40°C for 60 seconds) described in Example 4 of Patent Document 1 were used. The chemical conversion treatment agent described in Example 4 of Patent Document 1 contained 300.7 mmol / L hydrofluoric acid, 1.58 mmol / L copper nitrate (elemental copper concentration: 100 mg / L), 0.55 mmol / L hexafluorozirconic acid (elemental zirconium concentration: 50 mg / L), 60 mmol / L ammonium nitrate, 15.3 mmol / L zinc sulfate, 74 mmol / L aluminum nitrate (elemental aluminum concentration: 1997 mg / L), and 150 mg / L polydiallylamine (average molecular weight: 40,000), and the pH was adjusted to 4.0 using aqueous ammonia. The measured free fluorine concentration was 68 mg / L. In addition, the value of equation (1) was 5321.

[0058] (Comparative Example 60) Metal materials having chemical conversion coatings according to Comparative Example 60 were produced in the same manner as described above, except that the chemical conversion treatment agent described in Example 7 of Patent Document 1 was used and the treatment was carried out under the chemical conversion treatment conditions described in Example 7 of Patent Document 1 (various metal materials were immersed at 45°C for 90 seconds). The chemical conversion treatment agent described in Example 7 of Patent Document 1 contained 81.5 mmol / L of acid ammonium fluoride, 0.79 mmol / L of copper sulfate (elemental copper concentration: 50 mg / L), 2.19 mmol / L of zirconium oxonitrate (elemental zirconium concentration: 200 mg / L), 100 mmol / L of ammonium nitrate, 15.2 mmol / L of zinc sulfate, 74 mmol / L of aluminum nitrate (elemental aluminum concentration: 1997 mg / L), 500 mg / L of polydiallylamine (average molecular weight: 20,000), and 50 mg / L of hydroxyethylidene diphosphonic acid, and the pH was adjusted to 4.0 using aqueous ammonia. The measured free fluorine concentration was 2 mg / L, and the value of formula (1) was 159.

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

[0060] (Comparative Example 62) A chemical conversion treatment was carried out in the same manner as in Comparative Example 59, except that the chemical conversion treatment was carried out by immersion for 180 seconds at 25°C, to produce a metal material having a chemical conversion coating according to Comparative Example 62. 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 carrying out chemical conversion treatment in the same manner as in Comparative Example 60, except that the chemical conversion treatment was carried out by 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 coating films> The chemical conversion coatings formed on the surfaces of various metal materials were painted and then baked to produce metal materials with coating films. Details of the coating method and baking conditions are shown below.

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

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

[0069] <Adhesion test> In a DuPont impact test based on JIS K 5600-5-3, a weight was dropped onto the center of the coating surface of each test piece, with a height of 500 mm, a weight mass of 1000 g, a spherical radius of the impact point of 6.35 mm, and a receiving hole diameter of 9.52 mm. After the weight was dropped, tape peeling was performed on the convex portion of the test piece using commercially available tape (Cellotape®; 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 remains S: The remaining area of ​​the coating is 95% or more but less than 100% A: The remaining paint film area is 85% or more but less than 95% B: The remaining paint film area is 65% or more but less than 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 conversion coating agents> The chemical conversion treatment agents of each Example and Comparative Example were visually evaluated for liquid stability 24 hours after preparation. <Evaluation criteria> S: No precipitates D: Precipitates present

[0071] <Chemical appearance> The appearance of the conversion coating on the test pieces having the conversion coating obtained in each of the Examples and Comparative Examples was judged visually. <Evaluation criteria> S: No unevenness in the appearance of the test piece D: The test piece has uneven appearance The results of each evaluation test are shown in Table 2. In all evaluations, a grade 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 coating, comprising a step of contacting a surface or surfaces of a metal material with a chemical conversion treatment agent containing 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 having 90% or more, in terms of moles, of a structural unit represented by the following formula (i): the chemical conversion treatment 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, and a copper element concentration of 1 mg / L or more and 100 mg / L or less, and the polymer or salt thereof D has a solids mass concentration of 1 mg / L or more and 300 mg / L or less, and the chemical conversion treatment agent satisfies the relationship of the following formula (1): 900≦t×FF / pH≦4800...Formula (1) (In the formula (1), t is the Kelvin temperature (K) and is 283 to 308, FF is the free fluorine ion concentration (mg / L) in the chemical conversion treatment agent and is 15 to 100, and pH is 3.5 to 6.0.) 【Chemical 1】

2. The method for forming a chemical conversion coating according to claim 1 , wherein the chemical conversion treatment agent further comprises an amino group-containing silane coupling agent E.

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

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

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