TWI911605B - Method for manufacturing metallic materials with chemical conversion coating - Google Patents

Abstract

The purpose of this invention is to provide a method for manufacturing a metallic material with a chemical conversion coating, wherein the formed chemical conversion coating exhibits excellent corrosion resistance as evaluated by methods such as the appearance after chemical conversion treatment, post-coating exposure test, or VDA621-415 method, and can be used over a wide temperature range.

A method for manufacturing a metallic material with a chemical conversion coating, comprising forming a chemical conversion coating on or above the surface of the metallic material, including the following steps: Step I, contacting the metallic material with a chemical conversion treatment agent composed of: a fluorine ion supply source; a zirconium ion supply source A; an aluminum ion supply source B; and a concentration of 0.0001 g/L or more and 1.000 g/L. The following are water-soluble or water-dispersible polymers or their salts C having structural units expressed by formula (i) with a molar content of 90% or more; and step II involves bringing the metal material that has been in contact with the aforementioned chemical conversion treatment agent into contact at least once with an aqueous solution having a pH of 4.0 or higher and a pH of 12.0 or lower; the value obtained by subtracting the value from formula (2) from the value from formula (1) is 0.2 or higher.

(Ac+Bc)×(pH-2.7) ⁸ ‥‥Formula (1)

(D/0.18) ³ ×(t/1.5) ⁵ …Equation (2)

Description

Method for manufacturing metallic materials with chemical conversion coatings

This invention relates to a method for manufacturing a metal material having a chemical conversion coating formed on or on the surface of a metal material.

A treatment liquid for metal surface treatment that can achieve excellent corrosion resistance and good adhesion has been developed in the past. For example, Patent 1 discloses a composition for surface treatment of aluminum, aluminum alloys, magnesium or magnesium alloys, comprising: compound A, which contains at least one metal element selected from Hf(IV), Ti(IV) and Zr(IV); a fluorine-containing compound, the amount of which is sufficient to present fluorine in the composition at a molar concentration at least five times the total molar concentration of the metal contained in compound A; metal ion B, which is selected from at least one of the alkaline earth metal groups; metal ion C, which is selected from at least one of Al, Zn, Mg, Mn and Cu; and nitrate ions.

[Previous Art Documents] [Patent Documents] [Patent Document 1] International Publication No. 03/074761.

[Problem Solved by the Invention] However, not only adhesion and corrosion resistance, but also surface treatment is crucial as a measure of finish. Regarding finish, between the initial contact step with the chemical conversion agent and the next step, excessive liquid adhesion or prolonged adhesion time of the chemical conversion agent can affect the uniformity of appearance or corrosion resistance. Therefore, it is necessary to specify optimal admixture conditions, liquid adhesion amount, and adhesion time of the chemical conversion agent to achieve sufficiently good performance. Furthermore, in corrosion resistance testing, in recent years, more emphasis has been placed on exposure tests and corrosion tests that closely resemble actual environmental conditions compared to general methods such as the salt spray test (SST) and the JASO-M609 method. Moreover, from the perspective of reducing environmental impact, the reduction of chemical conversion treatment temperatures has also become important in recent years. The purpose of this invention is to provide a method for manufacturing a metal material with a chemical conversion coating, which, after chemical conversion treatment, exhibits excellent appearance and corrosion resistance as evaluated by exposure tests or the VDA621-415 method after coating, and can be used over a wide temperature range.

[Technical Means for Solving the Problem] The inventors have repeatedly and diligently researched and discovered a method for manufacturing a metal material with a chemical conversion coating, comprising the following steps: contacting the metal material with a chemical conversion treatment agent composed of a fluorine ion supply source, a zirconium ion supply source A, an aluminum ion supply source B, a specific water-soluble or water-dispersible polymer or its salt C; and contacting the aforementioned metal material with an aqueous solution of pH 4-12 at least once. By carrying out this method for manufacturing a metal material with a chemical conversion coating under conditions that meet specific parameters, it is possible to produce a chemical conversion coating with excellent corrosion resistance and appearance after chemical conversion treatment, thus completing this invention.

The present invention comprises the following: [1] A method for manufacturing a metal material having a chemical conversion coating, wherein a chemical conversion coating is formed on or above the surface of the metal material, comprising the following steps: Step I, wherein the metal material is brought into contact with a chemical conversion treatment agent composed of the following: a source of fluorine ions; a source of zirconium ions A; a source of aluminum ions B; and a water-soluble or water-dispersible polymer or its salt C having structural units represented by the following formula (i) with a molar conversion of more than 90%; and Step II, wherein the metal material that has been in contact with the aforementioned chemical conversion treatment agent is brought into contact at least once with an aqueous solution with a pH of more than 4.0 and less than 12.0; The value obtained by subtracting the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value ^from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value ^from the value from ^the value from the value from the value of ... Wherein, in the aforementioned formula (1), Ac is the concentration of zirconium element from the aforementioned supply source A in the aforementioned chemical conversion treatment agent, which is 2 g/L or less; Bc is the concentration of aluminum element from the aforementioned supply source B in the aforementioned chemical conversion treatment agent, which is 2 g/L or less; the ratio of Bc to Ac, i.e., Bc/Ac, is 0.03 or more and 10.0 or less; pH is the pH value of the aforementioned chemical conversion treatment agent, which is 3.2 or more and 6.0 or less; In the aforementioned formula (2), D is the amount of liquid adhering to the aforementioned chemical conversion treatment agent on the surface of the aforementioned metal material between steps I and II, which is more than 0 L/m ² and less than 0.5 L/m ² ; t is the time from the completion of step I to the start of step II, which is more than 0.01 minutes and less than 3.00 minutes. [2] The method for manufacturing a metal material with a chemical conversion coating as described in [1] further includes the following steps before step I: Step III, contact with an alkaline solution with a pH of 8.0 or higher and less than 13.0; and Step IV, contact with an aqueous solution with a pH of 7.0 or higher and less than 12.0. [3] The method for manufacturing a metal material with a chemical conversion coating as described in [1] or [2], wherein the metal material is at least one of iron, zinc or zinc-based plating, aluminum, aluminum alloy, aluminum-based plating, magnesium, and magnesium alloy.

[Effects of the Invention] This invention provides a method for manufacturing a metal material with a chemical conversion coating formed on or on the surface of a metal material. The metal material, after chemical conversion treatment, exhibits excellent appearance and corrosion resistance as evaluated by exposure tests or VDA621-415 method after coating, and can be used in a wide temperature range.

In this specification, the range of values indicated by "~" refers to the range including the values before and after "~" as the lower and upper limits, and "A~B" means the range above A and below B. The following describes a method for manufacturing a metal material with a chemical conversion coating, according to one embodiment of the present invention.

(Chemical Conversion Treatment Agent) The chemical conversion treatment agent used in this embodiment is composed of a fluorine ion source, a zirconium ion source A, an aluminum ion source B, and a water-soluble or water-dispersible polymer or its salt C having a molar content of more than 90% of the structural unit represented by formula (i) in a specific amount, mixed into an aqueous medium. Using this chemical conversion treatment agent, a chemical conversion coating with excellent corrosion resistance and coating appearance can be formed on a metal material. In addition, the chemical conversion treatment agent used in this embodiment may be composed of only a fluoride ion supply source, supply source A, supply source B and a specific polymer or its salt C added to an aqueous medium, or it may be composed of other components added.

(Fluoride Ion Supply Source) The chemical conversion treatment agent used in this embodiment is mixed with a fluoride ion supply source. There are no particular limitations on the fluoride ion supply source, as long as it is a compound (hereinafter referred to as "fluorine-containing compound") capable of supplying fluoride ions when mixed into the chemical conversion treatment agent. Examples of fluorine-containing compounds include hexafluorozirconic acid, hexafluorotitanium acid, hexafluoroganic acid, hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, germanium fluoride, potassium fluoride, potassium hydrogen fluoride, iron fluoride, hydrofluorosilicic acid, sodium fluoride, sodium hydrogen fluoride, etc., but it is not limited to these. Furthermore, compounds containing both zirconia and fluorine, such as hexafluorozirconic acid, can supply both zirconia ions and fluoride ions. Furthermore, one or more fluorinated compounds may be added. There are no particular restrictions on the amount of fluorinated compound added, but it should not affect the degree of chemical conversion coating formation. Specifically, it is preferable to add fluorine ions until the concentration is 4 to 8 times the molar concentration of zirconium and 2 to 4 times the molar concentration of aluminum in the chemical conversion agent. Adding fluorinated compounds within this range ensures an appropriate concentration of free fluorine ions during treatment, and also improves the reaction rate between the metal material and the chemical conversion agent. This results in a better amount of coating formed.

(Source A) The chemical conversion treatment agent used in this embodiment contains source A. Source A is not particularly limited as long as it is a compound capable of supplying zirconium-containing ions (hereinafter referred to as "zirconia-containing ions") when incorporated into the chemical conversion treatment agent. Therefore, the chemical conversion treatment agent used in this embodiment contains zirconium-containing ions. Examples of zirconium-containing ions include zirconium metal ions, zirconium zirconia ions, and zirconium oxide ions. Specific examples of source A containing zirconium ions include hexafluorozirconic acid, zirconium nitrate, zirconium nitrate oxynitrate, zirconium carbonate, zirconium hydroxide, and zirconium oxide. Furthermore, if these compounds can exist in the form of salts, they can also be used as salts. These sources can be mixed with only one of them, or with two or more.

There is no particular limitation on the zirconium ion concentration in the chemical conversion treatment agent. However, the zirconium concentration Ac from source A in the chemical conversion treatment agent is typically 0.02 g/L or higher, preferably 0.05 g/L or higher; and typically 2 g/L or lower, preferably 1.5 g/L or lower. When two or more sources are combined into the chemical conversion treatment agent, this refers to the total concentration of zirconium contained in these sources. Setting the zirconium concentration Ac within the above range ensures that the Zr in the chemical conversion coating is of an effective amount.

(Source B) The chemical conversion treatment agent used in this embodiment contains source B. Source B is not particularly limited as long as it is a compound capable of supplying aluminum ions (hereinafter referred to as "aluminum ions") when incorporated into the chemical conversion treatment agent. Therefore, the chemical conversion treatment agent used in this embodiment contains aluminum ions. Examples of aluminum ions include aluminum metal ions, aluminum oxide ions, and aluminum oxide ions. Specific examples of source B containing aluminum ions include aluminum hydroxide, aluminum nitrate, aluminum sulfate, aluminum carbonate, and aluminum oxide, but it is not limited to these. Furthermore, if these compounds can exist in the form of salts, they can also be used as salts. These sources can be mixed with only one of them, or with two or more.

There is no particular limitation on the aluminum ion concentration in the chemical conversion treatment agent. However, the aluminum element concentration Bc from source B in the chemical conversion treatment agent is typically 0.02 g/L or higher, preferably 0.05 g/L or higher; and typically 2 g/L or lower, preferably 1.5 g/L or lower. When two or more sources B are added to the chemical conversion treatment agent, it refers to the total concentration of aluminum element from these sources B. Setting the aluminum element concentration Bc within the above range allows for a preferred concentration of free fluoride ions in the chemical conversion treatment agent.

(Ratio of Source A to Source B) The ratio of aluminum concentration Bc from source B to zirconium concentration Ac from source A in the chemical conversion treatment agent (Bc/Ac) is typically above 0.03 and typically below 10.0.

(Water-soluble or water-dispersible polymer or its salt C) The chemical conversion treatment agent used in this embodiment contains a water-soluble or water-dispersible polymer or its salt C (hereinafter referred to as "polymer C"). There are no particular limitations on polymer C as long as it is a polymer having more than 90% of the structural unit represented by the above formula (i) in molar conversion. Specifically, examples of polymer C include diallylamine polymers; polydiallylamines such as diallylamine hydrochloride polymers, diallylamine sulfate polymers, diallylamine acetate polymers, and salts of diallylamine polymers.

The degree of polymerization of polymer C is not particularly limited, but the weight-average molecular weight is typically 1000 or higher, preferably 5000 or higher. Furthermore, the weight-average molecular weight is determined using GPC (gel osmosis chromatography) and converted to polystyrene values. The content (admixture amount) of polymer C in the chemical conversion treatment agent, in terms of solid content mass concentration, is typically 0.0001 g/L or higher, preferably 0.001 g/L or higher, more preferably 0.005 g/L or higher; and typically 1.000 g/L or lower, preferably (0.16×Ac+0.23) g/L or lower. Setting the polymer C content within the above range can improve the adhesion and corrosion resistance of the chemical conversion coating.

(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 water-mixed organic solvents (containing more than 50% water by volume of the aqueous medium). The water-mixed organic solvent is not particularly limited as long as it is mixed 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-mixable organic solvents may be mixed with water, or two or more may be mixed with water.

(Other Ingredients) Other additives may be incorporated into the chemical conversion treatment agents used in this embodiment, to the extent that they do not impair the effectiveness of the invention. Specifically, examples include organic acids, oxidants, metal ion sources other than sources A and B, organosilicon compounds, metal alkoxides, water-soluble or water-dispersible resins other than polymer C, surfactants, pH adjusters, etc. Only one of these other ingredients may be incorporated, or two or more may be incorporated.

(Organic Acids) The organic acids that the chemical conversion treatment agents used in this embodiment may contain, for example, organic sulfonic acids, organic phosphonic acids, organic phosphoric acids, aliphatic carboxylic acids, and aromatic carboxylic acids, specifically methanesulfonic acid, ethanesulfonic acid, lactic acid, oxalic acid, citric acid, etc., but are not limited to these. It may contain only one type of organic acid, or it may contain two or more types.

(Oxidizing agent) An oxidizing agent that can be incorporated into the chemical conversion treatment agent used in this embodiment may include, for example, hydrogen peroxide, nitrate, nitrite, permanganate, chlorate, persulfate, nitro-containing compounds, hypochlorous acid, organic peroxides, and bromates, with hydrogen peroxide, nitrate, and nitrite being preferred, but not limited to these. Only one oxidizing agent may be incorporated, or two or more may be incorporated. In addition, it may or may not contain sulfate ions.

(Metal ion supply sources other than supply sources A and B) Metal ion supply sources other than supply sources A and B that can be incorporated into the chemical conversion treatment agent used in this embodiment may include, but are not limited to, compounds containing copper, iron, manganese, magnesium, nickel, cobalt, zinc, tungsten, etc. Only one of the metal ion supply sources other than supply sources A and B may be incorporated, or two or more may be incorporated.

(Organosyl silane compounds) Organosyl silane compounds that can be incorporated into the chemical conversion treatment agent used in this embodiment, for example, are aminosilane compounds, epoxysilane compounds, and alkoxysilane compounds. 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- Aminopropyl diethylethoxysilane, N-2(aminoethyl)-3-aminopropylethyldiethoxysilane, 3-aminopropyl dimethylmethoxysilane, 3-aminopropyl methyldimethoxysilane, 3-aminopropyl diethylethoxysilane, 3-aminopropyl ethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl methyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyl dimethylmethoxysilane, 3-glycidoxypropyl ethyldiethoxysilane, 3-glycidoxypropyl diethylethoxysilane, 3-glycidoxypropyl triethoxysilane, etc., but not limited to these. In addition, the organosilicon compounds in the chemical conversion treatment agent can be in their original form, in the form of hydrolysates formed by the hydrolysis of organosilicon compounds, in the form of condensed polymers formed by the condensation polymerization of the hydrolysates, in the form of copolymers (alternating copolymers, random copolymers, block copolymers, branch copolymers, etc.) formed by the copolymerization of the individual hydrolysates, or in a mixed plurality of forms.

(Metal alkoxides) Metal alkoxides that can be incorporated into the chemical conversion treatment agent used in this embodiment may include, but are not limited to, tetrazirconium propoxide, tetrazirconium isopropoxide, tetrazirconium n-propoxide, tetrabutyl zirconate, titanium methanol, titanium ethoxide, isobutyl titanium tartrate, tetrabutyl titanium tartrate, tetrabutyl titanium tartrate dimer, tetra-2-ethylhexyl tannic acid ester, triisopropoxyvanadium (V), butanolvanadium, triethoxyvanadium (V), aluminum isopropoxide, and aluminum tributoxide. One metal alkoxide may be incorporated alone, or two or more may be incorporated. Furthermore, the metal alkoxides in the chemical conversion treatment agent can be in their original form, in the form of hydrolysates formed by the hydrolysis of metal alkoxides, in the form of condensation polymers formed by the condensation polymerization of the hydrolysates or hydrolysates of organosilicon compounds, or in the form of copolymers (alternating copolymers, random copolymers, block copolymers, branch copolymers, etc.) formed by the copolymerization of individual hydrolysates or hydrolysates of organosilicon compounds, and can also be in mixed multiple forms. Zirconium-containing metal alkoxides can also be used as supply source A, and aluminum-containing metal alkoxides can also be used as supply source B.

(Water-soluble or water-dispersible resins other than polymer C) These water-soluble or water-dispersible resins, other than polymer C, that can be incorporated into the chemical conversion treatment agent used in this embodiment may include, but are not limited to, poly(meth)acrylate resins, polyurethane resins, acrylic resins, epoxy resins, phenolic resins, and amino resins that do not contain the structural unit represented by formula (i). One or more water-soluble or water-dispersible resins other than polymer C may be incorporated alone or in combination.

(Surfactant) A surfactant that can be incorporated into the chemical conversion treatment agent used in this embodiment, such as nonionic surfactants, cationic, anionic, or amphoteric surfactants, etc. There are no particular limitations on nonionic surfactants, but examples include polyethylene glycol-type nonionic surfactants such as polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene dehydrated sorbitan fatty acid esters, and polyoxyethylene-polyoxypropylene-block polymers; polyol-type nonionic surfactants such as dehydrated sorbitan fatty acid esters; and amide-type nonionic surfactants such as fatty acid alkanolamides. There are no particular limitations on cationic surfactants, and examples include amine salt cationic surfactants such as higher alkylamine salts and polyoxyethylene higher alkylamines; and quaternary ammonium salt cationic surfactants such as alkyl trimethyl ammonium salts. There are no particular limitations on anionic surfactants, and examples include higher alkyl ether sulfate salts with ethylene oxide addition. Furthermore, there are no particular limitations on the HLB value (calculated using the Griffin method) of the above surfactants, but it is preferably 6 or higher and 18 or lower, more preferably 10 or higher and 14 or lower. The above surfactants can be added alone to the chemical conversion treatment agent used in this embodiment, or two or more can be added. By including the above-mentioned surfactants in the chemical conversion treatment agent, chemical conversion treatment and degreasing treatment can be carried out simultaneously in one step.

(pH value of the chemical conversion treatment agent) The pH value of the chemical conversion treatment agent used in this embodiment is generally in the acidic to neutral range, specifically, in the range of 3.2 to 6.0, preferably in the range of 3.4 to 6.0, and particularly preferably in the range of 4.1 to 5.1. Herein, the pH value in this specification refers to the value measured using a pH meter at 40°C. The pH value of chemical conversion treatment agents can be adjusted using acidic components such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, and organic acids; and alkaline components such as lithium hydroxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, barium hydroxide, alkali metal salts, amines, ammonium salts, and amines, but is not limited to these components. Furthermore, one or more pH adjusters can be used.

(Manufacturing method of chemical conversion treatment agent) The above-mentioned chemical conversion treatment agent can be manufactured by using a fluoride ion supply source, supply source A, supply source B and a specific polymer or its salt C as raw materials, and mixing them into an aqueous medium in a specific amount.

(Method for Forming a Chemical Conversion Coating) The present embodiment of the method for manufacturing a metal material having a chemical conversion coating formed on or on the surface of a metal material includes step I, which involves contacting the aforementioned chemical conversion treatment agent with the surface of the metal material. This allows a chemical conversion coating to be formed on or on the surface of the metal material. The method for contacting the chemical conversion treatment agent with the metal material may include conventional contact methods such as impregnation, spraying, or casting, or combinations thereof, but is not limited to these.

The contact temperature in the above contact steps is preferably in the range of 10°C to 60°C, and more preferably in the range of 20°C to 50°C. Furthermore, in this embodiment, the range of 10°C to 25°C is defined as "low temperature," and the range of 25°C to 50°C is defined as "high temperature." Also, the contact time is preferably in the range of 30 seconds to 300 seconds, and more preferably in the range of 60 seconds to 180 seconds, but is not limited to these durations.

In the manufacturing method of the chemically converted metal material of this embodiment, after step I, which involves contacting the metal material with the chemical conversion treatment agent, a further step II is included: contacting the metal material that has been in contact with the aforementioned chemical conversion treatment agent with an aqueous solution having a pH value of 4.0 or higher and 12.0 or lower. The contact with the aqueous solution in step II is carried out by, for example, immersion treatment or spray treatment, but is not limited to these methods. The pH value of the aqueous solution in step II is in the range of 4.0 to 12.0, preferably in the range of 5.0 to 10.0, and particularly preferably in the range of 6.5 to 9.0. The aqueous solution used in Contact Step II is not particularly restricted as long as it is within the pH range mentioned above; examples include tap water, deionized water, and sodium hydroxide solution. The "contact" step in Contact Process II only needs to be performed at least once, and can be performed multiple times. Furthermore, a drying step for the surface of the metal material can be performed after Contact Step II.

(Liquid Adhesion Amount D) In the manufacturing method of the metal material with chemical conversion coating of this embodiment, the liquid adhesion amount D refers to the amount of liquid chemical conversion treatment agent adhering to the surface of the metal material between steps I and II. When the contact method in step I is immersion, it refers to the amount of chemical conversion treatment agent adhering per unit area on the surface of the metal material at the point when the metal material is lifted from the chemical conversion treatment bath and removed from the liquid surface. Furthermore, when the contact method in step I is spraying or pouring, it refers to the amount of chemical conversion treatment agent remaining on the surface of the metal material per unit area when the spraying or pouring of the chemical conversion treatment agent to the metal material is stopped. The liquid adhesion amount D is preferably in the range of greater than 0 L/ ^m² , less than 0.5 L/ ^m² , and preferably less than 0.4 L/ ^m² .

(Time t from Step I to Step II) In the manufacturing method of the metal material with a chemical conversion film of this embodiment, the time from the completion of Step I to the start of Step II is defined as t. The completion point of Step I, when the contact method in Step I is immersion, refers to the point at which the metal material is lifted from the chemical conversion treatment bath and removed from the liquid surface; when the contact method in Step I is spraying or pouring, it refers to the point at which the spraying or pouring of the chemical conversion treatment agent onto the metal material is stopped. The start point of Step II refers to the point at which the metal material comes into contact with the aqueous solution of Step II. The preferred duration is 0.01 minutes or more and 3.00 minutes or less, even better is 0.08 minutes or more and 2.00 minutes or less, and the exceptionally good is 0.1 minutes or more and 1.5 minutes or less.

(Specific Parameter Values) In the manufacturing method of the metal material with chemical conversion coating of this embodiment, the values derived from Equation (1) which relates to the properties of the chemical conversion agent and the values derived from Equation (2) which relate to the liquid adhesion amount and residence time of the chemical conversion agent have a specific relationship. Specifically, the value of Equation (1) minus Equation (2) is usually 0.2 or more and 5000 or less, preferably 0.5 or more and 2000 or less, and more preferably 2.5 or more and 1000 or less. If the value of Equation (1) minus Equation (2) is within the above range, a chemical conversion coating with excellent corrosion resistance after coating and excellent appearance after chemical conversion treatment can be formed.

Furthermore, before step I, which involves contact with the chemical conversion treatment agent, a further step III may be included, involving contact with an alkaline solution with a pH value of 8.0 or higher and 13.0 or lower, and a step IV, involving contact with an aqueous solution with a pH value of 7.0 or higher and 12.0 or lower. Performing steps III and IV as described above removes oil and dirt adhering to the surface of the metal material. The alkaline solution in step III is not particularly limited as long as it is an alkaline solution with a pH value of 8.0 or higher and 13.0 or lower; examples include alkaline solutions containing degreasing agents. Similarly, the aqueous solution in step IV is not particularly limited as long as it is an aqueous solution with a pH value of 7.0 or higher and 12.0 or lower; examples include sodium hydroxide aqueous solutions.

Furthermore, in the manufacturing method of the chemically converted metal material of this embodiment, in addition to steps III and IV, a pretreatment step can be performed before step I, which involves contact with the chemical conversion agent. Examples of pretreatment steps include: pickling; degreasing; alkaline washing; chromate chemical conversion treatment; phosphate chemical conversion treatment using phosphates such as zinc phosphate and ferric phosphate; bismuth replacement coating; zirconium chemical conversion treatment; titanium chemical conversion treatment; iron chemical conversion treatment; vanadium chemical conversion treatment, etc. One of these pretreatment steps may be performed, or two or more steps may be combined and performed sequentially. Examples of combinations of two or more steps include combinations of phosphate chemical conversion treatment with chromate chemical conversion treatment, bismuth replacement coating, zirconium chemical conversion treatment, titanium chemical conversion treatment, dartium chemical conversion treatment, or vanadium chemical conversion treatment. In the zirconium chemical conversion treatment performed as a pretreatment step, the aforementioned chemical conversion agents may be used, or different chemical conversion agents may be used. In addition, when performing the various pretreatment steps described above, a water washing step can be performed after each pretreatment step. When performing multiple pretreatment steps, a water washing step can be performed after each step or after some of the steps. Furthermore, if a water washing step is performed, a drying step for the surface of the metal material can be performed afterward. There is no particular limitation on the order of steps III and IV and the pretreatment steps; the pretreatment steps can be performed before or after steps III and IV. Moreover, when performing two or more pretreatment steps, the pretreatment steps can be performed before or after steps III and IV.

Furthermore, in the manufacturing method of the chemically converted metal material of this embodiment, after contact step II, post-processing steps such as alkaline washing, water washing, chromate chemical conversion treatment, zinc phosphate chemical conversion treatment, bismuth replacement coating, ferrophosphorus chemical conversion treatment, zirconium chemical conversion treatment, titanium chemical conversion treatment, adamant chemical conversion treatment, and drying can also be performed. One of these post-processing steps can be performed, or two or more steps can be combined and performed sequentially. In the zirconium chemical conversion treatment step implemented as a post-treatment step, the aforementioned chemical conversion agent can be used, or a different chemical conversion agent can be used. Furthermore, when performing the various post-treatment steps described above, a water washing step can also be performed after each post-treatment step. When performing multiple post-treatment steps, a water washing step can be performed after each step or after some steps. Moreover, if a water washing step is performed, a drying step of the metal material surface can also be performed afterward.

Furthermore, a coating film can be formed on the chemical conversion coating formed by the manufacturing method of the metal material with chemical conversion coating of this embodiment, thereby manufacturing a coated metal material having both a chemical conversion coating and a coating film. In this case, a coating film forming treatment, such as a coating step and a drying step (which may also include a baking step and a hardening step) can be performed after the formation of the chemical conversion coating to form a coating film. In addition, a drying step can be performed to dry the surface of the metal material after water washing step II. Furthermore, one or more of the above-mentioned post-treatment steps can be performed after step II and before the coating step. In addition, when performing the various post-treatment steps described above, a water washing step can also be performed after each post-treatment step. When performing multiple post-treatment steps, a water washing step can be performed after each step or after a portion of the steps. Furthermore, if a water washing step is performed, a drying step for the surface of the metal material can also be performed afterward.

The above coating steps are performed using a coating material on the surface of the aforementioned chemically converted metal material. There are no particular limitations on the coating method; conventional methods can be used, such as roller coating, electrocoating (e.g., cation electrocoating, anion electrocoating, etc.), spraying, thermal spraying, airless spraying, electrostatic (powder) coating, roller coating, curtain coating, brush coating, and flow impregnation.

Examples of the aforementioned coatings include oil-based coatings, cellulose derivative coatings, phenolic resin coatings, alkyd resin coatings, amino alkyd resin coatings, urea resin coatings, unsaturated resin coatings, vinyl resin coatings, acrylic resin coatings, epoxy resin coatings, polyurethane resin coatings, silicone resin coatings, fluoropolymer coatings, rust-proof coatings, stain-proof coatings, powder coatings, cationic electrocoating coatings, anionic electrocoating coatings, water-based coatings, solvent coatings, and other conventional coatings. Furthermore, the coating process can involve applying the same or different paints in a single coat, or applying two or more coats. The drying process involves drying and hardening the applied paint. Examples of drying methods include natural drying, depressurized drying, convective heat drying (e.g., natural convection heat drying, forced convection heat drying), radiative drying (e.g., near-infrared drying, far-infrared drying), ultraviolet curing drying, electron beam curing drying, steam curing, and baking drying. One or more of these drying methods can be used, or a combination of two or more methods can be employed.

The aforementioned cationic electrocoating can be performed using conventional methods. For example, a cationic electrocoating containing an amine addition epoxy resin as the coating and a closed-type polyisocyanate hardener as the curing component can be used, and a method is employed to immerse a metal material with a chemical conversion coating in the coating. For instance, cationic electrocoating is performed by applying voltage to the metal material with the chemical conversion coating as the cathode while stirring the coating at a specific temperature using a rectifier. By washing and baking the metal material that has undergone cationic electrocoating as described above, a coating film can be formed on the chemical conversion coating. Baking is performed for a specific time within a specific temperature range, such as 20 minutes at 170°C. Additionally, when using cationic electrocoating, to prevent coating agglomeration caused by sodium ions, it is preferable to perform the aforementioned water rinsing step before the coating process using water with a sodium ion concentration of less than 500 ppm (by mass).

Coating methods using powder coatings, such as spray coating, electrostatic powder coating, and flow impregnation, can employ conventional methods. Examples of powder coatings include those containing polyester resins and sealed isocyanate hardeners, β-hydroxyalkylamide hardeners (e.g., see Japanese Patent Application Publication No. 2011-88083), or triglycidyl isocyanurate as hardeners. Baking is performed for a specific time within a specific temperature range, such as baking at 130°C to 250°C for 20 minutes.

Painting methods using the above-mentioned solvent-based paints, such as spray painting, electrostatic painting, and stick painting, can employ conventional methods. Examples of solvent-based paints include those containing melamine resin, acrylic resin, polyurethane resin, polyester resin, etc., and organic solvents such as thinners. Baking refers to a specific time within a specific temperature range, such as baking at 130°C for 20 minutes.

Drying methods for hardening applied coatings include, for example, natural drying, depressurized drying, convective heat drying (e.g., natural convection heat drying, forced convection heat drying), radiative drying (e.g., near-infrared drying, far-infrared drying), ultraviolet curing drying, electron beam curing, and vapor curing. One or more of these drying methods may be used, or a combination of two or more may be employed.

The coating obtained through the coating process can be a single layer or multiple layers. In the case of multiple layers, the coatings used to form various coatings, the coating methods for using the coatings, and the drying methods for the coated metal materials can be the same or different from each other.

Metallic materials can be exemplified by iron (e.g., cold-rolled steel sheets, hot-rolled steel sheets, high-tensile steel sheets, tool steel, alloy tool steel, spheroidal graphite cast iron, gray cast iron, etc.); galvanized materials can be exemplified by zinc and zinc-based galvanized materials (e.g., electro-galvanizing, hot-dip galvanizing, hot-dip galvanizing-aluminum, hot-dip galvanizing-aluminum-magnesium, alloy hot-dip galvanizing, electro-galvanizing, etc.); aluminum and aluminum alloys (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 casting materials, aluminum alloy casting materials, die casting materials, etc.), aluminum-based plating materials, magnesium and magnesium alloy materials (such as AZ91, AZ61, AZ31, etc.).

In the chemical conversion coating formed by the manufacturing method of the metallic material with chemical conversion coating of this embodiment, the mass of zirconium contained in the chemical conversion coating is preferably 5 mg/ ^m² or more, more preferably 10 mg/ ^m² or more, and even more preferably 20 mg/ ^m² or more. There is no particular upper limit, but it is preferably 800 mg/ ^m² or less. Furthermore, the mass of zirconium in the chemical conversion coating can be determined using, for example, a fluorescent X-ray analyzer.

The metal material with chemical conversion coating manufactured by the manufacturing method of the present embodiment can have one or more of the above-mentioned coatings (such as chromate chemical conversion coating, phosphate chemical conversion coating, bismuth replacement coating, etc.) above or below the chemical conversion coating obtained by contacting the chemical conversion treatment agent of the present embodiment.

By applying a coating onto the surface of a metal material having a chemical conversion coating of this embodiment to form a coating film, a coated metal material having both a chemical conversion coating and a coating film can be manufactured. The coated metal material can be one having a coating film on the surface of a metal material having a chemical conversion coating of this embodiment, or it can be one having a coating film on the surface of one or more of the aforementioned coatings (e.g., chromate chemical conversion coating, phosphate chemical conversion coating, bismuth substitution coating, vanadium chemical conversion coating, etc.) further formed on the chemical conversion coating. Furthermore, the coating film can consist of one layer or two or more layers. There are no particular limitations on the thickness of the coating; it can be set appropriately according to the intended use of the metal material being coated.

[Examples] The following examples will illustrate the effects of the present invention in detail, but the present invention is not limited to the following examples. <Metallic Materials> The metallic materials are the following sheets cut into dimensions of 70mm in length × 150mm in width: cold-rolled mild steel sheet conforming to JIS G3141:2011 (SPCC: thickness 0.8mm), alloyed hot-dip galvanized steel sheet conforming to JIS G3302:2012 (GA: thickness 0.8mm), aluminum alloy sheet conforming to JIS H4000:2014 (A6061: thickness 0.8mm), hot-dip galvanized steel sheet conforming to JIS G3302:2012 (SGCC: thickness 0.8mm), conforming to JIS... H4201: Magnesium alloy sheet (MP-AZ31B: 0.8mm thickness) and hot-dip galvanized aluminum-magnesium coating (ZM40/40: 0.8mm thickness) in 2018 specifications.

<Components used in the preparation of the chemical conversion agent> The following raw materials were used in the preparation of the chemical conversion agent. (Source A) A1: Hexafluorozirconium acid A2: Zirconium nitrate A3: Zirconium hydroxide (Source B) B1: Aluminum nitrate B2: Aluminum hydroxide (Polymer C) C1: Diallylamine polymer (PAS-21; NITTOBO MEDICAL Co., Ltd., formula (i) content 100%) C2: Diallylamine hydrochloride polymer (PAS-21CL; NITTOBO MEDICAL Co., Ltd., formula (i) content 100%) C3: Allylamine hydrochloride·diallylamine hydrochloride polymer (PAA-D11-HCL; NITTOBO MEDICAL Co., Ltd., formula (i) content 50%) In addition, the fluoride ion source is hydrofluoric acid.

In addition, the following ingredients were used as other additives. (Organic Acid D) D1: Methanesulfonic Acid D2: Ethyl Acetic Acid D3: Succinic Acid D4: Citric Acid (Oxidizing Agent E) E1: Nitric Acid (Metal F other than Sources A and B) F1: Ferric Sulfate F2: Ferric Nitrate (III) F3: Copper Nitrate (Organic Silane Compound G) G1: 3-Aminopropyldimethylmethoxysilane G2: 3-Aminopropylmethyldimethoxysilane G3: 3-Aminopropyldiethylethoxysilane G4: 3-Aminopropylethyldiethoxysilane G5: 3-Aminopropyltriethoxysilane G6: 3-Aminopropyltrimethoxysilane G7: 3-Glyceroxypropyltrimethoxysilane G8: Ethyltrimethoxysilane G9: Ureapropyltriethoxysilane G10: Isocyanatepropyltriethoxysilane G11: Vinyltrimethoxysilane (metal alkoxide H) H1: Titanium methanol H2: Vanadium propoxide H3: Zirconium tetra-n-propoxide H4: Aluminum isopropoxide (other components) I1: Hydroxylamine sulfate I2: Ascorbic acid

<Preparation of Chemical Conversion Treatment Agents> As shown in Tables 1-5, after adding specific amounts of each component, the pH value was adjusted to a specific value with sodium hydroxide, thereby preparing the chemical conversion treatment agents of Examples 1-59 and Comparative Examples 1-27.

<Manufacturing of Metallic Materials with Chemical Conversion Coating> Various metallic materials are treated as shown in Tables 1-5 to manufacture metallic materials with a chemical conversion coating. Specifically, each metallic material is immersed in a degreasing agent (FC-E2093; Pakase Sei Co., Ltd., Japan; dissolved in water to a concentration of 13 g/L for agent A and 11 g/L for agent B, adjusted to a specific pH value with sodium hydroxide or _CO2 gas) at 43°C for 120 seconds (Step III). After contact with the alkaline solution, an aqueous solution adjusted to a specific pH value with sodium hydroxide is sprayed at 25°C for 30 seconds (Step IV). In addition, when using two aqueous solutions in step IV, each aqueous solution was sprayed for 30 seconds at 25°C. The sprayed metal material was placed flat on a surface, and the evaluation surface was sprayed with various chemical conversion treatment agents (chemical conversion treatment agents of Examples 1-59 and Comparative Examples 1-27) for 120 seconds to achieve the liquid adhesion amount D (L/ ^m² ) shown in Tables 1-5 (step I). The temperature of the treatment solution during spraying was set as low at 15°C and high at 38°C. After spraying the chemical conversion treatment solution, it was left for the specific time t minutes shown in Tables 1-5 (steps I-II). Then, the surface of the resulting chemically converted metal material was washed with tap water (pH 6) followed by deionized water (pH 7) in that order (Step II). After washing, the test pieces used for appearance evaluation were dried at 40°C for 10 minutes. The test pieces used for corrosion resistance after coating were not dried and were used for coating as described later.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

<Manufacturing of Metallic Materials with Coating> A metallic material with a coating is produced by coating a chemical conversion film formed on the surface of various metallic materials and then baking it. Details of the coating method and baking conditions are as follows.

(Catonic Electrocoating) Various chemically converted metal materials were used as cathodes, and electrolysis was performed using a catonic electrocoating agent (KG-400; manufactured by Kansai Paint Co., Ltd.) to form a coating. Electrolysis was carried out at an applied voltage of 180V and a temperature of 30.0±0.5℃. Furthermore, the electrolysis was performed with the applied voltage adjusted to achieve a coating thickness of 15.0±1.0 μm. After catonic electrocoating, the coating surface was washed with deionized water and then baked at 170℃ for 20 minutes to produce coated metal materials (various test pieces).

<Appearance of Chemical Transformation> The appearance of the coating on the test pieces with chemical transformation coating obtained from the various embodiments and comparative examples was determined by visual inspection. <Evaluation Criteria> A: When observing the test piece from the front, there is no unevenness in the flat area and edges; when observing the test piece at a 20° angle from the front, there is no unevenness in the flat area and edges. B: When observing the test piece from the front, there is no unevenness in the flat area and edges; when observing the test piece at a 20° angle from the front, there is unevenness in the flat area and edges. C: When observing the test piece from the front, there is no unevenness in the flat area, but there is unevenness in the edges; when observing the test piece at a 20° angle from the front, there is unevenness in the flat area and edges. D: When observing the test piece from the front, there is unevenness in the flat area and edges; when observing the test piece at a 20° angle from the front, there is unevenness in the flat area and edges.

<Corrosion Resistance Test (Exposure Test)> Using a cutting knife, cross-cuts extending to the metal substrate were made on the coated surface of various test pieces. After exposing the test pieces to the seaside of Okinawa for two years, the expansion of the coating at the cross-cut area (maximum expansion on one side) was measured, and the corrosion resistance was evaluated according to the following evaluation criteria. <Evaluation Criteria - Cross-cut Section> A: Unilateral expansion width less than 5.0 mm B: Unilateral expansion width 5.0 mm or more but less than 10.0 mm C: Unilateral expansion width 10.0 mm or more but less than 15.0 mm D: Unilateral expansion width 15.0 mm or more

<Corrosion Resistance Test (VDA Method)> Using a cutting tool, a deep scratch extending to the metal substrate was made in the center of the coated surface of various test pieces. Six cycles of corrosion testing were conducted according to VDA test 621-415 and DIN EN ISO 20567-1 (1982 version; method C). The coating expansion (maximum expansion on one side) at the scratched area (cut area) of the test piece was measured, and the corrosion resistance was evaluated according to the following standards. <Evaluation Criteria - Cut Section> A: Single-sided expansion width less than 5.0 mm B: Single-sided expansion width 5.0 mm or more but less than 10.0 mm C: Single-sided expansion width 10.0 mm or more but less than 15.0 mm D: Single-sided expansion width 15.0 mm or more The results of each evaluation test are shown in Tables 6 to 8. Furthermore, in all evaluations, B or above is set as the passing standard.

[Table 6]

[Table 7]

[Table 8]

Although the invention has been described in detail with reference to specific embodiments, various changes and modifications can be made without departing from the purpose and scope of the invention, which are self-evident to those with ordinary knowledge in the technical field to which the invention pertains.

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Claims (3)

A method for manufacturing a metal material having a chemical conversion coating, comprising forming a chemical conversion coating on or above the surface of the metal material, comprising the following steps: Step I, contacting the metal material with a chemical conversion treatment agent composed of: a fluorine ion source; a zirconium ion source A; an aluminum ion source B; and a water-soluble or water-dispersible polymer or its salt C having a structural unit of formula (i) with a molar content of 90% or more; and Step II, contacting the aforementioned metal material, after contact with the chemical conversion treatment agent, with an aqueous solution having a pH of 4.0 or higher and a pH of 12.0 or lower at least once. The value obtained by subtracting the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value from the value ^{from the} value from the ^value from the value from the value from the value from the value of ... Wherein, in the aforementioned formula (1), Ac is the concentration of zirconium element from the aforementioned supply source A in the aforementioned chemical conversion treatment agent, which is 2 g/L or less; Bc is the concentration of aluminum element from the aforementioned supply source B in the aforementioned chemical conversion treatment agent, which is 2 g/L or less; the ratio of Bc to Ac, i.e., Bc/Ac, is 0.03 or more and 10.0 or less; pH is the pH value of the aforementioned chemical conversion treatment agent, which is 3.2 or more and 6.0 or less; in the aforementioned formula (2), D is the amount of liquid adhering to the surface of the aforementioned metal material between the aforementioned steps I and II, which is more than 0 L/m ² and less than 0.5 L/m ² ; t is the time from the completion of step I to the start of step II, which is more than 0.01 minutes and less than 3.00 minutes. The method for manufacturing a metal material with a chemical conversion coating as described in claim 1, wherein, prior to step I, the method further includes the following steps: step III, contact with an alkaline solution with a pH of 8.0 or higher and 13.0 or lower; and step IV, contact with an aqueous solution with a pH of 7.0 or higher and 12.0 or lower. The method for manufacturing a metal material with a chemical conversion coating as described in claim 1 or 2, wherein the aforementioned metal material is at least one of iron, zinc or zinc-based plating, aluminum, aluminum alloy, aluminum-based plating, magnesium, and magnesium alloy.