Chromium-free chemical treatment liquid and method of manufacturing member with chromium-free chemical coating

Abstract

To provide a chromium-free chemical treatment liquid capable of forming a chromium-free chemical coating which is superior in corrosion resistance and takes environmental conservation into consideration.SOLUTION: There is provided a chromium-free chemical treatment liquid that contains aluminum-containing substance, vanadium-containing substance and phosphoric acid-containing substance, and has a first ratio of 0.1 to 2.0 as the ratio of the aluminum equivalent mol concentration of the aluminum-containing substance to the vanadium equivalent mol concentration of the vanadium-containing substance and a second ratio of 0.01 to 0.25 as the ratio of the phosphorus equivalent mol concentration of the phosphoric acid-containing substance to the aluminum equivalent mol concentration of the aluminum-containing substance, the pH being 1.0 to 4.0.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition (chemical conversion treatment liquid) for chemical conversion treatment capable of forming a chromium-free chemical conversion film that substantially does not contain a component containing chromium as an active ingredient of the chemical conversion film, has excellent corrosion resistance, and takes into account environmental protection, and a method for manufacturing a member provided with the chemical conversion film formed by the chemical conversion treatment liquid.

Background Art

[0002] In recent years, due to directives considering the environment such as the RoHS (Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment) directive and the ELV (End of Life Vehicles) directive, it has been required to regulate the use of hazardous substances (lead, mercury, cadmium, hexavalent chromium, etc.).

[0003] In response to this trend, the anticorrosive chemical conversion film of a member having a surface (hereinafter referred to as "metal-based surface") at least partially made of a metal-based material, such as a zinc-plated member, is not a composition for chemical conversion treatment using chromate containing hexavalent chromium (hereinafter, the composition for chemical conversion treatment is referred to as "chemical conversion treatment liquid"), but is formed by a chemical conversion treatment liquid containing trivalent chromium (hereinafter referred to as "trivalent chromium chemical conversion treatment liquid"). The chemical conversion film obtained by the conventional chemical conversion treatment liquid containing hexavalent chromium contains soluble hexavalent chromium in the film. Therefore, such a film is subject to regulation by the above-mentioned directives.

[0004] However, since the chemical conversion film formed from the trivalent chromium chemical conversion treatment solution contains trivalent chromium, there is a concern that the trivalent chromium in the chemical conversion film may be oxidized by substances coexisting in the chemical conversion film to generate hexavalent chromium. Therefore, there has been a demand for a chromium-free chemical conversion treatment solution capable of forming a chromium-free chemical conversion film that substantially does not contain components containing chromium. As the chromium-free chemical conversion treatment solution according to the prior art, the chemical conversion treatment solutions disclosed in Patent Documents 1 to 4 below are exemplified.

[0005] Patent Document 1 discloses a metal surface treatment agent characterized by being an aqueous solution having a pH of 1.0 to 5.0 and containing an alkaline earth metal, a phosphoric acid of phosphorus and / or its phosphate, and further containing an oxygen acid of Mo, W, V, Ti and / or its phosphate.

[0006] Patent Document 2 discloses a surface treatment solution for use on the metal surface of zinc or a zinc alloy, which contains a compound of a vanadium group element, an ion of a rare earth element, and at least one selected from the group consisting of chloride ion, fluoride ion, nitrate ion, sulfate ion, ion of a phosphoric acid of phosphorus, and acetate ion, and does not contain chromium.

[0007] Patent Document 3 discloses a chromium-free chemical conversion treatment solution characterized by containing vanadate ion, nitrate ion, and a dicarboxylic acid as a complexing agent.

[0008] Patent Document 4 discloses a chemical conversion treatment composition for zinc or a zinc alloy, which is an aqueous solution having a pH of 0.3 to 2.5 and contains at least one component selected from the group consisting of a vanadic acid compound and a tungstic acid compound in a total amount of vanadium and tungsten of 0.05 to 0.7 mol / L and a phosphoric acid compound of 0.1 to 4 mol / L.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

[0010] The chromium-free chemical conversion treatment liquids described in Patent Documents 1 to 4 may all contain a vanadium component, and it is expected that an effective chromium-free chemical conversion treatment liquid can be obtained by containing the vanadium component. However, when the present inventors confirmed the chemical conversion films formed using the chemical conversion treatment liquids disclosed in the above-mentioned documents, none of the chemical conversion films had sufficient corrosion resistance. In particular, when the shape of the member to be treated is not a simple shape with few irregularities such as a plate shape, but a complex shape with many irregularities such as a bolt, a chemical conversion film having the desired corrosion resistance could not be obtained at all.

[0011] In view of such a situation, an object of the present invention is to provide a chromium-free chemical conversion treatment liquid that is substantially free of components containing chromium, can form a chemical conversion film excellent in corrosion resistance and considerate of environmental conservation. Another object is to provide a method for manufacturing a member provided with a chemical conversion film formed by such a chromium-free chemical conversion treatment liquid. [Means for Solving the Problems

[0012] As a result of studies by the present inventors to solve the above problems, they obtained a new finding that it is possible to form a chromium-free chemical conversion film excellent in corrosion resistance by containing an aluminum-containing substance in the chemical conversion treatment liquid. Specifically, by setting the content ratio of the aluminum-containing substance with respect to the vanadium-containing substance and the phosphoric acid-containing substance within a predetermined range and setting the pH within a predetermined range, a chemical conversion treatment liquid capable of forming a chemical conversion film excellent in corrosion resistance can be obtained.

[0013] Further, by incorporating a component based on a predetermined organic acid into this chemical conversion treatment liquid, the corrosion resistance of the resulting chemical conversion film can be enhanced, and a chemical conversion film having high corrosion resistance can be obtained even if the base material has a complex shape. Also, as a new finding, it has been obtained that by further incorporating silica sol into the chemical conversion treatment liquid, it is possible to form a chemical conversion film having more excellent corrosion resistance.

[0014] The present invention completed based on the above findings is as follows. 〔1〕A chromium-free chemical conversion treatment liquid characterized by containing an aluminum-containing substance, a vanadium-containing substance, and a phosphoric acid-containing substance, wherein a first ratio which is the ratio of the aluminum-converted molar concentration of the aluminum-containing substance to the vanadium-converted molar concentration of the vanadium-containing substance is 0.1 or more and 2.0 or less, a second ratio which is the ratio of the phosphorus-converted molar concentration of the phosphoric acid-containing substance to the aluminum-converted molar concentration of the aluminum-containing substance is 0.01 or more and 0.25 or less, and the pH is 1.0 or more and 4.0 or less. 〔2〕The chromium-free chemical conversion treatment liquid according to the above 〔1〕, containing a first organic acid-containing substance composed of one or more selected from the group consisting of a first organic acid represented by Chemical Formula (1) to Chemical Formula (3), and their salts and ions, in an amount of 0.005 mol / L or more and 0.1 mol / L or less. HOOC-COOH (1) HOOC-R 1 -COOH (2) R 2 -COOH (3) Here, R 1 is a hydrocarbon group having no unshared electron pair, and R 2 is hydrogen or a hydrocarbon group having no unshared electron pair. 〔3〕The chromium-free chemical conversion treatment liquid according to the above 〔1〕 or 〔2〕, containing silica sol in an amount of 0.1 g / L or more and 60 g / L or less in terms of silicon dioxide. 〔4〕Contact the chromium-free chemical conversion treatment liquid according to any one of the above 〔1〕 to 〔3〕 with a substrate having a metal-based surface to form a chemical conversion film on the metal-based surface of the substrate; and a cleaning step of cleaning the substrate that has undergone the contact step to obtain a member provided with the chemical conversion film. A method for manufacturing a member provided with a chromium-free chemical conversion film, characterized in that it comprises: 〔5〕The method for manufacturing a member according to the above 〔4〕, wherein the metal-based surface includes the surface of a zinc-based plating film.

Effects of the Invention

[0015] According to the present invention, there is provided a chromium-free chemical conversion treatment liquid that is substantially free of substances containing chromium, which has been frequently used to form chemical conversion films excellent in corrosion resistance in the past, is excellent in corrosion resistance, and takes environmental conservation into consideration. Also provided is a method for manufacturing a member provided with a chemical conversion film formed by such a chromium-free chemical conversion treatment liquid.

Best Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail. 1. Acidic Composition for Reactive Chemical Conversion Treatment The composition of the chromium-free chemical conversion treatment liquid according to an embodiment of the present invention will be described. In this specification, the "chromium-free chemical conversion treatment liquid" means a chemical conversion treatment liquid capable of forming a chromium-free chemical conversion film that substantially does not contain chromium-containing substances. Since the chemical conversion film is chromium-free, the chemical conversion treatment liquid for forming it naturally does not contain chromium-containing substances as components for forming the chemical conversion film, but even if it contains chromium-containing substances in extremely small amounts (for example, on the order of ppm) that may inevitably exist, it can be the "chromium-free chemical conversion treatment liquid" according to this embodiment.

[0017] The chemical conversion treatment liquid according to this embodiment is a chromium-free chemical conversion treatment liquid containing an aluminum-containing substance, a vanadium-containing substance, and a phosphoric acid-containing substance as essential components. The components included in the chemical conversion treatment will be described in detail below.

[0018] (1) Aluminum-containing substance The chemical conversion treatment liquid according to this embodiment contains an aluminum-containing substance. The aluminum-containing substance is composed of one or more substances selected from the group consisting of water-soluble substances containing aluminum, such as aluminum ions and their complexes, and is in a dissolved state in the aqueous chemical conversion treatment liquid.

[0019] In order to incorporate an aluminum-containing substance into the chemical conversion treatment liquid, that is, as a raw material substance of the aluminum-containing substance, it is preferable to use a water-soluble compound (hereinafter referred to as "aluminum compound") capable of generating an aluminum-containing substance in water.

[0020] Examples of aluminum compounds include aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum hydroxide, aluminum oxide, aluminum carbonate, aluminum phosphate, potassium aluminum sulfate, etc. The water-soluble aluminum compound may be composed of only one kind of compound or may be composed of a plurality of kinds of compounds.

[0021] From the viewpoint of forming a chemical conversion film excellent in corrosion resistance, the content of the aluminum-containing substance in the chemical conversion treatment liquid according to this embodiment is preferably 0.01 mol / L or more, more preferably 0.02 mol / L or more, and particularly preferably 0.03 mol / L or more in terms of aluminum. The upper limit of the content is not particularly limited, but if the aluminum-containing substance is contained in an excessive amount, it may be disadvantageous from the viewpoints of enhancing economic efficiency and reducing the load of waste liquid treatment. Therefore, the content of the aluminum-containing substance is preferably limited to about 0.5 mol / L or less, more preferably about 0.4 mol / L or less, and particularly preferably about 0.3 mol / L or less in terms of aluminum.

[0022] Regarding the compounding amount of the aluminum compound, if the compounding amount of the aluminum compound is excessively large, part of the aluminum compound may remain undissolved and remain in the chemical conversion treatment liquid in relation to the compounding amounts of other components. Therefore, from the viewpoint of preventing the generation of such undissolved components, the upper limit of the compounding amount of the aluminum compound may preferably be 0.5 mol / L in terms of aluminum, and may more preferably be 0.4 mol / L.

[0023] (2) Vanadium-containing substance The chemical conversion treatment liquid according to this embodiment contains a vanadium-containing substance. The vanadium-containing substance consists of one or more selected from the group consisting of water-soluble substances containing vanadium, such as vanadium ions and their complexes, and vanadate ions such as vanadic acid ions, and is in a dissolved state in the aqueous chemical conversion treatment liquid.

[0024] In order to incorporate a vanadium-containing substance into the chemical conversion treatment liquid, that is, as a raw material substance of the vanadium-containing substance, it is preferable to use a water-soluble compound (hereinafter referred to as "vanadium compound") capable of generating a vanadium-containing substance in water.

[0025] Examples of vanadium compounds include vanadium chloride, vanadyl dichloride, vanadium sulfate, vanadyl sulfate, vanadium nitrate, vanadium oxide, vanadium pentoxide, vanadic acid, potassium orthovanadate, sodium orthovanadate, potassium metavanadate, sodium metavanadate, ammonium metavanadate, etc. The vanadium compound may be composed of only one type of compound or may be composed of a plurality of types.

[0026] In the chemical conversion treatment liquid according to this embodiment, the content of the vanadium-containing substance is preferably 0.01 mol / L or more, more preferably 0.02 mol / L or more, and particularly preferably 0.03 mol / L or more in terms of vanadium, from the viewpoint of forming a chemical conversion film excellent in corrosion resistance. The upper limit of the content is not particularly limited, but if the vanadium-containing substance is contained in an excessive amount, it may be disadvantageous from the viewpoints of enhancing economic efficiency and reducing the load of waste liquid treatment. Therefore, the content of the vanadium-containing substance is preferably limited to about 0.5 mol / L or less, more preferably about 0.4 mol / L or less, and particularly preferably about 0.3 mol / L or less in terms of vanadium.

[0027] In the chemical conversion treatment liquid according to this embodiment, a first ratio, which is the ratio of the aluminum-equivalent molar concentration of the aluminum-containing substance to the vanadium-equivalent molar concentration of the vanadium-containing substance, is 0.1 or more and 2.0 or less from the viewpoint of enhancing the corrosion resistance of the chemical conversion film obtained from the chemical conversion treatment liquid. From the viewpoint of more stably enhancing the corrosion resistance of the chemical conversion film, the first ratio may preferably be 0.2 or more, more preferably 0.3 or more, and particularly preferably 0.5 or more in some cases. For the same reason, the first ratio may preferably be 1.8 or less, more preferably 1.7 or less, and particularly preferably 1.5 or less in some cases.

[0028] Regarding the blending amount of the vanadium compound, when the blending amount of the vanadium compound is excessively large, a part of the vanadium compound may remain undissolved in the chemical conversion treatment liquid in relation to the blending amounts of other components. Therefore, from the viewpoint of preventing the generation of such undissolved components, the upper limit of the blending amount of the vanadium compound is preferably 0.5 mol / L or less, and more preferably 0.4 mol / L or less in terms of vanadium in some cases.

[0029] (3) Phosphoric acid-containing substance The chemical conversion treatment liquid according to this embodiment contains a phosphoric acid-containing substance. The phosphoric acid-containing substance is composed of one or more selected from the group consisting of phosphoric acid and its ions and salts, and is in a dissolved state in the aqueous chemical conversion treatment liquid.

[0030] As a substance to be blended in order to contain the phosphoric acid-containing substance in the chemical conversion treatment liquid, that is, as a raw material substance of the phosphoric acid-containing substance, it is preferable to use a water-soluble compound (hereinafter referred to as "phosphoric acid compound") capable of generating the phosphoric acid-containing substance in water.

[0031] Examples of the phosphoric acid compound include phosphoric acid, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, ammonium phosphate, diammonium hydrogen phosphate, diammonium dihydrogen phosphate, aluminum phosphate, and the like. The phosphoric acid compound may be composed of only one kind of compound or may be composed of a plurality of kinds.

[0032] From the viewpoint of forming a chemical conversion film excellent in corrosion resistance, the content of the phosphoric acid-containing substance in the chemical conversion treatment liquid according to this embodiment is preferably 0.001 mol / L or more, more preferably 0.002 mol / L or more, and particularly preferably 0.003 mol / L or more in terms of phosphorus. Further, from the viewpoint of stably forming a chemical conversion film excellent in corrosion resistance, the content of the phosphoric acid-containing substance is preferably 0.1 mol / L or less, more preferably 0.07 mol / L or less, and particularly preferably 0.05 mol / L or less in terms of phosphorus.

[0033] In the formation treatment liquid according to the present embodiment, the second ratio, which is the ratio of the molar concentration of phosphorus in the phosphorus-containing substance to the molar concentration of aluminum in the aluminum-containing substance, is 0.01 or more and 0.25 or less from the viewpoint of enhancing the corrosion resistance of the conversion coating obtained from the formation treatment liquid. From the viewpoint of more stably enhancing the corrosion resistance of the conversion coating, the second ratio may preferably be 0.02 or more, more preferably 0.03 or more, and particularly preferably 0.05 or more. For the same reason, the second ratio may preferably be 0.24 or less, more preferably 0.22 or less, and particularly preferably 0.2 or less.

[0034] (4) First organic acid-containing substance The formation treatment liquid according to the present embodiment may contain a first organic acid-containing substance composed of one or more selected from the group consisting of a first organic acid represented by any of the following chemical formulas (1) to (3) and their salts and ions, in an amount of 0.005 mol / L or more and 0.1 mol / L or less. HOOC-COOH (1) HOOC-R 1 -COOH (2) R 2 -COOH (3)

[0035] Here, R 1 is a hydrocarbon group having no lone pair of electrons, and R 2 is hydrogen or a hydrocarbon group having no lone pair of electrons.

[0036] Specific examples of the first organic acid include oxalic acid (an organic acid according to chemical formula (1)), malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, terephthalic acid, etc., which are dicarboxylic acids according to chemical formula (2); formic acid, acetic acid, propionic acid, etc., which are monocarboxylic acids according to chemical formula (3). From the viewpoint of ensuring the solubility of the first organic acid-containing substance in the formation treatment liquid, preferred examples of the first organic acid include oxalic acid and R 1Examples of the organic acid having 2 or less carbon atoms include succinic acid, maleic acid, malonic acid, fumaric acid, etc. Further, as other preferable examples of the first organic acid, R contained in the chemical formula (3) 2 Examples of the compound represented by the formula include hydrogen or an organic acid having 2 or less carbon atoms, and specific examples thereof include formic acid, acetic acid, propionic acid, etc.

[0037] The chemical conversion treatment liquid according to the present embodiment contains a first organic acid-containing substance, whereby the corrosion resistance of the chemical conversion film formed from the chemical conversion treatment liquid is improved. Generally speaking, when the base material of the chemical conversion treatment has a complex shape with unevenness like a bolt, compared with the case of having a simple shape with less unevenness like a plate material, the adhesion uniformity (surrounding adhesion property) of the chemical conversion film decreases, and a region where the adhesion amount of the chemical conversion film on the member after the chemical conversion treatment is small (low adhesion region) is likely to occur. Such a low adhesion region becomes the corrosion initiation point of the chemical conversion film. Therefore, generally, the corrosion resistance of the chemical conversion film when the base material has a complex shape is lower than that when the base material has a simple shape.

[0038] When the chemical conversion treatment liquid according to the present embodiment contains a first organic acid-containing substance, even if the base material has a complex shape, it is easy to ensure the adhesion uniformity of the chemical conversion film formed from the chemical conversion treatment liquid. For this reason, the corrosion resistance of the chemical conversion film is improved.

[0039] The reason why the first organic acid-containing substance enhances the adhesion uniformity of the chemical conversion film is not clear, but an organic acid having a functional group (other functional group) having a lone pair other than the carboxy group, for example, a substance based on an organic acid having a hydroxyl group (the lone pair is possessed by oxygen) (for example, glycolic acid or malic acid), or a substance based on an organic acid having an amino group (the lone pair is possessed by nitrogen) (for example, glycine) is contained, the effect of improving the corrosion resistance of the chemical conversion film cannot be obtained. It is considered that the carboxy group of the first organic acid interacts with metal ions such as aluminum ions and vanadium ions, which contributes to the improvement of the surrounding adhesion property. If the first organic acid has other functional groups, the lone pairs of the other functional groups may have a negative impact on the interaction between the carboxy group and the metal ions.

[0040] As a substance to be blended in order to include the first organic acid-containing substance in the chemical conversion treatment liquid, that is, as a raw material substance of the first organic acid-containing substance, it is preferable to use a water-soluble compound capable of generating the first organic acid-containing substance in water (hereinafter referred to as "the first organic acid compound").

[0041] Examples of the first organic acid compound include dicarboxylic acids according to Chemical Formula (1) or Chemical Formula (2) such as oxalic acid, succinic acid, maleic acid, malonic acid, fumaric acid, and their salts such as sodium oxalate, potassium oxalate, sodium succinate, potassium succinate, sodium maleate, potassium maleate, sodium malonate, potassium malonate, sodium fumarate, potassium fumarate; monocarboxylic acids according to Formula (3) such as formic acid, acetic acid, propionic acid, and their salts such as sodium formate, potassium formate, sodium acetate, potassium acetate, sodium propionate, potassium propionate, etc. The first organic acid compound may be composed of only one kind of compound or may be composed of a plurality of kinds.

[0042] When the first organic acid-containing substance is included in the chemical conversion treatment liquid according to this embodiment, the content of the first organic acid-containing substance is preferably 0.005 mol / L or more, more preferably 0.008 mol / L or more, and particularly preferably 0.01 mol / L or more in terms of organic acid in view of stably obtaining the effect of improving the corrosion resistance of the chemical conversion film. The upper limit of its content is not particularly limited, but if the first organic acid compound is contained in an excessive amount, it may be disadvantageous from the viewpoints of enhancing economy and reducing the load of waste liquid treatment. Also, depending on the type of the first organic acid, in relation to other components, if the content of the first organic acid-containing substance becomes excessive, the effect of improving the corrosion resistance of the chemical conversion treatment may not be obtained. Therefore, the content of the first organic acid-containing substance is preferably limited to about 0.1 mol / L or less, more preferably about 0.09 mol / L or less, and particularly preferably about 0.08 mol / L or less in terms of organic acid.

[0043] Regarding the blending amount of the first organic acid compound, when the blending amount of the first organic acid compound is excessively large, a part of the first organic acid compound may remain undissolved and remain in the chemical conversion treatment liquid in relation to the blending amounts of other components. Therefore, from the viewpoint of preventing the generation of such undissolved components, the upper limit of the blending amount of the first organic acid compound may preferably be 0.1 mol / L in terms of the first organic acid, and may more preferably be 0.09 mol / L.

[0044] (5) Silica sol The chemical conversion treatment liquid according to this embodiment may contain silica sol in an amount of 0.1 to 60 g / L in terms of silicon dioxide. By containing silica sol, the corrosion resistance of the chemical conversion film may be improved. Also, the wettability of the chemical conversion film may be improved, and the friction coefficient of the chemical conversion film may be adjusted within a predetermined range. Specific examples of silica sol include "Snowtex O" manufactured by Nissan Chemical Industries, Ltd. and "Cataloid SN" manufactured by JGC Catalysts & Chemicals Ltd. Silica sol may be composed of one type of material or may be composed of a plurality of types. Since the pH of the chemical conversion treatment liquid is acidic as described later, silica sol is preferably acidic. Silica sol may be surface-modified.

[0045] When the chemical conversion treatment liquid according to this embodiment contains silica sol, the content of silica sol is preferably 0.1 g / L or more, more preferably 1 g / L or more, and particularly preferably 10 g / L or more in terms of silicon dioxide from the viewpoint of stably obtaining the effect of improving the corrosion resistance of the chemical conversion film. The upper limit of its content is not particularly limited, but from the viewpoints of enhancing economic efficiency and reducing the load of waste liquid treatment, the merit of containing an excessive amount of silica sol is small. Also, from the viewpoints of ensuring the stability of the chemical conversion treatment liquid and reducing the possibility of appearance defects in the chemical conversion film, the content of silica sol is preferably limited to about 60 g / L or less, more preferably about 50 g / L or less, and particularly preferably about 40 g / L or less in terms of silicon dioxide.

[0046] (6) Other organic acid-containing substances In addition, the chemical conversion treatment liquid according to the present embodiment may contain an organic acid-containing substance based on an organic acid other than the above-described first organic acid (also referred to as "other organic acid-containing substance" in this specification). Examples of the organic acid that provides the other organic acid-containing substance include tricarboxylic acids such as tricarballylic acid and aconitic acid; hydroxycarboxylic acids such as glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, isocitric acid, and ascorbic acid; and aminocarboxylic acids such as glycine and alanine. The organic acid-containing substances containing these organic acids do not have the effect of improving the corrosion resistance of the chemical conversion film like the first organic acid-containing substance, but may have effects such as improving the stability of the chemical conversion treatment liquid. The content of the other organic acid-containing substance in terms of organic acid should be appropriately set for each organic acid-containing substance, but there is also a concern that the function of the first organic acid-containing substance may decrease if it is contained excessively. Therefore, the content of the other organic acid-containing substance in terms of organic acid is preferably 0.1 mol / L or less.

[0047] (7) Other components In addition to the above substances, the chemical conversion treatment liquid according to the present embodiment may contain one or more selected from the group consisting of a water-soluble substance (metal-containing substance) containing a metal element other than the above-described metal elements (Al and V), an inorganic acid and its anion, an inorganic colloid, a silane coupling agent, and an organic phosphorus compound. Further, it may further contain one or more components selected from the group consisting of polyphenols such as pyrogallol and benzenediol; corrosion inhibitors; surfactants such as diols, triols, and amines; plasticizers; coloring materials such as dyes, pigments, and metal pigment generators; and desiccants and dispersants.

[0048] The chemical conversion treatment liquid according to the present embodiment does not substantially contain a water-soluble substance containing fluorine from the viewpoint of reducing the impact on the environment. Further, since the chemical conversion treatment by the chemical conversion treatment liquid according to the present embodiment is a reaction type, it does not substantially contain an organic component having film-forming properties such as polyvinyl alcohol.

[0049] Examples of the metal elements contained in the metal-containing substance include Zn, Ni, Na, K, Ag, Fe, Ca, Mg, Sc, Mn, Cu, Sn, Mo, Co, Zr, Te, Ti, and W. The metal-containing substance may exist in the form of hydrated ions in the chemical conversion treatment liquid, may exist in the form of oxyacid ions such as tungstate ions, or may exist in the form of a coordination compound. By including these metal-containing substances in the chemical conversion treatment liquid, additional effects may be obtained. Since the chemical conversion treatment liquid according to the present embodiment is a chromium-free chemical conversion treatment liquid, chromium-containing substances are not positively present in the chemical conversion treatment liquid.

[0050] The content of the above metal-containing substance is not particularly limited. It is appropriately set according to the role of the metal element contained in each metal-containing substance. For example, in the case of a nickel-containing substance, it is preferably 0.0001 mol / L or more, more preferably 0.0005 mol / L or more, and particularly preferably 0.001 mol / L or more in terms of nickel conversion. The upper limit of the content of the nickel-containing substance is not particularly limited, but if the nickel-containing substance is contained in an excessive amount, it may be disadvantageous from the viewpoints of enhancing economic efficiency and reducing the load of waste liquid treatment. Rather, excessive inclusion of the nickel-containing substance is feared to reduce the stability of the chemical conversion treatment liquid. Therefore, the content of the nickel-containing substance is preferably limited to about 1 mol / L or less, more preferably about 0.5 mol / L or less, and particularly preferably about 0.1 mol / L or less in terms of nickel conversion.

[0051] Examples of the inorganic acid include hydrohalic acids other than hydrofluoric acid such as hydrochloric acid and hydrobromic acid, chloric acid, perchloric acid, chlorous acid, hypochlorous acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid, ultraphosphoric acid, hypophosphorous acid, and perphosphoric acid. In particular, it is preferable that one or more selected from the group consisting of hydrohalic acids other than hydrofluoric acid, sulfuric acid, and nitric acid are contained as anions. From the viewpoint of enhancing the progress of the reaction related to the chemical conversion treatment, it may be preferable to use nitric acid as the inorganic acid. Note that nitric acid may be present in the chemical conversion treatment liquid as a nitrate or nitrate ion.

[0052] The content of these inorganic acids and / or inorganic acid ions is not particularly limited. Generally, the ratio of the total molar concentration of the inorganic acid and inorganic acid ions to the total molar concentration in terms of metal of the water-soluble metal-containing substance (here, including essential components Al and V) is 0.1 or more and 10 or less, preferably 0.5 or more and 3 or less.

[0053] Examples of the inorganic colloid include alumina sol, titanium sol, and zirconia sol, and examples of the silane coupling agent include vinyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane.

[0054] (8) Solvent, pH The solvent of the chemical conversion treatment liquid according to the present embodiment is mainly composed of water. From the viewpoint of increasing the solubility of the solute of the chemical conversion treatment liquid, the solvent may contain an organic solvent soluble in water such as alcohol, ether, and ester in addition to water. Even in that case, from the viewpoints of enhancing economic efficiency and reducing the load of waste liquid treatment, the content of the organic solvent is preferably 10% by mass or less of the entire solvent in some cases.

[0055] Further, the chemical conversion treatment liquid according to the present embodiment is acidic from the viewpoint of promoting the chemical conversion treatment, and the pH of the chemical conversion treatment liquid is set to be 1.0 or more and 4.0 or less from the viewpoint of ensuring the stability of the chemical conversion treatment liquid and enabling the formation of a chemical conversion film excellent in corrosion resistance. From the viewpoint of enhancing the quality of the chemical conversion film and the stability of the chemical conversion treatment liquid, the pH is preferably 1.5 or more and 3.5 or less, and more preferably 2.0 or more and 3.0 or less. For adjusting the pH of the chemical conversion treatment liquid, alkaline substances such as sodium hydroxide, potassium hydroxide, and ammonia, and acidic substances such as nitric acid, sulfuric acid, and hydrochloric acid can be used.

[0056] 2. Concentrated Composition for Preparing Chemical Conversion Treatment Liquid If a liquid composition (hereinafter referred to as "concentrated liquid for chemical conversion treatment") having a composition in which the main components of the above chemical conversion treatment liquid are concentrated about 5 times to about 20 times is prepared, it is preferable because it can save the labor of individually preparing the content of each component and is easy to store. When preparing this concentrated liquid for chemical conversion treatment, an upper limit is set for its content in consideration of the solubility of the substances (such as aluminum compounds) that give the above components in the chemical conversion treatment liquid.

[0057] 3. Substrate on which Chemical Conversion Treatment is Performed The material of the substrate on which the chemical conversion treatment according to the present embodiment is performed is not particularly limited as long as it has a metal-based surface on which a chemical conversion film can be formed using the chemical conversion treatment liquid according to the present embodiment. Preferred materials are metal-based materials, and in particular, a steel sheet coated with zinc-based plating is particularly preferred. The plating method may be electroplating or hot-dip plating, and in the case of hot-dip plating, an alloying treatment may be performed after plating.

[0058] Note that the composition of the above zinc-based plating may be pure zinc or a zinc alloy. In the case of zinc alloy plating, iron, nickel, and aluminum are exemplified as alloy metals. The plating method may be electroplating or hot-dip plating. In the case of electroplating, any of a cyanide bath, a chloride bath, a sulfate bath, and a zincate bath may be used, and a baking treatment may be performed after forming the plating film. Also, in the case of hot-dip plating, an alloying treatment may be performed after plating.

[0059] The shape of the base material is not limited either. The base material may have a simple shape with few irregularities like a plate material, or may have a complex shape with many irregularities like a bolt. The chemical conversion treatment liquid according to the present embodiment can form a chemical conversion film with good wrap-around property even when the base material has a complex shape. Therefore, such a chemical conversion film is excellent in corrosion resistance.

[0060] 4. Method for manufacturing a member provided with a chromium-free chemical conversion film A method for manufacturing a member provided with a chromium-free chemical conversion film using the chromium-free chemical conversion treatment liquid according to the present embodiment will be described.

[0061] The manufacturing method according to the present embodiment includes a contact step of bringing the chromium-free chemical conversion treatment liquid according to the present embodiment into contact with a base material having a metal-based surface to form a chemical conversion film on the metal-based surface of this base material, and a cleaning step of cleaning the base material that has undergone the contact step to obtain a member provided with a chromium-free chemical conversion film.

[0062] In the contact step, the method of bringing the chemical conversion treatment liquid according to the present embodiment into contact with a base material having a metal-based surface is not particularly limited. The simplest method is immersion, but spraying or coating using a roll (roll coating) may also be used. In the case of immersion, it may be preferable to stir the chemical conversion treatment liquid or rock the base material.

[0063] The contact conditions (contact temperature, contact time) between the chemical conversion treatment liquid and the base material are not particularly limited, and may be appropriately set in consideration of the composition of the chemical conversion treatment liquid, the composition of the material constituting the base material surface, productivity, etc. As an example where the temperature during the treatment of the chemical conversion treatment liquid is not limited, a range from room temperature (about 25°C) to about 50°C can be mentioned, and a range from 30°C to 40°C can be mentioned as a specific example of a preferable range. As a specific example where the contact time between the chemical conversion treatment liquid and the base material is not limited, a range from 10 seconds to 120 seconds can be mentioned, and a range from 20 seconds to 90 seconds can be mentioned as a specific example of a preferable range. Note that since the chemical conversion treatment liquid according to the present embodiment is a reaction-type chemical conversion treatment liquid, even if the time is made excessively long, it is not normal for the thickness of the chemical conversion film to increase according to the time.

[0064] The base material used in the contacting step is cleaned by a known method (for example, degreasing and rinsing), and may be subjected to an activation treatment by contacting it with an acidic aqueous solution (for example, a nitric acid aqueous solution of about several ml / L) at about room temperature for about 10 seconds.

[0065] The base material that has undergone the contacting step is washed using, for example, water. This is a step that is different from that of a so-called coating-type chemical conversion treatment liquid, and is performed because the chemical conversion treatment liquid according to the present embodiment is a reaction-type chemical conversion treatment liquid. By such a step, the chemical conversion treatment liquid remaining on the surface of the base material that has undergone the contacting step is washed away, and a member including the base material and the chemical conversion film is obtained. For the member after washing, a drying step is usually performed for the purpose of removing moisture adhering to the chemical conversion film and the base material. The drying conditions (drying temperature, drying time) are not particularly limited. They are appropriately set in consideration of the heat resistance, productivity, etc. of the base material. In some cases, it may be dried by leaving it standing in an oven maintained at a temperature of about 100°C or lower for about 10 minutes, in some cases, it may be dried using a centrifuge, and in some cases, it may be dried by leaving it standing in a normal environment. Note that depending on the type of the chemical conversion film, a change in composition may occur during drying, for example, a part or all of the hydroxide may change to an oxide.

[0066] In addition, the manufacturing method according to the present embodiment may include a finishing treatment step of forming a finishing film by treating the above base material with the chemical conversion treatment liquid according to the present embodiment to form a chromium-free chemical conversion film and then performing treatment with a finishing agent for enhancing corrosion resistance and scratch resistance. The type of the finishing treatment is not particularly limited, and specific examples include inorganic treatments such as silicate-based and phosphate-based treatments, organic treatments such as paints and resins, and organic-inorganic composite treatments. The solvent of the treatment agent for the finishing treatment is appropriately set according to the components contained in the treatment agent, and may be aqueous or non-aqueous. Specific examples of the treatment agent for the finishing treatment include "Metas YC-T", "LUBRUS C24", etc., all manufactured by Yuken Kogyo Co., Ltd.

[0067] The relationship between the finishing process and the drying process is appropriately set according to the type of the finishing process. After the cleaning process, there may be a case where the finishing process is performed without drying and then the drying process is performed, or there may be a case where the drying process is performed after the cleaning process and then the finishing process is performed.

[0068] 5. Method of Using Chromium-Free Chemical Conversion Treatment Liquid The method of using the chromium-free chemical conversion treatment liquid according to this embodiment will be described. The method of use according to this embodiment includes bringing the chromium-free chemical conversion treatment liquid according to this embodiment into contact with a substrate having a metal-based surface, and forming a chromium-free chemical conversion film on the metal-based surface of this substrate.

[0069] The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

Examples

[0070] Hereinafter, the effects of the present invention will be described based on examples, but the present invention is not limited thereto.

[0071] (Examples 1 to 12 and Comparative Examples 1 to 13) 1. Preparation of Test Specimens Chemical conversion treatment liquids according to Examples 1 to 12 and Comparative Examples 1 to 12 having the compositions shown in Table 1 were prepared. The solvent of each chemical conversion treatment liquid was pure water. The aluminum compound used for the preparation of each chemical conversion treatment liquid was aluminum sulfate, the vanadium compound was vanadium pentoxide, and the phosphoric acid compound was phosphoric acid. The pH was adjusted using nitric acid and sodium hydroxide. Magnesium hydroxide was used in the preparation of the chemical conversion treatment liquid according to Comparative Example 9, calcium hydroxide was used in the preparation of the chemical conversion treatment liquid according to Comparative Example 10, cerium sulfate was used in the preparation of the chemical conversion treatment liquid according to Comparative Example 11, and titanium sulfate was used in the preparation of the chemical conversion treatment liquid according to Comparative Example 12.

[0072]

Table 1

[0073] In Table 1, [Al], [Mg], [Ca], [Ce], [Ti], and [V] represent the molar concentration in terms of metal (such as aluminum-containing substances) of the substances containing the metals within the parentheses (unit: mol / L), [P] represents the molar concentration in terms of phosphorus of the phosphoric acid-containing substances (unit: mol / L), and [nitric acid] represents the molar concentration in terms of nitric acid of the nitric acid-containing substances (one or more substances selected from the group consisting of nitric acid and its salts and ions) (unit: mol / L). Also, [Al] / [V] in Table 1 is the first ratio, and [P] / [Al] is the second ratio. The column of treatment pH indicates the pH of the chemical conversion treatment solution (the same applies to Tables 2 and 3).

[0074] Also, as Comparative Example 13, a chemical conversion treatment solution of Sample No. 26 in the example of Patent Document 3 was prepared.

[0075] A base material having a zinc plating with a thickness of 8 - 10 μm was prepared on a cold-rolled steel sheet (100 mm × 50 mm × thickness 0.8 mm). After subjecting this base material to an activation treatment (immersion for 10 seconds) with a nitric acid aqueous solution of about 0.05 mol / L (25 °C), it was washed with water and immersed in any one of the chemical conversion treatment solutions of Examples 1 to 12 and Comparative Examples 1 to 13. For any of the chemical conversion treatment solutions, the immersion conditions were 35 °C for 30 seconds, and the base material was oscillated in the chemical conversion treatment solution. The test piece after immersion was washed with water (oscillated in pure water for 10 seconds) and dried (80 °C, 10 minutes). Thus, test members were obtained.

[0076] 2. Evaluation of Test Members (1) Evaluation of Corrosion Resistance The neutral salt spray test was conducted on the obtained test specimens in accordance with JIS Z2371:2000 (ISO 9227:1990). The area of white rust generation on the main surface of the test specimens was visually measured every 24 hours, and the ratio (unit: %) with respect to the area of the main surface of the test specimens was calculated from the measurement results. When the white rust area ratio was less than 10%, the neutral salt spray test was continued. When the white rust area ratio was 10% or more, the test was terminated, and the total test time was defined as the SST white rust 10% generation time (unit: hours).

[0077] (2) Other evaluations The as-prepared chemical conversion treatment solution was visually observed to confirm the presence or absence of precipitation.

[0078] 3. Evaluation results The measurement results and evaluation results are shown in Table 1. As shown in Table 1, when the chemical conversion treatment solution contains an aluminum-containing substance, a vanadium-containing substance, and a phosphoric acid-containing substance such that the first ratio and the second ratio are within appropriate ranges and the pH is within the range of 1.0 to 4.0 (Examples 1 to 12), the SST white rust 10% generation time is 120 hours or more, and a chemical conversion coating having higher corrosion resistance than the chemical conversion coating obtained from the chemical conversion treatment solution according to the prior art containing trivalent chromium (Comparative Example 13) was obtained.

[0079] On the other hand, when the first ratio is in an inappropriate range (Comparative Examples 1, 2, and 5), when the second ratio is in an inappropriate range (Comparative Examples 3, 4, and 6), when the pH is in an inappropriate range (Comparative Examples 7 and 8), and when the aluminum-containing substance is not contained (Comparative Examples 9 to 12), the corrosion resistance was lower than that of the chemical conversion coating formed from the chemical conversion treatment solution shown in Comparative Example 13. It was confirmed that precipitation occurred in the chemical conversion treatment solutions according to Comparative Examples 7 and 8 and Comparative Example 12 at the stage immediately after preparation.

[0080] (Examples 13 to 36 and Comparative Examples 14 and 15) 1. Preparation of test specimens Similar to the formation treatment liquid according to Example 1, the aluminum-equivalent molar concentration of the aluminum-containing substance is 0.08 mol / L, the vanadium-equivalent molar concentration of the vanadium-containing substance is 0.08 mol / L, and the phosphorus-equivalent molar concentration of the phosphoric acid-containing substance is 0.01 mol / L. A formation treatment liquid containing the organic acids shown in Table 2 at the concentrations shown in Table 2 and having the pH shown in Table 2 was prepared. In Table 2, the unit of the numbers in the "concentration" column of "organic acid" is mol / L. Among the organic acids shown in Table 2, the organic acids used in Examples 13 to 33 and Comparative Examples 14 and 15 are the first organic acids, and the organic acids used in Examples 34 to 36 are not the first organic acids. The formation treatment liquid according to Example 14 and the formation treatment liquid according to Example 15 have the same liquid composition, the formation treatment liquid according to Example 22 and the formation treatment liquid according to Example 23 have the same liquid composition, and the formation treatment liquid according to Example 30 and the formation treatment liquid according to Example 31 have the same liquid composition.

[0081] The aluminum compound used in the preparation of each formation treatment liquid is aluminum nitrate, the vanadium compound is sodium metavanadate, and the phosphoric acid compound is trisodium phosphate. The pH was adjusted using nitric acid and sodium hydroxide when preparing each formation treatment liquid.

[0082]

Table 2

[0083] Among Examples 13 to 36, except for Examples 15, 23, and 31, substrates having zinc plating with a thickness of 8 to 10 μm on M10 bolts (half-threaded, M10×50 mm) conforming to JIS B1180 were prepared. For Examples 15, 23, and 31, substrates of cold-rolled steel sheets were prepared in the same manner as in Example 1. After subjecting these substrates to an activation treatment (immersion for 10 seconds) with a nitric acid aqueous solution of about 0.05 mol / L (25°C) and then washing with water, they were immersed in either the chemical conversion treatment solution of Examples 13 to 36 or the chemical conversion treatment solution of Comparative Examples 14 to 15. The immersion conditions for any of the chemical conversion treatment solutions were 35°C for 30 seconds, and the substrates were rocked in the chemical conversion treatment solution. The test pieces after immersion were washed with water (rocked in pure water for 10 seconds) and dried (80°C, 10 minutes). Thus, test members were obtained.

[0084] 2. Evaluation of Test Members (1) Evaluation of Corrosion Resistance A neutral salt spray test was conducted on the obtained test members in accordance with JIS Z2371:2000 (ISO 9227:1990). Among Examples 13 to 36, except for Examples 15, 23, and 31, the area of white rust generation on the threaded part of the test member was visually measured every 24 hours, and the ratio (unit: %) to the area of the threaded part of the test member was calculated from the measurement results. When the white rust area ratio was less than 10%, the neutral salt spray test was continued. When the white rust area ratio was 10% or more, the test was terminated, and the total test time was taken as the SST white rust 10% generation time (unit: hours). For Examples 15, 23, and 31, the SST white rust 10% generation time (unit: hours) was determined in the same manner as in Example 1 and the like.

[0085] (2) Other Evaluations The chemical conversion treatment solution immediately after preparation was visually observed to confirm the presence or absence of precipitation.

[0086] 3. Evaluation Results The measurement results and evaluation results are shown in Table 2. As shown in the results of Example 30, when the base material of the test member is a bolt having a complex shape with many irregularities, compared with the case where the base material of the test member is a plate material having a simple shape with few irregularities, even if the composition of the chemical conversion treatment liquid is the same, it was confirmed that the SST white rust 10% occurrence time is shortened to less than half (see Example 1 and Example 31). Note that the chemical conversion treatment liquid according to Example 1 and the chemical conversion treatment liquid according to Example 30 and Example 31 have the same concentrations of aluminum-containing substances, vanadium-containing substances, and phosphoric acid-containing substances, but since the raw materials are different, the concentrations of other components contained in the chemical conversion treatment liquid such as nitrate ions are different. Thus, since the SST white rust 10% occurrence time is affected by the shape of the base material, in the chemical conversion treatment liquids according to Comparative Examples 1 to 12 where the base material of the test member is a plate material and the maximum SST white rust 10% occurrence time is 48 hours, it is assumed that when the base material of the test member is a bolt, the SST white rust 10% occurrence time will not be 24 hours or more.

[0087] As shown in Examples 13 to 29, when the chemical conversion treatment liquid according to the present embodiment contains the first organic acid-containing substance at an appropriate concentration, even when the base material of the test member is a bolt, the SST white rust 10% occurrence time is 120 hours or more, and it was confirmed that a chemical conversion film having particularly high corrosion resistance is formed.

[0088] Note that as shown in Examples 32 and 33, when the chemical conversion treatment liquid according to the present embodiment does not contain the first organic acid-containing substance at an appropriate concentration, the effect of containing the first organic acid-containing substance in the chemical conversion treatment liquid cannot be obtained. Also, as shown in Comparative Examples 14 and 15, when the pH of the chemical conversion treatment liquid is not within the predetermined range (1.0 to 4.0), the corrosion resistance is lower than that of the chemical conversion film formed from the chemical conversion treatment liquid shown in Example 30. Furthermore, as shown in Examples 34 to 36, when an organic acid other than the first organic acid is blended, no particular effect such as when the first organic acid is blended is obtained.

[0089] (Examples 37 to 43) 1. Preparation and evaluation of test members Similar to the chemical conversion treatment liquid according to Example 1, the pH is 2.5, the aluminum-equivalent molar concentration of the aluminum-containing substance is 0.08 mol / L, the vanadium-equivalent molar concentration of the vanadium-containing substance is 0.08 mol / L, the phosphorus-equivalent molar concentration of the phosphoric acid-containing substance is 0.01 mol / L, and the nitric acid-equivalent molar concentration of the nitric acid-containing substance is 0.1 mol / L. Similar to the chemical conversion treatment liquid according to Example 14, a chemical conversion treatment liquid containing 0.05 mol / L of a first organic acid-containing substance having oxalic acid as the first organic acid and further containing silica sol at the concentration shown in Table 3 was prepared.

[0090] The aluminum compound used for the preparation of each chemical conversion treatment liquid was aluminum chloride, the vanadium compound was vanadium sulfate, the phosphoric acid compound was potassium phosphate, and oxalic acid was used as the raw material of the first organic acid-containing substance. The pH was adjusted using nitric acid and sodium hydroxide when preparing each chemical conversion treatment liquid.

[0091]

Table 3

[0092] In Table 3, [oxalic acid] means the oxalic acid-equivalent molar concentration (unit: mol / L) of the first organic acid-containing substance, [silica sol] is the silicon dioxide-equivalent content of the silica sol (unit: g / L), and [nitric acid] means the nitric acid-equivalent molar concentration (unit: mol / L) of the nitric acid-containing substance (one or more substances selected from the group consisting of nitric acid and its salts and ions).

[0093] Hereinafter, test members having a cold-rolled steel sheet as a base material were produced in the same manner as in Example 1 and the like, and a neutral salt spray test was conducted to obtain the SST white rust 10% occurrence time (unit: hour). The results are shown in Table 3. Also, the chemical conversion treatment liquid immediately after preparation was visually observed to confirm the presence or absence of precipitation, and the test member immediately after production was visually observed for appearance evaluation.

[0094] 2. Evaluation Results As shown in Table 3, when the content of the silica sol in the formation treatment liquid is 0.1 g / L or more (Examples 37 to 40 and Example 42), compared with the case where no silica sol is contained (Example 41), the SST white rust 10% occurrence time becomes longer, and the effect of improving corrosion resistance is confirmed. On the other hand, when the content of the silica sol in the formation treatment liquid is less than 0.1 g / L (Example 43), the effect of containing the silica sol was not confirmed. In addition, the formation film according to Example 42 had a powdery surface. Therefore, it was confirmed that when the content of the silica sol in the formation treatment liquid is 70 g / L or more, the applicable range of the obtained formation film may be limited from the viewpoint of appearance.

Claims

1. containing an aluminum-containing substance, a vanadium-containing substance, and a phosphoric acid-containing substance, wherein a first ratio, which is a ratio of the aluminum-equivalent molar concentration of the aluminum-containing substance to the vanadium-equivalent molar concentration of the vanadium-containing substance, is 0.1 or more and 2.0 or less; wherein a second ratio, which is a ratio of the phosphorus-equivalent molar concentration of the phosphoric acid-containing substance to the aluminum-equivalent molar concentration of the aluminum-containing substance, is 0.01 or more and 0.25 or less; and having a pH of 1.0 or more and 4.0 or less characterized by a chromium-free chemical conversion treatment liquid.

2. The chromium-free chemical conversion treatment liquid according to claim 1, containing 0.005 mol / L or more and 0.1 mol / L or less of a first organic acid-containing substance composed of one or more selected from the group consisting of the first organic acids represented by Chemical Formulas (1) to (3), their salts, and ions. HOOC-COOH (1) HOOC-R 1 -COOH (2) R 2 -COOH (3) Here, R 1 is a hydrocarbon group having no unshared electron pair, and R 2 is hydrogen or a hydrocarbon group having no unshared electron pair.

3. The chromium-free chemical conversion treatment liquid according to claim 1 or claim 2, containing silica sol at 0.1 g / L or more and 60 g / L or less in terms of silicon dioxide.

4. A contact step of bringing the chromium-free chemical conversion treatment liquid according to any one of claims 1 to 3 into contact with a substrate having a metal-based surface to form a chemical conversion film on the metal-based surface of the substrate; and a cleaning step of cleaning the substrate that has undergone the contact step to obtain a member provided with the chemical conversion film characterized by a method for manufacturing a member provided with a chromium-free chemical conversion film.

5. The method for manufacturing a member according to claim 4, wherein the metal-based surface includes the surface of a zinc-based plating film.

Images