JP2025068520A - Aluminum-based metal material with chemical conversion coating film, chemical conversion treatment liquid for aluminum-based metal material, and surface treatment method for aluminum-based metal material - Google Patents

Abstract

To provide an aluminum-based metal material with a chemical conversion coating film, which has excellent corrosion resistance not only in a neutral environment but also in an acidic environment and an environment that contains Cu.SOLUTION: Disclosed is an aluminum-based metal material with a chemical conversion coating film, which has, on the surface of the aluminum-based metal material, a chemical conversion coating film that contains 1 mg/m2 to 160 mg/m2 of at least one metal element (A) that is selected from the group consisting of Zr, Ti, and V, 5-50 mg/m2 of elemental Cr (B) that is not hexavalent Cr, and 6-100 mg/m2 of elemental C, where: the mass ratio (A/B) of the metal element (A) to the elemental Cr (B) that is not hexavalent Cr is 1.45 to 5.0; and the mass ratio (C/B) of the elemental C to the elemental Cr (B) that is not hexavalent Cr is 0.15 to 7.2.SELECTED DRAWING: None

Description

The present invention relates to an aluminum-based metal material with a chemical conversion coating, a chemical conversion treatment solution for aluminum-based metal materials, and a method for surface treatment of aluminum-based metal materials.

Conventionally, chemical conversion treatment solutions containing trivalent chromium for metal materials have been developed for a wide range of fields, including aircraft materials, building materials, and automobile parts.

For example, Patent Document 1 discloses a chemical conversion treatment liquid for metallic materials that contains component (A) consisting of a water-soluble trivalent chromium compound, component (B) consisting of at least one compound selected from a water-soluble titanium compound and a water-soluble zirconium compound, component (C) consisting of a water-soluble nitrate compound, component (D) consisting of a water-soluble aluminum compound, and component (E) consisting of a fluorine compound.

Patent Document 2 discloses a chemical conversion treatment solution for metal materials that contains specific amounts of a specific trivalent chromium compound, a specific zirconium compound, and a specific dicarboxylic acid compound.

Patent Document 3 discloses a chemical conversion treatment solution for metal materials that contains predetermined amounts of a specific trivalent chromium compound, a specific zirconium compound, a specific phenol compound, and a fluorine-containing compound.

JP 2006-328501 A JP 2006-316334 A International Publication No. 2019/131436

However, while the chemical conversion treatment solutions for metal materials described in Patent Documents 1 to 3 are capable of forming a chemical conversion film with excellent corrosion resistance in a neutral environment on aluminum-based metal materials, it is difficult to form a chemical conversion film with excellent corrosion resistance in an acidic environment and an environment that contains Cu.

In view of the above circumstances, in one embodiment, the present invention aims to provide an aluminum-based metal material with a chemical conversion coating that has excellent corrosion resistance not only in neutral environments but also in acidic environments and environments containing Cu. In another embodiment, the present invention aims to provide a chemical conversion treatment liquid for aluminum-based metal materials that is suitable for obtaining the aluminum-based metal material with the chemical conversion coating. In yet another embodiment, the present invention aims to provide a surface treatment method for aluminum-based metal materials using the chemical conversion treatment liquid for aluminum-based metal materials.

As a result of intensive research, the inventors discovered that the above problems could be solved by forming a chemical conversion coating containing a specified amount of a specified component on the surface of an aluminum-based metal material, and thus completed the present invention.

That is, the present invention is exemplified as follows.
[Aspect 1]
An aluminum-based metallic material with a chemical conversion coating has a surface thereof comprising a chemical conversion coating containing 1 mg/ ^m2 to 160 mg/ ^m2 of at least one metal element (A) selected from the group consisting of Zr, Ti and V, 5 to 50 mg/ ^m2 of a Cr element (B) that is not a hexavalent Cr, and 6 to 100 mg/ ^m2 of a C element, wherein the mass ratio (A/B) of the metal element (A) to the Cr element (B) that is not a hexavalent Cr is 1.45 to 5.0, and the mass ratio (C/B) of the C element to the Cr element (B) that is not a hexavalent Cr is 0.15 to 7.2.
[Aspect 2]
2. The aluminum-based metal material with a chemical conversion coating according to claim 1, wherein the C element of the chemical conversion coating is derived from a polymer having a carbonyl group.
[Aspect 3]
3. The aluminum-based metallic material with a chemical conversion coating according to claim 1, wherein the chemical conversion coating contains an F element.
[Aspect 4]
In the emission intensity analysis using a Marcus-type high-frequency glow discharge optical emission surface analyzer (GD-OES), the depth range within 20 nm from the outermost surface is defined as the surface side, and the depth range beyond the depth at which the Al intensity first reaches 5 times the average value of the Al intensity in the depth range from the outermost surface to 5 nm is defined as the substrate side.
The aluminum-based metal material with a chemical conversion coating according to any one of Aspects 1 to 3, wherein the C element and the O element show maximum strength on the surface layer side, and at least one selected from the metal element (A) and the Cr element (B) that is not hexavalent Cr shows maximum strength on the substrate side.
[Aspect 5]
A chemical conversion treatment liquid for an aluminum-based metallic material, comprising: at least one metal compound (a) selected from the group consisting of zirconium compounds, titanium compounds, and vanadium compounds; a trivalent chromium compound (b); a polymer (C) having a carbonyl group; and a fluorine-containing compound (D).
[Aspect 6]
A chemical conversion treatment solution for aluminum-based metallic materials according to Aspect 5, wherein a mass ratio (A/B) of at least one metal element (A) selected from the group consisting of Zr, Ti and V to a Cr element (B) that is not hexavalent Cr is 0.6 to 7.0, and a mass ratio (C/B) of a C element to the Cr element (B) that is not hexavalent Cr is 0.5 to 20.
[Aspect 7]
A chemical conversion treatment solution for aluminum-based metallic materials according to aspect 5 or 6, wherein a mass ratio (X/Y) of the mass (X) of the polymer (C) having a carbonyl group to the total mass (Y) of Zr, Ti, V and Cr is 0.50 to 2.80.
[Aspect 8]
A step (i) of contacting an aluminum-based metallic material with the chemical conversion treatment solution for an aluminum-based metallic material according to any one of aspects 5 to 7 for 60 seconds or more;
After the step (i), a step (ii) of washing the aluminum-based metallic material with water;
The surface treatment method of the aluminum-based metal material includes the steps of:
[Aspect 9]
A method for surface treatment of an aluminum-based metallic material according to embodiment 8, wherein in the step (i), the time for contacting the aluminum-based metallic material with the chemical conversion treatment solution for aluminum-based metallic materials is 60 seconds to 600 seconds.

According to one embodiment of the present invention, it is possible to obtain an aluminum-based metal material with a chemical conversion coating that has excellent corrosion resistance not only in neutral environments but also in acidic environments and environments containing Cu. According to another embodiment of the present invention, it is possible to obtain a chemical conversion treatment liquid for aluminum-based metal materials that is suitable for obtaining the aluminum-based metal material with the chemical conversion coating. According to yet another embodiment of the present invention, it is possible to obtain a surface treatment method for aluminum-based metal materials using the chemical conversion treatment liquid for aluminum-based metal materials.

1 shows an example of an emission intensity profile of each element obtained when performing depth profiling by GD-OES.

The following describes an embodiment of the present invention. Note that in the present invention, the description "X to Y" indicating a numerical range means "X or more and Y or less."

<<1. Aluminum-based metal materials with chemical conversion coating>>
(Aluminum-based metal materials)
The aluminum-based metal material according to one embodiment of the present invention is not particularly limited, and may be a pure aluminum material, an aluminum alloy material, or the like. Examples of the aluminum alloy material include Al-Cu, Al-Si, Al-Mg, Al-Zn, Al-Si-Cu, Al-Si-Mg, Al-Co-Cu, Al-Mn-Mg, Al-Mn-Fe, and Al-Mn-Zn-Fe-Mg materials. The aluminum-based metal material may be used alone, or may be used as a composite material in combination with other metals, ceramics, or the like.

(At least one metal element (A) selected from the group consisting of Zr, Ti and V)
The chemical conversion coating according to one embodiment of the present invention contains at least one metal element (A) selected from the group consisting of Zr (zirconium), Ti (titanium), and V (vanadium).
The content of the metal element (A) in the chemical conversion coating is 1 mg/ ^m2 to 160 mg/ ^m2 , preferably 5 mg/ ^m2 to 160 mg/ ^m2 , more preferably 10 mg/ ^m2 to 160 mg/ ^m2 , and even more preferably 20 mg/ ^m2 to 160 mg/ ^m2 . When two or more types of metal elements (A) are contained in the chemical conversion coating, the total content of these elements is defined as the content of the metal element (A). If the content of the metal element (A) is less than 1 mg/ ^m2 , sufficient corrosion resistance cannot be obtained, and if it is more than 160 mg/ ^m2 , the cost increases.

The compound form of the metal element (A) contained in the chemical conversion coating according to one embodiment of the present invention is not particularly limited. The metal element (A) in the chemical conversion coating may be the metal compound (a) contained in the chemical conversion treatment liquid for aluminum-based metallic materials described below that is directly incorporated into the chemical conversion coating, or the metal compound (a) may be converted into a different compound form (such as an oxide) by a chemical conversion reaction with the aluminum-based metallic material and then incorporated.

(Cr element (B) that is not hexavalent Cr)
The chemical conversion coating according to one embodiment of the present invention contains Cr (chromium) element (B) that is not hexavalent Cr.
The content of the non-hexavalent Cr element (B) in the chemical conversion coating is 5 to 50 mg/ ^m2 , preferably 10 to 50 mg/ ^m2 , more preferably 15 to 50 mg/ ^m2 , and even more preferably 20 to 50 mg/ ^m2 . If the content of the non-hexavalent Cr element (B) is less than 5 mg/ ^m2 , sufficient corrosion resistance cannot be obtained, and if it is more than 50 mg/ ^m2 , the cost increases.

The compound form of the Cr element (B) that is not hexavalent Cr contained in the chemical conversion film according to one embodiment of the present invention is not particularly limited. The Cr element (B) that is not hexavalent Cr in the chemical conversion film may be a trivalent chromium compound (b) contained in the chemical conversion treatment liquid for aluminum-based metallic materials described below that is directly incorporated into the chemical conversion film, or the trivalent chromium compound (b) may be converted into another compound form (such as an oxide) by a chemical conversion reaction with the aluminum-based metallic material and then incorporated.

The chemical conversion coating according to one embodiment of the present invention may contain hexavalent Cr as long as the intended effect of the present invention is not lost, but considering the impact on the environment, it is preferable not to include it.

(C element)
The chemical conversion coating according to one embodiment of the present invention contains C (carbon). The content of C in the chemical conversion coating is 6 to 100 mg/ ^m2 , preferably 10 to 100 mg/ ^m2 , more preferably 15 to 100 mg/ ^m2 , and even more preferably 20 to 100 mg/ ^m2 . If the content of C is less than 6 mg/ ^m2 , sufficient corrosion resistance cannot be obtained, and if it is more than 100 mg/ ^m2 , the cost increases.

The origin of the C element is not particularly limited, but it is preferably derived from a polymer (C) having a carbonyl group. The polymer (C) having a carbonyl group is not particularly limited as long as it has a carbonyl group in its structure. More specifically, functional groups having a carbonyl group include amide groups, urethane groups, carboxy groups, acrylic groups, ester groups, etc. Examples of polymers (C) having a carbonyl group include polyesters, polyacrylamides, polyurethanes, polyacrylic acids, polyacrylic acid esters, etc. Only one type of polymer (C) having a carbonyl group may be contained in the chemical conversion coating, or two or more types may be contained.

The polymer (C) having a carbonyl group in the chemical conversion coating according to one embodiment of the present invention may be the polymer (C) having a carbonyl group contained in the chemical conversion treatment liquid for aluminum-based metallic materials described below that is directly incorporated into the chemical conversion coating, or the polymer (C) having a carbonyl group may form a complex with a metal compound and a chromium compound in the chemical conversion treatment liquid for aluminum-based metallic materials, and may be co-deposited with the metal compound and the chromium compound by contacting with the aluminum-based metallic material.

Corrosion resistance can be improved by appropriately adjusting the mass ratio (A/B) of the metal element (A) to the non-hexavalent Cr element (B). Specifically, the mass ratio (A/B) of the metal element (A) to the non-hexavalent Cr element (B) is preferably 1.45 to 5.0, more preferably 1.45 to 4.2, and even more preferably 1.45 to 3.64. When two or more types of metal elements (A) are contained in the chemical conversion coating, A/B is calculated based on their total content.

Corrosion resistance can be improved by appropriately adjusting the mass ratio (C/B) of C element to non-hexavalent Cr element (B). Specifically, the mass ratio (C/B) of C element to non-hexavalent Cr element (B) is preferably 0.15 to 7.2, more preferably 0.5 to 7.2, and even more preferably 1.35 to 7.2.

The chemical conversion coating according to one embodiment of the present invention contains F (fluorine). The presence of F element can be confirmed by X-ray fluorescence analysis. The presence of F (fluorine) element in the chemical conversion coating is desirable from the viewpoint of corrosion resistance.

The thickness of the chemical conversion coating in one embodiment of the present invention is not particularly limited, but is preferably 10 to 600 nm, and more preferably 30 to 600 nm.

The chemical conversion coating according to one embodiment of the present invention is not particularly limited in terms of the distribution of each of the coating components in the depth direction of the coating, so long as it contains a predetermined amount of each of the above-mentioned coating components. However, in a depth direction emission intensity analysis using a Marcus-type high-frequency glow discharge optical emission surface analyzer (GD-OES), it is desirable to have C and O elements concentrated on the surface layer side, and at least one, preferably two or more selected from a metal element (A) and a Cr element (B) that is not hexavalent Cr concentrated on the substrate side (hereinafter referred to as the "gradient structure of the chemical conversion coating"), in order to improve corrosion resistance compared to cases where this is not the case.

Here, the "surface side" refers to a depth range within 20 nm from the outermost surface of the chemical conversion coating in the emission intensity profile of each element obtained when performing a depth direction analysis using a Marcus type high frequency glow discharge optical emission surface analyzer (GD-OES), the "substrate side" refers to a depth range from the depth where the Al intensity first reaches 5 times the average value of the Al intensity in the depth range from the outermost surface of the chemical conversion coating to 5 nm measured by GD-OES, and the "concentration" refers to the position where the intensity of each coating component measured by GD-OES shows a maximum value in the measurement range. Figure 1 shows an example of an emission intensity profile of each element obtained when performing a depth direction analysis using GD-OES. In this specification, the depth measured by GD-OES is a value converted based on the sputtering rate of Si. Specifically, sputtering conditions that result in a sputtering rate of 40 nm/s for Si are determined in advance, and a depth direction analysis using GD-OES is performed under the sputtering conditions, and the sputtering time is converted to depth.

The gradient structure of the chemical conversion coating is formed, for example, by contacting an aluminum-based metal material with a chemical conversion treatment solution for aluminum-based metal materials, which contains at least one metal compound (a) selected from the group consisting of zirconium compounds, titanium compounds, and vanadium compounds, a trivalent chromium compound (b), a polymer having a carbonyl group (C), and a fluorine-containing compound (D), for 60 seconds or more, and then rinsing the aluminum-based metal material with water.

<<2. Chemical conversion treatment solution for aluminum-based metal materials>>
(At least one metal compound (a) selected from the group consisting of zirconium compounds, titanium compounds and vanadium compounds)
The chemical conversion treatment liquid for aluminum-based metallic materials according to one embodiment of the present invention contains at least one metal compound (a) selected from the group consisting of zirconium compounds, titanium compounds and vanadium compounds. The metal compound (a) may be used alone or in combination of two or more kinds.

Examples of zirconium compounds include zirconium tetrapropoxide, hexafluorozirconium acid, zirconium nitrate, zirconyl nitrate, zirconium carbonate, zirconium hydroxide, and zirconium oxide. The zirconium compound may be present in the form of zirconium ions in the chemical conversion treatment liquid for aluminum-based metal materials. Examples of zirconium ions include metal ions of zirconium, complex ions containing zirconium, and oxide ions of zirconium. Examples of complex ions containing zirconium include hexafluorozirconium ammonium, tetrafluorozirconium, trifluorozirconium ammonium, and hexafluorozirconium salts.

Examples of titanium compounds include titanium tetrapropoxide, hexafluorotitanium acid, titanium nitrate, titanium carbonate, dititanium hydroxide, and titanium oxide. The titanium compound may be present in the form of titanium ions in the chemical conversion treatment liquid for aluminum-based metal materials. Examples of titanium ions include titanium metal ions, titanium-containing complex ions, and titanium oxide ions. Examples of titanium-containing complex ions include hexafluorotitanium ammonium, hexafluorotitanium salts, titanium tetrafluoride, and titanium trifluoride ammonium.

Examples of vanadium compounds include vanadium oxypropoxide, vanadium nitrate, vanadium carbonate, vanadium hydroxide, and vanadium oxide. The vanadium compound may be present in the form of vanadium ions in the chemical conversion treatment liquid for aluminum-based metal materials. Examples of vanadium ions include metal ions of vanadium, complex ions containing vanadium, and oxide ions of vanadium. Examples of complex ions containing vanadium include vanadium fluoride and hexafluorovanadic acid.

The content of the metal compound (a) in the chemical conversion treatment liquid for aluminum-based metallic materials according to one embodiment of the present invention is not particularly limited, but is usually 1.5 to 500 mg/L, and more preferably 25 to 300 mg/L, converted into the value of the metal element zirconium, titanium or vanadium. When two or more types of metal compounds (a) are used, the total content of the metal element zirconium, titanium or vanadium contained in each metal compound (a) is regarded as the content of the metal compound (a).

(Trivalent chromium compounds (b))
The aluminum-based metal material chemical conversion treatment liquid according to one embodiment of the present invention contains a trivalent chromium compound (b). Examples of trivalent chromium compounds include chromium (III) fluoride, chromium (III) nitrate, chromium (III) sulfate, chromium (III) oxysulfate, and chromium (III) phosphate. The trivalent chromium compound may be present in the form of chromium ions in the aluminum-based metal material chemical conversion treatment liquid. Only one type of trivalent chromium compound may be used, or two or more types may be used in combination. The content of the trivalent chromium compound in the aluminum-based metal material chemical conversion treatment liquid is not particularly limited, but is usually 1 to 200 mg/L, and more preferably 25 to 150 mg/L, in terms of chromium. When two or more types of trivalent chromium compounds are used, the total content of the trivalent chromium compounds is taken as the content of the trivalent chromium compound.

(Polymer (C) Having Carbonyl Group)
The chemical conversion treatment liquid for aluminum-based metallic materials according to one embodiment of the present invention contains a polymer (C) having a carbonyl group. As described above, the polymer (C) having a carbonyl group is not particularly limited as long as it has a carbonyl group in its structure. More specifically, examples of functional groups having a carbonyl group include an amide group, a urethane group, a carboxy group, an acrylic group, and an ester group. The polymer (C) having a carbonyl group may have only one type of carbonyl group in its structure, or may have two or more types of carbonyl groups. Examples of the polymer (C) having a carbonyl group include polyester, polyacrylamide, polyurethane, polyacrylic acid, and polyacrylic acid ester. The polymer (C) having a carbonyl group may be used alone or in combination of two or more types. The content of the polymer (C) having a carbonyl group in the chemical conversion treatment liquid for aluminum-based metallic materials is not particularly limited, but is usually 1 to 1000 mg/L, and more preferably 100 to 600 mg/L, in terms of carbon. When two or more kinds of polymers (C) having a carbonyl group are used, the total content of the polymers (C) having a carbonyl group is regarded as the content of the polymer (C) having a carbonyl group.

(Fluorine-containing compound (D))
The aluminum-based metal material chemical conversion treatment liquid according to one embodiment of the present invention contains a fluorine-containing compound (D). Examples of the fluorine-containing compound (D) include hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, germanium fluoride, potassium fluoride, potassium hydrogen fluoride, iron fluoride, hydrosilicic acid, sodium fluoride, sodium hydrogen fluoride, hexafluorozirconium acid, hexafluorotitanium acid, and chromium (III) fluoride. Compounds that fall under both the metal compound (a) or the trivalent chromium compound (b) and the fluorine-containing compound (D) (e.g., hexafluorozirconium acid, hexafluorotitanium acid, and chromium (III) fluoride) function as the respective compounds. Only one type of fluorine-containing compound may be used, or two or more types may be used in combination. The content of the fluorine-containing compound in the chemical conversion treatment solution for aluminum-based metallic materials is not particularly limited, but the free fluorine ion concentration in the entire chemical conversion treatment solution for aluminum-based metallic materials is usually 3 to 100 mg/L, and more preferably 5 to 70 mg/L. The free fluorine ion concentration can be measured using a commercially available fluoride ion meter (ion electrode: fluoride ion composite electrode F-2021 (manufactured by DKK-TOA Corporation)) or the like.

The pH of the chemical conversion treatment solution for aluminum-based metal materials according to one embodiment of the present invention is not particularly limited, but is preferably 2.3 to 5.0, and more preferably 3.0 to 4.5. The pH can be adjusted by adding an acid or alkali (e.g., sodium hydroxide, ammonia, ammonium bicarbonate, nitric acid, sulfuric acid, hydrochloric acid, hydrofluoric acid, etc.). Here, the pH in this specification means the value at 25°C. The pH can be measured, for example, with a portable electrical conductivity/pH meter {WM-32EP (manufactured by DKK-TOA Corporation)}, etc.

In the chemical conversion treatment solution for aluminum-based metallic materials according to one embodiment of the present invention, the corrosion resistance can be improved by appropriately adjusting the mass ratio (A/B) of the metal element (A) to the non-hexavalent Cr element (B). Specifically, A/B is preferably 0.6 to 7.0, more preferably 0.6 to 4.2, and even more preferably 0.6 to 1.67. When two or more types of metal elements (A) are contained in the chemical conversion treatment solution, A/B is calculated based on their total content.

In the chemical conversion treatment solution for aluminum-based metallic materials according to one embodiment of the present invention, the corrosion resistance can be improved by appropriately adjusting the mass ratio (C/B) of C element to non-hexavalent Cr element (B). Specifically, C/B is preferably 0.5 to 20, more preferably 0.5 to 7.2, and even more preferably 0.5 to 3.33.

In the chemical conversion treatment solution for aluminum-based metallic materials according to one embodiment of the present invention, the corrosion resistance can be improved by appropriately adjusting the mass ratio (X/Y) of the mass (X) of the polymer (C) having a carbonyl group to the total mass (Y) of Zr, Ti, V and Cr. Specifically, X/Y is preferably 0.50 to 2.80, more preferably 0.50 to 1.76, and even more preferably 0.50 to 1.25.

<<3. Surface treatment method for aluminum-based metal materials>>
An aluminum-based metal material with a chemical conversion coating according to one embodiment of the present invention can be obtained by a surface treatment method including a step (i) of contacting an aluminum-based metal material with a chemical conversion treatment solution for aluminum-based metal materials for 60 seconds or more (hereinafter referred to as the "chemical conversion treatment step"), and a step (ii) of washing the aluminum-based metal material with water (hereinafter referred to as the "water washing treatment step") after the step (i). The method of contact is not particularly limited, and for example, a dipping treatment method, a spraying treatment method, a pouring treatment method, or a combination of these methods can be used.

In the chemical conversion treatment step, the temperature of the chemical conversion treatment solution for aluminum-based metallic materials at the time of contact is preferably in the range of 30°C or higher and 70°C or lower. The contact time is preferably in the range of 60 to 600 seconds, more preferably in the range of 60 to 300 seconds, and even more preferably in the range of 120 to 180 seconds. After the chemical conversion treatment step, a water washing treatment step is performed. After the chemical conversion treatment step or the water washing treatment step following the chemical conversion treatment step, a drying step may be performed. For example, drying can be performed for 10 to 6000 seconds in an atmosphere of 30 to 250°C.

Prior to the chemical conversion treatment step, although not essential, degreasing, hot water washing, pickling, solvent washing, etc. are usually performed in appropriate combination to remove oil and dirt adhering to the aluminum-based metal material (hereinafter referred to as the "cleaning step"). There are no particular limitations on the method of degreasing, and it can be appropriately selected from methods conventionally used in degreasing aluminum-based metal materials. Examples of degreasing methods that can be used include solvent degreasing (solvent washing, solvent vapor washing), alkaline degreasing, electrolytic alkaline degreasing, and emulsion degreasing. The aluminum-based metal material that has been subjected to the cleaning step may be subjected to a water washing step before the chemical conversion treatment step.

When manufacturing an aluminum-based metal material having a surface treatment film on the chemical conversion film manufactured by the manufacturing method of an aluminum-based metal material with a chemical conversion film according to one embodiment of the present invention, a step for forming the surface treatment film may be carried out after the manufacturing of the chemical conversion film. This step may be carried out multiple times to form one or more surface treatment films. Furthermore, after the above-mentioned chemical conversion treatment step and before the step for forming the surface treatment film is carried out, one or more water washing steps may be carried out. If a water washing step is carried out, a drying step may be carried out thereafter to dry the surface of the metal material.

The process for forming the surface treatment film is carried out on the surface of the metal material having the chemical conversion film by using a surface treatment agent or paint. The treatment method is not particularly limited, and conventionally known methods such as immersion, curtain flow coating, airless spray coating, hot spray coating, rolling coating, electrocoating (e.g. cationic electrocoating, anionic electrocoating, etc.), electrostatic (powder) coating, roller coating, brush coating, bar coating, and fluidized bed immersion can be applied, and a baking process or drying process may be carried out after the treatment as necessary.

When manufacturing an aluminum-based metal material having a surface treatment film on the chemical conversion film manufactured by the manufacturing method of an aluminum-based material with a chemical conversion film according to one embodiment of the present invention, a surface treatment agent may be applied for the purpose of imparting hydrophilicity. The surface treatment agent has a resin. The resin is not particularly limited, but examples thereof include urethane resin, polyvinyl alcohol resin, polyamide resin, epoxy resin, acrylic resin, amine resin, phenol resin, polyvinylpyrrolidone resin, polycarbodiimide resin, etc. The resin may be a homopolymer of these resins (including modified products in which the side chains of the homopolymers are modified with other compounds), or a copolymer obtained by combining and polymerizing two or more monomers to obtain these resins or modified products. Of these, it is preferable to use a resin having at least one functional group selected from an amino group, an amide group, a carboxy group, and a hydroxy group. The resin may have only one type of these functional groups, or may have two or more types. The surface treatment agent may contain only one type of resin, or may contain two or more types of resins. In addition to the resin, the surface treatment agent may contain deionized water, water-miscible solvents, etc. as appropriate.

The applications of the aluminum-based metal material with a chemical conversion coating according to one embodiment of the present invention are not particularly limited, but may be used, for example, in heat exchangers, building materials, automotive components, battery materials, etc.

By carrying out the above treatment, an aluminum-based metal material with a chemical conversion coating or an aluminum-based metal material having a surface treatment coating thereon can be obtained. The suitable thickness of the coating is as described above. The surface treatment coating on the chemical conversion coating may be composed of a single layer, or may be composed of multiple layers by carrying out the above treatment multiple times.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

(1. Raw materials used in the preparation of the surface treatment agent for aluminum-based metal materials)
As shown in Table 1, raw materials A1 to A5 were used as metal compounds (a), raw materials B1 to B3 were used as trivalent chromium compounds (b), raw materials C1 to C4 were used as polymers having a carbonyl group (C), and raw material D1 was used as a fluorine-containing compound (D).

(2. Surface treatment agents for aluminum-based metal materials)
The raw materials shown in Table 1 were mixed with water to give the concentrations shown in Table 2, to obtain surface treatment agents 1 to 23 for aluminum-based metallic materials.

In addition, the content (Y1) of the metal compound (a) shown in Table 2 is the mass concentration converted into metal, the content (Y3) of the trivalent chromium compound (b) is the mass concentration converted into chromium, and the content (X) of the polymer (C) having a carbonyl group is the mass concentration of the polymer itself.

<Measurement of free fluoride ion concentration>
The free fluorine ion concentration in each surface treatment agent for aluminum-based metallic materials was measured using a commercially available fluorine ion meter (ion electrode: fluoride ion composite electrode F-2021 (manufactured by DKK-TOA Corporation)). The results are shown in Table 2.

(3. Surface treatment of aluminum-based metal materials)
Example 1 (chemical conversion treatment)
A 70 mm x 75 mm x 0.8 mmt flat pure aluminum material (A1050P as specified in JIS H 4000:2014) was immersed for 3 minutes in an alkaline degreaser (a 20 g/L aqueous solution of Fine Cleaner 315E manufactured by Nippon Parkerizing) heated to 60 ° C., and then the surface was rinsed and cleaned with deionized water. The cleaned pure aluminum material was then immersed for 60 seconds in a surface treatment agent 1 at a temperature of 53 ° C., which had been adjusted to pH 3.7 using ammonia water. The pure aluminum material was then removed from the surface treatment agent 1 and washed with deionized water, and then dried in an electric oven (80 ° C. for 5 minutes) to obtain an aluminum-based metal material with a chemical conversion coating.

<Examples 2 to 17 and Comparative Examples 1 to 6 (chemical conversion treatment)>
Chemical conversion treatment was carried out under the same conditions as in Example 1 except that the conditions were changed to those shown in Table 3, to obtain aluminum-based metallic materials with chemical conversion coatings of Examples 2 to 17 and Comparative Examples 1 to 6.

<Comparative Examples 7 to 9 (painting)>
The pure aluminum materials shown in Table 3, which had been cleaned under the same conditions as in Example 1, were immersed in surface treatment agent 12, 16 or 23 at room temperature (about 25° C.) for 20 seconds, and then, without rinsing with water, the pure aluminum materials were taken out of surface treatment agent 12, 16 or 23, respectively, and baked and dried in an electric oven (at 150° C. for 6 minutes). In this way, the aluminum-based metal materials with coatings of Comparative Examples 7 to 9 were obtained.

(4. Analysis of surface-treated aluminum materials)
The mass of metal and the mass of carbon per unit area contained in the coating of the surface-treated aluminum material of Examples 1 to 17 and Comparative Examples 1 to 9 were measured by the following method. The measurement results are shown in Table 4.

In addition, the concentrated position (surface side or substrate side) in the coating thickness direction of each element contained in the surface-treated aluminum materials of Examples 1 to 17 and Comparative Examples 1 to 9 was measured by the following method. The measurement results are shown in Table 4. Note that there were cases where the elements were concentrated in a position between the surface side and the substrate side, and not all elements were concentrated on either the surface side or the substrate side.

The presence or absence of carbonyl groups in the molecular structures of the polymers in the surface-treated aluminum materials of Examples 1 to 17 and Comparative Examples 1 to 9 was measured using the following method. The measurement results are shown in Table 4.

The presence or absence of F element was measured for the coatings of the surface-treated aluminum materials of Examples 1 to 17 and Comparative Examples 1 to 9 using the following method. The measurement results are shown in Table 4.

The presence or absence of hexavalent chromium was measured for the surface-treated aluminum materials of Examples 1 to 17 and Comparative Examples 1 to 9 using the following method. The measurement results are shown in Table 4.

The thickness of the coating was measured for the surface-treated aluminum materials of Examples 1 to 17 and Comparative Examples 1 to 9 using the following method. The measurement results are shown in Table 4.

<Mass of metal per unit area>
The mass of metals (Zr, V, Ti, Cr) per unit area was measured using a scanning X-ray fluorescence analyzer (ZSX primus II (manufactured by Rigaku Corporation)) based on a calibration curve prepared in advance by changing the content of each metal in the coating, and the measured metal mass was calculated by dividing the measured metal mass by the X-ray irradiation area (π×15×15 ^mm2 ). The X-ray irradiation diameter was 30 mmφ. The surface-treated aluminum material was cut into 3.2 cm squares as the analysis sample, and the average value of three samples was taken as the measurement value.

<Carbon mass per unit area>
The carbon equivalent mass per unit area was calculated by using a total organic carbon meter (TOC-L (Shimadzu Corporation)) equipped with a solid sample combustion device to completely combust organic matter contained in the surface-treated aluminum material at a furnace temperature of 700°C, measuring the carbon mass from a calibration curve prepared in advance using a standard sample, and dividing the measured carbon mass by the surface area (projected area) of the surface-treated aluminum material used in the measurement. The surface-treated aluminum material was cut into pieces of 7.5 mmφ to serve as an analytical sample, and the average value of five samples was taken as the measured value.

<Presence or absence of carbonyl group>
A variable angle reflection accessory was attached to a Fourier transform infrared spectrophotometer (FT-IR) {Spectrum Two (manufactured by PerkinElmer)}, and measurements were performed by the reflection method. The measurements were performed at an infrared light incidence angle of 45°, a resolution of 4 cm ⁻¹ , an accumulation count of 32, a wave number range of 400 to 4000 cm ⁻¹ , and a temperature of 25° C. From the obtained infrared absorption spectrum, the presence or absence of an absorption peak (2000 to 1500 cm ⁻¹ ) due to carbonyl groups was confirmed. Taking into account the variation depending on the measurement location, the presence or absence of carbonyl groups was evaluated based on the results obtained from three randomly selected points on the surface-treated aluminum material. At this time, if a carbonyl group peak was confirmed at two or more measurement points out of the three points, the carbonyl group was deemed to be “present”.

<Analysis of the gradient structure of the film>
The emission intensity analysis of each element by a Marcus-type high-frequency glow discharge optical emission surface analyzer (GD-OES) was carried out using a JY-5000RF device manufactured by Horiba, Ltd. The GD-OES analysis was performed by argon sputtering in a pulse sputtering mode with a measurement range of 10 mmφ. The outermost surface of the surface-treated aluminum material was used as the measurement start position, and measurements were performed every 0.8 nm from the outermost surface toward the aluminum material, which is the base material, to a depth of 2.5 mm. The depth range from the outermost surface of the chemical conversion coating to 20 nm in the depth direction was defined as the "surface side", and the depth range from the outermost surface to the depth range of 5 nm from the outermost surface was defined as the "substrate side", and the depth range from the depth at which the Al intensity first reaches 5 times was defined as the "substrate side". The positions at which the intensity of each coating component showed the maximum value (concentration) in the measurement range were investigated. Considering the variation due to the measurement location, the gradient structure was evaluated based on the analysis results at three randomly selected points on the surface-treated aluminum material. At this time, it was confirmed that a similar gradient structure was obtained at two or more points out of the three points.

<Analysis of fluorine in coating>
Using a scanning X-ray fluorescence analyzer {ZSX primus II (manufactured by Rigaku Corporation)}, the wavelength range in which fluorescent X-rays of elements Be to U can be detected was adjusted to investigate whether or not F element was detected in the coating of the surface-treated aluminum material. A Rh tube was used, and the X-ray irradiation area of the analysis sample was 30 mmφ. The surface-treated aluminum material was cut into 3.2 cm square pieces to serve as analysis samples, and three samples were analyzed. At this time, if fluorine peaks were confirmed at two or more measurement points out of the three points, it was determined that fluorine was "detected," and if not, it was determined that fluorine was "not detected."

<Analysis of hexavalent chromium>
A hexavalent chromium elution test was conducted using the diphenylcarbazide coloring method in accordance with JIS H8625-1993 to confirm whether hexavalent chromium was detected in the surface-treated aluminum material. As a result, hexavalent chromium was recorded as "detected" when it was 0.05 mg/L or more, and as "not detected" when it was less than 0.05 mg/L.

<Film thickness>
The thickness was measured from the results of the GD-OES analysis. The thickness was calculated by multiplying the sputtering time (seconds) at which the Al intensity first reached 10 times the average value of the Al intensity in the depth range of 5 nm from the outermost surface by the sputtering rate of Si (40 nm/second).

(5. Corrosion resistance test for surface-treated aluminum materials)
<Corrosion resistance in neutral environments (salt spray test)>
A neutral salt spray test (JIS-Z2371:2015) was conducted on the surface-treated aluminum materials of Examples 1 to 17 and Comparative Examples 1 to 9. The evaluation time was 720 hours. After drying, the proportion of white rust that had developed on the surface of the surface-treated aluminum material was measured visually. The proportion of white rust is the proportion of the area where white rust has developed relative to the area of the observed portion. The evaluation criteria are as follows. The evaluation results are shown in Table 4.
<Evaluation criteria>
5 Percentage of white rust: 10% or less 4 Percentage of white rust: over 10% to 30% or less 3 Percentage of white rust: over 30% to 50% or less 2 Percentage of white rust: over 50% to 70% or less 1 Percentage of white rust: over 70%

<Corrosion resistance in acidic environments [SWAAT test (Sea Water Acidified Test)]>
The surface-treated aluminum materials of Examples 1 to 17 and Comparative Examples 1 to 9 were subjected to a SWAAT test (ASTM G85 Annex 2). The number of evaluation cycles was 240. After drying, the proportion of white rust that had developed on the surface of the surface-treated aluminum material was measured visually. The proportion of white rust is the proportion of the area where white rust has developed to the area of the observed portion. The evaluation criteria are as follows. The evaluation results are shown in Table 4.
<Evaluation criteria>
5 Percentage of white rust: 10% or less 4 Percentage of white rust: over 10% to 30% or less 3 Percentage of white rust: over 30% to 50% or less 2 Percentage of white rust: over 50% to 70% or less 1 Percentage of white rust: over 70%

<Corrosion resistance in acidic environments containing Cu (CAS test)>
The CASS test (JIS-Z2371:2015) was carried out on the surface-treated aluminum materials of Examples 1 to 17 and Comparative Examples 1 to 9. The evaluation time was 24 hours. After drying, the proportion of white rust that had occurred on the surface of the surface-treated aluminum material was measured visually. The proportion of white rust is the proportion of the area where white rust has occurred to the area of the observed portion. The evaluation criteria are as follows. The evaluation results are shown in Table 4.
<Evaluation criteria>
5 Percentage of white rust: 10% or less 4 Percentage of white rust: over 10% to 30% or less 3 Percentage of white rust: over 30% to 50% or less 2 Percentage of white rust: over 50% to 70% or less 1 Percentage of white rust: over 70%

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

Claims (9)

An aluminum-based metallic material with a chemical conversion coating has a surface thereof comprising a chemical conversion coating containing 1 mg/ ^m2 to 160 mg/ ^m2 of at least one metal element (A) selected from the group consisting of Zr, Ti and V, 5 to 50 mg/ ^m2 of a Cr element (B) that is not a hexavalent Cr, and 6 to 100 mg/ ^m2 of a C element, wherein the mass ratio (A/B) of the metal element (A) to the Cr element (B) that is not a hexavalent Cr is 1.45 to 5.0, and the mass ratio (C/B) of the C element to the Cr element (B) that is not a hexavalent Cr is 0.15 to 7.2. The aluminum-based metal material with a chemical conversion coating according to claim 1, wherein the C element of the chemical conversion coating is derived from a polymer having a carbonyl group. The aluminum-based metal material with a chemical conversion coating according to claim 1 or 2, wherein the chemical conversion coating contains an F element. In the emission intensity analysis using a Marcus-type high-frequency glow discharge optical emission surface analyzer (GD-OES), the depth range within 20 nm from the outermost surface is defined as the surface side, and the depth range beyond the depth at which the Al intensity first reaches 5 times the average value of the Al intensity in the depth range from the outermost surface to 5 nm is defined as the substrate side.
3. The aluminum-based metal material with a chemical conversion coating according to claim 1 or 2, wherein the C element and the O element show maximum strength on the surface layer side, and at least one element selected from the metal element (A) and the Cr element (B) that is not hexavalent Cr shows maximum strength on the substrate side. A chemical conversion treatment solution for aluminum-based metal materials, comprising at least one metal compound (a) selected from the group consisting of zirconium compounds, titanium compounds, and vanadium compounds, a trivalent chromium compound (b), a polymer (C) having a carbonyl group, and a fluorine-containing compound (D). The chemical conversion treatment solution for aluminum-based metallic materials according to claim 5, wherein the mass ratio (A/B) of at least one metal element (A) selected from the group consisting of Zr, Ti and V to the Cr element (B) that is not hexavalent Cr is 0.6 to 7.0, and the mass ratio (C/B) of the C element to the Cr element (B) that is not hexavalent Cr is 0.5 to 20. The chemical conversion treatment solution for aluminum-based metallic materials according to claim 5 or 6, wherein the mass ratio (X/Y) of the mass (X) of the polymer (C) having a carbonyl group to the total mass (Y) of Zr, Ti, V and Cr is 0.50 to 2.80. A step (i) of contacting an aluminum-based metallic material with the chemical conversion treatment solution for an aluminum-based metallic material according to claim 5 or 6 for 60 seconds or more;
After the step (i), a step (ii) of washing the aluminum-based metallic material with water;
The surface treatment method of the aluminum-based metal material includes the steps of: The method for surface treatment of an aluminum-based metal material according to claim 8, wherein in step (i), the aluminum-based metal material is brought into contact with the chemical conversion treatment solution for aluminum-based metal materials for a period of 60 to 600 seconds.