JP2018104759A - Metal surface treatment composition and metal surface treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for metal surface treatment which is substantially free of fluorine and can form a stable chemical conversion film. SOLUTION: This is a composition for metal surface treatment which is used for surface treatment of a metal and is substantially free of chromium and fluorine, and is a zirconium compound (A) which is substantially free of fluorine and an amphoteric metal compound (B). ), At least one of the monocarboxylic acid and its salt (C), the pH is 3 to 5, and the zirconium derived from the zirconium compound (A) is compared with the amphoteric metal derived from the amphoteric metal compound (B). A composition for metal surface treatment having a molar ratio of 1 to 10. [Selection diagram] None

Description

  The present invention relates to a metal surface treatment composition used for metal surface treatment and a metal surface treatment method for treating a metal surface.

  In general, when coating an object to be treated, a surface treatment is performed from the viewpoint of ensuring corrosion resistance and adhesion of a coating film. In particular, when coating a metal (metal material, metal structure), a chemical conversion treatment (surface treatment) for chemically forming a chemical conversion film on the metal surface is performed.

  As an example of the chemical conversion treatment, there is a chromate chemical conversion treatment with chromate. However, harmfulness due to chromium has been pointed out. In recent years, treatment agents that do not contain chromium (surface treatment agents, chemical conversion treatment agents). For example, treatment with a zinc phosphate-based treating agent (zinc phosphate treatment) is widely performed (see, for example, Patent Document 1).

  However, since the zinc phosphate-based treating agent is a highly reactive treating agent having a high metal ion and acid concentration, the economical efficiency and workability in wastewater treatment are not good. In addition, phosphate ions have a high impact on the environment due to eutrophication, and labor is required for the treatment of waste liquid.

As a treatment agent other than such a zinc phosphate-based treatment agent or a chromate chemical conversion treatment agent, a chemical conversion treatment agent containing a zirconium compound is known (for example, see Patent Document 2). Since the zirconium compound described in Patent Document 2 does not substantially contain fluorine, it is easy to handle and can reduce the burden on the environment.
Japanese Patent Laid-Open No. 10-204649 International Publication No. 2007/100018

  However, in the zirconium compound substantially not containing fluorine, the zirconium element may become unstable in the chemical conversion liquid. Therefore, there is room for improvement so that a more stable chemical conversion liquid can be adjusted.

  An object of this invention is to provide the composition for metal surface treatment which can form a favorable chemical conversion film substantially not containing a fluorine.

  The present invention is a metal surface treatment composition that is used for metal surface treatment and does not substantially contain chromium and fluorine, and a zirconium compound (A) that does not substantially contain fluorine, and an amphoteric metal compound (B). ) And at least one of monocarboxylic acids and salts thereof (C), having a pH of 3 to 5, and derived from the zirconium compound (A) with respect to the amphoteric metal derived from the amphoteric metal compound (B) The zirconium molar ratio relates to a metal surface treatment composition having a molar ratio of 1-10.

  The amphoteric metal compound (B) preferably contains an aluminum compound or a zinc compound.

  The amphoteric metal compound (B) is preferably at least one selected from the group consisting of aluminum nitrate, aluminum acetate, zinc nitrate and zinc acetate.

  The monocarboxylic acid is preferably at least one selected from the group consisting of acetic acid, propionic acid, butanoic acid and benzoic acid.

  The zirconium compound (A) preferably contains at least one of zirconium nitrate and zirconium acetate.

  Moreover, it is preferable that the molar ratio of at least one (C) among the said monocarboxylic acid and its salt with respect to the amphoteric metal derived from the said amphoteric metal compound (B) is 1-100.

  The present invention also relates to a metal surface treatment method for treating a metal surface, the method comprising a contact step of bringing the metal surface treatment composition into contact with the metal.

Moreover, it is preferable to form the chemical conversion film by 30-100 mg / m < ² > of the said metal surface treatment composition by the said contact process on the metal surface.

  ADVANTAGE OF THE INVENTION According to this invention, the composition for metal surface treatment which can form a stable chemical conversion film substantially not containing a fluorine can be provided.

  Hereinafter, the metal surface treatment composition, metal surface treatment method, and metal material of the present embodiment will be described in detail.

<Composition for metal surface treatment>
The metal surface treatment composition according to the present embodiment is used for metal surface treatment and substantially does not contain chromium and fluorine. Therefore, handling of the metal surface treatment composition is easy, and the burden on the environment can be reduced. Further, the metal surface treatment composition according to this embodiment is used for metal surface treatment, and includes at least one of a zirconium compound (A), an amphoteric metal compound (B), a monocarboxylic acid and a salt thereof. On the other hand, (C) is included.

In the present specification, “substantially not containing chromium” means that chromium ions are not contained in the treatment liquid to such an extent that they act as components in the metal surface treatment composition (treatment liquid). Specifically, this means that the chromium-containing compound is not intentionally used as a raw material. As an example, the measured value of the chromium element concentration is 1000 ppm (value specified by the RoHS directive in each EU country) or less. This is the case.
In the present specification, “substantially free of fluorine” means that fluorine ions are not contained in the treatment liquid to such an extent that they act as components in the metal surface treatment composition (treatment liquid). As an example, it means a case where the measured value of the fluorine element concentration using an ion chromatograph or the like is 10 ppm or less.

  Moreover, the metal surface treatment composition according to the present embodiment is diluted and adjusted with water to form a metal surface treatment liquid, which is used for metal surface treatment.

[Zirconium compound (A)]
The zirconium element contained in the zirconium compound (A) according to this embodiment is a main component that forms a chemical conversion film. By forming a chemical conversion film containing zirconium on the metal material, the corrosion resistance and adhesion of the metal material can be improved.

Conventionally, a metal surface treatment composition containing a fluorine element such as K ₂ ZrF ₆ , (NH ₄ ) ₂ ZrF ₆ has been used, but the zirconium compound (A of the metal surface treatment composition according to this embodiment) ) Is substantially free of fluorine.

  When the surface treatment of the metal material is performed with the metal surface treatment composition containing the zirconium compound (A) according to the present embodiment, a dissolution reaction of the metal constituting the metal material occurs. When the dissolution reaction of the metal occurs, it is considered that a hydroxide or oxide of zirconium is generated and precipitated on the surface of the metal material by increasing the pH of the interface. And the adhesiveness of a chemical conversion film and the coating film formed on the surface becomes favorable by presence of the Zr-O bond and / or Ti-O bond derived from this hydroxide or oxide of zirconium.

The zirconium compound (A) is not particularly limited, but zirconium nitrate, nitrite, sulfate, sulfite, chloride, bromide, oxide, hydroxide, peroxide, carbonate, etc. Can be mentioned. The zirconium compound (A) is preferably a compound containing an acid so that the pH in the metal surface treatment solution is 3 to 5, but is adjusted with an acid or a base so that the pH is within this range. Also good.
More specific examples of the zirconium compound (A) include zirconium nitrate, zirconium acetate, zirconium chloride, and ammonium zirconium carbonate. Among these, from the viewpoint of forming a chemical conversion film, the zirconium compound (A) according to the present embodiment preferably includes at least one of zirconium nitrate and zirconium acetate.

[Amphoteric metal compound (B)]
The amphoteric metal element contained in the amphoteric metal compound (B) according to the present embodiment is a component that forms a chemical conversion film together with zirconium. The amphoteric metal element and the carboxylic acid contribute to stabilizing the zirconium compound (A) containing no fluorine in the metal surface treatment composition as described later. Thereby, a chemical conversion film having excellent corrosion resistance and adhesion can be formed on the metal material.

  The amphoteric metal compound according to the present embodiment is a compound that forms an acid salt with respect to a base and a basic salt with respect to an acid. Specifically, the amphoteric metal element compound is a compound of aluminum, zinc, tin or lead. Among these, since the burden on the environment can be further reduced, the amphoteric metal compound according to the present embodiment preferably contains an aluminum compound or a zinc compound.

Examples of the aluminum compound include aluminum nitrate, aluminum acetate, and aluminum chloride. Examples of the zinc compound include zinc nitrate, zinc acetate, and zinc chloride.
Among these, the amphoteric metal compound according to the present embodiment is selected from the group consisting of aluminum nitrate and aluminum acetate as an aluminum compound, zinc nitrate and zinc acetate as a zinc compound, in order to more effectively exhibit corrosion resistance. It is preferable that it is at least one kind.

[At least one of monocarboxylic acid and its salt (C)]
Further, at least one (C) of the monocarboxylic acid and the salt thereof contained in the metal surface treatment composition according to the present embodiment stabilizes the zirconium element in the chemical conversion liquid together with the amphoteric metal compound (B). it is conceivable that. This is because it is considered that at least one (C) of the monocarboxylic acid and the salt thereof is contained in the chemical conversion liquid, so that the zirconium element and the amphoteric metal element form a composite chelate. For this reason, it is considered that the zirconium compound (A) is stabilized by the chemical conversion liquid even if it does not substantially contain fluorine.

Examples of the monocarboxylic acid or a salt thereof include acetic acid, sodium acetate, propionic acid, butanoic acid, benzoic acid, and isopropionic acid.
Among these, the monocarboxylic acid according to the present embodiment is preferably at least one selected from the group consisting of acetic acid, propionic acid, butanoic acid and benzoic acid in order to further improve the stability of the chemical conversion liquid.

[Ratio of zirconium compound (A) / amphoteric metal compound (B) / monocarboxylic acid (C)]
In the metal surface treatment composition according to the present embodiment, the zirconium compound (A), the amphoteric metal compound (B), and at least one of the monocarboxylic acid and its salt (C) are the zirconium compound (A) and The amphoteric metal compound (B) is preferably adjusted in a range capable of forming a complex chelate. Specifically, the molar ratio of zirconium to the amphoteric metal is preferably 1 to 10, and more preferably 1 to 2. When the molar ratio is less than 1, it becomes difficult to form a chemical conversion film mainly composed of zirconium due to the lack of zirconium, and when the molar ratio exceeds 10, the formation of the composite chelate is insufficient due to the lack of amphoteric metal elements. It becomes difficult.

  In this specification, the number of moles of the zirconium compound (A) means the number of moles of zirconium derived from the zirconium compound (A), and the number of moles of the amphoteric metal compound (B) means the amphoteric metal compound (B ) Means the number of moles of amphoteric metal derived from.

  In addition, the molar ratio of at least one of the monocarboxylic acid and its salt to the amphoteric metal is preferably 1 to 100, and more preferably 5 to 10. When the molar ratio is less than 1, the formation of a composite chelate becomes difficult due to the lack of components derived from monocarboxylic acid, and when the molar ratio exceeds 100, a chemical conversion film is formed due to an excess of components derived from monocarboxylic acid. It becomes difficult to do.

[Inorganic acid or salt thereof]
Moreover, it is thought that the inorganic acid or its salt contained in the composition for metal surface treatment which concerns on this embodiment accelerates | stimulates the formation reaction of a chemical conversion film as an oxidizing agent. Examples of the inorganic acid include nitric acid, nitrous acid, hydrochloric acid, bromic acid, chloric acid, hydrogen peroxide, HMnO ₄ and HVO ₃ . In addition, you may make it a metal surface treatment composition contain a sulfonic acid group containing compound or these salts as an oxidizing agent.

[PH of metal surface treatment composition]
The pH of the metal surface treatment composition according to the present embodiment is preferably 3 to 5, and more preferably 3 to 4. If the pH is less than 3, etching may be excessive and a sufficient chemical conversion film may not be formed, or the chemical conversion film may be non-uniform and adversely affect the appearance of the coating. On the other hand, if the pH exceeds 5, etching becomes insufficient and a good chemical conversion film cannot be obtained.

  In addition, pH of the composition for metal surface treatment can be adjusted using basic compounds, such as acidic compounds, such as nitric acid and a sulfuric acid, and sodium hydroxide, potassium hydroxide, ammonia.

[Surfactant]
In addition, the metal surface treatment composition according to the present embodiment includes at least one surfactant selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants. May further be included. As the nonionic surfactant, the anionic surfactant, the cationic surfactant and the amphoteric surfactant, conventionally known ones can be used. When the composition for metal surface treatment used in the present embodiment contains these surfactants, a good chemical conversion film can be formed without degreasing and cleaning the metal material in advance. .

[Metal elements]
The metal surface treatment composition according to the present embodiment may further contain a metal element other than zirconium and an amphoteric metal capable of imparting adhesion and corrosion resistance to the coating film. Examples of such metal elements include magnesium, calcium, gallium, indium, copper, iron, manganese, nickel, cobalt, cerium, strontium, rare earth elements, and silver.

[Other additives]
In order to further improve the coating film adhesion, a silane coupling agent such as organosiloxane and organosilane, and other silane compounds may be contained.

<Metal surface treatment method>
The metal surface treatment method for performing the metal surface treatment of the present embodiment is not particularly limited, and the metal surface treatment liquid containing the metal surface treatment composition according to the present embodiment is brought into contact with the metal (metal material). Can be done.

[Metal material]
Although the metal material (metal which makes the metal surface treatment composition contact) used in the metal surface treatment method according to the present embodiment is not particularly limited, examples thereof include a steel plate and an aluminum plate. The steel plate includes a cold-rolled steel plate, a hot-rolled steel plate, a mild steel plate, a high-tensile steel plate, and the like, and is not particularly limited. For example, an iron-based metal material, an aluminum-based metal material, a zinc-based metal material, and a magnesium-based steel A metal material etc. can be mentioned.
The iron-based metal material means a metal material made of iron or an alloy thereof. An aluminum-based metal material means a metal material made of aluminum or an alloy thereof. A zinc-based metal material means a metal material made of zinc or an alloy thereof. The magnesium-based metal material means a metal material made of magnesium or an alloy thereof.

[Pretreatment of metal materials]
The metal material according to this embodiment is preferably cleaned by a degreasing process. Furthermore, it is preferable that the metal material of this embodiment is degreased and then washed with water. These degreasing treatments and water washing treatments are performed to remove oil and dirt adhering to the surface of the metal material, and are usually 30 ° C to 55 ° C with a degreasing agent such as a phosphorus-free and nitrogen-free degreasing cleaning solution. Is immersed for about several minutes. If desired, a preliminary degreasing process can be performed before the degreasing process. Moreover, it is preferable that the washing process after a degreasing process is performed by a spray process at least once or more with a large amount of washing water in order to wash a degreasing agent.

  In addition, when the composition for metal surface treatment contains surfactant, a favorable chemical conversion film can be formed even if it does not degrease and clean a metal material beforehand. That is, in this case, the degreasing treatment of the metal material is performed at the same time in the treatment liquid contact step.

[Contact process]
The contact process according to the present embodiment is a process of bringing a metal surface treatment liquid containing a metal surface treatment composition into contact with a metal material. As an example of the processing method in a contact process, the immersion method, the spray method, the roll-coating method, the pouring process method etc. can be mentioned.

  The contacting step is preferably performed at a processing temperature of 10 ° C. or higher and 70 ° C. or lower. If it is less than 10 ° C, there is a possibility that a sufficient chemical conversion film may not be formed, and there is a disadvantage that temperature adjustment is required in summer. Will be reduced and will be economically disadvantageous. The treatment temperature is more preferably in the range of 20 ° C. or more and 50 ° C. or less.

  The contact step is preferably performed at a treatment time of 5 seconds or more and 1100 seconds or less. If it is less than 5 seconds, a sufficient chemical conversion film is not formed, which is inconvenient. If it exceeds 1100 seconds, even if a chemical conversion film longer than this is formed, the effect cannot be obtained, which is meaningless. The treatment time is more preferably in the range of 60 seconds to 120 seconds.

  The metal surface treatment method according to the present embodiment does not require the surface adjustment treatment as compared with the treatment with a zinc phosphate-based chemical conversion treatment solution that has been practically used. For this reason, it becomes possible to perform the chemical conversion treatment of the metal material with fewer steps.

  Moreover, the metal surface treatment method according to the present embodiment can also be subjected to electrolytic treatment using a metal material as a cathode. In this case, a reduction reaction of hydrogen occurs at the metal material interface which is the cathode, and the pH rises. As the pH rises, the stability of the compound containing zirconium element at the cathode interface decreases, and a surface-treated chemical conversion film is deposited as an oxide or a hydroxide containing water.

It is preferable to form a chemical conversion film with a metal surface treatment composition of 30 to 100 mg / m ^{2 on} the metal surface by the contact step according to the present embodiment, and with a metal surface treatment composition of 40 to 70 mg / m ^2. More preferably, a chemical conversion film is formed. When the chemical conversion film by the metal surface treatment composition is less than 30 mg / m ² , it may be difficult to form a uniform chemical conversion film on the metal material and obtain good adhesion. On the other hand, when the chemical conversion film by the composition for metal surface treatment exceeds 100 mg / m < ² >, coating-film adhesiveness will fall.

[Metal material post-treatment]
The metal material on which the chemical conversion film is formed by the metal surface treatment method according to the present embodiment is preferably subjected to a water washing treatment before the coating film formation to be performed thereafter. That is, the metal surface treatment method according to the present embodiment includes a contact step of bringing a metal surface treatment liquid containing a metal surface treatment composition into contact with the metal material, and a water washing step of washing the metal material that has undergone the contact step. Including. By performing the water washing treatment before forming the coating film, impurities on the surface of the chemical conversion film are removed, so that the adhesion with the coating film can be further improved and good corrosion resistance can be imparted.

  In the water washing treatment after the surface treatment, the final water washing is preferably performed with pure water. In the water washing treatment after the surface treatment, either spray water washing or immersion water washing may be used, and these methods may be combined for water washing.

  After performing a water washing treatment after the surface treatment, it may be dried as necessary according to a known method. However, when a chemical conversion film is formed by the metal surface treatment method according to the present embodiment, a drying treatment is performed after the water washing treatment. Can be painted without. That is, a wet and wet coating method can be adopted as a coating method after the chemical conversion film is formed by the metal surface treatment method according to the present embodiment. Therefore, the metal surface treatment method according to the present embodiment can be applied to metal materials before electrodeposition coating, in particular, vehicle exteriors and various parts such as automobile bodies and motorcycle bodies before electrodeposition coating, machine tools, and home appliances. It is possible to shorten the surface treatment process of the general industrial member and the like.

[Coating film formed thereafter]
After forming the chemical conversion film by the metal surface treatment method according to the present embodiment, examples of the coating film formed on the chemical conversion film include conventionally known paints such as electrodeposition paints, solvent paints, aqueous paints, and powder paints. The coating film formed by can be mentioned.

  After the water washing step of washing the metal material that has undergone the contact step of bringing the metal surface treatment liquid containing the metal surface treatment composition according to the present embodiment into contact with the metal material, or after the contact and electrolytic treatment, the metal material is The polymer-containing liquid containing at least one of a water-soluble polymer compound and a water-dispersible polymer compound may be contacted. That is, in the metal surface treatment method according to the present embodiment, after the water washing step of washing the metal material that has undergone the contact step, the metal material contains at least one of a water-soluble polymer compound and a water-dispersible polymer compound. A polymer-containing liquid contact step in which the molecule-containing liquid is brought into contact may be included. Thereby, corrosion resistance can further be improved.

  The water-soluble polymer compound and the water-dispersible polymer compound are not particularly limited. For example, polyvinyl alcohol, poly (meth) acrylic acid, a copolymer of acrylic acid and methacrylic acid, ethylene and (meth) acrylic acid , Copolymers with acrylic monomers such as (meth) acrylates, copolymers of ethylene and vinyl acetate, polyurethane, amino-modified phenol resins, polyester resins, epoxy resins, tannins, tannic acid and salts thereof, Examples thereof include silane compounds such as phytic acid, organosiloxane, and organosilane.

  As described above, the metal surface treatment composition in the present embodiment is a metal surface treatment composition that is used for metal surface treatment and does not substantially contain chromium and fluorine, and substantially contains fluorine. Contains no zirconium compound (A), amphoteric metal compound (B), at least one of monocarboxylic acid and its salt (C), has a pH of 3-5, and amphoteric metal compound (B) The molar ratio of the zirconium derived from the zirconium compound (A) to the derived amphoteric metal is 1-10. It is considered that the zirconium element and the amphoteric metal element form a composite chelate when at least one (C) of the monocarboxylic acid and its salt is contained in the chemical conversion liquid. Therefore, the zirconium compound (A) is stabilized in the chemical conversion liquid even if it does not substantially contain fluorine. Thereby, a stable chemical conversion liquid can be formed which does not substantially contain fluorine. Moreover, a stable chemical conversion film can be formed by such chemical conversion liquid.

  The amphoteric metal compound (B) contains an aluminum compound or a zinc compound, and is at least one selected from the group consisting of aluminum nitrate, aluminum acetate, zinc nitrate and zinc acetate. Thereby, a composite film with zirconium is formed, and the corrosion resistance can be further improved.

  The monocarboxylic acid is at least one selected from the group consisting of acetic acid, propionic acid, butanoic acid and benzoic acid. Thereby, stability of a chemical conversion liquid can be improved more.

  The zirconium compound (A) contains at least one of zirconium nitrate and zirconium acetate. Thereby, a chemical conversion film can be formed more uniformly.

  The molar ratio of at least one of the monocarboxylic acid and the salt thereof to the amphoteric metal derived from the amphoteric metal compound (B) is 1-100. Thereby, a more stable chemical conversion film can be formed.

  Moreover, the metal surface treatment method in this embodiment is a metal surface treatment method for treating the surface of a metal (metal material), and includes a contact step of bringing the metal surface treatment composition into contact with the metal. Thereby, a stable chemical conversion film substantially free of fluorine can be formed on the metal surface.

Moreover, a chemical conversion film by the metal surface treatment composition of 30-100 mg / m < ² > is formed on the surface of a metal by a contact process. Thereby, a more stable chemical conversion film can be formed on the metal surface.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited only to these Examples.

<Example 1>
Zirconium nitrate was used as the zirconium compound contained in the metal surface treatment composition. Moreover, aluminum nitrate was used as the aluminum compound. As acetic acid, 98% acetic acid was used. Moreover, sodium nitrate was used as an inorganic acid component. Each of these compositions was diluted and adjusted to have the ratio and pH shown in Table 1 to obtain a metal surface treatment liquid of Example 1. A 20% sodium hydroxide solution was used as a pH adjuster.

<Examples 2 to 24>
In the same manner as in Example 1, each composition shown in Table 1 was diluted and adjusted so that the ratio and pH shown in Table 1 were obtained, to obtain metal surface treatment liquids of Examples 2 to 24.

<Comparative Examples 1-3>
Without using the monocarboxylic acid and its salt, each composition shown in Table 1 was diluted and adjusted to the ratio and pH shown in Table 1 to obtain metal surface treatment liquids of Comparative Examples 1 to 3. .

<Comparative Examples 4-7>
Each composition shown in Table 1 has the ratio and pH shown in Table 1 so that the molar ratio of zirconium derived from the zirconium compound (A) to the amphoteric metal derived from the amphoteric metal compound (B) is 50. The metal surface treatment liquids of Comparative Examples 4 and 5 were obtained by dilution and adjustment.
The ratio, pH, and ratio shown in Table 1 for each composition shown in Table 1 so that the molar ratio of zirconium derived from the zirconium compound (A) to the amphoteric metal derived from the amphoteric metal compound (B) is 0.5. It diluted and adjusted so that the metal surface treatment liquid of Comparative Examples 6 and 7 was obtained.

<Comparative Examples 8-13>
Without using the amphoteric metal compound (B), the compositions shown in Table 1 were diluted and adjusted to the ratio and pH shown in Table 1 to obtain metal surface treatment solutions of Comparative Examples 8 to 13. .
In Comparative Examples 10 to 13, not the amphoteric metal compound (B) but calcium nitrate (Comparative Example 10), magnesium nitrate (Comparative Example 11), iron nitrate (Comparative Example 12), and manganese nitrate (Comparative Example 13). Each was used.

<Comparative Examples 14-17>
Without using the amphoteric metal compound (B), the monocarboxylic acid and its salt, each composition shown in Table 1 was diluted and adjusted to the ratio and pH shown in Table 1, and Comparative Examples 14 to 17 metal surface treatment solutions were obtained.
In Comparative Examples 14 to 17, not monocarboxylic acid and its salt but sodium sulfate (Comparative Example 14), trisodium phosphate (Comparative Example 15), aspartic acid (Comparative Example 16), etidronic acid (Comparative Example 17) ) Were used.

<Comparative Examples 18 and 19>
Comparative examples were prepared by diluting and adjusting the compositions shown in Table 1 to the ratio shown in Table 1 so that the pH was 2.0 (Comparative Example 18) or 5.5 (Comparative Example 19). 18 and 19 metal surface treatment solutions were obtained.

  In addition, the fluorine compound was not substantially contained in the zirconium compound (A) of the metal surface treatment liquid of each Example and a comparative example. Further, the metal surface treatment liquids of the examples and comparative examples were substantially free of chromium and fluorine.

<Liquid state>
After leaving each metal surface treatment liquid of an Example and a comparative example for 1 hour, the liquid state was visually evaluated on the following evaluation criteria. The results are shown in Table 1.
(Evaluation criteria)
1: Transparent 2: Translucent 3: White turbidity As shown in Table 1, in all Examples, no white turbidity was observed in the metal surface treatment liquid.

  Then, the steel plate (metal material) shown in Table 2 was degreased for 120 seconds at 40 ° C. using a “surf cleaner 53NF” 2% diluted solution manufactured by Nippon Paint. With respect to the degreased steel sheet, the metal surface treatment agents of the examples and comparative examples were treated by the dipping method at the treatment times and treatment temperatures shown in Table 2 to obtain the metal materials of the examples and comparative examples.

<Coating state>
The state of the coating film was evaluated by the following evaluation tests for each of the metal materials of Examples and Comparative Examples. The comparative examples other than Comparative Examples 2, 6, 7, 8, and 18 shown in Table 2 were excluded from the following evaluation tests because no chemical conversion film was formed on the surface of the metal material.

<Metal conversion coating amount>
The amount of coating formed on the metal material was measured with a fluorescent X-ray tester, and the results are shown in Table 2.
As shown in Table 2, a sufficient coating film (chemical conversion film) of about 30 to 100 mg / m ² was obtained in all examples except Example 23. In addition, the metal material of Example 23 and the metal material of Example 24 in which a sufficient coating film was obtained were obtained by treating the same metal surface treatment liquid with the same metal material at different treatment times. It was considered that a sufficient coating film (chemical conversion film) of about 30 to 100 mg / m ² could be obtained by bringing the metal surface treatment liquid of Example 23 into contact with the metal material at different treatment times.

<Corrosion resistance>
For each metal material, a cross cut reaching the substrate was made, and then a 5% NaCl aqueous solution was continuously sprayed for 960 hours in a salt spray tester maintained at 35 ° C. Thereafter, the peel width from the cut portion was measured, the corrosion resistance was evaluated according to the following evaluation criteria, and the results are shown in Table 2.
1: Less than 3 mm peeling width 2: More than 3 mm peeling width As shown in Table 2, high corrosion resistance was confirmed in all Examples.

<Adhesion>
About the coating test piece, the cross-cut peeling test was done according to JIS-K-5600 5.6. 100 squares of 1 mm square were prepared, a peel test was performed using a cellophane adhesive tape, the number of grids not peeled off was counted, the corrosion resistance was evaluated according to the following evaluation criteria, and the results are shown in Table 2.
1: 100/100 and no peeling 2: Even one piece was peeled As shown in Table 2, high adhesion was confirmed in all examples except Example 23. In addition, the metal material of Example 24 in which high adhesion with the metal material of Example 23 was confirmed was obtained by treating the same metal surface treatment liquid with the same metal material at different treatment times. It was thought that a coating film (chemical conversion film) having high adhesion could be obtained by bringing the metal surface treatment solution of 23 into contact with the metal material for different treatment times.

Claims (8)

A metal surface treatment composition which is used for metal surface treatment and does not substantially contain chromium and fluorine,
A zirconium compound (A) substantially free of fluorine;
An amphoteric metal compound (B);
Containing at least one of monocarboxylic acid and its salt (C),
pH is 3-5,
The metal surface treatment composition wherein the molar ratio of zirconium derived from the zirconium compound (A) to the amphoteric metal derived from the amphoteric metal compound (B) is 1 to 10.   The composition for metal surface treatment according to claim 1, wherein the amphoteric metal compound (B) contains an aluminum compound or a zinc compound.   The metal surface treatment composition according to claim 1 or 2, wherein the amphoteric metal compound (B) is at least one selected from the group consisting of aluminum nitrate, aluminum acetate, zinc nitrate, and zinc acetate.   The metal surface treatment composition according to claim 1, wherein the monocarboxylic acid is at least one selected from the group consisting of acetic acid, propionic acid, butanoic acid, and benzoic acid.   The metal surface treatment composition according to any one of claims 1 to 4, wherein the zirconium compound (A) contains at least one of zirconium nitrate and zirconium acetate.   The metal surface treatment composition according to any one of claims 1 to 5, wherein a molar ratio of at least one of the monocarboxylic acid and a salt thereof to the amphoteric metal derived from the amphoteric metal compound (B) is 1 to 100. . A metal surface treatment method for treating a metal surface,
A metal surface treatment method comprising a contact step of bringing the metal surface treatment composition according to claim 1 into contact with the metal. The metal surface treatment method according to claim 7, wherein a chemical conversion film of 30 to 100 mg / m ² of the metal surface treatment composition is formed on the metal surface by the contact step.