JP2004218074A - Chemical conversion treatment agent and surface-treated metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical conversion treatment agent and a surface-treated metal obtained by using the same with which burdens on the environment are made less, and excellent treatment can be performed to all metals such as iron, zinc and aluminum. <P>SOLUTION: The chemical conversion treatment agent consists of at least one kind selected from the group consisting of zirconium, titanium, and hafnium, fluorine, and a water-soluble resin. The water-soluble resin has the constitution unit expressed by the formula (1) and/or the formula (2) at least in a part thereof. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

The present invention relates to a chemical conversion treatment agent and a surface-treated metal.

When a cationic electrodeposition coating or powder coating is applied to the surface of a metal material, a chemical conversion treatment is usually applied for the purpose of improving properties such as corrosion resistance and coating film adhesion. Chromate treatment, which has been used in chemical conversion treatment from the viewpoint of further improving the adhesion and corrosion resistance of the coating film, has recently been pointed out to be harmful to chromium, and a chemical treatment agent containing no chromium The development of has been required. As such a chemical conversion treatment, treatment with zinc phosphate is widely performed (for example, see Patent Document 1).

However, the zinc phosphate-based treating agent is a highly reactive treating agent having a high concentration of metal ions and acid, and therefore has poor economic efficiency and workability in wastewater treatment. Further, with the metal surface treatment with the zinc phosphate-based treating agent, salts insoluble in water are formed and precipitate as precipitates. Such a precipitate is generally called sludge, and there is a problem in that such sludge is removed and discarded, which results in cost. In addition, phosphate ions may exert a load on the environment due to eutrophication. Therefore, labor is required in treating waste liquid, and it is preferable that phosphate ions are not used. Furthermore, in the metal surface treatment using a zinc phosphate-based treating agent, it is necessary to adjust the surface, and there is a problem that the process becomes long.

As a metal surface treatment agent other than such a zinc phosphate treatment agent or a chromate conversion treatment agent, a metal surface treatment agent comprising a zirconium compound is known (for example, see Patent Document 2). Such a metal surface treating agent comprising a zirconium compound has properties superior to the above-mentioned zinc phosphate treating agents in that generation of sludge is suppressed.

However, a chemical conversion coating obtained by a metal surface treatment agent composed of a zirconium compound has poor adhesion to a coating obtained by cationic electrodeposition coating or powder coating, and is usually used as a pretreatment step for such coating. It was rarely done. In particular, in a metal surface treating agent comprising such a zirconium compound, an improvement in adhesion and an improvement in corrosion resistance have been performed by using components such as phosphate ions in combination. However, when phosphate ions are used in combination, the problem of eutrophication occurs as described above. Further, there has been no study on using such a treatment with a metal conversion treatment agent as a pretreatment method for coating. Further, when treating an iron-based substrate with such a metal surface treating agent, there is a problem that sufficient adhesion of a coating film and corrosion resistance after coating cannot be obtained.

As a metal surface treating agent containing a zirconium compound that has improved the problem of coating film adhesion as described above, a metal surface treating agent containing no zirconium compound, vanadium, and resin without phosphate ions has also been developed ( For example, see Patent Document 3). However, such a metal surface treating agent is not preferable in that it contains vanadium and causes harm to the human body and a problem of waste liquid treatment.

Further, in some cases, it is necessary to perform surface treatment of all metals in a single treatment on articles made of various metal materials such as iron, zinc, and aluminum such as automobile bodies and parts. There is a demand for the development of a chemical conversion treatment agent that can perform a chemical conversion treatment without any problem.

JP-A-10-204649 JP-A-7-310189 JP-A-2002-60699

In view of the above, the present invention provides a chemical conversion treatment agent that can perform a good chemical conversion treatment on all metals such as iron, zinc, and aluminum with a small load on the environment, and a surface obtained using the chemical conversion treatment agent. It is intended to provide a treated metal.

The present invention is a chemical conversion treating agent comprising at least one selected from the group consisting of zirconium, titanium and hafnium, fluorine, and a water-soluble resin, wherein the water-soluble resin is at least partially represented by the following formula (1);

And / or the following formula (2);

It is a chemical conversion treatment agent characterized by having a structural unit represented by:
The water-soluble resin is preferably a polyvinylamine resin or a polyallylamine resin.
The water-soluble resin preferably has a molecular weight of 500 to 500,000, and the content of the water-soluble resin in the chemical conversion treatment agent is preferably 5 to 5,000 ppm.
It is preferable that the chemical conversion treating agent has a content of at least one selected from the group consisting of zirconium, titanium, and hafnium in the range of 20 to 10000 ppm in terms of metal, and a pH of 1.5 to 6.5.

The present invention is also a surface-treated metal having a chemical conversion film formed by the chemical conversion treatment agent.
The chemical conversion film preferably has a coating amount of 0.1 to 500 mg / m ² in terms of the total amount of metals contained in the chemical conversion treatment agent.
Hereinafter, the present invention will be described in detail.

The present invention is a chemical conversion treating agent containing at least one selected from the group consisting of zirconium, titanium and hafnium, and containing fluorine and substantially free of harmful heavy metal ions such as chromium and vanadium and phosphate ions.

When a metal surface is treated with a conventionally known chemical conversion treatment agent made of zirconium or the like, a good chemical conversion film may not be formed depending on the type of metal. In particular, when the iron-based substrate is treated with the above chemical conversion treatment agent, the adhesion between the coating film and the metal surface when coating is applied on the chemical conversion film and the corrosion resistance after coating are sufficiently obtained. There was a problem that can not be. The present invention has found that the above problem can be improved by a chemical conversion treating agent containing a specific resin component, and has completed the present invention.

At least one selected from the group consisting of zirconium, titanium, and hafnium contained in the chemical conversion treatment agent is a chemical conversion film-forming component, and the substrate has a chemical conversion film containing at least one selected from the group consisting of zirconium, titanium, and hafnium. By being formed, the corrosion resistance and abrasion resistance of the base material can be improved, and further, the adhesion to the coating film can be improved.

The source of the zirconium is not particularly limited. For example, alkali metal fluorozirconates such as K ₂ ZrF ₆ ; fluorozirconates such as (NH ₄ ) ₂ ZrF ₆ ; fluorozirconates such as H ₂ ZrF ₆ Soluble zirconium fluoride; zirconium fluoride; zirconium oxide and the like.

The source of the titanium is not particularly limited. For example, alkali metal fluorotitanate, fluorotitanate such as (NH ₄ ) ₂ TiF ₆ ; soluble fluorotitanate such as fluorotitanate acid such as H ₂ TiF ₆ ; titanium fluoride A titanium oxide and the like.

The source of the hafnium is not particularly limited, and examples thereof include a fluorohafnate acid such as H ₂ HfF ₆ and hafnium fluoride.
The zirconium, the at least one source of selected from the group consisting of titanium and hafnium, _ZrF ⁶ 2-due to its high film-forming _ability, ^TiF 6 2-, at least one selected from the group consisting of _HfF ^{6 2-} Is preferred.

The content of at least one selected from the group consisting of zirconium, titanium and hafnium contained in the chemical conversion treatment agent is preferably in the range of a lower limit of 20 ppm and an upper limit of 10,000 ppm in terms of metal. If the amount is less than the above lower limit, the performance of the resulting chemical conversion film is insufficient. If the amount exceeds the above upper limit, no further effect can be expected and it is economically disadvantageous. The lower limit is more preferably 50 ppm, and the upper limit is more preferably 2000 ppm.

The fluorine contained in the chemical conversion treating agent plays a role as an etching agent for the base material. The source of the fluorine is not particularly limited, and examples thereof include fluorides such as hydrofluoric acid, ammonium fluoride, boron fluoride, ammonium hydrogen fluoride, sodium fluoride, and sodium hydrogen fluoride. . Examples of the complex fluoride include hexafluorosilicate, and specific examples thereof include hydrofluorofluoric acid, zinc hydrofluorosilicate, manganese hydrofluorosilicate, magnesium hydrofluorosilicate, and hydrofluoric acid. Nickel, iron hydrofluorosilicate, calcium hydrofluorosilicate and the like can be mentioned.

The water-soluble resin used in the chemical conversion treating agent of the present invention includes at least a part of the following formula (1);

及び/ 又は下記式（２）；

And / or the following formula (2);

It is a water-soluble resin which has a structural unit represented by these. It is considered that the chemical conversion film composed of the water-soluble resin can form a chemical conversion film having high adhesion to the metal substrate and the coating film due to the action of the amino group contained in the water-soluble resin. The method for producing the water-soluble resin is not particularly limited, and can be produced by a known method.

The water-soluble resin includes a polyvinylamine resin that is a polymer composed of only the structural unit represented by the formula (1) and a polyvinylamine resin that is a polymer composed of only the structural unit represented by the formula (2). Particularly preferred. The polyvinylamine resin and the polyallylamine resin are particularly preferable because they have an excellent effect of improving adhesion. The polyvinylamine resin is not particularly limited, and a commercially available polyvinylamine resin such as PVAM-0595B (manufactured by Mitsubishi Chemical Corporation) can be used. The polyallylamine resin is not particularly limited, and for example, a commercially available polyallylamine resin such as PAA-01, PAA-10C, PAA-H-10C, and PAA-D11HCl (all manufactured by Nitto Boseki Co., Ltd.) may be used. Can be. Further, a combination of a polyvinylamine resin and a polyallylamine resin may be used.

The water-soluble resin is modified by a method such as acetylating a part of the amino group of the polyvinylamine resin and / or the polyallylamine resin as long as the object of the present invention is not impaired. Those completely neutralized with an acid, those crosslinked with a crosslinking agent within a range that does not affect the solubility, and the like can also be used.

The water-soluble resin preferably has an amino group in a range of a lower limit of 0.01 mol and an upper limit of 2.3 mol per 100 g of the resin. If the amount is less than 0.01 mol, a sufficient effect cannot be obtained, which is not preferable. If it exceeds 2.3 mol, the intended effect may not be obtained. The lower limit is more preferably 0.1 mol.

The content of the water-soluble resin in the chemical conversion treating agent of the present invention is preferably in the range of a lower limit of 5 ppm and an upper limit of 5000 ppm in solid content. If it is less than 5 ppm, it is not preferable because a chemical conversion film having sufficient coating film adhesion cannot be obtained. If it exceeds 5000 ppm, there is a possibility that film formation may be inhibited. The lower limit is more preferably 10 ppm, and the upper limit is more preferably 500 ppm.

The water-soluble resin preferably has a molecular weight in the range of a lower limit of 500 and an upper limit of 500,000. If it is less than 500, a chemical conversion film having sufficient coating film adhesion cannot be obtained, which is not preferable. If it exceeds 500,000, film formation may be inhibited. The lower limit is more preferably 5000, and the upper limit is more preferably 70000.

It is preferable that the chemical conversion treatment agent of the present invention does not substantially contain phosphate ions. The phrase “substantially free of phosphate ions” means that phosphate ions are not contained so much as to act as a component in the chemical conversion treatment agent. Since it does not contain ions, it does not substantially use phosphorus, which causes environmental load, and generates sludge such as iron phosphate and zinc phosphate when a zinc phosphate treating agent is used. Can be suppressed.

It is preferable that the pH of the chemical conversion treatment agent is in the range of a lower limit of 1.5 and an upper limit of 6.5. If the ratio is less than 1.5, the etching becomes excessive and a sufficient film cannot be formed. If it exceeds 6.5, the etching becomes insufficient and a good film cannot be obtained. The lower limit is more preferably 2.0, and the upper limit is more preferably 5.5. The lower limit is more preferably 2.5, and the upper limit is more preferably 5.0. In order to adjust the pH of the chemical conversion treating agent, acidic compounds such as nitric acid and sulfuric acid, and basic compounds such as sodium hydroxide, potassium hydroxide and ammonia can be used.

The chemical conversion treating agent of the present invention may be used in combination with optional components, if necessary, in addition to the above components. Components that can be used include zinc ions, magnesium ions, calcium ions, aluminum ions, manganese ions, iron ions, metal ions such as cobalt ions and copper ions, silica, water-dispersible silica, silicate silicate compounds, A silicon-containing compound such as a silane coupling agent can be used.

The surface treatment of the metal with the chemical conversion treatment agent is not particularly limited, and can be performed by bringing the chemical conversion treatment agent into contact with the metal surface under ordinary treatment conditions. The treatment temperature in the chemical conversion treatment is preferably within a range of a lower limit of 20 ° C. and an upper limit of 70 ° C. The lower limit is more preferably 30 ° C., and the upper limit is more preferably 50 ° C. The chemical conversion time in the chemical conversion treatment is preferably within a range of a lower limit of 5 seconds and an upper limit of 1200 seconds. The lower limit is more preferably 30 seconds, and the upper limit is more preferably 120 seconds. The chemical conversion treatment method is not particularly limited, and examples thereof include a dipping method, a spray method, and a roll coating method.

Examples of the metal substrate treated with the chemical conversion treating agent of the present invention include an iron-based substrate, an aluminum-based substrate, and a zinc-based substrate. Iron, aluminum, and a zinc-based substrate are an iron-based substrate whose base is made of iron and / or an alloy thereof, an aluminum base whose base is made of aluminum and / or an alloy thereof, and zinc and / or Or a zinc-based substrate made of an alloy thereof. The chemical conversion treating agent of the present invention can also be used for chemical conversion treatment of an object to be coated composed of a plurality of metal bases out of an iron base, an aluminum base, and a zinc base.

The chemical conversion treating agent of the present invention, with a chemical conversion treating agent comprising ordinary zirconium or the like, imparts sufficient coating film adhesion even to an iron-based substrate where it is difficult to obtain sufficient coating film adhesion. Therefore, it has excellent properties in that it can be used particularly for treating an object to be treated containing an iron-based substrate at least in part.

The iron-based substrate is not particularly limited, and examples thereof include a cold-rolled steel sheet and a hot-rolled steel sheet. The aluminum-based substrate is not particularly limited, and examples thereof include a 5000-th aluminum alloy and a 6000-th aluminum alloy. The zinc-based substrate is not particularly limited. For example, a zinc-coated steel sheet, a zinc-nickel-coated steel sheet, a zinc-iron-plated steel sheet, a zinc-chromium-plated steel sheet, a zinc-aluminum-plated steel sheet, a zinc-titanium-plated steel sheet, zinc- Examples thereof include zinc-based electroplated steel sheets such as magnesium-plated steel sheets and zinc-manganese-plated steel sheets, hot-dip coated steel sheets, and zinc- or zinc-based alloy-plated steel sheets such as vapor-deposited plated steel sheets. Using the above chemical conversion treatment agent, iron, aluminum and zinc-based substrates can be subjected to chemical conversion treatment at the same time.

Conversion coating obtained by the chemical conversion treatment agent of the present invention, the lower limit 0.1 mg / m 2 in a total amount of metal coating weight is comprised chemical conversion treatment agent ^is preferably in the range of the upper limit 500 mg / m ^2. If it is less than 0.1 mg / m ² , a uniform chemical conversion film cannot be obtained, which is not preferable. If it exceeds 500 mg / m ² , no further effect can be obtained, which is economically disadvantageous. The lower limit is more preferably 5 mg / m ² , and the upper limit is more preferably 200 mg / m ² .

It is preferable that the surface of the metal base material be subjected to a degreasing treatment, a degreasing and water washing treatment before the chemical conversion treatment with the chemical conversion treatment agent, and a post-chemical formation water washing treatment after the chemical conversion treatment.

The degreasing treatment is performed to remove oil and dirt attached to the surface of the base material, and is usually performed at a temperature of 30 to 55 ° C. for several minutes by a degreasing agent such as a phosphorus-free and nitrogen-free degreasing cleaning solution. An immersion process is performed. If desired, a preliminary degreasing treatment can be performed before the degreasing treatment.

The post-degreasing water washing treatment is performed by spraying once or more with a large amount of washing water in order to wash the degreasing agent after the degreasing treatment with water.

The post-chemical conversion washing treatment is performed once or more so as not to adversely affect the adhesion, corrosion resistance, and the like after the subsequent coating. In this case, it is appropriate that the final washing is performed with pure water. In the post-chemical water washing treatment, either spray water washing or immersion water washing may be used, and water washing may be performed by combining these methods.
After the above-mentioned post-formation water-washing treatment, it is dried if necessary according to a known method, and thereafter, various coatings can be performed.
In addition, the chemical conversion treatment using the chemical conversion treatment agent of the present invention does not require the surface conditioning treatment that is required in the method of treating with a zinc phosphate-based chemical conversion treatment agent that has been conventionally practically used. Therefore, the chemical conversion treatment of the metal substrate can be performed in fewer steps.

The present invention is also a surface-treated metal having a chemical conversion film formed by the chemical conversion treatment agent. The surface-treated metal of the present invention is excellent in adhesion between the coating film and the metal when a coating such as cationic electrodeposition coating or powder coating is formed on the chemical conversion coating. The coating that can be performed on the surface-treated metal of the present invention is not particularly limited, and examples thereof include cationic electrodeposition coating and powder coating. Among them, iron, zinc, because it is possible to perform a good treatment on all metals such as aluminum, at least a part is preferably used as a pre-treatment of the cationic electrodeposition coating of an object to be processed composed of an iron-based substrate. Can be used. The cationic electrodeposition coating is not particularly limited, and a conventionally known cationic electrodeposition coating made of an aminated epoxy resin, an aminated acrylic resin, a sulfonium-modified epoxy resin, or the like can be applied.

The chemical conversion treatment agent of the present invention contains at least one selected from the group consisting of zirconium, titanium, and hafnium as a chemical conversion film-forming component, and further contains a water-soluble resin having a specific structure, so that conventional zirconium and the like can be used. It is possible to form a chemical conversion film having excellent coating film adhesion even on an iron-based substrate that was not suitable for pretreatment with a chemical conversion treating agent.

Since the chemical conversion treating agent used in the present invention does not substantially contain phosphate ions, the load on the environment is small and sludge is not generated. Furthermore, since the chemical conversion treatment using the chemical conversion treatment agent of the present invention does not require a surface conditioning step, the chemical conversion treatment of the metal substrate can be performed with fewer steps.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to only these Examples.

Example 1
Using a commercially available cold-rolled steel plate (SPCC-SD, manufactured by Nippon Test Panel Co., Ltd., 70 mm × 150 mm × 0.8 mm) as a base material, pre-coating treatment was performed under the following conditions.
(1) Pre-coating treatment Degreasing treatment: 2% by mass of “Surf Cleaner 53” (degreasing agent manufactured by Nippon Paint Co., Ltd.) at 40 ° C. for 2 minutes.
Rinsing treatment after degreasing: spray treatment with tap water for 30 seconds.
Chemical conversion treatment: A chemical conversion treating agent having a zirconium concentration of 100 ppm and a solid content of 100 ppm as a resin was prepared using zircon hydrofluoric acid and PVAM-0595B (polyvinylamine resin: molecular weight 70000: manufactured by Mitsubishi Chemical Corporation) as a resin. The pH was adjusted to 4 using sodium hydroxide. The temperature of the chemical conversion treatment agent was adjusted to 40 ° C., and the substrate was dipped for 60 seconds. The coating amount at the initial stage of the treatment was 10 mg / m ² .

Rinse treatment after chemical formation: spray treatment with tap water for 30 seconds. Further, spray treatment was performed for 30 seconds with ion exchanged water.
Drying treatment: The cold-rolled steel sheet after the water washing treatment was dried at 80 ° C. for 5 minutes in an electric drying oven. The amount of the film was analyzed using "XRF1700" (X-ray fluorescence spectrometer manufactured by Shimadzu Corporation) as the total amount of metals contained in the chemical conversion treatment agent.

(2) After treating a cold-rolled steel sheet of 1 m ² per 1 L of a coating chemical conversion treatment agent, electrodeposition coating was performed using “Powernics 110” (a cationic electrodeposition coating product manufactured by Nippon Paint Co., Ltd.) so as to have a dry film thickness of 20 μm. After washing with water, the plate was heated at 170 ° C. for 20 minutes and baked to prepare a test plate.

Evaluation test <Sludge observation>
After processing the cold rolled steel sheet of the chemical conversion treatment agent 1L per 1 m ^2, it was visually observed turbidity in the chemical conversion treatment agent.
〇: No cloudiness ×: Cloudy

<Secondary adhesion test (SDT)>
Two vertical parallel cuts reaching the substrate were placed in the obtained test plate, and then immersed in a 5% NaCl aqueous solution at 50 ° C. for 480 hours. Thereafter, the cut portion was tape-peeled, and the peeling of the paint was observed.
：: No peeling 〇: Slight peeling X: Peeling width 3 mm or more The evaluation results are shown in Table 1.

Example 2
A test plate was prepared in the same manner as in Example 1, except that PAA-01 (polyallylamine resin: molecular weight 1000: manufactured by Nitto Boseki Co., Ltd.) was used as the water-soluble resin, and the resin concentration was changed to 500 ppm.

Example 3
A test plate was prepared in the same manner as in Example 1 except that PAA-10C (polyallylamine resin: molecular weight: 15,000, manufactured by Nitto Boseki Co., Ltd.) was used as the water-soluble resin.

Example 4
A test plate was prepared in the same manner as in Example 1, except that PAA-H-10C (polyallylamine resin: molecular weight 60000: manufactured by Nitto Boseki Co., Ltd.) was used as the water-soluble resin, and the resin concentration was changed to 50 ppm. .

Example 5
A test plate was prepared in the same manner as in Example 1 except that the resin concentration was changed to 50 ppm using PAA-D11-HCl (polyallylamine copolymer: molecular weight 70000: manufactured by Nitto Boseki Co., Ltd.) as a water-soluble resin. Produced.

Example 6
A test plate was prepared in the same manner as in Example 1, except that the resin concentration was changed to 5 ppm using PAA-H-10C as a water-soluble resin.

Example 7
A test plate was prepared in the same manner as in Example 1, except that the zirconium concentration was changed to 500 ppm and the resin concentration was changed to 5000 ppm using PAA-01 as a water-soluble resin.

Example 8
A test plate was prepared in the same manner as in Example 1, except that the metal base was changed to a zinc-based plated steel plate (GA steel plate, manufactured by Nippon Test Panel Co., Ltd., 70 mm × 150 mm × 0.8 mm).

Example 9
A test plate was prepared in the same manner as in Example 1, except that the metal base material was changed to 5000 series aluminum (70 mm × 150 mm × 0.8 mm, manufactured by Nippon Test Panel Co., Ltd.).

Comparative Example 1
A test plate was prepared in the same manner as in Example 1, except that the water-soluble resin was not blended.

Comparative Example 2
A test plate was prepared in the same manner as in Example 1 except that zircon hydrofluoric acid was not blended.

Comparative Example 3
After degreasing and washing, the surface was adjusted at room temperature for 30 seconds using Surf Fine 5N-8M (manufactured by Nippon Paint Co., Ltd.), and surfdyne SD-6350 (a zinc phosphate chemical conversion treating agent manufactured by Nippon Paint Co., Ltd.) was used. A test plate was obtained in the same manner as in Example 1 except that the chemical conversion treatment was performed by performing the immersion treatment at 35 ° C. for 2 minutes.

Table 1 shows that no sludge is generated in the chemical conversion treating agent of the present invention. Furthermore, it was shown that the chemical conversion treating agent of the present invention forms a chemical conversion film having good coating adhesion on all metal substrates. On the other hand, in the comparative example, it was not possible to obtain a chemical conversion film which suppressed generation of sludge and also had excellent adhesion to the cationic electrodeposition coating film.

Since the chemical conversion treating agent of the present invention does not substantially use harmful heavy metal compounds such as chromium and vanadium and phosphate compounds, the load on the environment is small and sludge is not generated. In addition, it is possible to perform a good treatment on all the materials of the iron base material, the aluminum base material and the zinc base material, and to form a chemical conversion film having excellent stability as a film and excellent film adhesion. be able to. It is also excellent in that surface treatment can be performed on an object to be processed composed of a plurality of substrates such as an iron-based substrate, an aluminum-based substrate, and a zinc substrate, such as an automobile body and parts. ing.

Claims (6)

Zirconium, at least one selected from the group consisting of titanium and hafnium, fluorine, and a chemical conversion treatment agent comprising a water-soluble resin,
The water-soluble resin is at least partially represented by the following formula (1);

And / or the following formula (2);

A chemical conversion treating agent having a structural unit represented by the formula: The chemical conversion treating agent according to claim 1, wherein the water-soluble resin is a polyvinylamine resin or a polyallylamine resin. The water-soluble resin has a molecular weight of 500 to 500,000,
The chemical conversion treatment agent according to claim 1 or 2, wherein the content of the water-soluble resin in the chemical conversion treatment agent is 5 to 5000 ppm. The chemical conversion treatment agent according to claim 1, wherein the content of at least one selected from the group consisting of zirconium, titanium and hafnium is 20 to 10000 ppm in terms of metal, and the pH is 1.5 to 6.5. . A surface-treated metal having a chemical conversion film formed by the chemical conversion treatment agent according to claim 1, 2, 3, or 4. Conversion coating, surface-treated metal according to claim 5, wherein a total amount of metal coating weight is comprised chemical conversion treatment agent is 0.1 to 500 mg / ^{m 2.}