EP3006600B1

EP3006600B1 - Supplement and production method for surface-treated metal material

Info

Publication number: EP3006600B1
Application number: EP13886009.3A
Authority: EP
Inventors: Satoshi Kawai; Yoshiyuki KAWADE
Original assignee: Nihon Parkerizing Co Ltd
Current assignee: Nihon Parkerizing Co Ltd
Priority date: 2013-05-28
Filing date: 2013-05-28
Publication date: 2018-12-19
Anticipated expiration: 2033-05-28
Also published as: CN105378144B; US20160186351A1; JP6055915B2; PH12015502678A1; KR101726536B1; JPWO2014192082A1; WO2014192082A1; CN105378144A; EP3006600A1; EP3006600A4; KR20160003134A

Description

TECHNICAL FIELD

The present invention relates to a replenisher and a method for producing a surface-treated metallic material.

BACKGROUND ART

In order to impart functions, such as paint adhesion, corrosion resistance after painting and unpainted corrosion resistance, to metallic material products, a surface thereof is normally subjected to a chemical conversion treatment including phosphate treatment and chromate treatment depending on its application.
Recently, however, interests in reducing environmental loads have been increasing, and studies for reducing industrial wastes such as phosphate sludge have been conducted and the compliance with regulations on the restriction of the use of hexavalent chromium have been taken, and a chemical conversion coating using a zirconium compound and the like is proposed as a new coating treatment to replace the phosphate treatment or the chromate treatment (Patent Literature 1 and Patent Literature 2). More specifically, by performing chemical conversion treatment and/or electrolysis treatment (for example, cathodic electrolysis and the like) on/over a metallic material in metallic material surface treating solution containing zirconium (hereinafter, also referred to as Zr) ion and fluorine (hereinafter, also referred to as F) ion, a zirconium-based chemical conversion coating (hereinafter, also referred to simply as coating) can be formed on/over the surface of the metallic material, thereby imparting excellent performance to the surface of the metallic material.
When coatings are continuously produced through the above-described surface treatment for metallic materials, zirconium ion in the metallic material surface treating solution is consumed while being converted into oxides and deposited as the coatings, whereby the zirconium ion concentration in the metallic material surface treating solution gradually decreases. In the meantime, an amount of fluorine ion that is taken into the coatings is smaller than that of zirconium ion so that a decrease in the fluorine ion concentration in the metallic material surface treating solution per unit area is smaller than that of the zirconium ion concentration.
More specifically, H₂ZrF₆ is often used in the metallic material surface treating solution containing zirconium ion, and the reaction formula thereof is as shown below.

H₂ZrF₆ + 2H₂O -> ZrO_2↓ + 6HF ··· Formula (1)
At the interface between a metallic material and the metallic material surface treating solution, acid consumption due to etching, reduction of hydrogen ion near a cathode electrode and the like raise the pH near the metallic material, hydrolysis of H₂ZrF₆ is caused as indicated by Formula (1), and a zirconium-based coating includes zirconium oxide or the like is formed on/over the surface of the metallic material.
Regarding fluorine ion, on the other hand, as shown in Formula (1), generation of one mole of ZrO₂ theoretically causes 6 moles of HF to be produced as a by-product in the metallic material surface treating solution. Compared to Zr that is the main component of the coating, the amount of HF taken into the coating is so small that, when metallic surface treatment is continuously performed, HF accumulates in the metallic material surface treating solution, increasing the concentration thereof. Since HF is shown in the right side of the Formula (1), if the HF concentration increases, the reaction to generate coating is inhibited, making it difficult to properly produce coating of the zirconium compound. In addition, when the zirconium ion concentration decreases, zirconium ion needs to be supplied. For that purpose, H₂ZrF₆ is normally supplied, but because of this ratio between zirconium ion and fluorine ion, accumulation of HF cannot be inhibited. Accordingly, in order to inhibit accumulation of HF, the method in which part of the metallic material surface treating solution is automatically drained (auto-drained) during continuous operation to keep the HF concentration constant has been conventionally adopted in many cases. However, in the environmental and economical point of view, it is not preferable to auto-drain the solution containing a large amount of zirconium ion or HF into drainage water in spite of the fact that the coatings with reduced environmental loads have been proposed, and thus improvements are desired.
Accordingly, Patent Literature 3 proposes that the above-described problem can be solved by replenishing the metallic material surface treating solution with zirconium ion in such an amount that the balance with the amount of supplied fluorine ion is taken into consideration using a replenisher containing a fluorine-containing zirconium compound and a fluorine-free zirconium compound. In particular, Patent Literature 3 discloses in paragraph [0033] that replenishment of Zr ion was performed by using a mixed solution of hexafluorozirconic acid and zirconium nitrate (weight ratio of hexafluorozirconic acid:zirconium nitrate = 55:45) having the Zr ion concentration of 17g/L.
US 2011/083580 A1 describes replenisher compositions and methods of replenishing pretreatment compositions. The methods include adding a replenisher composition to a pretreatment composition wherein the replenisher composition includes: (a) a dissolved complex metal fluoride ion wherein the metal ion comprises a Group IIIA metal, Group IVA metal, Group IVB metal, or combinations thereof; (b) a component comprising an oxide, hydroxide, or carbonate of Group IIIA, Group IVA, Group IVB metals, or combinations thereof; and optionally (c) a dissolved metal ion comprising a Group IB metal, Group IIB metal, Group VIIB metal, Group VIII metal, Lanthanide Series metal, or combinations thereof.
JP 2009 084623 A relates to the problem to provide a method for manufacturing a steel sheet covered with a conversion treatment film, which is a steel strip covered with a conversion treatment film obtained by continuously and cathodically electrolyzing the steel strip in a treatment solution that contains Zr fluoride ions, while stably supplying Zr ions to the treatment solution. As a solution to the problem, the document describes that the treatment solution contains the Zr ions in an amount of 0.05 to 30 g/L, and fluorine ions in an amount of 0.5 to 10 times that of Zr ions. The manufacturing method includes supplying the Zr ions to the treatment solution with the use of two or more types of Zr compounds selected from the group consisting of a Zr halide, Zr hydroxide, Zr carbonate, a Zr ammoniate, Zr nitrate, Zr sulfate and Zr acetate, in cathodic electrolysis treatment. The treatment solution contains the ions originating in the selected two or more types of the Zr compounds in an amount of 10 times of Zr ions or less, respectively.

CITATION LIST

PATENT LITERATURE

[Patent Literature 1] JP 2008-202149 A
[Patent Literature 2] JP 2010-90407 A
[Patent Literature 3] JP 4996409 B

SUMMARY OF INVENTION

TECHNICAL PROBLEMS

Meanwhile, a replenisher used to replenish the metallic material surface treating solution with zirconium ion is usually stored for a long time in a storehouse or the like after purchase. Hence, the replenisher has to be in a usable condition after a long-term storage. In particular, it is required that, when the replenisher is stored in the high-temperature environment for a long period of time, precipitation or the like not occur in the replenisher.
The inventors of the present invention studied storage stability of the replenisher specifically described in Patent Literature 3 and found that the storage stability thereof was not at the recent satisfactory level, and further improvements were necessary.
Moreover, in the recent years, cost reduction for the coating treatment is desired, and therefore further improvements in the production efficiency of the coating treatment are desired. Examples of the method to improve the production efficiency include the method in which auto-drainage is suppressed as much as possible, and the method in which the coating treatment is performed while the accumulated treatment load is increased to be larger compared to the conventional method. The accumulated treatment load refers to a value (S/V(m²/L)) obtained by dividing the accumulated treatment area (Sm²) of a metallic material by the volume (VL) of the metallic material surface treating solution as the result of continuous operation of the coating treatment. For the technique of coating treatment for the metallic material, it is necessary that variation in the composition balance of the metallic material surface treating solution be small with respect to the larger accumulated treatment load, and that the treatment performance not degrade. If the variation in the composition balance of the metallic material surface treating solution is large with respect to the accumulated treatment load, or the treatment performance easily degrades, the metallic material surface treating solution has to be partially or wholly renewed to keep the stable treatment performance. Such case is not preferable from the standpoints of the production efficiency, costs and the environment.
The present inventors performed continuous operation of coating treatment using the replenisher specifically described in Patent Literature 3, studied the coating treatment performance when the accumulated treatment load is larger, and discovered that the coating weight on/over the metallic material would have decreased.
Under the above-described circumstances, an object of the present invention is to provide a replenisher that can replenish the metallic material surface treating solution with zirconium ion at the higher concentration while inhibiting an increase of the HF concentration in the metallic material surface treating solution such that chemical conversion treatment and/or electrolysis treatment can be continuously performed on/over metallic materials, and that exhibits excellent long-term storage stability.
In addition, an object of the present invention also is to provide a method for producing a surface-treated metallic material using the replenisher.

SOLUTION TO PROBLEMS

As a result of the intense study, the present inventors discovered that the above-described problem can be solved by using a replenisher with high zirconium ion concentration that is obtained by using the predetermined compound.
That is, the constitution of the present invention to solve the above-described problem is described below.

(1) A replenisher used to replenish metallic material surface treating solution with zirconium ion, the metallic material surface treating solution containing zirconium ion and fluorine ion and being used to form a chemical conversion coating containing zirconium on/over a metallic material through chemical conversion treatment and/or electrolysis treatment, the replenisher comprising:
- a fluorine-free zirconium compound (A) containing at least one selected from a group consisting of zirconium basic carbonate, zirconium carbonate, zirconium hydroxide and ammonium zirconium carbonate; a fluorine-containing compound (B) containing at least one selected from the group consisting of hydrofluoric acid, a salt of hydrofluoric acid, hexafluorozirconic acid and a salt of hexafluorozirconic acid; and an acid component (C) containing at least one selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid and acetic acid,
- wherein following relationships (I) to (III) are satisfied:
  1. (I) a ratio (M_AC/M_F) of a total molar quantity (M_AC) of anions derived from the acid component (C) with respect to a total molar quantity (M_F) of fluorine ion derived from the fluorine-containing compound (B) is 0.35 or more and less than 2.00;
  2. (II) a total concentration (g/L) of zirconium ion derived from the fluorine-free zirconium compound (A) and the fluorine-containing compound (3) is 25 or higher; and
  3. (III) a ratio (M_F/F_Zr) of a total molar quantity (M_F) of fluorine ion derived from the fluorine-containing compound (B) with respect to a total molar quantity (M_Zr) of zirconium ion derived from the fluorine-free zirconium compound (A) and the fluorine-containing compound (B) is 2.00 or more and less than 6.00.
(2) The replenisher according to (1), wherein the ratio (M_AC/M_F) exceeds 0.50 and is less than 2.00.
(3) The replenisher according to (1) or (2), wherein the ratio (M_AC/M_F) exceeds 0.50 and is 1.60 or less.
(4) A method for producing a surface-treated metallic material comprising:
- continuously performing chemical conversion treatment and/or electrolysis treatment on/over a metallic material in metallic material surface treating solution containing zirconium ion and fluorine ion to form a chemical conversion coating containing zirconium on/over the metallic material; and
- replenishing the metallic material surface treating solution with zirconium ion by adding the replenisher according to any one of (1) to (3) to the metallic material surface treating solution.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can provide a replenisher having more excellent long-term storage stability and capable of replenishing the metallic material surface treating solution with zirconium ion at high concentration while the HF concentration in the metallic material surface treating solution is inhibited from increasing such that chemical conversion treatment and/or electrolysis treatment can be continuously performed on/over metallic materials.
In addition, according to the present invention, the method for producing a surface-treated metallic material using the replenisher can be provided.

DESCRIPTION OF EMBODIMENTS

Below, the replenisher and the method for producing a surface-treated metallic material of the present invention are described.
The replenisher of the present invention contains a predetermined fluorine-free zirconium compound (A), a predetermined fluorine-containing compound (B) and a predetermined acid component (C), and contains zirconium ion (Zr ion) at a high concentration. Of the replenisher of the present invention, a ratio (M_AC/M_F) between the total molar quantity (M_AC) of anions derived from the acid component (C) and the total molar quantity (M_F) of fluorine ion (F ion), and a ratio (M_F/M_Zr) between the total molar quantity (M_Zr) of zirconium ion and the total molar quantity (M_F) of fluorine ion fall within predetermined ranges. By satisfying the components and the component quantity ratios above, the replenisher can achieve long-term storage stability. Moreover, the replenisher contains zirconium ion at the higher concentration compared to fluorine ion. Accordingly, when the metallic material surface treating solution is continuously replenished with the replenisher in continuous production of chemical conversion coatings, increase of HF can be inhibited and a large amount of zirconium ion can be continuously supplied. As a result, the chemical conversion treatment and/or electrolysis treatment can be continuously performed on/over metallic materials while the amount of auto-drained solution is suppressed. Specifically, by adjusting the ratio (M_AC/M_F) to fall within the predetermined range, the replenisher that has more excellent long-term storage stability and that enables the chemical conversion treatment and/or electrolysis treatment to be continuously performed on/over metallic materials can be provided.
An aspect of the replenisher of the present invention is first described below, and the method for producing a surface-treated metallic material using the replenisher is then described.

[Replenisher]

The replenisher of the present invention is used to mainly supply zirconium ion to a metallic material surface treating solution that contains zirconium ion and fluorine ion and that is used to form on/over a metallic material surface a chemical conversion coating containing zirconium as the main component through chemical conversion treatment and/or electrolysis treatment. Meanwhile, it should be noted that implementation of auto-drainage in the continuous production of chemical conversion coatings is not denied.
First, respective materials contained in the replenisher are described in detail, and the method for producing the replenisher is then described in detail.

(Fluorine-free Zirconium Compound (A))

The fluorine-free zirconium compound (A) contained in the replenisher of the present invention is a compound that does not contain fluorine atoms but contains Zr atoms.
The fluorine-free zirconium compound (A) includes at least one compound selected from the group consisting of zirconium basic carbonate, zirconium carbonate, zirconium hydroxide and ammonium zirconium carbonate. Among these, zirconium basic carbonate or zirconium carbonate is more preferable in terms of improving the storage stability of the replenisher and continuously performing the surface treatment more frequently (hereinafter, simply referred to as "in terms of improving the excellent effect of the present invention").
Two or more compounds described above may be used as the fluorine-free zirconium compound (A).

(Fluorine-containing Compound (B))

The fluorine-containing compound (B) contained in the replenisher of the present invention is a compound that contains fluorine atoms and that supplies the replenisher with F ion. When hexafluorozirconic acid or a salt thereof is used as the fluorine-containing compound (B), Zr ion is also supplied into the replenisher.
The fluorine-containing compound (B) includes at least one compound selected from the group consisting of hydrofluoric acid, a salt of hydrofluoric acid, hexafluorozirconic acid and a salt of hexafluorozirconic acid. Among these, hydrofluoric acid or hexafluorozirconic acid is more preferable from the standpoint of improving the excellent effect of the present invention.
Examples of the salt of hydrofluoric acid includes a salt of hydrofluoric acid with a base (such as an amine compound) and preferably a salt of hydrofluoric acid with a base that contains no metal, such as an ammonium salt. Furthermore, examples of the salt of hexafluorozirconic acid include metal acid salts (for example, sodium salt, potassium salt, lithium salt, ammonium salt and the like) such as K₂ZrF₆.
Two or more compounds described above may be used as the fluorine-containing compound (B).

(Acid Component (C))

The acid component (C) contained in the replenisher of the present invention performs roles as adjusting a pH of the replenisher and promoting solubility of other components (fluorine-free zirconium compound (A) and/or fluorine-containing compound (B)).
The acid component (C) includes at least one component selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid and acetic acid. Among these, nitric acid or sulfuric acid is more preferable from the standpoint of improving the excellent effect of the present invention.
Two or more acid components described above may be used as the acid component (C).

(Respective Component Contents)

The respective components in the replenisher of the present invention satisfy the following relationships (I) to (III).

(I) The ratio (M_AC/M_F) of the total molar quantity (M_AC) of anions derived from the acid component (C) with respect to the total molar quantity (M_F) of fluorine ion derived from the fluorine-containing compound (B) is 0.35 or more and less than 2.00.
(II) The total concentration (g/L) of zirconium ion derived from the fluorine-free zirconium compound (A) and the fluorine-containing compound (3) is 25 or higher.
(III) The ratio (M_F/M_Zr) of the total molar quantity (M_F) of fluorine ion derived from the fluorine-containing compound (B) with respect to the total molar quantity (M_Zr) of zirconium ion derived from the fluorine-free zirconium compound (A) and the fluorine-containing compound (B) is 2.00 or more and less than 6.00.

The relationships are independently described below.

(Relationship (I))

In the replenisher of the present invention, the ratio (M_AC/M_F) of the total molar quantity (M_AC) of anions derived from the acid component (C) with respect to the total molar quantity (M_F) of fluorine ion derived from the fluorine-containing compound (B) is 0.35 or more and less than 2.00. When the ratio is within this range, the replenisher has excellent storage stability and enables continuous and stable production of chemical conversion coatings without accumulation of HF in the metallic material surface treating solution. As the range for the more excellent effect of the present invention, the ratio (M_AC/M_F) is preferably more than 0.40 and less than 2.00, more preferably more than 0.50 and less than 2.00, further more preferably more than 0.50 and 1.60 or less, and yet further more preferably 1.00 or more and 1.60 or less.
When the ratio (M_AC/M_F) is less than 0.35, the long-term storage stability of the replenisher is inferior. If the ratio (M_AC/M_F) is 2.00 or more, when the replenisher is continuously used, the coating weight would decrease, and the desired coating cannot be formed.
Anions derived from the acid component (C) (nitric acid, hydrochloric acid, sulfuric acid and acetic acid) are NO₃ ^-, Cl^-, SO₄ ^2-, and CH₃COO^-.

(Relationship (II))

In the replenisher of the present invention, the total concentration (g/L) of zirconium ion derived from the fluorine-free zirconium compound (A) and from the fluorine-containing compound (B) is 25 or higher. When the concentration is within the range, chemical conversion coatings can be more economically produced. Particularly, the total concentration (g/L) of zirconium ion is preferably 30 or higher, and more preferably 35 or higher, since the amount of replenisher used can be reduced, and the operation economy can be better. Although not particularly limited thereto, the upper limit of the concentration is often 70 or lower, in view of solubility of the fluorine-free zirconium compound (A) and the fluorine-containing compound (B) .
When the total concentration (g/L) of zirconium ion is lower than 25, since the replenisher is dilute, a large amount of the replenisher needs to be supplied to the metallic material surface treating solution and thus causes an excessive replenishment, whereby the amount of the metallic material surface treating solution increases. As a result, in order to continuously perform the chemical conversion treatment, it is required to increase the auto-drainage amount of the metallic material surface creating solution, which is not preferable from the environmental and economical standpoint.
In addition, when hexafluorozirconic acid or a salt thereof is used as the fluorine-containing compound (B), zirconium ion derived from the fluorine-containing compound (B) are supplied.

(Relationship (III))

In the replenisher of the present invention, the ratio (M_F/M_Zr) of the total molar quantity (M_F) of fluorine ion derived from the fluorine-containing compound (B) with respect to the total molar quantity (M_Zr) of zirconium ion derived from the fluorine-free zirconium compound (A) and the fluorine-containing compound (B) is 2.00 or more and less than 6.00. When the ratio is within this range, stable production of chemical conversion coatings can be continuously performed without accumulation of HF in the metallic material surface treating solution. As the range for the more excellent effect of the present invention, the ratio (M_F/M_Zr) is preferably 2.50 to 5.50, and more preferably 3.00 to 5.00.
When the ratio (M_F/M_Zr) is less than 2.00, it is difficult to have zirconium compounds dissolved in the replenisher. In addition, if the ratio (M_F/M_Zr) is 6.00 or more, when the replenisher is continuously used, accumulation of HF in the metallic material surface treating solution cannot be inhibited. Therefore, for stable production of chemical conversion coatings, the amount of auto-drained solution needs to be increased, which is not preferable from the environmental and economical standpoint.
The respective ions described above can be measured using a known measurement device, atomic absorption, ICP, ion chromatography, or a fluorine ion meter.
In the replenisher of the present invention, the fluorine-free zirconium compound (A) content is not particularly limited as long as the above-described relationships (I) to (III) are satisfied, but is preferably 0.1 to 500 parts by mass, and more preferably 10 to 300 parts by mass, with respect to 100 parts by mass of the fluorine-containing compound (B), since the deposition efficiency of the chemical conversion coating is excellent.
The pH of the replenisher of the present invention is not particularly limited, but is preferably less than 4.0, and more preferably more than 0 and 1.5 or less, since the replenisher has excellent stability. When the pH is adjusted, an alkaline component can be also used. The alkaline component include alkali metal oxides such as sodium hydroxide, potassium hydroxide and the like; hydroxides of alkali earth metals such as calcium hydroxide, magnesium hydroxide and the like; and organic amines such as ammonia, monoethanolamine, diethanolamine, triethanolamine and the like. Among these, ammonia is preferably used since it has no metallic contamination and contains no organic solvent.
The replenisher of the present invention may contain a solvent as necessary. The type of solvent used is not particularly limited, and water and/or an organic solvent is normally used.
Examples of the organic solvent include an alcohol-based solvent and the like. While the organic solvent content may be within the range in which stability of the replenisher and of the metallic material surface treating solution to be replenished with the replenisher is not impaired, no organic solvent is preferably contained from the standpoint of the working environment.
The total mass of the above-described fluorine-free zirconium compound (A), fluorine-containing compound (B) and acid component (C) when the replenisher contains a solvent is preferably 2 mass% to 90 mass%, and more preferably 4 mass% to 80 mass%, with respect to the whole quantity of replenisher, since the deposition efficiency of the chemical conversion coating is more excellent.
The method for producing the replenisher of the present invention is not particularly limited, and any known method is adopted. Examples thereof include the method in which the fluorine-free zirconium compound (A), the fluorine-containing compound (B) and the acid component (C) are added in the solvent(s) and mixed.

[Method for Producing Surface-treated Metallic Materials]

Below described is the method for producing the surface-treated metallic materials using the replenisher of the present invention.
The method for producing the surface-treated metallic materials of the present invention is a method in which chemical conversion treatment and/or electrolysis treatment is continuously performed on/over a metallic material in a metallic material surface treating solution containing zirconium ion and fluorine ion to form a chemical conversion coating containing zirconium on/over the metallic material.
When the method for producing the surface-treated metallic materials described above is continuously performed, the zirconium ion concentration in the metallic material surface treating solution decreases accordingly, making it harder to form a coating containing a zirconium compound. In order to compensate for the decrease in the zirconium ion concentration, the metallic material surface treating solution is replenished with the replenisher described above.
Generally, in order to obtain the predetermined chemical conversion coatings on/over metallic materials continuously and stably, the replenisher is preferably added to the metallic material surface treating solution in such a manner that the zirconium ion concentration does not decrease by 20% or more. The total amount of fluorine ion supplied together with zirconium is preferably an amount obtained by subtracting the amount of fluorine ion in HF generated in the metallic material surface treating solution as a by-product during producing the coating containing the zirconium compound from the sum of all fluorine ion that is taken into the chemical conversion coating and all fluorine ion in the metallic material surface treating solution that adheres to the metallic material having the chemical conversion coating formed on/over the surface when the metallic material is taken out from the bath.
The method for adding the replenisher of the present invention into the metallic material surface treating solution is not particularly limited, and examples thereof include the method in which the replenisher is divided into small portions and added in several times (method A) and the method in which the replenisher in a predetermined amount is added at once (method B). Particularly, the method A is preferable, since component variation in the metallic material surface treating solution is small and the surface-treated metallic materials can be continuously and stably produced.
In addition, when the replenisher of the present invention is added into the metallic material surface treating solution, either of the method in which production is once suspended and the replenisher is added into the metallic material surface treating solution and the method in which production is not suspended and the replenisher is added into the metallic material surface treating solution during production method of the surface-treated metallic materials can be adopted. Of these, the method in which the replenisher is added into the metallic material surface treating solution during production method of the surface-treated metallic materials is preferable, since production efficiency is excellent particularly at high-speed operation, and the surface-treated metallic materials can be continuously and stably produced.
Below, the metallic material surface treating solution used in the method for producing the surface-treated metallic materials of the present invention is described.

(Metallic Material Surface Treating Solution)

The metallic material surface creating solution used in the method for producing the surface-treated metallic materials of the present invention described above contains Zr ion and fluorine ion.
Examples of the supply source of zirconium ion in the metallic material surface treating solution include the above-described fluorine-free zirconium compound (A), hexafluorozirconic acid or a salt thereof.
Zr ion in the metallic material surface treating solution refers to both (1) zirconium fluoride complex ion in which 1 to 6 moles of fluorine are coordinated to 1 mole of zirconium as expressed by ZrF_n(^4-n) and (2) zirconium ion or zirconyl ion generated from inorganic acid zirconium such as zirconium nitrate and zirconium sulfate or inorganic acid zirconyl, or alternatively, an organic acid zirconium or organic acid zirconyl such as zirconium acetate and zirconyl acetate.
The amount of zirconium ion contained in the metallic material surface treating solution is not particularly limited but is preferably 0.05 g/L to 10.00 g/L, and more preferably 0.10 g/L to 2.00 g/L, since the metallic material surface treating solution has more excellent stability, and the deposition efficiency of the chemical conversion coating is also more excellent.
Any known compound containing fluorine (fluorine-containing compound) can be used as the supply source of fluorine ion in the metallic material surface treating solution.
A fluorine compound having at least one element selected from the group consisting of Ti, Zr, Hf, Si, Al and B is preferably used as the fluorine-containing compound. Specific examples thereof include complexes in which 1 to 3 hydrogen atoms are coordinated to anions such as (Ti⁷F₆)^2-, (ZrF₆)^2-, (HfF₆)^2-, (SiF₆)^2-, (AlF₆)^3- and (BF₄OH)^-, and ammonium salts and metal salts of these anions.
Other examples of the fluorine-containing compound include hydrofluoric acid and its ammonium salt and alkali metal salts; metal fluorides (such as aluminum fluoride, zinc fluoride, vanadium fluoride, tin fluoride, manganese fluoride, ferrous fluoride and ferric fluoride or the like); and acid fluorides (such as fluorine oxide, acetyl fluoride and benzoyl fluoride or the like).
Fluorine ion in the metallic material surface treating solution refers to both fluorine ion (F^-) derived from HF present in the metallic material surface treating solution and fluorine ion in fluorine-containing complex ion such as the above-described zirconium: fluoride complex ion, and the total fluorine ion concentration described above and later refers to the concentration of the sum of both fluorine ion. Free fluorine concentration refers to the concentration of HF-derived fluorine ion (F^-).
The total amount of fluorine ion contained in the metallic material surface treating solution is not particularly limited but is preferably 0.050 g/L to 10.000 g/L, and more preferably 0.100 g/L to 3.000 g/L as the total fluorine ion concentration, since the metallic material surface treating solution has more excellent stability, and the deposition efficiency of the chemical conversion coating is also excellent. The free fluorine ion concentration is preferably 5 mg/L to 400 mg/L, and more preferably 10 mg/L to 250 mg/L.
The amounts (concentrations) of Zr ion, total fluorine ion, and free fluorine ion in the metallic material surface treating solution can be measured by using atomic absorption, ICP, ion chromatography or a fluorine ion meter.
The pH of the metallic material surface treating solution is appropriately adjusted according to the metallic material to be treated or the condition of the chemical conversion treatment or electrolysis treatment, but is preferably about 2.5 to 5.0, and more preferably 3.0 to 5.0, since the metallic material surface treating solution has more excellent stability and the deposition efficiency of the chemical conversion coating is also more excellent. The pH of the metallic material surface treating solution can be measured by using a pH meter.
Below described are the metallic material used in the method for producing the surface-treated metallic material of the present invention as well as the chemical conversion treatment and the electrolysis treatment.

(Metallic Material)

The type of metallic material used is not particularly limited, and any known metallic material can be used. Examples thereof include iron material, plating material, zinc material, aluminum material, magnesium material and the like.
The shape of the metallic material is not particularly limited and can be a plate shape or any other shape. Examples of the other shapes include a vehicle body of a transporting device such as an automobile and its constituent component, a farm equipment and its constituent component, steel furniture, building material and the like.

(Chemical Conversion Treatment or Electrolysis Treatment)

The chemical conversion treatment using the metallic material surface treating solution described above can be performed using known treatment facilities under a known condition. The chemical conversion treatment is a treatment in which a metallic material is brought into contact (immersion, coating or spraying) with a predetermined metallic material surface treating solution that is at normal temperature or heated, whereby a coating is formed on/over the surface of the metallic material.
The duration of contact between the metallic material and the metallic material surface treating solution is appropriately adjusted depending on the quality or shape of the metallic material to be treated, treatment method, application thereof and the targeted coating weight, and is normally about 0.1 second to 600 seconds in many cases, since the chemical conversion coating has more excellent properties.
The electrolysis treatment (anodic electrolysis treatment, cathodic electrolysis treatment) using the metallic material surface treating solution can be performed using known electrolysis treatment facilities under a known condition.
For example, the current density is preferably 0.1 A/dm² to 20.0 A/dm², and more preferably 0.5 A/dm² to 10.0 A/dm² since the deposition efficiency of the chemical conversion coating is excellent.
The coating weight of zirconium in the formed chemical conversion coating is appropriately adjusted depending on the quality or application of the metallic material to be treated, and is normally about 1 mg/m² to 70 mg/m² in many cases in both the chemical conversion treatment and the electrolysis treatment, since the chemical conversion coating has more excellent properties.

EXAMPLES

The present invention is illustrated below with specific examples. The examples are given merely by way of illustration of the present invention and should not be construed as limiting the invention.

(Test Sheet)

The following test sheets (1) to (3) were used in Examples and Comparative Examples.

(1) Aluminum alloy sheet (6000-series aluminum alloy, thickness: 0.8 mm)
(2) Cold-rolled steel sheet (SPC, thickness: 0.8 mm)
(3) Alloyed hot-dip galvanized steel sheet (GA, thickness: 0.8 mm)

(Replenisher)

The fluorine-free zirconium compound (A), the fluorine-containing compound (B) and the acid component (C) were mixed in water so as to have compositions shown in Table 1, whereby the various replenishers were prepared.

(Surface Treatment Methods for Metallic Materials)

The surface treatment methods for metallic materials in Examples and Comparative Examples described below were performed in accordance with the following procedure.

(1) Degreasing
(2) Washing with water (tap water)
(3) Chemical conversion treatment
(4) Washing with water (tap water)
(5) Washing with water (ion-exchanged water)
(6) Draining off water and drying

The above degreasing process was performed using an alkaline degreasing agent, Finecleaner L4460 (2.0%; 45°C, 120 seconds, spraying) manufactured by Nihon Parkerizing Co., Ltd.
The chemical conversion treatment method will be described in detail in the next section about the continuous treating test method. In addition, in the process of draining off water and drying, after draining off the water with rollers, drying was performed in an oven at 100°C.

(Continuous Treating Test Method (Running Test))

As the above-described chemical conversion treatment, any one of the following continuous treating methods 1 to 3 was performed.

After a bath was made up of 10L of treating solution having the components of concentrations described below, the treating solution was adjusted to have a pH of 4.0 and heated to 40°C to prepare a metallic material surface treating solution. The metallic material surface treating solution was stirred and a test sheet (1) was immersed in the metallic material surface treating solution for 180 seconds, whereby the surface treatment was performed to achieve a target Zr coating weight of 13 mg/m². This process was regarded as one cycle and repeated using new test sheets (1) so as to perform surface treatment (continuous treating test). In this process, since the amount of the metallic material surface treating solution that adhered to and was taken out by the test sheet (1) (taken-out solution) was 75 mL/m², water and the replenisher shown in Table 1 were added to restore the solution level and to replenish the decreased Zr concentration in the metallic material surface treating solution at every processing load of 0.5 m²/L, thereby adjusting the solution level and the Zr concentration at a time. The pH of the metallic material surface treating solution was also adjusted at every 0.5 m²/L with ammonia water as necessary. The above-described continuous treating test was performed until 100% of all treating solution of 10L was replaced as the taken-out solution. That is, the test was conducted until the processing load reached 13.3 m²/L, and the Zr coating weight at the beginning of the continuous treating test and the Zr coating weight at the time when the processing load became 13.3 m²/L were measured. The Zr coating weight on the surface of the treated material was quantitatively determined using X-ray fluorescence (XRF) analysis.

(Components of Treating Solution)

Concentrations of the respective components were as follows: Zr ion concentration was 100 mg/L, total F ion concentration was 150 mg/L, free F ion concentration was 25 mg/L, and NO₃ ion concentration was 190 mg/L.

After a bath was made up of 10L of a treating solution having the components of concentrations described below, the treating solution was adjusted to have a pH of 4.0 and heated to 40°C to prepare a metallic material surface treating solution. The metallic material surface treating solution was stirred and a test sheet (2) was immersed in the metallic material surface treating solution for 120 seconds, whereby the surface treatment was performed to achieve a target Zr coating weight of 20 mg/m². This process was regarded as one cycle and repeated using new test sheets (2) so as to perform surface treatment (continuous treating test). In this process, since the amount of the metallic material surface treating solution that adhered to and was taken out by the test sheet (2) (taken-out solution) was 60 mL/m², water and the replenisher shown in Table 1 were added to restore the solution level and to replenish the decreased Zr concentration in the metallic material surface treating solution at every processing load of 0.5 m²/L, thereby adjusting the solution level and the Zr concentration at a time. The pH of the metallic material surface treating solution was also adjusted at every 0.5 m²/L with ammonia water as necessary. The above-described continuous treating test was performed until 100% of all treating solution of 10L was replaced as the taken-out solution. That is, the test was conducted until the processing load reached 16.7 m²/L, and the Zr coating weight at the beginning of the continuous treating test and the Zr coating weight at the time when the processing load became 16.7 m²/L were measured. The Zr coating weight on the surface of the treated material was quantitatively determined using X-ray fluorescence (XRF) analysis.

(Components of Treating Solution)

Concentrations of the respective components were as follows: Zr ion concentration was 500 mg/L, total F ion concentration was 680 mg/L, free F ion concentration was 36 mg/L, and NO₃ ion concentration was 750 mg/L.

After a bath was made up of 10L of treating solution having the components of concentrations described below, the treating solution was adjusted to have a pH of 3.7 and heated to 40°C to prepare a metallic material surface treating solution. The metallic material surface treating solution was stirred and a test sheet (3) was immersed in the metallic material surface treating solution for 30 seconds, thereby the surface treatment was performed to achieve a target Zr coating weight of 10 mg/m². This process was regarded as one cycle and repeated using new test sheets (3) so as to perform surface treatment (continuous treating test). In this process, since the amount of the metallic material surface treating solution that adhered to and was taken out by the test sheet (3) (taken-out solution) was 22 mL/m², water and the replenisher shown in Table 1 were added to restore the solution level and to replenish the decreased Zr concentration in the metallic material surface treating solution at every processing load of 0.5 m²/L, thereby adjusting the solution level and the Zr concentration at a time. The pH of the metallic material surface treating solution was also adjusted at every 0.5 m²/L with ammonia water as necessary. The above-described continuous treating test was performed until 100% of all treating solution of 10L was replaced as the taken-out solution. That is, the test was conducted until the processing load reached 45.5 m²/L, and the Zr coating weight at the beginning of the continuous treating test and the Zr coating weight at the time when the processing load became 45.5 m²/L were measured. The Zr coating weight on the surface of the treated material was quantitatively determined using X-ray fluorescence (XRF) analysis.

(Components of Treating Solution)

Concentrations of the respective components were as follows: Zr ion concentration was 1,500 mg/L, total F ion concentration was 2,010 mg/L, free F ion concentration was 95 mg/L, and NO₃ ion concentration was 2,190 mg/L.

(5) Evaluation Test

Evaluations (A) and (B) shown below were carried out by using the replenisher shown in Table 1.

(A) Replenisher Storage Stability Test (Long-term Storability)

The replenisher shown in Table 1 was put in a plastic container, which was sealed. The replenisher was stored for a maximum of 6 months at 35°C immediately after sealed, and appearance of the solution was then evaluated. The evaluation standards are described below. Practically, "Good" or
"Excellent" is preferable.
Excellent: Appearance does not change on or later than 6 months from the start of storage.
Good: Appearance changes in a period starting on or later than 3 months and ending earlier than 6 months from the start of storage.
Fair: Appearance changes in a period starting on or later than 2 weeks and ending earlier than 3 months from the start of storage.
Poor: Precipitation, or turbidness or gelation of the solution is observed earlier than 2 weeks from the start of storage.
Here, "appearance does not change" means that none of precipitation, turbidness and gelation is observed, and the solution is colorless and transparent.

(B) Running Test (Continuous Treating Test)

Continuous treating test was conducted according to the treating methods shown in Table 1, the Zr coating weight on the test piece (test sheet) was determined at the beginning of the test (first cycle) and at the time when the treating solution was 100% replaced, and the thus determined values were compared. The evaluation standards are described below. Practically, "Good" or "Excellent" is preferable.
Excellent: The Zr coating weight after 100% replacement is 95% or more and less than 105% with respect to the Zr coating weight at the beginning of the continuous treating rest.
Good: The Zr coating weight after 100% replacement is 85% or more and less than 95% with respect to the Zr coating weight at the beginning of the continuous treating test.
Fair: The Zr coating weight after 100% replacement is 50% or more and less than 85% with respect to the Zr coating weight at the beginning of the continuous treating test.
Poor: The Zr coating weight after 100% replacement is less than 50% with respect to the Zr coating weight at the beginning of the continuous treating test.

[Table 1]

Table 1

	Continuous Treating Method	Replenisher Composition						Performance Evaluation
	Continuous Treating Method	Fluorine-free Zirconium Component (A)	Fluorine-containing Component (B)	Acid Component (C)	Zr Concentration g/L	M_F/M_Zr	M_AC/M_F	Long-term Storability	Running Property
Example 1	1	Zr Carb	HF	Nitric Acid	35	3.00	1.00	Excellent	Excellent
Example 2	2	Zr Carb	HF	Nitric Acid	35	4.00	0.50	Good	Good
Example 3	3	Zr Basic Carb	H₂ZrF₆+HF *1)	Nitric Acid	45	5.00	0.50	Good	Good
Example 4	1	Zr Carb	HF	Nitric Acid	25	3.00	1.20	Excellent	Excellent
Example 5	2	Zr Carb	HF	Nitric Acid	35	4.00	1.20	Excellent	Excellent
Example 6	3	Zr Basic Carb	HF	Nitric Acid	35	5.00	1.20	Excellent	Excellent
Example 7	1	Zr Carb	HF	Nitric Acid	25	3.00	1.80	Excellent	Good
Example 8	2	Zr Carb	HF	Nitric Acid	35	4.00	1.80	Excellent	Good
Example 9	3	Zr Basic Carb	H₂ZrF₆+HF *1)	Nitric Acid	28	5.00	1.80	Excellent	Good
Comparative Example 1	1	Zr Carb	HF	Nitric Acid	25	3.00	0.33	Poor	*2)
Comparative Example 2	2	Zr Basic Carb	HF	Nitric Acid	35	4.00	0.33	Poor	*2)
Comparative Example 3	3	Zr Basic Carb	H₂ZrF₆+HF *1)	Nitric Acid	45	5.00	0.33	Poor	*2)
Comparative Example 4	1	Zr Carb	HF	Nitric Acid	25	3.00	2.50	Good	Poor
Comparative Example 5	2	Zr Basic Carb	HF	Nitric Acid	35	4.00	2.50	Good	Fair
Comparative Example 6	3	Zr Basic Carb	H₂ZrF₆+HF *1)	Nitric Acid	30	5.00	2.50	Good	Fair

In Table 1, "Zr Carb" refers to zirconium carbonate, "Zr Basic Carb" refers to zirconium basic carbonate, and "Zr Concentration" refers to zirconium ion concentration (g/L).

*1) H₂ZrF₆:HF = 4.6:1 (weight ratio)
*2) In Comparative Examples 1 to 3, since the replenisher had so poor long-term storability that precipitation was observed within 1 week at 35°C, the replenisher was regarded as practically unusable, and thus the running test was not performed.

As shown in Table 1, in Examples where the replenisher of the present invention was used, it was confirmed that the replenisher had excellent long-term storability as well as excellent continuous treating properties (continuous operation properties).
Particularly, as is seen from the comparison of Examples 2 to 3 with Examples 1 and 4 to 9, it was confirmed that when M_AC/M_F exceeded 0.50 and was less than 2.00, the replenisher had more excellent long-term storability.
In addition, as is seen from the comparison of Examples 2 to 3 and 7 to 9 with Examples 1 and 4 to 6, it was confirmed that when M_AC/M_F exceeded 0.50 and was 1.60 or less, running property (continuous operation property) was more excellent.
On the other hand, in Comparative Examples 1 to 3 where the ratio (M_AC/M_F) is below the predetermined range, the replenisher had the inferior storage stability.
The replenisher made from the mixture solution of hexafluorozirconic acid and zirconium nitrate described in paragraph [0033] of Patent Literature 3 ( JP 4996409 B ) has the ratio M_AC/M_F of 0.33 and could not achieve the desired effect, as being apparent from Comparative Examples 1 to 3 in Table 1.
In Comparative Examples 4 to 6, presumably because as anions that stabilize zirconium in the replenisher, anions derived from the acid component (C) are present at the higher rate than fluorine derived from the fluorine-containing compound (B), after the replenisher of any of Comparative Examples 4 to 6 is added to the metallic material surface treating solution, coordination between zirconium and other anions becomes stronger than Zr-F coordination in the metallic material surface treating solution, whereby stabilization of coating reaction becomes difficult. It is presumed that this was affected by coordination between zirconium ion and F ion since hydrolysis of H₂ZrF₆ is utilized as coating reaction.

Claims

A replenisher used to replenish metallic material surface treating solution with zirconium ion, the metallic material surface treating solution containing zirconium ion and fluorine ion and being used to form a chemical conversion coating containing zirconium on/over a metallic material through chemical conversion treatment and/or electrolysis treatment, the replenisher comprising:
a fluorine-free zirconium compound (A) containing at least one selected from a group consisting of zirconium basic carbonate, zirconium carbonate, zirconium hydroxide and ammonium zirconium carbonate; a fluorine-containing compound (B) containing at least one selected from the group consisting of hydrofluoric acid, a salt of hydrofluoric acid, hexafluorozirconic acid and a salt of hexafluorozirconic acid; and an acid component (C) containing at least one selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid and acetic acid,

wherein following relationships (I) to (III) are satisfied:
(I) a ratio (M_AC/M_F) of a total molar quantity (M_AC) of anions derived from the acid component (C) with respect to a total molar quantity (M_F) of fluorine ion derived from the fluorine-containing compound (B) is 0.35 or more and less than 2.00;

(II) a total concentration (g/L) of zirconium ion derived from the fluorine-free zirconium compound (A) and the fluorine-containing compound (B) is 25 or higher; and

(III) a ratio (M_F/M_Zr) of a total molar quantity (M_F) of fluorine ion derived from the fluorine-containing compound (B) with respect to a total molar quantity (M_Zr) of zirconium ion derived from the fluorine-free zirconium compound (A) and the fluorine-containing compound (B) is 2.00 or more and less than 6.00.
The replenisher according to claim 1, wherein the ratio (M_AC/M_F) exceeds 0.50 and is less than 2.00.
The replenisher according to claim 1 or 2, wherein the ratio (M_AC/M_F) exceeds 0.50 and is 1.60 or less.
A method for producing a surface-treated metallic material comprising:
continuously performing chemical conversion treatment and/or electrolysis treatment on/over a metallic material in metallic material surface treating solution containing zirconium ion and fluorine ion to form a chemical conversion coating containing zirconium on/over the metallic material; and

replenishing the metallic material surface treating solution with zirconium ion by adding the replenisher according to any one of claims 1 to 3 to the metallic material surface treating solution.