JP5591758B2 - Aqueous solution for blackening treatment of metal surface and blackening treatment method - Google Patents

Description

  The present invention relates to a treatment liquid and a treatment method for blackening a metal surface.

  A technique for coloring a metal surface and adding added value to the original metal has been performed for a long time. Among them, blackened metals are used in fields that require decorativeness and aesthetics, such as building materials, interior parts, and accessories. Further, since the blackened metal can suppress the reflection of light, there are many demands as an optical system device and parts.

Conventionally, many techniques for blackening a metal surface have been disclosed.
(1) Japanese Patent Laid-Open No. 53-52249 discloses that “a metal film is immersed in a dilute hydrofluoric acid aqueous solution of 1 weight percent or less of hydrogen fluoride to form a black coating on the metal surface. "Titanium metal surface treatment method" is disclosed.
(2) Japanese Patent Laid-Open No. 62-260070 discloses “a method of producing a black titanium material by treating titanium or a titanium alloy with a sulfuric acid aqueous solution at 50 ° C. or higher and then treating with a hydrofluoric acid aqueous solution”. ing.
(3) Japanese Unexamined Patent Publication No. 63-195295 discloses a “method of combining a pulse electrolysis method and a plasma chemical reaction in a method of producing a decorative film on aluminum, titanium, tantalum, zirconium, niobium or an alloy thereof”. It is disclosed.
(4) Japanese Patent Laid-Open No. 02-93097 states that “the surface of titanium and a titanium alloy is subjected to an anodizing treatment and then heat-treated at a temperature of at least 600 ° C. in a reducing atmosphere. "Method for forming black film of titanium and titanium alloy" is disclosed.
(5) Japanese Laid-Open Patent Publication No. 02-170984 discloses a “method for forming a colored film by treating titanium or a titanium alloy with a borohydrofluoric acid solution or an acidic potassium fluoride solution”. .

JP-A-53-52249 JP 62-260070 A JP-A 63-195295 Japanese Patent Laid-Open No. 02-93097 Japanese Patent Laid-Open No. 02-170984

As described above, many methods for coloring, particularly blackening, the metal surface have been disclosed. However, there are many harsh and cumbersome processing steps, such as a high processing solution temperature of, for example, 50 ° C. or higher, and electrolytic treatment such as pulse electrolysis and anodic electrolysis. The environment is never good. In addition, Patent Document 1 discloses a method of treating titanium metal with a hydrofluoric acid solution or a borohydrofluoric acid solution at around room temperature. However, the blackness of the formed black film is never satisfactory. Rather, the fields that can be used practically are limited.
Therefore, the present invention is a simple method in which the metal is brought into contact with the blackening solution without electrolytic treatment, and further, blackening that can form a practically effective blackening metal even under mild conditions where the processing temperature is near room temperature. It is an object to provide a treatment liquid and a blackening treatment method.

  The inventors of the present invention have made extensive studies in order to solve the above-mentioned problems. As a result, the metal surface is selected from the group consisting of (A) fluoride ions, borofluoride ions, and silicofluoride ions under mild conditions near room temperature. 1 or 2 or more, (B) 1 or 2 or more types of polar aprotic solvents, it is found that a uniform black appearance can be obtained by treating with an aqueous solution containing essential components. The present invention has been completed.

In one aspect, the present invention completed based on the above knowledge is an aqueous solution for blackening treatment of a metal surface containing the following components (A) and (B).
(A) component: 1 type, or 2 or more types selected from the group which consists of fluoride ion, borofluoride ion, and silicofluoride ion;
Component (B): one or more polar aprotic solvents

  In one embodiment of the blackening treatment aqueous solution according to the present invention, the polar aprotic solvent is N, N-dimethylformamide.

  In another embodiment of the aqueous solution for blackening treatment according to the present invention, the metal is Mg, Al, Si, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, and Re. Or an alloy containing one or more of them.

  In another embodiment of the blackening treatment aqueous solution according to the present invention, the total concentration of the component (A) is in the range of 0.01 to 10% by mass.

  In another embodiment of the blackening treatment aqueous solution according to the present invention, the total concentration of the component (B) is in the range of 1 to 60% by mass.

  In another aspect, the present invention is a method for blackening a metal surface, which includes a blackening step of bringing the metal surface into contact with any one of the blackening aqueous solutions according to the present invention.

  In one embodiment, a blackening treatment method according to the present invention is a pretreatment step in which a metal surface is brought into contact with a solution containing at least fluoride ions and not containing a polar aprotic solvent before performing the blackening step. including.

  In one embodiment, the blackening treatment method according to the present invention includes a post-treatment step of further performing a heat treatment at 200 to 450 ° C. on the metal whose surface is blackened after performing the blackening step.

  In still another aspect of the present invention, the metal obtained by the blackening treatment method according to the present invention has a blackened surface.

  If the aqueous solution for blackening treatment according to the present invention is used, it is practically effective even in mild conditions such that the metal is brought into contact with the aqueous solution without electrolytic treatment, and the treatment temperature is also near room temperature. A special effect that a blackened metal can be formed is obtained.

  For example, many methods for forming a colored film by treating titanium with a solution containing a fluorine compound have been disclosed. However, even if titanium is treated with a treatment solution containing a fluorine-based compound, if the treatment solution does not contain a polar aprotic solvent, the titanium surface is only dissolved and slightly colored. However, as in the present invention, in addition to (A) one or more selected from the group consisting of fluoride ions, borofluoride ions and silicofluoride ions, (B) one or more polar aprotic solvents or By treating with an aqueous solution containing two or more, a uniform and strong black film can be formed. Although the mechanism is unknown, it is presumed as follows. When treated with an aqueous solution containing a fluorine-based compound but not containing a polar aprotic solvent, titanium dissolves, but at that time, it becomes a water-soluble titanium fluoride compound, so it simply dissolves, and the metal surface is Do not color. In contrast, when a polar aprotic solvent is used in combination, the solvation state and solubility of titanium ions and fluoride ions in the solution change compared to the case of the aqueous solution, so that the insoluble titanium compound is deposited on the metal surface. It is thought to form easily and deposit. It seems that this insoluble titanium compound is black.

The metal surface blackening treatment liquid according to the present invention is provided as an aqueous solution containing both of the following components (A) and (B).
(A) component: 1 type, or 2 or more types selected from the group which consists of fluoride ion, borofluoride ion, and silicofluoride ion;
Component (B): one or more polar aprotic solvents

  (A) As a supply source of a component, acids, such as hydrofluoric acid, borohydrofluoric acid, and silicohydrofluoric acid, and these salts are mentioned. Although it is not intended that the present invention be limited by theory, it is believed that component (A) serves to dissolve the metal surface. As the component (A), a metal oxide film and the metal itself can be dissolved quickly, and therefore fluoride ions are preferable. In addition to hydrofluoric acid, ammonium, lithium, sodium, potassium, magnesium, tantalum, vanadium or A metal and fluorine salt such as manganese, or a double salt of such a salt and hydrogen fluoride can be preferably used as a fluoride ion supply source, and hydrofluoric acid is most preferably used.

  The total concentration of the component (A) is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, and most preferably 0.1 to 3% by mass. It is done. When the concentration is higher than 10% by mass, the reaction of the ions on the metal surface is too strong, and the metal surface simply dissolves, and blackening is difficult. On the other hand, when it is lower than 0.01% by mass, the metal surface does not dissolve or the reaction is very slow, which is not practical.

  The polar aprotic solvent used as the component (B) is not intended to limit the present invention by theory, but the component (B) is a compound in which the metal dissolved by the component (A) forms a black insoluble compound. This is thought to promote the reaction that deposits on the metal surface. It also has the role of improving the uniformity of the black film. Examples of the polar aprotic solvent include, but are not limited to, tetrahydrofuran, acetone, acetonitrile (AN), N, N-dimethylformamide (DMF), formamide, dimethyl sulfoxide (DMSO), 1,3-dimethyl-2- One or more kinds selected from imidazolidinone and hexamethylphosphoric triamide are preferably used. Among them, acetonitrile (AN), N, N-dimethylformamide (DMF), formamide, dimethyl sulfoxide (DMSO) are more preferably used because a darker treated appearance can be obtained, and N, N-dimethylformamide ( DMF) and dimethyl sulfoxide (DMSO) are more preferably used, and N, N-dimethylformamide (DMF) is most preferably used.

  As described above, the polar aprotic solvent is an indispensable compound for forming an insoluble black titanium compound. However, the concentration is very important to obtain a uniform black film. That is, the total concentration of the component (B) is preferably 1 to 60% by mass, more preferably 10 to 50% by mass, and most preferably 20 to 40% by mass. When the total concentration of the component (B) is higher than 60% by mass, the blackening reaction hardly proceeds, and when it is lower than 1% by mass, the dissolution reaction of the metal surface by the component (A) is too fast, and the metal Although it dissolves depending on the conditions, it is difficult to obtain a blackness that can be used practically.

  The mass ratio of the component (A) and the component (B) also affects the appearance. In a typical embodiment, the A / B ratio is less than 5, and in a more typical embodiment, the A / B ratio is 0.001 to 0.5. By setting A / B in such a range, a better black appearance can be obtained.

  The metal that can be blackened by the blackening aqueous solution according to the present invention is not particularly limited. However, when treated with the treatment liquid, the dissolved metal ions easily form a black insoluble compound. Si, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, and Re are preferably used. Among these, Mg, Al, Si, Ti, V, Cr, Zr, Nb, Mo, Ta, and W are preferably used, Mg, Al, Ti, and Ta are more preferably used, and Ti is most preferably used.

  These metal elements are preferably pure metals (including those inevitably containing impurities), alloys containing these metal elements as main components, or alloys containing them as additive elements. Alternatively, an alloy containing these metal elements as main components is more preferably used. Further, the pure metal or alloy is not limited to those produced metallurgically, and may be produced by performing wet or dry plating. That is, the metal referred to in the present invention refers to a material whose surface is made of metal, and the inside may be a material other than metal. For example, a material obtained by metal-plating a plastic surface also corresponds to the metal in the present invention.

  A known acid other than hydrofluoric acid, borohydrofluoric acid, and silicohydrofluoric acid that can be used as the component (A) may be added to the blackening treatment aqueous solution according to the present invention. For example, inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid and pyrophosphoric acid, and organic acids such as methanesulfonic acid, phenolsulfonic acid, sulfamic acid, citric acid and gluconic acid in the form of acids or their sodium, potassium, What is necessary is just to add in the form of salts, such as ammonium. By adding an acid, the degree of black can be changed and adjusted to a desired color. If the amount of acid added is too large, the original blackening reaction will be hindered, and if it is too small, no effect will be observed. Specifically, it is preferably about 0.1 to 30% by mass, and more preferably about 1 to 20% by mass. Since these acids generally have a weaker ability to dissolve metals than hydrofluoric acid, the effect of the basic component is not significantly hindered within this concentration range.

  A surfactant can be further added to the blackening aqueous solution according to the present invention. As the surfactant, known cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants are appropriately used alone or in combination.

  Examples of the cationic surfactant include tetra-lower alkyl ammonium halide, alkyl trimethyl ammonium halide, polyoxyethylene alkyl methyl ammonium halide, and the like. Examples of the anionic surfactant include alkyl (or formalin condensate) -β-naphthalene sulfonic acid (or salt thereof), alkyl sulfonate, alkyl benzene sulfonate, alkyl (or alkoxy) naphthalene sulfonate, and the like. . Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether (or ester), polyoxyalkylene phenyl (or alkylphenyl) ether, polyoxyalkylene naphthyl (or alkylnaphthyl) ether, polyoxy Ethylene alkylamine, etc. Examples of amphoteric surfactants include 2-alkyl-N-carboxymethyl (or ethyl) -N-hydroxyethyl (or methyl) imidazolinium betaine, 2-alkyl-N-carboxymethyl (or ethyl) -N-carboxy. Examples include methyloxyethyl imidazolinium betaine and dimethylalkyl betaine.

  The concentration of these surfactants is appropriately selected, but is generally preferably 0.001 to 50 g / L, and more preferably 0.01 to 20 g / L. By adding the surfactant, the appearance uniformity of the blackened film can be improved.

  By bringing the metal surface into contact with the aqueous solution for blackening treatment according to the present invention (blackening step), the surface can be blackened. Although there is no restriction | limiting in particular as a contact method, There exist the method of immersing a metal in the said aqueous solution, the method of apply | coating the said aqueous solution to a metal surface, the method of spraying the said aqueous solution on the metal surface, etc. Among these, the method of immersing a metal in the aqueous solution is simple and preferable for obtaining a uniform appearance.

  The temperature of the blackening treatment aqueous solution in the blackening step is preferably 5 to 50 ° C, more preferably 10 to 35 ° C. If the temperature is too low, the formation of the blackened film is slow and the productivity is inferior. However, according to the present invention, sufficient blackening can be achieved at a temperature near room temperature. Even if the temperature is too high, the effect reaches a peak, which is not economical, and the polar aprotic solvent as the component (B) is likely to evaporate, resulting in a poor working environment. The time for contacting the metal with the aqueous solution is not particularly limited, but is preferably about 10 seconds to 30 minutes, and more preferably 30 seconds to 10 minutes. If the treatment time is short, the blackness is not sufficient, and even if the treatment time is too long, the effect reaches its peak, resulting in poor productivity.

  Before carrying out the blackening step, a more uniform black appearance can be obtained by bringing the metal surface into contact with a solution containing at least fluoride ions and not containing a polar aprotic solvent (pretreatment step). . The pretreatment solution further contains an inorganic acid such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid or pyrophosphoric acid, or an organic acid such as methanesulfonic acid, phenolsulfonic acid, sulfamic acid, citric acid or gluconic acid in the form of acid or You may add in the form of salts, such as those sodium, potassium, and ammonium.

  In order to increase the degree of blackness, after performing the blackening step, the metal whose surface is blackened may be further subjected to a heat treatment (post-treatment step) at 200 to 450 ° C., preferably 300 to 400 ° C. . If the heat treatment time is short, the effect is weak, and if it is too long, the effect reaches its peak, which is uneconomical. Specifically, 10 to 60 minutes are preferable, and 20 to 40 minutes are more preferable.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples, Arbitrary deformation | transformation can be made within the range of the technical idea of this invention.

Example 1
A titanium plate (50 × 50 × 0.3 mm) was added to a blackening aqueous solution (liquid temperature) containing 3% by mass of hydrogen fluoride (as fluoride ions) and 35% by mass of N, N-dimethylformamide (DMF). (20 ° C.) for 3 minutes. Next, after washing with water, it was dried at 50 ° C. for 10 minutes. The sample was visually evaluated for color and uniformity.

The uniformity was classified into ◎, ○, and △ according to the following criteria.
◎: No unevenness ○: Unevenness (area less than 5% of test piece)
Δ: Unevenness (area of 5% to 20% of test piece)

(Examples 2 to 28)
Except that the type of metal, (A) the type and concentration of fluoride ion, borofluoride ion and silicofluoride ion, and (B) the type and concentration of polar aprotic solvent were changed as shown in Table 1. The titanium plate was treated under the same conditions as in Example 1, and the color and uniformity were visually evaluated.

(Comparative Example 1)
A titanium plate was treated in the same manner as in Example 1 except that an aqueous solution in which only 3% by mass of hydrofluoric acid (as fluoride ions) was added to water was used. The sample was visually evaluated for color and uniformity.

(Comparative Example 2)
A titanium plate was treated in the same manner as in Example 1 except that an aqueous solution containing only 3% by mass of borohydrofluoric acid (as borofluoride ions) was added to water. The sample was visually evaluated for color and uniformity.

(Comparative Example 3)
The titanium plate was treated in the same manner as in Example 1 except that an aqueous solution in which only 30% by mass of N, N-dimethylformamide was added to water was used. The sample was visually evaluated for color and uniformity.

  The results are shown in Table 1. It turns out that Examples 1-28 are strong blackness compared with Comparative Examples 1-3, and a blackened metal with high uniformity is obtained.

(Example 29)
Before immersing in the aqueous solution for blackening treatment, the titanium plate was immersed for 3 minutes in an aqueous solution (liquid temperature 20 ° C.) in which only hydrogen fluoride: 0.5% by mass (as fluoride ions) was added to water. The titanium plate was treated in the same manner as in Example 11. The sample was visually evaluated for color and uniformity. As a result, the uniformity of the appearance was improved as compared with Example 11.

(Example 30)
A titanium plate was treated in the same manner as in Example 12 except that phosphoric acid: 10% by mass was added to the blackening aqueous solution. The sample was visually evaluated for color and uniformity. As a result, the blackness was improved as compared with Example 12.

(Example 31)
A titanium plate was treated in the same manner as in Example 11 except that 1% by mass of polyoxyethylene lauryl ether was added to the blackening aqueous solution. The sample was visually evaluated for color and uniformity. As a result, the uniformity of the appearance was improved as compared with Example 11.

(Example 32)
A titanium plate was treated by the same method as in Example 12. The titanium plate having a blackened surface thus obtained was further heat-treated at 320 ° C. for 30 minutes. The sample was visually evaluated for color and uniformity. As a result, the blackness was improved as compared with Example 12.

Claims (10)

An aqueous solution for blackening treatment of a metal surface containing the following components (A) and (B).
(A) component: 1 type, or 2 or more types selected from the group which consists of fluoride ion, borofluoride ion, and silicofluoride ion;
Component (B): one or more polar aprotic solvents   The aqueous solution for blackening treatment of a metal surface according to claim 1, wherein the polar aprotic solvent is N, N-dimethylformamide.   The metal is any one of Mg, Al, Si, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W and Re, or one or more of them. The aqueous solution for blackening treatment of the metal surface according to claim 1 or 2, which is an alloy containing the metal.   The aqueous solution for blackening treatment of the metal surface according to any one of claims 1 to 3, wherein the total concentration of the component (A) is in the range of 0.01 to 10% by mass.   The aqueous solution for blackening treatment of a metal surface according to any one of claims 1 to 4, wherein the concentration of the polar aprotic solvent is in the range of 1 to 60% by mass.   Furthermore, the aqueous solution for the blackening process of the metal surface in any one of Claims 1-5 containing 0.001-50 g / L of surfactant in total.   A method for blackening a metal surface, comprising a blackening step of bringing the metal surface into contact with the aqueous solution for blackening treatment according to claim 1.   8. The blackening of the metal surface according to claim 7, further comprising a pretreatment step of bringing the metal surface into contact with a solution containing at least fluoride ions and not containing a polar aprotic solvent before performing the blackening step. Processing method.   The method for blackening a metal surface according to claim 7 or 8, further comprising a post-treatment step of performing a heat treatment at 200 to 450 ° C on the metal whose surface is blackened after the blackening step. .   A metal whose surface obtained by the blackening treatment method according to any one of claims 7 to 9 is blackened.