JPH09263959A - Method for color-developing titanium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily develop titanium from black of low brightness to various hues by treating the surface of a metallic titanium by an alkali soln. SOLUTION: A metallic titanium is immersed in an alkali soln. in a reaction vessel, and the inside of the vessel is heated to a prescribed temp. by an outside heater or the like. The alkali soln. is, e.g. composed of individual KOH, NaOH, LiOH or the like, or a mixed soln. thereamong. The heating temp. is preferably regulated to the range of 40 to 200 deg.C. In this temp. range, in accordance with the increase of the temp., its hue changes to gray, brown, black, sky blue or the like in order. Thus, by selecting the heating temp. in accordance with the desired color and holding the same, the color can be developed. The metallic titanium subjected to the treatment by the alkali soln. is furthermore subjected to nitriding treatment. In this way, the controllability and reproducibility are made good, and moreover, excellent film adhesion can be obtd.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a titanium coloring method used for producing black titanium and colored titanium having various tones.

[0002]

2. Description of the Related Art The titanium surface develops black or various chromatic colors by changing the thickness of an oxide film covering the surface of metallic titanium or forming a nitride film on the surface. For example, powdery metallic titanium that has been subjected to such a color development treatment is used for coating pigments, printing pigments, coloring materials for fibers, coloring materials for ornaments,
It is used as a cosmetic material, a sintering material, etc.

As a method for blackening metallic titanium, the metallic titanium is immersed in a dilute aqueous solution of hydrofluoric acid to form a black film on the titanium surface (Japanese Patent No. 11902).
No. 52), a method of blackening copper deposited on the titanium surface (Japanese Patent Publication No. 58-23469), a two-step treatment method using sulfuric acid and hydrofluoric acid (Summary of the 77th Metal Surface Technology Association Conference) 184).

Further, as a coloring method for producing a color other than black, there are an atmospheric oxidation method, an anodic oxidation method, a chemical oxidation method, an ion implantation method and the like.

[0005]

Among these titanium coloring methods, the blackening treatment method has a problem that the black film is peeled off or a heat treatment is required to reduce the brightness. Further, each of the coloring methods for producing a color other than black has the following problems.

The atmospheric oxidation method is a method of heating titanium metal in the atmosphere or oxygen using an electric furnace or the like. Since the surface is colored by the light interference effect of the titanium surface oxide film grown by heating, the color tone can be changed depending on the thickness of the oxide film, but the color variation is small, and the uniformity and reproducibility are not good.

The anodic oxidation method utilizes a phenomenon in which metallic titanium is used for the anode in the electrolytic cell and an oxide film is formed on the titanium surface when a direct current is passed at a constant current. When the film thickness is constant, no current flows, and since the voltage and film thickness are proportional, the color tone is rich, the reproducibility of each color is good, and control is easy, but black is not obtained. In addition, since the color tone changes due to fingerprints and the abrasion resistance is poor, the durability of the coating is low.

The chemical oxidation method is a method in which metallic titanium is boiled in an inorganic acid to form an oxide film and the color is developed by the light interference effect. This method is simple,
It takes a long time to grow the film and is low in efficiency. Also, there are few color variations.

As the ion implantation method, there is a method of producing titanium nitride by heating in nitrogen, for example. Although this nitrided film has a golden color, it has drawbacks such as no variation in color tone.

An object of the present invention is to provide a titanium coloring method capable of easily producing black titanium having low lightness and good film adhesion and colored titanium having a wide variety of colors and having good film adhesion at a low temperature close to room temperature. To do.

[0011]

In order to achieve the above object, the titanium coloring method of the present invention is to treat the surface of metallic titanium with an alkaline solution.

As the alkaline solution, KOH, NaOH,
An aqueous solution of an alkali metal such as LiOH or an aqueous ammonia solution can be used alone or in combination.

In the titanium coloring method of the present invention, for example, within the processing temperature range of 40 ° C. to 200 ° C., the color tone changes in order to gray, brown, black, sky blue, etc. as the processing temperature rises. This is because when the surface of metallic titanium is treated with an alkaline solution, fine irregularities that easily absorb light are formed on the titanium surface, and the irregularity shape changes depending on the treatment temperature and exhibits various colors. Is considered to be. Further, it is considered that, by further advancing the reaction, the amorphous titanium compound in the surface layer grows to give a sky-blue coloring.

The fine irregularities formed on the metallic titanium surface by the alkaline solution treatment were found by SEM observation to be a film of a fibrous structure grown so as to cover the metallic surface. It is considered that this film has a porous structure in which the structure is complex like fibers, because metallic titanium is dissolved by alkali and deposited on the surface and oxides of alkali titanium are formed. This film is not only suitable for color development on the surface irregularities, but also has better adhesion than conventional films. Again, this is believed to be due to the fibrous structure of the coating.

Further, when the metallic titanium whose surface is colored black by the alkaline solution treatment is subjected to the nitriding treatment, the brightness of the black is further lowered. It is considered that this is because the film of the fibrous structure on the surface changed to brown titanium nitride and the blackening progressed due to the fine structure. When metallic titanium whose surface is colored sky blue by alkaline solution treatment is subjected to nitriding treatment, the sky blue color changes to grayish white.

Thus, by treating metallic titanium with an alkaline solution and then nitriding it if necessary, black titanium having low lightness and good film adhesion can be easily produced by low temperature operation close to room temperature. It In addition, a film with rich color tone and high film adhesion can be easily manufactured by low temperature operation close to room temperature. Due to their fine fibrous structure, these films have excellent wear resistance and the like, and have high durability. Furthermore, since the color tone is controlled by the temperature, the controllability and reproducibility in film formation are also good.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

In the first step, metallic titanium is immersed in the alkaline solution in the reaction vessel, and the vessel is heated to a predetermined temperature by an external heater or the like.

The alkaline solution is, for example, KOH, NaOH,
It is a single solution or a mixed solution of an aqueous solution of an alkali metal such as LiOH and an aqueous solution of ammonia.

The concentration of the alkaline solution is not particularly limited,
If it is low, the reaction takes a long time, and if it is high, the reaction is quick and control becomes difficult. In the case of an aqueous solution of an alkali metal such as KOH, NaOH or LiOH, the range is preferably 1 to 10 mol / liter, and in the case of an aqueous ammonia solution, the range is preferably 1 to 15 mol / liter.

The metallic titanium may be pure titanium or titanium alloy. The shape thereof may be any of sponge-like, plate-like, lump-like, powder-like (spherical, scale-like), and the shape thereof is not limited.

The ratio of the alkali solution and metallic titanium is not particularly limited as long as metallic titanium is immersed in the solution.

From the viewpoint of alkali resistance, the reaction vessel is
Stainless steel or Teflon is preferable. Further, in order to keep the temperature in the container constant, it is desirable to have a stirrer. Further, a closed container is desirable in order to prevent the vapor from scattering and reducing the water content during heating.

The heating temperature is the factor that most affects the color development of titanium metal. It is desirable that the heating temperature is in the range of 40 to 200 ° C. for the reason of operation that if the heating temperature is low, the reaction takes a long time, and if it is high, the reaction is quick and control becomes difficult. Then, within this temperature range, the color tone changes in order to gray, brown, black, sky blue, etc. as the temperature is increased. Therefore, by selecting and maintaining the heating temperature according to the desired color, the color can be developed. Especially when black is desired, the temperature range of 60 to 90 ° C. is desirable.

The reason why the color development is controlled by the heating temperature is that it affects the solubility of titanium and the reaction rate thereafter. A film is formed by the reaction, and the color tone changes depending on the shape and thickness of the film.

The heating time affects the formation of the film as well as the heating temperature. When the temperature is constant and the heating time is changed, the film formation is insufficient for a short time and becomes non-uniform, and the color tone changes greatly until it becomes uniform. When the heating time is further extended, a slight change in color tone is observed. From this viewpoint, it is desired that the heating temperature be set within the range of 2 to 5 hours. That is, when the heating time is up to 2 hours, the formation of the film is insufficient and the film is likely to be non-uniform, and the color tone is significantly changed, so that the color control is difficult. It is easy to control the color after 2 hours because the change in color tone is gradual. However, after 5 hours, the color tone does not change any more.

When the first step is completed, as the second step,
The alkaline solution is removed from the titanium metal that has been treated with the alkaline solution and dried. Examples of methods for removing alkali include filtration, ultrasonic cleaning, decantation and the like.
Drying is 100 ~ 150 ℃ to prevent oxidation of titanium metal.
It is preferable to carry out at a low temperature, and it is desirable to continue for 5 hours or more to completely remove water.

If nitriding is desired, this is performed as the third step. In this treatment, it is desirable to hold titanium metal at 800 to 1200 ° C. for 1 to 5 hours in a nitrogen gas atmosphere. When the treatment temperature is low, nitriding does not proceed, and when it is high, the reaction is too fast and control becomes difficult. A particularly desirable processing temperature is 1000 to 1100 ° C. Regarding the processing time, if this is short, nitriding does not proceed, and if it is long, productivity deteriorates.

[0029]

Next, embodiments of the present invention will be described.

Example 1 112 g of KOH and 5 parts of water were placed in a reactor made of SUS having an internal volume of 1 liter.
00 g was put and stirred to prepare a KOH aqueous solution. A titanium plate (20 mm × 20 mm × 1 mmt) was placed in this and reacted at 100 ° C. for 2 hours. KOH with water after the reaction
The aqueous solution was washed off and dried at 100 ° C. for 20 hours. The surface of the obtained titanium plate was black. When this titanium plate was kept at 1000 ° C. for 1 hour under nitrogen flow, a darker titanium plate was obtained.

Example 2 120 g of NaOH and 500 g of water were placed in a SUS reactor having an internal volume of 1 liter and stirred to prepare an aqueous NaOH solution. 50 g of spongy titanium (average particle size of about 10 mm) was put into this and reacted at 80 ° C. for 4 hours. After completion of the reaction, add Na with water
The aqueous OH solution was washed off and dried at 100 ° C. for 20 hours.
The obtained titanium powder had a black color. When this titanium powder was kept at 1100 ° C. for 2 hours under nitrogen flow, a darker titanium powder was obtained.

Example 3 In a SUS reactor having an internal capacity of 1 liter, 10 mol / liter aqueous ammonia solution and 50 g of titanium powder (spherical, average particle size 70 μm
m) was added and reacted at 150 ° C. for 5 hours. After the reaction was completed, the aqueous ammonia solution was washed off with water and dried at 100 ° C. for 20 hours. The obtained titanium powder had a black color. When this titanium powder was kept at 900 ° C. for 5 hours under nitrogen flow, a darker titanium powder was obtained.

Example 4 112 g of KOH and 5 parts of water were placed in a SUS reactor having an internal volume of 1 liter.
00 g was put and stirred to prepare a KOH aqueous solution. A titanium plate (20 mm × 20 mm × 1 mmt) was placed in this and reacted at 40 ° C. for 5 hours. After the reaction was completed, the KOH aqueous solution was washed off with water and dried at 100 ° C. for 20 hours. The surface of the obtained titanium plate was gray. When this titanium plate was kept at 1000 ° C. for 1 hour under nitrogen flow, a brown titanium plate was obtained.

Example 5 120 g of NaOH and 500 g of water were placed in a SUS reactor having an internal volume of 1 liter and stirred to prepare an aqueous NaOH solution. 50 g of spongy titanium (average particle diameter of about 10 mm) was put into this and reacted at 220 ° C. for 3 hours. After completion of the reaction, N with water
The aOH aqueous solution was washed off and dried at 100 ° C. for 20 hours. The titanium powder obtained had a light blue color. When this titanium powder was kept at 1100 ° C. for 2 hours under nitrogen flow,
An off-white titanium powder was obtained.

Example 6 A 0.1 mol / liter aqueous ammonia solution and 50 g of titanium powder (spherical, average particle size 70 μm) were placed in a SUS reactor having an internal volume of 1 liter.
m) was added and reacted at 150 ° C. for 2 hours. After the reaction was completed, the aqueous ammonia solution was washed off with water and dried at 100 ° C. for 20 hours. The titanium powder obtained had a gray color. When this titanium powder was kept at 900 ° C. for 5 hours under nitrogen flow, a pale blue titanium powder was obtained.

Comparative Example 1 112 g of KOH and 5 parts of water were placed in a SUS reactor having an internal volume of 1 liter.
00 g was put and stirred to prepare a KOH aqueous solution. Add 50 g of titanium powder (spherical, average particle size 70 μm) to this 2
The reaction was performed at 5 ° C. for 8 hours. After the reaction was completed, the KOH aqueous solution was washed off with water and dried at 100 ° C. for 20 hours. The obtained titanium powder did not change before and after the reaction.

KOH1 was added to a SUS reactor having an internal capacity of 1 liter.
12 g and 500 g of water were added and stirred to prepare a KOH aqueous solution. 50g of titanium powder (spherical, average particle size 70μ
m) was added and reacted at 250 ° C. for 2 hours. After the reaction was completed, the KOH aqueous solution was washed off with water and dried at 100 ° C. for 20 hours. The obtained titanium powder was white and titanium dioxide was produced.

Examples 1 to 3 relate to black titanium. In order to evaluate the brightness of the black titanium of Examples 1 to 3, a spectrocolorimeter (Minolta CM-3500d) was used for investigation. Table 1 shows the results. It is L * <30 that the black color is recognized as good. In Examples 1 to 3, L * was 30 or less only by the alkali treatment, and black titanium having low brightness was obtained. By further performing the nitriding treatment, L * is reduced to about 10.

Examples 4 to 6 relate to pigmented titanium. In these examples, colored titanium having a brown color, a gray color, or a blue color was obtained. Table 2 shows the results.

The results of Comparative Examples 1 and 2 are shown in Table 3.
In Comparative Example 1, the reaction did not proceed because the reaction temperature was low. Further, in Comparative Example 2, since the reaction temperature was too high and the reaction was performed in a state in which metallic titanium was dissolved, titanium dioxide was produced.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

As is apparent from the above description, the titanium coloring method of the present invention can easily develop from black of low lightness to colors of various tones by treatment with an alkaline solution at a relatively low temperature. . In addition, since the color is controlled by the processing temperature, controllability and reproducibility are good, and further excellent film adhesion can be obtained.

Claims (3)

[Claims] 1. A titanium coloring method, characterized in that the surface of metallic titanium is treated with an alkaline solution. 2. The titanium coloring method according to claim 1, wherein the titanium surface is colored in a color corresponding to the set temperature by setting the treatment temperature in the range of 40 to 200 ° C. 3. The titanium coloring method according to claim 1, wherein the titanium metal after the treatment with the alkaline solution is further subjected to a nitriding treatment.