JPH0432596A - Method for continuously coloring titanium - Google Patents

Abstract

PURPOSE:To prevent the generation of striped color shades on a Ti strip at the time of continuously coloring the strip by the anodization in a liq. colorant by arranging an anode close to the position where the strip enters the colorant to control the anodization reaction caused at this time. CONSTITUTION:A voltage is impressed on a titanium coil 6 through a conductor roll 5, and the coil 6 is continuously immersed in a liq. colorant 3 by an immersion roll 7, anodized and colored. At this time, an anode 10 is arranged close to the position where the coil 6 enters the colorant 3 so that the distance from the coil 6 is controlled to about 5-50mm and the immersion depth to about 20-200mm and connected to the conductor roll 5 with a lead wire. The anodization reaction caused when the coil 6 enters the colorant 3 is controlled by this constitution. As a result, a colored titanium material with the color shades reduced and excellent in appearance is industrially and stably mass-produced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for continuously coloring titanium and titanium alloys with little color unevenness.

<Prior art and its challenges> Titanium (hereinafter referred to as a general term including titanium alloys) has high specific strength and excellent corrosion resistance, and can be chemically colored into various colors by anodizing. Therefore, these characteristics have attracted attention, and in recent years, it is one of the materials whose demand has increased significantly in fields such as building materials.

By the way, until now, technology for continuous operation on an industrial scale has not been established for this coloring treatment of titanium materials by anodizing, and as a result, product demand has been met by batch operations. .

Therefore, in order to meet the demands of the building materials field, which requires a stable supply in terms of quantity, the present inventors developed an industrial method in which titanium coil (strip plate) material is continuously colored by anodizing. We conducted repeated research with the aim of establishing the
No., Japanese Patent Application No. 2-35793, Japanese Patent Application No. 2-41629, etc. These proposed technologies have greatly contributed to the establishment of mass production technology for titanium coloring materials.

However, the inventors of the present invention have continued to conduct studies from various viewpoints since then, and based on the above-mentioned proposed technology, they have developed a method for continuous coloring of titanium in which a titanium coil is continuously anodized in a coloring solution while being unwound. Although it became possible to actually operate this method, we still couldn't help but realize that the product quality remained somewhat unsatisfactory in terms of color unevenness compared to the conventional batch-type anodizing method.

In other words, even when the conditions such as the coloring solution and applied voltage are the same, there is almost no color unevenness in conventional patch-type anodizing treatment, whereas continuous anodizing treatment of the coil If you do this, you will inevitably see Figure 4 (al) and Figure 4 (b).
Color unevenness as shown in Fig. 3 was apt to occur.

For this reason, the purpose of the present invention is to create a "continuous coloring method for titanium" that can stably mass-produce titanium materials with a homogeneous appearance comparable to that of conventional hatch-type anodized materials.
The goal was to establish the

Means for Solving the Problems> In order to achieve the above object, the present inventors first developed a "product obtained by a coloring method using continuous anodic oxidation of titanium coils."
(A) The striped color unevenness shown in Figure 4 (a) is caused by the following:
This occurs due to changes in the conditions of the coloring reaction (referred to as "liquid surface reaction") that occurs the moment the titanium coil enters the coloring liquid.

(B) The polka dot-like color unevenness shown in FIG. 4 (bl) is caused by air bubbles generated by the coloring reaction.

I have come to the conclusion that this is the case.

In other words, in the case of the batch type anodizing method, as shown in Fig.
It is sufficient to apply a voltage between the electrode and the counter electrode (4) for anodic oxidation, but in the case of continuous coloring method, a conductor roll (5) is used as shown in Figure 6. It is necessary to anodize the titanium coil (6) while continuously immersing it in the coloring liquid (3) while applying a voltage (note that 7 in the figure indicates a dipping roll). Therefore, in the case of the continuous coloring method, a coloring reaction occurs from the moment the titanium coil (6) enters the coloring liquid (3). At this time, if the liquid level of the coloring liquid (3) is completely stationary and the titanium coil (6) enters the coloring liquid (3) smoothly at a constant speed, there will be a problem of striped color unevenness. However, in reality, the liquid level of the coloring liquid (3) is more or less constantly fluctuating, so the conductor roll (5) is unavoidable.
) to the liquid level (indicated by l in FIG. 6), which leads to voltage fluctuations, resulting in a pulsating color reaction with varying strengths.

Furthermore, as shown in Fig. 7, on the side where the titanium coil (6) enters the coloring liquid (3), bubbles (8) are formed due to the coloring reaction of titanium, which is thought to be Ti+2N○3--Ti02+ 2 No□+ 26. This rises to the surface of the liquid and forms a layer of foam (9). The titanium coil (6) is also anodized while passing through the foam layer (9), but since the foam is a mixture of liquid and gas, the foam layer (9) and the titanium coil (6) are anodized. The anodic oxidation reaction (coloring reaction) that occurs when the two come into contact with each other is much more uneven and unstable than that in liquid.

In titanium anodic oxidation, even if the voltage is adjusted to be constant throughout, as shown in Figure 8, the reaction occurs most intensely at the moment the voltage is applied, and a large electrolytic current flows. Since this reaction progresses rapidly within a few seconds, the electrolytic current quickly decreases. Applying this to anodic oxidation in the continuous coloring method, it is thought that the most intense coloring reaction occurs where the titanium coil enters the coloring liquid, and the weakest reaction occurs where the titanium coil exits the coloring liquid. . Moreover, since the electrical resistance of titanium is quite high, the voltage drops noticeably with increasing distance from the point of contact between the conductor roll and the titanium coil.

Therefore, the tendency for the reaction to occur more vigorously at "the location where the titanium coil enters the coloring liquid" than at other locations is further strengthened.

In this way, in anodic oxidation in the continuous coloring method, the moment the titanium coil enters the coloring liquid, the most intense coloring reaction that affects the final color tone occurs, but because the liquid level is oscillating. Voltage fluctuations due to changes in the distance from the conductor roll to the liquid surface occur in this area, which is the biggest cause of striped color unevenness, and when the coil passes through a layer of bubbles formed on the liquid surface. Since a vigorous, non-uniform, and unstable coloring reaction occurs during this process, it is assumed that this is also a cause of promoting striped color unevenness.

On the other hand, it was speculated that the polka dot-like color unevenness was caused by the NO2 gas generated by the coloring reaction forming bubbles and adhering to the coil surface, thereby locally inhibiting the coloring reaction.

Therefore, the present inventors believe that in order to solve the color unevenness problem that has been pointed out in the titanium continuous coloring method, it is essential to have a plain text that prevents the "violent reaction at the moment the titanium coil enters the coloring liquid." As a result of further research in search of specific measures, we found that ``by placing an anode near the surface of the color-forming liquid where the titanium coil penetrates into the color-forming liquid, violent reactions immediately after the coil is immersed can be effectively prevented. The full-fledged coloring reaction begins after the coloring liquid has penetrated into the coloring liquid to a certain extent. It was found that if the coloring solution is stirred at the time of coloring, the occurrence of polka dot-like color unevenness, which tends to decrease to some extent even with the above-mentioned means, can be more effectively suppressed.

This invention was made based on the above findings, etc. [When a titanium coil (strip plate) is continuously colored by anodizing treatment in a coloring solution, as shown in FIG. An anode QOI is placed near the position where (6) enters the coloring liquid (3) to suppress the anodic oxidation reaction that occurs at the same time as the coloring liquid (6) enters the coloring liquid (3). It is characterized by the fact that the occurrence of color unevenness can be prevented as much as possible by also carrying out stirring.

Here, as the coloring liquid, it is preferable to use a molten material containing one or more of nitrates, nitrites, and dichromates as main components, as it can ensure a uniform and stable coloring effect. be.

As mentioned above, in order to prevent striped color unevenness in particular, it is necessary to prevent a violent reaction at the moment the titanium coil enters the coloring liquid, and to ensure that the coloring reaction starts only after the titanium coil has entered the coloring liquid to a certain extent. If this can be achieved, it should be possible to obtain a product with no color unevenness, just as with the batch method, but by placing the anode in the area where the titanium coil enters the coloring liquid, this purpose can be fully achieved. can be achieved.

Fig. 2 is a schematic diagram showing an example of the shape and arrangement position of the anode α, and the anode shape is a rectangular cylinder, but there are no particular restrictions on the shape or size of the anode. . However, in this case, the distance between the titanium coil (6) and the anode 0 and the immersion depth of the anode (II) are problematic.

Regarding the former, the narrower the spacing, the easier it is to suppress a violent liquid level reaction, but if the spacing is too narrow, the titanium coil (6)
), and there is also a risk that the generated bubbles will accumulate and overflow to the upper part of the anode α0. On the other hand, if the interval is too wide, the effect of suppressing the liquid surface reaction will be reduced. Therefore, the distance between the titanium coil (6) and the anode αω is usually
It is appropriate to adjust the power to about 5 to 50W. Regarding the latter anode immersion depth, if it is too shallow, the effect of suppressing the liquid surface reaction will be small, and if it is too deep, electricity will be wasted, so the immersion depth is usually about 20 to 200 m. is appropriate.

Furthermore, as a material for the anode αω, it is not preferable to use a material that is eluted by electrolysis.As a result of research, when using molten nitrate as the coloring liquid, stainless steel and Ni cannot be used because they elute too much, and titanium is preferable. That's what I found out.

There are no particular restrictions on the means for applying voltage to the anode 0ω, but simply connecting the conductor roll (5) and the anode αΦ with a lead wire as shown in FIG. 1 is sufficient. The voltage applied to this anode is not particularly limited either, but if it is too low, it will not be possible to effectively suppress the intense liquid level reaction of the titanium coil, and if it is too high, it will cause damage to the surface of the anode itself. Care must be taken, as the electrolytic current increases and electricity is wasted.

In addition, in order to prevent the harmful effects (causing color unevenness, etc.) caused by the bubble layer (9) that tends to accumulate on the surface of the coloring liquid, an opening aυ is formed on the side surface of the anode αω as shown in Figure 3. In addition to this, it is also effective to employ means for blowing hot air or cold air from above using a nozzle (2) or the like to expel the "generated and floated bubbles" to the outside through the opening αυ.

Furthermore, stirring the coloring liquid to prevent air bubbles from adhering to the coil surface is an effective means of suppressing the occurrence of uneven coloring, but it is recommended to use a mechanical stirrer as the stirring method. It is convenient and preferable. Of course, it goes without saying that a sufficient effect of preventing color unevenness can also be obtained by using a "stirring means such as using a pump to circulate the coloring liquid and spray it onto the coil surface."

Next, the effects of the present invention will be explained in more detail with reference to Examples.

<Example> A pure titanium carp (JIS JIS Class 1 equivalent material) with a plate thickness of 0.2 tll and a width of 300 m was prepared, and a mixed molten salt bath of KNO2 and NaN0t (weight ratio 2:1, temperature 300°C) was added to the coloring liquid. Color development tests for various color tones were carried out using the "continuous anodization method according to the present invention (method of the present invention)" used as a method and the "continuous anodization method proposed previously (comparative method)" using the same coloring solution. carried out.

In addition, the titanium coil material is made of [1%HF + 15%H] in advance.
NCh (50℃)] and [110%H2S0450℃)
] and then subjected to the test.

Further, in the method of the present invention, an apparatus as shown in FIG. 1 in which an anode of the type shown in FIG. 3 is arranged was used, and in the comparative method, an apparatus shown in FIG. 6 was used.

Furthermore, in order to investigate the effect of suppressing polka dot-like color unevenness, in both the method of the present invention and the comparative method, a part of the coloring liquid was stirred using an electric stirrer.

The results of these color development tests, together with other test conditions, are
Shown in the table.

As is clear from the results shown in Table 1, it was found that placing the anode at a predetermined location and stirring the coloring liquid has a remarkable effect on suppressing color unevenness in products, and the method of the present invention can reduce color unevenness. It can be confirmed that a high quality colored titanium material with almost no coloring can be obtained.

Although only an example in which a molten salt is used as the coloring liquid is shown here, it goes without saying that similar effects can be obtained even when the coloring liquid is an aqueous solution (for example, 5% Na5PO, aqueous solution).

Summary of Effects> As explained above, according to the present invention, it is possible to industrially stably mass-produce colored titanium materials with an excellent appearance with almost no color unevenness, which is an extremely important feature in industry. Useful effects are produced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the titanium continuous coloring method according to the present invention. FIGS. 2 and 3 are schematic diagrams showing different examples of anodes applied to the method of the present invention. FIG. 4 is an explanatory diagram of color unevenness observed in a colored titanium material obtained by continuous anodic oxidation.
) and FIG. 4(b) show different examples. FIG. 5 is an explanatory diagram of a titanium coloring method using a batch type anodic oxidation method. FIG. 6 is an explanatory diagram of a titanium coloring method using a continuous anodic oxidation method. FIG. 7 is a conceptual diagram illustrating the cause of color unevenness. FIG. 8 is a graph showing an example of changes in electrolytic current over time in anodizing titanium. In the drawings: 1... Titanium material, 2... Treatment tank. 3...Coloring liquid, 4...Counter electrode. 5... Conductor roll. 6...Titanium coil 8...Bubble 10...Anode. 12... Nozzle. 7...Immersion roll 9...Layer of foam. 11...Opening applicant Nippon Stainless Co., Ltd.

Claims (4)

[Claims] (1) When continuously coloring a titanium or titanium alloy strip by anodizing in a coloring solution, an anode is placed near the position where the strip enters the coloring solution. A continuous coloring method for titanium that is characterized by suppressing the anodic oxidation reaction that occurs simultaneously with invasion. (2) The coloring liquid is nitrate, nitrite, and dichromate.
2. The continuous coloring method for titanium according to claim 1, wherein the method is a molten material containing at least one species as a main component. (3) The continuous coloring method for titanium according to claim 1 or 2, wherein the anodizing treatment is performed while stirring the coloring liquid. (4) Claim 1, wherein the anodizing treatment is performed while blowing gas from above the liquid level to eliminate bubbles generated at the entry portion of the coil.
4. The method for continuously coloring titanium according to any one of 3 to 3.