JPS6213433B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for sharpening when chemically etching the surface of steel materials such as ferrous alloy steel such as stainless steel or ordinary steel using an etching solution made of chemicals such as ferric chloride solution. The present invention relates to an etching pretreatment method that provides a sharp etching pattern and enables deep etching.

Chemical etching is a process in which the surface of steel materials such as ferrous alloy steel such as stainless steel or ordinary steel is treated with an etching solution made of chemicals such as ferric chloride solution to create an uneven pattern. Etching is the process of chemically dissolving a part of the surface with an etching solution to create irregularities on the surface, and the process usually involves applying resist ink that is not immersed in the etching solution to the surface of the steel material to be etched. is coated in a desired pattern by photoprinting or screen printing and dried to form a film, and then the steel material with the resist ink film pattern formed on its surface is etched with a ferric chloride solution or the like. Etching is performed by immersion treatment in which the steel material is immersed in the etching solution, or by spray treatment in which the etching solution is sprayed onto the steel material. is not corroded and dissolved by the etching solution, and the portions where the resist ink film is not formed are corroded and dissolved to form an uneven pattern. To specifically illustrate this, Fig. 1 is a cross-sectional view of a steel material etched by a conventional method, and 1 is a steel material 2.
A resist ink film 3 is formed by coating the resist ink film on the surface of the resist ink film 1, and 3 is a boundary between the etched surface 4 that has been corroded and dissolved in the etching process and the non-etched surface 5 that has not been corroded and dissolved under the resist ink film 1. , l indicates the etching depth, and the etching surface 4 is etched by the etching process.
is corroded and dissolved to form an uneven pattern, but in this process, the boundary portion 3 between the corroded portion and the uncorroded portion is corroded more than necessary as the etched surface 4 corrodes and dissolves. Put it away. In the etching process, the sharpness of the etched uneven pattern is determined by the boundary portion 3, but if the boundary portion 3 is corroded more than necessary and the lines are disordered, it becomes difficult to form a sharp uneven pattern. In particular, when etching is performed so that the etched surface 4 becomes deep, the corrosion of the boundary portion 3 becomes severe, and the lines of the uneven pattern become more disordered and lack sharpness. For this reason, the etching depth l is limited. Conventionally, etching is usually done to a depth of 20 to 70μ, but the limit for the etching depth l is 200 to 300μ, and sharpness is particularly required for the uneven pattern. Naturally, as the etching depth l becomes shallower, various problems arise.

As a result of various studies conducted by the present inventors in order to solve these problems, we found that if an oxide film is formed on the surface of the steel material to be etched to improve the adhesion between the surface of the steel material and the resist ink, During the etching process, the boundary between the etched surface and the non-etched surface on which the resist ink film is formed is prevented from being corroded and dissolved by the etching solution, resulting in a clear and deeply etched uneven pattern. It was found that it was possible to obtain
The invention has been completed.

That is, in the present invention, before etching the surface of the steel material with an etching solution made of chemicals,
After immersing a steel material in an oxidizing solution to form an oxide film on the surface of the steel material, a pretreatment process is performed in which resist ink is applied in a predetermined pattern on the oxide film and dried to form a resist ink film. The present invention provides an etching pretreatment method characterized by the following.

Hereinafter, the etching pretreatment method according to the present invention will be explained in detail with reference to the drawings.

Figure 2 is a cross-sectional view showing an example of a steel material pretreated and etched by the method of the present invention, and Figure 3 is a mixed aqueous solution of chromic acid and sulfuric acid in order to form an oxide film on the surface. Figure 4 is a potential difference-time curve diagram showing the change over time in the potential difference between the surface potential of stainless steel immersed in an oxidizing solution and the potential of a reference electrode immersed in the oxidizing solution. Fig. 5 is a schematic diagram of an etching pattern formed by etching SUS304 stainless steel pretreated by the method of the present invention; FIG. 6 is a schematic diagram of an etching pattern formed by etching SUS304 stainless steel using a conventional method.

In the drawing, 1 is a resist ink film formed by applying it to the surface of a steel material 2, 3 is an etched surface 4 that has been corroded and dissolved in the etching process, and a non-etched surface that has not been corroded and dissolved under the resist ink film 1. 5, 6 is an oxide film formed on the surface of the steel material 2 by immersing the steel material 2 in an oxidizing solution, and A is an inflection point indicating the inflection potential difference at which the oxide film changes to a desired color tone. Point B is the extreme termination potential difference of the tonal range.

In the method of the present invention, an oxide film 6 is formed on the surface of the steel material 2 as shown in FIG.
This method uses a chemical coloring method that is commonly used to color the surface of stainless steel.These chemical coloring methods include alkaline oxidation method and acid oxidation method. When stainless steel is immersed in the stainless steel, an oxide film is formed on the surface, and the color tone of this oxide film varies depending on the thickness of the film, so by adjusting the thickness of the oxide film that is formed, it can be colored in various tones. This method is used to color ferrous alloy steel, including stainless steel, and the most commonly used method is to use a mixed aqueous solution of chromic acid and sulfuric acid as the coloring solution. This is a method of forming an oxide film. In order to form an oxide film on the surface of iron-based alloy steel and color it by immersing it in a coloring liquid made of an oxidizing liquid, a method for controlling the color tone by adjusting the thickness of the oxide film was proposed in Japanese Patent Application Laid-Open No. No. 48-11243 discloses a method for treating chromium alloys, and JP-A-49-21339 discloses a method for treating chromium alloys. Monitor the potential difference between the surface of the stainless steel to be colored and a reference electrode (such as a saturated aqueous electrode or platinum electrode) in the mixed aqueous solution, and determine the potential difference that will give the desired color tone to the stainless steel as shown in Figure 3. The change in potential difference with respect to time measured with respect to a reference electrode, i.e. the change in potential difference over time, the potential difference-time curve, which is the inflection potential difference that changes to the desired color tone, the inflection point A and the ending potential difference at the end of that tone range. In this method, coloring is controlled by removing colored stainless steel from a coloring solution when the potential difference changes from an inflection point A to a potential difference B of a desired color according to a predetermined amount. , the coloring is controlled by monitoring the thickness of the oxide film using a potential difference.

In the method of the present invention, the purpose is not to color the surface of iron-based alloy steel such as stainless steel, but to form an oxide film to improve adhesion with resist ink. A thin oxide film is formed on the surface of steel materials such as steel or ordinary steel using an oxidizing solution similar to the coloring solution used for coloring stainless steel, etc., and resist ink is applied on top of it in the desired pattern and dried. This is a method in which a film of resist ink is formed on the surface of the steel material.If the original surface appearance needs to be maintained, there is no need to make the oxide film so thick that it would color the surface of stainless steel, etc. Immediately before the potential difference between the potential and the potential of the platinum reference electrode or the saturated Amane reference electrode reaches the inflection point A in the potential difference-time curve in Figure 3, the All you have to do is take out the steel.

In the case of stainless steel, coloring begins at inflection point A of the potential difference-time curve in Figure 3, so before the potential difference reaches inflection point A, the thickness of the oxide film formed is so thick that the surface is colored. I'm not used to it. Figure 3 shows the potential difference over time between the surface of stainless steel and the reference electrode when stainless steel is immersed in a mixed aqueous solution of chromic acid and sulfuric acid.
Although it is a time curve, a thin oxide film can be formed on iron-based alloy steel or ordinary steel other than stainless steel by taking out the steel material from the mixed aqueous solution just before reaching the inflection point A of the potential difference-time curve. It is also possible to use acidic oxidizing liquids other than mixed aqueous solutions of chromic acid and sulfuric acid or sodium hydroxide.
It can also be applied to alkaline oxidizing liquids such as a mixed aqueous solution of sodium nitrate.

In the method of the present invention, an oxide film is formed on the surface of a steel material as described above, and then a resist ink that cannot be soaked in by an etching solution such as a ferric chloride solution is applied onto the oxide film in a desired pattern and dried. can be,
The resist ink is applied by the commonly used photoprinting method or screen printing method, and the resist ink is dried by conventional heat drying.

When the steel material 2 pretreated by the method of the present invention is etched with an etching solution, the non-resist surface 5 on which the resist ink film 1 is formed and the etched surface 4 are separated.
Since the boundary portion 3 between the two is not corroded and dissolved by the etching solution, there is no disturbance in the lines of the uneven pattern.
A sharp uneven pattern can be obtained, and the etching depth can be increased. For example, as shown in FIG. 5, when etching is performed using the method of the present invention after pretreatment, there is no disturbance in the lines of the boundary portion 3 and a sharp etched pattern is obtained, but as shown in FIG. Boundary area 3 is for those etched using the conventional method without pre-treatment.
The lines are disorganized, creating an etched pattern that lacks clarity. 5 and 6 are etched to a depth of 800 μm.

The method of the present invention will be further explained below with reference to Examples.

Example 1 Using SUS304 stainless steel and SUS430 stainless steel as the test materials, chromic anhydride 200 at a liquid temperature of 85°C
This test material is immersed in an oxidizing solution consisting of a mixed aqueous solution of 600 g/g/- of sulfuric acid, and the potential difference between the surface potential of the test material in the oxidizing solution and the potential of the platinum reference electrode immersed in the oxidizing solution is determined. Measure the potential difference-time curve, which is the change over time, and find the inflection point A of the potential difference-time curve.
Immediately before reaching the oxidizing solution, the test material was removed from the oxidizing solution to form a thin oxide film on the surface of the test material. Resist ink (Resist ink No. 906 manufactured by Fuji Pharmaceutical Co., Ltd.) was applied in a predetermined pattern by screen printing on the oxide film of the test material, which had been formed on the surface by such treatment. After, 100℃
The resist ink was dried by heating for 2 minutes to form a resist ink film. Next, an etching process was carried out by heating an etching solution consisting of a 38% by weight ferric chloride aqueous solution at 60°C and spraying it on the test material, and the etching process was continued by spraying this etching solution for 10 minutes. The depth was set to 800-1000μ. After spraying, washing with water and removing the resist ink film with a 3% by weight aqueous sodium hydroxide solution, we investigated the boundary area 3 shown in Figure 2, and found that the boundary area 3 had not been corroded or dissolved at all. First, it was possible to obtain a sharp uneven pattern without any disturbance in the lines of the uneven pattern.

Example 2 A 1 mm thick SUS304 stainless steel plate was used as the test material, and 150 g/- of sodium hydroxide at a liquid temperature of 110°C was used.
This test material was immersed in an oxidizing solution consisting of a mixed aqueous solution of 50 g of sodium nitrate, and the thickness of the oxide film formed on the surface of the immersed test material was controlled in the same manner as in Example 1, and the potential difference was adjusted. - The specimen was removed from the oxidizing solution just before reaching the inflection point A of the time curve. After applying resist ink (Resist Ink KMER manufactured by Kodatsu Co., Ltd.) in a predetermined pattern on the oxide film of the sample material treated in this way to form an oxide film on the surface, it was heated at 120°C. It was heated and dried for 5 minutes to form a resist ink film. Next, in the same manner as in Example 1, etching treatment and removal of the resist ink film were performed.

As a result, as shown in Figure 4, the cross section of the sample material showed that the etched surface 4 was completely corroded and dissolved and punched out to the back surface, and even though it was deeply etched, the boundary part 3 was not corroded and dissolved. First, the etched pattern retained sharp lines.

Example 3 A common steel plate with a thickness of 4 mm was used as the test material, and the test material was immersed in an oxidizing solution consisting of a mixed aqueous solution of 100 g of chromic anhydride/500 g of sulfuric acid at 70°C. The thickness of the oxide film formed on the surface of the sample was controlled in the same manner as in Example 1, and the sample was taken out from the oxidizing solution just before reaching the inflection point A of the potential difference-time curve. After applying resist ink (Selicor resist ink PC744 manufactured by Teikoku Ink Manufacturing Co., Ltd.) in a predetermined pattern by screen printing on the oxide film of the sample material treated in this way to form an oxide film on the surface. A resist ink film was formed by heating and drying at 130° C. for 1 minute. After etching and removing the resist ink film in the same manner as in Example 1, the boundary portion 3 shown in FIG. 2 was investigated.

As a result, although the etching depth reached approximately 1500 μm, the boundary portion 3 was not corroded and dissolved, and a sharp etched pattern was obtained without any disturbance of the lines of the etched uneven pattern. As detailed above, in the etching pretreatment method according to the present invention, before etching the steel material, an oxide film is formed on the surface of the steel material to improve the adhesion of the resist ink, and then the resist ink is applied. This is a pre-etching treatment method that performs pre-treatment by coating and drying. If an oxide film is formed on the surface of the steel material, the boundary between the etched surface and the non-etched surface will be affected by the etching solution during the etching process. Since it prevents etching from being corroded and dissolved, it is possible to prevent the lines of the uneven etching pattern from becoming disordered, and it is possible to obtain a sharp etching pattern. Moreover, it has excellent advantages such as deep etching is possible. and its industrial value is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a steel material that has been etched by a conventional method, FIG. 2 is a cross-sectional view of an example of a steel material that has been pre-treated and etched by the method of the present invention, and The figure shows the change over time in the potential difference between the surface potential of stainless steel immersed in an oxidizing solution consisting of a mixed aqueous solution of chromic acid and sulfuric acid to form an oxide film on the surface and the potential of a reference electrode immersed in the oxidizing solution. Potential difference-time curve diagram showing 4th
The figure is a sectional view showing another example of steel material pretreated and etched by the method of the present invention.
Figure 5 shows the results of pretreatment using the method of the present invention.
A schematic diagram of an etching pattern formed by etching SUS304 stainless steel. FIG. 6 is a schematic diagram of an etching pattern formed by etching SUS304 stainless steel by a conventional method. 1... Resist ink film, 2... Steel material, 3
...Boundary portion, 4...Etched surface, 5...Non-etched surface, 6...Oxide film, l...Etching depth, A...Inflection point showing the inflection potential difference, B...
Termination potential difference.

Claims (1)

[Scope of Claims] 1. Before etching the surface of the steel material with an etching solution made of chemicals, the steel material is immersed in an oxidizing solution to form an oxide film on the surface of the steel material, and then the surface of the steel material is etched. An etching pretreatment method comprising applying resist ink in a predetermined pattern and drying to form a resist ink film. 2 Claim 1 in which the steel material is iron-based alloy steel
The etching pretreatment method described in section. 3. The etching pretreatment method according to claim 2, wherein the iron-based alloy steel is stainless steel. 4. The etching pretreatment method according to claim 1, wherein the steel material is ordinary steel. 5. The etching pretreatment method according to any one of claims 1 to 4, wherein an acidic oxidizing solution is used as the oxidizing solution. 6. The etching pretreatment method according to claim 5, wherein a mixed solution of chromic acid and sulfuric acid is used as the acidic oxidizing solution. 7. The etching pretreatment method according to any one of claims 1 to 4, wherein an alkaline oxidizing solution is used as the oxidizing solution. 8. Claim 1, in which the oxide film is formed under the control of a potential difference-time curve showing the change over time of the potential difference between the surface potential of a steel material immersed in an oxidizing solution and the potential of a reference electrode in the oxidizing solution. 7. The etching pretreatment method according to any one of 7 to 7. 9. The etching pretreatment method according to claim 8, wherein the steel material is removed from the oxidizing solution immediately before the potential difference reaches the inflection point (A) in the potential difference-time curve. 10 Any one of claims 1 to 9 in which resist ink is applied by photoprinting method
The etching pretreatment method described in section. 11. The etching pretreatment method according to any one of claims 1 to 9, wherein the resist ink is applied by a screen printing method.