JPH01168893A - Method for coloring stainless steel sheet - Google Patents

Abstract

PURPOSE:To color a material with superior uniformity of a color tone and satisfactory reproducibility by carrying out electrolysis while controlling AC current density in accordance with the transfer length of the material passed through a cell. CONSTITUTION:When a stainless steel sheet as a material to be colored is subjected to oxidation coloring by AC electrolysis in an electrolytic cell filled with a soln. contg. chromic acid and sulfuric acid, AC current density is controlled in accordance with the transfer length of the material passed through the cell from the inlet of the cell. The supply of AC is calculated by properly determining a coefft. of correction in proportion to the transfer length. A colored stainless steel sheet obtd. by this method is applicable to any of building materials for interior and exterior finish works.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for coloring stainless steel cut plates for building materials, which has excellent surface uniformity of color tone and good reproducibility.

<Prior Art> As a prior art, Japanese Patent Publication No. 58-25747 discloses a technique for moving a colored liquid in the same direction in accordance with the moving speed of a material to be colored, as one of the coloring control methods. but,
The technique described above involves coloring continuous steel strips or molded parts on hangers placed between straightening nets.

The present invention is characterized by coloring the stainless steel plate of the cut plate, and since the cut plate has a front end and a rear end, the content of the prior art regarding continuous steel strips is applied to improve the uniformity and reproducibility of the coloring. The present invention proposes a means for ensuring uniformity and reproducibility of coloring by moving the stainless steel plate of the cut plate.

<Problems to be Solved by the Invention> The present invention solves this drawback, since it was not possible to ensure the uniformity and reproducibility of coloring when a cut plate was used as the material to be colored, unlike continuous steel strips. This was done in order to provide a technology that can overcome this problem and ensure stable and continuous coloring uniformity and reproducibility.

Means to solve problems〉 The inventors have investigated the uniformity of coloring of stainless steel sheets.

As a result of intensive research on reproducibility, we succeeded in achieving the objective by controlling the alternating current density by taking into account the current flow to the surface opposite to the surface to be colored and the position of the material to be colored in the alternating current electrolytic bath. gained knowledge that it is possible to reach
The present invention was made based on this knowledge.

In the present invention, when a material to be colored, such as a stainless steel plate, is subjected to alternating current electrolysis in a solution bath containing chromic acid and sulfuric acid to give oxidation coloring, an inlet of the material to be colored passing through the solution bath is provided. This is a method for coloring a stainless steel sheet, which is characterized by controlling alternating current density in accordance with the length of movement from the base.

It is well known that for uniform coloring by alternating current electrolysis, it is important to keep the current density per unit area of the material to be constant, but the current ff1 (A) to be applied cannot be determined quantitatively. It was not clear.

As a result of many years of research into the uniform coloring properties of alternating current electrolysis, the inventors of the present invention have determined that the current flow to the surface opposite to the surface to be colored and the passing position of the material to be colored in the alternating current electrolytic cell have been determined. We found that the relationship between the currents to be applied can be expressed as follows.

f(x) −α1oWx (k−(k−1) −)+
β-xi.

・−・−・−・・−・・−・・(1) Where, ), io: basic current density (A/dll”), W: convergence of steel plate (dm), L: counter electrode length (d+e), k: current wrap-around correction coefficient, α: width direction correction coefficient, β: Fixed correction factor.

In other words, it has been revealed that the current to be applied is proportional to the length of movement of the steel plate from the inlet of the alternating current electrolyzer, and can be calculated by appropriately setting α and β as correction coefficients.

<Example> The validity of the above formula (1) will be demonstrated below using an example.

SO5304HL (hairline) board (dimensions: 100
0siX2000+mw) (sulfuric acid 500g/i+chromic anhydride 2-note alternating current electrolysis), a black coloring test was conducted with α, β, and k as variables.

After coloring, the color was measured using a commercially available color difference meter and evaluated. The results are shown in Table 1.

From Table 1, it is possible to make the surface uniformity of color tone and its reproducibility by finding the coefficients of α, β, and by controlling the current by formulating it mathematically, it is possible to make the surface uniformity of color tone between the sheets and sheets. It is clear that the reproducibility can be measured.

<Effects of the Invention> According to the present invention, stainless steel sheets can be colored with excellent color uniformity and good reproducibility, so the colored stainless steel sheets produced by this method can be used as interior materials, building materials, etc., which are the main uses. Can be used regardless of exterior material.

Patent applicant: Kawasaki Steel Corporation

Claims (1)

[Claims] When applying oxidation coloring to a cut stainless steel plate by subjecting it to alternating current electrolysis in a solution bath containing chromic acid and sulfuric acid, A method for coloring a stainless steel sheet, characterized by controlling an alternating current density in accordance with the length of movement from an inlet in a tank.