JP2008144259A - Surface treated steel sheet having excellent stain resistance and fingerprint resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treated steel sheet having excellent stain resistance and fingerprint resistance, such as an operation panel and a door in an elevator, for example, which is frequently exposed to people's eyes, requires design property and has many opportunities to be touched by people. <P>SOLUTION: A hard silica film comprising an alkali metal element(s) or an alkaline-earth element(s) in 0.02 to 0.2% by molar ratio is formed on a designed stainless steel sheet at a thickness of 0.2 to 2 μ, thus finger prints are made inconspicuous, and its stain resistance can be improved without changing the texture of the stock and without deteriorating the designability of stainless steel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a surface treatment that is well exposed to human eyes, such as an operation panel and door of an elevator, etc., is required to have a design property, and has many opportunities to be touched by people. It relates to steel sheets.

  For a door material such as an elevator, an operation panel, etc., a surface-treated stainless steel plate obtained by etching stainless steel, polishing the surface, or coloring it is used as a high-grade design steel plate. However, this surface-treated steel sheet has a problem that fingerprints and the like adhere to the surface-treated steel sheet, and the design is impaired.

  As countermeasures, clear coating is applied to the surface, or wax or oil is applied. However, when clear coating is applied, the texture changes and the design is impaired. Moreover, it is necessary to apply | coat waxes etc. regularly. In addition, the surface irregularities are made fine to make the fingerprints inconspicuous, but it has not yet been fundamentally solved because it is restricted by the design.

  Many thin film surface treatment methods that improve stain resistance and fingerprint resistance without deteriorating the design properties have been devised and proposed. They are divided into the following two types, and one of them is a method of making the surface characteristics water-repellent, repelling fat such as fingerprints, and making it inconspicuous. Many are methods of making the resin water-repellent and using fluoride, silicon or the like. (JP 2003-226740, JP 2002-326325, JP 2000-119351, etc.). This method is applied to a thickness of several tens of microns, and as described above, the texture of the surface is changed and design properties are impaired.

  Some are treated with a treating agent having a water-repellent group and a hydrophilic group in one molecule as disclosed in JP-A No. 2002-174702, and the surface is used for water repellency with an extremely thin film. This film has excellent anti-contamination properties in a thin film by selecting a water-repellent group and a hydrophilic group, but it is close to a monomolecular film, and the film is easily destroyed by external forces such as abrasion, resulting in poor durability. .

On the other hand, many methods such as Japanese Patent Application Laid-Open No. 2006-282879 and Japanese Patent Application Laid-Open No. 2005-060675 have been proposed as methods for making them hydrophilic. The fact is that is not made use of.
However, there is a method of applying a photocatalyst as in JP-A-9-57912, JP-A-10-156999, etc., thereby making it hydrophilic, and decomposing contaminants. The amount of light is small and the effect cannot be expected very much. Furthermore, the strength of the coating itself is fragile and easily broken. As a countermeasure, it has been proposed to use various binders, but the film becomes thick and the texture changes.

Problems to be solved by the invention

  Therefore, it is a thin film treatment that does not impair the design of the article to be coated, and by imparting hydrophilicity or water repellency, a durable treatment excellent in stain resistance and fingerprint resistance is desired.

Means to solve the problem

  Therefore, paying attention to the fact that the alkali silicate film is hydrophilic, the alkali silicate is colloidally dispersed, mixed with colloidal silica, and the amount of alkali metal element in the film is controlled to be strong and hard. The inventors have found that a hydrophilic film can be obtained, and have arrived at the present invention.

That is, a film made of alkali silicate and silica is formed on the surface of a stainless steel sheet with a thickness of 0.2 μm or more and 2 μm or less, and the amount of alkali metal in the film is 0.02 to 0.02% of silicon. The surface-treated steel sheet is characterized in that it has a hardness of 2% and a film hardness of 6H or more.
Further, some or all of the alkali metal elements may be alkaline earth elements.

The invention's effect

  This film containing alkali silicate does not contain organic matter and is a thin film, so it does not change the texture of the material. Further, a strong siloxane bond is formed by silica, and a strong film having a pencil hardness of 6H or higher can be obtained only by natural drying. Furthermore, by baking, crystal water is blown off, and it becomes a hard film with a hardness of 9H or more. This film has a property that fingerprints are not conspicuous and oily magic marks can be easily removed by wetting water.

Colloidal silica containing an alkali silicate has a high water absorption when the amount of alkali metal element is large, the strength as a film is weak, and cracks are likely to occur in the long term. On the other hand, if the amount is small, the hydrophilicity is weak and the stain resistance and fingerprint resistance are poor. Therefore, the amount of alkali metal in the film is mol%, and a range of 0.02 to 0.2% of silicon shows a good result.
The thickness of the film is preferably thicker from the standpoint of stain resistance performance, but on the other hand, the treated stainless steel sheet must be able to withstand bending and impact, and further, it must be treated. Since it is desired that the texture after being applied does not change so much, it is not preferable to apply it too thickly. If it is too thin, unevenness will remain due to spray coating, and a part with no coating will be formed. Therefore, the range of 0.2 to 2 μ is desired from these.
Stainless steel surface-treated steel sheet is a physical treatment such as polishing on the surface of a stainless steel sheet, a chemical treatment such as coloring by immersing in a chemical, a physical ceramic coating such as ion sputtering treatment, Everything that has passed through the manufacturing process is included. There are no restrictions on the shape or the like as long as it is stainless steel, such as a simple plate or pipe.
Examples of these are given in the examples.

A colloidal solution consisting of alkali silicate and silica (solid content of about 5%) was applied onto stainless steel by air spray and baked in an atmosphere of 200 to 230 ° C. for 20 minutes. The level is shown in Table (1). The stainless steel design steel plate with a SUS304 vibration finish with a thickness of 1.2 mm was used.

  The evaluation method was performed as follows. Hardness: Pencil hardness (according to JISG3318), fingerprint resistance: A fingerprint was attached, and whether or not the trace of the fingerprint was conspicuous was evaluated (◯: almost unknown, Δ: faintly visible, ×: clearly visible). Contamination resistance: A line was drawn with an oil-based magic, and after 24 hours, wiped with a cloth soaked in water and evaluated in the state of the mark (◯: cleanly removed, Δ: some remained ×: no drop). Impact resistance: Evaluated by DuPont impact test (1/2 inch diameter spherical punch with a 1 kg load dropped from 500 mm to give an impact) (O: not peeled, x: partially peeled).

The invention's effect

  As is clear from the examples and comparative examples in Table (1), the surface-treated steel sheet having excellent stain resistance and fingerprint resistance according to the present invention has strong durability against impacts and the like, and dirt is conspicuous. Even if it is attached, it has a characteristic that it can be easily removed by wiping with water.

  Sectional view of Example 1

Explanation of symbols

1 Stainless steel surface-treated steel plate 2 Film

Claims (2)

  A film made of alkali silicate and silica is formed on the surface of a stainless steel surface-treated steel sheet with a thickness of 0.2 to 2 microns, and the amount of alkali metal in the film is 0.02 to 0.2% of silica. In addition, the surface-treated steel sheet is characterized in that the hardness of the film is a pencil hardness of 6H or more.   The surface-treated steel sheet according to claim 1, wherein a part or all of the alkali metal is alkaline earth.

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