JP2004136344A - Stainless steel plate having fingerprint staining resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide stainless steel plate having a finished surface which is less conspicuous in fingerprints stuck thereto, and easily wiped. <P>SOLUTION: In a stainless steel plate having the fingerprint staining resistance, a plurality of unevenness are protruded in a range of 30-1,000 pieces per 25.4 mm and in the height range of 2-30 micron at random without directivity with respect to the rolling direction of the steel plate, and a transparent organic resin film is formed on the surface. <P>COPYRIGHT: (C)2004,JPO

Description

【００１３】
上記式から明らかなように、たとえΔＬが小さくともΔａ、Δｂが大きければ指紋は目立つようになる。従って、指紋の目立ち易さはΔＥで判断すればよいものと考えられる。
尚、この判断が正しいことは、後述の表１に示した調査より検証された。
【００１４】
以上のように本発明等は、ΔＥを測定することにより指紋の目立ち易さを判断することとした。また、本発明者等は、鋼板の表面処理の種類、鋼板表面に存する凹凸の高さ、該凹凸の密度（単位面積当たりの個数）及び該凹凸の配置（方向性をもって配置されるか、ランダムに配置されるか）が、指紋の目立ち易さに関係することに留意した。
尚、表面の凹凸の数、２５．４ｍｍ（１インチ）当りの数値については、アメリカ自動車協会の規格に従って測定することとした。
以上の判断基準、留意の下に、実験を行い、下記の表１を作成した。
【００１５】
【表１】

【００１６】
表１に示した実験においては、実験Ｎｏｓ．　１〜７において用いられたステンレス鋼板の表面仕上げが、それぞれ、ＢＡ、Ｎｏ．　２Ｂ、Ｎｏ．　２Ｄ、ＨＬ、Ｎｏ．　３、Ｎｏ．　４、鏡面（Ｎｏ．　８）のものであり、一方Ｎｏｓ．　８〜１２において用いられたステンレス鋼板の表面仕上げは、いずれもダル仕上げとなっている。
実験Ｎｏｓ．　１〜３、Ｎｏ．　７のものについては、ステンレス鋼表面に凹凸が形成されていない。実験Ｎｏｓ．　４〜６のものは、ステンレス鋼表面に複数の凹凸があるが、これら複数の凹凸の形成には方向性があり、表１に示したように研磨方向に直交する方向に凹凸が複数形成されている。表１に示した凹凸の数は、研磨方向に直交する方向において測定したものである。実験Ｎｏｓ．　８〜１２については、ステンレス鋼表面に複数の凹凸がランダムに形成されている。
【００１７】
これら実験において、指紋をつけ色彩色差計により色差（ΔＥ値）を測定したところ、表１に示したような結果となった。
ΔＥの数値は、通常人間の目で見て僅かに差が認識できる限界のΔＥ値は０．５〜１．５程度であるとされ、ΔＥが１．５以下であるならば、指紋が目立たず、大きな効果があるものと評価される。一方、ΔＥが３以上であれば指紋は目立ち、６以上であれば大いに目立つものと評価される。
表１に示したように、ステンレス鋼表面に凹凸が形成されていないか或いは形成されていたとしてもランダムではない場合においては、ΔＥ値が高く、また視認によっても指紋が目立ったことが判明した。指紋が見える、見えない、或いは見えにくいということは、光の散乱の度合いの問題であり、散乱が全方位であれば見え易く、散乱に方向性があればその方向から見ると散乱校が像を結んで汚れとして見えてしまうためと思われる。即ち、凹凸がランダムでない場合には、研磨面の稜線に当たった汚れからの反射光が汚れの像を結び汚れとして見え易くなるものと思われる。
【００１８】
尚、表１の結果においては、ステンレス鋼表面がダル仕上げの場合にのみ効果があるように見えるが、後述の実施例２より明らかなように、ダル仕上げ以外のステンレス鋼板であっても請求項１の条件を満たすことにより、指紋は目立たなくなる。
【００１９】
また、鋼板表面に存する各々の凹凸の高さに関して、実験Ｎｏ．　８、Ｎｏｓ．　９〜１１、Ｎｏ．　１２を比較検討すると、０．４ミクロンの実験Ｎｏ．　８、３５．１ミクロンの実験Ｎｏ．　１２に対して、凹凸の高さが２．２ミクロン、８．８ミクロン、２６．５ミクロンの実験Ｎｏｓ．　９〜１１の場合、ΔＥ値が低く、視認によっても指紋は目立たなかった。これより、各々の凹凸の高さは、３〜３０ミクロンの場合に指紋が目立たないことが判明した。３ミクロン未満だと光の散乱の度合いが小さくなり、見かけ上平滑なものと類似した表面になり、肉眼では指紋部の協会が像を結ぶ状態になるものと思われる。また、３０ミクロンを越えると、凹凸の稜線が長くなることから、汚れ部の光の散乱が直線状になって指紋が見え易くなってしまうものと思われる。
【００２０】
更に、鋼板表面に存する凹凸の密度（単位面積当たりの個数）に関して、実験Ｎｏ．　８、Ｎｏｓ．　９〜１１、Ｎｏ．　１２を比較検討すると、凹凸の数が２５．４ｍｍ（１インチ）当り１２５２個である実験Ｎｏ．　８、２３個である実験Ｎｏ．　１２に対して、それぞれ８４３個、１５１個、５１個の実験Ｎｏｓ．　９〜１１の場合、ΔＥ値が低く、視認によっても指紋は目立たなかった。これより、凹凸の密度は、２５．４ｍｍ（１インチ）当り３０〜１０００個の場合に指紋が目立たないことが判明した。２５．４ｍｍあたり３０個未満だと、相対的に凹凸の高さが低くなった場合と同様な状態になり、光の散乱が小さくなることが起因するものと思われる。また、１０００個を越えても、ΔＥ値は大きくはなるが、１０００個を越えるためには凹凸の高さを低くせざるを得ない（実際表１に示した実験においても、１０００個を越えると、凹凸の高さは０．４ミクロンにしかできなかった）ためである。
【００２１】
次に、ステンレス鋼に有機樹脂皮膜を施すことに関して、フッ素樹脂、ポリエステル樹脂、アクリル樹脂、メラミン樹脂、アクリルメラミン樹脂の皮膜をそれぞれ施したものと、表１の最右欄に示した「皮膜なし」のものとを比較すると、特に実験Ｎｏｓ．　９〜１１の場合、皮膜なしの場合に比較して皮膜を施した場合の方が、ΔＥ値が低く、視認によっても指紋は目立たなかった。
有機樹脂皮膜に関しては、一般的に使用されている透明な有機樹脂の皮膜であればどんなものでもよく、種々実験を行ったところ、上述のフッ素樹脂、ポリエステル樹脂、アクリル樹脂、メラミン樹脂、アクリルメラミン樹脂の他に、シリコン変性樹脂（シリコン変性ポリエステル樹脂、シリコン変性アクリル樹脂）や、有機樹脂にシリカを代表成分とする無機物質を添加した有機・無機複合系樹脂も使用することが可能である。
樹脂皮膜の厚さは、６〜８ミクロンが好ましい。
【００２２】
従って、本発明の方法で、耐指紋汚染性が改善されるというメカニズムは以下のように考えられる。
仕上げ材たる鋼板の表面に付着した指紋が認められるのは、指紋が付着した部位と付着していない周囲の部位とで光の散乱が異なるためと考えられる。また、ダル仕上げ材では、平滑な表面あるいは方向性をもった研磨仕上げ材に比べて光の散乱が大きくなり見えにくくなる上に、仕上げ材表面に施した透明な樹脂皮膜により更に光の散乱が拡大されて指紋が認められなくなるものと思われる。
また、有機樹脂皮膜により、指紋を拭き取り易くなるという効果もある。
尚、付着させた指紋の拭き取り易さについては、表１中のいずれの条件の材料についても従来品と同様に良好であった。
【００２３】
【実施例１】
本発明の第１の実施例では、ステンレス鋼板ＳＵＳ　３０４の厚さ０．７ｍｍのＢＡ仕上げ材を使用し、エンボスロールで圧延加工し、表面凹凸の高さが１２ミクロンメートルで、２５．４ｍｍ（１インチ）当り１３１個の凹凸を圧延方向に対して方向性なくランダムに突設したもので、ダル仕上加工が施されている。
【００２４】
該鋼板の表面には、予めシランカップリングで塗装の前処理を行った後、厚さ６ミクロンの透明なアクリル・メラミン樹脂を塗装処理した。
この表面に指紋を付着してみたところ、肉眼観察では指紋は殆ど認められず、また指紋部の色差（ΔＥ）を測定した結果、０．４と良好な結果が得られた。
【００２５】
【実施例２】
本発明の第２の実施例のものは、鋼種はＳＵＳ　４３０で、材料の厚さ０．５ｍｍのＮｏ．　２Ｂ仕上材を使用し、エンボスロールで圧延加工し、表面の凹凸の高さが２１ミクロンで２５．４ｍｍ（１インチ）当り８９個の凹凸が方向性なくランダムに突設させた。
【００２６】
この材料の表面には、高分子ポリエステル樹脂との密着性を高めるために予めノンクロメートの塗装前処理を施した後、透明な高分子ポリエステル樹脂を厚さ１８ミクロンで塗装した。
この表面に指紋を付着してみたところ、肉眼観察では指紋は殆ど認められず、指紋部の色差（ΔＥ）を測定した結果０．７の良好な結果が得られた。
【００２７】
【発明の効果】
本発明により、従来の単なる拭き取り易さに加えて、指紋そのものが殆ど認められないという効果をもたらすこととなった。
【００２８】
この結果、ステンレス鋼材の表面の景観を保持するため、従来は頻繁な清掃が不可欠であったが、その頻度を著しく低減させることができるという効果をもたらすことになった。
【００２９】
従って、清掃の手間が省けるだけでなく、薬剤の使用量の低減と、それに伴う土壌の汚染の懸念が大きく軽減できるという効果を奏しめるものである。
【００３０】
また、該鋼板の表面が方向性のないダル仕上げとされ、かつその表面に透明な樹脂皮膜で塗装することにより、シルバーメタリック調の上品な重厚感のある落ち着いた景観を呈することができるので、例えば、家電製品関係、厨房機器、あるいは建物の内装のパネル等、幅広い用途に供することができるという効果をもたらすものである。
【００３１】
また、該鋼板の表面に塗装される塗料は透明で有れば無色或いは有色の塗料でもよく、塗装前処理を施した後、前期樹脂を塗装すれば、実施例１或いは実施例２の効果が得られるものである。[0001]
[Industrial applications]
The present invention relates to a stainless steel sheet which is suitable for components used in the fields of home appliances, kitchens, building interiors and exteriors, transportation equipment, etc., has less fingerprint contamination, and has fingerprint contamination resistance.
[0002]
[Prior art]
In recent years, stainless steel has been used in a variety of applications in large quantities, for example, refrigerators, household appliances such as microwave ovens, household or commercial kitchen appliances such as cabinets and countertops, or interior panels for buildings, It is widely used in applications such as railcar structures and exterior materials, along with improvements in stainless steel processing technology.
[0003]
Also, the finish and type of stainless steel are various, and HL finish specified by JIS and No. 3, no. In addition to the polished finish such as 4, a BA finish or a mirror finish is applied depending on the application and purpose.
[0004]
Depending on these stainless steel products or their use parts, there are many chances to touch human hands, fingerprints are easily attached, and it is difficult to remove them, so that there is a problem that fingerprints impair the appearance.
[0005]
For this reason, for some uses such as home appliances, a transparent coating process called clear coating has been performed as a process utilizing the appearance of the surface of stainless steel. When this process is performed, it is relatively easy to wipe off the attached fingerprint as compared with the case of not painting, but there is a problem that the fingerprint is still conspicuous until the wiping is performed.
[0006]
[Problems to be solved by the invention]
The present invention is to improve the disadvantages of the previous term, the stainless steel plate, fingerprints are less noticeable even when touched by human hands on the surface of stainless steel products, and have excellent anti-fingerprint contamination resistance with aesthetic appearance The challenge is to provide
[0007]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention has a configuration in which a plurality of irregularities are provided on the surface of a stainless steel plate, and a transparent organic resin film is applied to the surface on which the irregularities are formed. It is made of stainless steel in which the attached fingerprints are hardly noticeable.
[0008]
That is, in the invention of claim 1, the surface of the stainless steel plate has a plurality of irregularities in a height range of 2 to 30 microns and in a range of 30 to 1000 per 25.4 mm in the rolling direction of the steel plate. In addition, the stainless steel plate has a configuration in which it is randomly projected without directionality, and a transparent organic resin film is formed on the surface thereof.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, various transparent organic resin paints are applied to the surface of a stainless steel sheet having various surface finishes, and an artificial fingerprint is applied by a method of measuring an artificial fingerprint specified in JIS K2246. The conspicuousness was evaluated.
[0010]
An index for evaluation of the conspicuousness of the attached fingerprint is evaluated by a color difference (ΔE value) by a colorimeter as follows, and a value with a large ΔE value makes the fingerprint conspicuous and a ΔE value. The present inventors have determined that a small one has a fingerprint that is inconspicuous.
[0011]
When a fingerprint is attached to a stainless steel plate, it is considered that the fingerprint is indicated by the color difference (ΔE), not the lightness change (ΔL) from the surroundings where the fingerprint is not attached, rather than the lightness change.
Here, the relationship between ΔL and ΔE is defined by the following equation according to JIS Z8730.
[0012]
(Equation 1)

[0013]
As is apparent from the above equation, even if ΔL is small, the fingerprint becomes conspicuous if Δa and Δb are large. Therefore, it is considered that the conspicuousness of the fingerprint may be determined by ΔE.
The correctness of this determination was verified by the investigation shown in Table 1 described below.
[0014]
As described above, in the present invention and the like, the visibility of the fingerprint is determined by measuring ΔE. In addition, the present inventors have determined the type of surface treatment of the steel sheet, the height of the unevenness existing on the steel sheet surface, the density of the unevenness (the number per unit area), and the arrangement of the unevenness (arranged with directionality or randomized). Is related to the conspicuousness of the fingerprint.
The number of irregularities on the surface and the numerical value per 25.4 mm (1 inch) were measured in accordance with the standards of the American Automobile Association.
An experiment was conducted based on the above criteria and attention, and Table 1 below was created.
[0015]
[Table 1]

[0016]
In the experiments shown in Table 1, in Experiment Nos. The surface finish of the stainless steel plates used in Nos. 1 to 7 was BA, No., respectively. 2B, no. 2D, HL, No. 3, no. 4, mirror surface (No. 8), while Nos. The surface finishes of the stainless steel plates used in Nos. 8 to 12 are dull finishes.
Experiment Nos. 1-3, No. For No. 7, no irregularities were formed on the stainless steel surface. Experiment Nos. In the case of Nos. 4 to 6, the stainless steel surface has a plurality of irregularities, and the formation of the plurality of irregularities has directionality. As shown in Table 1, a plurality of irregularities are formed in a direction perpendicular to the polishing direction. ing. The number of irregularities shown in Table 1 was measured in a direction perpendicular to the polishing direction. Experiment Nos. For Nos. 8 to 12, a plurality of irregularities are randomly formed on the stainless steel surface.
[0017]
In these experiments, when the color difference (ΔE value) was measured by a colorimeter using a fingerprint, the results shown in Table 1 were obtained.
As for the value of ΔE, the limit ΔE value at which a slight difference can be generally recognized by human eyes is considered to be about 0.5 to 1.5, and if ΔE is 1.5 or less, the fingerprint becomes noticeable. Is evaluated as having a great effect. On the other hand, when ΔE is 3 or more, the fingerprint is evaluated to be conspicuous, and when ΔE is 6 or more, the fingerprint is evaluated to be significantly outstanding.
As shown in Table 1, when irregularities were not formed on the surface of the stainless steel, or even when the surface was formed, it was not random, the ΔE value was high, and it was found that the fingerprint was conspicuous visually. . The fact that fingerprints are visible, invisible, or difficult to see is a matter of the degree of light scattering. If the scattering is omnidirectional, it is easy to see. It seems that they are tied together and appear as dirt. That is, when the irregularities are not random, it is considered that the reflected light from the dirt hitting the ridge line of the polished surface connects the dirt image and is easily seen as dirt.
[0018]
In addition, in the results of Table 1, it seems that the effect is obtained only when the stainless steel surface is dull-finished. By satisfying condition 1, the fingerprint becomes less noticeable.
[0019]
Further, with respect to the height of each concavity and convexity existing on the steel sheet surface, Experiment No. 8, Nos. 9 to 11, No. 9; 12 are compared with each other. Experiment No. 8, 35.1 microns. 12, the height of the unevenness was 2.2 μm, 8.8 μm, and 26.5 μm. In the case of 9 to 11, the ΔE value was low, and the fingerprint was not conspicuous even by visual recognition. From this, it was found that the fingerprint was inconspicuous when the height of each unevenness was 3 to 30 microns. If it is less than 3 microns, the degree of light scattering will be small, and the surface will be similar to an apparently smooth surface, and it is considered that the association of fingerprints forms an image with the naked eye. On the other hand, if it exceeds 30 microns, the ridgeline of the concavo-convex becomes long, and it is considered that the scattering of light in the stained portion becomes linear and the fingerprint becomes easy to see.
[0020]
Further, with respect to the density of irregularities (the number per unit area) existing on the steel sheet surface, the experiment No. 8, Nos. 9 to 11, No. 9; Comparing and examining No. 12, Experiment No. 12 in which the number of irregularities is 1252 per 25.4 mm (1 inch). Experiment No. 8 and 23 12, 843, 151, and 51 experimental Nos. In the case of 9 to 11, the ΔE value was low, and the fingerprint was not conspicuous even by visual recognition. From this, it was found that the fingerprint was inconspicuous when the density of the irregularities was 30 to 1000 per 25.4 mm (1 inch). If the number is less than 30 per 25.4 mm, the state becomes the same as the case where the height of the unevenness is relatively reduced, and it is considered that the scattering of light is reduced. Further, even if the number exceeds 1,000, the ΔE value increases, but in order to exceed 1,000, the height of the unevenness must be reduced (in fact, even in the experiment shown in Table 1, the value exceeds 1,000). And the height of the unevenness could only be 0.4 microns).
[0021]
Next, regarding the application of the organic resin film to the stainless steel, a film of a fluorine resin, a polyester resin, an acrylic resin, a melamine resin, and a film of an acrylic melamine resin were respectively applied to the stainless steel. In particular, when compared with those of Experiment Nos. In the case of 9 to 11, the ΔE value was lower in the case where the film was formed than in the case where the film was not formed, and the fingerprint was not conspicuous by visual recognition.
Regarding the organic resin film, any film can be used as long as it is a commonly used transparent organic resin film, and various experiments have been carried out. As a result, the above-mentioned fluororesin, polyester resin, acrylic resin, melamine resin, acrylic melamine In addition to the resin, it is also possible to use a silicon-modified resin (silicon-modified polyester resin, silicon-modified acrylic resin) or an organic-inorganic composite resin obtained by adding an inorganic substance having silica as a representative component to an organic resin.
The thickness of the resin film is preferably 6 to 8 microns.
[0022]
Therefore, the mechanism by which the fingerprint contamination resistance is improved by the method of the present invention is considered as follows.
It is considered that the fingerprint attached to the surface of the steel plate as the finishing material is recognized because light scattering is different between the site where the fingerprint is attached and the surrounding site where the fingerprint is not attached. In addition, with a dull finish, light scattering is greater and less visible than a polished finish with a smooth surface or directivity, and light scattering is further reduced by the transparent resin film applied to the finish surface. It seems that the fingerprint is enlarged and no fingerprint can be recognized.
In addition, the organic resin film also has an effect that fingerprints can be easily wiped off.
The ease of wiping off the adhered fingerprints was as good as that of the conventional product for the materials under any of the conditions in Table 1.
[0023]
Embodiment 1
In the first embodiment of the present invention, a 0.7 mm thick BA finishing material of stainless steel plate SUS 304 is used, and is rolled with an embossing roll. 131 projections and depressions per inch are randomly projected without any directionality with respect to the rolling direction, and have a dull finish.
[0024]
The surface of the steel sheet was pre-treated for coating by silane coupling, and then coated with a transparent acrylic / melamine resin having a thickness of 6 microns.
When a fingerprint was adhered to this surface, almost no fingerprint was recognized by visual observation, and the color difference (ΔE) of the fingerprint portion was measured. As a result, a good result of 0.4 was obtained.
[0025]
Embodiment 2
In the second embodiment of the present invention, the steel type is SUS430, and the material No. having a material thickness of 0.5 mm is used. A 2B finishing material was used and rolled with an embossing roll, and the height of the surface irregularities was 21 microns, and 89 irregularities per 25.4 mm (1 inch) were randomly projected without directionality.
[0026]
The surface of this material was previously subjected to a non-chromate pre-coating treatment in order to enhance the adhesion with the high-molecular polyester resin, and then coated with a transparent high-molecular polyester resin to a thickness of 18 μm.
When a fingerprint was adhered to this surface, almost no fingerprint was recognized by naked eye observation, and a good result of 0.7 was obtained as a result of measuring the color difference (ΔE) of the fingerprint portion.
[0027]
【The invention's effect】
According to the present invention, in addition to the conventional easiness of wiping, the effect that a fingerprint itself is hardly recognized is brought about.
[0028]
As a result, in order to maintain the landscape of the surface of the stainless steel material, frequent cleaning has conventionally been indispensable, but the frequency can be significantly reduced.
[0029]
Therefore, not only can the labor of cleaning be eliminated, but also the effect of reducing the amount of chemicals used and the associated concern of soil contamination can be greatly reduced.
[0030]
In addition, since the surface of the steel sheet is dull finish with no directivity, and by painting the surface with a transparent resin film, it is possible to present an elegant and calm scene with a silver metallic tone, for example, It can be used for a wide range of applications, such as home appliance products, kitchen equipment, and panels for building interiors.
[0031]
The paint applied to the surface of the steel sheet may be colorless or colored as long as it is transparent. If the resin is applied after the pre-coating treatment, the effect of the embodiment 1 or 2 can be obtained. It is obtained.

Claims (1)

A plurality of irregularities are randomly projected on the surface of the stainless steel sheet in a range of height 2 to 30 microns and in a range of 30 to 1000 pieces per 25.4 mm with no directionality in the rolling direction of the steel sheet. And a transparent organic resin film is formed on the surface of the stainless steel sheet.