JPH10121269A - Hydrophilic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve hydrophilic property by forming a layer preventing the diffusion of Co, Ni, Fe and Cr atoms on the surface of a stainless steel product and fixing a photosemiconductor-contg. layer on the top of the formed layer when the suitability of the surface of the product to washing with water and rain is improved by the photoexcitation action of a photosemiconductor. SOLUTION: A layer of a silicic acid compd. or glaze free from Co, Ni, Fe and Cr atoms and preventing the diffusion of the atoms is formed preferably in >=2μm thickness on the surface of a stainless steel product, a carbon steel product, a ferrite-contg. magnetic substance, etc., required to be made hydrophilic and a photosemiconductor-contg. layer preferably having <=0.4μm thickness is fixed on the top of the formed layer. A wear or corrosion resistant protective layer of silica, alumina, silicone or a solid very strong acid capable of being made hydrophilic or other functional film may further be formed if necessary. It is preferable that the photosemiconductor-contg. layer further contains one or more among silica, a solid very strong acid and silicone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for making a surface of a substrate containing at least one of Co, Ni, Fe, and Cr atoms, such as a stainless steel substrate, highly hydrophilic and maintaining the surface. About. More particularly, the present invention relates to a technique for preventing the surface from being soiled by making the surface of the article highly hydrophilic, or for self-cleaning (self-cleaning) or easily cleaning the surface.

[0002]

2. Description of the Related Art The present inventors have proposed PCT / JP96 / 00.
No. 733, it has been found that when an optical semiconductor-containing layer is formed on a substrate surface, the layer surface exhibits a high degree of hydrophilicity of 10 ° or less in terms of a contact angle with water in response to optical excitation of the optical semiconductor. Further, it has been found that such effects as anti-fogging and improved visibility of transparent members such as glass, lenses and mirrors, and improved water-washing and rain-washing of the article surface can be obtained.

[0003]

However, as described in Example 1 below, when Co is added to a surface layer containing an optical semiconductor, the optical semiconductor hardly undergoes hydrophilization due to photoexcitation. It has been found that the addition of Ni, Fe, and Cr significantly reduces the hydrophilizing effect of the optical semiconductor by photoexcitation. Therefore, when a surface layer containing an optical semiconductor is directly fixed on a stainless steel product such as a sink, a railway car, a building material, etc .; a carbon steel product such as a tool or an industrial machine; Is not sufficiently exhibited, and it is difficult to sufficiently exhibit the effects of improving the water washability and rainfall washability of the article surface. The present invention has been made in view of the above circumstances,
Co, Ni, Fe, Cr
Even when immobilized on a substrate containing at least one kind of atoms, the photo-semiconductor is sufficiently exerted a hydrophilizing action by photoexcitation, and thus the effect of improving the water washability and rain washability of the article surface is sufficiently achieved. An object is to provide a hydrophilic member that can be exhibited.

[0004]

According to the present invention, in order to solve the above-mentioned problems, an optical semiconductor layer containing no Co, Ni, Fe or Cr atoms is formed on the surface of a substrate, and the optical semiconductor layer is used for optical excitation of the optical semiconductor. Accordingly, a hydrophilic member is provided, wherein the surface of the layer exhibits a high degree of hydrophilicity. In one embodiment, at least one of Co, Ni, Fe or Cr atoms
An optical semiconductor-containing layer is formed on the surface of the substrate containing the species via a layer that prevents the diffusion of the atomic species, and the layer surface exhibits a high degree of hydrophilicity in response to photoexcitation of the optical semiconductor. A hydrophilic member characterized by the above. Co, Ni,
By providing a layer for preventing the diffusion of Fe atoms to the surface layer, the surface layer containing the optical semiconductor is not affected by Co, Ni, and Fe atoms, and contains at least one of Co, Ni, and Fe atoms. Even when the optical semiconductor is fixed on the base material, the photo-semiconductor is sufficiently rendered hydrophilic by photoexcitation, so that the effects of improving the water-washing property and rain-washing property of the article surface are sufficiently exhibited.

[0005]

Next, the components of the present invention will be described. The base material containing at least one of Co, Ni, Fe, and Cr atoms is, for example, a stainless steel base material, carbon steel,
Cast iron, castings, ferromagnetic materials, etc. Co, Ni, Fe,
The layer for preventing the diffusion of Cr is preferably made of a material that does not contain Co, Ni, Fe, Cr and the like. For example,
When it is desired to utilize the color of the underlayer in a design, a transparent material such as a silicate compound such as silica, a silicone resin, an acrylic resin, and water glass can be suitably used. Also, Co, N
A coloring material may be used for the layer for preventing the diffusion of i, Fe, and Cr, and the layer may have a design property. In that case, glaze; Co, Ni, Fe, Cr such as Ag, Pt, etc.
Materials such as colored metals other than the above can be suitably used. Co,
The thickness of the layer for preventing the diffusion of Ni, Fe, and Cr is 0.0
It is preferably at least 2 μm. Then, diffusion of Co, Ni, Fe, and Cr from the base material to the surface layer can be effectively prevented.

The term "hydrophilic" refers to the property of being easily conformed when water is dropped on the surface, and generally refers to a state where the water wetting angle is less than 90 °. The high hydrophilicity in the present invention refers to a property that the surface is very easy to conform to when water is dropped, and rather forms a water film without forming a water drop. More specifically, the water wetting angle is 10状態 or less, preferably 5 ゜ or less.

[0007] An optical semiconductor is formed by irradiating light (excitation light) having an energy (ie, shorter wavelength) larger than the energy gap between the conduction electron band and the valence band of the crystal. A substance capable of generating conduction electrons and holes by excitation of electrons (photoexcitation) therein, for example, anatase type titanium oxide, rutile type titanium oxide, tin oxide, zinc oxide, bismuth trioxide, Tungsten trioxide, ferric oxide, strontium titanate and the like can be suitably used.
As the light source used for optical excitation of the optical semiconductor, indoor lighting such as a fluorescent lamp, an incandescent lamp, a metal halide lamp, and a mercury lamp, the sun, and a light source in which light from the light source is guided by a low-loss fiber are preferably used. it can. In order for the substrate surface to be highly hydrophilized by optical excitation of the optical semiconductor,
Illuminance of the excitation light, may if 0.001 mW / cm ² or more, preferably that it 0.01 mW / cm ² or more, 0.1
More preferably, it is at least mW / cm ² .

It is desirable that the optical semiconductor-containing layer contains at least one of silica, solid superacid, and silicon. When silica and solid superacid are contained,
It can easily exhibit a high degree of hydrophilicity at lower excitation light illuminance, and can maintain that state for a considerably long time. Even if silicon is contained, the silicon can be produced by photoexcitation of the optical semiconductor.
At least a part of the organic group bonded to the silicon atom in the compound is substituted with a hydroxyl group. Once substituted with a hydroxyl group, as in the case of silica addition, it tends to exhibit a high degree of hydrophilicity with low excitation light illuminance and can maintain that state for a considerably long time. Here, the super-strong acid refers to a strong acid containing a solid oxide having a Hammett acidity function Ho ≦ -11.93 as a component, and specifically, Al ₂ O ₃ supported on sulfuric acid, TiO ₂ supported on sulfuric acid, ZrO supported on sulfuric acid. ₂ , sulfuric acid supported Fe ₂ O ₃ , sulfuric acid supported SiO ₂ , sulfuric acid supported HfO ₂ , TiO ₂ / WO
₃ , WO ₃ / SnO ₂ , WO ₃ / ZrO ₂ , WO ₃ / F
e ₂ O ₃ , SiO ₂ .Al ₂ O _{3 and the} like can be suitably used. As the silicone, any polyorganosiloxane can be generally used. For example, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane , Ethyltripropoxysilane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, Diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyl Silane, phenyl methyl dipropoxy silane, phenyl methyl dibutoxy silane, .gamma.-glycidoxypropyltrimethoxysilane, and hydrolysates thereof, partial condensation polymerized material after hydrolysis,
A mixture obtained by hydrolyzing, dehydrating and condensing as required, a mixture or the like thereof as a precursor can be suitably used.

The thickness of the optical semiconductor-containing layer is preferably set to 0.4 μm or less. Then, cloudiness due to irregular reflection of light can be prevented, and the optical semiconductor-containing layer becomes substantially transparent. Further, the thickness of the optical semiconductor-containing layer is set to 0.2 μm.
m or less is more preferable. Then, color formation of the layer due to light interference can be prevented. Further, the thinner the optical semiconductor-containing layer, the higher its transparency. Furthermore, the thinner the film, the better the wear resistance of the layer. On the surface of the surface layer, silica, alumina, silicone,
A wear-resistant or corrosion-resistant protective layer such as a solid superacid or the like which can be hydrophilized or another functional film may be provided.

[0010] Ag, Cu, Z
A metal such as n can be added. The layer to which the metal is added can kill bacteria adhering to the surface even in a dark place. In addition, this layer inhibits the growth of microorganisms such as molds, algae and moss. Therefore, adhesion of dirt due to microorganisms is suppressed.

The optical semiconductor-containing layer contains Pt, Pd, R
A platinum group metal such as u, Rh, Os, Ir can be added. The layer to which the metal is added can enhance the oxidation reaction activity of the photosemiconductor by the photocatalysis, thereby improving the deodorizing and purifying action of indoor air and the decomposing and purifying action of pollutants contained in outdoor air.

[0012]

【Example】

Embodiment 1 FIG. (Effect of Co, Ni, Fe on photohydrophilization) 86 parts by weight of ethanol, 6 parts by weight of tetraethoxysilane (Wako Pure Chemical Industries), 6 parts by weight of pure water, and a hydrolysis inhibitor of tetraethoxysilane And 2 parts by weight of 36% hydrochloric acid were added and mixed to prepare a silica coating solution. This solution was coated with a 10 cm square source by the flow coating method.
It was applied to the surface of a Dalheim glass plate and dried at a temperature of 80 ° C. With drying, the tetraethoxysilane was hydrolyzed to be silanol first, and then a thin film of amorphous silica was formed on the surface of the glass plate by dehydration-condensation polymerization of silanol. Next, tetraethoxy titanium (Merc)
k) To a mixture of 1 part by weight and 9 parts by weight of ethanol, 0.1 part by weight of 36% hydrochloric acid was added as a hydrolysis inhibitor to prepare a titanium oxide coating solution, and this solution was coated with the amorphous silica thin film. Was applied by a flow coating method in dry air. The coating amount is 45 μg /
cm ² . Since the rate of hydrolysis of tetraethoxytitanium is extremely fast, part of the tetraethoxytitanium was hydrolyzed at the coating stage, and titanium hydroxide began to form. Next, the glass plate is maintained at a temperature of about 150 ° C. for 1 to 10 minutes to complete hydrolysis of tetraethoxytitanium and to subject the generated titanium hydroxide to dehydration polycondensation to form amorphous titanium oxide. Was obtained. This sample was fired at a temperature of 500 ° C. to crystallize the amorphous titanium oxide into an anatase type titanium oxide to obtain a plurality of # 1 samples. After applying 0.3 g of an aqueous solution of FeCl ₃ .xH ₂ O having a concentration of iron metal of 50 μmol / g to the surface of the # 1 sample, irradiate with a BLB fluorescent lamp at 0.4 mW / cm ² for 10 minutes to fix iron on the substrate. As a result, a # 2 sample was obtained.
After applying 0.3 g of an aqueous nickel chloride solution having a nickel metal concentration of 50 μmol / g to the sample surface of # 1 sample, the sample was irradiated with a BLB fluorescent lamp at 0.4 mW / cm ² for 10 minutes to fix nickel on the base material. A sample was obtained. After applying 0.3 g of an aqueous solution of cobalt chloride hexahydrate having a cobalt metal concentration of 50 μmol / g on the surface of the # 1 sample, an ultraviolet light source (Sankyo Electric, Black Light Blue (BLB) fluorescent lamp) was irradiated with an ultraviolet light of 0.4 m.
Irradiation was performed at W / cm ² for 10 minutes to fix cobalt on the substrate to obtain a # 4 sample. Next, oleic acid was applied to the # 1 to # 4 sample surfaces, rubbed with a neutral detergent (mama lemon), rinsed with tap water and distilled water, and then dried at 50 ° C. for 30 minutes using a dryer. The surface was intentionally contaminated. Thereafter, the contact angles of the sample surfaces # 1 to # 4 with water were measured 30 seconds after a water droplet was dropped from the microsyringe onto the sample surface using a contact angle measuring device (Kyowa Interface Science, CA-X150). The results are shown on the vertical axis of the irradiation time 0 in FIG. As can be seen from the figure, the surface of each of the samples # 1 to # 4 exhibited a contact angle with water of about 50 °. Next, # 1 to #
The surface of the sample 4 was irradiated with a BLB fluorescent lamp at 0.5 mW / cm ² , and the change over time in the contact angle of the sample surface with water was examined.
The results are shown in FIG. According to FIG. 1, while the # 1 sample was highly hydrophilized to a contact angle with water of less than 3 ° in about 3 hours,
# 2 sample to which iron and nickel were added, 25 for # 3 sample
The contact angle with water decreased only to about ゜, and the contact angle with water did not decrease in the # 4 sample to which cobalt was added.
From the above, Co, N were added to the surface layer containing the optical semiconductor.
It has been found that when i and Fe are added, the hydrophilizing effect of the optical semiconductor by photoexcitation is significantly reduced.

Embodiment 2 FIG. (Stainless steel substrate, water wettability, water washability) In 86 parts by weight of ethanol solvent, 6 parts by weight of tetraethoxysilane (Wako Pure Chemical), 6 parts by weight of pure water, and 36 parts by weight as a hydrolysis inhibitor of tetraethoxysilane % Hydrochloric acid was added and mixed to prepare a silica coating solution. This solution was applied to the surface of a 10 cm square stainless steel plate by a flow coating method and dried at a temperature of 80 ° C.
With drying, tetraethoxysilane was hydrolyzed to be silanol first, and then a thin layer of amorphous silica was formed on the surface of the stainless steel plate by dehydration-condensation polymerization of silanol. Next, tetraethoxytitanium (Merck) 1
0.1 part by weight of 36% hydrochloric acid as a hydrolysis inhibitor was added to a mixture of 9 parts by weight of ethanol and 9 parts by weight of ethanol to prepare a titanium oxide coating solution, and this solution was dried on the amorphous silica thin film by dry air. The coating was carried out by a flow coating method. The coating amount is 45 μg / cm ² in terms of titanium oxide.
And Since the rate of hydrolysis of tetraethoxytitanium is extremely fast, part of the tetraethoxytitanium was hydrolyzed at the coating stage, and titanium hydroxide began to form. Next, by maintaining the stainless steel plate at a temperature of about 150 ° C. for 1 to 10 minutes, hydrolysis of tetraethoxytitanium is completed, and the generated titanium hydroxide is subjected to dehydration polycondensation to form amorphous titanium oxide. Was obtained. This sample was fired at a temperature of 500 ° C. to crystallize the amorphous titanium oxide into an anatase type titanium oxide,
A # 5 sample was obtained. The following two evaluations were performed on the # 5 sample and a stainless steel plate for comparison. (1) Evaluation of surface hydrophilicity recovery performance upon irradiation with ultraviolet light After oleic acid was applied to the sample surface, rubbed with a neutral detergent (mama lemon), rinsed with tap water and distilled water, and then dried with a dryer.
The surface was intentionally contaminated by drying at 30 ° C. for 30 minutes, and then irradiated with a BLB fluorescent lamp at 0.5 mW / cm ² for 5 hours to examine the change in the contact angle of the sample surface with water. As a result, in the stainless steel plate, the contact angle with water after the contamination and after irradiation with the BLB fluorescent lamp was 70 °, and no change was observed. Was highly hydrophilized to almost 0 ° after irradiation with a BLB fluorescent lamp. (2) Water immersion cleaning effect of oleic acid Oleic acid was applied to the sample surface used in the test of (1), and the sample was immersed in water filled in a water tank while keeping the sample surface in a horizontal posture. . As a result, in the stainless steel plate, oleic acid remained attached to the surface of the sample, and even when lightly rubbed with water, the oil only extended on the sample, whereas in the # 5 sample, oleic acid was It rolled up into an oil drop, and was released from the surface of the sample and floated with a light finger rub in water.

[0014]

According to the present invention, an optical semiconductor-containing layer is formed on the surface of a substrate containing at least one of Co, Ni, Fe, and Cr atoms. In a member exhibiting hydrophilicity, Co, Ni,
By providing a layer for preventing the diffusion of Fe and Cr atoms into the surface layer, the surface layer containing the optical semiconductor can be made of Co, Ni,
No longer affected by Fe and Cr atoms, Co, Ni, F
Even when fixed on a substrate containing at least one of e and Cr atoms, the photo-semiconductor can sufficiently exhibit a hydrophilizing action by photoexcitation, thereby improving the water washing property and rainfall washing property of the article surface. Will be fully exhibited.

[Brief description of the drawings]

FIG. 1 is a view showing a state of recovery of hydrophilicity of a surface during BLB irradiation according to an embodiment of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C23C 28/00 C23C 28/00 B G02B 1/10 G02B 1/10 Z

Claims (9)

[Claims] 1. A hydrophilic member, wherein an optical semiconductor layer containing no Co atom is formed on a surface of a substrate, and the surface of the layer exhibits a high degree of hydrophilicity in response to photoexcitation of the optical semiconductor. 2. An optical semiconductor layer containing no Co atoms is formed on the surface of the substrate, and the surface of the layer exhibits a high degree of hydrophilicity in response to photoexcitation of the optical semiconductor, thereby washing with water and / or raining. A member whose surface is cleaned only by washing. 3. An optical semiconductor layer containing no Ni, Fe or Cr atoms is formed on a substrate surface, and the layer surface exhibits a high degree of hydrophilicity in response to photoexcitation of the optical semiconductor. Hydrophilic member. 4. An optical semiconductor layer containing no Ni, Fe or Cr atoms is formed on the surface of the substrate, and the surface of the layer exhibits a high degree of hydrophilicity in response to photoexcitation of the optical semiconductor. And / or a member whose surface is cleaned only by rain washing. 5. An optical semiconductor-containing layer is formed on a surface of a base material containing at least one of Co, Ni, Fe, and Cr atoms via a layer for preventing diffusion of the atomic species. A hydrophilic member, wherein the surface of the layer exhibits a high degree of hydrophilicity in response to photoexcitation of the semiconductor. 6. An optical semiconductor-containing layer is formed on a surface of a base material containing at least one of Co, Ni, Fe and Cr atoms via a layer for preventing diffusion of said atomic species. A member in which the surface of the layer exhibits a high degree of hydrophilicity in response to photoexcitation of the semiconductor, and the surface of which is cleaned only by water washing and / or rain washing. 7. The member according to claim 1, wherein said optical semiconductor-containing layer further contains at least one of silica, solid superacid, and silicone. 8. A layer which can be made hydrophilic such as silica, alumina, solid superacid, silicon, etc., is provided on the optical semiconductor-containing layer.
A member according to claim 1. 9. The member according to claim 1, wherein the base material is a stainless alloy.