JP2000321412A - Anti-fogging mirror for bathroom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhibit a sufficient anti-fogging function over a long period in the anti-fogging mirror for a bathroom by forming a layer containing an alkali metal silicate on the mirror surface having a reflection coat on its rear side. SOLUTION: A layer containing an alkali metal silicate is formed on the mirror surface having a reflection coat on its rear side. A sol coating method is the suitable one with which no constraint related to equipment is present with respect to the size and shape of the mirror. The coating layer is simply formed on the mirror surface without necessitating any special equipment. As the alkali metal silicate, sodium silicate, potassium silicate, lithium silicate or ammonium silicate is appropriately utilized. The coating layer is desirably formed with one or more kinds of inorganic oxide particles included in the layer containing the alkali metal silicate. Thereby desired projecting and recessing parts exhibiting high hydrophilicity are easily formed. In the case the sol coating method, a coating composition comprising 0.05-20 pts.wt. metal oxide and 99.95-80 pts.wt. solvent is preferably utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-fogging property and a drip-proof property which can be suitably used mainly in a bathroom or a shower room under an environment where a large amount of dirt is added to the soil and where a large amount of water vapor or water is constantly applied. The present invention relates to a hydrophilic antifogging mirror for bathrooms having excellent antifouling properties and self-cleaning properties.

[0002]

2. Description of the Related Art As a method for preventing fogging and dirt on a bathroom mirror, it has been conventionally performed to impart hydrophilicity to the mirror surface. Known methods for imparting hydrophilicity include a method of applying a surfactant to a mirror surface and a method of applying a hydrophilic substance such as a hydrophilic monomer or polymer. According to the method of applying a surfactant, water droplets attached to the surface by the surfactant are formed into a water film, so that the hydrophilic monomer
According to the method of applying a polymer, etc., by absorbing water adhering to the mirror surface, adhesion and formation of water droplets are prevented,
It becomes possible to prevent fogging and dirt on the member surface. Japanese Patent Application Laid-Open No. Hei 7-236553 also discloses that once water is applied to a mirror surface made of ground glass in which innumerable scratches are formed to form unevenness parallel to the surface, water that has entered the concave portion is used. Is transparent when it is flat, and fogging is prevented by its water film.

[0003]

The surfactant tends to run off due to moisture, and there is a problem in the sustainability of the effect particularly in an environment where water is frequently applied such as a bathroom. Also,
When a hydrophilic monomer / polymer absorbs water, its surface becomes soft and easily damaged. In particular, when used in an environment having a high vapor pressure under an operating environment such as a bathroom, the amount of water absorption increases, and the tendency becomes very remarkable. Further, there is a disadvantage that both the surfactant and the hydrophilic monomer / polymer easily adsorb dirt and the like in the air. Above all,
In the bathroom, besides dirt caused by metal ions in tap water, soap scum and sebum, etc., cleaning agents used at the time of hair washing and washing, especially silicone oil which is also a moisturizing component in rinsing, cationic system for obtaining a dry feeling Very many contaminants, such as surfactants, which adhere to the mirror surface and change the mirror surface into a property that makes it easier to repel water. Furthermore, they are scattered directly at the time of hair washing / washing, are scattered indirectly by a shower, and are in a state of being easily attached. In addition, since the bathroom is rich in moisture and organic matter, microorganisms are easy to grow especially in uneven parts, and when the mirror surface is given hydrophilicity by unevenness or hydrophilic organic substances, the microorganisms grow and inhibit hydrophilicity. May be. In such an environment where various kinds of dirt are present and are easily adhered, and the pollution load is large, the above-mentioned mirror can exhibit antifogging and antifouling properties only when the initial mirror is in a clean state. It was only during the holding, and it was almost impossible to maintain the antifogging property and antifouling property for a long time. There is also a method of wiping off the adhered dirt every time, but it is time-consuming, and even if it takes time and effort, if oil is applied to the hand, it will inhibit the hydrophilicity by itself, and it is difficult to surely restore the hydrophilicity. Was.

[0004] It is an object of the present invention to provide a hydrophilic anti-fog mirror for bathrooms, which has been difficult to exhibit a sufficient anti-fog function for a long period of time for the above essential reasons.

[0005]

According to the present invention, there is provided a self-cleaning system characterized in that a layer containing an alkali metal silicate is formed on a mirror surface having a reflection coating on the back surface. Provided is a bathroom anti-fog mirror having a function. By forming a layer containing an alkali metal silicate on the mirror surface, the following functions and effects are simultaneously exhibited. (1) The layer containing an alkali metal silicate is a glassy smooth layer, unlike a surfactant or a hydrophilic polymer. Therefore, since there are few irregularities, the amount of dirt attached is small even in the bathroom space where the dirt load is large, and the fixing force is weak.
Furthermore, the alkali ion component in the alkali metal silicate is gradually released from the adhered dirt, so that the mirror surface having the above layer is self-purified for a long time by washing with a shower. (2) The layer containing the alkali metal silicate is a layer made of a hard inorganic material, unlike the surfactant and the hydrophilic polymer. Therefore, the surface is not easily damaged, and the visibility of the mirror is not reduced. (3) The layer containing the alkali metal silicate is a glassy smooth layer, unlike the surfactant and the hydrophilic polymer. Therefore, since there are few irregularities, it is difficult for microorganisms to propagate even in a bathroom with a lot of moisture, and it is also difficult to adsorb dirt and the like in the air.

In a preferred aspect of the present invention, the layer further contains inorganic oxide particles. The inclusion of the inorganic oxide particles not only improves the mechanical strength and abrasion resistance of the surface layer of the mirror, but also makes it possible to control the property of gradually dissolving the alkali metal silicate. As a result, the mirror surface is self-cleansed over a long period of time, preventing dirt from sticking without hassle, repeatedly reproducing a clean and highly hydrophilic surface easily, and providing good antifogging and antifouling properties over a long period of time. Can be maintained.

In a preferred embodiment of the present invention, the height and width of the irregularities on the mirror surface at any position on the mirror surface measured by an atomic force microscope are 0.4 nm or more and 200 nm or less,
An uneven structure having a center line average surface roughness Ra of 0.1 nm or more and 50 nm or less is formed. More preferably, the average height of the unevenness is 0.8 nm or more and 40 nm or less, the average width of the unevenness is 9 nm or more and 100 nm or less, and the center line average surface roughness Ra is 0.1 nm.
At least 10 nm. By forming such an uneven structure on the mirror surface, it is transparent and exhibits high hydrophilicity without deteriorating the texture of the substrate, exhibits sufficient anti-fogging and water droplet preventing effects, adheres contaminants, and rinses with water Thus, it is possible to provide articles with improved cleanliness. The height, width, and surface roughness of the mirror surface can be determined using an atomic force microscope. When measuring a complex and fine uneven surface, the adsorbed water on the surface and the gas entering the surface interfere with each other, and accurate values cannot be obtained with a contact-type surface roughness meter. The measurement is preferably performed using a force microscope. It is preferable that the height and width of the unevenness be の of the wavelength of visible light, that is, 200 nm or less. This is because coloration of the surface layer due to light interference can be prevented, and the texture of the substrate is not impaired. The height and width of the unevenness are preferably 0.4 nm or more. If the height and width of the unevenness are smaller than this, mechanical strength cannot be secured. Surface roughness is mainly determined by the height of the irregularities.
In the cross section of the schematic surface shown in FIG. 1, the surface roughness (R
a) = height / 4. Here, the height of the unevenness is 0.4
Since the thickness is preferably from 200 nm to 200 nm, the surface roughness is preferably from 0.1 nm to 50 nm.

The present invention further provides a bathroom anti-fog mirror, characterized in that the uneven structure is a fractal structure. What is a fractal structure?
This is a multi-stage uneven structure including a large-period uneven structure on the surface of the base material and a small-period uneven structure in the structure. By using a fractal structure, that is, a complex structure having finer irregularities in the irregularities, it is possible to increase the water retention ability of the substrate surface and to express a higher degree of hydrophilicity.

In a preferred aspect of the present invention, the thickness of the layer is set to 400 nm or less. With the above thickness, a transparent film having excellent anti-fogging property and free from light interference and white turbidity can be formed.

In a preferred embodiment of the present invention, the layer is formed by a sol coating method. According to the sol coating method, since there is no restriction on the equipment depending on the size and shape of the mirror, it is possible to easily form a film on the mirror surface without special equipment.

In a preferred embodiment of the present invention, the metal oxide is selected from the group consisting of silica, alumina, zirconia, titania, tin oxide and zinc oxide. By using these oxides, a highly hydrophilic surface having excellent water resistance and chemical resistance can be obtained. Among these metal oxides, it is preferable to use zirconia, titania, tin oxide, and zinc oxide having photocatalytic activity.
In particular, when the mirror has irregularities on the surface, it is difficult to remove dirt from the surface if the dirt adheres to the interior of the concave. By doing so, a higher degree of hydrophilicity can be obtained by indoor lighting or ultraviolet rays from windows.

In a preferred embodiment of the present invention, a layer mainly composed of an alkali metal silicate is further formed on a surface having a concavo-convex structure, and the concavity and convexity at an arbitrary position on the outermost surface measured by an atomic force microscope is measured. The average height and average width are
A layer having a center line average surface roughness Ra of 0.1 nm or more and 50 nm or less. More preferably, the average height of unevenness is 0.1.
8 nm or more and 40 nm or less, unevenness average width 9 nm or more and 100
nm or less, center line average surface roughness Ra 0.1 nm or more and 10
nm or less. By forming more irregularities on the surface on which irregularities have been formed in advance, a better hydrophilic surface can be obtained. Further, even if the surface has interference fringes and cloudiness, there is also an effect of eliminating these and making the surface transparent.

In a preferred embodiment of the present invention, the zeta potential of the mirror surface in water near pH 7 is made negative. By making the zeta potential negative, it becomes possible to provide a bactericidal and / or antifouling effect when water comes into contact with the mirror surface. It is known that dirt and fungi around water are generally negatively charged in water near pH 7. Therefore, by making the zeta potential of the surface of the composite material negative, the surface of the composite material and the dirt and fungi are electrically repelled in a state of contact with water, and the adhesion of dirt and fungi can be prevented.

[0014] In a preferred aspect of the present invention, the mirror has a hydrophilicity such that a receding angle with water on the vertical surface is 20 degrees or less. This is because water adhered to the mirror surface in an upright manner shows a droplet property, and it is easy to exhibit antifouling properties, antifogging properties, waterdrop formation preventing properties, and waterdrop adhesion preventing properties over the entire mirror surface. The term “dropping property” refers to a state in which a water film is formed on a mirror surface in an upright surface such as a bathroom wall without being formed as a water droplet when water is applied. The receding angle is the contact angle of water when a sample is immersed in a water tank at a constant speed and pulled up.

In a preferred embodiment of the present invention, an antibacterial substance is carried on the surface of the mirror. By carrying a substance having antibacterial properties, it is possible to kill bacteria or microorganisms, which are one factor that inhibits hydrophilicity, or to suppress the proliferation, so that good hydrophilicity can be maintained.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The anti-fog mirror of the present invention
Especially in an environment where the amount of added dirt is large and water vapor and water are constantly applied, especially in bathrooms and shower rooms, excellent antifogging, dripproof, antifouling, and self-cleaning hydrophilicity for bathrooms It can be suitably used as an anti-fog mirror.

In the present invention, a sol coating method is preferred as a method for forming a layer containing an alkali metal silicate on the mirror surface having a reflection coating on the back surface. According to the sol coating method, since there is no restriction on the equipment depending on the size and shape of the mirror, it is possible to easily form a film on the mirror surface without special equipment. After forming a layer containing an alkali metal silicate on the surface of a transparent base material, a reflection coating may be applied to the back surface to mirror the surface. Here, as the alkali metal silicate, sodium silicate, potassium silicate, lithium silicate, and ammonium silicate can be suitably used.

In the present invention, it is preferable that the layer containing the alkali metal silicate is coated with at least one kind of inorganic oxide particles. According to this, desired irregularities exhibiting high hydrophilicity can be easily formed. According to the sol coating method, since there is no restriction on the equipment depending on the size and shape of the base material, the sol coating method can be easily performed without requiring special equipment. By increasing the treatment temperature in these methods, it is possible to further improve the durability required in a bathroom environment such as alkali resistance and hot water resistance.

In the present invention, the thickness of the oxide film is set to 400 nm or less. In particular, when a film having a thickness of more than 400 nm is formed using one kind of oxide, interference fringes, turbidity, and the like due to light interference occur, and defects in appearance are likely to occur. Also, as the film thickness increases, the abrasion resistance decreases, and it is inevitable that the film is easily damaged.

Here, as the inorganic oxide, silica, alumina, zirconia, ceria, yttria, boronia,
Magnesia, calcia, ferrite, hafnia, titanium oxide, zinc oxide, tungsten trioxide, ferric oxide, cuprous oxide, cupric oxide, bismuth trioxide, tin oxide,
Single oxides such as nickel oxide, cobalt oxide, barium oxide, strontium oxide, and vanadium oxide, and barium titanate, calcium silicate, water glass, aluminosilicate, calcium phosphate, strontium titanate,
Composite oxides such as potassium titanate, barium titanate, calcium titanate, and aluminosilicate can be suitably used. Among them, it is preferable to use any of silica, alumina, zirconia, titania, tin oxide, and zinc oxide. Silica and alumina are preferred for forming small and fine irregularities, and zirconia and
Titania, tin oxide and zinc oxide are preferred. In the sol coating method, silica, from which various things can be obtained regarding the particle diameter and the sol properties described below, is preferable. Silica is the cheapest and very practical. In addition, silica, zirconia, and the like having a negative zeta potential in water near pH 7;
High hydrophilicity can be obtained by using titania and tin oxide. Preferably, silica having the lowest surface potential is used, and the use of silica can provide a higher degree of hydrophilicity.

In the present invention, the inorganic oxide particles are preferably in the form of a sol dispersed colloidally in water or a hydrophilic solvent. The hydrophilic solvent is not particularly limited as long as it can stably disperse the metal oxide and form a uniform and smooth film on the substrate, but is preferably an organic solvent having a boiling point of 200 ° C. or lower. Solvents can be mentioned. Examples of preferred organic solvents include methanol, ethanol, n-propanol, isopropanol, t-butanol, isobutanol, and n-butanol.
2-methylpropanol, pentanol, ethylene glycol, monoacetone alcohol, diacetone alcohol, ethylene glycol monomethyl ether, 4-
Hydroxy-4-methyl-2-pentanone, dipropylene glycol, propylene glycol, tripropylene glycol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-propoxy -2-propanol, propylene glycol monomethyl ether,
Alcohol solvents such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, and 2-butoxyethanol, and hydrocarbon solvents such as n-hexane, toluene, xylene, and mineral spirits Examples of the solvent include ester solvents such as methyl acetate, ethyl acetate, and butyl acetate.

In the present invention, when a film is formed on the surface of the substrate by the sol coating method, the metal oxide may be used in an amount of 0.0
It is preferable to use a coating composition containing 5 to 20 parts by weight and 99.95 to 80 parts by weight of a solvent. By coating the coating solution on the surface of the base material, a transparent film having excellent antifogging properties and free from light interference and white turbidity can be formed.

In the case of the sol coating method, a granular metal oxide having an average particle diameter of 1 to 100 nm, an average diameter of 1 to 50 n
m, a chain metal oxide having an average length of 10 to 1000 nm, and a feather or rod-shaped metal oxide having an average diameter of 1 to 50 nm and an average length of 10 to 500 nm are preferably used. Examples of the granular metal oxide having an average particle diameter of 1 to 100 nm include silica and zirconia, and an average diameter of 1 to 50 n.
m, as the chain metal oxide having an average length of 10 to 1000 nm, silica, alumina, etc., an average diameter of 1 to 50 nm,
Examples of the feather-like or rod-like metal oxide having an average length of 10 to 500 nm include alumina and titania. If a chain-like, feather-like, or rod-like metal oxide is used, the durability of the film formed on the substrate surface can be improved. Also,
When a granular inorganic oxide is used, a film having desired unevenness and higher smoothness can be formed.

In the present invention, the base material surface layer preferably contains a binder for fixing the metal oxide on the base material surface. This is because the binder improves the adhesion to the substrate surface, and provides higher durability and abrasion resistance. As the binder, an inorganic binder such as glaze, water glass, and silicone, and an organic binder such as a thermosetting resin, a photocurable resin, and a thermoplastic resin can be used.

In the present invention, the coating liquid may contain a surfactant. Examples of surfactants that can be added include polyoxyethylene alkylphenyl ether ammonium sulfonate, sodium polyoxyethylene alkylphenyl ether sodium sulfonate, fatty acid soap, fatty acid sodium soap, dioctyl sodium sulfosuccinate, Alkyl sulfate, alkyl ether sulfate, alkyl sulfate soda salt, alkyl ether sulfate soda salt, polyoxyethylene alkyl ether tersulfate, polyoxyethylene alkyl ether tersulfate Da salt,
Alkyl sulfate TEA salt, polyoxyethylene alkyl ether sulfate TEA salt, 2-ethylhexyl alkyl sulfate sodium salt, sodium acylmethyltaurate, sodium lauroylmethyltaurate, sodium dodecylbenzenesulfonate, lauryl sulfosuccinate Disodium, disodium lauryl polyoxyethylene sulfosuccinate, polycarboxylic acid, oleoyl sarcosine, amide ether sulphate
Anionic surfactants such as sodium, lauroyl sarcosine and sodium sulfo FA ester; polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene acetyl ether, polyoxyethylene stearyl Ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether
Ter, polyoxyethylene alkyl ester, polyoxyethylene alkyl phenol ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene laura
Polyoxyethylene stearate, polyoxyethylene alkylphenyl ether, polyoxyethylene oleate, sorbitan alkyl ester, polyoxyethylene sorbitan alkyl ester, polyether-modified silicone, polyester-modified silicone Sorbitan laurate, sorbitan stearate, sorbitan palmitate, sorbitan sesquioleate, sorbitan oleate, polyoxyethylene sorbitan laurate,
Polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan oleate, glycerol stearate,
Polyglycerin fatty acid ester, alkyl alkylamide, lauric acid diethanolamide, oleic acid diethanolamine, oxyethylene dodecylamine, polyoxyethylene dodecylamine, polyoxyethylene alkylamine, polyoxyethylene octadecylamine, polyoxyethylene alkyl Propylene diamine,
Nonionic surfactants such as polyoxyethylene oxypropylene block polymer and polyoxyethylene stearate; amphoteric surfactants such as dimethyl alkyl betaine, alkyl glycine, amido betaine and imidazoline; octadecyl dimethyl benzyl ammonium chloride, alkyl dimethyl Benzyl ammonium chloride, tetradecyl dimethyl benzyl ammonium chloride, dioleyl dimethyl ammonium chloride, 1
-Hydroxy-2-alkylimidazoline quaternary salt, alkylisoquinolinium bromide, polymer amine, octadecyltrimethylammonium chloride, alkyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, alkylimidazoline Cationic surfactants such as quaternary salts, dialkyldimethylammonium chloride, octadecylamine acetate, tetradecylamine acetate, alkylpropylenediamine acetate, and didecyldimethylammonium chloride.

In the present invention, the method of applying the coating solution on the substrate surface may be appropriately selected from known methods.
Spray coating method using air gun, airless gun, aerosol spray, etc., spin coating method,
Examples include, but are not limited to, dip coating, flow coating, roll coating, brush coating, and sponge coating. In addition, various shampoos, primers, detergents, compounds, antistatic agents, and the like can be used as a treatment before applying the coating liquid to the substrate surface.

The heat treatment after applying the coating solution to the surface of the base material may be appropriately performed according to the type and properties of the coating solution and the base material, and may be any method such as natural drying, heating, and infrared / ultraviolet irradiation. In some cases, the solvent may simply be evaporated and dried. As a method of performing the heat treatment, the surface treatment agent is applied to the surface of the article and then the heat treatment is performed. The number of times of the application and the heat treatment may be two or more. There are various methods such as performing heat treatment at once after repeating application only a plurality of times and performing a series of operations of coating and heat treatment a plurality of times.

In the present invention, as shown in FIG. 4, it is possible to further form an uneven layer composed of a layer containing an alkali metal silicate as a main component on the surface of the substrate on which the unevenness has been formed in advance. The concavities and convexities formed in advance may be selected from known methods, but are preferably formed by a sol coating method, a vacuum deposition method, sputtering, or CVD as described above, and the concavo-convex structure has the height, width, It preferably falls within the range of the surface roughness. The metal oxide forming the uneven layer may be selected from the above-described metal oxides, and it is particularly preferable to use silica, alumina, zirconia, titania, tin oxide, and zinc oxide.
Among these metal oxides, those having photocatalytic activity such as zirconia, titania, tin oxide, and zinc oxide are preferably used. The hydrophilicity of the photocatalyst makes it possible to further enhance the hydrophilicity in the presence of ultraviolet light obtained from indoor lighting, incident light from windows, and the like. Further, the effect of decomposing and deodorizing can be expected by the decomposition function of the photocatalyst. It is preferable to use these oxide sols and form them by a sol coating method. Sols having various particle diameters and properties are available, and an optimum sol can be selected so as to enter the concave portions formed on the surface.
The oxide sol includes the various metal oxides described above, and among them, those having a particle diameter of 50 nm or less are preferable. This is because the surface of the base material surface is increased because of entering the unevenness formed in advance, and the hydrophilicity is further enhanced.

Further, metal particles can be fixed on the outermost surface of the substrate by a photoreduction method. In this case, the hydrophilic function can be enhanced by adding a metal having an electron capturing effect. Metals having an electron trapping effect include Pt, Pd, Au, Ag, Cu, Ni, Fe, C
It refers to metals such as o and Zn which have a small ionization tendency and are easily reduced. These metals may be used in combination. The average particle diameter of these metals is preferably 200 nm or less. This is to prevent color formation and white turbidity due to light interference and irregular reflection.

It is also possible to fill the gaps between the metal oxide layer particles formed on the substrate surface with particles having a smaller particle size than the gaps. By filling the gaps with particles, the surface area of the substrate surface can be increased, which leads to improvement in hydrophilicity. In addition, the particles filled in the gaps can bind the metal oxide layer particles, and the adhesion to the base material is improved. As particles having a particle size smaller than the gap,
Sn, Ti, Ag, Cu, Zn, Fe, Pt, Co, P
d, Ni and the like. If the metal having the electron capturing effect is filled, further improvement in hydrophilicity can be expected.

The outermost surface of the composite material can carry an antibacterial substance. Here, the substance having antibacterial properties may be an organic substance or an inorganic substance. Considering durability such as abrasion resistance, hot water resistance and chemical resistance, P
It is preferable to use metals such as t, Au, Ag, and Cu, or compounds thereof. By carrying these substances having antibacterial properties, it is possible to kill bacteria or microorganisms, which are one factor that inhibits hydrophilicity, or to suppress the proliferation, so it is very effective in maintaining hydrophilicity It is.

[0032]

EXAMPLES Example 1: Lithium silicate Lithium silicate (SiO ₂ solid content concentration 20-21)
%, Li ₂ O solid content concentration of _{2 to} 3.5%)
The sample was applied to a 10 cm square mirror by being included in a cloth, and was naturally dried to obtain a sample. The following five items were evaluated using the above samples. Table 1 shows the results.

Example 2: Lithium silicate + inorganic oxide sol lithium silicate (SiO ₂ solid concentration: 20 to 21)
%, Solid concentration of Li ₂ O _{2 to} 3.5%) and spherical colloidal silica (solid concentration 30 to 31%, particle size 8 to 11 n)
m) was mixed and adjusted so that the solid content ratio was 1% at a solid content ratio of 1: 1 and baked at 150 ° C. for 30 minutes to perform a coating treatment. If the thickness of the coating layer exceeds 400 nm, the transparency is lowered or the strength is lowered. The following five items were evaluated using the above samples. The receding angle was 20 degrees, and there was an initial dropping property. Table 1 shows the results.

Example 3 Treatment of Inorganic Oxide Sol on Irregular Surface By coating with a mixture of lithium silicate and spherical colloidal silica (solid concentration: 30 to 31%, particle diameter: 8 to 11 nm), fine irregularities were formed. The mirror surface thus formed was coated with lithium silicate, and a mixture of the spherical colloidal silica and the lithium silicate having a solid content ratio of 1:10, to obtain two types of samples.
The following evaluation was performed using this sample. In addition, the receding angle was 18 degrees, and there was an initial drip property. Table 1 shows the evaluation results.

Example 4 Treatment of Inorganic Oxide Sol on Irregular Surface The spherical colloidal silica, lithium silicate, the spherical colloidal silica and the lithium were formed on the mirror surface having fine irregularities by treating with a hydrofluoric acid solution. The mixture of the silicates was coated with three types of sols to obtain two types of samples. At the time when the mirror surface was formed with irregularities, slight turbidity was recognized, but no interference fringes and turbidity were recognized at all when the surface was exposed to light by coating the above three types of sols. The following evaluation was performed using this sample. Table 1 shows the evaluation results.

Comparative Example 1: Mirror For comparison with the above-described embodiment, no treatment was applied to 1
A 0 cm square mirror was prepared, and the following five items were evaluated. The receding angle was 22 degrees, and there was no initial drip property. Table 1 shows the results.

Evaluation Items 1. Surface roughness (Ra), average height of unevenness (H), average width of unevenness (L): Measured in an AFM (atomic force microscope) mode of a scanning probe microscope (D3000 manufactured by Digital Instruments). 2. Abrasion resistance: Sliding with a sponge and checking for abnormalities in appearance. ◎: No abnormality at all, ：: Slight scratches that can be seen when exposed to light, △: Shallow scratches, X: Deep scratches reaching the substrate, evaluated on four levels. 3. Droplet: Place the sample on a vertical surface and pour water on it.
After one minute, the state of water wetting was visually checked at the beginning and after one week exposure to the bathroom. ◎: 100% wet area, ○: 80% or more wet area 1
Less than 00%, Δ: 60% or more and less than 80% of water-wetted surface, ×:
Evaluated in 4 steps of less than 60% water wet area. 4. Antifouling property: Stain adhesion after exposure for one week was visually checked. ：: No contamination was observed, and the initial cleanliness was maintained.
：: Slightly adhered, but does not affect use. △: Dirty adhered and there is a part where the mirror is difficult to see. ×: Surface is cloudy with dirt. Rated on a scale. In addition, the sample was exposed for one week below the position of the mirror in the shower booth, and repeated bathing of four persons per day was performed. 5. Cleanability: After applying artificial dirt to the sample, spray it with water by spraying to check the dirt removal. ◎: The dirt is completely removed by one spraying of water, ○: The dirt is completely removed by three to four sprays of water, Δ: 3 to 4 spraying
The dirt is slightly left with the water, but the dirt remains.

[0038]

[Table 1]

As can be seen from Table 1, both the initial and after one week of exposure exhibited good antifogging properties without affecting the reflected image. Further, no stain was attached, and the initial cleanliness was maintained. From this, the layer containing the alkali silicate is formed, or the layer having the alkali silicate as a main component is further formed on the surface of the substrate on which the unevenness is formed in advance to form the unevenness. As a result, it was confirmed that good antifogging properties and antifouling properties were obtained.

Example 5 Five kinds of metal oxide sols of alumina sol, silica sol, tin oxide sol, titania sol and zirconia sol and layers containing alkali silicates were respectively coated on mirror surfaces to obtain samples. After measuring the surface roughness (Ra), average height of unevenness (H), average width of unevenness (L), and zero charge point of each sample, the sample was placed in a bathroom and exposed for 2 weeks. During the exposure period,
Bathing was done by four people a day, and no intentional watering or washing was performed on the mirror surface. For comparison, a normal mirror was similarly installed and exposed. The zero charge point is the pH of the aqueous solution when the zeta potential becomes zero. When the zeta potential is placed in an aqueous solution having a pH higher than the value of the zero charge point, the zeta potential becomes negative, and It will be positive when inserted. The zero charge point of the mirror surface was measured using a laser zeta potentiometer (ELS-6000, manufactured by Otsuka Electronics Co., Ltd.), and the electroosmotic flow was measured using polystyrene latex as a light scattering monitor particle. Of the aqueous electrolyte solution was determined by a titration method. The surface roughness (Ra), the average height of the unevenness (H), and the average width of the unevenness (L) are the values of A of a scanning probe microscope (D3000 manufactured by Digital Instruments).
The measurement was performed in an FM (atomic force microscope) mode. Sample is 2
After weekly exposure, the sample was taken out of the bathroom and visually evaluated according to a four-point scale according to the method for evaluating dropping properties. The results are shown in the table below.

[0041]

[Table 2]

As can be seen from Table 2, the normal mirror has the same zero charge point as the silica sol mirror, but has a water wet area of 60%.
Less than. On the other hand, in the mirrors coated with various sols, the alumina mirror is 60% or more, and the tin oxide / zirconia mirror is 80% or more.
% Or more, and the silica mirror showed a water wetted area of 100%. From the above, it was confirmed that it was difficult to maintain hydrophilicity only by a small value of the zero charge point (negative zeta potential) or only by fine irregularities. That is, by combining the fine irregularities with the zero charge point being less than 7 (the zeta potential is negative in water near pH 7), the lower the zero charge point, the better the hydrophilicity is maintained. It was confirmed that the formation of a water film provided antifogging properties, antifouling properties, waterdrop formation preventing properties, and waterdrop adhesion preventing properties.

Example 6 A 200 mm × 300 mm mirror was prepared. Lithium silicate, colloidal silica, and anatase-type titania sol were mixed and applied to obtain a sample in which irregularities were formed. After forming unevenness with a sol, a silver nitrate aqueous solution was applied thereon, and a sample in which silver was photoreduced and fixed using a BLB lamp was obtained. For comparison, a sample in which silver was directly fixed on the mirror surface was also prepared. After measuring the surface roughness (Ra), the average height of the unevenness (H), and the average width of the unevenness (L) of these samples, mold spores were attached to the surface, placed in a bathroom, and exposed for 2 weeks. Was. Bathing during the exposure period was 4 people a day. Two weeks later, the state of adhesion of dirt and the occurrence of mold was confirmed, and the dropping property was evaluated in the same manner as in Examples 1 to 9. Table 6 shows the results. The surface roughness (Ra), the average height of the unevenness (H), and the average width of the unevenness (L) are as follows:
The measurement was performed in an AFM (atomic force microscope) mode of a scanning probe microscope (D3000 manufactured by Digital Instruments).

[0044]

[Table 3]

As can be seen from Table 3, although no mold was generated on the surface of the comparative sample, dirt was attached to the surface, and the water-wetted area was less than 60%. Met. The sample having irregularities formed by the sol hardly adhered dirt, and barely retained the drip property with a water wet area of 60% or more. However, mold was spotted on the surface, and the portion lost hydrophilicity, which was not preferable for use. On the other hand, the one in which silver is fixed on the unevenness of the sol has surface roughness, average height of unevenness,
Despite the fact that the width was not much different from that of the sample in which the unevenness was formed with the sol, no mold was adhered, and the water-wetted area was 80% or more, and the good dropping property was maintained. From this, it was confirmed that by fixing silver on the unevenness, it was possible to prevent the occurrence of mold on the surface of the member and thereby maintain the hydrophilicity satisfactorily. From the above, it was suggested that the hydrophilicity can be maintained in a favorable state for a long time by combining the unevenness and the antibacterial metal.

[0046]

According to the present invention, an antifogging property and a drip-proofing property which can be suitably used mainly in a bathroom or a shower room under an environment where a large amount of dirt is added and a large amount of water vapor or water is constantly applied. It has become possible to provide a hydrophilic antifogging mirror for bathrooms having excellent antifouling properties and self-purifying properties.

[Brief description of the drawings]

FIG. 1 shows a schematic cross-sectional view of an uneven surface.

FIG. 2 is a schematic cross-sectional view of a case where a substrate is covered with a metal oxide layer to form irregularities.

FIG. 3 is a schematic cross-sectional view showing a case where irregularities are directly formed on a substrate.

FIG. 4 is a schematic cross-sectional view showing a case where irregularities are further formed on the irregular surface.

[Explanation of symbols]

 H: Height of unevenness L: Width of unevenness 1: Base material 2: Metal oxide layer

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 4, 2000 (200.8.4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Detailed description of the invention

[Correction method] Change

[Correction contents]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-fogging property and a drip-proof property which can be suitably used mainly in a bathroom or a shower room under an environment where a large amount of dirt is added to the soil and where a large amount of water vapor or water is constantly applied. The present invention relates to a hydrophilic antifogging mirror for bathrooms having excellent antifouling properties and self-cleaning properties.

[0002]

2. Description of the Related Art As a method for preventing fogging and dirt on a bathroom mirror, it has been conventionally performed to impart hydrophilicity to the mirror surface. Known methods for imparting hydrophilicity include a method of applying a surfactant to a mirror surface and a method of applying a hydrophilic substance such as a hydrophilic monomer or polymer.

According to the method of applying a surfactant, water droplets adhered to the surface are formed into a water film by the surfactant, and according to the method of applying a hydrophilic monomer or polymer, the water adhered to the mirror surface is dispersed. By absorbing water,
It is possible to prevent water droplets from adhering and forming, and to prevent clouding and dirt on the member surface.

Japanese Patent Application Laid-Open No. Hei 7-236553 discloses that a mirror surface made of ground glass having a number of scratches in the horizontal direction and having irregularities parallel to the surface is formed by once applying water to the mirror surface. It is disclosed that when the surface is made flat with water, the surface becomes transparent and the water film prevents fogging.

[0005]

The surfactant tends to run off due to moisture, and there is a problem in the sustainability of the effect particularly in an environment where water is frequently applied such as a bathroom.

The surface of a hydrophilic monomer / polymer becomes soft and easily damaged when it absorbs water. In particular, when used in an environment having a high vapor pressure under an operating environment such as a bathroom, the amount of water absorption increases, and the tendency becomes very remarkable.

Further, both the surfactant and the hydrophilic monomer / polymer have a drawback that they easily adsorb dirt and the like in the air.

[0008] In particular, in the bathroom, in addition to dirt caused by metal ions in tap water, soap scum, sebum, etc., a cleaning agent used at the time of shampooing and washing, especially silicone oil which is a moisturizing component in rinsing, has a dry feeling. Very many contaminants, such as cationic surfactants to be obtained, change the mirror surface into a property that makes it more repellent by adhering to the mirror surface. Furthermore, they scatter directly during hair washing and washing,
The shower is indirectly scattered or easily attached by the shower. Also, since the bathroom is rich in moisture and organic matter, microorganisms are easy to propagate especially in uneven parts,
When the mirror surface is given hydrophilicity by unevenness or hydrophilic organic substances, microorganisms may propagate and inhibit the hydrophilicity.

[0009] In such an environment where various kinds of dirt are present and are easily adhered, and the pollution load is large, the above-mentioned mirror can exhibit the antifogging property and antifouling property because the initial mirror is clean. It was only possible to maintain the proper state, and it was almost impossible to maintain the antifogging property and antifouling property for a long time.

Although there is a method of wiping off the adhered dirt every time, it takes time and effort, and even if it takes time and effort, if the oil is applied to the hands, the hydrophilicity alone will be impaired, and the hydrophilicity is surely restored. It was difficult.

An object of the present invention is to provide a hydrophilic anti-fog mirror for bathrooms, which has been difficult to exhibit a sufficient anti-fog function for a long period of time for the above essential reasons.

[0012]

According to the present invention, there is provided a self-cleaning system characterized in that a layer containing an alkali metal silicate is formed on a mirror surface having a reflection coating on the back surface. Provided is a bathroom anti-fog mirror having a function.

By forming a layer containing an alkali metal silicate on the mirror surface, the following functions and effects are simultaneously exerted. (1) The layer containing an alkali metal silicate is a glassy smooth layer, unlike a surfactant or a hydrophilic polymer. Therefore, since there are few irregularities, the amount of dirt attached is small even in the bathroom space where the dirt load is large, and the fixing force is weak.
Furthermore, the alkali ion component in the alkali metal silicate is gradually released from the adhered dirt, so that the mirror surface having the above layer is self-purified for a long time by washing with a shower. (2) The layer containing the alkali metal silicate is a layer made of a hard inorganic material, unlike the surfactant and the hydrophilic polymer. Therefore, the surface is not easily damaged, and the visibility of the mirror is not reduced. (3) The layer containing the alkali metal silicate is a glassy smooth layer, unlike the surfactant and the hydrophilic polymer. Therefore, since there are few irregularities, it is difficult for microorganisms to propagate even in a bathroom with a lot of moisture, and it is also difficult to adsorb dirt and the like in the air.

In a preferred embodiment of the present invention, the layer further contains inorganic oxide particles.

The inclusion of the inorganic oxide particles not only improves the mechanical strength and wear resistance of the mirror surface layer, but also
It becomes possible to control the property of the alkali metal silicate gradually dissolving. As a result, the mirror surface is self-cleansing for a long period of time, preventing dirt from sticking without hassle,
Reproduces a clean and highly hydrophilic surface easily and repeatedly,
Good antifogging and antifouling properties can be maintained over a long period of time.

In a preferred embodiment of the present invention, the height and width of the unevenness at an arbitrary position on the mirror surface measured by an atomic force microscope are 0.4 nm or more and 200 nm or less,
An uneven structure having a center line average surface roughness Ra of 0.1 nm or more and 50 nm or less is formed. More preferably, the average height of the unevenness is 0.8 nm or more and 40 nm or less, the average width of the unevenness is 9 nm or more and 100 nm or less, and the center line average surface roughness Ra is 0.1 nm.
At least 10 nm. By forming such an uneven structure on the mirror surface, it is transparent and exhibits high hydrophilicity without deteriorating the texture of the substrate, exhibits sufficient anti-fogging and water droplet preventing effects, adheres contaminants, and rinses with water Thus, it is possible to provide articles with improved cleanliness.

The height, width and surface roughness of the mirror surface can be determined using an atomic force microscope. When measuring a complex and fine uneven surface, the adsorbed water on the surface and the gas entering the surface interfere with each other, and accurate values cannot be obtained with a contact-type surface roughness meter. The measurement is preferably performed using a force microscope.

The height and width of the unevenness are 1/1 of the wavelength of visible light.
2, that is, preferably 200 nm or less.
This is because coloration of the surface layer due to light interference can be prevented, and the texture of the substrate is not impaired. The height and width of the unevenness are preferably 0.4 nm or more.
If the height and width of the unevenness are smaller than this, mechanical strength cannot be secured.

The surface roughness is mainly determined by the height of the irregularities, and in the schematic cross section of the surface shown in FIG. 1, the surface roughness (Ra) = height / 4. Here, since the height of the unevenness is preferably 0.4 nm or more and 200 nm or less, the surface roughness is preferably 0.1 nm or more and 50 nm or less.

The present invention further provides a bathroom anti-fog mirror, characterized in that the uneven structure is a fractal structure. What is a fractal structure?
This is a multi-stage uneven structure including a large-period uneven structure on the surface of the base material and a small-period uneven structure in the structure. By using a fractal structure, that is, a complex structure having finer irregularities in the irregularities, it is possible to increase the water retention ability of the substrate surface and to express a higher degree of hydrophilicity.

In a preferred embodiment of the present invention, the thickness of the layer is set to 400 nm or less. With the above thickness, a transparent film having excellent anti-fogging property and free from light interference and white turbidity can be formed.

In a preferred embodiment of the present invention, the layer is formed by a sol coating method. According to the sol coating method, since there is no restriction on the equipment depending on the size and shape of the mirror, it is possible to easily form a film on the mirror surface without special equipment.

In a preferred embodiment of the present invention, the metal oxide is selected from the group consisting of silica, alumina, zirconia, titania, tin oxide and zinc oxide. By using these oxides, a highly hydrophilic surface having excellent water resistance and chemical resistance can be obtained. Among these metal oxides, it is preferable to use zirconia, titania, tin oxide, and zinc oxide having photocatalytic activity.
In particular, when the mirror has irregularities on the surface, it is difficult to remove dirt from the surface if the dirt adheres to the interior of the concave. By doing so, a higher degree of hydrophilicity can be obtained by indoor lighting or ultraviolet rays from windows.

In a preferred embodiment of the present invention, a layer mainly composed of an alkali metal silicate is further formed on a surface having a concavo-convex structure, and the concavity and convexity at an arbitrary position on the outermost surface measured by an atomic force microscope is measured. The average height and average width are
A layer having a center line average surface roughness Ra of 0.1 nm or more and 50 nm or less. More preferably, the average height of unevenness is 0.1.
8 nm or more and 40 nm or less, unevenness average width 9 nm or more and 100
nm or less, center line average surface roughness Ra 0.1 nm or more and 10
nm or less. By forming more irregularities on the surface on which irregularities have been formed in advance, a better hydrophilic surface can be obtained. Further, even if the surface has interference fringes and cloudiness, there is also an effect of eliminating these and making the surface transparent.

In a preferred embodiment of the present invention, the zeta potential of the mirror surface in water near pH 7 is made negative. By making the zeta potential negative, it becomes possible to provide a bactericidal and / or antifouling effect when water comes into contact with the mirror surface. It is known that dirt and fungi around water are generally negatively charged in water near pH 7. Therefore, by making the zeta potential of the surface of the composite material negative, the surface of the composite material and the dirt and fungi are electrically repelled in a state of contact with water, and the adhesion of dirt and fungi can be prevented.

In a preferred aspect of the present invention, the mirror has a hydrophilicity such that a receding angle with water on the upright surface is 20 degrees or less. This is because water adhered to the mirror surface in an upright manner shows a droplet property, and it is easy to exhibit antifouling properties, antifogging properties, waterdrop formation preventing properties, and waterdrop adhesion preventing properties over the entire mirror surface. The term “dropping property” refers to a state in which a water film is formed on a mirror surface in an upright surface such as a bathroom wall without being formed as a water droplet when water is applied. The receding angle is the contact angle of water when a sample is immersed in a water tank at a constant speed and pulled up.

In a preferred embodiment of the present invention, an antibacterial substance is carried on the surface of the mirror. By carrying a substance having antibacterial properties, it is possible to kill bacteria or microorganisms, which are one factor that inhibits hydrophilicity, or to suppress the proliferation, so that good hydrophilicity can be maintained.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The anti-fog mirror of the present invention
Especially in an environment where the amount of added dirt is large and water vapor and water are constantly applied, especially in bathrooms and shower rooms, excellent antifogging, dripproof, antifouling, and self-cleaning hydrophilicity for bathrooms It can be suitably used as an anti-fog mirror.

In the present invention, a sol coating method is preferred as a method for forming a layer containing an alkali metal silicate on the mirror surface having a reflection coating on the back surface. According to the sol coating method, since there is no restriction on the equipment depending on the size and shape of the mirror, it is possible to easily form a film on the mirror surface without special equipment.

After forming a layer containing an alkali metal silicate on the surface of a transparent base material, a reflection coating may be applied to the back surface to mirror the surface.

Here, alkali metal silicates include:
Sodium silicate, potassium silicate, lithium silicate,
Ammonium silicate can be suitably used.

In the present invention, it is preferable that the layer containing the alkali metal silicate contains at least one kind of inorganic oxide particles to form a coating. According to this, desired irregularities exhibiting high hydrophilicity can be easily formed. According to the sol coating method, since there is no restriction on the equipment depending on the size and shape of the base material, the sol coating method can be easily performed without requiring special equipment. By increasing the treatment temperature in these methods, it is possible to further improve the durability required in a bathroom environment such as alkali resistance and hot water resistance.

In the present invention, the thickness of the oxide film is set to 400 nm or less. In particular, when a film having a thickness of more than 400 nm is formed using one kind of oxide, interference fringes, turbidity, and the like due to light interference occur, and defects in appearance are likely to occur. Also, as the film thickness increases, the abrasion resistance decreases, and it is inevitable that the film is easily damaged.

Here, as the inorganic oxide, silica, alumina, zirconia, ceria, yttria, boronia,
Magnesia, calcia, ferrite, hafnia, titanium oxide, zinc oxide, tungsten trioxide, ferric oxide, cuprous oxide, cupric oxide, bismuth trioxide, tin oxide,
Single oxides such as nickel oxide, cobalt oxide, barium oxide, strontium oxide, and vanadium oxide, and barium titanate, calcium silicate, water glass, aluminosilicate, calcium phosphate, strontium titanate,
Composite oxides such as potassium titanate, barium titanate, calcium titanate, and aluminosilicate can be suitably used.

Among them, silica, alumina, zirconia,
It is preferable to use any of titania, tin oxide, and zinc oxide. Silica and alumina are preferred for forming small and fine irregularities, and zirconia, titania, tin oxide and zinc oxide are preferred for forming large irregularities. In the sol coating method, silica, from which various things can be obtained regarding the particle diameter and the sol properties described below, is preferable. Silica is the cheapest and very practical. Further, by using silica, zirconia, titania or tin oxide having a negative zeta potential in water near pH 7, a high degree of hydrophilicity can be obtained. Preferably, silica having the lowest surface potential is used, and the use of silica can provide a higher degree of hydrophilicity.

In the present invention, the inorganic oxide particles are preferably in the form of a sol dispersed in water or a hydrophilic solvent in a colloidal state. The hydrophilic solvent is not particularly limited as long as it can stably disperse the metal oxide and form a uniform and smooth film on the substrate, but is preferably an organic solvent having a boiling point of 200 ° C. or lower. Solvents can be mentioned. Examples of preferred organic solvents include methanol, ethanol, n-propanol, isopropanol, t-butanol, isobutanol, and n-butanol.
2-methylpropanol, pentanol, ethylene glycol, monoacetone alcohol, diacetone alcohol, ethylene glycol monomethyl ether, 4-
Hydroxy-4-methyl-2-pentanone, dipropylene glycol, propylene glycol, tripropylene glycol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-propoxy -2-propanol, propylene glycol monomethyl ether,
Alcohol solvents such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, and 2-butoxyethanol, and hydrocarbon solvents such as n-hexane, toluene, xylene, and mineral spirits Examples of the solvent include ester solvents such as methyl acetate, ethyl acetate, and butyl acetate.

In the present invention, when a film is formed on the surface of a substrate by a sol coating method, the metal oxide may be used in an amount of 0.0
It is preferable to use a coating composition containing 5 to 20 parts by weight and 99.95 to 80 parts by weight of a solvent. By coating the coating solution on the surface of the base material, a transparent film having excellent antifogging properties and free from light interference and white turbidity can be formed.

In the case of the sol coating method, a granular metal oxide having an average particle diameter of 1 to 100 nm, an average diameter of 1 to 50 n
m, a chain metal oxide having an average length of 10 to 1000 nm, and a feather or rod-shaped metal oxide having an average diameter of 1 to 50 nm and an average length of 10 to 500 nm are preferably used.

Examples of the granular metal oxide having an average particle diameter of 1 to 100 nm include silica and zirconia.
Examples of the chain metal oxide having a thickness of 0 nm and an average length of 10 to 1000 nm include silica and alumina, and an average diameter of 1 to 50 n.
Examples of the feather-like or rod-like metal oxide having an average length of 10 to 500 nm include alumina and titania.

When a chain-like, feather-like, or rod-like metal oxide is used, the durability of the film formed on the substrate surface can be improved. In addition, when a granular inorganic oxide is used, a film having desired unevenness and higher smoothness can be formed.

In the present invention, the base material surface layer preferably contains a binder for fixing the metal oxide on the base material surface. This is because the binder improves the adhesion to the substrate surface, and provides higher durability and abrasion resistance. As the binder, an inorganic binder such as glaze, water glass, and silicone, and an organic binder such as a thermosetting resin, a photocurable resin, and a thermoplastic resin can be used.

In the present invention, the coating solution may contain a surfactant. Examples of surfactants that can be added include polyoxyethylene alkylphenyl ether ammonium sulfonate, sodium polyoxyethylene alkylphenyl ether sodium sulfonate, fatty acid soap, fatty acid sodium soap, dioctyl sodium sulfosuccinate, Alkyl sulfate, alkyl ether sulfate, alkyl sulfate soda salt, alkyl ether sulfate soda salt, polyoxyethylene alkyl ether tersulfate, polyoxyethylene alkyl ether tersulfate Da salt,
Alkyl sulfate TEA salt, polyoxyethylene alkyl ether sulfate TEA salt, 2-ethylhexyl alkyl sulfate sodium salt, sodium acylmethyltaurate, sodium lauroylmethyltaurate, sodium dodecylbenzenesulfonate, lauryl sulfosuccinate Disodium, disodium lauryl polyoxyethylene sulfosuccinate, polycarboxylic acid, oleoyl sarcosine, amide ether sulphate
Anionic surfactants such as sodium, lauroyl sarcosine and sodium sulfo FA ester; polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene acetyl ether, polyoxyethylene stearyl Ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether
Ter, polyoxyethylene alkyl ester, polyoxyethylene alkyl phenol ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene laura
Polyoxyethylene stearate, polyoxyethylene alkylphenyl ether, polyoxyethylene oleate, sorbitan alkyl ester, polyoxyethylene sorbitan alkyl ester, polyether-modified silicone, polyester-modified silicone Sorbitan laurate, sorbitan stearate, sorbitan palmitate, sorbitan sesquioleate, sorbitan oleate, polyoxyethylene sorbitan laurate,
Polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan oleate, glycerol stearate,
Polyglycerin fatty acid ester, alkyl alkylamide, lauric acid diethanolamide, oleic acid diethanolamine, oxyethylene dodecylamine, polyoxyethylene dodecylamine, polyoxyethylene alkylamine, polyoxyethylene octadecylamine, polyoxyethylene alkyl Propylene diamine,
Nonionic surfactants such as polyoxyethylene oxypropylene block polymer and polyoxyethylene stearate; amphoteric surfactants such as dimethyl alkyl betaine, alkyl glycine, amido betaine and imidazoline; octadecyl dimethyl benzyl ammonium chloride, alkyl dimethyl Benzyl ammonium chloride, tetradecyl dimethyl benzyl ammonium chloride, dioleyl dimethyl ammonium chloride, 1
-Hydroxy-2-alkylimidazoline quaternary salt, alkylisoquinolinium bromide, polymer amine, octadecyltrimethylammonium chloride, alkyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, alkylimidazoline Cationic surfactants such as quaternary salts, dialkyldimethylammonium chloride, octadecylamine acetate, tetradecylamine acetate, alkylpropylenediamine acetate, and didecyldimethylammonium chloride.

In the present invention, the method of applying the coating solution on the surface of the substrate may be appropriately selected from known methods.
Spray coating method using air gun, airless gun, aerosol spray, etc., spin coating method,
Examples include, but are not limited to, dip coating, flow coating, roll coating, brush coating, and sponge coating.

As a treatment before applying the coating solution to the surface of the substrate, various shampoos, primers, cleaning agents, compounds, antistatic agents and the like can be used.

The heat treatment after applying the coating solution to the surface of the substrate may be appropriately performed according to the type and properties of the coating solution and the substrate, and may be any method such as natural drying, heating, and infrared / ultraviolet irradiation. In some cases, the solvent may simply be evaporated and dried. As a method of performing the heat treatment, the surface treatment agent is applied to the surface of the article and then the heat treatment is performed. The number of times of the application and the heat treatment may be two or more. There are various methods such as performing heat treatment at once after repeating application only a plurality of times and performing a series of operations of coating and heat treatment a plurality of times.

In the present invention, as shown in FIG. 4, it is possible to further form an uneven layer composed of a layer containing an alkali metal silicate as a main component on the surface of the substrate on which the unevenness has been formed in advance. The concavities and convexities formed in advance may be selected from known methods, but are preferably formed by a sol coating method, a vacuum deposition method, sputtering, or CVD as described above, and the concavo-convex structure has the height, width, It preferably falls within the range of the surface roughness.

The metal oxide for forming the uneven layer may be selected from the above-mentioned metal oxides, but it is particularly preferable to use silica, alumina, zirconia, titania, tin oxide, and zinc oxide. Of these metal oxides,
It is preferable to use one having photocatalytic activity, such as zirconia, titania, tin oxide, and zinc oxide. The hydrophilicity of the photocatalyst makes it possible to further enhance the hydrophilicity in the presence of ultraviolet light obtained from indoor lighting, incident light from windows, and the like. Further, the effect of decomposing and deodorizing can be expected by the decomposition function of the photocatalyst.

It is preferable to use these oxide sols and form them by a sol coating method. Sols having various particle diameters and properties are available, and an optimum sol can be selected so as to enter the concave portions formed on the surface. The oxide sol includes the various metal oxides described above, and among them, those having a particle diameter of 50 nm or less are preferable. This is because the surface of the base material surface is increased because of entering the unevenness formed in advance, and the hydrophilicity is further enhanced.

Further, metal particles can be fixed on the outermost surface of the substrate by a photoreduction method. In this case, the hydrophilic function can be enhanced by adding a metal having an electron capturing effect. Metals having an electron trapping effect include Pt, Pd, Au, Ag, Cu, Ni, Fe, C
It refers to metals such as o and Zn which have a small ionization tendency and are easily reduced. These metals may be used in combination.

The average particle diameter of these metals is preferably 200 nm or less. This is to prevent color formation and white turbidity due to light interference and irregular reflection.

It is also possible to fill the gaps between the metal oxide layer particles formed on the substrate surface with particles having a smaller particle size than the gaps. By filling the gaps with particles, the surface area of the substrate surface can be increased, which leads to improvement in hydrophilicity. In addition, the particles filled in the gaps can bind the metal oxide layer particles, and the adhesion to the base material is improved. As particles having a particle size smaller than the gap,
Sn, Ti, Ag, Cu, Zn, Fe, Pt, Co, P
d, Ni and the like. If the metal having the electron capturing effect is filled, further improvement in hydrophilicity can be expected.

The outermost surface of the composite material can carry an antibacterial substance. Here, the substance having antibacterial properties may be an organic substance or an inorganic substance. Considering durability such as abrasion resistance, hot water resistance and chemical resistance, P
It is preferable to use metals such as t, Au, Ag, and Cu, or compounds thereof. By carrying these substances having antibacterial properties, it is possible to kill bacteria or microorganisms, which are one factor that inhibits hydrophilicity, or to suppress the proliferation, so it is very effective in maintaining hydrophilicity It is.

[0053]

EXAMPLES Example 1: Lithium silicate Lithium silicate (SiO2 solid content concentration 20-21)
%, Li2O solid content concentration of 2 to 3.5%)
The sample was applied to a 10 cm square mirror by being included in a cloth, and was naturally dried to obtain a sample. The following five items were evaluated using the above samples. Table 1 shows the results.

Example 2 Lithium silicate + inorganic oxide sol lithium silicate (SiO 2 solid concentration: 20 to 21)
%, Li2O solid content concentration 2 to 3.5%) and spherical colloidal silica (solid content concentration 30 to 31%, particle size 8 to 11n)
m) was mixed and adjusted so that the solid content ratio was 1% at a solid content ratio of 1: 1 and baked at 150 ° C. for 30 minutes to perform a coating treatment. If the thickness of the coating layer exceeds 400 nm, the transparency is lowered or the strength is lowered. The following five items were evaluated using the above samples. The receding angle was 20 degrees, and there was an initial dropping property. Table 1 shows the results.

Example 3 Treatment of Surface of Irregularities with Inorganic Oxide Sol By applying a coating treatment with a mixture of lithium silicate and spherical colloidal silica (solid content: 30 to 31%, particle diameter: 8 to 11 nm), fine irregularities were obtained. The mirror surface thus formed was coated with lithium silicate, and a mixture of the spherical colloidal silica and the lithium silicate having a solid content ratio of 1:10, to obtain two types of samples.
The following evaluation was performed using this sample. In addition, the receding angle was 18 degrees, and there was an initial drip property. Table 1 shows the evaluation results.

Comparative Example 1: Mirror For comparison with the above-described embodiment, no treatment was performed.
A 0 cm square mirror was prepared, and the following five items were evaluated. The receding angle was 22 degrees, and there was no initial drip property. Table 1 shows the results.

Evaluation Items 1. Surface roughness (Ra), average height of unevenness (H), average width of unevenness (L): Measured in an AFM (atomic force microscope) mode of a scanning probe microscope (D3000 manufactured by Digital Instruments). 2. Abrasion resistance: Sliding with a sponge and checking for abnormalities in appearance. ◎: No abnormality at all, ：: Slight scratches that can be seen when exposed to light, △: Shallow scratches, X: Deep scratches reaching the substrate, evaluated on four levels. 3. Droplet: Place the sample on a vertical surface and pour water on it.
After one minute, the state of water wetting was visually checked at the beginning and after one week exposure to the bathroom. ◎: 100% wet area, ○: 80% or more wet area 1
Less than 00%, Δ: 60% or more and less than 80% of water-wetted surface, ×:
Evaluated in 4 steps of less than 60% water wet area. 4. Antifouling property: Stain adhesion after exposure for one week was visually checked. ：: No contamination was observed, and the initial cleanliness was maintained.
：: Slightly adhered, but does not affect use. △: Dirty adhered and there is a part where the mirror is difficult to see. ×: Surface is cloudy with dirt. Rated on a scale. In addition, the sample was exposed for one week below the position of the mirror in the shower booth, and repeated bathing of four persons per day was performed. 5. Cleanability: After applying artificial dirt to the sample, spray it with water by spraying to check the dirt removal. ◎: The dirt is completely removed by one spraying of water, ○: The dirt is completely removed by three to four sprays of water, Δ: 3 to 4 spraying
The dirt is slightly left with the water, but the dirt remains.

[0058]

[Table 1]

As can be seen from Table 1, both the initial and after one week of exposure exhibited good antifogging properties without affecting the reflected image. Further, no stain was attached, and the initial cleanliness was maintained. From this, the layer containing the alkali silicate is formed, or the layer having the alkali silicate as a main component is further formed on the surface of the substrate on which the unevenness is formed in advance to form the unevenness. As a result, it was confirmed that good antifogging properties and antifouling properties were obtained.

Example 4 Layers containing five kinds of metal oxide sols of alumina sol, silica sol, tin oxide sol, titania sol and zirconia sol and alkali silicate were coated on the mirror surface to obtain samples. After measuring the surface roughness (Ra), average height of unevenness (H), average width of unevenness (L), and zero charge point of each sample, the sample was placed in a bathroom and exposed for 2 weeks. During the exposure period,
Bathing was done by four people a day, and no intentional watering or washing was performed on the mirror surface. For comparison, a normal mirror was similarly installed and exposed.

The zero charge point is the pH of the aqueous solution when the zeta potential becomes zero. When the zeta potential is lower than the value of the zero charge point, the zeta potential becomes negative,
It becomes positive when placed in an aqueous solution of H. The zero charge point of the mirror surface was measured using a laser zeta potentiometer (ELS, manufactured by Otsuka Electronics Co., Ltd.)
The electroosmotic flow was measured using polystyrene latex as monitor particles for light scattering, and the pH of the aqueous electrolyte solution when the electroosmotic flow became 0 was determined by a titration method. The surface roughness (Ra), the average height of the unevenness (H), and the average width of the unevenness (L) were measured in an AFM (atomic force microscope) mode of a scanning probe microscope (D3000 manufactured by Digital Instruments). The sample was taken out of the bathroom after exposure for two weeks, and visually evaluated according to a four-stage evaluation according to the method for evaluating the dripping property. The results are shown in the table below.

[0062]

[Table 2]

As can be seen from Table 2, the normal mirror has a zero charge point equivalent to that of the silica sol mirror, but has a water wet area of 60%.
Less than. On the other hand, in the mirrors coated with various sols, the alumina mirror is 60% or more, and the tin oxide / zirconia mirror is 80% or more.
% Or more, and the silica mirror showed a water wetted area of 100%.

From the above, it was confirmed that it was difficult to maintain hydrophilicity only by a small value of the zero charge point (negative zeta potential) or only fine irregularities. That is,
By combining the fine irregularities with the zero charge point being less than 7 (the zeta potential is negative in water near pH 7), the lower the zero charge point, the better the hydrophilicity can be maintained. It was confirmed that the formation of a water film provided antifogging properties, antifouling properties, waterdrop formation preventing properties, and waterdrop adhesion preventing properties.

Example 5 A 200 mm × 300 mm mirror was prepared. Lithium silicate, colloidal silica, and anatase-type titania sol were mixed and applied to obtain a sample in which irregularities were formed. After forming unevenness with a sol, a silver nitrate aqueous solution was applied thereon, and a sample in which silver was photoreduced and fixed using a BLB lamp was obtained. For comparison, a sample in which silver was directly fixed on the mirror surface was also prepared. After measuring the surface roughness (Ra), the average height of the unevenness (H), and the average width of the unevenness (L) of these samples, mold spores were attached to the surface, placed in a bathroom, and exposed for 2 weeks. Was. Bathing during the exposure period was 4 people a day. Two weeks later, the state of adhesion of dirt and the occurrence of mold was confirmed, and the dropping property was evaluated in the same manner as in Examples 1 to 9. Table 6 shows the results. The surface roughness (Ra), the average height of the unevenness (H), and the average width of the unevenness (L) are as follows:
The measurement was performed in an AFM (atomic force microscope) mode of a scanning probe microscope (D3000 manufactured by Digital Instruments).

[0066]

[Table 3]

As can be seen from Table 3, although no mold was generated on the surface of the comparative sample, dirt was adhered, and the water-wetted area was less than 60%. Met. The sample having irregularities formed by the sol hardly adhered dirt, and barely retained the drip property with a water wet area of 60% or more. However, mold was spotted on the surface, and the portion lost hydrophilicity, which was not preferable for use. On the other hand, the one in which silver is fixed on the unevenness of the sol has surface roughness, average height of unevenness,
Despite the fact that the width was not much different from that of the sample in which the unevenness was formed with the sol, no mold was adhered, and the water-wetted area was 80% or more, and the good dropping property was maintained. From this, it was confirmed that by fixing silver on the unevenness, it was possible to prevent the occurrence of mold on the surface of the member and thereby maintain the hydrophilicity satisfactorily. From the above, it was suggested that the hydrophilicity can be maintained in a favorable state for a long time by combining the unevenness and the antibacterial metal.

[0068]

According to the present invention, an antifogging property and a drip-proofing property which can be suitably used mainly in a bathroom or a shower room under an environment where a large amount of dirt is added and a large amount of water vapor or water is constantly applied. It has become possible to provide a hydrophilic antifogging mirror for bathrooms having excellent antifouling properties and self-purifying properties.

 ──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 11-65024 (32) Priority date March 11, 1999 (March 11, 1999) (33) Priority claim country Japan (JP) (72) Inventor Kaori Morihara 2-1-1, Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture Inside Totoki Equipment Co., Ltd. F-term (reference) in Equipment Co., Ltd. 2H042 DA12 DB11 DC04 DE08 3B111 AA01 AC01 AC03 BC01 BC03 BD01 CA03 CB01 CC01

Claims (15)

[Claims] 1. A bathroom antifogging mirror having a self-purifying function, wherein a layer containing an alkali metal silicate is formed on a mirror surface having a reflection coating on the back surface. 2. The antifogging mirror for bathroom according to claim 1, wherein the layer further contains inorganic oxide particles. 3. An average height and an average width of the concavo-convex structure measured by an atomic force microscope at an arbitrary position on the surface of the layer are not less than 0.4 nm and not more than 200 nm, and the center line average surface roughness Ra is not more than 0. The antifogging mirror for bathrooms according to claim 1, wherein the thickness is 1 nm or more and 50 nm or less. 4. An average height of the concavo-convex structure measured by an atomic force microscope at an arbitrary position on the surface of the layer is 0.8 nm.
Not less than 40 nm and an average width of not less than 9 nm and not more than 100 nm.
Hereinafter, the center line average surface roughness Ra is 0.1 nm or more and 10 n
The antifogging mirror for bathrooms according to any one of claims 1 to 3, wherein m is not more than m. 5. The bathroom antifogging mirror according to claim 1, wherein the uneven structure is a fractal structure. 6. The antifogging mirror for a bathroom according to claim 1, wherein the thickness of the layer is 400 nm or less. 7. The bathroom antifogging mirror according to claim 1, wherein the layer is formed by a sol coating method. 8. The inorganic oxide is silica, alumina,
2. A material selected from the group consisting of zirconia, titania, tin oxide, and zinc oxide.
8. The antifogging mirror for bathroom according to items 7 to 7. 9. The antifogging mirror for bathroom according to claim 8, wherein, among the inorganic oxides, zirconia, titania, tin oxide, and zinc oxide are photocatalysts. 10. A bathroom anti-fog mirror having a hydrophilic surface, comprising: a layer having the concavo-convex structure; and a layer mainly composed of an alkali metal silicate on the layer.
The average height and average width of the irregularities at an arbitrary position on the layer surface measured by an atomic force microscope are 0.4 nm or more and 2
00 nm or less, and the center line average surface roughness Ra is 0.1
An antifogging mirror for bathrooms, having a thickness of not less than 50 nm and not more than 50 nm. 11. An average height of irregularities on the surface of the layer is 0.8.
nm to 40 nm, average width 9 nm to 100 nm
Hereinafter, the center line average surface roughness Ra is 0.1 nm or more and 10 n
The antifogging mirror for bathrooms according to claim 10, wherein m is not more than m. 12. The antifogging mirror for a bathroom according to claim 1, wherein the zeta potential of the mirror surface is negative in water near pH 7. 13. The mirror according to claim 1, wherein the mirror has a receding angle of 20 degrees or less with respect to water on the upright surface.
13. The antifogging mirror for bathroom according to any one of items 12 to 12. 14. The antifogging mirror for a bathroom according to claim 1, wherein the mirror contains a substance having antibacterial properties. 15. The bathroom mirror, wherein an antifouling property and / or antifogging property and / or formation of water droplets are formed over the entire surface by forming a water film on the mirror surface by water on the mirror surface or water vapor in contact with the mirror surface. The antifogging mirror for a bathroom according to any one of claims 1 to 14, wherein the antifogging mirror has a property of preventing water droplet adhesion.