JP2000178042A - Hydrophilic mirror and processing method thereof - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a hydrophilic mirror which can maintain hydrophilicity even under external influence and which can withstand long-term use, and a method for processing the same. A hydrophilic mirror having a hydrophilic layer formed on the surface of a glass substrate, wherein the portion is made of a metal oxide having an antifouling function that is scattered and distributed on the surface of the glass substrate. 3 is a hydrophilic mirror 1 integrally provided with a hydrophilic layer 5 formed by mixing a portion 4 made of an organic compound having a hydrophilic function. In addition, this hydrophilic mirror 1
Forms a coating layer containing an organic compound having a hydrophilic function and a metal oxide having an antifouling function on the surface of the glass substrate 2 having the reflection film 6 formed on the back surface, and the coating layer contains a large amount of ultraviolet light. To expose the metal oxide on the surface in a scattering distribution state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrophilic mirror and a method of processing the same, and has a function of preventing a decrease in visibility mainly due to adhesion of water droplets on a vehicle mirror in rainy weather. And a method of processing the same.

[0002]

2. Description of the Related Art Conventionally, in a mirror used for a vehicle, visibility is remarkably reduced due to adhesion of water droplets on a normal glass surface in rainy weather. In order to prevent this state, a wiper device is mounted on the mirror. Attached or mechanically treated, such as a mirror with a water-repellent treatment on the mirror surface, a mirror using ultrasonic vibration, or a heater attached to the back of the mirror to evaporate water droplets attached to the mirror surface Many are known.

[0003] Furthermore, a method of applying a surfactant or an organic polymer or a low molecular weight organic compound having a hydrophilic functional group to the mirror surface to obtain a hydrophilic property, such as a method of obtaining a higher hydrophilicity than the conventional one, will be used. Have recently been proposed and are being put to practical use. Many proposals have been made for techniques for performing a process for preventing a decrease in visibility on the mirror surface. For example, Japanese Patent Application Laid-Open No. 8-227006 discloses a mirror in which a reflective coating is applied to one surface of a glass substrate. In the above, a surface layer made of a metal oxide is provided on the surface opposite to the coating surface of the glass substrate with a fine uneven shape, and a hydrophilic low-molecular organic compound layer is provided on the underlayer. Are disclosed.

Japanese Patent Application Laid-Open No. Hei 9-226531 discloses a vehicle mirror having a surface layer containing substantially transparent photocatalyst particles on the surface of a vehicle mirror with a heater. In this method, a photocatalyst is photoexcited by forming a surface layer containing silica, thereby making the photocatalyst hydrophilic. In addition, a titanium oxide film is formed on the surface of a glass substrate of a mirror in JP-A-10-36144, and a transparent inorganic oxide film is formed on a porous surface so that hydrophilicity can be obtained. Things are disclosed.

[0005]

However, these prior arts have the following problems. At present, not all water droplets can be eliminated in mirrors using water repellent treatment and ultrasonic waves, and small water droplets remain depending on the degree of water repellent function, such as headlights of following vehicles during night driving. Light impinges on the adhering water droplets, causing a light diffusion phenomenon like a chandelier, and visibility is remarkably reduced.
The use of a surfactant generally does not last long due to a short water retention time on the mirror surface due to water solubility.

In the method of applying an organic polymer material to the mirror surface, the abrasion resistance is poor and foreign matter in the air adheres to the surface after drying, and the hydrophilic effect cannot be sufficiently exhibited. Heater-based mirrors require a considerable amount of time for the heat of the heater to conduct on the mirror surface and for the water droplets to evaporate.

[0007] Furthermore, in recent mirrors which are formed by forming a hydrophilic layer by physically or chemically treating the mirror surface, 5) a low molecular organic compound is formed on a glass substrate surface as an underlayer and pits are formed on the underlayer. After forming a hole, a hydrophilic mirror in which a metal oxide is embedded in the hole (for example, Japanese Patent Application Laid-Open No.
In Japanese Patent No. 227006, there is an attempt to impart hydrophilicity and antifouling function. However, if a layer that generates structurally hydrophilicity is placed on the underlying layer with emphasis on hydrophilicity, the antifouling function is reduced and the antifouling function is reduced. If the emphasis is placed, there is a problem that the hydrophilicity is inferior. Further, in the structure of a pit having a low molecular weight organic compound as a lower layer and a metal oxide as a lower layer, there is a disadvantage that the adhesion of the metal oxide is basically deteriorated due to an effect such as an antifouling function.

[0008] 6) A hydrophilic mirror in which a transparent metal oxide (TiO ₂ ) is uniformly formed on the surface of a glass substrate and an inorganic oxide film (SiO ₂ ) or the like is formed in a porous state on an upper layer. In Japanese Unexamined Patent Publication No. Hei 10-36144, for example, the hydrophilicity and antifouling function are to be imparted in the same manner as in the above 5), but when NOx adheres to a structurally porous portion (exhaust gas of a vehicle) The metal oxide film (TiO ₂ ) is nitrated by the photocatalytic function of the metal oxide film (TiO ₂ ) by water and light (ultraviolet light), accompanied by deterioration of the inorganic oxide (inorganic oxide film) that produces hydrophilicity. In this case, if the surface layer is deteriorated, the durability can be secured to some extent in a state such as consumption of the inorganic oxide, but the inorganic oxide that produces hydrophilicity is formed on a metal oxide having a photocatalytic function. Therefore, there is a problem that peeling deterioration is caused, adhesion of the inorganic oxide is impaired, and the effect of hydrophilicity is deteriorated.

The present invention has been made in order to solve such problems, and provides a hydrophilic mirror which can maintain hydrophilicity even under external influence and which can withstand long-term use, and a method of processing the same. The purpose is to do so.

[0010]

In order to achieve the above-mentioned object, a hydrophilic mirror according to the present invention is a hydrophilic mirror having a hydrophilic layer formed on the surface of a glass substrate. Wherein a hydrophilic layer formed by mixing a portion that scatters and distributes a metal oxide having an antifouling function and a portion of an organic compound that has a hydrophilic function is provided integrally on the surface of the glass substrate. It is assumed that.

According to the hydrophilic mirror of the present invention configured as described above, the hydrophilic layer formed on the surface of the glass substrate constituting the mirror has a portion where the metal oxide having an antifouling function is scattered and distributed. Since the organic compound part having the function is mixed and formed, the surface is not uniformly flat unlike the conventional hydrophilic mirror, and the metal oxide part and the organic compound part appear as a mixture in the surface layer. At the same time, since dents are formed between the two, a hydrophilic area is increased to enhance the hydrophilic effect, and the working surface of the metal oxide is also increased, thereby improving the antifouling function. As a result, an effect of increasing the hydrophilic effect by reacting even with minute water droplets is achieved. In addition, since the metal oxide scattered on the fixed hydrophilic layer is in a state of being held by the organic compound around its surface excluding the projecting portion, even if the nitric acid reaction is affected by the outside air, the metal oxide may be separated. It has the effect that it can be maintained for a long time and its function can be exhibited for a long time.

Further, in the hydrophilic mirror of the present invention, it is preferable that a heater is brought into contact with the back surface of the reflection film layer of the glass substrate. In this way, in addition to the effect of evaporating water droplets on the mirror surface, which is the effect of the heater alone, a more excellent effect is exhibited in combination with the effect that the water film on the mirror surface easily flows due to heat. Can be done.

Next, a method for processing a hydrophilic mirror according to a second invention is to provide a method for forming a surface of a glass substrate having a reflection film formed on a back surface.
Forming a coating layer containing an organic compound having a hydrophilic function and a metal oxide having an antifouling function, and irradiating the coating layer with light containing a large amount of ultraviolet rays to expose the metal oxide in a scattering distribution state on the surface. It is characterized by the following.

By doing so, the hydrophilic mirror having high antifouling function and high hydrophilic function according to the first aspect of the present invention, in which the metal oxide is dispersed and fixed in a stable state, can be easily obtained.

Further, the coating layer containing the organic compound having a hydrophilic function and the metal oxide having an antifouling function is formed by applying a solution containing the organic compound having a hydrophilic function and the metal oxide having an antifouling function. It is preferable to form a film and then bake and dry the applied film at a temperature that does not affect the reflective film. In this case, the metal oxide can be easily scattered and distributed, and the organic compound can be easily fixed on the glass substrate surface. In order to apply such a solution of the organic compound containing a metal oxide, a dipping method, a flow coating method, a roll coating method, a spray coating method, or the like can be adopted. It is better to Then, the formed coating film can be fixed on the surface of the glass substrate by baking in a temperature range where the reflection film is not affected.

Further, the coating layer containing the organic compound having a hydrophilic function and the metal oxide having an antifouling function may be made of a metal material to be scattered and distributed on a glass substrate in a vacuum furnace or an inert gas furnace. The mixture of the oxidation promoter is heated and evaporated to distribute and fix the metal oxide on the upper surface of the glass substrate, and the organic compound is formed by applying and drying the organic compound on the upper surface of the glass substrate on which the metal oxide is distributed and fixed outside the furnace. Good. In this case, it is easy to regulate the amount of the metal oxide to be scattered and distributed on the upper surface of the glass substrate, and to facilitate the fixation to the glass surface.

Means for obtaining a light beam containing a large amount of ultraviolet light used for light irradiation for making the film layer formed as a hydrophilic layer in the present invention function as a hydrophilic layer include a light having a wavelength of 100 to 400 nm.
It is preferable to use m light sources. Plasma light, corona light, and excimer laser can be used as such a light source. By irradiating light having such a wavelength, the surface of the coating film (coating) is modified, and it becomes easy to expose a part of the scattered and distributed metal oxide material on the surface. And it is easy to increase durability. As the metal oxide used in the present invention, TiO ₂ having a high antifouling function is used. As the organic compound, a low molecular weight organic compound such as a fatty acid ester or a carboxylic acid ester is used.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of a hydrophilic mirror and a method for processing the same according to the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged sectional view of a main part showing the structure of the hydrophilic mirror according to the first invention. As shown in FIG. 1, the hydrophilic mirror 1 of the present embodiment has a portion 3 made of metal oxide and a hydrophilic organic material on the surface of the mirror substrate 2 opposite to the reflection surface forming portion 6 of the glass substrate 2. The structure is such that a hydrophilic layer 5 in which a portion 4 made of a compound is mixed is formed.

As the glass substrate 2 in the present embodiment,
A known glass plate generally used as a mirror is used.

In order to process the hydrophilic mirror 1 having the hydrophilic layer 5 formed on one surface, a reflective film 6 is previously formed on the back surface of the glass substrate 2 by a known means. Next, the hydrophilic layer 5 is formed on the surface of the glass substrate 2 having the reflection film 6 on the back surface.
A sol solution in which a metal oxide 3 having an antifouling function and an organic compound 4 having a hydrophilic function are dispersed and mixed is formed by coating.

As a coating solution used here, a suspension in which a fluororesin is dispersed in water or an organic solvent using a surfactant is mixed with a liquid in which a metal oxide (for example, titanium oxide (TiO ₂ )) is dispersed. A sol solution consisting of

The coating means can be selected and adopted according to the size of the mirror surface, such as a dipping method in which a glass substrate is dipped in a sol solution bath and pulled up, a flow coating method, a roll coating method, a spray coating method, or the like. It is preferable that the thickness of the coating film is 0.5 μm or less at the time of film formation. The thickness of the sol solution is preferably adjusted by adjusting the viscosity of the sol solution. As the film thickness increases, the surface becomes cloudy and the transparency decreases.

As a drying means for fixing the coating film formed on the surface of the glass substrate 2, the organic film is heated by heating to a range which does not affect the reflection film 6 formed on the back surface of the glass substrate 2. The coating layer of the compound and the metal oxide is baked. In this case, the temperature is preferably 180 ° C. or less.

The coating layer of the organic compound and the metal oxide, which is formed on the surface of the glass substrate 2 in this manner, has its surface hardness increased by firing, and at the same time, is fixed to the glass surface and is stable. However, the intended hydrophilic effect is weak and the antifouling function cannot be exhibited.

Therefore, the coating layer is irradiated with a light beam containing a large amount of ultraviolet rays to perform a surface modification treatment. In this case, the coating layer is instantaneously dissolved by the energy of the irradiated light, the surface state is modified, and the metal oxide particles in the state of being wrapped in the organic compound cover the surface of the organic compound. Is removed and exposed. As a result, some of the dispersed particles of the metal oxide mixed in the coating film layer are exposed and scattered on the surface. In addition, the organic compound in the vicinity of the exposed portion of the metal oxide becomes a depression corresponding to the difference in the amount of energy absorption at the time of the light irradiation, and fine irregularities occur on the surface of the coating layer, and the surface area increases. .

A coating layer (coating layer) in which a metal oxide is mixed with the organic compound thus formed on the surface of the glass substrate.
Is in a state where the hydrophilic function and antifouling function possessed by each can be fully exhibited, and the metal oxide portion is firmly held by the bonding force of the organic compound on the glass substrate surface, and the exposed portion has the antifouling function. Demonstrate, and the organic compound can further enhance the hydrophilic function by increasing the surface area due to unevenness,
It becomes a hydrophilic layer that functions so that water droplets adhering to the surface quickly become a uniform water film.

Further, the hydrophilic layer thus formed on the glass substrate has a structure in which the metal oxide exhibiting the antifouling function is held by the portion of the organic compound exhibiting the hydrophilic function as described above. Since they are arranged in a state, even if they are exposed to the air and cause a nitric acid reaction due to NOx or the like, they can function for a long time without being easily separated.

As a result, the hydrophilic mirror according to the present invention
Compared to conventionally known hydrophilic mirrors, the wettability of water droplets on the surface of the hydrophilic layer is maintained for a longer period of time, and it is used as a vehicle mirror so that even when it is raining, the visibility of water droplets on the mirror surface remains unchanged. This has the effect that the field of view is not interrupted and the field of view can always be secured.

In the hydrophilic mirror 1 of this embodiment, as shown in FIG. 1, a heater 7 is provided behind a reflective film layer 6 formed on the back surface of the glass substrate 2 of the mirror. In this case, when the glass substrate 2 is heated, the action of heating and evaporating the attached water in the hydrophilic layer 5 and the water film in a wet state easily flow, thereby promoting the fluidization of the subsequently attached water droplets. The effect of promptly removing obstacles due to water droplets on the mirror surface can be exhibited.

Next, working examples of the hydrophilic mirror according to the present invention will be described.

[0032]

EXAMPLE 1 A suspension of a fluororesin dispersed in water or an organic solvent using a surfactant (fatty acid ester) on the surface of a glass substrate made of a well-known glass material having a reflective film on the back surface. Liquid and metal oxide (titanium oxide (Ti
A sol solution obtained by mixing a solution in which O ₂ ) is dispersed is applied by a dipping method to form a coating layer in which metal oxide particles are dispersed and mixed in an organic compound. The thickness of the coating layer is adjusted by adjusting the viscosity of the sol solution. The thickness of the coating film formed here is adjusted within 0.5 μm. The formed coating layer is baked and dried at a temperature of 160 ° C. In this case, baking and drying are performed at the maximum temperature in a temperature range in which the reflection film formed on the back surface of the glass substrate is not damaged. It is preferable that the firing temperature be higher in order to increase the surface hardness.

Next, the coating layer fixed by baking and drying on the surface of the glass substrate is irradiated with intense light containing a large amount of ultraviolet rays, in this example, plasma light to modify the surface. The irradiated plasma light is emitted using a light source centered at 180 nm. An example of the irradiation device is represented by a schematic diagram shown in FIG. In this example, electrodes 12 and 13 are vertically arranged at required intervals in a closed chamber 11, and a high-frequency current is applied to one of the electrodes 12 from a high-frequency power supply 14 through a matching unit 15. The chamber 11 is supplied with, for example, helium or a mixed gas mainly containing helium from the discharge gas supply source 16 (supply system) into the chamber 11 from the outside.
The other is connected to a piping 17 of an exhaust system, and uses a plasma irradiation apparatus 10 that can discharge generated exhaust gas to the outside.

The sample (1) having the coating layer formed by the above-described process is placed on one electrode 13 in the chamber 11 of the plasma irradiation apparatus 10 as described above. Plasma irradiation is performed for 5 minutes. The irradiation time is determined by the wettability test method (JIS K676).
Judgment is made based on the degree of the wetting index based on 8). In this case, the coating layer is modified with high energy by the plasma light, and the organic substances on the upper surface of the metal oxide particles in the surface layer are removed and exposed to the surface. In addition, a part of the organic compound partially evaporates between the dispersed metal oxide particles, resulting in a state in which irregularities are generated on the surface, and at the same time, the coating layer is further hardened and solidified on the glass substrate. Is established.

The thickness of the thus-modified hydrophilic layer on the surface of the hydrophilic mirror is in the range of about 5 to 200 °. In addition, as a result of confirming the hydrophilic effect of the mirror surface by the above-mentioned wettability test method, the mirror surface showed a wet state without water repellency.

As the light irradiation device, an atmospheric plasma irradiation device 10A as schematically shown in FIG. 3 can be used in addition to the closed-type irradiation device as shown in FIG. In this device, a high-voltage current is passed from an alternating-current high-voltage source 22 to a pair of dielectrics 21 and 21 arranged at required intervals in an open state, and a discharge space 23 formed between the dielectrics 21 and 21 is formed. The plasma irradiation is performed in a state where the sample is placed in the discharge space 23 and the helium gas is filled in the discharge space 23. The surface modification as described above can be performed by such a plasma irradiation apparatus 10A.

(Example 2) A glass substrate having a reflective film on the back side was placed on the upper part of a vacuum furnace (or an inert gas furnace (nitrogen gas)), and the lower part was placed in a crucible heated by a heat source by an electric heater. And a metal compound (eg, titanium nitrate and potassium nitrate as an oxidation promoter) is placed therein. When the furnace conditions (0.5 atm or less) were established, the heat source of the crucible was actuated to heat the contents, so that the material was evaporated and scattered so as not to be charged, and scattered on the glass substrate. The metal oxide is scattered and attached. A glass substrate is taken out of the furnace, and a coating film made of an organic compound (such as a fatty acid ester) is formed on the surface. In this case, drying of the coating film
After natural drying, baking is performed at a temperature of 180 ° C. or less (the maximum temperature that does not affect the reflective film). By performing the same surface modification as in Example 1 on the thus-obtained coating layer, a mirror having high hydrophilicity can be obtained.

(Example 3) A glass substrate having a reflective film on the back surface is irradiated with strong light (plasma light, etc.) containing a large amount of ultraviolet rays, and has a surfactant (fatty acid ester, etc.) and a water-soluble film on the surface. A sol solution composed of a metal oxide (TiO ₂ ) is applied to form a coating layer. After natural drying, baking is performed at a temperature of 180 ° C. or less (the maximum temperature that does not affect the reflective film). By performing the same surface modification as in Example 1 on the coating layer thus obtained,
A highly hydrophilic mirror is obtained.

In any of these embodiments, the hydrophilic layer formed on the glass substrate is not formed on a two-dimensional surface but on a three-dimensional structure having a depth and a height. It has the property of reacting to water droplets smaller than the size of the water droplets that exhibit the effect of the hydrophilic mirror.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part showing a configuration of a hydrophilic mirror according to a first invention.

FIG. 2 is a schematic diagram of a closed-type plasma irradiation apparatus.

FIG. 3 is a schematic diagram of an atmospheric irradiation device.

[Explanation of symbols]

 Reference Signs List 1 hydrophilic mirror 2 glass substrate 3 part made of metal oxide 4 part made of organic compound 5 hydrophilic layer 6 reflection film 7 heater 10, 10A plasma irradiation device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 5/08 G02B 1/10 Z F-term (Reference) 2H042 DB11 DB12 DE01 2K009 AA12 BB02 CC03 DD02 DD05 EE02 3D025 AA02 AC09 AC20 AD13 4G059 AA01 AA11 AB03 AB09 AC21 EA04 EB05 FA11 FB05 FB06 GA01 GA04 GA16 4J038 CD091 EA011 GA12 HA216 MA07 MA10 NA05 NA06 PC03

Claims (6)

[Claims] 1. A hydrophilic mirror having a hydrophilic layer formed on the surface of a glass substrate, wherein the hydrophilic mirror has a portion that scatters and distributes a metal oxide having an antifouling function on the surface of the glass substrate. A hydrophilic mirror, wherein a hydrophilic layer formed by mixing organic compound portions is integrally provided. 2. The hydrophilic mirror according to claim 1, wherein a heater is brought into contact with the back surface of the reflective film layer of the glass substrate. 3. A coating layer containing an organic compound having a hydrophilic function and a metal oxide having an antifouling function is formed on the surface of a glass substrate having a reflective film formed on the back surface, and the coating layer contains a large amount of ultraviolet rays. A method for processing a hydrophilic mirror, comprising irradiating light to expose the metal oxide on the surface in a scattering distribution state. 4. The coating layer containing an organic compound having a hydrophilic function and a metal oxide having an antifouling function is formed by applying a solution containing the organic compound having a hydrophilic function and a metal oxide having an antifouling function. 4. The method for processing a hydrophilic mirror according to claim 3, wherein the coating film is formed by baking and drying at a temperature that does not affect the reflection film thereafter. 5. A coating layer containing an organic compound having a hydrophilic function and a metal oxide having an antifouling function, wherein the coating layer contains a metal substance to be scattered and distributed on a glass substrate in a vacuum furnace or an inert gas furnace. The mixture of the oxidation promoter is heated and evaporated to disperse and fix the metal oxide on the upper surface of the glass substrate, and an organic compound is applied and dried on the upper surface of the glass substrate on which the metal oxide is distributed and fixed outside the furnace. 4. The method for processing a hydrophilic mirror according to item 3. 6. The hydrophilic liquid according to claim 3, wherein a light source having a wavelength of 100 to 400 nm is used as a means for obtaining a light beam containing a large amount of ultraviolet light used for light irradiation for making the formed film layer function as a hydrophilic layer. Processing method of sex mirror.