JP2000131513A - Surface mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mirror which is advantageous to improve anti-fog property and to prevent flaws in a light-reflecting layer while improving drawbacks of a double reflection. SOLUTION: This surface mirror consists of a base body 1 having a smooth surface where light enters, light-reflecting layer formed on the smooth surface of the base body 1, and photocatalyst layer formed on the light-reflecting layer where light outgoes. The light-reflecting layer is a metal layer 2 such as metal titanium. The photocatalyst layer is made of a metal oxide layer such as titanium oxide (TiO2) layer 3 having photocatalytic property and transparency formed by anodically oxidizing the metal layer such as metal titanium layer 2 as the light-reflecting layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mirror provided with a light reflecting layer on the side of a substrate on which light is incident, and more particularly to a surface mirror having a light reflecting layer formed of a metal layer.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, a titanium oxide layer 101 is formed by vapor deposition on a surface 100a of a glass substrate 100 on which light is incident, and thereafter, a titanium oxide layer 101 is formed.
The crystallization of titanium oxide is promoted by performing atmospheric heating in a temperature range of 0 ° C.
The light reflection layer 102 is laminated by depositing metal aluminum or metal chromium on the light reflection layer 10c.
2 is provided with a mirror coated with a protective film 104. Since the titanium oxide layer 101 has a photocatalytic function, it has good self-cleaning properties, antifouling properties, antifogging properties, and hydrophilic properties.

Assuming that the side on which light is incident is the front surface and the opposite is the back surface, the mirror shown in FIG. 8 employs a back mirror system in which the light reflecting layer 102 is present on the back surface 100c of the glass substrate 100. . In other words, instead of the surface 100a on the light incident side of the glass substrate 100, the glass substrate 10
The light reflection layer 102 is formed on the back surface 100c side of the “0”. The reason is that an external damage force that damages the mirror is usually applied to the mirror from the surface side of the mirror, so that damage to the light reflecting layer 102 having a function of reflecting light is avoided.

[0004]

As described above, when the back mirror system is employed, as described above, the glass substrate 100 is not the surface 100a on the light incident side, but the glass substrate 100. Light reflecting layer 10 on the back surface 100c side of
2 are formed. Therefore, as shown in FIG. 8, the distance α between the reflection surface 102a of the light reflection layer 102 and the surface 101a of the titanium oxide layer 101, which is the outermost surface layer of the surface mirror, is set.
1 is large and the double reflection of the surface mirror may be large.

It is conceivable to adopt a surface mirror system in which a light reflecting layer is laminated on the surface 100a of the glass substrate 100 on which light is incident, but in this case, the essential function of the mirror is to be reduced. The light reflecting layer that is exerted is easily damaged. The present invention has been made in view of the above-described circumstances, and by adopting a metal layer such as a metal titanium layer as a light reflecting layer, it is advantageous to improve the anti-fog property while improving the problem of double reflection. Another object of the present invention is to provide a surface mirror which is advantageous for preventing the light reflecting layer from being damaged.

[0006]

Means for Solving the Problems The present inventor has been diligently developing a surface mirror having a method of laminating a light reflecting layer on the surface on the light incident side of a substrate such as a glass substrate. Was. The present inventor has reported that the photocatalytic substance is titanium oxide (Ti
Metal oxides such as O ₂ ) are typical. A light reflection layer having a function of reflecting light is formed of a metal layer such as a metal titanium layer, and the metal layer itself constituting the light reflection layer is formed. The present invention has been completed, with the idea that a metal oxide layer such as a transparent titanium oxide layer serving as a photocatalytic layer having adhesiveness can be easily formed by anodizing.

That is, a surface mirror according to the present invention comprises a base material having a smooth surface on the side where light is incident, a light reflection layer laminated on the smooth surface of the base material, and a light reflection layer on the exposed surface side of the light reflection layer. A light reflecting layer is formed of a metal layer, and the light reflecting layer is a metal oxide layer having transparency and photocatalytic properties formed by anodizing the metal layer to be the light reflecting layer. It is characterized by being formed by.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A substrate according to the present invention has a smooth surface on a light incident side. A smooth surface is a surface having extremely small surface roughness. The smooth surface may be a flat surface or a curved surface. The substrate can usually be formed of glass containing a silica (SiO ₂ ) component, but may be a resin or a metal such as stainless steel in some cases.

[0009] The light reflection layer is formed of a metal layer laminated on a smooth surface of the substrate. The light reflecting layer is made of a metal (titanium, tin, zinc, bismuth, tungsten, etc.) which is a metal oxide capable of exhibiting a photocatalytic function by physical film forming means (evaporation,
It can be formed by forming a film by sputtering or ion plating) or plating means (electroless plating or electroplating).

A metal layer such as a titanium oxide layer is provided on the surface side of the light reflection layer, and is formed by anodizing a metal layer such as a metal titanium layer constituting the light reflection layer. The metal oxide layer according to the present invention has a photocatalytic function and is dense and transparent. Transparency includes translucent. Anodization is performed by connecting a metal layer to an anode in an electrolytic bath, using the other electrode as a cathode, and applying a voltage between the anode and the cathode to conduct electricity.

When the metal oxide layer is a titanium oxide layer, the titanium oxide layer formed on the titanium metal layer by anodic oxidation has a titanium oxide having anatase crystal rather than a rutile crystal titanium oxide. Is increased, which is advantageous for securing the photocatalytic function. In anodic oxidation, the thickness of the metal oxide layer such as titanium oxide can be controlled by adjusting the applied voltage and time. By adjusting the thickness of a metal oxide layer such as a titanium oxide layer, a large number of colors can be expressed depending on the wavelength of incident light.

According to the surface mirror of the present invention, the thickness of the glass substrate can be about 0.05 to 10 mm, and the thickness of the metal layer such as the titanium metal layer can be about 100 to 100 nm. The thickness of a metal oxide layer such as a titanium oxide layer can be set to about 100 to 400 nm in consideration of the wavelength of ultraviolet light that is a main cause of photoexcitation.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a schematic sectional view of the whole. The glass substrate 1 functioning as a substrate is formed of soda-lime glass containing a silica component (SiO ₂ ). Glass substrate 1
Is a smooth surface. The back surface 1c of the glass substrate 1 is also a smooth surface. A metal titanium layer 2 (Ti) as a metal layer constituting the light reflection layer is formed on the surface 1 a side of the glass substrate 1 by a physical film forming method (evaporation or sputtering).
Is formed.

The titanium oxide layer 3 (titania: anatase: Ti) which can function as a metal oxide layer constituting the photocatalyst layer
O ₂ ) directly coats the metallic titanium layer 2 on the glass substrate 1
It is formed on the surface side of the metal titanium layer 2 by anodizing. The titanium oxide layer 3 is dense, has transparency, and has a photocatalytic function. In this embodiment, the thickness of the glass substrate 1 is about 0.05 to 10 mm, the thickness of the metal titanium layer 2 is about 100 to 1000 nm, and the thickness of the titanium oxide layer 3 is about 200 to 400 nm.

In manufacturing, a glass substrate 1 is used.
The glass substrate 1 is ultrasonically cleaned with acetone as a cleaning liquid. Next, using a vacuum film forming apparatus having a vacuum chamber, after the degree of vacuum in the vacuum chamber reaches 2 × 10 ⁻⁶ Torr, RF reverse sputtering treatment is performed, and heating is performed to 250 ° C. The surface 1a is kept clean. Thereafter, while the glass substrate 1 is being heated, the thick metal titanium layer 2 (thickness: 600 n) is formed on the surface 1a of the glass substrate 1 by vacuum evaporation.
m) is formed.

Next, anodizing treatment is performed on the metal titanium layer 2 to form a titanium oxide layer 3 having a thickness of 200 to 400 nm on the surface side of the metal titanium layer 2. In the anodic oxidation treatment, as shown in FIG. 3, a bath 41 containing an electrolytic solution 40 containing a phosphoric acid aqueous solution containing 1% by weight of phosphoric acid and a DC power supply 44 are used to form a glass substrate having a metal titanium layer 2. The material 1 is immersed in the electrolytic solution 40 together with the counter electrode 43, the metal titanium layer 2 is used as an anode, and the counter electrode is used as a cathode. Then, an anodizing treatment was performed by applying a predetermined voltage among DC voltages (30 to 20 volts). Thus, the surface of the metal titanium layer 2 laminated on the glass substrate 1 was anodized to form a titanium oxide layer 3. When the thickness of the titanium oxide layer 3 formed by anodic oxidation becomes a certain thickness or more,
Current hardly flows.

In anodic oxidation, the thickness of the titanium oxide layer 3 tends to increase as the applied voltage increases. According to the thickness of the titanium oxide layer 3, the color tone of the titanium oxide layer 3 can be changed to golden, brown, blue, purple, green, yellow green, pink, or the like. X-ray diffraction confirmed that the titanium oxide layer 3 formed by such anodization was of an anatase type.

After forming a metal titanium layer 2 (thickness: about 600 nm) on a glass substrate 1 by DC ion plating instead of vacuum deposition, the surface of the metal titanium layer 2 is similarly anodized. A titanium oxide layer 3 was formed on the side. Also in this example, the titanium oxide layer 3 formed by anodic oxidation was confirmed to be an anatase type by X-ray diffraction.

In both the vacuum deposition method and the DC ion plating method, the output was 10 kV and 0.15 A, and the film formation rate was 5.0 angstroms / second. The adhesion strength between the metal titanium layer 2 and the titanium oxide layer 3 was tested. In this exam,
After attaching the tape, the tape was peeled off, and the adhesion strength was evaluated based on the area of the peeled portion. The test was performed immediately after the formation of the titanium oxide layer 3 and was further performed daily until one week had elapsed.
Tests were performed. In this example, the evaluation of the adhesion strength between the metal titanium layer 2 and the titanium oxide layer 3 was good.

As a comparative example, a titanium oxide layer was formed by a sol-gel method on a metal titanium layer formed on a glass substrate in the same manner as in the example. In the sol-gel method, titanium tetrabutoxide was used as a metal alkoxide, a solution in which this was mixed with cyclohexane was prepared, and a glass substrate having a metal titanium layer was dipped in the solution to form a film. Thereafter, the mixture was left to form a gel-like layer,
Formed by heating to ° C.

The same test was performed on the test piece according to this comparative example. In the comparative example, peeling was observed immediately after forming the titanium oxide layer, and the evaluation was not good. With respect to the test piece according to this example, the change in the concentration of each element of oxygen, titanium, and Si in the depth direction was examined by an Auger analyzer. The result is shown in FIG. The horizontal axis in FIG. 2 indicates the depth, and the vertical axis indicates the Auger intensity. In a depth region from 0 to about 200 nm from the surface side, TiO
₂ (anatase) was observed. The region having a depth of about 200 to about 400 nm is a region where TiO ₂ (titanium oxide layer 3) transitions to Ti (metal titanium layer 2). In this region, the composition is TiOx (x = 1 to 2). In the depth region of about 400 to about 550 nm, oxygen is hardly recognized, and Ti (metal titanium layer 2) is formed. In a depth region of about 550 to about 800 nm, Ti, Ti
Ox and SiOx were recognized, and simple Si was also recognized. In the region from about 800 nm to over 1000 nm, Si and oxygen, which are main components of the glass substrate 1, are recognized, and S
The composition is iO ₂ .

As shown in FIG. 2, between TiO ₂ and Ti, a gradient composition portion where the concentration continuously changes was observed. Also between Ti and SiO ₂ , a graded composition portion where the composition continuously changed was observed. It is presumed that the above-mentioned gradient composition part is a factor that increases the adhesion strength of the metal titanium layer 2 and the adhesion strength of the titanium oxide layer 3. Further, a single Si exists between Ti and SiO ₂ . The reason for the existence of elemental Si is that the titanium of the metal titanium layer 2 oxidizes by taking O from SiO _{2 of the} glass substrate 1 and oxidizes to form TiOx due to the strong oxidizing power of the metal titanium. It is presumed to do.

As described above, according to the present embodiment, since the metal titanium layer 2 serving as the light reflecting layer is formed on the surface 1a of the glass substrate 1 on the light incident side, the surface mirror is formed. The distance α2 (see FIG. 1) between the outermost surface layer and the light reflecting layer is small, which is advantageous in improving the problem of double reflection of the mirror. According to the present embodiment, a transparent titanium oxide layer 3 having a photocatalytic function formed by anodizing the metal titanium layer 2 constituting the light reflection layer is formed on the surface side. Therefore, self-cleaning property, antifouling property,
Antifogging property and hydrophilicity are secured.

According to this embodiment, as described above, hydrophilicity on the surface of the surface mirror can be obtained, so that the antifogging property of the surface mirror can be enhanced. Further, the hydrophilicity improves the flowability of water droplets attached to the surface of the surface mirror, and is thus advantageous in preventing icing of water droplets. Further, the surface mirror can be expected to be easily washable, easily dry, and the like. Further according to the present embodiment,
Since the metal titanium layer 2 is protected by the hard titanium oxide layer 3, it is advantageous to prevent the metal titanium layer 2 constituting the light reflection layer having the essential function of a surface mirror from being damaged.

In this embodiment, the titanium oxide layer 3 is formed by anodic oxidation after forming the metal titanium layer 2 by a physical film formation method.
Adopt the process of forming. Since this process is performed at a relatively low temperature, deformation of the glass substrate 1 can be suppressed.
Therefore, it can be expected that the glass substrate 1 is replaced with a resin substrate. According to the present embodiment, by directly anodizing the metal titanium layer 2 after forming the metal titanium layer 2,
The titanium oxide layer 3 integrated with the metal titanium layer 2 is formed. Therefore, the integrity of the titanium metal layer 2 and the titanium oxide layer 3 is improved. That is, the integration of the light reflection layer and the photocatalyst layer is improved.

Further, according to the present embodiment, the thickness of the titanium oxide layer 3 can be adjusted by adjusting the anodic oxidation conditions (voltage, etc.). Therefore, the thickness of the titanium oxide layer 3 and the thickness of the metal titanium layer 2 can be adjusted. That is, the thickness of the photocatalyst layer and the thickness of the light reflection layer can be adjusted according to the use of the surface mirror.
Furthermore, according to the present embodiment, by adjusting the voltage of the anodic oxidation, the color tone of the titanium oxide layer 3 can be changed to golden, brown, blue, purple, green, yellow-green, pink, etc., and the design can be enhanced. .

(Other Examples) In the above-described embodiment, the electrolytic solution 40 composed of an aqueous solution of phosphoric acid containing 1% by weight of phosphoric acid is used in the anodizing treatment. A mixed solution with aqueous hydrogen peroxide can also be used as the electrolyte. In some cases, a mixed solution of phosphoric acid and sulfuric acid can be used as the electrolytic solution. A solution obtained by adding a metal salt such as iron, cobalt, and chromium to a solution obtained by adding a hydrogen peroxide solution to the solution may be used as the electrolytic solution.

(Embodiment 2) Embodiment 2 is shown in FIG. 4 and FIG. The second embodiment has basically the same configuration as the first embodiment, and basically has the same effect as the first embodiment. As shown in FIG. 3, the surface mirror 6 includes a surface mirror holder 60 and a surface mirror main body 61 held by the surface mirror holder 60. The surface mirror main body 61 is composed of a glass substrate 1 formed of glass containing a silica component, and a metal constituting a light reflection layer laminated by vapor deposition on the surface 1 a side of the glass substrate 1 which is a convex curved smooth surface. Titanium layer 2 (thickness: for example, 100 to
1000 nm) and a titanium oxide layer 3 constituting a photocatalyst layer formed by anodic oxidation on the surface side of the metal titanium layer 2.
(Anatase, thickness: 100 to 400 nm, for example).

As shown in FIG. 5, the opposite sides of the glass substrate 1 are not subjected to anodic oxidation by masking to expose the metal titanium layer 2 as it is, thereby providing two metal electrode portions 1x. Keep it. Then, as shown in FIG. 4, a clip-shaped electrode terminal 63 functioning as a terminal means.
Is attached to each metal electrode portion 1x, and each electrode terminal 6
3 is covered with an insulating layer 64 (butyl rubber) to protect it in an electrically insulated state. When electricity is supplied to each electrode terminal 63, the metal titanium layer 2 generates heat, and the antifogging property on the surface of the front mirror is further ensured. Furthermore, the anti-freezing property of the surface mirror in winter or the like is also ensured.

In this embodiment, since the metal titanium layer 2 constituting the light reflection layer can function as a heater layer, a separate heater device can be eliminated. That is, the metal titanium layer 2 according to the present embodiment has both the light reflection function and the heater function. Further, in this embodiment, since the metal titanium layer 2 serving as the light reflection layer can function as a heater layer, the heater layer is located at a position close to the surface layer side of the surface mirror main body 61 and the surface 3a of the titanium oxide layer 3 serving as the surface mirror surface. The efficiency of heat transfer for transferring heat to the heat sink is improved. As described above, the heater heat can be transmitted to the surface of the front mirror 6 at an early stage, which is more advantageous in anti-fogging property and anti-icing property.

(Embodiment 3) Embodiment 3 is shown in FIGS. The third embodiment has basically the same configuration as the first embodiment, and basically has the same effect. As shown in FIG. 6, the surface mirror 7 includes a surface mirror holder 70 and a surface mirror main body 71 held by the surface mirror holder 70. The surface mirror main body 71 is composed of a substrate 75 formed of mirror-polished stainless steel, and a film-shaped metal titanium layer 2 (thickness: 100 to 100) laminated on the surface side of the substrate 77 by electrolytic plating.
1000 nm) and a titanium oxide layer 3 (thickness: 100 to 400 n) formed on the surface side of the metal titanium layer 2 by anodic oxidation.
m).

Since the surface mirror of this embodiment is made of stainless steel, titanium metal, and titanium oxide as main materials, an improvement in durability can be expected. Also in this embodiment,
Since the surface of the surface mirror is composed of the titanium oxide layer 3 having a photocatalytic function and having hydrophilicity, it is advantageous for suppressing generation of water droplets on the surface of the surface mirror.

(Supplementary Note) The following technical idea can be grasped from the above description. A step of forming a light reflection layer on the smooth surface of the substrate by forming a metal titanium layer using a substrate having a smooth surface on the side where light is incident, and a metal titanium layer constituting the light reflection layer Forming a titanium oxide layer having a photocatalytic function and transparency on the surface side of the light reflecting layer by anodizing the surface of the light reflecting layer.

According to this manufacturing method, since the metal titanium layer constituting the light reflecting layer is anodized to form the titanium oxide layer on the surface side of the light reflecting layer, the photocatalytic layer integrated with the light reflecting layer is formed. It is advantageous to do so.

[0035]

According to the surface mirror of the present invention, since the light reflecting layer formed of titanium metal is formed on the smooth surface of the base material on the light incident side, light enters. There is a light reflecting layer on the side. Therefore, the distance between the outermost surface layer of the surface mirror and the light reflecting layer is reduced, which is advantageous for improving the problem of double reflection of the surface mirror.

According to the surface mirror of the present invention, a metal layer such as a titanium oxide layer having a photocatalytic function obtained by anodizing a metal layer such as a metal titanium layer constituting the light reflection layer is provided on the exposed side of the light reflection layer. An oxide layer is formed. Therefore, self-cleaning property, antifouling property, antifogging property, and hydrophilic property on the surface of the surface mirror are secured. Furthermore, according to the surface mirror according to the present invention,
On the surface side of the light reflection layer, a metal oxide layer such as a titanium oxide layer obtained by anodizing a metal layer such as a metal titanium layer constituting the light reflection layer is formed. Therefore, since the light reflecting layer is covered and protected by a hard metal oxide layer such as a titanium oxide layer, it is possible to prevent the light reflecting layer, which performs the essential function of the surface mirror, from being damaged and extend the life of the surface mirror. This is advantageous.

According to the surface mirror of the present invention, a metal oxide layer such as a titanium oxide layer is formed by anodizing a metal layer such as a titanium metal layer. Therefore, a metal oxide layer such as a titanium oxide layer can be formed by a low-temperature process, which is advantageous for suppressing thermal deformation of the base material. Further, the present invention is applicable not only when the substrate is made of glass but also when it is made of resin. According to the surface mirror of the present invention, a metal layer such as a titanium metal layer can be energized and used as a heat generating layer. Therefore, mounting of a separate heater can be eliminated. Further, since the metal titanium layer that can be used as a heater is located near the surface layer of the surface mirror, it is advantageous for improving the antifogging property and the antifreezing property on the surface of the surface mirror.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an enlarged cross section of a surface mirror.

FIG. 2 is a graph showing a distribution of elements in a depth direction.

FIG. 3 is a configuration diagram schematically showing a step of performing anodic oxidation.

FIG. 4 is a cross-sectional view of a surface mirror according to another embodiment.

FIG. 5 is a perspective view of a surface mirror main body constituting the surface mirror.

FIG. 6 is a sectional view of a surface mirror according to still another embodiment.

FIG. 7 is a front view schematically showing a surface mirror.

FIG. 8 is a cross-sectional view schematically showing an enlarged cross-section of a surface mirror according to a conventional example.

[Explanation of symbols]

In the figure, 1 indicates a glass substrate, 2 indicates a metal titanium layer, 3 indicates a titanium oxide layer, and 6 indicates a surface mirror.

Claims (1)

[Claims] 1. A substrate having a smooth surface on a side on which light is incident;
A light reflecting layer laminated on a smooth surface of the base material, and a surface mirror composed of a photocatalytic layer provided on an exposed surface side of the light reflecting layer, wherein the light reflecting layer is formed of a metal layer; A surface mirror, wherein the photocatalyst layer is formed of a metal oxide layer having transparency and photocatalytic properties formed by anodizing the metal layer serving as the light reflection layer.