JPH11130468A - Plate glass provided with photocatalyst film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst film-coated plate glass capable of activating the photocatalyst films by irradiating two photocatalyst films formed on the both surfaces of plate glass respectively, with exciting light without exposing human bodies to ultraviolet rays and accordingly, exhibiting an antifogging function. SOLUTION: This photocatalyst film-coated plate glass is provided with two photocatalyst films 3 formed on the surface and rear of plate glass 1 respectively. Also, a light source 5 is placed in an appropriate position in an edge face of the plate glass 1 or in the peripheral part of any one of the surface and rear of the plate glass 1, in which position no photocatalyst film 3 is formed, in such a way that exciting light 2 is not leaked out from the position, and/or the incidence plane of the exciting light 2 from the light source 5 is appropriately designed, to repeatedly subjecting the exciting light 2 made incident on the inside of the plate glass 1 from this position to total reflection within the plate glass 1 and to propagate the exciting light 2 within the plate glass 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet glass used for transportation equipment such as a vehicle, for display of a show window or a show case, or as a window material for general buildings, and the like. By forming a photocatalyst film on both surfaces and irradiating it with excitation light (ultraviolet light), the photocatalyst film is activated photochemically, and organic dust adhering to the plate glass (window material) is decomposed and removed. To impart hydrophilicity to the sheet glass (window material) and to suppress the generation of dew drops of water vapor based on the difference in temperature and humidity between one side and the other side, and in particular, the excitation light (ultraviolet light)
The present invention relates to a glass with a photocatalytic film designed so as not to adversely affect the human body.

[0002]

2. Description of the Related Art Photocatalytic substances (for example,
TiO ₂ semiconductors) are excited by high-energy light (ultraviolet light) to generate electron-hole pairs, and these electrons (e-) and holes (h +) oxidize the adsorbed and adhering substances on the surface. Reduce,
For example, organic substances are decomposed, oxidized and reduced, and removed. Photocatalytic substances decompose and remove adsorbed organic substances (hydrophobic substances) to make them hydrophilic, and water is chemically adsorbed on the surface of the photocatalytic substance in the form of -OH. It is believed that the adhering water combines therewith to form a smooth water film, preventing dew drops or fogging of the water.

[0003] Excitation light is required for activating the photocatalytic substance, and sunlight (ultraviolet region) is also an effective activating means. However, in places where sunlight is not sufficiently incident, ultraviolet light as excitation light is used. Need to be irradiated. However, ultraviolet rays are harmful to human health, such as causing inflammation and sometimes cancer when they come into contact with human eyes and skin.

[0004] It is an object of the present invention to provide a photocatalytic film-coated glass which eliminates the above-mentioned adverse effects upon irradiation with ultraviolet light.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a plate glass with a photocatalytic film. 1) A photocatalytic film is formed on the front and back surfaces of the plate glass, an excitation light source of the photocatalyst leaks from an end surface of the plate glass, and excitation light leaks from the end surface. A glass sheet with a photocatalytic film, which is arranged so as not to be incident, and the excitation light is incident on the glass sheet from the end face of the glass sheet, and is totally reflected inside the glass sheet repeatedly to propagate through the glass sheet.

2) A photocatalyst film is formed on the front and back surfaces of the sheet glass, and an excitation light source of the photocatalyst is applied to an appropriate portion of one peripheral edge of the sheet glass where the photocatalyst film is not formed. Arranged so as not to leak, the excitation light is incident on the plate glass from the location, and the refraction angle γt of the excitation light on the one surface XX ′ is set so that the excitation light is repeatedly totally reflected in the plate glass and propagates in the plate glass. Plate glass with photocatalytic film set.

3) A plate glass with a photocatalytic film, in which the excitation light incidence conditions are adjusted so that the refraction angle γt of the incident excitation light with respect to one surface XX ′ is 41.8 ° or more.

4) The plate glass with a photocatalyst film according to the above 2) and 3), wherein the glass surface at the excitation light incidence point is inclined with respect to one surface XX '.

5) The photocatalyst according to the above items 1) to 4), wherein a light-introducing hologram or a prism is added to the excitation light-incident portion, and the excitation light is incident through the light-introducing hologram or the prism. Plate glass with membrane.

6) The sheet glass with a photocatalytic film according to the above items 1) to 5), wherein a transparent oxide film having a lower refractive index than the photocatalytic film is interposed between the photocatalytic film and the sheet glass. Consists of

[0011]

Embodiments and specific examples of the present invention

[ Embodiment in which excitation light is incident from the end face of a glass sheet ] FIG.
FIG. 1A is a schematic cross-sectional view showing a mode in which excitation light according to the present invention is incident from an end surface of a glass sheet. FIG. 1A shows a mode in which a lamp 5 is used as an excitation light source, and FIG. The mode of more irradiation was shown.

The sheet glass 1 includes alkali aluminosilicate glass, alkali silicate glass, borosilicate glass,
Alkaline lime silicate glass containing soda lime silica glass and the like are available. As an example, soda lime glass sheet 1 made by a float method is used.

On the front and back surfaces of the glass sheet 1, a film (photocatalytic film) 3 composed of a photocatalytic substance or mainly composed of a photocatalytic substance is formed. In addition, since the sheet glass 1 is a glass whose front and back surfaces are parallel, the photocatalyst films 3 disposed on the front and back surfaces are parallel, and the end face 4 of the sheet glass (the cut surface of the sheet glass continuously produced in a strip shape) is the front surface. Naturally, it is perpendicular to the back surface (cut at right angles to the front and back surfaces).

In FIG. 1A, a light source 5 is arranged, for example, above the end face 4 of the glass sheet, and is covered with a lamp shade 6 to prevent the excitation light 2 from leaking out.

In FIG. 1B, the excitation light from the light source is
The light is introduced into an optical fiber via a condensing means such as a convex lens or a concave mirror (not shown), and the light is irradiated from a light irradiating section 5 'via the optical fiber.
This prevents leakage of the excitation light 2. In this case,
There is an advantage that an ultraviolet light source disposed at another place such as sunlight can be used, and a light divergence (irradiation) space can be designed to be more compact than when the lamp 5 of FIG. 1A is used.

The excitation light 2 (hereinafter simply referred to as light) refers to light that excites and activates the photocatalytic substance constituting the photocatalyst film. In the present invention, the excitation light 2 is used to activate an anatase that is optimal as the photocatalytic substance. Effective wavelength range 320-390nm
It refers to light containing a degree of ultraviolet light.

Light 2 diverging from the light source 5 or radiating from the light irradiating section 5 ′ is incident on the end face 4 of the glass sheet and propagates through the glass sheet 1, as shown in FIG. The reflection is repeated, and the photocatalytic film 3 is excited by the light 2 to exhibit a hydrophilic action.

Meanwhile, the light 2 is absorbed by the glass and attenuated to activate the photocatalytic film 3. In order to allow the light 2 to spread over the entire surface of the photocatalytic film 3, the initial light intensity is designed in consideration of the size of the glass sheet 1 and the area of the photocatalytic film 3 provided with a film. This is an appropriate design item.

For example, in a sheet glass with a photocatalytic film having a size as shown in Example 1 to be described later, as shown in FIG.
Light is obliquely incident on the end face 4 of the glass sheet from the light irradiating section 5 ′ (light 2 is not emitted directly to the end face 4 ′), and the light intensity on the end face 4 of the glass sheet becomes 20 mW / cm ² . The light 2 is inspected for leakage at the opposing end face 4 'so that the light 2 reaches the opposing end face 4' at a vertical length of 455 mm of the sheet glass only by repeated reflection between the two photocatalytic films 3 only. As a result, light of about 3 mW / cm ² was detected, and even though light energy was absorbed in the glass and absorbed and attenuated by the photocatalytic film, surplus light energy was still detected, and the entire photocatalytic film was found to be uniform. It can be said that it is activated without.

FIG. 2 shows the incidence (refraction) of light on a sheet glass,
FIG. 3 is an enlarged partial cross-sectional view showing a reflection path, and with reference to this drawing, a condition under which incident light 2 on an end face 4 of the glass sheet is totally reflected in the glass sheet 1 will be described. The symbols in the figure are as follows. αi: Incident angle at air / sheet glass interface αt: Refraction angle at air / sheet glass interface βi: Incident angle at sheet glass / photocatalytic film interface βt: Refraction angle at sheet glass / photocatalytic film interface θi: photocatalytic film / Incident angle at interface of air θt: refraction angle at photocatalyst film / air interface no: refractive index of air (1.00) n1: refractive index of plate glass (1.53) n2: refractive index of photocatalytic film (anatase) (2.15) Note 1: Refractive index is the excitation wavelength range of photocatalytic film (320nm)
390 nm). Note 2: The refractive index of sheet glass is around 1.53, though it depends on the composition of soda-lime glass.

<About the incident angle for total reflection at the photocatalyst film / air space interface> Light 2 is made incident from the end face 4 of the glass sheet to excite the photocatalyst film 3 without leaking the light 2 out of the front and back surfaces of the glass sheet 1. In order to do so, it is necessary to totally reflect the light 2 at the interface between the photocatalytic film 3 and the air a. The incident angle for preventing the light 2 from leaking from the photocatalytic film 3 can be obtained from Snell's equation.

The interfaces of the air / photocatalyst film and the photocatalyst film / plate glass (plate glass / photocatalyst film) are all parallel, and it is assumed that these surfaces are orthogonal to the end surfaces of the plate glass on which light enters.

The incident angle θi at the photocatalyst film / air interface is
It is represented by the following [Equation 1]. θi = sin ⁻¹ [(n0 / n2) sin θt] (Because θt for total reflection at the interface is 90 °) = sin ⁻¹ (n0 / n2) (1) That is, the photocatalytic film / Incident angle at the air interface θi ≧ sin ^-1
If (n0 / n2), it is totally reflected and does not leak into the air space.

<Regarding the Angle of Incidence at the Glass / Photocatalyst Film Interface for Obtaining the θi> The angle of incidence βi at the glass / photocatalyst film interface is obtained from the following equation. βi = sin ⁻¹ [(n2 / n1) sin βt] (Because βt = θi, substitute [Equation 1]) = sin ⁻¹ [(n2 / n1) sin θi] = sin ⁻¹ [(n2 / n1) (n0 / n2)] = sin ^-1 (n0 / n1) [Equation 2] = 41.8 That is, regardless of the refractive index of the photocatalyst, the incident angle βi at the glass / photocatalyst film interface. If ≧ 41.8 °, total reflection occurs at the photocatalytic film / air space interface.

<Regarding the incident angle of light on the end face of the glass sheet for obtaining the above βi> The incident angle αi at the interface between the air space and the glass sheet is obtained by the following equation. αi = sin ⁻¹ [(n1 / n0) sin αt] (αt = 90.0−βi) = sin ⁻¹ [(n1 / n0) cos βi] (formula 3) = 41.8 °, sinαi ≦ 1.14, and at any angle of incidence αi, total reflection will occur and no light will leak out of the photocatalytic film. Therefore, the person using the mirror can be prevented from being exposed to ultraviolet rays.

Actually, the surface of the film is not completely parallel to the plate glass of the substrate. A haze value is an obvious physical property value that indicates deviation from parallelism, and the haze value is expressed as an intensity ratio between scattered light of light that is perpendicularly incident on the film surface and total transmitted light.

When the photocatalytic film is completely parallel to the glass sheet, the haze value of the film measured by the perpendicular incident light is 0.5 under the condition that total reflection occurs at the photocatalytic film / air interface.
%, There is light obliquely incident at an angle smaller than the critical angle at the photocatalytic film / air interface, and the light leaks out of the system, that is, into the air. The amount is at most 0.5%,
It is presumed that the influence on the human body is negligible at such a light amount. Actually, as shown in an example described later, a haze value of 0.5%
If it is below, it cannot be detected even by the ultraviolet ray detector, and it can be considered that there is no influence on the human body.

As the photocatalyst substance constituting the photocatalyst film,
It is known that anatase exhibits the best catalytic activity, but one or more of silica, alumina, tin oxide, zirconium oxide and the like are mixed to improve the strength of the film and the adhesion to the substrate glass. be able to.

Alternatively, between the plate glass and the photocatalytic film,
By interposing a film having a refractive index lower than those of the photocatalytic films and adjusting the film thickness, reflection from the photocatalytic film (a double image) can be reduced by light interference.

In order to form a film of anatase or a composite metal oxide containing anatase in the photocatalyst film, an oxide sol solution containing a metal alkoxide such as titanium or a metal acetylacetonate such as titanium as a starting material is used. A sol-gel method in which the metal oxide is applied to a heated substrate and fired by heating, or a CVD method in which a similar metal compound vapor is sprayed on the heated substrate to form an oxide film by thermal decomposition or the like, and the metal oxide is applied to the substrate by physical vapor deposition means. The PVD method or the like for vapor deposition is suitable, and in each case, the haze value can be made 0.5% or less.

In the above description, the suppression of the leakage of light from the surface of the glass sheet has been described. However, the end face 4 'opposite to the end face (reference numeral 4 in FIG. 1) of the glass sheet on which the light is incident, or the side end face of the glass sheet. Light leakage is not a major problem as long as a person is facing the glazing. In order to suppress leakage from each of the ends, a film made of a reflective substance (various metals such as stainless steel and aluminum) or an absorbent substance (ceria or titania) may be coated on each end. Good. As a preferred example, a coating film for forming a photocatalytic substance may be applied to a portion of the plate glass except for a portion to which light is incident by a dipping method, and the coating may be cured to form a film. Further, if the side and lower sides of the sheet glass are covered with a frame such as a sash, the above-mentioned coating treatment is not necessary.

Separately, if the opposing end face 4 'is coated with a reflective material as shown by reference numeral 7 (shown by a broken line) in FIG.
The light 2 to be leaked is reflected into the system, which is advantageous because surplus light can be effectively used again for the activity of the photocatalytic film. Alternatively, although not shown, light is added to the end face 4 of the sheet glass, and the opposite end face is added. It is also possible to arbitrarily design such that the light enters from 4 ′ and the activation of the photocatalyst is accelerated.

[ Implementation of Injecting Excitation Light from Edge of Sheet Glass]
Example 1 <Example 1> An anatase type photocatalytic film having a film thickness of 153 ± 20 nm was coated on a surface of a sheet glass having a size of 363 mm x 455 mm by a sol-gel film forming method.

Titanium isopropoxide was used as a starting material, dissolved in an isopropyl alcohol solvent, and hydrolyzed to obtain a titania sol solution. A plate glass whose upper and lower end surfaces were covered with a mask film was immersed in this solution, and then gradually dissolved. Pull up and coat both sides, dry this,
By heating and baking at about 500 ° C., an anatase type photocatalytic film is formed. The haze value of this glass was 0.3% as determined by a haze meter.

As shown in FIG. 1A, the mask film on the upper surface of the plate glass 1 having a length of 363 mm and a width of 5 mm was peeled off, a lamp shade was provided so as to cover the end surface, and a high-pressure mercury lamp was provided therein. A high-pressure mercury lamp was set at a position where the light intensity at the end face became 20 mW / cm ² . The emission spectrum of the high-pressure mercury lamp is a bright line spectrum, and the relative intensity at a wavelength of 305 nm is 75%, 95% at 357 nm, and 67% at 395 nm.

Incidentally, when the high-pressure mercury lamp was incident on the end face of the glass plate provided with the photocatalytic film and the amount of light leaking from both photocatalytic films was measured using a photomultiplier made by Otsuka Electric Co., Ltd. (MCPD-1100 type), no detection was possible. .

Separately, as shown in FIG. 1B, light is obliquely incident on the upper end face 4 of the sheet glass (to prevent the light 2 from being directly emitted to the opposite end face 4 ') from the light irradiating section 5'. The arrangement is designed so that the light intensity at the end face 4 becomes 20 mW / cm ² , and the light 2 reaches the opposing (lower) end face 4 ′ in the vertical length of the glass sheet of 455 mm only by repeated reflection between the two photocatalytic films 3. Then, when the leakage of the light 2 at the opposite end face 4 ′ where the mask film was peeled was inspected, light of about 3 mW / cm ² was detected, the light energy was absorbed in the glass, and also absorbed by the photocatalytic film, Even if it attenuated, the surplus light energy was still detected, indicating that the entire photocatalyst film was activated uniformly.

As Example 1, both the plate glass with the photocatalytic film provided with the light source lamp 5 as shown in FIG. 1A and the plate glass as the base plate not coated with the photocatalytic film as Comparative Example 1 were subjected to saturated steam of about 43 ° C. After contacting for about 3 minutes, about 40 ° C
And then left at room temperature for about 1 hour, and then allowed to stand at room temperature for 1 hour. The fog test was performed on both sides of the plate glass up to 10 cycles, with one cycle until the first saturated steam contact was started again. Then, the occurrence of fogging during contact with saturated steam for about 3 minutes was visually evaluated. During the test, the plate glass of Example 1 always received light from a high-pressure mercury lamp from the end face.

As a result, as shown in Table 2, Comparative Example 1
No fogging occurred on both sides of the sheet glass of Example 1, but no fogging was observed on both sides of the sheet glass of Example 1 for 10 cycles.

[Table 2] Sample judgment 1 2 3 4 5 6 7 8 9 10 Example 1 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Comparative Example 1 ○ ○ × × × × × × × × (Note) ○: No fogging is observed. X: Clouding was observed.

Example 2 A solution obtained by adding octylene glycol to titanium tetraisopropoxide was poured into a stainless steel sealed container (evaporator) heated to about 200 ° C. by a metering pump. Separately, a dry nitrogen gas was passed through the container, and further mixed with dry air at about 200 ° C. at the outlet side to prepare a normal pressure CVD gas.

Example 1 The same sheet glass was conveyed into a heating furnace by a transfer conveyer, heated to a maximum temperature of about 620 ° C., and placed on the upper surface of the sheet glass immediately after being unloaded from the heating furnace by the transfer conveyer. The prepared gas was sprayed from a CVD nozzle by an apparatus to form an anatase type photocatalytic film. Further, the same operation was repeated with the non-film-forming surface of the plate glass facing upward, and a photocatalyst film was similarly formed on the surface to produce a plate glass with a double-sided photocatalytic film.

The thickness of the photocatalyst film on both surfaces of the glass is 120 ±
The glass had a haze value of 0.5%.

A high-pressure mercury lamp covered with a lamp shade was set in the same manner as in Example 1, and the amount of light leaking from the photocatalytic films on both surfaces of the plate glass was measured. As a result, no light could be detected. Stearic acid was applied to one photocatalytic film of this plate glass so that the haze value was about 3% as measured by a haze meter, and the end face was irradiated with ultraviolet rays for about 20 minutes by the high-pressure mercury lamp, and the haze value was measured again. As a result, the haze value was reduced to 1% or less.

When a stearic acid was applied to one surface of the same plate glass as in Comparative Example 1 without the photocatalytic film, and the haze value was measured after the same time, the haze value of 3% at the time of application changed completely after the elapse. There was no.

Example 3 The same plate glass as in Example 1 was used, and the same as in Example 1, except that titanium isopropoxide and silicon tetraethoxide (titania: silica = 70 in terms of oxide weight) were used as starting materials. : 30), dissolved in isopropyl alcohol solvent, and hydrolyzed to obtain a titania / silica sol solution. After immersing the plate glass in this solution, gradually pulling it up to form a film on both sides, drying it and drying at 500 ° C By heating and baking to a degree, an anatase / silica mixed photocatalyst film was formed. The haze value of this glass was 0.3% as determined by a haze meter.

A high-pressure mercury lamp covered with a lamp shade was set in the same manner as in Example 1, and the amount of light leaking from the photocatalytic film on both sides of the plate glass was measured. As a result, no light could be detected.

In the same manner as in Example 2, stearic acid was applied to the photocatalytic film of the plate glass so that the haze value was about 3%, and the end face was irradiated with ultraviolet rays for about 20 minutes by the high-pressure mercury lamp, and the haze value was measured again. As a result, the haze value was reduced to about 1%.

In addition, it was found that the silica was mixed in the photocatalyst film, so that the film was less likely to be peeled off than in the case of only anatase even in an abrasion test using an abrasion wheel.

[ Excitation light is applied from the periphery of the front (back) surface of the glass sheet.
Embodiment 3 incident is a schematic cross-sectional view of the excitation light showing the form that enters from the periphery of the plate glass plate glass surface or back surface in the present invention, FIG. 3A using a lamp 5 as the light source, the light from the prism 8 FIG. 3B shows a state where light is incident on the oblique section 1 a ′ of the periphery of the sheet glass from the light irradiation section 5 ′ shown in the previous embodiment, and FIG.
A mode in which light is incident on a ′ via a light introduction hologram is shown.

As the glass sheet 1, a glass sheet similar to the above embodiment is employed. Further, as in the previous embodiment, a film (photocatalytic film) 3 made of a photocatalytic substance or mainly composed of a photocatalytic substance is formed on the front and back surfaces of the glass sheet 1.

In this embodiment, the light source 5 is the sheet glass 1
The excitation light (hereinafter referred to as light) 2 composed of ultraviolet light mainly having a wavelength of 320 nm to 390 nm, which is disposed on the front side (or the rear side) of the portion 1a where the photocatalytic film is not applied, is covered by the lamp shade 6, Avoid leakage outside.

The light enters from the peripheral edge 1a of the front side of the sheet glass,
The light 2 propagating in the sheet glass 1 repeatedly enters and reflects between the two photocatalyst films 3 as shown in the drawing, and during this time, the light irradiating the photocatalyst film 3 excites the photocatalyst film 3 to exhibit a hydrophilic action. Meanwhile, the light 2 is absorbed by the glass and the photocatalytic film 3
Decay to activate. In order to allow the light 2 to spread over the entire surface of the photocatalytic film 3, the initial light intensity is designed in consideration of the size of the glass sheet 1 and the area of the photocatalytic film 3 provided with a film. It is a design matter as appropriate,
This is the same as that shown in the previous embodiment and Example 1 relating thereto.

FIG. 4 shows the incidence (refraction) of light on the glass sheet,
FIG. 3 is an enlarged partial cross-sectional view showing a reflection path, and a condition in which incident light 2 to a surface side peripheral edge portion 1a of the glass sheet is totally reflected in the glass sheet 1 will be described with reference to FIG. The symbols in the figure are as follows. γi: Angle of incidence at the air / sheet glass front (back) surface interface γt: Refraction angle at the air / sheet glass front (back) surface interface (the following symbols correspond to the symbols shown in the previous embodiment) βi: sheet glass / Incident angle at the photocatalytic film interface βt: refraction angle at the plate glass / photocatalytic film interface θi: incident angle at the photocatalytic film / air interface θt: refraction angle at the photocatalytic film / air interface n0: refraction of air Index (1.00) n1: Refractive index of plate glass (1.53) n2: Refractive index of photocatalytic film (anatase) (2.15) Note 1: Refractive index is excitation wavelength region of photocatalytic film (320 nm)
390 nm). Note 2: The refractive index of sheet glass is around 1.53, though it depends on the composition of soda-lime glass.

<Incident Angle of Total Reflection at Photocatalyst Film / Air Space Interface> Surface 1a near the edge of sheet glass
Light 2 is incident from the front and back of the sheet glass 1.
In order to excite the photocatalytic film 3 without leaking out, it is necessary to totally reflect the light 2 at the interface between the photocatalytic film 3 and the air a. The incident angle for preventing the light 2 from leaking from the photocatalytic film 3 is
It can be obtained from Snell's equation as in the previous embodiment.

The interface between the air / photocatalyst film and the photocatalyst film / plate glass (plate glass / photocatalyst film) is all parallel as described above. The incident angle θi at the photocatalytic film / air interface is represented by the following [Equation 4]. θi = sin ⁻¹ [(n0 / n2) sin θt] (Because θt for total reflection at the interface is 90 °) = sin ⁻¹ (n0 / n2) −−−− [Equation 4] That is, the photocatalytic film / Incident angle at the air interface θi ≧ sin ^-1
If (n0 / n2), it is totally reflected and does not leak into the air space.

<About the incident angle at the glass / photocatalytic film interface for obtaining the above θi> The incident angle βi at the glass / photocatalytic film interface can be obtained from the following equation. βi = sin ⁻¹ [(n2 / n1) sin βt] (Because βt = θi, substitute [Equation 4]) = sin ⁻¹ [(n2 / n1) sin θi] = sin ⁻¹ [(n2 / n1) (n0 / n2)] = sin ^-1 (n0 / n1) [Equation 5] = 41.8 That is, regardless of the refractive index of the photocatalyst, the incident angle βi at the interface between the plate glass and the photocatalytic film. If ≧ 41.8 °, total reflection occurs at the photocatalyst film / air space interface, and from the preconditions, βi = γt (the refraction angle at the air / sheet glass interface; (Represented by the line XX ′ in each figure), so that if the refraction angle γt ≧ 41.8 °, the light is totally reflected.

<Regarding the incident angle of light on the surface near the edge of the plate glass for obtaining the above βi> The incident angle γi at the air space / sheet glass interface is obtained by the following equation. γi = sin ⁻¹ [(n1 / n0) sin γt] (γt = βi) = sin ⁻¹ [(n1 / n0) sin βi] (Equation 6) By the way, βi ≧ 41.8 °, the incident angle γi> 90 °
And light cannot be incident as it is.

In the embodiment shown in FIG. 3A, a prism 8 is additionally provided at the light incident point 1a, so that βi = γt ≧ 41.8 ° can be easily achieved, thereby causing total reflection. Does not leak from the photocatalytic film. Therefore, the surrounding persons can be prevented from being exposed to the ultraviolet rays. (The above angle is the angle when the refractive index of the glass sheet is set to 1.53 as described above. Needless to say, there are also minor fluctuations).

The angle φ of the prism 8 and the refractive index can be appropriately designed in consideration of the position of the light source 1. Separately, as shown in FIG. 1B, if the light incident portion of the plate glass 1 is a surface 1a ′ which is inclined so as to be thinner toward the end surface of the plate glass, and the light is incident, the apparent surface X-X ′ of the plate glass is obtained. The refraction angle γt ≧ 4 with respect to the line
Since the angle can be set to 1.8 °, light does not leak from the photocatalytic film as described above.

The light source unit 5 'can be designed to collect sunlight, or light from an ultraviolet light source arranged at another location, transmit the light to the light source unit 5' by an optical fiber, and make the light incident. .

Further, in FIG. 1C, similarly to the above, the light incident portion of the plate glass 1 is made to be an inclined surface 1a ', and the known reflected light is diffracted at this portion so as to have a desired angle of refraction 41.8 ° or more. If a sheet made of a light-introducing hologram to be adhered is attached, a desired refraction angle can be obtained.

As in the previous embodiment, the surface of the film is not completely parallel to the plate glass of the substrate, and haze occurs. However, the haze value is at most 0.5%. It cannot be detected even with a container, and it may be considered that there is no effect on the human body.

As in the previous embodiment, it is known that anatase exhibits the best catalytic activity as a photocatalytic substance constituting the photocatalytic film, but the strength of the film and the adhesion to the substrate glass are improved. For silica, alumina,
One or more of tin oxide, zirconium oxide, and the like can be mixed, or a film having a lower refractive index than the photocatalytic film is interposed between the sheet glass and the photocatalytic film, and the film thickness is adjusted. The reflection from the photocatalytic film (which produces a double image) can be reduced by light interference.

Further, in forming a film of anatase or a composite metal oxide containing anatase in the photocatalytic film, a sol-gel method using a metal alkoxide such as titanium as a starting material, or a similar CVD method using a metal compound vapor. ,
As in the previous embodiment, the PVD method or the like (in each case, the haze value is 0.5% or less) in which the metal oxide is deposited on the substrate by physical vapor deposition means is preferable.

In addition, in order to prevent light from leaking from the end face 4 'of the sheet glass or the side end face of the sheet glass, each end is coated with a film made of a reflective substance or an absorbing substance, or a sash or the like. The design can be made in the same manner as in the previous embodiment, such as covering with a frame.

[ Excitation light is applied from the periphery of the front (back) surface of the glass sheet.
Example of incidence ] <Example 4> Same as Example 1, 363 mm x 455 mm x 5 mm
On both sides of the sheet glass 1 having a size of (thickness), the film thickness 1 is left except for one peripheral portion 1a (width 10 mm) of one surface on which light is to be incident.
An anatase type photocatalytic film 3 of 53 ± 20 nm was coated by a sol-gel film forming method.

In the same manner as in Example 1, an isopropyl alcohol solution of titanium isopropoxide was hydrolyzed to obtain a titania sol solution.
a is immersed in a sheet glass coated with a mask film, and then gradually pulled up to form a double-sided film, which is dried and heated and fired at about 500 ° C. to form an anatase-type photocatalytic film. The haze value of this glass was 0.3% as determined by a haze meter, which was the same as in Example 1.

A prism 8 having the same refractive index as that of the plate glass is attached to one peripheral edge portion 1a of the plate glass having a length of 363 mm and a width of 10 mm from which the mask film has been peeled off, and a lamp shade is disposed so as to cover the plate. A high-pressure mercury lamp was disposed inside the lamp, and the high-pressure mercury lamp was set at a position where the light intensity on the light incident surface of the prism 8 became 20 mW / cm ² .

Incidentally, light is incident from the high pressure mercury lamp,
When the amount of light leaking from the photocatalytic film on both sides of the plate glass was measured using a photomulti (MCPD-1100) manufactured by Otsuka Electric Co., it was not detected.

In the same manner as in Example 1, the plate glass with the photocatalyst film was brought into contact with saturated steam at about 43 ° C. for about 3 minutes,
乾燥 C for about 10 minutes in a dryer at room temperature for 1 hour,
A clouding test was performed up to 10 cycles, with one cycle until the first contact with saturated steam was started again. In each cycle, the state of clouding during contact with saturated steam for about 3 minutes was visually evaluated. During this test, the light from the high-pressure mercury lamp was always incident on the plate glass via the prism 8. As a result, in the sheet glass of this example, no fogging was observed for 10 cycles, and the same effect as in Example 1 was observed.

Example 5 A solution obtained by adding octylene glycol to titanium tetraisopropoxide was poured into a stainless steel sealed container (evaporator) heated to about 200 ° C. by a metering pump. Separately, a dry nitrogen gas was passed through the container, and further mixed with dry air at about 200 ° C. at the outlet side to prepare a normal pressure CVD gas.

Example 4 A plate glass similar to that of Example 4 was placed on a peripheral portion 1a to be irradiated with light on the upper surface thereof, and then was conveyed into a heating furnace by a transfer conveyor.
Immediately after the temperature was raised to about 620 ° C. and immediately after being carried out of the heating furnace by the transfer conveyer, the prepared gas was sprayed from a CVD nozzle onto the upper surface of the sheet glass using a CVD apparatus prepared in advance to form an anatase type photocatalytic film. Further, a photocatalytic film was formed on the entire surface of the plate glass by the same operation with the non-film-forming surface facing up. The thickness of this glass was 120 ± 25 nm, and the haze value of the glass was 0.5%.

This is carried out in the same manner as in the fourth embodiment, in the
A high-pressure mercury lamp covered with a lamp shade was set.

In the same manner as in Example 4, the plate glass with the photocatalyst film was brought into contact with saturated steam at about 43 ° C. for about 3 minutes,
乾燥 C for about 10 minutes in a dryer at room temperature for 1 hour,
A clouding test was performed up to 10 cycles, with one cycle until the first contact with saturated steam was started again. In each cycle, the state of clouding during contact with saturated steam for about 3 minutes was visually evaluated. During this test, the light from the high-pressure mercury lamp was always incident on the plate glass via the prism 8. As a result, in the plate glass of this example, no fogging was observed for 10 cycles, and the same effect as in Example 4 was recognized.

[0076]

According to the present invention, it is possible to activate the photocatalyst film by irradiating the photocatalyst film on both sides of the plate glass without exposing the human body to ultraviolet rays, and to exhibit a satisfactory anti-fog function.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a plate glass with a photocatalytic film according to one embodiment, and FIG.
FIG. 1B shows a mode in which light is incident from a light irradiation unit.

FIG. 2 is an enlarged partial sectional view corresponding to FIG.

3A and 3B are cross-sectional views of a sheet glass with a photocatalytic film according to another embodiment, in which FIG. 3A shows a mode in which light is incident from a light source lamp via a prism 8, and FIG. FIG. 3C shows a mode in which light is incident on the oblique section through a light introduction hologram.
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FIG. 4 is an enlarged partial sectional view of FIG. 3;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sheet glass 1a peripheral edge of one surface of sheet glass 1a 'inclined surface 2 light (excitation ultraviolet light) 3 photocatalytic film 4 one end face of sheet glass 5 light source (lamp) 5' light irradiation section 8 prism 8 'sheet made of light introduction hologram

Claims (6)

[Claims] 1. A photocatalyst film is formed on the front and back surfaces of a sheet glass, an excitation light source for the photocatalyst is arranged on an end face of the sheet glass so that the excitation light does not leak from the end face, and the excitation light enters the sheet glass from the end face of the sheet glass. Characterized in that the glass sheet is provided with a photocatalytic film, and is repeatedly reflected by the inside of the sheet glass and propagated in the sheet glass. 2. A photocatalyst film is formed on the front and back surfaces of a sheet glass, and an excitation light source for the photocatalyst is applied to an appropriate portion of one peripheral edge of the sheet glass where the photocatalyst film is not formed. Arranged so as not to leak, the excitation light is incident on the plate glass from the location, and the refraction angle γt of the excitation light on the one surface XX ′ is set so that the excitation light is repeatedly totally reflected in the plate glass and propagates in the plate glass. A sheet glass with a photocatalytic film, characterized by setting: 3. The glass plate with a photocatalytic film according to claim 2, wherein the excitation light incidence condition is adjusted so that the refraction angle γt of the incident excitation light with respect to one surface XX ′ is 41.8 ° or more. . 4. The glass surface at the excitation light incident point is connected to one surface X
The plate glass with a photocatalytic film according to claim 2 or 3, wherein the surface is inclined with respect to -X '. 5. A light-introducing hologram or a prism is additionally provided at an excitation light incident point, and the excitation light is incident through the light-introducing hologram or the prism. The plate glass with a photocatalytic film according to the above. 6. The glass sheet with a photocatalytic film according to claim 1, wherein a transparent oxide film having a lower refractive index than the photocatalytic film is interposed between the photocatalytic film and the glass sheet.