JP2000323757A - Optical catalyst film coating method, optical catalyst film coated thereby, led lamp coated by the method, and display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To coat an optical catalyst film which tightly contacts a translucent base material by preventing tanning phenomenon of the translucent base material under ultraviolet ray. SOLUTION: A cover base material 111 (translucent base material) such as an epoxy resin is irradiated with ultraviolet ray under non-oxygen condition such as in vacuum or inert gas atmosphere. Then an air comprising water content, etc., is allowed to contact the surface of the cover base material 111 which was irradiated with ultraviolet ray, for surface treatment. Then, the cover base material 111 whose surface is treated is coated with an optical catalyst film 112 of titanium oxide, etc., by a normal method. Thus, a cover 110 where the optical catalyst film 112 is thus formed is used to provide an LED lamp 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photocatalytic film coating method, a photocatalytic film coated by the method, and an LE coated with a photocatalytic film by the method.
The present invention relates to a D lamp and a display device using the LED lamp. More specifically, the present invention relates to a method of coating a photocatalytic film on the surface of a light-transmitting substrate made of epoxy resin such as a cover of an LED lamp, and a photocatalytic film coated by the method. The present invention relates to an LED lamp and a display device using the LED lamp.

[0002]

2. Description of the Related Art FIG. 1 shows an L coated with a photocatalytic film.
FIG. 2 is a schematic configuration diagram of an LED display device 200, and FIG. 3 is an LED lamp 1 shown in FIG.
FIG. 7 is a cross-sectional structural view of a cover 110 of FIG. As shown in FIG. 1, the LED lamp 100 includes a light-emitting element 120 disposed inside a light-transmitting cover 110 made of plastic, glass, or the like, and a pair of leads 130 electrically connected to the light-emitting element 120. It is drawn out through the substrate 140. The cover 110 is colored in various colors such as red, blue, and green, and light emitted from the light emitting element 120 passes through the cover 110 and emits light in various colors such as red, blue, and green.

[0003] Such LED lamps 100 have been used in many fields than ever before. For example, as shown in FIG. 2, a large number of LED lamps 100 are arranged to display various road conditions such as traffic congestion information. It is used as various kinds of LED display devices 200 such as information boards and advertising boards for advertisements and publicity.

[0004] These road information boards and advertising boards are constantly being
Exposure to dirty air and weather. As a result, LED
When the surface of the cover 110 of the lamp 100 becomes dirty,
There has been a problem that the luminous intensity of the LED lamp 100 is reduced, and the display of the road information board and the advertising board becomes difficult to see.

Therefore, in recent years, as shown in FIG. 3, an LED lamp 100 in which a photocatalytic film 112 made of a photocatalyst such as titanium oxide is coated on the surface of a cover substrate 111 has been developed. By forming such a photocatalyst film 112, hydrocarbons, soot and the like attached to the surface are decomposed by the photocatalysis, and the surface is kept clean.

Here, the cover substrate 111 is generally made of a water-repellent material such as an acrylic resin. Therefore, in this state, the dispersion of titanium oxide and the solution of silica alkoxide serving as an undercoat agent of the photocatalyst film 112 were repelled, and the photocatalyst film 112 could not be sufficiently coated. For this reason, in general, pretreatment such as polishing of the surface of the cover substrate 111 and plasma irradiation has been performed.

However, in the former method using polishing, the surface of the cover substrate 111 becomes turbid, which causes a decrease in light transmittance. Although the latter method using plasma treatment does not have such a drawback, the plasma irradiation apparatus is expensive and causes a cost increase.
This may adversely affect the lamp unit such as the light emitting element 120 of No. 00.

Further, a coating film can be formed by increasing the viscosity of the dispersion or the solution of the undercoating agent or by increasing the lipophilicity. The adhesiveness of 112 decreases.

Accordingly, the present inventor has made intensive efforts to improve the hydrophilicity of the cover substrate 111 by irradiating the surface of the cover substrate 111 made of epoxy resin with ultraviolet rays.
It has been found that the photocatalytic film 112 is coated with good adhesion.

[0010]

However, although the adhesion of the photocatalyst film 112 was improved by irradiating ultraviolet rays, the resin was deteriorated due to the following reaction, and a yellowing phenomenon occurred. That is, an alkyl radical is generated by ultraviolet rays, and the alkyl radical reacts with surrounding oxygen molecules to generate a peroxide radical or an oxidized radical. As a result, a substance represented by ROOR is generated, and the substance turns yellow. It is thought to cause a phenomenon.

[0011]

The present invention has been made in view of the above problems, and has as its object to prevent the above-mentioned yellowing phenomenon and enable coating of a photocatalytic film having good adhesion to an epoxy resin.

[0013]

According to a first aspect of the present invention, there is provided a method for coating a photocatalyst film on a light-transmitting substrate, wherein the light-transmitting substrate is coated with an ultraviolet ray under oxygen-free conditions. Is irradiated, and then the exposed surface is brought into contact with moisture, and thereafter, a photocatalytic film is coated.

The method for coating a photocatalytic film according to claim 2 shows a more specific method.
In a chamber filled with vacuum or inert gas,
It is characterized by irradiating the light-transmitting substrate with ultraviolet light.

That is, in the present invention, the organic radical generated when the light-transmitting substrate is irradiated with ultraviolet light,
The purpose is to inhibit the reaction with oxygen. This can suppress the generation of peroxide radicals and oxide radicals that cause the yellowing phenomenon.

The light-transmitting substrate used in the present invention is premised on having a light-transmitting property, but in the present invention, a material which causes a yellowing phenomenon upon irradiation with ultraviolet rays, that is, It is particularly effective for a light-transmitting substrate made of plastic. In addition, as long as it is made of a plastic having light transmissivity, its use, shape, and the like are not limited. For example, the present invention can be used not only as a cover base material for various lamps such as an LED lamp described below, but also as a cover base material requiring light transmittance.

In the present invention, the photocatalyst means a catalyst which lowers a reaction potential by light energy and promotes various chemical reactions such as an oxidation reaction and a reduction reaction, and is widely irradiated with light such as ultraviolet rays. Accordingly, the catalyst is not particularly limited as long as it is a catalyst that promotes a decomposition reaction of a substance to be contaminated. However, in the present invention, in order for the light emitted from the light emitting element to be emitted to the outside, a material having good light transmittance is selected. In this regard, titanium oxide is particularly preferable because it can form a transparent photocatalyst film having high light transmittance, but other photocatalysts can be used as long as they have a certain degree of light transmittance. When using titanium oxide,
Anatase-type titanium oxide is preferable because of its high activity.

In the present invention, the term "vacuum" does not mean a complete vacuum, but a vacuum sufficient to achieve the above object is sufficient. Specifically, 1.0.times.10.sup.- ²
A vacuum of about torr is sufficient.

In the present invention, the ultraviolet irradiation may be performed in a chamber replaced with an inert gas such as a nitrogen gas or an argon gas, without having to evacuate the inside of the chamber. Furthermore, it goes without saying that ultraviolet irradiation can be performed after the inside of the chamber is made oxygen-free by, for example, putting an oxygen removing agent into the chamber. In addition, it is only necessary to be able to irradiate ultraviolet rays under oxygen-free conditions. It is also conceivable to arrange a permeable substrate in an inert gas stream, place the substrate in an inert gas atmosphere, and irradiate ultraviolet rays.

Thereafter, the present invention is characterized in that, after irradiation with ultraviolet rays, air containing moisture is fed into the chamber.

The surface of the light-transmitting substrate on which the photocatalyst film is coated by the above method is only irradiated with ultraviolet rays to perform the surface treatment, but the bonding with the photocatalyst film cannot be sufficiently increased. For this reason, when the light-transmissive substrate irradiated with ultraviolet light is brought into contact with moisture, the organic radicals generated on the surface of the substrate react with moisture to generate hydroxyl groups on the surface of the light-transmissive substrate. As a result, the surface of the light-transmitting substrate becomes hydrophilic, and the photocatalyst film can be stably coated without increasing the viscosity of the photocatalyst solution or the like. For this purpose, for example, air containing moisture may be sent into the chamber.

Further, the photocatalyst film coating method according to claim 4 is characterized in that the light-transmitting substrate is an epoxy resin.

As described above, the present invention is effective when an epoxy resin is used as the light-transmitting substrate, and it is possible to make the surface of the epoxy resin hydrophilic without yellowing.

The photocatalyst film according to claim 5 of the present application is a photocatalyst film coated on the surface of a light-transmitting substrate, and the photocatalyst film is formed by any one of the methods according to claims 1 to 4. It is characterized by:

This photocatalytic film is very stable because it is formed on the surface of the light-transmitting substrate having hydrophilicity as described above, and the light-transmitting substrate is yellowed. There is no. For this reason, light transmittance does not decrease,
A light-transmissive substrate of stable quality can be obtained.

According to a sixth aspect of the present invention, there is provided an LED lamp comprising a light-emitting element and a cover having a photocatalytic film formed on a surface of a light-transmitting substrate. It is characterized by being formed by any one of the items 1 to 4.

In the LED lamp, a stable photocatalytic film is formed without yellowing of the light-transmitting substrate. Therefore, it is possible to stably obtain an LED lamp with less contamination by dust and the like.

Further, an LED display device according to a seventh aspect of the present invention is an LED display device having a large number of LED lamps, wherein the LED lamp is the LED lamp according to the sixth aspect.

In the present invention, the LED display means a device in which a large number of LED lamps are arranged in a matrix, and there is no particular limitation on the use or structure of the device, such as a road information board or a billboard. As described above, since the LED display device of the present invention uses the above-described LED lamp, it is possible to provide a maintenance-free LED display device without reducing illuminance over a long period of time.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with respect to an LED lamp and an LED display device. The configurations of the LED lamp and the LED display device according to the present invention are the same as those of the conventional LED lamp and LE shown in FIGS.
Since it is the same as the D display device, its details are omitted.

In the LED lamp 100, a light emitting element 120 is disposed inside a cover 110 having a light transmitting property, and a pair of leads 130 electrically connected to the light emitting element 120 are led out through an element substrate 140. . The cover 110 is provided with a photocatalytic film 1 on a surface of a cover substrate 111 made of a resin such as an epoxy resin having optical transparency.
12 are formed.

As the cover substrate 111, various plastic materials are used, and in particular, epoxy resin is preferably used from the viewpoints of light transmittance, durability, coloring property and the like.
The photocatalyst film 112 is formed of titanium oxide, particularly anatase type titanium oxide, as described above.

Specifically, first, the cover substrate 111 is placed in a chamber for irradiating ultraviolet rays, and the inside of the chamber is evacuated to about 1 × 10 ^-2 torr using a vacuum pump or the like. Alternatively, the inside of the chamber is replaced with an inert gas such as a nitrogen gas.

After that, the surface of the cover substrate 111 is irradiated with ultraviolet rays. The wavelength of the ultraviolet light to be irradiated is not particularly limited, but a wavelength emitted from an ultra-high pressure mercury lamp, a xenon lamp, a metal hide lamp, or the like, specifically, a wavelength of about 250 to 400 nm is preferably used. . Further, the irradiation intensity and irradiation time of the ultraviolet ray may be appropriately set according to the cover substrate (light transmitting substrate) 111 used.
Irradiation may be performed at an intensity of 0 to 100 mW / cm ² for about 10 minutes to 1 hour. When irradiating with ultraviolet rays, it is preferable to operate a vacuum pump or to continuously supply inert gas even during the irradiation in order to maintain the inside of the chamber in a vacuum state or a state filled with an inert gas. Further, it is preferable that the inert gas used does not contain moisture as well as oxygen.

Instead of using a chamber, a light-transmissive substrate may be placed in an inert gas stream, placed under an inert gas atmosphere, and irradiated with ultraviolet light. In this case, the process can be performed without using a chamber, so that there is an effect that cost can be suppressed.

After the irradiation with the ultraviolet rays, the vacuum pump is stopped or the supply of the inert gas is stopped.
After that, air containing moisture is sent into the chamber, and the surface of the cover substrate 111 that has been subjected to the ultraviolet irradiation treatment is brought into contact with the moisture. The amount of water contained in the air is usually
If the amount of water present in the room is sufficient and the amount of water is not sufficient, the room may be humidified before use. Further, in order to prevent the reaction between the remaining organic radicals and oxygen in the air, it is needless to say that water vapor may be mixed with the above inert gas such as nitrogen gas and then sent into the chamber. Thus, the cover substrate 1
11 is subjected to a surface treatment to impart hydrophilicity. Further, it is only necessary that the cover substrate 111 that has been subjected to the ultraviolet treatment can be brought into contact with moisture, and for example, it may be simply taken out from the chamber. In addition, when ultraviolet irradiation is performed in an inert gas stream, by stopping the inert gas, it can be brought into contact with moisture in the air.

Thereafter, a photocatalytic film 112 is coated on the surface of the cover substrate 111 which has been subjected to the surface treatment. The coating method is not particularly limited, and a variety of conventionally used methods are used. In general, coating can be performed by applying a dispersion of a photocatalyst such as titanium oxide or dropping or spraying a silica alkoxide solution. .

As described above, according to the present invention, the cover substrate 1
The photocatalyst film 112 can be firmly formed on the surface of the cover substrate 111 by an extremely simple method without affecting the light transmittance of the photocatalyst 11.

[0039]

Next, the present invention will be described in more detail based on an LED lamp according to an embodiment of the present invention. A photocatalytic film was formed on an LED lamp using a cover substrate made of a colorless and transparent epoxy resin. First, the LED lamp was placed in a chamber made of quartz glass transmitting ultraviolet light, and the pressure was reduced to 1 × 10 ^-2 torr by a vacuum pump.

Next, ultraviolet rays of about 10 to 100 mW / cm ² were irradiated from the outside of the chamber for 30 minutes using an ultra-high pressure mercury lamp. Then open the chamber,
The indoor air was sent into the chamber without any treatment, and was brought into contact with the surface of the cover substrate that had been subjected to the ultraviolet irradiation treatment. The surface of the cover substrate of this LED lamp was not yellowed, and the wavelength of the LED lamp centered at 460 nm was not shifted.

Then, a silica alkoxide solution was dropped or sprayed on the surface of the surface-treated cover substrate to form a photocatalytic film.

Even if the photocatalyst film was hit with the tip of a flathead screwdriver, it was not easily peeled off, and it was confirmed that the photocatalyst film was coated with hardness and high adhesion.

[0043]

The photocatalyst film coating method of the present invention comprises:
After irradiating the light-transmitting substrate with ultraviolet light under oxygen-free conditions, moisture is brought into contact with the irradiation surface, and then a photocatalytic film is coated on the ultraviolet irradiation surface. A photocatalytic film having a strong bonding force with the light-transmitting substrate can be formed without affecting the light-transmitting property of the photocatalyst. Therefore, a stable action of decomposing dust and the like by the photocatalyst film is expected, and an LED lamp and the like with further reduced luminous intensity can be provided.

For example, it is sufficient to irradiate ultraviolet rays in a chamber filled with a vacuum or an inert gas, and then, by feeding air containing moisture into the chamber, a photocatalytic film having a strong bonding force can be easily obtained. .

In particular, the effect is sufficiently exerted on a light-transmitting substrate made of an epoxy resin.

Further, since the photocatalyst film of the present invention is formed by the above method, a photocatalyst film having a high bonding force with the substrate can be obtained by a simple method.

Since the photocatalytic film formed on the LED lamp of the present invention is coated by the above method, the photocatalytic film has a high bonding force with the cover substrate and is a reliable photocatalytic film. In addition, there is little decrease in light transmittance during the manufacturing process. For this reason, this photocatalyst curtain is less likely to be stained by an effective photocatalytic action, and stable illuminance can be obtained for a long period of time.

Therefore, by using these LED lamps, it is possible to provide a reliable LED display device with less illuminance reduction due to dirt and the like and no breakage of the photocatalytic film.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of an LED lamp coated with a photocatalytic film.

FIG. 2 is a schematic configuration diagram of an LED display device.

FIG. 3 is a sectional structural view of a cover of the LED lamp shown in FIG. 1;

[Explanation of symbols]

 Reference Signs List 100 LED lamp coated with photocatalytic film 110 Cover 111 Cover base material 112 Photocatalytic film 120 Light emitting element 130 Lead 140 Element substrate 200 LED display device

Claims (7)

[Claims] 1. A method for coating a light-transmissive substrate with a photocatalytic film, comprising irradiating the light-transmissive substrate with ultraviolet light under oxygen-free conditions, bringing the irradiated surface into contact with moisture, A method for coating a photocatalyst film, comprising coating a film on the surface irradiated with ultraviolet light. 2. The method for coating a photocatalytic film according to claim 1, wherein the light transmitting substrate is irradiated with ultraviolet rays in a chamber filled with a vacuum or an inert gas. 3. The method according to claim 2, wherein air containing moisture is sent into the chamber after the irradiation with the ultraviolet rays.
The photocatalyst film coating method according to the above. 4. The method for coating a photocatalytic film according to claim 1, wherein said light-transmitting substrate is an epoxy resin. 5. A photocatalytic film coated on a surface of a light-transmitting substrate, wherein the photocatalytic film is a photocatalytic film.
A photocatalytic film formed by any one of the methods described above. 6. An LED lamp comprising a light-emitting element and a cover having a photocatalytic film formed on a surface of a light-transmitting substrate, wherein the photocatalytic film is formed by any one of claims 1 to 4. An LED lamp characterized by being performed. 7. An LED display device having a large number of LED lamps, wherein the LED lamp is the LED lamp according to claim 6.