JP2016112561A - Photocatalytic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalytic member that expresses self-purifying action by light irradiation with an illumination device having a low dose of ultraviolet, and has high durability.SOLUTION: A photocatalytic member 1 comprises a base material 2, a tungsten oxide layer 3 provided on the base material 2, and a titanium oxide layer 4 provided on the tungsten oxide layer 3. Preferably a platinum layer 5 is provided between the tungsten oxide layer 3 and the titanium oxide layer 4, partially on the oxidize tungsten layer 3.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a photocatalytic member capable of self-purifying dirt adhered to surfaces of outer walls, windows, mirrors, lenses, displays, and the like.

  A technique for self-cleaning dirt adhering to the surface of a photocatalytic member by the photoexcitation action of the photocatalyst is known (for example, Patent Document 1). The surface of the photocatalytic member described in Patent Document 1 is coated with a semiconductor photocatalyst such as anatase type titanium oxide (hereinafter simply referred to as “photocatalyst”). The photocatalytic member is self-purified by irradiating the photocatalyst with ultraviolet rays.

WO96 / 29375

  Since the above phenomenon is a phenomenon induced by photoexcitation of a semiconductor, in order to develop the above phenomenon, a photon (photon) having energy higher than the band gap of the photocatalyst is required. When titanium oxide is used as a photocatalyst, the photon energy necessary for exhibiting a self-purifying action is required to be 3.0 eV or more corresponding to the band gap of titanium oxide. That is, when converted into the wavelength of light, ultraviolet rays of 400 nm or less are required. The intensity of ultraviolet rays emitted from a lighting device such as a fluorescent lamp or an incandescent lamp is very small. For this reason, when titanium oxide is used as a photocatalyst, the self-purifying action is not sufficiently exhibited.

  As a countermeasure, it is possible to use tungsten oxide having a low photon energy, that is, a self-purifying action that can be expressed by visible light of 400 nm or more when converted to the wavelength of light.

  However, tungsten oxide has low durability and has problems such as elution when it is exposed to the outside air and peeling off from the substrate.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a highly durable photocatalytic member that exhibits a self-cleaning action even with light irradiation by an illumination device with a small amount of ultraviolet rays. It is to be.

  That is, the photocatalytic member of the present invention has a base material, a tungsten oxide layer provided on the base material, and a titanium oxide layer provided on the tungsten oxide layer.

  As a result of intensive studies to solve the above problems, the present inventors have used tungsten oxide and titanium oxide as photocatalysts, and formed a titanium oxide layer on the tungsten oxide layer, thereby reducing the amount of ultraviolet light. It has been found that self-purifying action is manifested by light irradiation by the apparatus. Furthermore, with this configuration, the tungsten oxide layer is not directly exposed to the outside air, so durability is increased.

  Moreover, it is preferable that the photocatalytic member of the present invention further has a platinum layer formed on a part of the titanium oxide layer.

  The present inventors have also found that the self-cleaning action is further improved by providing a platinum layer on a part of the titanium oxide layer.

  In addition, the photocatalytic member of the present invention further includes a platinum layer provided between the tungsten oxide layer and the titanium oxide layer, and the platinum layer is provided in a part on the tungsten oxide layer. It is preferable to be made.

  By providing a platinum layer between the tungsten oxide layer and the titanium oxide layer, the self-cleaning action is further improved. In the case of this configuration, since the platinum layer is not directly exposed to the outside air, the platinum layer is hardly peeled off.

  In the photocatalytic member of the present invention, the platinum layer is preferably a platinum fine particle dispersed layer in which platinum fine particles are dispersed.

  If the platinum layer is a platinum fine particle dispersed layer in which platinum fine particles are dispersed, the portion where the platinum layer is provided and the portion where the platinum layer is not provided can be evenly arranged on the titanium oxide layer or the tungsten layer. The purification action is further improved.

  According to the present invention described above, it is possible to provide a photocatalytic member that exhibits a self-cleaning action and has high durability even in light irradiation by a lighting device with a small amount of ultraviolet rays.

It is a typical sectional view of a photocatalytic member concerning a first embodiment of the present invention. It is a typical sectional view of a photocatalytic member concerning a second embodiment of the present invention. It is a figure for demonstrating the position of the platinum layer 5 in the top view of the photocatalytic member which concerns on 2nd embodiment of this invention. It is a typical sectional view of a photocatalytic member concerning a third embodiment of the present invention. It is a figure which shows the time passage of the density | concentration of acetaldehyde under visible light irradiation. It is a figure which shows the time passage of the density | concentration of acetaldehyde under visible light irradiation.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described. However, the present invention is not limited to the following embodiments, and is based on ordinary knowledge of a person skilled in the art without departing from the gist of the present invention. It should be understood that modifications and improvements as appropriate to the following embodiments also fall within the scope of the present invention.

(First embodiment)
First, a first embodiment of the present invention will be described. As shown in FIG. 1, the photocatalytic member 1 of the present invention includes a base material 2, a tungsten oxide layer 3, and a titanium oxide layer 4.

  As the base material 2, a transparent material such as glass or transparent plastic, or a material such as metal, ceramic, plastic, wood, stone, or concrete can be used. The shape of the base material 2 can be a plate shape, a spherical shape, a lens shape, or the like depending on the application.

  The tungsten oxide layer 3 is formed on the substrate 2. Since tungsten oxide has a smaller band gap than titanium oxide, the tungsten oxide layer 3 exhibits a self-cleaning action with visible light of 400 nm or more when converted to the wavelength of light. The tungsten oxide layer 3 may contain other metal oxides.

  The titanium oxide layer 4 is formed on the tungsten oxide layer 3. The titanium oxide layer 4 has higher durability than the tungsten oxide layer 3. As described above, in order to express the self-cleaning action, titanium oxide requires ultraviolet light having a wavelength of 400 nm or less in terms of the wavelength of light. However, although the reason is unknown, it was found that when formed on the tungsten oxide layer 3, the titanium oxide layer 4 expresses a self-cleaning action by visible light of 400 nm or more when converted to the wavelength of light.

  The thickness of the tungsten oxide layer 3 is preferably 200 to 1500 nm. If the thickness of the tungsten oxide layer 3 is less than 200 nm, the self-cleaning action may not be exhibited in light irradiation by a lighting device with a small amount of ultraviolet rays, and if it is greater than 1500 nm, film formation time and cost are required. The thickness of the tungsten oxide layer 3 is more preferably 450 to 1100 nm.

  The thickness of the titanium oxide layer 4 is preferably 50 to 200 nm. If the thickness of the titanium oxide layer 4 is less than 50 nm, the durability may be lowered. If the thickness is more than 200 nm, the self-cleaning action may not be exhibited in light irradiation by an illumination device with a small amount of ultraviolet rays. The thickness of the titanium oxide layer 4 is more preferably 90 to 160 nm.

  The thickness ratio of the tungsten oxide layer 3 to the titanium oxide layer 4 (titanium oxide layer / tungsten oxide layer) is preferably 0.03 to 0.2. When the thickness ratio between the tungsten oxide layer 3 and the titanium oxide layer 4 is less than 0.03, the durability may be lowered. There may be no purification effect. The ratio of the thickness of the tungsten oxide layer 3 to the titanium oxide layer 4 (titanium oxide layer / tungsten oxide layer) is more preferably 0.05 to 0.15.

  The photocatalytic member 1 is produced by forming the titanium oxide layer 4 after forming the tungsten oxide layer 3 on the substrate 2. The tungsten oxide layer 3 and the titanium oxide layer 4 can be formed by sputtering, vacuum deposition, CVD, or the like.

(Second embodiment)
Next, a second embodiment of the present invention will be described. In addition, description of the part which is common in 1st embodiment is abbreviate | omitted. As shown in FIG. 2, the photocatalytic member 1 of the present invention includes a base material 2, a tungsten oxide layer 3, a titanium oxide layer 4, and a platinum layer 5.

  The platinum layer 5 is formed on the titanium oxide layer 4. Since the platinum layer 5 stores electrons, the multi-electron reduction reaction of oxygen is promoted, and at the same time, the oxidation reaction is promoted. Therefore, the self-purifying action is strongly expressed. The platinum layer 5 is not formed so as to cover the entire titanium oxide layer 4 but is provided in a part. That is, as shown in the plan view of the photocatalytic member 1 in FIG. 3, the platinum layer 5 is formed so that the titanium oxide layer 4 is exposed. The formation area ratio of the platinum layer 5 is preferably 30 to 80% with respect to the formation area of the titanium oxide layer 4. If the formation area ratio of the platinum layer 5 is less than 30%, the above effect is hardly obtained, and if it is more than 80%, the titanium oxide layer 4 is almost covered with the platinum layer 5 and the decomposition activity is lowered. The formation area ratio of the platinum layer 5 is more preferably 35 to 70%.

  The platinum layer 5 is preferably a layer in which platinum fine particles are dispersed, that is, a so-called platinum fine particle dispersed layer. Since the platinum fine particles are easily dispersed uniformly on the titanium oxide layer 4 and the portion where the platinum layer 5 is provided and the portion where the platinum layer 5 is not provided can be arranged uniformly, the self-cleaning action is further improved.

  The platinum layer 5 can be formed by sputtering, vacuum deposition, CVD, or the like after the titanium oxide layer 4 is formed. The formation area ratio of the platinum layer 5 can be adjusted by adjusting the film formation time of the platinum layer 5. For example, the film formation time of the platinum layer 5 is preferably 5 to 15 seconds.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In addition, description of the part which is common in 1st embodiment and 2nd embodiment is abbreviate | omitted. As shown in FIG. 4, the photocatalytic member 1 of the present invention includes a base material 2, a tungsten oxide layer 3, a titanium oxide layer 4, and a platinum layer 5.

  The platinum layer 5 is formed between the tungsten oxide layer 3 and the titanium oxide layer 4. The platinum layer 5 is not formed entirely on the tungsten oxide layer 3 but is formed in part.

  The formation area ratio of the platinum layer 5 on the tungsten oxide layer 3 is preferably 40 to 75%. If the formation area ratio of the platinum layer 5 is less than 40%, the effect of the self-cleaning action is hardly obtained, and if it is more than 75%, the visible light response effect of tungsten oxide is lowered. The formation area ratio of the platinum layer 5 is more preferably 45 to 65%.

  The platinum layer 5 is preferably a layer in which platinum fine particles are dispersed, that is, a so-called platinum fine particle dispersed layer. Since the platinum fine particles are easily dispersed uniformly on the tungsten oxide layer 3 and the portion where the platinum layer 5 is provided and the portion where the platinum layer 5 is not provided can be arranged uniformly, the self-cleaning action is further improved.

  The photocatalytic member 1 is manufactured by forming the platinum layer 5 after forming the tungsten oxide layer 3 on the substrate 2 and finally forming the titanium oxide layer 4. The tungsten oxide layer 3, the platinum layer 5, and the titanium oxide layer 4 can be formed by a sputtering method, a vacuum evaporation method, a CVD method, or the like. For example, the film formation time of the platinum layer 5 is preferably 5 to 15 seconds.

  In the present embodiment, since the platinum layer 5 is configured not to be exposed to the outside air, the platinum layer 5 is difficult to peel from the photocatalytic member 1. The formation area ratio of the platinum layer 5 can be adjusted by adjusting the film formation time.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

  The measurement sample will be described below.

Glass having dimensions of 50 mm × 50 mm × 1 mm was prepared as a substrate, and tungsten oxide, titanium oxide and platinum were formed on one surface of the substrate by a sputtering method.
Sample No. No. 1 was obtained by forming a tungsten oxide layer on a substrate and forming a titanium oxide layer thereon. The thickness ratio of the tungsten oxide layer to the titanium oxide layer (titanium oxide thickness / tungsten oxide thickness) is 0.1 (titanium oxide layer = 100 nm, tungsten oxide layer = 1000 nm). Note that the tungsten oxide layer is completely covered with the titanium oxide layer.
Sample No. No. 2 was obtained by forming a tungsten oxide layer on a substrate and forming a titanium oxide layer thereon. The ratio of the thickness of the tungsten oxide layer to the titanium oxide layer (titanium oxide thickness / tungsten oxide thickness) is 0.15 (titanium oxide layer = 150 nm, tungsten oxide layer = 1000 nm). Note that the tungsten oxide layer is completely covered with the titanium oxide layer.
Sample No. 3 was obtained by forming a tungsten oxide layer on the substrate. The ratio of the thickness of the tungsten oxide layer to the titanium oxide layer (titanium oxide thickness / tungsten oxide thickness) is 0 (titanium oxide layer = 0 nm, tungsten oxide layer = 500 nm). The base material is completely covered with the tungsten oxide layer.
Sample No. No. 4 was obtained by forming a tungsten oxide layer on the substrate. The thickness ratio of the tungsten oxide layer to the titanium oxide layer (titanium oxide thickness / tungsten oxide thickness) is 0 (titanium oxide layer = 0 nm, tungsten oxide layer = 1000 nm). The base material is completely covered with the tungsten oxide layer.

Sample No. No. 5 was obtained by forming a tungsten oxide layer on a substrate and forming a titanium oxide layer thereon. The ratio of the thickness of the tungsten oxide layer to the titanium oxide layer (titanium oxide thickness / tungsten oxide thickness) is 1 (titanium oxide layer = 100 nm, tungsten oxide layer = 100 nm). Note that the tungsten oxide layer is completely covered with the titanium oxide layer.
Sample No. No. 6 was obtained by forming a tungsten oxide layer on the substrate, forming a platinum layer on a part of the tungsten oxide layer, and forming a titanium oxide layer on the tungsten oxide layer and the platinum layer. The ratio of the thickness of the tungsten oxide layer to the titanium oxide layer (titanium oxide thickness / tungsten oxide thickness) is 1 (titanium oxide layer = 100 nm, tungsten oxide layer = 100 nm). The sputtering time for the platinum layer is 7 seconds. The formation area ratio of platinum on the tungsten oxide layer is 70%.
Sample No. No. 7 was obtained by forming a tungsten oxide layer on the substrate, forming a platinum layer on a part of the tungsten oxide layer, and forming a titanium oxide layer on the tungsten oxide layer and the platinum layer. The thickness ratio of the tungsten oxide layer to the titanium oxide layer (titanium oxide thickness / tungsten oxide thickness) is 1 (titanium oxide layer = 100 nm, tungsten oxide layer = 100 nm), and between the titanium oxide layer and the tungsten oxide layer. A platinum layer was formed. The sputtering time for the platinum layer is 10 seconds. The formation area ratio of platinum on the tungsten oxide layer is 70%.
Sample No. No. 8 was obtained by forming a tungsten oxide layer on a substrate, forming a titanium oxide layer thereon, and forming a platinum layer on a portion of the titanium oxide.
The thickness ratio of the tungsten oxide layer to the titanium oxide layer (titanium oxide thickness / tungsten oxide thickness) was 1 (titanium oxide layer = 100 nm, tungsten oxide layer = 100 nm), and a platinum layer was formed on the titanium oxide layer. . The sputtering time for the platinum layer is 7 seconds. The formation area ratio of the titanium oxide layer is 75%.

Each of the measurement samples was placed in a transparent sealed container, and the container was filled with acetaldehyde-containing gas. The concentration of acetaldehyde in the gas is 60 ppm. After filling the sealed container with gas, it is sealed so that outside air does not flow into the container, and then a xenon lamp (center wavelength: 450 nm) with a filter (AGC Techno Glass Co., Ltd., UV absorption filter V-40) attached to the sealed container. , Watt density: 1.0 mW / cm ² ). During irradiation with light, 1 ml of gas in the container was taken out so that outside air would not flow into the container every minute, and the concentration of acetaldehyde was measured by gas chromatography. The lower the concentration of acetaldehyde, the more self-purifying action is expressed.

5 and 6 show the time course of the concentration of acetaldehyde under the visible light irradiation of the measurement sample. Sample No. 1 and sample no. No. 2 is a sample No. 2 in which the tungsten oxide layer is directly irradiated with light although the outermost surface is a titanium oxide layer. 3 and Sample No. As high as 4, acetaldehyde resolution was shown.
In addition, the self-cleaning action was improved by providing a platinum layer partly on the titanium oxide layer or partially between the tungsten oxide layer and the titanium oxide layer.

1 Photocatalytic member, 2 base material, 3 tungsten oxide layer, 4 titanium oxide layer, 5 platinum layer

Claims (4)

A substrate;
A tungsten oxide layer provided on the substrate;
A titanium oxide layer provided on the tungsten oxide layer;
A photocatalytic member characterized by comprising:   The photocatalytic member according to claim 1, further comprising a platinum layer provided on a part of the titanium oxide layer.   Furthermore, it has a platinum layer provided between the said tungsten oxide layer and the said titanium oxide layer, The said platinum layer is provided in a part on the said tungsten oxide layer, It is characterized by the above-mentioned. 1. The photocatalytic member according to 1.   4. The photocatalytic member according to claim 2, wherein the platinum layer is a platinum fine particle dispersed layer in which platinum fine particles are dispersed.