WO2004101146A1

WO2004101146A1 - Titanium oxide thin film exhibiting high photocatalytic activity under weak ultraviolet ray

Info

Publication number: WO2004101146A1
Application number: PCT/JP2004/002395
Authority: WO
Inventors: Masakazu Anpo; Takashi Kamegawa; Satoru Dohshi; Masaya Matsuoka
Original assignee: Murakami Corporation
Priority date: 2003-05-16
Filing date: 2004-02-27
Publication date: 2004-11-25
Also published as: JP2004339021A

Abstract

A titanium oxide thin film capable of exhibiting such a high photocatalytic activity that under irradiation with weak ultraviolet rays such as those of 1.0 μw/cm2 light intensity, the thin film independently realizes a contact angle with water of 5° or less (especially substantially 0°). The titanium oxide thin film characterized by exhibiting such a high photocatalytic activity that under irradiation with ultraviolet rays of 1.0 μw/cm2 or less light intensity, the thin film independently (titanium oxide thin film layer (2) independently) realizes a contact angle with water of 5° or less (especially substantially 0°) can be obtained by, for example, controlling film forming conditions and crystal grain diameter.

Description

Description Titanium oxide thin film with high photocatalytic activity under weak UV light

The present invention provides a titanium oxide thin film exhibiting a high photocatalytic activity having a water contact angle of substantially 0 ° under irradiation of weak ultraviolet light having a light amount of 1.0 iw / cm ² or less, a method of forming the same, and the like. About. Background art

Titanium oxide photocatalyst material has anti-staining properties, antibacterial properties, deodorizing properties, etc., and is a material for which applied technology is expected. In addition, the titanium oxide thin film has high transparency, exhibits high photocatalytic activity when irradiated with ultraviolet light, and exhibits high hydrophilic properties such that the contact angle with water is substantially 0 °.

However, in order to exhibit such a high hydrophilic property that the contact angle of water becomes substantially 0 °, an ultraviolet intensity of at least 10 wZcm ² or more is necessary. The environment in which ultraviolet light can be irradiated is limited, and there is a demand for the development of a titanium oxide photocatalyst material that can exhibit a photocatalytic function even with visible light or weak ultraviolet light included in, for example, fluorescent light.

Non-Patent Document 1 (Kazuhito Hashimoto like, Ad v. M atter. 2 00 0, 1 2, N o. 24, pi 9 2 3.) , the composite membrane of the c- W0 ₃ and T i 0 ₂ It has been reported that a highly hydrophilic state in which the contact angle of water is substantially 0 ° can be achieved under irradiation with a faint ultraviolet light of a light intensity of 1.0 / zwZ cm ² .

However, the use of the composite film complicates the formation of the photocatalyst layer and has the problem that the material is expensive. Also, water under irradiation with light intensity 1. 0 wZcm ² that weak ultraviolet light contact angle substantially 0 ° what can be done by achieving a high degree of hydrophilicity to be the c-W0 ₃ and T i 0 ₂ Although reported for composite films, it was not reported for titanium oxide thin films alone.

Therefore, an object of the present invention is to provide a titanium oxide thin film having a light intensity of 1.0 / zw / cm ^2. The goal is to achieve a highly hydrophilic state in which the contact angle of water is substantially 0 ° under the irradiation of weak ultraviolet light. Disclosure of the invention

The present inventors have conducted intensive studies and found that the contact angle of water was substantially (measured) 0 ° under irradiation of weak ultraviolet light of 1.0; w Z cm ² with the titanium oxide thin film alone. For the first time, the present inventors succeeded in achieving a high photocatalytic activity state (claim 1). The titanium oxide single film having such characteristics can be produced by controlling the conditions at the time of film formation. For example, RF output: 250 to 350 W, substrate temperature at the time of film formation: room temperature to 600 ° C, deposition rate: 0.37 nm / min-1.47 nm / min (deposition time: 1-9 hours) and deposition pressure: 1-3 Pa It has been found that it can be produced by RF-magnet sputtering under controlled conditions (claim 2). As described above, in the present invention, by controlling the film formation conditions and the like, the contact angle of water is substantially 0 ° under the irradiation of the weak ultraviolet light of 1.0 iwZ cm ^{2 with} the titanium oxide thin film alone. However, by controlling the film formation conditions, the titanium oxide thin film alone can be used under irradiation of ultraviolet light with a light intensity of 1.0 w / cm ² or less by controlling the film formation conditions. Thus, it is possible to achieve a state showing a high photocatalytic activity in which the contact angle of water is 5 ° or less (approximately 0 ° to 5 °) (claim 1). The contact angle of water is preferably 4 ° or less (approximately 0 ° to 4 °), more preferably 3 ° or less (approximately 0 ° to 3 °), and further preferably 2 ° or less (approximately 0 ° to 2 °). It is more preferably 1 ° or less (approximately 0 ° to 1 °), and further preferably substantially 0 ° (measured 0 °). In addition, the inventors have found that a titanium oxide single film having the above characteristics has an unprecedented characteristic of having a crystal particle diameter of 13 to 17 nm (claim 3). As a result of further intensive research, it was found that by forming a titanium oxide thin film on a metal or alloy with a small work function, the photocatalytic activation light of the titanium oxide thin film can be highly improved (the work function of metal and the rate of hydrophilization). (There is a correlation with the constant) (Claim 4).

Furthermore, a titanium oxide thin film (highly active By forming a titanium oxide thin film, it is possible to achieve a highly hydrophilic state in which the contact angle of water becomes substantially 0 ° under irradiation of a weak ultraviolet light of 1. 1.zw/cm ^2. (Claim 5).

Further, by forming a predetermined highly active titanium oxide thin film on a metal or alloy having a small work function, that is, a titanium oxide thin film having the features of claims 1 to 3, a light amount of 1.0 iwZ It has been found that a highly hydrophilic state in which the contact angle of water becomes substantially 0 ° can be stably and surely achieved under irradiation with a faint ultraviolet light of cm ² (claims 6 to 8).

As the metal or alloy having a small work function, for example, aluminum (4.2 ev) or an aluminum alloy is preferable from the viewpoint of enhancing the photocatalytic property of the titanium oxide thin film, and has a work function equal to or less than that of aluminum. It has been found that it is preferable to use a metal that emits electrons in the presence of light (claim 9).

As described above, in the present invention, by forming a predetermined titanium oxide thin film (a highly active titanium oxide thin film) on a metal or an alloy having a small work function, the light amount 1.

0; It is possible to achieve a highly hydrophilic state in which the contact angle of water becomes substantially 0 ° under the irradiation of the weak ultraviolet light of awZc m ² , but of course, for metals with a small work function, etc. By controlling the selection and the conditions for forming the titanium oxide thin film, etc., the amount of light 1.

Under irradiation of ultraviolet light of 0 iwZcm ² or less, a state showing a high photocatalytic activity with a water contact angle of 5 ° or less (approximately 0 ° to 5 °) can be achieved (claims 5 and 6). . The contact angle of water is preferably 4 ° or less (approximately 0 ° to 4 °), more preferably 3 ° or less (approximately 0 ° to 3 °), and further preferably 2 ° or less (approximately 0 ° to 2 °). The angle is more preferably 1 ° or less (approximately 0 ° to 1 °), and further preferably substantially 0 ° (measured 0 °).

The titanium oxide thin film of the present invention preferably has an anatase type titanium oxide content of 70% or more. This makes it possible to obtain a high photocatalytic activity. The titanium oxide thin film of the present invention preferably has a titanium oxide crystal particle diameter of 13 to 17 nm. Make the titanium oxide crystal particle size in the range of 13 to 17 nm. It is considered that this makes it possible to obtain high photocatalytic activity. As used herein, “the titanium oxide crystal particle diameter is in the range of 13 to 17 nm” means, as can be seen from the SEM photograph of the titanium oxide thin film of the present invention described later, 80% or less of the titanium oxide crystal particles. The above (preferably at least 85%, more preferably at least 90%, more preferably at least 95%) is intended to have a particle size within this range. This is not the purpose except for the case where crystal particles are included. In the titanium oxide thin film of the present invention, the titanium oxide preferably has an average crystal particle diameter of 13 to 17 nm, and preferably contains crystal particles having a particle diameter in this range in the above ratio.

In the titanium oxide thin film of the present invention, uniform gaps are formed between crystal grains of the titanium oxide film, and the crystal grains are independent of each other without contacting each other, and the crystal grains are joined together as they grow and further grow. It is preferable that the number of particles considered to be small is small, the surface area (specific surface area) is large, the shape of the crystal particles is an angular rock, and the uniformity of the crystal particle shape is high. It is thought that these characteristics make it possible to obtain high photocatalytic activity.

In the titanium oxide thin film of the present invention, it is preferable to select and control the material of the substrate on which the film is formed and / or the surface roughness of the surface on which the substrate is formed. It is thought that these make it possible to obtain high photocatalytic activity.

The thickness of the titanium oxide layer is not particularly limited and may be appropriately selected depending on conditions such as a rate of hydrophilicity and a property of maintaining darkness (recovery of a contact angle). 0 nm.

According to the present invention, a photocatalytic action can be exerted even under the irradiation of a weak ultraviolet light having a light amount of 1.0 iwZ cm ² or less. Therefore, it has become possible to provide a sample that can exhibit photocatalysis even with a fluorescent lamp or visible light, as compared with a conventional composite material that can exhibit photocatalysis only with a relatively high amount of ultraviolet light.

As described above, in the present invention, it is possible to have a photocatalytic effect under irradiation of ultraviolet light having a light amount of 1.0 wZ cm ² or less. Therefore, in the present invention, by irradiating the surface of the titanium oxide layer, which is a photocatalyst layer, with light, the photocatalyst is excited even under the irradiation of weak light having a light amount of 1.0 O / x wZ cm ² or less, thereby preventing the dyeing. It can exhibit photocatalytic action such as antibacterial property, antibacterial property and deodorizing property. Therefore, the present invention can be effectively applied not only to conventional uses but also to various uses under irradiation of weak light, for example, an outer mirror and an inner mirror for a vehicle, and a mirror for a bathroom. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view showing a sample manufactured in the example.

FIG. 2 is a diagram showing characteristics of a fluorescent lamp (18 W) as a light source used in the example.

FIG. 3 is a diagram illustrating characteristics of the light quantity measuring device used in the example.

FIG. 4 is a diagram showing the results of an RF output dependency test measurement of a sample using a quartz substrate as the substrate.

FIG. 5 is a diagram showing a measurement result of an RF output dependency test of a sample using a quartz substrate as the substrate.

FIG. 6 is a view showing an electron microscope (SEM) photograph of each sample in which a titanium oxide film is formed on a quartz substrate by changing the RF output.

FIG. 7 is a diagram showing a measurement result of a film forming temperature dependence test of a sample using a quartz substrate as a substrate.

FIG. 8 is a view showing an electron microscope (SEM) photograph of each sample in which a titanium oxide film was formed on a quartz substrate by changing the substrate temperature during film formation.

Figure 9 shows for each sample by changing the deposition when the substrate temperature was deposited titanium oxide film on a quartz substrate, a 5 0 0 ^ ultraviolet light irradiation time of cm ^2, the relationship between the contact angle of water FIG.

FIG. 10 is a view showing a measurement result of a film thickness dependency test of a sample using a quartz substrate as a substrate.

FIG. 11 is a view showing an electron microscope (SEM) photograph of each sample in which a titanium oxide film was formed on a quartz substrate by changing the film formation time and the film thickness.

FIG. 12 is a diagram showing a measurement result of a film forming pressure dependency test of a sample using a quartz substrate as the substrate.

FIG. 13 is a view showing an electron microscope (SEM) photograph of each sample in which a titanium oxide film was formed on a quartz substrate by changing the film forming pressure and the film forming time. FIG. 14 is a diagram showing the measurement results of the light amount dependency test of a sample using a quartz substrate as the substrate.

FIG. 15 is a diagram showing the measurement results of the light intensity dependence test of a sample using a quartz substrate as the substrate.

FIG. 16 is a view showing the results of a measurement of a sample using a quartz base material as a base material, which was maintained in place.

FIG. 17 is a diagram showing an ultraviolet-visible light absorption measurement result of a sample using a quartz substrate as the substrate.

FIG. 18 is a diagram showing the results of X-ray diffraction measurement of a sample using a quartz substrate as the substrate.

FIG. 19 is a diagram showing the results of an RF output dependency test measurement of a sample using an A1 plate as a base material.

FIG. 20 is a diagram showing a measurement result of an RF output dependency test of a sample using an A1 plate as a base material.

FIG. 21 is a diagram showing a measurement result of a film forming temperature dependency test of a sample using an A1 plate as a base material.

FIG. 22 is a diagram showing a measurement result of a film thickness dependency test of a sample using an A1 plate as a substrate.

FIG. 23 is a diagram showing a measurement result of a film forming pressure dependency test of a sample using an A1 plate as a base material.

FIG. 24 is a view showing the measurement results of the light amount dependency test of the sample using the A1 plate as the base material.

FIG. 25 is a diagram showing the measurement results of a light amount dependency test of a sample using an A1 plate as a base material.

FIG. 26 is a diagram showing the results of a dark place maintenance test measurement of a sample using the A1 plate as the base material.

2 7, for samples deposited titanium oxide film under the same conditions in A 1 substrate and the QZ substrate, the light quantity 1. 0 cm ² in the irradiation of a ultraviolet light, investigating changes in the contact angle of water It is a figure showing a result. FIG. 28 is a diagram showing the amount of hydrophilic constant of each sample in which a titanium oxide film was formed on the A1 substrate and the QZ substrate under the same conditions.

FIG. 29 is a diagram showing electron microscope (SEM) photographs of each sample in which a titanium oxide film was formed on the A1 substrate and the QZ substrate under the same conditions. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples.

In the following Examples, as shown in FIG. 1, a sample composed of a substrate 1 and a titanium oxide layer 2 was produced.

In the following examples, a fluorescent lamp (18 W) having the characteristics shown in FIG. 2 (vertical axis: intensity, horizontal axis: wavelength (nm)) was used as a light source. As is evident from Fig. 2, the amount of ultraviolet light in this light source is very small and its intensity is extremely low.

The light intensity was measured by mounting UD-36 to UVR-2 manufactured by TOP COM. As shown in Fig. 3 (vertical axis: relative sensitivity, horizontal axis: wavelength (nm)), UD-36 can measure light in the wavelength range of 310 to 400 nm. The amount of light was adjusted by adjusting the distance between the substrate and the light source.

In the following examples, a titanium oxide sintered body was used as an evening get.

[Example 1]

(RF output dependency test)

To investigate RF output dependency in RF magnet sputtering (a) l Pa, 600 ° C, 100 W, 9 hours, (b) l Pa, 600, 200 W, 4 5 hours, (c) l Pa, 600 ° C, 300 W, 3.0 hours, (d) l Pa, 600 ° C, 400 W, 2.25 hours Each sample was prepared by forming a titanium oxide film on a quartz substrate by RF magnet sputtering under film forming conditions. Figures 4 (a) and 4 (b) show the RF output dependence test results of these samples. FIGS. 4 (a) longitudinal axis and the contact angle of water (°), the horizontal axis is 1. 0 μ wZc m ² of UV irradiation time: shows the (unit time) (FIG. 5 to be described later (a), FIG. 7 (a), FIG. 10 (a), and FIG. 12 (a).) Figure 4 (b) shows the rate constant for hydrophilization (see Figure 5 (b) The same applies to FIG. 7 (b), FIG. 10 (b), FIG. 12 (b), and FIG. 14 (b). As shown in Figs. 4 (a) and (b), the sample formed with the RF output of 300 W showed very good photocatalysis. It is also found that a titanium oxide film exhibiting a high photocatalytic activity with a water contact angle of ⁵⁰ or less can be formed by controlling the film forming conditions and the like. It should be noted that when the RF output is increased (for example, 400 W), the titanium oxide formed may be of rutile type, and thus cannot be simply compared.

Next, as shown in Fig. 5 (a) and (b), the RF output was set to 250 W (1 Pa, 600 hours, 4.5 hours), 300 W (l Pa, 600 ° C). The titanium oxide layer was formed on a quartz substrate under each RF output condition of, 3.0 hours) and 350 W (1 Pa, 60 O, 2.75 hours). At W, a low water contact angle and a high hydrophilization rate constant were obtained. Therefore, it can be seen that in the present invention, it is preferable to set the RF output to about 300 W. It is also found that by controlling the film forming conditions and the like, a titanium oxide film exhibiting a high photocatalytic activity with a water contact angle of 5 ° or less can be formed.

l Under the same conditions of Pa, 3 hours and 600, the RF output was changed to (a) 100 W, (b) 200 W, and (c) 300 W, and RF magnet sputtering was performed. Figures 6 (a) to 6 (c) show electron microscope (SEM) photographs (X100K, 5.OK) of each sample in which a titanium oxide film was formed on a quartz substrate. From Fig. 6 (a) to (c), even if the RF output is changed, there is not much difference in the average crystal grain size.

In the 0 W titanium oxide film, uniform gaps are formed between the crystal grains, the crystal grains are independent of each other without contact, the surface area (specific surface area) is large, and the shape of the crystal grains is angular. It can be seen that it is rocky.

In Example 1, the film formation rate was 0.37 nm / min to 1.47 nm

1 n.

[Example 2]

(Deposition test of film deposition temperature)

As shown in Figures 7 (a) and (b), room temperature (RT) (3 hours, 1.0 Pa, 300 W), 200 (3 hours, 1.0 Pa, 300 Pa) W), at 400 (3 hours, 1.0 When the titanium oxide layer was formed on a quartz substrate under the substrate temperature conditions of each of (Pa, 300 W) and 600 ° C (3 hours, 1.0 Pa, 300 W), It can be seen that the higher the film formation temperature, the higher the hydrophilicity tends to be. It is also found that by controlling the film forming conditions and the like, a titanium oxide film exhibiting a high photocatalytic activity with a water contact angle of 5 ° or less can be formed.

In the same manner as above, under the same conditions of lPa, 3B, and 300W, the substrate temperature during film formation was set to (a) room temperature (RT), (b) 200 ° C, and (c) 400 °. C, (d) Electron microscope (SEM) photographs (X100K, 5.K) of each sample in which a titanium oxide film was formed on a quartz substrate by RF magnet sputtering by changing the temperature to 600 ° C. Fig. 8 (a) to (d)

Shown in From Figures 8 (a) to 8 (d), uniform gaps are formed between crystal grains in the titanium oxide film at 200 to 600 ° C, and the crystal grains are independent without contacting each other. This indicates that the surface area (specific surface area) is large, which is preferable, and that the titanium oxide film at 600 ° C. is particularly preferable because the crystal grains are in the form of a rock having an angular shape.

In the same manner as above, under the same conditions of lPa, 3 hours, and 300W, the substrate temperature during film formation was set to (a) room temperature (RT), (b) 200 ° C, and (c) 400 ° C. (D) 600. C and each sample on which a titanium oxide film was formed on a quartz substrate by RF magnet sputtering by means of RF magnet sputtering, was irradiated with 500 / xwZcm ² of ultraviolet light (light source: SHL-10

0 UV), and the result of examining the time until the contact angle of water becomes 5 ° or less is shown in FIG. The vertical axis in FIG. 9 shows the contact angle of water (°), and the horizontal axis shows the irradiation time (unit: minute) of 500 / iwZcm ² ultraviolet light. From FIG. 9, it can be seen that the higher the film formation temperature, the shorter the time required for the water contact angle to become 5 ° or less.

Incidentally, in Example 2, the film formation rate was 0.37 nmZmin to l.47 nmZm

1 n.

[Example 3]

(Thickness dependence test)

As shown in Figures 10 (a) and (b), the film thickness is 200 nm (1.0 Pa, 3 hours, 600 W, 300 W), 400 nm (1.0 Pa, 6 hours, 6001 :, 300 W) A titanium oxide layer was formed on a quartz substrate under various film thickness conditions (deposition time conditions) of 700 nm (1.0 Pa, 9 hours, 600 ° C., 300 W). It can be seen that the higher the film thickness, the higher the hydrophilicity.

Titanium oxide deposited under the condition of 700 nm (1.0 Pa, 9 hours, 600 ° C, 300 W) was irradiated with ultraviolet light with a light intensity of 1.0 tw / cm ² or less. Below, for the first time, it was confirmed that after 72 hours, it exhibited a high degree of hydrophilicity with a water contact angle of substantially 0 °. It is also found that a titanium oxide film exhibiting a high photocatalytic activity with a water contact angle of 5 ° or less can be formed by controlling the film forming conditions and the like. Similarly to the above, under the same conditions of lPa, 3 hours, and 600 ° C, changing the deposition time to (a) 3 hours, (b) 6 hours, (c) 9 hours, and changing the RF An electron microscope (SEM) of each sample in which a titanium oxide film with a thickness of (a) 200 nm, (b) 400 nm, and (c) 700 nm was formed on a quartz substrate by magnet sputtering. ) The photographs (X100K, 5.OK) are shown in Figs. 11 (a) to (c). From Figs. 11 (a) to 11 (c), the titanium oxide film of 400 to 700 nm has a large crystal grain size, and uniform gaps are formed between the crystal grains. It is clear that they are independent from each other, that they have a large surface area (specific surface area), and that the crystal grains are in the form of angular rocks.

In Example 3, the film formation rate was 0.37 nmZmin: 1.47 nmZmin.

[Example 4]

(Deposition dependency test)

As shown in Figs. 12 (a) and (b), the film forming pressure 1 Pa (300 w, 600 hours, 3 hours), 2 Pa (300 w, 600 ° C, When a titanium oxide layer was formed on a quartz substrate under each of the film forming pressure conditions of 3 hours) and 3 Pa (300 w, 600 ° C., 3 hours), water was formed under these conditions. It can be seen that a titanium oxide film exhibiting a high photocatalytic activity with a contact angle of ⁵⁰ or less can be formed.

The film forming pressure and film forming time are (a) l Pa, 3 hours (300 w, 6Ό0), (b) 2 Pa, 6 hours (300 w, 600 ^), (c ) 3 Pa, 9 hours (300 w, 600 ° C) with RF magnet sputtering. Electron microscope (SEM) photographs (X1 to X1) of each sample on which a titanium oxide film of (a) 200 nm, (b) 400 nm, and (c) 700 nm was formed, respectively. 0 0 K, 5. OK) are shown in Figs. 13 (a) to (c). As shown in Figs. 13 (a) to (c), the titanium oxide film of l to 2Pa has a large crystal grain size, and more uniform gaps between the crystal particles than in Figs. 11 (a) to (c). Are formed, the crystal grain shape is highly uniform, and there are few particles that are considered to have joined together with the growth of the crystal grains and to have grown further.

In Example 4, the film formation rate was 0.37 nmZmin to l.47 nm / min.

[Example 5]

(Light intensity dependence)

In order to examine the light intensity dependence of the sample prepared in Example 3, the light intensity (a) 1.

At 0 w / cm ² , (b) 2.0 pi w / cm ² , and (c) 10.0 zw / cm ² , the light quantity dependence of a sample having a titanium oxide layer formed on a quartz substrate was examined. The results are shown in FIGS. 14 (a) and (b). FIG 1 4 (a), it is understood that capable of expressing (b) as shown in, 1. O ^ contact angle of water in weak light quantity of WZcm ² becomes 5 ° or less advanced photocatalytic activity.

The vertical axis in Fig. 14 (a) shows the contact angle of water (°), and the horizontal axis shows the irradiation time (unit: time) of each amount of ultraviolet light.

Under the same conditions of 1.0 Pa, 600 W, 3 000 W, and 3 hours, the amount of light (a) was 1 for each sample in which a titanium oxide film was formed on a quartz substrate by RF magnet sputtering. 0 (iw / cm (b) 1 0.0 w / cm ² , (c) 2 0.0 w / cm ² , (d) 500 twZ cm ² The results are shown in Fig. 15. From Fig. 15, it was found that the irradiation angle of water at 500 cm ² was substantially 0 ° immediately after irradiation with UV light, and 20 wZcm ^{In the case} of UV light irradiation ( ²⁾ , the contact angle of water becomes substantially 0 ° in the time after irradiation, and in the case of UV irradiation of 10 ^ w / cm ² , the contact angle of water becomes substantially 0 in 24 hours after irradiation. °, it turns out.

The vertical axis in FIG. 15 shows the contact angle (°) of water, and the horizontal axis shows the irradiation time (unit: time) of the ultraviolet light of each light amount. [Example 6]

(Maintain darkness)

Under the same conditions of l Pa, 600 W, and 300 W, the film formation time was changed to (a) 3 hours, (b) 6 hours, and (c) 9 hours, and by RF magnet sputtering. A titanium oxide film with a thickness of (a) 200 nm, (b) 400 nm, and (c) 700 nm was formed on a quartz substrate, and a UV light of 1.0 iwZc m ² or less was formed. After elapse of 72 hours under irradiation, the cells were stored in a dark place, and the relationship between the contact angle of water and time was examined. The results are shown in FIG. From Fig. 16 [The vertical axis is the contact angle of water (°), and the horizontal axis is the elapsed time from the end of UV light irradiation (unit: days)], the recovery of the contact angle is slow as the film thickness increases. It turns out that the dark place maintenance is high.

[Example 7]

(Ultraviolet light-visible light absorption measurement)

(a) 1.0 Pa, 3 hours, 600 ° C, 300 W, (b) 1.0 Pa, 6 hours, 600 t, 300 W, (c) 1. A sample was prepared by forming a titanium oxide film on a quartz substrate by RF magnet sputtering under the respective film forming conditions of 0 Pa, 9 hours, 600 ° C., and 300 W. The film thicknesses were (a) 200 nm, (b) 400 nm, and (c) 700 nm, respectively. Figure 17 shows the results of ultraviolet-visible light absorption measurement of these samples. As shown in Fig. 17 (vertical axis: transmittance (a.u.), horizontal axis: wavelength (nm)), since the thickness of these samples is different, the appearance of interference fringes and the position of the absorption edge are also slightly different. However, it can be seen that all of these titanium oxide layers are of an ultraviolet light responsive type (ultraviolet light responsive type).

[Example 8]

(X-ray diffraction)

(a) l Pa, 600 ° C., 300 W, 3 hours, (b) l Pa, 600. A sample was prepared by forming a titanium oxide film on a quartz substrate by RF magnet sputtering under the conditions of C, 400 W, and 2.25 hours. X-ray diffraction (XRD measurement) of these samples was performed. The results are shown in FIG.

From FIG. 18 (vertical axis: strength (cps), horizontal axis: 20 (°)), anatase content (% ₎ and particle size were determined according to the following equations. Anasose content (%) = 100 / [1 + 1.265 (Ir / Ia)]

D [Particle size (A)]

cos θ

(K = 0.9, λ = 1.540 56, β (half width) (red))

As a result, each sample had an anatase content of 70% or more and a particle size of 13 nm to 17 ηm. The crystallinity and orientation of each sample were very good.

In the following examples, samples were produced in the same manner as in the above examples except that the substrate was A1 plate (commercially available aluminum plate; manufactured by Nicola Corporation: 0131461 aluminum plate), and photocatalytic properties were obtained. And examined the relationship.

[Example 9]

(RF output dependency test)

To examine the RF output dependency in RF magnet sputtering, (a) lPa, 600 W, 100 W, 9 hours, (b) lPa, 600 ° C, 200 W, 6 hours, (c) lPa, 600, 300 W, 3 hours, (d) lPa, 600. A sample was prepared by forming a titanium oxide film on an aluminum substrate by RF magnet sputtering under the conditions of C, 400 W, and 2.25 hours. Figures 19 (a) and (b) show the RF output dependence test results of these samples. The vertical axis in Fig. 19 (a) indicates the contact angle of water (°), and the horizontal axis indicates the irradiation time (unit: time) of 1.0 iw / cm ² ultraviolet light (Fig. 20 (a) described later). The same applies to FIG. 23 (a)). FIG. 19 (b) shows the hydrophilization rate constant (the same applies to FIGS. 20 (b) to 23 (b) described later). As shown in Fig. 19 (a) and (b), the sample formed with the RF power of 300 W showed very good photocatalysis. Also, compared to the case of forming on a quartz substrate, the photocatalytically active light of the titanium oxide thin film can be improved to a high degree, and the contact angle of water is substantially reduced under the irradiation of weak UV light with a light intensity of 1.0 / wZ cm ^2. It has been found that a high degree of hydrophilicity of 0 ° can be achieved.

Next, as shown in Figs. 20 (a) and (b), the RF output was set to 250W (lPa, 600 ° C, 4.5 hours), 300W (lPa, 60h). 0, 3.0 hours) and 350 W (lPa, 600 ° C., 2.75 hours) under a RF output condition, a titanium oxide layer was formed on an aluminum substrate. At a RF power of 300 W, a low water contact angle and a high hydrophilization rate constant were obtained. Therefore, in the present invention, the RF output is set to about 300 W is preferable. Also, compared to the case of forming on a quartz substrate, the photocatalytically active light of the titanium oxide thin film can be improved to a high degree, and the contact angle of water is 5 ° under the irradiation of a faint ultraviolet light of 1.0 z ^ wZcm ² . In the following, it has been found that a highly hydrophilic state, particularly at substantially 0 °, can be stably and surely achieved.

In Example 9, the film formation rate was 0.37 nm / min to l.47 nmZmin.

[Example 10]

(Deposition test of film deposition temperature)

As shown in Fig. 21 (a) and (b), room temperature (RT) (3 hours, 1.0 Pa, 300 W), 200 ° C (3 hours, 1.0 Pa, 3 Oxidation at 400 ° C (3 hours, 1.0 Pa, 300 W), 600 ° C (3 hours, 1.0 Pa, 300 W) When a titanium layer was formed on an aluminum substrate, it was found that the higher the film formation temperature, the higher the hydrophilicity. Also, compared to the case of forming on a quartz substrate, the photocatalytically active light of the titanium oxide thin film can be improved to a high degree, and the contact angle of water is 5 ° or less under the weak ultraviolet light of 1.0 / iwZcm ² , In particular, it has been found that a highly hydrophilic state of substantially 0 ° can be stably and surely achieved. At the same time, by controlling the deposition conditions of the titanium oxide thin film, the contact angle of water is 5 ° or less (approximately 0 ° to 5 °) under irradiation of ultraviolet light with a light intensity of 1.OiwZcm ² or less. 4 ° or less (approximately 0 ° to 4 °), 3 ° or less (approximately 0 ° to 3 °), 2 ° or less (approximately 0 ° to 2 °;), 1 ° or less (approximately 0 ° to 1 °), real It has been found that a state showing a high photocatalytic activity of 0 ° (measured 0 °) can be achieved.

In Example 10, the deposition rate was 0.37 nm / min to 1.47 nm / min.

[Example 11]

(Thickness dependence test)

As shown in Fig. 22 (a;) and (b), the film thickness is 200 nm (1. OP a, 3 hours, 600 ° C, 300 W), 400 nm (1. OP a , 6 hours, 600 ° C, 300 W), 700 nm (1 OPa, 9 hours, 600, 300 W) When the layer was formed on an aluminum substrate, It turns out that it shows high hydrophilicity.

Moreover, compared with the case of forming the quartz substrate, a titanium oxide thin film can be improved photocatalytic activity light with high degree of light intensity 1. 0 / iw / cm ² water contact angle of substantially under irradiation of weak ultraviolet light that It has been found that a high degree of hydrophilicity of 0 ° can be achieved stably and reliably. At the same time, by controlling the deposition conditions of the titanium oxide thin film, under irradiation light quantity 1. 0 iwZc m ² or less of ultraviolet light, water contact angle of 5 ° or less (approximately 0 ° ~ 5 °), 4 ° or less (approximately 0 ° to 4 °), 3 ° or less (approximately 0 ° to 3 °), 2 ° or less (approximately 0 ° to 2 °), 1 ° or less (approximately 0 ° to 1 °), substantial It has been found that a state showing a high photocatalytic activity of 0 ° (0 ° in measurement) can be achieved.

In Example 11, the film formation rate was 0.37 nm / min to .47 nm / mi η.

[Example 12]

(Deposition dependency test)

As shown in Fig. 23 (a) and (b), the deposition pressure l Pa (300 W, 600 ° C, 3 hours), 2 Pa (300 W, 600 ° C, When a titanium oxide layer was formed on an aluminum substrate under the pressure conditions of 3 hours) and 3 Pa (300 W, 600 ° C., 3 hours), the oxidation was higher than when a titanium oxide layer was formed on a quartz substrate. The photocatalytic activation light of titanium thin film can be improved to a high degree, and a highly hydrophilic state in which the contact angle of water becomes substantially 0 ° under the irradiation of a faint ultraviolet light of 1.0 wZ cm ² is stably and reliably achieved. Have achieved what they can achieve. At the same time, by controlling the film formation conditions of the titanium oxide thin film, the contact angle of water is 5 ° or less (approximately 0 ° to 5 °) and 4 ° under irradiation of ultraviolet light with a light amount of 1.0 cm ² or less. Less than (approximately 0 ° to 4 °), less than 3 ° (approximately 0 ° to 3 °), less than 2 ° (approximately 0 ° to 2 °), less than 1 ° (approximately 0 ° to: 1 °), substantially It has been found that a state showing a high photocatalytic activity of 0 ° (0 ° on measurement) can be achieved.

In Example 12, the film formation rate was 0.37 nm / min to 1.47 nm / min.

[Example 13]

(Light intensity dependence) The sample prepared in Example 1 1, the amount of light (a) 1 to investigate the quantity of light dependent. 0 nw / m (b) 2. 0 w / cm 2, (c) 1 0. 0 zwZc m 2 Da The light quantity dependence of a sample having a titanium oxide layer formed on a luminium substrate was examined. The results are shown in FIG. As shown in Fig. 24 (the vertical axis is the contact angle of water (°), and the horizontal axis is the irradiation time (unit: time) of ultraviolet light of each light amount), the present invention was achieved even with a weak light amount of 1.0 wZ cm ^2. It can be seen that the sample can exhibit a high degree of photocatalytic activity with a water contact angle of 5 ° or less, particularly substantially 0 °.

Under the same conditions of 1.0 Pa, 600 ° C, 300 W, and 3 hours, for each sample in which a titanium oxide film was formed on an aluminum substrate by RF magnetron sputtering, the light intensity (a ) 1.0 aw / c (b) 10.0 ^ w / cm ² , (c) 20.0 UL W / cm ² , (d) 500 0 ^ w / cm ² The light intensity dependence was investigated. The results are shown in FIG. From Figure 2 5, 500 cm ² of ultraviolet irradiation will immediately contact angle of water substantially 0 ° after irradiation, 2 0 w / cm contact angle of water in the ^second ultraviolet light irradiation 1 8 h after irradiation in Becomes substantially 0 °, and the contact angle of water becomes substantially 0 ° in 24 hours after irradiation under the irradiation of l O ^ wZcm ² , and 1.O / zwZ cm ^{2 under} the irradiation of ultraviolet light It can be seen that the contact angle of water becomes substantially 0 ° 48 hours after irradiation.

In FIG. 25, the vertical axis indicates the contact angle of water (°), and the horizontal axis indicates the irradiation time (unit: time) of the ultraviolet light of each light amount.

[Example 14]

(Maintain darkness)

Under the same conditions of l Pa, 600 ° C, and 300 W, RF magnet sputtering by changing the deposition time to (a) 3 hours, (b) 6 hours, and (c) 9 hours the film thickness on an aluminum substrate, respectively (a) 2 0 0 nm, (b) 40 0 nm, (c) 7 0 0 forming a titanium oxide film of nm, the light quantity 1. 0 cm ² or less of ultraviolet light After 72 hours under irradiation, they were stored in a dark place and examined for the relationship between water contact angle and time. The results are shown in FIG. Fig. 26 [The vertical axis indicates the contact angle of water (°), and the horizontal axis indicates the elapsed time from the end of UV light irradiation (unit: days)]. It turns out that maintainability is high. [Example 15]

(Comparison between A1 board and QZ board)

l P a, 600 ° C, 300 W, 3 hours Under the same conditions, (a) QZ substrate, (b) Al substrate, a sample with a titanium oxide film formed by RF magnet sputtering It was created.

The change of the contact angle of water was examined under irradiation of ultraviolet light with a light amount of 1.0 ^ w / cm ² . Figure 27 shows the results. From Fig. 27 [The vertical axis indicates the contact angle of water (°) and the horizontal axis indicates the irradiation time of ultraviolet light (unit: hours)], the sample with the titanium oxide film formed on the A1 substrate is virtually zero. It can be seen that a high degree of photocatalytic activity can be expressed and the time required for the water contact angle to become 5 ° or less is short (that is, the hydrophilization constant is large). Figure 28 shows the hydration constants of these samples.

Electron microscope (SEM) photographs (X100K, 5.OK) of each of these samples are shown in Figs. 29 (a) and (b). From FIGS. 29 (a) and (b), in the sample in which the titanium oxide film was formed on the A1 substrate, uniform gaps were formed between the crystal particles of the titanium oxide film, and the crystal particles were in contact with each other. It is preferable because they are independent from each other, have a large surface area (specific surface area), and have a crystal particle shape of angular rock. As described above, the present invention has the following excellent effects.

(1) For the first time, a titanium oxide thin film alone achieves a high level of photocatalytic activity in which the contact angle of water becomes substantially 0 ° under irradiation of a faint ultraviolet light of 1.0 ^ wZ cm ^2. Successful (Claim 1). In the present invention, the titanium oxide thin film alone exhibits a high photocatalytic activity with a water contact angle of 5 ° or less (approximately 0 ° to 5 °) under irradiation of ultraviolet light of 1.O ^ iwcm ² or less. The state can be achieved (Claim 1).

The titanium oxide single film having such characteristics can be produced by controlling the conditions at the time of film formation (claim 2), and has an unprecedented characteristic that the crystal particle diameter is 13 to 17 nm. (Claim 3).

(2) By forming a titanium oxide thin film on a metal or alloy having a small work function, the photocatalytically active light of the titanium oxide thin film can be improved to a high degree (claim 4).

Furthermore, a titanium oxide thin film (highly active By forming a titanium oxide thin film, a high level of photocatalytic activity with a contact angle of water of 5 ° or less to substantially 0 ° is achieved under irradiation with a faint UV light of 1.0 β wcm ² It is possible (claim 5).

Further, by forming a titanium oxide thin film having a predetermined high activity on a metal or alloy having a small work function, that is, a titanium oxide thin film having the features of claims 1 to 3, the light amount is 1.0 ^. It is possible to stably and surely achieve a high photocatalytic activity state in which the contact angle of water is 5 ° or less to substantially 0 ° under irradiation of a weak ultraviolet light of wZcm ² (claims 6 to 8).

(3) According to the present invention, it is possible to exert a photocatalytic action even under irradiation of a weak ultraviolet light having a light amount of 1.0 zw cm ² or less. Therefore, it has become possible to provide a sample that can exhibit a photocatalytic action even with a fluorescent lamp or visible light, as compared with a conventional composite material that can exhibit a photocatalytic action only with a relatively high amount of ultraviolet light.

Claims

: Scope of request

1. Ultraviolet light of less than 1.0 wZc m ² with titanium oxide thin film alone

A titanium oxide thin film characterized by exhibiting a high photocatalytic activity under water irradiation with a water contact angle of 5 ° or less.

2. The titanium oxide thin film has an RF output of 250 to 350 W, a substrate temperature at the time of film formation: room temperature to 600 ° C., and a film formation rate of 0.37 nm / min; 2. The film is formed by RF-magnet sputtering while controlling the film forming conditions under a film forming condition of nm / min and a film forming pressure of 1 to 3 Pa. Oxidation thin film.

3. The titanium oxide thin film according to claim 1, wherein a crystal particle diameter of the titanium oxide thin film is 13 to 17 nm.

4. A titanium oxide thin film characterized in that the photocatalytic activity of the titanium oxide thin film is highly improved by forming the titanium oxide thin film on a metal or alloy having a small work function.

5. By forming a predetermined highly active titanium oxide thin film on a metal or alloy with a small work function, the contact angle of water is 5 ° or less under the weak UV light of 1.0 ^ wZ cm ² A titanium oxide thin film characterized by exhibiting high photocatalytic activity.

6. The predetermined highly active titanium oxide thin film according to claim 1, wherein the titanium oxide thin film alone has a water contact angle of 5 ° or less under irradiation of ultraviolet light with a light intensity of 1.0 wZc m ² or less. become and shows a high degree of photocatalytic activity, thereby, stable and reliable light intensity 1. 0 wZcm contact angle of water under irradiation of weak ultraviolet light that ² becomes 5 ° or less high degree of photocatalytic activity 6. The titanium oxide thin film according to claim 5, wherein the titanium oxide thin film shows a state.

7. The titanium oxide thin film has an RF output of 250 to 350 W, a substrate temperature during film formation: room temperature to 600 ° C., and a film formation speed of 0.37 nm / min to 1.47. 7. The film is formed by RF-magnet sputtering while controlling the film forming conditions under a film forming condition of nm / min and a film forming pressure of 1 to 3 Pa. Titanium oxide thin film.

8. The crystal particle diameter of the titanium oxide thin film is 13 to 17 nm The titanium oxide thin film according to claim 6.

9. The titanium oxide thin film according to any one of claims 4 to 8, wherein the metal or alloy having a low work function is aluminum or an alloy thereof.