WO2007108350A1

WO2007108350A1 - Method for testing photocatalyst function and apparatus for use in the test

Info

Publication number: WO2007108350A1
Application number: PCT/JP2007/054838
Authority: WO
Inventors: Bunsho Ohtani; Hirokazu Watanabe; Shinji Kato
Original assignee: National University Corporation Hokkaido University
Priority date: 2006-03-22
Filing date: 2007-03-12
Publication date: 2007-09-27
Also published as: JP2007256010A

Abstract

This invention provides a testing method and a testing apparatus that, in the field where a member utilizing a photocatalyst is actually used, for example, exterior materials for building, a photocatalyst function exerted by a photocatalyst contained in the member can be simply evaluated. The method for an evaluation test of a photocatalyst function comprises the step of providing a light transparent tubular test piece (1) having a hollow part (8), of which the diameter is such that causes a capillary phenomenon, and of which the wall surface is provided with a photocatalyst layer (4), the step of applying light L to the tubular test piece, the step of disposing the tubular test piece in such a state that, in a container (P) containing an aqueous solvent (SW), one opening end (8a) is located in the aqueous solvent and the other opening end (8b) is located in the air, and the step of comparing capillary rise in the hollow part of the tubular test piece before light irradiation with capillary rise in the hollow part of the light-exposed tubular test piece to evaluate the function of the photocatalyst.

Description

Specification

Photocatalytic function test method and instrument used for the test

Technical field

[0001] The present invention relates to a method for simply testing a photocatalytic function and an instrument used for the test. Specifically, the present invention relates to a method and an instrument that can easily test the photocatalytic function at the site of use of a photocatalyst used for building materials.

Background art

[0002] Photocatalysts such as titanium oxide are used in various applications. For example, building materials are being marketed that contain photocatalysts on the surface of building materials (outer wall materials, etc.) that make up the exterior of buildings. Such exterior building materials with a photocatalyst can exhibit a so-called self-cleaning function that always maintains the surface of the exterior material in a clean state by a photocatalytic reaction induced by light irradiation, that is, a decomposition reaction or a hydrophilization reaction. it can.

[0003] By the way, as factors that make the self-cleaning function and other photocatalytic functions work well, (1) the material factor of the essential activity (performance) of the photocatalyst itself used, and (2) the use of the photocatalyst Environmental factors (for example, whether or not the photocatalyst is sufficiently supplied with light having a wavelength that can be absorbed by the photocatalyst). Therefore, in order to correctly evaluate the photocatalytic function in the usage mode of materials, materials, and products (hereinafter collectively referred to as “photocatalyst utilization members”) containing photocatalysts used for desired applications, the above (1) and It is necessary to consider both aspects of (2).

[0004] Among these, for (1), a photocatalyst function evaluation model test can be performed in a laboratory based on various conventionally proposed methods. For example, Non-Patent Document 1 introduces several evaluation methods for the self-cleaning function of a photocatalyst. Patent Documents 1 and 2 evaluate the photocatalytic function by coloring the surface of the photocatalytic film formed on the substrate and measuring the absorbance or reflectance while irradiating the colored surface with ultraviolet rays. A method is described. In Patent Document 3, an organic layer containing a lower alcohol is formed on the surface of a photocatalyst layer formed on a substrate, the organic layer is irradiated with ultraviolet rays, and then the organic layer (after decomposition of the organic layer) is formed. Is a photocatalytic layer) by examining the contact angle of water on the surface A method for evaluating the photocatalytic function is described.

Patent Document 1: Japanese Patent Laid-Open No. 11 83833

Patent Document 2: JP 2000-162129 A

Patent Document 3: Japanese Patent Laid-Open No. 2001-183359

Non-Patent Document 1: Hiroki Tobimatsu, “Evaluation method of self-cleaning of photocatalyst”, Industrial Materials, 200 3 July, p26-27

Disclosure of the invention

Problems to be solved by the invention

However, in order to carry out the evaluation method as described in the above document, it is necessary to perform a complicated process and use a device that is difficult to carry. For this reason, the place where the evaluation can be performed is limited to a specific experimental facility, and it is difficult to evaluate the photocatalytic function of the member at the site where the photocatalyst utilizing member to be evaluated is actually used.

[0006] An object of the present invention is to provide a test method that can easily evaluate a photocatalytic function that can be exhibited by a photocatalyst contained in a member that actually uses a photocatalyst-utilizing member. Another object of the present invention is to provide instruments and kits suitably used for such a test method.

Means for solving the problem

[0007] The method provided by the present invention is a test method for evaluating the photocatalytic function. In the method disclosed here, a tubular specimen that can transmit light, both ends of which constitute an open end connected to the hollow portion, and the diameter of the hollow portion is a size that can cause capillary action, The wall of the hollow part includes a step for preparing a light-transmitting tubular test body on which a photocatalytic layer is formed. Moreover, the step which irradiates light to the prepared tubular test body is included. In addition, the method includes the step of placing the tubular specimen in a container containing an aqueous solvent in a state where the one open end is in the aqueous solvent and the other open end is in the atmosphere. Then, the step of evaluating the function of the photocatalyst by comparing the capillary rise in the hollow portion of the tubular test body before the light irradiation and the capillary rise in the hollow portion of the tubular test body irradiated with the light is included. [0008] In the test method having such a configuration, a container containing a light-transmitting tubular test body having a simple configuration as described above and an appropriate amount of an aqueous solvent (typically water) is used, and the test body exhibits capillary action. Place it in a state where it can occur. And the rise of the capillary water before the light irradiation in the said tubular test body, the rise condition of the capillary water which advances corresponding to the hydrophilization by the photocatalytic action that occurs when the external force light is irradiated to the test body, Thus, the photocatalytic function of the photocatalyst layer on the inner wall surface of the hollow portion of the tubular test body can be evaluated.

According to this method, there is no limitation on the location using the change in capillary phenomenon (typically, the capillary rise value or elevation height) before and after light irradiation in the hollow part of the tubular specimen having the above-described configuration as an index. And the test of a photocatalyst function can be performed simply. Therefore, according to the test method of the present invention, the function of the photocatalyst contained in the predetermined photocatalyst-utilizing member can be easily evaluated at the site where the member is used.

[0009] In a preferred embodiment of the test method disclosed herein, a tubular test body in which a substrate layer containing a substance decomposable by a photocatalytic action is further formed on the surface of the photocatalyst layer is used.

By using a tubular test body in which such a substrate layer is formed on the photocatalyst layer, the degree of decomposition of the substance (typically easily decomposable organic matter) in the substrate layer by the photocatalytic reaction at the time of light irradiation, that is, the sample is provided. The degree of substance decomposition performance of the photocatalyst is increased by increasing the capillary rise value based on the hydrophilicity improvement of the inner wall surface of the hollow part due to the decomposition, or until the capillary rise starts or the progress of the capillary rise is completed. It can be easily tested by measuring the time. Therefore, according to the test method of this embodiment, among the functions exhibited by the photocatalyst included in the predetermined photocatalyst utilizing member, particularly the substance decomposition performance can be easily evaluated at the site where the photocatalyst utilizing member is used.

[0010] Preferably, the substrate layer includes a hydrophobic organic substance as the decomposable substance.

When such a substance is decomposed by photocatalysis, the inner wall surface is hydrophilized, and the rate of increase in capillary water, which is an indicator of organic decomposition, can be more pronounced.

Particularly preferably, the hydrophobic organic substance has a hydrophobic structure portion and a reactive group capable of binding to the photocatalyst layer. For example, the reactive group has a hydroxyl group, a carboxyl group, an amino group, an epoxy group, a thiol group, a halogen, etc., and a long chain alkyl group as a hydrophobic structure portion. And hydrophobic substances (eg, higher fatty acids) having a sulfur group.

The hydrophobic substance having such a structure can be firmly bonded to the photocatalyst layer by a covalent bond or the like due to the presence of the reactive group. For this reason, a highly accurate photocatalytic function (decomposition function) evaluation test can be performed.

In another preferred embodiment, a dye-containing liquid is used as the aqueous solvent, and the degree of coloration of the aqueous solvent in the hollow portion of the tubular test body before the light irradiation and the tubular test body irradiated with the light The method further includes the step of evaluating the function of the photocatalyst by comparing the degree of coloration of the aqueous solvent in the hollow portion.

According to this method, there is no restriction on the location, using the change in the degree of color development (typically transmitted light intensity) of the aqueous solvent before and after the light irradiation in the hollow part of the tubular test body having the above configuration as an index, and without any restrictions. In addition, the photocatalytic function can be tested.

[0012] Further, the present invention provides, as another aspect, an instrument for suitably performing the above-described test method.

That is, the present invention is a test body used for evaluating the photocatalytic function, and has a tubular structure that allows light to pass therethrough, and both ends thereof constitute open end portions connected to the hollow portion, and the hollow portion The diameter is a size that can cause capillary action, and a photocatalyst layer is formed on the wall surface of the hollow portion to provide a tubular test body.

By using a tubular specimen having a strong structure, it is possible to suitably apply the test method of the present invention.

[0013] In a preferred embodiment, a substrate layer containing a substance that can be decomposed by photocatalytic action is further formed on the surface of the photocatalyst layer. Particularly preferably, the substrate layer contains a hydrophobic organic substance as the decomposable substance. As the strong hydrophobic organic substance, a hydrophobic substance (for example, higher fatty acid) having a hydrophobic structure portion and a reactive group capable of binding to the photocatalyst layer is preferable.

By using the tubular test body having such a configuration, it is possible to easily perform an evaluation test at a site where the member is used, particularly regarding the substance decomposition performance among the photocatalytic functions of the predetermined photocatalyst utilizing member.

[0014] Further, the present invention is a kit for use in the photocatalyst function evaluation test disclosed herein, One of the tubular specimens disclosed herein, and a container into which an aqueous solvent is placed so that the specimen can be placed in a state where capillarity can occur (typically in a vertically standing state). A kit for a photocatalyst function evaluation test is provided.

The invention's effect

[0015] According to the present invention, the photocatalytic function can be easily and easily tested without limiting the location by using the change in the capillary phenomenon before and after the light irradiation in the hollow portion of the tubular test body as an index. . Therefore, according to the present invention, the function of the photocatalyst contained in the predetermined photocatalyst utilization member can be easily evaluated at the site where the member is used.

Brief Description of Drawings

FIG. 1 is a diagram schematically illustrating a configuration example of a tubular test body according to the present invention. FIG. 1A is a longitudinal sectional view, FIG. 1B is a transverse sectional view, and FIG. 1C is different from that shown in FIG. FIG. 3 is a cross-sectional view of a tubular test specimen in the form.

FIG. 2 is a diagram schematically illustrating an example of use of the tubular specimen of the present invention.

FIG. 3 is a graph showing the results obtained in the examples of the test method of the present invention, where the horizontal axis represents the light irradiation time (hours) and the vertical axis represents the capillary rise value (mm).

BEST MODE FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, preferred embodiments of the present invention will be described. It should be noted that matters other than matters specifically mentioned in the present specification (for example, the shape of the tubular specimen and the composition of the material constituting the specimen) and matters necessary for the implementation of the present invention (for example, for photocatalyst layer formation) Material preparation and coating methods) can be understood as design matters for those skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common general technical knowledge in the field.

[0018] The photocatalytic function test method disclosed herein includes the above-described tubular test body, and an aqueous solvent (that is, tap water, distilled water, ion-exchanged water, pure water, seawater, or spring water). This can be achieved by using a container for supplying an aqueous solution containing various salts and other hydrophilic solvents. The light source is not particularly limited as long as it can emit light having a wavelength that can excite a photocatalytic substance such as titanium dioxide (a semiconductor substance such as a metal oxide or metal sulfide). For example, the method can be used outdoors (i.e. using the Natural light can be used when it is carried out at the place where the member is originally used. When this method is carried out indoors, various light sources such as general fluorescent lamps, mercury lamps and incandescent lamps can be used.

As shown in FIG. 1, the tubular specimens 1 and 10 used in the photocatalytic function testing method disclosed herein are made of a material that can transmit light that allows the tubular bodies 2 and 12 to excite the photocatalytic substance ( For example, the hollow portions 8 and 18 are formed so that the aqueous solvent introduced from one open end portion 8a can rise by capillary action when the test method of the present invention is performed. The tubular structure is not particularly limited as long as it has a diameter of 5 mm. The lengths of the tubular bodies 2 and 12 are not particularly limited as long as the capillary rise value can be measured, and may be, for example, twice as long as the expected capillary rise value. In this way, even if one of the open ends 8a and 18a of the tubular bodies 2 and 12 is placed in an aqueous solvent, the position of the water surface in the hollow portions 8 and 18 is the same as the open ends 8a and 8 Since it is positioned between the part 8b, the capillary rise value can be measured (see Fig. 2).

The material of the tubular bodies 2 and 12 is preferably glass having a wide transmission wavelength range. For example, quartz glass, high silicate glass (for example, Vycor (registered trademark) glass, which is a product of Corning), and borosilicate glass (for example, Pyrex (registered trademark) glass, which is a product of Corning) It is mentioned as a preferable material.

A tubular test body 1 having a tubular body 2 having a circular cross section as shown in FIGS. 1A and 1B is a typical example of a tubular test body used in the test method of the present invention, but as long as capillary action can occur, For example, it may be a tubular specimen 10 including a plate-shaped tubular body 12 having a flat cross section as shown in FIG. 1C.

As shown in FIG. 1, photocatalyst layers 4 and 14 containing a photocatalyst to be tested are formed on the inner wall surfaces of the hollow portions 8 and 18 of the tubular test bodies 1 and 10 (tubular bodies 2 and 12). The Such photocatalyst layers 4 and 14 can be formed by various conventionally known methods. For example, a suspension (typically an ink-like or best suspension) containing photocatalyst particles made of titanium dioxide or the like and an appropriate binder is prepared, and the suspension (sol) is prepared as a hollow hollow body. Apply to internal wall. Thereafter, by appropriately performing drying and / or heat treatment, the photocatalyst layers 4 and 14 in which the photocatalyst particles are almost uniformly coated on the inner wall surface can be formed. Also light touch Before forming the media layers 4, 14, the inner walls of the hollow portions 8, 18 may be coated with a base material. Examples of the base agent include silicon oxide and aluminum oxide.

The tubular test bodies 1 and 10 in which the photocatalyst layers 4 and 14 are formed on the inner wall surfaces of the hollow portions 8 and 18 as described above can be used in a test method as described in Examples described later.

Further, as shown in FIG. 1, substrate layers 6 and 16 containing substances that can be decomposed by photocatalytic action may be further formed on the surfaces of the photocatalyst layers 4 and 14. With such a configuration, the substance decomposition function of the photocatalyst can be easily evaluated based on the capillary rise.

A solution containing an appropriate degradable substrate material (for example, an organic substance such as alcohol, fatty acid, sugar, peptide, nucleic acid) is introduced into the hollow portions 8 and 18 of the tubular bodies 2 and 12 with the photocatalyst layers 4 and 14, Thereafter, the substrate layers 6 and 16 containing the target substrate substance can be formed on the surface of the photocatalyst layers 4 and 14 by appropriately performing drying, Z or heat treatment.

The substrate substance is particularly preferably a hydrophobic organic substance that binds to and competes with the surfaces of the photocatalyst layers 4 and 14 by a strong bond such as a covalent bond that is preferred by the hydrophobic organic substance. This type of hydrophobic organic substance reacts with an alkyl chain that is a hydrophobic moiety and a fatty acid having a carboxyl group that is a reactive group (preferably a higher fatty acid such as oleic acid) and an alkyl chain that is a hydrophobic moiety. Examples thereof include alcohols such as octanol having a hydroxyl group which is a functional group.

[0022] In the test method of the present invention disclosed herein, the tubular test specimens 1 and 10 obtained as described above are used in a state where capillary action can occur. Typically, as shown in FIG. 2, one open end 8a is in the aqueous solvent SW and the other open end is in a container P containing a suitable aqueous solvent (typically water) SW. Place the tubular specimen 1 with the part 8b in the atmosphere. Typically, as shown in the drawing, the tubular specimen 1 is vertically arranged. At this time, an uneven shape is provided on the bottom of the container P so that the open end 8a immersed in the aqueous solvent SW is not blocked, or the periphery of the open end 8a of the tubular test body 1 is made of the aqueous solvent SW. You may provide the notch part (not shown) which can enter.

In addition, a holder H (for example, an engagement hole corresponding to the outer diameter of the tubular test body 1) that can stably hold the tubular test body 1 for a long time in a state where capillarity can occur (typically in a vertically standing state). A container P equipped with a socket-like holder) is particularly preferred. Such a dedicated container is preferable as a component of the kit according to the present invention. In FIG. 2, as a typical example, the force with which the tubular specimen 1 is set up vertically is acceptable as long as the capillary rise value can be measured in this test method.For example, the tubular specimen 1 is inclined to the side wall surface of the container P. The test may be performed in a standing state.

In the state shown in FIG. 2, the tubular specimen 1 is placed in the container P, and the photocatalytic function evaluation is started. In the test method disclosed herein, the test location is not limited, and a photocatalyst-utilizing member containing the photocatalyst to be tested, such as a tile, a wall panel material, or a paint intended to provide a self-cleaning function by the photocatalyst. It can be carried out using natural light or certain lighting equipment at the site (outdoor or indoor) where the building exterior material is actually used.

In the test method disclosed here, the photocatalytic substance (titanium oxide or the like) constituting the photocatalyst layer 4 is irradiated with light L after passing through the tubular body 2 of the tubular test body 1, and the hydrophilization reaction caused by the photocatalyst generated thereby. Is used. Specifically, as shown in FIG. 2, the force that the aqueous solvent (water in this case) SW enters into the hollow portion 8 of the tubular test body 1 that functions as a capillary and forms the capillary water CW at this time, a predetermined contact angle In addition, the capillary water CW rises to a predetermined position (height) corresponding to the diameter of the hollow portion 8.

When the light L is irradiated and the hydrophilization proceeds, the contact angle Θ between the inner wall surface of the hollow portion 8 and the liquid surface of the capillary water CW is reduced, thereby further pushing up the liquid surface of the capillary water CW. (For example, the position of the dotted line in FIG. 2), the capillary rises. Therefore, in the test method disclosed herein, the capillary rise in the hollow portion 8 of the tubular test body 1 before the light irradiation is compared with the capillary rise in the hollow portion 8 of the tubular test body 1 after the light irradiation. Thus, the function of the photocatalyst constituting the photocatalyst layer 4 can be easily evaluated regardless of the place. Depending on the purpose, this evaluation method may be performed simultaneously with light irradiation, or after performing a light irradiation treatment for a predetermined time (for example, 1 to 24 hours or more) in advance as shown in FIG. The body 1 may be placed in the container P and irradiated with light, or may be performed without light irradiation.

[0024] It should be noted that the capillary rise value h (cm) is defined by the formula: h = 2γX cos Θ / (pXgXR). Where γ is the surface tension of water (70 g 'cm ² ' s_ ² ), Θ is the contact angle, p is the density of water (lg 'cm — ³ ), g is the acceleration of gravity (981 cm' s — ² ), and R is The radius (cm 2) of the hollow part 8 (capillary) of the tubular specimen is shown. Therefore, by measuring the capillary rise value by carrying out this test method, for example, calculating the contact angle before light irradiation and the contact angle after light irradiation for a predetermined time, the photocatalytic function is quantified and evaluated for a predetermined parameter. can do.

In addition, the photocatalytic function can be evaluated by this test method even in a hollow portion having a cross-sectional plate (planar) shape as shown in FIG. 1C as long as capillary action is observed. For example, for the capillary rise value when the contact angle becomes 0 °, the maximum capillary rise value when irradiated with light of sufficient intensity as a comparative control test can be obtained as an index.

Further, as shown in FIG. 1, when the substrate layers 6 and 16 are formed on the surfaces of the photocatalyst layers 4 and 14, similarly, the capillary rise before light irradiation and the capillary rise after light irradiation By comparing the photocatalytic function, the photocatalytic function can be evaluated. In addition, a tubular test body having the same photocatalyst layer and having a substrate layer formed on the surface thereof and a tubular test body having no substrate layer formed thereon are prepared. It is possible to evaluate the substance decomposition performance of the photocatalyst by measuring the time until the capillary rise value reaches the maximum value (plateau) in each tubular specimen with the substrate layer and comparing the measured values.

[0026] In addition, since the tubular specimens 1 and 10 disclosed herein are extremely easy to carry and set for testing, the use of the tubular specimen allows any other photocatalyst function evaluation test to be performed. Can be done at any place.

For example, the hollow portions 8 and 18 are filled with an appropriate reaction substrate and irradiated with light to cause various photocatalytic reactions (for example, oxidation-reduction reactions) in the hollow portions 8 and 18, and the photocatalyst is based on the intensity of the reaction. The function can be tested 'evaluated. For example, a liquid containing pigment such as methylene blue is filled in the hollow portions 8 and 18, and the color development degree (transmission light intensity) of the filling liquid after light irradiation is measured with a colorimeter or the like. The photocatalytic function of the photocatalyst utilizing member can be easily evaluated at a place where it is actually used.

[0027] The tubular test body of the present invention is also applied to a photocatalyst-utilizing member in which a photocatalyst layer is formed by a method that is difficult to apply to the inside of the tubular bodies 2 and 12 such as a sputtering method by creating a calibration curve. 1 and 10 can be used to evaluate the photocatalytic function.

For example, when evaluating the photocatalytic function of a building exterior material having a photocatalyst layer formed by sputtering, the capillary rise value (or the capillary rise value) in the tubular specimen of the present invention is used. A calibration curve may be prepared in advance between a parameter (such as a calculated contact angle of water) and a numerical value (for example, a contact angle of water) indicating the photocatalytic function of the building exterior material. In order to create such a calibration curve, for example, the tubular specimen of the present invention and the building exterior material to be evaluated are irradiated with the same intensity of light for the same time in the laboratory, and the capillary rise in the tubular specimen of the present invention is increased. A value (or a parameter such as a water contact angle calculated from a capillary rise value) and a numerical value (for example, a water contact angle) indicating a photocatalytic function in the building exterior material may be measured. In order to more accurately evaluate the photocatalytic function, (1) the tubular test body of the present invention, and (2) the photocatalyst layer by the same method as the tubular test body (for example, a method by applying a suspension). Prepare the formed flat specimen, and (3) the building exterior material on which the photocatalyst layer to be evaluated was formed, and the calibration curve between (1) and (2) and (2) and (3) A calibration curve between and may be created in advance.

Example

[0028] The present invention will be described in more detail with reference to the following examples. However, the present invention is not intended to be limited to those shown in the examples.

[0029] <Example 1>

A Pyrex (registered trademark) glass tube with a length of 20 mm, an outer diameter of 4 mm, and a hollow diameter of 2 mm was prepared. Further, as the photocatalyst coating liquid (sol), a commercially available ultrafine titanium oxide zone (Product “Showa Denko Co., Ltd. product“ Nanotitania (registered trademark) NTB-01J ”) was used.

That is, the above-mentioned titania sol was diluted and appropriately diluted with water (alcohols) into the hollow portion of the glass tube, and then the excess sol was discharged from the hollow portion. After draining, it was dried in air, then transferred to an electric furnace and baked at about 300 ° C. By the above treatment, a tubular test body in which a photocatalyst layer made of titanium dioxide particles was formed on the inner wall surface of the hollow portion was obtained.

[0030] A test for evaluating the hydrophilization performance of the photocatalyst was conducted using the obtained tubular specimen. That is, one open end of the test body according to this example was placed in a petri dish containing water. Several hours later, the specimen was irradiated with light using a 400 W high-pressure mercury lamp.

0.5 hours, 1 hour, 1.5 hours, 2 hours, 3 hours and 2 before and after light irradiation The capillary rise value at the time when 4 hours had elapsed (that is, the height from the water level of the Petri dish to the liquid level of the capillary water rising the hollow portion of the tubular specimen) was measured. The results are shown in the graph of FIG. 3. At the same time, as Comparative Example 1, the capillary rise value at the time when 24 hours had elapsed without performing light irradiation was measured for a tubular test piece produced by the same treatment. The result is shown in the graph of FIG.

[0031] Example 2>

As a photocatalyst coating liquid (sol), a commercially available titanium oxide zonore (Titanium Chemical Co., Ltd., “Tainok (registered trademark) M-6”) was used, and the same material and method as in Example 1 were used. A tubular test body in which a photocatalyst layer made of titanium dioxide particles was formed on the inner wall surface of the part was obtained.

Then, the same test as in Example 1 was performed, and the capillary rise value was measured before light irradiation and at the time of 0.5 hours, 1 hour, 1.5 hours, 2 hours, 3 hours, and 24 hours after light irradiation. It was. The result is shown in the graph of FIG.

At the same time, as Comparative Example 2, the capillary test value was measured at the time when 24 hours had passed without performing light irradiation on a tubular test specimen produced by the same treatment. The result is shown in the graph of FIG. In addition, as Comparative Example 3 (control test), the same test was performed on the above glass tube in which the photocatalyst layer was not formed, and before light irradiation, and 0.5 hours, 1 hour, 1.5 hours from light irradiation, Capillary elevation was measured after 2 hours, 3 hours and 24 hours. The results are shown in the graph of Fig. 3.

The same material as in Example 1 was used, except that a commercially available ultrafine titanium oxide sol (Showa Denko Co., Ltd. product, Knotitania (registered trademark) NTB_03)) was used as the photocatalyst coating liquid (sol) and treated in the same manner. After forming a photocatalyst layer on the inner wall surface of the hollow part of the glass tube, a substrate layer was further formed on the surface. That is, a substrate layer forming solution was prepared by mixing oleic acid and ethanol so that the oleic acid concentration was 20 to 50 vol%.

This solution was poured into the hollow part of the test specimen and filled at 50 to 90 ° C. for 60 minutes to form a substrate layer having oleic acid power on the surface of the photocatalyst layer. Using the obtained tubular test specimen with a substrate layer, the same test as in Example 1 was performed, and before and after the light irradiation. The capillary rise was measured at the time of 0.5 hour, 1 hour, 1.5 hour, 2 hours, 3 hours and 24 hours. The result is shown in the graph of FIG.

The same material as in Example 1 was used, except that a commercially available titanium oxide sol (Titanium Oxide Zonole “Tainock (registered trademark) A-6” manufactured by Taki Chemical Co., Ltd.) was used as the photocatalyst coating liquid (sol). Then, a photocatalyst layer was formed on the inner wall surface of the hollow part of the glass tube, and then the same treatment as in Example 3 was performed to form a substrate layer on the surface of the photocatalyst layer. The same test as in Example 1 was carried out using the obtained tubular test specimen with the base layer, and before light irradiation and 0.5 hours, 1 hour, 1.5 hours, 2 hours, 3 hours and so on. Capillary elevation was measured after 24 hours. The result is shown in the graph of FIG.

As is apparent from the graph of FIG. 3, according to the test method disclosed herein, the photocatalytic function can be easily evaluated by measuring the capillary rise value. For example, in Examples 1 and 2, the capillary rise value, which was 2 to 8 mm before light irradiation, increased to 15 to 16 mm by light irradiation for 0.5 hours. Such a change was not observed in Comparative Examples 1, 2 and 3. Moreover, the difference in the capillary rise value was recognized by the kind of photocatalyst used. This test method clearly identifies the difference in the degree of the photocatalytic function (especially the hydrophilization performance that affects the self-cleaning ability) that can be exhibited according to the place of use (environmental factors) for multiple types of photocatalysts. Show you get.

[0035] Further, in the test body of Example 4 in which the substrate layer was formed, the capillary rise value, which was 6 to 8 mm before light irradiation, increased to 15 to 16 mm after 24 hours. This indicates that the oleic acid constituting the substrate layer was decomposed by the photocatalyst excited by light irradiation, and the hydrophilicity proceeded (contact angle approached 0 °). On the other hand, in the test sample of Example 3 in which the substrate layer was formed, such a high capillary rise was not recognized after 24 hours from the start of light irradiation. This means that this test method can be used for multiple types of photocatalysts depending on the place of use (environmental factors) (especially the decomposition performance of substances (especially organic substances) that affect the ability to remove pollutants and harmful substances). It is shown that the difference in degree can be clearly discriminated by measuring the time until the conspicuous capillary rise appears.

[0036] This application claims priority based on Japanese Patent Application No. 2006-079386 filed on Mar. 22, 2006. To do. All the contents described in the application specification are incorporated herein by reference. Industrial applicability

The present invention can correctly and simply test and evaluate the photocatalytic function of various photocatalyst-utilizing members (for example, building exterior materials) at actual usage sites. Therefore, the present invention can be used in various industrial fields where photocatalysts are used.

Claims

The scope of the claims

[1] A test method for evaluating the photocatalytic function,

It is a tubular test body that can transmit light, and both ends thereof constitute an open end portion that is continuous with the hollow portion, and the diameter of the hollow portion is a size that can cause capillary action. Providing a light transmissive tubular specimen in which a layer is formed;

Irradiating the tubular specimen with light;

Placing the tubular specimen in a container containing an aqueous solvent in a state where the one open end is in the aqueous solvent and the other open end is in the atmosphere; and before the light irradiation. Comparing the capillary rise in the hollow portion of the tubular specimen with the capillary rise in the hollow portion of the tubular specimen irradiated with light, and evaluating the function of the photocatalyst;

Including methods.

[2] The method according to claim 1, wherein the tubular specimen further has a substrate layer containing a substance decomposable by photocatalytic action on the surface of the photocatalytic layer.

[3] The method according to claim 2, wherein the substrate layer includes a hydrophobic organic substance as the decomposable substance.

[4] The aqueous solvent is a dye-containing liquid,

The function of the photocatalyst is compared by comparing the degree of coloration of the aqueous solvent in the hollow part of the tubular specimen before the light irradiation and the degree of coloration of the aqueous solvent in the hollow part of the tubular specimen that has been irradiated with light. The method of claim 1, further comprising the step of evaluating.

[5] A test specimen used for evaluating the photocatalytic function,

It has a tubular structure that allows light to pass through, and both ends constitute an open end connected to the hollow portion, and the diameter of the hollow portion is a size that can cause capillary action, and a photocatalytic layer is formed on the wall surface of the hollow portion. A tubular specimen.

6. The tubular test body according to claim 5, further comprising a substrate layer containing a substance decomposable by a photocatalytic action on the surface of the photocatalytic layer.

[7] A kit for use in a photocatalytic function evaluation test,

A tubular test body according to claim 5; A container in which an aqueous solvent is placed, wherein the test body can be placed in a state where capillary action can occur;

A photocatalyst function evaluation test kit.