WO2011115237A1

WO2011115237A1 - Photocatalyst filter, and deodorizing device equipped with same

Info

Publication number: WO2011115237A1
Application number: PCT/JP2011/056509
Authority: WO
Inventors: 里恵野中; 信幸谷
Original assignee: 株式会社キャタラー
Priority date: 2010-03-15
Filing date: 2011-03-14
Publication date: 2011-09-22
Also published as: JPWO2011115237A1

Abstract

Disclosed are a photocatalyst filter and a deodorizing device equipped with same. A photocatalyst is provided with a substrate, and a photocatalyst layer in which a photocatalyst component is supported, directly or via a binder layer, on the surface of the substrate. The aforementioned binder layer is formed from: one organic binder layer or one layer formed from a mixture of an organic binder and an inorganic binder; or two or more layers in which an inorganic binder layer or a layer formed from a mixture of an organic binder and an inorganic binder are laminated on the aforementioned organic binder layer. The aforementioned photocatalyst component has a crystallite diameter of 50 to 150nm when measured by means of an X-ray diffraction device, and the amount of photocatalyst components supported on the aforementioned binder layer is 5 to 50g/L or less.

Description

Photocatalytic filter and deodorizing apparatus having the same

The present invention relates to a photocatalytic filter excellent in durability and having a high photocatalytic ability, and a deodorizing apparatus including the same.

A photocatalytic component such as titanium oxide has an action of decomposing various organic substances into substances having a simple structure such as water and carbon dioxide when irradiated with light. Such a photocatalyst carrying a photocatalyst component on the substrate surface is used for a filter or the like of a deodorizer for the purpose of purifying bad odors in the air (Japanese Patent Laid-Open Nos. 2000-21372 and 2001-259003). JP-A-11-188089, JP-A-2001-170497, JP-A-2003-93890, JP-A-2005-169298, JP-A-2004-016832, JP-A-2002-071298) .

The photocatalyst demonstrates its photocatalytic activity using sunlight and light from room lights. By increasing the intensity of light applied to the photocatalyst, the decomposition rate of harmful substances and the like is accelerated. However, conventional photocatalysts do not have sufficient light utilization efficiency. In particular, when the photocatalyst is placed inside a device that does not receive light, improvement of light utilization efficiency becomes a major problem. In this case, a light source is secured by incorporating an ultraviolet lamp or a fluorescent lamp in the apparatus, but the problem has not been solved.

In addition, the photocatalyst component is easily detached from the base material, and it has been difficult to ensure the strength with which the conventional photocatalyst can withstand actual use. There are also photocatalytic filters that ensure high strength by interposing a binder between the base material and the photocatalyst layer, but depending on the shape of the filter, pressure loss increases over time, maintaining purification performance for a long time The problem of being unable to do so remains.

JP 2000-21372 A JP 2001-259003 A JP 11-188089 A JP 2001-170497 A JP 2003-93890 A JP 2005-169298 A JP 2004-016832 A JP 2002-071298 A

An object of the present invention is to provide a possible photocatalytic filter excellent in durability in addition to having a high photocatalytic ability and a deodorizing apparatus including the photocatalytic filter.

As a result of intensive studies, the inventor combined or combined specific materials for the base material, binder layer, and photocatalyst layer constituting the photocatalytic filter, so that the reflectance of the base material was maintained or improved, and the photocatalytic ability of the photocatalytic filter was improved. It has been found that the photocatalytic component does not fall off from the base material for a long time, and as a result, high photocatalytic ability is maintained for a long time, and the present invention has been completed.

Specifically, the present invention provides:
(1) A photocatalyst having a substrate and a photocatalyst layer in which a photocatalyst component is supported directly on the substrate surface or via a binder layer, wherein the binder layer is a single organic binder layer or organic layer It consists of a layer made of a mixture of a binder and an inorganic binder, or consists of two or more layers in which an organic binder layer or a layer made of a mixture of an organic binder and an inorganic binder is laminated on the organic binder layer. ,
The crystallite diameter of the photocatalytic component is 50 to 150 nm when measured with an X-ray diffractometer,
A photocatalytic filter having a photocatalyst component loading on the binder layer of 5 to 50 g / L or less,
(2) The photocatalyst filter, wherein the photocatalyst layer further comprises an inorganic binder, and the weight ratio of the photocatalyst component and the inorganic binder contained in the photocatalyst layer is 3 or less with respect to the photocatalyst component 1,
(3) The photocatalytic filter according to (1) or (2), wherein the reflectance of the substrate surface is 60% or more when measured at a wavelength of 400 nm using a spectrophotometer,
(4) The photocatalytic filter according to any one of (1) to (3), wherein the substrate has a honeycomb shape,
(5) A deodorizing apparatus comprising the photocatalytic filter according to any one of (1) to (4) and a UV and / or fluorescent lamp.
I will provide a.

According to the present invention, by combining a specific base material, a photocatalyst layer, and optionally these with a binder layer, a photocatalyst filter having a photocatalytic performance equal to or higher than that of a conventional photocatalyst filter and having excellent durability is provided. Can be provided.

FIG. 1 is a diagram showing the acetaldehyde purification performance of the photocatalyst of the present invention.
FIG. 2 is a diagram showing the ammonia purification performance of the photocatalyst of the present invention.
FIG. 3 is a diagram showing the acetic acid purification performance of the photocatalyst of the present invention.
FIG. 4 is a diagram showing the relationship between the coating amount of the photocatalyst layer constituting the photocatalyst of the present invention and the acetaldehyde purification performance.
FIG. 5 is a graph showing the relationship between the thickness of the base material constituting the photocatalyst of the present invention and the acetaldehyde purification performance.
FIG. 6 is a diagram showing the relationship between the number of cells of the base material constituting the photocatalyst of the present invention and the acetaldehyde purification performance.

The present invention is a photocatalyst having a substrate and a photocatalyst layer on which the photocatalyst component is supported directly or via a binder layer on the surface of the substrate,
The binder layer is composed of one organic binder layer or a layer composed of a mixture of an organic binder and an inorganic binder, or a layer composed of an inorganic binder layer or a mixture of an organic binder and an inorganic binder is laminated on the organic binder layer. Two or more layers formed,
The crystallite diameter of the photocatalytic component is 50 to 150 nm when measured with an X-ray diffractometer,
Provided is a photocatalytic filter having a photocatalyst component loading on the binder layer of 5 to 50 g / L or less.

The base material used in the present invention stably holds the photocatalyst layer and imparts strength that can be used as a photocatalyst filter. The material of the base material is not particularly limited, but has a strength capable of holding the shape independently, and is a material that is chemically and physically stable in a use environment as a photocatalytic filter, such as UV, moisture, and photocatalyst. It is preferable that the metal surface is made of a material that is not easily oxidized or eroded by a reaction product or the like. Furthermore, it is preferable that the substrate itself has a high reflectance. For example, a preferable material is a metal such as aluminum, iron, or stainless steel. In order to prevent oxidation or erosion of the substrate or to maintain the reflectance, the substrate may be used after being subjected to a coating treatment. In another embodiment, the substrate may be formed from ceramics such as cordierite, alumina, mullite, silicon carbide, or mixtures thereof. When ceramics is used, the reflectance can be improved to a desired value by polishing or glazing the surface. In yet another aspect, the reflectance of the ceramics may be improved by applying a mirror finish by metal plating such as nickel or copper.

The reflectance (%) of the substrate can be measured using a spectrophotometer. The reflectance described in this specification is measured by UV-3150 manufactured by Shimadzu Corporation.

The reflectance of the base material or the material itself constituting the base material is 60% or more, preferably 70% or more, more preferably 75% or more. Unless otherwise specified, the “reflectance” used in the present specification refers to the reflectance of the base material or the material constituting the base material itself that does not carry a coating layer. However, the reflectance may be derived from light reflected from the substrate surface after the light passes through the coating layer and reaches the substrate surface.

When measuring the reflectance of the constituent material of the base material, the reflectance before the base material is molded, for example, in the case of a honeycomb, the reflectance of the foil is measured. By effectively using “reflection” of light irradiated on the substrate, the photocatalyst supported on the substrate can be used efficiently. Specifically, the light emitted from the light source passes through the photocatalyst layer and binder layer located in the vicinity of the light source, then reflects off the substrate surface, and passes through the binder layer and photocatalyst layer located away from the light source. Therefore, the entire photocatalyst layer is effectively used, and as a result, the photocatalyst utilization rate is improved. As a result, the photocatalytic ability as a filter is improved. When the coat layer or the like absorbs light and there is no reflection, the light does not reach the substrate surface, and the reflected light from the substrate surface cannot be used effectively. It is preferable that a material having a high reflectance such as metal is adopted as the base material, but the reflectance of the base material surface is desired through the pretreatment process even if the material does not reach the above reflectance. It can be used as a base material by improving to the value of. For example, when the base material is made of metal, the reflectance may be improved by acid-treating the base material surface in advance before supporting the photocatalyst layer or the organic binder layer on the base material surface. When the substrate is made of ceramics, the reflectance is improved by polishing or glazing the surface.

Even when the base material has a desired reflectance, the amount of light applied to the coat layer formed on the base material passes through the coat layer and reaches the base material. May decrease significantly. That is, even when sufficient light is irradiated to the photocatalyst filter, depending on the presence of the coating layer, the photocatalyst itself is not irradiated with light, and the photoactivity can be reduced. Therefore, in order to ensure a sufficient amount of light used for the photocatalyst and to make the most of the photocatalytic activity, in addition to selecting a substrate having the above reflectance, a coat layer through which light passes sufficiently is employed. This is very important.

The light transmittance of the coating layer varies depending on the thickness of the coating layer and affects the photocatalytic activity. When the coat layer is thin and has light transmission properties, the light that has passed through the coat layer passes through the coat layer again after being reflected by the substrate. When the coat layer is thick and does not transmit light, the coat layer absorbs light and the photocatalyst utilization rate decreases. As used herein, “coat layer” means a binder layer, a photocatalyst layer, or both.

The thickness of the binder layer is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. The thickness of the photocatalyst layer is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. Even if the thickness of the photocatalyst layer is outside this range, the photocatalyst utilization rate can be ensured by reflection that occurs in a portion of the photocatalyst layer if the thickness falls within this range.

When a metal substrate is used, and the coat layer on the substrate is thin and light transmissive, the light that reaches the metal substrate through the coat layer existing near the light source is the substrate Since the light is reflected on the surface and the reflected light reaches the coat layer existing away from the light source, the photocatalytic component of the entire coat layer can be effectively used. When a metal base material with light reflectivity is selected and a reflective material is added to the coating layer on the base material, in addition to the reflection from the base material, the added reflective material reduces the photocatalyst utilization rate. Can be raised. Even when a metal base material that does not reflect light or a base material that does not reflect light is used, when a reflective material is included in the coat layer, the reflective material plays a role of reflecting light. Even photocatalytic components that are difficult to reach and are located away from the light source can be fully utilized. Alternatively, even when a non-reflective substrate is used, it may be possible to make the substrate reflective by applying a reflective material on the substrate. Light is absorbed by the substrate located so that only the photocatalytic component near the light source is irradiated. On the other hand, when the coat layer on the reflective material is thin and has light transmission, the light reaching the reflective material is reflected and contributes to the improvement of the photocatalyst utilization rate.

High photocatalytic activity can be secured by appropriately selecting the shape of the substrate in addition to the material of the substrate. For example, when a foam-shaped base material is used, light is reflected to the opposite position that is a shadow of light incidence of the foam, and the light reaches a photocatalyst existing at a position away from the light source, so that the photocatalytic activity is improved.

The shape of the substrate used in the present invention is not particularly limited as long as at least a part of the photocatalyst layer is irradiated with light. However, since the harmful substance removal ability of the photocatalyst contributes to the surface area, it is desirable that the base material has a large geometric surface area. For example, preferred shapes include a porous shape such as a honeycomb shape, a pellet shape, and a foam shape, a thin film such as paper, a cloth formed from a fibrous material, and a secondary processed product thereof. A honeycomb has a smaller pressure loss than paper and is preferable as a substrate. The manufacturing method of the honeycomb is not particularly limited. Examples of the secondary processed product include a sheet shape, a sheet-shaped base material having a bellows shape, a corrugated shape, a cylindrical shape, and a columnar / ellipsoidal column. As described above, the honeycomb-shaped and foam-shaped substrates are preferable from the viewpoint of effectively utilizing the photocatalytic component.

When using a foam-shaped base material, if the number of bubbles (cells) is too large, light is hardly transmitted, the effect of the photocatalyst is reduced, and the pressure loss is further increased. On the other hand, when the number of cells is too small, the geometric surface area is further reduced, and as a result, the coating area of the photocatalyst is also reduced. Therefore, in the foam-shaped base material, the number of cells formed by the foam skeleton aligned between 1 inch in a straight line can be adjusted to a predetermined range. For example, in the case of a ceramic foam such as cordierite, it is preferably 2 to 20 pieces / inch, and in the case of a metal foam, it is preferably 2 to 50 pieces / inch.

The BET specific surface area of the photocatalyst layer of the present invention is not particularly limited. However, when a honeycomb-shaped substrate is used, by adjusting the BET specific surface area to 50 m ² / g or more, dust or the like originally passing through the through holes of the honeycomb Can be trapped on the surface, which is preferable. The BET specific surface area described in the present specification refers to a value measured using FLOWSORB-3 (manufactured by Shimadzu Corporation).

When a honeycomb is used as the substrate, its cell density (number of cells per square inch) and its opening diameter vary depending on the conditions for arranging the photocatalytic filter of the present invention. However, from the viewpoint of securing a high geometric surface area, the cell density is preferably 50 to 1500 cells / (inch) ² , more preferably 400 to 1000 cells / (inch) ² . The size of the honeycomb itself varies depending on the use conditions as in the case of the cell, but the honeycomb thickness is within 50 mm, preferably within 30 mm.

The photocatalytic layer is coated on the surface of the base material directly or via a binder layer. Since photocatalyst components such as titanium oxide constituting the photocatalyst layer are easily removed from the substrate, it is preferable to form a binder layer on the substrate surface and form the photocatalyst layer on the binder layer. When the binder is interposed between the base material and the photocatalyst layer, the photocatalyst component is less likely to drop off as the photocatalyst layer is peeled off.

The binder constituting the binder layer may be an organic binder, an inorganic binder, or a mixture thereof. When using ceramics as a base material, the organic binder may not be used, and the binder layer can be formed with an inorganic binder alone. In the case of using a metal substrate, it is preferable to use an organic binder or a mixture of an organic binder and an inorganic binder because the adhesion between the metal substrate and the inorganic binder is low. Although not intended to be bound by theory, among organic binders, an organic binder layer made of a thermoplastic synthetic resin is softened by a part of the organic binder layer in the drying stage of photocatalyst layer formation. This is desirable because the photocatalyst layer is easily fixed. Examples of such organic binders include highly transparent amorphous synthetic resins such as acrylic resins, and polyvinyl acetate. A highly transparent resin such as an acrylic resin is preferable because it does not hinder reflection on the substrate. The acrylic resin is also preferable from the viewpoint of preventing the coating layer such as the photocatalyst layer from peeling off from the base material and preventing the photocatalytic component in the coating layer from being detached. In the case where the synthetic resin stock solution is diluted with water to a predetermined concentration, an aqueous dispersion is desirable. In order to maintain the reflectance of the base material, it is necessary to select a layer in which the formed layer is difficult to absorb light.

By including an inorganic binder in the binder layer, the immobilization of the photocatalyst component becomes strong. In particular, when the photocatalyst component decomposes a part of the organic binder layer, the inorganic binder becomes a skeleton, and the photocatalyst is prevented from falling off. By using a combination of binders having different crystallite diameters or particle diameters, the binder effect is enhanced, and further dropout suppression can be achieved. The inorganic binder contained in the binder layer may be any one or a combination of two or more of silica-based, titania-based, zirconia-based, alumina-based, and the like. Since the titania binder itself may have a photocatalytic ability, it is desirable as an inorganic binder from the viewpoint of improving the photocatalytic ability. A binder that forms a coating layer having a high BET specific surface area, for example, a BET specific surface area of 50 m ² / g or more is preferable because it traps dust in the air.

A titania binder is a titanium compound, an organic titanium compound, or a mixture of an organic titanium compound and other compounds, and is a substance that can bind photocatalyst components or photocatalyst components to a substrate surface or a binder layer. There is no particular limitation on what kind of substance it is. Examples of the titania binder include titanium alkoxide, titanium oxide sol (for example, STS-01, STS-02 manufactured by Ishihara Sangyo, A-6, M-6 manufactured by Taki Chemical), titanium oxide sol containing an inorganic binder in titanium oxide sol (for example, CA-62) manufactured by Taki Chemical Co., Ltd., and titanium oxide sol containing metal alkoxide in titanium oxide (for example, Tynok CZG manufactured by Taki Chemical Co., Ltd .; ethyl polysilicate is used as the metal alkoxide).

The inorganic binder may be either gel or sol. As a precursor, the inorganic binder may be a sol having a certain degree of viscosity in the form of a colloid dispersed in a medium such as water. The inorganic binder preferably has a sol particle diameter of 5 to 200 nm from the viewpoint of fixing the photocatalyst.

Not only an inorganic binder having a single crystallite diameter or particle diameter but also an inorganic binder having a combination of different crystallite diameters or particle diameters can be used. The crystallite diameter can be measured with an X-ray diffractometer according to Scherrer's formula (Scherrer, P. (1918). Nachr. Ges. Wiss. Gottingen, 26 September, p. 98-100). The crystallite diameter described in the present specification refers to a value measured using RINT-2500V (manufactured by Rigaku Corporation).

The binder layer may be a single organic binder layer or a layer composed of a mixture of an organic binder and an inorganic binder. However, the binder layer is not limited to a single layer, and may be composed of a plurality of layers. When the binder layer is composed of a plurality of layers, each layer is composed of the same or different kinds of organic binders, inorganic binders and / or mixtures thereof, and when the organic binder and the inorganic binder are combined, the ratio is It is determined appropriately so as to improve the strength. From the viewpoint of improving the strength of the photocatalytic filter, the binder layer is preferably a single binder layer, particularly a single binder layer comprising an organic binder. Moreover, when a binder layer consists of a several layer, it is preferable that another binder layer is laminated | stacked on the one organic binder layer formed in the base-material surface. In another embodiment, these layers may contain an optional component such as a phosphorescent material and a reflective material in addition to the binder. Due to the presence of the reflective material, the reflectance of the base material is improved, and as a result, the photocatalytic ability is also improved. As an example of the reflective material, there is Unibeads (manufactured by Unitika).

The method for supporting the binder layer on the substrate surface is not particularly limited. A method in which a solution in which a binder is dissolved or suspended is prepared in advance, and the solution is directly applied to the substrate surface and dried to form a binder layer. A method of forming a binder layer on the surface of the substrate by immersing and drying the substrate in the solution, or a method of forming a binder layer by pressing the binder onto the surface of the substrate without using a solution is conceivable. . The thickness of the binder layer can be adjusted by repeating the above supporting method. From the viewpoint of maintaining the reflectance, the thickness of the binder layer is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

The photocatalytic layer is formed on the surface of the base material or the binder layer. As used herein, the term “photocatalytic component” means a substance that is activated when irradiated with light to decompose harmful substances in the air. The light is selected depending on the application and the light source installed, and a photocatalyst that responds to the light source used therefor is selected. Photocatalyst components include titanium oxide (titania), zinc oxide, tungsten oxide, copper oxide and other metal oxides, or metal oxide-supported titanium oxide such as platinum, gold, silver, copper, iron, palladium, zirconium, or ruthenium complexes. A simple substance of a metal complex such as, or a complex thereof can be used. What substituted a part of titanium oxide with other elements, such as nitrogen, can also be used.

When titanium oxide is used as the photocatalytic component, the crystal structure of titanium oxide may be any of anatase type, rutile type, brookite type, or a mixture thereof. The photocatalyst may be either gel or sol. As a precursor, the photocatalyst may be a sol having a certain degree of viscosity in the form of a colloid dispersed in a medium such as water. The particle size of the sol may be within the range normally used, for example, 5 to 200 nm. From the viewpoint of uniformly dispersing the photocatalytic component, the particle size is preferably 10 to 50 nm. The crystallite diameter of the photocatalyst component is preferably 50 to 150 nm, more preferably 60 to 120 nm, and even more preferably 70 to 100 nm. The supported amount of the photocatalyst component is preferably 5 to 50 g, more preferably 6 to 35 g, and still more preferably 7 to 20 g per liter.

The photocatalyst layer may further contain an inorganic binder. By including an inorganic binder in the photocatalyst layer, the immobilization of the photocatalyst component can be made stronger. The kind of the inorganic binder in the photocatalyst layer may be the same as or different from that contained in the binder layer. The inorganic binder may be either gel or sol, and it is preferable to select a sol as the precursor. The particle size of the inorganic binder is preferably 5 to 300 nm, more preferably 5 to 100 nm, from the viewpoint of fixing the photocatalytic component. If it is in the range of the said particle diameter, it can also be used combining the inorganic binder which has a different particle diameter.

When an inorganic binder is included in the photocatalyst layer, by increasing the ratio of the inorganic binder, the adhesion between the substrate and the coating layer is improved, and the photocatalyst component can be prevented from peeling off from the substrate. That is, by increasing the weight ratio of the inorganic binder in the photocatalyst layer, it is possible to prevent the degradation of the photocatalytic performance due to the loss of the photocatalytic action. On the other hand, when the inorganic binder increases and the absolute amount of the photocatalyst component decreases, the photocatalytic ability decreases. Therefore, from such a viewpoint, the weight ratio of the photocatalyst component to the inorganic binder is 3 or less, preferably 2.5 or less, with respect to the photocatalyst component 1. Note that the decrease in the photocatalytic ability accompanying the increase in the amount of the inorganic binder also occurs when the photocatalytic component is buried in the binder.

The photocatalyst layer may contain arbitrary components as long as the photocatalytic ability of the photocatalyst is not impaired. For example, for the purpose of improving the photocatalytic ability of the photocatalytic component, a phosphorescent material or a reflective material as described above may be included.

The method for supporting the photocatalyst layer on the surface of the substrate or the binder layer is not particularly limited, and a solution in which the photocatalyst component and optionally an inorganic binder are dissolved or suspended is used as a base on which the substrate surface or the binder layer is formed. A method of coating and drying on the surface of the material, a method of immersing and drying a substrate on which a binder layer is formed in the solution, or a photocatalyst component or a mixture of a photocatalyst component and an inorganic binder without using such a solution. A method of pressure-bonding to the surface of the base material on which the adsorbent layer is formed is conceivable. The thickness of the photocatalyst layer can be adjusted by repeating the above supporting method. From the viewpoint of effectively utilizing light while maintaining the reflectance, the thickness of the photocatalyst layer is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. Even if the thickness of a part of the photocatalyst layer is outside the numerical value range, the photocatalyst utilization rate may be ensured if the thickness of the other part is within the numerical value range.

The photocatalytic filter of the present invention is suitable for treating malodors such as three components of acetaldehyde, acetic acid and ammonia contained in tobacco odor, as well as formaldehyde, hydrogen sulfide, methyl mercaptan, toluene, nitrogen oxides, ozone and the like. . Among these malodors, the photocatalytic filter of the present invention can efficiently purify toluene, ammonia and acetic acid. You may arrange | position the photocatalyst filter of this invention in a deodorizing apparatus, for example, a general purpose air cleaner. The arrangement of the photocatalytic filter in the deodorizing apparatus is not particularly limited, but a UV lamp or a fluorescent lamp lamp, particularly a UV lamp, is arranged around the filter in order to maximize the photocatalytic ability of the filter. It is desirable. For example, you may arrange | position the said photocatalyst filter in the downstream direction part of the malodorous flow direction of a UV lamp or a fluorescent lamp lamp. In addition to the UV lamp or the fluorescent lamp, a filter, a fan or the like having a dustproof function and an adsorption deodorizing function may be installed in the apparatus. The coexistence of the photocatalyst filter of the present invention and the filter having an adsorption deodorizing function complements each other and makes it possible to remove malodors that could not be removed alone.

The present invention will be described more specifically with reference to the following examples. The present invention is not limited to these examples.

Production of photocatalytic filter An aluminum honeycomb (made by Cataler) made of an aluminum foil having a reflectance of 81% was used, and an acrylic resin (Boncoat AB-795 (made by DIC Corporation)) was used as an organic binder. The reflectance was measured at a wavelength of 400 nm using a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation).

The acrylic resin was diluted with ion-exchanged water so as to have a nonvolatile content of 2.5% by weight, the substrate was immersed in the diluent, and the diluent was uniformly attached to the substrate surface. After blowing off the excessive diluent on the substrate surface, the substrate was dried at 110 ° C. to form an organic binder layer. It was immersed in the aqueous photocatalyst liquid (pH 7) prepared beforehand, and the said photocatalyst liquid was made to adhere evenly to the surface of the organic binder layer. After blowing off excess photocatalyst solution on the substrate surface, the substrate was dried at 110 ° C. to form a photocatalyst layer, and a photocatalyst filter as shown in the following table was obtained (Example 1). ~ 6 and Comparative Example 1) (photocatalyst layer coating amount: 30 g / L; photocatalyst component / inorganic binder: 50/50 ... weight ratio). Here, the crystallite diameter of the photocatalyst component in the following table is measured using RINT-2500V (manufactured by Rigaku Corporation).

Odor purification test Acetaldehyde purification performance evaluation A 60 x 60 mm filter test piece of the photocatalytic filter was prepared. The test piece was placed in an acrylic box (30 L) and sealed, and then 1% acetaldehyde (300 mL) was added so that the inside of the box was about 100 ppm. The acetaldehyde concentration in the box was made uniform using a container stirring fan. The initial concentration C ₀ was measured 60 minutes after the addition of acetaldehyde. Irradiating the initial concentration measured after black light, to determine the concentration _{C t} after 15, 30, 45, 60 minutes from the irradiation. The concentration C ₀ and the concentration C _t were measured using a hydrogen flame ion detector (FID: GC-8A manufactured by Shimadzu Corporation). The measurement results after 30 minutes are shown in FIG. The purification rate was calculated based on the following calculation formula.
Purification rate (%) = (100− (C ₀ −C _t ) / C ₀ ) × 100

2. Instead of ammonia purification performance evaluation 1% acetaldehyde, with 1% ammonia and, except that the density was

C

_t 5, 15 minutes after the black light irradiation, the photocatalyst under the same conditions as acetaldehyde purification performance evaluation A filter test piece (60 × 60 mm) was subjected to an ammonia purification performance evaluation test. The concentration C ₀ and the concentration C _t were measured using detector tubes (105SD (for concentration of 0.2 to 20 ppm) and 105SC (5 to 260 ppm) manufactured by Komyo Chemical Co., Ltd.). The measurement result after 5 minutes is shown in FIG. The purification rate was calculated based on the above formula.

3. Acetic acid purification performance evaluation Instead of 1% acetaldehyde, 1% acetic acid (prepared as a 1% gas with tetrabac) was used, and the concentration C _t was performed 15 and 30 minutes after irradiation with black light. The test piece (60 × 60 mm) of the photocatalytic filter was subjected to an acetic acid purification performance evaluation test under the same conditions as the acetaldehyde purification performance evaluation. The initial concentration was measured using a detector tube (81 manufactured by Gastec). The measurement results after 15 minutes are shown in FIG. The purification rate was calculated based on the above formula.

As is clear from the results of FIGS. 1 to 3, it can be seen that the photocatalytic filter of the present invention deodorizes any offensive odors tested in a short time.

Examination of photocatalyst layer coating amount In order to examine the relationship between the photocatalyst layer coating amount and the purification performance, photocatalytic filters described in the following table were prepared.

As apparent from the above table and FIG. 4, the acetaldehyde purification rate improved as the coating amount increased.

Examination of substrate thickness In order to examine the relationship between the substrate thickness and the purification performance, photocatalytic filters described in the following table were prepared.

As is clear from the above table and FIG. 5, the acetaldehyde purification rate increases as the substrate thickness increases.

Examination of the number of substrate cells In order to examine the relationship between the number of substrate cells and the purification performance, photocatalytic filters described in the following table were prepared.

As can be seen from the above table and FIG. 6, the acetaldehyde purification rate increases as the number of substrate cells increases, but the acetaldehyde purification rate of the photocatalytic filter of 1200 cells / (inch) ² is 400 cells / (inch) ² . It was lower than the one.

Peeling test In order to test the strength of the photocatalytic filter of the present invention, a photocatalytic filter having one binder layer (Examples 17 to 19) and a photocatalytic filter having two binder layers (Examples 20 to 22) were prepared. .

A) Preparation of photocatalytic filter having one binder layer The photocatalytic filter of the present invention was prepared according to the following procedure.
1. Weight measurement (S ₀ ) of aluminum honeycomb (made by Cataler) (W30 × D30 × H20 mm) made of aluminum foil having a reflectance of 81%
2. An organic binder having a nonvolatile content of 50% by weight (see Table 1 below) was diluted 20 times with ion-exchanged water to prepare a binder solution having a nonvolatile content of 2.5% by weight.
3. The base material is Then, the substrate is dried (110 ° C.) (formation of an organic binder layer).
4.3. Weight measurement (S ₁ ).
5. A photocatalyst (TiO ₂ sol solid content 20% by weight) and an inorganic binder (silica sol solid content 20% by weight) were mixed at a weight ratio of 5: 5.
6.4. 5. Then, the substrate is dried (110 ° C.) (formation of a photocatalyst layer containing an inorganic binder).
7.6. Weight measurement (S ₃ ).
8). The coat layer weight (CW) is calculated from the difference in weight between the sample after coating and the substrate. CW = (S ₃ −S ₀ ).

By following the above procedure, a photocatalytic filter having a substrate, an organic binder layer carried on the surface of the substrate, and a photocatalyst layer containing an inorganic binder carried on the surface of the organic binder layer (implementation) Examples 17 to 19) were prepared (photocatalyst component loading: 13.9 g / L; photocatalyst component / inorganic binder: 50/50 weight ratio). Here, the crystallite size of the photocatalyst component used in Examples 17 to 19 was measured using RINT-2500V (manufactured by Rigaku Corporation), and as a result, all were in the range of 81 to 82 nm.

B) Preparation of photocatalytic filter having two binder layers The photocatalytic filter of the present invention was prepared according to the following procedure.
1. Weight measurement (S ₀ ) of an aluminum honeycomb (made by Cataler) (W30 × D30 × H20 mm) made of an aluminum foil having a reflectance of 81%.
2. An organic binder having a nonvolatile content of 50% by weight (see Table 1 below) was diluted 20 times with ion-exchanged water to prepare a binder solution having a nonvolatile content of 2.5% by weight.
3. The base material is Then, the substrate is dried (110 ° C.) (formation of an organic binder layer).
4.3. Weight measurement (S ₁ ).
5. 2. Inorganic binder (silica sol, solid content 20% by weight) Then, the substrate is dried (110 ° C.) (formation of an inorganic binder layer).
6). A photocatalyst (TiO ₂ sol solid content 20% by weight) and an inorganic binder (silica sol solid content 20% by weight) were mixed at a weight ratio of 5: 5.
7.5. Weight measurement (S ₂ ).
8.6. 7. Then, the substrate is dried (110 ° C.) (formation of a photocatalyst layer containing an inorganic binder).
9.8. Weight measurement (S ₃ ).
10. The coat layer weight (CW) is calculated from the difference in weight between the sample after coating and the substrate. CW = (S ₃ −S ₀ ).

By following the above procedure, a base material, an organic binder layer supported on the surface of the base material, an inorganic binder layer supported on the surface of the organic binder layer, and supported on the surface of the inorganic binder layer A photocatalyst filter (Examples 20 to 22) having a photocatalyst layer containing an inorganic binder was prepared (photocatalyst component loading: 6.9 g / L; photocatalyst component / inorganic binder: 50/50 ... weight ratio) . Here, the crystallite diameter of the photocatalyst component used in Examples 20 to 22 was measured using RINT-2500V (manufactured by Rigaku Corporation), and as a result, all were in the range of 81 to 82 nm.

Photocatalyst component drop-off test by peeling off coat layer A 30 × 30 mm test piece of the photocatalyst filter of each example was dried at 110 ° C. for 3 hours or more, allowed to cool, and its weight was measured (W ₁ ). The test piece was placed in a 200 mL tall beaker containing 100 mL of distilled water, and subjected to ultrasonic treatment for 60 minutes in an ultrasonic cleaning machine (UT105 manufactured by Sharp Corporation). Then, the test piece was taken out and dried for 10 hours or more with a dryer (110 ° C.). After leaving it to be 30 ° C. or lower, the weight of the test piece was measured (W ₂ ). The coating layer peeling rate was calculated from the following formula: (W ₁ −W ₂ / CW) × 100. The results are shown in Table 6 below.

From the results in Table 2, it can be seen that the peeling rate varies depending on the type of organic binder, and that the peeling rate also depends on the number of coatings of the layer coated on the organic binder layer. Further, it has been clarified that when an acrylic organic binder is included in the binder layer among the organic binders, the coat layer on the binder layer is hardly peeled off.

The photocatalytic filter of the present invention has a photocatalytic performance equal to or higher than that of a conventional photocatalytic filter and is excellent in durability, so that it is required to maintain a high photocatalytic performance for a long period of time, for home use or for business use. It is suitable for.

Claims

A photocatalyst having a substrate and a photocatalyst layer on which the photocatalyst component is supported directly or via a binder layer on the substrate surface,
The binder layer is composed of one organic binder layer or a layer composed of a mixture of an organic binder and an inorganic binder, or a layer composed of an inorganic binder layer or a mixture of an organic binder and an inorganic binder is laminated on the organic binder layer. Two or more layers formed,
The crystallite diameter of the photocatalytic component is 50 to 150 nm when measured with an X-ray diffractometer,
A photocatalytic filter, wherein the amount of the photocatalytic component supported on the binder layer is 5 to 50 g / L or less.
The photocatalyst filter according to claim 1, wherein the photocatalyst layer further comprises an inorganic binder, and the weight ratio of the photocatalyst component and the inorganic binder contained in the photocatalyst layer is 3 or less with respect to the photocatalyst component 1. .
The photocatalytic filter according to claim 1 or 2, wherein the reflectance of the substrate surface is 60% or more when measured at a wavelength of 400 nm using a spectrophotometer.
4. The photocatalytic filter according to claim 1, wherein the substrate has a honeycomb shape.
A deodorizing apparatus comprising the photocatalytic filter according to any one of claims 1 to 4 and a UV and / or fluorescent lamp.