JP2001238938A - Deodorization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deodorization method which allows the execution of deodorization even when the UV rays of sunlight are drastically attenuated by UV protective glass or films, etc. SOLUTION: In the deodorization method to arrange photocatalysts in an irradiation region of the sunlight shielded or attenuated of the UV rays, these photocatalysts are preferably arranged in the state that the photocatalyst particulates are deposited within the communicating gaps of the baked body of a polytetrafluoroethylene resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deodorizing method for removing or reducing the concentration of tobacco and other bad smells in a vehicle or a room using a photocatalyst, and more particularly to a method for removing deodorization in a state where ultraviolet rays are shielded or reduced. Useful to do.

[0002]

2. Description of the Related Art As is well known, in a metal oxide semiconductor such as titanium oxide, electrons in a valence band jump up to a conduction band by irradiation of ultraviolet rays to generate holes, and contact with the surface under this excited state. Active species (radicals) are generated from the generated oxygen and moisture, and the active species oxidize and decompose organic substances and microorganisms attached to the surface.

Therefore, it is known to purify air such as deodorant or antibacterial in a living space or a work place by utilizing the oxidative decomposition action of a metal oxide semiconductor such as titanium oxide, that is, photocatalytic particles. For example, it is known to deodorize new vehicle odors, tobacco odors, or to reduce and remove volatile organic compounds (VOCs) in vehicles.

Conventionally, as a photocatalyst sheet, a mesh-shaped photocatalyst sheet in which a resin layer containing photocatalyst particles is provided on the surface of a mesh-shaped support base material is known (JP-A-3-106).
No. 420). With this mesh-shaped photocatalyst sheet, the air resistance can be sufficiently reduced to purify the flowing air. Also,
There is an advantage that the photocatalyst action can be performed on the entire surface of the mesh by reflecting the ultraviolet light having passed through the ventilation hole with the reflecting mirror.

Further, the applicant of the present invention applied such a mesh-shaped photocatalyst sheet to a mesh-shaped glass base material by applying a dispersion of polytetrafluoroethylene powder and photocatalyst particles, and forming this coating layer on the mesh glass base material. A photocatalyst sheet that is safely fired under heat resistance has been developed (JP-A-11-128630).

It has been known that the above-mentioned photocatalyst sheet is excited by an ultraviolet lamp, sunlight, or the like. However, the ultraviolet lamp can easily obtain a certain effect at the time of light emission. It was common in equipment. on the other hand,
It is difficult to obtain a stable effect of sunlight under seasonal, weather, day and night conditions, but there is an advantage that the effect can be obtained without using artificial energy. In particular, in the vicinity of a window in a room or in a vehicle, the photocatalytic sheet is easily exposed to sunlight, and the deodorizing and purifying effect of the photocatalyst sheet is easily obtained.

[0007]

However, in recent years,
It has been pointed out that ultraviolet components contained in sunlight have a bad effect on human bodies such as human skin and eyes, and ultraviolet-cut glass and ultraviolet-cut films are increasingly used for window glasses of automobiles and houses. Accordingly, sunlight passing through such a window glass has an insufficient amount of ultraviolet light (for example, 99% or more of ultraviolet light extinction ratio). Therefore, a photocatalyst known to have a photocatalytic action by ultraviolet light has no deodorizing effect. It has been considered impossible.

Accordingly, an object of the present invention is to provide a deodorizing method capable of deodorizing even when ultraviolet rays of sunlight are remarkably dimmed by an ultraviolet cut glass or a film.

[0009]

The present inventors surprisingly and unexpectedly found that a photocatalyst sheet or the like that can be deodorized by sunlight is
Even when irradiating sunlight with extremely reduced ultraviolet light,
They have found that they have a practically usable level of deodorizing effect, and have completed the present invention.

That is, in the deodorizing method of the present invention, a photocatalyst is disposed in an irradiation area of sunlight where ultraviolet rays are blocked or reduced.

The present invention is particularly useful when the sunlight is transmitted through a material that selectively blocks 99% or more of ultraviolet rays.

[0012] In the above, when disposing the photocatalyst, it is preferable that the photocatalyst fine particles be supported in the communication gap in the fired body of polytetrafluoroethylene resin.

[Effects] According to the deodorizing method of the present invention,
As shown by the results of the examples, practically sufficient deodorizing effects can be obtained even when ultraviolet rays of sunlight are significantly reduced by ultraviolet cut glass or film.
Although the reason is not always clear, it is possible that the wavelength range of the excitation light at which the photocatalyst is excited does not completely match the wavelength range of the ultraviolet light (ultraviolet absorption area) blocked by the ultraviolet cut glass or the like. It is considered as.

When the sunlight passes through a material that selectively blocks 99% or more of the ultraviolet rays, it has been considered that a photocatalyst cannot be expected to have any deodorizing effect. Therefore, the present invention is particularly useful. Become. In other words, even if the material blocks 99% or more of ultraviolet rays, the ultraviolet ray absorption range is 370n.
m or less, and the upper limit wavelength of the excitation light at which the photocatalyst is excited becomes longer than that (for example, in general, absorption of titanium oxide starts at a wavelength of 400 nm or less. In this case, the wavelength is 413 nm)
Therefore, it is possible to obtain a certain deodorizing effect.

When disposing the photocatalyst, when the photocatalyst fine particles are carried in the communication voids in the fired body of polytetrafluoroethylene resin, the communication voids exist between the photocatalyst fine particles and the resin. As a result of increasing the contact area of the photocatalyst fine particles with air, the deodorizing efficiency is further improved. In addition, there is a technology that enables deodorization under visible light by doping or ion-implanting metal ions into a photocatalyst, but in the above case, without passing through such a complicated manufacturing process, sunlight Even if the ultraviolet rays are shielded, a sufficient deodorizing effect can be reliably obtained.

[0016]

Embodiments of the present invention will be described below. The deodorizing method of the present invention is to dispose a photocatalyst in an irradiation area of sunlight where ultraviolet rays are blocked or dimmed. The ultraviolet light that is blocked or dimmed refers to, for example, a material that selectively blocks or diminishes ultraviolet light, ultraviolet light cut glass, sunlight that has passed through an ultraviolet light cut film, or the like, and has a wavelength smaller than about 300 to 400 nm. Are absorbed or the like, and are blocked or dimmed. In an automobile, a house, etc., an ultraviolet cut glass having a dimming rate of 99% or more is often used. However, in the present invention, deodorization is performed even when irradiating sunlight passing through a 99% or more ultraviolet cut glass. It is possible. In addition, the definition of the extinction ratio of the ultraviolet cut glass or the like is the integrated amount ratio in the ultraviolet region of 380 nm or less.

The deodorizing effect in the present invention is determined by the selection of a photocatalyst with respect to a material that blocks or diminishes ultraviolet rays.
Even when irradiation is performed with the light reduced to / 100 or less, it is preferable that the deodorizing effect of the photocatalyst is maintained at 1/10 or more, and more preferably at least 1/5 or more. At that time, the ratio of the deodorizing effect depends on whether the material is absent or present,
Odorous compounds such as acetaldehyde (for example, initial concentration 6p
The ratio of the reciprocal of the time until the residual ratio of pm) becomes 20% or less may be obtained.

As a method for disposing the photocatalyst, the photocatalyst in the form of particles may be placed in a container such as a tray and disposed as it is in the irradiation area. However, the particles of the photocatalyst may be directly or via a suitable binder onto the supporting substrate. Fixing is preferred from the viewpoint of handling and the like.

The form of the supporting substrate may be any form such as a film, a sheet, a fiber, a woven fabric, a nonwoven fabric, a mesh sheet, or a pleated, tubular, or spiral shape thereof. . Further, the material of the supporting base material may be any material such as resin, ceramic, and metal.

Examples of the photocatalyst include titanium oxide, strontium titanate, tungsten oxide, zinc oxide, tin oxide, and cadmium sulfide. Anatase type titanium oxide fine particles exhibiting the most excellent photocatalytic activity can be used. preferable. Further, in order to enhance the activity of the photocatalyst particles, an alkali metal ion can be supported.

Examples of the binder include an organic binder such as a fluorine-based resin such as polytetrafluoroethylene, vinyl ether-fluoroolefin copolymer and vinyl ester-fluoroolefin copolymer, and a silicone-based resin, and an inorganic binder such as silica-based and metal amorphous. Any one may be used.

Further, a deodorizing agent mainly composed of an adsorbent such as activated carbon, zeolite, copper carboxymethylcellulose, silica gel and alumina may be used in combination. In that case, they may be laminated while being held on a sheet-like material, or may be mixed with the photocatalyst particles.

In the present invention, in disposing the photocatalyst, it is preferable that the photocatalyst fine particles be supported in the communication gap in the fired body of the polytetrafluoroethylene resin. It is preferable to use a photocatalyst having a photocatalyst layer in which fine particles of photocatalyst are dispersed in a fired body, minute voids are formed between the resin and the fine particles of photocatalyst, and a porosity of 7% or more is formed on a supporting substrate. Hereinafter, this will be described as a preferred example.

In this photocatalyst, a photocatalyst layer is provided on the surface of a supporting substrate, and photocatalyst fine particles are dispersed in a sintered body of sintered polytetrafluoroethylene powder. Are formed, and the gaps between the sintered polytetrafluoroethylene powders are connected to the air layer to form a multi-gap communication structure. The thickness of the gap between the polytetrafluoroethylene resin and the photocatalyst fine particles is a fine gap of several nanometers to several microns, and due to the hydrophobicity of polytetrafluoroethylene, passage of water and the like does not occur, but air Can be well spilled.

In order to produce a photocatalyst, a dispersion containing polytetrafluoroethylene powder and photocatalyst fine particles is applied to a supporting substrate, the solvent in the coating layer is removed by evaporation by heating, and further heated and baked (heated). (The temperature is 330 ° C. or higher) to sinter the polytetrafluoroethylene particles. At the time of cooling after the sintering, due to the heat shrinkage larger than the photocatalyst fine particles of the polytetrafluoroethylene resin and the non-fusion property of the polytetrafluoroethylene resin to the photocatalyst fine particles, the photocatalytic fine particles and the polytetrafluoroethylene resin An air layer forms between them. Also, the melt viscosity of the polytetrafluoroethylene powder during firing is high (10
⁽⁸ poise or more) Since the particle shape is maintained without flowing and the sintering is performed without pressure, a sufficient gap is left between the sintered polytetrafluoroethylene powders. Therefore,
The photocatalyst layer becomes a gas permeable multi-gap structure.

The particle size of the polytetrafluoroethylene powder is 0.1 to 1 μm, and the particle size of the photocatalyst fine particles is 200 n.
m, preferably 50 nm or less. The porosity of the photocatalyst layer is at least 7%, preferably at least 10%.
The porosity x is given by x = 1− [w / (vρ)], where ρ is the true specific gravity of the photocatalytic layer and w is the weight of the volume v of the photocatalytic layer. If the porosity is less than 7%, the effect of improving the degree of contact between air and photocatalyst fine particles by the multi-porous structure is low, and it is difficult to satisfactorily deodorize. However, it is preferable to be 30% or less in terms of mechanical strength. The thickness of the photocatalyst layer is 3 μm to 30 μm.
It is preferably set to μm. If it is less than 3 μm, the volume of the photocatalyst layer will be small and the deodorizing performance will be low. If it exceeds 30 μm, the gas diffusion efficiency will decrease and the layer thickness will be unnecessarily thick. If the content of the photocatalyst fine particles in the dispersion is too large, the binding strength between the photocatalyst fine particles by polytetrafluoroethylene becomes insufficient. Therefore, the content of the photocatalyst fine particles is preferably 5 to 60% by weight.

As the above-mentioned supporting base material, a material having heat resistance which does not cause deformation or the like even by heating during firing is used, for example, metal foil such as aluminum and stainless steel, inorganic plate such as ceramic plate and glass plate, and the like. Heat-resistant plastic film such as polyimide or polytetrafluoroethylene, or woven glass fiber or polyamide fiber impregnated with heat-resistant plastic such as polytetrafluoroethylene, or felt of glass fiber, ceramic fiber, metal fiber, or carbon fiber alone or as a mixture A net-like material such as a glass fiber, a ceramic fiber, a metal fiber, and a carbon fiber alone or as a mixture can be used. The method for applying the dispersion to the support substrate includes a method of applying the dispersion with a roll coater, a method of dipping and lifting the support substrate in the dispersion, a method of spraying the dispersion, a method of brushing the dispersion, and a method of dispersing the dispersion. A method of casting John can be used. The concentration of the dispersion is set according to the coating method, and is usually 40 to 60% by weight. An additive for increasing the porosity of the fired layer, an additive for improving the strength, and a gas adsorbent that can withstand the firing temperature can be appropriately added to the dispersion.

The deodorizing method of the present invention can be used for a portion where an ultraviolet cut glass or an ultraviolet cut film is used such as an automobile or a house. When used in an automobile, for example, the photocatalyst is arranged between the windshield and the rearview mirror of the automobile so as to substantially not obstruct the driver's view, or the passenger's view is substantially reduced near the rear window. They can be arranged in unobstructed dimensions. In addition, when used in the interior of a house or in an office building, it can be placed on the whole or a part of the window glass or a part of the wall surface. For example, a method of hanging from a curtain rail like a curtain, screws on a window frame, etc. And a method of fixing with a fastener.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and the like specifically showing the configuration and effects of the present invention will be described below.

(Preparation of Mesh Photocatalyst Sheet)
Glass cloth mesh with 16 meshes (16 × 16 meshes per inch) (KS5241 manufactured by Kanebo)
Was cut into 500 mm x 660 mm to obtain a hand-coated glass cloth mesh base material. Next, as an undercoating solution, a PTFE dispersion solution (XAD936 manufactured by Asahi Glass Fluoropolymers Co., Ltd. (base concentration: 6)
(0 wt% product)) was diluted with distilled water to a base concentration of 40 wt% to obtain an undercoating solution. After the glass cloth mesh base material for hand coating is immersed in the entire undercoating solution, the glass cloth mesh base material for hand coating is pulled up, and the surface is squeezed with two wire bars (# 3) to reduce the coating thickness. Made uniform. Thereafter, in a drying furnace, preliminary drying (drying of water) was performed at 120 ° C. × 2 minutes, and then baking was performed at 390 ° C. × 2 minutes, and the temperature was returned to room temperature.

Next, as a top coating solution,
A PTFE dispersion solution (XAD936 manufactured by Asahi Glass Fluoropolymers Co., Ltd. (base concentration: 60 wt%)) so that the composition ratio (weight ratio) becomes PTFE 6 / titanium oxide 4.
And titanium oxide (ST-01 manufactured by Ishihara Sangyo Co., Ltd.) and distilled water are mixed and stirred to obtain a top coating solution having a base concentration of 40 wt%. After dipping the undercoated glass cloth mesh base material prepared above in the top coating solution on the entire surface, the undercoated glass cloth mesh base material is pulled up, and a wire bar (# 3)
With two, the surface was roughened and the coating thickness was made uniform. afterwards,
Pre-drying (drying of water) 120 ° C x 2 in a drying oven
Then, baking was performed at 390 ° C. for 2 minutes to obtain a mesh-shaped photocatalyst sheet. The opening ratio of this sheet was 49%, and the ventilation was sufficient.

(Embodiment) As shown in FIG.
Sealable 2m with transient FEP transparent film ^Three Bob
In the box, the photocatalyst sheet (500 x 660 mm)
Install horizontally 30mm below the ceiling and fan in the box
The apparatus was set up and stirred so that air did not stay.

In order to measure comparative data in the case where there is no UV cut glass, acetaldehyde was poured into a box beforehand at about 11 am when sunny and direct sunlight was applied, with a light-shielding plate installed on the ceiling ( Concentration about 6 ppm), 4
After one minute, the light-shielding plate was removed and direct sunlight was applied to the photocatalyst sheet, and the acetaldehyde concentration was continuously measured every minute by a photoacoustic gas monitor. 3 after sunshine
The measurement was stopped after 0 minutes.

Next, the box was opened, the inside air was replaced and the inside was resealed, and from 00:00 pm, a 99.6% ultraviolet cut laminated glass (UV, manufactured by Asahi Glass Co., Ltd., UV) was placed between the light-shielding plate and the FEP film. Cut glass, float Lamisafe UV 6 mm thick), acetaldehyde was injected in the same manner as above, and after 4 minutes, the light-shielding plate was removed, and direct sunlight passed through the UV-cut glass to the photocatalyst sheet. In this way, the gas concentration was measured. Measurements were stopped 90 minutes after sun exposure.

To measure the blank data, open the box, replace the air inside, reseal it, place the box in a room free from sunlight, and keep the light-shielding plate in place as described above. Acetaldehyde was injected, and the gas concentration was measured after 4 minutes. The gas concentration measurement was stopped after 30 minutes.

As a result, as shown in FIG. 2, about 1/3 of the decomposition effect (deodorization effect) is obtained with the light transmitted through the UV cut glass as compared with the case where the direct sunlight is irradiated, and it takes a little time. However, the final decomposition residual ratio was the same.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an apparatus used for concentration measurement in an embodiment.

FIG. 2 is a graph showing the relationship between the measurement time and the residual ratio of acetaldehyde in Examples.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadanori Michimoto 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 4C080 AA07 BB02 CC12 HH05 JJ06 KK08 LL10 MM02 NN01 NN02 NN27 NN28 QQ20 4D048 AA19 AA22 AB03 BA07X BA15Y BA16Y BA21Y BA27Y BA41X BB07 BB08 CA06 CD01 CD05 EA01 4G069 AA03 AA08 BA04B BA22C BA32C BA48A BE34C CA10 CA15 CA17 DA06 EA01X EA01Y EA09 FC04 FB04

Claims (3)

[Claims] 1. A deodorizing method in which a photocatalyst is disposed in an irradiation area of sunlight where ultraviolet rays are blocked or reduced. 2. The deodorizing method according to claim 1, wherein the sunlight passes through a material that selectively blocks 99% or more of ultraviolet rays. 3. The deodorizing method according to claim 1, wherein, when the photocatalyst is disposed, the photocatalyst fine particles are supported in communication voids in a fired body of polytetrafluoroethylene resin.