JP2005208262A - Surface leakage light optical waveguide and photo-catalytic device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface leakage light optical waveguide which is manufactured easily, made to be of long-length and large area, and further excellent in an efficiency of photocatalytic reaction, and also to provide a photo-catalytic device using the waveguide. <P>SOLUTION: In the surface leakage light optical waveguide 10 provided with a core part 11 and clad parts 12, 12 which are made of a material with a lower refractive index than the core part 11 and stacked as surrounding the core part 11, a mode coupling part 13 for producing mode coupling of light propagated in the core part 11 is arranged in the clad parts 12, 12, and a photo-catalytic film 15 is provided outside the clad parts 12, 12. The mode coupling part 13 is to be made of air bubbles arranged in the clad part 12, 12 or an additive which is added in the clad parts 12, 12 and does not absorb the light in the wavelength band where photocatalytic reaction is caused. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface leakage optical waveguide that activates a photocatalyst supported on the outside using a function of light gradually leaking from a surface while propagating light, and a photocatalytic device using the same.

  In recent years, research and application on the decomposition of organic substances and pollutants by photocatalytic reactions have been actively conducted. Conventionally, a photocatalyst device provided with a photocatalyst is roughly composed of a carrier such as various filters and tiles and a photocatalyst carried on the surface thereof. This photocatalytic device causes a photocatalytic reaction by directly irradiating light emitted from a separate light source.

  However, in the photocatalytic device having such a configuration, when dust or other organic or inorganic dust adheres to the surface of the photocatalyst, the light emitted from the light source cannot sufficiently reach the surface of the photocatalyst. In addition, the photocatalytic reaction does not occur sufficiently or the photocatalytic reaction does not occur at all.

Further, in such a photocatalytic device, the light source and the photocatalyst are arranged at a distance, so that light emitted from the light source is lost due to scattering, absorption, and the like. Therefore, since all the light emitted from the light source cannot be used for the photocatalytic reaction, the efficiency of the photocatalytic reaction is very poor.
For example, when this photocatalyst device is applied to sewage treatment, the photocatalyst device is immersed in sewage, so most of the light emitted from the light source is absorbed by the turbid colored sewage, and the surface of the photocatalyst is absorbed. Not reach. Therefore, the photocatalyst is not activated, and as a result, it is impossible to treat sewage.

  In order to solve such a problem, a long light guide made of glass, ceramics, plastic, or the like is used as a support for the photocatalyst, and a photocatalyst layer is provided on the outer peripheral surface of the light guide to A photocatalytic filter or a photocatalytic device that directly irradiates propagating light to a photocatalyst has been proposed (see, for example, Patent Document 1). In the photocatalytic filter disclosed in Patent Document 1, a photocatalytic layer having a high refractive index is provided on the outer peripheral surface of a light guide having a low refractive index, and light propagating through the light guide gradually leaks from the outer peripheral surface. Utilizes and activates the photocatalyst. In addition, since the photocatalytic filter can increase the contact area between the light guide and the photocatalyst by miniaturizing the light guide, the efficiency of the photocatalytic reaction can be increased.

However, the photocatalytic filter disclosed in Patent Document 1 has a drawback that the amount of light leaking from the light guide in the outer circumferential direction becomes non-uniform as the length increases.
In an optical fiber or the like, light leaks immediately from a low refractive index region to a high refractive index region. Similarly, in this photocatalytic filter, light propagating through a light guide having a low refractive index immediately leaks to the photocatalytic layer having a high refractive index, and when the length of the photocatalytic filter is long, light is transmitted to the end of the photocatalytic filter. As a result, the photocatalyst cannot be activated. For this reason, there is a problem that it is difficult to increase the length and area of the photocatalytic filter.

  A photocatalytic fiber in which a photocatalytic layer is provided on the outer peripheral surface of the optical fiber has also been proposed (see, for example, Patent Document 2). In this photocatalyst fiber, by bending it, light propagating through the optical fiber can be leaked from its outer peripheral surface, and the photocatalyst can be activated.

However, in this photocatalytic fiber, it is necessary to bend the optical fiber necessary for leaking light from the optical fiber, so that the mechanical strength of the optical fiber must be increased. Therefore, the manufacturing process of the photocatalytic fiber becomes complicated, and there is a problem that the manufacturing cost increases. Furthermore, in this photocatalyst fiber, most of the light leaks from the outer edge side when the optical fiber is bent, but since there is little light leaking from the inner edge side, only the photocatalyst arranged on the outer edge side is activated, so the photocatalytic reaction There is a problem of inefficiency.
JP 9-225262 A JP 2000-24513 A

  The present invention has been made in view of the above circumstances, and can be easily manufactured, can be made long and large in area, and has a surface leakage optical waveguide excellent in the efficiency of the photocatalytic reaction. An object of the present invention is to provide a photocatalytic device.

  In order to solve the above-mentioned problems, the present invention provides a surface light leakage optical waveguide comprising at least a core portion and a clad portion made of a material having a refractive index lower than that of the core portion and laminated so as to surround the core portion. The clad portion is configured to scatter or radiate light propagating in the core portion, and provides a surface leakage optical waveguide in which a photocatalyst is supported outside the clad portion.

  By forming the cladding portion of the surface light leakage optical waveguide to scatter or radiate the light propagating in the core portion, the light propagating in the core portion is scattered in the cladding portion. It is possible to leak in different directions (surface direction of the surface light leakage optical waveguide). As a result, the photocatalyst supported on the outer side of the clad portion can be activated.

  In the surface leakage optical waveguide having the above structure, the light is scattered or emitted by an additive or a bubble having a refractive index different from that of the cladding disposed in the cladding, and the additive and the bubble. It is preferable that the gas forming the gas does not absorb or hardly absorbs light in the operating wavelength band in which the reaction of the photocatalyst carried outside the cladding portion occurs.

Conventional optical waveguides that leak light by bending, such as optical fibers, usually have a smaller numerical aperture (NA), that is, the relative refractive index difference between the core portion and the clad portion in order to facilitate light leakage. Designed to be smaller. When this relative refractive index difference is small, there arises a problem that the light coupling efficiency at the junction between the optical waveguide and the light source is extremely lowered.
Therefore, in the present invention, an additive that has a refractive index different from that of the clad added in the clad part and does not absorb or hardly absorbs light in the operating wavelength band in which the reaction of the supported photocatalyst occurs (hereinafter referred to as “additive”). In other words, mode coupling occurs in the clad portion and light is scattered (leaked). Further, the amount of light leaking to the surface of the surface light leakage optical waveguide can be adjusted by changing the kind of additive, or the size and distribution density (addition amount) thereof. Therefore, since the relative refractive index difference between the core portion and the clad portion can be increased, the coupling efficiency between the surface light leakage optical waveguide of the present invention and the light source is improved.

  The surface light leakage optical waveguide is preferably a columnar optical waveguide, a ribbon optical waveguide, or a sheet optical waveguide. Further, it may be a columnar optical fiber.

  By making the surface light leakage optical waveguide into a columnar optical waveguide, ribbon optical waveguide or sheet optical waveguide, the surface light leakage optical waveguide can be selected according to the place to be purified and the amount of treatment (decomposition, removal) of contaminants or pathogens. You can change the size.

  In the surface light leakage optical waveguide having the above configuration, the photocatalyst is preferably made of at least one selected from titanium oxide, zinc oxide, tin oxide, strontium titanate, tungsten oxide, bismuth oxide, and iron oxide.

  Since these photocatalysts are highly active, they can be efficiently decomposed and removed regardless of the state of pollutants and pathogenic bacteria (gas, liquid, solid).

  In the surface light leakage optical waveguide having the above-described configuration, it is preferable that a waveguide lead portion for guiding light from an external light source is provided to the core portion on one end face of the surface light leakage optical waveguide.

  By providing the waveguide lead portion in the surface light leakage optical waveguide, when the distance between the place to be purified and the light source is long, light from the light source can be guided to the surface light leakage optical waveguide without loss.

  The present invention provides a photocatalytic device comprising at least the above-described surface light leakage optical waveguide and a light source for allowing light necessary for a photocatalytic reaction to enter the surface light leakage optical waveguide.

  The photocatalytic device using the surface light leakage optical waveguide of the present invention can efficiently decompose and remove these regardless of the state of contaminants and pathogenic bacteria (gas, liquid, solid).

  Since the surface light leakage optical waveguide of the present invention can scatter light propagating in the core portion by the additive added in the cladding portion, this light is spread over the entire length in the longitudinal direction of the surface light leakage optical waveguide. It can be gradually leaked in the surface direction. As a result, the photocatalyst supported on the outer side of the clad portion can be activated over the entire length in the longitudinal direction of the surface leakage optical waveguide. Therefore, since the entire surface on which the photocatalyst is supported becomes the photocatalytic reaction surface, contaminants and pathogens can be efficiently decomposed and removed. Furthermore, since the surface light leakage optical waveguide of the present invention can leak light from its surface regardless of deformation such as bending, it is easy to manufacture and can be made long and large in area.

  Hereinafter, a surface light leakage optical waveguide embodying the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a refractive index distribution in an optical fiber that is one of optical waveguides.
In FIG. 1, reference numeral 1 denotes a core, 2 denotes a clad, n ₀ denotes a refractive index of the clad 2, and n ₁ denotes a refractive index of the core 1.
As shown in FIG. 1, in an optical fiber comprising a core 1 and a clad 2 made of a material having a lower refractive index and covering the outer periphery of the core 1, the light incident on the core 1 Is totally reflected at the interface between the core 1 and the clad 2 and travels forward in the longitudinal direction of the optical fiber while propagating through the core 1.

FIG. 2 is a schematic view showing a cross section of an embodiment of the surface light leakage optical waveguide according to the present invention.
In FIG. 2, reference numeral 10 denotes a surface leakage optical waveguide, 11 denotes a core part, 12 denotes a cladding part, 13 denotes a mode coupling part, 14 denotes an optical waveguide, and 15 denotes a photocatalytic film.
The surface light leakage optical waveguide 10 is made of a core part 11, a clad part 12, 12 that is made of a material having a lower refractive index than the core part 11, and laminated so as to sandwich the core part 11, and the clad parts 12, 12. An optical waveguide 14 composed of an additive or a bubble (hereinafter referred to as a “mode coupling portion”) 13 that scatters or emits light propagating in the core portion 11, and the surfaces of the cladding portions 12 and 12. A photocatalyst film 15 made of a photocatalyst carried on the entire area is roughly constituted.

  In addition, this embodiment can be applied to all optical waveguides such as a columnar shape, a sheet shape, and a ribbon shape as the optical waveguide 14.

  The material forming the core portion 11 is not particularly limited, and a material that does not absorb light in the wavelength range of light propagating through the core portion 11 is desirable. For example, synthetic resin such as polymethyl methacrylate and fluorine resin, quartz Glass or the like is used. Among these materials, a synthetic resin is more preferable because it is resistant to bending and is difficult to break.

  The material forming the cladding portion 12 is not particularly limited, but a material having a refractive index lower than that of the core portion 11, not decomposed by the photocatalytic action, and having no absorption in the wavelength region of light propagating in the core portion 11. Desirably, for example, synthetic resin such as polymethyl methacrylate and fluorine resin, quartz glass, and the like are used. Among these materials, a fluorine-based resin that is resistant to bending, hardly breaks, has a low refractive index, and is difficult to be decomposed by a photocatalyst is more desirable.

The relative refractive index difference between the core portion 11 and the cladding portion 12 is preferably 0.002 or more and 0.2 or less, and more preferably 0.01 or more and 0.15 or less.
If the relative refractive index difference is less than 0.002, the numerical aperture (NA) of the optical waveguide 14 is small, and it is not desirable because the joining efficiency becomes small when joining the incident side and the light source.
On the other hand, when the non-refractive index difference exceeds 0.2, the numerical aperture (NA) of the optical waveguide 14 is too large, and the light confinement action is strong. As a result, the degree of light leakage decreases, and the optical waveguide Insufficient light leakage to the surface of 14 makes it impossible to cause a photocatalytic reaction.

  A large number of mode coupling portions 13 are provided in the cladding portions 12 and 12 locally or in the entire region. Here, the mode coupling portion 13 being locally provided means that the mode coupling portion 13 is localized in the clad portion 12 in a band shape or a lump (island) shape.

When it is desired to scatter (leak) light substantially uniformly in the direction of the surface 14 a of the optical waveguide 14, it is preferable to provide the mode coupling portion 13 uniformly in the cladding 12.
In addition, if it is desired to locally leak light on the surface of the optical waveguide 14 based on the same principle, the mode coupling portion 13 may be locally provided in the cladding 12.

Here, the principle that light can be leaked by providing a mode coupling portion at the interface between the core and the clad will be described.
As shown in FIG. 3, in this optical waveguide 20, a mode coupling portion 23 having a refractive index different from that of the cladding portion 22 is provided at the boundary between the core portion 21 and the cladding portion 22. The optical waveguide 20 has a refractive index distribution as shown in FIG. 1, and the waveguide principle uses total reflection. In FIG. 3, the arrows indicate the propagation (scattering) direction of light.
At the interface between the core portion 21 and the cladding portion 22, the light 27 that should be totally reflected hits the mode coupling portion 23, and a light beam partially exceeding the critical angle of total reflection is generated, and is emitted (scattered) to the cladding portion 22. Or Further, the light beam propagating in the core unit 21 strikes the mode coupling unit 23 and the propagation condition is changed, and the mode is converted. Among the light beams whose modes have changed, modes that do not meet the propagation conditions (most high-order modes) are also radiated to the cladding portion 22 and become light leakage.

The light scattered and radiated on the cladding part 22 leaks to the surface (outer periphery) of the optical waveguide 20 while being reflected by the mode coupling part 23, hits the outer photocatalyst, and causes a photocatalytic reaction.
Moreover, if the number of mode coupling parts 23 per unit volume increases, light scattering and radiation will increase.

  The mode coupling portion 13 is made of an additive having a refractive index different from that of the clad disposed in the clad portion 12, and does not absorb or hardly absorbs light in the operating wavelength band where the supported photocatalyst reacts. It is preferable.

  When the mode coupling unit 13 is formed of bubbles, the gas forming the bubbles is not particularly limited, and for example, air, argon gas, nitrogen, helium, or the like is used.

By changing the type of gas forming the bubbles (refractive index of the additive), the size of the bubbles (particle size as additive), and the number of bubbles per unit volume (hereinafter referred to as “distribution density”). The amount of light leakage from the optical waveguide 14 can be adjusted.
The size and distribution density of the bubbles are not particularly limited, but basically, the lower the refractive index of the bubbles, the lower the refractive index of the entire cladding portion 12 and the larger the numerical aperture (NA). The coupling efficiency is improved.

  The bubble particle size may be selected according to the operating wavelength band in which the photocatalytic reaction occurs. For example, when the wavelength to be leaked is 365 nm with ultraviolet rays, the bubble diameter may be about 30 nm to 3 μm based on the principle of scattering.

  Furthermore, with regard to the distribution density of bubbles, basically, if the distribution of bubbles is uniform and the distribution density is small, incident light can be gradually leaked in small amounts, so the optical waveguide should be lengthened. However, the ratio of light leakage per unit length is small. On the other hand, when the distribution is uniform and the distribution density is large, a large amount of incident light is leaked, and the ratio of the amount of light leaked per unit length is large (the photocatalytic reaction capacity per unit length is strong). Cannot be lengthened. Therefore, the distribution density of the bubbles is not particularly limited because it can be adjusted according to the dimensions and reaction capacity required for the optical waveguide.

No particular limitation is imposed on the additives, such as silicon dioxide (SiO _2), zirconium oxide (ZrO _2), or particles made of acrylic resin or silicone resin is hardly absorbed not occur in the ultraviolet wavelength region is used. Among these, particles made of silicon dioxide, acrylic resin, silicon resin or the like that do not absorb ultraviolet rays are preferable.

Here, for example, a case where zirconium oxide is used as an additive will be described.
Zirconium oxide is short-wave ultraviolet light having a band gap of 5.0 eV and an absorption spectrum of about 248 nm or less. The photocatalyst titanium oxide (TiO ₂ ) is a short wavelength ultraviolet ray having a band gap of 3.0 eV and an absorption spectrum of about 385 nm or less.
Therefore, mercury (Hg) -xenon that emits light with a wavelength of 365 nm or a wavelength of around 310 nm as a light source on the end face of the optical waveguide in which zirconium oxide is added to the cladding portion and a photocatalyst made of titanium oxide is supported on the surface of the cladding portion. Xe) Consider a case where a lamp is connected and light enters the optical waveguide from this lamp. Since zirconium oxide scatters light without absorbing light having a wavelength of 365 nm or near 310 nm, the optical waveguide can leak light of this wavelength in a direction different from the longitudinal direction. Thereby, the photocatalytic function of the titanium oxide supported on the surface of the cladding part is activated.

The amount of light leaking from the optical waveguide 14 can be adjusted by changing the type of additive (refractive index of the additive), particle size, and distribution density.
Although these parameters are not particularly limited, basically, the lower the refractive index of the additive, the lower the refractive index of the entire cladding portion 11, the larger the numerical aperture (NA), and the coupling efficiency with the light source. Will improve.
Moreover, the particle diameter of the additive may be selected as the optimum particle diameter depending on the operating wavelength band in which the photocatalytic reaction occurs. For example, when the light to be leaked is ultraviolet light having a wavelength of 365 nm, the particle size of the additive may be about 30 nm to 3 μm based on the principle of scattering.
Furthermore, with regard to the distribution density of the additive, basically, if the distribution of the additive is uniform and the distribution density is small, the incident light can be gradually leaked in a small amount, so the optical waveguide is lengthened. However, the ratio of the amount of leakage light per unit length is small. On the other hand, when the distribution is uniform and the distribution density is large, a large amount of incident light is leaked, and the ratio of the amount of leakage light per unit length is large (the photocatalytic reaction capacity per unit length is strong), but the optical waveguide Cannot be lengthened. Therefore, the distribution density of the additive is not particularly limited because it can be adjusted according to the dimensions and reaction capacity required for the optical waveguide.

Here, FIG. 4 is a graph showing changes in the amount of leaked light when the type, particle size, and distribution density of the scatterers (additives) in the surface light leakage optical waveguide are changed.
A columnar optical fiber was used as the optical waveguide. In addition, the distribution density is indicated by number / cm ³ in the case of bubbles, and is a ratio with respect to the total solid content after resin drying in the case of other additives. The particle size is the average particle size of the additive.

This columnar optical fiber is obtained by the following method.
Pure quartz is prepared as a core material, and the clad can be produced by an ordinary spinning machine and by an ordinary spinning process. The core quartz base material is melted in a sintering furnace, drawn from the lower end, and wound up to a bobbin through a spinning pass line. In the meantime, there are two coating devices. Conventionally, it coats two layers of resin, but various additives are uniformly dispersed in the first layer coating device to produce this columnar optical fiber. Then, a fluororesin dissolved in an organic solvent having a lower refractive index than that of the ultraviolet transmission type quartz is put, and the first layer clad containing the additive is coated on the outer periphery of the quartz core while drawing. Then, it is dried by heating through the cross-linking cylinder of the coating apparatus. The obtained columnar optical fiber may be used as a light leakage fiber as it is. However, since the core material is glass, in order to improve the mechanical strength, the ultraviolet transmission type quartz without the additive is further added. A fluororesin dissolved in an organic solvent having a lower refractive index was placed in the second layer coating apparatus, and the second layer resin (cladding) was thickened while spinning. The mechanical strength of the resulting fiber was similar to that of normal fiber.
Then, the obtained various fibers were incident with an ultraviolet light source (mercury-xenon lamp), and the transmission loss was measured by the cutback method. It was found that the amount of light at the emission end gradually decreased by adding the additive, that is, gradually leaked while propagating light. Furthermore, it has been found that the amount of light leakage can be adjusted by the type, particle size and distribution density of the additive.

No particular limitation is imposed on the photocatalyst constituting the photocatalyst film 15, for example, titanium oxide _(TiO 2), zinc oxide (ZnO), tin oxide _(SnO 2), strontium titanate (SrTiO _3), tungsten oxide _(WO 3), Bismuth oxide (Bi ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ), or the like is used. These photocatalysts may be used alone or in combination of two or more.

  Among the above photocatalysts, titanium oxide can be used as a highly active photocatalyst. In particular, for the purpose of decomposing and removing pollutants, anatase-type titanium oxide is desirable, but rutile-type titanium oxide can also be used depending on the application.

When the surface light leakage optical waveguide 10 in FIG. 2 is a ribbon-shaped optical waveguide, a known method for manufacturing a laminated sheet can be applied to manufacture the optical waveguide.
For example, a resin sheet A that forms the core portion 11 and a resin sheet B that is made of a material having a lower refractive index than that of the resin sheet A and to which the clad portions 12 and 12 are formed are prepared.
Next, the resin sheet A is sandwiched between the resin sheets B, and heat is applied and pressed in this state to obtain a sheet-like laminate in which the resin sheets A and B are laminated.

Next, the sheet-like laminate is cut into a predetermined width, whereby a core part 11, clad parts 12 and 12 laminated so as to sandwich the core part 11, and a mode coupling part 13 made of an additive are formed. A ribbon-shaped optical waveguide 14 having the above-described structure is obtained.
Alternatively, the resin sheet C that forms the thick core portion 11 and the resin sheet D that forms the thick clad portion 12 are preliminarily overlapped, and heat is applied to the resin sheet C so that the thickness is reduced. A large number of ribbon-shaped optical waveguides 14 can be manufactured at a time.

Next, the photocatalyst is supported on the entire surface of the two cladding portions 12 and 12 to form the photocatalyst film 15, and the surface leakage light waveguide 10 is obtained. Alternatively, a protective layer such as silicon may be applied to the surface of the clad portion 12 and then a photocatalyst may be applied thereon.
The method for supporting the photocatalyst on the surfaces of the cladding portions 12 and 12 is not particularly limited. For example, photocatalyst particles such as titanium oxide are mixed with an inorganic binder such as low-melting glass, and this mixture is applied to the surfaces of the clad parts 12 and 12 and dried to thereby form photocatalysts on the surfaces of the clad parts 12 and 12. Can be supported. Moreover, after apply | coating to the surface of the clad parts 12 and 12 of a photocatalyst, a chemical reaction is caused on the surface of the clad parts 12 and 12, and a photocatalyst can also be carry | supported.

  In this embodiment, as the optical waveguide 14, the optical waveguide may be a wide sheet-shaped optical waveguide, a plate-shaped optical waveguide, or a columnar fiber.

In the case where the surface light leakage optical waveguide is a columnar fiber, the method described in paragraph [0043] can be applied to manufacture this.
Also, keep the core material with the usual spinning method, coat the resin with a refractive index lower than that of the core to make a fiber, then cut it to the required length, remove the coating of the part you want to leak light, and add What is necessary is just to disperse | distribute a thing uniformly, to immerse in the fluororesin melt | dissolved in the organic solvent whose refractive index is lower than a core, apply | coat the resin which makes a clad to a core material with a dipping method, and just heat and dry. In the case of using an ultraviolet curable fluororesin, the fluororesin may be cured by irradiation with ultraviolet light.

  Moreover, in this embodiment, although the mode coupling part 13 illustrated the form provided in both the clad parts 12 and 12 of the optical waveguide 14, this invention is not limited to this. In the present invention, when the optical waveguide is in a ribbon shape, a sheet shape, or a flat plate shape, the additive may be provided in any one of at least two clad portions. Further, when the optical waveguide is a columnar fiber, the mode coupling portion may be provided at the interface between the core and the clad or the entire clad.

  Moreover, in this embodiment, although the photocatalyst film | membrane 15 which consists of photocatalysts was provided in the whole region on the surface of the clad parts 12 and 12, this invention is not limited to this. In the present invention, when the optical waveguide is in a ribbon shape, a sheet shape, or a flat plate shape, it is sufficient that the photocatalyst is supported locally or entirely on the surface of the clad portion provided with at least the mode coupling portion 13. Further, when the optical waveguide is a columnar fiber, the photocatalyst may be supported locally or entirely on the outer peripheral surface of the cladding.

Thus, the surface light leakage optical waveguide 10 has a photocatalytic function because the photocatalytic film 15 is provided on the surfaces of the cladding portions 12 and 12.
In order to purify the gas or liquid using the surface light leakage optical waveguide 10, the surface light leakage optical waveguide 10 is disposed at a place where it is desired to be purified, and light is propagated into the core portion 11. Then, light propagating in the core portion 11 is scattered by the mode coupling portion 13 and leaks from the surface of the optical waveguide 14, and the photocatalytic film 15 is activated by the leaked light. When a liquid or gas comes into contact with the photocatalyst film 15, the liquid or gas is purified by decomposing, removing, or sterilizing contaminants (for example, bacteria, organic contamination, dust, etc.) contained in the liquid or gas. Is done. Therefore, it is possible to decompose, remove or sterilize contaminants contained in gas or liquid even in a dark place where light does not reach.

  Further, in order to increase the processing speed for decomposing, removing or sterilizing contaminants, a plurality of surface leakage light waveguides 10 may be used simultaneously. For example, if a large number of surface light leakage optical waveguides 10 are converged, and both ends thereof are bonded and polished to form a bundle, light can be incident on all the surface light leakage optical waveguides 10 from one light source. Furthermore, if the surface light leakage optical waveguide 10 is bundled, the arrangement of the surface light leakage optical waveguide 10 is facilitated, so that the processing efficiency of contaminants is improved.

  Further, when the distance between the place to be purified and the light source separate from the surface light leakage optical waveguide 10 is long, the light from the light source is guided to the core portion 11 to one end surface (not shown) of the surface light leakage optical waveguide 10. A waveguide lead portion (not shown) may be provided, and the surface light leakage optical waveguide 10 and the light source may be connected via the waveguide lead portion. In this case, the waveguide lead portion preferably has a structure capable of confining the light incident from the light source without leaking and guiding the light to the core portion 11 of the surface light leakage optical waveguide 10. That is, the waveguide lead portion is preferably an optical fiber or an optical waveguide having no additive in the cladding portion as described above.

  When the distance between the place to be purified and the light source is short, the surface light leakage optical waveguide and the light source may be directly connected.

FIG. 5 is a schematic view showing an embodiment of a photocatalytic device according to the present invention.
In FIG. 5, reference numeral 30 denotes a surface light leakage optical waveguide, 31 denotes a waveguide lead portion, 32 denotes a light incident jig, 33 denotes a light guide, and 34 denotes a light source.
The photocatalytic device of this embodiment is generally configured by a surface light leakage optical waveguide 30, a waveguide lead portion 31, a light incident jig 32, a light guide 33, and a light source 34.

  In the photocatalytic device of this embodiment, a waveguide lead portion 31 for guiding light from the light source 34 to the core portion of the surface light leakage optical waveguide 30 is provided on one end surface of the surface light leakage optical waveguide 30. A light incident jig 32 for making light from the light source incident on the waveguide lead 31 is attached to the end face of the waveguide lead 31 that is not connected to the surface leakage light waveguide 30. Furthermore, one end surface of the light guide 33 extended from the light source 34 is connected to the end surface of the light incident jig 32 that is not attached to the waveguide lead portion 31.

  As the surface light leakage optical waveguide 30, the surface light leakage optical waveguide of the present invention as described above is used.

As described above, as the waveguide lead portion 31, the light emitted from the light source 34 and incident through the light incident jig 32 and the light guide 33 is confined without leaking, and the waveguide lead portion 31 is confined in the core portion of the surface light leakage optical waveguide 30. Those having a structure capable of being guided are used. That is, for example, when the surface light leakage optical waveguide is a columnar optical fiber manufactured by the method described in the paragraph [0043], the additive is not added at all in the same manner. If no resin is used as the cladding, an optical fiber with very low transmission loss can be obtained without causing scattering loss and mode coupling. At that time, the optical fiber may be cut into a required length, and the leakage optical fiber may be connected by a normal fiber connection method.
Moreover, the light leakage part can be simultaneously formed in one step as the lead part by the dipping method described in [0050]. For example, usually, only the core material is made into a fiber without coating by the spinning method, and then the necessary length is cut and immersed only in the resin dissolved in the organic solvent containing the additive, and the resin is removed by the dipping method. After coating as a clad, heat and dry. Then, the portion where the resin clad containing the additive is formed becomes a light leakage portion according to the above-mentioned principle, but the portion that is not covered at all becomes air clad, and there is no loss. Nearly 100% of incident light can be transmitted. That is, the portion not covered at all is a waveguide lead portion.

  The material of the light incident jig 32 is not particularly limited, and any material such as a metal (for example, aluminum, brass) or a resin such as polytetrafluoroethylene can be used. Further, the shape is not particularly limited, and any shape such as a tube shape or a box shape may be used.

  The light guide 33 may not be used, but a normal large-diameter transmission is used in order to narrow down the light beam emitted from the light source 34 in order to match the size of the surface light leakage optical waveguide or the waveguide lead 31. An optical fiber or a lens is used.

  As the light source 34, for example, a normal high-pressure mercury-xenon lamp, a light emitting diode (LED), or the like is used. Further, when the surface light leakage optical waveguide 30 supporting a photocatalyst activated by visible light (visible light active photocatalyst) is used, various visible light sources (such as an indoor lamp) can be used as the light source 34. Further, sunlight may be used as a light source instead of the light source 34.

  In this embodiment, the form in which the waveguide lead portion 31 is provided on the one end face of the surface light leakage optical waveguide 30 is illustrated, but the present invention is not limited to this. In the present invention, when the distance between the place to be purified and the light source is short, the light incident jig and the surface light leakage optical waveguide may be directly connected without providing the waveguide lead portion.

  In order to purify a gas or a liquid using this photocatalytic device, the surface light leakage optical waveguide 30 is disposed at a place where it is desired to purify, and light emitted from the light source 34 enters the surface light leakage optical waveguide 30 and propagates therethrough. . Then, the light propagating in the surface light leakage optical waveguide 30 is scattered or radiated by the additive disposed in the cladding portion of the surface light leakage optical waveguide 30 (light leakage), and the photocatalyst is activated by this light leakage. Shows the effect.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

(Example 1)
The core material is pure quartz, and the clad is manufactured by a normal spinning machine by a normal spinning process.
The core quartz base material is melted in a sintering furnace, drawn from the lower end, and wound up to a spinning pass line. In between, there are two coating devices. Conventionally, two layers of resin are coated with this, and in order to produce this light leakage fiber, the SiO ₂ additive (average particle size 300 nm, relative concentration of resin solid content 5 wt%) is contained in the first layer coating apparatus. Is added to the outer periphery of the core while adding a fluororesin (refractive index of 1.37) dissolved in ethyl acetate having a lower refractive index than that of ultraviolet transmission type quartz. Coating. Then, it is dried by crosslinking and heating through a crosslinking cylinder of a coating apparatus. It can be used as a fiber as it is, but since the core material is glass, it is then dissolved in ethyl acetate, which has a lower refractive index than the above-mentioned ultraviolet transmission type quartz without additives, in order to improve the mechanical strength. The obtained fluororesin was put into a second layer coating device, and the second layer clad was thickened while spinning. The mechanical strength of the obtained fiber was almost the same as that of the normal fiber. Table 1 shows the characteristics of this fiber.

  Thereafter, this fiber was cut to prepare 50 fibers having a length of 2.5 m. Next, one side was converged, and this part was bonded with an adhesive, and then polished to form a bundle.

  Next, a commercially available titanium oxide slurry for photocatalyst application was applied to the outer peripheral surface of the bundled fiber. The fiber coated with the titanium oxide slurry was dried and then dried to obtain a surface leakage optical waveguide in which the outer peripheral surface of the fiber was coated with a titanium oxide film having photocatalytic activity. The thickness of the obtained titanium oxide film was about 1 μm. The characteristics of the obtained surface light leakage optical waveguide are also shown in Table 1.

Using this surface leakage optical waveguide, a methylene blue decomposition experiment was conducted.
FIG. 6 is a schematic diagram showing a methylene blue decomposition experiment apparatus.

Two liters of a methylene blue solution 52 having a methylene blue concentration adjusted to about 10 micromol / liter was injected into a completely light-shielded container 51. Near the center of the container 51, a surface light leakage optical waveguide 40 in which 50 fibers coated with a titanium oxide film are bundled to form a bundle is disposed. A waveguide lead 41 was provided by connecting to one end face of the surface light leakage optical waveguide 40, and the waveguide lead 41 was led out of the container 51 from an insertion hole (not shown) provided in the container 51. A light incident jig 42 was attached to the end face of the waveguide lead 41 that is not connected to the surface leakage light waveguide 40. One end face of the light guide 43 extended from the ultraviolet light source 44 having a wavelength of 365 nm was connected to the end face of the light incident jig 42 not attached to the waveguide lead portion 41.
As the ultraviolet light source 44, a mercury-xenon lamp (illuminance 2000 mW / cm ² ) was used.
The spectral translucency of the methylene blue solution 52 in the container 51 was measured every predetermined time, and the progress of methylene blue decomposition was examined. The experimental results are shown in FIG.

  The measurement result of the spectral transmissivity shows that the higher the solution transmittance (%), the lower the methylene blue concentration in the methylene blue solution 52 is. Therefore, from the results of FIG. 7, it was confirmed that the decomposition of methylene blue was progressing because the solution permeability (%) increased with the passage of time.

(Example 2)
In the same manner as in Example 1, a surface leakage optical fiber with an outer diameter of 250 μm added with an acrylic additive (average particle diameter 300 nm, relative concentration of resin solid content 0.5 wt%) was produced. Thereafter, the surface leakage optical fiber was cut to prepare 50 fibers having a length of 2.5 m. Next, one side was converged, and this part was bonded with an adhesive, and then polished to form a bundle.

  Next, a commercially available titanium oxide slurry for photocatalyst application was applied to the outer peripheral surface of each optical fiber. The optical fiber coated with the titanium oxide slurry was dried to obtain a surface leakage optical waveguide coated with a titanium oxide film having photocatalytic activity. The thickness of the obtained titanium oxide film was about 1 μm. Table 2 also shows the characteristics of the obtained surface light leakage optical waveguide.

Using this surface light leakage optical waveguide, a methylene blue decomposition experiment was conducted in the same manner as in Example 1. The experimental results are shown in FIG.
From the results of FIG. 8, it was confirmed that the decomposition of methylene blue was progressing because the solution permeability (%) increased with the passage of time.

(Example 3)
In the same manner as in Example 1, a surface leakage optical fiber having an outer diameter of 250 μm added with an acrylic additive (average particle diameter of 100 nm, relative concentration of resin solid content of 0.3 wt%) was produced. Thereafter, the surface leakage optical fiber was cut to prepare 50 fibers having a length of 2.5 m. Next, one side was converged, and this part was bonded with an adhesive, and then polished to form a bundle.

  Next, a commercially available titanium oxide slurry for photocatalyst application was applied to the outer peripheral surface of each optical fiber. The optical fiber coated with the titanium oxide slurry was dried to obtain a surface leakage optical waveguide coated with a titanium oxide film having photocatalytic activity. The thickness of the obtained titanium oxide film was about 1 μm. Table 3 also shows the characteristics of the obtained surface light leakage optical waveguide.

Using this surface light leakage optical waveguide, a methylene blue decomposition experiment was conducted in the same manner as in Example 1. The experimental results are shown in FIG.
From the results in FIG. 9, it was confirmed that the decomposition of methylene blue was progressing because the solution permeability (%) increased with the passage of time.

Example 4
50 commercially available acrylic fibers having a length of 3 m were prepared. Thereafter, 0.5 m on one side was converged and fixed as a waveguide lead portion. In addition, 2.5 m of these fibers are made of acetic acid having a refractive index lower than that of ultraviolet transmission acrylic in which SiO ₂ additive (average particle size 300 nm, relative concentration of resin solids 5 wt%) is uniformly dispersed. A fluororesin (refractive index: 1.37) dissolved in ethyl was added, and the resin was coated as a clad by the dipping method, and then heated and dried. Next, the portion that converged on one side was bonded with an adhesive, and then polished to form a bundle.

  Subsequently, a commercially available titanium oxide slurry for photocatalyst application was applied to the outer peripheral surface of the fluororesin containing an additive for each optical fiber. The optical fiber coated with the titanium oxide slurry was dried to obtain a surface leakage optical waveguide coated with a titanium oxide film having photocatalytic activity. The thickness of the obtained titanium oxide film was about 1 μm. Table 4 also shows the characteristics of the obtained surface light leakage optical waveguide.

Using this surface leakage optical waveguide, a methylene blue decomposition experiment was conducted in the same manner as in Example 1 except that a high-pressure mercury-xenon lamp (illuminance 3500 mW / cm ² , main wavelengths 360 nm and 310 nm) was used as an ultraviolet light source. It was. The result of this experiment is shown in FIG.
From the results of FIG. 10, it was confirmed that the decomposition of methylene blue was progressing because the solution permeability (%) increased with the passage of time.

(Example 5)
In the same manner as in Example 2, a surface leakage optical fiber having an outer diameter of 250 μm added with an acrylic additive (average particle diameter 100 nm, relative concentration of resin solid content 0.3 wt%) was produced. Thereafter, the surface leakage optical fiber was cut to prepare 100 pieces having a length of 2.5 m. Next, the portion that converged on one side was bonded with an adhesive, and then polished to form a bundle. Next, a commercially available titanium oxide slurry for photocatalyst application was applied to the outer peripheral surface of each optical fiber. The optical fiber coated with the titanium oxide slurry was dried to obtain a surface leakage optical waveguide coated with a titanium oxide film having photocatalytic activity. The thickness of the obtained titanium oxide film was about 1 μm.

  A photocatalyst module as shown in FIG. 11 was produced using the obtained bundle fiber. In FIG. 11, 61 is a power source, 62 is an ultraviolet light source similar to that of Example 1, 63 is a flexible tube, 64 is a photocatalyst-coated fiber, 65 is a fiber bundle, 66 is a polytetrafluoroethylene tube, and 67 is an object to be decomposed. An inlet for gas (here, acetaldehyde), 68 indicates an outlet for the gas to be decomposed.

Next, an acetaldehyde decomposition experiment was performed in a completely sealed and light-shielded state. Acetaldehyde with an initial concentration of 100 ppm was circulated from the inlet 66 and outlet 67 at a volume of 2 liters and a flow rate of 20 cc / min, and the concentration of acetaldehyde was measured by gas chromatography at each elapsed time. The experimental results are shown in FIG.
From the results of FIG. 12, it was confirmed that the decomposition proceeded because the concentration of residual acetaldehyde decreased with the passage of time.

(Example 6)
In the same manner as in Example 5, a surface leakage optical fiber with an outer diameter of 250 μm added with an acrylic additive (average particle diameter of 100 nm, relative concentration of resin solid content of 0.3 wt%) was produced. Thereafter, the surface leakage optical fiber was cut to prepare 50 fibers having a length of 2.5 m. Next, the portion that converged on one side was bonded with an adhesive, and then polished to form a bundle.

Next, using the obtained bundle fiber, a sheet-type photocatalytic device as shown in FIG. 13 was produced. In FIG. 13, 71 is the same ultraviolet light source as in Example 1, 72 is a fiber, 73 is a transparent resin sheet, and 74 is a photocatalytic film.
Next, a commercially available titanium oxide slurry for photocatalyst application was applied to the surface of the transparent resin sheet. The titanium oxide slurry was dried and then sintered to obtain a surface leakage light photocatalytic device coated with a titanium oxide film having photocatalytic activity. The thickness of the obtained titanium oxide film was about 1 μm.

Next, this surface light-splitting photocatalytic device was placed in a completely sealed and light-shielded volume of 2 liters, and an acetaldehyde decomposition experiment was conducted. Acetaldehyde having an initial concentration of 100 ppm was placed in a container, and the concentration of acetaldehyde was measured by gas chromatography at each elapsed time. The experimental results are shown in FIG.
From the results shown in FIG. 14, it was confirmed that the decomposition proceeded because the concentration of residual acetaldehyde in the container decreased with time.

  The surface light leakage optical waveguide of the present invention can also be applied to a photocatalytic device using light outside the ultraviolet region such as visible light.

It is a figure which shows the refractive index distribution in an optical fiber. It is a schematic diagram which shows the cross section of one Embodiment of the surface light leakage optical waveguide which concerns on this invention. In the surface light leakage optical waveguide according to the present invention, FIG. It is a graph which shows the result of having measured the light quantity of leakage when the magnitude | size and distribution density of the additive in a surface light leakage optical waveguide are changed. It is a mimetic diagram showing one embodiment of a photocatalyst device concerning the present invention. It is a schematic diagram which shows the decomposition | disassembly experiment apparatus of methylene blue. 4 is a graph showing the results of spectral transmittance measurement of a methylene blue solution in Example 1. It is a graph which shows the result of the spectral transmissivity measurement of the methylene blue solution in Example 2. 6 is a graph showing the results of spectral transmittance measurement of a methylene blue solution in Example 3. It is a graph which shows the result of the spectral transmissivity measurement of the methylene blue solution in Example 4. It is a schematic diagram which shows the decomposition | disassembly experiment apparatus of acetaldehyde. It is a graph which shows the result of the decomposition experiment of acetaldehyde in Example 5. It is a schematic diagram which shows the decomposition | disassembly experiment apparatus of acetaldehyde. It is a graph which shows the result of the decomposition | disassembly experiment of the acetaldehyde in Example 6. FIG.

Explanation of symbols

10, 20, 30, 40 ... surface leakage optical waveguide, 11, 21 ... core portion, 12, 22 ... cladding portion, 13 ... mode coupling portion, 14 ... optical waveguide, 15, 74 ... Photocatalyst film 31, 41 ... Waveguide lead part, 32, 42 ... Light incident jig, 23 ... Additive, 33, 43 ... Light guide, 34 ... Light source, 44, 62, 71 ... UV light source, 51 ... container, 52 ... methylene blue solution, 61 ... power supply, 63 ... flexible tube, 64 ... photocatalyst coated fiber, 65 ... fiber Bundle, 66 ... tube, 67 ... inlet, 68 ... outlet, 72 ... fiber, 73 ... transparent resin sheet.

Claims (7)

A surface light leakage optical waveguide comprising at least a core part and a clad part made of a material having a lower refractive index than the core part and laminated so as to surround the core part,
The surface leakage light waveguide according to claim 1, wherein the clad portion is configured to scatter or emit light propagating in the core portion, and a photocatalyst is supported outside the clad portion.   The light is scattered or emitted by an additive or bubbles having a refractive index different from that of the cladding disposed in the cladding, and the additive and the gas forming the bubbles are in the cladding. 2. The surface light leakage optical waveguide according to claim 1, wherein light in an operating wavelength band in which a reaction of a photocatalyst supported on the outside occurs is hardly or hardly absorbed.   The surface light leakage optical waveguide according to claim 1, wherein the surface light leakage optical waveguide is a columnar optical waveguide, a ribbon optical waveguide, or a sheet optical waveguide.   The surface light leakage optical waveguide according to claim 1, wherein the surface light leakage optical waveguide is a columnar optical fiber.   5. The photocatalyst comprises at least one selected from titanium oxide, zinc oxide, tin oxide, strontium titanate, tungsten oxide, bismuth oxide, and iron oxide. The surface leakage light waveguide according to claim.   6. The surface light leakage light guide according to claim 1, wherein a waveguide lead portion that guides light from an external light source to the core portion is provided on one end face of the surface light leakage optical waveguide. Waveguide. 7. A photocatalytic device comprising at least the surface light leakage optical waveguide according to any one of claims 1 to 6 and a light source for entering light necessary for a photocatalytic reaction into the surface light leakage optical waveguide.

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