JPH0975633A - Filter product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the peel resistance of a surface layer containing photocatalyst particles useful for the decomposition of a malodor component by forming a hydrophilic surface layer containing photocatalyst particles on the surface of a wire material being the material of a filter through the protective layer protecting the wire material from the redox reaction by a photocatalyst. SOLUTION: In a filter product such as a screen door, the filter of an air conditioner or a sieve, for example, in the screen door, longitudinal and lateral wire materials 3 are provided in a frame member under tension. A protective layer 4 constituted, for example, of an aluminum vapor deposition layer or a layer containing aluminum particles is provided on the surfaces of the wire materials 3 to protect the wire materials from the redox reaction by a photocatalyst. A hydrophilic surface layer 5 containing photocatalyst particles is formed on the protective layer 4. When the wire materials are composed of a resin, photocatalyst particles 6 are added to the interiors of the wire materials 3 and the protective film 7 is formed on the surfaces of the photocatalyst particles 6 to protect the wire materials 3 from redox reaction. In this case, the wire materials 3 are etched to expose the photocatalyst particles 6 to the open air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter product such as a screen door, an air conditioner filter, a sieve, etc., which allows air and the like to flow through a gap formed between wires.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 3-106420 proposes a deodorizing method in which a titanium oxide film is formed on a reticulated structure and the titanium oxide film is irradiated with ultraviolet rays to decompose offensive odor components.

The above-mentioned prior art focuses on the decomposition action of photocatalyst particles (optical semiconductors). That is, the decomposition action of the photocatalyst particles is based on an oxidation-reduction reaction, and when the photocatalyst particles are irradiated with ultraviolet rays or the like, an electron-hole pair is generated by photoexcitation, and among these electrons, the surface oxygen is reduced and the superoxide ion ( O ₂ ⁻ ) is generated, and the holes oxidize the surface hydroxyl groups to generate hydroxyl radicals (· OH). By the redox reaction of these extremely reactive active species (O ₂ ⁻ and · OH). It is to decompose the malodorous components and the like adhering to the surface.

On the other hand, the present inventors have recently newly found that the photocatalyst has a hydrophilizing action. Although the theoretical basis for the hydrophilization action of photocatalyst particles has not been completely clarified, hydroxyl groups (OH ⁻ ) are chemically adsorbed on the surface of photocatalyst particles by the photocatalytic effect, or hydroxyl groups (OH ⁻ ) are replaced with organic groups. Furthermore, it is considered that the water molecules in the air are physically adsorbed on the hydroxyl group (OH ⁻ ), and the hydrophilicity of the surface is increased by increasing the physically adsorbed water, so that a superhydrophilic surface is realized.

As a specific example, the case where the surface layer is made of a silicone resin having a Si--O bond will be described. Before the photocatalyst particles are irradiated with light, as shown in FIG.
Since the alkyl group (R) is bonded to the atom, the surface layer exhibits hydrophobicity. However, when the surface layer is irradiated with light having an energy higher than the band gap energy of the photocatalyst particles, as shown in FIG. the substitution (chemisorption), further the hydroxyl group - ^(OH) alkyl group (R) is a hydroxyl group by photocatalytic effect - exhibit hydrophilic water molecules in the air are physically adsorbed ^(OH).

Further, titanium oxide (Ti
Explaining the case of only O ₂ ), the state shown in FIG. 2A before the irradiation with light was changed to the state shown in FIG. 2B when irradiated with the light, as shown in FIG. 2B. The hydroxyl group (OH ⁻ ) constituting the compound is chemically adsorbed to the T ⁱ atom, and the hydrogen atom (H ⁺ ) is chemically adsorbed to the oxygen atom (O), and the hydroxyl group (OH ⁻ ) and the hydrogen atom (H ⁺ ) are water in the air. The molecule physically adsorbs and exhibits hydrophilicity.

[0007] In the above description, it is apparent that the decomposition and hydrophilization effect of a substance is completely different, if Shimese concrete examples, TiO ₂ anatase even TiO ₂ oxidation-reduction reaction However, rutile-type TiO ₂ shows almost no decomposition action of the substance based on the redox reaction. Also, among the photocatalysts, tin oxide does not show a decomposition effect of a substance based on a redox reaction. In these photocatalyst particles, the energy level of the conduction band is not sufficiently high, so that the reduction reaction does not proceed. As a result, the electrons excited by the photoexcitation in the conduction band become excessive, and the electron-hole pairs generated by the photoexcitation are oxidized and reduced. It is believed that they recombine without participating in the reaction. However, both rutile TiO ₂ and tin oxide exhibit a hydrophilizing action. Further, the photocatalytic layer needs to have a thickness of at least 100 nm in order to exhibit the decomposing action of the substance, but it is possible for the photocatalytic layer to exhibit a hydrophilizing action if it has a thickness of several nm or more. From these facts, it can be said that the decomposition action of the substance by the photocatalyst and the hydrophilization action are completely different.

[0008]

As described above, since the photocatalyst has a hydrophilizing action, the surface layer containing the photocatalyst particles constitutes a filter product such as a mesh door as proposed in JP-A-3-106420. If it is formed on the surface of the wire (fiber), not only the deodorizing effect but also the self-cleaning effect that the adhered dirt is washed away by rainwater or the like without using a detergent or the like will be exhibited.

However, when a surface layer containing photocatalyst particles is directly formed on the surface of the wire as proposed in Japanese Patent Laid-Open No. 3-106420, the wire itself may be corroded or deteriorated by the redox reaction of the photocatalyst. is there. Further, when the surface layer containing photocatalyst particles is directly formed on the surface of the wire, there is a possibility that the surface layer may be easily peeled off due to rubbing or the like.

[0010]

The present invention has been made on the basis of the above findings, that is, that the photocatalyst has a hydrophilizing action and can exhibit a self-cleaning effect, and the conventional problems. The filter product according to 1 (first invention) has a hydrophilic layer containing a photocatalyst particle formed on the surface of a wire constituting the filter product by forming a protective layer for protecting the wire from a redox reaction by a photocatalyst. To form a permeable surface layer.

In the filter product according to claim 3 (the second invention), the wire itself contains photocatalyst particles, and the surface of the photocatalyst particles is provided with a protective film for protecting the wire from the redox reaction by the photocatalyst. In the filter product according to the second aspect of the present invention, if the photocatalyst particles are exposed to the outside air by etching the surface of the wire rod, the hydrophilic effect is further improved.

Titanium oxide is most preferable as the photocatalyst particles, but in addition to this, ZnO, SnO ₂ , SrTiO ₃ , W
Examples thereof include metal oxides such as O ₃ , Bi ₂ O ₃ , and Fe ₂ O ₃ . It is considered that, since a metal element and oxygen are present on the surface, a hydroxyl group (OH ⁻ ) is easily adsorbed on the surface, and therefore, it is easy to exhibit hydrophilicity. The titanium oxide may be either anatase type or rutile type.

As a method of forming a hydrophilic surface layer containing photocatalyst particles (titania), formation of amorphous titania,
Examples include application of silica-containing titania, application of tin oxide-containing titania, application of titania-containing silicone paint, and the like.

The formation of the amorphous titania is a method in which the surface to be coated is first coated with the amorphous titania and then fired to change the phase to crystalline titania, and any of the following methods can be adopted. . (1) Hydrolysis and Dehydration Polycondensation of Organic Titanium Compounds Titanium alkoxides such as tetraethoxy titanium, tetraisopropoxy titanium, tetra n-propoxy titanium, tetrabutoxy titanium, tetramethoxy titanium, and hydrolyzed hydrochloric acid or ethylamine. After adding a decomposition inhibitor and diluting with an alcohol such as ethanol or propanol, the mixture is spray-coated, flow-coated, spin-coated, while the hydrolysis is partially or completely allowed to proceed. It is applied by dip coating, roll coating or other coating method, and dried at room temperature to 200 ° C. By drying, the hydrolysis of the alkoxide of titanium is completed to form titanium hydroxide, and a layer of amorphous titania is formed by dehydration-condensation polymerization of titanium hydroxide. Instead of titanium alkoxide, other organotitanium compounds such as titanium chelate or titanium acetate may be used. (2) Formation of amorphous titania by inorganic titanium compound Inorganic titanium compound such as TiCl ₄ or Ti (S
An acidic aqueous solution of O ₄ ) ₂ is applied by spray coating, flow coating, spin coating, dip coating, roll coating or other coating method, and dried at a temperature of 100 to 200 ° C. to perform hydrolysis and dehydration polycondensation, Form a layer of amorphous titania. Or it may form a layer of amorphous titania on the surface to be coated by chemical vapor deposition of TiCl _4. (3) Formation of amorphous titania by sputtering A target of metal titanium is irradiated with an electron beam in an oxidizing atmosphere to form a layer of amorphous titania on the surface to be coated.

Application of silica-containing titania is to form a layer of a mixture of titania and silica on the surface to be coated. The ratio of silica to the total of titania and silica is 5 to 90 mol%, preferably 10 to 70 mol%, more preferably 10 to 50 mol%. The following method can be employed for forming the surface layer made of silica-containing titania. (1) A suspension containing particles of anatase type or rutile type titania and particles of silica is applied to a surface to be coated, and fired at a temperature equal to or lower than the softening point of the substrate (object to be coated). (2) Based on a mixture of a precursor of amorphous silica (for example, tetraalkoxysilane such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, etc.) and crystalline titania sol After applying to the surface of the material and hydrolyzing it as necessary to form silanol, heating at a temperature of about 100 ° C. or more and subjecting the silanol to dehydration polycondensation, the titania is bound with amorphous silica. Obtained surface layer (photocatalytic coating). In particular, if the dehydration condensation polymerization of silanol is performed at a temperature of about 200 ° C. or higher, the degree of polymerization of silanol can be increased, and the alkali resistance performance of the photocatalytic coating can be improved. (3) Dispersing silica particles in a solution of amorphous titania precursor (organic titanium compound such as alkoxide, chelate or acetate of titanium, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) Is applied to the surface of the base material, and the titanium compound is cooled to room temperature for 20 minutes.
By subjecting it to hydrolysis and dehydration polycondensation at a temperature of 0 ° C.,
A thin film of amorphous titania in which silica particles are dispersed is formed. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate. (4) Amorphous titania precursor (organic titanium compound such as alkoxide, chelate or acetate of titanium, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) in a solution of amorphous titania precursor (For example, tetraalkoxysilanes such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-propoxytitanium, tetrabutoxytitanium, tetramethoxytitanium, etc., silanols which are hydrolysates thereof, or polysiloxanes having an average molecular weight of 3000 or less) And apply to the surface of the substrate. Then, these precursors are subjected to hydrolysis and dehydration polycondensation to form a thin film composed of a mixture of amorphous titania and amorphous silica. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate.

The application of tin oxide-containing titania is to form a layer of a mixture of titania and tin oxide on the surface to be coated. The ratio of tin oxide to the total of titania and tin oxide is 1 to 95 mol%, preferably 1 to 50 mol%. The following method can be adopted as a method for forming a surface layer made of titania mixed with tin oxide. (1) A suspension containing particles of anatase type or rutile type titania and particles of tin oxide is applied to a surface to be coated, and fired at a temperature equal to or lower than the softening point of the substrate (object to be coated). (2) Dispersion of tin oxide particles in a solution of a precursor of amorphous titania (organic titanium compound such as titanium alkoxide, chelate or acetate, or inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) ₂ ) The resulting suspension is applied to the surface of the substrate, and the titanium compound is heated to room temperature for 20 minutes.
By subjecting it to hydrolysis and dehydration polycondensation at a temperature of 0 ° C.,
A thin film of amorphous titania in which tin oxide particles are dispersed is formed. Next, the amorphous titania is changed into crystalline titania by heating to a temperature higher than the crystallization temperature of titania and lower than the softening point of the substrate.

The titania-containing silicone paint is applied by using a paint in which titania (photocatalyst particles) is dispersed in a film-forming element made of uncured or partially cured silicone (organopolysiloxane) or a precursor of silicone. .. Specifically, when the photocatalyst is photoexcited after the above coating material is applied to the surface of the substrate and the coating film forming element is cured, the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the action of the photocatalyst. , The surface is made hydrophilic (superhydrophilic). This method has the advantages that the film-forming element can be cured at a relatively low temperature, can be applied as many times as necessary, and can be easily hydrophilized even by sunlight. Examples of the resin that cures at a temperature as low as room temperature include the following. Methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltrit-butoxysilane, ethyltrichlorosilane, ethyltribromosilane, ethyltrimethoxysilane, ethyltriethoxysilane, Ethyltriisopropoxysilane, ethyltri-t-butoxysilane, n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n
-Propyltriisopropoxysilane, n-propyltrit-butoxysilane, n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n
-Hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane, n-decyltrichlorosilane,
n-decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyltriisopropoxysilane, n-decyltrit-butoxysilane, n-octadecyltrichlorosilane, n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n
-Octadecyltriisopropoxysilane, n-octadecyltrit-butoxysilane, phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltrit-butoxysilane, tetrachloro Silane, tetrabromosilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane, dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldichloro Silane, diphenyldibromosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenylmethyldichlorosilane, phenylmethyl Dibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, triethoxyhydrosilane, tribromohydrosilane, trimethoxyhydrosilane, isopropoxyhydrosilane, tri-t-butoxyhydrosilane, vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyl Triethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane, trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane ,
Trifluoropropyltri-t-butoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltrit-butoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyl Trimethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltrit-butoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-ami Nopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltrit-butoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane,
β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and partial hydrolysates thereof or a mixture thereof can be used. In order to ensure good hardness and smoothness of the silicone resin film, it is preferable to contain 10 mol% or more of the three-dimensional crosslinked siloxane. In order to provide sufficient flexibility of the resin film while ensuring better hardness and smoothness, 2
It is preferable that the dimensional cross-linking siloxane content be 60 mol% or less. Further, in order to accelerate the rate at which the organic group bonded to the silicon atom of the silicone molecule is replaced with the hydroxyl group by photoexcitation, the organic group bonded to the silicon atom of the silicone molecule is n.
It is preferred to use silicones consisting of -propyl or phenyl groups. An organopolysilazane compound having a silazane bond can be used instead of the silicone having a siloxane bond.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 3 is an overall view of a screen door as an example of the filter product according to the present invention, and FIG. 4 is an enlarged view of a wire rod that constitutes the screen door. In the screen door 1, a wire rod 3 is stretched vertically and horizontally inside a frame body 2. A protective layer 4 is formed on the surface of the wire 3 and a hydrophilic surface layer 5 containing photocatalyst particles is formed on the protective layer 4.

The protective layer 4 is composed of, for example, a vapor-deposited aluminum layer or a layer containing aluminum particles. By providing the protective layer 4, the wire is protected from the redox reaction by the photocatalyst.

In the above embodiment, the surface layer 5 was formed on the surface of the wire 3 with the protective layer 4 interposed therebetween. However, when the wire is made of resin or the like, as shown in FIG. The photocatalyst particles 6 may be contained in the interior of the material 3. In this case, for the same reason as above, it is preferable to form the protective film 7 on the surface of the photocatalyst particles 6 to protect the wire from the redox reaction by the photocatalyst.

As described above, when the protective film 7 is formed, the activity of the photocatalyst particles 6 is somewhat impaired. Therefore, FIG. 5 (b)
As shown in, the wire 3 may be etched to remove the protective film 7 on the surface of the photocatalyst particles 6 to expose the photocatalyst particles 6 to the outside air.

(Example 1) A silicone resin containing titanium oxide sol in a proportion of 0 to 80% was applied to the surface of a commercially available screen door using a polyester net to form a surface layer. Then, this surface layer was irradiated with ultraviolet rays of 0.5 mW / cm ² . The results are shown in (Table 1) below.

[0023]

[Table 1]

(Example 2) A titanium oxide film was deposited by sputtering on the surface of a commercially available screen door using a metal net.
This titanium oxide film was baked at 500 ° C. to form a surface layer. Then, when the surface layer was irradiated with 0.5 mW / cm ² of ultraviolet rays, the contact angle of the surface layer with water was less than 3 °.

[0025]

As described above, according to the first invention of the present application, a base layer for forming a hydrophilic surface layer containing photocatalyst particles on the surface of a wire constituting a filter product such as a screen door. As described above, since the protective layer for protecting the wire from the redox reaction by the photocatalyst is formed, it is possible to effectively prevent the wire from being corroded or deteriorated.

Further, according to the second invention of the present application, since the wire rod itself is made to contain the photocatalyst particles, it is difficult to peel off,
Particularly when the photocatalyst particles are included in the wire itself, a protective film is formed on the surface of the photocatalyst particles to protect the wire from oxidation-reduction reaction, so the wire can be effectively prevented from being corroded or deteriorated, and the wire surface can be etched with alkali or the like. Since the photocatalyst particles are exposed to the outside air, the hydrophilic effect can be improved.

[Brief description of drawings]

1A is a conceptual diagram of a hydrophobic surface, and FIG. 1B is a conceptual diagram of a hydrophilic surface.

FIG. 2 is a diagram illustrating a process of imparting hydrophilicity to a surface layer made of photocatalytic particles.

FIG. 3 is an overall view of a screen door as an example of a filter product according to the present invention.

FIG. 4 is an enlarged view of the wire rods that make up the screen door.

5A is a cross-sectional view showing a state before etching the wire rod, and FIG. 5B is a cross-sectional view showing a state after etching the wire rod.

[Explanation of reference numerals] 1 ... screen door, 2 ... frame, 3 ... wire rod, 4 ... protective layer, 5 ... surface layer, 6 ... photocatalyst particles, 7 ... protective film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiya Watanabe 2-1, 1-1 Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka Prefecture Totoki Kikai Co., Ltd. (72) Inventor Makoto Senkuni, Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka 2-1, 1-1 Totoki Equipment Co., Ltd.

Claims (4)

[Claims] 1. A filter product in which only an object having a size smaller than a predetermined size is allowed to pass through a gap formed between the wire rods, and a protective layer for protecting the wire rods from a redox reaction by a photocatalyst on the surface of the wire rods. A filter product, wherein a hydrophilic surface layer containing photocatalyst particles is formed via the. 2. The filter product according to claim 1, wherein the hydrophilic surface layer containing the photocatalyst particles is formed by forming a silicone resin layer containing the photocatalyst particles, hydrolysis of the titanium compound and dehydration condensation polymerization. A filter product obtained by forming a regular silica layer or forming an amorphous titania layer by sputtering. 3. A filter product in which only an object having a size smaller than a predetermined size is allowed to pass through a gap formed between the wire rods, wherein the wire rods themselves contain photocatalyst particles, and the photocatalyst particles have a photocatalyst surface. A filter product having a protective film formed thereon for protecting the wire from the redox reaction. 4. The filter product according to claim 3, wherein photocatalyst particles are exposed to the outside air by etching on the surface of the wire.