JP2002058925A - Air cleaning filter and producing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air cleaning filter excellent in an air cleaning function and a producing method thereof. SOLUTION: This air cleaning filter is produced by impregnating directly an air permeable material with a resin solution which contains a substance having photocatalytic activity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air purification filter obtained by impregnating a gas permeable filter substrate with a resin solution containing a substance having a photocatalytic activity.

[0002]

2. Description of the Related Art Titanium dioxide and zinc oxide having photocatalytic activity are themselves optical semiconductors and have a band gap of about 3 eV, so that when they are irradiated with sunlight or artificial illumination light (ultraviolet light), they become conductive bands. Is a hole where holes are accumulated
Occurs. It is known that the photocatalytic activity of oxidizing harmful substances in the atmosphere, for example, nitrogen oxides and finally converting them into nitric acid by an oxidation-reduction action based on the electron transfer generated by the accumulated electrons and holes is known. Various proposals have been made to industrially utilize.

[0003] For example, as a method of purifying a living environment, a titanium oxide containing titanium oxide obtained by performing papermaking with ultrafine titanium oxide, an inorganic filler for supporting the titanium, and an organic fiber material having a papermaking ability is used. Paper (JP-A-9-5989)
No. 2) is known. What is described in the publication,
There is a problem that the strength of the titanium oxide-containing paper is extremely reduced because it is easily hydrated and swelled with water due to its high hydrophilicity, and the purifying ability is reduced because titanium is easily desorbed.

Further, a functional mixture containing a photoreactive semiconductor, a metal oxide composite thermoplastic polymer emulsion, and a film-forming inorganic substance such as colloidal silica is applied to a base material such as nonwoven paper and a porous film. A coated photocatalytic filter (see JP-A-11-114330) is known. The one described in this publication has poor performance such as water resistance of the base material because the functional mixture hardly penetrates the base material, and further has a small effect of reinforcing the base material with the functional mixture, thereby further increasing the durability. Can't improve.

[0005]

The present inventors have made intensive studies to achieve the above object, and as a result, have achieved the above object by using a resin solution, particularly an organic silicon high condensate, as a binder. They found what they could do and completed the present invention.

Thus, according to the present invention, there is provided an air purification filter characterized by impregnating a gas permeable filter substrate with a resin solution containing a substance having photocatalytic activity.

Further, the present invention provides a method for producing an air purification filter, which comprises impregnating a resin solution containing a substance having photocatalytic activity directly into a gas-permeable filter substrate and drying it at room temperature or under heat. Related to

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a substance having photocatalytic activity, a conventionally known substance can be used without any particular limitation, and titanium dioxide and zinc oxide powders are particularly preferred.

As the titanium dioxide, any one having photocatalytic activity can be used without particular limitation.
Preferable ones include anatase type titanium dioxide. Suitable commercial products of anatase type titanium dioxide include, for example, ST-0 manufactured by Ishihara Techno Co., Ltd.
1, ST-21, ST-31, ST-41; SSP-25, SSP-20, SSP- manufactured by Sakai Chemical Co., Ltd.
M: AMT-100, AMT-60 manufactured by Teika Corporation
0, ST-157, JA-1; PC-101, PC-102, manufactured by Titanium Industry Co., Ltd .; DN-1, DN-S1, DN-1-0, DN, manufactured by Furukawa Machine Metal Co., Ltd. -10,
DN-12, DN-22A; T made by Fuji Titanium Co., Ltd.
PY-2Y; P-25 manufactured by Degussa; and the like.

As the zinc oxide used as the powder having photocatalytic activity, any zinc oxide having photocatalytic activity can be used without any particular limitation. Suitable commercial products are, for example, those manufactured by Sakai Chemical Co., Ltd. Zinc Hua No. 1 special product.

The powder having photocatalytic activity is excited by absorbing ultraviolet light such as sunlight or artificial illumination light, for example, ultraviolet light having a wavelength of 400 nm or less, preferably light having a wavelength of 285 nm to 380 nm. And OH radicals, which show strong oxidation performance and oxidize and decompose harmful substances.

In the present invention, the resin solution used together with the substance having photocatalytic activity is not particularly limited as long as it has good permeability to the gas permeable filter, but is preferably an organic silicon high condensate.

The above-mentioned organosilicon high-condensate has good storage stability, and does not gel for a long time even if a photoactive catalyst powder is added. In addition, since the highly condensed product is formed by using tetraalkoxysilane and trialkoxysilane in combination, the crosslinking density can be appropriately adjusted by changing the mixing ratio, and as a result, the balance between curability and thick coatability can be obtained. In other words, it is possible to form an inorganic coating film having excellent thickness, that is, no cracking or peeling at the time of curing, as a thick film having a thickness of 50 μm or more. Further, the cured film has a main skeleton of -Si-OS-S
Since it is an i-bond, it has excellent properties such as heat resistance, corrosion resistance, chemical resistance, and weather resistance.

In the organosilicon compound represented by the above general formula [A] used as a raw material, R is the same or different and is a hydrocarbon group having 1 to 8 carbon atoms. And alkyl groups such as ethyl, propyl and hexyl, aryl groups such as phenyl, tolyl and xylyl, and cycloalkyl groups such as cyclohexyl, cyclobutyl and cyclopentyl. Specific compounds include, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraphenoxysilane and the like. The low condensate means an oligomer having a polymerization degree of 10 or less.

R in the organosilicon compound represented by the general formula [B] is the same as that in the general formula [A]. On the other hand, R ′ is a hydrocarbon group having 1 to 12 carbon atoms bonded to silicon by a carbon-silicon bond, and examples of the hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, hexyl and octyl, phenyl, tolyl, Aryl groups such as xylyl and naphthyl; and cycloalkyl groups such as cyclohexyl, cyclobutyl and cyclopentyl.

Specific compounds include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane and the like.

In obtaining a highly condensed product using the above general formulas [A] and [B], it is appropriate to mix the two components in the following ratio on a weight basis.

Compound of general formula [A]: 5 to 95% by weight, preferably 20 to 80% by weight Compound of general formula [B]: 5 to 95%
% By weight, preferably 20-80% by weight
When the amount of the compound (A) is less than 5% by weight, that is, when the amount of the compound (B) exceeds 95% by weight, the curability of the inorganic coating film formed using this condensate is poor. When the amount of the compound (B) is less than 5% by weight, that is, when the amount of the compound (A) is more than 95% by weight, the coating film is liable to crack or peel when subjected to thick coating using the condensate. There are disadvantages.

In obtaining the above condensate, a bifunctional organic silicon compound such as dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, methylethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, triphenylmethoxysilane ,
Monofunctional organosilicon compounds such as dimethylethylethoxysilane can be used together in a range of 20% by weight or less.

When condensing the mixture of the organosilicon compound represented by the general formulas [A] and [B] and / or the low condensate thereof, the mixture of the compound and / or the low condensate is dissolved in a water-soluble compound. Solvents, for example, alcohol solvents, cellosolve solvents, cellosolve acetate solvents, added to glyme solvents, etc., hydrochloric acid, sulfuric acid, mineral acids such as phosphoric acid or formic acid, in the presence of organic acids such as acetic acid, Si Water is added at a rate of 0.2 to 2 mol per 1 mol of the bonded RO group, and the mixture is reacted under stirring at about 20 to 100 ° C. for about 30 minutes to 10 hours. An inorganic base, aliphatic amines such as monoethylamine, diethylamine and triethylamine, ammonia and the like are added to raise the pH of the system to 7 or more, and the condensation reaction proceeds. After completion of the reaction, the desired product highly condensed product can be easily obtained by removing remaining water by distillation, azeotropic distillation, or the like.

The highly condensed product thus obtained is a three-dimensional condensate (which may include a straight chain) and has a degree of condensation of at least 20 and a molecular weight of at least about 3,000.
Further, it has a sufficient function as a paint binder containing a functional group of an alkoxysilyl group and / or a hydroxysilyl group, and cures in about 10 minutes to 10 hours after application. At this time, the curability can be further improved by adding a strong base catalyst such as tetramethylammonium hydroxide or tributylamine, or a metal alkoxide such as titanium or aluminum, a metal acetylacetonate, or a metal carboxylate.

In the coating composition of the present invention, the amount of the above-mentioned substance (I) having photocatalytic activity is preferably 5 to 65 parts by weight based on 100 parts by weight of the total solid content of the coating composition. More preferably, it is in the range of 50 to 50 parts by weight.

The coating composition of the present invention preferably contains a substance having photocatalytic activity and a high condensate of organosilicon as essential components. If necessary, pigments, fillers, and fluidity generally used in the paint industry are usually used. Additives such as a regulator can be blended.

The coating composition of the present invention can be applied to a breathable filter substrate by spray coating, mat coating, brush coating, roller coating, dipping, or the like.
Although the coating film thickness is not particularly limited, it is usually 1 to
It is suitable that it is in the range of 200 μm, more preferably in the range of 10 to 100 μm. The coating film is dried at room temperature, but may be cured by baking at 100 to 200 ° C. for about 15 to 60 minutes.

The solid content of the resin solution when impregnating the substrate is preferably 1 to 60% by weight, particularly preferably 10 to 30% by weight. The organic solvent used to dissolve the resin is not particularly limited as long as it dissolves the resin, and is a conventionally known organic solvent, for example, a hydrocarbon-based organic solvent such as toluene, xylene (o −, M−, p−)
As alcohols, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol, isobutyl alcohol, etc. As ethers, for example, dioxane, tetrahydrofuran, cellosolve, methyl cellosolve, butyl cellosolve, methyl carb Tall, 2-methoxyethanol, 2-butoxyethanol, diethylene glycol,
Examples of ketones such as diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and dipropylene glycol monomethyl ether, such as acetone and methyl ethyl ketone , Isophorone, cyclohexanone, etc., as esters, for example, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, 3-methoxybutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, ethylene glycol mono Examples include acetate, cellosolve acetate, carbitol acetate, ethyl acetoacetate and the like.

The air-permeable filter substrate of the present invention includes:
There is no particular limitation, and examples thereof include an air purifier used for home, commercial use, and factory use, and an air purifying filter of an air purifying unit of a room air conditioner.

Examples of the shape of such a gas permeable filter include a honeycomb filter.

For example, as a honeycomb filter,
It has a shape of a structure composed of cell walls having openings, and is formed by laminating single corrugated boards manufactured in accordance with "exterior cardboard" described in JIS-Z-1516 as a specific example of a honeycomb. Examples include corrugated honeycombs, hexagonal honeycombs composed of hexagonal cells, honeycombs composed of rhombic cells, honeycombs composed of square cells, honeycombs composed of triangular cells, and honeycombs composed of hollow cylindrical cells.

The air-permeable filter substrate according to the present invention includes paper, woven fabric, non-woven fabric, net, sponge, etc., as well as polyethylene film, polypropylene film,
And general-purpose thermoplastic films such as polyester films and thin plates. Of these, a sheet having poor air permeability, such as a film or a thin plate, may have a fine hole to improve air permeability, and may be used as a gas permeable substrate. Among them, in particular, when paper and non-woven fabric are used, not only can relatively uniform air permeability be ensured, but also encapsulation processing is easy, so that they are used advantageously.

The nonwoven fabric used as the air-permeable base material includes polyamide fibers, polyester fibers, polyalkylene paraoxybenzoate fibers, polyurethane fibers,
Synthetic fibers such as polyvinyl alcohol fiber, polyvinylidene chloride fiber, polyvinyl chloride fiber, polyacrylonitrile fiber, polyolefin fiber and phenol fiber, inorganic fibers such as glass fiber, metal fiber, alumina fiber and activated carbon fiber Use natural fibers such as wood pulp, hemp pulp, and cotton linter pulp, regenerated fibers, or fibers that have these fibers imparted functions such as hydrophilicity, flame retardancy, deodorization, adsorption, and antibacterial properties. It is manufactured by various methods.

The method for producing the nonwoven fabric is not particularly limited, and the web obtained by a dry method, a wet papermaking method, a melt blown method, a spun bond method, etc. may be subjected to a hydroentanglement method, a needle punch method, a stitch, etc. It can be produced by appropriately combining a physical method such as a bonding method, a bonding method using heat such as a thermal bonding method, and a bonding method using an adhesive such as a resin bond to develop strength.

The present invention also includes an air purification filter obtained by applying a resin solution containing the substance having photocatalytic activity after the base treatment of the air-permeable filter substrate. As the base treatment, it is preferable to use the above-mentioned organosilicon high condensate.

In the method of the present invention, the air permeable filter substrate is directly impregnated (painted) with a resin solution containing the substance having photocatalytic activity, and the air purification filter is manufactured by drying at room temperature or by heating. Can be.

In the method of the present invention, the air-permeable filter base material is coated with the base treatment liquid, then impregnated with a resin solution containing the substance having photocatalytic activity, and air-dried at room temperature or by heating and drying. Purification filters can be manufactured.

[0035]

The present invention is a highly durable multifunctional filter that exhibits a plurality of air purifying functions such as deodorization, antibacterial, and dust removal. It is inferred that such effects are exhibited for the following reasons. (1) In particular, by using a high condensate of organosilicon as a binder, the surface tension of the condensate is small, so that it easily penetrates into a gas permeable filter. The condensate that has permeated into the base material has excellent adhesion to the base material because the alkoxysilyl group of the condensate is hydrolyzed into a hydroxysilyl group, and the remaining hydroxysilyl groups are mutually bonded. Since the polysiloxane bond is formed by the condensation reaction, the polysiloxane bond becomes hydrophobic, and a coating film excellent in water resistance, processability, durability and the like is formed. (2) Further, in the organic silicon high-condensate, by controlling the amount of application, it can be applied to the base material but can be applied so as not to be applied between the eyes between the base materials. The air purifying function can be exhibited without lowering the air quality. (3) The air-permeable filter is periodically cleaned and maintained. However, the filter of the present invention is excellent in water resistance and the strength of the filter is strong, so that there is no risk of breakage or breakage in the maintenance. In addition, there is an advantage that it can be washed with water. (4) Since the wettability (adhesion) between the organosilicon high-condensate and the substance having photocatalytic activity is excellent, the substance having photocatalytic activity does not desorb even after long-term use. During the period, the above-described air cleaning function is exhibited.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Note that “parts” and “%” are based on weight, respectively.

Production Example of Organic Silicon High Condensate Production Example 1 62 g of tetraethoxysilane, 125 g of methyltriethoxysilane and 187 g of ethyl alcohol were placed in a reaction vessel.
Was added thereto, and the content was heated to 80 ° C. while stirring, and then 30 g of 0.2N hydrochloric acid was added, followed by a reaction at 80 ° C. for 10 hours. Next, triethylamine 3 was added to the reaction product.
0 g was added to raise the pH to 7 or more, and a condensation reaction was carried out at 80 ° C. for 2 hours. Thereafter, 100 g of benzene was added and the solvent was removed until the nonvolatile content became 40% (% by weight, the same applies hereinafter). Condensate-1 was obtained.

The highly condensed product (varnish) thus obtained is transparent, has a viscosity of 5.8 centipoise, does not thicken or gel even after storage at 30 ° C. for 2 months, and shows excellent storage stability. Was.

Production Example 2 To a reaction vessel, 427 g of ES-40 (tetraethoxysilane low-condensate manufactured by Nippon Colcoat Co., Ltd.), 58 g of ethyltriethoxysilane and 300 g of ethyl alcohol were added, and the contents were heated to 80 ° C. while stirring. 0.2N after
-Hydrochloric acid 142g was added and reacted at 80 ° C for 30 minutes.
Next, 5 g of potassium hydroxide was added to the reaction product to raise the pH to 7 or more, and a condensation reaction was performed at 80 ° C. for 2 hours.
Thereafter, 200 g of benzene was added, and the solvent was removed until the nonvolatile content became 30%, to obtain a highly condensed product-2.

The highly condensed product (varnish) thus obtained is transparent, has a viscosity of 11.2 centipoise, and does not thicken or gel even after storage at 30 ° C. for 2 months and shows excellent storage stability. Was.

Example 1 100 g (solid content) of the highly condensed product-1 obtained in Production Example 1 was anatase-type titanium dioxide powder (manufactured by Teica Co., Ltd., AM
100 g of T-100 (trade name) and 1 g of aluminum tris (ethylacetoacetate) were mixed and dispersed to obtain a coating composition of the present invention.

Example 2 100 g (solid content) of the highly condensed product-2 obtained in Production Example 2 was anatase-type titanium dioxide powder (manufactured by Ishihara Techno Co., Ltd.).
ST-01 (trade name) 150 g and tris (ethylacetoacetate) aluminum 1 g were mixed and dispersed to obtain a coating composition of the present invention.

Example 3 100 g (solid content) of the highly condensed product-2 obtained in Production Example 2, 100 g of titanium dioxide used in Example 2, and zinc oxide powder (Zinc Hua No. 1 manufactured by Sakai Chemical Co., Ltd.) Special, trade name) 50g
And 2 g of tetramethylammonium hydroxide
Was mixed and dispersed to obtain a coating composition of the present invention.

Preparation of Paint Filter A paper honeycomb filter AS50 (manufactured by Seibu Giken Co., Ltd .: 10 mm in thickness) is 200 mm × 300 mm (A4
Plate) and cut to the size of the coating material. This filter has a corrugated honeycomb structure, and has a cell pitch of 5.1 mm and a height of 3 mm. Examples 1, 2, and 3
Was diluted with butyl cellosolve to a viscosity suitable for spray coating, and the material was spray-coated by ordinary air spray coating. At this time, the solid content concentrations of Example 1 were 40% (resin concentration 20%), Example 2 was 37% (resin concentration 14.8%), and Example 3 was 3%.
It was 5% (resin concentration 14%). The sample was baked at 160 ° C. for 30 minutes using a hot air dryer coated several times so that the photocatalyst layer had a predetermined thickness.
2.3a was obtained.

The coating composition of Example 3 was left at room temperature for 7 days after coating to obtain a coating filter 3b.
At this time, the thickness of the photocatalytic film on the filter was measured by observing the cross section with a microscope, and was 50 μm to 60 μm. Blank unpainted paper filter (comparative example)
And The obtained coated filter and blank were tested according to the following test method. The test results are shown in Table 1 below.

Test Method Coating appearance: Observed with the naked eye.

Nitrogen oxide decomposability: A sample was 30 mm long and 5 mm wide.
It was cut into a size of 0 mm, and the coated plate was placed in a reaction vessel having a height of 400 mm, a width of 400 mm and a depth of 500 mm. Nitrogen oxide (NO) 1.0 was used as an atmospheric gas in the reaction vessel.
It consists of ppm and air. After irradiating black light from the upper part of the reaction vessel at an irradiation intensity of 0.1 mW / cm ^{2 for} 5 minutes, 30 minutes and 1 hour, the nitrogen oxide concentration in the reaction vessel was measured by “Chemical emission type NOx meter CLAD1000” (manufactured by Shimadzu Corporation). , Nitrogen oxide analyzer, trade name). Displays the nitrogen oxide concentration (ppm). Water resistance: The sample was immersed in tap water for 24 hours with a weight attached so as not to float, then pulled up. Immediately afterwards, both ends of the sample were grasped by hand and pulled to test whether the filter was broken. The case where the filter was robust and did not deform was rated as ○, the case where the filter was slightly deformed in the pulling direction but did not break was rated as △, and the case where the filter was easily broken due to peeling off of the corrugated adhesive portion was evaluated as ×. Table 1

[0048]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 183/04 B01D 53/36 J F-term (Reference) 4C080 AA07 BB02 CC01 HH05 JJ03 KK08 LL10 MM02 NN01 NN24 NN26 NN27 NN28 NN29 4D019 AA01 BA12 BA13 BB02 BB03 BB08 BC06 BC07 CB06 4D048 AA21 AA22 BA07X BA13X BA16X BA41X BA45X BB02 CC40 EA01 4G069 AA03 AA08 BA04A BA04B BA21C BA22A BA22B BA29B BA48A BB04A BB04B BC35A BC35B BD05C BE06C BE32A BE32B BE32C CA01 CA11 CA17 EA18 EA21 EB12Y EB14Y EB15Y EC22Y FA02 FB05 FB17 FB57 4J038 DL031 KA03 KA12 KA20 MA09 NA04 NA05 NA18 PA07 PB06 PC08 PC10

Claims (6)

[Claims] 1. An air purification filter comprising a gas permeable filter substrate impregnated with a resin solution containing a substance having photocatalytic activity. 2. An air purifying filter, comprising: applying a resin solution containing a substance having photocatalytic activity after a base treatment of a permeable filter substrate. 3. A resin solution comprising the following component (I): a powder having photocatalytic activity; (II) an organosilicon compound represented by the following general formula [A] and / or a low condensate thereof: (Where R is a hydrocarbon group having 1 to 8 carbon atoms) An organosilicon compound represented by the following general formula [B] and / or a low condensate thereof: (Wherein R 'is a hydrocarbon group having 1 to 12 carbon atoms, and R is the same as described above), after hydrolyzing the mixture in the presence of an acid catalyst, and then condensing the mixture to a pH of 7 or more to obtain an organic compound. The air purification filter according to claim 1 or 2, which is a harmful substance decomposable coating composition containing a silicon high-condensate. 4. The air purification filter according to claim 1, wherein the air permeable filter substrate is a honeycomb filter. 5. A method for producing an air purification filter, comprising impregnating a resin solution containing a substance having photocatalytic activity directly into a gas-permeable filter substrate, and drying it at room temperature or by heating. 6. An air purification filter obtained by coating a base treatment liquid on a permeable filter base material, impregnating with a resin solution containing a substance having photocatalytic activity, and drying at room temperature or by heating. Manufacturing method.