JPH08117556A - Photo-reactive harmful matter-removing material and production thereof - Google Patents

Abstract

PURPOSE: To obtain a photo-reactive harmful matter-removing material utilizing titanium oxide being a photocatalyst, having the decomposition capacity of a harmful substance such as a malodor or antibacterial properties, excellent in processability or handleability and capable of being produced in low cost. CONSTITUTION: A photo-reactive harmful matter-removing material has constitution such that titanium oxide precipitated from a titania sol is supported on a nonwoven fabric containing a thermoplastic resin fiber or a glass fiber and is produced by impregnating the nonwoven fabric with the titania sol and treating the impregnated nonwoven fabric with an aq. soln. of an alkali agent containing alkali metal hydroxide or carbonate and drying the treated nonwoven fabric to support titanium oxide on the surface of the nonwoven fabric as fine floc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreactive harmful substance removing material capable of removing harmful substances such as malodor and bacteria by utilizing the photocatalytic ability of titanium oxide, and a method for producing the same.
More specifically, the present invention relates to a photoreactive harmful substance removing material in which a non-woven fabric is efficiently loaded with titanium oxide exhibiting the optimum photocatalytic ability, and a method for producing the same.

[0002]

2. Description of the Related Art With increasing interest in environmental issues,
There is an increasing demand for development of odor removing materials and odor removing devices that can easily remove odors in daily life. In addition, there is a rapidly increasing demand for the development of an antibacterial material which has a high antibacterial property against MRSA nosocomial infections and water treatment of pools and the like and is safe for the human body.

In response to such special and difficult requirements, titanium oxide has been attracting attention in recent years. Titanium oxide has been used as a white pigment for a long time in paints, fillers, and cosmetics. As a semiconductor, titanium oxide has been studied for a long time for its photocatalytic ability. For example, J. Oil. Chem. Assoc. , 61 , 351
(1978) reported photodecomposition of alcohol by titanium oxide fine powder suspended in a hydroalcoholic mixed solution, and Japanese Patent Publication No. 57-47753 reported photodecomposition of water. Furthermore, in recent years, JP-A-61-13
Japanese Patent No. 5669 discloses decomposition of sulfide and Japanese Patent Publication No. 2-622.
No. 97, photodecomposition of nitrogen oxides, and JP-A-3-6.
In 9695 and 6-256540 gazettes, anti (kill)
Bacterial action and inhibition of water moss activity are disclosed.

After collecting various data on deodorization and antibacterial properties, Japanese Patent Laid-Open No. 253544/1993 describes an attempt to fix titanium oxide as a photocatalyst on the surface of a tile by sintering and use it. However, in such a method, the heat treatment is costly, and the amount of titanium oxide to be fixed is regulated by the surface area of the support, and further, the effective surface area is reduced by the binder, and the ability is reduced. was there.

In order to carry a sufficient amount of titanium oxide, it is necessary to increase the surface area of the carrier. For example, in JP-A-3-94814, a carrier carrying titanium oxide is processed into a corrugated plate. The method to be used is described. However, even in this method, since titanium oxide, which is a photocatalyst, is molded and fixed together with the carrier by sintering, there is a problem that the cost becomes high and post-processing is difficult.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photoreactive harmful substance removing material capable of removing harmful substances such as malodor and bacteria by utilizing the photocatalytic ability of titanium oxide, and a method for producing the same. Yes, specifically, the production of photoreactive toxic substance removal material in which titanium oxide that optimally exhibits photocatalytic activity is supported on the non-woven fabric and photoreactive toxic substance removal material that efficiently supports titanium oxide in the non-woven fabric with excellent photocatalytic ability. It provides a method. Another object of the present invention is to provide a photoreactive harmful substance removing material which can be laminated with another non-woven fabric or film in order to have other functions as a sheet such as design, texture and touch.

[0007]

Means for Solving the Problems As a result of studies conducted by the present inventors to solve the above problems, the titanium oxide precipitated from a titania sol by an alkali treatment is carried on a non-woven fabric, whereby titanium oxide having excellent photocatalytic activity is obtained. It has been found that the precipitation of the above can be carried out at the same time as the deposition on the non-woven fabric, and as a result, a photoreactive harmful substance removing material with excellent performance can be obtained at low cost, and the present problem has been solved.

The components of the photoreactive harmful substance removing material of the present invention and the method for producing the same will be described in detail below. The photoreactive harmful substance removing material of the present invention is composed of titanium oxide precipitated from titania sol and a non-woven fabric, and the non-woven fabric preferably contains at least either thermoplastic resin fiber or glass fiber. The titania sol according to the present invention is a semi-transparent acidic water system obtained by alkali-cleaning the precipitate of hydrous titanium oxide obtained in the process of producing titanium oxide from a naturally occurring titanium source, and deflocculating with a strong acid such as hydrochloric acid or nitric acid. Of dispersed sol. What is hydrous titanium oxide? "Titanium oxide" (Gaku Seino,
It is described in detail in Gihodo Shuppan (published in 1991), but generally, it is obtained by thermally hydrolyzing a titanium sulfate solution in the production process of titanium oxide by the sulfuric acid method.

The primary particles of such a titania sol according to the present invention are said to be anatase type microcrystals having a size of about several nm like the hydrous titanium oxide, and the pH of the solution changes from the acidic side. According to.
Therefore, if a supported body including the nonwoven fabric according to the present invention is made to coexist during titania sol aggregation, titanium oxide is supported on the nonwoven fabric as the carrier. 1 for the precipitated titanium oxide
When dried at a temperature below 00 ° C, the particle size will be 0.01 μm.
The photocatalytically active titanium oxide having a specific surface area of 200 m ² / g or more is obtained below.

The titanium oxide formed as described above is agglomerated and deposited on the non-woven fabric and carried. Raw materials used for the non-woven fabric include olefin resins such as polyethylene and polypropylene, polyester resins such as polystyrene, poly-p-xylylene and declone, epolyvinyl acetate, styrene vinyl acetate copolymer resins, polyamide resins such as nylon. , Thermoplastic resin fiber made of polyacrylonitrile, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl ether, polyvinyl ketone, polyether, polyvinyl alcohol resin, diene resin, polyurethane resin, etc., phenol resin, furan Thermosetting resin fiber such as resin, ketone / formaldehyde resin, xylene / formaldehyde resin, urea resin, melamine resin, aniline resin, unsaturated polyester resin, alkyd resin, and epoxy resin, as well as silicone type Wei, fluorine-based fibers, metal fibers stainless steel wool, various glass fibers, cellulosic fibers, and protein-based fibers or the like.

The shape of the raw material fibers used in the nonwoven fabric according to the present invention is not particularly limited, and the cross-sectional shape is not only circular but also oval, triangular, star-shaped, T-shaped, Y-shaped or so-called atypical shape such as leaf-shaped. It may have a sectional shape. Further, those having a void on the surface, a branched structure, and a core-sheath structure using different resins on the outside and inside of the fiber can also be used. Although the fiber length of these resin fibers is somewhat different depending on the fiber, it is generally 1 to 50 mm, and more preferably 5 to 50 mm. In addition, as the fiber diameter, generally 5 to 20 μm is suitable.

In the non-woven fabric according to the present invention, olefin resins such as polyethylene and polypropylene, polyester resins such as polystyrene, poly-p-xylylene and declone, epolyvinyl acetate, styrene vinyl acetate copolymer resin, Thermoplastic resin composed of polyamide resin such as nylon, polyacrylonitrile, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl ether, polyvinyl ketone, polyether, polyvinyl alcohol resin, diene resin, polyurethane resin, etc. Fibers and various glass fibers are preferably used.

The glass fiber used in the non-woven fabric according to the present invention is a glass fiber processed into a fibrous form, the most typical of which is E-glass, and C- which has excellent acid resistance.
Various glasses such as glass, low dielectric loss D-glass, high strength S-glass, and high elasticity M-glass can be used. The glass fiber diameter is typically about 3 to 10 μm, but ultrafine fibers of 1 μm or less may be used.

The non-woven fabric containing at least glass fibers has extremely high tensile strength, improved dimensional stability, moisture resistance, heat resistance and the like, and also improved affinity with titania sol and titanium oxide. The glass fiber can be made into a web by a dry method in a state of long fiber, and can be wet-processed in a state of short fiber. Further, at this time, it can be mixed with thermoplastic resin fibers, pulp, rayon and the like.

The non-woven fabric according to the present invention is a wet method in which the above fibers are suspended in water to form a sheet by a paper making method, a resin bond by resin adhesion, a needle punch utilizing interlacing with needles, a stitch bond knitted by a thread, or Applying the so-called dry method such as thermal bonding to bond by heat, the hydroentangling method of injecting high-pressure water from a nozzle to entangle fibers with each other, spunbond to form a sheet while directly spinning, and the principle of spraying when directly spinning It can be manufactured by a melt blow method or the like in which a sheet is formed while making fine fibers.

The thickness, porosity, void shape, porosity, flexibility, elasticity, fluffiness, and texture of the non-woven fabric can be adjusted by selecting the above manufacturing method. In particular, the non-woven fabric according to the present invention does not have strength if it is too thin, and conversely if the non-woven fabric is thick, the amount of titanium oxide supported per unit area can be increased, but all of it cannot receive light. About 80 g is preferable. Further, in the present invention, since the water-based treatment is performed, the non-woven fabric needs to have water wettability to some extent, and it is preferable that the web is made of hydrophilic fibers. Further, from the viewpoint of sheet strength, it is preferable to process the nonwoven fabric by a spunbond or spunlace method.

Next, a method for supporting titanium oxide on the nonwoven fabric from the titania sol according to the present invention will be described. The titania sol according to the present invention is impregnated into a nonwoven fabric in a sol state by dipping or coating. In the case of dipping, the impregnation amount is adjusted by the concentration of the sol and the degree of squeezing. When using a non-woven fabric with poor water wettability, corona treatment, glow discharge treatment,
It is preferable to improve water wettability by plasma treatment, electron beam irradiation treatment, far ultraviolet ray irradiation treatment, ozone treatment, and physical / chemical treatment such as surfactant. Further, after impregnation with the titania sol, the following treatment may be carried out in a wet state, but may be once dried.

The non-woven fabric impregnated with the titania sol is then treated with an alkali to coagulate and deposit titanium oxide on the non-woven fabric and carry it. As the alkaline agent used in the alkaline treatment relating to the cohesive precipitation of titanium oxide from titania sol, hydroxides or hydrous oxides of alkali metals and alkaline earth metals, and acids such as carbonic acid, phosphoric acid, boric acid, and silicic acid are used. And water-soluble inorganic substances such as basic ammonium salts such as carbonic acid and phosphoric acid, alcohol amines, alkylamines, alkylenediamines, morpholine, and basic guanidine salts. These are single species,
Alternatively, two or more kinds may be used in combination.

Of the above-mentioned alkaline agents, the use of an aqueous solution of a hydroxide or carbonate of an alkali metal such as lithium, sodium and potassium is preferably used because the aggregation rate of titanium oxide can be carried quickly. The pH of the treatment liquid in the alkali treatment is 14 or less, preferably about 8-12. When an aqueous solution of such an alkali is applied to a non-woven fabric impregnated with titania sol, the dispersion stability of the titania sol is impaired, titanium oxide is coagulated and deposited uniformly on the fiber surface of the non-woven fabric, and the titania sol is cohesively deposited. Both the adhesive strength and the uniformity of impregnation are improved by supporting it on a non-woven fabric afterwards.

Titanium oxide covers the surface of the non-woven fabric fiber by the alkali treatment. However, if the amount of the titania sol impregnated is high or if the above alkaline solution is not sufficiently squeezed, the titanium oxide agglomerates become large, and adsorption alone is sufficient. The titanium oxide powder is desorbed from the non-woven fabric. Therefore, it is important to adjust the supporting conditions so that the size of the supported titanium oxide aggregate is 10 μm or less, preferably 5 μm or less. In this state, titanium oxide is supported on the nonwoven fabric without being detached.

[0021]

In the photoreactive harmful substance removing material and the method for producing the same of the present invention, titanium oxide, which is a photoreactive harmful substance removing agent, is carried simultaneously with deposition from the sol, so that the titanium oxide is uniformly and firmly formed on the nonwoven fabric. Not only is it carried, but since it does not increase the particle size, it can be carried with a large specific surface area, and by irradiating with light including ultraviolet light, it is possible to decompose and remove harmful substances such as malodors and bacteria floating in the air. Titanium oxide having an excellent effect is obtained on a nonwoven fabric.

Further, if the non-woven fabric contains glass fiber, the strength at the time of post-processing after supporting is improved and at the same time the affinity with titania sol and titanium oxide is improved. On the other hand, if the raw material fiber having thermoplasticity is contained, it is excellent in processability such as being able to be laminated or laminated with another non-woven fabric or film at a low cost. Are better. Furthermore, by combining the photoreactive harmful substance removing material of the present invention with a non-woven fabric having other characteristics, it is possible to add various characteristics such as designability, texture and touch.

[0023]

The present invention will be described in more detail with reference to the following examples, but it should be understood that the present invention is not limited thereto.

Example 1 (A) Preparation of titania sol Titanium oxide hydroxide obtained in the usual production process of titanium oxide by the sulfuric acid method was neutralized and washed with an aqueous solution of sodium hydroxide, peptized with hydrochloric acid and converted into titanium oxide of 40. A titania sol stock solution with a pH of 1 in weight% was obtained. 10 parts of this titania sol stock solution
After doubling the dilution, 1000 ppm of a methanol solution of butynediol-based nonionic surfactant was added to obtain a titania sol impregnation liquid.

(B) Impregnation of Titanium Oxide A nonwoven fabric made of polypropylene fibers having an increased strength by the hydroentangling method (weight per unit area: 40 g / m ² ) was corona treated, then dipped in the above titania sol impregnating solution and squeezed lightly.
On the other hand, sodium hydrogen carbonate was dissolved in water to prepare an aqueous solution for alkali treatment having a pH of 8, and a non-woven fabric impregnated with titania sol was immersed in this aqueous solution for alkali treatment to support titanium oxide on the non-woven fabric, and at 80 ° C. for 3 minutes. Air-dried to obtain a photoreactive harmful substance removing material. No powder of titanium oxide was observed in the produced sheet. .

(C) Observation of Sheet The presence of titanium oxide was confirmed by the fluorescent X-ray analyzer in the prepared photoreactive harmful substance removing material. The amount of titanium oxide deposited was 4.3 g / m ^{2 based} on the weight difference before and after impregnation. Also, when observing the surface of this sheet with an electron microscope,
The size of the titanium oxide aggregate was 5 μm or less.

(D) Measurement of photocatalytic activity This sheet was cut into a size of 120 cm ² and placed in a 5.6 liter hermetic container. About 200 ppm of acetaldehyde, which is a typical compound having a bad odor of cigarettes or sweat, was injected into this container, and the change in the concentration of acetaldehyde in the container was measured over time while irradiating with a black lamp (6 W). Similarly, the titanium oxide-supported non-woven fabric prepared above was placed in a closed container together with acetaldehyde and was not irradiated with light. Furthermore, a non-woven fabric not supporting titanium oxide was put in another container, and then acetaldehyde was injected and irradiated with a black lamp. As a result, when the titanium oxide-supported non-woven fabric was irradiated with a black lamp, acetaldehyde was reduced to 50 ppm after 30 minutes, but 180 ppm was obtained for those not irradiated with light. Further, in the case of the titanium oxide-unsupported nonwoven fabric, it decreased by only a few ppm. Therefore, the photocatalytic ability that the acetaldehyde is decomposed by irradiating the supported titanium oxide with light was observed.

Example 2 The titania sol stock solution prepared in Example 1 was diluted 10 times and a titania sol impregnating solution containing a surfactant was impregnated into a glass fiber non-woven fabric made of E-glass using polyvinyl alcohol as a binder and squeezed lightly. On the other hand, sodium hydroxide was dissolved in water to prepare an alkaline aqueous solution having a pH of 10. This glass fiber non-woven fabric impregnated with titania sol was immersed in an alkaline aqueous solution to deposit and carry titanium oxide, and dried at 60 ° C. for 10 minutes. When the deposit on the surface of the glass fiber non-woven fabric was analyzed and weighed in the same manner as in Example 1, the deposit was titanium oxide, and the deposit amount was 5.4 g / m ² .

This sheet was cut into a size of 120 cm ² and placed in a 5.6 liter hermetically sealed container.
When the photodecomposition ability of acetaldehyde was measured under the same conditions as above, the initial concentration of 200 ppm was 40 ppm after 30 minutes.
Decreased to.

Comparative Example 1 Rutile type titanium oxide (Saton Chemical Co .; Titon R-3L)
Was dispersed in water containing 1000 ppm of a methanol solution of butynediol-based nonionic surfactant at 4% by weight to prepare a titanium oxide impregnated solution. Two glass fiber nonwoven fabric sheets prepared in Example 2 were used. After being immersed in the titanium oxide impregnating solution, one sheet was treated with the alkaline solution used in Example 2 and the other sheet was not treated with the alkaline solution. The two sheets were dried under the same conditions as in Example 2 to prepare a titanium oxide-supported nonwoven fabric. The photocatalytic ability of the two titanium oxide-supported nonwoven fabrics was measured in the same manner as in Example 1, and the black lamp irradiation 3
The acetaldehyde decomposition amount after 0 minutes was 20 ppm or less in all cases.

Example 3 Using the titania sol impregnating solution prepared in Example 1 in a non-woven fabric having a basis weight of 40 g / m ² produced by a wet method by mixing polypropylene resin and cellulose fibers in equal amounts, Example 1
Titanium oxide was supported in the same manner as in. Separately from this, heat-sealing was performed on a breathable non-woven fabric made of polypropylene resin fiber (weight per unit area: 20 g / m ² ) with an embossed hot roll to prepare a photoreactive harmful substance removing material. This removing material was cut into 25 cm ² and immersed in 50 cc of an aqueous solution containing 10,000 E. coli / ml. When a 20 w fluorescent lamp was irradiated from a distance of 30 cm in this state, the E. coli concentration decreased to 250 cells / ml after 5 hours. On the other hand, when the titanium oxide was loaded from the titania sol but was not irradiated with light, or when a non-woven fabric that was irradiated with light but was not impregnated was used, the Escherichia coli concentration was increased rather than decreased.

Example 4 A titania sol impregnated solution was prepared by diluting the titania sol stock solution prepared in Example 1 to a titanium oxide concentration of 20% by weight and further adding the surfactant used in Example 1. The non-woven fabric prepared in Example 1 was impregnated with this sol, immersed in an alkaline aqueous solution of pH 13 in which sodium hydroxide was dissolved, and then dried at 60 ° C. for 5 minutes. The amount of titanium oxide that could be supported on the non-woven fabric was 19.5 g / m ² , but some titanium oxide fell off during handling. When the produced photoreactive harmful substance removing material was observed with an electron microscope, aggregates of titanium oxide of 50 μm or more were confirmed.

120 cm of this sheet as in Example 1
It was cut into a size of ² and placed in a 5.6 liter sealable container. About 200 pp of acetaldehyde in this container
Then, the change in the concentration of acetaldehyde in the container was measured over time while irradiating with a black lamp. Similarly, the titanium oxide-supported non-woven fabric prepared above was placed in a closed container together with acetaldehyde and was not irradiated with light. As a result, when the titanium oxide-supported nonwoven fabric was irradiated with a black lamp, acetaldehyde was exposed to 40 p after 30 minutes.
Those who did not irradiate with light decreased to pm 160ppm
Met.

This is because the titanium oxide has a weak gas adsorbing ability regardless of the presence or absence of light irradiation, and the acetaldehyde concentration was lower than in Example 1 because the absolute amount of titanium oxide was large when light irradiation was not performed. On the other hand, if light irradiation is performed, Example 1
Although it had a sufficient photocatalytic ability as in Example 1, the removal efficiency compared with the absolute amount of titanium oxide was inferior to that of Example 1 probably because the size of titanium oxide in the secondary aggregate was large.

[0035]

As described above, according to the present invention, by irradiating light, a low concentration of harmful substances such as a bad odor in the air can be removed, and a sheet-like photoreactive harmful substance having a bactericidal property can be removed. An object removing material can be provided at low cost. If this non-woven fabric contains thermoplastic resin fibers, this photo-reactive harmful substance removing material can also be laminated with other thermoplastic non-woven fabrics at a low cost, for example, with another design and texture. It can also be laminated with an excellent breathable nonwoven fabric such as.

Such a photoreactive harmful substance removing material can be easily removed by simply cutting it to an appropriate size, placing it in a place where it is desired to remove the harmful substance, and irradiating it with light. It can be used easily according to the amount of harmful substances and the place of installation, especially for the removal of low-concentration harmful substances. Therefore, the photoreactive harmful substance removing material of the present invention can be installed, for example, in the back seat of an automobile or near an air conditioner, in a shoe box, a refrigerator, a locker, a closet, or on a hanger indoors or in a bed. It can be laid on a (mattress) and used easily in a hospital, or it can be used as a blind or curtain inside or in a car. Further, it is effective not only in such a sealed space but also in a ventilation place such as a discharge port of a vacuum cleaner or a garbage dryer to be used as a filter. Further, since it has antibacterial properties and the like, it can be used for sterilization of water supply and for preventing deterioration of water quality in baths, pools and the like, and also as antibacterial wallpaper and floor sheet materials for hospitals and the like.

Claims (5)

[Claims] 1. A photoreactive harmful substance removing material, characterized in that titanium oxide precipitated from titania sol is supported on a non-woven fabric. 2. The photoreactive harmful substance removing material according to claim 1, wherein the precipitated titanium oxide is carried on the surface of the non-woven fabric in a size of 10 μm or less and adsorbed and carried. 3. The photoreactive harmful substance removing material according to claim 1, wherein the raw material fibers of the nonwoven fabric supporting titanium oxide precipitated from titania sol contain at least one of a thermoplastic resin fiber and a glass fiber. 4. After impregnating a non-woven fabric with titania sol,
A method for producing a photoreactive harmful substance removing material, which comprises carrying out alkali treatment to deposit titanium oxide to support titanium oxide on the nonwoven fabric. 5. The method for producing a photoreactive harmful substance removing material according to claim 4, wherein alkali precipitation of titanium oxide from the titania sol is carried out using an aqueous solution containing an alkali metal hydroxide or carbonate.