JP2005105509A - Sheet containing titanium dioxide and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet containing titanium dioxide, exerting sufficient oxidizing ability. <P>SOLUTION: The sheet containing titanium dioxide is obtained by soaking a sheet comprising fibers into water, then soaking the obtained in a soaking liquid comprising porcelain clay, water and titanium dioxide and drying the resultant. Thereby, the titanium dioxide is impregnated in the sheet and fixed, and so the sheet exerts sufficient oxidizing ability. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a titanium dioxide-containing sheet and a method for producing the same.

  Conventionally, titanium dioxide has been known to have photocatalytic activity, decompose organic compounds, and exhibit a bactericidal action. This mechanism is considered as follows.

  When titanium dioxide is irradiated with light of a predetermined wavelength, electrons in the titanium dioxide are excited from the valence band to the conduction band. At this time, holes are generated in the valence band, and electrons are taken away from surrounding water molecules. At this time, it is considered that hydrogen ions and hydroxyl (OH) radicals are generated. In addition, it is considered that excited electrons react with surrounding oxygen molecules to generate oxygen radicals, and react with the hydrogen ions to generate hydroxyl peroxide (OOH) radicals. These radicals have strong oxidizing power, and it is considered that the organic compounds and the like are decomposed or a bactericidal action is exhibited by the radicals.

  Note that the energy level of holes in the titanium dioxide is +3.0 V with respect to the hydrogen reference potential, and chlorine used as an oxidizing agent is generally +1.3 V and ozone is +2.07 V. From the strength of the oxidizing power of titanium dioxide, it is considered that the decomposition of organic compounds and the bactericidal action can be explained.

  By the way, in order to express the oxidizing power of the titanium dioxide more, it is preferable that the surface area is larger. For this reason, it is possible to use titanium dioxide as fine particles. For this reason, a method of fixing the titanium dioxide fine particles by kneading into a synthetic resin or the like is conceivable.

  However, when kneaded into a synthetic resin or the like, titanium dioxide was buried inside the synthetic resin or the like, and a sufficient oxidizing power could not be exhibited.

  Then, this invention aims at providing the titanium dioxide containing sheet | seat which exhibits sufficient oxidizing power.

  The present invention solves the above-mentioned problems by impregnating a sheet composed of fibers with water, then impregnating it with an impregnation liquid containing clay for clay, water, and titanium dioxide, followed by drying.

  Since a predetermined sheet impregnated with water in a predetermined impregnating solution is immersed, this sheet can be impregnated with titanium dioxide and fixed, and sufficient oxidizing power can be exhibited.

The present invention will be described in detail below.
The titanium dioxide-containing sheet according to the present invention is formed of a sheet composed of fibers, clay for clay, titanium dioxide, and optionally lignin, impregnated with the sheet composed of the above fibers in water, It is produced by impregnating with an impregnating liquid to which clay for clay, water, titanium dioxide, and lignin as necessary are added, and then drying.

  The sheet composed of the above fibers (hereinafter simply referred to as “sheet”) is a sheet in which fibers are used as structural units, and specific examples include woven fabrics and non-woven fabrics.

  Examples of the fibers include natural fibers, semi-synthetic fibers, and synthetic resin fibers. Examples of the natural fibers include fibers such as cotton, silk, cotton, pulp and cellulose fibers, and wood fibers such as rayon. Furthermore, examples of the semi-synthetic fiber include acetate fiber and triacetate fiber. The synthetic resin fiber refers to a polyolefin fiber made of polyolefin such as polyethylene, polypropylene, polystyrene or the like, a fiber made of nylon fiber, polyester fiber, acrylic fiber, polyurethane fiber or the like.

  In addition, when comprising the said sheet | seat, the fiber used may be either said fiber single, and may combine the said fiber.

  The clay for porcelain is an aggregate of fine hydrous silicate minerals, which is a component that produces plasticity when mixed with an appropriate amount of water, and contributes to fixing and fixing of the titanium dioxide. Examples of the components constituting this clay for clay include kaolin, bentonite, talc, mica, montmorillonite, vermiculite, kibushi clay, gyrome clay and the like. The clay for porcelain is a raw clay for producing ceramics and porcelain by firing at a high temperature. The content of the clay varies depending on the production area, and has properties unique to the production area. Examples of production areas of this clay are Karatsu City, Saga Prefecture, Seto City, Aichi Prefecture, Mitsuda City, Hyogo Prefecture, Shigaraki Town, Shiga Prefecture.

  The clay for clay is calcined at 800 ° C. or lower, preferably 80 to 500 ° C., more preferably 100 to 300 ° C., if necessary. By baking the viscosity for porcelain clay, the state of running out of water becomes better, and drying becomes easier at the time of molding described later.

  The clay for clay is adjusted in particle size by grinding or sieving as required. The average particle diameter of the clay for clay thus obtained is preferably 1 to 100 nm, and preferably 10 to 50 nm. If it is smaller than 1 nm, it may take time to suspend in water. On the other hand, if it is larger than 100 nm, the fixing property of titanium dioxide may be insufficient.

  The clay for porcelain serves as an adhesive for the titanium dioxide, and in some cases, the components contained in the clay for porcelain can cause a dark reaction of titanium dioxide and exhibit photocatalytic activity. . This dark reaction refers to a reaction that exerts photocatalytic activity in the absence of light. This dark reaction can be caused by irradiating light in advance.

  The titanium dioxide mainly contains an anatase type crystal structure, and fine ones such as powder and granules are preferable. The content of titanium dioxide having the anatase type crystal structure is preferably 50% or more, preferably 80% or more, and more preferably 90% or more with respect to the entire titanium dioxide. Even if the anatase type crystal structure is less than 50%, there is no problem as long as it has photocatalytic activity, but it is not economical because the amount of titanium dioxide used increases. Furthermore, the higher the content ratio of the anatase type crystal structure, the more preferable it is because the photocatalytic activity can be exerted more strongly.

  The titanium dioxide is calcined at 800 ° C. or lower, preferably 80 to 500 ° C., more preferably 100 to 300 ° C., if necessary. Since a calcination temperature shall be 800 degrees C or less, the anatase type of the said titanium dioxide is hold | maintained and photocatalytic activity is hold | maintained. Furthermore, you may bake, after mixing with the said clay for clay.

  The titanium dioxide can be adjusted in particle size by grinding or sieving as required. The average particle diameter of the titanium dioxide particles is preferably 1 to 100 nm, and preferably 10 to 50 nm. If it is smaller than 1 nm, it may take time to suspend in water. On the other hand, if it is larger than 100 nm, the degree of expression of the photocatalytic activity in a certain amount of titanium dioxide used may not be sufficient.

  In addition, when the said titanium dioxide mixture is baked, you may add the particle | grains of the said unsintered titanium dioxide newly as needed. Thereby, the photocatalytic activity of the titanium dioxide containing composition obtained can be improved more. The amount of the newly added titanium dioxide particles added is preferably 50% by weight, preferably 1 to 30% by weight, based on the titanium dioxide mixture. If it is more than 50% by weight, titanium dioxide may fall off when the resulting titanium dioxide-containing composition is molded into a molded body.

The specific surface area of the titanium dioxide particles is not particularly limited but is preferably 50 to 300 m ² / g. If it is less than 50 m ² / g, the degree of expression of photocatalytic activity in a certain amount of titanium dioxide used may not be sufficient. On the other hand, it may be larger than 300 m ² / g, but such a product may be difficult to obtain because it is difficult to manufacture.

  The above lignin is a kind of component constituting mushrooms such as plants such as trees, litchi and birch, and is a compound mainly composed of aromatic compounds.

  The impregnation liquid is a mixture of the clay for clay, water, titanium dioxide, and lignin as necessary, and suspended. Although the addition amount of the clay for clay is not particularly limited, 0.5 to 50 parts by weight is preferable, 1 to 20 parts by weight is preferable, and 2 to 10 parts by weight is more preferable with respect to 1000 parts by weight of water. When the amount of clay for clay is too small, the fixability of the titanium dioxide to the sheet tends to be lowered. On the other hand, although it may be too much, the fixability of the titanium dioxide to the sheet does not increase in proportion to the amount of addition, so about 50 parts by weight is sufficient.

  The amount of titanium dioxide added is not particularly limited, but is preferably 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight, and more preferably 2 to 10 parts by weight with respect to 1000 parts by weight of water. If the amount of titanium dioxide added is too small, the effect of the photocatalytic activity of the obtained titanium dioxide-containing sheet may not be sufficiently exhibited. On the other hand, although it may be too much, there is a tendency for the amount of titanium dioxide not fixed to the sheet to increase.

  Although the addition amount of the said lignin is not specifically limited, When using, 0.01-10 weight part is preferable with respect to 100 weight part of titanium dioxide, and 0.1-5 weight part is preferable. The amount of lignin added may be less than 0.01 parts by weight, but by setting it to 0.01 parts by weight or more, the fixability of titanium dioxide to the sheet can be further improved. On the other hand, when the amount is more than 10 parts by weight, the resulting titanium dioxide-containing sheet is intensely colored, and the finish tends to deteriorate.

  The water used for the impregnation liquid is not particularly limited, and pure water such as distilled water and reverse osmosis water, water containing a trace amount of metal components such as ground water, and the like may be used. it can.

  The impregnating liquid is impregnated with the sheet, which is impregnated with water in advance. Thereby, it can prevent that a bubble intervenes between a sheet | seat and titanium dioxide or clay for clay, and can improve the joining property of the said sheet | seat and titanium dioxide. The water used at this time is the same as that used in the above impregnating liquid.

  The impregnation time of the sheet in the impregnation liquid is not particularly limited, and 1 to 24 hours is sufficient. The impregnation temperature may be room temperature. After impregnation, the sheet is pulled up from the impregnation liquid and dried to obtain the titanium dioxide-containing sheet according to the present invention. Examples of the drying method include sun drying and drying with a dryer.

  It is more preferable to perform the above-mentioned sun drying because the photocatalytic activity of the titanium dioxide contained can be improved. Moreover, when drying using a dryer, it is preferable to dry at 300 degrees C or less, and it is more preferable to dry at 200 degrees C or less. When the temperature exceeds 300 ° C., depending on the type of fiber constituting the sheet, the change may occur, which may not be preferable.

  The impregnating liquid can contain metal powder as necessary. Even when the clay is not exposed to light, the clay for clay described above can exert photocatalytic activity due to the dark reaction of titanium dioxide by the components contained, but by mixing this metal powder and metal pieces, This is because the photocatalytic activity due to the dark reaction of titanium dioxide can be more effectively exhibited.

  The metal which comprises this metal powder is not specifically limited, For example, iron, copper, silver, gold | metal | money, aluminum, magnesium, nickel, zinc etc. are mention | raise | lifted. Although the magnitude | size of the said metal powder is not specifically limited, The magnitude | size which can be disperse | distributed in the said impregnation liquid is good.

  Although the metal powder in the said impregnation liquid is not specifically limited, 0.001-10 weight part is good with respect to 1000 weight part of water, and 0.01-5 weight part is preferable. If it is less than 0.001 part by weight, a sufficient dark reaction may not occur. On the other hand, it may be more than 10 parts by weight, but if it is added more, the degree of photocatalytic activity does not increase so much, and about 10 parts by weight is sufficient.

  By the way, said titanium dioxide containing sheet | seat is combined with a metal piece, metal powder, metal foil, a metal film, a metal sheet, a metal plate etc. (henceforth "metal piece etc.") as needed. May be used. These may be of a single type or may be of a plurality of types. Furthermore, you may affix, laminate | stack, or spray 1 type or multiple types, such as the said metal piece, to a part or all of the said titanium dioxide containing sheet | seat. As a metal used for said metal piece etc., the metal used for the above-mentioned metal powder and metal piece is mention | raise | lifted. By using the above metal piece or the like, the dark reaction can be performed more effectively.

  Said titanium dioxide containing sheet | seat exhibits photocatalytic activity by the anatase type titanium dioxide to contain, especially the exposed anatase type titanium dioxide. The photocatalytic activity refers to an oxidizing power that is expressed by irradiating general light such as sunlight (that is, sunlight), ultraviolet light, fluorescent light, incandescent light, and the like. In particular, when irradiating light such as ultraviolet rays having a wavelength of 380 nm or less, the oxidative power expressed becomes larger.

  In addition, as described above, the dark reaction can be made to exhibit photocatalytic activity in the absence of light by irradiating light in advance as described above. That is, general light such as sunlight), ultraviolet light, light from fluorescent lamps, incandescent lamps, and the like. In particular, in order to more strongly exert the photocatalytic activity, it is preferable to irradiate light such as ultraviolet light having a wavelength of 380 nm or less among the above light.

  Moreover, since it will improve the photocatalytic capability of titanium dioxide when the said titanium dioxide containing sheet | seat is put in a humidification state, it is more preferable to use humidifiers, such as an automatic humidification adjustment apparatus, together.

  Such photocatalytic activity includes decomposition of residual organic substances such as tannic acid, formaldehyde, pollen, agricultural chemicals, dioxin, phenol, and environmental hormones, decomposition of inorganic malodorous gases such as ammonia, decomposition of tobacco odor, nitrogen oxide (NOx) ), Microorganisms such as yeast and bacteria, fungicides and fungi such as mites and mites, and mites and functions of these dead bodies.

  The titanium dioxide-containing sheet produced by the above production method can be used for various applications. Installed in general households, offices, factories, etc., automobiles, buses, airplanes and other vehicles, toilets, etc., for wallpaper, decorative paper, interior decoration, photocatalytic deodorant, photocatalytic air It can be used as a cleaning material, NOx decomposition material, sterilization / mold prevention member, organic material decomposition material, and the like.

  Specific examples include a mask and a filter containing the titanium dioxide. In the case of the above titanium dioxide-containing mask, as a mask having a sterilizing action and a deodorizing action due to the photocatalytic activity of titanium dioxide, that is, as a photocatalytic deodorizing material, a photocatalytic air cleaning material, a sterilizing / antifungal member, an organic matter decomposing material, etc. Can be used.

  In addition, in the case of the titanium dioxide-containing filter, various components such as NOx in the exhaust gas can be removed by attaching an air purifier using this filter to the exhaust port of a vehicle, the tunnel or the exhaust port of various structures. It can be used as a photocatalytic deodorant material, a photocatalytic air cleaning material, a NOx decomposition material, a sterilization / mold prevention member, an organic matter decomposition material, and the like.

  Furthermore, when using a blanket made of fibers such as acrylic fibers as the sheet, it is possible to remove ticks and pests that tend to occur in bedding by containing and fixing titanium dioxide by the above-described method. It can be used as an anti-mold member.

The present invention will be described more specifically with reference to the following examples.
(Manufacture of impregnating liquid)
Clay for clay (from Shigaraki Town, Shiga Prefecture) was baked at 200 ° C. for 24 hours. The obtained clay for clay was pulverized to form fine particles. Among these, 5 parts by weight with a mean particle size of about 20 to 30 nm as the center, and titanium dioxide particles (Fuji Titanium Industry Co., Ltd. 1500D, crystal type: anatase, purity 90% by weight, specific surface area 200 m ² / g, 5 parts by weight (average particle size: 20 to 30 nm) was added to 1000 parts by weight of water and kneaded with a mixer to produce an impregnating solution.

(Examples 1-3)
Each of the commercially available masks (made of polyester and polyethylene, made of polyester and polypropylene, and made of cotton) was immersed in the above impregnating solution for 3 hours, then pulled up and dried in the sun all day and night.

Example 4
Toray Industries, Inc .: A non-woven fabric made of Ecodia was soaked in the above impregnating solution for 3 hours, then pulled up and dried in the sun all day and night.

(Example 5)
The cardboard liner was immersed in the impregnating solution for 3 hours, then pulled up and dried in the sun all day and night.

(Example 6)
5 parts by weight of clay for porcelain with an average particle diameter of about 20 to 30 nm obtained by the above method, 2 parts by weight of a piece of sliced lychee (mushroom), and 5 parts by weight of titanium dioxide particles In addition to 1000 parts by weight of water, the mixture was kneaded with a mixer to produce an impregnating solution.
A liner impregnated with titanium dioxide was obtained in the same manner as in Example 5 except that the obtained impregnation liquid was used.

(Comparative Examples 1-5)
About the sheet | seat (woven fabric or nonwoven fabric) used in Examples 1-5, the case where it used as it was, without performing the impregnation process of titanium dioxide was made into Comparative Examples 1-5.

  Each test was performed according to the following method using each titanium dioxide-containing sheet produced by the above method. The results are shown in Tables 1 and 2. The unit of numerical values in Tables 1 and 2 is “ppm”.

[Degradability test]
Sencha was put on each of the sheets of Examples 1 to 6 containing and fixing titanium dioxide. Immediately after dripping, it turned brown. This was exposed to the sun for 3 hours. As a result, the brown color change described above disappeared and became the original color.
On the other hand, using the respective sheets of Comparative Examples 1 to 5, sencha was dispensed in the same manner. Immediately after dripping, it turned brown. This was exposed to the sun for 3 hours. As a result, in all cases, the discoloration remained as it was.

[Deodorization test]
Each of the above-mentioned titanium dioxide-containing and fixed sheets (woven fabric or non-woven fabric) was cut into 5 × 5 cm, placed in a thermostatic chamber at 20 ° C. and 65% RH, and left under ultraviolet irradiation for 24 hours.
Further, 4 liters of air and 500 μl of 29% ammonia water (manufactured by Kanto Chemical Co., Ltd.) were injected into a 5 liter Tedlar bag, sealed and left for 24 hours to obtain ammonia standard gas.
Next, after putting the cloth cut into the predetermined size into the Tedlar bag, 4 liters of air is injected, and the ammonia standard gas is injected and sealed so that the ammonia concentration in the Tedlar bag is 100 ppm. One Tedlar bag was irradiated with ultraviolet rays.
After 2 hours, the ammonia residual gas amount in the two Tedlar bags was measured with a detector tube (manufactured by Gastec Corporation). Thereafter, the ammonia standard gas was again injected so that the ammonia concentration in the Tedlar bag was 100 ppm. This operation was repeated 4 times, and a total of 5 tests were continuously performed. Table 1 shows the ammonia residual gas amount (unit: ppm) after 30 minutes and 2 hours in each test.

[NOx removal test]
Continuous distribution owned by Osaka Prefectural Institute of Advanced Industrial Science and Technology is the NOx removal performance of the sheet containing and fixing the titanium dioxide described in Examples 4 to 6 or the sheet described in Comparative Example 4 or 5. Measurement was performed according to the method described in JIS R 1701-1 using a NOx removal performance evaluation apparatus (using a low-potential electrolyte sensor).
Table 2 shows the total amount of residual gases of nitrogen dioxide and nitric oxide after 3 hours.

[Acetaldehyde removal test]
The sheet containing and fixing the titanium dioxide described in Examples 4 to 6 above, or the sheet described in Comparative Example 4 or 5 is cut into 5 × 5 cm and placed in a constant temperature and constant chamber at 20 ° C. and 65% RH. Left for 24 hours.
In addition, 4 liters of air and 500 μl of acetaldehyde gas were injected into a 5 liter Tedlar bag, sealed and allowed to stand for 24 hours to obtain an acetaldehyde standard gas.
Next, after putting the cloth cut into the predetermined size into a 5 liter Tedlar bag, 4 liters of air was added, and the acetaldehyde standard gas was injected so that the concentration in the tedlar bag was 100 ppm. The Tedlar bag was irradiated with ultraviolet rays. After 24 hours, the amount of acetaldehyde residual gas in the Tedlar bag was measured with a detector tube (manufactured by Gastec Corporation). The results are shown in Table 2.

Claims (6)

  A method for producing a titanium dioxide-containing sheet, wherein a sheet composed of fibers is impregnated with water, then impregnated with an impregnating liquid containing clay for clay, water, and titanium dioxide, and then dried.   The said impregnation liquid is a manufacturing method of the titanium dioxide containing sheet | seat of Claim 1 containing a lignin.   The titanium dioxide containing mask manufactured by the manufacturing method of the titanium dioxide containing sheet | seat of Claim 1 or 2.   The air cleaner which has a titanium dioxide containing filter manufactured by the manufacturing method of the titanium dioxide containing sheet of Claim 1 or 2.   Titanium dioxide-containing sheet formed from a sheet composed of fibers, clay for clay and titanium dioxide.   A titanium dioxide-containing sheet formed from a sheet composed of fibers, clay for clay, lignin and titanium dioxide.