Fiber fabric exhibiting photocatalytic function to visible light and its manufacturing method

The present invention relates to a visible light type photocatalytic functional fiber fabric capable of exhibiting photocatalytic activity even under a light source such as a fluorescent lamp having a large amount of visible light and a small amount of ultraviolet rays, and a method for producing the same.

In recent years, functional fiber products have been proposed that can exhibit deodorant function, antibacterial function, protein stain decomposition function such as sebum (hereinafter referred to as sebum stain decomposition function), etc. by imparting fine particles having photocatalytic activity to the fiber fabric. Has been done. This functional textile product utilizes the fact that malodorous substances and harmful substances existing around the textile product are decomposed by the strong oxidizing action of OH radicals generated by the action of ultraviolet rays on the photocatalyst.

However, when fine particles having photocatalytic activity are fixed to the fiber fabric, the first problem is that the fixed fibers themselves and the binder used for fixing are decomposed by the photocatalytic activity. That is, when the fiber or the binder is decomposed, the durability of the function of the functional fiber is not maintained, and the decomposition gas causes a foul odor.

In addition, textile products are generally washed and used continuously. After washing, textile products are often dried indoors under fluorescent lights as well as when they are dried under strong sunlight. In recent years, there has been a great demand for indoor drying, and at this time, a foul odor may be generated in the textile product. In this case, the light of the fluorescent lamp has less ultraviolet rays than the sunlight, the photocatalytic activity is not sufficiently exhibited, and the sufficient deodorizing function, antibacterial function, sebum stain decomposition function, etc. cannot be obtained. Problems occur.

As a method for solving these two problems at the same time, the functional fiber fabric described in Patent Document 1 below has been proposed. This functional fiber fabric is characterized in that the visible light photocatalyst is fixed to the fiber fabric with a cellulosic binder and / or a polysaccharide binder.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2004-137611</text></patcit>

<p> By the way, in the above-mentioned functional fiber cloth, a specific photocatalyst having photocatalytic activity by visible light by introducing nitrogen into titanium dioxide is used as a fiber cloth with a specific binder such as a cellulosic binder and / or a polysaccharide binder. It is fixed.</p><p> That is, the specific photocatalyst has strong photocatalytic activity not only under visible light but also under ultraviolet light as in the conventional photocatalyst. Therefore, even in this case, the specific binder is required so that the fibers and the binder are not decomposed.</p><p> Further, as the binder for fixing the photocatalyst to the fiber, it is necessary to select the optimum binder according to the fiber from the viewpoint of the durability of the photocatalyst activity and the texture of the fiber cloth.</p><p> However, limiting to a specific binder as described above causes a problem that the photocatalyst cannot be widely used for any fiber.</p><p> Therefore, the present invention copes with the above-mentioned matters and is a source of a light source such as a fluorescent lamp which has a large amount of visible light and a small amount of ultraviolet rays, in which fibers and binders are not easily decomposed even under strong sunlight. However, it is an object of the present invention to provide a visible light type photocatalytic functional fiber cloth having sufficient photocatalytic activity capable of exerting a deodorizing function, an antibacterial function, a sebum stain decomposition function, and the like of the fiber cloth, and a method for producing the same.</p>

<p> In order to solve the above problems, in the visible light type photocatalytic functional fiber cloth according to the present invention, according to the description of claim 1, zinc oxide fine particles having a cumulative 90% average secondary particle size of 1 μm or less are used in the fiber cloth. It is fixed with a binder.</p><p> According to this, fibers and binders are not easily decomposed even in strong sunlight, and even under fluorescent lamps with a lot of visible light and little ultraviolet rays, the deodorant function, antibacterial function, and sebum stains of the fiber cloth. It is possible to exhibit sufficient photocatalytic activity capable of exerting a decomposition function and the like.</p><p> Here, in the present invention, as described in claim 2, the primary particle size of the zinc oxide fine particles according to claim 1 may be within the range of 5 nm to 60 nm.</p><p> Further, in the method for producing a visible light type photocatalytic functional fiber fabric according to the present invention, according to the description of claim 3, the cumulative 90% of the zinc oxide fine particles have an average secondary particle diameter of 1 μm or less. A treatment liquid obtained by mixing an aqueous dispersion liquid and an aqueous dispersion liquid of a binder is applied to the fiber cloth to produce a visible light type photocatalytic functional fiber cloth.</p><p> This makes it possible to produce a visible light type photocatalytic functional fiber fabric in which the effects of the invention according to claim 1 can be achieved. Further, by producing the visible light type photocatalyst functional fiber cloth in this way, it is possible to arbitrarily select the optimum binder for fixing the photocatalyst to the fiber cloth according to the fiber.</p><p> Here, in the present invention, as described in claim 4, the primary particle size of the zinc oxide fine particles according to claim 3 may be within the range of 5 nm to 60 nm.</p>

Hereinafter, an embodiment of a visible light type photocatalytic functional fiber fabric according to the present invention will be described. In the present invention, zinc oxide fine particles, which are visible light type photocatalysts, are fixed to the fiber cloth.

The fibers used in this fiber fabric are not particularly limited, and may generally be used as clothing or industrial materials. For example, polyester, synthetic fibers such as nylon and acrylic, semi-synthetic fibers such as acetate, natural cellulose fibers such as cotton and linen, regenerated cellulose fibers such as rayon, cupra, polynosic or tencel, and protein fibers such as wool and silk. and so on.

As these fibers, two or more kinds of fibers such as single or mixed fibers, mixed fibers, mixed weaving, and mixed knitting may be mixed in an arbitrary ratio. Further, the fiber fabric of the present invention may be in any form such as a knitted fabric, a woven fabric, or a non-woven fabric made of the above fibers.

In the present invention, the photocatalyst refers to a substance that decomposes organic substances by using ultraviolet rays such as sunlight and exhibits photocatalytic activity such as deodorant function, antibacterial function and antifouling function. Semiconductor materials are generally used for this material, and titanium dioxide is particularly widely used.

Further, in the present invention, the visible light type photocatalyst refers to a substance that exhibits the above photocatalytic activity not only by ultraviolet rays but also by visible light. This substance includes a substance in which another element such as nitrogen is introduced into titanium dioxide.

Both of these conventional ultraviolet type photocatalysts and visible light type photocatalysts exhibit strong photocatalytic activity under ultraviolet rays. Therefore, the fixed fiber or binder of the photocatalyst is an organic substance and is decomposed. Therefore, any binder is not durable, or on the contrary, a foul odor is generated by the decomposition gas.

Therefore, as a result of diligent research, the present inventor has made arbitrary use of zinc oxide fine particles having a specific particle size as a visible light type photocatalyst without decomposing fibers and binders even under ultraviolet rays. It has been found that fibers and arbitrary binders can be used, and that photocatalytic activities such as deodorizing function, antibacterial function and sebum stain decomposition function can be exhibited even under visible light.

Here, zinc oxide used in the present invention is a kind of semiconductor, and its photocatalytic activity under ultraviolet rays is known. However, under ultraviolet rays, its photocatalytic activity is lower than that of titanium dioxide, and it is not generally used as a photocatalyst.

The present inventor investigated the photocatalytic activity of zinc oxide fine particles having a specific particle size, and exhibited the photocatalytic activity such as deodorizing function, antibacterial function and sebum stain decomposition function even under a fluorescent lamp having a large amount of visible light and a small amount of ultraviolet rays. It was found that it exerts its full potential and exhibits photocatalytic activity under ultraviolet rays such as sunlight, but its activity is not strong enough to decompose fibers and binders.

That is, in the visible light type photocatalytic functional fiber cloth according to the present invention, zinc oxide fine particles having a cumulative 90% average secondary particle diameter of 1 μm or less are fixed to the fiber cloth with a binder to solve the problem of the present invention. Can be achieved.

In the present invention, zinc oxide exists in the form of secondary particles aggregated on the fiber. This is applied as a treatment liquid in a dispersed state when the primary particles of zinc oxide ultrafine particles are applied to the fibers. In the dispersion liquid, the zinc oxide ultrafine particles exist in an aggregated state and form secondary particles to be stably dispersed. It is applied and fixed on the fiber in the form of the secondary particles.

The zinc oxide fine particles fixed to the fibers are in the form of secondary particles in which the primary particles are aggregated, and the average secondary particle size of the cumulative 90% is 1 μm or less. Since the secondary particles are aggregated particles, they have a particle size distribution in a certain range. Specifically, it is preferable to show a particle size distribution within the range of 0.02 μm to 1.2 μm. In this case, the cumulative 50% average secondary particle size is preferably 0.1 μm or less.

Here, the particle size of the zinc oxide secondary particles in the dispersion can be measured by various measuring methods. For example, it can be measured by a dynamic light scattering type particle size distribution measuring device. Examples of this dynamic light scattering type particle size distribution measuring device include MICROTRAC UPA (model: 9340-UPA150) manufactured by Nikkiso Co., Ltd.

The zinc oxide primary particles used in the present invention preferably have a particle size within the range of 5 nm to 60 nm. More preferably, it is in the range of 10 nm to 30 nm.

Due to the small particle size of the primary particles, the specific surface area of zinc oxide as a photocatalyst increases. It seems that much of the surface area of the primary particles works even if they are agglomerated into the secondary particles.

As a result, zinc oxide, which has conventionally been considered to have a small photocatalytic activity, can have sufficient photocatalytic activity capable of exerting a deodorizing function, an antibacterial function, a sebum stain decomposition function, and the like of the woven fabric.

Further, even with this particle size, the characteristic that the fibers and the binder are not easily decomposed under the strong sunlight of ultraviolet rays is maintained.

On the other hand, the binder used in the present invention is not particularly limited, but is selected from the viewpoint of adhesiveness and texture between zinc oxide and fibers. Generally, acrylic resin, fluororesin, silicone resin, polyester resin, nylon resin, urethane resin and the like are used. From the viewpoint of the adhesiveness to the zinc oxide to be fixed and the adhesiveness to the fiber to be fixed, the optimum binder of the fiber is arbitrarily selected in consideration of washing durability and texture.

Next, a method for producing a visible light type photocatalytic functional fiber fabric will be specifically described. A dispersion of the above zinc oxide fine particles is prepared. This dispersion may be an aqueous dispersion or an organic solvent dispersion. An aqueous dispersion is preferable for normal fiber processing.

Specifically, a dispersant is used to disperse zinc oxide ultrafine particles having a primary particle diameter within the range of 5 nm to 60 nm in water. As the dispersant, various commonly used surfactants can be used. The active ingredient of zinc oxide in the dispersion can be adjusted arbitrarily, but is usually in the range of 10% by weight to 40% by weight, for example. The zinc oxide fine particles in the aqueous dispersion are stably dispersed in water as aggregated secondary particles.

On the other hand, the aqueous dispersion of the binder is also obtained by emulsifying and dispersing the above-mentioned various resins in water using a dispersant. This also usually has a solid content in the range of, for example, 10% to 40% by weight.

The aqueous dispersion of the binder is mixed with the aqueous zinc oxide dispersion, and the concentration of each component is arbitrarily adjusted by diluting with water. The mixed solution of the above zinc oxide aqueous dispersion and the binder aqueous dispersion is used as the treatment solution.

If necessary, the treatment liquid may be mixed with a binder cross-linking agent, a catalyst, or a fiber processing aid such as a fiber softener or a dye fixing agent.

The actual processing of the fiber fabric will be described. The fiber fabric to be processed is pretreated in advance by smelting, bleaching or the like by a usual method. Further, in the case of general clothing, the processing of the present invention can be performed after dyeing.

First, the fiber cloth is impregnated with the aqueous treatment liquid. The impregnation may be performed by any known method such as a pad method, a spray method or a coating method.

The larger the amount of zinc oxide fine particles imparted to the fiber fabric, the greater the photocatalytic activity, but in reality, the active ingredient as zinc oxide is in the range of 0.1% by weight to 3.0% by weight, preferably within the range of the fiber weight. It is within the range of 0.1% by weight to 1.0% by weight. When the amount of zinc oxide is within the range of 0.1% by weight to 3.0% by weight, sufficient deodorizing and antibacterial functions can be exhibited even under fluorescent lighting, and the fiber fabric can be washed while maintaining a good texture. Durability can be obtained.

After the above impregnation, the fiber cloth is dried and heat-treated if necessary. The conditions for drying and heat treatment are appropriately selected, but are usually performed within the range of 100 ° C to 180 ° C, preferably within the range of 100 ° C to 160 ° C. The drying time is appropriately selected in relation to the temperature, but is usually performed within a range of 10 seconds to 5 minutes, preferably within a range of about 30 seconds to 3 minutes.

The fiber fabric is dried, dried, heat-treated, left as it is, or washed with water if necessary, and then used.

As a result, the fiber cloth processed as described above is a fiber cloth that does not easily decompose fibers and binders even under strong sunlight and even under a fluorescent lamp having a large amount of visible light and a small amount of ultraviolet rays. It is possible to obtain a visible light type photocatalytic functional fiber cloth having sufficient photocatalytic activity capable of exerting a deodorizing function, an antibacterial function, a sebum stain decomposition function and the like. This makes it possible to arbitrarily select the optimum binder for fixing the photocatalyst to the fiber fabric according to the fiber.

Hereinafter, in the present embodiment, the following examples and comparative examples were prepared and evaluated.

Example 1: In this example, zinc oxide fine particles are fixed to a cotton fabric with an acrylic binder.

Zinc oxide ultrafine particles having a primary particle size in the range of 10 nm to 30 nm were dispersed in water using an anionic emulsifier. The zinc oxide solid content in the zinc oxide aqueous dispersion was 30% by weight. The cumulative 90% average secondary particle size of the zinc oxide aqueous dispersion was 0.8 μm, and the cumulative 50% average secondary particle size was 0.08 μm.

Prepare a treatment solution by mixing 2% by weight of the above zinc oxide aqueous dispersion and 2% by weight of a commercially available acrylic resin aqueous dispersion (Toyo Ink Co., Ltd. Tokril 0-125; solid content 30% by weight) and diluting with water. did.

The 100% cotton woven fabric smelted and bleached by a usual method was dipped and squeezed with the above-mentioned treatment liquid by a pad method, and applied with a pickup of 60% with respect to the weight of the test cloth.

After applying the treatment solution, the test cloth was dried at 120 ° C. for 90 seconds. Subsequently, the test cloth of Example 1 was obtained by heat treatment at 150 ° C. for 90 seconds.

Comparative Example 1: In this Comparative Example, the visible light type titanium dioxide fine particles are fixed to the same cotton fabric as in Example 1 with the same acrylic binder as in Example 1.

Nitrogen-introduced titanium dioxide ultrafine particles having a primary particle size in the range of 10 nm to 20 nm were dispersed in water using an anionic emulsifier. The zinc oxide solid content in the zinc oxide aqueous dispersion was 10% by weight. The cumulative 90% average secondary particle size of the zinc oxide aqueous dispersion was 0.6 μm, and the cumulative 50% average secondary particle size was 0.3 μm.

6% by weight of the above zinc oxide aqueous dispersion and 2% by weight of a commercially available acrylic resin aqueous dispersion (Toyo Ink Co., Ltd. Tokril 0-125; solid content 30% by weight) are mixed and diluted with water to prepare the treatment solution. Got ready. The treatment method was the same as in Example 1 above to obtain a test cloth of Comparative Example 1.

Comparative Example 2: In this Comparative Example, the ultraviolet type titanium dioxide fine particles are fixed to the same cotton fabric as in Example 1 with the same acrylic binder as in Example 1.

Commercially available anatase-type titanium dioxide ultrafine particles were dispersed in water using an anionic emulsifier. The zinc oxide solid content in the zinc oxide aqueous dispersion was 10% by weight.

6% by weight of the above zinc oxide aqueous dispersion and 2% by weight of a commercially available acrylic resin aqueous dispersion (Toyo Ink Co., Ltd. Tokril 0-125; solid content 30% by weight) are mixed and diluted with water to prepare the treatment solution. Got ready. The treatment method was the same as in Example 1 above to obtain a test cloth of Comparative Example 2.

The characteristics of each of the Examples and Comparative Examples prepared as described above were evaluated. In this evaluation, the photocatalytic activity under visible light and ultraviolet rays was evaluated as an evaluation item.

The photocatalytic activity was carried out by the following method. Cut the unprocessed cloth and each test cloth of Examples and Comparative Examples into 10 cm × 5 cm, add a 0.03 g / L aqueous solution of methylene blue, and irradiate with visible light or ultraviolet rays. Visible light irradiation was performed at 8000LX under fluorescent light for 4 hours. UV irradiation is performed under black light with an ultraviolet intensity of 2000 μW / cm.²I went there for 2 hours. The photocatalytic activity is determined by the fading of the blue color of the methylene blue.

The color of methylene blue of the test cloth after irradiation was compared to evaluate the photocatalytic activity. The evaluation criteria were evaluated on a four-point scale: very strong photocatalytic activity (), good photocatalytic activity (), weak photocatalytic activity (Δ), and no photocatalytic activity (×).

The decomposition of the fiber and the binder was evaluated by the washing durability of the photocatalytic activity. That is, the test cloth after light irradiation was washed, and the degree of decrease in photocatalytic activity after repeating the cycle consisting of light irradiation and washing 20 times was evaluated. The laundry was done at home in accordance with JIS L 0217 103 law.

In addition, the deodorant function, antibacterial function, and sebum stain decomposition function of these test cloths were confirmed. As a result, it was confirmed that there is sufficient functionality in the above evaluation criteria ().

According to these evaluations, the evaluation results shown in Table 1 below were obtained.

<tables num="1"><img file="JP2007136342A_D0001.tif" /></tables>

According to this Table 1, Example 1 has good photocatalytic activity under both visible light and ultraviolet light. In addition, good photocatalytic activity is maintained even after irradiation washing.

On the other hand, Comparative Example 1 has good photocatalytic activity under visible light, but the photocatalytic activity is too strong under ultraviolet light, and the photocatalytic activity cannot be maintained after washing by irradiation with ultraviolet light. ..

On the other hand, Comparative Example 2 cannot exhibit photocatalytic activity under visible light. In addition, the photocatalytic activity is too strong under ultraviolet rays, and the photocatalytic activity cannot be maintained after washing by irradiation with ultraviolet rays.