JP4647334B2 - Photocatalytic liquid composition - Google Patents

Description

  The present invention relates to a liquid composition applied to a fabric substrate to impart photocatalytic activity.

  In recent years, in order to impart deodorant properties, antibacterial properties, and antifouling properties to fabrics, application of photocatalysts to fabric substrates has been studied (see, for example, Patent Documents 1 and 2). A fabric having photocatalytic activity not only exhibits excellent properties per se, but also has an advantage of being useful for purification of an indoor environment when used indoors.

  Titanium oxide is known as a photocatalyst to be applied to a fabric substrate. Titanium oxide is an excellent photocatalytic material, but the following problems occur when it is applied to a fabric. First, under light irradiation, titanium oxide may oxidize and decompose fiber processing agents, flameproofing agents, binders, fabric base materials, etc., and the fabric may turn yellow. Furthermore, malodorous components are produced during this decomposition process, which may hinder the achievement of the photocatalytic purpose of deodorization. In addition, this undesirable side reaction can reduce the catalytic activity.

  In order to prevent the side reaction of the photocatalyst, it has also been reported to use a fabric base material coated with a protective layer of melamine resin (see Patent Document 2). However, there is still a need for a method that can impart photocatalytic activity to a wide range of fabric substrates.

  Regarding the shape of the photocatalyst particles, the smaller the particle size is, the higher the catalytic activity in normal applications. Therefore, particles having a small particle size have been studied for fabric use. For example, in Patent Document 1, titanium oxide having a particle size of 50 nm or less is used. However, the photocatalytic activity of these conventional fabrics is not always sufficient, and further improvements are desired.

As described above, it is required to further improve the photocatalytic activity of a fabric by suppressing discoloration of the fabric under light irradiation.
JP-A-11-323726 JP 2000-328438 A

  This invention is made | formed in view of said situation, and provides the liquid composition apply | coated to a fabric base material in order to provide photocatalytic activity.

  As a result of intensive studies to solve these problems, the present inventors have a core containing a photocatalytic material and a layer covering at least a part of the core, and an average particle size of 0.5 to 10 μm. It was found that by using photocatalyst particles, discoloration of the fabric can be suppressed and excellent photocatalytic activity can be imparted, and the present invention has been completed. The photocatalyst particles used in the present invention have an average particle diameter in a specific range suitable for a fabric, so that excellent catalytic activity is realized, and undesirable side reactions are suppressed by the coating layer.

That is, the present invention provides the following.
(1) A liquid composition comprising a photocatalyst particle having a core containing a photocatalyst material and a layer covering at least a part of the core, and applied to a fabric substrate to impart photocatalytic activity, the photocatalyst The liquid composition as described above, wherein the average particle size of the particles is in the range of 0.5 to 10 μm, and the photocatalytic activity of the material of the coating layer is lower than that of the photocatalytic material of the core.
(2) The liquid composition according to (1), wherein the core contains titanium oxide.
(3) The liquid composition according to (1) or (2), wherein the coating layer contains silica, calcium phosphate, polysiloxane, or a combination thereof.
(4) The liquid composition according to any one of (1) to (3), further including a binder.

  The liquid composition of the present invention contains photocatalyst particles. This photocatalyst particle contains the photocatalyst particle which has the core containing a photocatalyst material, and the layer which coat | covers at least one part of this core, and the photocatalytic activity of the material of this coating layer is low compared with the photocatalyst material of this core. The presence of this coating layer can prevent oxidative decomposition of the fiber processing agent, flameproofing agent, binder, fabric base material and the like by the core.

  The photocatalytic material of the core is not limited and includes titanium oxide, strontium titanate, barium titanate, zinc oxide, tungsten oxide, iron oxide, indium oxide, and zinc sulfide. These may be used alone or in combination. Of these, titanium oxide is preferable. The crystal structure of titanium oxide is not limited and may be any of anatase type, rutile type, brookite type, or amorphous type, but an anatase type having strong activity is preferred. In order to give stronger and more electron-reducing properties, these metals are coated with fine metal particles such as platinum, gold, palladium, silver, copper, zinc, and rhodium, or more strongly oxidizable by holes. Therefore, a metal oxide coating treatment such as ruthenium oxide may be performed, or a visible light responsive photocatalytic material may be used. Here, the photocatalytic material refers to a material that exhibits organic substance decomposition activity or superhydrophilicity when irradiated with light such as ultraviolet light and visible light. The photocatalytic degradation activity under light irradiation can be evaluated by the acetaldehyde degradation test and the methylene blue degradation test described in Examples. However, the target of the photocatalytic reaction is not limited to these compounds.

  The material of the coating layer is not particularly limited as long as it is a material that suppresses side reactions caused by the core and does not inhibit the decomposition of the target product. When the photocatalytic activity of the material alone is measured, the activity is higher than that of the core photocatalytic material. What is necessary is just low and what does not have photocatalytic activity is preferable. Examples of the material for the coating layer include silica, calcium phosphate, polysiloxane, apatite, alumina, and zirconia. These may be used alone or in combination. Among these, silica is preferable. There is no restriction | limiting in particular in the form of coating | cover, You may coat | cover the whole core and may coat a part. The primary particles of the core may be coated, or the secondary particles may be coated.

Examples of the photocatalyst particles having such a coating layer include silica-coated titanium oxide described in JP-A-2002-159865.
The preferred average particle diameter of the coated photocatalyst particles in the liquid composition depends on the thickness of the fibers constituting the fabric and the spacing between the fibers, but usually the average particle diameter of the photocatalyst particles is 0.5 μm or more, preferably 0.8. It is 8 μm or more, more preferably 1.0 μm or more, 10 μm or less, preferably 5 μm, and more preferably 1.5 μm or less. When the average particle diameter is less than the above range, the particles are ubiquitous in the gaps between the fibers and are not uniformly distributed on the surface of the fabric, so that the catalyst activity as the fabric may be reduced. When the average particle diameter exceeds the above range, the specific surface area decreases, so that the catalytic activity per unit catalyst weight is likely to decrease, and the product is poor in design because it is colored white.
The average particle diameter of the coated photocatalyst particles is the average particle diameter in the liquid composition, and is the average particle diameter of the primary particles if present in the primary particles. Depending on the production method, the primary particles may aggregate to form secondary particles. In this case, it is the average particle size of the secondary particles.

In this specification, the value obtained by the dynamic light scattering method is used as the average particle diameter. The measurement conditions of the dynamic light scattering method are as described in the examples.
The liquid composition of the present invention may further contain a binder. Examples of the binder include an inorganic binder such as silica and an organic binder such as a fiber processing agent. An organic binder is preferable, and a fiber processing agent is particularly preferable. The fiber processing agent refers to an agent that affects properties such as flexibility, hardness, gloss, and water absorption of the fiber fabric, and includes a hard finish. Examples of the hard finish include water-soluble resins such as acrylic resins, vinyl acetate resins, polyurethane resins, melamine resins, urea resins, vinyl chloride resins, vinylidene chloride resins, polyester resins, and starches. . Examples of hard finishes for polyester resins include hard finishes that can be purchased from Takamatsu Yushi Co., Ltd. as pesresin 2000 and TK set 413.

  The liquid composition of the present invention may further contain a dispersant. In order to improve the dispersibility of the photocatalyst particles in the liquid composition, it is preferable to include a dispersant. Examples of the dispersant include polycarboxylic acid-based dispersants (for example, polyacrylic acid, polymethacrylic acid, styrene-maleic anhydride copolymer); sulfonic acid-based dispersants (for example, lignin sulfonic acid and naphthalene sulfonic acid); Examples thereof include alcohol-based dispersants (for example, polyvinyl alcohol); amino acid-based dispersants; nonionic dispersants;

The liquid composition of the present invention may further contain various known components such as a stabilizer, a pH adjuster, a thickener, and a defoaming agent as necessary.
The liquid composition can be obtained by mixing each of the aforementioned components in a solvent. Here, the solvent may be any of water, an organic solvent, and a mixture thereof, and water is preferable. Any known mixing means can be used for mixing. Examples thereof include a ball mill and a dyno mill. The ratio of the photocatalyst particles in the liquid composition is selected according to the coating method. In general, the weight of the photocatalyst particles with respect to the total weight of the liquid composition is 0.1 wt% or more, preferably 0.5 wt% or more, 20 wt% or less, preferably 10 wt% or less. The liquid composition is preferably in the form of a suspension or dispersion in which the photocatalyst particles do not settle.

  There is no restriction | limiting in particular in the fabric base material with which the liquid composition of this invention is applied, Natural fibers, such as polyester, nylon, an acryl, rayon, etc .; Cotton, linen, etc .; Nonwoven fabric; Fabric-like wallpaper; In applications requiring flameproofing properties such as curtains, wallpaper, and roll screens, it is preferable to perform flameproofing in advance before coating. Or you may use the fabric base material of a flame-retardant fiber. For the flameproofing process, any flameproofing agent including a halogen flameproofing agent can be used.

  Various known coating methods can be used for coating on the fabric substrate. For example, spray coating method, dipping method, gravure coating, roll coating, and pad method can be mentioned. After coating, the fabric having photocatalytic activity is obtained by further drying.

  The present invention also relates to a fabric to which the aforementioned photocatalyst particles are attached. There is no restriction | limiting in the attachment method, It can also obtain by apply | coating the liquid composition of this invention to a fabric base material, and drying. Here, adhesion includes a case where the photocatalyst particles are in direct contact with the fabric; a case where the photocatalyst particles are in contact via other components such as a binder; and a case where the layer containing the binder and the photocatalyst particles covers the fabric. The above-mentioned fiber processing agent may act as a binder.

  The fabric to which the photocatalyst particles are attached can be used in various applications including interior fabrics, furniture members, bedding members, bedding and furniture covers, and rugs. For example, as fabrics of the present invention, interiors such as roll screens, wall cloths (including wall cloth-like wallpaper), curtains and table cloths; furniture members such as chair seats and backrest cloths, sofa cloths, and cushion cloths; Covers such as futon covers, pillow covers, bed covers, home appliance covers, sofa covers, cushion covers, piano covers; carpets, rugs, mats and other rugs.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
[Example 1]
Titanium oxide powder (TKP-101, anatase type, silica-coated product manufactured by Teica) was dispersed in water using a ball mill to obtain an aqueous dispersion having a titanium oxide concentration of 20.0 wt%. When the average particle diameter of the titanium oxide particles was measured by a dynamic light scattering method using this dispersion, the average particle diameter was 1 μm. The particle size was measured using a model Malvern HPPS, model name HPP5001 manufactured by Malvern. The measurement temperature was 25 ° C.

This titanium oxide aqueous dispersion and a fiber processing agent (PET hard finish) were mixed to obtain a liquid composition. The titanium oxide concentration in the liquid composition was 2.0 wt%. This liquid composition was used as a coating solution. This coating solution was applied to a polyester white cloth that had been subjected to a flameproofing treatment in advance with a halogen-based flameproofing agent (hexabromocyclodecane (HBCD)), and further dried to obtain a polyester cloth containing titanium oxide. The coating amount was 40 g / m ² .
[Example 2]
A polyester fabric containing titanium oxide was obtained in the same manner as in Example 1 except that the titanium oxide concentration of the coating solution was 4.0 wt%.
[Comparative Example 1]
A neutral titania sol (manufactured by Ishihara Sangyo Co., Ltd., containing uncoated titanium oxide with an average particle size of 100 nm, titanium oxide concentration 20.1 wt%, pH = 7.9) instead of silica-coated titanium oxide aqueous dispersion A polyester fabric containing titanium oxide was obtained in the same manner as in Example 1 except for the points used. The average particle size was measured in the same manner as in Example 1.
[Comparative Example 2]
A polyester fabric containing titanium oxide was obtained in the same manner as in Comparative Example 1, except that the titanium oxide concentration of the coating solution was 4.0 wt%.
[Comparative Example 3]
Instead of silica-coated titanium oxide aqueous dispersion, titanium oxide powder (Ishihara Sangyo Co., Ltd.) dispersed in water using a ball mill (titanium oxide concentration 20.0 wt%, average particle size 1 μm) is used. Except for the above, a polyester fabric containing titanium oxide was obtained in the same manner as in Example 1. The average particle size was measured in the same manner as in Example 1.
[Evaluation Example 1 (yellowing test)]
A yellowing test was performed on the fabric samples of Examples 1 and 2 and Comparative Example 1-3. The yellowing test was performed by irradiating each sample with black light as ultraviolet rays and measuring the time course of yellowness. Yellowness (YI) was calculated from X, Y, and Z colorimetric values. The measurement conditions are as follows.

Light source: FL15BLB-A (Toshiba Lighting & Technology Corp.)
Irradiation intensity: 1.0mW / cm ²
UV intensity meter: UVR-2 (TOPCON Co., Ltd.), light receiving unit UD-36
Colorimeter: Z-1001 DP (Nippon Denshoku Industries Co., Ltd.)
For comparison, a test was also conducted on a polyester fabric substrate (prefabricated fabric) that was not applied. The results are shown in FIGS.

As can be seen from FIG. 1, when the fabrics of Examples 1 and 2 to which silica-coated titanium oxide having an average particle diameter of 1 μm is attached are irradiated with ultraviolet rays, the yellowness is temporarily increased initially, but thereafter, the fabric is stable. YI was maintained at 10 or less even after irradiation for 100 hours or more. On the other hand, in the case of the uncoated titanium oxide of Comparative Example 3 (average particle diameter is 1 μm as in Examples 1 and 2), yellowing progresses as the irradiation time becomes longer, and YI for irradiation of 50 hours or more. Exceeded 20 (FIG. 2). These results indicate that yellowing was suppressed by coating with titanium oxide. When the average particle size was 100 nm (Comparative Examples 1 and 2), yellowing was observed as in Comparative Example 3.
[Evaluation Example 2 (Acetaldehyde Decomposition Test)]
The acetaldehyde decomposition test was done about the fabric of the Example and the comparative example. The test method is as follows.

  A spacer was placed on the bottom of the glass container, and the sample was allowed to stand on it. The spacer created a gap between the sample and the bottom and was used to bring the sample into good contact with acetaldehyde. Next, the glass container was installed above the black light so that ultraviolet rays could be irradiated from the bottom surface of the glass container. The glass container was decompressed with an aspirator, a predetermined amount of acetaldehyde gas was injected with a syringe, and then returned to atmospheric pressure.

  In general, since a part of the injected acetaldehyde is adsorbed on the sample or the wall of the container, the gas phase concentration of acetaldehyde is greatly reduced immediately after the injection. Therefore, it was left until the decrease in the acetaldehyde concentration converged. During this time, the gas in the container was periodically collected and the acetaldehyde concentration was monitored by gas chromatography.

  After the fluctuation of the acetaldehyde concentration was subsided, ultraviolet irradiation was started, and the time-dependent change of the acetaldehyde concentration was measured by gas chromatography. Detailed measurement conditions are as follows.

Test container: 4L glass container batch type Light source: FL15BLB-A (Toshiba Lighting & Technology Corp.)
Irradiation intensity: 1.0mW / cm ²
UV intensity meter: UVR-2 (TOPCON Co., Ltd.), light receiving unit UD-36
Sample area: 50cm ² (5cm × 10cm)
Gas chromatograph: GC-14B (Shimadzu Corporation)
The results are shown in FIGS. In the fabrics of Examples 1 and 2, acetaldehyde rapidly decomposed, and the concentration decrease over 24 hours from the start of irradiation exceeded 140 ppm, and the residual concentration decreased to 0-10 ppm. On the other hand, in the fabrics of Comparative Examples 1 and 2, the decrease in the acetaldehyde concentration was comparable to that of the blank, and no significant photocatalytic activity was observed. The photocatalytic activity of the fabric of Comparative Example 3 was higher than that of Comparative Examples 1 and 2, but did not reach that of Examples 1 and 2.
[Evaluation Example 3 (Wet Methylene Blue Decomposition Test)]
A wet methylene blue decomposition test was performed on the samples of Examples and Comparative Examples 1-3. The test was conducted in accordance with the “Method for testing wet decomposition performance in photocatalyst products” of the photocatalyst product forum, with a 40 mmφ sample submerged in the bottom of the test cell. The measurement conditions are as follows.

Test cell size: 40mmφ × 30mm
Amount of charged methylene blue solution: 35ml
Methylene blue aqueous solution concentration for adsorption: 0.025mmol / l
Adsorption time: 24hr
Methylene blue aqueous solution concentration for testing: 0.010mmol / l
Light source: FL15BLB-A (Toshiba Lighting & Technology Corp.)
Irradiation intensity: 1.0mW / cm ²
UV intensity meter: UVR-2 (TOPCON Co., Ltd.), light receiving unit UD-36
Absorbance measurement: Self-recording spectrophotometer, U-4000 (Hitachi, Ltd.)
Measurement cell: Standard cell The results are shown in the table below.

The methylene blue activity index of the fabrics of Examples 1 and 2 is higher than that of Comparative Example 1-3, indicating that the fabric of the present invention has a high oxidative degradation ability.
[SEM observation and EPMA measurement]
About the sample of an Example and a comparative example, SEM observation and EPMA measurement were performed, and distribution of the titanium oxide particle was investigated (FIGS. 5-9). The white bar shown in the SEM image corresponds to 20 μm. The EPMA map (right) in FIG. 5-9 corresponds to the same region as the SEM image (left), and the position where the Ti atom is detected is displayed in white. Comparing the results of the SEM image and the EPMA map, it can be seen that the particles observed in the SEM image correspond to titanium oxide attached to the fabric.

  In the fabrics of Example 1 (FIG. 5), Example 2 (FIG. 6), and Comparative Example 3 (FIG. 9) using titanium oxide particles having an average particle diameter of 1 μm, the particles are not only on the fiber gaps but also on the fabric surface. Widely distributed. On the other hand, in Comparative Example 1 (FIG. 7) and Comparative Example 2 (FIG. 8) using titanium oxide particles having an average particle diameter of 100 nm, the particles are concentrated in the gaps of the fibers and are sparsely distributed on the fabric surface. . In Comparative Example 1 and Comparative Example 2, yellowing occurs due to decomposition of the fiber processing agent or the like by the photocatalyst buried inside the fiber processing agent layer, but the photocatalyst is buried inside the fiber processing agent layer, so the outside of the fiber processing agent layer It is thought that the decomposition activity of organic substances coming from is weakened. Since the distribution form of titanium oxide particles correlates with the photocatalytic activity (Evaluation Examples 2 and 3), the average particle size of the titanium oxide particles is controlled to prevent the particles from being ubiquitous and the frequency of contact with the gas to be decomposed It is considered that a high catalytic activity was realized by increasing.

  By attaching the coated photocatalyst particles having an average particle size of 0.5 to 10 μm to the fabric substrate, it is possible to impart excellent photocatalytic activity to the fabric and to suppress yellowing. This fabric can be used for various applications that require high photocatalytic activity and suppression of discoloration.

FIG. 1 shows the results of a yellowing test performed on the fabrics of Examples 1 and 2. FIG. 2 shows the results of a yellowing test performed on the fabric of Comparative Example 1-3. FIG. 3 shows the results of an acetaldehyde decomposition test performed on the fabrics of Examples 1 and 2. FIG. 4 shows the results of an acetaldehyde decomposition test performed on the fabric of Comparative Example 1-3. FIG. 5 shows an SEM image (left) of the fabric of Example 1 and an EPMA measurement result (right) of the same region. The white bar in the SEM image corresponds to 20 μm. FIG. 6 shows the SEM image (left) of the fabric of Example 2 and the result of EPMA measurement (right) in the same region. The white bar in the SEM image corresponds to 20 μm. FIG. 7 shows the SEM image (left) of the fabric of Comparative Example 1 and the result of EPMA measurement (right) in the same region. The white bar in the SEM image corresponds to 20 μm. FIG. 8 shows the SEM image (left) of the fabric of Comparative Example 2 and the result of EPMA measurement (right) in the same region. The white bar in the SEM image corresponds to 20 μm. FIG. 9 shows the SEM image (left) of the fabric of Comparative Example 3 and the result of EPMA measurement (right) in the same region. The white bar in the SEM image corresponds to 20 μm.

Claims (6)

A fabric substrate coated with a liquid composition to impart photocatalytic activity,
The liquid composition contains photocatalyst particles having a core containing a photocatalytic material and a layer covering at least a part of the core, and a binder,
The average particle diameter of the photocatalyst particles is in the range of 1.0 to 1.5 μm,
Compared with the photocatalytic material of the core, the photocatalytic activity of the material of the coating layer is low,
The binder is a hardener selected from acrylic resins, vinyl acetate resins, polyurethane resins, melamine resins, urea resins, vinyl chloride resins, vinylidene chloride resins, and polyester resins.
The fabric substrate . The fabric substrate according to claim 1, wherein the core comprises titanium oxide. The fabric substrate according to claim 1 or 2, wherein the coating layer comprises silica, calcium phosphate, polysiloxane, or a combination thereof. A method for producing a fabric having photocatalytic activity, comprising a step of applying a liquid composition to a fabric substrate,
The liquid composition contains photocatalyst particles having a core containing a photocatalytic material and a layer covering at least a part of the core, and a binder,
The average particle diameter of the photocatalyst particles is in the range of 1.0 to 1.5 μm,
Compared with the photocatalytic material of the core, the photocatalytic activity of the material of the coating layer is low,
The binder is a hardener selected from acrylic resins, vinyl acetate resins, polyurethane resins, melamine resins, urea resins, vinyl chloride resins, vinylidene chloride resins, and polyester resins.
The manufacturing method . The manufacturing method of Claim 4 in which a core contains a titanium oxide . The coating layer includes silica, calcium phosphate, polysiloxane, or combinations thereof
The manufacturing method according to claim 4 or 5 .