JP7533710B2 - Self-cleaning agent - Google Patents

Description

The present invention relates to a self-cleaning agent that has dirt-decomposing properties.

Anti-soiling processing is processing that makes it difficult for stains and dirt to adhere and makes it easier to remove stains by washing, wiping, etc. The methods of anti-soiling processing are roughly divided into water- and oil-repellent systems and water- and oil-absorbing systems, and the water- and oil-repellent systems include those that contain fluorine compounds, and a method that uses photocatalytic titanium oxide to break down dirt is known (see, for example, Patent Document 1).

However, the photocatalytic titanium oxide requires a strong energy source, namely ultraviolet light, and has the problem that its strong oxidizing effect can cause deterioration of the processed material or the base material itself.

JP 2014-163030 A

The problem that this invention aims to solve is to provide a self-cleaning agent that can break down dirt components under indoor light.

The present invention provides a self-cleaning agent that contains a visible light responsive photocatalyst.

The self-cleaning agent of the present invention can decompose dirt components under practical indoor light. In addition, by using a specific visible light responsive photocatalyst, a self-cleaning agent with even better antibacterial and antiviral properties can be obtained. In addition, when a specific visible light responsive photocatalyst is used, the agent is easy to handle even when the titanium oxide concentration is increased.

The self-cleaning agent of the present invention preferably contains a visible light responsive photocatalyst in order to solve the problems of the present invention.

The visible light responsive photocatalyst may be, for example, a composition containing titanium oxide (a), and preferably a composition in which a metal compound is supported on titanium oxide (a) because it provides even more excellent antiviral properties.

As the titanium oxide (a), for example, rutile type titanium oxide (a1), anatase type titanium oxide, brookite type titanium oxide, etc. can be used. These titanium oxides may be used alone or in combination of two or more. Among these, it is preferable to include rutile type titanium oxide (a1) because it has excellent photocatalytic activity in the visible light region.

The content (rutilated rate) of the rutile-type titanium oxide (a1) is preferably 15 mol% or more, more preferably 50 mol% or more, and even more preferably 90 mol% or more, in order to obtain even better antiviral properties in bright and dark places, organic compound decomposition properties in bright places, and visible light responsiveness.

The liquid phase method and the gas phase method are generally known as methods for producing the titanium oxide (a). The liquid phase method is a method in which titanium oxide is obtained by hydrolyzing or neutralizing titanyl sulfate obtained from a liquid in which raw ore such as ilmenite is dissolved. The gas phase method is a method in which titanium oxide is obtained by a gas phase reaction between oxygen and titanium tetrachloride obtained by chlorinating raw ore such as rutile. Note that one method for distinguishing between titanium oxides produced by both methods is to comparatively analyze the titanium (Ti) content and the metal element content using a fluorescent X-ray analyzer or the like.

The titanium oxide produced by the liquid phase method contains metal elements such as zirconium and niobium derived from ilmenite ore in the product. The zirconium content ratio (Zr/Ti ratio) to titanium 100 in the titanium oxide produced by the liquid phase method may be 0.03 or more, 0.04 or more, 0.05 or more, 0.8 or less, 0.5 or less, or 0.3 or less. Any combination of these upper and lower limits may be used. The zirconium content ratio (Zr/Ti ratio) to titanium 100 in the titanium oxide may be 0.03 to 0.8, 0.04 to 0.5, or 0.05 to 0.3. The content ratio of niobium to titanium 100 (Nb/Ti ratio) in the titanium oxide produced by the liquid phase method may be 0.05 or more, 0.08 or more, 0.1 or more, 0.8 or less, 0.5 or less, or 0.3 or less. Any combination of these upper and lower limits is acceptable. The content ratio of niobium to titanium 100 (Nb/Ti ratio) in the titanium oxide may be 0.05 to 0.8, 0.08 to 0.5, or 0.10 to 0.3. If the titanium oxide is within the above range, it is highly dispersible in the solvent and a mixture liquid that is easy to handle can be produced even if the titanium oxide concentration is increased. The visible light responsive photocatalyst obtained from the titanium oxide within the above range has the same content ratio of metal elements (zirconium and/or niobium) to titanium 100 in the visible light responsive photocatalyst as the above range.

In contrast, in the gas phase method, titanium tetrachloride is refined, so these metal elements (zirconium and/or niobium) are not substantially contained in the titanium oxide. Here, "titanium oxide substantially does not contain metal elements" means that the content ratio of metal elements in titanium oxide is less than 0.02 per 100 titanium. Conversely, "titanium oxide substantially contains metal elements (zirconium and/or niobium)" means that the content ratio of metal elements in titanium oxide is 0.02 or more per 100 titanium. A visible light responsive photocatalyst obtained from titanium oxide that substantially contains metal elements (zirconium and/or niobium) substantially contains metal elements (zirconium and/or niobium).

Although titanium oxide produced by the gas phase method has the advantage of being able to produce uniform particle diameters, it is thought that secondary aggregates are difficult to produce, and therefore the apparent specific surface area is high, which increases the viscosity of the mixed liquid during the reaction process. In contrast, titanium oxide (a) produced by the liquid phase method is thought to produce gentle secondary aggregates in the firing process, and has low cohesive force compared to the specific surface area (BET value) caused by the primary particles, making it possible to suppress the viscosity of the mixed liquid. For these reasons, titanium oxide (a) produced by the liquid phase method is preferable because it can further improve the productivity of the self-cleaning agent.

The BET specific surface area of the titanium oxide (a) is preferably in the range of 1 to 200 m ² /g, more preferably in the range of 3 to 100 m ² /g, more preferably in the range of 4 to 70 m ² /g, and even more preferably in the range of 8 to 50 m ² /g, from the viewpoint of obtaining even better antiviral properties and visible light responsiveness, and is preferably in the range of 7.5 to 9.5 m ² /g from the viewpoint of further increasing the productivity of the self-cleaning agent. The method for measuring the BET specific surface area of the rutile titanium oxide (a1) will be described in the Examples below.

The primary particle diameter of the titanium oxide (a) is preferably in the range of 0.01 to 0.5 μm, more preferably in the range of 0.06 to 0.35 μm, in order to obtain even better antiviral properties and visible light responsiveness. The primary particle diameter of the titanium oxide (a) is measured by a method in which a transmission electron microscope (TEM) is used to directly measure the size of the primary particles from an electron microscope photograph. Specifically, the minor axis diameter and major axis diameter of each primary particle of titanium oxide are measured, and the average is taken as the particle diameter of the primary particle. Next, the volume (weight) of each particle is calculated for 100 or more titanium oxide particles by approximating it to the cube of the calculated particle diameter, and the volume average particle diameter is taken as the average primary particle diameter.

In addition, as the visible light responsive photocatalyst, it is preferable to use a titanium oxide (a) carrying a metal compound (titanium oxide composition) since this further improves the photocatalytic activity in the visible light region and is likely to exhibit a suitable activity capable of decomposing dirt components under practical indoor light.

As the metal compound, for example, a copper compound, an iron compound, a tungsten compound, etc. can be used. Among these, a copper compound is preferred, and a divalent copper compound is more preferred, in that it provides even more excellent antibacterial and antiviral properties. A known method can be used to support the metal compound on the titanium oxide (a).

Next, we will explain the most preferred method of supporting a divalent copper compound on titanium oxide (a).

As an example of a method for supporting a divalent copper compound on the titanium oxide (a), there can be mentioned a method having a mixing step (i) of titanium oxide (a) including rutile-type titanium oxide (a1), a divalent copper compound raw material (b), water (c), and an alkaline substance (d).

The concentration of the titanium oxide (a) in the mixing step (i) is preferably in the range of 3 to 40% by mass. In the present invention, when titanium oxide (a) produced by a liquid phase method is used, the mixing step can be carried out with good handling even if the concentration of titanium oxide (a) is increased. Specifically, the mixing step can be carried out well even if the concentration of titanium oxide (a) is in the range of more than 25% by mass to 40% by mass or less.

As the divalent copper compound raw material (b), for example, a divalent copper inorganic compound, a divalent copper organic compound, etc. can be used.

Examples of the divalent copper inorganic compound that can be used include inorganic acid salts of divalent copper such as copper sulfate, copper nitrate, copper iodate, copper perchlorate, copper oxalate, copper tetraborate, ammonium copper sulfate, copper amidosulfate, ammonium copper chloride, copper pyrophosphate, and copper carbonate; divalent copper halides such as copper chloride, copper fluoride, and copper bromide; copper oxide, copper sulfide, azurite, malachite, and copper azide. These compounds may be used alone or in combination of two or more.

Examples of the divalent copper organic compounds include copper formate, copper acetate, copper propionate, copper butyrate, copper valerate, copper caproate, copper enanthate, copper caprylate, copper pelargonate, copper caprate, copper myristic acid, copper palmitate, copper margarate, copper stearate, copper oleate, copper lactate, copper malate, copper citrate, copper benzoate, copper phthalate, copper isophthalate, copper terephthalate, copper salicylate, copper mellitic acid, copper oxalate, copper malonate, copper succinate, copper glutarate, copper adipic acid, copper fumarate, and glycol. Examples of compounds that can be used include copper glycerate, copper gluconate, copper tartrate, copper acetylacetonate, copper ethylacetoacetate, copper isovalerate, copper β-resorcylate, copper diacetoacetate, copper formylsuccinate, copper salicylamine, copper bis(2-ethylhexanoate), copper sebacate, copper naphthenate, copper oxine, copper acetylacetonate, copper ethylacetoacetate, copper trifluoromethanesulfonate, copper phthalocyanine, copper ethoxide, copper isopropoxide, copper methoxide, and copper dimethyldithiocarbamate. These compounds may be used alone or in combination of two or more.

As the divalent copper compound raw material (b), among those mentioned above, it is preferable to use one represented by the following general formula (1).
_CuX2 (1)
(In formula (1), X represents a halogen atom, CH ₃ COO, NO ₃ , or (SO ₄ ) _1/2 .)

In the formula (1), X is more preferably a halogen atom, and even more preferably a chlorine atom.

The amount of the divalent copper compound raw material (b) used in the mixing step (i) is preferably in the range of 0.01 to 20 parts by mass, more preferably in the range of 0.1 to 15 parts by mass, and even more preferably in the range of 0.3 to 10 parts by mass, per 100 parts by mass of the titanium oxide (a).

The water (c) is a solvent in the mixing step (i), and although water alone is preferred, other solvents may be included as necessary. Examples of the other solvents that can be used include alcohol solvents such as methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; dimethylformamide, tetrahydrofuran, and the like. These solvents may be used alone or in combination of two or more.

Examples of the alkaline substance (d) that can be used include sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetrabutylammonium hydroxide, triethylamine, trimethylamine, ammonia, and basic surfactants, and it is preferable to use sodium hydroxide.

The alkaline substance (d) is preferably added as a solution in order to facilitate control of the reaction, and the concentration of the alkaline solution added is preferably in the range of 0.1 to 5 mol/L, more preferably in the range of 0.3 to 4 mol/L, and even more preferably in the range of 0.5 to 3 mol/L.

In the mixing step (i), the titanium oxide (a), the divalent copper compound raw material (b), the water (c), and the alkaline substance (d) may be mixed. For example, the titanium oxide (a) may be mixed with the water (c) and stirred as necessary, the divalent copper compound raw material (b) may then be mixed and stirred, and the alkaline substance (d) may then be added and stirred. By this mixing step (i), the divalent copper compound derived from the divalent copper compound raw material (b) is supported on the titanium oxide (a).

The total stirring time in the mixing step (i) is, for example, 5 to 120 minutes, and preferably 10 to 60 minutes. The temperature during the mixing step (i) is, for example, in the range of room temperature to 70°C.

In order to ensure good support of the divalent copper compound on the titanium oxide (a), the titanium oxide (a), the divalent copper compound raw material (b), and water (c) are mixed and stirred, and then the alkaline substance (d) is mixed and stirred to produce a mixture having a pH value preferably in the range of 8 to 11, and more preferably in the range of 9.0 to 10.5.

After the mixing step (i) is completed, the mixture can be separated as a solid content. Methods for the separation include, for example, filtration, sedimentation, centrifugation, and evaporation and drying, with filtration being preferred. The separated solid content may then be washed with water, crushed, classified, etc., as necessary.

After obtaining the solid content, it is preferable to heat treat the solid content in order to more firmly bond the divalent copper compound derived from the divalent copper compound raw material (b) supported on the titanium oxide (a). The heat treatment temperature is preferably in the range of 150 to 600°C, more preferably in the range of 250 to 450°C. The heat treatment time is preferably 1 to 10 hours, more preferably 2 to 5 hours.

By the above method, a titanium oxide composition containing titanium oxide in which a divalent copper compound is supported on titanium oxide (a) can be obtained. The amount of the divalent copper compound supported on the titanium oxide (a) is preferably in the range of 0.01 to 20 parts by mass per 100 parts by mass of titanium oxide (a) from the viewpoint of photocatalytic activity including antiviral activity. The amount of the divalent copper compound supported can be adjusted by the amount of the divalent copper compound raw material (b) used in the mixing step (i). The method for measuring the amount of the divalent copper compound supported will be described in the Examples below.

Next, we will explain specific aspects of how the self-cleaning agent of the present invention is used.

Examples of the above include kneading the material into fibers, spraying it, and using it as a coating agent.

As a method for kneading the self-cleaning agent into the fibers, for example, a method in which the self-cleaning agent is kneaded into fibers such as polyester using an extruder or the like, and then spun into yarn can be given.

Examples of the spray agent include a mixture of the self-cleaning agent and a solvent such as water or alcohol.

The coating agent may be, for example, a mixture of the self-cleaning agent, a solvent such as water or alcohol, and a binder resin. The binder resin may be, for example, an acrylic resin, a urethane resin, a phenolic resin, a polyester resin, or an epoxy resin. These binder resins may be used alone or in combination of two or more kinds.

As described above, the self-cleaning agent of the present invention can decompose dirt components under practical indoor light in the form of organic materials such as fibers and inorganic materials such as slate boards. In addition, by using a specific visible light responsive photocatalyst, a self-cleaning agent with even better antibacterial and antiviral properties can be obtained.

The self-cleaning agent according to the present invention also has excellent antiviral and antibacterial properties, safety to the human body, heat resistance, weather resistance, and water resistance.

The present invention will be explained in more detail below using examples.

[Preparation Example 1]
(1) Titanium oxide a) Crystalline rutile titanium oxide b) Manufacturing method: Liquid phase method (sulfuric acid method)
c) Physical properties: BET specific surface area: 9.0 m ² /g
- Rutile rate: 95.4%
・Primary particle size: 0.18μm
・Zr/Ti ratio: 0.05
・Nb/Ti ratio: 0.17

(2) Manufacturing process a) Mixing process (reaction process)
600 parts by mass of the titanium oxide, 8 parts by mass of copper (II) chloride dihydrate, and 900 parts by mass of water were mixed in a stainless steel container. The mixture was then stirred in a stirrer ("Robomix" manufactured by Tokushu Kika Kogyo Co., Ltd.). The mixture was stirred at RT, and a 1 mol/L aqueous solution of sodium hydroxide was added dropwise until the pH of the mixture reached 10.
b) Dehydration step: The mixture was filtered under reduced pressure using a qualitative filter paper (5C) to separate the solid matter from the mixture, and then washed with ion-exchanged water. The washed solid matter was then dried at 120° C. for 12 hours. The water was removed, and after drying, a powdered titanium oxide composition was obtained using a mill (Miller, manufactured by Iwatani Sangyo Co., Ltd.).
c) Heat Treatment Step: The mixture was heat-treated at 450° C. for 3 hours in the presence of oxygen using a precision incubator (DH650 manufactured by Yamato Scientific Co., Ltd.) to obtain a titanium oxide composition containing titanium oxide carrying a divalent copper compound. Got it.

(3) Changing the titanium oxide concentration of the mixture in the mixing step In the above (2) manufacturing process a) mixing step (reaction step), the titanium oxide concentration was changed, and the stirrable state was judged for each blend ratio. Specifically, if the mixture was stirred uniformly in the container, it was rated as "T," and if the mixture became gel-like and only the stirring around the stirring shaft was insufficient, it was rated as "F."

[Preparation Example 2]
A titanium oxide composition was obtained in the same manner as in Example 1, except that the amount of copper(II) chloride dihydrate used in Preparation Example 1 was changed from 8 parts by mass to 3.3 parts by mass. In addition, a test for changing the titanium oxide concentration was conducted in the same manner as in Preparation Example 1.

[Preparation Example 3]
(1) Titanium oxide a) Crystalline rutile titanium oxide b) Manufacturing method: Liquid phase method c) Physical properties BET specific surface area: 37.2 m ² /g
- Rutile rate: 99.6%
・Primary particle size: 0.04μm
・Zr/Ti ratio: 0.05
・Nb/Ti ratio: 0.26

A titanium oxide composition was obtained in the same manner as in Preparation Example 1, except that the type of titanium oxide in Preparation Example 1 was changed to the titanium oxide described above. In addition, a test for changing the titanium oxide concentration was conducted in the same manner as in Preparation Example 1.

[Preparation Example 4]
(1) Titanium oxide a) Crystalline rutile titanium oxide b) Manufacturing method: Liquid phase method c) Physical properties BET specific surface area: 6 m ² /g
- Rutile rate: 87.2%
・Zr/Ti ratio: 0.17
・Nb/Ti ratio: 0.20

A titanium oxide composition was obtained in the same manner as in Preparation Example 1, except that the type of titanium oxide in Preparation Example 1 was changed to the titanium oxide described above. In addition, a test for changing the titanium oxide concentration was conducted in the same manner as in Preparation Example 1.

[Preparation Example 5]
(1) Titanium oxide a) Crystalline rutile titanium oxide b) Manufacturing method: Gas phase method c) Physical properties BET specific surface area: 13 m ² /g
- Rutile rate: 95.6%
・Primary particle size: 0.15μm
・Zr/Ti ratio: 0.00
・Nb/Ti ratio: 0.01

A titanium oxide composition was obtained in the same manner as in Preparation Example 1, except that the type of titanium oxide was changed to the titanium oxide described above and the amount of water used was changed from 900 parts by mass to 4,000 parts by mass. In addition, a test for changing the titanium oxide concentration was conducted in the same manner as in Preparation Example 1.

[Preparation Example 6]
A titanium oxide composition was obtained in the same manner as in Preparation Example 5, except that the amount of copper(II) chloride dihydrate used was changed from 8 parts by mass to 3.3 parts by mass in Preparation Example 5. In addition, a test for changing the titanium oxide concentration was conducted in the same manner as in Preparation Example 1.

[Preparation Example 7]
(1) Titanium oxide a) Crystalline rutile titanium oxide b) Manufacturing method: Gas phase method c) Physical properties BET specific surface area: 6.8 m ² /g
- Rutile rate: 99.6%
・Primary particle size: 0.25μm
・Zr/Ti ratio: 0.01
・Nb/Ti ratio: 0.01

A titanium oxide composition was obtained in the same manner as in Preparation Example 5, except that the type of titanium oxide in Preparation Example 5 was changed to the titanium oxide described above. In addition, a test for changing the titanium oxide concentration was conducted in the same manner as in Preparation Example 1.

[Preparation Example 8]
(1) Titanium oxide a) Crystalline rutile titanium oxide b) Manufacturing method: Gas phase method c) Physical properties BET specific surface area: 13.5 m ² /g
- Rutile ratio: 76.5%
・Primary particle size: 0.13μm
・Zr/Ti ratio: 0.00
・Nb/Ti ratio: 0.01

A titanium oxide composition was obtained in the same manner as in Preparation Example 5, except that the type of titanium oxide in Preparation Example 5 was changed to the titanium oxide described above. In addition, a test for changing the titanium oxide concentration was conducted in the same manner as in Preparation Example 1.

[Preparation Example 9]
(1) Titanium oxide a) Crystalline rutile titanium oxide b) Manufacturing method: Gas phase method c) Physical properties BET specific surface area: 20 m ² /g
- Rutile rate: 53%
・Primary particle size: 0.07μm
・Zr/Ti ratio: 0.00
・Nb/Ti ratio: 0.01

A titanium oxide composition was obtained in the same manner as in Preparation Example 5, except that the type of titanium oxide in Preparation Example 5 was changed to the titanium oxide described above. In addition, a test for changing the titanium oxide concentration was conducted in the same manner as in Preparation Example 1.

[Method for measuring the BET specific surface area of titanium oxide (a)]
The specific surface area was measured (BET single point method) using a fully automatic BET specific surface area measuring device "MacSORBHM model-1208" manufactured by Mountech Co., Ltd.

[Method for measuring the rutile content of titanium oxide (a)]
Using an X-ray diffractometer "XRD-6100" manufactured by Shimadzu Corporation, the peak height ratio corresponding to rutile crystals was calculated from the peak heights corresponding to the entire titanium oxide crystals (rutile, brookite, and anatase types).

[Method of calculating Zr/Ti ratio and Nb/Ti ratio of titanium oxide (a)]
Metal element composition analysis was performed by the bulk fundamental parameter (bulk FP) method using a fluorescent X-ray analyzer "SEA1200VX" manufactured by Seiko Instruments Inc. The intensity ratio of the fluorescence intensity (cps: counts per second) of zirconium or niobium to the fluorescence intensity (cps) of titanium obtained by measuring the titanium oxide (a) sample was calculated as the Zr/Ti ratio or the Nb/Ti ratio, respectively.

[Method for measuring the amount of divalent copper compound supported on titanium oxide (a)]
The titanium oxide compositions obtained in Preparation Examples 1 to 9 were completely dissolved in a hydrofluoric acid solution, and the extract was analyzed by an ICP atomic emission spectrometer to quantify the amount of divalent copper compound supported on titanium oxide (a) (amount of divalent copper compound supported (parts by mass)/titanium oxide (a) (parts by mass)). Note that the cases where the amount supported was not measured were marked with "-".

[Antiviral]
Antiviral tests were conducted in accordance with JIS R 1756: 2013. The antiviral properties were evaluated by uniformly applying 1 g/ ^m2 of the titanium oxide compositions obtained in the Examples and Comparative Examples onto a soda-lime glass plate, irradiating the sample for 4 hours with a light source that cuts off wavelengths of 400 nm or less with an N-113 filter, and calculating the value (degree of inactivation) from the following formula.
Inactivation degree = log (N/N ₀ )
N: infectious titer of the sample after the reaction, N ₀ : infectious titer of the inoculated phage.
Inactivation degree-1 indicates 90% inactivation, inactivation degree-2 indicates 99%, and inactivation degree-3 indicates 99.9% inactivation.
In addition, those for which antiviral tests were not performed were marked "-".

As shown in Preparation Examples 1 to 4, it was found that if titanium oxide is obtained by a liquid phase method, the titanium oxide (a) can be mixed stably even if the concentration in the mixture during the mixing step (i) is increased, and an antiviral agent with excellent antiviral properties can be efficiently produced.

On the other hand, all of Preparation Examples 5 to 9 use rutile-type titanium oxide produced by a gas phase method instead of titanium oxide (a), but it was found that when the titanium oxide concentration in the mixing step (i) exceeds 20 mass%, the viscosity of the mixture becomes extremely high, making it difficult to handle and resulting in poor productivity.

In particular, in Preparation Examples 5 to 9, experiments were conducted with varying ranges of the BET specific surface area of titanium oxide, but even in Preparation Example 7, where the value was small, the viscosity of the mixed liquid became extremely high as the titanium oxide concentration increased, and no improvement in productivity was observed.

[Example 1]
25 parts by mass of the titanium oxide composition obtained in Preparation Example 1, 73.5 parts by mass of water, and 1.5 parts by mass of a dispersant (DISPERBIK 190 manufactured by BYK-Chemie) were dispersed in a sand grinder to obtain an aqueous slurry.
35 parts by mass of the obtained aqueous slurry, 5 parts by mass of an acrylic resin binder ("RYUDYE-W FIXER 254PK" manufactured by DIC Corporation), and 60 parts by mass of an O/W type emulsion (an emulsion of 5 parts of "RYUDYE-W REDUCER CONC 720ENF" manufactured by DIC Corporation, 45 parts of water, and 50 parts of mineral spirits) were mixed and printed on a cotton broadcloth (122.5 g/ ^m2 ) using an auto screen printing machine (manufactured by Tsujii Senki Kogyo Co., Ltd.) so that the coating amount before drying was 100 g/ ^m2 , and the mixture was dried for 2 minutes at 150°C in a hot air circulation dryer to obtain a sample for evaluation.

30 μL of stain component (A) (0.5 parts by mass of oil red, 49.75 parts by mass of ethanol, and 49.75 parts by mass of oleic acid) was dripped onto the obtained sample using a micropipette and left in a room at 500 lux. The a* value was measured 1 hour (0 days), 1 day, and 2 days after dripping using a colorimeter (Konica Minolta, Inc. "CR-200 D65 light source").

[Example 2]
In Example 1, the a* value was measured in the same manner as in Example 1, except that the stain component (A) was changed to the stain component (B) (chili oil manufactured by S&B Co., Ltd.). The Δa* was calculated by the difference from Comparative Example 4.

[Example 3]
The same procedure as in Example 1 was repeated, except that the stain component (A) in Example 1 was changed to stain component (C) (1 part by mass of SB curry powder granules and 99 parts by mass of ethanol).
The a* value was measured. Note that Δa* was determined by the difference from Comparative Example 6.

[Example 4]
The a* value was measured in the same manner as in Example 1, except that a slate board (manufactured by Nozawa Co., Ltd.) was used instead of the cotton broadcloth in Example 1. The a* value was determined by the difference from Comparative Example 8.

[Comparative Example 1]
The a* value was measured in the same manner as in Example 1, except that the stain component (A) was dropped directly onto the cotton broadcloth used in Example 1. The a* value was used as the standard for the color change (Δa*) in Example 1, Comparative Example 2, and Comparative Example 3.

[Comparative Example 2]
5 parts by weight of an acrylic resin binder ("RYUDYE-W FIXER 254PK" manufactured by DIC Corporation) and 95 parts by weight of an O/W type emulsion (an emulsion of 5 parts of "RYUDYE-W REDUCER CONC 720ENF" manufactured by DIC Corporation, 45 parts of water, and 50 parts of mineral spirits) were mixed, and printed on the cotton broadcloth used in Example 1 using an auto screen printing machine (manufactured by Tsujii Senki Kogyo Co., Ltd.) so that the coating amount before drying was 100 g/ ^m2 , and dried in a hot air circulation dryer at 150°C for 2 minutes to obtain a sample for evaluation. The a* value was measured in the same manner as in Example 1, except that the stain component (A) was dropped onto the sample.

[Comparative Example 3]
Instead of the titanium oxide composition of Preparation Example 1, 25 parts by mass of an ultraviolet light responsive photocatalyst ("ST-41" manufactured by Ishihara Sangyo Kaisha, Ltd.), 73.5 parts by mass of water, and 1.5 parts by mass of a dispersant ("DISPERBIK 190" manufactured by BYK-Chemie) were dispersed in a sand grinder to obtain an aqueous slurry.
35 parts by weight of the obtained aqueous slurry, 5 parts by weight of an acrylic resin binder ("RYUDYE-W FIXER 254PK" manufactured by DIC Corporation), and 60 parts by weight of an O/W type emulsion (an emulsion of 5 parts of "RYUDYE-W REDUCER CONC 720ENF" manufactured by DIC Corporation, 45 parts of water, and 50 parts of mineral spirits) were mixed, and printed on a cotton broadcloth (122.5 g/m ² ) using an auto screen printing machine (manufactured by Tsujii Senki Kogyo Co., Ltd.) so that the coating amount before drying was 100 g/m ² , and dried in a hot air circulation dryer at 150° C. for 2 minutes to obtain a sample for evaluation. The a* value was measured in the same manner as in Example 1, except that the stain component (A) was dropped onto the sample.

[Comparative Example 4]
The a* value was measured in the same manner as in Comparative Example 1, except that the stain component (A) in Comparative Example 1 was changed to the stain component (B). This a* value was used as the standard for the color change (Δa*) in Example 2 and Comparative Example 5.

[Comparative Example 5]
The a* value was measured in the same manner as in Comparative Example 2, except that the stain component (A) in Comparative Example 2 was changed to the stain component (B).

[Comparative Example 6]
The a* value was measured in the same manner as in Comparative Example 1, except that the stain component (A) in Comparative Example 1 was changed to the stain component (C). This a* value was used as the standard for the color change (Δa*) in Example 3 and Comparative Example 7.

[Comparative Example 7]
The a* value was measured in the same manner as in Comparative Example 2, except that the stain component (A) in Comparative Example 2 was changed to the stain component (C).

[Comparative Example 8]
The a* value was measured in the same manner as in Comparative Example 1, except that a slate board (manufactured by Nozawa Co., Ltd.) was used instead of the cotton broadcloth of Comparative Example 1. This a* value was used as the standard for the color change (Δa*) of Example 4 and Comparative Example 9.

[Comparative Example 9]
The a* value was measured in the same manner as in Comparative Example 2, except that a slate board (manufactured by Nozawa Co., Ltd.) was used instead of the cotton broadcloth.

[Evaluation of dirt decomposition ability]
The evaluation sample onto which the dirt was dropped was left to stand for 11 hours during the day (illuminance 500 to 550 lux, illuminance meter "YOKOGAWA 3281A") and for 13 hours at night (illuminance 10 lux or less), and the color of the portion onto which the dirt was dropped was measured using a color difference meter ("CR-200" manufactured by Konica Minolta, Inc.) 1 hour after dropping (0 days) and n days later.
The stain decomposition effect was calculated from the difference Δa* with the a* value of the comparative example in which only the stain component was dropped onto the substrate (cotton broadcloth, slate board) as the standard. The color change was evaluated from Δa* after n days and the initial value (0 days), and the more negative the color change, the more the stain component pigment was decomposed.

The self-cleaning agent of the present invention was found to have excellent dirt-decomposing properties under indoor light.

On the other hand, all of the comparative examples 1 to 9, which do not contain a visible light responsive photocatalyst, were inferior in dirt decomposition under indoor light.

Claims (6)

The visible light responsive photocatalyst is a titanium oxide (a) having a metal compound supported thereon,
the titanium oxide (a) contains rutile-type titanium oxide (a1), and the content of the rutile-type titanium oxide (a1) in the titanium oxide (a) is 50 mol % or more;
The self-cleaning agent is characterized in that the content ratio of zirconium to titanium 100 in the visible light responsive photocatalyst (Zr/Ti ratio) is 0.03 to 0.8, and the content ratio of niobium to titanium 100 in the visible light responsive photocatalyst (Nb/Ti ratio) is 0.05 to 0.8. 2. The self-cleaning agent according to claim 1, wherein the content of the rutile-type titanium oxide (a1) in the titanium oxide (a) is 90 mol % or more. The self-cleaning agent according to claim 1 or 2, wherein the metal compound is a divalent copper compound. The self-cleaning agent according to any one of claims 1 to 3, wherein the titanium oxide (a) has a BET specific surface area of 1 to 200 m ² /g. The self-cleaning agent according to any one of claims 1 to 4, wherein the content ratio of zirconium to titanium 100 (Zr/Ti ratio) in the visible light responsive photocatalyst is 0.05 to 0.3. The self-cleaning agent according to any one of claims 1 to 5, wherein the content ratio of niobium to titanium 100 (Nb/Ti ratio) in the visible light responsive photocatalyst is 0.1 to 0.3.