KR20050056155A - Coating composition, method for preparation of film having photocatalyst function, and photocatalyst member - Google Patents

Abstract

(Problem) Having a photocatalytic function, even if the thickness of the film is thick, no cracking or peeling occurs due to dry shrinkage, that is, a thick film can be obtained, and the adhesion and transparency of the film are also excellent, indicating that the photocatalytic activity is high. It is to provide technology that can.

(Solution means) A coating composition containing photocatalyst particles, an organic alkali, an anionic dispersant, and curable plate-shaped particles.

Description

COATING COMPOSITION, METHOD FOR PREPARATION OF FILM HAVING PHOTOCATALYST FUNCTION, AND PHOTOCATALYST MEMBER}

The present invention relates to a coating composition, in particular a coating composition having a photocatalytic function (photocatalytic activity), a method of forming a film having a photocatalytic function, and a film having a photocatalytic function, such as deodorization, removal of nitrogen oxides, contamination prevention, hydrophilicity, or It relates to a photocatalyst member exhibiting functions such as antimicrobial activity.

As ceramic paints having excellent heat resistance and abrasion resistance as compared with organic paints, paints such as alkali metal silicate, phosphate, silica sol and metal oxides are known. In addition, these paints have inherent characteristics of ceramic paints such as excellent heat resistance and abrasion resistance in the past, but in recent years, attempts to have new functions in addition to ceramic coatings have been made centering on metal oxides.

Among them, titanium oxide can impart an excellent photocatalytic effect, and exhibit high oxidation power by irradiation of ultraviolet rays. Then, titanium oxide having excellent photocatalytic activity is formed on the surface of substrate (substrate) such as metal, glass, ceramic, and the like to prevent contamination from adhering, decomposition of odor components, water purification, rust prevention, antibacterial and algae breeding. It is considered to be effective for prevention and decomposition of hardly degradable wastes.

For this reason, various titanium oxide coating materials and its manufacturing method for the purpose of forming a titanium oxide film on the surface of a raw material are proposed.

As the formation method of a titanium oxide film, the sol-gel method of the method of apply | coating the thing which hydrolyzed the alkoxide of titanium is the most common.

As a technique similar to this, for example, a method of adding amide and glycol to titanium alkoxide disclosed in JP-A 4-83537, and alcohol amines in titanium alkoxide disclosed in JP-A-7-100378. A method of adding is known.

In addition to these methods, as disclosed in Japanese Unexamined Patent Publication No. 6-293519, a method of dispersing and applying titanium oxide fine particles crystallized by hydrothermal treatment into an acid solution having a pH of 3 or less is known.

As disclosed in Japanese Unexamined Patent Application Publication No. Hei 9-71418, a sol liquid composed of hydrogen peroxide water and titanium oxide and a manufacturing method thereof are known.

Further, as disclosed in Japanese Patent No. 3238349, a titanium oxide ceramic paint containing one type selected from ortho titanoic acid and titanium (IV) ions and anatase type crystalline particles is known.

However, in the proposed technique, when the thickness of the film having a photocatalytic function is set to 1 µm or more, there is a fear that when the film is dried, cracking occurs in the film due to shrinkage stress during drying or, in severe cases, peeling. have.

For this reason, conventionally, the film | membrane which has a photocatalytic function must be made into the thin film of less than 1 micrometer, and the photocatalytic activity falls that much.

In order to solve this problem, the coating composition containing a photocatalyst particle and curable plate-shaped particle | grains is proposed (Unexamined-Japanese-Patent No. 2002-166175).

(Patent Document 1) JP-A 4-83537

(Patent Document 2) Japanese Patent Application Laid-Open No. 7-100378

(Patent Document 3) Japanese Unexamined Patent Publication No. 6-293519

(Patent Document 4) Japanese Patent Application Laid-Open No. 9-71418

(Patent Document 5) Japanese Patent No. 3238349

(Patent Document 6) Japanese Unexamined Patent Publication No. 2002-166175

However, it has been found that the technique proposed in Japanese Unexamined Patent Publication No. 2002-166175 has a problem that the transparency of the coating film is insufficient, resulting in a white opaque film.

Accordingly, the problem to be solved by the present invention is that even if the thickness of the film having a photocatalytic function is increased, no cracking or peeling occurs due to dry shrinkage, that is, a thick film can be obtained, and the film has excellent adhesion and transparency. Therefore, the present invention provides a technique capable of exhibiting high photocatalytic activity.

By the way, the present inventors prepared a dispersion solution of titanium dioxide, such as titanic acid or anatase type, obtained by hydrolyzing an inorganic titanium salt aqueous solution such as titanium chloride or titanium sulfate at low temperature, and the aqueous solution of the titanium oxide contained polyphosphoric acid or the like. of anionic dispersing agent and then neutralized by addition of an organic alkali, to obtain a high-dispersion sol of the titanium oxide to redistribute the other hand, the main component of SiO ₂ produced by washing, a hydrothermal process in which particles gelling a mixture of sulfuric acid to alkali silicate aqueous solution The curable plate-shaped particle | grains which were used were prepared, and the photocatalyst coating agent was test-tested by mixing this curable plate-shaped particle with the said dispersion sol of titanium oxide.

Then, the coating agent produced in this test was applied to a glass plate to have a dry film thickness of 2 to 3 μm, and then fired at 400 ° C. to examine the adhesion, transparency, and photocatalytic activity of the photocatalytic film. As a result, the film was colorless and transparent. It was confirmed that it is excellent and has the outstanding photocatalytic activity which has never existed.

The present invention has been achieved based on the above findings.

That is, the said subject is a photocatalyst particle,

With organic alkali,

Anionic dispersants,

It solves with the coating composition characterized by containing curable plate-shaped particle | grains.

Moreover, it is solved by the photocatalyst member characterized by apply | coating the said coating composition.

In particular, the coating composition is solved by a photocatalyst member, which is formed so as to have a dry film thickness of 0.5 to 50 µm.

And the coating process of apply | coating the said coating composition to a base material,

After the application | coating process, it has an organic alkali decomposition process which decomposes the organic alkali in a coating film, and is solved by the formation method of the film | membrane with a photocatalyst function characterized by the above-mentioned.

In particular, the coating process of apply | coating the said coating composition to a base material so that a dry film thickness may be set to 0.5-50 micrometers,

After the application | coating process, it has an organic alkali decomposition process which decomposes the organic alkali in a coating film, and is solved by the formation method of the film | membrane with a photocatalyst function characterized by the above-mentioned.

Moreover, it is solved by the photocatalyst member formed by the formation method of the film | membrane which has the said photocatalyst function.

In the present invention, various particles can be used as the photocatalyst particles. In other words, when light of a wavelength having an energy of a bandgap or more is irradiated, it may be a photocatalyst function. For example, well-known metal compound semiconductors, such as titanium oxide, titanic acid, zinc oxide, tungsten oxide, iron oxide, etc., can be used individually or in combination of 2 or more types. Especially, the case where titanium oxide or titanic acid is used is preferable. That is, when titanic acid such as ortho titanic acid or peroxotitanic acid is used, or anatase type titanium dioxide (including metatitanic acid) or visible light titanium oxide (visible light-responsive titanium dioxide such as nitrogen doping type or oxygen defective type) When crystalline ones having photocatalytic activity such as crystalline titanium dioxide, rutile type, and brookite type were used, transparency of the film and photocatalytic activity were further improved. Especially, amorphous titanic acid (ortho titanic acid) which becomes a crystalline titanium dioxide photocatalyst by heat baking, or metatitanic acid or anatase type titanium dioxide which has crystallinity is preferable. And it is preferable that the secondary particle diameter is 1-300 nm. When using crystalline titanium dioxide, it is preferable that the primary crystal diameter is 1-30 nm. Although the particle size of the colloidal particle of titanium dioxide in this invention is not specifically limited, It is preferable that the particle diameter is 1 nm-500 nm. In particular, it is preferable that it is 3-120 nm.

The titanic acid used in the present invention is, for example, by adding an alkali to a solution in which inorganic titanium compounds such as titanium chloride, titanium oxychloride, titanium sulfate and titanium sulfate are dissolved in water, or by treating with an anion exchange membrane or an ion exchange resin. What was used as a sol solution can be used. In this case, after removing impurity ions, such as chlorine and sulfuric acid, hydrogen peroxide may be added and it may be set as the peroxotitanic acid solution. Moreover, when using an alkoxide as a raw material, a preferable titanic acid solution can be obtained by hydrolyzing titanium alkoxide at low temperature. In addition, a large amount of crystalline titanium dioxide is obtained by performing hydrolysis at a temperature of 70 ° C. or higher, and amorphous ortho titanic acid can be mainly obtained by hydrolysis at room temperature or lower. And it is preferable to use these acidic sols as a raw material of the titanium oxide of this invention, but when corrosive anions, such as chlorine ion, sulfate ion, and nitrate ion, are contained in the acidic sol of a raw material, it carries out filtration washing, ion exchange, dialysis, etc. It is preferable to remove as much as possible by the method of. Examples of the most preferred titanic acid solution include a neutral amorphous titanium oxide sol disclosed in Japanese Patent No. 3238349, and a peroxo titanium oxide sol disclosed in JP-A-9-71418.

The titanium dioxide used in the present invention can be obtained by a method such as subjecting the raw material solution obtained by the above method to a heat hydrolysis operation or reacting the vaporized titanium compound with oxygen at a high temperature. The visible light-responsive titanium dioxide can be obtained by contacting anatase-type titanium dioxide with ammonia at a temperature of 300 ° C. or higher, or by firing titanic acid containing an ammonium salt.

On the other hand, in the coating film formed by apply | coating the coating composition of this invention, it is preferable that there exist about 300-3000 mg / m <2> of photocatalyst particles, such as titanium dioxide. This is because excessively small photocatalyst particles deteriorate the catalytic activity effect. In addition, the increase of the photocatalyst particle | grains does not have a problem from a catalyst activity effect point, but it made 3000 mg / m <2> or less a preferable reference | standard from a viewpoint of cost and the physical strength of a coating film.

In the coating composition of the present invention, an anionic dispersant is used as an essential component. That is, when an anionic dispersant is not used, the dispersibility of photocatalyst particles, such as titanium compound particles, for example becomes worse, dispersion particle diameter becomes excessive, and adhesiveness of a coating film falls. Thus, anionic dispersants are very important factors.

Dispersants other than anionic dispersants are known, but in the present invention, they must be anionic dispersants. For example, when a cationic dispersant is used, the charge of photocatalyst particles, such as titanium oxide particles, becomes unstable and agglomerates easily in the neutral to weak alkaline region, and it is difficult to obtain the effect of the present invention. In addition, when a nonionic dispersant is used, there is no effect of imparting a negative charge to photocatalyst particles such as titanium oxide particles, so that the dispersing effect is worse when the dispersant is not used in large quantities. Is lowered. Therefore, it is not enough to simply use a dispersant, but an anionic dispersant must be used.

As an anionic dispersant, polyhydric carboxylic acids, such as hydroxycarboxylic acids, such as condensed phosphoric acid, such as pyrroline acid and tripolyphosphoric acid, phosphoric acid, lactic acid, and glycolic acid, gluconic acid, tartaric acid, polycarboxylic acid, and ammonium salt containing these in an aqueous solution And those selected from the group of compounds such as alkali metal salts are mentioned as preferred. Other anionic dispersants such as organic carboxylic acid, sulfuric acid ester, phosphate ester and organic sulfonic acid can also be used. Moreover, an amphoteric surfactant can also be used as an anionic dispersant as long as it has a group which is neutral and has anionic property. And especially preferable is a dispersing agent containing what is chosen from the group of condensed phosphoric acid, phosphoric acid, hydroxycarboxylic acid, polyhydric carboxylic acid, and polycarboxylic acid.

Moreover, it is preferable that the quantity of anionic dispersing agent is 0.5-50 mass parts with respect to 100 mass parts of photocatalyst particles. That is, when the amount of the anionic dispersant is small, the dispersion of the photocatalyst particles becomes unstable, the dispersibility effect is insufficient, the diameter of the dispersed particles tends to increase, and the adhesion of the coating film tends to decrease. On the contrary, when too large, it tends to adversely affect catalyst activity and membrane strength. Therefore, 0.5-50 mass parts is preferable for anionic dispersing agent with respect to 100 mass parts of photocatalyst particles. The more preferable range is 1-40 mass parts, Especially preferably, it is 3-20 mass parts.

In the coating composition of the present invention, an organic alkali is used as an essential component. This is because when the organic alkali is not used, the pH value is small and dispersion of photocatalyst particles such as titanium compound particles is insufficient. And by using organic alkali, the dispersibility of photocatalyst particles like a titanium compound particle improves.

And if the pH value is enlarged, you may use inorganic alkali instead of organic alkali. However, when inorganic alkali is used, photocatalyst particles, such as titanium dioxide particles, tend to aggregate, and dispersibility falls. Therefore, it should be organic alkali, not simply alkali.

And as an organic alkali, what is chosen from the group of alkanolamine, such as monoethanolamine, diethanolamine, and triethanolamine, tetraalkylammonium, such as tetramethylammonium, oxazine, such as morpholine, piperidine, and choline It is mentioned as a preferable thing. Especially, monoethanolamine, diethanolamine, morpholine, and tetramethylammonium hydroxide are preferable.

Moreover, it is preferable that the quantity of organic alkali is 0.5-100 mass parts with respect to 100 mass parts of photocatalyst particles. That is, when the amount of organic alkali is small, the pH value becomes too low, and the dispersibility effect of the photocatalyst particles is insufficient. On the contrary, when too much, pH value will become high too much and there exists a tendency for corrosiveness to become strong. Therefore, 0.5-100 mass parts of organic alkalis are preferable with respect to 100 mass parts of photocatalyst particles. More preferably, the range is 2 to 80 parts by mass, particularly preferably 4 to 40 parts by mass.

Moreover, it is preferable that the ratio (mass ratio) of anionic dispersing agent and organic alkali is anionic dispersing agent: organic alkali = 100: 50-500.

Curable plate-shaped particle | grains are used as an essential component in the coating composition of this invention. That is, by using curable plate-shaped particle | grains, it becomes possible to set it as thickness whose film thickness exceeds 1 micrometer, for example, 2-50 micrometers. In addition, in this invention, curable plate-shaped particle | grains are cohesive plate-shaped particle | grains and mean what is curable independently. As such a thing, layered polysilic acid, such as a silica-X, a silica-Y, a margarite, and a kanemite, is mentioned as a preferable thing, for example. As silica-X, flaky silica of Unexamined-Japanese-Patent No. 11-351182 (Unexamined-Japanese-Patent No. 2001-136613) can be illustrated. In addition, talc, mica, glass flakes, and the like can also be mentioned. Curable plate-shaped particles mainly containing SiO ₂ as described above are particularly preferred. Further, as described in JP-A-2001-136613, for example, scrubbed silica gel particles obtained by mixing sulfuric acid in a water glass aqueous solution and gelling them, and then hydrothermal treatment again, scaly primary particles The most preferable is curable plate-shaped particle obtained by forming the aggregated particle | grains and grind | pulverizing this aggregated particle | grain.

And it is preferable that the aspect ratios of the said curable plate-shaped particle are 10-300. In particular, it is preferable that aspect ratio is 20-200. This is because the adhesiveness of a coating film falls when the aspect ratio of curable plate-shaped particle becomes small too much, and, on the contrary, when it becomes large too much, there exists a tendency for transparency of a coating film to fall. Moreover, the plate-shaped particle whose average particle length diameter is 2 micrometers or less, especially 0.1-0.8 micrometer is preferable.

Moreover, it is preferable that the quantity of curable plate-shaped particle is 0.5-400 mass parts with respect to 100 mass parts of photocatalyst particles. That is, when there is little quantity of curable plate-shaped particle, there exists a tendency for the adhesiveness of a coating film to fall and it is difficult to make thick film. On the contrary, when too much, the transparency of a coating film will fall and the photocatalyst particle in a film | membrane will become comparatively small, and there exists a tendency for photocatalytic activity to run short. Therefore, 0.5-400 mass parts of curable plate-shaped particle are preferable with respect to 100 mass parts of photocatalyst particles. The more preferable range is 5-200 mass parts, Especially preferably, it is 10-150 mass parts.

The said coating composition is apply | coated on a base material, and the film | membrane which shows a photocatalytic function is formed.

However, it is preferable not only to be comprised by apply | coating the said coating composition to a base material and to dry, but also to decompose the organic alkali content which exists in the coating film. For example, after an application | coating process, organic alkali powder is decomposed | disassembled by heating (heat baking) at 200 degreeC or more high temperature (preferably 600 degrees C or less), or irradiating the light (electromagnetic wave) whose wavelength is 600 nm or less. Of course, you may use both together. That is, the photocatalytic function is further improved by decomposing the organic alkali powder. That is, these post-treatments decompose the organic alkali adsorbed on the surface of the titanium dioxide particles in the coating film to cure the coating film, and at the same time, fine pores are formed to easily adsorb water, gas, organic matters, etc. on the surface of the photocatalyst particles, resulting in more excellent It is because it is thought that photocatalytic activity and hydrophilicity will be expressed.

In addition, when an inorganic alkali such as sodium hydroxide is used as the alkali powder necessary for the neutralization of the coating composition of the present invention, the alkali powder adsorbed on the surface of the photocatalytic particles such as titanium dioxide particles cannot be removed, and thus the photocatalytic activity This decreases that much. Therefore, organic alkali is used in the present invention in that the alkali component can be easily removed by the post-treatment as described above.

It is preferable that pH of the liquid of this composition exists in the range of 4-10 of the coating composition of this invention.

In consideration of the case where the coating is applied to a substrate such as a metal, the concentration of chlorine ions is preferably 0 to 20 ppm in order to prevent the occurrence of gap corrosion.

Water is most preferred as the solvent of the coating composition of the present invention. Subsequently, a solvent compatible with water such as ethanol, methanol and propanol is preferable. A part of water can also be substituted by water-soluble solvents, such as alcohol, glycol, and a ketone.

In the present invention, it is also possible to add silane derivatives such as silica sol and alkyltrimethoxysilane as binder components to improve the coating film properties.

Although it does not specifically limit as a base material used for the photocatalyst member of this invention, Resin, such as metals, such as aluminum, stainless steel, and plated steel, polycarbonate, vinyl chloride, polyethylene terephthalate, acryl, paper, wood, glass, ceramics, etc. Can be mentioned.

The photocatalyst member of the present invention is formed by drying a coating material containing the coating composition of the present invention on the surface of a substrate by a method such as spraying, dipping, roll coating, spin coat, blade coat, brush coating, or the like. Preferably, after that, the organic alkali in the coating film is decomposed by a method such as heat drying or electromagnetic wave irradiation, and the coating film is cured.

The coating film formed as described above is deposited in parallel to the substrate surface to form a multilayer structure in which photocatalytic particles such as titanium dioxide are sandwiched. Since the surface of the plate-shaped particles has many hydroxyl groups, it is chemically bonded to adjacent plate-shaped particles during the dehydration drying process to form a porous, rigid and flexible inorganic film, thereby obtaining a thick film without cracking or peeling. Moreover, it is preferable that the coating film formed as mentioned above is substantially transparent. For example, it is preferable that haze at the time of apply | coating to a colorless transparent glass is 60% or more in visible light transmittance below 10%.

Best Mode for Carrying Out the Invention

The coating composition of this invention contains photocatalyst particle, organic alkali, anionic dispersing agent, and curable plate-shaped particle.

Various particles can be used as the photocatalyst particles. For example, well-known metal compound semiconductors, such as titanium oxide, titanic acid, zinc oxide, tungsten oxide, iron oxide, etc., can be used individually or in combination of 2 or more types. Among them, titanium oxide or titanic acid is used. That is, when titanic acid such as ortho titanic acid or peroxotitanic acid is used, or anatase type titanium dioxide (including metatitanic acid) or visible light titanium oxide (visible light-responsive titanium dioxide such as nitrogen doping type or oxygen defective type) When crystalline ones having photocatalytic activity, such as crystalline titanium dioxide, rutile type, and brookite type, were used, the transparency and the photocatalytic activity of the film were further improved. Especially, amorphous titanic acid (ortho titanic acid) which becomes a crystalline titanium dioxide photocatalyst by heat baking, or metatitanic acid or anatase type titanium dioxide which has crystallinity is preferable. The titanic acid is obtained by adding alkali to a solution in which inorganic titanium compounds such as titanium chloride, titanium oxychloride, titanium sulfate and titanium sulfate are dissolved in water, or treating with an anion exchange membrane or an ion exchange resin to form a sol solution. Can be used. In this case, after removing impurity ions such as chlorine and sulfuric acid, hydrogen peroxide is added to form a peroxotitanic acid solution. When using an alkoxide as a raw material, the titanium alkoxide was hydrolyzed at low temperature. In addition, many crystalline titanium dioxide is obtained by performing hydrolysis at the temperature of 70 degreeC or more. By hydrolysis below room temperature, amorphous ortho titanic acid is mainly obtained. And these acidic sol is used as a raw material of the titanium oxide of this invention. Moreover, when corrosive anions, such as chlorine ion, sulfate ion, and nitrate ion, are contained in the acidic sol of a raw material, it removes as much as possible by methods, such as filtration washing, ion exchange, and dialysis. Examples of the most preferred titanic acid solution are the neutral amorphous titanium oxide sol disclosed in Japanese Patent No. 3238349, and the peroxo titanium oxide sol disclosed in JP-A-9-71418. Titanium dioxide is obtained by a method such as performing a heat hydrolysis operation on the raw material solution obtained by the same method, or reacting the vaporized titanium compound with oxygen at a high temperature. The visible light-responsive titanium dioxide can be obtained by contacting anatase-type titanium dioxide with ammonia at a temperature of 300 ° C. or higher, or by firing titanic acid containing an ammonium salt. The amount of photocatalyst particles such as titanium dioxide is such that the photocatalyst particles are 300 to 3000 mg / m 2 (particularly 500 mg / m 2 or more and 2000 mg / m 2 or less) in the coating film formed by coating the coating composition.

As the anionic dispersant, various dispersants may be used. For example, polyhydric carboxylic acids, such as hydroxycarboxylic acids, such as condensed phosphoric acid, such as pyrrolinic acid and tripolyphosphoric acid, phosphoric acid, lactic acid, and glycolic acid, gluconic acid, tartaric acid, polycarboxylic acid, ammonium salt containing these, and alkali in aqueous solution It is selected from the group of compounds, such as a metal salt. Other anionic dispersants such as organic carboxylic acid, sulfuric acid ester, phosphate ester and organic sulfonic acid can also be used. Moreover, an amphoteric surfactant can also be used as an anionic dispersant as long as it has a group which is neutral and has anionic property. Especially preferable are dispersants containing those selected from the group of condensed phosphoric acid, phosphoric acid, hydroxycarboxylic acid, polyhydric carboxylic acid and polycarboxylic acid. The amount of the anionic dispersant is 0.5 to 50 parts by mass (particularly 1 part by mass or more, or 3 parts by mass or more and 40 parts by mass or less, or 20 parts by mass or less) with respect to 100 parts by mass of the photocatalyst particles.

As the organic alkali, various alkalis can be used. For example, those selected from the group of alkanolamines such as monoethanolamine, diethanolamine and triethanolamine, tetraalkylammonium such as tetramethylammonium, oxazines such as morpholine, piperidine and choline are mentioned as preferred. Can be. Especially, monoethanolamine, diethanolamine, morpholine, and tetramethylammonium hydroxide are preferable. The amount of the organic alkali is 0.5 to 100 parts by mass (particularly 2 parts by mass or more, or 4 parts by mass or more and 80 parts by mass or less, or 40 parts by mass or less) with respect to 100 parts by mass of the photocatalyst particles. Moreover, the ratio (mass ratio) of anionic dispersant and organic alkali is anionic dispersant: organic alkali = 100: 50-500.

Various particles can be used as the curable plate-shaped particles. For example, there are layered polysilicates such as silica-X, silica-Y, margariteite, and garnetite. As silica-X, the flaky silica of especially Unexamined-Japanese-Patent No. 11-351182 (Unexamined-Japanese-Patent No. 2001-136613) can be illustrated. In addition, talc, mica, glass flakes, and the like can be cited, but curable plate-shaped particles having SiO ₂ as a main component are particularly preferable. Further, as described in JP-A-2001-136613, for example, after washing the silica gel particles obtained by mixing sulfuric acid with an aqueous glass solution and gelling them, further hydrothermal treatment is performed to aggregate the flaky primary particles. Most preferable are curable plate-shaped particles obtained by forming particles and pulverizing these aggregated particles. The aspect ratio of curable plate-shaped particle | grain is 10-300, especially 20-200 thing. Moreover, it is a plate-shaped particle whose average particle diameter is 2 micrometers or less, especially 0.1-0.8 micrometer. The quantity of curable plate-shaped particle | grains is 0.5-400 mass parts (especially 5 mass parts or more, or 10 mass parts or more, and 200 mass parts or less, or 150 mass parts or less) with respect to 100 mass parts of photocatalyst particles.

The coating composition of this invention has a pH of 4-10 (especially 4.5 or more and 9.0 or less). Moreover, chlorine ion concentration is 20 ppm or less (it also contains 0). In particular, water is used as the solvent of the coating composition. Solvents compatible with water such as ethanol, methanol, propanol and the like are also used. Part of the water may be substituted with a water-soluble solvent such as alcohol, glycol, ketone, and the like.

The coating composition of this invention may contain silane derivatives, such as a silica sol and alkyl trimethoxysilane, as a binder component.

The formation method of the film which has a photocatalytic function of this invention is a method of apply | coating the said coating composition to a base material. In particular, it is a method of apply | coating so that a dry film thickness may be set to 0.5-50 micrometers (especially 1 micrometer or more, or 1.5 micrometers or more, More preferably, 2 micrometers or more. As the coating method, methods such as spraying, dipping, roll coat, spin coat, blade coat, brush coating and the like are adopted. And after apply | coating, it has an organic alkali decomposition process which decomposes the organic alkali in a coating film. An organic alkali decomposition process is a heating process, for example. When it demonstrates more concretely, it is the process of heating (heat baking) at high temperature 200 degreeC or more (preferably 600 degrees C or less). Or it is a light irradiation process. More specifically, it is a process of irradiating light (electromagnetic waves) with a wavelength of 600 nm or less. In other words, by decomposing the organic alkali content present in the coating film, the organic alkali adsorbed on the surface of the titanium dioxide particles in the coating film is decomposed to cure the coating film, and at the same time, fine pores are formed to adsorb water, gas, and organic substances on the surface of the photocatalyst particles. It becomes easy to be.

Although it does not specifically limit as a base material used for the photocatalyst member of this invention, Resin, such as metals, such as aluminum, stainless steel, and plated steel, polycarbonate, vinyl chloride, PET, and acrylic, paper, wood, glass, ceramics, etc. are used. .

The photocatalyst member of the present invention is formed by coating the coating composition on a substrate. In particular, it is apply | coated and formed on the base material by the formation method of the film | membrane which has the said photocatalyst function. The film thickness after drying is 0.5-50 micrometers (especially 1 micrometer or more, or 1.5 micrometers or more, More preferably, it is 2 micrometers or more. And 40 micrometers or less, or 30 micrometers or less.).

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated to a specific Example. However, this invention is not restrict | limited at all by an Example.

Example

The following materials were used.

[Photocatalyst Particle]

One of the following two types of dispersing sols (A, B) was used.

(A) titanic acid

In Examples 1-5, Example 7, and Comparative Examples 1-8, the thing prepared by the following method was used as a titanate sol.

PH produced by dilution of aqueous titanium chloride solution (Toho Titanium Co., Ltd.) (Ti: 15 to 16%) with water, deionization treatment with an ion exchange membrane to obtain an aqueous titanium oxychloride solution at 70 to 85 ° C., followed by thermal hydrolysis. The titanium dioxide sol of 1-2 was refine | purified and used. The crystal particle diameter of titanium dioxide by the transmission electron microscope was 0.002-0.01 micrometer. The concentration of the titanium oxide sol particles was 5.0% by dry weight.

In Example 10, the precipitate of ortho titanic acid produced by adding ammonia to an aqueous titanium oxychloride solution was washed with water, and dissolved in hydrogen peroxide solution to give a 2% peroxotitanic acid solution.

(B) titanium dioxide

In Examples 6, 8, 9, and Comparative Example 9, a 5% dispersion liquid obtained by dispersing the titanium dioxide powder particles manufactured by Ishihara Industries Co., Ltd .: ST-01 (crystal particle diameter: 0.007 µm, anatase type) in water was used. Used.

[Dispersant]

As the anionic dispersant, it was selected from gluconic acid, glycolic acid, lactic acid, polyphosphoric acid, sodium pyrrolate, and tripolyphosphoric acid.

As the cationic dispersant, benzalkonium chloride was used.

In addition, these chemicals are the reagent grade 1 products of Wako Pure Chemical Industries, Ltd. make.

[Alkali Ingredients]

As the organic alkali, one selected from monoethanolamine, diethanolamine, triethanolamine, morpholine, piperidine, and choline was used.

Sodium hydroxide or potassium hydroxide was used as the inorganic alkali.

And these chemicals are reagent primary or equivalent.

[Curable Particles]

In Examples 1-10 and Comparative Examples 1-6, Toray Chemical Co., Ltd. product SanLabi LFS-050 (aspect ratio: 50) was used.

In Comparative Examples 7 to 9, Nissan Chemical Co., Ltd. silica sol: Snowtex O was used as spherical particles.

Example 1

A titanium oxide coating liquid was prepared by mixing and stirring 4.3 parts by mass of monoethanolamine, 5.7 parts by mass of polyphosphoric acid, and 14.3 parts by mass of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Example 2

A titanium oxide coating liquid was prepared by mixing and stirring 5.0 parts by weight of tetramethylammonium, 14.3 parts by weight of glycolic acid, and 35.7 parts by weight of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by weight of photocatalyst particles.

Example 3

A titanium oxide coating solution was prepared by mixing and stirring 14.3 parts by mass of choline, 28.6 parts by mass of polyphosphoric acid and 57.1 parts by mass of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Example 4

A titanium oxide coating liquid was prepared by mixing and stirring 13.3 parts by weight of diethanolamine, 10.0 parts by weight of gluconic acid, and 250.0 parts by weight of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by weight of photocatalyst particles.

Example 5

A titanium oxide coating solution was prepared by mixing and stirring 4.2 parts by weight of monoethanolamine, 1.7 parts by weight of glycolic acid, and 125.0 parts by weight of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by weight of photocatalyst particles.

Example 6

A titanium oxide coating liquid was prepared by mixing and stirring 14.3 parts by mass of morpholine, 7.1 parts by mass of lactic acid, and 3.6 parts by mass of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Example 7

A titanium oxide coating solution was prepared by mixing and stirring 42.1 parts by weight of triethanolamine, 21.0 parts by weight of phosphoric acid, and 52.6 parts by weight of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by weight of photocatalyst particles.

Example 8

A titanium oxide coating liquid was prepared by mixing and stirring 5.7 parts by weight of tetramethylammonium, 25.0 parts by weight of glycolic acid, and 57.1 parts by weight of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by weight of photocatalyst particles.

Example 9

A titanium oxide coating solution was prepared by mixing and stirring 2.9 parts by mass of morpholine, 17.9 parts by mass of phosphoric acid and 1.4 parts by mass of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Example 10

A titanium oxide coating solution was prepared by mixing and stirring 7.1 parts by weight of piperidine, 4.3 parts by weight of glycolic acid, and 39.3 parts by weight of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by weight of photocatalyst particles.

Comparative Example 1

A titanium oxide coating solution was prepared by mixing and stirring 4.3 parts by mass of monoethanolamine, 5.7 parts by mass of polyphosphoric acid, and 14.3 parts by mass of spherical curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Comparative Example 2

A titanium oxide coating liquid was prepared by mixing and stirring 4.3 parts by mass of sodium hydroxide, 5.7 parts by mass of polyphosphoric acid, and 14.3 parts by mass of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Comparative Example 3

A titanium oxide coating solution was prepared by mixing and stirring 4.3 parts by weight of monoethanolamine, 5.7 parts by weight of benzalkonium chloride (cationic dispersant), and 14.3 parts by weight of plate-shaped curable particles to an aqueous dispersion sol containing 100 parts by weight of photocatalyst particles.

[Comparative Example 4]

A titanium oxide coating liquid was prepared by mixing and stirring 5.7 parts by mass of polyphosphoric acid and 14.3 parts by mass of spherical curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

[Comparative Example 5]

A titanium oxide coating solution was prepared by mixing and stirring 4.3 parts by mass of monoethanolamine and 14.3 parts by mass of spherical curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Comparative Example 6

A titanium oxide coating liquid was prepared by mixing and stirring 4.3 parts by mass of monoethanolamine and 5.7 parts by mass of polyphosphoric acid to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Comparative Example 7

A titanium oxide coating solution was prepared by mixing and stirring 8.6 parts by weight of sodium hydroxide, 21.4 parts by weight of polyphosphoric acid, and 35.7 parts by weight of spherical curable particles to an aqueous dispersion sol containing 100 parts by weight of photocatalyst particles.

Comparative Example 8

A titanium oxide coating solution was prepared by mixing and stirring 8.3 parts by mass of potassium hydroxide, 0.3 parts by mass of lactic acid, and 250.0 parts by mass of spherical curable particles to an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

Comparative Example 9

A titanium oxide coating solution was prepared by mixing and stirring 55.6 parts by mass of spherical curable particles in an aqueous dispersion sol containing 100 parts by mass of photocatalyst particles.

[characteristic]

The coating solution of each of the above examples was applied to the substrate by a bar coater such that the film thickness was 2.5 μm. Substrate, the acrylic resin was used for coating an aluminum alloy and the glass plate subjected to SiO ₂ primer coat. In addition, the glass plate was used for evaluation of transparency.

And the thing of Examples 1-6, Example 10, Comparative Examples 1-7, and Comparative Example 9 was heat-dried at 300 degreeC for 10 minutes.

In Examples 7 to 9 and Comparative Example 8, ultraviolet rays having a wavelength of 360 nm and an intensity of 2 mW / cm 2 were irradiated for 24 hours.

Since the performance of the coating film thus obtained was evaluated by the following test methods and evaluation criteria, the results are shown in Table-1 below.

[Transparency]

O: visible light transmittance of glass test piece is 70% or more

△: visible light transmittance of glass test piece is 40% or more and less than 70%

X: Visible light transmittance of a glass test piece being less than 40%

[Adhesiveness]

The adhesion of the coating film was determined according to the JIS-K 5400 checkerboard scale tape coating film adhesion test.

0: peeling of a coating film is not recognized

Δ: partial peeling of the coating film is recognized

X: The whole coating film peeled

[Photocatalytic Activity]

An aluminum test piece of 100 × 100 mm was placed in a 3 L Pyrex glass container, sealed, and injected with acetaldehyde gas so as to have a concentration of 300 ppm. Ultraviolet rays were irradiated with 20 W black light for 3 hours, the aldehyde concentration after irradiation was measured by a gas detector tube, the removal rate was calculated, and the degradability by the photocatalyst was measured.

Transparency Adhesion Acetaldehyde removal rate (%) Example 1 ○ ○ 95 Example 2 ○ ○ 92 Example 3 ○ ○ 92 Example 4 ○ ○ 94 Example 5 ○ ○ 91 Example 6 ○ ○ 94 Example 7 ○ ○ 89 Example 8 ○ ○ 90 Example 9 ○ ○ 94 Example 10 ○ ○ 92 Comparative Example 1 △ × 75 Comparative Example 2 × △ 78 Comparative Example 3 △ × 78 Comparative Example 4 △ × 70 Comparative Example 5 △ × 72 Comparative Example 6 △ × 76 Comparative Example 7 △ × 55 Comparative Example 8 △ × 65 Comparative Example 9 △ △ 70

The coating film formed by apply | coating the coating composition of this invention is excellent in adhesiveness with a base material, Furthermore, high transparency is obtained, The outstanding catalyst activity is obtained, and the practical photocatalyst member can be obtained. For example, it can be applied to various purposes such as deodorization, pollution decomposition, and antibacterial, and its practical value is very large.

Claims (11)

Photocatalyst particles, With organic alkali, Anionic dispersants, A coating composition containing curable plate-shaped particles. The coating composition according to claim 1, wherein the photocatalyst particles are particles containing one selected from the group consisting of titanium oxide and titanic acid. The coating composition according to claim 1, wherein the organic alkali is an alkali containing one selected from the group consisting of alkanolamine, tetraalkylammonium, oxazine, piperidine and choline. The coating composition according to claim 1, wherein the anionic dispersant is a dispersant containing one selected from the group consisting of condensed phosphoric acid, phosphoric acid, hydroxycarboxylic acid, polyvalent carboxylic acid, and polycarboxylic acid. The coating composition according to claim 1, wherein the curable plate-shaped particles have SiO ₂ as a main component, and their aspect ratio is 10 to 300. The amount of the organic alkali is 0.5 to 100 parts by mass, 0.5 to 50 parts by mass of the anionic dispersant, and 0.5 to 400 parts by mass of the curable plate-shaped particles, based on 100 parts by mass of the photocatalyst particles. Paint compositions. An application step of applying the coating composition according to claim 1 to a substrate, And an organic alkali decomposition step of decomposing the organic alkali in the coating film after the coating step. 8. The method for forming a film having a photocatalytic function according to claim 7, wherein the organic alkali decomposition step is a step by heating. 8. The method of forming a film having a photocatalytic function according to claim 7, wherein the organic alkali decomposition step is a step by light irradiation. The coating composition of Claim 1 is apply | coated, The photocatalyst member characterized by the above-mentioned. It is formed by the formation method of the film | membrane which has a photocatalyst function of Claim 7, The photocatalyst member characterized by the above-mentioned.