JPH0940872A - Composition containing photocatalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition, containing a photocatalyst, comprising titanium oxide having the photocatalytic actions, curable at low temperatures by the actions of the catalyst, good in adhesion and excellent in resist printing and antimicrobial coatings. etc. SOLUTION: This composition, contains a photocatalyst and comprises (A) titanium oxide having photocatalytic actions, (B) a hydrolyzable organometallic compound (preferably a metallic alkoxide) and (C) an aqueous solvent (preferably an organic solvent containing water) and preferably further (D) a boron compound or halide ions as a curing catalyst or (E) a dispersing agent. A powder having an anatase crystal type is preferably used as the component (A) and a powder having 1-100nm particle diameter and 10-700m<2> /g, especially 30-500m<2> /g specific surface area is preferred as the component (A). The respective components are preferably blended by adding water and the catalyst (especially a halogen) just before use when the preservation stability is required. The temperature for preparing the component is 0-150 deg.C, preferably 10-100 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition containing titanium oxide having photocatalytic activity, and more particularly to a coating composition.

[0002]

2. Description of the Related Art Various applications are known for titanium oxide having a photocatalytic action. For example, it adheres to walls and surfaces of sanitary equipment to exert antibacterial action, decomposes and purifies organic compounds in wastewater, decomposes and purifies ammonia, sulfur compounds and organic substances in the atmosphere, and is used for sterilizing water. Applications such as use for air purification have been proposed. In particular, as a method for coating titanium oxide, there is known a method in which colloidal silica or colloidal titania is used as a binder and dried and baked at a temperature of 200 ° C. or higher. It is known that when an organic compound is used as a binder, the binder is decomposed by a photocatalytic action and does not play a role.

[0003]

However, the known coating method requires a baking treatment at a high temperature for a long time, and there are problems of simplicity, coating speed, and adhesion to a substrate, and improvement thereof is desired. It was In addition, like the spraying of glass
In the towing, there was a problem that the surface of the photocatalyst was covered and the activity decreased.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a coating composition containing titanium oxide which acts as a photocatalyst, and more particularly a coating composition which is cured at a low temperature by the action of a catalyst and has good adhesion. That is, the present invention provides a composition containing (1) titanium oxide having photocatalytic activity, a hydrolyzable organometallic compound, and an aqueous solvent. (2) titanium oxide having photocatalytic activity, a hydrolyzable organometallic compound, and A coating composition containing an aqueous solvent (3) A composition according to (2) containing a boron compound as a curing catalyst (4) A halogen ion as a curing catalyst (2),
(3) Composition (5) Dispersant-containing composition (2) (3) (4) Composition (6) (2) Hydrolyzable organometallic compound is metal alkoxide Certain composition (7) The composition according to (4), wherein the halogen ion is fluorine, bromine or chlorine ion.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail. As the titanium oxide having a photocatalytic action, it is preferable to use a powder having an anatase type crystal form. Its particle size is 1
100 nm, specific surface area 10-700 square meters / g
Is preferred, especially those having 30 to 500 square meters / g. The amount used is 5 to 95%, preferably 10 to 80% of the total solids (hereinafter simply referred to as solids) excluding the solvent in the composition.

The hydrolyzable organic metal compound is not particularly limited, but a metal alkoxide is most preferable, and a compound partially substituted with an alkyl group, an aryl group, a halogen or the like can also be used. Specific examples of compounds include lithium ethoxide, magnesium isopropoxide, aluminum isopropoxide, aluminum ethoxide, zinc isopropoxide, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, zirconium propoxide, zirconium acetyl. Acetonate, titanium tetrapropoxide, titanium tetraethoxide, titanium tetraoctadecyl oxide, titanium oxyacetylacetonate, triethyl borate, trimethyl borate, barium ethoxide, barium butoxide and the like. They can be used alone or in combination of two or more. The amount used is 10% to 50 times that of titanium oxide as a photocatalyst. 30% to 30 times is particularly preferable. The titanium oxide of the photocatalyst is used by adjusting it so that the solid content is in the above-mentioned proportion.

As the aqueous solvent, an organic solvent containing water is most suitable. As the organic solvent, methanol,
Ethanol, propanol, butanol, ethylene glycol, propylene glycol, etc., alcohols, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc. ketones, ethyl acetate, butyl acetate, etc. esters , Ethyl cellosolve, butyl cellosolve, etc., and dioxane, tetrahydrofuran, etc., ethers. It is also possible to add a halogen-based solvent such as chloroform, methylene chloride or dichloroethane, or a hydrocarbon-based solvent such as toluene or xylene.

The amount of the solvent used is 2% to 80% as solid content.
%, Preferably 5% to 60%. The amount of water used may be the theoretical amount necessary for the hydrolysis reaction, but in order to proceed the reaction smoothly, 0.01
% To 90%, preferably 0.5% to 70%. However, even if there is no theoretical amount of water, there is no problem because water in the air is also used. It is preferable to add water before curing because there is a problem of storage stability.

The liquidity during the reaction is preferably pH 4 to 10. However, if the object to be applied is not affected, it is possible to use acidity or basicity outside this range. Acids or bases act as catalysts for the hydrolysis. Mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid can be used as the acid or base, and caustic alkalis such as caustic soda and caustic potash, and organic amines such as ammonia, triethylamine and pyridine can be used as the base. In the near neutral region, it is preferable to use a boron compound and / or a halogen ion as a curing catalyst.

As the boron compound, boric acid ester,
Boron tetrahalide salts are used. As boric acid ester, trimethyl borate, triethyl borate, tripropyl borate, tributyl borate and the like are preferable. As the boron tetrahalide salt, organic amine salts such as triethylamine salt, pyridinium salt of boron tetrafluoride, ammonium salt and the like are effective. The amount used is preferably 0.001 to 10% by weight as the concentration in the solution, and about 0.1% to 50% by weight with respect to the hydrolyzable organometallic compound.

The halogen ion-releasing compound may be hydrochloric acid, hydrobromic acid, hydrofluoric acid, or an organic amine salt such as sodium, potassium, ammonium salt, triethylamine salt or pyridine salt and an acid salt thereof. The concentration is 0.001 to 1 mol / L, preferably 0.002 to 0.2 mol / L.

The composition containing the above components can be prepared by mixing the predetermined components before use. At this time, if the dispersed state is not good, a dispersant can be used.
As the dispersant, polyacrylic acid, polymethacrylic acid,
Styrene-maleic anhydride copolymers and other polycarboxylic acid type dispersants, lignin sulfonic acid, naphthalene sulfonic acid and other sulfonic acid type dispersants, nonionic type dispersants,
Polyvinyl alcohol, fatty acid sugar ester sugar alcohol
A le-type dispersant or the like can be used, and the amount thereof is preferably 0.01% to 5%, particularly preferably 0.05% to 2% in the system.

For mixing, an efficient stirrer may be used, but an inking machine such as a planetary ball mill, a dyno mill, a homomixer or a sand grinder can also be used.

There are no particular restrictions on the procedure for mixing the components, but when storage stability is required, it is preferable to add water and a catalyst (especially halogen) immediately before use. Therefore, it is desirable to use the two-pack type. The adjusting temperature of the composition is 0 ° C to 150 ° C, preferably 10 ° C to 100 ° C.
A degree is desirable. Depending on the solvent, a temperature that does not exceed its boiling point is desirable.

When the prepared composition is used as a coating composition, it is applied to a target surface by using a coater. Various printing methods are possible, and spray coating can also be used using a spray. Brush coating and spin coating are also possible. The object is plastics,
It can be used for glass, metal, paper, wood, ceramics, ceramics, etc. The film thickness to be applied is not particularly limited, but is 0.2 μm to 5 mm, preferably 0.5 to 1 mm. If it is too thick, the photocatalytic cure will be low relative to the amount of titanium oxide. The coating is preferably performed at room temperature, and in some cases, the coating can be performed while heating at 50 to 100 ° C.

The coated surface is cured at 20 to 200 ° C. It is preferably 50 to 150 ° C. The curing time is
Although it varies depending on the type of solvent, the boron compound, the type of catalyst, and the liquidity, it can be cured in 10 seconds to 5 minutes at a temperature of about 150 ° C. In addition to being used for coating, the composition of the present invention can be used by being added to an adhesive, a sizing agent, a plasticizer, a paint, a photosensitizer paste, a microbial medium, etc. for the purpose of sterilization and bacteriostatic.

[0017]

EXAMPLES Examples will be described below.

Example 1 25 g of zirconium tetrabutoxide, 5 g of isopropyl alcohol, 1 g of methanol, and 1 g of ethanol were beaded.
It was placed in a car and stirred with a magnetic stirrer. 1 g of triethyl borate was further added thereto. Further, here, anatase-type titanium oxide having a specific surface area of 320 square meters / g (Type ST-01; trade name of Ishihara Sangyo Co., Ltd.) 2
5 g were added. In a separate container, 1 g of water and 0.1 g of ammonium acid fluoride were taken and stirred. The obtained two liquids and 0.1 g of polyacrylic acid (molecular weight 120,000) were charged in a planetary ball mill and made into ink at 40 ° C. for 30 minutes. The pH of this product was 6. This was coated in glass form with a coating rod. When this was heat-treated in a dryer at 150 ° C. for 2 minutes, a white film was obtained. The film thickness was 60 μm. When I scratched it with a knife, it partly came off, but it did not come off at my fingertips.

Example 2 Instead of the zirconium tetrabutoxide of Example 1, 25 g of tetraethoxysilane was used. Also the solvent 1
The same amount of butyl cellosolve was used instead of ethanol as a component. Others were treated in the same manner to obtain an ink. This product had a PH of 6 and was applied to a surface-treated polyester film with a coating rod. After heat treatment at 130 ° C. for 3 minutes, a white coating film was obtained. The film thickness was 50 μm. When I scratched it with a knife, it partly came off, but the toe did not.

Example 3 10 g of tetraethoxysilane, 5 g of aluminum triisopropoxide, 10 g of diisopropoxy lead, 1 g of titanium tetraoctadecyl oxide, isopropyl alcohol.
5 g, methyl isobutyl ketone 1 g, and tetrahydrofuran 1 g were placed in a beaker and stirred with a magnetic stirrer. 1 g of trimethyl borate was further added thereto.
Furthermore, 15 g of anatase type titanium oxide (Type ST-11; trade name of Ishihara Sangyo Co., Ltd.) having a specific surface area of 60 square meters / g was added thereto. Further, 1 g of water was added and hydrochloric acid was adjusted to 0.
After adding 1 and stirring for 10 minutes, ammonia water was added and pH was adjusted to 5. Then, 0.1 g of polyvinyl alcohol (molecular weight 250,000) was charged into a planetary ball mill at 40 ° C.
It was made into ink for 30 minutes. This was coated on glass with a coating rod. When this was heat-treated in a dryer at 150 ° C. for 2 minutes, a white film was obtained. The film thickness was 90 μm. When I scratched it with a knife, it didn't come off at the tip of the toe.

Example 4 The coating composition obtained in Example 1 was used as an aluminum alloy.
It was applied on the aluminum plate. A thin film with good adhesion was obtained. It did not come off on the toes.

Example 5 The photocatalyst coatings obtained in Examples 1 to 3 were beaded.
Soaked in water in the car. When left outdoors in Tokyo from March to May, there was no change in the surface. A large amount of green algae adhered to the surface of the beaker containing no photocatalytic coating.

Example 6 The aluminum plate surface-coated in Example 4 was
It was left in the room for 3 months. No stain on the white film was observed.

[0024]

The coating having a photocatalytic action can be easily performed, and the applications such as antifouling coating and antibacterial coating can be expanded.

Claims (7)

[Claims] 1. A composition containing photocatalytic titanium oxide, a hydrolyzable organometallic compound, and an aqueous solvent. 2. A coating composition containing titanium oxide having photocatalysis, a hydrolyzable organometallic compound, and an aqueous solvent. 3. The composition according to claim 2, which contains a boron compound as a curing catalyst. 4. The composition according to claim 2, which contains a halogen ion as a curing catalyst. 5. The composition according to claim 2, 3 or 4 containing a dispersant. 6. A composition in which the hydrolyzable organometallic compound according to claim 2 is a metal alkoxide. 7. A composition in which the halogen ion according to claim 4 is a fluorine, bromine or chlorine ion.