JPH10195341A - Photocatalytic coating material, production thereof, and coating film formed therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a titanium oxide-based photocatalytic coating material excellent in photocatalytic activity and transparency, its production process, and a coating film formed by applying the same. SOLUTION: This coating material comprises superfine-particle anatase titanium oxide having an average primary particle size of 0.01-0.1μm, an org. solvent, a β-diketone, a titanate or aluminate coupling agent, and a silica sol. The content of the titaium oxide is 0.5-20wt.%; the β-diketone is added in an amt. of 0.5-10.0wt.% of the titanium oxide; and the coupling agent is added in an amt. of 0.1-5.0wt.% of the titanium oxide. The material is prepd. by dispersing the titanium oxide in a solvent homogeneously to a high degree. The coating film is formed by applying the material to a substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a titanium oxide-based photocatalytic paint having excellent photocatalytic activity and transparency, a method for producing the same, and a coating film formed by applying the same.

[0002]

2. Description of the Related Art As described in JP-A-7-100378, a method of forming a photocatalytic thin film is known in which a titania sol prepared from an alkoxide of titanium and an alcoholamine is coated on a substrate and then fired. Have been. Also known is a method for producing a two-layer coating type coating film in which an undercoat film is provided between the substrate and the titanium oxide layer in order to protect the substrate and improve the adhesion with the titanium oxide layer.

[0003]

According to the conventional technique described above, in the method of firing using titania sol, since the firing treatment is performed at a high temperature, there is a risk that the transparency of the film is reduced. Necessary and can be processed at low temperature 2
The layer coat type requires two coatings and drying, which are not simple methods, and in order to sufficiently bring out the activity of the photocatalyst, the content of titanium oxide must be 80% by weight or more. In this case, there is a problem that the transparency of the formed film itself and the adhesion between the titanium oxide particles and the substrate are not sufficient and a stable film cannot be formed.
With the expansion of uses of photocatalysts, development of photocatalytic paints capable of forming excellent coating films having higher activity, higher transparency and higher adhesion has been demanded.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to respond to the above-mentioned demands. As a result, the present inventors have found that ultrafine particles having an average primary particle diameter of 0.01 μm to 0.1 μm and a crystal form of anatase type are obtained. The titanium oxide is highly dispersed in an organic solvent in the presence of a β-diketone and a titanate-based or aluminate-based coupling agent, and is uniformly mixed with a silica sol. It was found that it could be formed.

The present invention has been made based on the above findings. (1) Ultrafine anatase type titanium oxide having an average primary particle diameter of 0.01 μm to 0.1 μm, an organic solvent, β-
(2) The photocatalytic coating according to (1), wherein the content of the titanium oxide is 0.5 to 20% by weight, (3) the photocatalytic coating comprising a diketone, a titanate-based or aluminate-based coupling agent and silica sol. (1) or (2) wherein the amount of β-diketone is 0.5 to 10.0% by weight based on the titanium oxide.
(4) The titanate-based or aluminate-based coupling agent is added in an amount of 0.1 to 0.1 with respect to the titanium oxide.
(5) The titanium oxide is mixed with a β-diketone and a titanate-based or aluminate-based coupling agent in the presence of the organic compound. The method for producing a photocatalytic coating according to any one of (1) to (4), which is uniformly dispersed in a solvent and then mixed with the silica sol. (6) The method according to any one of (1) to (4). A coating film formed by applying the photocatalytic paint of (1) to a substrate, and a glass to which the coating films of (7) and (6) can be applied. (8) Plastic to which the coating film of (6) can be applied. (9) A metal to which the coating film of (6) can be applied. (10) Wood to which the coating film of (6) can be applied. (11) Building materials to which the coating film of (6) can be applied. (12) Paper on which the coating film of (6) can be applied. (13) A film to which the coating film of (6) can be applied. It is characterized by the following.

In the present invention, the average primary particle size (hereinafter, referred to as the primary particle size)
Ultrafine titanium oxide (anatase type) having a particle diameter of 0.01 μm to 0.1 μm is referred to as an average primary particle diameter.
In a liquid consisting of β-diketone and titanate or aluminate coupling agent, it is uniformly and highly dispersed to a state close to the primary particles, and a coating material obtained by uniformly mixing an appropriate amount of silica sol is obtained. A thin and uniform coating is possible by applying on top, and the adhesion between titanium oxide particles and the substrate is increased by the action of β-diketone, coupling agent, and silica sol, and stable coating film formation Was obtained.

In the present invention, the β-diketone has a polar functional group (ketone group) acting on the titanium oxide fine powder and a polar group (hydroxyl group, oxygen group) present on the surface of the substrate and condensing during baking. It is presumed that close packing of the fine titanium oxide powder occurred, and the powder and the substrate were bonded to each other to act as a film-forming agent to increase the adhesion.

Further, in the present invention, the coupling agent acts as a haze reducing agent, and by adding the same, a secondary aggregation group is not formed in the film structure, and uniform close-packing and surface smoothness are achieved. It is presumed that haze is reduced (transparency is improved) due to the further increase in the haze.

Further, even if the content of the titanium oxide fine powder is increased by the uniform mixing of the silica sol (80% by weight or more), sufficient catalytic activity can be obtained without lowering the transparency by the uniform mixing action of SiO2. And the effect of further improving the adhesion to the substrate by the action of the silica sol is obtained.

As the organic solvent of the present invention, any organic solvent capable of dissolving components other than the titanium oxide fine powder and SiO2 (or having compatibility with liquid components) can be used. However, of course,
Components used as the film-forming agent coupling agent in the present invention are excluded from the solvent. Examples of suitable solvents include alcohols such as methanol (hereinafter referred to as A-1), ethanol (A-2), isopropanol (A-3), butanol (A-4), and acetone (A-
5), ketones such as methyl ethyl ketone (A-6), methyl isobutyl ketone (A-7), cyclohexanone (A-8), isophorone (A-9), and toluene (A-1)
0), xylene (A-11), hexane (A-12),
Hydrocarbons such as cyclohexane (A-13), N, N-
Examples include amides such as dimethylformamide (A-14) and sulfoxides such as dimethyl sulfoxide (A-15). Depending on the components used, one or more solvents are selected so as to dissolve them. I do. The amount of the solvent is not particularly limited as long as a composition having a viscosity suitable for application can be obtained.

The β-diketone of the present invention includes 2,4-
Pentanedione (hereinafter referred to as B-1), 3-methyl-2,4-pentanedione (B-2), 3-isopropyl-2,4-pentanedione (B-3), 2,2-dimethyl -3,5-hexanedione (B-4) and the like.

The coupling agent of the present invention includes an aluminate-based coupling agent containing an acetoalkoxy group, and a titanate-based coupling agent containing a dialkylpyrophosphate group or a dialkylphosphite group. Examples of the aluminate-based coupling agent containing an acetoalkoxy group include a compound represented by the following formula (a). Examples of the titanate coupling agent having a dialkyl pyrophosphate group include compounds represented by the following formulas (b) to (d). Examples of the titanate coupling agent having a dialkyl phosphite group include: There are compounds represented by formulas (e) to (f). One or more of these can be used.

[0013]

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An embodiment of the present invention will be described. First, a predetermined amount of anatase-type titanium oxide fine powder having a predetermined average primary particle size is prepared, and an appropriate amount of an organic solvent,
β-diketone and a liquid comprising a titanate-based or aluminate-based coupling agent were mixed and, for example, uniformly dispersed with a predetermined amount of zirconia beads using a paint shaker for a predetermined time. Thereafter, the mixture was uniformly mixed with an appropriate amount of a silica sol solution having a predetermined concentration to prepare the paint of the present invention. This coating material was applied to a predetermined substrate using, for example, a spin coater, and dried at a predetermined temperature for a predetermined time to prepare a photocatalytic coating film. The haze and photocatalytic activity of this coating were measured. The haze of the coating film of the present invention was 1.0% or less and had high transparency.
In addition, the photocatalytic activity was excellent, the film adhesion was good, and a stable photocatalytic coating film was obtained.

The coating film of the present invention can be obtained by spin coating, dipping, spraying or the like. By changing the type of solvent and the mixing ratio, it is possible to obtain a drug corresponding to any of the methods, and therefore, the application method is not particularly limited.

The glass on which the coating film of the present invention can be applied includes:
Indoor environment purification (contaminant decomposition) glass such as fluorescent lamps and windows,
Water purification glass for aquariums, fish cages, anti-fog glass for cars,
There are antifouling glass such as CRTs, LCD screens, windows, mirrors, spectacles, etc., cameras, antifouling of optical devices, and antifungal lenses.

The plastics to which the coating film of the present invention can be applied include AV equipment, computers, mice, keyboards and the like.
Devices, such as computers, remote controllers, floppy disks, and peripheral products thereof, as well as antifouling, antibacterial, and antifungal plastics used for household goods used in car interiors, furniture, kitchens, baths, toilets, and the like.

Metals to which the coating film of the present invention can be applied include antifouling, antibacterial, and antifungal stainless steels used for clothes racks, clothes poles, kitchens, work tables and washing rooms in laboratories, ventilation fans, and the like.
There are antifouling and antibacterial treatment door knobs.

Wood applications to which the coating film of the present invention can be applied include antifouling furniture, antibacterial game facilities in parks, and the like. As a building material on which the coating film of the present invention can be applied, an antifouling treated outer wall material,
There are roofs, flooring materials, and other inner wall materials that have indoor environmental purification (contaminant decomposition) properties, and various interior products that have been subjected to antifouling, antibacterial, and antifungal treatments. The paper on which the coating film of the present invention can be applied can be used for antibacterial treatment stationery and the like.

Applications of the film to which the coating film of the present invention can be applied include a transparent antibacterial film for food packaging, a transparent ethylene gas decomposition film for storing vegetables, and a film for environmental and water purification.

As described above, the various substrates coated with the coating film of the present invention exert the effects of antifouling, environmental purification, antibacterial and antifungal, so that irradiation of ultraviolet rays (including sunlight, fluorescent light) is effective. If possible, it can be used for many applications other than those exemplified.

[0022]

EXAMPLES Examples of the present invention will be specifically described below. Of course, the present invention is not limited to the embodiments. An organic solvent, a β-diketone, and a titanate-based or aluminate-based coupling agent are mixed with titanium oxide fine particles having an average primary particle diameter as described in Table 1 in the same composition as shown in Table 1. And zirconia beads 1
From 00 g, the mixture was dispersed with a paint shaker for 16 hours. Thereafter, the mixture was mixed with a 10% by weight silica sol solution, and mixed with the photocatalyst paints 1 to 10 of the present invention (hereinafter simply referred to as paints 1 to 10 of the present invention).
). Each of these paints was applied to a glass substrate by a spin coater, and dried at 150 ° C. for 1 hour, to thereby prepare coating films 1 to 10 of the present invention. In order to evaluate each coating film, haze (Haze Computer HGM-3D manufactured by Suga Test Instruments) and photocatalytic activity of each coating film were measured. The photocatalytic activity was determined by placing a glass plate coated with a photocatalyst film in a 1-liter Pyrex container, sealing the mixture, introducing 2 μl of acetaldehyde, and measuring the acetaldehyde concentration after irradiation with a UV lamp for 2 hours using a gas-tech detector tube. . [Removal rate (%) = [(initial density−density after light irradiation) / initial density] × 100] The measurement results are shown in Table 2.

Next, for comparison, paints having a composition as shown in Table 1 which lacked any of the paint components of the present invention or contained only a value less than the prescribed amount were prepared as comparative paints 1 to 4. Comparative coating films 1 to 4 were formed in the same manner as in the above examples, and the haze and photocatalytic activity of the coating films were measured.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

As is clear from Table 2, the coating films 1 to 5 of the present invention were obtained.
No. 10 has a low haze value, a high acetaldehyde removal rate, and forms an excellent coating film having high catalytic activity and high transparency as compared with Comparative coating films 1 to 4. Such an excellent coating film was obtained because, in a liquid composed of an organic solvent, β-diketone, a titanate-based or aluminate-based coupling agent, and silica sol, titanium oxide fine particles as a photocatalyst were primary This is because a paint uniformly dispersed to a state close to particles is obtained, and this paint can be applied thinner and more uniformly on the substrate, and the smoothness of the surface is further improved. By increasing the bonding between the substrates and improving the adhesion, the durability as a coating film is also enhanced, which contributes to the expansion of the use of the photocatalyst.

Claims (13)

[Claims] An average primary particle size of 0.01 μm to 0.1 μm.
A photocatalytic paint comprising 1 μm ultrafine anatase type titanium oxide, an organic solvent, β-diketone, titanate or aluminate coupling agent, and silica sol. 2. The titanium oxide content is 0.5 to 20.
2. The photocatalytic coating according to claim 1, wherein the content is by weight. 3. The photocatalytic paint according to claim 1, wherein the amount of the β-diketone is 0.5 to 10.0% by weight based on the weight of the titanium oxide. . 4. The amount of the titanate-based or aluminate-based coupling agent added to the titanium oxide in a range of about 0.1 to about 0.5%.
The photocatalytic paint according to any one of claims 1 to 3, wherein the content is 1 to 5.0% by weight. 5. The method according to claim 1, wherein the titanium oxide is uniformly dispersed in the organic solvent in the presence of a β-diketone and a titanate or aluminate coupling agent, and then mixed with the silica sol. Claims 1 to 4
The method for producing a photocatalytic paint according to any one of the above. 6. A coating film formed by applying the photocatalytic coating material according to claim 1 to a substrate. 7. A glass to which the coating film according to claim 6 can be applied. 8. A plastic to which the coating of claim 6 can be applied. 9. A metal to which the coating of claim 6 can be applied. 10. Wood to which the coating of claim 6 can be applied. 11. A building material to which the coating film according to claim 6 can be applied. 12. A paper to which the coating of claim 6 can be applied. 13. A film on which the coating film according to claim 6 is applied.