Photocatalytic coating material, production thereof, and coating film formed therefrom

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

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】

[Conventional technology]

As described in JP-A-7-100378, a method of coating a titania sol prepared from titanium alkoxide and alcohol amines on a substrate and then firing it is known as a method of forming a photocatalytic thin film. Further, in order to protect the substrate and improve the adhesion to the titanium oxide layer, 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 is also known. In addition to these methods, the present inventors have higher activity, higher transparency, and higher adhesion than the above-mentioned conventional techniques by applying a coating film obtained by dispersing ultrafine titanium oxide in a silica sol. Finding a paint film.

【0003】

[Problems to be Solved by the Invention]

However, there are limits to the effects obtained from the photocatalytic function of titanium oxide in the coating film obtained by dispersing the above-mentioned titanium oxide in silica sol, the transparency and adhesion of the produced coating film, and higher activity and higher transparency. There has been a demand for the development of a photocatalytic paint capable of forming a coating film having better high adhesion.

【0004】

[Means for solving problems]

In order to meet the above demands, the present inventors have further studied using various oxide powders instead of titanium oxide, and as a result, have added silicon and / or iron to titanium oxide instead of titanium oxide powder. -It was found that a more active coating film can be obtained while maintaining high transparency and high adhesion by using a titanium oxide-based composite oxide (hereinafter, simply referred to as a composite oxide). It was.

【0005】

The present invention has been obtained based on the above findings. (1) Photocatalytic paint consisting of ultrafine titanium oxide-based composite oxide with an average particle size of 0.01 μm to 0.1 μm of primary particles, an organic solvent, β-diketone, titanate-based or aluminate-based coupling agent, and silica sol. , (2) The photocatalytic coating material according to (1), wherein the composite oxide is formed by coating titanium oxide with either silicon and / or iron. (3) The photocatalytic coating material according to any one of (1) to (2), wherein the composite oxide is titanium oxide coated with either silicon and / or iron in an amount of 0.1 to 20% by weight. (4) The photocatalytic coating material according to any one of (1) to (3), wherein the content of the composite oxide is 0.5 to 20% by weight. (5) The photocatalytic coating material according to any one of (1) to (4), wherein the amount of the β-diketone added is 0.5 to 10.0% by weight based on the composite oxide. (6) The photocatalytic paint according to any one of (1) to (5), wherein the amount of the titanate-based or aluminate-based coupling agent added is 0.1 to 10.0% by weight based on the composite oxide. (7) The composite oxide is uniformly dispersed in the organic solvent in the presence of β-diketone and a titanate-based or aluminate-based coupling agent, and then mixed with the silica sol (1) to (6). The method for producing a photocatalytic paint according to any one of. (8) A coating film formed by applying the photocatalytic paint according to any one of (1) to (6) above to a base material. (9) Glass to which the coating film described in (8) can be applied. (10) A plastic to which the coating film described in (8) can be applied. (11) A metal to which the coating film described in (8) can be applied. (12) Wood to which the coating film described in (8) can be applied. (13) A building material to which the coating film described in (8) can be applied. (14) Paper to which the coating film described in (8) can be applied. (15) A film to which the coating film described in (8) can be applied. It has the characteristics of.

【0006】

In the present invention, the composite oxide of ultrafine particles having an average particle size (hereinafter referred to as an average primary particle size) of 0.01 μm to 0.1 μm of the primary particles is an organic solvent, β-diketone, and a titanate-based or aluminate-based cup. In a liquid composed of a ring agent, the particles are uniformly dispersed to a state close to that of primary particles, and an appropriate amount of silica sol is uniformly mixed therein to obtain a paint. Furthermore, by applying this on the substrate, it is possible to apply it thinly and uniformly, and the adhesion between the composite oxide particles and with the substrate is improved by the action of β-diketone, the coupling agent, and the silica sol, and it is stable. A coating film was formed.

【0007】

The composite oxide used in the present invention is an ultrafine particle powder having an average particle size of 0.01 μm to 0.1 μm, which is formed by adding silicon and / or iron to titanium oxide. By using a composite oxide in which silicon and / or iron is added to titanium oxide, a coating film having higher catalytic activity can be obtained as compared with the case where ordinary titanium oxide is used.

【0008】

In the present invention, in the β-diketone, the polar functional group (ketone group) acts on the composite oxide and the polar group (hydroxyl group, oxygen group) existing on the surface of the substrate, and the composite oxide is condensed during baking to form the composite oxide. It is presumed that the dense packing of the fine powder occurred, the powder and the powder and the substrate were bonded to each other, and acted as a film-forming agent to improve the adhesion.

【0009】

Further, in the present invention, the coupling agent acts as a low haze agent, and by adding this, a secondary agglutination group is not formed in the film structure, and uniform closest packing and surface smoothing accuracy are further improved. It is presumed that the haze decreases (transparency improves) because it is increased.

【0010】

Further, by uniformly mixing the silica sol, sufficient catalytic activity can be obtained without lowering the transparency even if the content of the composite oxide is increased (80% by weight or more), and further, the action of the silica sol makes it possible to obtain sufficient catalytic activity with the substrate. Adhesion is further improved.

【0011】

The organic solvent of the present invention includes composite oxides and SiO.₂Any organic solvent capable of dissolving components other than the above (or, for liquid components, having compatibility with the components) can be used. However, as a matter of course, the 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 (referred to as A1, the same applies hereinafter), ethanol (A2), isopropanol (A3), butanol (A4), acetone (A5), methyl ethyl ketone (A6), methyl isobutyl ketone. Ketones such as (A7), cyclohexanone (A8), isophorone (A9), hydrocarbons such as toluene (A10), xylene (A11), hexane (A12), cyclohexane (A13), N, N-dimethylformamide Examples thereof include amides such as (A14) and sulfoxides such as dimethyl sulfoxide (A15), and one or two kinds of these solvents are selected so as to dissolve them depending on the components used. The amount of the solvent may be any amount as long as a composition having a viscosity suitable for coating can be obtained, and is not particularly limited.

【0012】

The β-diketone of the present invention includes 2,4-pentanedione (referred to as B1 and the same applies hereinafter), 3-methyl-2,4-pentanedione (B2), and 3-isopropyl-2,4-pentanedione (B3). ), 2,2-Dimethyl-3,5-hexanedione (B4) and the like.

【0013】

Examples of the coupling agent of the present invention include an aluminate-based coupling agent containing an acetoalkoxy group, and a titanate-based coupling agent containing a dialkylpyrophosphate group or a dialkylphosphite group. An example of an aluminate-based coupling agent containing an acetoalkoxy group is a compound represented by the following formula (a). Further, in the example of the titanate-based coupling agent having a dialkylpyrophosphate group, there are compounds represented by the following formulas (b) to (d), and in the example of the titanate-based coupling agent having a dialkylphosphite group, the following There are compounds represented by equations (e) to (f). One or more of these can be used.

【0014】

[Chemical 1]

<img file="JPH10259320A_D0001.tif" />【0015】

Glasses to which the coating film of the present invention can be applied include fluorescent lamps, indoor environment purification (contamination substance decomposition) glass such as windows, water purification glass such as water tanks and living cages, anti-fog glass for cars, CRT, LCD screens, windows, etc. There are antifouling glass for mirrors, eyeglasses, etc., antifouling for cameras and optical equipment, antifouling lenses, etc.

【0016】

Plastics to which the coating film of the present invention can be applied include AV equipment, computers, mice, keyboards, remote controls, floppy disks and other equipment and their peripheral products, car interiors, furniture, kitchens, etc. There are antifouling, antibacterial, antifungal plastics, etc. used for household items used in baths, washrooms, etc.

【0017】

Examples of the metal to which the coating film of the present invention is applied include antifouling, antibacterial, antifungal stainless steel, antifouling, and antibacterial treated doorknobs used for workbenches such as clothes drying tables, clothes drying rods, kitchens, laboratories, and ventilation fans. There is.

【0018】

Applications of wood to which the coating film of the present invention can be applied include antifouling furniture, antibacterial amusement facilities in parks, and the like. Building materials to which the coating film of the present invention can be applied include antifouling treated outer wall materials, roofs, flooring materials, inner wall materials having indoor environmental purification (pollutant decomposition) properties, and various interiors with antifouling, antibacterial, and antifungal treatments. There are goods etc. The paper to which the coating film of the present invention is applied can be used for antibacterial-treated stationery and the like.

【0019】

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

【0020】

As described above, the various base materials coated with the coating film of the present invention have antifouling, environmental purification, antibacterial, and antifungal effects, and therefore, conditions under which ultraviolet rays (including sunlight and fluorescent lamps) can be irradiated. If so, it can be used for many purposes other than those illustrated.

【0021】

Implementation of the Invention BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described. First, a predetermined amount of composite oxide fine powder having a predetermined average primary particle size is prepared, and this is mixed with an appropriate amount of an organic solvent, β-diketone, and a liquid consisting of a titanate-based or aluminate-based coupling agent. For example, a predetermined amount of zirconia beads was uniformly dispersed with a paint shaker for a predetermined time. Then, it was uniformly mixed with an appropriate amount of a predetermined concentration silica sol solution to produce the coating material of the present invention. Using this paint, for example, it was applied to a predetermined substrate with a spin coater and dried at a predetermined temperature for a predetermined time to prepare a coating film of a photocatalyst.

【0022】

Hereinafter, as described above, the reason for limiting the numerical values will be described. (a) Average primary particle size of composite oxide This value has the effect of adjusting the dispersibility of the fine powder and the filling property in the coating film, but if the value is less than 0.01 μm, high dispersibility cannot be obtained and it becomes difficult to apply thinly and uniformly. If the value exceeds 0.1 μm, the filling property of the fine powder tends to deteriorate and the adhesion between the fine powder particles due to the dense packing and the adhesion to the substrate tends to decrease, so the value was set to 0.01 μm to 0.1 μm. ..

【0023】

(b) Content of composite oxide This value acts to add catalytic activity to the coating film, but if the value is less than 0.5% by weight, sufficient catalytic activity cannot be obtained, while if the value exceeds 20% by weight, the dispersibility becomes dispersible. The value is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, because the value is lowered and the haze of the coating film is deteriorated.

【0024】

(c) Silicon or iron dope amount This value has the effect of improving the photocatalytic activity inherent in titanium oxide, but if the amount of dope is less than 0.1% by weight with respect to titanium oxide, the catalytic activity due to the addition effect of silicon or iron is sufficient. No improvement is obtained. On the other hand, if the value is more than 20% by weight, the characteristics of titanium oxide are diminished and the characteristics of the dope metal as an oxide are exhibited, and the photocatalytic activity that titanium oxide should originally have is weakened. Therefore, a sufficient photocatalytic activity effect cannot be obtained. Therefore, the dope amount is preferably 0.1 to 20% by weight, more preferably 1 to 15% by weight.

【0025】

(d) Amount of β-diketone added This value has the effect of improving the dispersibility of the composite oxide fine powder and increasing the adhesion between the powders and between the powder and the substrate, but it is sufficient if the value is less than 0.5% by weight with respect to the composite oxide. Dispersibility cannot be obtained, and the effect of improving adhesion is not observed. On the other hand, if the value exceeds 10.0% by weight, further improvement in dispersibility and adhesion is not observed. Therefore, the value is preferably 0.5 to 10.0% by weight, more preferably 2 to 8% by weight.

【0026】

(e) Amount of titanate-based and aluminate-based coupling agents added This value has the effect of lowering haze, but if the value is less than 0.1% by weight with respect to the composite oxide, the effect of lowering haze cannot be obtained, while if the value exceeds 10.0% by weight, the effect of lowering haze cannot be obtained. The value is preferably 0.1 to 10.0% by weight, more preferably 0.5 to 5.0% by weight, because improvement in the action of lowering haze cannot be expected.

【0027】

[Example]

Hereinafter, examples of the present invention will be specifically described. Composite oxide fine particles having an average primary particle size as shown in Table 1 are mixed with an organic solvent, β-diketone, and a titanate-based or aluminate-based coupling agent in the same composition as shown in Table 1. The mixture was mixed and dispersed in a paint shaker for 16 hours using 100 g of zirconia beads. Then, it was mixed with a 10% by weight silica sol solution to prepare the photocatalytic paints 1 to 11 of the present invention (hereinafter, simply referred to as the paints 1 to 11 of the present invention). Each of these paints was applied to a glass substrate with a spin coater and dried at 150 ° C. for 1 hour to prepare coating films 1 to 11 of the present invention. In order to evaluate each coating film, the haze (Haze Computer HGM-3D manufactured by Suga Test Instruments Co., Ltd.) and photocatalytic activity of each coating film were evaluated. For photocatalytic activity, a glass plate coated with a photocatalytic film was placed in a 1-liter Pyrex container, sealed, 2 μl of acetaldehyde was introduced, and the acetaldehyde concentration after light irradiation for 2 hours with an ultraviolet lamp was measured with a gastech detector tube. .. The removal rate (%) = {(initial concentration)-(concentration after light irradiation)} ÷ (initial concentration) × 100, and the measurement results are shown in Table 2.

【0028】

[table 1]

<img file="JPH10259320A_D0002.tif" />【0029】

[Table 2]

<img file="JPH10259320A_D0003.tif" />Then, for comparison, paints having a composition composition in which any of the paint components of the present invention as shown in Table 1 was missing or contained less than the specified amount were prepared as comparative paints 1 to 4. Then, comparative coating films 1 to 4 were formed in the same manner as in the above Examples, and the haze and photocatalytic activity of these coating films were measured and shown in Table 2.

【0030】

[Effect of the invention]

As is clear from Table 2, the coating films 1 to 11 of the present invention have a lower haze value, a higher acetaldehyde removal rate, and an excellent coating film having high catalytic activity and high transparency as compared with the comparative coating films 1 to 4. Is. Such an excellent coating film was obtained by using a composite oxide, which is a photocatalyst, in a liquid consisting of an organic solvent, β-diketone, titanate-based or aluminate-based coupling agent, and silica sol. This is because a paint that is uniformly dispersed to a state close to particles can be obtained, and this paint can be applied thinly and evenly, and the smoothing accuracy of the surface is further improved. Furthermore, the bond strength between the fine particles and between the fine particles and the substrate is increased, and the adhesion is improved, so that the durability as a coating film is also improved, which further expands the use of the photocatalyst.