JP3346278B2 - Method of forming photocatalytic film on organic base material and its use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method for forming a photocatalytic film on a surface of an organic base material without causing deterioration (chalking) of the base material, and an organic system having such a photocatalytic film. Regarding the substrate.

[0002]

2. Description of the Related Art It has been known that titanium oxide functions as a photocatalyst and, when irradiated with light, causes decomposition and oxidation of substances. Utilizing the photocatalytic action of this titanium oxide, trace amounts of harmful components present in the indoor or outdoor space for the purpose of environmental purification (eg, deodorization, antifouling, antibacterial, antifungal, etc.)
In particular, attempts have been made to remove harmful components of organic substances including microorganisms. For example, formation of a titanium oxide photocatalytic film on an inorganic base material such as glass, tile, and building material to decompose organic substances attached to or in contact with the base material has been widely used.

[0003] The photocatalyst film is formed by a method of forming a photocatalyst film composed of only titanium oxide, such as a sol-gel method or sintering of titanium oxide powder, or by applying a photocatalytic paint made of titanium oxide powder and heating and drying. The method is roughly divided into a method of forming a photocatalytic film in which titanium oxide is bound by a binder. Since the former method generally requires firing at 400 ° C. or higher, the applicable substrate is substantially limited to an inorganic substrate having excellent heat resistance.

[0004]

There is an increasing demand for forming a photocatalyst film not only on conventional inorganic base materials but also on organic base materials such as plastics, films and woods to provide a function of removing harmful components. ing. However, since the photocatalyst decomposes organic substances by ultraviolet irradiation, when a photocatalyst film is formed on an organic base material, the photocatalyst film deteriorates the base material itself. There is a problem that the phenomenon occurs.

As means for preventing the deterioration of the organic base material due to the choking, an intermediate layer serving as a protective layer and an adhesive layer is interposed between the organic base material and the photocatalytic film (titanium oxide layer). Was attempted. However, practically sufficient adhesion and transparency have not yet been obtained.

An object of the present invention is to provide a photocatalytic film having sufficient adhesion and transparency for practical use, good photocatalytic activity and film strength, without causing a choking phenomenon on the surface of an organic base material. It is an object of the present invention to provide a method for forming and an organic base material on which such a photocatalytic film is formed.

[0007]

Means for Solving the Problems The present inventors have intensively studied to improve the adhesion and transparency of a photocatalytic film while preventing chalking. Quality underlayer is formed, and a photocatalyst paint containing ultrafine titanium oxide, β-diketone, a coupling agent and an alkoxysilane hydrolyzate is applied thereon to form a photocatalyst film. The present inventors have found that no chalking occurs and that the formed coating film has extremely high adhesion and transparency, and the present invention has been accomplished.

The present invention has been completed on the basis of the above-mentioned findings, and is described as follows. "A hydrolyzate obtained by at least partially hydrolyzing an alkoxysilane oligomer is contained in an organic solvent on the surface of an organic base material. Base coat containing a hydrolyzate obtained by at least partially hydrolyzing alkoxysilane and a fluorine-containing surfactant having a perfluoroalkyl group in an organic solvent, and drying the base coat by drying and drying. A formation layer is formed thereon, and a hydrolyzate obtained by at least partially hydrolyzing ultrafine titanium oxide having an average primary particle diameter of 0.1 μm or less, β-diketone, a coupling agent, and alkoxysilane is contained in an organic solvent. Forming a photocatalyst film on the surface of an organic base material, comprising forming a photocatalyst film by applying and drying a photocatalyst paint that has been applied. "

In a preferred embodiment, the photocatalytic paint contains a titanium oxide dispersion obtained by dispersing the titanium oxide in an organic solvent containing a β-diketone and a coupling agent, and a hydrolyzate of the alkoxysilane. An alkoxysilane in the photocatalyst paint is an alkoxysilane oligomer; an oligomer of the alkoxysilane is a 2- to 100-mer; a photocatalyst paint a There contain a fluorine-based surfactant having a perfluoroalkyl group, 0.1~15.0wt% amount of fluorine surfactant is against SiO ₂ equivalent amount of hydrolyzate of alkoxysilane in the coating material The ultrafine titanium oxide in the photocatalyst is of the anatase type; and the amount of β-diketone in the photocatalytic paint is
The coupling agent in the photocatalytic paint is selected from titanate-based coupling agents and aluminum-based coupling agents, and the amount of the coupling agent in the photocatalytic paint is 0.1 to 10% based on titanium oxide. 5 wt%, the content of titanium oxide in the photocatalytic paint is 0.5 to 20 wt%, and the weight ratio of titanium oxide in the photocatalytic paint / silica equivalent of alkoxysilane hydrolyzate is 30 / 70- The photocatalytic film is formed by drying at 170 ° C. or less and has a pencil hardness of 3H or more. The haze of the formed photocatalytic film is 0.1 to 1.0%.

According to the above method, a photocatalyst in which a siliceous underlayer and an ultrafine titanium oxide having an average primary particle diameter of 0.1 μm or less are bonded on the surface thereof with a siliceous binder containing β-diketone and a coupling agent. An organic substrate having a film is obtained. Preferably, the photocatalytic film has a pencil hardness of 3H or more and a haze of 0.1 to 1.0%.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the method of the present invention, first, an undercoat is applied to the surface of an organic base material to form a siliceous underlayer, and a photocatalytic paint containing ultrafine titanium oxide thereon. Is applied to form a photocatalytic film. That is, a photocatalytic film is formed on an organic base material via an underlayer. Hereinafter, the base paint, the photocatalytic paint, and the film forming method will be described in order.

[0012] base paint undercoat paint become a hydrolyzate that is at least partially hydrolyze the alkoxysilane from a solution containing in an organic solvent, or the alkoxysilane is the alkoxysilane oligomer (low-order polymer) And / or the base coating material further comprises a fluorosurfactant having a perfluoroalkyl group in addition to the hydrolyzate of alkoxysilane.

The alkoxysilane is converted into a polymer by a siloxane bond represented by -Si-O- through hydrolysis and polycondensation, and finally forms a siliceous film when organic substances are completely removed. At this time, if the alkoxysilane is an oligomer and / or a fluorosurfactant having a perfluoroalkyl group is present, the wettability to the organic base material is significantly improved, and the adhesion to the organic base material is improved. An excellent underlayer can be formed. Further, the formed silica-based underlayer improves the transparency in addition to the adhesion. If these conditions are not satisfied, the adhesion of the underlayer to the organic base material becomes insufficient, so that the photocatalyst film cannot function as an underlayer, and the transparency of the film is also impaired.

As the alkoxysilane to be hydrolyzed, ethyl silicate (= tetraethoxysilane)
Are commonly used, but are not limited to other alkoxysilanes (e.g., methyl silicate,
Isopropyl silicate, butyl silicate, etc.) can also be used. As described above, the alkoxysilane to be hydrolyzed may be an oligomer.

The alkoxysilane oligomer can be obtained by hydrolyzing the alkoxysilane in an organic solvent under controlled reaction conditions. This hydrolysis can be carried out with or without the use of an acid catalyst. At this time, whether or not an acid catalyst is used, the amount used, and the amount of water for hydrolysis present in the reaction system The degree of polymerization is controlled by adjusting the reaction conditions such as reaction temperature and reaction time to obtain an alkoxysilane oligomer. The organic solvent and the acid catalyst may be the same as those described later. This oligomer of alkoxysilane is generally not crosslinked, and an alkoxy group remains at the terminal of the molecule. Ethyl silicate, that is, an oligomer of tetraethoxysilane, is commercially available.

When an alkoxysilane oligomer is used as a raw material for hydrolysis of a base coating material, the oligomer is preferably an average of 2 to 100-mers (oligomer containing 2 to 100 Si atoms). When the oligomer has a higher molecular weight than the monomer, it becomes difficult to improve the wettability and adhesion with the organic base material. More preferably, the oligomer is a 3- to 50-mer, particularly preferably a 4- to 35-mer.

The base paint can be prepared by heating a solution containing an alkoxysilane or an oligomer thereof in an organic solvent to at least partially hydrolyze the alkoxysilane or the oligomer thereof. This hydrolysis is preferably performed in a water-containing organic solvent while heating and stirring. The reaction temperature is preferably 30-60 ° C
And more preferably 35 to 55 ° C. Reaction time is 2
About 5 hours is preferable. It is preferable to hydrolyze under such relatively mild conditions to obtain a hydrolyzate in which an alkoxy group still remains considerably.

When the alkoxysilane is not an oligomer, a fluorine-based surfactant is added to a solution of the hydrolyzate of the alkoxysilane obtained by hydrolysis. of course,
Even when the alkoxysilane is an oligomer, a fluorine-based surfactant may be added after hydrolyzing the solution.

The fluorine-based surfactant means a surfactant containing a perfluoroalkyl group. Preferred fluorinated surfactants are nonionic surfactants containing a perfluoroalkylsulfonamide group. A typical example is a compound represented by the following formula.

The amount of the C ₈ F ₁₇ SO ₂ N (C ₃ H ₇ ) (C ₂ H ₄ O) ₁₀ -H fluorine-based surfactant added is calculated based on the SiO ₂ equivalent of the hydrolyzate of alkoxysilane in the base coating material. 0.1-15.0 for quantity
It is preferably within the range of wt%. If the amount is less than 0.1 wt% or more than 15.0 wt%, the effect of improving adhesion is reduced. A more preferred addition amount is 1.0 to 5.0 wt%.

As the organic solvent, alcohols such as methanol, ethanol, isopropanol and butanol;
Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; and hydrocarbons such as toluene, xylene, hexane and cyclohexane. These are 1
Species can be used alone or in combination of two or more. Particularly preferred solvents are alcohols. Alcohol solvents also include ether group-containing alcohols such as methoxyethanol and methoxypropanol, and these ether group-containing alcohols may be used by mixing with normal alcohols.

As the acid catalyst for hydrolysis, inorganic acids such as sulfuric acid, nitric acid and hydrochloric acid are preferable, but strong organic acids such as paratoluenesulfonic acid can also be used.

The base coating material used in the present invention is obtained by converting a hydrolyzate of an alkoxysilane or an oligomer thereof to 5% in terms of SiO _2.
~ 20wt%, organic solvent 90 ~ 65wt%, acid 0.05 ~ 0.5wt
%, 4.95 to 14.5 wt% of water, and optionally SiO ₂
It is preferable to contain 0.1 to 15.0% by weight of a fluorine-based surfactant.

Photocatalytic paint The photocatalytic paint used for forming the photocatalytic film contains ultrafine titanium oxide, β-diketone, a coupling agent, and a hydrolyzate of alkoxysilane in an organic solvent. However, since the photocatalytic paint is easily gelled when left, it is preferable to separate the hydrolyzate of alkoxysilane from other components when storing. That is, (A) a titanium oxide dispersion in which ultrafine titanium oxide is dispersed in an organic solvent containing a β-diketone and a coupling agent, and (B) a solution containing a hydrolyzate of alkoxysilane in an organic solvent. ,
It is preferable to prepare a photocatalytic paint by mixing the two liquids before use.

Ultrafine particles having an average primary particle diameter of 0.1 μm or less are used as the titanium oxide of the photocatalyst. With titanium oxide having an average primary particle size of more than 0.1 μm, particularly when the content of titanium oxide in the photocatalytic film is relatively low,
The photocatalytic activity becomes insufficient. Further, as pointed out in the prior art, the coating film becomes cloudy and the transparency is significantly reduced. The average primary particle diameter of the titanium oxide is preferably 0.01 to
It is 0.1 μm, more preferably 0.01 to 0.05 μm.

The method for producing the ultrafine titanium oxide is not particularly limited. Ultrafine titanium oxide is commercially available as a product manufactured by a gas phase method by thermal oxidative decomposition of titanium tetrachloride gas (eg, P-25 manufactured by Nippon Aerosil Co., Ltd.), and can be used as it is. However, ultrafine titanium oxide having the above average primary particle diameter can be produced by the sulfuric acid method which is a liquid phase method, and ultrafine titanium oxide produced by the liquid phase method can also be used. When used as a pigment, titanium oxide is shipped after being subjected to a surface treatment of coating alumina or silicon oxide on the particle surface to reduce its photocatalytic activity, but is used as a photocatalyst in the present invention. Therefore, such surface treatment of titanium oxide is not required.

Titanium oxide used industrially includes two types of crystal forms, anatase type and rutile type. Any of them can be used, but the anatase type is preferred because of its higher photocatalytic activity. If the average primary particle diameter is fine as described above, titanium oxide can form a sufficiently high-activity photocatalyst film by forming a film with the coating material of the present invention. Need not be doped.
However, ultrafine titanium oxide doped with one or more elements may be used to improve the photocatalytic activity. As such a doping element, potassium, phosphorus, potassium + aluminum or phosphorus is known as described above. Also, silicon and iron can be used as the doping element.

The organic solvent used for the photocatalytic coating material is not particularly limited, but the organic solvent exemplified above can be used since the binder is a hydrolyzate of alkoxysilane similarly to the base coating material. Also in the case of the photocatalytic paint, preferred solvents are alcohols including alkoxy alcohol.

The β-diketone and the coupling agent improve the dispersibility of the ultrafine titanium oxide in the organic solvent, thereby improving the preservability of the paint and increasing the transparency of the obtained coating film (haze is reduced). To reduce). These may be added in advance to the solvent before the ultrafine particle titanium oxide is dispersed, or may be added simultaneously when the titanium oxide is dispersed in the solvent. Since these are one kind of dispersing aid, it is not impossible, but not preferable, to add them after the dispersion of titanium oxide.

Examples of β-diketones are 2,4-pentanedione (= acetylacetone), 3-methyl-2,4-
Pentanedione, 3-isopropyl-2,4-pentanedione, 2,2-dimethyl-3,5-hexanedione, 2,2,
6,6-tetramethyl-3,5-heptanedione (= dipivaloylmethane) and the like, and one or more kinds can be used.

If the amount of β-diketone is less than 0.5 wt% with respect to titanium oxide, sufficient dispersibility cannot be obtained.
If it exceeds 0.0% by weight, it does not lead to further improvement in dispersibility. Therefore, the amount is preferably in the range of 0.5 to 10.0% by weight. A more preferred addition amount is 0.5 to 5.0 wt%.

As the coupling agent, the most common silane coupling agent can be used, but a titanate-based or aluminum-based coupling agent is preferably used. Examples of suitable coupling agents for use in the present invention include aluminate-based coupling agents having an acetoalkoxy group, and titanate-based coupling agents having a dialkyl pyrophosphate or dialkyl phosphite group.

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

[0034]

Embedded image

When the amount of the coupling agent is less than 0.1 wt% with respect to titanium oxide, the effects of dispersibility and haze reduction cannot be obtained. On the other hand, when the amount exceeds 5.0 wt%, further effects cannot be obtained. It is preferably in the range of 0.1 to 5.0 wt%.
A more preferred addition amount is 0.1 to 2.5 wt%.

As the binder, a hydrolyzate obtained by at least partially hydrolyzing alkoxysilane is used as in the case of the base paint. This hydrolysis can be performed in the same manner as described for the base paint. The alkoxysilane used as a binder for the photocatalyst paint may be an oligomer of alkoxysilane, but is not necessarily required because the underlayer is formed. When an oligomer of alkoxysilane is used, the degree of polymerization of the oligomer may be the same as that of the base paint.

The photocatalytic paint may also contain a fluorine-based surfactant. In this case, if the photocatalytic coating is a two-pack type, the fluorine-based surfactant is added to the solution of the hydrolyzate of alkoxysilane. The type and amount of the fluorine-based surfactant may be the same as those described for the base paint.

When an alkoxysilane oligomer is used in the preparation of the photocatalytic coating or the photocatalytic coating contains a fluorine-containing surfactant, the titanium oxide particles are more strongly bonded to the binder, and the dispersibility thereof is increased, so that the film is increased. Because it will be evenly distributed inside, even if the binder amount is reduced,
It is possible to form a photocatalytic film having high film strength and photocatalytic activity and excellent transparency.

The content of titanium oxide in the photocatalytic paint (the paint after mixing two liquids in the case of a two-pack type) used in the present invention is preferably in the range of 0.5 to 20% by weight. If the content of titanium oxide is less than 0.5 wt%, the film thickness at the time of film formation will be thin, and if it is desired to increase the film thickness, it must be repeatedly applied several times, which is troublesome. If the content of titanium oxide exceeds 20% by weight, the dispersibility of titanium oxide tends to decrease. A more preferred content of titanium oxide is 3.0 to 17% by weight.

As for the ratio of the titanium oxide as the photocatalyst and the binder, the weight ratio of the amount of titanium oxide to the amount of silica of the alkoxysilane hydrolyzate is preferably in the range of 30/70 to 95/5. If the weight ratio is less than 30/70, the proportion of titanium oxide will be insufficient and the photocatalytic activity will be insufficient. If it exceeds 95/5, the amount of binder will be insufficient and the film strength will be insufficient.

Film-forming method First, a base paint is applied to the surface of the organic base material, and the coating film is dried to form a siliceous base layer on the base material surface. Next, a photocatalyst paint is applied on the underlayer, and the coating film is dried to form a photocatalyst film. Thus, on the surface of the organic base material, a siliceous underlayer and an average primary particle diameter of 0.1 μm
The following ultrafine titanium oxide can form a photocatalytic film in which β-diketone and a siliceous binder containing a coupling agent are combined.

The method of applying the base paint and the photocatalytic paint can be appropriately selected according to the type and shape of the base material. The application can be performed by, for example, a method such as spin coating, roll coating, spray coating, bar coating, and dipping.

The coating film can be dried at room temperature, but it is preferable to heat it to shorten the drying time. The drying temperature is preferably 50 ° C. or more and 170 ° C. or less and not more than the heat-resistant temperature of the substrate, and the heating time is several minutes to several hours, depending on the temperature. Even at such relatively low drying temperatures,
A film strength with a pencil hardness of 3H or more can be obtained. It is not necessary to dry the coating film of the undercoating material until the coating film is completely cured, and it is sufficient that the drying is performed to such an extent that the organic solvent is substantially removed.

The silica base layer has a wettability with respect to an organic base material because the base coating contains a hydrolyzate of an oligomer of alkoxysilane and / or a fluorine-based surfactant. And has good adhesion to the substrate. Therefore, the photocatalyst film formed thereon also has improved adhesion to the substrate, and at the same time, improved transparency. In order to obtain this effect sufficiently, the thickness of the underlayer must be set to 0.
The thickness is preferably 1 μm or more. The upper limit of the thickness of the underlayer is not particularly limited, but is preferably 1.0 μm or less from the viewpoint of economy.

The photocatalytic film formed on the underlayer has good dispersibility of titanium oxide because the binder of the photocatalytic paint is derived from alkoxysilane and the paint contains β-diketone and a coupling agent. And titanium oxide is firmly bound. Therefore, it shows the excellent photocatalytic activity possessed by ultrafine titanium oxide, has high hardness, is hardly damaged, and has excellent durability. Due to this excellent durability and the improved adhesion provided by the underlayer, the photocatalytic film can exhibit its photocatalytic activity over a long period of time.

Further, since the photocatalytic film has excellent transparency, the transparency or appearance of the substrate is not impaired. The thickness of the photocatalytic film is not particularly limited, but will usually be in the range of 0.1 to 1 μm.

The material of the organic base material on which the photocatalytic film is formed on the surface according to the present invention is not particularly limited. For example, synthetic and natural resin films and molded articles, synthetic and natural fibers, wood, paper, coating materials, leather and the like are exemplified.

The photocatalytic film formed by the method according to the present invention exerts a catalytic action when irradiated with light, particularly light containing ultraviolet light, and can decompose organic substances attached or contacted to the film. In addition, oxidizable inorganic substances can be rendered harmless by oxidation (eg, oxidation of NO _x and SO _x ).
.

If the substrate is transparent, light is irradiated on the back side of the substrate.
(From the side where the photocatalytic film is not formed). Therefore, for example, if a photocatalytic film is formed on the indoor side surface of a window glass, the photocatalytic action is exerted by sunlight during the daytime and indoor illumination light at nighttime, and harmful organic substances in the room (e.g., building materials) Aldehydes, tobacco tar, oils from cooking, microorganisms such as bacteria and mold)
Can be decomposed.

Specific examples of the substrate suitable for forming the photocatalyst film of the present invention include covers of various lightings (eg, car lightings, tunnel lightings, fluorescent lights, white light bulbs, etc.), lenses, dishes and cooking. Containers (e.g., balls, colanders, storage containers), ventilation fans, eyeglass lenses and frames, goggles, helmet shields, signs, signs, home appliance housings, range hoods, sinks (e.g., polyvinyl chloride), kitchen counters (e.g., (Artificial marble), sanitary ware and accessories
(Eg, pedestal and lid of a Western style toilet), bathtub (eg, made of FRP),
Furniture (eg, melamine resin table boards, plastic chairs), indoor or outdoor exhibits and displays (eg, information boards)
, Outdoor furniture (eg, benches) and playground equipment, outdoor fixed structures
(E.g., noise barriers on expressways), building materials (corrugated sheets, acrylic boards)
And plastic films and sheets (including shade sheets), greenhouses, wooden or other plant-based building materials, interior materials and building accessories (doors, shoji, sliding doors, screen doors, sudare, tatami mats) etc)
, Wall spray, natural and synthetic fibers and fabrics,
Examples include paper and leather products.

However, the organic base material is not limited to this. These substrates can form the photocatalytic film of the present invention either in the state of the raw material before commercialization or after commercialization. Even if the base material is an inorganic material such as a metal, the method of the present invention is preferably applied when an organic paint is applied for anticorrosion or beauty. In this case, if the formation of the underlayer is omitted, the coating film on the substrate surface is deteriorated by the photocatalytic film.

For example, in a tunnel, a photocatalytic film is formed on a tunnel illumination light cover according to the method of the present invention, and preferably, the surface of an inorganic base material such as a tile for interior of a tunnel or a metal plate is further applied to the surface. direct coating or a photocatalytic coating used in the process, or to form a photocatalytic film according to the method of the present invention when the coated metal plate, it is possible to decompose NO _x and sO _x in addition to the organic components in the exhaust gas Helps to purify the air in the tunnel. Other substrates can also decompose the surrounding organic matter, and are effective in cleaning the environment and also in the antibacterial and antifungal properties of the substrate.

[0053]

EXAMPLE A mixture of an ethyl silicate oligomer or monomer, an organic solvent, an acid and water in the amounts shown in Table 1 was reacted with stirring at the reaction temperature and time shown in Table 1 to obtain ethyl silicate. The oligomer or monomer was partially hydrolyzed. The solutions obtained by this hydrolysis were used as base coats A to C, respectively.

Further, to the solution obtained by partially hydrolyzing the oligomer or monomer of ethyl silicate obtained above, a fluorine-based surfactant was added in an amount shown in Table 1 and mixed to contain the fluorine-based surfactant. Undercoat paints FA to FC were obtained.

Of the above base coatings A to C and FA to FC, only base coating C in which alkoxysilane is a monomer and does not contain a fluorosurfactant is a base coating for comparison, and the rest are base coatings for the present invention. 1 is a base coating according to the invention.

[0056]

[Table 1]

The materials used in Table 1 are as follows: Ethyl silicate: ES40 = oligomer with a degree of polymerization of about 4 (pentamer) ES45 = oligomer with a degree of polymerization of about 31 (32-mer) ES28 = monomer (Monomer) Solvent: ethanol Acid: 60% nitric acid Surfactant: Fluorine-based nonionic interface represented by [C ₈ F ₁₇ SO ₂ N (C ₃ H ₇ ) (C ₂ H ₄ O) ₁₀ -H] Surfactant (for fluorosurfactants
wt% is a value based on the amount of ethyl silicate in terms of SiO ₂ ).

On the other hand, the kinds and amounts of organic solvent, β-diketone, coupling agent, and photocatalyst powder (P-25 manufactured by Nippon Aerosil Co., Ltd. Fine particle titanium oxide, average primary particle diameter 0.02
μm) and dispersed in a paint shaker using 100 g of zirconia beads for 16 hours to obtain a titanium oxide dispersion.

In this titanium oxide dispersion, any of the binder solutions selected from the base coating materials A to C prepared above (that is, the alkoxysilane is an oligomer or a monomer and does not contain a fluorine-based surfactant) ) In the amounts shown in Table 2, or any of the binder solutions selected from the base paints FA to FC prepared above (that is, the alkoxysilane is an oligomer or monomer and contains a fluorine-based surfactant). Was mixed in the amounts shown in Table 3 to prepare photocatalytic coatings. In Table 2,3, TiO ₂ / SiO ₂ weight ratio, photocatalytic powder the amount relative to the amount as calculated as SiO ₂ amount of ethyl silicate hydrolyzate of the binder solution (TiO ₂₎
Is the weight ratio.

One of the primers selected from Table 1 (described in Tables 2 and 3) was applied to one side of a PET film having a thickness of 0.1 mm with a bar coater (No. 8), and dried at 80 ° C. for 1 hour. do it,
A siliceous underlayer having a thickness of about 0.5 μm was formed. The photocatalyst paints shown in Tables 2 and 3 were applied on the underlayer with a bar coater (No. 8), and dried at 120 ° C. for 1 hour.
A 0.5 μm photocatalytic film was formed.

The haze of the formed photocatalytic film (Haze Computer HGM-3D manufactured by Suga Test Instruments) was measured. The adhesion of the photocatalyst film was evaluated by the number of peeled cells by a cross cut / tape peel test (100 cells). In addition, a UV lamp (1.2 mW / c
m ² ) was continuously irradiated for one week, and the presence or absence of choking after this light irradiation was visually judged according to the following criteria.

：: no choking, Δ: partial choking, ×: choking all over.

Separately, a PET film having a photocatalytic film
A 10 × 10 cm test piece was placed in a 1-liter Pyrex container with the coated side up, the container was sealed, acetaldehyde was injected in a predetermined amount (350 ppm), and a 10 cm UV lamp installed at a distance (1.2 mW / cm ² )
The photocatalytic activity was evaluated by measuring the acetaldehyde concentration after light irradiation for 2 hours with a gas tech detector tube and calculating the acetaldehyde removal rate by the following equation.

Removal rate (%) = [(initial density-density after light irradiation) / initial density] × 100 The test results above are also shown in Tables 2 and 3. In addition, Table 2 shows the case where the base coating material is obtained by hydrolyzing an oligomer of alkoxysilane and does not contain a fluorine-based surfactant, and Table 3 shows the case where the base coating material contains a fluorine-based surfactant. .

[0065]

[Table 2]

[0066]

[Table 3]

As can be seen from Tables 2 and 3, the photocatalytic film formed according to the present invention had a good haze of 1% or less, good transparency, and a high photocatalytic activity of 60% or more. Furthermore, since the photocatalytic film was formed on the underlayer having excellent adhesion to the organic base material, the film was excellent in adhesion, and the choking of the base material could be completely prevented even when irradiated with light.

Further, when the binder solution of the photocatalytic paint is a solution having high adhesion to the organic base material used for the base paint in the present invention (ie, base paints AB and FA-FC), the titanium oxide particles Bonding strength increases, and the content of SiO ₂ as binder becomes 70 wt% based on the total amount with titanium oxide.
(In other words, the proportion of titanium oxide as a photocatalyst is reduced to 30 wt%), a photocatalyst film having high photocatalytic activity can be formed, and the SiO ₂ content of the binder is reduced to 5 wt%. Good adhesiveness was obtained even when reduced to a low level.

On the other hand, in the comparative example (using base coating C) in which the base coating was obtained by hydrolyzing an alkoxysilane monomer and did not contain a fluorine-based surfactant, the photocatalytic coating was used. For example, even when a fluorine-based surfactant was contained, the transparency and adhesion of the photocatalyst film were greatly reduced. Furthermore, since the adhesion of the underlayer was poor, the substrate was not sufficiently protected, and choking could not be prevented despite the provision of the underlayer.

Even when the base coating material according to the present invention is used, if the photocatalytic coating material does not contain β-diketone or a coupling agent, the dispersibility of titanium oxide is reduced, and haze and photocatalytic activity are reduced. Dropped.

In order to demonstrate the effectiveness of the photocatalyst paint of the present invention on various organic base materials, a combination of the base paint and the photocatalyst paint described in Example 3 in Table 2 was used. The base layer and the photocatalyst film were formed on the surface of the substrate with the changes shown in Table 3. The same coating method was used for the base paint and the photocatalytic paint, and the drying conditions of the coating film were the same as above. The base material was cut out to about 10 × 10 cm except for the spectacle lens (made of plastic). The adhesion of the photocatalyst film thus formed was tested in the same manner as above, and if the substrate was transparent, the presence or absence of choking was also tested in the same manner as above. The test results are shown in Table 4 together with the thicknesses of the underlayer and the photocatalyst film.

[0072]

[Table 4]

As can be seen from Table 4, the photocatalytic film, in which choking was prevented, could be formed on various organic base materials with good adhesion according to the method of the present invention even when the base material and the coating method were different. . In addition, it was confirmed that the same results as shown in Table 4 were obtained when the combination of the base paint and the photocatalytic paint described in Example 3 of Table 3 was used.

[0074]

According to the present invention, a photocatalytic film having excellent transparency and durability can be formed with good adhesion to an organic substrate without causing any choking of the substrate. Therefore, conventionally it could not be applied for chalking,
The photocatalytic film can be used for organic base materials such as plastic and wood, and the use of the photocatalytic film is significantly expanded.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-310039 (JP, A) JP-A-9-71437 (JP, A) JP-A-9-24335 (JP, A) JP-A-9-1997 75748 (JP, A) JP-A-5-345877 (JP, A) JP-A-9-52973 (JP, A) JP-A-9-227829 (JP, A) JP-A 8-295775 (JP, A) JP-A-7-98414 (JP, A) JP-A-9-225382 (JP, A) JP-A-7-101408 (JP, A) WO 97/134 (WO, A1) WO 97/45502 (WO , A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 7/24 303 B05D 1/38 B01J 35/02 B01J 37/02 301 B32B 9/00 C09D 5/00, 5/14, 5/16

Claims (19)

(57) [Claims] 1. A silica base layer is formed on a surface of an organic base material by applying and drying a base paint containing a hydrolyzate obtained by at least partially hydrolyzing an alkoxysilane oligomer in an organic solvent. , On which the average primary particle diameter
Form a photocatalytic film by applying and drying a photocatalytic paint containing ultra-fine particles of 0.1 μm or less titanium oxide, β-diketone, coupling agent, and a hydrolyzate obtained by at least partially hydrolyzing alkoxysilane in an organic solvent. Forming a photocatalytic film on the surface of an organic base material. 2. A base coating material comprising a hydrolyzate obtained by at least partially hydrolyzing alkoxysilane and a fluorosurfactant having a perfluoroalkyl group in an organic solvent on the surface of an organic base material. A hydrolyzate obtained by forming a siliceous underlayer by coating and drying, and at least partially hydrolyzing ultrafine titanium oxide having an average primary particle diameter of 0.1 μm or less, β-diketone, a coupling agent, and alkoxysilane on the siliceous underlayer. A method for forming a photocatalyst film on a surface of an organic base material, characterized by forming a photocatalyst film by applying and drying a photocatalyst coating material containing the compound in an organic solvent. 3. A photocatalytic coating material comprising: a titanium oxide dispersion obtained by dispersing the titanium oxide in an organic solvent containing a β-diketone and a coupling agent; and an organic solvent solution containing the alkoxysilane hydrolyzate. The method according to claim 1, wherein the method is prepared by mixing liquids. 4. The method according to claim 1, wherein the alkoxysilane in the photocatalytic coating is an alkoxysilane oligomer. 5. The method according to claim 1, wherein the alkoxysilane oligomer is 2 to 10%.
The method according to claim 1 or 4, which is a 0-mer. 6. The method according to claim 1, wherein the photocatalytic coating contains a fluorosurfactant having a perfluoroalkyl group. 7. The amount of the fluorinated surfactant is 0.1% with respect to the SiO ₂ equivalent of the hydrolyzate of alkoxysilane in the paint.
7. The method according to claim 2, wherein the amount is from 1 to 15.0% by weight. 8. The method according to claim 1, wherein the ultrafine titanium oxide in the photocatalyst is of the anatase type. 9. The photocatalytic paint according to claim 1, wherein the amount of β-diketone is 0.5 to 10.0% by weight based on titanium oxide.
The method according to any one of claims 1 to 4. 10. The method according to claim 1, wherein the coupling agent in the photocatalytic coating is selected from a titanate coupling agent and an aluminum coupling agent. 11. The amount of the coupling agent in the photocatalytic coating is 0.1 to 5.0 wt% based on titanium oxide.
11. The method according to any one of claims 10 to 10. 12. The content of titanium oxide in the photocatalytic paint is
The method according to any one of claims 1 to 11, wherein the amount is 0.5 to 20% by weight. 13. The weight ratio of the amount of titanium oxide in the photocatalytic paint to the amount of silica in the alkoxysilane hydrolyzate in terms of silica is 30/70.
13. The method according to any one of claims 1 to 12, wherein the method is in the range of ~ 95/5. 14. The photocatalyst film is formed by drying at 170 ° C. or less and has a pencil hardness of 3H or more.
14. The method according to any one of 13 above. 15. The haze of the formed photocatalytic film is 0.1 to 1.
15. The method according to any one of claims 1 to 14, which is 0%. 16. A silica-based underlayer on the surface, and ultrafine titanium oxide having an average primary particle diameter of 0.1 μm or less,
An organic substrate having a photocatalytic film bonded with a siliceous binder containing a diketone and a coupling agent. 17. A photocatalyst film having a pencil hardness of 3H or more and 0.1% or less.
17. The organic substrate having the photocatalyst film according to claim 16, which has a haze of about 1.0%. 18. The organic base material may be a synthetic or natural resin film or molded article, synthetic or natural fiber, wood, paper,
18. The organic base material having a photocatalytic film according to claim 16 or 17, which is a material selected from the group consisting of a coating material and leather. 19. The organic base material may be a cover for various kinds of lighting including an automobile and a tunnel, a lens, tableware, a ventilation fan, an eyeglass lens and a frame, a goggle, a mask shield,
Includes signs, signs, home appliances housing, range hoods, sinks, kitchen counters, sanitary fixtures and accessories, bathtubs, furniture, indoor or outdoor exhibits and displays, outdoor furniture and playground equipment, outdoor fixed structures, building materials Various plastic moldings and plastic films and sheets, greenhouses, wooden or other botanical building materials, interior materials and building accessories, wall spraying materials, natural and synthetic fibers and fabrics, paper, leather products, and resin coatings 19. The organic substrate having a photocatalyst film according to claim 18, wherein the organic substrate is selected from the group consisting of inorganic substrates.