JP3461227B2 - Article having a silica film containing titanium dioxide - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an article useful for decomposing, removing and sterilizing various malodorous gases and harmful gases generated in daily life, harmful compounds in water, oils, etc. The present invention relates to an article in which a silica film containing titanium dioxide, which is active and has a high effect of decomposing various organic substances and inorganic substances, is formed on a substrate via a resin layer. The silica film on the surface of the obtained article has adhesiveness,
It is characterized by excellent workability and weather resistance.

[0002]

It is widely known that when titanium dioxide is irradiated with ultraviolet rays, electrons are transferred from the valence band to the conduction band by photoexcitation to become an n-type semiconductor, which exhibits a decomposing and sterilizing effect on various compounds. Decomposition of organic matter in water (“Water and Wastewater”, vol.30 No.10 (1988) p943)
-948), decomposition of organic matter, deodorization, sterilization (“surface” vo
l. 25 No. 8 (1987) p477-495,
"Ceramics" 21 (1986) No. 4, p326
-333) and the like can be used. However, when the photocatalytic activity of titanium dioxide is actually used for the purpose of decomposing and sterilizing harmful gas in exhaust gas, malodorous gas such as cigarettes and toilets, oil content, etc., it is supported on some substrate. , It is necessary to fix.

As a method for supporting titanium dioxide for photocatalyst on a substrate, for example, the following methods have been proposed. (1) Titanium oxide fine powder is adhered to a film-like, bead-like, board-like, fiber-like substrate made of a light-transmitting substance material such as nitrocellulose, glass, polyvinyl chloride, nylon, methacrylic resin, and polypropylene. Method (JP-A-62-66861) (2) A porous glass support is impregnated with an alcohol solution of titanium (IV) tetrabutoxyoxide and heated to
Method of holding and fixing to a porous glass support by using anatase type titanium oxide (Japanese Patent Laid-Open No. 2-5015)
4) (3) Hold the semiconductor catalyst powder by a method such as press-fitting, impregnation, or adhesion in a porous polymer film (for example, polyfluoroethylene resin) having a photosensitizer such as a dye or a metal complex as a side chain. Method of fixing (JP-A-58-125602) (4) Method of supporting titanium oxide on a filtration filter made of polypropylene fiber or ceramics (JP-A-2-68190) (5) In the entanglement of quartz, glass and plastic fibers A method of holding and fixing titanium oxide powder on the both sides and holding both surfaces thereof with light-transmitting glass (US Pat. No. 4,888,810).
1) (6) Platinum is adhered to an alumina substrate by a sputtering method, a mixed dispersion liquid of anatase type titanium oxide powder and an organic solvent solution of methylmethacrylate is applied thereon by a spin coating method, and then bonded. While thermally decomposing methyl methacrylate as a binder,
Method for converting anatase-type titanium oxide into rutile-type titanium oxide (Robert E. Hetric, Appli
ed Physics Communications,
5, (3), 177-187 (1985)) (7) A method of thermally spraying titanium oxide on the surface of a polyester cloth by a low temperature thermal spraying method (Saji Sakurada, Surface Technology Vol. 41, 10
No., P60 (1990))

The above-mentioned known methods for supporting photocatalytic titanium dioxide on a substrate have the following drawbacks.
Fixing with organic substances such as (1), (3), (4), and (5) as a binder causes most of the organic substances to be decomposed by the photocatalytic action of titanium dioxide, so fixing during long-term use is reliable. There is no. In the method (2), since the expensive organic titanium compound is used as the raw material and the glass is directly supported on the glass which is easily broken, the strength is not reliable. Further, the methods (6) and (7) are not preferable because the temperature becomes extremely high during fixing and the high photocatalytic activity of titanium dioxide is lost. In addition, as a method often used, an inorganic porous material, a method of impregnating and supporting a slurry of titanium dioxide on fibers, and a binder obtained by hydrolyzing or melting an alkali salt such as silica-based or alumina-based are used. There is a method to use, but in the former, the titanium dioxide particles are not fixed, so they easily fall off due to vibration and shock, and in the latter, the catalyst surface is coated with a binder for fixing the catalyst and activated. Was lost. Furthermore, since heat resistance and the like are required in these methods, the types of substrates that can be used are also limited, and it is difficult to fix and process them on a wide surface, resulting in high cost, but insufficient utilization of light energy. There was a problem. This problem is common to all photocatalysts other than titanium dioxide, and also to highly active substances such as adsorbents and germicides. It is conventionally known that titanium dioxide decomposes various organic substances and inorganic substances by ultraviolet irradiation and exhibits a bactericidal effect, but when putting it into practical use, it does not reduce the catalytic activity, has excellent strength, and is inexpensive. A fixing method that is easy to handle has been desired.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems, and utilizes the photocatalytic activity of titanium dioxide to produce a malodorous gas such as acetaldehyde or mercaptan, N.
Harmful gases O _X such harmful substances agricultural chemicals, environmental pollutants,
An object of the present invention is to provide an article excellent in processability and weather resistance, which is excellent in decomposition and removal of oil components and sterilization effect.

[0006]

DISCLOSURE OF THE INVENTION As a result of intensive studies to achieve the above object, the present inventors have found that titanium dioxide is dispersed in a mixture of a silicate ester, water and an optional organic solvent. The coating composition is applied to the resin layer formed on the surface of the substrate to form a silica film, the substrate, the resin layer formed on the substrate surface, and the silica film containing titanium dioxide and fixed on the resin layer. The articles possessed are malodorous gases such as aldehydes and mercaptans due to the photocatalytic effect of ultraviolet irradiation,
It has been found that it exhibits excellent effects on oil removal and sterilization, and that it is excellent in adhesion, workability and weather resistance even when applied to non-heat resistant substrates such as aluminum plates and resins. Completed the invention.

That is, the present invention relates to an article having a substrate, a resin layer formed on the surface of the substrate, and a silica film containing titanium dioxide and fixed on the resin layer. The substrate may be of any type as long as it can form a resin layer on its surface, but is preferably aluminum.
A metal material containing at least one selected from the group consisting of iron, nickel and copper as a main component, glass, ceramics,
It is selected from resin, cloth, fiber, or combinations thereof. Any type of resin layer can be used on the surface of the substrate, such as epoxy, acrylic, urethane resin, etc., as long as it has adhesiveness to the substrate and solubility in the paint in which titanium dioxide is dispersed. obtain. Of these, acrylic and epoxy resins are preferable, and epoxy resins are particularly preferable because they have strong adhesion to various substrates. As the epoxy resin, any of bisphenol A type, novolac type and aliphatic type resins can be used. The type of epoxy resin and the type of curing agent can be appropriately selected according to the type of substrate used and required performance. It is also possible to add a pigment to the resin for coloring, or to add an ultraviolet absorber to improve the light resistance. It is sufficient that the thickness of the resin layer is 1 μm or more.

The titanium dioxide for photocatalyst used in the production of the silica film of the present invention is preferably anatase type,
The specific surface area is preferably 20 m ² / g or more, 50 m ² / g
The above is more preferable. Further, the titanium dioxide particle size is preferably 1 μm or less, more preferably 0.1 μm or less for the strength of the coating film. For titanium dioxide, W, S
It is also preferable to contain a metal oxide such as n, S, Mo, V, Mn, and Zn that improves the catalytic activity. Further, a photocatalyst other than titanium dioxide can be similarly fixed, or can be freely colored by adding a colored pigment according to the application. Further, the silica film may contain an antibacterial substance such as silver, copper or zinc or another functional substance. In the article of the present invention, the silica film is fixed to the substrate via the resin layer. The silica layer is divided into blocks of several μm to several tens of μm or more due to contraction of volume due to dehydration of silica sol and evaporation of solvent, so that, for example, a metal plate having a silica film fixed thereon is processed by bending or the silica film is fixed. Even if the cloth is deformed such as folded, the deformation can be absorbed, so that peeling is less likely to occur. As the thickness of the silica film increases, the strength tends to decrease, so the film thickness is 100 μm.
The following is preferable. The proportion of titanium dioxide in the silica film is preferably 10 to 90% by weight, more preferably 20 to 85% by weight, and most preferably 40 to 80% by weight.
Is. A known method can be used as a method for providing the resin layer on the surface of the substrate and a method for providing the silica layer on the resin layer. Depending on the shape of the substrate, coating, spraying,
A suitable coating method such as dipping can be selected.

The present invention further provides a method for producing the above article, wherein a coating material in which titanium dioxide is dispersed in a silicate ester, water and an arbitrary organic solvent is formed on a resin layer formed on the surface of a substrate. Then, a manufacturing method of heat-treating at 400 ° C. or lower is provided. Any known silicate ester can be used, but methyl silicate, ethyl silicate, and butyl silicate are preferable, and ethyl silicate is most preferable.
The organic solvent easily has affinity with the hydrophilic titanium dioxide particles and silica sol produced by hydrolysis of the silicate ester, is miscible with the silicate ester and the alcohol which is the decomposition product thereof, and makes the silica film good for the substrate. It is necessary to be able to dissolve the resin layer for adhesion. Further, if the alcohol produced by the hydrolysis of the silicate has the property of dissolving the resin layer and the amount thereof is sufficient, it is not necessary to add a solvent. The type of solvent can be appropriately selected according to the type of resin layer used, and representative examples thereof include cellosolves, carbitols, and alcohols. Among the cellosolves, those having an alkyl group are preferable, and butyl cellosolve having a butyl group is particularly preferable. Among the carbitols, carbitol and carbitol acetate are preferable.
Among alcohols, ethanol and butanol are preferable.
The water added to the paint is used for the hydrolysis of silicate ester, but the dispersibility of titanium dioxide in the paint,
In order to increase the coating strength, the coating pH is preferably acidic,
A pH of 4 or less is more preferable, and a pH of 2 or less is particularly preferable. As a method for lowering the coating pH, it is preferable to attach sulfate radicals to the surface of the titanium dioxide particles, or to add a small amount of acid to water to lower the coating pH when the titanium dioxide itself is weakly acidic. Acids added to water include hydrochloric acid, sulfuric acid,
Either nitric acid or the like can be used.

The blending ratio of the paint for producing the silica film is 3 parts by weight of ethyl silicate when 100 parts by weight of titanium dioxide is used as ethyl silicate.
0 to 3200 parts by weight, preferably 60 to 1400 parts by weight, more preferably 80 to 520 parts by weight. When methyl silicate or butyl silicate is used as the silicate ester, the preferred amount is the ratio of the respective molecular weights. It is the value obtained by multiplying the corresponding coefficient, 0.73, 1.54, by the value for ethyl silicate. That is, silicate ester is
It can be used in the range of 20 to 5000 parts by weight.
Wear. The solvent is 0 to 1000 parts by weight, preferably 0 to 50
0 parts by weight, and water is 10 to 1100 parts by weight, preferably 20 to 500 parts by weight, and more preferably 30 to 200 parts by weight. When the content of titanium dioxide is less than the above content, the photocatalytic activity of the film becomes low, and when the content is high, the adhesion and strength of the silica film deteriorate, which is not preferable. The heat treatment after coating is preferably performed in a temperature range where oxidation, deterioration and deformation of the resin layer and the substrate do not occur. Generally, it is preferably 400 ° C or lower, but 10
When the temperature is 0 ° C or lower, it takes a long time to gel the silica sol and it is difficult to obtain the film strength. Therefore, 100 to 400 ° C is more preferable.
In addition, the coating film is washed with warm water of 60 ° C. or higher to obtain free silica,
After removing the resin and the like, the catalyst activity is further enhanced by irradiating ultraviolet rays to decompose the resin adhering to the surface of the titanium dioxide particles.

When titanium dioxide is used as a photocatalyst, it is usually carried in a layer on a flat substrate or dispersed on the inner wall of a porous body, but the light reaching the lower part of the layer or the inside of the porous body is usually used. Since the proportion of energy is small and it is preferable to spread the titanium dioxide fine particles thinly and fix them in order to improve efficiency, it is desirable to apply titanium dioxide as a paint to the substrate and fix it as a coating film. In the production method according to the present invention, by adding an organic solvent to the silica sol and alcohol obtained by hydrolyzing a silicate ester, not only the viscosity as a coating material, the dispersibility, and the drying rate are improved, but also the substrate surface. By melting the surface of the resin layer prepared in Example 1 to form a layer in which silica and resin are mixed, the silica layer was successfully fixed on the resin layer. Moreover, since titanium dioxide itself is fixed in the silica film, the effect of not directly contacting the resin is obtained,
The deterioration of the resin due to the photocatalytic effect can be prevented. When forming the silica layer, it is conceivable that the base material is coated with a coating of titanium dioxide and silica sol, in which the resin has been dissolved, and then the base is fixed with the resin. In order to obtain strength, it is necessary to increase the initial amount of resin added, and as a result, the proportion of titanium dioxide and silica in the coating film decreases, resulting in photocatalytic activity,
The film strength is also inferior, which is not preferable.

The article according to the present invention is preferably used as a deodorant. That is, the present invention provides, as one aspect thereof, a deodorant having a substrate, a resin layer formed on the surface of the substrate, and a silica film containing titanium dioxide and fixed on the resin layer. The silica film in the article of the present invention becomes porous by dehydration and evaporation of alcohol from silica sol produced by hydrolysis of silicate ester, and evaporation of organic solvent,
Since the included titanium dioxide particles easily come into contact with the atmosphere gas, the oil content attached to the surface, the bacteria, etc., these can be efficiently decomposed. In addition, NO _x , ammonia,
Inorganic gases such as hydrogen sulfide, agricultural chemicals, decomposition of oil, etc. and sterilization and removal of other fungi, algae, etc. are known as the photocatalytic effect of titanium dioxide, and when a deodorizing effect is obtained, it is known as the photocatalytic effect. It is clear that the other effects that have been obtained can be obtained at the same time. Examples will be given below,
The content of the present invention will be described in more detail, but these examples are merely examples, and the scope of the present invention is not limited thereto.

Example 1 Titanium dioxide (anatase type specific surface area 60 m ² / g
6 g of average particle diameter 0.1 μm), 9 g of ethyl silicate, 3 g of water containing 0.5 mol / l of hydrochloric acid and 6 g of butyl cellosolve together with 90 g of 3 mmφ glass beads 12
It was charged in a 0 ml mayonnaise bottle, dispersed and mixed for 10 minutes with a paint conditioner manufactured by Red Devil Co. to obtain a silica sol-containing paint. Sky Aluminum Co., Ltd. Sky coat (color aluminum plate)
The above paint was applied to a 60 mm × 150 mm × 0.5 mm epoxy resin coated surface with a 2 mil doctor blade. After air-drying for a whole day and night, it was baked at 150 ° C. to form a silica film. The thickness of the coating film is about 20 according to the scanning electron microscope observation.
μm, coating weight per unit area is about 2 mg / cm ²
The weight of titanium dioxide was about 1.5 mg / cm ² . This film was tested for adhesion and hardness of the coating film according to the method of JIS-K5400.
The pencil hardness was 3H or higher. In addition, 1 aluminum base
It was bent at 80 degrees, but the silica film was not peeled off. Although the surface of the coating film is smooth to the touch, the surface of the silica coating film is divided into about 10 μm squares by electron microscope observation shown in FIG. 1, and this is considered to be useful for absorbing the deformation of the substrate.

Cut out the coated surface of 5 cm × 1 cm to 120
Put in a milliliter glass bottle, inject acetaldehyde to the amount of gas concentration in the bottle is 1000ppm,
UV light with a wavelength of 350 nm is 4.0-4.4 m from the outside of the bottle.
After irradiating at 1 W / cm ² for 1 hour, the air in the bottle was filled with gas chromatograph G3800 (detector FI manufactured by Yanagimoto Seisakusho).
When measured in D), the acetaldehyde concentration is 0 pp
It became m. Similarly, 50 ppm of acetic acid became 0 ppm after 1 hour of ultraviolet irradiation. Trimethylamine 10
00 ppm became 0 ppm after 1 hour of ultraviolet irradiation. 1000 ppm of ethyl mercaptan was changed to 60 ppm by ultraviolet irradiation for 1 hour. Dimethyl sulfide 5
0 ppm became 0 ppm by ultraviolet irradiation for 1 hour.
Table 3 shows the removal data of acetaldehyde and ethyl mercaptan by ultraviolet irradiation this time. still,
A glass test tube with 5 cm x 1 cm of the coating film cut out and 20 ml of water was put in it, and the sample was left outdoors for one week. Algae were found to appear in those without the coating film. There was no change in what I put.

Examples 2 to 4 In Example 1, a film was prepared in which the substrate was a Sky Aluminum Co., Ltd. Sky Coat (color aluminum plate) coated surface with polyester, acrylic and vinyl resins. The coating composition is shown in Table 1 and the results are shown in Table 2.

Examples 5 to 23 In Example 1, the type of titanium dioxide, the composition of the paint, and
A film was prepared by changing the type of resin applied to the substrate and the coating method of the paint. The coating compositions are shown in Table 1 and the results are shown in Table 2. In addition, as for Example 6 to 8, similarly to Example 1, data for removing acetaldehyde and ethyl mercaptan by ultraviolet irradiation are shown in Table 3. Examples 24 and 25 A film having a polypropylene cloth as a base and a fiber was prepared. Since the pencil test is unsuitable for these, the test pieces were replaced by 100 times bending and washing in a washing machine, but no weight reduction due to peeling of the film was observed.

Comparative Example 1 A silica film was prepared in the same manner as in Example 1 except that butyl cellosolve was not used. The coating film was peeled off simultaneously with drying. Comparative Example 2 In Example 1, when the acid concentration of water added for the hydrolysis of ethyl silicate was lowered and the coating pH was set to 8,
The catalyst particles aggregated in the paint and the coating film peeled off. Comparative Example 3 In Example 5, when an aluminum plate on which the resin was not applied to the substrate was used, the coating film was peeled off. Also, the aluminum plate was corroded. Comparative Example 4 In Example 1, when the ratio of titanium dioxide, ethyl silicate, water added with 0.5 mol of hydrochloric acid and butyl cellosolve was increased to 6/1/1/6 and the ratio of titanium dioxide was increased, the coating film was Peeled off. Comparative Example 5 In Example 5, when a paint prepared by dissolving 10% of an epoxy resin in advance was applied to an aluminum plate, the coating film was peeled off and the aluminum plate was corroded. Comparative Examples 6 to 8 A paint prepared by dispersing titanium dioxide in acrylic, acrylic-melamine and urethane resins was applied to an aluminum plate. In the case of acrylic and urethane resins, the film had no strength, and the film was pulverized by irradiation with ultraviolet rays for 12 hours. In the case of acrylic-melamine resin, no photocatalytic activity was found in the coating film. Comparative Example 9 Further, 10 parts of the titanium dioxide powder for catalyst used in Example 1 were used.
When the acetaldehyde decomposition test was conducted in the same manner for mg (approximately the same amount as contained in the coating surface of 5 cm × 1 cm), the rate of decrease in concentration was almost the same as in Example 1.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[Brief description of drawings]

FIG. 1 is an electron micrograph (× 1000) of a silica film metallic structure on the surface of an article of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C09D 1/00 C09D 1/00 (72) Inventor Hideki Department Baka 25 Chitan Kogyo Co., Ltd. 72) Inventor Tatsuo Saito Within 25 Chitan Kogyo Co., Ltd., 1978, Ogushi, Ube City, Yamaguchi Prefecture (72) Inventor Toshio Utagawa 6-2 61, Imafuku Nishi, Joto-ku, Osaka City, Osaka Prefecture Matsushita Seiko Co., Ltd. (72 ) Inventor Kenji Kato 6-2 61, Imafuku Nishi, Joto-ku, Osaka City, Osaka Prefecture Matsushita Seiko Co., Ltd. (72) Inventor, Takuya Murayama 6-2 61, Imafuku Nishi, Joto-ku, Osaka City, Osaka Matsushita Seiko Co., Ltd. (56) References JP-A-7-171408 (JP, A) European Patent Application Publication 633064 (EP, A 1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 1/00 -35 / 00 B01J 21/00-37/36 C09D 1/00-201/10 A61L 9/00-9/22

Claims (6)

(57) [Claims] 1. An article having a substrate, a resin layer formed on the substrate surface, and a silica film containing titanium dioxide and fixed on the resin layer , wherein the silica film and the resin are mixed.
Layer is formed, and the silica film is several microns to several tens of microns.
Items divided into blocks. 2. The article according to claim 1 , which has a pencil hardness of 2H or more . 3. A metal material whose main component is at least one selected from the group consisting of aluminum, iron, nickel and copper, glass, ceramics, resin, cloth, fiber,
Alternatively, the article according to claim 1 or 2, selected from a combination thereof. In 4. silicic acid ester and water paints containing dispersed titanium dioxide, after coating a fabricated surface of the resin layer on the surface of the substrate, heat treatment at 400 ° C. or less, from the claims 1
4. The method for manufacturing the article according to any one of 3 above . 5. The coating of a dispersion of titanium dioxide in a silicate ester, water, and an organic solvent is coated on the surface of the resin layer on the surface of the substrate, and then heat treated at 400 ° C. or lower . A method for manufacturing the article according to any one of claims. 6. A deodorant as claimed in any one of claims 1 to 3.
Item 1.