JP2001269581A - Photocatalyst-coated composite member excellent in photocatalytic activity and light resistance and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst-coated composite member which is improved in photocatalytic activity and excellent in light resistance and in which the decomposition of a coating film used as a binder is controlled. SOLUTION: A photocatalyst coating film 3 in which photocatalyst particles coated with zeolite are dispersed is formed on a base material directly or through a primer layer 2. The photocatalyst particles 4 are coated with zeolite films 5, for example, 5 nm-5 μm in thickness and dispersed in the coating film 3 in a ratio of 5-80 mass%. Metal, glass, tile, a synthetic resin, a particle board, gypsum, cocrete, or the like, are used for the base material 1. The photocatalyst coating film 3 is formed by applying an organic resin coating material containing the photocatalyst particles 4 coated with the zeolite films 5 on a primer coating film and heat-treating the coating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to organic substances, SOx, NO
The present invention relates to a composite member which decomposes x and the like, has a photocatalytic effect effective for antibacterial activity, and has excellent light resistance even in combination with an organic resin.

[0002]

_2. Description of the Related Art Photocatalysts such as TiO ₂ are activated by light irradiation and exhibit an action of decomposing organic substances, SOx, NOx and the like. Utilizing this effect, it has been studied to impart photocatalytic activity to various materials by providing a coating film containing photocatalyst particles on the surface of a substrate. The composite member with photocatalytic activity decomposes surface dirt caused by air contaminated with soot, exhaust gas, etc. around large cities and industrial areas,
Maintain aesthetics for a long time. In this type of photocatalyst-coated composite member, when an organic substance is used as a binder of a coating film for dispersing photocatalyst particles, O ₂ ⁻ ,
-The organic coating film is decomposed by active oxygen such as OH, and the coating film may be peeled off by chalking.

[0003] Even if the amount of the photocatalyst particles is reduced to suppress the decomposition of the organic coating film, satisfactory light resistance and photocatalytic activity cannot be obtained. Therefore, an inorganic material such as a silica-based material is generally used as a base resin (Japanese Patent Laid-Open No. 7-1).
13272, JP-A-8-164334, W
O96 / 29375). In addition, even when an organic coating film is based on a relatively stable fluororesin, the decomposition of the coating film is suppressed. Therefore, a coating film in which anatase TiO ₂ particles are dispersed based on a fluororesin is known ( JP-A-7-171408).

[0004]

A composite member having a photocatalytic coating film using an inorganic material as a binder does not cause chalking even when used as a building material or the like exposed to light irradiation for a long period of time. Will be maintained. However, it promotes contact with the resin carrying photocatalyst particles and components requiring decomposition,
Alternatively, the photocatalytic reaction occurs only when the photocatalytic particles come into contact with the photocatalytic particles without increasing the concentration of the photocatalytic particles around the photocatalytic particles. NOx
For example, there is room for improvement.

When the photocatalyst particles are supported on the substrate with a hardly decomposable binder together with an adsorbent such as activated carbon or zeolite, the components required for decomposition in the atmosphere are preferentially collected by the adsorbent, and the resolution of the photocatalyst particles is improved. However, it is difficult to uniformly disperse the photocatalyst particles and the adsorbent in the coating film, and if both are covered with the binder, the catalytic action and the adsorptive action are significantly reduced. Further, a metal plate or the like on which an inorganic coating film in which photocatalyst particles are dispersed is formed is also disadvantageous in that the processability is poor. For example, when bending the coated steel sheet with photocatalytic activity by dispersing photocatalyst particles in the inorganic coating,
Cracks are easily generated and the coating film is easily peeled off from the steel sheet surface. On the other hand, a coating film in which photocatalyst particles are dispersed in a fluororesin tends to have insufficient light resistance. In order to satisfy both light resistance and photocatalytic activity, a method of preventing direct contact between the photocatalyst particles and the organic coating film by coating the periphery of the photocatalyst particles with silica may be considered. Photocatalytic activity decreases.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been devised in order to solve such a problem. By dispersing photocatalyst particles coated with zeolite in a coating film, the photocatalytic activity can be enhanced, It is an object of the present invention to provide a photocatalyst-coated composite member that suppresses decomposition of a coating film used as a binder and has excellent light resistance. In order to achieve the object, the photocatalyst-coated composite member of the present invention is characterized in that an inorganic or organic photocatalyst coating film in which photocatalyst particles coated with zeolite are dispersed is formed on a substrate surface.

As the photocatalyst particles coated with zeolite, for example, photocatalyst particles covered with a zeolite film having a thickness of 5 nm to 5 μm are used, and it is preferable to disperse them in the photocatalyst coating film at a ratio of 5 to 80% by mass. Base materials include metal, glass, tile, synthetic resin, particle board,
Gypsum, concrete, etc. are used. Examples of the metallic substrate include a normal steel plate, a plated steel plate, a stainless steel plate, an aluminum plate, and an aluminum alloy plate. The photocatalyst coating film in which the zeolite-coated photocatalyst particles are dispersed forms a primer coating film containing a pigment on the substrate surface, and then applies an organic resin coating containing the zeolite-coated photocatalyst particles on the primer coating film. And formed by heat treatment. Alternatively, the primer layer may be omitted, and the photocatalytic coating film may be formed directly on the surface of the substrate.

[0008]

[Function] Photocatalytic particles are excited by ultraviolet irradiation,
It exhibits photocatalytic activity to decompose organic substances. Therefore, when a coating film is formed using an organic resin, the resin itself is oxidatively decomposed and chalking occurs. The present inventors disperse the zeolite-coated photocatalyst particles in the organic resin coating film in the process of studying a method of suppressing choking caused by the photocatalytic reaction, and the decomposition of the organic resin is maintained while maintaining the photocatalytic activity. Found to be suppressed. This is inferred as follows.

The zeolite has the general formula M _{x / m} Al _x Si
_(1-x) aluminosilicate crystal represented by O ₂ .nH ₂ O (M is a cation, m is the valence of cation M, and n is the number of water molecules adsorbed in pores) It is known as a molecular sieve having pores of a molecular size (5 to 13 °) for selectively adsorbing and transmitting gaseous components inside the crystal. Therefore, even if a zeolite membrane is provided on the surface of the photocatalyst particles,
Formaldehyde, SOx, NOx and the like in the atmosphere pass through the zeolite membrane and reach the surface of the photocatalyst particles. Rather, formaldehyde, SOx, NOx, and the like are preferentially adsorbed to the zeolite membrane from the atmosphere, the chance of contact with the photocatalyst particles increases, and the photocatalytic activity improves.

The effect of improving the photocatalytic activity by providing a zeolite membrane effectively functions for both inorganic coatings and organic coatings. In the organic coating film, the chalking resistance is further improved by forming a zeolite membrane. That is,
The radical generated on the surface of the photocatalyst particles has a very short movable distance and does not reach the organic resin constituting the coating film because the surface of the photocatalyst particles is covered with the zeolite film. In this regard, in a coating film in which photocatalyst particles coated with silica are dispersed, contact between the photocatalyst particles and the components requiring decomposition is prevented by the silica, and the photocatalytic activity is reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A photocatalyst-coated composite member according to the present invention comprises:
For example, as shown in FIG. 1, a photocatalytic coating film 3 is provided on a surface of a base material 1 such as metal, glass, tile, synthetic resin, particle board, gypsum, concrete, etc. via a primer layer 2 as necessary. . The primer layer 2 is a photocatalytic coating 3
The primer layer 2 can be omitted from an inorganic base material 1 made of metal or the like that is not easily affected by a photocatalytic reaction, which is provided to improve the adhesion of the primer layer (FIG. 2).

The metal substrate used as the substrate 1 includes:
There are various types of plated steel sheets such as ordinary steel sheets, galvanized steel sheets, and aluminum-plated steel sheets, stainless steel sheets, aluminum sheets, and aluminum alloy sheets. When a metal substrate is used, pretreatment such as alkali degreasing, chromate treatment, and phosphate treatment is performed as necessary. The primer layer 2 is made of a rust preventive pigment,
It is formed by applying a paint in which an extender, a white pigment, and the like are dispersed in an organic resin to the substrate 1 and baking it. The primer layer 2 improves the adhesion and corrosion resistance of the photocatalytic coating film 3. As the organic resin, a polyester resin, an acrylic resin, an epoxy resin, a urethane resin, or the like is used. When a metal substrate having excellent corrosion resistance and good adhesion to the photocatalytic coating film 3 is used, the primer layer 2 can be omitted.

The photocatalyst coating film 3 is formed by applying a coating material in which the photocatalyst particles 4 covered with the zeolite film 5 are dispersed by electrostatic spraying or roll coating and baking. When an inorganic binder such as silica or alumina is used, baking is performed at 400 ° C. or less, and when an organic binder is used, low-temperature baking at 200 ° C. or less is also possible. Examples of the organic binder include polyester resin, acrylic resin, epoxy resin, urethane resin, vinylidene fluoride resin, and silicone resin. As the photocatalyst particles 4,
One or more of TiO ₂ , ZnO, WO ₃ , FeTiO ₃ and SrTiO ₃ are used. Among them, fine particles with excellent chemical stability and low cost and high activity (particle size: 5-200
nm), anatase-type TiO ₂ is preferable. The activity of the photocatalyst particles 4 increases as the particle size decreases, but if the particle size is too small, it becomes difficult to disperse the photocatalyst particles in the paint.

After dispersing the photocatalyst particles in a solution prepared by dissolving aluminum alkoxide, alkoxysilane, alkali metal and / or alkaline earth metal alkoxide, amines and water in an organic solvent, the powder is filtered and filtered.
When dried at 0 to 400 ° C., the alkoxide contained in the solution adheres to the surface of the photocatalyst particles 4 in a hydrolyzed state, and undergoes a dehydration and polycondensation reaction in a heating step to form a zeolite membrane 5.
Is formed. At this time, if amines are present, clouding after hydrolysis is prevented, a uniform zeolite membrane 5 is formed, and gelation is also prevented. As a result, the surface of the photocatalyst particles 4 is covered with the uniform zeolite membrane 5.

Photocatalyst particles 4 coated with zeolite membrane 5
Is dispersed in the photocatalytic coating film 3 at a ratio of 5 to 80% by mass. When the dispersion amount of the photocatalyst particles 4 is less than 5% by mass, the decomposition efficiency of organic substances, SOx, NOx, etc. by the photocatalytic reaction is not sufficient.
Formation becomes difficult. The zeolite membrane 5 has a thickness of 5 nm to 5 μm.
It is preferably formed on the surface of the photocatalyst particles 4 with a film thickness of m. When the film thickness is less than 5 nm, the ability to adsorb gas is insufficient, and the contact between the photocatalyst particles 4 and the organic resin cannot be completely prevented when the organic resin is used as the binder. Conversely, when the film thickness exceeds 5 μm, the zeolite membrane 5
Cracks are more likely to occur. The zeolite membrane 5
Is adjusted by the concentration and viscosity of the solution, the contact time with the photocatalyst particles 4, and the like.

When an organic resin is used for the binder, the baking temperature at the time of forming the photocatalytic coating film 3 is set to an optimum temperature according to the type of the resin used. 150 ~
A baking temperature of 300 ° C. is sufficient, but when using a heat-resistant resin, the baking temperature can be extended to 450 ° C. At a baking temperature of less than 150 ° C., crosslinking between polymers does not proceed sufficiently, and poor adhesion and peeling of the coating film are likely to occur.
Conversely, if the baking temperature is too high, peeling of the coating film due to decomposition of the resin occurs, and the workability decreases. By properly setting the baking temperature, a strong bond is obtained between the primer layer 2 and the photocatalytic coating film 3, and the adhesion of the photocatalytic coating film 3 to the primer layer 2 is improved. In the case of a paint based on a mixture of a vinylidene fluoride resin and an acrylic resin, it is preferable to perform controlled cooling after baking in order to suppress crystallization of the coating film.

[0017]

Example 1 1.0 mol of aluminum isopropoxide, 2.5 mol of tetraethoxysilane, 1.0 mol of sodium methoxide, 5.0 mol of monoisopropanolamine
A sol-gel basic bath of zeolite was prepared by dissolving 7.0 mol of water and 15.0 mol of water in 15.0 mol of butyl cellosolve. A sol-gel bath was prepared by adding butyl cellosolve to decrease the viscosity, and a bath was prepared by adding 0.2 to 2.0% of hydroxypropylcellulose to increase the viscosity.

1 kg of anatase-type TiO ₂ particles having a particle size of 20 nm were added to 1 liter of each sol-gel bath, stirred and sufficiently dispersed, and then filtered with a filter.
Heated in a drying oven at 10 ° C. for 10 minutes. The zeolite membrane 5 formed on the surface of the TiO ₂ particles 4 has a thickness of 5.0 nm to 5.0 μm.
m. Using a concrete plate and an aluminum-plated steel plate having a plate thickness of 0.5 mm as a base material 1, applying an epoxy resin paint in which rust-preventive pigments and extender pigments are dispersed, and baking at 200 ° C. for 20 minutes to form a primer layer 2 did.

On the concrete plate, a photocatalytic coating material in which anatase-type TiO ₂ particles 5 having a particle size of 20 nm and covered with a zeolite film 5 are dispersed is applied to the primer layer 2.
The photocatalyst coating film 3 was formed by baking at 00 ° C. for 20 minutes. A photocatalytic coating film 3 was similarly formed on an aluminum-plated steel sheet using a photocatalytic coating material in which anatase TiO ₂ particles 4 having a particle size of 7 nm were dispersed.

For comparison, a concrete plate on which a photocatalytic coating film 3 containing anatase-type TiO ₂ particles having a particle size of 20 nm which is not covered with the zeolite film 5 was formed, an anatase-type TiO ₂ particle 4 having a particle size of 20 nm and a particle size of 2 μm Concrete plate on which a photocatalytic coating film 3 containing zeolite powder of
Aluminum-plated steel sheet on which a photocatalytic coating film 3 containing anatase-type TiO ₂ particles 7 having a particle size of 7 nm which is not covered with the zeolite film 5 is formed.
₍₂₎ An aluminum-plated steel sheet having a photocatalytic coating film 3 containing particles 4 and zeolite powder having a particle size of 2 μm was prepared.

Each composite member on which the photocatalytic coating film 3 is formed is
It was subjected to an Ox resolution test and a light fastness test. In the NOx resolution test, the photocatalyst-coated composite member was sized 210 mm x 3
A test piece of 00 mm was cut out and placed in a glass container. While irradiating with a fluorescent lamp, high-purity air containing NO gas having a concentration of 1 ppm is continuously fed into the glass container at a flow rate of 0.5 L / min.
The O ₂ concentration was measured with a NOx meter. The NOx removal rate was calculated from the measured value according to the following equation, and the NOx resolution of each test piece was evaluated from the obtained NOx removal rate. NOx removal rate = [A ₁ − (A ₂ + B ₂ ) / A ₁ ] × 100 (%) where A ₁ : initial NO concentration A ₂ : NO concentration after decomposition B ₂ : NO ₂ concentration after decomposition

In the light resistance test, the photocatalyst-coated composite member was cut into test pieces having a size of 100 mm × 100 mm,
Irradiation was performed with a 20 W black light (UV intensity: 5.0 mW / cm ² ) placed at a position distant from a centimeter. After the irradiation was continued for 24 hours, the surface of the test piece was rubbed with a finger, and the coating film adhered to the finger was evaluated as ×. Light resistance was evaluated as ○ when gloss retention was 80% or more without adhesion.

As can be seen from the survey results in Tables 1 and 2.
TiO coated with zeolite membrane 5 _TwoDispersed particles 4
The coated photocatalyst coating 3 is made of TiO_TwoParticle 4 is dispersed alone
Photocatalyst coating 3 or TiO_TwoSeparate particles and zeolite powder
Higher NOx resolution than the dispersed photocatalytic coating 3
did. In addition, the organic components of the coating film can be separated by UV irradiation.
Without being understood, the light resistance was also good.

[0024]

[0025]

[0026]

Example 2 A zinc-plated steel sheet and an aluminum-plated steel sheet having a thickness of 0.5 mm were used for a base material 1 and alkali degreasing was performed.
After the phosphate treatment, it was washed with water and dried. Next, a polyester resin paint in which a rust-preventive pigment and an extender pigment are dispersed is applied and baked at 215 ° C. × 40 seconds to form a primer layer 2
Was formed. For a galvanized steel sheet, apply a photocatalytic paint in which anatase type TiO ₂ having a particle diameter of 20 nm coated with a zeolite film is dispersed in various organic resins to the primer layer 2. For an aluminum plated steel sheet, an anatase having a particle diameter of 7 nm is applied. Photocatalytic coating film 3 was similarly formed using a photocatalytic coating material in which type TiO ₂ was dispersed in various organic resins. As the photocatalyst particles 4 covered with the zeolite membrane 5, those prepared in the same manner as in Example 1 were used. In the photocatalytic coating film 3 based on a polyester resin, 200 to 250 ° C. × 1 minute,
The photocatalytic coating film 3 based on a vinylidene fluoride-acrylic mixed resin was baked at 250 ° C. for 1 minute.

For comparison, a galvanized steel sheet having a photocatalytic coating film 3 containing anatase-type TiO ₂ particles 4 having a particle size of 20 nm, not covered with a zeolite film 5, having a particle size of 20 nm
Galvanized steel sheet formed with a photocatalytic coating film 3 containing anatase-type TiO ₂ particles 4 and zeolite powder having a particle size of 2 μm, and a photocatalytic coating film containing anatase-type TiO ₂ particles 4 having a particle size of 7 nm which are not covered with a zeolite film 5 Coated aluminum plate, anatase type T having a particle size of 7 nm
An aluminum-plated steel sheet having a photocatalytic coating film 3 containing iO ₂ particles 4 and zeolite powder having a particle size of 2 μm was prepared.

For each composite member having the photocatalytic coating film 3 formed thereon,
In the same test as in Example 1, NOx resolution and light resistance
And the processability was also evaluated. In the workability test
Is a 2mm bend of a 25mm x 50mm test piece,
Paste the adhesive tape on the tape and peel it off instantly, then bend
Visual observation of the coating peeling state of the part, the coating peeling was detected
Processed as × and those without peeling as ○
The sex was evaluated. As can be seen from the survey results in Tables 3 and 4.
TiO coated with zeolite membrane 5 _TwoDispersed particles 4
The coated photocatalyst coating 3 shows high NOx resolution and
Light resistance and workability were also good. In contrast, TiO
_TwoPhotocatalyst coating film 3 in which particles 4 are dispersed alone or TiO_Twoparticle
4 and the zeolite powder-dispersed photocatalytic coating 3
Organic components of the coating film are decomposed by external radiation, causing chalking.
did.

[0029]

[0030]

[0031]

As described above, since the photocatalyst-coated composite member of the present invention forms a photocatalyst coating film in which photocatalyst particles coated with a zeolite film are dispersed, formaldehyde, SOx, SOx, Harmful components such as NOx are adsorbed by the zeolite membrane and are maintained at a short distance from the photocatalyst particles. Therefore, the photocatalytic reaction is efficiently used for decomposing harmful components, and high resolution is exhibited. In addition, the zeolite membrane that covers the photocatalyst particles prevents the organic components that make up the coating film from directly contacting the photocatalyst particles. Never be. Therefore, a photocatalytic coating film having excellent light resistance is obtained. Furthermore, when a metal substrate is used as a base material, a coated metal plate excellent in workability can be obtained, and thus it is used in a wide range of fields as various interior building materials utilizing photocatalytic activity, outer panels of home electric appliances, and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a surface layer of a photocatalyst-coated composite member on which a photocatalyst coating film is formed via a primer layer.

FIG. 2 is a cross-sectional view showing a surface layer of a photocatalyst-coated composite member having a photocatalyst coating film formed directly on a substrate.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B01J 35/02 311 B01D 53/36 J B32B 9/00 104Z (72) Inventor Hiroshige Nakamura 7 Takatani-machi, Ichikawa-shi, Chiba No. 1 Inside Nisshin Steel R & D Co., Ltd. (72) Inventor Kenji Sakado 7-1 Inside Nisshin Steel Co., Ltd. R & D Laboratories (72) Inventor Akihiro Ando 7 Takaya Shinmachi, Ichikawa-shi, Chiba No. 1 F-term in Nisshin Steel R & D Co., Ltd. F-term (reference) 4D048 AA02 AA06 AA17 AB03 AB05 BA03Y BA07Y BA12Y BB03 CC04 CC38 EA01 EA08 4F100 AA20 AA21 AB01 AB03 AB10 AC04 AC04A AE01 AE06 AG00 AK01 AK52 AT00 AK17 AK52 AP02 BA03 BA07 BA10A BA10B CC00 CC00A DE01A EH46 EH462 EH71 EJ422 EJ65 EJ65C GB07 GB08 GB48 JA20A JL01 JL08 JL08A JM02A JN02 JN30 YY00A 4G069 AA03 AA08 AA11 BA04A BA04B CA07 BA02B02 BA17 BC EA14 EB15X EB15Y EE01 EE06 FA03 FB23 FB30 FC05 FC08

Claims (4)

[Claims] 1. A photocatalyst-coated composite member having excellent photocatalytic activity and light resistance, characterized in that a photocatalyst coating film in which photocatalyst particles coated with zeolite are dispersed is formed on a substrate surface. 2. The photocatalyst particles coated with zeolite are 5
The photocatalyst-coated composite member according to claim 1, wherein the photocatalyst-coated composite member is dispersed in the photocatalytic coating film at a ratio of from about 80% by mass. 3. The photocatalyst-coated composite member according to claim 1, wherein the photocatalyst particles covered with the zeolite film having a thickness of 5 nm to 5 μm are dispersed in the photocatalyst coating film. 4. An organic resin paint containing photocatalyst particles coated with zeolite is applied on the primer coating film, and a heat treatment forms a photocatalyst coating film in which the photocatalyst particles coated with zeolite are dispersed. A method for producing a photocatalyst-coated composite member having excellent photocatalytic activity and light resistance.