JPH1119520A - Production of functional material having photocatalytic activity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expose a photo-semiconductive material to the surface of a base material by forming a photoactive layer containing a synthetic resin, the photo- semiconductive material and a sensitizer on the surface of the base material and irradiating the photoactive layer with excimer laser having an oscillation wavelength with a specific value or less to evaporate the synthetic resin. SOLUTION: A photoactive layer is a layer wherein a photo-semiconductive material is exposed to a base material such as glass, ceramics or the like and, for example, formed by irradiating a coating film of a resin compsn. consisting of the photo-semiconductive material, a sensitizer and a synthetic resin (matrix) or a resin molded product obtained from the resin compsn. with excimer laser having an oscillation wavelength of 400 nm or less to generate obrasion to evaporate the syntyhetic resin. Herein, as the photo-semiconductive material, anatase type titanium coated with a porous material such as silica or the like is pref. used. As the sensitizer, benzoyl, bonzoin, pyrene or the like are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a functional material having photocatalytic activity.

[0002]

2. Description of the Related Art Conventionally, photocatalytic particles such as anatase-type titanium oxide have been used on the surface of a substrate to impart functions such as antibacterial property, antifouling property and deodorizing property to the surface of the substrate by utilizing photocatalytic action. There has been proposed a method of forming a thin film. As one of the methods, there is known a method in which anatase-type titanium oxide is kneaded with a binder, applied to the surface of a base material, and thermally cured. As another method, a binder layer is formed on the surface of the base material, and a photocatalyst layer is formed so that a part of the lower layer is buried in the binder layer, and then the photocatalyst layer is exposed to the surface by irradiating light of a specific wavelength. A method has been proposed (Japanese Patent Laid-Open No. 8-131842).

[0003] However, in the former method, only a very small portion of the kneaded photocatalyst particles such as titanium oxide is exposed on the surface, so that there is a problem that a sufficient photocatalysis cannot be exhibited. In the latter method, the photocatalyst layer is exposed by irradiating light after forming the photocatalyst layer and decomposing unnecessary resin and the like by a photocatalytic action. For this reason, light is absorbed by the resin or the like covering the photocatalyst layer, so that the photocatalysis becomes difficult to occur, and the photocatalyst layer may not be sufficiently exposed to the surface.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a functional material having photocatalytic activity by reliably exposing a photoconductive substance to a surface.

[0005]

According to the method of the present invention for producing a functional material having photocatalytic activity, a photoactive layer containing a synthetic resin, a photoconductive substance and a sensitizer is formed on the surface of a substrate. By exposing the photoactive layer to an excimer laser having an oscillation wavelength of 400 nm or less to evaporate the synthetic resin, the photoconductive material is exposed on the substrate surface.

[0006] The photoactive layer used in the present invention is formed of a resin composition comprising a synthetic resin, a photoconductive substance and a sensitizer.

The photoconductive material is not particularly limited as long as it has photocatalytic activity, and examples thereof include zinc oxide, titanium dioxide (hereinafter, referred to as titanium oxide), tungsten oxide, strontium titanate, and strontium oxide. Metal oxides such as diiron; metal chalcogenites such as zinc sulfide, cadmium sulfide, lead sulfide, zinc selenide, cadmium selenide; Group IV elements such as silicon and germanium; gallium-phosphorus, gallium-arsenic, indium-phosphorus III-V such as
Genus compounds; organic semiconductors such as polyacetylene, polypyrrole, polythiophene, polyaniline, and polyvinylcarbazole. The above-mentioned light semiconductive substance may be used alone, or two or more kinds may be used in combination.

[0008] Of the above photoconductive materials, metal oxides such as titanium oxide and tungsten oxide are preferable from a practical viewpoint, and titanium oxide is more preferable because it is easily available. As the type of titanium oxide, any of amorphous, rutile type and anatase type can be used, but when used for the purpose of removing antibacterial properties and nitrogen oxides, the activity of anatase type titanium oxide is most excellent. I have.

[0009] Titanium oxide, which is generally used as a white pigment, is not preferred because the surface is often completely coated with alumina or silica, which lowers the photocatalytic action.

It is more preferable to use a material having a median diameter larger than the laser processing resolution as the above-mentioned light semiconductive substance because the processing workability is improved. In addition, when a decrease in the physical properties of the photoactive layer is allowed to some extent, the photoconductive material is preferably aggregated within the allowable range and dispersed in the photoactive layer, so that workability is improved, which is preferable. .

As the above-mentioned light semiconductive substance, it is preferable to use one coated with a porous substance, and as the above porous substance, a substance satisfying the following requirements is preferable. (1) Deterioration does not occur easily even when it comes into direct contact with an optical semiconductor. (2) Transmit the light required for the photocatalytic reaction. (3) It does not evaporate together with the synthetic resin when excimer laser light is irradiated.

As such a porous substance, for example,
Inorganic substances such as silica and alumina; and fluorine-based resins such as polytetrafluoroethylene. However, in consideration of light transmittance and the like, a glassy substance such as silica is more preferable.

The above-mentioned porous substance is manufactured by a conventionally known manufacturing method. Further, as a method for producing a photocatalyst coated with porous silica, a known method can be used,
For example, according to the sol-gel method, the surface of the photoconductive material can be coated with porous glass. If the porous substance is a microcapsule-like powder, a microcapsule-like photoconductive substance can be obtained by incorporating the photoconductive substance therein. A conventionally known method can be used for the type and manufacturing method of the microcapsules.

As a method for molding the above-mentioned porous microcapsules, for example, a method disclosed in Japanese Patent Publication No. 54-6251 can be adopted, and the particle size and porosity of the microcapsules can be controlled by this method. it can. It is also possible to combine a known method with a method for preparing a multiphase emulsion.

[0015] The porosity of the porous material is not particularly limited. However, coating the photoconductive material with a non-porous material reduces the catalytic activity. As a method for making the microcapsules porous, a known method can be used.For example, as a porous wall constituent component, after forming microcapsules using an inorganic material mixed with an organic substance, only the organic substance is calcined or dissolved with a solvent. Dissolving method: a method in which a water-soluble or oil-soluble salt or the like is introduced into the constituent components of the porous wall and then dissolved later.

The coating state of the photoconductive substance with the above-mentioned porous substance is not particularly limited, but the photoconductive substance adheres when the photoconductive substance is completely covered with the porous substance. It is more preferable because deterioration of the weather resistance of the portion is suppressed.

The shape of the porous substance or the porous microcapsule is not particularly limited. When imparting transparency, the thickness is preferably in the form of a film, and the diameter (major axis) is preferably 0.4 μm or less in the case of a powder. 0.4μ if the refractive index is close to the refractive index of the supporting substrate or binder
Even if it exceeds m, transparency can be imparted. In addition, it is preferable to make the median diameter of the photoconductive substance covered with the porous substance larger than the processing resolution of the laser for improving the processability.

The catalytic effect can be improved by using a conductive substance together with the above-mentioned photoconductive substance. As a method of adding the conductive substance, for example, in the production process of titanium oxide, a method of including an iron oxide component in the structure as a part of the photoconductive substance; A method of supporting a conductive substance is exemplified. Further, as a simple method, for example, a method of adding a conductive substance simultaneously with the photo-semiconductor substance can be adopted. In particular, in the porous substance, by allowing these components to be present at the same time, the carrier is supported. The same effect as in the case can be obtained.

Examples of the conductive substance include powders or fibers of carbon, metal, etc., which are generally used for imparting conductivity. For example, carbon black,
Silver, copper, gold, iron, aluminum, nickel, platinum, palladium, tin oxide, indium oxide and the like are preferably used. Further, as the conductive material, those obtained by coating a conductive material on the surface of a non-conductive material which is a core material can be used. For example, silver-plated fine particles; fine particles coated with aluminum; Coated barium sulfate fine particles are exemplified. Among the above conductive materials, tin oxide fine particles which are easily available and relatively inexpensive and barium sulfate fine particles whose surface is coated with tin oxide are preferable from a practical viewpoint.

As the tin oxide, those containing 0.1 to 20% by weight of antimony oxide are preferable because they exhibit particularly high conductivity.

When the amount of the conductive substance added to the photoconductive substance is small, the effect of the addition of the conductive substance is not exhibited. When the amount is more than a certain amount, the effect of the addition of the conductive substance is saturated. The amount is preferably 0.01 to 100 parts by weight based on 100 parts by weight of the semiconductive substance. When the conductive substance is added to the light semiconductive substance without adding a special process such as supporting the light semiconductive substance on the surface, 1 to 100 parts by weight based on 100 parts by weight of the light semiconductive substance is used. Is preferred. Furthermore, when the conductive substance does not inhibit the photocatalytic effect and is used as a carrier for the photoconductive substance, the amount of addition may be large.

The synthetic resin used in the present invention is not particularly limited as long as it has absorption in the ultraviolet region and ablation occurs by irradiation with an excimer laser in a state in which a sensitizer described later is used in combination. Examples thereof include polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyethylene terephthalate, polycarbonate, polyether sulfone, and polyester.

The sensitizer used in the present invention is preferably a compound exhibiting strong absorption in the ultraviolet region, and examples thereof include benzoin, bilen, benzophenone and benzotriazole. When these are used, ablation becomes easy even with a resin having a low absorption coefficient at the laser oscillation wavelength.

Here, ablation is a phenomenon in which an organic / inorganic compound is irradiated with high-energy light, thereby explosively decomposing a bond between these compounds and dispersing the decomposed fragments in a plasma state. Say.

The substrate used in the present invention is not particularly limited as long as a photoactive layer can be formed on the surface thereof. For example, inorganic materials such as glass and ceramics; organic materials such as plastics and wood; Metal or the like is used. The shape and size of the substrate are not particularly limited.

The photoactive layer is a layer in which the photoconductive substance is exposed on the substrate, and is, for example, a resin composition comprising a photoconductive substance, a sensitizer and a synthetic resin (matrix). 400 to a coating film or a resin molded product obtained from the resin composition.
It can be formed by irradiating an excimer laser having an oscillation wavelength of not more than nm to cause ablation and evaporating a synthetic resin.

There is a certain correlation between the energy intensity per unit pulse and unit area of the excimer laser and the depth of evaporation of the synthetic resin due to ablation. Therefore, in order to expose the photoconductive substance with a smaller number of pulses, the thickness of the resin composition layer is preferably 3 mm or less because it becomes difficult to expose the photoconductive substance if it is too thick. Preferably, more preferably 200μ
m or less.

Further, the ablation of the above synthetic resin is effective.
In order to raise it efficiently, 400 nm or less of the above synthetic resin
The extinction coefficient of an excimer laser having an oscillation wavelength of 1 ×
10 ^Twocm^-1The above is preferred. The extinction coefficient is 1 × 10^Two
cm^-1Below, the depth at which ablation occurs is very
It does not become shallow or ablation itself
There is.

The type of the excimer laser is not particularly limited as long as it acts on the synthetic resin and the sensitizer to cause ablation. (A) Absorption coefficient of the synthetic resin at the oscillation wavelength of the excimer laser In order to shorten the working time, it is necessary to use a laser with an oscillation wavelength with a deep ablation depth per pulse, and (b) increase the amount of energy per unit area per pulse. preferable.

As the type of the excimer laser, known types can be used. For example, F ₂ (oscillation wavelength: 157 n
m), ArCl (oscillation wavelength 175 nm), ArF (oscillation wavelength 193 nm), KrCl (oscillation wavelength 222 nm),
KrF (oscillation wavelength 248 nm), XeBr (oscillation wavelength 2
82 nm), XeCl (oscillation wavelength 308 nm), XeF
(An oscillation wavelength of 351 nm).

The laser processing apparatus used in the present invention is not special, and a commercial product can be used as it is.

[0032]

According to the production method of the present invention, the photoactive layer is formed of a resin composition containing a photoconductive substance, a sensitizer and a synthetic resin, and is irradiated with an excimer laser having an oscillation wavelength of 400 nm or less. This causes ablation, so that the synthetic resin can be evaporated. On the other hand, since the energy required for ablation of a photoconductive substance is much larger than that of the synthetic resin, the synthetic resin can be selectively removed from the photoactive layer by appropriately adjusting the energy amount of the excimer laser. It can be removed. Further, since the ablation by the excimer laser is used, the synthetic resin is removed in a plasma state.

Therefore, compared with the conventional thermal processing using carbon dioxide gas or YAG laser, the synthetic resin in the vicinity of the excimer laser irradiation site is less likely to be deteriorated by heat. In addition, since the excimer laser is used, it is easy to control the removal depth of the synthetic resin. Therefore, the photoconductive substance can be reliably exposed to the surface.

Ablation is liable to occur when the photoactive layer contains a sensitizer, and even a synthetic resin having a low absorption coefficient at an oscillation wavelength of 400 nm or less can be easily evaporated. Further, even in the case of a synthetic resin having a high absorption coefficient at an oscillation wavelength of 400 nm or less, ablation is easily caused by irradiation with an excimer laser.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Titanium oxide (manufactured by Wako Pure Chemical Industries, Ltd.)
4 g of a mixture (powder) obtained by mixing anatase type, primary particle diameter 0.3 μm) and tin oxide containing antimony oxide (“T-1” manufactured by Mitsubishi Materials Corporation, particle diameter 0.02 μm) at a weight ratio of 9: 1. Was added to 50 ml of an aqueous sodium silicate solution (4 mol / l in terms of silicon dioxide) and stirred for 10 minutes to prepare a uniform suspension. The above suspension was added to 110 ml of a benzene solution of sorbitan monostearate (1% by weight), and shaken for 3 minutes using a shaker.
An O-type (water-in-oil type) emulsion was prepared. Then, the above emulsion was treated with an aqueous solution of ammonium sulfate (1 mol / l) 50
The solution was added to 0 ml with stirring, and reacted for 30 minutes.
After completion of the reaction, the reaction mixture was filtered, washed with water, and dried at 110 ° C. for 24 hours.
A 3 μm microcapsule-shaped photoconductive substance was obtained.

The above microcapsule-shaped photoconductive substance (0.3 g), toluene (7 ml) and one-part dry acrylic paint ("Acrydic A-16" manufactured by Dainippon Ink and Chemicals, Inc.)
6 ", extinction coefficient 2 × of Acurly resin at wavelength 193 nm
10 ³ ) 5 g were kneaded to obtain a coating material containing a light semiconductive substance. The above coating material was applied to a smooth aluminum-zinc alloy steel plate base material (size: 0.4 mm thick x 2 cm x 2 cm) by spray coating so that the coating thickness after drying became 20 m, and then ArF (oscillation wavelength 193 nm) A) Ablation of the coating film by a laser irradiation device,
A functional material sample having a photoconductive material exposed on the surface was obtained.

(Example 2) 15 parts by weight of a microcapsule-shaped light semiconductive substance obtained in the same manner as in Example 1 and a thermoplastic polyimide resin (manufactured by Mitsui Toatsu Chemicals, wavelength 248)
extinction coefficient of polyimide resin in nm 2.8 × 10 ⁵ ) 1
Then, the mixture was kneaded with 100 parts by weight, followed by press molding to obtain a molded body (size: 2 mm thick × 10 cm × 2 cm). The molded body was subjected to ablation of the molded body by a KrF (oscillation wavelength: 248 nm) laser irradiation device to obtain a functional material sample having a surface exposed to a photoconductive substance.

(Comparative Example 1) A coating material containing a photoconductive substance obtained in the same manner as in Example 1 was sprayed onto a smooth aluminum-zinc alloy steel sheet substrate (size: 0.4 mm thick x 2 cm x 2 cm). By coating, the film thickness after drying is 20
A sample coated to a thickness of μm was obtained. No laser irradiation was performed after the coating film was formed.

(Comparative Example 2) The molded body sample obtained in Example 2 was used without laser irradiation.

The samples obtained in the above Examples and Comparative Examples were evaluated for the following antibacterial properties, and the results are shown in Table 1. (1) Antibacterial performance evaluation method A sample was placed in a sterile petri dish, and a test bacterial solution [Difco's Heart Infusion Broth medium (hereinafter referred to as BH
A solution prepared by diluting 25 g / l with physiological saline 100-fold in a saline solution (prepared at 1 × 10 ⁷ CFU / ml) was dispensed. After the petri dish was sealed and cultured at 30 ° C. for 1 day under a fluorescent lamp, the viable cell count of the test bacteria after the culture was measured by a usual colony counting method. The test bacteria were E. coli and Micrococ.
cus sp.

(2) Antifungal Performance Evaluation Method Molds and yeasts previously cultured on a potato dextrose agar medium (manufactured by Nissui Pharmaceutical Co., Ltd .; hereinafter referred to as PDA medium) were scraped with a platinum loop to obtain 0.05% of fungi. Tween
After dispersing and stirring in a saline solution to which 80 had been added, filtration was performed using a glass filter. The obtained filtrate is
The mixture was centrifuged at 000 rpm for 15 minutes, and the supernatant was removed to obtain a precipitate (spore). To this was added an appropriate amount of potato dextrose liquid medium (Difco, hereinafter referred to as PDB medium) to prepare a spore suspension. After autoclaving the PDA medium, keep the agar
The mixture was incubated at 5 ° C., and the above-mentioned spore suspension was added to 1/10 volume of PDA medium and stirred. The samples obtained in Examples and Comparative Examples were placed in a sterile Petri dish, and the spore suspension-containing PDA medium was dropped by 50 μl on each,
It was solidified into a hemisphere. Next, the petri dish was sealed and cultured at 30 ° C. for 3 to 5 days under a fluorescent lamp, and then the growth of the bacteria was visually determined according to the following criteria. ：: No growth of test bacteria was observed ×: Growth of test bacteria was observed

[0043]

[Table 1]

[0044]

The method for producing a functional material having photocatalytic activity according to the present invention has the above-described structure, and the photoconductive substance can be reliably exposed to the surface. Even if it contains an acidic substance, it exhibits stronger photocatalytic activity than conventional ones. Therefore, the functional material obtained by this production method has stronger antibacterial action, antifouling action, deodorizing action and nitrogen oxide removing action than those obtained by the conventional method.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C09D 7/12 C09D 7/12 Z

Claims (2)

[Claims] 1. A photoactive layer containing a synthetic resin, a photoconductive substance and a sensitizer is formed on the surface of a substrate, and a photoactive layer is formed on the photoactive layer.
A method for producing a photocatalytically active functional material, comprising exposing a photoconductive substance to a substrate surface by irradiating an excimer laser having an oscillation wavelength of 0 nm or less to evaporate a synthetic resin. 2. The method for producing a photocatalytically active functional material according to claim 1, wherein an anatase type titanium oxide coated with a porous material is used as said photoconductive material.