JP2002191984A - Photocatalyst composition and thermoplastic resin composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin material having a photocatalytically active surface excellent in photocatalytic reactivity, used on the wall surface or the like of a building and not deteriorated over a long period of time. SOLUTION: A thermoplastic resin composition is prepared by compounding a photocatalyst composition which consists of a photocatalyst and an inorganic powder inactive as the photocatalyst, with a thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst composition and a thermoplastic resin composition, and more particularly, to a resin material which is used for a wall surface of a building, has a long term photocatalytic reaction activity, and is hardly deteriorated. To a photocatalyst composition and a thermoplastic resin composition.

[0002]

2. Description of the Related Art Recently, by applying a photocatalyst to an outer wall of a building, a soundproof wall of a road, an inner wall of a hospital, or an inner wall of a vegetable store, for example, ammonia is applied by utilizing a photocatalytic reaction under ultraviolet irradiation. , removal of malodor substances such as mercaptans, prevention of soot stains, removal of harmful substances such as NO _X, the removal of plant growth (spoilage) promoting substances such as ethylene generated from fruit and vegetables, such as sterilization or antifungal is achieved (For example, JP-A-9-277463, JP-A-9-277463)
1-11659). Since the photocatalyst is powder particles of a semiconductor (photocatalyst) having a band gap of 0.5 to 5 eV such as titanium dioxide, the photocatalyst is used by being fixed to a base material using an organic binder or mixed with a resin. You. However, there is a problem that the organic binder and the base material are decomposed by the photocatalytic function of the photocatalyst. In contrast, for example,
A method of preparing a porous microcapsule containing a photocatalyst by a water-in-oil type emulsion preparation method and blending it with an unsaturated polyester resin (JP-A-9-225320)
Japanese Patent Application Laid-Open No. 9-225319), and a method of supporting ceramics in the form of islands on the surface of titania particles has been proposed. However, using these methods to prepare photocatalyst particles that do not decompose an organic binder or a substrate requires a complicated process, and the operation is complicated.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, an object of the present invention is to provide a photocatalytically active surface which is used for a building wall or the like and which does not deteriorate for a long period of time and which has excellent photocatalytic reactivity. It is to provide a resin material having. The present inventors have conducted intensive studies and found that when a mixture of anatase-type titanium dioxide powder and a large amount of rutile-type titanium dioxide powder was kneaded into a resin, high photocatalytic reactivity was obtained over a long period of time without photodeterioration of the resin molded product. Have been found, and the present invention has been completed based on this finding.

[0004]

Thus, according to the present invention, (1) a photocatalyst composition comprising a photocatalyst and an inorganic powder which is inactive as a photocatalyst, and (2) a thermoplastic resin are described in (1) above. And (3) a resin molded article comprising the thermoplastic resin composition described in the above (2).

In a preferred embodiment, (4) the photocatalyst composition according to the above (1), wherein the photocatalyst is an anatase type titanium dioxide, and (5) the inorganic powder inactive as the photocatalyst is rutile type titanium dioxide. (6) The photocatalyst composition according to (1), wherein the weight ratio of the photocatalyst to the inorganic powder inert as the photocatalyst is 5/95 to 20/80. And (7)
A method for producing a thermoplastic resin composition is provided, wherein the photocatalyst and an inorganic powder which is inert as the photocatalyst are mixed in advance and then mixed with the thermoplastic resin.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The photocatalyst used in the present invention is a semiconductor having a band gap of 0.5 to 5 eV, and a semiconductor that generates a photocatalytic reaction by irradiating the semiconductor with light having energy equal to or larger than the band gap. When such a semiconductor is irradiated with light,
Electron excitation from the valence band to the conduction band occurs, holes are generated in the valence band, and electrons are generated in the conduction band. These holes and electrons undergo photocatalytic reactions in the gas phase or aqueous phase where they come into contact with the semiconductor surface. It is known. Note that the forbidden band width is preferably 2 to 4 eV. Examples of the photocatalyst include metal oxides such as anatase type titanium dioxide, tin dioxide, zinc oxide, tungsten trioxide, cerium oxide, barium titanate, and ferric oxide; zinc sulfide, cadmium sulfide, lead sulfide, and selenide. Metal chalcogenides such as zinc and cadmium selenide; group IV elements such as silicon and germanium; compounds of group III and group V elements such as gallium phosphide, gallium arsenide and indium phosphide; polyacetylene, polypyrrole, polythiophene, polyaniline And organic semiconductors such as polyvinyl carbazole. Among these, metal oxides such as anatase-type titanium dioxide, suboxide, tungsten trioxide, and cerium oxide are preferable, and anatase-type titanium dioxide is particularly preferable. In addition, a noble metal such as platinum or silver can be carried on the semiconductor to enhance the catalytic action. The photocatalyst is usually in the form of a powder. The powder particles of the photocatalyst having primary particles of 1 to 1000 nm have a large surface area, which is advantageous for the photocatalytic reaction. When the primary particles are aggregated into granules to form secondary particles having a particle size of 10 to 200 μm, it is preferable that most of the particles are loosened into the primary particles in the process of preparing the photocatalyst composition described below.

[0007] Titanium dioxide has three crystal structures, anatase type, rutile type and brookite type, but the anatase type and brookite type have photocatalytic activity. The crystals of the anatase type are tetragonal, a: c = 1: 1.771, and the specific gravity is 3.84.
It is. 800-1000 anatase type titanium dioxide
Converts to rutile titanium dioxide when heated to ° C. The rutile type titanium dioxide has a tetragonal crystal system, and a: c = 1:
At 0.6442, the specific gravity is 4.26, which is inactive as a photocatalyst. The crystal structure is distinguished by X-ray diffraction measurements.

The inorganic powder that is inert as a photocatalyst used in the present invention (hereinafter referred to as “photoinert inorganic powder”) is
It is an inorganic powder that does not or hardly exhibits a photocatalytic reaction. Examples of the photoinert inorganic powder, in addition to the above rutile titanium dioxide, hydrotalcite, bentonite, zeolite, talc, mica, clay, kaolin, mica, montmorillonite, silica, calcium carbonate, calcium phosphate, calcium silicate, Examples include aluminum oxide, aluminum hydroxide, aluminum sulfate, aluminum phosphate, alumina cement, Portland cement and the like. Among them, rutile-type titanium dioxide, hydrotalcite, and bentonite treated with an organic substance are preferable, and rutile-type titanium dioxide is particularly preferable. The primary particle diameter of the photo-inert inorganic powder is preferably 1 to 1000.
nm, more preferably 10 to 200 nm, which is smaller than the particle size of the semiconductor.

The photocatalyst composition of the present invention comprises a photocatalyst powder and a photoinert inorganic powder in a weight ratio of usually 5/95 to 20 /.
80, preferably in the range of 8/92 to 15/85. The method of mixing the two is not particularly limited as long as it is a method using a device used for mixing powders. Preferred mixing devices include a tumbler mixer,
Universal mixers, Hobart mixers, ribbon blenders, Henschel mixers and the like can be mentioned. As a preferred embodiment of the photocatalyst composition, there is an embodiment in which an anatase type titanium dioxide is used as a photocatalyst powder and a rutile type titanium dioxide is used as a photoinert inorganic powder. In this case, in addition to the method of mixing both powders with the above-described mixing device, anatase-type titanium dioxide powder at a temperature of 800 to 13 is used.
By baking at 00 ° C. for 1 to 5 hours, a method of preparing a mixture of anatase-type titanium dioxide particles and rutile-type titanium dioxide can be adopted. Also in this case, the weight ratio between the anatase type and the rutile type needs to be within the above range.

Examples of the method of using the photocatalyst composition of the present invention include a method in which the photocatalyst composition is mixed with a thermoplastic resin to obtain a molded product; a method in which the photocatalyst composition is mixed with ready-mixed concrete to obtain a concrete molded product.

[0011] The thermoplastic resin used in the present invention is not particularly limited. As a specific example of such a thermoplastic resin,
For example, fluorine resins such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, and ethylene-tetrafluoroethylene copolymer; polyamides such as polyamide 6, polyamide 66 and polyamide 12; polyolefins such as polyethylene, polypropylene and polymethylpentene; polystyrene , Aromatic vinyl resins such as poly-α-methylstyrene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; chlorine resins such as vinyl chloride resins and polyvinylidene chloride; acrylic resins, ABS resins, ethylene-vinyl acetate copolymers,
Norbornene resin, polyacetal, polyetherimide, polycarbonate, polyvinyl acetate, polyvinyl alcohol and the like can be mentioned. The thermoplastic resin composition containing the photocatalyst composition of the present invention can maintain its effect for a long time because the thermoplastic resin as the base material is hardly decomposed by the photocatalytic function of the photocatalyst. In particular, when compounded with a chlorine-based resin such as a vinyl chloride resin having a property of being easily decomposed by a photocatalyst, the base material does not decompose for a long period of time, so that adverse effects such as generation of hydrogen chloride gas can be prevented.

To mix the photocatalyst composition with the thermoplastic resin, a tumbler mixer, a universal mixer, a Hobart mixer, a ribbon blender, a Henschel mixer, a Banbury mixer, a pressure kneader or the like may be used. The mixing ratio of the thermoplastic resin composition is, with respect to 100 parts by weight of the thermoplastic resin, the photocatalyst composition, usually,
It is 1 to 100 parts by weight, preferably 5 to 50 parts by weight.
If the amount of the photocatalyst composition is too small, the photocatalytic reaction of the resin molded article may be small. Conversely, if the amount of the photocatalyst composition is too large, the thermoplastic resin may be decomposed. When preparing the above resin composition, a heat stabilizer, a lubricant, an impact resistance enhancer, a plasticizer, an antistatic agent, which are usually compounded during resin processing,
It is preferable that a flame retardant, an antioxidant, an ultraviolet absorber, a pigment, a coupling agent, a fungicide and the like are also blended and mixed.

When a photocatalyst composition is blended with a thermoplastic resin, a masterbatch in which the photocatalyst composition is blended in advance with a small amount of the same kind of resin, and this may be blended with a large amount of resin may be employed. A method in which the composition is directly mixed with a large amount of resin may be adopted. A masterbatch is a resin composition which is sufficiently and uniformly dispersed and prepared in advance in a small amount of the same kind of resin as the resin to which the photocatalyst composition is to be applied. This enables uniform dispersion to be achieved even with simple mixing.

The thermoplastic resin composition containing the photocatalyst composition may be melt-kneaded with an extruder or the like to form pellets.
Further, when the thermoplastic resin composition is, for example, a vinyl chloride resin composition or an olefin-based resin composition, and the powder is processed, the thermoplastic resin composition needs to be in a powder form. The molding method of the thermoplastic resin composition containing the photocatalyst composition of the present invention is not particularly limited, and includes an extrusion molding method, a calender roll molding method, an injection molding method, a compression molding method, a vacuum molding method, a powder molding method, and the like. Can be molded.

The surface of a resin molded article using the photocatalyst composition of the present invention is particularly suitable as a light source because ultraviolet rays having a wavelength of 400 nm to 200 nm actively activate a photocatalytic reaction. Visible light and infrared light may be simultaneously irradiated in addition to ultraviolet light. Examples of the ultraviolet light source include sunlight, ultrahigh-pressure mercury lamp, xenon lamp, low-pressure mercury lamp, chemical lamp, laser, black light, germicidal lamp, LED, and fluorescent lamp.

The surface of a resin molded article using the photocatalyst composition of the present invention is exposed to ultraviolet rays and has the effect of causing various photocatalytic reactions such as stain prevention, sterilization, mold prevention, odor removal, harmful gas removal and freshness maintenance. Have. Specific usages include, for example, walls of houses and garages for prevention of dirt due to soot and the like in exhaust gas of automobiles; inner walls of hospitals for sterilization; ball-point pens and blowers for sterilization; Wall of bathroom for bathroom; inner wall of house for prevention of sick house syndrome caused by formalin etc .; inner wall of house for removal of malodorous substances such as ammonia, amine, methyl mercaptan, hydrogen sulfide, isovaleric acid; of _NO X, SO
Inner walls of parking lots and tunnels for removing harmful gases such as _X ; inner walls of vegetable stores for removing plant growth promoting substances such as ethylene and acetaldehyde to maintain freshness.

[0017]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, parts and% are based on weight. As a photocatalyst, anatase type titanium dioxide (A-1)
00, manufactured by Taki Chemical Co., Ltd., crystallite size: 8 nm). The test method was as follows. (1) Photocatalytic reaction test One sample piece was placed in a 1500 ml separable flask made of Pyrex (registered trademark), and a chemical lamp was placed above the flask while circulating the air at 3 liters / minute with an air pump. (FL10BL, manufactured by Toshiba Corporation) UV light intensity 1 mW / cm through quartz lid
Irradiate at ² . Ethylene is added to this system by a gas-tight syringe in such an amount that the initial concentration becomes 100 ppm, and the ethylene concentration which is decomposed and reduced by the photocatalyst is measured over time. The measurement of the ethylene concentration is based on a flame ionization detector (FID) type gas chromatography. The smaller the value, the greater the effect of the photocatalytic reaction.

(2) A light resistance test UV tester (SUV-W13, manufactured by Iwasaki Electric Co., Ltd.) was equipped with three test pieces of the same type, and was provided with a water-cooled metal halide lamp, a wavelength of 295 to 450 nm, and a UV intensity of 50 mW /
cm ² , temperature 50 ° C., and relative humidity 70%.
After 100 and 200 hours, one test piece is taken out, the surface state is observed, and the evaluation is made according to the following criteria. ：: No crack or chipping. Δ: Cracks or chips were slightly observed. ×: Cracks or chips are seen in more than half the area.

Example 1 Photocatalytic composition A was prepared by mixing anatase type titanium dioxide (A-100) and rutile type titanium dioxide (R-820, manufactured by Ishihara Sangyo Co., Ltd.) at a weight ratio of 1/9. did. Next, 100 parts of a vinyl chloride resin [ZEST 1000Z, manufactured by Shin-Daiichi PVC Co., Ltd., vinyl chloride homopolymer, average degree of polymerization 1050], 10 parts of the photocatalyst composition A, and tribasic lead sulfate / stearic acid A powdery mixture obtained by high-speed mixing of 3 parts of the lead composite heat stabilizer with a Henschel mixer is subjected to a biaxially different-direction extruder having a cylinder diameter of 40 mm.
Pellets were formed at a barrel temperature of 175 ° C. with a hot cut die of 3 mmφ × 60 holes to prepare a vinyl chloride resin composition A. Using the pellets of the obtained vinyl chloride resin composition A, a single screw extruder (L / D = 40 mm in cylinder diameter) was used.
24, compression ratio 2.5, 25 rpm, barrel temperature 170
C., a 1 mm thick × 45 mm wide belt die) was used to extrude a 45 mm wide, 1 mm thick, 500 mm long belt made of a hard vinyl chloride resin. From this, height 75m
Five test pieces of vinyl chloride resin having a length of 45 mm, a width of 45 mm and a thickness of 1 mm were prepared. Table 1 shows the results of a photocatalytic reaction test and a light resistance test of the obtained test piece under ultraviolet irradiation.

Comparative Example 1 In Example 1, a vinyl chloride resin was added to the photocatalyst composition A.
Anatase type titanium dioxide (A-100) 10
A vinyl chloride resin composition was prepared in the same manner as in Example 1 except that the parts were added. Immediately thereafter, the vinyl chloride resin began to decompose, and a test piece could not be prepared.

EXAMPLE 2 A powder of anatase type titanium dioxide (A-100) was calcined at a temperature of 1000 ° C. for 3 hours, and a photocatalyst composition in which the weight ratio of anatase type titanium dioxide / rutile type titanium dioxide was 13/87 was mixed. B was prepared. Next, using the photocatalyst composition B, a vinyl chloride resin composition B was prepared in the same manner as in Example 1, and a photocatalytic reaction test and a light resistance test were performed. The results are shown in Table 1.

Example 3 A pressure-resistant reactor equipped with a stirrer and a cooling jacket was charged with 80 parts of methyl methacrylate and n-butyl acrylate 2
0 parts, chain transfer agent t-dodecyl mercaptan 0.5 part,
0.1 part of the polymerization initiator lauroyl peroxide and 150 parts of methyl ethyl ketone are added, and the mixture is stirred at a temperature of 75 parts.
The polymerization reaction was carried out at ℃. The reaction was terminated by cooling at a polymerization conversion of 98%. Mw of the obtained acrylic resin is 75,
000 and Tg were 74 ° C. After the polymerization reaction was completed, 25 parts of the reaction solution was collected and put into a rotary evaporator, and methyl ethyl ketone was partially distilled off under reduced pressure at 50 ° C., and when the viscosity of the acrylic resin solution was 6500 mPa · s, For 100 parts of acrylic resin,
10 parts of the photocatalyst composition A prepared in Example 1 was added and uniformly mixed. This dispersion is made of stainless steel, 75 m long
m, 45 mm wide and 2 mm deep in a dish-shaped container at a temperature of 6
Dry under reduced pressure at 0 ° C, length 75mm, width 45mm, thickness 1m
m test pieces were obtained. Table 1 shows the results of a photocatalytic reaction test and a light fastness test performed on the obtained test pieces.

Comparative Example 2 In accordance with the description in JP-A-9-225319, silicon tetraethoxide was hydrolyzed on the surface of anatase-type titanium dioxide having water adsorbed on the surface of the particles, and the particles of inert ceramics were used as a photocatalyst. Photocatalyst particles (photocatalyst C) attached to the surface in an island shape were prepared. Next, the same operation as in Example 1 was performed to obtain a vinyl chloride resin composition C. Table 1 shows the results of the photocatalytic reaction test and the light resistance test performed on the test pieces prepared in the same manner as in Example 1.

[0024]

[Table 1]

The photocatalyst composition of the present invention can be easily prepared. As shown in Table 1, a thermoplastic resin composition using the photocatalyst composition has a low ethylene concentration under ultraviolet irradiation and a long-term The irradiated molded product surface is not damaged (Examples 1 to 3). On the other hand, in the case of the vinyl chloride resin composition containing only the anatase type titanium dioxide, the vinyl chloride resin was decomposed and a molded article was not obtained (Comparative Example 1). When photocatalyst particles in which inactive ceramics are attached to the particle surface in the form of islands are used as the photocatalyst, the vinyl chloride resin molded article has the same photocatalytic reaction activity as that of Example 1, but the surface shows a light resistance test. Deterioration was observed (Comparative Example 2).

[0026]

According to the present invention, there is provided a resin material having a photocatalytically active surface which is not deteriorated for a long time and has excellent photocatalytic reactivity, which is used for a wall surface of a building or the like.

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Claims (3)

[Claims] 1. A photocatalyst composition comprising a photocatalyst and an inorganic powder inert as a photocatalyst. 2. A thermoplastic resin composition obtained by blending the photocatalyst composition according to claim 1 with a thermoplastic resin. 3. A resin molded article comprising the thermoplastic resin composition according to claim 2.