JP2000129018A - Production of synthetic resin molding having photocatalysis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a synthetic resin molding having a more excellent photocatalysis by increasing the area of contact of photocatalyst particles with the external organic substances by subjecting a synthetic resin article to an operation of exposing the photocatalyst particles to the surface of the article. SOLUTION: There is provided a process for producing a synthetic resin molding having photocatalysis, which comprises the step of: producing a synthetic resin molding 3 containing photocatalyst 2 particles on at least the near the surface, and exposing at least part of the surfaces of the photocatalyst particles to the surface of the article by irradiating the surface of the article with light having a wavelength activating the photocatalyst to decompose the synthetic resin which covers the tops of the photocatalyst particles near the surface of the article.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic resin molded article having a photocatalytic function, and more particularly to a method for producing a synthetic resin molded article in which a photocatalytic function is remarkably enhanced by exposing photocatalytic particles on the surface. .

[0002]

2. Description of the Related Art A photocatalyst such as titanium dioxide (TiO ₂ ) having an anatase type crystal structure causes a photochemical reaction when irradiated with light such as ultraviolet rays, and acts as a catalyst for decomposing various organic substances. It is known that it has an action such as antibacterial or antifungal action.

[0003] The mechanism of the photocatalytic function of the photocatalyst such as anatase type titanium dioxide is as follows.
It is described as follows based on the electronic structure.

That is, when the photocatalyst is irradiated with light (photon) having energy equal to or larger than the band gap, electrons in the valence band are excited to the conduction band, and the valence band after the excitation of the electrons is positive in the valence band. Holes are formed (so-called “pair generation”), and the excited electrons in the conduction band react with oxygen in the air to form O ₂ ⁻ , O ₂
^And active oxygen species such as-, and holes in the valence band react with a small amount of water attached to the surface of the photocatalyst to generate OH radicals. Then, various organic substances are decomposed by the active oxygen species and OH radicals thus generated, and a function such as an antibacterial or antifungal action is obtained.

[0005] By utilizing the action of the photocatalyst, a technique for applying a photocatalyst such as anatase type titanium dioxide to water treatment, air cleaning, soil treatment, and the like has recently been put into practical use. As typical examples, for example, decomposition and removal of pollutants such as nitrogen oxides (NO _x ) in the atmosphere and offensive odors in a daily living space are being studied.

As an application example of such a technique, as disclosed in Japanese Patent Application No. 5-253544, it is made of building materials such as outer wall materials, tiles, bricks, plate glass, tiles, and other inorganic materials. Vacuum evaporation, sputtering, CVD (Chemical Vapor) is applied to the surface of the structure.
It is known that a film of the photocatalyst alone is formed by a method such as a deposition method or sintering of ultrafine particle sol. However, these methods require time,
It required labor and cost.

[0007]

Therefore, it is conceivable that a photocatalyst powder is immobilized on a surface of the above-mentioned various articles by using a synthetic resin binder to impart a photocatalytic function to the article. Was.

For example, Japanese Patent Application Laid-Open No. H10-156988 disclosed by the present applicant discloses a method in which a photocatalyst carrier in which a photocatalyst is supported in an inorganic transparent porous body is contained in a base resin and molded. Synthetic resin moldings and articles are described. This is to prevent the decomposition of the base resin by the photocatalyst by supporting the photocatalyst in the inorganic porous material, and to selectively photodecompose only the low-molecular-weight or fine-particle organic substances to be decomposed. It is like that.

However, the above synthetic resin molded article has an excellent selective photocatalytic function because the photocatalyst powder is supported on an inorganic transparent porous body.
During the production of the synthetic resin molded product, the photocatalyst carrier is buried in the resin binder, and is separated from substances such as odorous components (formaldehyde, ammonia, etc.) and dirt (tobacco tar, etc.) to be decomposed. In some cases, the function was not fully exhibited.

Therefore, the present invention relates to the above-mentioned JP-A-10-15 / 1990.
By improving the synthetic resin molded article having the photocatalytic function described in JP-A-6988, and performing an operation of exposing the photocatalyst particles on the surface of the synthetic resin article, the contact area between the photocatalyst particles and the external organic substance is increased, An object of the present invention is to provide a method for producing a synthetic resin molded article having an excellent photocatalytic action.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method for producing a synthetic resin molded article having a photocatalytic function, which comprises producing a synthetic resin molded article containing photocatalyst particles at least immediately below the surface. And irradiating the surface of the synthetic resin molded article with light having a wavelength for activating a photocatalyst, thereby decomposing the synthetic resin that covers just above the photocatalyst particles in the vicinity of the synthetic resin surface, thereby obtaining a surface of the photocatalyst particles. A method for producing a synthetic resin molded article having a photocatalytic function, comprising a step of exposing at least a part of the synthetic resin molded article surface.

In the method for producing a synthetic resin molded article having a photocatalytic function according to the present invention, the step of producing a synthetic resin molded article containing the photocatalyst particles at least immediately below the surface is preferably carried out in an inorganic transparent porous body. More preferably, it is a step of producing a synthetic resin molded article comprising a photocatalyst carrier carrying a photocatalyst at least immediately below the surface vicinity.

According to the present invention, a contact area between the photocatalyst particles and an external organic substance can be increased, and a synthetic resin molded article having an excellent selective photocatalytic function can be manufactured.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a synthetic resin molded article having a photocatalytic function according to the present invention will be described in detail.
As described above, the present invention provides (1) a step of producing a synthetic resin molded article containing photocatalyst particles at least immediately below the surface, and (2) activating a photocatalyst on the surface of the synthetic resin molded article. By irradiating light of a wavelength to decompose and remove the synthetic resin that covers just above the photocatalyst particles near the synthetic resin surface, at least a part of the photocatalyst particle surface is exposed to the surface of the synthetic resin molded product. Become.

(1) Step of Producing a Synthetic Resin Molded Article Containing Photocatalyst Particles at least Immediately Near the Surface The photocatalyst referred to in the present invention refers to all those generally called "photocatalysts". Is a substance that causes a photochemical reaction when irradiated with light of a specific wavelength, thereby acting as a catalyst for decomposing various organic substances and the like, and has a function such as an antibacterial or antifungal action.

Examples of the photocatalyst include aldehydes such as acetaldehyde and formaldehyde; mercaptans such as methyl mercaptan; sulfides such as hydrogen sulfide; amines such as ammonia and trimethylamine;
Toluene, causative ones and odor such as acetic acid, nitrogen oxides (NO _X) pollutants in the air such as oil dirt and mist, decomposition of such tobacco fat (tar), bactericidal action, antifungal The action and the like are known. In the present invention, all those which can be decomposed, disinfected and fungicidally by the action of the photocatalyst can be targeted. Among these, the synthetic resin molded article of the present invention exerts a particularly great effect on gases and low molecular weight organic substances.

Examples of the photocatalyst include titanium dioxide (TiO ₂ ), zinc oxide (ZnO) and cerium oxide (CeO) having an anatase type crystal structure.

Among the above, according to the present invention, 1) high catalytic activity is obtained even in sunlight or illumination light required for daily life, and no special light source is required; 2) it is chemically stable. Anatase-type titanium dioxide is particularly preferably used because it has high photocatalytic activity for a long time, 3) has no toxicity, and 4) is inexpensive and advantageous in cost. In addition, in the crystal system of titanium dioxide, anatase type and rutile type which are excellent in photocatalytic activity are known, but titanium dioxide used in the present invention exhibits a photocatalytic function that all have an anatase type crystal structure. Although preferred above, it may be one having a rutile crystal structure in part.

Further, in the present invention, if necessary, a spectral sensitizer can be added in order to shift the upper limit of the photosensitive wavelength for expressing the photocatalytic activity of the anatase type titanium dioxide to the longer wavelength side. . Examples of such a sensitizer include Ru (4,4′-dicarboxyl-2,
Ruthenium complexes such as 2′-pyridine) ₂ (NCS) ₂ .

The photocatalyst particles used in the present invention can be used alone in a resin or used in the form of a photocatalyst carrier in which the photocatalyst particles are carried on a carrier such as an inorganic transparent porous body. Can also. The preferable content of the photocatalyst particles is about 10 to 100 parts by weight based on 100 parts by weight of the resin.

When the photocatalyst particles are used alone,
The photocatalyst particles are uniformly dispersed and used in the resin without causing separation and sedimentation. By uniformly dispersing and containing the particles, a film-forming sheet can be obtained in which the photocatalyst particles are dispersed uniformly, that is, also in the vicinity of the surface.

When the photocatalyst particles are carried, the specific form of the photocatalyst carrier carrying the photocatalyst particles is not particularly limited, but is preferably carried on an inorganic transparent porous body. When used as a carrier in which photocatalyst particles are carried in an inorganic transparent porous body, it is possible to effectively prevent the resin present below the photocatalyst carrier from being decomposed due to contact with the photocatalyst. It is.

The photocatalyst inherently has a function of decomposing organic substances, but at the time of producing a synthetic resin molded product, the resin behaves as an aggregate due to the cohesive force acting between the resin molecules. Further, the affinity between the organic resin and the inorganic transparent porous body is poor, and air may enter inside the pores of the photocatalyst particle carrier or between the photocatalyst particle carrier and the resin. It is hard to penetrate inside the pores of the transparent porous body. If no photocatalyst particles are present, no decomposition of the resin occurs.

Furthermore, even if the photocatalyst particles are present inside the pores and the resin enters into the pores and the resin is decomposed, the decomposition is only locally decomposed, and the effect of the photocatalyst particles does not affect the whole. Absent.

On the other hand, most of the above-mentioned decomposed substances are usually low molecules and are diffused in air in a molecular state. Therefore, the substances easily enter the pores of the inorganic transparent porous material by a diffusion phenomenon. Decomposed selectively upon contact with photocatalyst.

The inorganic transparent porous body supporting the photocatalyst is
Depending on the combination with the photocatalyst to be supported, a material that has transparency to light having a wavelength at which the catalytic activity of the photocatalyst can be obtained and can transmit such light can be appropriately selected.

For example, when anatase type titanium dioxide particles are used as the photocatalyst particles, the anatase type titanium dioxide particles can obtain photocatalytic activity with ultraviolet light having a wavelength of 380 nm or less. Those that transmit ultraviolet light are preferred. However, when the above-mentioned spectral sensitizer is added, it is preferable to select a material which is transparent to a wavelength which is not more than the upper limit (absorption width) of the shifted photosensitive wavelength.

Specific examples of the inorganic transparent porous material include zeolite, silica gel, silica alumina, cement, tricalcium silicate, calcium silicate,
Examples thereof include porous glass, aluminum hydroxide, and magnesium carbonate. Among these, it is preferable to use silica gel or zeolite in view of the characteristics of supporting the photocatalyst and the adsorptivity of products decomposed by the photocatalyst.

In this case, it is more preferable that the photocatalyst particles are supported on a porous body so as to have an average particle diameter of 1 to 200 μm and a specific surface area of 10 to 300 m ² / g.

In order to obtain a sufficient photocatalytic activity, it is particularly preferable to support 10 to 900 parts by weight of photocatalyst particles per 100 parts by weight of the inorganic transparent porous material. Further, in order to impart an antibacterial effect to the photocatalyst carrier, Ag ions or the like can be adsorbed or carried on the carrier, or copper ions can be added to reinforce the photocatalytic function.

FIG. 2 shows an example of the photocatalyst carrier 4 in the present invention.
Shown in For example, the carrier 4 has a) a photocatalyst 7 supported at an arbitrary position in the hole 6 of the massive inorganic transparent porous body 5 (FIG. 2A), and b) an inorganic transparent porous body. 5 is formed in a hollow shape, and a photocatalyst 7 is supported on the hollow wall surface (FIG. 2 (b)). C) Arbitrary portions in the holes 6 of the inorganic transparent porous body 5 having a hollow inside. One in which a photocatalyst 7 is supported in place and a porous body 8 of the same or different type as the porous body 5 is filled in the hollow portion (FIG. 2 (c)).

In order to prevent the base resin from entering the pores 6 of the inorganic transparent porous body 5 and to allow the decomposition target to enter and selectively decompose the inorganic resin, the inorganic transparent porous body 5 is required. The diameter r of the pores 6 appearing on the surface of the transparent porous body 5 is 10 nm to 10 μm, and the specific surface area of the inorganic transparent porous body 5 is 10 to 100 m ² / g.
It is preferred that In addition, the inorganic transparent porous body 5 includes:
It is preferable to use one having an average particle size of 1 to 100 μm.

The resin which can be used in the method for producing a synthetic resin molded article having a photocatalytic function according to the present invention contains photocatalyst particles or a photocatalyst carrier at a predetermined ratio and has a wavelength which activates the photocatalyst. There is no particular limitation as long as it can be decomposed by the action of the photocatalyst by irradiation.

Examples of such resins include polyolefin resins, acrylic resins, urethane resins, polyester resins, polystyrene, vinyl chloride resins, vinylidene chloride resins, vinyl acetate resins, polyamide resins, epoxy resins, and fluorine resins. Can be. Among these, the use of an acrylic resin, a polyolefin-based resin, or a urethane resin is particularly preferred in terms of moldability, processability, compatibility with photocatalyst particles or a photocatalyst carrier, and the like.

As the polyolefin resin, for example,
Homopolymers consisting only of ethylenically unsaturated monomers such as polyethylene and polypropylene, ethylene-propylene copolymers, copolymers of ethylenically unsaturated monomers such as ethylene-propylene-butene copolymers, ethylene -Binary or tertiary of an ethylenically unsaturated monomer such as vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer and a monomer polymerizable therewith.
And the like.

Examples of the acrylic resin include poly (methyl meth) acrylate, ethyl poly (meth) acrylate, propyl poly (meth) acrylate, butyl poly (meth) acrylate, methyl (meth) acrylate- ( Meta)
Butyl acrylate copolymer, methyl (meth) acrylate-butyl (meth) acrylate- (meth) acrylic acid 2-
Homo- or copolymers of alkyl (meth) acrylates, such as hydroxyethyl copolymers, methyl (meth) acrylate-styrene copolymers, or alkyl (meth) acrylates and other monomers One or a mixture of two or more such as a copolymer with a polymer can be exemplified. In addition, the above-mentioned poly (methyl methacrylate) etc. is used in the meaning of polymethyl acrylate or polymethyl methacrylate.

The urethane resin is a resin obtained by causing polyaddition polymerization of an isocyanate and a polyol, and is roughly classified into a one-part curing type (moisture curing type) and a two-part curing type. Any of these can be used in the present invention. The one-component curable urethane resin is made of a polyfunctional isocyanate prepolymer having a urethane skeleton, a polycarbonate skeleton, or the like, absorbs water (humidity) in the air or the like, and reacts with the water to form polyurethane. In addition, the two-component curable urethane resin is a material in which a polyfunctional polyol and a polyfunctional isocyanate react to form a polyurethane. As the polyol, acrylic polyol, polyester polyol, polycarbonate polyol, polyether polyol, or the like may be used. it can.

Examples of the isocyanate include aromatic isocyanates such as 2,4-tolylene diisocyanate and 4,4 diphenylmethane diisodianate, and aliphatic (or alicyclic) such as isophorone diisocyanate and 1,6-hexamethylene disissocyanate. Formula) Isocyanates, or adducts or multiples thereof can be used.

In order to obtain a resin molded product in which at least a part of the photocatalyst particles is distributed immediately below the surface, a resin composition containing the photocatalyst particles or the photocatalyst carrier is applied to the surface of the substrate and dried. A method of forming a resin layer containing photocatalyst particles or a photocatalyst carrier on the surface of a base material by applying a heat treatment as desired, forming the above resin composition containing the photocatalyst particles or the photocatalyst carrier into a film shape. ,
There is a method of obtaining a resin sheet containing photocatalyst particles or a photocatalyst carrier by stretching. In this case, the resin composition can be used in the form of a heated melt, an organic solvent solution, or an emulsion.

More specifically, the above-mentioned method is a method in which the photocatalyst particles or the photocatalyst carrier in which the photocatalyst particles are carried on an inorganic transparent porous material are dissolved in an organic solvent solution of a resin composition or an aqueous (water-dispersed) emulsion or the like. By coating the resin composition on the surface of an article to be provided with a photocatalytic function by a known coating method such as gravure coating, roll coating, spray coating, flow coating, and comma coating, a resin layer having a photocatalytic function is formed. To form. In this case, the resin layer is preferably a porous layer. For that,
For example, a thermally decomposable foaming agent such as azodicarbonamide may be added to the resin layer for foaming by heating, or the resin layer may be stretched. The thickness of the resin layer is 20 to 2 from the viewpoints of ensuring a sufficient photocatalytic function and processability of a molded product.
It is preferably about 00 μm.

In addition, the above-mentioned method comprises the steps of using a photocatalyst particle or a resin composition obtained by dispersing a photocatalyst carrier in which a photocatalyst particle is supported on an inorganic transparent porous material in a resin by an inflation method, a calender method, an extrusion method or the like. A resin sheet (resin layer) containing photocatalyst particles or a photocatalyst carrier is obtained by forming a film by a conventionally known method. In this case, it is also preferable that the obtained resin sheet is further stretched to generate shear stress at the interface between the photocatalyst particles and the resin to make the resin sheet porous. The stretching ratio is 1.5
It is preferably from about 3.0 to about 3.0 times from the viewpoint of securing the content of the photocatalyst particles per unit volume, not causing stretching unevenness, and the like. The stretching may be either uniaxial stretching or biaxial stretching. The thickness of the obtained porous sheet is usually preferably about 50 to 500 μm.

Then, the resin layer (sheet) itself is left as it is, or the resin layer and the base material are laminated by heat-sealing or an adhesive layer to form a synthetic layer which can be used in the present invention. A resin molded product can be obtained. Examples of the resin that can be used as the adhesive include a urethane resin, a polyester resin, a polyamide resin,
Examples thereof include vinyl acetate-acrylate resins, carboxyl group-containing acrylic resin resins, vinyl acetate-ethylene resins, and polyvinyl resins.

As a synthetic resin molded product before light irradiation obtained as described above, a single-layered product as shown in FIG. 3A or a base material 3 as shown in FIG. Examples thereof include those laminated on the top, and those formed into a film, a sheet, or a plate, or those laminated with another base material may be used.

In preparing a synthetic resin molded article composed of a single synthetic resin layer, as shown in FIG. 4, the photocatalyst particles or the photocatalyst carrier 2 are dispersed on a releasable support sheet 9. After the formed resin layer (sheet) 1 is formed (or laminated), the support sheet 9 is peeled off, so that a synthetic resin molded article composed of a single resin layer can be manufactured. As the support sheet, a coated paper in which a polyolefin resin such as polyethylene or polymethylpentene or a silicone resin is laminated as a release layer, a biaxially stretched polyethylene terephthalate sheet, or the like can be used.

Examples of the base material constituting the synthetic resin molded product include synthetic resins such as polyvinyl chloride, polyester, polyolefin, phenol resin, polycarbonate, acrylic resin, ABS resin, and polystyrene, as well as iron, aluminum, Non-ceramic ceramic materials such as metals such as copper, glass, ceramics such as ceramics, gypsum, calcium silicate, and cement; plywood, veneer, fiberboard, and particle board made of various trees such as cedar, pine, oak, teak, and lauan Wood material etc. The shape of the above-mentioned base material is arbitrary, such as a sheet, a plate, and a three-dimensional shape.

Papers such as Japanese paper, high-quality paper, and backing paper for wallpaper;
Woven or non-woven fabric made of fibers such as glass fiber, carbon fiber, polyester fiber, and vinylon fiber. The above substrate is
Exclusively, its shape is used as a sheet.

In the synthetic resin molded article of the present invention,
As long as the photocatalytic function is not impaired, pattern printing or embossing of an uneven pattern can be performed.

The resin layer containing the photocatalyst particles or the photocatalyst carrier of the synthetic resin molded article may contain various additives as long as the photocatalytic function is not impaired.

As an example of the additive, ITO (Inziu)
m Tin Oxide) An antistatic agent such as powder or scale, and a surfactant such as polyoxyethylene amine, polyoxyethylene alkyl phosphate, sorbitan fatty acid ester, and alkyl alkanolamine. In particular, it is preferable to add an antistatic agent because it can provide an effect of preventing contaminants such as oil stains from adhering. The amount of the additive is usually 0.5 to
It is about 5% by weight.

Alternatively, in order to reinforce the function of the photocatalyst, a catalyst other than the photocatalyst, an antibacterial agent and an antifungal agent may be added. Examples of the catalyst other than the photocatalyst include iron oxide, copper oxide, and zinc oxide. These catalysts are particularly effective in taking over at least part of the function of the photocatalyst in an environment where no light is present, such as at night.

As an antibacterial agent, zeolite carrying silver ions in an ion-exchangeable manner, and as an antifungal agent, 1
0,10'-oxybisphenoxyarsine and the like are typical.

Alternatively, in order to further improve the weather resistance (light), a hindered amine radical scavenger such as bis- (2,2,6,6-tetramethyl-4-piperidinyl) sebacate is used in an amount of 0.1 to 5% by weight. It may be added to some extent.

(2) By irradiating the surface of the synthetic resin molded article with light having a wavelength for activating a photocatalyst, the synthetic resin covering just above the photocatalyst particles near the surface of the synthetic resin is decomposed and removed. Exposing at least a part of the surface of the photocatalyst particles to the surface of the synthetic resin molded product.

The next step is a step of irradiating the surface of the obtained resin sheet with light having a wavelength for activating the photocatalyst to photodecompose and remove the photocatalyst particles or the resin immediately above the photocatalyst carrier. In order for a photocatalyst to exhibit a photolytic action, it is necessary to activate the photocatalyst first. For example, in titanium dioxide (TiO ₂ ) having an anatase type crystal structure, about 38
Light having a wavelength of 0 nm or less is required. It is also known that when a ruthenium catalyst as described above is used in combination, the wavelength shifts to the longer wavelength side (about 450 nm). Therefore, in order to increase the production efficiency of the synthetic resin molded product, it is necessary to select the wavelength of the light to be applied depending on the photocatalyst system used.

The time for irradiating the photocatalyst with light having a wavelength for activating the photocatalyst is such that the resin immediately above the photocatalyst particles (or the photocatalyst carrier) is decomposed by the action of the photocatalyst existing in the vicinity of the surface of the resin molded article, and the photocatalyst particles (or It is sufficient that the time is sufficient to expose the photocatalyst carrier) to the resin surface. on the other hand,
If the irradiation time is too long, the deterioration of the resin may progress not only on the surface but also on the lower part. Therefore, it depends on the type of resin used, the illuminance, the content of the photocatalyst, and the like, and needs to be freely designed and changed. For example, in the case of ultraviolet light output from a high pressure mercury lamp, the illuminance is 80
At W / cm ^2, it is preferably about 10 to 90 seconds.

Light sources that can be used in the light irradiation step include, for example, an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a black light lamp (fluorescent lamp), a xenon lamp, an excimer laser, a nitrogen laser, a carbon arc lamp, and hydrogen. Discharge tubes and the like can be mentioned.

FIG. 5 is a sectional view showing a step of light irradiation. That is,
As described above, a synthetic resin molded article made of a resin containing photocatalyst particles (or a photocatalyst carrier) at least in the vicinity of the surface is prepared (for example, the one shown in FIG. 5A). As shown in (1), the surface resin layer 1 containing the photocatalyst particles (or the photocatalyst carrier) is irradiated with ultraviolet light (or near ultraviolet light) containing light having a wavelength for activating the photocatalyst at a predetermined illuminance for a predetermined time. . By this irradiation treatment, the resin immediately above the photocatalyst existing near the surface of the surface resin layer 1 is photodecomposed and removed, and the photocatalyst particles 2 (or the photocatalyst carrier 4) as shown in FIG. Thus, a synthetic resin molded product exposed to the substrate can be obtained.

The synthetic resin molded article having a photocatalytic function which can be produced as described above is shown in FIG.
In addition to those shown in (b), those formed into a film, a sheet, or a plate, or those further laminated with another base material may be used. In addition, various three-dimensional shapes such as window frames (sashes), handrails, doors, door frames, wall boards, ceiling panels, flooring materials, wall materials, window glass, partitioning and other interior and exterior materials required for construction, dining tables, chests, drawers Furniture, sinks, etc.
Housing equipment such as ventilation fans, ventilation ducts, wash basins, bathtubs, etc., vehicles such as light reflectors, light boards, gloves, CRT (CRT) surfaces, cabinets for weak electric / OA equipment such as television receivers, keyboards, etc. It may be formed into a specific product form such as an interior material or the like, and its specific shape does not matter.

[0059]

Next, the present invention will be described in detail with reference to examples. The following embodiments are merely examples of the embodiments of the present invention, and can be freely designed and changed without departing from the gist of the present invention.

Example First, 40 parts by weight of anatase-type titanium dioxide particles were supported on 100 parts by weight of silica gel to obtain a photocatalyst carrier 4 having an average particle size of 5 μm. Next, 50 parts by weight of the photocatalyst carrier is added to 100 parts by weight of a solid content of urethane resin-based binder 1 (100 parts by weight of acrylic polyol and 6 parts by weight of 1,6-hexamethylene diisocyanate) decomposable by the photocatalyst. A coating composition was prepared by allowing the coating composition to be contained. Then, this is coated with a 100 μm-thick biaxially stretched polyethylene terephthalate (PET) substrate 3 by a gravure coating method.
As shown in FIG. 5 (a), a sheet-like synthetic resin molded product having a surface resin layer having a thickness of 12 μm formed by coating on the surface was obtained.

Next, the surface of the obtained sheet on the surface resin layer side was irradiated with ultraviolet light having an illuminance of 80 W / cm ² for 45 seconds using a high-pressure mercury lamp (manufactured by I-Graphics Co., Ltd.). By forcibly decomposing and removing the resin covering the photocatalyst carrier of the layer, a sheet (synthetic resin molded product) having the same layer structure as shown in FIG. 1B was obtained. A sample piece having an area of 15 cm ² was cut out from the obtained sheet to obtain a photocatalytic activity evaluation sample described later.

[0062] The same photocatalyst carrier to that used in Comparative Example Example, by incorporating 50 parts by weight with respect to the photocatalyst by decomposed hardly fluororesin binder (polyvinylidene fluoride) 100 parts by weight of the solid content, the coating A working composition was prepared. Then
This was gravure-coated to a thickness of 100 μm.
Was coated on the surface of the biaxially stretched polyethylene terephthalate (PET) base material to obtain a sheet-like synthetic resin molded article having a surface resin layer having a thickness of 12 μm as shown in FIG.

Next, the obtained sheet is irradiated with ultraviolet rays.
15cm from the sheet ^TwoSize sump
Cut off a piece of the catalyst,
did.

Photocatalytic Activity Evaluation Test 1 The following photocatalytic activity evaluation tests were performed using the evaluation test sample pieces obtained in Examples and Comparative Examples. That is, a high-pressure mercury lamp (manufactured by I-Graphics Co., Ltd.) was used on the surface of the sample piece obtained in the above example, and an ultraviolet light having an illuminance of 80 W / cm ² was used. UV light including spectrum, 0, 10, 3
Samples irradiated in six stages for 0, 50, 70, and 90 seconds were prepared, and the same amount of tobacco fat was applied to the entire surface of the sample piece at each stage, and again irradiated with the same ultraviolet rays as described above. The change with time of the color difference (ΔE value) accompanying the decomposition of the fat was measured. The color difference (ΔE value) is a value based on the color of each sample before the application of fat, measured with a spectrophotometer, and evaluated by the Hunter's Lab formula. The measurement results are shown in Table 1 and FIG. The closer the color difference (ΔE) is to 0 at the same irradiation time, the more active the photocatalytic function is determined.

[0065]

[Table 1]

As shown in Table 1 and FIG. 6, the illuminance 80 W /
At cm ² , the time required to activate the photocatalyst was found to be saturated at about 90 seconds.

Evaluation Test of Deterioration of Coating Film by Photocatalyst A high-pressure mercury lamp (manufactured by I-Graphics Co., Ltd.) was used on the surface of the sample obtained in the comparative example (ie, one not irradiated with ultraviolet rays) on the surface resin layer side. UV light having an illuminance of 80 W / cm ² was irradiated for a predetermined time, and the degree of deterioration of the fluororesin covering the photocatalyst carrier of the surface resin layer was measured over time. The degree of deterioration of the binder resin was represented by a color difference (ΔE value), and the color difference (ΔE value) was measured by a spectrophotometer and evaluated by Hunter's Lab formula. Table 2 shows the measurement results.

[0068]

[Table 2]

From Table 2, it was found that the preferable irradiation time at an illuminance of 80 W / cm ² was 10 to 90 seconds.

Photocatalytic activity evaluation test 2 The surfaces (entire surfaces) of the sample pieces obtained in the above Examples and Comparative Examples
The same amount of tobacco fat (dust) is attached to each of them, and the illuminance is 80 W using a high pressure mercury lamp (manufactured by Eye Graphics Co., Ltd.)
/ Using the ultraviolet surface of cm ² light sources consisting of a low-pressure mercury lamp, ultraviolet rays comprising a spectral wavelength 380 nm 30
Irradiation for 10 hours, and the color difference (ΔE
Value) was measured. The color difference (ΔE value) was measured by a spectrophotometer, and evaluated by Hunter's Lab formula. The results are shown in Table 3 and FIG.

[0071]

[Table 3]

In Table 3 and FIG. 7, the color difference (ΔE value)
It shows that the smaller the is, the more efficiently the tobacco fat is decomposed. From Table 3 and FIG. 7, it was found that the synthetic resin molded product of the example had an excellent photocatalytic function as compared with that of the comparative example.

[0073]

As described above, according to the method for producing a synthetic resin molded article having a photocatalytic function of the present invention, a synthetic resin molded article having an excellent photocatalytic function can be obtained simply and with high yield. Can be.

[Brief description of the drawings]

FIG. 1 is a structural cross-sectional view of a synthetic resin molded article having a photocatalytic function obtained by the production method of the present invention. (A) is an example of a synthetic resin molded article composed of a single layer, and (b) is an example of a synthetic resin molded article composed of a porous layer containing a substrate and a photocatalyst.

FIG. 2 is a view conceptually showing an example of a photocatalyst carrier in which a photocatalyst is carried on an inorganic transparent porous body.

FIG. 3 is an example of a synthetic resin molded product that can be used in the production method of the present invention.

FIG. 4 is a cross-sectional view showing main steps of a production example of a synthetic resin molded product that can be used in the production method of the present invention using a releasable support sheet.

FIG. 5 is a view showing a light irradiation step of the manufacturing method of the present invention.

FIG. 6 is a diagram showing the results of a photocatalytic UV coating film deterioration evaluation test. The vertical axis represents the change in the ΔE value, and the horizontal axis represents the irradiation time (second).

FIG. 7 is a view showing test results of a photocatalytic activity evaluation test (cigarette fat decomposition test). The vertical axis represents the change in the ΔE value, and the horizontal axis represents the elapsed time.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... resin binder, 2 ... photocatalyst, 3 ... base material, 4 ... photocatalyst carrier, 5 ... inorganic transparent porous body, 6 ... hole, 7 ... photocatalyst, 8 ... other inorganic transparent porous body, 9 ... support Sheet

Claims (2)

[Claims] 1. A method for producing a synthetic resin molded article having a photocatalytic function, comprising the steps of: producing a synthetic resin molded article containing photocatalyst particles at least immediately below the surface; and applying a photocatalyst to the surface of the synthetic resin molded article. A step of exposing at least a part of the surface of the photocatalyst particles to the surface of the synthetic resin molded article by irradiating light having a wavelength to be activated to decompose the synthetic resin covering the photocatalyst particles immediately above the surface of the synthetic resin. A method for producing a synthetic resin molded article having a photocatalytic function, comprising: 2. The step of producing a synthetic resin molded article containing the photocatalyst particles at least immediately below the surface is characterized by comprising a photocatalyst carrier having a photocatalyst supported in an inorganic transparent porous body at least immediately below the surface. The method for producing a synthetic resin molded article having a photocatalytic function according to claim 1, which is a step of producing a synthetic resin molded article comprising: