JP2009221362A - Photocatalyst coating film and photocatalyst composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalyst coating film sufficiently excellent in durability of a substrate and/or coating while holding the decomposition activity (photocatalyst activity) and/or hydrophilicity of an organic substance at a high level by a photocatalyst immobilized on the surface of the substrate. <P>SOLUTION: The photocatalyst film comprises a rutile type titanium dioxide and a compound showing high photocatalyst ability. The content of the rutile type titanium dioxide satisfies the conditions represented by the following formula (1): 4/X≤a≤100/X, wherein X represents the thickness (unit: μm) of the photocatalyst coating film; and a represents the content (unit: % by mass) of the rutile type titanium dioxide to the total amount of the photocatalyst coating film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photocatalyst coating film and a photocatalyst composition.

  The photocatalyst refers to a substance that causes a reaction (for example, oxidation or reduction reaction) of another substance to proceed by light irradiation. In other words, when light (excitation light) having energy larger than the energy gap between the conduction band and the valence band (ie, short wavelength) is irradiated, excitation of electrons in the valence band (photoexcitation) occurs. Thus, it is a substance that can generate conduction electrons and holes. At this time, various chemical reactions can be performed using the reducing power of electrons generated in the conduction band and / or the oxidizing power of holes generated in the valence band.

  The photocatalytic activity refers to an activity that causes an oxidation or reduction reaction to proceed by light irradiation. It is known that a photocatalyst exhibits a photocatalytic activity and exhibits an organic substance decomposing action and a surface hydrophilizing action. Based on this action, the photocatalyst is applied to fields such as environmental purification, antifouling, and antifogging. For example, Patent Document 1 proposes an outdoor display panel that includes a surface layer portion containing photocatalyst particles and has a surface that is self-cleaned by rain (self-cleaning), and a cleaning method therefor. According to Patent Document 1, by providing a surface layer containing a photocatalyst, the surface of the surface layer portion exhibits hydrophilicity according to photoexcitation of the photocatalyst. Therefore, when the surface of the outdoor display panel is exposed to rain, the deposited deposits and / or contaminants can be washed away by raindrops.

  By the way, when the photocatalyst is applied to fields such as environmental purification, antifouling, and antifogging, the technology for immobilizing the photocatalyst on the substrate plays a very important role. In this immobilization technique, it is necessary to (a) firmly fix the photocatalytic activity to the substrate without impairing the photocatalytic activity, and (b) provide stability that does not deteriorate the substrate and its coating by the photocatalytic action.

In order to fix the photocatalyst satisfying such a need, a method has been proposed in which a protective layer is interposed between the substrate and the surface layer portion containing the photocatalyst provided thereon. For example, in Patent Document 2, a multilayer in which a vapor deposition layer made of silicon oxide or aluminum oxide having a predetermined thickness is provided on one surface of a base film and a photocatalytic layer mainly composed of titanium oxide is provided thereon. Photocatalytic films have been proposed. Alternatively, Patent Document 3 proposes a method in which a photocatalyst is mixed in a resin paint and the resin paint is coated on a substrate. Furthermore, as disclosed in Patent Document 4, for example, a method of supporting an inorganic substance that is difficult to decompose with a photocatalyst on the surface of the photocatalyst particle has been proposed.
Japanese Patent Laid-Open No. 9-230810 Japanese Patent Laid-Open No. 11-348172 JP 2002-154915 A JP 2005-170687 A

  However, the method proposed in Patent Document 2 has a drawback that the workability is inferior because the number of coating steps increases. Further, in the method of mixing a photocatalyst in a resin paint and coating the resin paint on a substrate, it is necessary to reduce the amount of the resin paint used in order to exhibit sufficient photocatalytic activity and / or hydrophilicity. This has the disadvantage that the durability of the substrate, the hardness of the coating, and the adhesion are not sufficient. On the other hand, when the amount of the resin coating used is increased, the photocatalytic activity and / or hydrophilicity becomes insufficient. Furthermore, in the methods described in Patent Documents 3 and 4, deterioration of the substrate and the coating cannot be suppressed if the amount of the inorganic substance supported or the amount of the resin coating is small, and if they are large, the photocatalytic activity and the hydrophilicity are also reduced. It will be. Therefore, it is very difficult to form a photocatalyst layer on the substrate that can maintain the decomposition activity (photocatalytic activity) and / or hydrophilicity of the organic substance by the photocatalyst at a high level and can also suppress the deterioration of the substrate and the coating. .

  Moreover, most of the paints used in these conventional techniques employ organic solvents, and there is room for improvement in terms of toxicity, environmental pollution, and flammability due to volatilization of organic solvents. Further, from the viewpoint of solvent resistance, there is room for studying the use of a substrate made of a resin or a substrate on which an organic film is formed.

  The present invention has been made in view of the above circumstances, and the durability of the substrate and / or coating is maintained while maintaining a high level of decomposition activity (photocatalytic activity) and / or hydrophilicity of organic substances by the photocatalyst immobilized on the surface of the substrate. An object of the present invention is to provide a photocatalyst coating film that is sufficiently excellent in properties and a photocatalyst composition that can form the photocatalyst coating film.

  As a result of intensive studies to achieve the above object, the present inventors have completed the present invention. That is, the present invention is as follows.

(1) A photocatalytic coating film comprising rutile titanium oxide and a compound exhibiting high photocatalytic activity, wherein the content ratio of the rutile titanium oxide satisfies the condition represented by the following formula (1).
4 / X ≦ a ≦ 100 / X (1)
Here, in the formula (1), X represents the film thickness (unit: μm) of the photocatalyst coating film, and a represents the content ratio (unit: mass%) of the rutile titanium oxide with respect to the total amount of the photocatalyst coating film. Show.
(2) The photocatalytic coating film according to (1), wherein a content ratio of the rutile-type titanium oxide satisfies a condition represented by the following formula (1a).
4 / X ≦ a ≦ 60 / X (1a)
Here, in the formula (1), X represents the film thickness (unit: μm) of the photocatalyst coating film, and a represents the content ratio (unit: mass%) of the rutile titanium oxide with respect to the total amount of the photocatalyst coating film. Show.
(3) The photocatalytic coating film according to (1) or (2), wherein a mass ratio of the compound exhibiting high photocatalytic activity to the rutile-type titanium oxide is 0.10 to 2.0.
(4) The photocatalytic coating film according to any one of (1) to (3), wherein the rutile-type titanium oxide and the compound exhibiting high photocatalytic activity both have a primary particle diameter of 100 nm or less.
(5) The photocatalyst coating film as described in any one of Claims 1-4 whose compound which shows the said high photocatalytic ability is anatase type titanium oxide.
(6) The photocatalyst coating film according to any one of (1) to (5), comprising an aqueous binder.
The photocatalyst composition used in order to form any one photocatalyst coating film of (1)-(6).

  According to the present invention, there is provided a photocatalyst coating film that is sufficiently excellent in durability of the substrate and / or coating while maintaining the decomposition activity (photocatalytic activity) and / or hydrophilicity of the organic substance by the photocatalyst immobilized on the substrate surface at a high level. can do.

  Hereinafter, the best mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail.

  The photocatalyst coating film of this embodiment is a photocatalyst coating film containing a compound showing rutile type titanium oxide and high photocatalytic activity, and the content ratio of the rutile type titanium oxide satisfies the condition represented by the above formula (1). Is. Here, the “photocatalyst” means that an electron in the valence band is irradiated with light (excitation light) having energy (ie, short wavelength) larger than the energy gap between the conduction band and the valence band. A substance that can generate conduction electrons and holes when excitation (photoexcitation) occurs. “High photocatalytic activity” refers to the decomposition activity of organic substances based on a photocatalyst per unit mass rather than rutile titanium oxide.

  A compound exhibiting a high photocatalytic ability can exhibit a high antifouling property, and the antifouling property is particularly excellent on the surface of the photocatalyst coating film. On the other hand, rutile-type titanium oxide exhibits high ultraviolet absorbing ability although it has low activity as a photocatalyst. Therefore, the photocatalytic coating film of this embodiment can reduce the amount of ultraviolet rays reaching the substrate by containing both of them, and can suppress the photocatalytic activity of a compound having a high photocatalytic ability existing in the vicinity of the substrate. It becomes. As a result, the photocatalyst of this embodiment can exhibit both excellent weather resistance and antifouling properties.

Examples of the compound exhibiting high photocatalytic activity include anatase type titanium oxide (TiO ₂ ), brookite type titanium oxide (TiO ₂ ), ZnO, SrTiO ₃ , CdS, GaP, InP, GaAs, BaTiO ₃ , BaTiO ₄ , BaTi _4. O ₉ , K ₂ NbO ₃ , Nb ₂ O ₅ , Fe ₂ O ₃ , Ta ₂ O ₅ , K ₃ Ta ₃ Si ₂ O ₃ , WO ₃ , SnO ₂ , Bi ₂ O ₃ , BiVO ₄ , NiO, Cu _{2 O, SiC, MoS 2, InPb} , RuO 2, CeO 2 and the like. Moreover, as a compound which shows high photocatalytic ability, the layered oxide which has 1 or more types of elements chosen from the group which consists of Ti, Nb, Ta, and V is mentioned, for example. Such layered oxides are disclosed in JP-A-62-274452, JP-A-2-172535, JP-A-7-24329, JP-A-8-89799, JP-A-8-89800, JP-A-8. -89804, JP-A-8-198061, JP-A-9-248465, JP-A-10-99694, and JP-A-10-244165. In addition, these photocatalysts were coated with a metal typified by Pt, Rh, Ru, Nb, Cu, Sn, Ni, Fe and / or an oxide of a metal, or porous calcium phosphate. A photocatalyst (for example, one described in JP-A-11-267519) may also be used as a compound exhibiting high photocatalytic activity according to this embodiment.

  In addition, a visible light responsive photocatalyst that can exhibit photocatalytic activity and / or hydrophilicity by irradiation with visible light (for example, having a wavelength of about 400 to 800 nm) may be used as the compound exhibiting high photocatalytic activity. . When the photocatalyst coating film of this embodiment contains this visible light responsive photocatalyst, it is useful in that the environmental purification effect and the antifouling effect are increased even in places where ultraviolet rays such as indoors are not sufficiently irradiated.

The visible light responsive photocatalyst is only required to exhibit photocatalytic activity and / or hydrophilicity with visible light. Examples of such visible light responsive photocatalysts include oxynitride compounds represented by TaON, LaTiO ₂ N, CaNbO ₂ N, LaTaON ₂ , and CaTaO ₂ N (see, for example, JP-A-2002-66333). , Oxysulfide compounds represented by Sm ₂ Ti ₂ S ₂ O _{7 and the} like (see, for example, JP-A-2002-233770), CaIn ₂ O ₄ , SrIn ₂ O ₄ , ZnGa ₂ O ₄ , Na ₂ Sb ₂ O ₆ oxides containing metal ions of ^{d 10} electronic states represented by (e.g., see JP-a-2002-59008) and the like. Titanium oxide imparted with a visible light responsive function by various modifications can also be cited as a visible light responsive photocatalyst. As such a titanium oxide, in the presence of a nitrogen-containing compound typified by ammonia or urea, for example, a titanium oxide precursor typified by titanium oxysulfate, titanium chloride or alkoxytitanium or high surface titanium oxide is baked. Nitrogen-doped titanium oxide obtained (see, for example, JP 2002-29750 A, JP 2002-87818 A, JP 2002-154823 A, JP 2001-207082 A), sulfur compounds such as thiourea Sulfur-doped titanium oxide and titanium oxide obtained by firing titanium oxide precursors represented by titanium oxysulfate, titanium chloride, and alkoxy titanium in the presence of hydrogen plasma treatment or heat treatment under vacuum Oxygen-deficient titanium oxide (see, for example, JP-A-2001-98219) And the like. Further, the photocatalyst particles are treated with a platinum halide compound (for example, see JP-A-2002-239353), and the photocatalyst particles are treated with tungsten alkoxide (see JP-A-2001-286755). A surface-treated photocatalyst is also preferably used as the visible light responsive photocatalyst.

In order to further increase the photocatalytic activity of the compound exhibiting high photocatalytic activity, a metal such as platinum, gold, silver, copper, palladium, rhodium, ruthenium or an oxide of the metal is added to the surface of the photocatalyst particles. It may be attached.
The above compounds exhibiting high photocatalytic activity are used singly or in combination of two or more.

  Among the compounds exhibiting high photocatalytic activity, anatase type titanium oxide and brookite type titanium oxide are preferable, and anatase type titanium oxide is more preferable. Any titanium oxide is suitable as a photocatalyst because it is inexpensive and harmless and has excellent chemical stability. In particular, anatase-type titanium oxide is useful as the above compound because of its higher photocatalytic activity.

  The compound showing high photocatalytic activity according to the present embodiment may be subjected to surface treatment on the primary particles and / or secondary particles in order to exhibit various performances. For example, the particles of this compound may be coated with an inorganic substance such as silicone, silica, alumina, calcium phosphate, apatite, or clay compound. Of these, silica and alumina are frequently used from the viewpoint of suppressing secondary aggregation of particles.

  The compound exhibiting high photocatalytic activity according to the present embodiment is obtained by adding or fixing a metal represented by Pt, Rh, Ru, Nb, Cu, Sn, Ni, Fe and / or an oxide of a metal to the particle. Alternatively, the particles may be coated with porous calcium phosphate or the like (for example, those described in JP-A-11-267519).

The photocatalyst coating film of this embodiment contains a rutile type titanium oxide so that the conditions represented by the said Formula (1) may be satisfied. This photocatalyst coating film preferably contains rutile type titanium oxide so as to satisfy the condition represented by the above formula (1a), and contains rutile type titanium oxide so as to satisfy the condition represented by the following formula (1b). More preferably.
6 / X ≦ a ≦ 40 / X (1b)
Here, X and a in formula (1b) have the same meanings as in formula (1).

  By satisfying such conditions, the photocatalytic coating film of this embodiment can contain an appropriate amount of rutile-type titanium oxide mainly from the viewpoint of ultraviolet absorption, depending on the film thickness. That is, when the film thickness of the photocatalyst coating film is increased, the amount of the rutile titanium oxide may be relatively small in order to suppress the amount of ultraviolet rays that reach the substrate by itself. On the other hand, when the film thickness of the photocatalytic coating film becomes thinner, the ultraviolet rays easily pass through the coating film, and the content of rutile-type titanium oxide is relatively increased and the amount of absorbed ultraviolet rays increases. Can be suppressed. As a result, the photocatalytic coating film of this embodiment can absorb ultraviolet rays more efficiently and reliably. Moreover, since the photocatalyst coating film of this embodiment does not contain excessive rutile type titanium oxide by satisfying the above conditions, the performance inherent to the coating film such as transparency can be maintained high.

  Moreover, in the photocatalyst coating film of this embodiment, it is preferable that mass ratio of the compound which shows the high photocatalytic ability with respect to a rutile type titanium oxide is 0.10-2.0. By including a rutile type titanium oxide and a compound exhibiting high photocatalytic activity within the numerical range, this photocatalytic coating film can more effectively express the performance of the photocatalyst while maintaining weather resistance. From the same viewpoint, the mass ratio is more preferably 0.10 to 1.3.

  In addition, as a photocatalyst containing rutile type titanium oxide and anatase type titanium oxide, a product name “P-25” manufactured by Degussa Co., Ltd. is commercially available. In this photocatalyst, the mass ratio of anatase-type titanium oxide to rutile-type titanium oxide is 73.5 / 26.5 (≈2.8). However, the photocatalyst is characterized by high photocatalytic performance, and cannot exhibit high weather resistance like the photocatalyst coating film of this embodiment. In addition, there are various theories as to the reason for the high activity of this photocatalyst, and it is generally considered that the feature is that rutile-type titanium oxide and anatase-type titanium oxide form a supporting structure. Thus, the above-mentioned photocatalyst manufactured by Degussa is completely different from the one according to the present embodiment (refer to Otani Bunko, “Photocatalyst Standard Research Method”, Tokyo Book, January 2005, P373-374). ).

  In the photocatalyst coating film of this embodiment, the rutile-type titanium oxide and the compound exhibiting high photocatalytic activity exist in the form of particles, but the particle diameter of both particles is preferably 100 nm or less in terms of primary particle diameter, preferably 50 nm or less. More preferably, it is more preferably 30 nm or less. By adjusting the particle diameter of both particles within the numerical range, the photocatalytic activity is further improved and a better appearance can be maintained. The primary particle size of both particles is a value obtained by randomly extracting 100 particles observed with a transmission electron microscope and calculating an arithmetic average thereof.

  Moreover, in the photocatalyst coating film of this embodiment, it is preferable that the ratio of the primary particle diameter of the compound which shows the high photocatalytic capability with respect to the primary particle diameter of a rutile type titanium oxide is 3/1-1/5. This further maintains the dispersion uniformity and good appearance.

  In the photocatalyst coating film of the present embodiment, the rutile titanium oxide and the compound exhibiting high photocatalytic activity may have the primary particles uniformly dispersed or the secondary particles uniformly dispersed, the primary particles and Secondary particles may be mixed and uniformly dispersed. Here, the secondary particles of both are secondary particles in which primary particles of rutile titanium oxide are aggregated, secondary particles in which primary particles of a compound exhibiting high photocatalytic activity are aggregated, and the above primary particles coexist. 1 or more types of secondary particles selected from the group consisting of secondary particles.

  It is preferable that the photocatalyst coating film of this embodiment contains an aqueous binder. Here, the “aqueous binder” refers to a solid component contained in a binder resin solution or binder resin dispersion substantially containing water as a dispersion medium. Examples of the binder resin contained in the aqueous binder include polyvinyl alcohol, cation-modified polyvinyl alcohol, polyvinyl alcohol derivatives typified by silanol-modified polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamides, starch and starch derivatives, carboxymethyl cellulose, and hydroxyethyl cellulose. Conventionally known poly (meth) acrylate-based, polyvinyl acetate-based, vinyl acetate-acrylic-based, ethylene vinyl acetate obtained by representative cellulose derivatives, casein, gelatin, radical polymerization, anionic polymerization, cationic polymerization in an aqueous medium , Silicone, polybutadiene, styrene butadiene, NBR, polyvinyl chloride, chlorinated polypropylene, polyethylene, Restyrene-based, vinylidene chloride-based, polystyrene- (meth) acrylate-based, styrene-maleic anhydride-based copolymers, silicone-modified acrylic, fluorine-acrylic, acrylic silicon, epoxy-acrylic modified copolymers Is mentioned. Here, “(meth) acrylate” means methacrylate and its corresponding acrylate.

When the photocatalyst coating film contains an aqueous binder, the photocatalyst coating film and the photocatalyst composition used to form the photocatalyst coating film are improved in toxicity, environmental pollution, and flammability due to volatilization of organic solvents, and have a low environmental impact. It becomes. Further, from the viewpoint of solvent resistance, it becomes easy to adopt a substrate made of a resin or a substrate on which an organic film is formed.
The aqueous binder is preferably contained in an amount of 30% by mass to 99.9% by mass and more preferably 50% by mass to 99% by mass with respect to the total mass of the photocatalyst coating film. By including the aqueous binder in the range, the photocatalytic coating film is further excellent in film formability, and the film formability and the activity of the photocatalyst can be further balanced.

  The aqueous binder may further include a compound having a functional group that reacts with the functional group of the binder resin. Examples of such compounds include (poly) isocyanate compounds, (poly) epoxy compounds, amino compounds, (poly) carboxy compounds, (poly) hydroxy compounds, glycol compounds, silanol compounds, silyl compounds, alkoxy compounds, (meta ) Acrylates.

  The photocatalyst coating film of this embodiment may contain other photocatalysts in addition to the above-described titanium oxide. Other photocatalysts have a band gap energy of 1.2 to 1.2 from the balance between the ability to advance oxidation and reduction reactions of other substances by light irradiation and the light energy necessary to generate holes and electrons. A semiconductor compound of 5.0 eV is preferable, and a semiconductor compound of 1.5 to 4.1 eV is more preferable.

  It is particularly preferable that the aqueous binder in the photocatalyst coating film of the present embodiment further contains metal oxide particles and / or polymer emulsion particles that do not have photocatalytic activity. Furthermore, the photocatalyst coating film of the present embodiment may include a solid component among other components that can be included in the photocatalyst composition described below. In the description of the photocatalyst composition described below, these particles and other components will be described in detail.

  The content ratio of each component in the photocatalyst coating film of the present embodiment satisfies the condition represented by the above formula (1), and the mass ratio of the compound exhibiting high photocatalytic ability with respect to rutile-type titanium oxide is preferably in the above numerical range. If it is in the range which can achieve the objective of this invention, it will not specifically limit. However, with respect to 100 parts by mass of the polymer emulsion particles, the compound particles having high photocatalytic ability and the metal oxide particles having no photocatalytic ability are each preferably 5 to 900 parts by mass, and 0.1 to 50 parts by mass. Is more preferable, 10 to 800 parts by mass is further preferable, and 0.5 to 30 parts by mass is particularly preferable. As a result, it is possible to form a film having excellent coating film formability and few defects and high transparency at a higher level. Furthermore, this range is preferable from the viewpoint of the balance between water resistance and hydrophilicity and the photocatalytic activity of the photocatalyst.

  Although the film thickness of the photocatalyst coating film of this embodiment is not specifically limited, It is preferable in it being 0.05-100 micrometers, it is more preferable in it being 0.1-10 micrometers, and it is still more preferable in it being 1.0-2.5 micrometers. Thereby, the above-mentioned effect by this invention can be show | played more effectively and reliably. In addition, when the thickness is 100 μm or less, good transparency can be secured, and when the thickness is 0.05 μm or more, functions such as antifouling property and photocatalytic activity can be expressed more effectively. . This film thickness is controlled by adjusting the content ratio of the photocatalyst contained in the photocatalyst composition described later, the type and content ratio of the binder resin contained in the aqueous binder, the coating method, and the like.

  Moreover, it is preferable that the haze value is 0.0-2.0, and it is especially preferable that the photocatalyst coating film of this embodiment is 0.0-2.0 from a viewpoint of ensuring the transparency. This haze value is controlled by adjusting the film thickness and the content ratio of solid components, particularly the content ratio of metal oxide particles and polymer emulsion particles that do not have photocatalytic activity.

  The photocatalyst coating film of this embodiment may be formed so as to cover the entire surface of the substrate, and maintains durability at a high level while maintaining the decomposition activity (photocatalytic activity) and / or hydrophilicity of organic substances by the photocatalyst at a high level. It may be formed so as to cover only a part of the surface of the substrate that needs to be sufficiently excellent.

  The photocatalyst coating film of the present embodiment described above is excellent in photocatalytic activity and / or hydrophilicity as well as in weather resistance, water resistance, and optical characteristics by having the above-described configuration. In order to suppress the deterioration of the substrate and the peeling of the photocatalyst coating film, it is also conceivable to reduce the ultraviolet rays reaching the substrate by increasing the number of metal oxide particles having no photocatalytic activity. However, in this case, the transparency of the photocatalyst coating film is lowered, and by containing the rutile type titanium oxide so as to satisfy the condition represented by the above formula (1), the deterioration of the substrate is suppressed, Sufficient transparency can be secured. Moreover, this photocatalyst coating film shows a favorable antifouling and antifogging effect by including a compound exhibiting high photocatalytic activity. And even if this photocatalyst coating film is formed so as to be in direct contact with the surface of the substrate, decomposition and deterioration of the substrate can be sufficiently suppressed, so that it can be easily formed with fewer steps. Furthermore, the photocatalyst coating film of this embodiment can suppress peeling over a long period, while maintaining high photocatalytic activity and hydrophilicity over a long period.

Here, the photocatalytic activity can be determined, for example, by measuring the decomposability of an organic substance such as a pigment in a material in contact with the coating film when the photocatalytic coating film is irradiated with light. A surface having photocatalytic activity exhibits excellent decomposition activity and contamination resistance of contaminating organic substances. Here, the light irradiation is performed using a light source having a higher energy than the band gap energy of the photocatalyst. As the light source, light such as black light, xenon lamp, mercury lamp, LED, etc. can be used in addition to light obtained in a general residential environment such as sunlight and indoor lighting. Illuminance of the light is preferably at 0.001 mW / cm ² or more, more preferably 0.01 mW / cm ² or more, further preferable to be 0.1 mW / cm ² or more.

  Moreover, hydrophilicity is determined by measuring the contact angle at the time of light irradiation of the photocatalyst coating film surface. A surface with excellent hydrophilicity exhibits a low contact angle. From the viewpoint of antifouling properties, the contact angle at the time of light irradiation is preferably 60 ° or less, and more preferably 40 ° or less.

  Next, the photocatalyst composition of this embodiment will be described in detail. The photocatalyst composition of this embodiment is a photocatalyst composition used for forming the photocatalyst coating film. The photocatalyst coating film is obtained by applying the photocatalyst composition to the surface of a substrate or a coating covering the substrate and drying it. Therefore, the photocatalyst composition of this embodiment contains both a rutile type titanium oxide and a compound exhibiting high photocatalytic activity. Furthermore, this photocatalyst composition preferably contains an aqueous binder, and in that case, it contains water as a solvent or dispersion medium for the aqueous binder. Details of these components are the same as those described above, and a description thereof is omitted here.

  The photocatalyst composition of the present embodiment comprises at least a first hydrolyzable silicon compound and a first secondary and / or 3 in the presence of metal oxide particles having no photocatalytic activity, water and a first emulsifier. More preferably, it further comprises polymer emulsion particles obtained by copolymerization with a vinyl monomer having a secondary amide group. Here, “having no photocatalytic activity” refers to a substance that does not exhibit photocatalytic activity even when irradiated with light.

  Examples of the metal oxide particles having no photocatalytic activity according to the present embodiment include silicon dioxide (silica) particles, aluminum oxide (alumina) particles, calcium silicate particles, magnesium oxide particles, antimony oxide particles, zirconium oxide particles and the like. These composite oxide particles are mentioned. These are used singly or in combination of two or more. Among these, from the viewpoint of increasing the surface hydroxyl groups, increasing the surface area of the metal oxide particles, and strengthening the bond between the metal oxide particles or between the metal oxide and the polymer emulsion particles, the silicon dioxide particles, oxidation Aluminum particles, antimony oxide particles, and composite oxide particles thereof are preferable, and colloidal silica particles that are a dispersion of silica based on silicon dioxide in water or a water-soluble solvent are more preferable.

  The number average particle diameter of the metal oxide particles is preferably 1 to 400 nm, more preferably 1 to 100 nm, and further preferably 1 to 50 nm. When the particle diameter is 400 nm or less, the surface area of the metal oxide particles is increased, and the effect of strengthening the bond between the metal oxide particles or between the metal oxide and the polymer emulsion particles is exhibited. Here, the number average particle size of the metal oxide particles is measured by a wet particle size measuring apparatus of a dynamic light scattering method. This number average particle size is determined by creating a calibration curve between the dynamic light scattering wet particle size measuring device and the laser diffraction / scattering wet particle size measuring device. You may determine by converting the number average particle diameter measured with the measuring apparatus into what was measured with the measuring apparatus of the dynamic light scattering system.

The polymer emulsion particles according to this embodiment are a vinyl monomer having at least a first hydrolyzable silicon compound and a first secondary and / or tertiary amide group in the presence of water and a first emulsifier. Are obtained by copolymerization. As a 1st hydrolysable silicon compound, the compound represented by following General formula (1), its condensation product, and a silane coupling agent can be illustrated.
SiW _x R _y (2)
In the formula, W is an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, an acetoxy group having 1 to 20 carbon atoms, a halogen atom, a hydrogen atom, an oxime group having 1 to 20 carbon atoms, a phenoxy group, an aminoxy group, an amide. A group selected from the group consisting of groups is shown. R represents a hydrocarbon group selected from the group consisting of linear or branched alkyl groups having 1 to 30 carbon atoms, cycloalkyl groups having 5 to 20 carbon atoms, and aryl groups having 6 to 20 carbon atoms. Note that the aryl group having 6 to 20 carbon atoms may be substituted with an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a halogen atom. X is an integer of 1 to 4, y is an integer of 0 to 3, and x + y = 4. Further, when x is 2 or more, the plurality of Ws may be the same or different from each other, and when y is 2 or more, the plurality of Rs may be the same or different from each other.

  Examples of the compound represented by the above formula (2) include tetraalkoxysilanes represented by tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, and tetra-n-butoxysilane, Methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, n-butyltrimethoxysilane N-butyltriethoxysilane, n-pentyltrimethoxysilane, n-hexyltrimethoxysilane, n-heptyltrimethoxysilane, n-octyltrimethoxysilane, vinyltrimethoxysilane, vinyl Ethoxysilane, allyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3,3,3- Trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-hydroxyethyltrimethoxysilane, 2-hydroxyethyltriethoxy Silane, 2-hydroxypropyltrimethoxysilane, 2-hydroxypropyltriethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-hydroxypropyltriethoxysilane 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl Triethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meta ) Atacrylyloxypropyltriethoxysilane, 3- (meth) acryloyloxypropyltri-n-propoxysilane, 3- (meth) acryloyloxypropyltriisopropoxysilane, 3-ureidopropyltrimethoxysila , Trialkoxysilanes represented by 3-ureidopropyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, di-n-propyldimethoxysilane, di-n-propyldi Ethoxysilane, diisopropyldimethoxysilane, diisopropyldiethoxysilane, di-n-butyldimethoxysilane, di-n-butyldiethoxysilane, di-n-pentyldimethoxysilane, di-n-pentyldiethoxysilane, di-n- Hexyldimethoxysilane, di-n-hexyldiethoxysilane, di-n-heptyldimethoxysilane, di-n-heptyldiethoxysilane, di-n-octyldimethoxysilane, di-n-octyldiethoxysilane, di-n -Cyclohe For dialkoxysilanes represented by sildimethoxysilane, di-n-cyclohexyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane, trimethylmethoxysilane, trimethylethoxysilane Representative monoalkoxysilanes can be mentioned. These are used singly or in combination of two or more.

  The silane coupling agent is preferably a hydrolyzable silicon compound having a functional group having reactivity with an organic substance in the molecule. Examples of the functional group include a vinyl polymerizable group, a thiol group, an epoxy group, an amino group, a methacryl group, a mercapto group, and an isocyanate group. Among these functional groups, a vinyl polymerizable group is preferable from the viewpoint of forming a chemical bond by copolymerization or a chain transfer reaction with a vinyl monomer having a secondary and / or tertiary amide group. Examples of the hydrolyzable silicon compound having a vinyl polymerizable group include 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, and 3- (meth) acryloyloxypropylmethyldimethoxy. Silane, 3- (meth) acryloyloxypropyltri-n-propoxysilane, 3- (meth) acryloyloxypropyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, 2-trimethoxysilylethyl Vinyl ether is mentioned. These are used singly or in combination of two or more. In this case, from the same viewpoint as described above, the first hydrolyzable silicon compound is vinyl polymerizable with respect to 100 parts by mass of the vinyl monomer having the first secondary and / or tertiary amide group described later. It is preferable to contain 0.1 to 100 parts by mass of one or more hydrolyzable silicon compounds having a group.

  Examples of the vinyl monomer having the first secondary and / or tertiary amide group include N-alkyl or N-alkylene-substituted (meth) acrylamide. More specifically, for example, N-methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N-ethylmeta Acrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-ethylmethacrylamide, N-isopropylacrylamide, Nn-propylacrylamide, N-isopropylmethacrylamide, Nn-propylmethacrylamide, N-methyl -N-n-propylacrylamide, N-methyl-N-isopropylacrylamide, N-acryloylpyrrolidine, N-methacryloylpyrrolidine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acrylic Ylhexahydroazepine, N-acryloylmorpholine, N-methacryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, N, N′-methylenebisacrylamide, N, N′-methylenebismethacrylamide, N-vinylacetamide, dye Examples include acetone acrylamide, diacetone methacrylamide, N-methylol acrylamide, and N-methylol methacrylamide. These are used singly or in combination of two or more. Among these, it is preferable to use a vinyl monomer having a tertiary amide group because hydrogen bondability is enhanced.

  Examples of the first emulsifier include acid typified by alkylbenzene sulfonic acid, alkyl sulfonic acid, alkyl sulfosuccinic acid, polyoxyethylene alkyl sulfuric acid, polyoxyethylene alkyl aryl sulfuric acid, and polyoxyethylene distyryl phenyl ether sulfonic acid. Emulsifier, alkali metal (Li, Na, K, etc.) salt of acidic emulsifier, ammonium salt of acidic emulsifier, anionic surfactant represented by fatty acid soap, alkyltrimethylammonium bromide, alkylpyridinium bromide, imidazolinium laurate Representative cationic surfactants such as quaternary ammonium salt, pyridinium salt, imidazolinium salt type, polyoxyethylene alkyl aryl ether, polyoxyethylene sorbitan fatty acid ester, polyoxy Ethylene polyoxypropylene block copolymers, nonionic surfactants represented by polyoxyethylene distyryl phenyl ether, a reactive emulsifier having a radical-polymerizable double bond. These are used singly or in combination of two or more. Among these, a reactive emulsifier having a radical polymerizable double bond is preferable from the viewpoints of water dispersion stability of the polymer emulsion particles and mechanical strength, chemical resistance, and water resistance of the formed coating film.

  Examples of the reactive emulsifier having a radical polymerizable double bond include vinyl monomers having a sulfonic acid group or a sulfonate group, vinyl monomers having a sulfate ester group, alkali metal salts of these vinyl monomers, and ammonium. Examples thereof include vinyl monomers having nonionic groups represented by salts and polyoxyethylene, and vinyl monomers having quaternary ammonium salts.

  Among the reactive emulsifiers, the vinyl monomer salt having a sulfonic acid group or a sulfonate group includes, for example, a radical polymerizable double bond, and an ammonium salt, sodium salt or potassium salt of a sulfonic acid group. A partially substituted alkyl group having 1 to 20 carbon atoms, an alkyl ether group having 2 to 4 carbon atoms, a polyalkyl ether group having 2 to 4 carbon atoms, an aryl group having 6 or 10 carbon atoms, and Examples thereof include a compound having a substituent selected from the group consisting of a succinic acid group, and a vinyl sulfonate compound having a vinyl group to which a group which is an ammonium salt, sodium salt or potassium salt of a sulfonic acid group is bonded. The vinyl monomer having a sulfate ester group has a radically polymerizable double bond and is partially substituted with a group that is an ammonium salt, sodium salt, or potassium salt of a sulfate ester group, having 1 carbon atom. Examples thereof include compounds having a substituent selected from the group consisting of ˜20 alkyl groups, C 2-4 alkyl ether groups, C 2-4 polyalkyl ether groups, and C 6 or 10 aryl groups.

  Specific examples of the compound having a succinic acid group partially substituted with a group which is an ammonium salt, sodium salt or potassium salt of the sulfonic acid group include allylsulfosuccinate. Examples of commercially available products include Eleminol JS-2 (trade name, manufactured by Sanyo Kasei Co., Ltd.), Latemul S-120, S-180A or S-180 (trade name, manufactured by Kao Corporation). It is done.

  Further, a compound having an alkyl ether group having 2 to 4 carbon atoms or a polyalkyl ether group having 2 to 4 carbon atoms, which is partially substituted by a group which is an ammonium salt, sodium salt or potassium salt of the sulfonic acid group. As what is marketed, for example, Aqualon HS-10 or KH-1025 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap SE-1025N or SR-1025 (trade name, Asahi Denka Kogyo ( Co., Ltd.).

  Other specific examples of the compound having an aryl group partially substituted with a sulfonate group include ammonium salt, sodium salt and potassium salt of p-styrenesulfonic acid.

  Examples of the vinyl sulfonate compound having a vinyl group to which a group of ammonium salt, sodium salt or potassium salt of the sulfonic acid group is bonded include, for example, alkylsulfonic acid (meth) acrylate represented by 2-sulfoethyl acrylate, Examples include methyl propane sulfonic acid (meth) acrylamide, and ammonium salt, sodium salt, and potassium salt of allyl sulfonic acid.

  Examples of the compound having an alkyl ether group having 2 to 4 carbon atoms or a polyalkyl ether group having 2 to 4 carbon atoms partially substituted by ammonium salt, sodium salt or potassium salt of the sulfate group include, for example, sulfonate group And a compound having an alkyl ether group partially substituted by.

  In addition, specific examples of vinyl monomers having a nonionic group include α- [1-[(allyloxy) methyl] -2- (nonylphenoxy) ethyl] -ω-hydroxypolyoxyethylene (trade name: ADEKA rear soap). NE-20, NE-30, NE-40, etc., manufactured by Asahi Denka Kogyo Co., Ltd.), polyoxyethylene alkylpropenyl phenyl ether (trade names: Aqualon RN-10, RN-20, RN-30, RN-50, etc.) , Daiichi Pharmaceutical Industry Co., Ltd.).

  The polymer emulsion particles according to the present embodiment are copolymerized with the first hydrolyzable silicon compound and the vinyl monomer having the first secondary and / or tertiary amide group and other monomers. For example, it may be obtained by polymerizing a vinyl monomer having no secondary or tertiary amide. Examples of vinyl monomers having no secondary or tertiary amide include, for example, (meth) acrylic acid esters, aromatic vinyl compounds, vinyl cyanides, carboxyl group-containing vinyl monomers, and hydroxyl group-containing vinyl monomers. And monomers containing functional groups such as a monomer, an epoxy group-containing vinyl monomer, a carbonyl group-containing vinyl monomer, and an anionic vinyl monomer. These are used singly or in combination of two or more.

  Examples of the (meth) acrylic acid ester include (meth) acrylic acid alkyl ester having 1 to 50 carbon atoms in the alkyl portion, and (poly) oxyethylene di (meth) acrylate having 1 to 100 ethylene oxide groups. Is mentioned. Specific examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and methyl (meth) acrylate. Examples include cyclohexyl, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, and dodecyl (meth) acrylate. Specific examples of (poly) oxyethylene di (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, diethylene glycol methoxy (meth) acrylate, tetraethylene glycol di (meth) acrylate Is mentioned.

  In the present specification, “(meth) acryl” means “methacryl” and “acryl” corresponding to it.

  When the vinyl monomer having no secondary or tertiary amide contains a (meth) acrylic acid ester, the content thereof is one or a mixture of two or more vinyls having no secondary and tertiary amide. Based on the monomer amount, it is preferably more than 0 mass% and 99.9 mass%, more preferably 5 to 80 mass%.

  Examples of the carboxyl group-containing vinyl monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, or itaconic acid, maleic acid, and fumaric acid. Examples include half esters of acids. By using a carboxylic acid group-containing vinyl monomer, a carboxyl group can be introduced into the polymer emulsion particles, improving the stability as an emulsion, and having a resistance to an external dispersion breaking action. It becomes possible. At this time, a part or all of the carboxyl groups introduced into the polymer emulsion particles can be neutralized with amines such as ammonia, triethylamine and dimethylethanolamine, and bases such as NaOH and KOH.

  When the vinyl monomer having no secondary or tertiary amide contains a carboxyl group-containing vinyl monomer, its content does not have all secondary and tertiary amides as one or a mixture of two or more. From the viewpoint of water resistance, it is preferably more than 0 mass% and 50 mass% based on the vinyl monomer amount. This content is more preferably 0.1 to 10% by mass, still more preferably 0.1 to 5% by mass.

  Examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, hydroxyalkyl ester of (meth) acrylic acid represented by 4-hydroxybutyl (meth) acrylate, di-2-hydroxyethyl fumarate, mono-2-hydroxyethyl monobutyl fumarate , Allyl alcohol, (poly) oxyethylene mono (meth) acrylate having 1 to 100 ethylene oxide groups, and (poly) oxypropylene mono (meth) acrylate having 1 to 100 propylene oxide groups. Furthermore, “Placcel FM, FA monomer” (trade name, manufactured by Daicel Chemical Industries, Ltd., caprolactone-added monomer) and other hydroxyalkyl esters of α, β-ethylenically unsaturated carboxylic acid can be mentioned. Specific examples of the (poly) oxyethylene (meth) acrylate include ethylene glycol (meth) acrylate, ethylene glycol methoxy (meth) acrylate, diethylene glycol (meth) acrylate, diethylene glycol methoxy (meth) acrylate, (meth ) Tetraethylene glycol acrylate and tetraethylene glycol methoxy (meth) acrylate. Specific examples of (poly) oxypropylene (meth) acrylate include propylene glycol (meth) acrylate, propylene glycol methoxy (meth) acrylate, dipropylene glycol (meth) acrylate, dimethoxy meth (meth) acrylate. Examples include propylene glycol, tetrapropylene glycol (meth) acrylate, and tetrapropylene glycol methoxy (meth) acrylate. By using a hydroxyl group-containing vinyl monomer, it becomes possible to control the hydrogen bonding force of the polymerization product with a vinyl monomer having a secondary and / or tertiary amide group, and the polymer emulsion particles Water dispersion stability can be improved.

  When the vinyl monomer having no secondary or tertiary amide contains a hydroxyl group-containing vinyl monomer, the content thereof is one or a mixture of two or more vinyls having no secondary or tertiary amide. Based on the monomer amount, it is preferably more than 0% by mass and 80% by mass, more preferably 0.1 to 50% by mass, and further preferably 0.1 to 10% by mass.

  Examples of the glycidyl group-containing vinyl monomer include glycidyl (meth) acrylate, allyl glycidyl ether, and allyl dimethyl glycidyl ether.

  When a glycidyl group-containing vinyl monomer or a carbonyl group-containing vinyl monomer is used, the polymer emulsion particles have good reactivity. As a result, it is possible to form a photocatalyst composition excellent in solvent resistance by crosslinking with a hydrazine derivative, a carboxylic acid derivative, an isocyanate derivative, or the like. When the vinyl monomer having no secondary or tertiary amide contains a glycidyl group-containing vinyl monomer and / or a carbonyl group-containing vinyl monomer, the content thereof is one or a mixture of two or more. Based on the amount of vinyl monomer having no secondary or tertiary amide, it is preferably more than 0% by mass and 50% by mass.

  Specific examples of vinyl monomers other than those described above include, for example, (meth) acrylamide, ethylene, propylene, olefins typified by isobutylene, dienes typified by butadiene, vinyl chloride, vinylidene chloride vinyl chloride, Haloolefins typified by tetrafluoroethylene, chlorotrifluoroethylene, vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl benzoate, vinyl pt-butylbenzoate, vinyl pivalate, 2-ethylhexanoic acid Carboxylic acid vinyl esters typified by vinyl, vinyl versatate, vinyl laurate, isopropenyl acetate, isopropenyl carboxylic acid represented by isopropenyl propionate, ethyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl Vinyl ethers typified by ether, aromatic vinyl compounds typified by styrene, vinyl toluene, allyl acetates typified by allyl acetate, allyl benzoate, allyl ethers typified by allyl ethyl ether, allyl phenyl ether, 4- (meth) acryloyloxy-2,2,6,6, -tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, perfluoromethyl (meth) Examples include acrylate, perfluoropropyl (meth) acrylate, perfluoropropylmethyl (meth) acrylate, vinylpyrrolidone, trimethylolpropane tri (meth) acrylate, and allyl (meth) acrylate. These are used singly or in combination of two or more.

  The polymer emulsion particles according to this embodiment are prepared by a known emulsion polymerization except that the above-mentioned ones are used. In this case, a known one such as a polymerization initiator such as ammonium persulfate or a surfactant such as dodecylbenzenesulfonic acid is used. May be used. At this time, the mass ratio of the vinyl monomer having the first secondary and / or tertiary amide group to the polymer emulsion particles is preferably 0.1 to 0.5 and preferably 0.1 to 0.3. And more preferred. By setting the mass ratio within this range, the balance between hydrogen bonding properties and blending stability can be improved.

  The mass ratio of the vinyl monomer having the first secondary and / or tertiary amide group to the metal oxide particles described above is preferably 0.1 to 1.0, preferably 0.1 to 0.7. More preferably. From the viewpoint of achieving a good balance between hydrogen bonding properties and blending stability, the mass ratio is preferably within this range.

  The polymer emulsion particles according to the present embodiment may have a core / shell structure including a core part and one or more shell parts covering the core part. For example, when the polymer emulsion particles include a core portion and a single shell portion, in the presence of water, a first emulsifier and seed particles, at least a first hydrolyzable silicon compound and a first secondary and Obtained by copolymerizing with a vinyl monomer having a tertiary amide group, wherein the seed particles are at least a second secondary and / or in the presence of water and a second emulsifier. A vinyl monomer having a tertiary amide group, a vinyl monomer copolymerizable with the vinyl monomer and having no secondary or tertiary amide group, and a second hydrolyzable silicon compound It may be obtained by polymerizing one or more compounds selected from the group.

  As the second hydrolyzable silicon compound for obtaining the seed particles, the same one as the first hydrolyzable silicon compound is used. However, the first and second hydrolyzable silicon compounds used to obtain the same polymer emulsion particles may be the same as or different from each other. The vinyl polymer having the second secondary and / or tertiary amide group for obtaining seed particles is the same as the first secondary and / or tertiary amide group. However, the first and second vinyl polymers having secondary and / or tertiary amide groups used to obtain the same polymer emulsion particles may be the same or different from each other. Further, the second emulsifier for obtaining seed particles is the same as the first emulsifier. However, the first and second emulsifiers used to obtain the same polymer emulsion particles may be the same or different from each other.

  Examples of vinyl monomers that can be copolymerized with the second vinyl monomer and have no secondary or tertiary amide group include acrylic acid esters, methacrylic acid esters, aromatic vinyl compounds, and vinyl cyanides. Others containing a functional group such as a carboxyl group-containing vinyl monomer, a hydroxyl group-containing vinyl monomer, an epoxy group-containing vinyl monomer, a carbonyl group-containing vinyl monomer, or an anionic vinyl monomer The body is mentioned. These are used singly or in combination of two or more. These compounds can be exemplified by those described above, and can be selected according to the required performance such as water dispersibility, control of hydrogen bonding force, water resistance and chemical resistance.

  The seed particles are preferably obtained by polymerizing the second hydrolyzable silicon compound. Thereby, high flexibility can be imparted to the coating film, and higher weather resistance is recognized.

  When the polymer emulsion particles according to the present embodiment have a core / shell structure including a core portion and one or more shell portions covering the core portion, the outermost shell portion of the shell portions and The core part is obtained by copolymerizing at least a first hydrolyzable silicon compound and a vinyl monomer having a first secondary and / or tertiary amide group. The mass ratio of the vinyl monomer having the first secondary and / or tertiary amide group to the hydrolyzable silicon compound is 1.0 or less, and the first hydrolyzable silicon compound in the outermost shell part The mass ratio of the vinyl monomer having the first secondary and / or tertiary amide group to may be 0.1 to 5.0. The mass ratio of the vinyl monomer having the first secondary and / or tertiary amide group to the first hydrolyzable silicon compound in the core portion is 1.0 or less, the first in the outermost shell portion. By making the mass ratio of the vinyl monomer having the first secondary and / or tertiary amide group to the hydrolyzable silicon compound of 0.1 or more, further, the first in the outermost shell portion When the mass ratio of the vinyl monomer having the first secondary and / or tertiary amide group to the hydrolyzable silicon compound is 5.0 or less, higher water resistance and weather resistance are recognized.

  The polymer emulsion particles having a core / shell structure according to this embodiment are prepared by two or more known emulsion polymerizations except that the above-described materials are used. In the obtained polymer emulsion particles, the seed particles become a core part.

  The number average particle diameter of the polymer emulsion particles having or not having the core / shell structure according to this embodiment is preferably 1 to 400 nm, and more preferably 1 to 200 nm. When the number average particle diameter is 400 nm or less, the hydrogen bonding force with the metal oxide particles is increased, and a coating film having further excellent strength, hardness, and durability can be formed. Here, the number average particle size of the polymer emulsion particles is measured by a wet particle size measuring apparatus of a dynamic light scattering method. This number average particle size is determined by creating a calibration curve between the dynamic light scattering wet particle size measuring device and the laser diffraction / scattering wet particle size measuring device. You may determine by converting the number average particle diameter measured with the measuring apparatus into what was measured with the measuring apparatus of the dynamic light scattering system.

  The content ratio of each component in the photocatalyst composition of the present embodiment is such that the photocatalyst coating film obtained using the composition satisfies the condition represented by the above formula (1), and preferably has a high photocatalytic ability for rutile titanium oxide. If the mass ratio of the compound which shows is in the said numerical range and can achieve the objective of this invention, it will not specifically limit. However, with respect to 100 parts by mass of the polymer emulsion particles, the photocatalyst particles containing rutile titanium oxide and the metal oxide particles having no photocatalytic ability are each preferably 5 to 900 parts by mass, and 0.1 to 50 parts by mass. Part is more preferable, 10 to 800 parts by mass is further preferable, and 0.5 to 30 parts by mass is particularly preferable. As a result, it is possible to form a film having excellent coating film formability and few defects and high transparency at a higher level. Furthermore, this range is preferable from the viewpoint of the balance between water resistance and hydrophilicity and the photocatalytic activity of photocatalysts including titanium oxide.

  In addition, the photocatalyst composition of the present embodiment may further contain an emulsifier in addition to the first and second emulsifiers, particularly from the viewpoint of dispersion stability of rutile titanium oxide and a compound exhibiting high photocatalytic ability. Examples of the emulsifier include those similar to the first and second emulsifiers. This emulsifier may be the same as or different from the first and second emulsifiers.

  Furthermore, the photocatalyst composition of the present embodiment may contain a dispersion stabilizer from the viewpoint of dispersion stability of each particle. Examples of the dispersion stabilizer include various water-soluble oligomers selected from the group consisting of polycarboxylic acids and sulfonates, polyvinyl alcohol, hydroxyethyl cellulose, starch, maleated polybutadiene, maleated alkyd resin, polyacrylic acid (salt ), Synthetic or natural water-soluble or water-dispersible various water-soluble polymer substances typified by polyacrylamide, water-soluble or water-dispersible acrylic resins. These emulsifiers and dispersion stabilizers are used singly or in combination of two or more.

  Moreover, the photocatalyst composition of this embodiment may contain another component in the range which does not inhibit achievement of the objective of this invention. For example, a small amount of an organic solvent such as alcohols may be included for the purpose of controlling the interaction between the photocatalyst and the aqueous binder. In addition, the photocatalyst composition of the present embodiment is a component added and blended with a normal paint or molding resin, for example, a thickener, a leveling agent, a thixotropic agent, an antifoaming agent, depending on its use and usage method. Agent, freezing stabilizer, matting agent, crosslinking reaction catalyst, pigment, curing catalyst, crosslinking agent, filler, anti-skinning agent, dispersant, wetting agent, light stabilizer, antioxidant, UV absorber, rheology control Agent, antifoaming agent, film-forming aid, rust preventive agent, dye, plasticizer, lubricant, reducing agent, antiseptic agent, antifungal agent, deodorant agent, yellowing preventive agent, antistatic agent or charge preparation agent Etc. may be selected and combined in accordance with each purpose.

  The photocatalyst composition of the present embodiment can be obtained by adding and mixing the above-described components by a conventional method. Therefore, the method of mixing the rutile titanium oxide and the compound exhibiting high photocatalytic ability is not particularly limited. However, it is most convenient to synthesize rutile titanium oxide and a compound exhibiting high photocatalytic ability separately before mixing them. In this mixing, sols of rutile-type titanium oxide obtained by synthesis or a compound exhibiting high photocatalytic ability may be mixed, or those particles obtained by drying the sol may be mixed. Among these, in order to disperse more uniformly, it is preferable to mix sols. The sol may be either an organosol or a hydrosol, but a hydrosol is preferable from the viewpoint of reducing the environmental burden.

  When the rutile titanium oxide and the compound exhibiting high photocatalytic activity are mixed, it can be mixed more uniformly by using a stirring device. The mixing device may be a known one, and for example, a magnetic stirrer, ball mill, sand glider, high-speed high shear disperser, colloid mill, ultrasonic disperser, homogenizer or the like may be used. It is also effective to synthesize a compound showing high photocatalytic ability or rutile type titanium oxide in advance and depositing rutile type titanium oxide or a compound showing high photocatalytic ability on the particle surface. Or when using anatase type titanium oxide as a compound which shows high photocatalytic ability, you may synthesize | combine rutile-anatase mixed crystal type titanium oxide by a conventional method.

  By applying the photocatalyst composition of the present embodiment to the surface of the substrate or the coating covering the substrate and drying, the photocatalyst coating film formed on the substrate can be obtained. Examples of the base material on which the photocatalyst composition is applied include organic substrates represented by synthetic resins, natural resins, fibers, inorganic substrates represented by metals, ceramics, glass, stone, cement, concrete, and combinations thereof. Is mentioned.

  Examples of the synthetic resin include thermoplastic resins and curable resins (thermosetting resins, photocurable resins, moisture curable resins, and the like). Specific examples include silicone resin, acrylic resin, methacrylic resin, fluorine resin, alkyd resin, aminoalkyd resin, vinyl resin, polyester resin, styrene-butadiene resin, polyolefin resin, polystyrene resin, polyketone resin, polyamide resin, polycarbonate. Resin, polyacetal resin, polyether ether ketone resin, polyphenylene oxide resin, polysulfone resin, polyphenylene sulfone resin, polyether resin, polyvinyl chloride resin, polyvinylidene chloride resin, urea resin, phenol resin, melamine resin, epoxy resin, urethane resin And silicone-acrylic resin. Examples of the natural resin include cellulose resins, isoprene resins typified by natural rubber, and protein resins typified by casein.

When the substrate is a resin plate or fiber, the surface thereof may be subjected to a surface treatment such as a corona discharge treatment, a flame treatment, or a plasma treatment, but these surface treatments are not essential.
The kind and film thickness of the base material can be properly used according to the application.

  The photocatalyst composition of the present embodiment can be applied by any method depending on its use and the like. Examples of the application method include spray spraying, flow coating, roll coating, brush coating, dip coating, spin coating, screen printing, casting, gravure printing, and flexographic printing.

  After apply | coating the photocatalyst composition of this embodiment, a photocatalyst coating film is obtained by drying and removing a volatile matter. In this case, for example, after drying at a low temperature of 20 ° C. to 80 ° C., heat treatment at 20 ° C. to 500 ° C., more preferably 40 ° C. to 250 ° C. may be performed as desired, or ultraviolet irradiation or the like may be performed. Good.

  In this embodiment, a photocatalyst-coated product includes a substrate and the photocatalyst coating film formed on the substrate. The photocatalyst-coated product may be the same as the known embodiment except that the photocatalyst coating film of the present embodiment is provided. Specific examples of the photocatalyst-coated product of the present embodiment include, for example, building materials, building exteriors, building interiors, window frames, window glass, structural members, building facilities such as houses, vehicle illumination lamp covers, window glass, mechanical devices, Exterior of goods, dustproof cover and painting, display equipment, its covers, traffic signs, various display devices, display objects such as advertising towers, sound insulation walls for roads and railways, bridges, exterior and painting of guardrails, tunnel interior and painting Examples include exterior parts such as insulators, solar battery covers, solar water heater heat collection covers, etc., and exterior parts of electronic and electrical equipment, especially transparent members, greenhouses, greenhouses, and the like. This photocatalyst-coated product may be obtained by applying the photocatalyst composition of the present embodiment on the surface of the substrate and drying to form a photocatalyst coating film on the substrate, but the production method is not limited thereto. For example, the substrate and the photocatalyst coating film may be molded at the same time, and more specifically, may be integrally molded. In addition, after the photocatalyst coating film of the present embodiment is formed on a substrate, the photocatalyst coating film is adhered to another substrate by adhesion, fusion, or the like in a state where the photocatalyst coating film is peeled off or adhered to the substrate. You may let them.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. In Examples and Comparative Examples, various physical properties were measured by the following methods.

1. Contact angle of water with respect to coating film surface The contact angle was measured by placing a drop of deionized water on the surface of the photocatalyst coating film and leaving it at 23 ° C. for 1 minute, and then using a CA-X150 contact angle meter manufactured by Kyowa Interface Science Co., Ltd. Measured. The smaller the contact angle of water with the coating film, the higher the hydrophilicity of the coating film surface.
2. Transparency The transparency of the photocatalyst coating film is determined by forming a photocatalyst coating film on a PET film as described later, and using a turbidimeter (trade name “NDH2000”) manufactured by Nippon Denshoku Industries Co., Ltd. The haze value was measured and evaluated according to -K7105.

3. Light resistance The photocatalyst coating film was irradiated with light from a high-pressure mercury lamp using an ultraviolet irradiation device (trade name “HandyUV300”) manufactured by Oak Seisakusho. The haze value of the laminate of the coating film and the PET film after 15 hours from the start of irradiation was measured in the same manner as in 2 above, and the durability of the PET film and the photocatalyst coating film was evaluated. If the durability is inferior, the haze value is increased, and the photocatalytic coating film is peeled off as the deterioration further proceeds.
4). Photocatalytic activity (decomposition index)
A wet decomposition performance test of the photocatalyst coating film was performed in accordance with JIS R 1703-2, and a decomposition index was obtained from the absorbance at a wavelength of 664 nm. At this time, methylene blue trihydrate manufactured by Wako Pure Chemical Industries, Ltd. was used as methylene blue. For the measurement of absorbance, an ultraviolet / visible spectrophotometer (trade name “V-550”) manufactured by JASCO Corporation was used.

[Production Example 1]
(Create water-based binder)
A reactor having a reflux condenser, a dropping tank, a thermometer, and a stirring device was charged with 400 g of ion-exchanged water and 2.57 g of a 10% by mass dodecylbenzenesulfonic acid aqueous solution, and then heated to 80 ° C. with stirring. did. In this reactor, 54.5 g of dimethyldimethoxysilane, 34.4 g of phenyltrimethoxysilane, and 1.0 g of methyltrimethoxysilane and 15.0 g of a 2% by weight aqueous solution of ammonium persulfate were added to the reactor. It was dripped simultaneously over about 2 hours in the state which maintained temperature at 80 degreeC. Thereafter, stirring was continued for about 1 hour while maintaining the temperature in the reactor at 80 ° C. Next, 12.3 g of butyl acrylate, 13.5 g of phenyltrimethoxysilane, 31.4 g of tetraethoxysilane and 1.2 g of 3-methacryloxypropyltrimethoxysilane, 24.6 g of diethylacrylamide, and 1 g of acrylic acid , Reactive emulsifier (trade name “Adekaria Soap SR-1025”, manufactured by Asahi Denka Co., Ltd., 25% solids aqueous solution), reactive emulsifier (trade name “AQUALON KH-1025”, Daiichi Kogyo Seiyaku Co., Ltd. (Made by Co., Ltd., 25% solid content aqueous solution) 0.7 g, a mixed solution of 2% by weight ammonium persulfate aqueous solution 8.5 g and ion-exchanged water 255 g, with the temperature in the reactor kept at 80 ° C. It was dripped simultaneously over 2 hours. Further, stirring was continued for about 2 hours while maintaining the temperature in the reactor at 80 ° C. Thereafter, the liquid in the reactor was cooled to room temperature and filtered through a 100-mesh wire mesh to obtain a polymer emulsion aqueous dispersion having a solid content of 12.8% by mass. And it adjusted so that solid content might be 10.0 mass% with ion-exchange water, and obtained the polymer emulsion water dispersion (a). The number average particle diameter of the polymer emulsion particles was 183 nm.

  100 g of the obtained polymer emulsion dispersion (a) and 50 g of water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, trade name “Snowtex O”, solid content 20% by mass) are mixed, and an aqueous binder aqueous dispersion ( A) was prepared.

[Example 1]
1.67 g of rutile type titanium oxide (made by Ishihara Sangyo Co., Ltd., trade name “TTO-W-05”, solid content 30% by mass) and anatase type titanium oxide (Ishihara Sangyo Co., Ltd.) with respect to the aqueous binder aqueous dispersion (A) (Product name “MPT-422”, solid content 20 mass%) 2.5 g was mixed to prepare a photocatalyst composition. This photocatalyst composition was applied to the surface of a 20 cm square PET film (film thickness: 90 μm) by a bar coating method and dried at 70 ° C. for 10 minutes to obtain a photocatalyst coating film having a film thickness of 2.1 μm. Various evaluation results are shown in Table 1. In Table 1, “rutile-type titanium oxide amount (%)” indicates the content ratio (unit: mass%) of rutile-type titanium oxide with respect to the total amount of the photocatalytic coating film, and “anatase-type titanium oxide amount (%)”. Indicates the content ratio (unit: mass%) of anatase-type titanium oxide with respect to the total amount of the photocatalytic coating film. “Transparency” and “transparency after light resistance test” both indicate haze values.

[Examples 2-6, Comparative Examples 1-5]
A photocatalyst coating film was obtained in the same manner as in Example 1 except that the content ratio of rutile type titanium oxide and anatase type titanium oxide with respect to the total amount of the photocatalyst coating film was changed as shown in Table 1. Various evaluation results are shown in Table 1. In Table 1, “-” means that the photocatalyst coating film does not contain rutile titanium oxide and / or anatase titanium oxide. “Peeling” indicates that the photocatalyst coating film was peeled from the PET film.

  The photocatalyst coating film of the present embodiment is a photocatalyst coating film that achieves both photocatalytic activity and durability of the substrate, and can be cured with a small environmental load. It is useful to be applied to the like.

Claims (7)

A photocatalytic coating film comprising a rutile type titanium oxide and a compound exhibiting high photocatalytic activity, wherein the content ratio of the rutile type titanium oxide satisfies a condition represented by the following formula (1).
4 / X ≦ a ≦ 100 / X (1)
(In the formula, X represents the film thickness (unit: μm) of the photocatalytic coating film, and a represents the content ratio (unit: mass%) of the rutile-type titanium oxide with respect to the total amount of the photocatalytic coating film.) The photocatalyst coating film of Claim 1 with which the content rate of the said rutile type titanium oxide satisfies the conditions represented by a following formula (1a).
4 / X ≦ a ≦ 60 / X (1a)
(In the formula, X represents the film thickness (unit: μm) of the photocatalytic coating film, and a represents the content ratio (unit: mass%) of the rutile-type titanium oxide with respect to the total amount of the photocatalytic coating film.)   The photocatalyst coating film of Claim 1 or 2 whose mass ratio of the compound which shows the said high photocatalytic ability with respect to the said rutile type titanium oxide is 0.10-2.0.   The photocatalyst coating film as described in any one of Claims 1-3 whose particle diameter of the compound which shows the said rutile type titanium oxide and the said high photocatalytic ability is 100 nm or less in both primary particle diameters.   The photocatalyst coating film as described in any one of Claims 1-4 whose compound which shows the said high photocatalytic capability is anatase type titanium oxide.   The photocatalyst coating film as described in any one of Claims 1-5 containing an aqueous binder.   The photocatalyst composition used in order to form the photocatalyst coating film as described in any one of Claims 1-6.