JP6283922B1 - Photocatalyst material and photocatalyst coating composition - Google Patents

Abstract

The present invention provides a photocatalyst material having high antimicrobial properties and capable of exhibiting algae-proofing property for a long period of time, and a photocatalyst coating composition for forming the photocatalyst material. A photocatalyst material 100 includes a base material 10 and a photocatalyst layer 20 provided on one surface of the base material. The photocatalyst layer includes photocatalyst particles 21, copper compound particles 22 containing at least a divalent copper ion compound, inorganic particles 23 having no photocatalytic activity, and a binder 24, with respect to 100 parts by mass of the photocatalyst particles. The copper in the copper compound particles is 0.1 to 5 parts by mass. The photocatalyst coating composition contains photocatalyst particles, a copper compound containing at least a divalent copper ion compound, inorganic particles not having photocatalytic activity, and a binder precursor, and is based on 100 parts by mass of the photocatalyst particles. The copper inside is 0.1 to 5 parts by mass. [Selection] Figure 1

Description

  The present invention relates to a photocatalyst material and a photocatalyst coating composition. Specifically, the present invention relates to a photocatalyst material having antimicrobial properties and capable of suppressing the growth of algae, and a photocatalyst coating composition for obtaining the photocatalyst material.

A variety of antimicrobial members that reduce microorganisms in the living environment have been developed and commercialized due to the improvement of consumer cleanliness. For example, since photocatalysts such as titanium oxide (TiO ₂ ) utilize light energy and exhibit an excellent purification and sterilization effect, various products having antifouling, sterilization, and deodorizing effects have been put into practical use. In addition, since titanium oxide exhibits a self-cleaning effect due to super hydrophilicity and photodecomposition reaction, application to exterior materials is being studied.

  In recent years, added value such as an anti-algae function has been strongly demanded as an antifouling function. However, regarding the algal control function, it has become clear that the effect of titanium oxide alone is weak. That is, as described above, since titanium oxide exhibits superhydrophilicity when irradiated with ultraviolet rays, it has been reported that the surface is more easily moisturized than ordinary exterior materials, and algae and the like are easily propagated. Therefore, in addition to titanium oxide, addition of metals having antimicrobial properties such as silver and copper has been studied.

  For example, Patent Document 1 discloses a sol containing crystalline titanium oxide and a copper ion compound complexed with an alkanolamine as main components, and by applying the sol, an antibacterial function is imparted to various products. It describes what you can do. As described above, in Patent Document 1, as a material that has high safety during production and use, has long-term stability, and can impart high antimicrobial properties to crystalline titanium oxide, it is complexed into a solution. Copper with improved stability is applied.

Japanese Patent No. 4356951

  In Patent Document 1, copper complexed with alkanolamine exists as copper oxide or copper hydroxide, and these are high antibacterial factors. However, since the periphery of copper is coated with alkanolamine, the contact with bacteria is hindered and the antibacterial performance may be lowered. In fact, Patent Document 1 describes that when the molar ratio of alkanolamine / copper ion compound (CuO) is 5.8 or higher, the antibacterial performance decreases although the reason is not clear.

  Further, the degree of elution into a water or dilute acid differs depending on the valence and counter ion of the copper ion compound. Therefore, when using a copper ion compound outdoors, the influence of acid rain etc. must be considered. In particular, since the monovalent copper ion compound is soluble in an acid, it is eluted when used outdoors, and the antimicrobial performance may be lowered in the long term.

  The present invention has been made in view of such problems of the prior art. An object of the present invention is to provide a photocatalyst material that has high antimicrobial properties and that can exhibit algae-proofing properties over a long period of time, and a photocatalyst coating composition for obtaining the photocatalyst material. It is in.

In order to solve the above-mentioned subject, the photocatalyst material concerning the 1st mode of the present invention has a base material and a photocatalyst layer provided in one side of a base material. The photocatalyst layer includes photocatalyst particles, copper compound particles containing at least one of copper oxide (II) and copper hydroxide (II), inorganic particles not having photocatalytic activity, and inorganic binder, The copper in the copper compound particles is 0.1 to 5 parts by mass with respect to 100 parts by mass, and the copper compound particles are supported so as to be in contact with the surfaces of the photocatalyst particles and the inorganic particles. diameter of 50 nm to 200 nm, the average particle size of the copper compound particles 0.1Nm～20nm, average particle diameter of the inorganic particles Ru 5nm~100nm der.

The photocatalyst coating composition according to the second aspect of the present invention is a photocatalyst coating composition for forming a photocatalyst layer in a photocatalyst material, comprising photocatalyst particles, copper oxide (II) and copper hydroxide (II). A copper compound containing at least a divalent copper ion compound, inorganic particles having no photocatalytic activity, and an inorganic binder precursor, and the copper in the copper compound is contained in 100 parts by mass of the photocatalytic particles. 0.1 to 5 parts by mass.

  According to the present invention, it is possible to obtain a photocatalyst material having high antimicrobial properties and capable of exhibiting antialgae properties for a long period of time, and a photocatalyst coating composition for forming the photocatalyst material. .

It is the schematic which shows the cross section of the photocatalyst material which concerns on embodiment of this invention.

  Hereinafter, the photocatalyst material and the photocatalyst coating composition according to the present embodiment will be described in detail. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

[Photocatalyst material]
As shown in FIG. 1, the photocatalyst material 100 according to the present embodiment includes a base material 10 and a photocatalyst layer 20 provided on one surface of the base material 10. The photocatalyst layer 20 includes photocatalyst particles 21, copper compound particles 22 containing at least a divalent copper ion compound, inorganic particles 23 having no photocatalytic activity, and a binder 24.

  In this embodiment, the base material 10 is not specifically limited, The member which can hold | maintain the photocatalyst layer 20 on the surface can be used. The material used for the substrate may be rigid or flexible. The photocatalyst material 100 of the present embodiment is preferably applied to a building exterior material. In that case, the base material may be any commercially available exterior material. Furthermore, a color layer for coloring, a color fading preventing layer for suppressing color change of the color layer, and the like may be present on the surface of the exterior material as the base material. In addition, a functional layer may be provided on the exterior material as necessary.

  Although the photocatalyst material of the present embodiment can suppress the growth of algae, it can also suppress the growth of other microorganisms as an application. The photocatalyst material can suppress the propagation of bacteria and fungi, for example. Therefore, for these microorganisms, it is assumed that the photocatalyst layer 20 is formed on a transparent film or the like, and the photocatalyst coating composition may be directly applied to the building material.

  The specific material of the substrate may basically be anything such as organic polymer, ceramic, metal, glass, plastic, decorative plywood or a composite thereof. The shape of the substrate is not particularly limited. For example, it may be a simple or complex shape such as a plate-like object, a spherical object, a columnar object, a cylindrical object, a rod-like object, a prismatic object, or a hollow prismatic object. Good. The substrate may be a porous body such as a filter. Specifically, building materials such as tiles, glass, wall materials, floors, and exterior materials can be used as the base material.

  The photocatalyst layer 20 includes photocatalyst particles 21, copper compound particles 22, inorganic particles 23 having no photocatalytic activity, and a binder 24. The photocatalyst particles 21, the copper compound particles 22, and the inorganic particles are contained inside the binder 24. The particles 23 are highly dispersed. As shown in FIG. 1, the copper compound particles 22 are supported so as to be in contact with the surfaces of the photocatalyst particles 21 and the inorganic particles 23. The particle diameter of the copper compound particles 22 is smaller than the particle diameters of the photocatalyst particles 21 and the inorganic particles 23.

  The copper compound particles 22 need not be supported on the surfaces of the photocatalyst particles 21 and the inorganic particles 23, and may be dispersed inside the binder 24 so as not to contact the photocatalyst particles 21 and / or the inorganic particles 23. Good. Further, the particle diameter of the copper compound particles 22 may be larger than the particle diameters of the photocatalyst particles 21 and the inorganic particles 23. As shown in FIG. 1, the photocatalyst particles 21 and the inorganic particles 23 may be in contact with each other inside the binder 24 or may be separated from each other.

The photocatalyst particle 21 may be a compound that generates electrons and holes by absorption of excitation light having energy greater than or equal to the band gap and causes a reduction / oxidation reaction on the surface of the photocatalyst particle. Examples of such photocatalytic particles include titanium oxide (TiO ₂ ), tungsten oxide (WO ₃ ), strontium titanate (SrTiO ₃ ), niobium oxide (Nb ₂ O ₃ ), zinc oxide (ZnO), and tin oxide (SnO ₂ ). ) And the like. These photocatalyst particles may be used alone or in combination of two or more.

  When it is assumed that the photocatalyst material 100 is used as an exterior material, the photocatalyst layer 20 preferably has high transparency so as not to lose the color of the color layer that is the base layer. For this reason, the photocatalyst particles 21 preferably include titanium oxide particles, and more preferably titanium oxide particles. Since titanium oxide has a very high photocatalytic activity, it can exert an effect of suppressing the growth of algae by oxidative decomposition reaction. Moreover, since titanium oxide particles are inexpensive and harmless and are white, they can be suitably used for exterior materials. Furthermore, since the titanium oxide particles are super hydrophilic, dirt such as algae can be washed away by rain. Since titanium oxide is also commercially available in a sol state, it is possible to simplify the manufacturing process by using a sol state material in advance.

  As titanium oxide particles preferable as the photocatalyst particles, particles made of anatase type or rutile type titanium oxide can be used. Moreover, the particle | grains which anatase type titanium oxide and rutile type titanium oxide mixed can also be used. However, it is preferable to use anatase-type titanium oxide particles as the titanium oxide. This is because anatase-type titanium oxide has a larger band gap and excellent photocatalytic activity than rutile-type titanium oxide.

  The anatase-type titanium oxide particles may be mixed with amorphous titanium oxide. However, since amorphous titanium oxide has a poor photocatalytic activity, the amount of mixing is preferably as small as possible.

In the photocatalyst layer 20, the average particle diameter of the photocatalyst particles 21 is not particularly limited, but is preferably 50 nm to 200 nm. When the average particle diameter of the photocatalyst particles 21 is 50 nm or more, the destruction of the crystal structure in the photocatalyst particles 21 is suppressed, and the photocatalytic activity and antimicrobial properties can be enhanced. When the average particle diameter of the photocatalyst particles 21 is 200 nm or less, the photocatalyst particles have a high specific surface area, so that high photocatalytic activity can be exhibited. In addition, the average particle diameter of the photocatalyst particle 21 can be calculated | required by measuring the diameter of the some photocatalyst particle 21 using a transmission electron microscope (TEM), for example.

  The copper compound particles 22 contained in the photocatalyst layer 20 contain at least a divalent copper ion compound. Since the divalent copper ion compound has a protein denaturing action, it can suppress the growth of algae on the surface of the photocatalyst layer 20. The divalent copper ion compound contained in the copper compound particles 22 is not particularly limited, and preferably includes at least one of copper (II) oxide and copper (II) hydroxide, and includes copper (II) hydroxide. More preferred. Since copper hydroxide (II) is difficult to dissolve in water and dilute acid, it becomes possible to continue exhibiting alga-proof performance for a long time even outdoors exposed to rainwater.

  In the present embodiment, it is preferable that the photocatalyst layer 20 further includes monovalent copper ion compound particles. That is, the copper compound particles 22 are preferably formed by mixing monovalent copper ion compound particles and divalent copper ion compound particles. In general, monovalent copper ion compounds are known to have higher antimicrobial properties and in particular antibacterial and antiviral properties than divalent copper ion compounds. Similarly, since the monovalent copper ion compound has a very high algal reproduction suppression effect, the presence of monovalent copper ion compound particles containing the monovalent copper ion compound further suppresses the algal reproduction. It becomes possible. The monovalent copper ion compound particles are preferably particles containing at least one of copper oxide (I) (cuprous oxide) and copper hydroxide (I).

The monovalent copper ion compound particles preferably contain cuprous oxide particles. By containing cuprous oxide (Cu ₂ O) having a particularly high antimicrobial property among monovalent copper ion compounds, it becomes possible to further suppress the growth of algae.

  In the photocatalyst layer 20, the average particle diameter of the copper compound particles 22 is not particularly limited, but is preferably 0.1 nm to 20 nm. When the average particle diameter of the copper compound particles 22 is within this range, the copper compound particles 22 have a high specific surface area, so that the copper ions are efficiently eluted and the effect of suppressing the growth of algae can be exhibited. . Further, since the copper compound particles 22 have a high specific surface area, it is possible to impart high antimicrobial properties to the photocatalyst layer 20 even if the addition amount is small. In addition, the average particle diameter of the copper compound particle | grains 22 can be calculated | required by measuring the diameter of the several copper compound particle | grains 22 using a transmission electron microscope (TEM), for example.

  As described above, the photocatalyst layer 20 according to the present embodiment contains the photocatalyst particles 21 and the copper compound particles 22 containing a divalent copper ion compound, so that the oxidative decomposition action of the photocatalyst and the protein of the copper ion compound can be obtained. Denaturing action is exerted. As a result, it is possible to obtain the photocatalyst material 100 that has antimicrobial properties and that can particularly suppress the growth of algae. However, when the photocatalyst particles 21 and the copper compound particles 22 coexist in the photocatalyst layer 20, electrons are injected from the photocatalyst particles 21 excited by the excitation light into the copper compound particles 22, and as a result, a divalent copper ion compound is formed. It may be reduced to a monovalent copper ion compound. A monovalent copper ion compound has a property of being gradually oxidized to be a divalent copper ion compound when left in the air for a long time. Therefore, when the photocatalyst particles 21 and the copper compound particles 22 coexist, the copper ion compound causes a reaction that repeats monovalent and divalent.

  And as above-mentioned, since a monovalent | monohydric copper ion compound has a high protein denaturation effect | action compared with a bivalent copper ion compound, it is excellent in antimicrobial property. Therefore, when the copper compound particle 22 consists only of a monovalent | monohydric copper ion compound, it is estimated that the photocatalyst layer 20 has high algae-proof property. However, since a monovalent copper ion compound is soluble in an acid, when it is used outdoors, it elutes due to the influence of acid rain and the like, and the antimicrobial property is lowered in the long term. Therefore, when the copper compound particles 22 are composed of only a monovalent copper ion compound, it is difficult to expect long-term anti-algae properties.

  Therefore, the photocatalyst layer 20 of this embodiment contains the inorganic particle 23 which does not have photocatalytic activity. By containing the inorganic particles 23, the copper compound particles 22 present on the surface of the inorganic particles 23 can maintain the state of a divalent copper ion compound. That is, even if electrons are injected from the photocatalyst particles 21 excited by the excitation light into the copper compound particles 22, they are inhibited by the inorganic particles 23, so that the copper compound particles 22 maintain the state of a divalent copper ion compound. Is possible. And a bivalent copper ion compound is hard to melt | dissolve in water or a dilute acid compared with a monovalent copper ion compound. As a result, even if the photocatalyst layer 20 is used outdoors, the copper compound particles 22 are less likely to elute due to the influence of acid rain, and thus can exhibit antimicrobial properties over a long period of time.

  In the photocatalyst layer 20 of the present embodiment, the copper compound particles 22 need to contain at least a divalent copper ion compound from the viewpoint of maintaining long-term antimicrobial properties. However, when the copper compound particles 22 contain a monovalent copper ion compound in addition to the divalent copper ion compound, long-term and high antimicrobial properties can be obtained.

The inorganic particles 23 are not particularly limited as long as they do not have photocatalytic activity, but are composed of silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and barium sulfate (BaSO ₄ ). At least one selected from the group can be used. Moreover, when the use with an exterior material is assumed, in order not to lose the color of the color layer which is an underlayer, it is preferable that the photocatalyst layer 20 has high transparency. Therefore, by using a sol-state material in advance as the inorganic particles 23, it is possible to further simplify the manufacturing process while ensuring transparency.

  In the photocatalyst layer 20, the average particle diameter of the inorganic particles 23 is not particularly limited, but is preferably 5 nm to 100 nm. When the average particle diameter of the inorganic particles 23 is within this range, injection of electrons from the photocatalyst particles 21 to the copper compound particles 22 is suppressed, and the copper compound particles 22 on the surface of the inorganic particles 23 are divalent for a long period. Can be maintained. In addition, the average particle diameter of the inorganic particle 23 can be calculated | required by measuring the diameter of the some inorganic particle 23, for example using a transmission electron microscope (TEM).

  The photocatalyst layer 20 of the present embodiment contains a binder 24 in order to bind and hold the photocatalyst particles 21, the copper compound particles 22 and the inorganic particles 23 in a highly dispersed state. The material of the binder 24 is not particularly limited as long as it does not hinder the action of the photocatalyst particles 21, the copper compound particles 22, and the inorganic particles 23. As the binder 24, an organic binder made of an organic compound or an inorganic binder made of an inorganic compound can be used. As the binder 24, an organic-inorganic hybrid binder obtained by combining an organic component and an inorganic component from the molecular level to the nano level can also be used. However, when it is assumed that the photocatalyst material 100 is used as an exterior material, long-term weather resistance is required. Therefore, the binder 24 is preferably an inorganic binder.

The inorganic binder is not particularly limited, but at least one selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titania (TiO ₂ ), and zirconia (ZrO ₂ ) can be used. The inorganic binder is preferably obtained by hydrolysis and polycondensation by heating an organic alkoxide that is a binder precursor.

  When the inorganic binder is made of silica, alkoxysilane is preferably used as the binder precursor. The alkoxysilane is not particularly limited. For example, tetraethoxysilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrisilane. Methoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, and the like can be used. When the inorganic binder is made of alumina, it is preferable to use aluminum alkoxide as the binder precursor. The aluminum alkoxide is not particularly limited, and aluminum ethoxide, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, and the like can be used.

  When the inorganic binder is composed of titania, it is preferable to use titanium alkoxide as the binder precursor. The titanium alkoxide is not particularly limited, and titanium isopropoxide, titanium butoxide, and the like can be used. When the inorganic binder is made of zirconia, it is preferable to use zirconium alkoxide as the binder precursor. The zirconium alkoxide is not particularly limited, and zirconium methoxide, zirconium ethoxide, zirconium propoxide, zirconium isopropoxide, zirconium n-butoxide, zirconium sec-butoxide, zirconium tert-butoxide, and the like can be used. These organic alkoxides may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the photocatalyst layer 20 of this embodiment, it is preferable that the copper in a copper compound particle is 0.1-5 mass parts with respect to 100 mass parts of photocatalyst particles, and it is more preferable that it is 0.1-1 mass part. . When the copper in the copper compound particles is 0.1 parts by mass or more, the antimicrobial performance can be efficiently exhibited. Moreover, when the copper in the copper compound particles is 5 parts by mass or less, coloring of the photocatalyst layer 20 can be suppressed, and appearance problems such as a color change of the photocatalyst material 100 can be solved. In the present specification, the content ratio of the copper compound particles in the photocatalyst layer 20 is calculated after converting the copper compound particles into the mass of copper alone.

  Although the thickness of the photocatalyst layer 20 in the photocatalyst material 100 is not particularly limited, the thickness after curing is preferably 0.5 μm to 20 μm, and more preferably 2 μm to 10 μm. When the thickness of the photocatalyst layer 20 is within this range, the surface hardness of the cured film is improved and high weather resistance can be obtained.

  Thus, the photocatalyst material 100 of this embodiment includes the base material 10 and the photocatalyst layer 20 provided on one surface of the base material 10. The photocatalyst layer 20 includes photocatalyst particles 21, copper compound particles 22 containing at least a divalent copper ion compound, inorganic particles 23 having no photocatalytic activity, and a binder 24, and 100 parts by mass of the photocatalyst particles. On the other hand, the copper in a copper compound particle is 0.1-5 mass parts. The photocatalyst material 100 has a structure including, in addition to the photocatalyst particles 21, inorganic particles 23 having no photocatalytic activity, and copper compound particles 22 containing a divalent copper ion compound and exposed on the surface. As a result, it is possible to obtain the photocatalyst material 100 having high antimicrobial properties and capable of exhibiting particularly high algal resistance.

  That is, the copper compound particles 22 are affected by both the reduction reaction by the photocatalyst and the oxidation reaction by water or oxygen in the atmosphere, and can take both monovalent and divalent. The monovalent copper ion compound greatly contributes to the algaeproofing performance, but it is difficult to expect long-term algaeproofing properties by eluting with dilute acid. On the other hand, the copper compound particles 22 present on the surface of the inorganic particles 23 having no photocatalytic activity can maintain a divalent state. And since a bivalent copper ion compound does not melt | dissolve in water or a dilute acid, it becomes possible to continue exhibiting algae-proof performance for a long term also in the outdoors exposed to rainwater.

  As described above, the photocatalyst material 100 according to the present embodiment obtains the effect of high antialgae property by the photocatalyst particles 21, high algaeproof property by the monovalent copper ion compound, and long-term antialgae effect by the divalent copper ion compound. be able to. In the photocatalyst material 100 of FIG. 1, the photocatalyst layer 20 is provided on one surface of the base material 10, but the photocatalyst layer 20 is also provided on the other surface on the opposite side of the one surface. Also good.

[Production method of photocatalyst material and photocatalyst coating composition]
Next, the manufacturing method of a photocatalyst material and the photocatalyst coating composition used when manufacturing a photocatalyst material are demonstrated.

  The photocatalyst material 100 of this embodiment can be obtained by applying a photocatalyst coating composition to the substrate 10 and drying it. And the photocatalyst coating composition contains photocatalyst particles, a copper compound containing at least a divalent copper ion compound, inorganic particles not having photocatalytic activity, and a binder precursor, Copper in a copper compound is 0.1-5 mass parts.

  The photocatalyst coating composition can be prepared by mixing the above-mentioned photocatalyst particles, copper compound, inorganic particles, and a binder precursor, and highly dispersing them. Moreover, in order to disperse | distribute photocatalyst particle, a copper compound, an inorganic particle, and a binder precursor highly, a solvent may be added as needed.

  For example, water or an organic solvent is preferably used as the solvent. The organic solvent is not particularly limited, but it is preferable to appropriately select an organic solvent that volatilizes easily when the photocatalyst layer 20 is formed and that does not cause curing inhibition when the photocatalyst layer 20 is formed. Examples of the organic solvent include aromatic hydrocarbons (such as toluene and xylene), alcohols (such as methanol, ethanol, and isopropyl alcohol), and ketones (such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone). Furthermore, aliphatic hydrocarbons (such as hexane and heptane), ethers (such as tetrahydrofuran), and amide solvents (such as N, N-dimethylformamide (DMF) and dimethylacetamide (DMAc)) may be mentioned. Of these, alcohols are preferred. These organic solvents may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the method for producing the photocatalyst coating composition, any method can be used as long as the photocatalyst particles, the copper compound and the inorganic particles can be highly dispersed together with the binder precursor. For example, the photocatalytic coating composition can be prepared by stirring using a general dissolver. In addition, ball mills, bead mills, sand mills, horizontal media mill dispersers, colloid mills, and the like using bead media such as glass and zircon can also be used. As a medium used in the bead mill, a bead medium having a diameter of 1 mm or less is preferable, and a bead medium having a diameter of 0.5 mm or less is more preferable.

  Next, the obtained photocatalyst coating composition is applied to one surface of the substrate 10. The coating method at this time is not particularly limited. As a method for applying the photocatalyst coating composition, a coating method or a printing method can be used. As the coating method, a spray method, a bar coating method, a dip coating method, or the like can be used. In the printing method, gravure printing, reverse gravure printing, offset printing, flexographic printing, screen printing, and the like can be used.

  And the photocatalyst material 100 can be obtained by heating the base material 10 which apply | coated the photocatalyst coating composition, and removing a solvent. The heating conditions at this time are not particularly limited, but when an organic alkoxide is used as the binder precursor, it is preferable to heat at a temperature at which the organic alkoxide is hydrolyzed and polycondensed to produce an inorganic binder. Therefore, when heating the base material 10 to which the photocatalyst coating composition is applied, it is preferably heated at 150 to 200 ° C. in the air.

  When preparing the photocatalyst coating composition, it is preferable to use a sol for the photocatalyst particles and the inorganic particles. By using a sol as the photocatalyst particles and the inorganic particles, a photocatalyst material in which the photocatalyst particles and the inorganic particles are highly dispersed in the binder and exhibit high microbial properties in the long term can be obtained.

  As the copper compound added to the photocatalyst coating composition, it is preferable to use a compound that dissolves in water. Specifically, at least one selected from the group consisting of copper chloride, copper acetate, copper chlorate, copper perchlorate, copper formate, copper bromide, copper nitrate and copper sulfate can be used as the copper compound. . And when preparing a photocatalyst coating composition, it is more preferable to add the aqueous solution of a copper compound using photocatalyst particle sol and inorganic particle sol. Thereby, it becomes possible to easily carry the copper compound particles 22 on the surfaces of the photocatalyst particles 21 and the inorganic particles 23 of the photocatalyst layer 20. Specifically, by adding an aqueous solution in which a copper compound is dissolved to the photocatalyst particle sol and the inorganic particle sol, copper ions adhere to the surfaces of the photocatalyst particles and the inorganic particles as the photocatalyst coating composition is heated and dried. To do. Since the adhered copper ions become, for example, particles of copper hydroxide or copper oxide, a photocatalyst material having long-term durability can be easily obtained.

  In preparing the photocatalyst coating composition, the photocatalyst particle sol, the inorganic particle sol, and the copper compound aqueous solution are not essential materials. For example, the photocatalyst coating composition can also be obtained by mixing powdery photocatalyst particles, inorganic particles and copper compound particles together with a binder precursor and highly dispersing them. At this time, the photocatalytic coating composition may further contain a monovalent copper ion compound. Thereby, since the obtained photocatalyst material 100 will contain a monovalent | monohydric copper ion compound in addition to a bivalent copper ion compound, it will become possible to acquire long-term and high antimicrobial property. The monovalent copper ion compound is selected from the group consisting of copper oxide (I) (cuprous oxide), copper sulfide (I), copper iodide (I), copper chloride (I), and copper hydroxide (I). It is preferable that it is at least one.

  Moreover, in a photocatalyst coating composition, it is preferable that the copper in a copper compound is 0.1-5 mass parts with respect to 100 mass parts of photocatalyst particles. Thereby, in photocatalyst layer 20 of photocatalyst material 100 concerning this embodiment, it becomes possible to make content of copper compound particle 22 into the above-mentioned range.

  Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to these examples.

In the examples and comparative examples, the following were used as the raw material TiO ₂ sol, SiO ₂ dispersion, copper ion compound, and silicate binder precursor. As the TiO ₂ sol, an average particle diameter (D50) of TiO ₂ measured by a small-angle X-ray scattering method using a photocatalytic titanium oxide aqueous dispersion STS-21 manufactured by Ishihara Sangyo Co., Ltd. was 20 nm. As the SiO ₂ dispersion, AERODISP (registered trademark) W7520 manufactured by EVONIK was used. As the copper ion compound, copper chloride manufactured by Wako Pure Chemical Industries, Ltd. was used. Copper chloride was dissolved in ion-exchanged water and used as a copper ion aqueous solution. As the silicate binder precursor, Shin-Etsu Chemical Co., Ltd. product name KEB-04 (tetraethoxysilane) was used. In addition, since the above-mentioned commercially available material has high solid content concentration, ion-exchange water, alcohol, etc. were added as a solvent, and solid content concentration was adjusted and used.

[Example 1]
First, a TiO ₂ sol, a SiO ₂ dispersion, a copper ion compound, and a silicate binder precursor were mixed in this order. At this time, every time a new material was added, it was sufficiently stirred. This obtained the photocatalyst coating composition of this example. In the photocatalyst coating composition, the solid content concentration of TiO ₂ was 0.3 mass%, the solid content concentration of SiO ₂ was 0.5 mass%, and the solid content concentration of the copper ion compound was converted to copper. Each was mixed so that it might become 0.003 mass%. Further, the silicate binder precursor was mixed so that the solid content concentration was 0.2% by mass.

Next, the obtained photocatalyst coating composition was applied to the surface of the anodized plate by a spray method and dried at 200 ° C. for 30 minutes. At this time, the film was formed so that the film thickness of the photocatalyst layer was about 3 μm. The alumite plate used was 70 mm long and 150 mm wide. Thus, the photocatalyst material of this example in which the photocatalyst layer was formed on the alumite plate was obtained. In the photocatalyst layer of the present embodiment, with respect to TiO 2 ₁₀₀ parts by weight of a photocatalyst particles, copper oxide copper particles is 1 part by mass.

[Example 2]
When the solid content concentration of TiO ₂ is 0.3 mass%, the solid content concentration of SiO ₂ is 0.5 mass%, and the solid content concentration of the copper ion compound is converted to copper, 0.0003 mass%, a silicate binder precursor Each was mixed so that the solid content concentration was 0.2 mass%. Other than that was carried out similarly to Example 1, and obtained the photocatalyst material of this example. In the photocatalyst layer of the present embodiment, with respect to TiO 2 ₁₀₀ parts by weight of a photocatalyst particles, copper oxide copper particles is 0.1 part by mass.

[Example 3]
When the solid content concentration of TiO ₂ is 0.3 mass%, the solid content concentration of SiO ₂ is 0.5 mass%, and the solid content concentration of the copper ion compound is converted to copper, 0.015 mass%, a silicate binder precursor Each was mixed so that the solid content concentration was 0.2 mass%. Other than that was carried out similarly to Example 1, and obtained the photocatalyst material of this example. In the photocatalyst layer of the present embodiment, with respect to TiO 2 ₁₀₀ parts by weight of a photocatalyst particles, copper oxide copper particles is 5 parts by mass.

[Comparative Example 1]
When the solid content concentration of TiO ₂ is 0.3 mass%, the solid content concentration of SiO ₂ is 0.5 mass%, and the solid content concentration of the copper ion compound is converted to copper, 0.00003 mass%, a silicate binder precursor Each was mixed so that the solid content concentration was 0.2 mass%. Other than that was carried out similarly to Example 1, and obtained the photocatalyst material of this example. In the photocatalyst layer of the present embodiment, with respect to TiO 2 ₁₀₀ parts by weight of a photocatalyst particles, copper oxide copper particles is 0.01 parts by weight.

[Comparative Example 2]
When the solid content concentration of TiO ₂ is 0.3 mass%, the solid content concentration of SiO ₂ is 0.5 mass%, and the solid content concentration of the copper ion compound is converted to copper, 0.03 mass%, a silicate binder precursor Each was mixed so that the solid content concentration was 0.2 mass%. Other than that was carried out similarly to Example 1, and obtained the photocatalyst material of this example. In the photocatalyst layer of this example, copper of the copper oxide particles is 10 parts by mass with respect to 100 parts by mass of TiO ₂ that is the photocatalyst particles.

[Comparative Example 3]
First, the same TiO ₂ sol, copper ion compound and silicate binder precursor as in Example 1 were mixed in this order. At this time, every time a new material was added, it was sufficiently stirred. This obtained the photocatalyst coating composition of this example. In the photocatalyst coating composition, the solid content concentration of TiO ₂ is 0.8% by mass, and the solid content concentration of the copper ion compound is 0.003% by mass when converted as copper, and the solid content concentration of the silicate binder precursor. Each was mixed so that 0.2% by mass.

Next, the obtained photocatalyst coating composition was applied to the surface of the alumite plate in the same manner as in Example 1, and dried at 200 ° C. for 30 minutes. At this time, the film was formed so that the film thickness of the photocatalyst layer was about 3 μm. Further, the same alumite plate as in Example 1 was used. Thus, the photocatalyst material of this example in which the photocatalyst layer was formed on the alumite plate was obtained. In the photocatalyst layer of the present embodiment, with respect to _TiO 2 100 parts by weight of a photocatalyst particles, copper oxide copper particles is 0.375 parts by weight.

[Comparative Example 4]
First, the same SiO ₂ dispersion, copper ion compound and silicate binder precursor as in Example 1 were mixed in this order. At this time, every time a new material was added, it was sufficiently stirred. This obtained the photocatalyst coating composition of this example. In the photocatalyst coating composition, the solid content concentration of SiO ₂ is 0.8 mass%, and the solid content concentration of the copper ion compound is 0.003 mass% when converted to copper, and the solid content concentration of the silicate binder precursor. Each was mixed so that 0.2% by mass.

  Next, the obtained photocatalyst coating composition was applied to the surface of the alumite plate in the same manner as in Example 1, and dried at 200 ° C. for 30 minutes. At this time, the film was formed so that the film thickness of the photocatalyst layer was about 3 μm. Further, the same alumite plate as in Example 1 was used. Thus, the photocatalyst material of this example in which the photocatalyst layer was formed on the alumite plate was obtained.

[Comparative Example 5]
First, the same TiO ₂ sol and silicate binder precursor as in Example 1 were mixed by being sufficiently stirred. This obtained the photocatalyst coating composition of this example. In the photocatalyst coating composition, the solid content concentration of TiO ₂ was 0.8 mass%, and the solid content concentration of the silicate binder precursor was 0.2 mass%.

  Next, the obtained photocatalyst coating composition was applied to the surface of the alumite plate in the same manner as in Example 1, and dried at 200 ° C. for 30 minutes. At this time, the film was formed so that the film thickness of the photocatalyst layer was about 3 μm. Further, the same alumite plate as in Example 1 was used. Thus, the photocatalyst material of this example in which the photocatalyst layer was formed on the alumite plate was obtained.

[Comparative Example 6]
First, the same TiO ₂ sol, SiO ₂ dispersion, and silicate binder precursor as in Example 1 were mixed in this order. At this time, every time a new material was added, it was sufficiently stirred. This obtained the photocatalyst coating composition of this example. In the photocatalyst coating composition, the solid content concentration of TiO ₂ is 0.3% by mass, the solid content concentration of SiO ₂ is 0.5% by mass, and the solid content concentration of the silicate binder precursor is 0.2% by mass. Each was mixed.

  Next, the obtained photocatalyst coating composition was applied to the surface of the alumite plate in the same manner as in Example 1, and dried at 200 ° C. for 30 minutes. At this time, the film was formed so that the film thickness of the photocatalyst layer was about 3 μm. Further, the same alumite plate as in Example 1 was used. Thus, the photocatalyst material of this example in which the photocatalyst layer was formed on the alumite plate was obtained.

[Evaluation]
(Coloring test)
A coloring test was performed using the photocatalyst materials of Examples 1 to 3 and Comparative Examples 1 and 2. Specifically, as a color difference meter, a spectrocolorimeter CM-700d manufactured by Konica Minolta Co., Ltd. was used, and a color difference ΔL ^* with the photocatalyst material of Comparative Example 6 to which copper was not added was measured. As a result, the case where the color difference ΔL ^* with the photocatalyst material of Comparative Example 6 was within ± 1 was evaluated as “◯”, and the case where it exceeded ± 1 was evaluated as “×”. The evaluation results are shown in Table 1.

As shown in Table 1, in Examples 1 to 3 and Comparative Example 1 having a small copper content, the value of the color difference ΔL ^* was within the allowable value. However, in Comparative Example 2 having a large copper content, the value of the color difference ΔL ^* was outside the allowable value. From this result, in order to suppress the color change of a photocatalyst material, it turns out that it is preferable that the copper in a copper compound particle is 0.1-5 mass parts with respect to 100 mass parts of photocatalyst particles.

(Algae prevention test)
Algae prevention tests were performed using the photocatalyst materials of Examples 1 to 3 and Comparative Examples 1 and 2. Test conditions and evaluation methods were as follows.

Test place: Area surrounded by trees Installation location: Place the photocatalyst material of the base material facing the north surface, and further about 1m in height from the ground. At this time, the base material was installed perpendicular to the ground, and a gutter was provided so that rainwater hit the base material.
Test period: From April to October of the following year Evaluation method: The surface area of the photocatalyst material covered with algae is visually determined. Algae coverage of less than 5% was evaluated as “◯”, 5-50% was evaluated as “Δ”, and the case where it exceeded 50% was evaluated as “x”.

  The following is assumed as the basis for setting the test conditions. First, by setting the area surrounded by trees as the test place, algae can easily fly and adhere to the surface of the photocatalyst material. Moreover, direct sunlight can be prevented by directing the photocatalyst material of the base material toward the north surface, and growth of algae can be prevented from being suppressed by drying or irradiation with sunlight (particularly ultraviolet rays). Furthermore, by providing a cocoon, it was easy to keep the photocatalyst material wet and promoted the growth of algae. Further, in order to evaluate the long-term algae-proofing property, a test from April to October of the following year was conducted in order to pass twice the rainy season with high humidity, a lot of rain, and a small amount of sunlight. The evaluation results are shown in Table 2.

In the photocatalyst material according to the present embodiment, the mechanism capable of exhibiting an algae-proofing effect is “1. Photolytic reaction with TiO ₂ ”, “2. Protein denaturation with monovalent copper (cuprous oxide) generated by the reduction reaction”, “Protein denaturation with divalent copper (copper hydroxide)”. Moreover, monovalent copper has a higher algal control effect than divalent copper. Based on these, we will examine the results of the algae control test.

  In April of the first year immediately after installation, all the samples were started from a state where no algae were propagated. Next, in July of the first year, since the rainy season was experienced once, the growth of algae was confirmed in Comparative Example 1, Comparative Example 4 and Comparative Example 5.

Here, in Comparative Example 1, “1. Photolytic reaction with TiO ₂ ”, “2. Protein denaturation with monovalent copper (cuprous oxide) generated by reduction reaction”, “3.2 Bivalent copper (hydroxide) The anti-algae effect of “protein modification by copper” can be expected. However, since Comparative Example 1 has a very low copper content, “2. Protein modification by monovalent copper (cuprous oxide) generated by reduction reaction”, “3.2 Protein by bivalent copper (copper hydroxide)” The effect of “denaturation” is very small, and the algae is considered to have propagated. In Comparative Example 4, since there is only a weak algal control effect of only “3.2 protein modification with copper (copper hydroxide)”, it is considered that algae has propagated. In Comparative Example 5, although “1. Photodecomposition reaction with TiO ₂ ” could be exhibited, the algae was considered to have propagated because it was easily moisturized by the hydrophilicity of the surface.

Furthermore, in July of the second year after the second rainy season, the algae breeding was also confirmed in Comparative Example 3. That is, in Comparative Example 3, in July of the first year, algae were propagated by “1. Photolytic reaction by TiO ₂ ” and “2. Protein modification by monovalent copper (cuprous oxide) generated by reduction reaction”. I was able to suppress it. However, since it does not contain inorganic particles that do not have photocatalytic activity, cuprous oxide is eluted by rainwater, which is a dilute acid, and loses its algal control effect. Therefore, it is considered that algae grew as of July of the second year. .

Finally, even in October of the second year, the growth of algae could not be confirmed in Examples 1 to 3 and Comparative Example 2. In other words, in these examples, “1. Photolytic reaction with TiO ₂ ”, “2. Protein denaturation with monovalent copper (cuprous oxide) generated by reduction reaction”, “3.2 With divalent copper (copper hydroxide)” It is thought that three effects of “protein denaturation” could be exhibited. In addition, in these examples, it is considered that long-term anti-algae effect could be exhibited by divalent copper (copper hydroxide) that does not cause elution by dilute acid.

  The results of the above-described coloring test and algae control test are summarized in Table 3. As shown in Table 3, it can be seen that the photocatalyst materials of Examples 1 to 3 according to the present embodiment have a very small change in color and exhibit high algaeproofing properties over a long period of time.

On the other hand, it can be seen that the photocatalyst material of Comparative Example 1 having a small amount of copper compound particles has a very small change in color, but has insufficient algaeproofing properties. Moreover, although the photocatalyst material of the comparative example 2 with excess copper compound particle | grains has sufficient alga-proof property, since a color change is large, it turns out that it is difficult to apply as an exterior material. The photocatalyst materials of Comparative Examples 3 to 5 are “1. Photolytic reaction with TiO ₂ ”, “2. Protein denaturation with monovalent copper generated by reduction reaction”, “3.2 Protein denaturation with bivalent copper”. Since either of them was missing, the algae resistance was insufficient.

  In addition, since the photocatalyst material of the comparative example 6 only contains the silica which does not have photocatalytic activity and antimicrobial property with a titanium oxide, it will be considered that it becomes the evaluation result similar to the comparative example 5.

  As described above, the contents of the present embodiment have been described according to the examples. However, the present embodiment is not limited to these descriptions, and it is obvious to those skilled in the art that various modifications and improvements are possible. is there.

DESCRIPTION OF SYMBOLS 10 Base material 20 Photocatalyst layer 21 Photocatalyst particle 22 Copper compound particle 23 Inorganic particle which does not have photocatalytic activity 24 Binder 100 Photocatalyst material

Claims (6)

A substrate;
A photocatalyst layer provided on one surface of the substrate;
Have
The photocatalyst layer contains photocatalyst particles, copper compound particles containing at least one of copper oxide (II) and copper hydroxide (II), inorganic particles not having photocatalytic activity, and an inorganic binder,
The copper in the copper compound particles is 0.1 to 5 parts by mass with respect to 100 parts by mass of the photocatalyst particles,
The copper compound particles are supported so as to contact the surface of the photocatalyst particles and the inorganic particles ,
An average particle diameter of the photocatalyst particles is 50 nm to 200 nm, the average particle diameter of the copper compound particles is the 0.1Nm～20nm, the average particle diameter of the inorganic particles Ru 5nm~100nm der photocatalytic material.   The photocatalyst material according to claim 1, wherein the photocatalyst layer further contains monovalent copper ion compound particles.   The photocatalyst material according to claim 2, wherein the monovalent copper ion compound particles include cuprous oxide particles. The photocatalyst material according to any one of claims 1 to 3 , wherein the photocatalyst particles include titanium oxide particles. A photocatalyst coating composition for forming a photocatalyst layer in the photocatalyst material according to any one of claims 1 to 4 ,
A photocatalyst particle, a copper compound containing copper (II) oxide and copper hydroxide (II) and containing at least a divalent copper ion compound, inorganic particles having no photocatalytic activity, and an inorganic binder precursor Including
The photocatalyst coating composition whose copper in the said copper compound is 0.1-5 mass parts with respect to 100 mass parts of said photocatalyst particles. The photocatalyst coating composition according to claim 5 , further comprising a monovalent copper ion compound.

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