Oxide complex

Abstract

To provide an oxide complex improved in resistance to dissolution of a silver compound in water, adhesion to a substrate, and the like.SOLUTION: The invention provides an oxide complex.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an oxide composite. [Background technology]

[0002] Patent Document 1 discloses metal nanoparticle-supported titania nanoparticles in which metal nanoparticles are supported on the surface of titania nanoparticles, wherein the titania nanoparticles have acyloxy groups bonded to at least some of the titanium atoms present on the surface, and when the titania nanoparticles are heated to 600°C using a thermogravimetric and differential thermal analyzer, they experience a mass loss of 5% by mass or more at 200°C or higher, and the metal nanoparticles are supported on the surface in an amount of 90% by mass or less relative to the titanium oxide in the titania nanoparticles, as well as a photocatalyst containing the metal nanoparticle-supported titania nanoparticles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-154233 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an oxide composite having improved resistance to silver elution in water, improved adhesion to a substrate, and improved transparency. [Means for solving the problem]

[0005] The present invention encompasses the following oxide composites:

[0006] Section 1. An oxide composite, (A) A part of the surface of the silver fine particles is coated with (B) inorganic oxide fine particles, The (A) silver fine particles have an average primary particle diameter of 1 nm to 1,000 nm, The (B) inorganic oxide fine particles have an average primary particle diameter of 1 nm to 100 nm. Oxide complex.

[0007] Section 2. Item 2. The oxide composite according to item 1, wherein the (A) silver fine particles have an average primary particle size of 1 nm to 200 nm.

[0008] Section 3. Item 2. The oxide composite according to item 1, wherein the (A) silver fine particles have a surface coverage of 1% or more.

[0009] Section 4. Item 2. The oxide composite according to item 1, wherein the (A) silver fine particles have a surface coverage of 5% to 95%.

[0010] Section 5. The ratio of the average primary particle size of the (A) silver fine particles to the average primary particle size of the (B) inorganic oxide fine particles ((A) average primary particle size of silver fine particles / (B) average primary particle size of inorganic oxide fine particles) Item 2. The oxide composite according to item 1, wherein the ρ is 0.5 or more.

[0011] Section 6. The ratio of the average primary particle size of the (A) silver fine particles to the average primary particle size of the (B) inorganic oxide fine particles ((A) average primary particle size of silver particles / (B) average primary particle size of inorganic oxide) Item 2. The oxide composite according to item 1, wherein the molecular weight is 1 or more and 200 or less.

[0012] Section 7. Item 2. The oxide composite according to Item 1, wherein the (B) inorganic oxide fine particles covering the (A) silver fine particles have a random ratio of 50% or more.

[0013] Section 8. The mass ratio of the silver mass (Ag mass) in the silver fine particles (A) to the titanium oxide mass (TiO mass) in the inorganic oxide fine particles (B) ((A) Ag mass in silver particles / (B) TiO2 mass in inorganic oxide particles) Item 2. The oxide composite according to item 1, wherein the R is ≦10 (10 or less).

[0014] Section 9. In the oxide composite, Item 2. The oxide composite according to item 1, wherein the total solid content of the (A) silver fine particles and the (B) inorganic oxide fine particles is 50 mass % or less.

[0015] Section 10. Item 2. The oxide composite according to item 1, wherein the inorganic oxide fine particles (B) are titania fine particles (B1).

[0016] Section 11. The (B1) titania fine particles are The surface is protected with organic acid, The mass of the organic acid is 1% by mass or more relative to the weight of titanium oxide. Item 11. The oxide composite according to item 10.

[0017] Section 12. The organic acid is at least one organic acid selected from the group consisting of monocarboxylic acids having 1 to 4 carbon atoms and hydroxycarboxylic acids having 2 to 3 carbon atoms, or an acyloxy group derived from at least one organic acid selected from the group consisting of monocarboxylic acids having 1 to 4 carbon atoms and hydroxycarboxylic acids having 2 to 3 carbon atoms; Item 12. The oxide composite according to item 11,

[0018] Section 13. Item 12. The oxide complex according to item 11, wherein the organic acid is at least one organic acid selected from the group consisting of acetic acid and lactic acid.

[0019] Section 14. Item 11. The oxide composite according to item 10, wherein the (B1) titania fine particles are positively charged.

[0020] Section 15. The oxide composite according to any one of items 1 to 14, and water, A dispersion containing 0.5% by mass or more of water.

[0021] Section 16. Item 16. The dispersion according to item 15, wherein the pH of the dispersion is 1 to 8.

[0022] Section 17. The oxide composite according to any one of items 1 to 14, or 17. The dispersion according to any one of items 15 to 16. Paint containing.

[0023] Section 18. Item 18. A coating film formed by the coating material according to item 17.

[0024] The present invention provides an oxide composite in which the surfaces of silver particles are partially coated with inorganic oxide particles (titanium oxide particles, etc.). The oxide composite of the present invention has improved resistance to elution of the silver compound in water and improved adhesion to a substrate. [Effects of the Invention]

[0025] The present invention makes it possible to provide an oxide composite having improved resistance to elution of a silver compound in water, improved adhesion to a substrate, and the like. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be described in detail below.

[0027] The embodiments of the present invention are intended to provide a better understanding of the gist of the invention, and unless otherwise specified, do not limit the content of the invention.

[0028] In this specification, the terms "comprise" and "contain" are concepts that encompass all of "comprise," "consist essentially of," and "consist only of."

[0029] In this specification, when a numerical range is expressed as "A to B," it means "not less than A and not more than B."

[0030] In this specification, the expressions parts, % and the like are generally used.

[0031] In this specification, unless otherwise specified, all parts by mass or % by mass (wt%) are used.

[0032] [1] Oxide complex In the prior art (Patent Document 1), a uniform dispersion of metal nanoparticle-supported titania nanoparticles is prepared using ultrasound, etc. In this prior art, silver is supported on titanium oxide (support), and the secondary particle size of the silver nanoparticle-supported titania nanoparticles is relatively large, so further study is required on the dispersion stability in the liquid and the elution of silver nanoparticles into water.

[0033] Conventional technology has a structure in which silver is supported on the periphery of titanium oxide, that is, a structure in which silver coats the periphery of titanium oxide. Generally, silver is easily ionized and elutes in water, resulting in low durability of antibacterial and antiviral properties. Methods of imparting resistance to silver elution in water include supporting silver on a carrier in the form of silver nanoparticles or immobilizing silver by embedding it in a binder or the like. However, further study is needed to achieve the simultaneous antibacterial and antiviral properties, transparency, and resistance of silver to elution in water with conventional technology.

[0034] The present invention provides a structure in which inorganic oxide fine particles (titania, etc.) are supported on the periphery of silver fine particles (support). The present invention provides a structure in which inorganic oxide fine particles (titania, etc.) are coated around the periphery of silver fine particles (support). The oxide composite of the present invention is subjected to high-pressure dispersion treatment to control the secondary particle size of the inorganic oxide fine particles (titania nanoparticles, etc.)-supported silver fine particles, thereby coating the periphery of the silver with titanium oxide, and making it possible to prepare a dispersion in which the silver is uniformly and stably dispersed in liquid.

[0035] The oxide composite of the present invention is formed by coating silver nanoparticles with a sol of inorganic oxide fine particles (titanium oxide, etc.), thereby improving the resistance of silver to elution into water, maintaining the antibacterial and antiviral properties of the silver contained in the oxide composite, and also maintaining the adhesion of the oxide composite to a substrate, the transparency of the oxide composite, etc.

[0036] The oxide composite of the present invention is (A) A part of the surface of the silver fine particles is coated with (B) inorganic oxide fine particles, The (A) silver fine particles have an average primary particle diameter of 1 nm to 1,000 nm, The inorganic oxide fine particles (B) have an average primary particle diameter of 1 nm to 100 nm.

[0037] (1-1)(A) Silver nanoparticles The oxide composite of the present invention has a structure in which inorganic oxide particles (titania, etc.) are supported on the periphery of silver particles (support), or a structure in which inorganic oxide particles (titania, etc.) are coated on the periphery of silver particles (support). In the oxide composite, (A) silver particles are partially coated on the surface with (B) inorganic oxide particles, and the (A) silver particles have an average primary particle diameter of 1 nm to 1,000 nm.

[0038] The average primary particle diameter of the (A) silver fine particles is 1 nm to 1,000 nm, preferably 1 nm to 500 nm, more preferably 1 nm to 200 nm, and even more preferably 1 nm to 100 nm. The average primary particle diameter of the silver nanostructures is measured using a transmission electron microscope (TEM).

[0039] The sample is prepared by adjusting the concentration of the compound with the larger solid content (either silver or inorganic oxide) that constitutes the inorganic oxide composite to 0.2% by mass (wt%), dropping it onto a TEM grid, and drying it at a temperature below room temperature. If the compound concentration is less than 0.2% by mass, the concentration is not adjusted, but the sample is dropped onto a TEM grid and dried at a temperature below room temperature.

[0040] By adjusting the average particle size of the supported silver nanostructures within this range, a dispersion with high dispersion stability can be obtained, which further improves visible light catalytic activity and allows the formation of a film with improved transparency.

[0041] The form of the silver nanostructure is not particularly limited, and from the viewpoints of the stability of silver, antibacterial activity in light and dark places (particularly in dark places), antiviral activity, etc., it is preferable to use silver nanoparticles, silver nanorods, silver nanowires, etc.

[0042] (A) Surface coverage of silver particles The (A) fine silver particles preferably have a surface coverage of 1% or more, and more preferably a surface coverage of 5% to 95%.

[0043] Definition of coverage An oxide composite having a structure in which inorganic oxide particles (titania (Ti) or the like) are supported around silver (Ag) particles (support) is imaged using an electron microscope (scanning electron microscope (SEM) or transmission electron microscope (TEM)), and the locations of the A particles and Ti particles are clarified by elemental analysis (energy dispersive X-ray analysis (EDS), electron probe microanalyzer (EPMA), electron energy loss spectroscopy (EELS), etc.).

[0044] Then, 10 random Ag particles are selected and arranged in order of particle size. Focus is then placed on the Ag nanoparticles with the fifth and sixth smallest particle sizes, and binarization is performed using image processing software such as the image analysis software WinROOF (Mitani Shoji Co., Ltd.).

[0045] (A) Particle size ratio α(Ag) / β(Ti) The particle diameter of the silver (Ag) particles is defined as α (nm), and the particle diameter of the titania (Ti) particles is defined as β (nm). α / β is calculated based on this. α / β is preferably 1 / 2 or more.

[0046] By adjusting the ratio α(Ag particles) / β(Ti particles) to 1 / 2 or more (the silver nanoparticles are relatively large), the particle size of the titanium oxide particles is maintained at a satisfactory level relative to the silver nanoparticles (the particle size of the titanium oxide particles is not too large compared to the particle size of the silver nanoparticles), and the transparency of the dispersion containing the oxide composite can be maintained satisfactorily. α(Ag) / β(Ti) is more preferably adjusted to 1 to 1,000, and even more preferably adjusted to 1 to 100.

[0047] (B) Coverage of Ag particles As a result of this binarization process, the area of ​​the Ag particles is defined as A, and the area of ​​the inorganic oxide particles that overlap with the Ag nanoparticles is defined as B. Based on this result, the coverage rate is defined as B (inorganic oxide particles) / A (Ag particles) × 100 (%).

[0048] When the Ag particles are completely covered with inorganic oxide particles, the coverage rate is 100%.

[0049] When the Ag particle exists alone, the coverage rate is 0%, and the Ag particle is not covered with the inorganic oxide particle.

[0050] The oxide composite has a coverage value of 1 to 99 surface %, preferably 5 to 95 surface %, more preferably 10 to 80 surface %, and even more preferably 15 to 65 surface %. By adjusting the coverage value of titania within the above range, the oxide composite exhibits good antibacterial and antiviral activity, a dispersion containing the oxide composite has good dispersion stability, and a coating film containing the oxide composite has improved resistance to silver elution in water and adhesion to a substrate.

[0051] When the coverage of the oxide composite exceeds 99%, the exposure rate of the Ag particles decreases, possibly resulting in a decrease in antiviral performance. When the coverage of the oxide composite is less than 1%, the stability of the Ag particles in the oxide composite or dispersion may decrease. By adjusting the coverage (B (inorganic oxide particles) / A (Ag particles) × 100 (%)) to 1 surface % to 99 surface %, the oxide composite of the present invention can partially coat the surfaces of the Ag particles, improving antiviral performance and the stability of a dispersion containing the oxide composite. The oxide composite also improves the resistance of silver to elution in water and its adhesion to substrates.

[0052] (C) Random ratio of inorganic oxide particle (Ti, etc.) islands The random ratio of Ag particles is defined as follows:

[0053] As a result of binarization processing using image processing software (WinROOF), the coordinate positions of Ag particles are defined as follows: AgXmax (maximum value of the X coordinate of an Ag particle) AgXmin (minimum value of the X coordinate of an Ag particle) AgYmax (maximum Y coordinate of Ag particles) AgYmin (minimum Y coordinate of Ag particles)

[0054] Next, N inorganic oxide particles are extracted from the inorganic oxide particles by measuring their shape characteristics using WinROOF. Each inorganic oxide particle is arbitrarily assigned a number in order, such as 1, 2, 3, and the nth inorganic oxide particle is defined as On.

[0055] For On, the coordinate position is defined as follows: Onx (X coordinate of the center of gravity of the nth inorganic oxide particle) Ony (Y coordinate of the center of gravity of the nth inorganic oxide particle)

[0056] Next, the region of the Ag particle is divided as follows: AgX1=AgXmin (first X coordinate) AgXm+1=AgXm+(AgXmax-AgXmin) / N (m+1th X coordinate) AgY1=AgYmin (first Y coordinate) AgYm+1=AgYm+(AgYmax-AgYmin) / N (m+1th Y coordinate)

[0057] The number of inorganic oxide particles in each of the divided regions and the maximum value thereof are defined as follows. The number of Onx contained within the coordinates of AgXm and AgXm+1 is defined as NOmx. Furthermore, the maximum value of NOmx is defined as NOxmax. The number of Ony contained in the coordinates of AgYm and AgYm+1 is defined as NOmy. Furthermore, the maximum value of NOmx is defined as NOymax.

[0058] The random rate in the X-axis direction (Ranx) and the random rate in the Y-axis direction (Rany) are as follows: Ranx = (1 - NOxmax / N) x 100 Rany = (1-NOymax / N) x 100

[0059] This allows the measurement of the randomness (Ranx, Rany). Each of the randomness (Ranx, Rany) is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more. In the oxide composite of the present invention, a high randomness means that the number of Ti particles coated on the Ag particles is large and that they are well dispersed.

[0060] By adjusting the random ratios Ranx and Rany, the oxide composite of the present invention can efficiently expose Ag particles while increasing the dispersibility of the Ag particles, thereby improving the dispersion stability and antiviral activity of the Ag particles and preventing the elution of Ag from the inorganic oxide composite.

[0061] (1-2)(B) Inorganic oxide fine particles The oxide composite of the present invention has a structure in which inorganic oxide particles (titania, etc.) are supported on the periphery of silver particles (support), or a structure in which inorganic oxide particles (titania, etc.) are coated on the periphery of silver particles (support). In the oxide composite of the present invention, a portion of the surface of the (A) silver particles is coated with (B) inorganic oxide particles, and the (B) inorganic oxide particles have an average primary particle diameter of 1 nm to 100 nm.

[0062] (B) The inorganic oxide fine particles are silica, alumina, ceria, calcium oxide, titanium oxide, tungsten oxide, and zinc oxide, and (B1) titania fine particles are preferred.

[0063] The (B1) titania fine particles preferably have their surfaces protected with an organic acid, and the mass of the organic acid is 1% by mass or more relative to the weight of titanium oxide. The organic acid is preferably

[0064] at least one organic acid selected from the group consisting of monocarboxylic acids having 1 to 4 carbon atoms and hydroxycarboxylic acids having 2 to 3 carbon atoms, or

[0065] The acyloxy group is derived from at least one organic acid selected from the group consisting of monocarboxylic acids having 1 to 4 carbon atoms and hydroxycarboxylic acids having 2 to 3 carbon atoms.

[0066] The organic acid is preferably at least one organic acid selected from the group consisting of acetic acid and lactic acid.

[0067] The (B1) titania fine particles are preferably positively charged.

[0068] Water, inorganic acids, free organic acids, etc. generally evaporate almost completely at temperatures below 200°C.

[0069] (B1) When titania microparticles are heated using a thermogravimetric differential thermal analyzer (TG-DTA), the mass loss at temperatures above 200°C indicates the weight of organic acids or acetoxy groups present on the surface of the titania microparticles.

[0070] When the (B1) titania fine particles are heated to 600°C using a thermogravimetric differential thermal analyzer (TG-DTA), their mass loss at 200°C or higher is 5% by mass or more, preferably 7% to 20% by mass. By adjusting the mass loss within this range, aggregation of titania nanoparticles during drying or calcination can be suppressed, reducing cracking and peeling, resulting in particularly excellent coatability and transparency. The (B) inorganic oxide fine particles (preferably (B1) titania fine particles) can suppress cracking and peeling and facilitate strong metal support, resulting in excellent visible light photocatalytic activity. The detailed conditions for the thermogravimetric differential thermal analyzer (TG-DTA) are: atmosphere: air, heating rate: 3°C / min.

[0071] The organic acid (B1) protecting the titania fine particles is preferably at least one organic acid selected from the group consisting of monocarboxylic acids having 1 to 4 carbon atoms and hydroxycarboxylic acids having 2 to 3 carbon atoms, or an acyloxy group (-OCOR) derived from at least one organic acid selected from the group consisting of monocarboxylic acids having 1 to 4 carbon atoms and hydroxycarboxylic acids having 2 to 3 carbon atoms.

[0072] In -OCOR, the alkyl group of R is preferably a methyl group, an ethyl group, an n-propyl group, etc. In -OCOR, the monocarboxylic acid is preferably formic acid, acetic acid, propionic acid, butyric acid, etc.

[0073] In -OCOR, the hydroxyalkyl group of R is preferably a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, etc. In -OCOR, the hydroxycarboxylic acid is preferably glycolic acid, lactic acid, etc.

[0074] In —OCOR, from the viewpoints of volatility, toxicity, and decomposability, R is preferably a hydrogen atom, or a methyl group, a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, or the like.

[0075] In -OCOR, from the viewpoints of water solubility and odor, R is preferably a methyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, or the like.

[0076] From the viewpoints of volatility, toxicity and decomposability, -OCOR is preferably a monocarboxylic acid such as formic acid or acetic acid.

[0077] From the viewpoints of volatility, toxicity and decomposability, -OCOR is preferably a hydroxycarboxylic acid such as glycolic acid or lactic acid.

[0078] From the viewpoints of water solubility and odor, particularly preferred -OCORs are acetic acid, glycolic acid, lactic acid, and the like.

[0079] The organic acid may be at least one compound selected from the group consisting of the above organic acids, and these organic acids may be used alone or in combination (blended) in two or more types depending on the purpose.

[0080] The average primary particle diameter of the (B) inorganic oxide fine particles is preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm, even more preferably 1 nm to 10 nm, and particularly preferably 2 nm to 6 nm. The average primary particle diameter of the (B) inorganic oxide fine particles (supported side) is preferably smaller than the average primary particle diameter of the (A) silver fine particles (support, supporting side). By adjusting the average particle diameter of the (B) inorganic oxide fine particles within the above range, the (B) inorganic oxide fine particles can be supported appropriately and more firmly around the (A) silver fine particles (support), and the (B) inorganic oxide fine particles can form a film with higher visible light photocatalytic activity and higher transparency.

[0081] The average secondary particle diameter of the (B) inorganic oxide fine particles is 1,000 nm or less, more preferably 5 nm to 500 nm, and even more preferably 5 nm to 100 nm.

[0082] The average particle size of the secondary particles of the oxide composite is measured by observation with a particle size distribution analyzer.

[0083] (B) The average particle size of inorganic oxide microparticles is measured by observation with a transmission electron microscope (TEM). The sample is prepared by adjusting the concentration of silver or inorganic oxide, whichever has the larger solid content, to 0.2%, dropping it onto a TEM grid, and drying it at 25°C or below. At this time, samples with a compound concentration of less than 0.2% by mass (wt%) are dropped onto a TEM grid without concentration adjustment and dried at 25°C or below.

[0084] (B) The specific surface area of ​​the inorganic oxide fine particles is preferably 150 m 2 / g~500m 2 / g, more preferably 200m 2 / g~400m 2 / g, and more preferably 210 to 300m 2 By adjusting the specific surface area of ​​the (B) inorganic oxide fine particles to fall within the above range, the (B) inorganic oxide fine particles can be supported appropriately and more firmly around the (A) silver fine particles (carrier), and the (B) inorganic oxide fine particles can form a film with higher visible light photocatalytic activity and higher transparency.

[0085] (B) The specific surface area of ​​the inorganic oxide fine particles is measured by the BET method.

[0086] The titania nanoparticles can have N, Cl, and S element concentrations of preferably 0 to 5,000 ppm, more preferably 0 to 1,000 ppm. By adjusting the N, Cl, and S element concentrations of the titania nanoparticles within this range, corrosion of the substrate can be suppressed. The N, Cl, and S element concentrations of the titania nanoparticles mean that impurities derived from acidic titania precursors such as TiCl4 and TiOSO4 are absent or present in very small amounts.

[0087] The concentrations of N, Cl, and S elements in (B) inorganic oxide fine particles (preferably (B1) titania fine particles) are measured by WDX (fluorescent X-ray).

[0088] The crystal form of the (B1) titania fine particles is preferably anatase type, and the (B1) titania fine particles preferably contain no crystal forms other than anatase type and are 100% anatase type. By using the (B1) titania fine particles of anatase type, the visible light catalytic activity is improved.

[0089] (1-3) Oxide complex In the oxide composite, the ratio of the average primary particle size of the (A) silver microparticles to the average primary particle size of the (B) inorganic oxide microparticles (average primary particle size of the (A) silver microparticles / average primary particle size of the (B) inorganic oxide microparticles) is preferably 0.5 or more.

[0090] In the oxide composite, the ratio of the average primary particle size of the (A) silver microparticles to the average primary particle size of the (B) inorganic oxide microparticles (average primary particle size of the (A) silver microparticles / average primary particle size of the (B) inorganic oxide) is preferably 1 or more and 200 or less.

[0091] In the oxide composite, the random ratios (Ranx, Rany) of the inorganic oxide fine particles (B) that cover the silver fine particles (A) are preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more.

[0092] In the oxide composite, the mass ratio of the silver mass (Ag mass) in the (A) silver fine particles to the titanium oxide mass (TiO2 mass) in the (B) inorganic oxide fine particles (preferably, (B1) titania fine particles) (Ag mass in the (A) silver fine particles / TiO2 mass in the (B) inorganic oxide fine particles) is preferably ≦10 (10 or less), more preferably 0.0001 to 5, and even more preferably 0.001 to 1. By adjusting the Ag mass in the (A) silver fine particles / TiO2 mass in the (B) inorganic oxide fine particles to ≦10 (10 or less), the antimicrobial activity (antibacterial activity and antiviral activity) and stability of the oxide composite can be well maintained, and the strength and transparency of the coating film can be maintained.

[0093] In the oxide composite, the total solid content of (A) the silver fine particles and (B) the inorganic oxide fine particles is preferably 50 mass % or less.

[0094] (1-4) Dispersions, paints, and coating films The present invention encompasses a dispersion containing the oxide composite of the present invention and water, the dispersion containing 0.5 mass % or more of water.

[0095] The pH of the dispersion is preferably from 1 to 8, and more preferably from 2 to 5. By setting the pH of the dispersion within this range, the stability and transparency of the dispersion become good, and cracks in the coating film can be prevented when the dispersion is applied to a substrate and dried.

[0096] The present invention includes a coating material containing the oxide complex or dispersion of the present invention, and a coating film formed by the coating material of the present invention.

[0097] [2] Manufacturing method for oxide composite The oxide composite of the present invention has a structure in which inorganic oxide particles (titania, etc.) are supported on the periphery of silver particles (support), or a structure in which inorganic oxide particles (titania, etc.) are coated on the periphery of silver particles (support).

[0098] In the present invention, the method for supporting (B) inorganic oxide fine particles (preferably (B1) titania fine particles or titania sol) around (A) silver fine particles (carrier) is preferably a method in which (A) silver compound and (B) inorganic oxide fine particles are mixed, and then silver nanoparticles are formed by irradiating with light, while the surfaces of the silver nanoparticles are coated with inorganic oxide fine particles (preferably (B1) titania fine particles or titania sol).

[0099] A preferred method for supporting (B) inorganic oxide fine particles around (A) silver fine particles (support) is to mix (A) silver compound and (B) inorganic oxide fine particles, and then coat the surfaces of the silver nanoparticles with inorganic oxide fine particles (preferably (B1) titania fine particles or titania sol) while forming silver nanoparticles using a reducing agent. A preferred method for supporting (B) inorganic oxide fine particles around (A) silver fine particles (support) is to contact (A) silver fine particles (support) with (B) inorganic oxide fine particles, mix them, or allow them to stand, and support them.

[0100] The method for producing inorganic oxide fine particles preferably includes the steps of: (Step A) Step (B) comprises a step of heating a dispersion liquid obtained by mixing a substance containing inorganic oxide fine particles, an organic acid, and water at a temperature higher than 90° C. for one hour or more.

[0101] (Step B) In the method for producing an oxide composite, after step (A), the dispersion containing inorganic oxide fine particles (B) obtained in step (A) is preferably subjected to a pressure treatment of 30 MPa or more (high-pressure dispersion method).

[0102] The method for producing an oxide composite preferably includes step (C) (step (C1), (C2), (C3), or (C4)) after step (B).

[0103] Step C1 is a step in which the dispersion obtained in step B is mixed with a precursor of silver particles and the dispersion is subjected to a chemical reduction treatment. Step C1 can improve the loading efficiency by applying external energy.

[0104] Step C2 is a step of irradiating the dispersion obtained by mixing the dispersion obtained in step B with (A) silver fine particles with ultraviolet light. Step C2 can improve the loading efficiency by applying energy from the outside.

[0105] Step C3 is a step of mixing the dispersion obtained in step B with (A) silver fine particles. Step C3 can prevent the dispersion of (B) inorganic oxide fine particles from becoming too viscous, thereby obtaining uniform particles.

[0106] (Step C4) This is a step of adding (A) fine silver particles to the dispersion liquid obtained in step (B) and leaving it to stand.

[0107] By carrying out steps (C1), (C2), (C3), and (C4) at a temperature of 25°C or less, it is possible to further improve the particle size controllability of the (A) silver fine particles.

[0108] [2-1] Process (A) In step (A), a dispersion is obtained by mixing (B) a substance containing inorganic oxide fine particles, an organic acid, and water. (B) The inorganic oxide fine particles are preferably (B1) titania fine particles.

[0109] (B1) Preparation of titania particles The titanium-containing substance used is preferably a substance that becomes titanium oxide when heated. The titanium-containing substance is preferably titanium oxide and / or a titanium oxide precursor, and more preferably titanium oxide; titanium hydroxide; titanium alkoxide; titanium halides such as titanium trichloride and titanium tetrachloride (particularly those neutralized with a base); metallic titanium, etc.

[0110] The titanium-containing substance is preferably titanium alkoxide, titanium hydroxide, or titanium halide (particularly, one neutralized with a base) from the viewpoints of the dispersibility, coatability, transparency, and visible light photocatalytic activity of the resulting titania. The titanium-containing substance is more preferably titanium alkoxide from the viewpoints of purity, dispersibility, coatability, transparency, and visible light photocatalytic activity.

[0111] The titanium alkoxide is preferably titanium tetraisopropoxide, titanium tetra n-butoxide, titanium tetra n-propoxide, titanium tetraethoxide, etc. From the viewpoints of cost, water solubility of by-products, coatability, and visible light catalytic property, the titanium alkoxide is more preferably titanium tetraisopropoxide.

[0112] The titanium-containing substance may be at least one compound selected from the group consisting of the titanium-containing substances described above, and these titanium-containing substances may be used alone or in combination (blended) of two or more types depending on the purpose.

[0113] Depending on the combination of titanium alkoxide and organic acid, the resulting titania may act as a catalyst to liberate a poorly water-soluble ester compound. However, there is no problem with the titania itself. For example, in the combination of titanium tetra-n-butoxide and acetic acid, butyl acetate is generated and liberated during mixing and heating. However, from the viewpoint of obtaining a uniform dispersion, it is preferable to use a combination of an organic acid and titanium alkoxide that produces an organic acid alkoxide with excellent water solubility.

[0114] Titanium halides (titanium tetrachloride, titanium trichloride, etc.) are preferably neutralized with a base and the precipitate washed before use from the viewpoints of impurities (halogens), corrosion of a reactor during mass production, crystallinity control, coatability, transparency, and visible light catalysis. Titanium halides are preferably used without drying from the viewpoint of dispersibility of the resulting titania.

[0115] When a solid such as titanium oxide or metallic titanium is used as the titanium-containing substance, the average primary particle size is preferably 100 nm or less, more preferably 50 nm or less. There is no particular lower limit for the average particle size of the titanium-containing substance, and it is preferably about 1 nm.

[0116] When the particle size is large, it is preferable to use the powder after dry or wet pulverization using a planetary ball mill, paint shaker or the like.

[0117] The average particle size of solids such as titanium oxide and metallic titanium is measured by observation using a transmission electron microscope (TEM).

[0118] The concentration of the titanium-containing substance in the dispersion produced in step (A) is preferably 0.01 mol / L to 5 mol / L, more preferably 0.05 mol / L to 3 mol / L, from the viewpoints of productivity, viscosity of the reaction liquid, coatability, transparency, and visible light catalytic properties.

[0119] The acid used in the reaction is an organic acid, and since a volatile acid is preferred, it is preferably an acid represented by the chemical formula C n H 2n+1 Monocarboxylic acids represented by COOH (n=0 to 3) (monocarboxylic acids having 1 to 4 carbon atoms), hydroxycarboxylic acids having 2 to 3 carbon atoms, etc. are used.

[0120] The monocarboxylic acid is preferably formic acid where n=0, or acetic acid where n=1, from the viewpoints of volatility, toxicity, and decomposition.

[0121] The hydroxycarboxylic acid is preferably glycolic acid, lactic acid, or the like, and from the viewpoints of water solubility and odor, more preferably acetic acid, glycolic acid, lactic acid, or the like.

[0122] The organic acid may be at least one compound selected from the group consisting of the above organic acids, and these organic acids may be used alone or in combination (blended) in two or more types depending on the purpose.

[0123] From the viewpoints of dispersibility, coatability, transparency, visible light catalytic properties, and cost, the amount of organic acid used is preferably adjusted so that the number of moles of organic acid is 0.5 moles or more, and particularly preferably 1 mole or more, per mole of titanium in the titanium-containing substance. The more organic acid used, the more the stability over time, coatability, transparency, etc. can be improved. There is no particular upper limit to the amount of organic acid used, and it is preferably adjusted so that the number of moles of acyloxy groups is 10 moles or less per mole of titanium in the titanium-containing substance.

[0124] The concentration of the organic acid in the dispersion obtained in step (A) is preferably 0.02 mol / L to 10 mol / L, more preferably 0.1 mol / L to 7 mol / L, from the viewpoints of dispersibility, coatability, transparency, visible light catalytic properties, and cost.

[0125] The reaction solvent is preferably an aqueous solvent such as water, which is used as the main component (preferably 50% by mass or more). The reaction solvent may contain an alcohol or an ester during the reaction.

[0126] When titanium tetraisopropoxide is used as a raw material, the reaction solvent reacts with an organic acid to produce isopropyl alcohol. Heating can also produce an isopropyl ester of the organic acid. The alcohol or ester may be added to the dispersion obtained in step (A), or it may be generated in the system. The alcohol or ester may be removed by heating in an open system at 100°C or below, or by reducing the pressure, or it may remain in the reaction solution.

[0127] When alcohol is contained in the dispersion, the average particle size of the obtained titania nanoparticles and metal-supported titania nanoparticles tends to become small, and therefore alcohol may be intentionally added to control the average particle size.

[0128] In general, inorganic acids (especially strong inorganic acids) such as nitric acid, hydrochloric acid, and sulfuric acid, which are often used in the hydrothermal synthesis reaction of titania nanoparticles, are preferably not used in principle, not only because the crystal form of the resulting titania nanoparticles is a mixture of anatase and brookite types, but also from the viewpoints of the storage stability of the resulting dispersion, corrosion of the equipment, impurities, wastewater, etc.

[0129] Inorganic acids can be used supplementarily to improve the dispersibility, transparency, uniformity, etc. of the raw materials and to facilitate handling, as long as the effects are not impaired, for example, in a range of 0.01 mol / L or less. The concentrations of N, Cl, and S elements in the dispersion obtained in step (A) are all 0.01 mol / L or less.

[0130] The pH of the dispersion obtained in step (A) is preferably 2 or more and less than 6, more preferably 2.1 to 5, from the viewpoints of corrosion of the equipment, safety in handling, dispersibility, and the like.

[0131] In step (A), the method for preparing the dispersion is not particularly limited, and the titanium-containing substance, organic acid, and water (solvent) may be mixed simultaneously or sequentially. On a mass production scale, from the viewpoints of preventing aggregation and forming large lumps and facilitating continuous stirring, it is preferable to mix the organic acid and water (solvent) first, and then add the titanium-containing substance while stirring. On a laboratory scale, it is preferable to mix the titanium-containing substance and organic acid first, and then add water while stirring.

[0132] The resulting dispersion is heated at a temperature higher than 90°C for at least 1 hour. Heating is preferably carried out under normal pressure, or under pressure in a sealed container. From the viewpoint of reducing the average particle size of the titania nanoparticles and the metal nanoparticle-supported titania nanoparticles, heating is preferably carried out under normal pressure. Preferably, heating is carried out under conditions of 0.09 MPa to 0.11 MPa. When heating is carried out under pressure, from the viewpoint of easily forming a film with high visible light catalytic activity and high transparency, the reaction is preferably carried out for a short period of time (approximately 5 to 30 minutes) at a pressure of 0.2 MPa or less (0.11 MPa to 0.2 MPa).

[0133] During heating, stirring is preferably performed in order to sufficiently react the titanium-containing substance, the organic acid, and the water. The stirring method is not particularly limited and follows a conventional method. The stirring time is preferably 1 hour or more, more preferably 1.5 hours or more, in order to sufficiently react the titanium-containing substance, the organic acid, and the water. The upper limit of the stirring time is not particularly limited and is preferably 240 hours.

[0134] The heating temperature is preferably higher than 90°C, more preferably higher than 92°C. If the heating temperature is lower than 90°C, the crystal growth of the titanium oxide fine particles cannot be controlled, and the dispersion stability tends to decrease over time after heating, or precipitation tends to occur when the silver fine particles are combined. The upper limit of the heating temperature is not particularly limited, and is preferably 120°C when the reaction is carried out at normal pressure.

[0135] The pH of the dispersion obtained in step (A) is preferably 2 or more and less than 6, more preferably 2.1 to 5, from the viewpoints of corrosion of the equipment, safety in handling, dispersibility, and the like.

[0136] [2-2] Process (B) <High-pressure dispersion method (pressure treatment)> In step (B), the dispersion containing the inorganic oxide fine particles (B) obtained in step (A) is subjected to a pressure treatment of 30 MPa or more (high-pressure dispersion method). The inorganic oxide fine particles (B) are preferably titania fine particles (B1).

[0137] When the high-pressure dispersion method is employed, the dispersion containing (B) inorganic oxide fine particles is preferably subjected to a pressure treatment of 30 MPa or more.

[0138] By applying pressure treatment, the primary particles and / or secondary particles of the (B) inorganic oxide microparticles are atomized, improving the dispersion stability and transparency of the (B) inorganic oxide microparticles, thereby improving the reactivity and uniformity in step (C), and making it possible to better coat the surfaces of the (A) silver microparticles with the (B) inorganic oxide microparticles when they are combined with the (A) silver microparticles.

[0139] The pressure level when carrying out the pressure treatment is not particularly limited as long as it can sufficiently atomize the inorganic oxide fine particles (B). The pressure level is preferably adjusted to 30 MPa or more, more preferably adjusted to 50 MPa to 400 MPa, and even more preferably adjusted to 100 MPa to 300 MPa. The pressure treatment is preferably carried out using a high-pressure dispersion device, a supercritical water production device, or the like. The high-pressure dispersion device can disperse the inorganic oxide fine particles (B) by applying mechanical pressure. The supercritical water production device can increase the pressure of the system by heating the water.

[0140] By applying pressure, for example, (i) causing two or more dispersions of inorganic oxide fine particles (B) to collide with each other; (ii) (B) Colliding a dispersion of inorganic oxide fine particles with a metal or ceramic material (a high-hardness material such as silicon carbide or alumina), (iii) (B) A dispersion of inorganic oxide particles is placed on a substrate with a cross-sectional area of ​​1 cm 2 Passing through the following spaces Processing such as the above is performed.

[0141] By applying pressure, it is possible to make the pressure conditions stronger, which makes it possible to more efficiently atomize the inorganic oxide fine particles (B), and further reduce the processing time.

[0142] The pressurization operation is preferably carried out two or more times, more preferably three or more times.

[0143] The temperature during pressurization is not particularly limited. The temperature during pressurization is adjusted so that the inorganic oxide fine particles can be sufficiently dispersed and the solvent does not boil. Therefore, the temperature during pressurization is preferably 0°C to 99°C, and more preferably 10°C to 90°C. Since the temperature rises during pressurization due to pressure and collision, it is preferable to cool the mixture using a heat exchanger or the like. By setting the temperature within this range, it is possible to prevent re-aggregation of the (B) inorganic oxide fine particles.

[0144] When pressure treatment is carried out, it is preferable to use, as a preliminary treatment (pretreatment), dispersion treatment using other dispersion devices such as ordinary mechanical stirring, dispersion treatment using an emulsifying device, dispersion treatment using a bead mill, etc. This can have the effect of preventing clogging in high-pressure dispersion devices, etc.

[0145] The more powerful the dispersion treatment in this pretreatment, the better. For example, in the case of dispersion treatment using an emulsifier, the rotation speed is preferably 5,000 to 100,000 rpm, and more preferably 10,000 to 50,000 rpm.

[0146] [2-3] Process (C1) In the step (C1), a dispersion obtained by mixing the dispersion containing the inorganic oxide fine particles (B) obtained in the step (B) with a silver salt (A) is subjected to a chemical reduction treatment.

[0147] silver halide The silver salt used as a precursor for silver fine particles is preferably a silver salt whose aqueous solution is acidic or neutral, since the dispersion (sol) containing inorganic oxide fine particles (titania nanoparticles) (B) obtained in steps (A) and (B) is acidic. Silver salts used are preferably silver salts whose aqueous solution is acidic or neutral. Silver salts that are preferably used include silver chloride (I), silver nitrate (I), organic silver salts (silver lactate (I), silver acetate (I), silver citrate (I), silver myristate (I), etc.), silver sulfide (I), silver oxide (I), silver phosphate (I), silver carbonate (I), silver bromide (I), and silver iodide (I).

[0148] The precursor of the silver particles may be at least one compound selected from the group consisting of the silver salts described above, and these silver salts may be used alone or in combination (blended) of two or more types depending on the purpose.

[0149] In step (C1), the amount of silver fine particles used is, from the viewpoints of dispersibility, transparency, antimicrobial activity (antibacterial activity and antiviral activity), stability of the inorganic oxide fine particles (titania nanoparticles, etc.), etc., such that the mass ratio of the silver mass (Ag mass) in the (A) silver fine particles to the titanium oxide mass (TiO2 mass) in the (B) inorganic oxide fine particles (Ag mass in the (A) silver fine particles / titanium oxide mass (TiO2 mass) in the (B) inorganic oxide fine particles) is preferably ≦10 (10 or less), more preferably 0.0001 to 5, and even more preferably 0.001 to 1.

[0150] Chemical reduction treatment In step (C1), the chemical reduction treatment is not particularly limited, and preferably, a method using a reducing agent such as sodium borohydride, a polyol reduction method, an ethanol reduction method, etc. When a reducing agent is used, the treatment is preferably carried out at a temperature of 0°C or higher but lower than 20°C (room temperature) from the viewpoints of dispersion stability and prevention of discoloration.

[0151] Step (C1) may be carried out under air or anaerobic conditions. The anaerobic conditions in step (C1) are preferably under an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere.

[0152] In step (C1), the chemical reduction treatment is preferably performed by stirring the dispersion obtained in step (B) so as to sufficiently react the silver fine particles with the dispersion. The stirring method is not particularly limited and can be performed according to a conventional method.

[0153] The pH of the resulting dispersion varies depending on the type of metal added and the amount of metal added, but is preferably 1 to 5, more preferably 2 to 4, from the viewpoint of coatability.

[0154] Thereafter, the oxide composite, in which (A) silver fine particles (carrier) are coated with (B) inorganic oxide fine particles (preferably (B1) titania fine particles or titania sol), can be recovered by precipitating and centrifuging the resulting oxide composite in a conventional manner.

[0155] [2-4] Process (C2) In step (C2), the dispersion containing the inorganic oxide fine particles (B) obtained in step (B) is mixed with the silver salt described in step (C1) to obtain a dispersion, which is then irradiated with ultraviolet light.

[0156] UV exposure In step (C2), from the viewpoints of ease of supporting (B) inorganic oxide fine particles (preferably (B1) titania fine particles or titania sol) around (A) silver fine particles (carrier), reaction rate, reaction controllability, and productivity, it is preferable to use an ultraviolet irradiation device with a wavelength of 280 nm to 500 nm. If the wavelength range is shorter than 280 nm, dispersion stability decreases, and if the wavelength is longer than 500 nm, silver is not reduced and silver nanoparticles are not produced.

[0157] In step (C2), during the ultraviolet light irradiation, the dispersion containing the inorganic oxide fine particles (B) obtained in step (B) is preferably stirred to sufficiently react with the silver fine particles (A). The stirring method is not particularly limited and can be performed according to a conventional method.

[0158] Step (C2) may be carried out under air or anaerobic conditions. The anaerobic conditions in step (C2) are preferably under an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere.

[0159] The reaction time in step (C2) is preferably 1.5 hours or more, more preferably in the range of 1.5 to 36 hours. If the reaction time is shorter than this range, the inorganic oxide fine particles will not surround the silver nanoparticles and gelation will occur, while if the reaction time is longer than this range, the particle size of the silver nanoparticles will increase and precipitation will occur.

[0160] The pH of the resulting dispersion varies depending on the type of metal added and the amount of metal added, but is preferably 1 to 5, more preferably 2 to 4, from the viewpoint of coatability.

[0161] Thereafter, the oxide composite, in which (B) inorganic oxide fine particles (preferably (B1) titania fine particles or titania sol) are supported around (A) silver fine particles (carrier), can be recovered by precipitating the oxide composite and centrifuging the precipitate.

[0162] [2-5] Steps (C3) and (C4) As the step (C3), a step of mixing the dispersion containing the inorganic oxide fine particles (B) obtained in the step (B) with the silver fine particles (A) can be adopted.

[0163] As the step (C4), a step of adding (A) silver fine particles to the dispersion containing (B) inorganic oxide fine particles obtained in the step (B) and allowing the mixture to stand can be adopted.

[0164] silver fine particles The conditions such as the (A) silver fine particles and the amount used are the same as those in step (C1). Mix and let stand

[0165] In step (C3), the method for mixing the dispersion obtained in step (B) with the silver fine particles (A) is not particularly limited and follows a conventional method. In step (C3), the silver fine particles (A) are added to the dispersion obtained in step (B) and stirred. The stirring method is not particularly limited and follows a conventional method.

[0166] Steps (C3) and (C4) may be carried out in an air atmosphere or under anaerobic conditions, and the anaerobic conditions in steps (C3) and (C4) are preferably carried out under an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere.

[0167] The pH of the resulting dispersion varies depending on the type of metal added and the amount of metal added, but is preferably 1 to 5, more preferably 2 to 4, from the viewpoint of coatability.

[0168] Thereafter, the oxide composite, in which (B) inorganic oxide fine particles (preferably (B1) titania fine particles or titania sol) are supported around (A) silver fine particles (carrier), can be recovered by precipitating the oxide composite and centrifuging the precipitate.

[0169] [3] Dispersion, paint, and coating film containing oxide complex Dispersion containing oxide complex The dispersion containing the oxide composite of the present invention (photocatalyst dispersion, further, visible light responsive photocatalyst dispersion) uses a reaction liquid that has undergone step (A), step (B), and step (C1), step (C2), step (C3), or step (C4).

[0170] Conventional dispersions of visible light responsive photocatalysts could not be made uniform unless a dispersant was used.

[0171] A dispersant may be added to the dispersion containing the oxide composite of the present invention. The dispersion containing the oxide composite of the present invention has much better dispersibility than a typical visible light responsive photocatalyst, even without adding a dispersant.

[0172] The dispersion containing the oxide composite of the present invention has good dispersibility, resulting in excellent crack resistance of the coating. The dispersion containing the oxide composite of the present invention does not require the addition of a dispersant, making it possible to form a dense titania coating, and is excellent in coatability and transparency as well as visible light catalytic activity.

[0173] In the dispersion containing the oxide composite, the content of water as the main solvent is preferably 50% by mass or more, and more preferably 60% by mass or more, from the viewpoints of ease of coating, film properties of the coating, etc., where the total amount of the dispersion containing the oxide composite is taken as 100% by mass.

[0174] It is also possible to remove the oxide composite from the reaction solution and change the solvent. Water may be removed from the reaction solution by centrifugation, a filtration membrane, or the like, and the solvent may be replaced with an organic solvent. From the viewpoints of dispersibility, transparency, and the like, it is preferable not to dry the oxide composite.

[0175] The organic solvent used in the dispersion is preferably an alcohol, etc. The alcohol is preferably an aliphatic alcohol having 1 to 6 carbon atoms, such as methanol, ethanol, propanol, or isopropanol, or a non-aliphatic alcohol, such as α-terpineol; a glycol solvent, such as butyl carbitol (diethylene glycol monobutyl ether), hexylene glycol (2-methyl-2,4-pentanediol), ethylene glycol-2-ethylhexyl ether, ethylene glycol monomethyl ether, or propylene glycol monomethyl ether; or a diol, such as 1,4-butanediol, 1,5-pentanediol, or 1,6-hexanediol.

[0176] The organic solvent used in the dispersion liquid preferably has affinity with titania and other solvents (water, alcohol, etc.), even if it does not have an OH group. Examples of the organic solvent include diethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dibutyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol diacetate, triethylene glycol diacetate, and tetraethylene glycol diacetate. From the viewpoint of boiling point, etc., more preferably, diethylene glycol monobutyl ether acetate, tetraethylene glycol dimethyl ether, etc. are used as the organic solvent.

[0177] Paint containing oxide complexes The viscosity of the dispersion containing the oxide composite is preferably adjusted depending on the application to form a paint. When the paint is applied by spin coating, dip coating, spraying, or the like, the viscosity is preferably adjusted to a low level. When the paint is applied by brush coating, squeegee, or the like, the viscosity is preferably adjusted to a higher level. When the paint is applied by screen printing, the viscosity is preferably adjusted to a higher level to suppress flowability.

[0178] Coating containing oxide complexes The resulting coating film containing the oxide complex allows for a dense coating.

[0179] The coated product having a coating film is not particularly limited, and examples thereof include building materials, building exteriors, building interiors, window frames, window glass, various lenses, structural members, building facilities such as housing, cooking utensils, textile products, furniture, displays, display protective films, plumbing members, vehicle light covers and window glass, exteriors of machinery or articles, dustproof covers and paints, display devices, their covers, traffic signs, various display devices, signs such as billboards, sound insulation walls for roads and railways, exteriors and paints of bridges and guardrails, interiors and paints of tunnels, insulators, solar cell covers, solar hot water heater heat collector covers, and exterior parts of electronic and electrical equipment used outdoors, particularly transparent members, exteriors of vinyl greenhouses, greenhouses, etc. [Example]

[0180] The present invention will be specifically described below with reference to examples.

[0181] The present invention is not limited to the following specific examples.

[0182] [Example 1] To 142.1 g (0.5 mol) of titanium tetraisopropoxide, 30 g (0.5 mol) of acetic acid was added and stirred for 60 minutes. Next, 538 g of water was added and stirred at normal pressure (0.10 MPa) and 95°C for 3 hours. Then, a high-pressure dispersion treatment (160 MPa) was performed to obtain a dispersion liquid containing titanium oxide microparticles.

[0183] The titanium oxide fine particles contained in this dispersion were found to have primary particles with an average size of 3 nm from observation of a transmission electron microscope image, and secondary particles with a size distribution analyzer of 30 nm.

[0184] To 15 g of this dispersion (solid content 5.2 mass%), silver nitrate (I) was added so that the silver content was 25 mass% based on the metal weight of the titania particles (titanium oxide) contained in the dispersion, and the mixture was stirred thoroughly. Then, the mixture was irradiated with an ultraviolet lamp for 3 hours to obtain a white-ish dispersion. The color of the obtained dispersion remained unchanged even after standing for about 3 weeks, confirming that the silver component was stably present in the solution.

[0185] When this dispersion was evaluated using a transmission electron microscope, it was found that the primary particle size of the titanium oxide particles coating the silver particles was 70 nm, the primary particle size of the titanium oxide particles was 4 nm, the coverage rate was 20% of the surface, and the randomness rate was 98%. This indicates that the dispersion contains an oxide composite in which part of the surface of the silver nanoparticles is randomly coated with titanium oxide nanoparticles.

[0186] [ka]

[0187] A 0.7mm thick, 50mm square glass sheet with a solid content of 60mg / m 2 After coating the dispersion liquid, the substrate was dried at 80°C and measured with a spectrophotometer (Konica Minolta CM-36sG), and the haze change of the coating film was 0.3. It can be seen that the coating film of Example 1 has excellent transparency.

[0188] Even when the coating surface of the obtained glass substrate was rubbed strongly with a finger, the coating did not slide off, which shows that the coating of Example 1 has a high degree of adhesion between the titania particles and the glass surface.

[0189] The obtained glass substrate was subjected to an antibacterial test in accordance with JIS Z 2801, after which a load of 750 g was applied using a Hayden friction tester and the antibacterial activity value was 3.0 or more. It was confirmed that the glass substrate having the coating surface of Example 1 maintained its antibacterial properties even after wiping with water.

[0190] [Example 2] 30g (0.5mol) of acetic acid was added to 142.1g (0.5mol) of titanium tetraisopropoxide and stirred for 60 minutes, then 538g of water was added and stirred at normal pressure (0.10MPa) and 95℃ for 3 hours, followed by high-pressure dispersion treatment (160MPa) to obtain a dispersion containing titanium oxide fine particles. Observation of transmission electron microscope images of the titanium oxide fine particles contained in this dispersion showed that the primary particles had an average size of 3nm, and particle size distribution analysis showed that the secondary particles had a size of 30nm.

[0191] To 15 g of this dispersion (solid content 5.2 mass%), silver acetate (I) was added so that the silver content was 5 mass% based on the metal weight of the titania particles (titanium oxide) contained in the dispersion, and the mixture was stirred thoroughly. Then, the mixture was irradiated with a UV lamp for 3 hours to obtain a white-ish dispersion. The color of the obtained dispersion remained unchanged even after being left for about 3 weeks, confirming that the silver component was stably present in the solution.

[0192] When this dispersion was evaluated using a transmission electron microscope, it was found that the titanium oxide particles coating the silver particles had a particle size of 30 nm, a primary particle size of 4 nm, and a surface coverage of 23%. The randomness was 99%. This indicates that the dispersion contains an oxide composite in which part of the surface of the silver particles is randomly coated with titanium oxide particles.

[0193] A 0.7mm thick, 50mm square glass sheet with a solid content of 60mg / m 2 After coating the dispersion liquid, the substrate was dried at 80°C and measured with a spectrophotometer (Konica Minolta CM-36sG), and the haze change of the coating film was 0.2. It can be seen that the coating film of Example 2 has excellent transparency.

[0194] Even when the coating surface of the obtained glass substrate was rubbed strongly with a finger, the coating did not slide off, which shows that the coating of Example 2 has a high degree of adhesion between the titania particles and the glass surface.

[0195] The obtained glass substrate was subjected to an antibacterial test in accordance with JIS Z 2801, after which a load of 750 g was applied using a Hayden friction tester and the antibacterial activity value was 3.0 or more. It was confirmed that the glass substrate having the coating surface of Example 2 maintained its antibacterial properties even after wiping with water.

[0196] [Example 3] A 20% by mass aqueous dispersion of silica fine particles with a primary particle size of 12 nm was diluted 10 times with distilled water and subjected to high-pressure dispersion treatment (200 MPa) to obtain 100 g of a 2% by mass aqueous dispersion. The titanium oxide fine particles contained in this dispersion were found to have an average primary particle size of 12 nm based on observation using a transmission electron microscope, and secondary particles of 80 nm based on particle size distribution analysis.

[0197] To this aqueous dispersion, silver microparticles with a particle size of 100 nm were added so that the weight of silver contained in the silver microparticles was 5 mass% relative to the weight of silica in the silica microparticles, and the mixture was stirred and mixed at room temperature for 24 hours to obtain an aqueous dispersion of silver microparticles coated with silica microparticles.

[0198] When this dispersion was evaluated using a transmission electron microscope, it was found that the primary particle size of the silver particles and the silica particles covering the silver particles were 100 nm and 12 nm, respectively, and the coverage was 50% of the surface. The randomness was 80%. This indicates that the dispersion contains an oxide composite in which part of the surface of the silver particles is randomly covered with titanium oxide particles.

[0199] A 0.7mm thick, 50mm square glass sheet with a solid content of 60mg / m 2 After coating the dispersion liquid, the substrate was dried at 80°C and measured with a spectrophotometer (Konica Minolta CM-36sG), and the haze change of the coating film was 0.5. It can be seen that the coating film of Example 3 has excellent transparency.

[0200] Even when the coating surface of the obtained glass substrate was rubbed strongly with a finger, the coating did not slide off, which shows that the coating of Example 2 has a high degree of adhesion between the titania particles and the glass surface.

[0201] The obtained glass substrate was subjected to an antibacterial test in accordance with JIS Z 2801, after which a load of 750 g was applied using a Hayden friction tester and the antibacterial activity value was 3.0 or more. It was confirmed that the glass substrate having the coating surface of Example 2 maintained its antibacterial properties even after wiping with water.

[0202] [Comparative Example 1] (silver nanoparticles only) A dispersion of commercially available silver nanoparticles (Sigma-Aldrich) with a particle size of 100 nm was applied to a glass substrate.

[0203] When the coating surface of the obtained glass substrate was rubbed with a finger, peeling was confirmed. The coating film of Comparative Example 1 could not be used for further evaluation.

[0204] Comparative Example 2 (silica supported silver) To 100 g of an aqueous dispersion of silica microparticles with a particle size of 150 nm, silver microparticles with a particle size of 15 nm were added so that the amount of silver contained in the silver microparticles was 1 mass % relative to the amount of silica in the silica microparticles, and the mixture was stirred and mixed at room temperature for 24 hours to obtain a 25 mass % aqueous dispersion of silver microparticle-supported silica microparticles.

[0205] When the obtained dispersion was left to stand for about a week, the solution became cloudy and a white precipitate formed.

[0206] When this dispersion was evaluated using a transmission electron microscope, it was found that the particle size of the silver particles was 15 nm, the particle size of the silica particles was 150 nm, the coverage rate was 100% of the surface, and the random rate was 0%.

[0207] This dispersion was applied to a 50 mm square glass substrate with a thickness of 0.7 mm, and the substrate was dried at 80°C. Measurement was performed using a spectrophotometer (Konica Minolta CM-36sG), and the haze change of the coating film was found to be 2 or more. It can be seen that the dispersion of Comparative Example 2 was inferior in transparency to Examples 1 to 3.

[0208] Even when the coated surface of the obtained glass substrate was rubbed strongly with a finger, the coating did not slide off.

[0209] The obtained glass substrate was subjected to an antibacterial test in accordance with JIS Z 2801 after wiping with water under a load of 750 g using a Hayden friction tester, and the antibacterial activity value was less than 2.0. The glass substrate having the coating surface of Comparative Example 2 was unable to maintain its antibacterial properties after wiping with water.

[0210] Comparative Example 3 (Silver nanoparticles are supported on secondary particles of titanium oxide nanoparticles) To 142.1 g (0.5 mol) of titanium tetraisopropoxide, 30 g (0.5 mol) of acetic acid was added and stirred for 60 minutes. Next, 538 g of water was added and stirred at normal pressure (0.10 MPa) and 85°C for 3 hours. Then, ultrasonic dispersion treatment was performed to obtain a dispersion liquid containing titanium oxide microparticles.

[0211] Observation of a transmission electron microscope image of the titanium oxide fine particles contained in this dispersion showed that the primary particles had an average size of 5 nm, and measurement of a particle size distribution analyzer showed that the secondary particles had an average size of 2 μm.

[0212] To 15 g of this dispersion (solid content 5.2 mass%), silver nitrate (I) was added so that the silver content was 25 mass% based on the metal weight of the titania fine particles (titanium oxide) contained in the dispersion, and the mixture was stirred well. Then, the mixture was irradiated with an ultraviolet lamp for 30 minutes to obtain a white-ish dispersion. After 3 weeks, the obtained dispersion did not maintain its dispersion stability, and precipitation was observed.

[0213] The dispersion immediately after being composited with silver was evaluated using a transmission electron microscope. It was found that the titanium oxide nanoparticles coating the silver nanoparticles had a primary particle size of 40 nm, a primary particle size of the titanium oxide nanoparticles of 4 nm, and a structure in which the silver nanoparticles were supported on the secondary silver particles. The coverage rate was 100% of the surface, and the random rate was 0%. This indicates that the dispersion has a structure in which the silver nanoparticles are supported on the secondary titanium oxide nanoparticles.

[0214] A 0.7mm thick, 50mm square glass sheet with a solid content of 60mg / m 2After applying this dispersion to the substrate, the substrate was dried at 80°C and measured with a spectrophotometer (Konica Minolta CM-36sG), and the haze change of the coating film was found to be 2 or more. It can be seen that the dispersion of Comparative Example 3 is inferior in transparency to Examples 1 to 3.

[0215] Even when the coated surface of the obtained glass substrate was rubbed strongly with a finger, the coating did not slide off.

[0216] The obtained glass substrate was subjected to an antibacterial test in accordance with JIS Z 2801 after wiping with water under a load of 750 g using a Hayden friction tester, and the antibacterial activity value was less than 2.0. The glass substrate having the coating surface of Comparative Example 2 was unable to maintain its antibacterial properties after wiping with water.

[0217] [Industrial Applicability] The oxide composite of the present invention has a structure in which inorganic oxide fine particles (titania, etc.) are supported on the periphery of silver fine particles. The oxide composite of the present invention has a structure in which inorganic oxide fine particles (titania, etc.) are coated on the periphery of silver fine particles. By performing a high-pressure dispersion treatment and controlling the secondary particle size of the inorganic oxide fine particles (titania nanoparticles, etc.)-supported silver fine particles, the periphery of the silver is coated with titanium oxide, making it possible to prepare a dispersion in which the silver is uniformly and stably dispersed in a liquid.

[0218] The oxide composite of the present invention is formed by coating silver nanoparticles with a sol of inorganic oxide fine particles (titanium oxide, etc.), thereby improving the resistance of silver to elution into water, maintaining the antibacterial and antiviral properties of the silver contained in the oxide composite, and also maintaining the adhesion of the oxide composite to a substrate, the transparency of the oxide composite, etc.

Claims

1. An oxide composite, (A) The surface of the silver particles is partially coated with (B) inorganic oxide particles, the (A) silver fine particles have an average primary particle diameter of 1 nm to 1,000 nm, The inorganic oxide fine particles (B) have an average primary particle diameter of 1 nm to 100 nm. Oxide complex.

2. 2. The oxide composite according to claim 1, wherein the (A) silver fine particles have an average primary particle diameter of 1 nm to 200 nm.

3. 2. The oxide composite according to claim 1, wherein the (A) silver fine particles have a surface coverage of 1% or more.

4. 2. The oxide composite according to claim 1, wherein the (A) silver fine particles have a surface coverage of 5 to 95 surface %.

5. The ratio of the average primary particle size of the (A) silver fine particles to the average primary particle size of the (B) inorganic oxide fine particles ((A) average primary particle size of silver particles / (B) average primary particle size of inorganic oxide particles) is 2. The oxide composite according to claim 1, wherein the ρ is 0.5 or more.

6. The ratio of the average primary particle size of the (A) silver fine particles to the average primary particle size of the (B) inorganic oxide fine particles ((A) average primary particle size of silver particles / (B) average primary particle size of inorganic oxide) 2. The oxide composite according to claim 1, wherein the molecular weight is 1 or more and 200 or less.

7. 2. The oxide composite according to claim 1, wherein the (B) inorganic oxide fine particles covering the (A) silver fine particles have a random ratio of 50% or more.

8. The mass of titanium oxide (TiO 2 (A) the mass ratio of the silver mass (Ag mass) in the silver fine particles to the mass (A) Ag mass in silver particles / (B) TiO in inorganic oxide particles 2 mass) is 2. The oxide composite of claim 1, wherein Mn is ≦10.

9. In the oxide composite, 2. The oxide composite according to claim 1, wherein the sum of the solid contents of the (A) silver fine particles and the (B) inorganic oxide fine particles is 50 mass % or less.

10. 2. The oxide composite according to claim 1, wherein the inorganic oxide fine particles (B) are titania fine particles (B1).

11. The (B1) titania fine particles are The surface is protected with organic acid, The mass of the organic acid is 1% by mass or more relative to the weight of titanium oxide. The oxide composite according to claim 10.

12. The organic acid is at least one organic acid selected from the group consisting of monocarboxylic acids having 1 to 4 carbon atoms and hydroxycarboxylic acids having 2 to 3 carbon atoms, or An acyloxy group derived from at least one organic acid selected from the group consisting of monocarboxylic acids having 1 to 4 carbon atoms and hydroxycarboxylic acids having 2 to 3 carbon atoms.

12. The oxide composite according to claim 11, wherein

13. 12. The oxide complex according to claim 11, wherein the organic acid is at least one organic acid selected from the group consisting of acetic acid and lactic acid.

14. 11. The oxide composite according to claim 10, wherein the titania fine particles (B1) are positively charged.

15. The oxide composite according to any one of claims 1 to 14, and water, A dispersion containing 0.5% by mass or more of water.

16. 16. The dispersion of claim 15, wherein the pH of the dispersion is pH=1 to 8.

17. An oxide composite according to any one of claims 1 to 14, or Dispersion according to claims 15 to 16 Paint containing.

18. A coating film formed by the coating material according to claim 17.

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