JP4120887B2 - In4Sn3O12 composite oxide fine particles for solar radiation shielding, method for producing the same, coating liquid for solar radiation shielding film formation, solar radiation shielding film, and solar radiation shielding substrate - Google Patents

Description

The present invention is a vehicle, a building, an office, a window for a general house, a telephone box, a show window, a lamp for lighting, a transparent case, a single plate glass, a laminated glass, a plastic, and other bases that require a solar radiation shielding function. The present invention relates to a solar radiation shielding In ₄ Sn ₃ O ₁₂ composite oxide fine particle used for a material, a method for producing the same, a solar radiation shielding coating liquid, a solar radiation shielding film, and a solar radiation shielding substrate.

As a method for removing and reducing a heat component from an external light source such as sunlight or a light bulb, conventionally, a film made of a material that reflects infrared rays is formed on a glass surface and used as a heat ray reflecting glass. As the material, metal materials such as Fe, FeOx, CoOx, CrOx, and TiOx and metal materials having a large amount of free electrons such as Ag, Au, Cu, Ni, and Al have been selected.
However, these materials have a problem of reducing visible light transmittance because they have the property of simultaneously reflecting or absorbing visible light in addition to infrared rays that greatly contribute to the thermal effect. And since the transparent base material used for a building material, a vehicle, a telephone box, etc. needs the high transmittance | permeability of visible region, when using the said material, the film thickness had to be made very thin. For this reason, it has been usually performed to form a thin film of 10 nm level using a physical film forming method such as spray baking, CVD method, sputtering method or vacuum deposition method.
However, these film forming methods require a large-scale apparatus and vacuum equipment, have a problem in productivity and an increase in area, and have a drawback that the manufacturing cost of the film becomes high. Moreover, when it is going to make the solar radiation shielding characteristic (characteristic which shields the light of wavelength range 300-2100 nm) with these materials, there is a tendency that the absorptivity and the reflectance in the visible light region also increase at the same time, like a mirror. Gives a glaring appearance and damages the beauty. Furthermore, many of these materials have high film conductivity. If the film conductivity is high, radio waves from mobile phones, TVs, radios, etc. are reflected and reception becomes impossible, or radio interference is caused in the surrounding area. There is a problem.
In order to improve such a conventional defect, as the physical properties of the film, the reflectance of light in the visible light region is low, the absorption factor or reflectance in the infrared region is high, and the surface resistance of the film is approximately 10 ⁶ Ω. / □ or more is considered necessary.
By the way, indium tin oxide (hereinafter abbreviated as ITO) is described as one of materials having a high visible light transmittance and a low transmittance in the infrared region (hereinafter referred to as solar radiation shielding characteristics). )It has been known. If this ITO is utilized, it is thought that the material which has a solar radiation shielding function will be obtained.
Here, in order to obtain this ITO powder, generally, a method (coprecipitation method) is known in which a precipitant is added to a mixed aqueous solution of indium salt and tin salt and coprecipitated, and this precipitate is dried and fired (coprecipitation method). ing. For example, in Patent Document 1, in order to have a function of cutting off 90% or more of infrared rays on a long wavelength side from a certain wavelength in or near the infrared region of 1000 nm or less, the raw material of ITO powder or the atmosphere A method of heat-treating ITO powder fired in a pressurized inert gas is described.
Patent Document 2 describes a heat treatment method in an alcohol atmosphere as a treatment method for stably reducing the resistance of ITO. In Patent Document 3, as a method for producing ITO fine powder for obtaining an ITO film excellent in transparency and infrared shielding properties, the pH of the reaction system is maintained while maintaining a mixed solution of tin salt and indium salt at 30 ° C. or lower. Hydrate obtained by adding an alkaline aqueous solution at an addition time of 0.5 to 12 hours so that the final value becomes 5.0 to 9.0 in an inert gas atmosphere or a reducing gas atmosphere The method of heat-treating with is described.
Patent Document 4 discloses a conductive oxide raw material comprising a combination of two or more transition metals as a method for producing ultra-fine, low-resistance conductive ITO powder having excellent mass productivity, uniform conductive characteristics and little variation. A method for heat treatment in a pressurized inert gas is described.
However, all of the above-mentioned ITO powders are obtained by adding about 1 to 15% by weight of an Sn compound to an indium compound, and the main metal is expensive indium. It was. Accordingly, the present inventors have searched for an inexpensive and easy-to-manufacture solar shading material that can replace the above-mentioned ITO while having predetermined solar shading characteristics.
Here, as a substance having a low indium content, conventionally, in the field of development of conductive materials, an indium oxide-based conductive powder containing at least one dopant and a tin oxide-based conductive powder containing at least one dopant are used. Composite conductive powder (patent document 5) mixed and fired at 3: 7 to 7: 3, In ₄ Sn ₃ O obtained by mixing indium oxide and tin oxide as a conductive film material and firing in air ₁₂ (Non-patent Document 1), In ₄ Sn ₃ O ₁₂ transparent conductive film (Non-patent Document 2) and the like formed by sputtering.
Patent Document 1: Japanese Patent Application Laid-Open No. 7-69632 Patent Document 2: Japanese Patent Application Laid-Open No. 5-24837 Patent Document 3: Japanese Patent No. 312375 Patent Document 4: Japanese Patent Application Laid-Open No. 7-21831 Patent Document 5: Japanese Patent Application Laid-Open No. 7-2008 No. 335031 Non-patent document 1: H. Enoki and J.M. Echigoya: Phys. Status Solidi (a), 132, K1 (1992)
Non-Patent Document 2: New development of transparent conductive film, CMC, p. 58 (1993)

However, even if the solar radiation shielding film is formed using the indium compound described in Patent Document 5 and Non-Patent Document 1, the solar radiation transmittance is reduced while ensuring the desired visible light transmittance, which will be described later in this specification. In addition to being unable to do so, it becomes a so-called high haze film and does not have characteristics as a film for shielding solar radiation.
The invention described in Non-Patent Document 2 relates to a transparent conductive film formed by a physical film formation method with high production cost, and cannot be applied to a solar radiation shielding film with low production cost, which is an object of the present invention. It was a thing.
The present invention has been made to solve the above-mentioned problems, and is a composite oxidation for solar radiation shielding, which is cheaper in raw material cost than conventional ITO and can be easily manufactured and has high productivity. An object of the present invention is to provide a fine particle, a production method thereof, a coating solution for forming a solar shading film, a solar shading film, and a solar shading base material.
A first means for solving the above-mentioned problems is that the average primary particle diameter of the fine particles is 400 nm or less, and the powder color in the L ^* a ^* b ^* color system is L ^* is 30 to 70, a ^*. Is -9.0 to -0.1 and b ^* is -15.0 to 4.0. In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding.
The second means includes at least one element selected from Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, Re, Ru, P, and Ge. The In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding according to claim 1, characterized in that they are characteristic.
The third means is a step of reacting a raw material mixed solution containing a tin compound and an indium compound with an alkali solution and aging the mixture continuously to obtain a precipitate, and washing the precipitate by decantation. And drying to obtain a hydroxide or hydrate powder comprising indium and tin, and the hydroxide or hydrate powder is mixed with an inert gas or an inert gas and a reducing gas. atmosphere, a method of manufacturing calcined to _in 4 _Sn 3 _{O 12} composite oxide obtained microparticles step and, solar radiation shielding _in 4 _Sn 3 _{O 12} composite oxide fine particles, characterized by comprising at 1200 ° C. or higher It is.
The fourth means is a tin compound, an indium compound, and at least selected from Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, Re, Ru, P, and Ge. A first step of reacting a raw material mixed solution containing a compound containing one kind of element with an alkaline solution and aging with continuous stirring to obtain a precipitate, obtained in the first step The resulting precipitate is washed by decantation and then dried to form indium, tin, Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, Re, Ru, P, and Ge. A second step of obtaining a hydroxide or hydrate powder containing at least one element selected from the above, and the hydroxide or hydrate powder obtained in the second step, an inert gas or Mixed gas atmosphere of inert gas and reducing gas At least one selected from Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, Re, Ru, P, and Ge after firing at 1200 ° C. or higher And a third step of obtaining In ₄ Sn ₃ O ₁₂ composite oxide microparticles containing the above elements. The method for producing In ₄ Sn ₃ O ₁₂ composite oxide microparticles for solar radiation shielding is provided.
5. The solar radiation shielding In according to claim ₃ , wherein the fifth means comprises a step of crushing the In ₄ Sn ₃ O ₁₂ composite oxide fine particles by a mechanical method. This is a method for producing ₄ Sn ₃ O ₁₂ composite oxide fine particles.
The sixth means is characterized in that the pH of the solution after reacting the raw material mixed solution and the alkali solution is 4.0 to 9.0. The method for producing In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding according to claim 1.
The seventh means is carried out until the conductivity of the cleaning liquid becomes 1 mS / cm or less when the precipitate is decanted. In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding.
The eighth means is a solar shading film-forming coating solution in which a solar shading material is dispersed in a solvent, wherein the solar shading material is the solar shading In ₄ Sn according to claim 1 or 2. _A coating solution for forming a solar shading film, characterized in that it contains ₃ O ₁₂ composite oxide fine particles.
9. The solar radiation shielding film according to claim 8, wherein at least one kind of fine particles selected from boride fine particles, antimony tin oxide fine particles, and tungsten oxide fine particles is added to the ninth means. This is a forming coating solution.
The tenth means is the solar shading film-forming coating solution according to claim 8 or 9, wherein an inorganic binder or a resin binder is contained.
The eleventh means is a solar shading film formed by using the solar shading film forming coating solution according to any one of claims 8 to 10.
A twelfth means is a solar shading base material characterized in that the solar shading film according to claim 11 is formed on glass or plastic.
The thirteenth means is the solar shielding In ₄ Sn ₃ O ₁₂ composite oxide fine particles according to claim 1 or 2, or the claims 8 to 10 according to any one of claims 8 to 10. This solar shading film-forming coating liquid is kneaded into a base material forming base material and formed into a plate shape, a sheet shape, or a film shape.
The fourteenth means is a method in which another substrate is laminated on the solar shading base material so as to sandwich the solar shading film of the solar shading base material according to claim 12. A solar radiation shielding base material characterized in that the solar radiation shielding base material described in the item is sandwiched and laminated by another base material.
As described above in detail, according to the present invention, the In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding, which can be produced inexpensively and easily compared with conventional ITO and the like, and a method for producing the same In addition, it is possible to provide a coating solution for forming a solar radiation shielding film, a solar radiation shielding film, and a solar radiation shielding substrate.

  FIG. 1 is a list of properties of composite oxide fine particles and film characteristics of solar radiation shielding films according to Examples and Comparative Examples.

In the above-described means, the type of fine particles is In ₄ Sn ₃ O ₁₂ composite oxide fine particles for the following reason. First, as a material used for solar radiation shielding, it must basically have an optical characteristic capable of exhibiting the solar radiation shielding function. That is, the material must have a property of transmitting / reflecting light that transmits visible light but does not transmit infrared light.
Here, the inventor has paid attention to the fact that the wavelength dependency of the light transmittance of a substance depends on the plasma frequency inherent to the substance. That is, as a result of the interaction between light and electrons in the substance, each substance has its own plasma frequency, but light with a wavelength longer than this intrinsic plasma frequency is reflected and light with a shorter wavelength is transmitted. Are known. The plasma frequency ω _p is expressed by equation (1).
ω _p ² = nq ² / εm (1)
Here, n is the conduction electron density, q is the charge of the electron, ε is the dielectric constant, and m is the effective mass of the electron.
In general, the plasma frequency depends on the conduction electron density of the substance. When the conduction electron density increases, the plasma frequency also increases, and light on the short wavelength side is reflected.
For example, the conduction electron density of metal is 10 ²² / cm ³ , whereas the conventional ITO is 10 ²¹ / cm ³ . For this reason, in the case of metal, the reflectance is already high from the visible light region, but in the case of ITO, visible light is transmitted and the reflectance is high from the near infrared region.
The inventor of the present application searched for a substance having a conduction electron density comparable to that of conventional ITO. As a result, an In ₄ Sn ₃ O ₁₂ composite oxide was found. This In ₄ Sn ₃ O ₁₂ composite oxide is the same indium oxide-tin oxide based material as that of conventional ITO, but the conventional ITO contains about 1 to 15% by weight of Sn-containing material in terms of Sn. On the other hand, the In ₄ Sn ₃ O ₁₂ composite oxide is different in that it contains about 39% by weight of a Sn-containing substance in terms of Sn. That is, it is inexpensive because the content of expensive In is very small compared to conventional ITO. However, the In ₄ Sn ₃ O ₁₂ composite oxide according to the conventional technology (for example, the In ₄ Sn ₃ O ₁₂ composite oxide described in Non-Patent Document 1) has a desired visible light transmittance as described above. In addition to being unable to reduce the solar transmittance while ensuring, it becomes a so-called high-haze film and does not have the characteristics as a film for shielding solar radiation.
Here, the present inventors have repeated trial and error, have an average primary particle diameter of 400 nm or less, having a predetermined characteristic as a solar radiation shielding material, and a powder color L ^* in the L ^* a ^* b ^* color system ^. but 30 to 70, ^{a *} is -9.0~-0.1, ^{b *} was conceived sunlight shielding _in 4 _Sn 3 _{O 12} composite oxide is -15.0～4.0.
The reason why the average primary particle diameter of the In ₄ Sn ₃ O ₁₂ composite oxide for solar radiation shielding is 400 nm or less is that the composite oxide becomes a scattering source when the average primary particle diameter is 400 nm or less. This is because the film can be prevented from becoming cloudy, that is, haze, or causing a decrease in visible light transmittance. In the present specification, the particle size is expressed as an average primary particle diameter. However, for the reasons described above, a fine powder having a narrow particle size distribution with a small proportion of coarse powder exceeding 400 nm is preferable.
Further, the In ₄ Sn ₃ O ₁₂ composite oxide fine particles have a powder color L ^* of 30 to 70, a ^* of −9.0 to −0.1, and b ^{* in} the L ^* a ^* b ^* color system. The reason for being -15.0 to 4.0 is considered as follows.
When the In ₄ Sn ₃ O ₁₂ composite oxide fine particles are heat-treated in an inert gas alone, a mixed gas of a reducing gas and an inert gas, or an alcohol-containing inert gas atmosphere, the powder color is yellow → yellowish green → At the same time as the change from light blue to dark blue, the dust resistance also decreases. This is because the In ₄ Sn ₃ O ₁₂ composite oxide fine particles were heat-treated in the gas atmosphere as described above to generate vacancies in the fine particles, and the increase in the vacancies increased the free electrons in the fine particles. Conceivable. That is, it is expected that the powder color of fine particles and the conduction electron density, that is, the plasma frequency have a deep relationship.
Therefore, the relationship between the In ₄ Sn ₃ O ₁₂ composite oxide fine particles and the solar transmittance when these are formed is investigated in detail, and the conditions under which high transmittance at 850 nm and high solar shielding performance are exhibited. were _determined, in ₄ Sn _{3 O 1 2} composite oxide fine particles of the ^L * ^a * ^{b *} color system powder color ^{L *} is 30 to 70 by, ^{a *} is -9.0~-0.1, b ^{When *} is in the range of -15.0 to 4.0, it is conceived that the desired solar radiation shielding function is exhibited.
Further, if necessary, for the purpose of improving the characteristics in a desired function, the In ₄ Sn ₃ O ₁₂ composite oxide fine particles are changed to Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, It is also a preferred configuration to add at least one element selected from Ga, Re, Ru, P and Ge.
Next, a method for producing the solar shielding In ₄ Sn ₃ O ₁₂ composite oxide fine particles according to the above-described means will be described.
The first step is to convert a tin compound and an indium compound, or a tin compound and an indium compound, and if necessary, Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, In the process of obtaining a precipitate by reacting a raw material mixed solution containing a compound containing at least one element selected from Re, Ru, P and Ge with an alkali solution and aging with continuous stirring. is there.
The second step is a step in which the precipitate obtained in the first step is sufficiently washed by decantation and then dried to obtain a hydroxide powder composed of indium and tin.
In the third step, the hydroxide powder obtained in the second step is calcined at 1200 ° C. or higher in an inert gas or a mixed gas atmosphere of an inert gas and a reducing gas, and In ₄ Sn ₃ O _This is a step of obtaining ₁₂ composite oxide particles.
In the fourth step, the In ₄ Sn ₃ O ₁₂ composite oxide particles obtained in the third step are crushed by a mechanical method to obtain a solar radiation shielding material comprising the In ₄ Sn ₃ O ₁₂ composite oxide fine particles. It is a process to obtain.
Hereinafter, each step will be described in more detail.
First, in the first step, the indium compound and the tin compound applied in the present invention are not particularly limited, and examples thereof include indium nitrate, indium chloride, tin chloride, and tin nitrate.
A compound containing at least one element selected from Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, Re, Ru, P and Ge, which is added as necessary, Although not particularly limited, those that are water-soluble or soluble in organic solvents are preferred. As for the addition amount, when the element of the compound to be added is X, X / (In ₂ O ₃ or SnO ₂ + X) is preferably 0.1 to 15% by weight. This is because a desired solar shading characteristic can be obtained within this range.
Moreover, the alkaline solution used by this invention is not specifically limited, either, For example, each aqueous solution, such as ammonium hydrogencarbonate, ammonium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, is mentioned. The concentration of the alkali component is not less than the chemical equivalent necessary for each salt to become a hydroxide or a hydrate, preferably from an equivalent to an equivalent 1.5-fold excess from the viewpoint of washing time due to residual alkali. . The solution temperature at this time is not particularly limited, but it is usually preferably 100 ° C. or less from the viewpoint of productivity. The lower limit of the solution temperature is not particularly limited due to the characteristics of the obtained In ₄ Sn ₃ O ₁₂ composite oxide fine particles, but if it is too low, a cooling device or the like is newly required. It is preferable to set the temperature so as not to require such an apparatus.
The time for the neutralization reaction is not particularly limited, but is preferably less than 30 minutes, preferably 25 minutes or less from the viewpoint of productivity. After completion of the neutralization reaction, aging is carried out with continuous stirring to make the system uniform, and the temperature at that time is the same as the coprecipitation temperature. Moreover, although time is not specifically limited, From a viewpoint of productivity, it is 30 minutes or less, Preferably it is 15 minutes or less.
Here, although a hydroxide or a hydrate is obtained as a precipitate, the average primary particle size of the In ₄ Sn ₃ O ₁₂ composite oxide fine particles is determined at this stage, and therefore, several nm to 100 nm. It is necessary to control the conditions so that For this purpose, the concentration of the raw material in the solution is increased to increase the concentration (Q) of the precipitation component ions, the solution temperature is decreased to decrease the solubility (S) of the precipitate, and the relative supersaturation ratio (however, It is preferable to increase the value of the supersaturation ratio = (Q−S) / S). When a precipitate is generated from a state where the value of the relative supersaturation ratio is large, a large number of precipitation component nuclei are generated at one time, and a uniform and fine precipitate is obtained. Moreover, it is preferable in terms of particle size control that the pH of the solution after reacting the raw material mixed solution and the alkaline solution is 4.0 to 9.0. When the pH is lower, the particle size of the precipitate tends to be finer.However, if the pH is too low, the precipitation of the precipitate is insufficient. This is because the diameter becomes too large.
Next, in the second step, the precipitate obtained by aging in the first step is sufficiently washed by decantation. At this time, the electrical conductivity of the cleaning supernatant liquid is 1 mS / cm or less due to the influence that the residual impurities in the precipitate cause the optical properties of the In ₄ Sn ₃ O ₁₂ composite oxide, particularly the solar radiation shielding rate, to decrease. After washing up to (the amount of residual chlorine impurities corresponds to 0.2% by weight or less), it is dried. There is no particular limitation on the drying temperature and the time after the washing treatment.
Next, in the third step, the hydroxide or hydrate powder dried in the second step is heat-treated in an inert gas or a mixed gas atmosphere of an inert gas and a reducing gas. Although the In ₄ Sn ₃ O ₁₂ composite oxide can be obtained even when the heat treatment is performed in the air, the In ₄ Sn ₃ O ₁₂ composite oxide has low electron shielding properties due to insufficient electron density. The heat treatment temperature at this time is 1200 ° C. or higher, more preferably 1300 ° C. or higher, and further preferably 1400 ° C. or higher from the viewpoint of producing In ₄ Sn ₃ O ₁₂ composite oxide particles. This is because if it is 1200 ° C. or higher, a composite oxide can be obtained instead of a mixed phase separated into two phases of indium oxide and tin oxide. Although the upper limit temperature is not particularly limited, excessive growth of particles due to sintering can be avoided if it is 1600 ° C. or lower. If the particles grow excessively, the pulverization operation in the subsequent process, for example, the crushing / dispersing efficiency by the bead mill at the time of preparing the coating liquid is lowered, and this causes high haze at the stage where the solar radiation shielding film is formed. Accordingly, the heat treatment temperature is preferably 1400 to 1600 ° C, and most preferably 1500 ° C.
In addition, the hydroxide powder or hydrate dried in the second step, which is the In ₄ Sn ₃ O ₁₂ composite oxide particle precursor, is once fired in the atmosphere to form a mixed phase of indium oxide and tin oxide. In ₄ Sn ₃ O ₁₂ composite oxide fine particles similar to the present invention can also be obtained when heat treatment is performed in an atmosphere of an inert gas or a mixed gas of an inert gas and a reducing gas after formation. However, in this case, since the firing step is two steps, from the viewpoint of productivity, heat treatment is performed in an inert gas or a mixed gas atmosphere of an inert gas and a reducing gas from the beginning as described above. Is preferred.
Next, in the fourth step, it is desirable to perform the crushing treatment of the In ₄ Sn ₃ O ₁₂ composite oxide particles by a mechanical method. The crushing treatment method is not particularly limited as long as it breaks the aggregation of the primary particles of the composite oxide particles and can pulverize the partially grown particles to form fine particles, but considering the crushing efficiency, it is like a jet mill. A media-mediated crushing apparatus such as a self-pulverized impact crusher or a bead mill is preferred. By the steps described above, In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar shading that have high visible light transmittance and exhibit high solar shading performance can be obtained.
Next, a solar shading film-forming coating solution according to the above-described means using the solar shading In ₄ Sn ₃ O ₁₂ composite oxide fine particles and a manufacturing method thereof will be described in detail.
The coating solution for forming a solar shading film according to the above means is obtained by dispersing the In ₄ Sn ₃ O ₁₂ composite oxide particles in a solvent as a solar shading material. The dispersion solvent is not particularly limited, and can be appropriately selected according to coating conditions and coating environment. Furthermore, when an inorganic binder or a resin binder is contained in the coating solution for forming a solar shading film, it can be appropriately selected according to the binder. Specific examples include alcohols such as water, ethanol, propanol, butanol, isopropyl alcohol, isobutyl alcohol, diacetone alcohol, ethers such as methyl ether, ethyl ether, propyl ether, esters, acetone, methyl ethyl ketone, diethyl ketone, Various organic solvents such as ketones such as cyclohexanone and isobutyl ketone can be used, and the pH may be adjusted by adding acid or alkali as necessary. Furthermore, various surfactants and coupling agents can of course be added to further improve the dispersion stability of the fine particles in the coating solution.
Moreover, the kind of the inorganic binder and the resin binder that are blended into the coating solution for forming the solar shading film as needed is not particularly limited. For example, a silicon, zirconium, titanium, or aluminum metal alkoxide, a partially hydrolyzed polycondensation product thereof, or an organosilazane can be used as an inorganic binder. A thermoplastic resin such as an acrylic resin or a heat such as an epoxy resin can be used as a resin binder. A curable resin can be used.
The method for dispersing In ₄ Sn ₃ O ₁₂ composite oxide particles at the time of producing the coating solution for forming a solar shading film is not particularly limited as long as it is a method of uniformly dispersing in a solvent. For example, a bead mill, ball mill, sand mill , Paint shaker, ultrasonic homogenizer and the like.
The electroconductivity of the film when the solar radiation shielding film is formed using this coating solution can be obtained by the movement of electrons along the conductive path passing through the contact portion of the In ₄ Sn ₃ O ₁₂ composite oxide fine particles. Therefore, by adjusting the amount of, for example, a surfactant or a coupling agent in the coating solution for forming the solar shading film, the conductive path can be partially cut, and the conductivity of the film is 10 ⁶ Ω / □. It is easy to reduce to the above surface resistance value. The conductivity of the solar shading film can also be controlled by adjusting the content of the inorganic binder or the resin binder in the solar shading film forming coating solution.
Next, the solar shading film formed with the solar shading film forming coating solution will be described.
The solar shading film according to the above means is formed by applying the solar shading film forming coating liquid, which is the above-described In ₄ Sn ₃ O ₁₂ composite oxide fine particle dispersed coating liquid, onto a transparent substrate. The solar shading film is a film formed by depositing the above In ₄ Sn ₃ O ₁₂ composite oxide fine particles at a high density, and the resin binder or inorganic binder contained in the coating liquid is In ₄ after coating and curing. There is an effect of improving the adhesion of the Sn ₃ O ₁₂ composite oxide fine particles to the substrate and further improving the hardness of the film.
On the solar shading film obtained in this way, a film made of a metal alkoxide of silicon, zirconium, titanium, or aluminum, or a partially hydrolyzed polycondensation product thereof is applied as a second layer, and silicon, zirconium, By forming an oxide film of titanium or aluminum, it is possible to further improve the binding force to the base material of the film mainly composed of In ₄ Sn ₃ O ₁₂ composite oxide fine particles, the hardness of the film, and the weather resistance. it can.
Further, the film to be obtained using a coating solution containing no resin binder or an inorganic binder in the coating solution, only the In ₄ Sn ₃ O ₁₂ composite oxide fine particles is the film structure deposited on a substrate. Although the solar radiation shielding effect is exhibited as it is, a coating liquid containing an inorganic binder or a resin binder such as a metal alkoxide of silicon, zirconium, titanium, or aluminum or a partially hydrolyzed polycondensation product thereof is further coated on this film. It is preferable to form a multilayer film. By doing so, the coating liquid component is formed to fill the gap where the first layer of In ₄ Sn ₃ O ₁₂ composite oxide fine particles are deposited, so that the haze of the film is further reduced and the visible light transmittance is reduced. And the binding property of the particles to the base material is improved.
Further, the coating method for the solar shading film-forming coating solution according to the above means and the coating method for forming a film used in the present invention are not particularly limited. For example, spin coating method, bar coating method, spray coating method, dip coating Any method may be used as long as the processing liquid can be applied flatly, thinly and uniformly, such as a coating method, a screen printing method, a roll coating method, or a flow coating method.
Further, when the coating solution for forming a solar shading film according to the above means contains a metal alkoxide of silicon, zirconium, titanium, or aluminum and a hydrolysis polymer thereof as an inorganic binder, the substrate heating temperature after coating of the coating solution is Below 100 ° C., the polymerization reaction of the alkoxide or its hydrolysis polymer contained in the coating film often remains incomplete, and water and organic solvents remain in the film and are visible in the solar shading film after heating. It may cause a decrease in light transmittance. Therefore, the substrate heating temperature after coating is preferably 100 ° C. or higher, more preferably heating at the boiling point of the solvent in the coating solution. On the other hand, when the resin binder is contained in the solar shading film-forming coating solution, it may be cured according to the respective curing method. For example, if it is an ultraviolet curable resin, it may be irradiated with ultraviolet rays as appropriate, and if it is a room temperature curable resin, it may be left as it is after application. By using the configuration, application to an existing window glass or the like can be performed on site.
In the solar shading film according to the present invention, since the In ₄ Sn ₃ O ₁₂ composite oxide fine particles are dispersed, the crystal is densely filled like an oxide thin film manufactured by a physical film forming method. Compared with a film having a mirror-like surface, there is less reflection in the visible light region, and it can be avoided that it has a glaring appearance. On the other hand, since it has a plasma frequency in the near-infrared region, the resulting plasma reflection is increased in the near-infrared region. Further, when it is desired to suppress reflection in the visible light region, a film having a low refractive index such as SiO ₂ or MgF ₂ is formed on the In ₄ Sn ₃ O ₁₂ fine particle dispersion film, thereby making it easy to observe A multilayer film having a reflectance of 1% or less can be obtained.
In addition, in order to provide further ultraviolet shielding function of the solar shading material, coating liquid and solar shading film according to the above means, fine particles such as inorganic titanium oxide, zinc oxide, cerium oxide, organic benzophenone, benzotriazole, etc. One or more of these may be added.
As described above, according to the above means, a stable In ₄ Sn ₃ O ₁₂ composite oxide as an inexpensive material with a reduced indium content has been established by establishing powder characteristics and a manufacturing method that exhibit functions for solar radiation shielding. It is possible to produce a coating solution for forming a solar shading film using a coating film, and to produce a coating film exhibiting a solar shading effect by using the coating solution. Since In ₄ Sn ₃ O ₁₂ composite oxide fine particles are inorganic materials, they have extremely high weather resistance as compared with organic materials. For example, even if they are used in areas exposed to sunlight (ultraviolet rays), the deterioration of color and various functions will not occur. Almost does not occur.
In addition, the coating liquid according to the above means does not form the desired solar radiation shielding film by utilizing the decomposition or chemical reaction of the coating components by the heat at the time of baking. Can be formed.

  Hereinafter, the present invention will be described more specifically with reference to examples. In the following, the crystal structure of the solar shading material powder was measured by powder X-ray diffraction (CuKα, Rotaflex RAD-γVB manufactured by Rigaku Corporation). Moreover, the visible light transmittance and solar transmittance of the film obtained using the coating solution for forming the solar shading film were measured using a spectrophotometer U-4000 manufactured by Hitachi, Ltd., and JIS R 3106 Based on the calculation. For film evaluation, the visible light transmittance and solar transmittance of the film obtained by film formation with a bar coater were measured.

While stirring a mixed aqueous solution of 500 g of 10% In (NO ₃ ) ₃ · 3H ₂ O aqueous solution and 370.6 g of 10% SnCl ₄ · 5H ₂ O aqueous solution (equivalent to Sn 39.1% by weight) at 20 ° C., 15 450 g of a% NH ₄ HCO ₃ aqueous solution was added dropwise over 17 minutes, and after the addition, the mixture was further stirred for 10 minutes to age the precipitate.
The obtained precipitate was repeatedly washed with 2,000 ml of ion-exchanged water at a time by decantation, and the washing was terminated when the supernatant liquid had a conductivity of 1 mS / cm or less. Thereafter, the precipitate was dried at 105 ° C. The residual Cl content in the dried product was 0.07%. Next, the pulverized dried product is placed in a furnace, and the atmosphere is evacuated to 0.02 Pa, then replaced with nitrogen gas to 1 atm, and baked at 1500 ° C. for 3 hours while supplying nitrogen. Oxide fine particles A were obtained.
This composite oxide fine particle A powder was identified as In ₄ Sn ₃ O ₁₂ by X-ray diffraction.
The powder color of the fine particles A was L ^* of 45.0075, a ^* of 1.9325, and b ^* of −5.6953.
Next, 30% by weight of the composite oxide fine particles A, 56% by weight of isobutyl alcohol, and 14% by weight of a dispersant are mixed and filled into a container together with 0.15 mmφ glass beads, and then subjected to a bead mill dispersion treatment for 1 hour. _{A 4} Sn ₃ O ₁₂ composite oxide fine particle dispersion was prepared. A soda lime glass substrate having a size of 100 mm × 100 mm × 3 mm was applied to a coating solution containing 67.5 wt% of the dispersion, 27.5 wt% of an acrylic resin solution dissolved in methyl isobutyl ketone as a binder, and 5 wt% of a curing agent. After being applied to the film, it was baked at 180 ° C. for 1 hour to obtain a solar radiation shielding film a. The solar radiation transmittance was 58.0% when the visible light transmittance of the solar light shielding film a was 70%.
[Examples 2 to 4 and Comparative Examples 1 to 4]
Example 2 A composite oxide fine particle B was produced in the same manner as in Example 1 except that the firing conditions were changed to 1450 ° C. for 3 hours, and a solar radiation shielding film b was formed in the same manner as in Example 1. .
(Example 3) A composite oxide fine particle C was produced in the same manner as in Example 1 except that the atmosphere of the firing conditions was N ₂ and under a pressure of 0.12 MPa. Further, in the same manner as in Example 1, the solar radiation shielding film was produced. c was formed.
(Example 4) The dried product of Example 1 was placed in a furnace and baked at 1200 ° C in the air for 1 hour, and then the atmosphere in the furnace was evacuated to 0.02 Pa and further replaced with nitrogen gas to 1 atm. Thereafter, composite oxide fine particles D were produced in the same manner as in Example 1 except that the calcination was performed at 1500 ° C. for 3 hours, and a solar radiation shielding film d was formed in the same manner as in Example 1.
Comparative Example 1 Composite oxide fine particles E were produced in the same manner as in Example 1 except that the firing condition was 1100 ° C. for 1 hour. However, when the X-ray diffraction pattern of the fine particles E was analyzed, only the In ₂ O ₃ phase and the SnO ₂ phase were found, so the solar shading film e was not formed.
(Comparative Example 2) Fine composite oxide particles as in Example 1 except that the firing conditions were 1 hour at 1400 ° C in the air and then 30 minutes at 380 ° C in a 9% H ₂ / N ₂ atmosphere. F was manufactured, and further a solar shading film f was formed in the same manner as in Example 1.
(Comparative Example 3) Composite oxide fine particles in the same manner as in Example 1 except that the firing conditions were fired at 1400 ° C in the air for 1 hour and then 30 minutes at 430 ° C in a 9% H ₂ / N ₂ atmosphere. G was produced, and a solar shading film g was formed in the same manner as in Example 1.
Comparative Example 4 A mixed powder obtained by physically mixing In ₂ O ₃ powder and SnO ₂ powder at a molar ratio of 2: 3 was manufactured, and the mixed powder was placed in a furnace. Then, the atmosphere in the furnace was evacuated to 0.02 Pa, replaced with nitrogen gas to 1 atm, and fired at 1500 ° C. for 3 hours while supplying nitrogen to produce composite oxide fine particles H. Further Examples The solar shading film h was formed in the same manner as in 1.
FIG. 1 is a table showing the properties of the composite oxide fine particles and the film characteristics of the solar radiation shielding film in the above-described Examples and Comparative Examples. The composite oxide fine particles B (Example 2) to D (Example 4) of the example shown in FIG. 1 were identified as In ₄ Sn ₃ O ₁₂ by X-ray diffraction, and the powder color of L ^* was 30 to 70, a ^* was −9.0 to −0.1, b ^* was within the range of −15.0 to 4.0, and the average particle size was 400 nm or less. Further, the solar radiation transmittance when the visible light transmittance was 70% was 59% or less.
On the other hand, the average particle diameters of the fine particles E (Comparative Example 1) to H (Comparative Example 4) were all 400 nm or less, but the X-rays of the fine particles E according to Comparative Example 1 and the fine particles H according to Comparative Example 4 were used. When the diffraction pattern was analyzed, Comparative Example 1 was only an In ₂ O ₃ phase and an SnO ₂ phase, and Comparative Example 4 was a mixed phase of In ₂ O ₃ phase, SnO ₂ phase, and In ₄ Sn ₃ O ₁₂ phase. . In addition, the powder color of the fine particles F of Comparative Example 2 is outside the scope of the present invention for L ^* and b ^* , and the powder color of the fine particles G of Comparative Example 3 is visible outside the scope of the present invention, b ^*. The solar radiation transmittance was 60% or more when the light transmittance was 70%.

Example 5 to Example 9

(Example 5) The composite oxide fine particles were prepared in the same manner as in Example 1 except that in the preparation of the mixed solution for producing the precipitate in Example 1, an ethanol solution of 4.19% SbCl _{3 was} further mixed with 79.3 g. I was produced, and a solar shading film i was formed in the same manner as in Example 1.
(Example 6) A composite oxide fine particle J was produced in the same manner as in Example 1, except that 1.02 g of SnF ₄ was further mixed in the preparation of the mixed solution for producing the precipitate in Example 1, and A solar shading film j was formed in the same manner as in Example 1.
(Example 7) Same as Example 1 except that 6.8 g of ethanol solution of 25% [(CH ₃ ) ₂ CHO] ₄ Ge was further mixed in the preparation of the mixed solution for producing the precipitate in Example 1. Then, composite oxide fine particles K were produced, and a solar radiation shielding film k was formed in the same manner as in Example 1.
(Example 8) A composite oxide fine particle L was produced in the same manner as in Example 1 except that in the preparation of the mixed solution for producing precipitates in Example 1, 2.6 g of 60% HReO ₄ solution was further mixed. Further, a solar radiation shielding film 1 was formed in the same manner as in Example 1.
(Example 9) In the mixed solution preparation for producing a precipitate in Example 1, the composite oxide fine particles M were prepared in the same manner as in Example 1 except that 7.9 g of an ethanol solution of 10% TaCl _{5 was} further mixed. Then, a solar shading film m was formed in the same manner as in Example 1.
FIG. 1 is a table showing the properties of the composite oxide fine particles, the film characteristics of the solar shading film, and the like in the above-described embodiment. The composite oxide fine particles I (Example 5) to M (Example 9) of the example shown in FIG. 1 were identified as In ₄ Sn ₃ O ₁₂ by X-ray diffraction, and the powder color of L ^* was 30 to 70, a ^* was −9.0 to −0.1, b ^* was within the range of −15.0 to 4.0, and the average particle size was 400 nm or less. Further, the solar radiation transmittance when the visible light transmittance was 70% was 59% or less.

0.09% by weight of lanthanum hexaboride fine particles having an average primary particle size of 67 nm, 16.92% by weight of In ₄ Sn ₃ O ₁₂ composite oxide fine particles A of Example 1, 22.7% by weight of a room temperature curable binder, toluene A green glass substrate having a thickness of 100 mm × 100 mm × about 2 mm in thickness of a dispersion comprising 1.3 wt%, isobutyl alcohol 9.8 wt%, methyl isobutyl ketone 34.9 wt%, and dispersant 14.3 wt% After being applied to the film, it was baked at 180 ° C. for 1 hour to obtain a solar shading film n. In the solar radiation shielding film n, the solar radiation transmittance was 50.7% when the visible light transmittance was 78%. This is shown in FIG.

The solar radiation shielding film a surface on the solar radiation shielding glass obtained in Example 1 was sandwiched between the other clear glass substrates with 0.76 mm thick polyvinyl butyral for interlayer film, and heated to 80 ° C. Then, after temporarily mounting, main bonding by an autoclave was performed at 140 ° C. under the condition of 14 kg / cm ² to prepare a laminated glass o. In the laminated glass o, the solar radiation transmittance was 44.3% when the visible light transmittance was 72%. This is shown in FIG.

In ₄ Sn ₃ O ₁₂ composite oxide fine particle dispersion produced in Example 1 is added to polyvinyl butyral, triethylene glycol-di-2-ethylbutyrate is added as a plasticizer, and In ₄ Sn ₃ O ₁₂ is added. An intermediate film composition having a composite oxide fine particle A concentration of 0.20% by weight, a lanthanum hexaboride fine particle concentration of 0.0041% by weight, and a polyvinyl butyral concentration of 71.1% by weight used in Example 5. Prepared. The intermediate film composition was kneaded with a roll and formed into a 0.76 mm thick sheet to prepare an intermediate film. This intermediate film is sandwiched between two 100 mm × 100 mm × about 2 mm thick green glass substrates, heated to 80 ° C. and temporarily bonded, then subjected to main bonding by an autoclave at 140 ° C. and 14 kg / cm ² , and laminated glass p was produced. In the laminated glass p, the solar radiation transmittance was 44.7% when the visible light transmittance was 74%. This is shown in FIG.

Claims (14)

The average primary particle diameter of the fine particles is 400 nm or less, and the powder color in the L ^* a ^* b ^* color system is L ^* is 30 to 70, a ^* is −9.0 to −0.1, b In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding, characterized in that -15.0 to 4.0. It contains at least one element selected from Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, Re, Ru, P, and Ge. In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding according to item 1. A step of reacting a raw material mixed solution containing a tin compound and an indium compound with an alkali solution and aging with continuous stirring to obtain a precipitate;
Washing the precipitate by decantation and drying to obtain a hydroxide or hydrate powder comprising indium and tin;
A step of calcining the hydroxide or hydrate powder at 1200 ° C. or higher in an inert gas or a mixed gas atmosphere of an inert gas and a reducing gas to obtain In ₄ Sn ₃ O ₁₂ composite oxide fine particles. When,
Method of manufacturing a solar radiation shielding _In 4 _Sn 3 _{O 12} composite oxide fine particles, characterized by comprising. A tin compound, an indium compound, and at least one element selected from Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, Re, Ru, P, and Ge A first step of reacting a raw material mixed solution containing a compound with an alkaline solution and aging with continuous stirring to obtain a precipitate;
The precipitate obtained in the first step is washed by decantation and then dried, and then indium, tin, Sb, V, Nb, Ta, W, Zr, F, Zn, Al, Ti, Pb A second step of obtaining a hydroxide or hydrate powder comprising, at least one element selected from Ga, Re, Ru, P and Ge;
The hydroxide or hydrate powder obtained in the second step is baked at 1200 ° C. or higher in an inert gas or a mixed gas atmosphere of an inert gas and a reducing gas to obtain Sb, V, Nb. In ₄ Sn ₃ O ₁₂ composite oxide microparticles containing at least one element selected from Ta, W, Zr, F, Zn, Al, Ti, Pb, Ga, Re, Ru, P and Ge 3 steps,
Method of manufacturing a solar radiation shielding _In 4 _Sn 3 _{O 12} composite oxide fine particles, characterized by comprising. Wherein _{an In} 4 _Sn 3 _{O 12} composite oxide microparticles solutions claim 3, characterized in that it comprises a step of grinding or the fourth term sunlight shielding _{an In} 4 _Sn 3 _{O 12} composite oxide according by a mechanical method Method for manufacturing fine particles. The pH of the solution after reacting the raw material mixed solution and the alkali solution is 4.0 to 9.0, according to any one of claims 3 to 5, A method for producing In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding. The solar radiation shielding In _{4 according} to any one of claims 3 to 6, wherein the precipitate is decanted until the conductivity of the cleaning liquid becomes 1 mS / cm or less. A method for producing Sn ₃ O ₁₂ composite oxide fine particles. The solar radiation shielding In ₄ Sn ₃ O ₁₂ composite oxide according to claim 1 or 2, wherein the solar radiation shielding material is a solar radiation shielding film forming coating solution in which a solar radiation shielding material is dispersed in a solvent. A coating solution for forming a solar shading film, characterized by containing fine particles. 9. The coating solution for forming a solar shading film according to claim 8, wherein at least one kind of fine particles selected from boride fine particles, antimony tin oxide fine particles, and tungsten oxide fine particles is added. The coating solution for forming a solar shading film according to claim 8 or 9, wherein an inorganic binder or a resin binder is contained. A solar shading film formed by using the solar shading film forming coating solution according to any one of claims 8 to 10. A solar radiation shielding base material, wherein the solar radiation shielding film according to claim 11 is formed on glass or plastic. The In ₄ Sn ₃ O ₁₂ composite oxide fine particles for solar radiation shielding according to claim 1 or 2, or for the formation of a solar radiation shielding film according to any one of claims 8 to 10. A solar radiation shielding base material, wherein the coating liquid is kneaded into a base material forming base material and formed into a plate shape, a sheet shape, or a film shape. The solar radiation shielding substrate according to claim 12 is laminated with the solar radiation shielding substrate so as to sandwich the solar radiation shielding film of the solar radiation shielding substrate according to claim 12, or the solar radiation shielding substrate according to claim 13. A solar radiation shielding base material characterized in that the base material is sandwiched and laminated by another base material.

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