JP4941637B2 - Method for producing boride particles and boride particles - Google Patents

Description

The present invention relates to a method for producing boride particles and boride particles .

  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 to form a heat ray reflective glass. As the material, metal oxides such as FeOx, CoOx, CrOx, and TiOx and metal materials such as Ag, Au, Cu, Ni, and Al have been selected.

  However, since these materials have the property of reflecting or absorbing visible light at the same time, in addition to infrared rays that greatly contribute to the thermal effect, there is a problem that the visible light transmittance is lowered. In particular, base materials used for building materials, vehicles, telephone boxes, etc. require high transmittance in the visible light region. I had to make it thinner. For this reason, a method of forming a film as a 10 nm level thin film by using a physical film forming method such as spray baking, CVD method, sputtering method or vacuum vapor deposition method is employed.

However, these film forming methods require a large-scale apparatus and vacuum equipment, and there are drawbacks in productivity and large area, and there is a drawback that the manufacturing cost of the film becomes high. In addition, when trying to increase the solar shading characteristics with these materials, the reflectance in the visible light region also tends to increase at the same time, and there is also a disadvantage that it gives a glaring appearance like a mirror and impairs the beauty. It was. Furthermore, the film formed with these materials has a relatively low electrical resistance value, and the reflection with respect to the radio wave becomes high, for example, the radio wave of a mobile phone, a TV, a radio, etc. is reflected and cannot be received, There were also drawbacks such as causing radio interference in the surrounding area.
In order to improve such a defect, as the physical properties of the film, the light reflectance in the visible light region is low, the reflectance in the infrared region is high, and the surface resistance value of the film is approximately 10 ⁶ Ω / □ or more. The film must be controllable.

  Note that antimony tin oxide (hereinafter abbreviated as ATO) and indium tin oxide (hereinafter abbreviated as ITO) are known as materials having high visible light transmittance and excellent solar radiation shielding function. And since these materials have a relatively low visible light reflectance, they do not give a glaring appearance. However, since the plasma frequency is in the near infrared region, the reflection / absorption effect is still not sufficient in the near infrared region closer to visible light. Furthermore, since these materials have a low solar shielding power per unit weight, there is a problem that the amount of use increases and the cost becomes high in order to obtain a high shielding function.

Therefore, the present applicant has previously developed a dispersion for solar radiation shields using hexaboride particles as a solar radiation shielding component, and a solar radiation shield using the same. Hexaboride particles are powders that are colored grey-black, brown-black, green-black, etc. depending on the production conditions, but the particle size of the powder is sufficiently small compared to the visible light wavelength, and in the interlayer film or solar radiation shield When uniformly dispersed therein, visible light permeability can be ensured while keeping the infrared light shielding ability sufficiently strong.
The reason for this is not known in detail, but these hexaborides have a large amount of free electrons in the particles, and the absorption energy of indirect interband transitions due to free electrons inside and on the surface of the particles is just visible to near red. Since it is in the vicinity of the outer region, it is considered that heat rays in this wavelength region are selectively reflected and absorbed.

According to experiments, a film in which the hexaboride particles have a specific surface area of 10 m ² / g or more and is uniformly dispersed in a solvent has a maximum value between 400 nm and 700 nm in transmittance, and a wavelength between 700 nm and 700 nm. It was observed that there was a minimum value between 1800 nm and the difference between the maximum value and the minimum value of these transmittances was 15 points or more. This indicates that visible light is effectively transmitted through the film, considering that the visible light wavelength is 380 nm to 780 nm and the visibility is a bell-shaped peak having a peak near 550 nm.

  In addition, the solar shading ability per unit weight of the hexaboride particles is very high. For example, the effect is exhibited at a use amount of 1/10 or less as compared with ITO fine particles and ATO fine particles. It has also been found that by using hexaboride fine particles together with ITO fine particles and / or ATO fine particles, only the solar radiation shielding property can be further improved while maintaining a certain visible light transmittance. As a result, it is possible to reduce the total amount of solar shielding particles used and to reduce production costs.

  Furthermore, since hexaboride particles also absorb in the visible light region, by controlling the amount added to the solar shield, the absorption in the visible light region of the solar shield can be freely controlled, and the brightness It is also possible to provide additional functions such as thickness adjustment and privacy protection.

Here, for example, Non-Patent Document 1 and Non-Patent Document 2 have been proposed as methods for producing boride particles. These documents, by _{B 4} C reduction method of _La 2 _{O 3,} have been described for industrial production method of LaB ₆ is a kind of boride particles. Although the methods described in these documents are methods that can produce LaB ₆ at low cost, since the firing temperature is as high as 1600 ° C., the resulting LaB ₆ has coarse particles. However, for example, boride fine particles for use in the field of solar radiation shielding are required to have a sufficiently small particle diameter as compared with the visible light wavelength, but the above-mentioned coarse boride particles used a jet mill or the like. Even if powerful pulverization is performed by a mechanical method, it is very difficult to make fine particles.

Therefore, the present applicant has excellent by avoiding the coarsening of boride particles by controlling the firing temperature at the time of producing boride particles by firing finer particles of the raw material first. A method for producing boride particles having a particle diameter exhibiting a solar radiation shielding function was found and provided as Patent Document 2.
However, when the obtained slurry of boride particles and various solvents is mixed together with beads into a medium stirring mill to produce a dispersion for forming a solar shading body, a dispersion time required to obtain a desired dispersed particle size As for the haze value of the solar radiation shield produced using the dispersion liquid, there is still room for improvement in any method.

JP 2000-169765 A JP 2004-277274 A Doi, Powder and Industry, 21 (5) 1989. Functional materials, 15 (6) 1995.

The present invention has been made paying attention to such problems, and the problem is that the dispersion time for dispersing boride particles in various solvents can be shortened and the haze value can be reduced. The object is to provide a method for producing boride particles, and boride particles .

  As a result of continual research to solve the above problems, the present inventor preliminarily pulverized boride particles produced by controlling the raw material particle size and the firing temperature with a jet mill to obtain the obtained boride particles. The present inventors have found that the processing time when the dispersion processing is performed by putting the particles in a medium stirring mill together with the beads can be greatly shortened, and the haze value of the solar radiation shielding body composed of the fine particles can be reduced, thereby reaching the present invention.

A first configuration for solving the problem is a general formula XB _m (where X is an alkaline earth element or one or more metal elements selected from rare earth elements including yttrium (Y), 4 ≦ m ≦ 6.3) a method for producing boride particles represented by:
A step of reacting a solution of a compound containing X with an alkaline solution while stirring to obtain a precipitate;
Drying the precipitate to obtain X hydroxide particles and / or hydrate particles having an average particle size of 0.1 μm or less ;
Heat treating the X hydroxide particles and / or hydrate particles to obtain an aggregate of the X oxide particles having an average particle size of 20 μm or less ;
And agglomerates of particles of an oxide of the X, the average particle size was mixed with the following B _{4 C} particles 60μm or 22 .mu.m, obtained particles of oxide of X, a mixture of B 4 _C particles Process,
Heat-treating the mixture at a temperature of less than 1600 ° C. in a vacuum or an inert gas atmosphere to obtain boride particles represented by the general formula XB _m and having an average particle diameter D ₅₀ of 20 μm or more and 25 μm or less ;
Boride particles comprising the step of colliding the boride particles with each other in a jet stream and crushing to obtain fine particles of boride having a particle size of 0.2 μm or more and 1.5 μm or less. It is a manufacturing method.

The second configuration is represented by the general formula XB _m (where X is an alkaline earth element or one or more metal elements selected from rare earth elements including yttrium (Y), 4 ≦ m ≦ 6.3). A method for producing boride particles represented by:
A step of reacting a solution of a compound containing X with an alkaline solution while stirring to obtain a precipitate;
Drying the precipitate to obtain X hydroxide particles and / or hydrate particles having an average particle size of 0.1 μm or less ;
Mixing the hydroxide and / or hydrate particles of X with B ₄ C particles having an average particle size of 22 μm or more and 60 μm or less, and the hydroxide and / or hydrate particles of X; Obtaining a mixture with particles of B ₄ C;
Heat-treating the mixture at less than 1600 ° C. in a vacuum or an inert gas atmosphere to obtain boride particles represented by the general formula XB _m and having an average particle diameter D ₅₀ of 20 μm or more and 25 μm or less ;
Boride particles comprising the step of colliding the boride particles with each other in a jet stream and crushing to obtain fine particles of boride having a particle size of 0.2 μm or more and 1.5 μm or less. It is a manufacturing method.

The third configuration is a method for producing boride particles according to the first or second configuration,
When mixing the X hydroxide particles and / or hydrate particles, or the X oxide particles and the B ₄ C particles, in the mixing ratio of both, X element: boron atom The boride particles are produced by mixing so that the number ratio is 1: 4 to 1: 6.3.

The fourth configuration is a method for producing boride particles according to the first or second configuration,
When mixing the X hydroxide particles and / or hydrate particles, or the X oxide particles and the B ₄ C particles, in the mixing ratio of both, X element: boron atom The boride particles are produced by mixing so that the number ratio is 1: 5.9 to 1: 6.1.

The fifth configuration is a method for producing boride particles according to any one of the first to fourth configurations,
X hydroxide particles and / or hydrate particles having an average particle size of 0.1 μm or less, or X oxide particles having an average particle size of 20 μm or less,
A boride particle production method comprising mixing B ₄ C particles having an average particle diameter of 60 μm or less.

  A sixth configuration is boride particles manufactured by the boride particle manufacturing method according to any one of the first to fifth configurations.

According to the present invention, since obtained by heat treatment at below 1600 ° C., and pulverized by a boride particles represented by the general formula XB _m collide with each other in a jet stream to obtain a boride particles, For example, boride particles having an optimum particle diameter and a small amount of impurities can be produced at a low production cost as a solar radiation shield.

  Then, the slurry obtained by mixing the boride (fine) particles and the solvent thus obtained is put together with the beads into a medium stirring mill, and further pulverized and dispersed to prepare a dispersion for forming a solar shield. The dispersion time of boride particles having individual particle sizes can be greatly shortened, and the production efficiency can be improved. And since the coarsening of boride particle | grains can be reduced, the solar radiation shielding body with a low haze value can be obtained, and it is industrially useful.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
Figure 1 is a flow diagram showing the process of manufacturing the boride particles represented by the general formula XB _m according to the present invention.

  In the compound solution of X represented by the symbol (1), X is one or more metal elements selected from alkaline earth elements or rare earth elements including yttrium (Y). Among them, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sr, Ba, or Ca can be favorably used. As the X compound, for example, nitrates, sulfates, chlorides, etc. of the X element can be used.

  The alkaline solution represented by the symbol (2) is not particularly limited, and for example, various aqueous solutions of ammonium hydrogen carbonate, ammonium hydroxide, sodium hydroxide, potassium hydroxide, and the like can be used favorably. The concentration of the alkaline solution (2) is not less than the chemical equivalent necessary for the salt of the X compound to become a hydroxide, preferably from the equivalent to 1.5 times the excess. Within this range, the compound solution (1) of X and the alkaline solution (2) are sufficiently reacted, and the time required for washing in the subsequent step is preferably short.

  The compound solution (1) of X described above and the alkaline solution (2) are mixed, and the mixture is continuously stirred (11) to neutralize both to form a precipitate (12). Although the upper limit of the solution temperature at this time is not specifically limited, Usually, it shall be 100 degrees C or less. On the other hand, the lower limit of the solution temperature is not particularly limited, but if it is set too low, a new cooling device or the like is required, which causes an increase in production cost. The time for the neutralization reaction is not particularly limited, but is less than 30 minutes, preferably 25 minutes or less from the viewpoint of productivity. After the neutralization reaction is completed, in order to homogenize the system, precipitation is matured while continuing stirring, and the temperature at that time is the same as the neutralization temperature. The duration of stirring is not particularly limited, but may be 30 minutes or less, preferably about 15 minutes or less from the viewpoint of productivity.

The precipitate produced by the precipitation (12) is thoroughly washed (13) to remove the remaining alkali content and the like. As the cleaning method, decantation with pure water can be used.
Drying (14) the washed (13) complete precipitate gives particles of X hydroxide and / or hydrate (3). In drying (14), the temperature and time are not particularly limited.

The obtained particles of hydroxide and / or hydrate (3) may be used as it is, but the particles of hydroxide and / or hydrate (3) of X may be used. Further, heat treatment (15) may be performed to obtain an oxide of X (5), and the process may proceed to a later step. When the particles of X hydroxide and / or hydrate (3) are subjected to heat treatment (15), the heat treatment temperature is set from the viewpoint of avoiding coarsening of the generated oxide of X (5) particles. Although it will be 400 degreeC-1000 degreeC and heat processing time will not be specifically limited if it is 30 minutes or more, From a viewpoint of productivity, it is preferable to set it as 30 minutes-4 hours. By the heat treatment (15), the hydroxide and / or hydrate (3) of X becomes an aggregate in which particles of the oxide (5) of X are aggregated.
By adopting the production process described above, the particle size of the obtained hydroxide and / or hydrate (3) of X and the particle size of the oxide (5) particles can be obtained by, for example, an excellent solar radiation shielding function. In the range required for producing boride fine particles exhibiting the above.

Next, the obtained X hydroxide and / or hydrate (3) particles, or the X oxide (5) particles and the B ₄ C (4) particles are mixed (16). To do.
At the time of this mixing (16), it mixes uniformly so that the atomic ratio of X element and B element may be set to 1: 4-6.3. At this time, the average particle diameter of the B ₄ C (4) particles is preferably 60 μm or less, preferably 40 μm or less, and more preferably 30 μm or less, from the viewpoint of generation of fine particles such as XB ₄ and XB _6. . Further, the average particle diameter of the hydroxide particles and / or hydrate particles of X is preferably 0.1 μm or less, and the average particle diameter of the oxide of X is preferably 20 μm or less. Thus, by specifying the particle size of each raw material powder, boride particles (6) having a dispersed particle size in a solvent of 800 nm or less can be easily produced at low cost.

Next, the obtained uniform mixture is heat-treated at less than 1600 ° C. in a vacuum or an inert gas atmosphere (17) to obtain a general formula XB _m (provided that 4 ≦ m ≦ 6.3, the same applies hereinafter). The boride particle | grains (6) represented by these are obtained.

Here, the boride particles (6) will be further described.
The boride particles (6) are represented by the general formula XB _m , and boride compounds represented by XB ₄ , XB ₆ , XB _{12 and the} like can be mentioned, but the material for the solar radiation shield is 4 ≦ m ≦ 6. 3 is preferred. That is, the boride particles are preferably mainly composed of XB ₄ and XB ₆ among the borides, and may partially contain XB ₁₂ . Here, m is a chemical analysis of the obtained powder containing boride particles (6), and indicates the atomic ratio of B to one atom of X element.

The produced powder containing boride particles (6) is actually a mixture of XB ₄ , XB ₆ , XB _{12 and the} like. For example, in the case of hexaboride which is a typical boride particle, even if it is a single phase in X-ray diffraction, it is actually 5.8 <m ≦ 6.3, and contains a small amount of other phases. It is thought that there is. Here, when m ≧ 4, the generation of XB, XB _{2 and the} like is suppressed, and the detailed reason is unknown, but the solar shading characteristics are improved. On the other hand, when m ≦ 6.3, the generation of boron oxide particles in addition to the boride particles (6) is suppressed. Since boron oxide particles are hygroscopic, if boron oxide particles are mixed in the boride powder, the moisture resistance of the boride powder is lowered, and the deterioration of solar radiation shielding characteristics with time is increased. Therefore, it is preferable to suppress the generation of boron oxide particles by setting m ≦ 6.3.
From the above, the particles of X hydroxide and / or hydrate (3), or the mixture of X oxide (5) particles and B ₄ C (4) particles (16) At this time, it is preferable to form a uniform mixture so that the atomic ratio of the X element and the B element is 1: 4 to 1: 6.3.

When heat-treating (17) the particles of X hydroxide and / or hydrate (3) or the homogeneous mixture of particles of X oxide (5) and B ₄ C (4) The atmosphere is preferably a vacuum or an inert gas atmosphere. If the atmosphere is a vacuum, a higher degree of vacuum is preferable from the viewpoint of the stability of boride particles. If the atmosphere is an inert gas, it is preferable to use a gas other than nitrogen from the viewpoint of avoiding the formation of boron nitride.
The heat treatment temperature is preferably less than 1600 ° C. This is because if the temperature is less than 1600 ° C., the coarsening of the boride particles (6) can be avoided. Moreover, what is necessary is just to select baking time suitably so that a desired average particle diameter etc. may be obtained in the boride particle | grains (6).

In this manner, boride particles (6) represented by the general formula XB _m (where 4 ≦ m ≦ 6.3), for example, suitable for solar shading are obtained. The boride particles (6) are preferably not oxidized on the surface, but those usually obtained are slightly oxidized, and surface oxidation occurs in the particle dispersion process to some extent. Inevitable. In addition, the boride particles (6) exhibit a greater solar shielding effect as the crystal perfection is higher, but even if the crystallinity is low and X-ray diffraction produces a very broad diffraction peak, If the basic bond inside the particle is composed of a bond between an X element such as lanthanum and boron, a desired solar shading effect is exhibited.

Further, the average particle diameter D ₅₀ (median value of the particle size cumulative distribution curve) of the obtained boride particles (6) is the alkaline earth element used or the rare earth element containing yttrium (Y), and the raw material of B ₄ C Although it depends on the particle diameter, it is about 20 to 25 μm. Therefore, it is necessary to further pulverize with a medium stirring mill to make a dispersion.
When boride particles (6) are directly pulverized with a medium agitating mill without using a jet mill, a dispersion liquid is produced, and the pulverization time becomes long. In particular, the visible light transmission performance with a dispersed particle diameter of 100 nm or less is high. In order to obtain a dispersion for the shielding body, it has been a problem that the pulverization time becomes long. In addition, when the obtained boride particles (6) include particles whose crystals grow and become coarse, clogging of the filter of the medium agitating mill may occur, and stable dispersion is achieved. In order to produce the liquid, it was necessary to solve this problem.

Accordingly, next, the resulting formula XB boride particles represented by _m, for example, using a jet mill, colliding a particle together with each other in a jet stream. In this case, jet mill grinding conditions are not particularly limited.
In this way, after preliminary jet milling (7), the dispersion particle diameter of boride particles can be 800 nm or less by further grinding with a medium stirring mill (9). In this way, even when the boride particles are further pulverized by a medium stirring mill to produce a dispersion, the pulverization time is relatively short. In particular, the pulverization time for obtaining a dispersion for a shield having a dispersed particle size of 100 nm or less and a haze value of less than 1.0% and high visible light transmission performance does not become longer than about 20 hours. . In addition, coarse boride particles are not included, and the risk of clogging of the filter during pulverization of the medium stirring mill is eliminated.

  In addition, the particle size distribution of the boride fine particles obtained by jet milling becomes sharp, and the lower limit of the particle size obtained by the particle size distribution measurement is 0.2 μm or more, and the upper limit is 1.5 μm or less. It is done. Thereby, in the solar radiation shielding body produced by further applying the dispersion liquid after being pulverized by the medium stirring mill, the solar radiation shielding ratio is improved and the haze value can be reduced to less than 1.0%.

  Next, the slurry obtained by mixing (18) the boride particles (6) obtained by jet milling in the solvent (8) is put into a medium stirring mill together with beads, and further pulverized and dispersed (19). A dispersion (10) for forming a sunscreen is prepared.

The medium agitation mill is a method in which spherical beads and a slurry of powder to be crushed are put into a pulverization vessel and forcedly stirred, and the particles in the slurry are pulverized mainly using the shear stress of the beads. It is a method of dispersion.
The stirring mechanism of the medium stirring mill is not particularly limited as long as the shear stress of the beads is efficiently transmitted to the slurry.

  The bead diameter is generally selected according to the final particle diameter of the target slurry, but is preferably 1 mm or less in diameter. If it is 1 mm or less, the efficiency which grinds particles finely will become high. Further, the smaller the bead diameter, the faster the grinding speed and the smaller the particle size of the boride to be ground. In particular, beads having a diameter of 0.3 mm or less are preferred when pulverized and dispersed to fine boride particles of 800 nm or less, and further 100 nm or less.

The bead material is made of a material of the same quality as that of the slurry, compared to beads with a light specific gravity, such as glass beads, in order to prevent impurities from entering the slurry containing the material to be crushed having a high hardness such as boride. It is preferred to use beads. In addition, ceramic beads are preferable among beads that are generally available on the market. Specific examples include ZrO ₂ beads and YSZ beads. Since these beads have characteristics such as high specific gravity, high grinding efficiency, low wear, and worn components are transparent, they are preferable when the ground product is used for optical applications.

  In the process of pulverizing and dispersing, it is preferable to use various dispersants in order to prevent dispersion inhibition due to reaggregation or the like. As the dispersant, a compound having an alkoxide group in the molecular structure, a compound having an amino group, various surfactants, and the like are used. These adsorb on the surface of the boride which has been pulverized and dispersed, and prevent reaggregation by utilizing structural disturbance or electrostatic repulsion.

  The medium stirring mill is not particularly limited as long as it is a method of uniformly dispersing boride particles in the dispersion, and examples thereof include a bead mill, a ball mill, a sand mill, a paint shaker, and an ultrasonic homogenizer. Depending on the dispersion treatment conditions using these equipment, boride particles can be dispersed in a solvent and at the same time micronization by collision of boride particles can proceed, and boride particles can be further micronized and dispersed ( That is, it is pulverized and dispersed).

The solvent (8) is not particularly limited, and may be selected in accordance with the coating conditions, the coating environment, the inorganic binder and the resin binder that are appropriately added, etc., of the dispersion for solar radiation shielding body (10). . For example, as the solvent (8), water, alcohols such as ethanol, propanol, butanol, isopropyl alcohol, isobutyl alcohol, diacetone alcohol, ethers such as methyl ether, ethyl ether, propyl ether, esters, or acetone, Various organic solvents such as ketones such as methyl ethyl ketone, diethyl ketone, cyclohexanone, and isobutyl ketone can be used. If necessary, pH may be adjusted by adding an acid or an alkali.
Furthermore, in order to further improve the dispersion stability of the boride particles (6) in the dispersion for solar radiation shielding body (10), it is of course possible to add various surfactants and coupling agents.

  By the way, the obtained dispersion for solar radiation shielding body (10) is specified by measuring the dispersion state of the boride particles (6) when the boride particles (6) are dispersed in the solvent (8). The

  The dispersed particle size of the boride particles can be determined depending on the purpose of use, but when maintaining transparency and applying to optical applications, the particle size is preferably 800 nm or less. Particles exceeding 800 nm completely block light, resulting in a gray film or molded body (plate, sheet, etc.) with a monotonously reduced transmittance, and maintaining visibility in the visible light region. At the same time, it is difficult to maintain transparency efficiently. In particular, when importance is attached to the transparency in the visible light region, it is necessary to consider scattering by particles. When importance is attached to the transparency, the dispersed particle diameter is 200 nm or less, preferably 100 nm or less.

  Here, the dispersed particle size means the aggregated particle size of boride particles in a solvent, and can be measured with various commercially available particle size distribution analyzers. For example, an ELS-800 manufactured by Otsuka Electronics Co., Ltd., which is sampled from a dispersion in which boride fine particles are dispersed in a solvent in the presence of an aggregate of boride fine particles and the dynamic light scattering method is used as a measurement principle It is possible to measure the dispersed particle diameter. In addition, an apparatus for measuring the dispersed particle diameter by analyzing light scattering of a laser can be used.

If the dispersed particle diameter of the boride particles is larger than 800 nm, the light in the visible light region of 400 nm to 780 nm is scattered by geometrical scattering or Mie scattering, and it becomes like frosted glass, so that clear transparency cannot be secured. . In particular, when the dispersed particle diameter is 200 nm or less, the above-described scattering is further reduced and a Rayleigh scattering region is obtained. In the Rayleigh scattering region, the scattered light decreases in inverse proportion to the sixth power of the particle diameter. Therefore, as the dispersed particle diameter becomes smaller, scattering is reduced and transparency is improved. Furthermore, when the thickness is 100 nm or less, the scattered light is very small and the transparency is further increased.
As described above, by applying the dispersion for forming a solar shielding body in which the dispersed particle diameter of the boride particles is sufficiently fine to 800 nm or less and uniformly dispersed, an excellent solar shielding body can be obtained.

For a solar radiation shield in which the boride particles (6) have a dispersed particle diameter of 800 nm or less and are sufficiently fine and uniformly dispersed, the light transmittance has a maximum value at a wavelength of 400 to 700 nm and a minimum value at a wavelength of 700 to 1800 nm. A solar shading body is obtained.
As the ratio (P / B) between the maximum value and the minimum value of the film transmittance in the solar radiation shielding body is larger, the solar radiation shielding characteristics are more excellent. This is because the transmission profile of boride particles has a maximum value at a wavelength of 400 nm to 700 nm, a minimum value at a wavelength of 700 to 1800 nm, a visible light wavelength range of 380 nm to 780 nm, and a visual sensitivity peaking around 550 nm. It is clear considering that it is a bell-shaped. That is, it is understood from this transmission characteristic that visible light is effectively transmitted and other heat rays are effectively reflected and absorbed.

  Incidentally, the boride particles (6) of the present embodiment or the solar shading body formed from the solar shading body-forming dispersion liquid (10) in which the boride particles (6) are dispersed in the solvent (8), Further, in order to impart an ultraviolet shielding function, one or more kinds of particles such as inorganic titanium oxide, zinc oxide and cerium oxide, organic benzophenone and benzotriazole may be added.

  Moreover, in order to improve the light transmittance of the solar shading body, particles such as ATO, ITO, and aluminum-added zinc oxide may be further mixed. When these transparent particles are added to the dispersion (10) for forming a sunscreen, the transmittance in the vicinity of 750 nm increases and the near infrared rays are shielded, so that the visible light transmittance is high and the sunscreen properties. A higher solar shield is obtained.

Conversely, when the dispersion for solar radiation shielding body (10) of this embodiment is added to a dispersion in which particles such as ATO, ITO, and aluminum-added zinc oxide are dispersed, for example, the above LaB ₆ (boride) Since the film color of lanthanum) is green, the film can be colored, and at the same time, the solar radiation shielding effect can be assisted. In this case, the solar radiation shielding effect can be assisted with only a small addition amount with respect to ATO or ITO as a main component, the required amount of ATO or ITO can be greatly reduced, and the cost of the dispersion can be reduced.

Since the dispersion for solar radiation shielding body (10) of the present embodiment as described above does not form a target solar radiation shielding body by utilizing decomposition or chemical reaction of the liquid component due to heat at the time of firing, A solar shading body having stable characteristics can be formed.
Furthermore, since the boride particles (6) exhibiting such excellent solar radiation shielding effect are inorganic materials, they are superior in weather resistance as compared with organic materials, and are used, for example, in areas exposed to sunlight (ultraviolet rays). However, there is almost no deterioration of color and various functions.
As a result, windows, telephone boxes, show windows, lamps for lighting, transparent cases, etc. for vehicles, buildings, offices, general houses, etc., such as single glass, laminated glass, plastics, and other transparent substrates that require solar radiation shielding functions. It can be used in a wide range of fields such as materials.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
In addition, the dispersed particle diameter obtained in the following Examples and Comparative Examples was measured using ELS-800 manufactured by Otsuka Electronics Co., Ltd., and the visible light transmittance and the solar transmittance of the solar shield were measured by Hitachi Ltd. It measured using the spectrophotometer U-4000 made from a company. The haze value was measured using HR-200 manufactured by Murakami Color Research Laboratory Co., Ltd.
In film evaluation, two types of films were formed on a PET film having a thickness of 50 μm using a two-layer bar coater with different wire diameters (bar Nos. 10 and 24), and visible light was formed. The solar radiation transmittance and haze value at a transmittance of 70% were calculated from the two-point plot of the film.

Example 1
To 500 g of 10% La (NO ₃ ) ₃ 6H ₂ O aqueous solution, a 15% NH ₄ OH solution was added dropwise over 20 minutes while stirring at room temperature to form a precipitate. After the addition, stirring was continued for another 10 minutes. Aged.
Next, the precipitate produced by decantation was washed with pure water, and this was repeated until the conductivity of the supernatant liquid became 1 mS / cm or less. The washed precipitate was dried at 105 ° C. and calcined at 600 ° C. for 1 hour in the air to obtain La ₂ O ₃ .
The obtained La ₂ O ₃ and B ₄ C particles having an average particle diameter of about 22 μm were mixed so that the atomic ratio of La element to B element was 1: 6 to obtain a uniform mixture. The uniform mixture was fired at 1500 ° C. for 3 hours in a vacuum atmosphere (about 0.02 Pa) to obtain a powder mainly containing LaB ₆ particles. The average particle diameter _{D 50} of the LaB ₆ was 1.0μm, as shown in Table 1. Next, the LaB ₆ particles were pulverized using a jet mill under the conditions of a gas pressure of 0.6 MPa / cm ² and a used air amount of 0.8 m ³ / min.
A mixture of 2% by weight of the obtained LaB ₆ fine particles, 4% by weight of a polymeric dispersant and 94% by weight of toluene and ZrO ₂ beads having a diameter of 0.3 mm are filled in a paint shaker (medium stirring mill) and pulverized. And a dispersion treatment was performed to prepare LaB ₆ dispersion A.

Table 1 and FIG. 2 show changes in the dispersed particle size with respect to the paint shaker processing time. In the dispersion A after being prepared by the pulverization and the dispersion treatment for 18 hours, the dispersed particle diameter of LaB ₆ was 93.4 nm. To this LaB ₆ dispersion A, toluene and UV curable resin are further added, and LaB ₆ 0.63% by weight, UV curable resin 33.3% by weight, polymer dispersant 1.0% by weight, and the remaining toluene is sufficient. Mixing and stirring were performed to prepare a dispersion for forming a sunscreen.
Then, as described above, two kinds of films having different thicknesses are formed on a 50 μm-thick PET film, and the solar radiation transmittance and haze value when the visible light transmittance is 70% are calculated from the two-point plot of the film. And asked.
As a result, as shown in Table 1, the solar radiation transmittance was 48.5% and the haze value was 0.9%.

(Example 2, Example 3)
A paint shaker treatment was carried out in the same manner as in Example 1 except that Ce (NO ₃ ) ₃ 6H ₂ O was used instead of La (NO ₃ ) ₃ 6H ₂ O, and CeB ₆ dispersion B (Example 2) was used. In addition, a paint shaker treatment was performed in the same manner as in Example 1 except that Nd (NO ₃ ) ₃ 6H ₂ O was used to prepare NdB ₆ dispersion C (Example 3). The average particle diameter _{D 50} of CeB ₆ of Example 2 is 1.3 .mu.m, the mean particle diameter _{D 50} of NdB ₆ of Example 3 was 1.5 [mu] m.
Table 1 and FIG. 2 show changes in the dispersed particle size with respect to the paint shaker processing time. In Examples 2 and 3, both the dispersed particle diameter of CeB ₆ in dispersion B and the dispersed particle diameter of NdB ₆ in dispersion C after being prepared by the pulverization and the dispersion treatment for 18 hours are both It was 100 nm. Moreover, after preparing the dispersion for forming a solar shading body in the same manner as in Example 1, two types of films having different film thicknesses were formed, and the solar transmittance and haze value when the visible light transmittance was 70% were described above. Calculated from a two-point plot of the membrane.
As a result, as shown in Table 1, the solar radiation transmittance of Example 2 was 48.6%, the haze value was 0.9%, the solar radiation transmittance of Example 3 was 48.5%, and the haze value. Was 0.9%.

(Comparative Example 1)
In Example 1, except that the pulverization by the jet mill was not performed, the paint shaker process was performed and the circulation process by the bead mill was performed in the same manner as in Example 1 to prepare LaB ₆ dispersion E (Comparative Example 1). . The average particle diameter _{D 50} of the LaB ₆ was 23.0Myuemu.
Table 1 and FIG. 2 show changes in the dispersed particle size with respect to the paint shaker processing time. In the dispersion E prepared by the pulverization and the dispersion treatment for 18 hours, the dispersed particle diameter of LaB ₆ was 105 nm. Moreover, after preparing the dispersion for forming a solar shading body in the same manner as in Example 1, two types of films having different film thicknesses were formed, and the solar transmittance and haze value when the visible light transmittance was 70% were described above. Calculated from a two-point plot of the membrane.
As a result, as shown in Table 1, the solar radiation transmittance was 49.5% and the haze value was 1.1%.

Example 4
It is the same as that of Example 1 except having performed the following bead mill (medium stirring mill) processes instead of the paint shaker process of Example 1. FIG. That is, 13% by weight of pulverized LaB ₆ particles, 13% by weight of a dispersant, and 74% by weight of toluene were mixed and stirred to prepare a 2.4 kg slurry. This slurry was circulated by a bead mill for 10 hours continuously using a ZrO ₂ bead having a diameter of 0.3 mm under the condition of a rotor rotation speed of 13 m / sec, and LaB ₆ dispersion D (Example 4) was obtained. Prepared.
Table 2 and FIG. 3 show changes in the dispersed particle size with respect to the bead mill treatment time. In the dispersion D prepared after the pulverization and the dispersion treatment for 8 hours, the dispersed particle diameter of LaB ₆ was 82.8 nm. Moreover, after preparing the dispersion for forming a solar shading body in the same manner as in Example 1, two types of films having different film thicknesses were formed, and the solar transmittance and haze value when the visible light transmittance was 70% were described above. Calculated from a two-point plot of the membrane.
As a result, as shown in Table 2, the solar radiation transmittance was 47.9%, and the haze value was 0.7%.

(Evaluation of dispersed particle size)
As described above, the change in the dispersed particle size with respect to the paint shaker treatment time and the bead mill treatment time in each Example and Comparative Example is shown in FIGS. 2 and 3 as described above.
As shown in FIG. 2, the time required for boride particles to have a dispersed particle size of, for example, 100 nm or less is 18 hours or less in Examples 1 to 3, whereas it exceeds 20 hours in Comparative Example 1. Moreover, since the haze value when forming a film using the dispersion liquid after 18 hours of the dispersion treatment is larger in Comparative Example 1, coarse particles are larger in Comparative Example 1 than in Examples 2 and 3. Is presumed to exist. Moreover, in Example 4 which performed the bead mill process, as shown in FIG. 3, the dispersion particle diameter is set to 100 nm in 4.5 hours. Thus, since the boride particles obtained in Examples 1 to 4 are atomized in a shorter time as compared with Comparative Example 1, the dispersed particle diameter of the boride particles in the dispersion for forming the solar radiation shielding body It can be easily reduced and production efficiency can be improved.

It is a flowchart which shows the manufacturing process of the boride particle | grains which concern on this invention. It is a graph which shows the change of the dispersion particle diameter of the boride particle | grain with respect to the paint shaker processing time which concerns on this invention. It is a graph which shows the change of the dispersion particle diameter of the boride particle | grains with respect to the bead mill processing time which concerns on this invention.

Explanation of symbols

1 X Compound Solution 2 Alkaline Solution 3 X Hydroxide / Hydrate 4 B ₄ C
5 X Oxide 6 Boride 7 Jet Mill Grinding 8 Solvent 9 Medium Agitation Mill 10 Dispersion Liquid for Formation of Solar Shielding Body 11 Mixing, Continuous Stirring 12 Precipitation 13 Washing 14 Drying 15 Heat Treatment 16 Mixing 17 Heat Treatment 18 Mixing 19 Grinding, dispersion

Claims (6)

Boride particles represented by the general formula XB _m (where X is one or more metal elements selected from alkaline earth elements or rare earth elements including yttrium (Y), 4 ≦ m ≦ 6.3) A manufacturing method of
A step of reacting a solution of a compound containing X with an alkaline solution while stirring to obtain a precipitate;
Drying the precipitate to obtain X hydroxide particles and / or hydrate particles having an average particle size of 0.1 μm or less;
Heat treating the X hydroxide particles and / or hydrate particles to obtain an aggregate of the X oxide particles having an average particle size of 20 μm or less;
And agglomerates of particles of an oxide of the X, the average particle size was mixed with the following B _{4 C} particles 60μm or 22 .mu.m, obtained particles of oxide of X, a mixture of B 4 _C particles Process,
Heat-treating the mixture at a temperature of less than 1600 ° C. in a vacuum or an inert gas atmosphere to obtain boride particles represented by the general formula XB _m and having an average particle diameter D ₅₀ of 20 μm or more and 25 μm or less;
The boride particles collide with each other in a jet stream and pulverized to obtain boride fine particles having a particle size of 0.2 μm or more and 1.5 μm or less;
A method for producing boride particles, comprising: Boride particles represented by the general formula XB _m (where X is one or more metal elements selected from alkaline earth elements or rare earth elements including yttrium (Y), 4 ≦ m ≦ 6.3) A manufacturing method of
A step of reacting a solution of a compound containing X with an alkaline solution while stirring to obtain a precipitate;
Drying the precipitate to obtain X hydroxide particles and / or hydrate particles having an average particle size of 0.1 μm or less;
Mixing the hydroxide and / or hydrate particles of X with B ₄ C particles having an average particle size of 22 μm or more and 60 μm or less, and the hydroxide and / or hydrate particles of X; Obtaining a mixture with particles of B ₄ C;
Heat-treating the mixture at a temperature of less than 1600 ° C. in a vacuum or an inert gas atmosphere to obtain boride particles represented by the general formula XB _m and having an average particle diameter D ₅₀ of 20 μm or more and 25 μm or less;
The boride particles collide with each other in a jet stream and pulverized to obtain boride fine particles having a particle size of 0.2 μm or more and 1.5 μm or less;
A method for producing boride particles, comprising: A method for producing boride particles according to claim 1 or 2,
When mixing the X hydroxide particles and / or hydrate particles, or the X oxide particles and the B ₄ C particles, in the mixing ratio of both, X element: boron atom A method for producing boride particles, wherein the mixing is performed so that the number ratio is 1: 4 to 1: 6.3. A method for producing boride particles according to claim 1 or 2,
When mixing the X hydroxide particles and / or hydrate particles, or the X oxide particles and the B ₄ C particles, in the mixing ratio of both, X element: boron atom A method for producing boride particles, wherein the mixing is performed so that the number ratio is 1: 5.9 to 1: 6.1. A method for producing a boride particle according to any one of claims 1 to 4,
X hydroxide particles and / or hydrate particles having an average particle size of 0.1 μm or less, or X oxide particles having an average particle size of 20 μm or less,
A boride particle production method comprising mixing the B ₄ C particles having an average particle diameter of 60 μm or less.   A boride particle produced by the boride particle production method according to claim 1.

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