JP2017222540A - Heat ray-shielding fine particle and heat ray-shielding fine particle dispersion liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide heat ray-shielding fine particles and a heat ray-shielding fine particle dispersion liquid containing the heat ray-shielding fine particles, which exhibit heat ray-shielding characteristics and suppress scorching feeling on a skin, when applied to a structure such as a window material, and which allow use of a communication apparatus, an imaging apparatus, a sensor or the like using near infrared light through a heat ray-shielding film or a heat ray-shielding glass each constituting the structure, or through a dispersion material or a laminated transparent substrate.SOLUTION: The heat ray-shielding fine particles are composite tungsten oxide fine particles represented by general formula of (LM)WOhaving elements L and M, tungsten, and oxygen, and having a hexagonal crystalline structure, where the element L is an element selected from K, Rb, and Cs and the element M is at least one element selected from K, Rb, and Cs and different from element L.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat ray shielding fine particle and a heat ray shielding fine particle dispersion that transmit near infrared light having a predetermined wavelength while having a good visible light transmittance and an excellent heat ray shielding function.

  Various technologies have been proposed so far as heat ray shielding techniques that have good visible light transmittance and reduce solar radiation transmittance while maintaining transparency. Among them, the heat ray shielding technology using conductive fine particles, a dispersion of conductive fine particles, and a laminated transparent base material has excellent heat ray shielding properties and low cost compared to other technologies, and has radio wave permeability. Further, there are advantages such as high weather resistance.

  For example, Patent Document 1 discloses that a transparent resin containing tin oxide fine powder in a dispersed state or a transparent synthetic resin containing tin oxide fine powder contained in a dispersed state is formed into a sheet or film. An infrared-absorbing synthetic resin molded product laminated on a material has been proposed.

  In Patent Document 2, Sn, Ti, Si, Zn, Zr, Fe, Al, Cr, Co, Ce, In, Ni, Ag, Cu, Pt, Mn, Ta are provided between at least two opposing plate glasses. An intermediate layer in which a metal such as W, V, or Mo, an oxide of the metal, a nitride of the metal, a sulfide of the metal, a Sb or F dopant to the metal, or a mixture thereof is dispersed. A sandwiched laminated glass has been proposed.

  Further, the applicant discloses in Patent Document 3 a selective permeable membrane coating solution and a selectively permeable membrane in which at least one of titanium nitride fine particles and lanthanum boride fine particles is dispersed.

  However, the heat ray shielding structures such as infrared absorbing synthetic resin molded products disclosed in Patent Documents 1 to 3 have a problem that the heat ray shielding performance is not sufficient when high visible light transmittance is required. There was a point. For example, as an example of specific numerical values of the heat ray shielding performance of the heat ray shielding structures disclosed in Patent Documents 1 to 3, the visible light transmittance calculated based on JIS R 3106 (in the present invention, simply “ When the visible light transmittance is sometimes 70%, the solar radiation transmittance calculated based on JIS R 3106 (in the present invention, it may be simply referred to as “sunlight transmittance”). ) Exceeded 50%.

Accordingly, the applicant has disclosed an infrared shielding material fine particle dispersion in which infrared shielding material fine particles are dispersed in a medium, and the infrared shielding material fine particles are represented by the general formula M _x W _y O _z (wherein element M is H , He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, One or more elements selected from I, W is tungsten, O is oxygen, 0.001 ≦ x / y ≦ 1, 2.2 ≦ z / y ≦ 3.0) Composite tungsten oxide fine particles Patent application title: A heat-ray shielding dispersion comprising one or more kinds of fine particles having a crystal structure of tetragonal, tetragonal, or cubic crystals, wherein the infrared shielding material fine particles have a particle diameter of 1 nm to 800 nm. It was disclosed as Reference 4.

As disclosed in Patent Document 4, the heat ray shielding dispersion using the composite tungsten oxide fine particles represented by the general formula M _x W _y O _z exhibits high heat ray shielding performance and has a visible light transmittance of 70%. When solar radiation transmittance was improved to below 50%. In particular, the heat ray shielding fine particle dispersion using the composite tungsten oxide fine particles adopting at least one selected from the specific elements such as Cs, Rb, Tl as the element M and having a crystal structure of hexagonal crystal has excellent heat ray shielding performance. The solar transmittance when the visible light transmittance was 70% was improved to below 37%.

Further, the applicant has the general formula M _a WO _c (where 0.001 ≦ a ≦ 1.0, 2.2 ≦ c ≦ 3.0, and the M element is Cs, Rb, K, Tl, In, Ba, One or more elements selected from Li, Ca, Sr, Fe, and Sn), and containing composite tungsten oxide fine particles having a hexagonal crystal structure, and represented by the general formula M _a WO _c When the powder color of the composite tungsten oxide shown is evaluated in the L ^* a ^* b ^* color system, L ^* is 25 to 80, a ^* is −10 to 10, and b ^* is −15 to 15. An ultraviolet / near-infrared light shielding dispersion characterized by the above is disclosed as Patent Document 5.

JP-A-2-136230 JP-A-8-259279 JP-A-11-181336 International Publication Number WO2005 / 037932 JP 2008-231164 A

The composite tungsten oxide fine particles represented by the general formula M _x W _y O _z , heat ray shielding dispersions, heat ray shielding films, heat ray shielding glasses, heat ray shielding fine particle dispersions and laminated transparent substrates using the same are marketed. As a result of expanding the range of use in Japan, new issues were discovered.
The problem is that the composite tungsten oxide fine particles described by the general formula M _x W _y O _z , the heat ray shielding film or heat ray shielding glass containing the composite tungsten oxide fine particles, and the dispersion containing the composite tungsten oxide fine particles When the body or heat ray shielding laminated transparent base material is applied to a structure such as a window material, the transmittance of near-infrared light having a wavelength of 700 to 1200 nm is greatly reduced in light passing through the window material or the like. It is.
Near-infrared light in this wavelength region is almost invisible to the human eye, and can be oscillated by a light source such as an inexpensive near-infrared LED, so communication and imaging equipment using near-infrared light Widely used in sensors, etc. However, a structure such as a window material using a composite tungsten oxide fine particle represented by the general formula M _x W _y O _z , a structure such as a heat ray shielding body, a heat ray shielding base material, a dispersion, and a laminated transparent base material Absorbs near-infrared light in the wavelength region strongly with heat rays.
As a result, a structure such as a window material using the composite tungsten oxide fine particles represented by the general formula M _x W _y O _z , a heat ray shielding film, a heat ray shielding glass, a dispersion, and a laminated transparent substrate are used. In some cases, communication using near-infrared light, use of imaging devices, sensors, and the like are restricted.

  For example, when the heat ray shielding film using the composite tungsten oxide fine particles described in Patent Document 4 is attached to a window of a general house, it is composed of an infrared oscillator placed indoors and an infrared receiver placed outdoors. The near-infrared light communication between the intrusion detection devices was interrupted, and the devices did not operate normally.

  Despite the existence of the above problems, heat ray shielding films using composite tungsten oxide fine particles, structures such as window materials, dispersions and heat ray shielding laminated transparent base materials have a high ability to cut the heat rays greatly. Use has expanded in market areas where shielding is desired. However, when such a structure, such as a heat ray shielding film or window material, a dispersion or a heat ray shielding laminated transparent base material is used, wireless communication using near infrared light, imaging equipment, sensors, etc. can be used. It was not possible.

In addition, the general formula M _x W _y O or composite tungsten oxide fine particles expressed by _z, the heat ray shielding dispersion using the same heat ray shielding film, solar control glass, heat-ray shielding fine particle dispersion and the combined transparent substrate However, the heat ray with a wavelength of 2100 nm was not sufficiently shielded.

  For example, when the heat ray shielding film using the composite tungsten oxide fine particles described in Patent Document 4 was attached to a window of a general house, the heat felt tingling on the skin indoors.

  The present invention has been made under the above circumstances. And when the problem which it is going to solve is applied to structures, such as a window material, while exhibiting a heat ray shielding characteristic and suppressing the irritating feeling to skin, the structure, the heat ray shielding film, or Heat ray shielding glass, heat ray shielding fine particles enabling use of near infrared light through the dispersion or laminated transparent substrate, imaging equipment, sensors, and the like, and heat rays containing the heat ray shielding fine particles It is to provide a shielding fine particle dispersion.

The present inventors have made various studies in order to solve the above-described problems.
For example, even when a heat ray shielding film, heat ray shielding glass, a heat ray shielding dispersion, and a heat ray shielding laminated transparent base material are used, communication devices, imaging devices, sensors, etc. that use near infrared light can be used. Therefore, it was considered that the transmittance of near-infrared light in the wavelength region of 800 to 900 nm should be improved. If the transmittance of near-infrared light in the wavelength region is simply improved, the concentration of the composite tungsten oxide fine particles in the film, the concentration of the composite tungsten oxide fine particles in the heat ray shielding film or the heat ray shielding glass, the heat ray shielding It has also been considered that the concentration of the composite tungsten oxide fine particles in the dispersion or the heat ray shielding laminated transparent base material may be appropriately reduced.
However, when the concentration of the composite tungsten oxide fine particles, the concentration of the composite tungsten oxide fine particles in the heat ray shielding dispersion or the heat ray shielding laminated transparent base material in the film are decreased, the heat ray absorbing ability with the wavelength range of 1200 to 1800 nm as the bottom. At the same time, the heat ray shielding effect is lowered, and the skin feels irritated.

  Here, it is considered that the sunlight gives the skin a sensation due to the large influence of heat rays with a wavelength of 1500 to 2100 nm (for example, Yoshikazu Ozeki et al. 33-99, 13 (1999), which shows that the absorbance of human skin is small for near-infrared light with a wavelength of 700-1200 nm, but large for heat rays with a wavelength of 1500-2100 nm. This is considered to be the reason.

Based on the above knowledge, the present inventors have conducted various studies. As a result, the composite tungsten oxide fine particles represented by the general formula N B _′ W _C O _D have a near-infrared absorptivity with plasmon resonance. We paid attention to the fact that it is composed of two types of elements, absorption and polaron absorption. Then, the inventors have conceived that the wavelength regions of near infrared light absorbed by the two types of components are different. And in the composite tungsten oxide fine particles, the inventors came up with an epoch-making configuration of controlling the magnitude of polaron absorption while preserving plasmon resonance absorption.

Then, in place of the element N in the composite tungsten oxide represented by the general formula N B _′ W _C O _D , two or more elements L and M are selected from K, Rb, and Cs, and the two or more elements are selected. The inventors have also conceived a configuration in which polaron absorption of the composite tungsten oxide fine particles is controlled by controlling the mixing ratio of the elements L and M.

  Specifically, the near-infrared absorption band of the composite tungsten oxide fine particles is composed of plasmon resonance absorption having a wavelength of 1200 to 1800 nm as a bottom and polaron absorption in a wavelength region of 700 to 1200 nm. By controlling the size of polaron absorption while preserving the absorption, the absorption of the wavelength 800 to 900 nm is controlled while maintaining the heat ray absorption capability with the wavelength 1200 to 1800 nm as the bottom, and in the wavelength 2100 nm region. It has been found that composite tungsten oxide fine particles having improved absorption ability can be obtained.

However, composite tungsten oxide fine particles whose transmittance of near-infrared light is improved in the wavelength range of 800 to 900 nm by controlling the polaron absorption ability are the evaluation criteria of the heat ray shielding performance in the dispersion of heat ray shielding fine particles. As a result, it is inferior to the composite tungsten oxide according to the prior art when evaluated using an index conventionally used (for example, solar transmittance with respect to visible light transmittance evaluated according to JIS R 3106). I was also worried.
Therefore, from this point of view, the composite tungsten oxide fine particles having improved transmittance of near-infrared light having a wavelength of 800 to 900 nm by controlling the magnitude of polaron absorption were further examined.

The composite tungsten oxide fine particles whose transmittance of near infrared light having a wavelength of 800 to 900 nm is improved by controlling the magnitude of polaron absorption described above are compared with the composite tungsten oxide fine particles according to the related art. Thus, it has been found that the performance as heat ray shielding fine particles is not inferior.
This is because the absolute value of plasmon absorption is reduced in the composite tungsten oxide fine particles whose transmittance of near-infrared light having a wavelength of 800 to 900 nm is improved by controlling the magnitude of polaron absorption, but in visible light. This is because the transmittance is increased, the composite tungsten oxide fine particle concentration per unit area can be increased, and the transmission of heat rays having a wavelength of 1500 to 2100 nm can be suppressed.

As a result of the above examination, the present inventors have a heat ray shielding function, have elements L and M, tungsten and oxygen, and are represented by the general formula (L _A M _B ) W _C O _D. The present invention was completed by conceiving composite tungsten oxide fine particles having a crystal system crystal structure.
However, the element L is an element selected from K, Rb, and Cs, and the element M is one or more elements different from the element L, selected from K, Rb, and Cs.

  Furthermore, the present inventors also used a heat ray shielding material, a heat ray shielding film, a heat ray shielding glass, a heat ray shielding dispersion and a laminated transparent substrate using the composite tungsten oxide fine particles according to the present invention as a heat ray shielding material. From the viewpoint of suppressing the irritating feeling on the skin, the present inventors have also found that it is equivalent to the composite tungsten oxide fine particles according to the prior art, and completed the present invention.

That is, the first invention for solving the above-described problem is
Composite tungsten oxide fine particles having elements L and M, tungsten, and oxygen, represented by a general formula (L _A M _B ) W _C O _D and having a hexagonal crystal structure,
The element L is an element selected from K, Rb, and Cs.
The element M is a heat ray shielding fine particle characterized in that it is one or more elements selected from K, Rb, and Cs and different from the element L.
The second invention is
In the composite tungsten oxide fine particles, the atomic ratio (A + B) / C between the elements L and M and W is 0.001 ≦ (A + B) /C≦1.0. It is a heat ray shielding fine particle as described in 1st invention.
The third invention is
In the composite tungsten oxide fine particles, the atomic ratio (A + B) / C between the elements L and M and W is 0.25 ≦ (A + B) /C≦0.35. It is a heat ray shielding fine particle as described in 1st invention.
The fourth invention is:
When the values of A and B are A ≧ B, the heat ray shielding fine particles according to any one of the first to third inventions, wherein B / A ≧ 0.01.
The fifth invention is:
The heat ray shielding fine particles according to any one of the first to fourth inventions, wherein the composite tungsten oxide fine particles have a particle size of 1 nm or more and 800 nm or less.
The sixth invention is:
When the light absorption by only the composite tungsten oxide fine particles is calculated and the visible light transmittance is 85%, the average value of the transmittance in the wavelength range of 800 to 900 nm is 30% to 60%, and The average value of the transmittance in the wavelength range of 1200 to 1500 nm is 20% or less, and the transmittance in the wavelength of 2100 nm is 22% or less, according to any one of the first to fifth inventions These are heat ray shielding fine particles.
The seventh invention
A heat-shielding fine particle according to any one of the first to sixth inventions is a dispersion liquid that is dispersed and contained in a liquid medium,
The liquid medium is water, an organic solvent, a vegetable oil, a vegetable oil-derived compound, a petroleum solvent, an oil or fat, a liquid resin, a plasticizer for a liquid plastic, or a mixture of any two or more of the liquid media. This is a heat ray shielding fine particle dispersion.
The eighth invention
Content of the said heat ray shielding fine particle contained in the said liquid medium is 0.01 mass% or more and 75 mass% or less, It is a heat ray shielding fine particle dispersion liquid of 7th invention characterized by the above-mentioned.

  The structure using the heat ray shielding fine particles and the heat ray shielding fine particle dispersion according to the present invention, the heat ray shielding film or the heat ray shielding glass, the dispersion and the laminated transparent base material exhibit heat ray shielding properties and have a jerky feeling on the skin. Even when these structures and the like are interposed, it is possible to use communication devices, imaging devices, sensors, and the like using near infrared light.

2 is an X-ray diffraction profile of powder A according to Example 1. FIG. 3 is an X-ray diffraction profile of powder B according to Example 2. FIG. 3 is an X-ray diffraction profile of powder C according to Example 3. 4 is an X-ray diffraction profile of powder D according to Example 4. 7 is an X-ray diffraction profile of powder E according to Example 5. FIG. 7 is an X-ray diffraction profile of powder F according to Example 6. FIG. 7 is an X-ray diffraction profile of powder G according to Example 7. 3 is an X-ray diffraction profile of powder H according to Comparative Example 1.

  Hereinafter, embodiments of the present invention will be described in the order of [a] heat ray shielding fine particles, [b] a method of producing heat ray shielding fine particles, and [c] a method of producing a heat ray shielding fine particle dispersion containing heat ray shielding fine particles. .

[A] Heat ray shielding fine particles (composite tungsten oxide fine particles)
The heat ray shielding fine particles according to the present invention include the elements L and M, tungsten, and oxygen, and are represented by the general formula (L _A M _B ) W _C O _D and have a hexagonal crystal structure. In the oxide fine particle, the element L is an element selected from K, Rb, and Cs, and the element M is selected from K, Rb, and Cs, and is one or more kinds different from the element L It is an element. Specifically, the elements L and M can be a combination of KRb, KCs, RbCs, and KRbCs (the order of each element can be changed).
And the light absorption by only the composite tungsten oxide fine particles is calculated, and when the visible light transmittance is 85%, the average value of the transmittance in the wavelength range of 800 to 900 nm is 30% or more and 60% or less. And the average value of the transmittance | permeability in the wavelength range of 1200-1500 nm is 20% or less, and it is a heat ray shielding fine particle whose transmittance | permeability in wavelength 2100 nm is 22% or less.

In the composite tungsten oxide fine particles represented by the general formula (L _A M _B ) W _C O _D , the atomic ratio between the elements L and M and tungsten is 0.001 ≦ (A + B) / C ≦ 1. 0.0, and more preferably 0.25 ≦ (A + B) /C≦0.35. If the value of (A + B) / C is 0.001 or more and 1.0 or less, more preferably 0.25 or more and 0.35 or less, it is easy to obtain a hexagonal crystal single phase of the composite tungsten oxide, and the heat ray absorption effect is sufficient. It is because it expresses. On the other hand, the value of D may be any value as long as the composite tungsten oxide can be hexagonal. In the composite tungsten oxide, tetragonal crystals and orthorhombic crystals may be precipitated in addition to hexagonal crystals. The heat ray absorption effect of these non-hexagonal precipitates does not reach the absorption characteristics of hexagonal composite tungsten oxide. However, there is no particular problem even if these non-hexagonal precipitates are included to such an extent that they do not affect the heat ray absorption effect exhibited by the hexagonal composite tungsten oxide.
The composite tungsten oxide preferably contains no other impurities. The absence of the impurity is confirmed by the fact that no impurity peak is observed when XRD measurement is performed on the composite tungsten oxide powder.

  In the composite tungsten oxide according to the present invention, part of oxygen may be substituted with another element as long as the heat ray absorption effect is not lowered. Examples of the other elements include nitrogen, sulfur, and halogen.

  The particle diameter of the composite tungsten oxide fine particles according to the present invention can be appropriately selected according to the intended use of the composite tungsten oxide fine particles and the heat ray shielding film / heat ray shielding substrate produced using the dispersion liquid. It is preferably 1 nm or more and 800 nm. If the particle diameter is 800 nm or less, strong near infrared absorption by the composite tungsten oxide fine particles according to the present invention can be exhibited. If the particle diameter is 1 nm or more, industrial production is easy. It is.

  When the heat ray shielding film is used for applications requiring transparency, it is preferable that the composite tungsten oxide fine particles have a dispersed particle diameter of 40 nm or less. If the composite tungsten oxide fine particles have a dispersed particle diameter of less than 40 nm, light scattering due to Mie scattering and Rayleigh scattering of the fine particles is sufficiently suppressed, and visibility in the visible light wavelength region is maintained. This is because the transparency can be maintained efficiently. When used for applications such as windshields for automobiles where transparency is required, the dispersion particle diameter of the composite tungsten oxide fine particles should be 30 nm or less, preferably 25 nm or less in order to further suppress scattering.

[B] Method for producing heat ray shielding fine particles The composite tungsten oxide fine particles according to the present invention can be obtained by heat-treating a tungsten compound starting material in an inert gas atmosphere or a reducing gas atmosphere.

First, the tungsten compound starting material will be described.
The tungsten compound starting material according to the present invention is a single substance or a mixture containing each of tungsten and elements L and M. Tungsten acid powder, tungsten trioxide powder, tungsten dioxide powder, tungsten oxide hydrate powder, tungsten hexachloride powder, ammonium tungstate powder, or tungsten hexachloride powder is dissolved in alcohol and then dried. Or tungsten oxide hydrate powder obtained by dissolving tungsten hexachloride in alcohol and then adding water to precipitate and drying it. One or more selected from a tungsten compound powder obtained by drying an ammonium tungstate aqueous solution and a metal tungsten powder are preferable. The raw materials for elements L and M include element L or element M alone, chloride salt of element L or element M, nitrate, sulfate, oxalate, acetate, oxide, carbonate, tungstate, water Examples thereof include, but are not limited to, oxides.

The respective raw materials related to the above-mentioned tungsten and elements L and M are weighed, and the tungsten compound starting materials and elements L and M are blended and mixed in a predetermined amount satisfying 0.001 ≦ (A + B) /C≦1.0. At this time, it is preferable that the respective raw materials related to the elements L and M and tungsten are uniformly mixed as much as possible, if possible, at the molecular level. Therefore, it is most preferable that the above-mentioned raw materials are mixed in the form of a solution, and it is preferable that each raw material can be dissolved in a solvent such as water or an organic solvent.
If each raw material is soluble in a solvent such as water or an organic solvent, the tungsten compound starting raw material according to the present invention can be produced by volatilizing the solvent after thoroughly mixing each raw material and the solvent. However, even if there is no soluble solvent in each raw material, the tungsten compound starting raw material according to the present invention can be produced by mixing each raw material sufficiently uniformly by a known means such as a ball mill.

Next, heat treatment in an inert gas atmosphere or a reducing gas atmosphere will be described. First, the heat treatment conditions in an inert gas atmosphere are preferably 400 ° C. or higher and 1000 ° C. or lower. The starting material heat-treated at 400 ° C. or higher has a sufficient heat ray absorption ability and is efficient as heat ray shielding fine particles. As the inert gas, an inert gas such as Ar or N ₂ is preferably used.

  In addition, as a heat treatment condition in a reducing atmosphere, it is preferable to heat-treat the starting material at 300 ° C. or higher and 900 ° C. or lower. If it is 300 ° C. or higher, the formation reaction of the composite tungsten oxide having a hexagonal crystal structure according to the present invention proceeds, and if it is 900 ° C. or lower, the composite tungsten oxide fine particles having a structure other than the hexagonal crystal or metallic tungsten are not intended. It is preferable that a side reaction product is hardly generated.

The reducing gas at this time is not particularly limited, but H ₂ is preferable. Then, when H ₂ is used as the reducing gas, the composition of the reducing atmosphere, for example, Ar, preferably mixed with 0.1% or more by volume of H ₂ in an inert gas such as N _2, More preferably, 0.2% or more is mixed. H ₂ can be advanced efficiently reduced if more than 0.1% by volume. The reduction temperature and reduction time, the conditions such as the type and concentration of the reducing gas, is expressed by the general formula _{(L A M B) W C} O D, the composite tungsten oxide fine particles having a hexagonal crystal structure (but, The element L is an element selected from K, Rb, and Cs, and the element M is one or more elements selected from K, Rb, and Cs and different from the element L). I can do it. As described above, the atomic ratio between the elements L and M and W in the structure of the composite tungsten oxide is preferably 0.001 ≦ (A + B) /C≦1.0, and 0.25 Although it is more preferable that ≦ (A + B) /C≦0.35, it can be realized by appropriately adjusting the above-described processing conditions.
If necessary, after performing a reduction treatment in a reducing gas atmosphere, a heat treatment may be performed in an inert gas atmosphere. In this case, the heat treatment in an inert gas atmosphere is preferably performed at a temperature of 400 ° C. or higher and 1200 ° C. or lower.

  It is preferable from the viewpoint of improving the weather resistance that the heat ray shielding fine particles according to the present invention are surface-treated and coated with a compound containing at least one selected from Si, Ti, Zr, and Al, preferably an oxide. . In order to perform the surface treatment, a known surface treatment may be performed using an organic compound containing one or more selected from Si, Ti, Zr, and Al. For example, the heat ray shielding fine particles according to the present invention and an organosilicon compound may be mixed and subjected to a hydrolysis treatment.

[C] Heat ray shielding fine particle dispersion The heat ray shielding fine particle dispersion according to the present invention can be produced by dispersing the heat ray shielding fine particles according to the present invention in a liquid medium. The heat ray shielding fine particle dispersion is a dispersion of the conventional composite tungsten oxide fine particles in various fields where other conventional materials that strongly absorb near-infrared rays, such as the composite tungsten oxide disclosed in Patent Document 4, are used. It can be used in the same manner as the liquid.

  Hereinafter, it will be described in the order of [1] production method of heat ray shielding fine particle dispersion and [2] usage example of heat ray shielding fine particle dispersion. In the present invention, the heat ray shielding fine particle dispersion may be simply referred to as “dispersion”.

[1] Manufacturing method of heat ray shielding fine particle dispersion The heat ray shielding fine particles according to the present invention and, if desired, an appropriate amount of a dispersant, a coupling agent, a surfactant, and the like are added to a liquid medium to perform dispersion treatment. The heat ray shielding fine particle dispersion according to the invention can be obtained. The medium of the heat ray shielding fine particle dispersion is required to have a function for maintaining the dispersibility of the heat ray shielding fine particles and a function for preventing application defects when the heat ray shielding fine particle dispersion is applied.

  As a medium, water, organic solvent, vegetable oil, compound derived from vegetable oil, petroleum solvent, fats and oils, liquid resin, liquid plasticizer for plastic, or a mixture thereof can be selected to produce a heat ray shielding dispersion. Various organic solvents such as alcohols, ketones, hydrocarbons, glycols, and water can be selected as organic solvents that satisfy the above requirements. Specifically, alcohol solvents such as methanol, ethanol, 1-propanol, isopropanol, butanol, pentanol, benzyl alcohol and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone and isophorone Solvents such as 3-methyl-methoxy-propionate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, propylene Glycol derivatives such as glycol ethyl ether acetate; Amides such as N-methylformamide, dimethylformamide, dimethylacetamide and N-methyl-2-pyrrolidone; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as ethylene chloride and chlorobenzene Can be mentioned. Among these, organic solvents having low polarity are preferable, and isopropyl alcohol, ethanol, 1-methoxy-2-propanol, dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether acetate, n-butyl acetate and the like are more preferable. preferable. These solvents can be used alone or in combination of two or more.

  As the vegetable oil, linseed oil, sunflower oil, tung oil, sesame oil, cottonseed oil, rapeseed oil, soybean oil, rice bran oil, olive oil, coconut oil, palm oil, dehydrated castor oil and the like are preferable.

  The vegetable oil-derived compound is preferably a fatty acid monoester obtained by directly esterifying a fatty acid of a vegetable oil and a monoalcohol, or a vegetable oil such as an ether.

  As the petroleum solvent, Isopar E, Exol Hexane, Exol Heptane, Exol E, Exol D30, Exol D40, Exol D60, Exol D80, Exol D95, Exol D110, Exol D130 (above, manufactured by Exxon Mobil) and the like are preferable.

  As the liquid resin, methyl methacrylate and the like are preferable. Liquid plasticizers include plasticizers that are compounds of monohydric alcohols and organic acid esters, ester plasticizers such as polyhydric alcohol organic acid ester compounds, and phosphorus compounds such as organic phosphate plasticizers. A preferable example is an acid plasticizer. Of these, triethylene glycol di-2-ethyl hexaonate, triethylene glycol di-2-ethyl butyrate, and tetraethylene glycol di-2-ethyl hexaonate are more preferable because of their low hydrolyzability.

  The dispersant, coupling agent, and surfactant can be selected according to the use, but preferably have an amine-containing group, a hydroxyl group, a carboxyl group, or an epoxy group as a functional group. These functional groups are adsorbed on the surface of the composite tungsten oxide fine particles, prevent aggregation of the composite tungsten oxide fine particles, and have an effect of uniformly dispersing the heat ray shielding fine particles according to the present invention even in the heat ray shielding film.

  Suitable dispersants include, but are not limited to, phosphate ester compounds, polymeric dispersants, silane coupling agents, titanate coupling agents, aluminum coupling agents, and the like. It is not a thing. Examples of the polymer dispersant include an acrylic polymer dispersant, a urethane polymer dispersant, an acrylic block copolymer polymer dispersant, a polyether dispersant, and a polyester polymer dispersant.

  The added amount of the dispersant is desirably in the range of 10 parts by weight to 1000 parts by weight, more preferably in the range of 20 parts by weight to 200 parts by weight with respect to 100 parts by weight of the heat ray shielding fine particles. When the added amount of the dispersant is in the above range, the heat ray shielding fine particles do not aggregate in the liquid, and dispersion stability is maintained.

The dispersion treatment method can be arbitrarily selected from known methods as long as the heat ray shielding fine particles are uniformly dispersed in the liquid medium. For example, a bead mill, a ball mill, a sand mill, an ultrasonic dispersion method or the like can be used.
In order to obtain a uniform heat ray shielding fine particle dispersion, various additives and dispersants may be added, or the pH may be adjusted.

  The content of the heat ray shielding fine particles in the heat ray shielding fine particle dispersion described above is preferably 0.01% by mass to 75% by mass. If it is 0.01 mass% or more, it can be used suitably for manufacture of the coating film mentioned later, a plastic molding, etc., and if it is 75 mass% or less, industrial production is easy. More preferably, it is 1 mass% or more and 35 mass% or less.

  The heat ray shielding fine particle dispersion according to the present invention in which such heat ray shielding fine particles are dispersed in a liquid medium is placed in a suitable transparent container, and the light transmittance is measured as a function of wavelength using a spectrophotometer. be able to. The heat ray shielding fine particle dispersion according to the present invention has a visible light transmittance of 85% when only light absorption by the heat ray shielding fine particles is calculated (in the examples according to the present invention, simply “visible light transmittance is 85%”). The average value of the transmittance in the wavelength range of 800 to 900 nm is 30% or more and 60% or less, and the average value of the transmittance in the wavelength range of 1200 to 1500 nm is 20%. And the transmittance at a wavelength of 2100 nm is 22% or less.

  In this measurement, adjusting the visible light transmittance to 85% when calculating only the light absorption by the heat ray shielding fine particles contained in the heat ray shielding fine particle dispersion has compatibility with the dispersion solvent or the dispersion solvent. This can be done easily by diluting with an appropriate solvent.

  The light transmittance profile of the heat ray shielding fine particle dispersion according to the present invention described above generally includes composite tungsten oxide fine particles having a composition equivalent to that of the heat ray shielding fine particles according to the present invention, except that the elements L and M are included. Compared with the transmission profile of light when using the light, the width of the visible light transmission band spreads to the long wavelength side without greatly increasing the minimum value of the solar radiation transmittance existing in the wavelength range of 1200 to 1500 nm, and the wavelength of 800 It has a transmittance of near infrared light in a range of ˜900 nm.

[2] Example of use of heat ray shielding fine particle dispersion The heat ray shielding fine particles or the heat ray shielding fine particle dispersion according to the present invention is dispersed in a solid medium, thereby dispersing powder, a master batch, a heat ray shielding film, and a heat ray shielding plastic molding. A body etc. can be manufactured.

  As an example of a general method of use, a method for producing a heat ray shielding film using the heat ray shielding fine particle dispersion according to the present invention will be described. A heat ray shielding film can be produced by mixing the heat ray shielding fine particle dispersion described above with a plastic or monomer to produce a coating solution and forming a coating film on a substrate by a known method.

  As the medium of the coating film, for example, a UV curable resin, a thermosetting resin, an electron beam curable resin, a room temperature curable resin, a thermoplastic resin, or the like can be selected according to the purpose. Specifically, polyethylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, polystyrene resin, polypropylene resin, ethylene vinyl acetate copolymer, polyester resin, polyethylene terephthalate resin, fluorine resin, polycarbonate resin, acrylic resin And polyvinyl butyral resin. These resins may be used alone or in combination. Also, a binder using a metal alkoxide can be used. Representative examples of the metal alkoxide include alkoxides such as Si, Ti, Al, and Zr. Binders using these metal alkoxides can form oxide films by hydrolysis and condensation polymerization by heating or the like.

  The base material may be a film as described above, but may be a board if desired, and the shape is not limited. As the transparent substrate material, PET, acrylic, urethane, polycarbonate, polyethylene, ethylene vinyl acetate copolymer, vinyl chloride, fluorine resin, and the like can be used according to various purposes. Moreover, glass other than resin can be used.

Hereinafter, the present invention will be described more specifically with reference to examples.
However, the present invention is not limited to the following examples.

The transmittance of the heat ray shielding fine particle dispersion in each example for light having a wavelength of 300 to 2100 nm is a spectrophotometer cell (manufactured by GL Sciences, model number: S10-SQ-1, material: synthetic quartz, optical path length: 1 mm). ) And the dispersion was held and measured using a spectrophotometer U-4100 manufactured by Hitachi, Ltd.
At the time of the measurement, the transmittance was measured in a state where the solvent of the dispersion (methyl isobutyl ketone) was filled in the above-described cell, and a baseline for transmittance measurement was obtained. As a result, the spectral transmittance and visible light transmittance described below are calculated only for light absorption by the heat ray shielding fine particles, excluding contributions from light reflection on the cell surface for spectrophotometers and light absorption of the solvent. It will be.
The visible light transmittance was calculated based on JIS R 3106 from the transmittance for light having a wavelength of 380 to 780 nm. The average dispersed particle size of the heat ray shielding fine particles was measured using a Microtrac particle size distribution meter manufactured by Nikkiso Co., Ltd.

[Example 1]
(MIBK dispersion of composite tungsten oxide fine particles in which Rb / Cs / W (molar ratio) = 0.30 / 0.03 / 1.00)
Tungstic acid (H ₂ WO ₄ ) and powders of cesium hydroxide (CsOH) and rubidium hydroxide (RbOH) are mixed into Rb / Cs / W (molar ratio) = 0.30 / 0.03 / 1.00. After weighing in an appropriate ratio, the mixture was sufficiently mixed in an agate mortar to obtain a mixed powder. The mixed powder was heated while supplying 5% H ₂ gas with N ₂ gas as a carrier, subjected to reduction treatment at a temperature of 600 ° C. for 1 hour, and then at 800 ° C. for 30 minutes in an N ₂ gas atmosphere. Firing was performed to obtain composite tungsten oxide fine particles (hereinafter abbreviated as “powder A”) which are heat ray shielding fine particles according to Example 1.

  FIG. 1 shows an X-ray diffraction profile obtained by measuring the powder A by the X-ray diffraction method. The obtained X-ray diffraction profile revealed that powder A was a hexagonal single phase. Therefore, in the powder A, it was determined that the Rb component, the Cs component, and the tungsten component were completely dissolved in the crystal of the hexagonal composite tungsten oxide fine particles.

Acrylic polymer dispersant having 20% by mass of powder A and a group containing an amine as a functional group (an acrylic dispersant having an amine value of 48 mgKOH / g and a decomposition temperature of 250 ° C.) (hereinafter abbreviated as “dispersant a”). ) 10% by mass and 70% by mass of methyl isobutyl ketone (MIBK) were weighed. These were loaded into a paint shaker containing 0.3 mmφZrO ₂ beads, and pulverized and dispersed for 15 hours to obtain a heat ray shielding fine particle dispersion (hereinafter abbreviated as “dispersion A”). Here, the average dispersed particle size of the heat ray shielding fine particles in the dispersion A was measured and found to be 26 nm.

Dispersion A was appropriately diluted with MIBK and placed in a 10 mm thick rectangular container, and the spectral transmittance was measured. From the transmittance profile of Dispersion A when measuring the dilution rate so that the visible light transmittance is 85%, the average value of transmittance at a wavelength of 800 to 900 nm is 37.1%, and the wavelength is 1200 to 1200. The average transmittance at 1500 nm was found to be 8.2%, and the transmittance at a wavelength of 2100 nm was found to be 15.2%.
From the measurement results, the composite tungsten oxide fine particles according to Example 1 clearly have a visible light transmission band wider than the cesium tungsten bronze produced by the conventional method according to Comparative Example 1 described later, and have a wavelength of 2100 nm. It was confirmed that the heat ray shielding performance was improved.
The measurement results of dispersion A are shown in Table 1.

[Example 2]
(MIBK dispersion of composite tungsten oxide fine particles in which Rb / K / W (molar ratio) = 0.10 / 0.23 / 1.00)
Tungstic acid (H ₂ WO ₄ ) and powders of rubidium hydroxide (RbOH) and potassium hydroxide (KOH) are mixed into Rb / K / W (molar ratio) = 0.10 / 0.23 / 1.00. Composite tungsten oxide fine particles (hereinafter abbreviated as “powder B”), which are heat ray shielding fine particles according to Example 2, were obtained in the same manner as in Example 1 except that they were weighed at an appropriate ratio.

  The result of measuring Powder B by X-ray diffraction is shown in FIG. The obtained X-ray diffraction profile revealed that powder B was a hexagonal single phase. Therefore, it was determined that the Rb component, the K component, and the tungsten component were completely dissolved in the hexagonal composite tungsten oxide fine particles.

20% by mass of powder B, 10% by mass of dispersant a, and 70% by mass of MIBK were weighed. These were loaded into a paint shaker containing 0.3 mmφZrO ₂ beads, and pulverized and dispersed for 12 hours to obtain a heat ray shielding fine particle dispersion (hereinafter abbreviated as “dispersion B”). Here, when the average dispersed particle diameter of the heat ray shielding fine particles in the dispersion B was measured, it was 21 nm.

Dispersion B was appropriately diluted with MIBK and placed in a 10 mm thick rectangular container, and the spectral transmittance was measured. From the transmittance profile of Dispersion B when measured by adjusting the dilution rate so that the visible light transmittance is 85%, the average value of the transmittance at a wavelength of 800 to 900 nm is 58.3% and the wavelength of 1200 to 1200. The average transmittance at 1500 nm was found to be 19.4%, and the transmittance at a wavelength of 2100 nm was found to be 16.2%.
The measurement results of Dispersion B are shown in Table 1.

[Example 3]
(MIBK dispersion of composite tungsten oxide fine particles with Rb / K / W (molar ratio) = 0.20 / 0.13 / 1.00)
Each powder of tungstic acid (H ₂ WO ₄ ), rubidium hydroxide (RbOH) and potassium hydroxide (KOH) was converted into Rb / K / W (molar ratio) = 0.20 / 0.13 / 1.00. Composite tungsten oxide fine particles (hereinafter abbreviated as “powder C”) as heat ray shielding fine particles according to Example 3 were obtained in the same manner as in Example 1 except that they were weighed at a corresponding ratio.

  The result of measuring powder C by X-ray diffraction is shown in FIG. The obtained X-ray diffraction profile revealed that powder C was a hexagonal single phase. Therefore, it was determined that the Rb component, the K component, and the tungsten component were completely dissolved in the hexagonal composite tungsten oxide fine particles.

20% by mass of powder C, 10% by mass of dispersant a, and 70% by mass of MIBK were weighed. These were loaded into a paint shaker containing 0.3 mmφZrO ₂ beads and pulverized and dispersed for 12 hours to obtain a heat ray shielding fine particle dispersion (hereinafter referred to as “dispersion C”). Here, when the average dispersed particle diameter of the heat ray shielding fine particles in the dispersion C was measured, it was 18 nm.

Dispersion C was appropriately diluted with MIBK and placed in a 10 mm thick rectangular container, and the spectral transmittance was measured. From the transmittance profile of Dispersion C when the dilution rate was adjusted so that the visible light transmittance was 85%, the average transmittance at a wavelength of 800 to 900 nm was 53.3%, and the wavelength was 1200 to 1200. The average transmittance at 1500 nm was found to be 13.2%, and the transmittance at a wavelength of 2100 nm was found to be 11.5%.
The measurement results of Dispersion C are shown in Table 1.

[Example 4]
(MIBK dispersion of composite tungsten oxide fine particles with Cs / K / W (molar ratio) = 0.05 / 0.28 / 1.00)
Tungstic acid (H ₂ WO ₄ ) and powders of cesium hydroxide (CsOH) and potassium hydroxide (KOH) were mixed into Cs / K / W (molar ratio) = 0.05 / 0.28 / 1.00. Composite tungsten oxide fine particles (hereinafter abbreviated as “powder D”), which are heat ray shielding fine particles according to Example 4, were obtained in the same manner as in Example 1 except that they were weighed at a corresponding ratio.

  The result of measuring the powder D by the X-ray diffraction method is shown in FIG. From the obtained X-ray diffraction profile, it was found that the powder D was a hexagonal single phase. Therefore, it was determined that the Cs component, the K component, and the tungsten component were completely dissolved in the crystal of the hexagonal composite tungsten oxide fine particles.

20% by mass of powder D, 10% by mass of dispersant a, and 70% by mass of MIBK were weighed. These were loaded into a paint shaker containing 0.3 mmφZrO ₂ beads, and pulverized and dispersed for 12 hours to obtain a heat ray shielding fine particle dispersion (hereinafter referred to as “dispersion D”). Here, when the average dispersed particle diameter of the heat ray shielding fine particles in the dispersion D was measured, it was 23 nm.

Dispersion D was appropriately diluted with MIBK and placed in a 10 mm thick rectangular container, and the spectral transmittance was measured. From the transmittance profile of Dispersion D when the dilution rate was adjusted so that the visible light transmittance was 85%, the average transmittance at a wavelength of 800 to 900 nm was 57.7%, and the wavelength was 1200 to 1200. The average transmittance at 1500 nm was found to be 15.7%, and the transmittance at a wavelength of 2100 nm was found to be 13.3%.
The measurement results of Dispersion D are shown in Table 1.

[Example 5]
(MIBK dispersion of composite tungsten oxide fine particles with Cs / K / W (molar ratio) = 0.10 / 0.23 / 1.00)
Each powder of tungstic acid (H ₂ WO ₄ ), cesium hydroxide (CsOH) and potassium hydroxide (KOH) was converted into Cs / K / W (molar ratio) = 0.10 / 0.23 / 1.00. Composite tungsten oxide fine particles (hereinafter abbreviated as “powder E”), which are heat ray shielding fine particles according to Example 5, were obtained in the same manner as in Example 1 except that they were weighed at a corresponding ratio.

  The result of measuring the powder E by the X-ray diffraction method is shown in FIG. The obtained X-ray diffraction profile revealed that the powder E was a hexagonal single phase. Therefore, it was determined that the Cs component, the K component, and the tungsten component were completely dissolved in the crystal of the hexagonal composite tungsten oxide fine particles.

20% by mass of powder E, 10% by mass of dispersant a, and 70% by mass of MIBK were weighed. These were loaded into a paint shaker containing 0.3 mmφZrO ₂ beads and pulverized and dispersed for 12 hours to obtain a heat ray shielding fine particle dispersion (hereinafter referred to as “dispersion E”). Here, when the average dispersed particle diameter of the heat ray shielding fine particles in the dispersion E was measured, it was 24 nm.

Dispersion E was appropriately diluted with MIBK and placed in a 10 mm thick rectangular container, and the spectral transmittance was measured. From the transmittance profile of dispersion E when the dilution rate was adjusted so that the visible light transmittance was 85%, the average transmittance value at a wavelength of 800 to 900 nm was 50.7%, and the wavelength was 1200 to 1200. The average transmittance at 1500 nm was found to be 10.9%, and the transmittance at a wavelength of 2100 nm was found to be 10.7%.
The measurement results of Dispersion E are shown in Table 1.

[Example 6]
(MIBK dispersion of composite tungsten oxide fine particles with Cs / K / W (molar ratio) = 0.20 / 0.13 / 1.00)
Each powder of tungstic acid (H ₂ WO ₄ ), cesium hydroxide (CsOH) and potassium hydroxide (KOH) was converted into Cs / K / W (molar ratio) = 0.20 / 0.13 / 1.00. Composite tungsten oxide fine particles (hereinafter abbreviated as “powder F”), which are heat ray shielding fine particles according to Example 6, were obtained in the same manner as in Example 1 except that they were weighed at a corresponding ratio.

  The result of measuring the powder F by the X-ray diffraction method is shown in FIG. From the obtained X-ray diffraction profile, it was found that the powder F was a hexagonal single phase. Therefore, it was determined that the Cs component, the K component, and the tungsten component were completely dissolved in the crystal of the hexagonal composite tungsten oxide fine particles.

20% by mass of powder F, 10% by mass of dispersant a, and 70% by mass of MIBK were weighed. These were loaded into a paint shaker containing 0.3 mmφZrO ₂ beads and pulverized and dispersed for 12 hours to obtain a heat ray shielding fine particle dispersion (hereinafter referred to as “dispersion F”). Here, when the average dispersed particle diameter of the heat ray shielding fine particles in the dispersion F was measured, it was 28 nm.

Dispersion F was appropriately diluted with MIBK and placed in a 10 mm thick rectangular container, and the spectral transmittance was measured. From the transmittance profile of the dispersion F when the dilution rate was adjusted so that the visible light transmittance was 85%, the average transmittance value at a wavelength of 800 to 900 nm was 42.5%, and the wavelength was 1200 to 1200. The average transmittance at 1500 nm was found to be 8.0%, and the transmittance at a wavelength of 2100 nm was found to be 10.7%.
The measurement results of Dispersion F are shown in Table 1.

[Example 7]
(MIBK dispersion of composite tungsten oxide fine particles in which Cs / K / W (molar ratio) = 0.25 / 0.08 / 1.00)
Each powder of tungstic acid (H ₂ WO ₄ ), cesium hydroxide (CsOH) and potassium hydroxide (KOH) was converted into Cs / K / W (molar ratio) = 0.25 / 0.08 / 1.00. Composite tungsten oxide fine particles (hereinafter abbreviated as “powder G”), which are heat ray shielding fine particles according to Example 7, were obtained in the same manner as in Example 1 except that they were weighed at an appropriate ratio.

  The result of measuring the powder G by the X-ray diffraction method is shown in FIG. The obtained X-ray diffraction profile revealed that the powder G was a hexagonal single phase. Therefore, it was determined that the Cs component, the K component, and the tungsten component were completely dissolved in the crystal of the hexagonal composite tungsten oxide fine particles.

20% by weight of powder G, 10% by weight of dispersant a, and 70% by weight of MIBK were weighed. These were loaded into a paint shaker containing 0.3 mmφZrO ₂ beads and pulverized and dispersed for 12 hours to obtain a heat ray shielding fine particle dispersion (hereinafter referred to as “dispersion G”). Here, when the average dispersed particle diameter of the heat ray shielding fine particles in the dispersion G was measured, it was 20 nm.

Dispersion G was appropriately diluted with MIBK and placed in a 10 mm thick rectangular container, and the spectral transmittance was measured. From the transmittance profile of the dispersion G when measuring the dilution rate so that the visible light transmittance is 85%, the average value of the transmittance at a wavelength of 800 to 900 nm is 34.6%, and the wavelength is 1200 to 1200. The average transmittance at 1500 nm was found to be 7.0%, and the transmittance at a wavelength of 2100 nm was found to be 14.1%.
The measurement results of dispersion G are shown in Table 1.

[Comparative Example 1]
(MIBK dispersion of composite tungsten oxide fine particles with Cs / W (molar ratio) = 0.33 / 1.00)
Example 1 except that each powder of tungstic acid (H ₂ WO ₄ ) and cesium hydroxide (CsOH) was weighed at a ratio corresponding to Cs / W (molar ratio) = 0.33 / 1.00 Similarly, composite tungsten oxide fine particles (hereinafter abbreviated as “powder H”), which are heat ray shielding fine particles according to Comparative Example 1, were obtained.

  The result of measuring powder H by the X-ray diffraction method is shown in FIG. The obtained X-ray diffraction profile revealed that the powder H was a hexagonal single phase. Therefore, it was determined that the Cs component and the tungsten component were completely dissolved in the crystal of the hexagonal composite tungsten oxide fine particles.

20% by mass of powder H, 10% by mass of dispersant a, and 70% by mass of MIBK were weighed. These were loaded into a paint shaker containing 0.3 mmφZrO ₂ beads, and pulverized and dispersed for 12 hours to obtain a heat ray shielding fine particle dispersion (hereinafter abbreviated as “dispersion H”). Here, when the average dispersed particle diameter of the heat ray shielding fine particles in the dispersion H was measured, it was 29 nm.

The dispersion H was appropriately diluted with MIBK and placed in a 10 mm thick rectangular container, and the spectral transmittance was measured. From the transmittance profile of the dispersion H when the dilution rate was adjusted so that the visible light transmittance was 85%, the average transmittance at a wavelength of 800 to 900 nm was 21.7%, and the wavelength was 1200 to 1200. It was found that the average value of transmittance at 1500 nm was 10.9%, and the transmittance at wavelength 2100 nm was 22.3%.
The measurement results of dispersion H are shown in Table 1.

[Evaluation of Examples 1 to 7 and Comparative Example 1]
Compared with Comparative Example 1 which is a conventional composite tungsten oxide fine particle, the composite tungsten oxide fine particle which is a heat ray shielding fine particle according to Examples 1 to 7 has a wavelength of 800 to 800 when the visible light transmittance is 85%. The average transmittance of near-infrared light at 900 nm is high, and the transmittance at wavelengths of 1200 to 1500 nm and 2100 nm is low. From this result, it was found that high transmittance was obtained with near-infrared light having a wavelength of 800 to 900 nm while ensuring high heat-shielding characteristics exhibited by the composite tungsten oxide fine particles, and the irritability to the skin was reduced. .

Claims (8)

Composite tungsten oxide fine particles having elements L and M, tungsten, and oxygen, represented by a general formula (L _A M _B ) W _C O _D and having a hexagonal crystal structure,
The element L is an element selected from K, Rb, and Cs.
The heat ray shielding fine particles, wherein the element M is one or more elements selected from K, Rb, and Cs and different from the element L.   In the composite tungsten oxide fine particles, the atomic ratio (A + B) / C between the elements L and M and W is 0.001 ≦ (A + B) /C≦1.0. The heat ray shielding fine particles according to claim 1.   In the composite tungsten oxide fine particles, the atomic ratio (A + B) / C between the elements L and M and W is 0.25 ≦ (A + B) /C≦0.35. The heat ray shielding fine particles according to claim 1.   4. The heat ray shielding fine particles according to claim 1, wherein B / A ≧ 0.01 when the values of A and B are A ≧ B. 5.   The heat ray shielding fine particles according to any one of claims 1 to 4, wherein the composite tungsten oxide fine particles have a particle diameter of 1 nm or more and 800 nm or less.   When the light absorption by only the composite tungsten oxide fine particles is calculated and the visible light transmittance is 85%, the average value of the transmittance in the wavelength range of 800 to 900 nm is 30% to 60%, and 6. The heat ray according to claim 1, wherein an average value of transmittance in a wavelength range of 1200 to 1500 nm is 20% or less and a transmittance in a wavelength of 2100 nm is 22% or less. Shielding fine particles. The heat ray shielding fine particles according to any one of claims 1 to 6, wherein the heat ray shielding fine particles are dispersed and contained in a liquid medium,
The liquid medium is water, an organic solvent, a vegetable oil, a vegetable oil-derived compound, a petroleum solvent, an oil or fat, a liquid resin, a plasticizer for a liquid plastic, or a mixture of any two or more of the liquid media. A heat ray shielding fine particle dispersion characterized by the above.   The heat ray shielding fine particle dispersion according to claim 7, wherein the content of the heat ray shielding fine particles contained in the liquid medium is 0.01% by mass or more and 75% by mass or less.