JP5673273B2 - Near-infrared absorbing particles and production method thereof, dispersion liquid, resin composition, article having near-infrared absorbing coating film and near-infrared absorbing article - Google Patents

Description

  The present invention relates to a near-infrared absorbing particle that absorbs light in the near-infrared region, a method for producing the same, a dispersion containing the near-infrared absorbing particle, a resin composition, an article having a near-infrared absorbing coating film, and a near-infrared absorbing article.

  Sensitivity of imaging devices such as cameras (CCD, CMOS, etc.) and light receiving devices such as automatic exposure meters ranges from the visible light region to the near infrared region. On the other hand, human visibility is only in the visible light region. Therefore, for example, in a camera, a near-infrared filter that transmits light in the visible light region (420 to 630 nm) and absorbs or reflects light in the near-infrared region (700 to 1100 nm) is interposed between the lens and the image sensor. By providing, the sensitivity of the image sensor is corrected so as to approach the human visibility. In order to make it closer to human visibility, the near-infrared filter is required to have a sharp change in transmittance between wavelengths of 630 to 700 nm.

As a near-infrared filter, a filter having a near-infrared absorbing coating formed by applying a paint obtained by adding a binder resin or the like to a dispersion obtained by dispersing near-infrared absorbing particles in a dispersion medium on the surface of a glass substrate. Are known.
Some near infrared absorbing particles containing copper and phosphoric acid have been proposed.
(1) The wavelength of 700 was obtained by treating the surface of near-infrared absorbing particles having a CuO / P ₂ O ₅ molar ratio of 0.05 to 4 in terms of copper as CuO and phosphoric acid as P ₂ O ₅ with an aluminum compound. Near-infrared absorbing particles that absorb light of ˜1100 nm (Patent Document 1).
(2) A dispersion in which copper phosphate is dispersed in a dispersion medium using a dispersant (Patent Document 2).

  It has been confirmed that the near-infrared absorbing particles of (1) and the dispersion liquid of (2) both absorb near-infrared rays having a wavelength of 800 nm or more. However, the transmittance of the near-infrared absorbing film does not change sharply between wavelengths of 630 to 700 nm, and does not sufficiently satisfy the performance required for the near-infrared filter.

Japanese Patent Application Laid-Open No. 07-070548 JP 2004-231708 A

Therefore, the inventors of the present invention have a near-infrared absorbing particle composed of a crystallite of the compound represented by the following formula (1) that has a high transmittance in the visible light region, a low transmittance in the near-infrared region, and a wavelength of 630 to 630. It has been found that the transmittance changes sharply between 700 nm (Japanese Patent Application No. 2009-227554).
A _{1 / n} CuPO ₄ (1).
However, A is an alkali metal (Li, Na, K, Rb , Cs), alkaline earth metal and a (Mg, Ca, Sr, Ba ) and one or more selected from the group consisting of NH _4,
n is 1 when A is an alkali metal or NH ₄ , and 2 when A is an alkaline earth metal.

However, when the near-infrared absorbing particles absorb moisture, the crystallites cannot maintain the crystal structure of A _{1 / n} CuPO ₄ , the transmittance in the visible light region is lowered, and the transmittance in the near-infrared region is reduced. Has the problem of becoming high.

  The present invention relates to a near-infrared absorbing particle having high transmittance in the visible light region, low transmittance in the near-infrared region, a sharp change in transmittance between wavelengths of 630 to 700 nm, and excellent moisture resistance, and a method for producing the same , A dispersion, a resin composition, an article having a near-infrared absorbing coating film, and a near-infrared absorbing article.

The near-infrared absorbing particles of the present invention are obtained by surface-treating particles composed of crystallites of a compound represented by the following formula (1) with an alkoxide of a metal M selected from the group consisting of Al, Zr, Ti and Sn. It is characterized by that.
In the near-infrared absorbing particles of the present invention, the element of the metal M selected from the group consisting of Al, Zr, Ti and Sn is unevenly distributed on the surface of the particles made of crystallites of the compound represented by the following formula (1). The near-infrared absorbing particle is characterized in that the atomic number concentration ratio (Cu / M) of M element and Cu element obtained by energy dispersive X-ray analysis is 2.0 to 10.6.
A _{1 / n} CuPO ₄ (1).
However, A is an alkali metal (Li, Na, K, Rb , Cs), alkaline earth metal and a (Mg, Ca, Sr, Ba ) and one or more selected from the group consisting of NH _4,
n is 1 when A is an alkali metal or NH ₄ , and 2 when A is an alkaline earth metal.

  In the near-infrared absorbing particles of the present invention, the crystallite size determined from X-ray diffraction is 5 to 50 nm, the number-average aggregated particle diameter of the near-infrared absorbing particles is 20 to 200 nm, The reflectance at a wavelength of 450 nm in the diffuse reflection spectrum of the infrared absorbing particles is preferably 80% or more.

The near-infrared absorbing particles of the present invention preferably have a reflectance change amount D represented by the following formula (2) of -0.41 or less.
D (% / nm) = [ _R700 (%)- _R600 (%)] / [700 (nm) -600 (nm)] (2).
However, R ₇₀₀ is a reflectance at a wavelength of 700 nm in the diffuse reflection spectrum of the near-infrared absorbing particles, and R ₆₀₀ is a reflectance at a wavelength of 600 nm in the diffuse reflection spectrum of the near-infrared absorbing particles.

  In the near-infrared absorbing particles of the present invention, the reflectance at a wavelength of 715 nm in the diffuse reflection spectrum of the near-infrared absorbing particles is preferably 19% or less, and the reflectance at a wavelength of 500 nm is preferably 85% or more.

The manufacturing method of the near-infrared absorption particle | grains of this invention has the following process (d), It is characterized by the above-mentioned.
(D) A step of surface-treating particles comprising crystallites of the compound represented by the formula (1) with an alkoxide of a metal M selected from the group consisting of Al, Zr, Ti and Sn.

It is preferable that the manufacturing method of the near-infrared absorption particle | grains of this invention further has the following process (a)-process (c).
At (a) in a solvent, a salt containing ^{Cu 2+,} a salt or an organic material containing _PO ^{4 3-,} _PO ^{4 3-} molar ratio with respect to _{^{Cu 2+ (PO 4 3- / Cu}} 2+) 10-20 And A ^{n +} (where A is an alkali metal (Li, Na, K, Rb, Cs), alkaline earth metal (Mg, Ca, Sr, Ba) and NH ₄ ) 1 or more selected, and n is 1 when A is an alkali metal or NH ₄ , and 2 when A is an alkaline earth metal). Is a step of dispersing a raw material in a dispersion medium to obtain a raw material slurry.
(B) A step of introducing particles of the raw material slurry obtained in the step (a) into thermal plasma or flame and cooling the resulting product to obtain particles.
(C) A step of heat-treating the particles obtained in the step (b) at 300 to 700 ° C. to obtain particles composed of crystallites of the compound represented by the formula (1).

The dispersion of the present invention is characterized in that the near-infrared absorbing particles of the present invention are dispersed in a dispersion medium.
The resin composition of the present invention is characterized in that the near-infrared absorbing particles of the present invention are dispersed in a resin.
The article having the near-infrared absorbing coating film of the present invention is characterized by having a near-infrared absorbing coating film containing the near-infrared absorbing particles of the present invention on the surface of a substrate.
The near-infrared absorbing article of the present invention includes the near-infrared absorbing particles of the present invention.

The near-infrared absorbing particles of the present invention have a high transmittance in the visible light region, a low transmittance in the near-infrared region, a sharp change in wavelength between 630 to 700 nm, and excellent moisture resistance.
According to the method for producing near-infrared absorbing particles of the present invention, the transmittance in the visible light region is high, the transmittance in the near-infrared region is low, the transmittance sharply changes between wavelengths of 630 to 700 nm, and the moisture resistance. It is possible to produce near-infrared absorbing particles that are superior to the above.
The dispersion of the present invention has a high transmittance in the visible light region, a low transmittance in the near-infrared region, a sharp change in transmittance between wavelengths of 630 to 700 nm, and an excellent near-infrared absorbing coating film. It is useful for the formation of
The resin composition of the present invention has a high transmittance in the visible light region, a low transmittance in the near-infrared region, a sharp change in transmittance between wavelengths of 630 to 700 nm, and excellent near-infrared absorption coating. It is useful for forming films and near infrared absorbing articles.
The article having the near-infrared absorbing coating film of the present invention has a high transmittance in the visible light region, a low transmittance in the near-infrared region, a sharp change in transmittance between wavelengths of 630 to 700 nm, and Excellent moisture resistance.
The near-infrared absorbing article of the present invention has a high transmittance in the visible light region, a low transmittance in the near-infrared region, a sharp change in wavelength between 630 and 700 nm, and excellent moisture resistance.

It is a figure which shows the result of the X-ray diffraction of the near-infrared absorption particle before the surface treatment of Example 1. FIG. 4 is a diagram showing the results of X-ray diffraction of near-infrared absorbing particles after the surface treatment of Example 1. FIG. 4 is a diagram showing the results of X-ray diffraction of near-infrared absorbing particles after the wet heat resistance test of Example 1. 2 is a diffuse reflection spectrum of near-infrared absorbing particles before and after the wet heat resistance test of Example 1. It is a figure which shows the result of the X-ray diffraction of the near-infrared absorption particle after the heat-and-moisture resistance test of Example 9. It is a diffuse reflection spectrum of the near-infrared absorbing particles before and after the wet heat resistance test of Example 9.

<Near-infrared absorbing particles>
The near-infrared absorbing particles of the present invention are obtained by surface-treating particles composed of crystallites of a compound represented by the following formula (1) with an alkoxide of a metal M selected from the group consisting of Al, Zr, Ti and Sn. .
A _{1 / n} CuPO ₄ (1).
However, A is an alkali metal (Li, Na, K, Rb , Cs), alkaline earth metal and a (Mg, Ca, Sr, Ba ) and one or more selected from the group consisting of NH _4,
n is 1 when A is an alkali metal or NH ₄ , and 2 when A is an alkaline earth metal.

“Crystallite” means a unit crystal that can be regarded as a single crystal, and “particle” is composed of a plurality of crystallites.
"Consisting crystallites of the compound represented by formula (1)", for example, as shown in FIG. 1, you can see the crystal structure of A _{1 / n} CuPO ₄ by X-ray diffraction, essentially A _{1 / n} It means that it consists of crystallites CuPO ₄ have been identified by X-ray diffraction, and "consisting of crystallites substantially _a 1 / n CuPO _4" is crystallite _a 1 / n CuPO ₄ This means that impurities may be contained within a range in which the crystal structure of A _{1 / n} CuPO ₄ can be confirmed by X-ray diffraction.
X-ray diffraction is measured with a X-ray diffractometer on powdered near-infrared absorbing particles.

The reason why alkali metal, alkaline earth metal or NH ₄ is used as A in the present invention is as follows (i) to (iii).
(I) The crystal structure of the crystallite in the near-infrared absorbing particles of the present invention is a network-like three-dimensional skeleton composed of alternating bonds of PO ₄ ³⁻ and Cu ^2+, and has a space inside the skeleton. The size of the space is alkali metal ion (Li ⁺ : 0.90Å, Na ⁺ : 1.16Å, K ⁺ : 1.52Å, Rb ⁺ : 1.66 ：, Cs ⁺ : 1.81Å), alkaline earth metal In order to match the ionic radius of ions (Mg ²⁺ : 0.86 Å, Ca ²⁺ : 1.14 Å, Sr ²⁺ : 1.32 Å, Ba ²⁺ : 1.49 Å) and NH ₄ ⁺ (1.66 Å) Sufficiently maintain.

(Ii) Alkali metal ions, alkaline earth metal ions, and NH ₄ ⁺ can stably exist as monovalent or divalent cations in the solution, and therefore, when the precursor is generated in the production process of near-infrared absorbing particles. Cations are easily incorporated into the crystal structure.
(Iii) A cation having a strong coordination bond with PO ₄ ³⁻ , such as a transition metal ion, may give a crystal structure different from the crystal structure in the present invention that exhibits sufficient near infrared absorption characteristics.
As A, the cation size is most suitable as an ion taken into the skeleton composed of PO ₄ ³⁻ and Cu ^2+, and K is particularly preferable from the viewpoint of taking a thermodynamically stable structure.

The near-infrared absorbing particles of the present invention are particles in which a specific metal M element is unevenly distributed on the surface of a particle made of A _{1 / n} CuPO ₄ crystallites with a specific metal M alkoxide. It becomes.
The near-infrared absorbing particles of the present invention are obtained by surface-treating particles composed of crystallites of A _{1 / n} CuPO ₄ with an alkoxide of a specific metal M. The presence of M element is confirmed by energy dispersive X-ray analysis. Confirmed by confirming.

The atomic number concentration ratio (Cu / M) between the M element and the Cu element determined by energy dispersive X-ray analysis is 2.0 to 10.6, and preferably 2.9 to 10.6. If Cu / M is 10.6 or less, the surface of the particles composed of crystallites of A _{1 / n} CuPO ₄ is sufficiently covered with a specific metal M compound (oxide, etc.), and moisture resistance Will improve. When Cu / M is 2.0 or more, the crystallite can sufficiently maintain the crystal structure of A _{1 / n} CuPO ₄ , and as a result, sufficient near infrared absorption characteristics can be exhibited.

  The specific metal M is selected from the group consisting of Al, Zr, Ti and Sn, since the compound (oxide or the like) has excellent moisture resistance and excellent transmittance in the visible light region. As the specific metal M, Al is particularly preferable because the compound (oxide or the like) is excellent in moisture resistance, chemical resistance, transmittance in the visible light region, and the like.

5-50 nm is preferable and, as for the magnitude | size of the crystallite in the near-infrared absorption particle | grains of this invention, 10-30 nm is more preferable. If the crystallite size is 5 nm or more, the crystallite can sufficiently maintain the crystal structure of A _{1 / n} CuPO ₄ , and as a result, sufficient near infrared absorption characteristics can be exhibited. If the crystallite size is 50 nm or less, the number-average aggregated particle diameter of the near-infrared absorbing particles can be kept small, and the haze of the dispersion, the resin composition, and the near-infrared absorbing coating film formed using them can be reduced. Is kept low.
The size of the crystallite is a value obtained by performing X-ray diffraction on the near-infrared absorbing particles in a powder state and calculating by the Scherrer method.

The number average aggregate particle diameter of the near infrared ray absorbing particles of the present invention is preferably 20 to 200 nm, more preferably 20 to 150 nm. If the number average aggregate particle diameter is 20 nm or more, the crystallite can sufficiently maintain the crystal structure of A _{1 / n} CuPO ₄ , and as a result, sufficient near infrared absorption characteristics can be exhibited. If the number average agglomerated particle diameter is 200 nm or less, the haze of the dispersion, the resin composition, and the near-infrared absorbing coating film formed using these will be low, that is, the transmittance will be high. It is suitable for use of a filter.
The number average agglomerated particle diameter is a value measured using a dynamic light scattering particle size distribution measuring apparatus for a particle diameter measurement dispersion in which near-infrared absorbing particles are dispersed in a dispersion medium.

The reflectance at a wavelength of 450 nm in the diffuse reflection spectrum of the near-infrared absorbing particles of the present invention is preferably 80% or more, and more preferably 81% or more.
High reflectivity of near infrared absorbing particles means that light absorption by near infrared absorbing particles is low, and low reflectivity of near infrared absorbing particles means that light absorption by near infrared absorbing particles is high. ing. The reflectance at a wavelength of 450 nm can be regarded as corresponding to the transmittance at a wavelength of 420 nm on the short wavelength side in the visible light region in the transmission spectrum of the film containing particles. That is, in the present invention, the absorption of light of the near-infrared absorbing particles is not performed using the reflectance of the wavelength 450 nm, which is a relatively small change amount of the diffuse reflection spectrum with respect to the wavelength, but the wavelength of 420 nm. Judging that there are few. That is, if the reflectance at a wavelength of 450 nm is 80% or more, the transmittance at a wavelength of 420 nm in the transmission spectrum of the film containing the particles is sufficiently high, and the near-infrared absorbing particles sufficiently absorb light in the visible light region. For example, it is suitable for a near infrared absorption filter of a camera.

In order to keep the near-infrared absorbing coating film low in haze, if the near-infrared absorbing particles are excessively pulverized to reduce the number-average aggregated particle diameter of the near-infrared absorbing particles, the crystallites constituting the particles are A _1. The crystal structure of _{/ n} CuPO ₄ cannot be sufficiently maintained, and the reflectance at a wavelength of 450 nm in the diffuse reflection spectrum tends to be small. Therefore, if the reflectance at a wavelength of 450 nm is 80% or more, the crystallites can sufficiently maintain the crystal structure of A _{1 / n} CuPO ₄ even if the number average aggregate diameter of the near infrared absorbing particles is 200 nm or less. It becomes a standard of being. Further, in order to sufficiently maintain the crystal structure of the A _{1 / n} CuPO ₄ crystallite, near-infrared absorbing particles having a sufficiently small number average agglomerated particle diameter can be obtained without excessive pulverization. The method for producing near-infrared absorbing particles described later (steps (a) to (c)) is suitable.

The reflectance change amount D represented by the following formula (2) of the near-infrared absorbing particles of the present invention is preferably −0.41 or less, more preferably −0.45 or less.
D (% / nm) = [ _R700 (%)- _R600 (%)] / [700 (nm) -600 (nm)] (2).
However, R ₇₀₀ is a reflectance at a wavelength of 700 nm in the diffuse reflection spectrum of the near-infrared absorbing particles, and R ₆₀₀ is a reflectance at a wavelength of 600 nm in the diffuse reflection spectrum of the near-infrared absorbing particles.

In diffuse reflection spectrum measurement of particles with light absorption, since the intensity of light absorption varies depending on the optical path length at the light absorption wavelength, a weak absorption band in the transmission spectrum of the film containing particles is observed relatively strongly in the diffuse reflection spectrum. . Therefore, the reflectance change rate calculation in this specification uses a reflectance value of 600 to 700 nm, which is a range in which the reflectance changes in the same manner as the transmittance change in the transmission spectrum of the film including particles.
When the reflectance change amount D is −0.41 or less, the transmittance change between wavelengths of 630 to 700 nm is sufficiently steep, and a near-infrared absorbing coating film formed using this is, for example, a camera It is suitable for the near infrared absorption filter.

19% or less is preferable and the reflectance of the wavelength of 715 nm in the diffuse reflection spectrum of the near-infrared absorbing particles of the present invention is more preferably 18% or less. If the reflectance at a wavelength of 715 nm is 19% or less, the transmittance in the near infrared region is sufficiently low.
The reflectance of the wavelength of 500 nm in the diffuse reflection spectrum of the near-infrared absorbing particles of the present invention is preferably 85% or more, and more preferably 86% or more. If the reflectance at a wavelength of 500 nm is 85% or more, the transmittance in the visible light region is sufficiently high.
The diffuse reflection spectrum is measured using a UV-visible spectrophotometer for powdered near-infrared absorbing particles.

In the near-infrared absorbing particles of the present invention, when the crystal structure other than A _{1 / n} CuPO ₄ , for example, A _{1 / n} Cu ₄ (PO ₄ ) ₃ increases, the transmittance changes between wavelengths of 630 to 700 nm. The near-infrared absorbing coating film formed by using this is slow and is not suitable for a near-infrared absorbing filter of a camera.
Therefore, it is necessary to have been identified by X-ray diffraction to be substantially composed of A _{1 / n} CuPO ₄ crystallites.

(Function and effect)
The near-infrared absorbing particles of the present invention described above are near-infrared absorbing particles mainly composed of crystallites of a compound represented by A _{1 / n} CuPO ₄ , and therefore have a transmittance in the visible light region. The transmittance of the film including the near infrared absorbing particles is steeply changed between the wavelengths of 630 to 700 nm.
In the near-infrared absorbing particles of the present invention described above, particles made of A _{1 / n} CuPO ₄ crystallites are surface-treated with a specific metal M alkoxide, or energy dispersive X Since the atomic number concentration ratio (Cu / M) of the M element and the Cu element obtained by the line analysis is 2.0 to 10.6, the moisture resistance is excellent.

<Method for producing near-infrared absorbing particles>
The manufacturing method of the near-infrared absorbing particles of the present invention is a method having the following step (d), and the following step (a) from the point that near-infrared absorbing particles having a sufficiently small number average aggregated particle diameter can be obtained. ) To (d) are preferred.
At (a) in a solvent, a salt containing ^{Cu 2+,} a salt or an organic material containing _PO ^{4 3-,} _PO ^{4 3-} molar ratio with respect to _{^{Cu 2+ (PO 4 3- / Cu}} 2+) 10-20 A step of obtaining a raw material slurry by dispersing a raw material powder obtained by mixing in the presence of ^{An +} in a dispersion medium.
(B) A step of introducing particles of the raw material slurry obtained in the step (a) into thermal plasma or flame and cooling the resulting product to obtain particles.
(C) A step of heat-treating the particles obtained in the step (b) at 300 to 700 ° C. to obtain particles made of A _{1 / n} CuPO ₄ crystallites.
(D) A step of surface-treating particles composed of crystallites of A _{1 / n} CuPO ₄ with an alkoxide of metal M selected from the group consisting of Al, Zr, Ti, and Sn.

(Process (a))
^Examples of salts containing Cu ²⁺ include copper (II) sulfate pentahydrate, copper (II) chloride dihydrate, copper (II) acetate monohydrate, copper (II) bromide, and copper (II) nitrate. And trihydrate.
Examples of the salt or organic substance containing PO ₄ ^3- include alkali metal phosphates, ammonium phosphates, alkaline earth metal phosphates, phosphoric acid, and the like.

Examples of alkali metal phosphate or alkaline earth metal phosphate include dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, disodium hydrogen phosphate dodecahydrate, sodium dihydrogen phosphate Examples thereof include dihydrate, trisodium phosphate dodecahydrate, lithium phosphate, calcium hydrogen phosphate, magnesium hydrogen phosphate trihydrate, and magnesium phosphate octahydrate.
Examples of the ammonium salt of phosphoric acid include diammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium ammonium hydrogen phosphate tetrahydrate, and ammonium phosphate trihydrate.

As a method for allowing ^{An +} to exist, a method using an alkali metal phosphate, an ammonium phosphate, an alkaline earth metal phosphate, or the like as a salt containing PO ₄ ^3- ; a salt containing Cu ²⁺ and PO _{4 When} a salt containing ^3- or an organic substance is mixed, a method of adding a salt containing ^{An +} is exemplified.
Salts containing ^{An +} include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal chlorides, alkaline earth metal chlorides, alkali metal bromides, alkaline earth metal bromides, Examples thereof include alkali metal nitrates, alkaline earth metal nitrates, alkali metal carbonates, alkaline earth metal carbonates, alkali metal sulfates, alkaline earth metal sulfates, and the like.

Mixing of the salt containing Cu ²⁺ and the salt or organic substance containing PO ₄ ^3- is performed in a solvent. As the solvent, a salt containing Cu ²⁺ and a salt containing PO ₄ ³⁻ or a solvent capable of dissolving an organic substance is preferable. When a salt containing ^{An +} is used, the solvent is preferably a solvent that can also dissolve a salt containing ^{An +} . As the solvent, water is particularly preferable.

Ratio of the salt or organic containing salt and _PO ^{4 3-} and containing Cu ²⁺ is, _PO ^{4 3-} molar ratio with respect to ^{_{Cu 2+ (PO 4 3- / Cu}} 2+) 10-20, preferably 12-18 and The ratio is as follows. If PO ₄ ³⁻ / Cu ²⁺ is 10 or more, even if A _{1 / n} Cu ₄ (PO ₄ ) ₃ is not by-produced or by-produced in the step (b), the amount of crystallites is A _{1. Since} the crystal structure of _{/ n} CuPO ₄ can be sufficiently maintained, near-infrared absorbing particles in which the change in transmittance between wavelengths of 630 to 700 nm is sufficiently steep are obtained. If PO ₄ ³⁻ / Cu ²⁺ is 20 or less, impurities other than A _{1 / n} CuPO ₄ are not by-produced in the step (b), or even if they are by-produced, the amount of crystallites is A _{1 / n.} Since the crystal structure of CuPO ₄ is sufficiently maintained, near-infrared absorbing particles in which the change in transmittance between wavelengths of 630 to 700 nm is sufficiently steep can be obtained.

Temperature at the time of mixing the salt or organic containing salt and _PO ^{4 3-} and containing Cu ²⁺ is preferably 10 to 95 ° C., and more preferably from 15 to 40 ° C.. If the temperature is too high, the solute is concentrated by evaporation of the solvent, and impurities other than the target product may be mixed. If the temperature is too low, the reaction rate becomes slow and the reaction time becomes long.

In a solvent, a salt containing ^{Cu 2+,} a salt or an organic material containing _PO ^{4 3-,} _PO ^{4 3-} molar ratio with respect to _{^{Cu 2+ (PO 4 3- / Cu}} 2+) to become 10 to 20 The raw material powder obtained by mixing in a small proportion and in the presence of ^{An +} is solid-liquid separated and dried as necessary, and dispersed in a dispersion medium to obtain a raw material slurry.

  Examples of the dispersion medium for the raw slurry include water, alcohol, ketone, ether, ester, aldehyde, amine, aliphatic hydrocarbon, alicyclic hydrocarbon, and aromatic hydrocarbon. A dispersion medium may be used individually by 1 type, and may use 2 or more types together. As the dispersion medium, alcohols such as methanol, ethanol, and isopropanol are preferable because they are easy to handle and contain an oxygen atom that becomes an oxygen source when passing through thermal plasma.

  Since the particle diameter of the near-infrared absorbing particles obtained in the step (b) varies depending on the solid content concentration in the raw material slurry, it is necessary to adjust the solid content concentration of the raw material slurry as necessary. That is, the higher the solid content concentration in the raw slurry, the higher the crystal nucleus concentration when passing through the thermal plasma, the crystal growth occurs, and the near infrared absorbing particles having a large particle diameter can be obtained. The lower the solid content concentration in the raw slurry, the lower the crystal nucleus concentration when passing through the thermal plasma, the crystal growth is suppressed, and the near-infrared absorbing particles having a small particle diameter can be obtained. The amount of the dispersion medium is preferably 50 to 95% by mass in the dispersion (100% by mass).

  The raw material slurry can be prepared by mixing raw material powder, a dispersion medium, and if necessary, zirconia beads and the like, and stirring with a rotation / revolution mixer, a bead mill, a planetary mill, an ultrasonic homogenizer or the like. In order to obtain a uniform near-infrared absorbing particle having a small particle size, the particle size of the raw material powder in the raw material slurry needs to be small and uniform. Stirring may be performed continuously or intermittently.

(Process (b))
Methods for introducing raw slurry into thermal plasma or flame and cooling the resulting product to obtain particles are described in JP-A-2005-170760, JP-A-4420690, and the like.
Therefore, except using the raw material slurry obtained in step (a) as the raw material slurry, using the apparatus described in Japanese Patent Application Laid-Open No. 2005-170760, Japanese Patent No. 4420690, etc., Japanese Patent Application Laid-Open No. 2005-170760, The particles may be produced by appropriately changing the conditions described in Japanese Patent No. 4420690.

  For example, plasma gas (argon gas, etc.) is supplied into a plasma torch, and while generating thermal plasma in the plasma torch, the raw material slurry is sprayed together with a carrier gas (oxygen gas, etc.) from a nozzle provided in the plasma torch. By doing so, droplets of the raw slurry are introduced into the thermal plasma. While the solvent of the raw material slurry is evaporated in the thermal plasma, the raw material contained in the raw material slurry is reacted, and the product generated from the thermal plasma is moved to a chamber adjacent to the lower part of the plasma torch. The product from the thermal plasma is crystallized by quenching in the chamber to produce particles.

(Process (c))
The particles obtained in the step (b) may have oxygen defects in the crystal structure. Since particles having an oxygen defect in the crystal structure have a low transmittance in the visible light region, it is preferable to perform heat treatment to reduce the oxygen defect in the crystal structure.

The heat treatment temperature is 300 to 700 ° C, preferably 300 to 500 ° C. If the heat treatment temperature is 300 ° C. or higher, oxygen defects in the crystal structure can be sufficiently reduced. If heat processing temperature is 700 degrees C or less, decomposition | disassembly by a heat | fever can be suppressed.
The heat treatment time is preferably 0.5 to 300 minutes, more preferably 1 to 10 minutes. If the heat treatment time is 0.5 minutes or more, oxygen defects in the crystal structure can be sufficiently reduced. If the heat treatment time is 300 minutes or less, crystal growth due to the heat treatment can be suppressed.
When an infrared image furnace is used, rapid heating and rapid cooling are possible, which is effective in suppressing crystal growth. A rotary kiln furnace that can be fired while flowing particles is also effective in suppressing crystal growth.

(Process (d))
As a method for surface-treating particles composed of crystallites of A _{1 / n} CuPO ₄ with an alkoxide of a specific metal M, a microwave or the like is not required, and the present invention is simple and low-cost. In view of the ability to produce infrared absorbing particles, the following method is preferred.
A alkoxide of a specific metal M is added to a dispersion obtained by dispersing particles composed of crystallites of A _{1 / n} CuPO _{4 in} a dispersion medium, and after stirring for a predetermined time, the dispersion medium is removed and unreacted as necessary. A method in which the alkoxide of a specific metal M is removed, and then the particles are dried by heating and, if necessary, fired.

  Examples of the dispersion medium include water, alcohol (methanol, ethanol, isopropanol, etc.), ketone (acetone, methyl ethyl ketone, etc.), ether (tetrahydrofuran, 1,4-dioxane, etc.), ester (ethyl acetate, methyl acetate, etc.), glycol ether ( Ethylene glycol monoalkyl ether), nitrogen-containing compounds (N, N-dimethylacetamide, N, N-dimethylformamide, etc.), sulfur-containing compounds (dimethyl sulfoxide, etc.) and the like.

The concentration of the particles composed of A _{1 / n} CuPO ₄ crystallites in the dispersion is preferably 0.1 to 40% by mass, and more preferably 0.5 to 20% by mass in the dispersion (100% by mass). If the concentration of the particles is 0.1% by mass or more, the production efficiency of near-infrared absorbing particles will be good. If the concentration of the particles is 40% by mass or less, the particles are difficult to aggregate.

  Specific metal M alkoxides include aluminum trimethoxide, aluminum triethoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum tri-sec-butoxide, aluminum tri-tert-butoxide, monobutoxyaluminum dioxide. Aluminum alkoxides such as isopyrate and aluminum phenoxide; titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetra-n-butoxide, titanium tetra-tert-butoxide, titanium tetra-sec-butoxide, titanium tetra Isobutoxide, titanium tetra-2-ethylhexoxide, titanium lactate, titanium tetra (methoxypropoxide) ), Titanium tetra (methylphenoxide), titanium tetra-n-nonyloxide, titanium tetrastearyloxide, titanium bis (triethanolamine) -diisopropoxide, etc .; zirconium tetramethoxide, zirconium tetraethoxide, Zirconium tetraisopropoxide, zirconium tetra-n-propoxide, zirconium tetra-n-butoxide, zirconium tetra-sec-butoxide, zirconium tetra-tert-butoxide, zirconium tetraisobutoxide, zirconium tetra-2-ethylhexoxide, Zirconium alkoxides such as zirconium tetra (2-methyl-2-butoxide); antimony tetraethoxide, antimonte trisopro Kishido, antimony alkoxides such as antimony tetra -n- butoxide.

The amount of the alkoxide of the specific metal M is preferably 50 to 1000 parts by mass and more preferably 100 to 400 parts by mass with respect to 100 parts by mass of the particles made of crystallites of A _{1 / n} CuPO ₄ . If the amount of the alkoxide of the specific metal M is 50 parts by mass or more, the surface of the particles made of crystallites of A _{1 / n} CuPO ₄ is sufficiently covered with the specific metal M compound (oxide etc.). And moisture resistance is improved. If the amount of the alkoxide of the specific metal M is 1000 parts by mass or less, the crystallite can sufficiently maintain the crystal structure of A _{1 / n} CuPO ₄ , and as a result, sufficient near infrared absorption characteristics can be exhibited.

The stirring time is preferably 1 to 72 hours, and more preferably 5 to 48 hours.
The temperature during stirring is preferably from room temperature to 80 ° C, more preferably from room temperature to 50 ° C.

Examples of the method for removing the dispersion medium include a method by centrifugation, a method by filtration, and the like.
Examples of the method for removing the unreacted specific metal M alkoxide include a method in which particles are dispersed again in a dispersion medium, subjected to ultrasonic treatment, and then the dispersion medium is removed together with the unreacted specific metal M alkoxide.

The drying time is preferably 0.5 to 24 hours, and more preferably 1 to 5 hours.
The drying temperature is preferably 80 to 200 ° C, more preferably 100 to 150 ° C.

By performing the firing, the moisture resistance of the near-infrared absorbing particles is further improved.
The firing time is preferably 0.5 to 300 minutes, more preferably 0.5 to 10 minutes.
The firing temperature is preferably 200 to 700 ° C, more preferably 300 to 500 ° C.

(Other surface treatment)
The near-infrared absorbing particles obtained as described above are further subjected to surface treatment by a known method for the purpose of improving weather resistance, acid resistance, water resistance, etc. and improving compatibility with the binder resin by surface modification. May be.
As a surface treatment method, a surface treatment agent or a surface treatment agent diluted with a solvent is added to a dispersion containing near-infrared absorbing particles, the mixture is stirred and treated, and then the solvent is removed and dried (wet method). ); A method (dry method) in which a surface treatment agent diluted with a surface treatment agent or a solvent is jetted with dry air or nitrogen gas and then dried while stirring the near infrared absorbing particles (dry method).
Examples of the surface treatment agent include a surfactant and a coupling agent.

(Function and effect)
In the method for producing near-infrared absorbing particles of the present invention described above, since the particles made of A _{1 / n} CuPO ₄ crystallites are surface-treated with a specific metal M alkoxide in the step (d), It is possible to produce near-infrared absorbing particles having a high transmittance in the visible light region, a low transmittance in the near-infrared region, a sharp change in transmittance between wavelengths of 630 to 700 nm, and excellent moisture resistance.

  In addition, in the step (b), the raw material slurry passes through thermal plasma or flame, so that the raw material particles contained in the raw material slurry are rapidly heated and vaporized to an atomic state, and then rapidly cooled. Therefore, particle growth due to bonding between adjacent crystal nuclei is suppressed, and a product having a crystallite size of 5 to 50 nm obtained from X-ray diffraction can be easily obtained. Further, by subjecting the product to a heat treatment in step (c), particle growth due to the heat treatment is suppressed, and particles having few structural defects and high transmittance in the visible light region are obtained. That is, the number average aggregate particle diameter of the particles is 20 to 200 nm without excessive pulverization.

  On the other hand, when not using the method which has process (a)-(c), in order to make the number average aggregated particle diameter of a near-infrared absorption particle 20-200 nm, processes, such as wet grinding | pulverization, are required. However, an excessive pulverization treatment may partially destroy the crystal structure of the particles and reduce the transmittance in the visible light region. That is, when the method having the steps (a) to (c) is not used, an excessive pulverization process is required, and therefore the number-average aggregated particle diameter is small, but the near-infrared absorbing particles having a low visible light region transmittance There is a case. In addition, pulverization for as long as possible is preferable because pulverization for a long time reduces productivity efficiency.

From the above, in the method having the steps (a) to (c), the crystallite size obtained from X-ray diffraction is 5 to 50 nm without excessive pulverization, and the number average aggregated particles Particles made of A _{1 / n} CuPO ₄ crystallites having a diameter of 20 to 200 nm can be produced.

<Application>
The near-infrared absorbing particles of the present invention may be dispersed in a dispersion medium and used as a dispersion, or may be dispersed in a resin and used as a resin composition.

<Dispersion>
The dispersion liquid of the present invention includes a dispersion medium and the near-infrared absorbing particles of the present invention dispersed in the dispersion medium, and optionally includes a dispersant, a binder resin, and other light absorbing materials.
The amount of near-infrared absorbing particles is preferably 5 to 50% by mass in the dispersion (100% by mass). If the amount of near-infrared absorbing particles is 5% by mass or more, sufficient near-infrared absorbing characteristics can be exhibited. If the amount of near-infrared absorbing particles is 50% by mass or less, the transmittance in the visible light region can be maintained high.

(Dispersion medium)
Examples of the dispersion medium include water, alcohol, ketone, ether, ester, aldehyde, amine, aliphatic hydrocarbon, alicyclic hydrocarbon, and aromatic hydrocarbon. A dispersion medium may be used individually by 1 type, and may use 2 or more types together. The amount of the dispersion medium is preferably 50 to 95% by mass in the dispersion (100% by mass) from the viewpoint of maintaining the dispersibility of the near-infrared absorbing particles.

(Dispersant)
Dispersing agents that have a modification effect on the surface of near-infrared absorbing particles, such as surfactants, silanes, silicone resins, titanate coupling agents, aluminum coupling agents, zircoaluminate couplings Agents and the like.

  Surfactants include anionic surfactants (special polycarboxylic acid type polymer surfactants, alkyl phosphate esters, etc.), nonionic surfactants (polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxy Ethylene carboxylic acid esters, sorbitan higher carboxylic acid esters, etc.), cationic surfactants (polyoxyethylene alkylamine carboxylic acid esters, alkylamines, alkylammonium salts, etc.), and amphoteric surfactants (higher alkylbetaines, etc.). .

Examples of silane include a silane coupling agent, chlorosilane, alkoxysilane, and silazane. Examples of the silane coupling agent include alkoxysilanes having a functional group (glycidoxy group, vinyl group, amino group, alkenyl group, epoxy group, mercapto group, chloro group, ammonium group, acryloxy group, methacryloxy group, etc.).
Examples of the silicone resin include methyl silicone resin and methylphenyl silicone resin.

Examples of titanate coupling agents include those having an acyloxy group, phosphoxy group, pyrophosphoxy group, sulfoxy group, aryloxy group, and the like.
Examples of the aluminum coupling agent include acetoalkoxyaluminum diisopropylate.
Examples of the zircoaluminate coupling agent include those having an amino group, a mercapto group, an alkyl group, an alkenyl group, and the like.

  Although the quantity of a dispersing agent is based also on the kind of dispersing agent, 0.5-10 mass% is preferable among dispersion liquids (100 mass%). If the amount of the dispersant is within the above range, the dispersibility of the near-infrared absorbing particles becomes good, the transparency is not impaired, and the near-infrared absorbing particles are prevented from settling with time.

(Binder resin)
Binder resins include thermoplastic resins (polyester resins, acrylic resins, polycarbonate resins, polyamide resins, alkyd resins, etc.), thermosetting resins (epoxy resins, thermosetting acrylic resins, silsesquioxy). Sun resin). When the near-infrared absorbing coating film needs transparency, the binder resin is preferably an acrylic resin or a polyester resin. As for the quantity of binder resin, 10-90 mass% is preferable among solid content (100 mass%) of a dispersion liquid.

(Other light absorbers)
Examples of other light absorbing materials include ultraviolet absorbing materials and other infrared absorbing materials.
Examples of the ultraviolet absorber include zinc oxide, titanium oxide, cerium oxide, zirconium oxide, mica, kaolin, and sericite.
Examples of other infrared absorbing materials include ITO (Indium Tin Oxide), ATO (Antimony doped Tin Oxide), and the like. ITO has a high transmittance in the visible light region and has a wide range of electromagnetic wave absorptivity including a radio wave region exceeding 1100 nm. Therefore, ITO is particularly preferable when radio wave shielding is required.
The number average aggregated particle diameter of the other light absorbing material is preferably 100 nm or less from the viewpoint of transparency.

(Preparation of dispersion)
The dispersion of the present invention is mixed with the near-infrared absorbing particles of the present invention, a dispersion medium, a dispersant, a binder resin, etc., if necessary, and stirred by a rotation / revolution mixer, a bead mill, a planetary mill, an ultrasonic homogenizer, or the like. Can be prepared. In order to ensure high transparency, it is necessary to sufficiently stir. Stirring may be performed continuously or intermittently.

(Function and effect)
In the dispersion of the present invention described above, since the near-infrared absorbing particles of the present invention are dispersed in a dispersion medium, the transmittance in the visible light region is high, the transmittance in the near-infrared region is low, It is useful for forming a near-infrared absorbing coating film having a sharp change in transmittance between wavelengths of 630 and 700 nm and excellent moisture resistance.

<Resin composition>
The resin composition of the present invention includes a resin and the near-infrared absorbing particles of the present invention dispersed in the resin, and optionally includes a dispersant and other light absorbing materials.
The amount of near-infrared absorbing particles is preferably 10 to 60% by mass in the resin composition (100% by mass). If the amount of near-infrared absorbing particles is 10% by mass or more, sufficient near-infrared absorbing characteristics can be expressed. When the amount of the near-infrared absorbing particles is 60% by mass or less, the transmittance in the visible light region can be maintained high.

(resin)
Resins include thermoplastic resins (polyester resins, acrylic resins, polycarbonate resins, polyamide resins, alkyd resins, etc.), thermosetting resins (epoxy resins, thermosetting acrylic resins, silsesquioxanes). Resin). When the near-infrared absorbing coating film needs transparency, the resin is preferably an acrylic resin or a polyester resin. The amount of the resin is preferably 40 to 90% by mass in the resin composition (100% by mass).

(Dispersant)
As the dispersant, those having a modification effect on the surface of the near infrared absorbing particles, for example, the above-mentioned surfactant, silane, silicone resin, titanate coupling agent, aluminum coupling agent, zircoaluminate type. A coupling agent etc. are mentioned.

(Other light absorbers)
Examples of the other light absorbing material include the above-described ultraviolet absorbing material and other infrared absorbing materials.

(Preparation of resin composition)
The resin composition of the present invention is a mixture of the near-infrared absorbing particles of the present invention, a resin, and a solvent and a dispersing agent as required, and a rotation / revolution mixer, a bead mill, a planetary mill, a mixer-type kneader, and a three-roll It can prepare by kneading | mixing by etc. In order to ensure high transparency, it is necessary to knead sufficiently. Kneading may be performed continuously or intermittently.

(Function and effect)
In the resin composition of the present invention described above, since the near-infrared absorbing particles of the present invention are dispersed in the resin, the transmittance in the visible light region is high, the transmittance in the near-infrared region is low, It is useful for the formation of a near-infrared absorbing coating film and a near-infrared absorbing article having a sharp change in transmittance between wavelengths of 630 to 700 nm and excellent in moisture resistance.

<Articles with near infrared absorption coating>
The article having the near infrared absorbing coating film of the present invention has a near infrared absorbing coating film containing the near infrared absorbing particles of the present invention on the surface of the substrate.
The article having the near-infrared absorbing coating film of the present invention is required by applying the dispersion liquid of the present invention to the surface of the substrate and drying, or applying the resin composition of the present invention to the surface of the substrate. Can be produced by curing.

Examples of the article having a near-infrared absorbing coating include a near-infrared filter for a camera, an optical filter for a plasma display, a glass window for a vehicle (such as an automobile), a lamp, and the like.
The shape of the substrate may be a film shape or a plate shape. Examples of the material for the base material include glass, polyethylene terephthalate (PET), acrylic resin, urethane resin, polycarbonate, polyethylene, ethylene vinyl acetate copolymer, vinyl chloride, and fluororesin. From the viewpoint of transparency and heat resistance Glass is preferred.

The transmittance change amount D ′ represented by the following formula (3) of the near-infrared absorbing coating film is preferably −0.36 or less, and more preferably −0.37 or less.
D ′ (% / nm) = [T ₇₀₀ (%) − T ₆₃₀ (%)] / [700 (nm) −630 (nm)] (3).
_{However, T 700} is the transmittance at a wavelength of 700nm near infrared absorbing _{coating, T 630} is a transmittance at a wavelength of 630nm near infrared absorbing coating.

When the transmittance change amount D ′ is −0.36 or less, the transmittance change between wavelengths of 630 to 700 nm is sufficiently steep, which is suitable for a near-infrared absorption filter of a camera.
The transmittance of the near-infrared absorbing coating film at a wavelength of 600 nm is preferably 70% or more, and more preferably 75% or more. If the transmittance at a wavelength of 600 nm is 70% or more, red light absorption is sufficiently suppressed, which is suitable for a near-infrared absorption filter of a camera.
The transmittance of the near-infrared absorbing coating film at a wavelength of 450 nm is preferably 75% or more, and more preferably 80% or more. If the transmittance at a wavelength of 450 nm is 75% or more, light absorption in the visible light region is small, which is suitable for a near infrared absorption filter of a camera.

The transmittance of the near-infrared absorbing coating film at a wavelength of 715 nm is preferably 10% or less, and more preferably 5% or less.
The transmittance of the near-infrared absorbing coating film at a wavelength of 500 nm is preferably 80% or more, and more preferably 85% or more.
The transmittance of the near infrared absorbing coating film is measured as follows.
When the resin is a polyester-based resin, a dispersion containing 31% by mass of near-infrared absorbing particles and 69% by mass of resin as a solid content is applied to a glass substrate to form a near-infrared absorbing coating film having a thickness of 70 μm. When the resin is an acrylic resin, a dispersion containing 50% by mass of near-infrared absorbing particles and 50% by mass of resin as a solid content is applied to a glass substrate to form a near-infrared absorbing coating film having a thickness of 20 μm. The transmittance of the near-infrared absorbing coating film is measured using an ultraviolet-visible spectrophotometer.

<Near-infrared absorbing article>
The near-infrared absorbing article of the present invention includes the near-infrared absorbing particles of the present invention.
The near-infrared absorbing article of the present invention can be produced by molding the resin composition of the present invention by a known molding method.
Examples of the molding method include an extrusion molding method, an injection molding method, a calendar method, and a casting method.
Examples of the shape of the article include a film shape, a plate shape, and a coating film on the substrate.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
Examples 1 to 8 are examples, and example 9 is a comparative example.

(Energy dispersive X-ray analysis)
Elementary analysis was performed on the near-infrared absorbing particles in a powder state using an energy dispersive X-ray analyzer (manufactured by HORIBA, EMAX ENERGY EX-250).

(X-ray diffraction)
About the near-infrared absorption particle | grains of a powder state, the X-ray-diffraction measurement was performed using the X-ray-diffraction apparatus (the RIGAKU company make, RINT-TTR-III), and the crystal structure was identified. Further, the size of the crystallite was obtained by calculation according to Scherrer's method for reflection at 2θ = 14 °.

(Number average agglomerated particle size)
About a dispersion for particle size measurement (solid content concentration: 5% by mass) in which near-infrared absorbing particles are dispersed in water, a dynamic light scattering particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., Microtrac Ultrafine Particle Size Analyzer UPA-) 150) was used to measure the number average aggregate particle size.

(Reflectance)
About the near-infrared absorption particle | grains of a powder state, the diffuse reflection spectrum (reflectance) was measured using the ultraviolet visible spectrophotometer (the Hitachi High-Technologies company make, U-4100 type). Barium sulfate was used as the baseline.

(Transmittance)
About the near-infrared absorption coating film, the transmission spectrum (transmittance) was measured using the ultraviolet visible spectrophotometer (Hitachi High-Technologies company make, U-4100 type).

(Haze)
About the near-infrared absorption coating film used for the transmittance | permeability measurement, the haze was measured using the haze meter (the BYK Gardner company make, gaze-gard plus).

[Example 1]
Step (a):
To 500 g of 52 mass% dipotassium hydrogen phosphate (made by Junsei Kagaku), 500 g of 5 mass% copper sulfate pentahydrate (made by Junsei Chemical) aqueous solution is added with stirring and stirred at room temperature for 5 hours or more. As a result, a light blue reaction solution was obtained. Table 4 shows PO ₄ ³⁻ / Cu ²⁺ (molar ratio) during the reaction. The light blue reaction solution was subjected to solid-liquid separation using a desktop centrifuge to obtain a light blue precipitate. The light blue sediment was dispersed in acetone, subjected to ultrasonic treatment, and then subjected to solid-liquid separation using a desktop centrifuge. The obtained precipitate was dried at 150 ° C. for 2 hours and then dispersed in ethanol to obtain a raw material slurry.

Step (b):
Using the apparatus described in JP-A-2005-170760, the raw material slurry obtained in step (a) is introduced into the thermal plasma in the plasma torch, and the resulting product is cooled in the chamber to dark green. Obtained particles.

Step (c):
The particles obtained in the step (b) were transferred to a flat plate and heat-treated at 500 ° C. for 5 minutes in the air to obtain light blue-green particles. An infrared image furnace was used for the heat treatment.

Near-infrared absorbing particles before surface treatment:
X-ray diffraction was measured for the near-infrared absorbing particles before the surface treatment obtained in the step (c) of Example 1. The results are shown in FIG. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ could be confirmed, and it was identified that the particles were particles substantially composed of crystallites of KCuPO ₄ .

Step (d):
3 g of the near-infrared absorbing particles before the surface treatment obtained in the step (c) was mixed with 40 g of 2-propanol, and a dispersion was prepared by ultrasonic treatment. After adding 3 g of aluminum triethoxide to the dispersion and stirring for 24 hours at room temperature, the solvent was removed by centrifugation. 2-Propanol was added to the resulting sediment, and ultrasonic treatment was performed to dissolve unreacted aluminum ethoxide contained in the sediment, and then the solvent was removed by centrifugation. The obtained sediment was put in a crucible and heat-dried in a thermostatic bath at 150 ° C. for 2 hours to obtain surface-treated near-infrared absorbing particles.

Near-infrared absorbing particles after surface treatment:
Energy dispersive X-ray analysis was performed on the near-infrared absorbing particles after the surface treatment. The results are shown in Table 1. From the result of EDX, the atomic number concentration ratio of Cu / Al was 8.5, the aluminum element was detected, and the addition of the aluminum element in the step (d) was shown.

Moreover, X-ray diffraction was measured about the near-infrared absorption particle | grains after surface treatment. The results are shown in FIG. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ was confirmed, and it was identified that the particle was a near-infrared absorbing particle substantially composed of a crystallite of KCuPO ₄ even after passing through the step (d). . That is, the near-infrared absorbing particles that have undergone step (d) are near-infrared-absorbing particles having a central portion made of crystallites of KCuPO ₄ and are presumed to have a crystal structure close to a core-shell structure in which aluminum elements are unevenly distributed on the surface. Is done. The crystallite size is shown in Table 2.
Further, a dispersion for measuring the particle size of near-infrared absorbing particles after the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 2.
Further, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the surface treatment was measured. The results are shown in Table 2. The diffuse reflection spectrum is shown by a solid line in FIG.

Moist heat resistance test:
The near-infrared absorbing particles after the surface treatment were put in a crucible and subjected to a moisture and heat resistance test. As a tester, a thermo-hygrostat (manufactured by ESPEC Co., Ltd., a small environmental tester LH-113) was used. The test conditions were set to 85 ° C. and relative humidity 85%, and the tester was exposed for 1000 hours. X-ray diffraction was measured for the near-infrared absorbing particles after the test. The results are shown in FIG. The result of X-ray diffraction agrees with the X-ray diffraction of the near-infrared absorbing particles before the test shown in FIG. 2, indicating that the crystal structure of KCuPO ₄ is retained after the test.
Moreover, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the test was measured. The results are shown by broken lines in FIG. The result of the diffuse reflection spectrum agrees with the diffuse reflection spectrum of the near-infrared absorbing particles before the test shown by a solid line in FIG. 4, indicating that the near-infrared absorption characteristics are maintained even after the test.

Dispersion, coating:
The near-infrared absorbing particles after the surface treatment and a 25% by mass cyclohexanone solution of polyester resin (manufactured by Osaka Gas Chemical Co., Ltd., OKP4HT), solid content of 31% by mass of the near-infrared absorbing particles and 69% by mass of the polyester-based resin The mixture was mixed at such a ratio that it was stirred with a rotating / revolving mixer to obtain a dispersion. The dispersion was applied to a glass substrate, dried with a nitrogen-substituted desiccator for 15 minutes or more, and heated at 150 ° C. for 10 minutes to form a near-infrared absorbing coating film having a thickness of 70 μm.

  The transmittance and haze of the near infrared absorbing coating film were measured. Moreover, the heat-and-moisture resistance test was done. As a tester, a thermo-hygrostat (manufactured by ESPEC Co., Ltd., a small environmental tester LH-113) was used. The test conditions were 85 ° C. and relative humidity 85%, and exposure was performed for 100 hours. The transmittance and haze of the near-infrared absorbing coating film after the test were measured and compared with those before the test. The results are shown in Table 2. In addition, the following was employ | adopted as a comparative evaluation method.

About the transmittance | permeability spectrum of the near-infrared absorptive coating film after 100-hour humidity-heat test, (100- (800 nm transmittance | permeability (%) of the near-infrared absorptive coating after a test)) (100- (before test When the value obtained by dividing the near-infrared absorbing coating film by 800 nm transmittance (%) is 0.95 or more, it is evaluated as ◯. When the above value is 0.90 or more and less than 0.95, Δ When the above value was less than 0.90, it was marked as x.
For the haze of the near-infrared absorbing coating film after 100 hours of the wet heat resistance test, (100- (haze (%) of the near-infrared absorbing coating film after the test)) (100- (near-infrared absorbing coating film before the test) When the value divided by haze (%) is 0.95 or more, the result is ◯, and when the value is 0.90 or more and less than 0.95, the result is Δ. When it was less than 90, it was set as x.

[Example 2]
The near-infrared absorbing particles surface-treated in the same manner as in Example 1 were obtained except that the near-infrared absorbing particles obtained in the step (d) of Example 1 were further baked at 500 ° C. for 1 minute. The obtained near-infrared absorbing particles were subjected to energy dispersive X-ray analysis. Table 2 shows Cu / Al.
Further, X-ray diffraction was measured for the particles after the surface treatment. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ was confirmed, and it was identified that the particle was a near-infrared absorbing particle substantially composed of a crystallite of KCuPO ₄ even after passing through the step (d). . The crystallite size is shown in Table 2.
Further, a dispersion for measuring the particle size of near-infrared absorbing particles after the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 2.
Further, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the surface treatment was measured. The results are shown in Table 2.

Moist heat resistance test:
The near-infrared absorbing particles after the surface treatment were put in a crucible, and a moisture and heat resistance test was conducted in the same manner as in Example 1. About the near-infrared absorbing particles after the test, X-ray diffraction and diffuse reflection spectrum (reflectance) were measured, and it was confirmed that the near-infrared absorption characteristics were maintained even after the wet heat resistance test.

Dispersion, coating:
A near-infrared absorbing coating film was formed in the same manner as in Example 1 using the near-infrared absorbing particles after the surface treatment. The near-infrared absorbing coating film was subjected to a heat and moisture resistance test in the same manner as in Example 1, and comparatively evaluated for changes in transmittance and haze before and after the test. The results are shown in Table 2.

[Example 3]
Near-infrared absorbing particles surface-treated were obtained in the same manner as in Example 1 except that the stirring time in the step (d) was 5 hours. The obtained near-infrared absorbing particles were subjected to energy dispersive X-ray analysis. Table 2 shows Cu / Al.
Further, X-ray diffraction was measured for the particles after the surface treatment. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ was confirmed, and it was identified that the particle was a near-infrared absorbing particle substantially composed of a crystallite of KCuPO ₄ even after passing through the step (d). . The crystallite size is shown in Table 2.
Further, a dispersion for measuring the particle size of near-infrared absorbing particles after the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 2.
Further, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the surface treatment was measured. The results are shown in Table 2.

Moist heat resistance test:
The near-infrared absorbing particles after the surface treatment were put in a crucible, and a moisture and heat resistance test was conducted in the same manner as in Example 1. About the near-infrared absorbing particles after the test, X-ray diffraction and diffuse reflection spectrum (reflectance) were measured, and it was confirmed that the near-infrared absorption characteristics were maintained even after the wet heat resistance test.

Dispersion, coating:
A near-infrared absorbing coating film was formed in the same manner as in Example 1 using the near-infrared absorbing particles after the surface treatment. The near-infrared absorbing coating film was subjected to a heat and moisture resistance test in the same manner as in Example 1, and comparatively evaluated for changes in transmittance and haze before and after the test. The results are shown in Table 2.

[Example 4]
Except that the stirring time in the step (d) was 1 hour, near-infrared absorbing particles surface-treated in the same manner as in Example 1 were obtained. The obtained near-infrared absorbing particles were subjected to energy dispersive X-ray analysis. Table 3 shows Cu / Al.
Further, X-ray diffraction was measured for the particles after the surface treatment. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ was confirmed, and it was identified that the particle was a near-infrared absorbing particle substantially composed of a crystallite of KCuPO ₄ even after passing through the step (d). . The crystallite size is shown in Table 3.
Further, a dispersion for measuring the particle size of near-infrared absorbing particles after the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 3.
Further, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the surface treatment was measured. The results are shown in Table 3.

Moist heat resistance test:
The near-infrared absorbing particles after the surface treatment were put in a crucible, and a moisture and heat resistance test was conducted in the same manner as in Example 1. About the near-infrared absorbing particles after the test, X-ray diffraction and diffuse reflection spectrum (reflectance) were measured, and it was confirmed that the near-infrared absorption characteristics were maintained even after the wet heat resistance test.

Dispersion, coating:
A near-infrared absorbing coating film was formed in the same manner as in Example 1 using the near-infrared absorbing particles after the surface treatment. The near-infrared absorbing coating film was subjected to a heat and moisture resistance test in the same manner as in Example 1, and comparatively evaluated for changes in transmittance and haze before and after the test. The results are shown in Table 3.

[Example 5]
Surface-treated near-infrared absorbing particles were obtained in the same manner as in Example 1 except that the stirring time in the step (d) was 72 hours. The obtained near-infrared absorbing particles were subjected to energy dispersive X-ray analysis. Table 3 shows Cu / Al.
Further, X-ray diffraction was measured for the particles after the surface treatment. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ was confirmed, and it was identified that the particle was a near-infrared absorbing particle substantially composed of a crystallite of KCuPO ₄ even after passing through the step (d). . The crystallite size is shown in Table 3.
Further, a dispersion for measuring the particle size of near-infrared absorbing particles after the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 3.
Further, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the surface treatment was measured. The results are shown in Table 3.

Moist heat resistance test:
The near-infrared absorbing particles after the surface treatment were put in a crucible, and a moisture and heat resistance test was conducted in the same manner as in Example 1. About the near-infrared absorbing particles after the test, X-ray diffraction and diffuse reflection spectrum (reflectance) were measured, and it was confirmed that the near-infrared absorption characteristics were maintained even after the wet heat resistance test.

Dispersion, coating:
A near-infrared absorbing coating film was formed in the same manner as in Example 1 using the near-infrared absorbing particles after the surface treatment. The near-infrared absorbing coating film was subjected to a heat and moisture resistance test in the same manner as in Example 1, and comparatively evaluated for changes in transmittance and haze before and after the test. The results are shown in Table 3.

[Example 6]
Near-infrared absorbing particles surface-treated in the same manner as in Example 1 were obtained except that the aluminum triethoxide in the step (d) was changed to aluminum tri-sec-butoxide. The obtained near-infrared absorbing particles were subjected to energy dispersive X-ray analysis. Table 3 shows Cu / Al.
Further, X-ray diffraction was measured for the particles after the surface treatment. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ was confirmed, and it was identified that the particle was a near-infrared absorbing particle substantially composed of a crystallite of KCuPO ₄ even after passing through the step (d). . The crystallite size is shown in Table 3.
Further, a dispersion for measuring the particle size of near-infrared absorbing particles after the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 3.
Further, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the surface treatment was measured. The results are shown in Table 3.

Moist heat resistance test:
The near-infrared absorbing particles after the surface treatment were put in a crucible, and a moisture and heat resistance test was conducted in the same manner as in Example 1. About the near-infrared absorbing particles after the test, X-ray diffraction and diffuse reflection spectrum (reflectance) were measured, and it was confirmed that the near-infrared absorption characteristics were maintained even after the wet heat resistance test.

Dispersion, coating:
A near-infrared absorbing coating film was formed in the same manner as in Example 1 using the near-infrared absorbing particles after the surface treatment. The near-infrared absorbing coating film was subjected to a heat and moisture resistance test in the same manner as in Example 1, and comparatively evaluated for changes in transmittance and haze before and after the test. The results are shown in Table 3.

[Example 7]
Near-infrared absorbing particles surface-treated were obtained in the same manner as in Example 1 except that the aluminum triethoxide in the step (d) was changed to aluminum triisopropoxide. The obtained near-infrared absorbing particles were subjected to energy dispersive X-ray analysis. Table 4 shows Cu / Al.
Further, X-ray diffraction was measured for the particles after the surface treatment. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ was confirmed, and it was identified that the particle was a near-infrared absorbing particle substantially composed of a crystallite of KCuPO ₄ even after passing through the step (d). . The crystallite size is shown in Table 4.
Further, a dispersion for measuring the particle size of near-infrared absorbing particles after the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 4.
Further, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the surface treatment was measured. The results are shown in Table 4.

Moist heat resistance test:
The near-infrared absorbing particles after the surface treatment were put in a crucible, and a moisture and heat resistance test was conducted in the same manner as in Example 1. About the near-infrared absorbing particles after the test, X-ray diffraction and diffuse reflection spectrum (reflectance) were measured, and it was confirmed that the near-infrared absorption characteristics were maintained even after the wet heat resistance test.

Dispersion, coating:
A near-infrared absorbing coating film was formed in the same manner as in Example 1 using the near-infrared absorbing particles after the surface treatment. The near-infrared absorbing coating film was subjected to a heat and moisture resistance test in the same manner as in Example 1, and comparatively evaluated for changes in transmittance and haze before and after the test. The results are shown in Table 4.

[Example 8]
Near-infrared absorbing particles surface-treated were obtained in the same manner as in Example 1 except that the aluminum triethoxide in the step (d) was changed to zirconium tetra-n-butoxide. The obtained near-infrared absorbing particles were subjected to energy dispersive X-ray analysis. Table 4 shows Cu / Zr.
Further, X-ray diffraction was measured for the particles after the surface treatment. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ was confirmed, and it was identified that the particle was a near-infrared absorbing particle substantially composed of a crystallite of KCuPO ₄ even after passing through the step (d). . The crystallite size is shown in Table 4.
Further, a dispersion for measuring the particle size of near-infrared absorbing particles after the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 4.
Further, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the surface treatment was measured. The results are shown in Table 4.

Moist heat resistance test:
Near-infrared absorbing particles containing aluminum were placed in a crucible and subjected to a moisture and heat resistance test in the same manner as in Example 1. About the near-infrared absorbing particles containing aluminum after the test, X-ray diffraction and diffuse reflection spectrum (reflectance) were measured, and it was confirmed that the near-infrared absorbing characteristics were maintained even after the wet heat resistance test.

Dispersion, coating:
A near-infrared absorbing coating film was formed in the same manner as in Example 1 using the near-infrared absorbing particles after the surface treatment. The near-infrared absorbing coating film was subjected to a heat and moisture resistance test in the same manner as in Example 1, and comparatively evaluated for changes in transmittance and haze before and after the test. The results are shown in Table 4.

[Example 9]
Near-infrared absorbing particles before surface treatment:
When the near-infrared absorbing particles before the surface treatment obtained in the step (c) of Example 1 were subjected to energy dispersive X-ray analysis, no Al element was detected.
Moreover, X-ray diffraction was measured about the near-infrared absorption particle | grains before surface treatment. Table 4 shows the crystallite size.
Moreover, a dispersion for measuring the particle size of near-infrared absorbing particles before the surface treatment was prepared, and the number average aggregated particle size was measured. The results are shown in Table 4.
Moreover, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles before the surface treatment was measured. The results are shown in Table 4. Further, the diffuse reflection spectrum is shown by a solid line in FIG.

Moist heat resistance test:
The near-infrared absorbing particles before the surface treatment obtained by the step (c) of Example 1 were put in a crucible and subjected to a moisture and heat resistance test. The same tester as in Example 1 was used, and the test conditions were set to 85 ° C. and 85% relative humidity, and exposed for 66 hours. X-ray diffraction was measured for the near-infrared absorbing particles after the test. The results are shown in FIG. From the result of X-ray diffraction, it was shown that the crystal structure of KCuPO ₄ was destroyed after the test because it was different from the X-ray diffraction of the near-infrared absorbing particles before the test shown in FIG.

  Moreover, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles after the test was measured. The results are shown by broken lines in FIG. From the result of the diffuse reflectance spectrum, unlike the diffuse reflectance spectrum of the near-infrared absorbing particles before the test shown by a solid line in FIG. 6, the reflectance on the long wavelength side of the visible light wavelength range decreases after the test, and the near-infrared wavelength The reflectivity of the area increased. That is, it was shown by this test that the near-infrared absorption characteristic of near-infrared absorption particles is impaired.

Dispersion, coating:
A near-infrared absorbing coating film was formed in the same manner as in Example 1 using the near-infrared absorbing particles before surface treatment obtained by the step (c) of Example 1. The near-infrared absorbing coating film was subjected to a heat and moisture resistance test in the same manner as in Example 1, and comparatively evaluated for changes in transmittance and haze before and after the test. The results are shown in Table 4.

  The near-infrared absorbing particles of the present invention are useful as near-infrared absorbing materials contained in near-infrared absorbing coatings such as near-infrared filters for cameras, optical filters for plasma displays, glass windows for vehicles (automobiles, etc.), lamps, etc. It is.

Claims (11)

Particles composed of crystallites of the compound represented by the following formula (1)
Near-infrared absorbing particles surface-treated with an alkoxide of a metal M selected from the group consisting of Al, Zr, Ti and Sn.
A _{1 / n} CuPO ₄ (1).
However, A is an alkali metal (Li, Na, K, Rb , Cs), alkaline earth metal and a (Mg, Ca, Sr, Ba ) and one or more selected from the group consisting of NH _4,
n is 1 when A is an alkali metal or NH ₄ , and 2 when A is an alkaline earth metal. Near-infrared absorbing particles in which an element of a metal M selected from the group consisting of Al, Zr, Ti, and Sn is unevenly distributed on the surface of particles made of crystallites of a compound represented by the following formula (1),
Near-infrared absorbing particles having an atomic number concentration ratio (Cu / M) of M element and Cu element determined by energy dispersive X-ray analysis of 2.0 to 10.6.
A _{1 / n} CuPO ₄ (1).
However, A is an alkali metal (Li, Na, K, Rb , Cs), alkaline earth metal and a (Mg, Ca, Sr, Ba ) and one or more selected from the group consisting of NH _4,
n is 1 when A is an alkali metal or NH ₄ , and 2 when A is an alkaline earth metal. The size of the crystallite obtained from X-ray diffraction is 5 to 50 nm,
The number-average aggregated particle diameter of the near-infrared absorbing particles is 20 to 200 nm,
The near-infrared absorbing particles according to claim 1 or 2, wherein a reflectance at a wavelength of 450 nm in the diffuse reflection spectrum of the near-infrared absorbing particles is 80% or more. The near-infrared absorbing particles according to any one of claims 1 to 3, wherein the reflectance change amount D represented by the following formula (2) is -0.41 or less.
D (% / nm) = [ _R700 (%)- _R600 (%)] / [700 (nm) -600 (nm)] (2).
However, R ₇₀₀ is a reflectance at a wavelength of 700 nm in the diffuse reflection spectrum of the near-infrared absorbing particles, and R ₆₀₀ is a reflectance at a wavelength of 600 nm in the diffuse reflection spectrum of the near-infrared absorbing particles.   The reflectance at a wavelength of 715 nm in the diffuse reflectance spectrum of the near-infrared absorbing particles is 19% or less, and the reflectance at a wavelength of 500 nm is 85% or more. Near-infrared absorbing particles. A method for producing near-infrared absorbing particles according to any one of claims 1 to 5,
The manufacturing method of near-infrared absorption particles which has the following process (d).
(D) A step of surface-treating particles comprising crystallites of the compound represented by the formula (1) with an alkoxide of a metal M selected from the group consisting of Al, Zr, Ti and Sn. The manufacturing method of the near-infrared absorption particle | grains of Claim 6 which further has the following process (a)-process (c).
At (a) in a solvent, a salt containing ^{Cu 2+,} a salt or an organic material containing _PO ^{4 3-,} _PO ^{4 3-} molar ratio with respect to ^{_{Cu 2+ (PO 4 3- / Cu}} 2+) 10-20 And A ^{n +} (where A is an alkali metal (Li, Na, K, Rb, Cs), alkaline earth metal (Mg, Ca, Sr, Ba) and NH ₄ ) 1 or more selected, and n is 1 when A is an alkali metal or NH ₄ , and 2 when A is an alkaline earth metal). Is a step of dispersing a raw material in a dispersion medium to obtain a raw material slurry.
(B) A step of introducing particles of the raw material slurry obtained in the step (a) into thermal plasma or flame and cooling the resulting product to obtain particles.
(C) A step of heat-treating the particles obtained in the step (b) at 300 to 700 ° C. to obtain particles composed of crystallites of the compound represented by the formula (1).   The dispersion liquid which disperse | distributed the near-infrared absorption particle in any one of Claims 1-5 to the dispersion medium.   The resin composition which disperse | distributed the near-infrared absorption particle in any one of Claims 1-5 to resin.   An article having a near-infrared absorbing coating film, having a near-infrared absorbing coating film comprising the near-infrared absorbing particles according to any one of claims 1 to 5 on the surface of the substrate.   The near-infrared absorption article containing the near-infrared absorption particle in any one of Claims 1-5.

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