Near-infrared absorbing fine particle dispersion liquid and method for producing the same

A method for producing a near infrared absorbing fine particle dispersion liquid, comprising:

• mixing near Infrared absorbing fine particles selected from the group consisting of:
• fine particles of a composite tungsten oxide expressed by MxWyOz in which M is at least one element selected from the group consisting of 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, and I,
• W is tungsten,
• O is oxygen, and
• 0.001≤x/y≤1 and 2.2≤z/y≤3.0, and
• fine particles of a tungsten oxide having a Magneli phase and expressed by a general formula WyOz in which
• W is tungsten,
• O is oxygen, and
• 2.45≤z/y≤2.999,
• into a first solvent comprising at least one solvent selected from the group consisting of alcohols, ethers, esters, ketones, aromatic hydrocarbons, and glycol ethers, and having a boiling point of 180° C. or less, to thereby obtain a mixture;
• then dispersing the mixture in a medium mill, to thereby obtain a first dispersion liquid;
• adding and mixing a second solvent comprising at least one solvent selected from the group consisting of vegetable oils and vegetable oil-derived compounds into the first dispersion liquid, to thereby obtain a second dispersion liquid;
• removing from the second dispersion liquid the first solvent until a residual content of the first solvent in the second dispersion liquid is 1.15 mass % or more and 4.20 mass % or less, to thereby obtain a near infrared absorbing fine particle dispersion liquid, wherein a content of the near infrared absorbing fine particles in the near infrared absorbing fine particle dispersion liquid is 25 mass % or more and 75 mass % or less.

A method for producing a near Infrared absorbing fine particle dispersion liquid, comprising:

• mixing a first solvent comprising at least one solvent selected from the group consisting of alcohols, ethers, esters, ketones, aromatic hydrocarbons, and glycol ethers, and having a boiling point of 180° C. or less, and a second solvent comprising at least one solvent selected from the group consisting of vegetable oils and vegetable oil-derived compounds, to thereby obtain a mixed solvent;
• mixing infrared absorbing fine particles selected from the group consisting of:
• fine particles of a composite tungsten oxide expressed by MxWyOz in which M is at least one element selected from the group consisting of 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, and I,
• W is tungsten,
• O Is oxygen, and
• 0.001≤x/y≤1 and 2.2≤z/y≤3.0, and
• fine particles of a tungsten oxide having a Magneli phase and expressed by a general formula WyOz in which
• W is tungsten,
• O is oxygen, and
• 2.485≤z/y≤2.999,
• into the mixed solvent to obtain a mixture, and dispersing the mixture in a wet medium mill, to thereby obtain a dispersion liquid;
• and
• removing from the dispersion liquid the first solvent until a residual concentration of the first solvent in the dispersion liquid is 1.15 mass % or more and 4.20 mass % or less, to thereby obtain a near infrared absorbing fine particle dispersion liquid, wherein a content of the near Infrared absorbing fine particles in the near Infrared absorbing fine particle dispersion liquid is 25 mass % or more and 75 mass % or less.