Surface-treated infrared absorbing fine particles, surface-treated infrared absorbing fine powder, infrared absorbing fine particle dispersion liquid using the surface-treated infrared absorbing fine particles, infrared absorbing fine particle dispersion body and method for producing them

A method for producing surface-treated infrared absorbing fine particles, comprising:

• mixing infrared absorbing fine particles and water, and performing a dispersion treatment to obtain a coating layer-forming dispersion liquid with water as a medium;
• adding a metal chelate compound and / or a metal cyclic oligomer compound while stirring the coating layer-forming dispersion liquid with water as a medium;
• continuing the stirring after the addition, and coating a surface of the infrared absorbing fine particles with a coating layer containing at least one component selected from hydrolysis product of a metal chelate compound, polymer of hydrolysis product of a metal chelate compound, hydrolysis product of a metal cyclic oligomer compound, and polymer of hydrolysis product of a metal cyclic oligomer compound, wherein the component has a hydroxyl group or a carboxyl group, and the metal chelate compound or the metal cyclic oligomer compound contains at least one metal element selected from Al, Zr, Ti, and Zn, to obtain an infrared absorbing fine particle dispersion liquid.

A method for producing surface-treated infrared absorbing fine particles, comprising:

• mixing infrared absorbing fine particles and an organic solvent, performing a dispersion treatment, to obtain a coating layer-forming dispersion liquid with the organic solvent as a medium;
• simultaneously adding a metal chelate compound or / and a metal cyclic oligomer compound and water in parallel while stirring the coating layer-forming dispersion liquid with the organic solvent as a medium;
• continuing the stirring after the addition, and coating a surface of the infrared absorbing fine particles with a coating layer containing at least one component selected from hydrolysis product of a metal chelate compound, polymer of hydrolysis product of a metal chelate compound, hydrolysis product of a metal cyclic oligomer compound, and polymer of hydrolysis product of a metal cyclic oligomer compound, wherein the component has a hydroxyl group or a carboxyl group, and the metal chelate compound or the metal cyclic oligomer compound contains at least one metal element selected from Al, Zr, Ti, and Zn, to obtain an organic solvent dispersion liquid of infrared absorbing fine particles.