NEAR-INFRARED-ABSORBING PARTICLES, PROCESS FOR PRODUCING SAME, DISPERSION, AND ARTICLE THEREOF

摘要

Provided are near-infrared-absorbing particles which have a high transmittance in the visible light region and a low transmittance in the near infrared region and which, when incorporated, can give a near-infrared-absorbing coating film that abruptly changes in transmittance in the wavelength range of 630-700 nm. Also provided are a process for producing the particles and a dispersion of the particles. The near-infrared-absorbing particles comprise crystallites of A1/nCuPO4 and have a number-average aggregate diameter of 20-200 nm. In the formula, A is one or more atoms or groups selected from a group consisting of alkali metals (Li, Na, K, Rb, and Cs), alkaline earth metals (Mg, Ca, Sr, and Ba), and NH4, and n is 1 when A is an alkali metal or NH4 or is 2 when A is an alkaline earth metal.