THERMAL INSULATING MATERIAL BASED ON PIGMENT CONTAINING SILICA AEROGELS

摘要

A thermal insulating material based on a pigment-containing silica aerogel is obtainable by a) reacting an aqueous dispersion of sodium silicate and a pigment with a strong acid or sodium silicate with a pigment-containing strong acid to give a pigment-containing silica hydrogen, the pigment being such that it scatters, absorbs or reflects infrared radiation of wavelength 3-10 mu m, b) substantially freeing the resulting pigment-containing silica hydrogel from ionic constituents by washing with water, c) displacing the water in the hydrogen by a low-boiling liquid which is inert toward the pigment-containing silica gel, d) heating the liquid-containing silica gel thus obtained under supercritical conditions while completely covered with the liquid, and e) subsequently removing the liquid from the solid by flash vaporization at supercritical temperature.