Method for producing silica aerogel coating

A method for producing a silica aerogel coating having fine pores, comprising:

• preparing an organically modified wet gel by forming a wet gel by the hydrolysis and polymerization of an alkoxysilane and/or silsesquioxane, and by reacting said wet gel with an organic-modifying agent comprising unsaturated groups;
• preparing an organically modified silica-containing sol by dispersing said organically modified wet gel in a dispersing medium by an ultrasonic treatment wherein the ultrasonic radiation frequency is 10-30 kHz, the output is 300-900 W, and the ultrasonic treatment time is 5-120 minutes;
• mixing said organically modified silica-containing sol, an ultraviolet-curable fluororesin having a refractive index of 1.5 or less after curing and a photo-polymerization initiator to prepare a coating liquid;
• coating and drying said coating liquid on a substrate to evaporate the dispersing medium in said coating liquid, and thereby forming a layer composed of an organically modified silica, said ultraviolet-curable fluororesin and said photo-polymerization initiator;
• irradiating ultraviolet rays to said layer to polymerize said ultraviolet-curable fluororesin, and said ultraviolet-curable fluororesin and said organically modified silica, whereby a cured fluororesin layer formed by ultraviolet polymerization of said ultraviolet-curable fluororesin covers the surface and pores of said organically modified silica;
• and then
• baking said layer, and thereby forming said silica aerogel coating having a refractive index of 1.2-1.3.