Method for producing silica / alumina sol, silica / alumina sol, transparent film-forming coating material containing the sol, and substrate with transparent film

摘要

Disclosed is a silica-alumina sol that is stable even at high concentrations and has good dispersibility in a matrix component, and a method for producing the same. Silica / alumina sol removes cations (alkali metal ions) that are derived from manufacturing raw materials, reduces impurities, and uses silica / alumina particles whose surface negative charge is adjusted within a specified range. The silicon compound is adsorbed on the particle surface in advance, and then hydrolyzed and surface-treated.