METHOD FOR PRODUCING SILICA POWDER AND SILICA POWER PRODUCED B USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a method for suppressing an increase in the viscosity of a silicone resin even when the filling rate of an silica powder into the silicone resin is increased for enhancing the strength of the silicone resin. SOLUTION: The silica powder 11 with an average diameter of 0.005-0.1μm is stored in a sealed container 12 and a heated to 300-500 deg.C while making an inert gas flow into the container 12 and stirring the silica powder 11, and then a water vapor is fed to the silica powder 11 which is being heated. The density of the silanol groups on the surface of the silica powder thus produced is 2.50 groups/nm<2> or higher.