| 摘要 |
PROBLEM TO BE SOLVED: To obtain a hydrophobic sol-gel silica powder having high hydrophobicity and low loss on drying and containing a modest amount of carbon.SOLUTION: In a dry surface treatment, an inert gas and a hydrophobizing agent are fed into a reaction vessel in a state where hydrophilic sol-gel silica particles are housed, and the silica particles are surface-treated while being fluidized. The linear velocity of the inert gas fed into the reaction vessel per cross-sectional area of the reaction vessel is set to be in the range of 1-12 m/s, the bulk density of the hydrophilic sol-gel silica particles during the surface treatment is set to be in the range of 0.6-0.9 time the bulk density of the silica particles when left at rest in the reaction vessel, and the bulk density of the silica particles at the heat treatment in the reaction vessel is set to be in the range of 150-300 g/L. |
