| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydrophobic silica powder which can stably maintain excellent hydrophobicity and fluidity and is useful as the fluidizing agent for various organic and inorganic powders, and the thickening agent and the reinforcing filler for resins and the like. SOLUTION: The hydrophobic silica powder is a silica powder having been surface treated with a polysiloxane and a trimethylsilylating agent, and 0.3-1.5 trimethylsilyl groups per 1 nm<2> surface area of the original silica powder of the silica powder are allowed to be present and, at the same time, the polysiloxane is attached at a ratio of A/20 pts.wt. to A/5 pts.wt. [provided that A is a specific surface area (m<2> /g) of the original silica powder] based on 100 pts.wt. original silica powder of the silica powder.
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