| 摘要 |
The present invention pertains to hydrophobic silica obtained by surface treatment of wet-process synthetic silica using silicone oil. In this hydrophobic silica, (i) the amount of silicone oil eluted into toluene is less than 0.2% relative to the hydrophobic silica mass, where this elution amount is the silicone oil elution rate when the silicone oil is dispersed at a concentration of 2% in toluene and after the elapse of 24 hours at 20°C relative to before the dispersion. A method for producing hydrophobic silica obtained by surface treatment of wet-process synthetic silica using silicone oil. This method includes coating the surface of wet-process synthetic silica with silicone oil in the presence of a strong-acid/strong-base-type neutral salt compound, subsequently providing conditions under which silanol groups of the wet-process synthetic silica and the coated silicone oil form siloxane bonds, and obtaining hydrophobic silica. The present invention provides hydrophobic silica in which it is possible to decrease the release and elution of silanol groups from the silica surface and reduce the amount of unreacted silicone oil while maintaining the hydrophobicity, represented by the M value and DBA adsorption level, at the target value after hydrophobization treatment. |
