| 摘要 |
PROBLEM TO BE SOLVED: To provide hydrophobic silica which enables a decrease in isolated or eluted silicone oil which has not reacted with silanol groups on the silica surface, while maintaining the target degree of hydrophobization represented by an M value or an amount of adsorbed DBA after a hydrophobization treatment.SOLUTION: Provided is hydrophobic silica obtained by surface-treating wet-process synthetic silica with a silicone oil. The hydrophobic silica (i) contains a silicone oil eluted in toluene in an amount of less than 0.2% relative to the weight of the hydrophobic silica, where the eluted amount is a ratio of eluted silicone oil after the hydrophobic silica is dispersed in toluene in a concentration of 2% and kept at 20°C for 24 hours in comparison to the weight before dispersion. Also provided is a method for producing hydrophobic silica obtained by surface-treating wet-process synthetic silica with a silicone oil comprises the steps of: coating a surface of wet-process synthetic silica on which a strong acid-strong base-type neutral salt compound is made present, with a silicone oil; and subsequently subjecting the coated silicone oil and silanol groups of the wet-type synthetic silica to a condition where they react to form a siloxane bond.SELECTED DRAWING: None |
