| 摘要 |
<p>PURPOSE: To profitably obtain the fine silica (fumed silica) having a high specific surface area without causing any trouble on operation by flame-hydrolyzing an organohalosilane or disilane in the diffused flame of a gas containing a specific flammable gas and free oxygen. CONSTITUTION: The method for producing the fine silica comprises subjecting an organohalosilane or disilane to a flame hydrolysis treatment by a diffusion combustion method under conditions comprising using a quadruple pipe burner, charging the organohalosilane or disilane having a boiling point of <=200 deg.C, such as methyltrichlorosilane, as the gas in the central pipe 1 in a pressure of 2.6kg/cm<2> G (gauge pressure), while heating the gas with steam of 2kg/cm<2> G (gauge pressure), charging a gas containing free oxygen, such as dry air, in the air-charging pipe 2 in a rate of 0.83Nm<3> /h, charging a flammable gas capable of burning to produce steam, such as hydrogen gas, in a hydrogen-charging pipe 3 in a rate of 0.3Nm<3> /h, charging dry air in the outside air-charging pipe 4 in a rate of 0.83Nm<3> /h, and sucking the synthesized fumed silica in a rate of 40Nm<3> /h for carrying the fumed silica. Thus, the fumed silica having a specific surface area (BEST method) of 215m<2> /g is produced in a rate of approximately 1.0kg/h.</p> |
