Silicone oil-treated silica particles and toner for electrophotography

A silicone oil-treated silica particle comprising a silica particle body and silicone oil, wherein:

• the silica particle body has a BET specific surface area of 70 m2/g to 120 m2/g,
• the silica particle body has been surface-treated with the silicone oil,
• the silica particle body is fumed silica,
• the silica particle body has a particle density of 2.23 g/cm3 or more as measured by a helium (He) gas pycnometer, with an apparent density of 20 g/l to 35 g/l,
• the amount of free silicone oil liberated from the surface of the silica particle body in the silicone oil accounts for 2.0 mass % to 5.0 mass % with respect to the silica particle body,
• a surface-treated styrene acrylic resin particle, in which 2 parts by mass of the silicone oil-treated silica particle has been added to 100 parts by mass of a styrene acrylic resin particle having a particle size median of 5 um to 8 um, has a degree of agglomeration of 18% or less, and
• wherein respective fractal shape parameter a values of the silica particle body in measurement ranges of 20-30 nms, 30-40 nm, and 50-70 nm have a maximum value αmax of 2.9 or more.