Silica composite particles and method of preparing the same

Silica composite particles in which a silica particle surface is sequentially surface-treated with a titanium compound in which an organic group is bonded to a titanium atom through an oxygen atom, and a hydrophobizing agent,

• wherein,
• a titanium content in the silica composite particles measured using fluorescence X-ray particles measured using fluorescence X-ray is from 0.1% by weight to 3% by weight;
• a titanium content of a surface layer of the silica composite particles satisfies the following Formula (1);
• an average particle diameter of the silica composite particles is from 100 nm to 250 nm;
• and
• a particle size distribution index of the silica composite particles is from 1.25 to 1.4:
• 0.6<Y/X<1.8 (1)
• wherein in Formula (1), X represents a titanium content (% by weight) in silica composite particles measured using fluorescence X-ray, and Y represents a titanium content (atom %) of the silica composite particle surface obtained by XPS measurement.

A method of preparing silica composite particles, comprising:

• preparing an alkali catalyst solution in which an alkali catalyst is contained in a solvent containing alcohol;
• supplying a tetraalkoxysilane and an alkali catalyst into the alkali catalyst to form silica particles;
• adding a mixed solution of alcohol and a titanium compound in which an organic group is bonded to a titanium atom through an oxygen atom, in the alkali catalyst solution in which the silica particles are formed, to perform a surface-treatment of the surface of the silica particles by the titanium compound;
• and
• performing a surface-treatment of the surface of the silica particles treated by the titanium compound, with a hydrophobizing agent.

A method of preparing silica composite particles, comprising:

• preparing an alkali catalyst solution containing an alkali catalyst at a concentration of from 0.6 mol/L to 0.85 mol/L, in a solvent containing alcohol;
• supplying, into the alkali catalyst solution, tetraalkoxysilane at a supply amount of from 0.001 mol/(mol·min) to 0.01 mol/(mol·min) relative to the alcohol, an alkali catalyst at a supply amount of from 0.1 mol to 0.4 mol, relative to per 1 mol of a total supply amount of the tetraalkoxysilane per one minute, to form silica particles;
• supplying a mixed solution of alcohol and a titanium compound in which an organic group is bonded to a titanium atom through an oxygen atom, in the alkali catalyst solution in which the silica particles are formed, to perform a surface-treatment of the surface of the silica particles by the titanium compound;
• and
• performing a surface-treatment of the surface of the silica particles treated by the titanium compound, with a hydrophobizing agent.