Patent ID: 8048394

Claim:
A process for producing hollow silica particles comprising an outer shell portion having a mesoporous structure, said process comprising: (I) preparing an aqueous solution comprising (a) 0.1 to 100 mmol/L of at least one quaternary ammonium salt selected from the group consisting of a compound represented by the formula (1) and a compound represented by the formula (2): [R 1 (CH 3 ) 3 N] + X − (1), [R 1 R 2 (CH 3 ) 2 N] + X − (2), wherein R 1 and R 2 are each independently a linear or branched alkyl group having 4 to 22 carbon atoms; and X is a monovalent anion; (b) 0.1 to 100 mmol/L of a silica source capable of forming a silanol compound by hydrolysis thereof; (c1) 0.1 to 100 mmol/L of a hydrophobic organic compound or (c2) 0.01 to 10% by mass of a polymeric organic compound, wherein the polymeric organic compound is at least one compound selected from the group consisting of a water insoluble cationic polymer and a water insoluble nonionic polymer; and water; (II) stirring the aqueous solution prepared in (I) at a temperature of 10 to 100° C. to precipitate composite silica particles comprising silica particles which comprise an outer shell portion having a mesoporous structure, and the hydrophobic organic compound (c1) or the polymeric organic compound (c2) incorporated inside of the silica particles; and (III) baking the composite silica particles obtained in (II).