Hydrophobic silica particles and method of producing same

Hydrophobic silica particles prepared by a method comprising:

• a) providing a hydrosiloxane agent having the following formula
• wherein R1=—H, —CH3,
• R2=—H, —CH3,
• R3=—CH3, —CH2CH3, —CH2CH2CH3, —CH2Ar, —CH2CH2Ar, —Ar, —CH2CH2CF3, or —CH2CH2—Rf with Rf being a C1 to C8 perfluoroalkyl group,
• R4=—CH3, —CH2CH3, —CH2CH2CH3, —CH2CH2CF3, or —CH2CH2—Rf with Rf being a C1 to C8 perfluoroalkyl group,
• R5=—CH3, —CH2CH3, —CH2Ar, —CH2CH2Ar, or —Ar,
• R6=—H, —OH, —OCH3, or —OCH2CH3,
• Ar is unsubstituted phenyl or phenyl substituted with one or more methyl, halogen, ethyl, trifluoromethyl, pentafluoromethyl, or —CH2CF3 groups,
• n, m, and k are integer numbers;
• n≧1, m≧1, k≧0, wherein the hydrosiloxane agent has number average molecular weight from 282 to about 20,000;
• b) contacting silica particles with the hydrosiloxane agent in the presence of a solvent, the solvent, silica particles, and hydrosiloxane agent forming a reaction mixture, wherein the reaction mixture has pH from about 2 to about 6 or from about 8 to about 12;
• and
• c) drying the reaction mixture to provide the hydrophobic silica particles.

A particle composition comprising the reaction product of a solvent dispersion of silica particles at a pH from about 2 to about 6 or from about 8 to about 12 and at least a hydrosiloxane agent having the formula

• wherein R1=—H, —CH3,
• R2=—H, —CH3,
• R3=—CH3, —CH2CH3, —CH2CH2CH3, —CH2Ar, —CH2CH2Ar, —Ar, —CH2CH2CF3, or —CH2CH2—Rf with Rf being a C1 to C8 perfluoroalkyl group,
• R4=—CH3, —CH2CH3, —CH2CH2CH3, —CH2CH2CF3, or —CH2CH2—Rf with Rf being a C1 to C8 perfluoroalkyl group,
• R5=—CH3, —CH2CH3, —CH2Ar, —CH2CH2Ar, or —Ar,
• R6=—H, —OH, —OCH3, or —OCH2CH3,
• Ar is unsubstituted phenyl or phenyl substituted with one or more methyl, halogen, ethyl, trifluoromethyl, pentafluoromethyl, or —CH2CF3 groups,
• n, m, and k are integer numbers;
• n≧1, m≧1, and wherein the hydrosiloxane agent has a number average molecular weight from 282 to about 20,000.

A toner composition comprising toner particles and the reaction product of a solvent dipersion of silica particles at a pH from about 2 to about 6 or from about 8 to about 12 and at least a hydrosiloxane agent having the formula

• wherein R1=—H, —CH3,
• R2=—H, —CH3,
• R3=—CH3, —CH2CH3, —CH2CH2CH3, —CH2Ar, —CH2CH2Ar, —Ar, —CH2CH2CF3, or —CH2CH2—Rf with Rf being a C1 to C8 perfluoroalkyl group,
• R4=—CH3, —CH2CH3, —CH2CH2CH3, —CH2CH2CF3, or —CH2CH2—Rf with Rf being a C1 to C8 perfluoroalkyl group,
• R5=—CH3, —CH2CH3, —CH2Ar, —CH2CH2Ar, or —Ar,
• R6=—H, —OH, —OCH3, or —OCH2CH3,
• Ar is unsubstituted phenyl or phenyl substituted with one or more methyl, halogen, ethyl, trifluoromethyl, pentafluoromethyl, or —CH2CF3 groups,
• n, m, and k are integer numbers;
• n≧1, m≧1, k≧0 and wherein the hydrosiloxane agent has a number average molecular weight from 282 to about 20,000.