Patent ID: 6521290
Filing Date: 2003-02-18
Classification: C08K

Abstract:
A process for producing silane-surface-treated fine silica particles, comprising the steps of:(A) introducing an R2SiO3/2 unit (wherein R2 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms) to the surfaces of hydrophilic fine silica particles comprising an SiO2 unit to obtain hydrophobic fine silica particles; and (B) introducing an R13SiO1/2 unit (wherein R1's may be the same or different and each represent a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms) to the surfaces of the resultant hydrophobic fine silica particles; wherein; the step (A) comprises adding to an aqueous dispersion or mixed-solvent dispersion containing the hydrophilic fine silica particles a trifunctional silane compound represented by the general formula (II): R2Si(OR4)3â€ƒâ€ƒ(II) (wherein R2 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R4's may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms) or a partial hydrolysis-condensation product thereof or a mixture of these, to treat the surfaces of the hydrophilic fine silica particles and obtain an aqueous hydrophobic fine silica particle dispersion; andthe step (B) comprises the step of converting the dispersion medium of the aqueous hydrophobia fine silica particle dispersion into a ketone solvent to obtain a hydrophobic fine silica particle ketone solvent dispersion, and the step of adding to the hydrophobic fine silica particle ketone solvent dispersion a monofunctional silazane compound represented by the general formula (III): R13SiNHSiR13â€ƒâ€ƒ(III) (wherein R1's may be the same or different and each represent a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms), a monofunctional silane compound represented by the general formula (IV):R13SiXâ€ƒâ€ƒ(IV) (wherein R1's are as defined in the general formula (III), and X represents a hydroxyl group or a hydrolyzable group) or a mixture of these to make triorganosilylation of reactive groups remaining on the surfaces of the hydrophobic fine silica particles.