Patent ID: 6855759

Claim:
An organic resin composition comprising; (a) 100 parts by weight of an organic resin; and (b) from 0.01 to 10 parts by weight of silane-surface-treated fine silica particles wherein said silane-surface-treated fine silica particles comprise primary particles having a particle diameter of from 0.1 to 5 μm, and the fine silane-surface-treated silica particles are obtained by: (A) introducing an R 2 SiO 3/2 unit to the surface of a hydrophilic fine silica particle comprising an SiO 2 unit to form a hydrophobic fine silica particle by adding to an aqueous dispersion medium or mixed-solvent dispersion medium comprising the hydrophilic fine silica particle, a trifunctional silane compound represented by formula (II): R 2 Si(OR 4 ) 3 (II) wherein R 2 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and the R 4 groups may be the same or different and may each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms, or a partial hydrolysis-condensation product thereof or a mixture thereof, to treat the surfaces of the hydrophilic fine silica particles and form an aqueous hydrophobic fine silica particle dispersion; and (B) introducing an R 1 3 SiO 1/2 unit to the surface of the hydrophobic fine silica particle by converting the dispersion medium of the aqueous hydrophobic fine silica particle dispersion into a ketone solvent to obtain a hydrophobic fine silica particle ketone solvent dispersion, and adding to the hydrophobic fine silica particle ketone solvent dispersion a monofunctional silazane compound represented by formula (III): R 1 3 SiNHSiR 1 3 (III) wherein the R 1 groups may be the same or different and each may represent a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, a monofunctional silane compound represented by formula (IV): R 1 3 SiX (IV) wherein the R 1 groups are as defined in formula (III), and X represents hydroxyl group or a hydrolyzable group, or a mixture thereof to triorganosilylate the reactive groups remaining on the surface of the hydrophobic fine silica particles wherein the fine silica particles fulfill the following conditions (i) and (ii), (i) when an organic compound which is liquid at room temperature and has a dielectric constant of from 1 to 40 F/m and fine silane-surface-treated silica particles are mixed in a weight ratio of 5:1 and shaken, the fine silane-surface-treated silica particles disperse uniformly in the organic compound; and (ii) the quantity of primary particles remaining as primary particles when methanol is evaporated under heating from a dispersion prepared by dispersing the fine silane-surface-treated silica particles in methanol and thereafter holding the fine silane-surface-treated silica particles at a temperature of 100° C. for 2 hours, is at least 20% based on the quantity of primary particles originally present.