Patent ID: 7615201
Filing Date: 2009-11-10
Classification: B82Y,C01B,C01G,C01P

Abstract:
1. A method for preparing spherical particles of silica-containing compound oxide consisting of 12.3 to 91.6% by weight of silica and the balance of at least two metal oxides other than silica wherein the metal oxides other than silica are selected from Ti, Al, Zr and Sn, comprising the steps of: feeding a halogen-free siloxane and at least two organometallic compounds each containing a metal other than silicon in liquid mixture form, said organometallic compound being used directly if it is liquid or after dissolution in a siloxane, alcohol or hydrocarbon solvent if it is solid, the halogen-free siloxane being selected from the group consisting of: an organopolysiloxane having the general formula (1):  wherein R an organopolysiloxane having the general formula (2):  wherein R an organopolysiloxane having the general formula (3):  wherein R the organometallic compound being selected from the group consisting of: a metal alkoxide having the general formula (4):  wherein M is a metal element selected from the group consisting of Ti, Al, Zr and Sn, OR a metal acylate compound having the general formula (5):  wherein COR a metal alkyl compound having the general formula (6): and  wherein R the halogen-free siloxane and the organometallic compound being fed so that 12.3 to 91.6% by weight of silica and the balance of at least two metal oxides other than silica are formed, and simultaneously atomizing and burning said halogen-free siloxane and said organometallic compound in a flame, wherein a hydrocarbon gas is fed as a combustion-assisting gas in an amount of 0.1 to 2 moles per mole of the siloxane and organometallic compounds combined, and an oxygen-containing gas is fed as a combustion-supporting gas in such an amount that a molar amount of oxygen is 1.0 to 4.0 times of the stoichiometric amount of oxygen required for combustion, and thereby obtaining spherical particles being substantially halogen-free and having a particle size of 10 nm to 3 μm, wherein the spherical particles have a light transmittance of at least 90% at a wavelength of visible light (400 to 760 nm).