Spherical silica particles and method of production
AssigneeShin-Etsu Chemical Co., Ltd.
InventorsYoshiharu Konya, Koichiro Watanabe, Susumu Ueno
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Abstract
Spherical, non-crystalline silica particles made by burning a non-halogenated siloxane starting material are substantially halogen-free, and have a content of metallic impurities other than silicon of not more than 1 ppm, a particle size of 10 nm to 10 μm and a specific surface area of 3-300 m2/g. Production of the particles is carried out by oxidative combustion of the non-halogenated siloxane in a flame at a high adiabatic flame temperature to effect the formation of a large number of core particles and promote their coalescence and growth.
Claims9
Spherical, non-crystalline silica particles made by burning a non-halogenated siloxane starting material, which particles are substantially halogen-free and have a content of metallic impurities other than silicon of not more than 1 ppm, a particle size of 10 nm to 10 μm and a specific surface area of 3 to 300 m2/g.
A method of producing spherical silica particles comprising the steps of:
- feeding a non-halogenated siloxane to the top of a combustion zone housing a flame having an adiabatic flame temperature of 1,600° C. to 5,600° C. thereby producing hot silica droplets;
- causing the hot silica droplets to coalesce into hot spherical particles having a diameter of 10 nm to 10 μm and a specific surface area of 3 to 300 m2/g while the hot silica particles are downwardly falling toward the bottom of the combustion zone under the influence of gravity;
- cooling the hot spherical particles while the hot silica particles are continuing to downwardly fall toward the bottom of the combustion zone under the influence of gravity to form cooled spherical particles;
- recovering the cooled spherical particles.
Dependencies are inferred from the claim text.