Patent ID: 11932543
Assignee: TOKUYAMA CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A method for producing a silica-based composite oxide powder comprising a composite oxide of silicon and at least one metal selected from the group consisting of titanium and zirconium, the silica-based composite oxide powder having a volume-based cumulative 50% diameter measured by a laser diffraction scattering method in a range of 0.05 μm to 2.0 μm, and a coefficient of variation of 40% or less, wherein in a 5 mass % dispersion of the silica-based composite oxide powder obtained by ultrasonic irradiation (at an output of 40 W for 10 minutes), a content of particles having a particle diameter of 5 μm or more in a particle size distribution obtained by a Coulter counter method is 10 ppm or less on a number basis, the method comprising:
(1) preparing a partial hydrolysate of silicon alkoxide;
(2) mixing the partial hydrolysate with alkoxide of metal selected from the group consisting of titanium and zirconium or a mixture of the alkoxide of the metal and a complexing agent such that titanium or zirconium is mixed in a proportion of 50 mol % or less to a total amount of metal, thereby preparing a composite alkoxide material;
(3) hydrolyzing and condensing the composite alkoxide material in a dispersion medium containing water, thereby obtaining composite oxide particles;
(4) wet-filtering a dispersion of the composite oxide particles dispersed in the dispersion medium containing water using a filter medium having a pore size of 3 μm or more and 5 μm or less;
(5) adding a compound including at least one selected from the group consisting of carbon dioxide, ammonium carbonate, ammonium bicarbonate, and ammonium carbamate to the wet-filtered dispersion of the composite oxide particles to coagulate the composite oxide particles, thereby obtaining a coagulated composite oxide dispersion containing the coagulated composite oxide;
(6) separating the composite oxide particles from the coagulated composite oxide dispersion; and
(7) drying the separated composite oxide particles.