Colloidal silica, and method for production thereof
AssigneeFuso Chemical Co., Ltd.
InventorKazuaki Higuchi
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Abstract
The present invention provides dense silica particles with reduced metal impurities. Specifically, the present invention provides a colloidal silica produced by using an alkyl silicate as a starting material, wherein, with respect to a sample prepared by adding, as an internal standard, 1 wt. % of polydimethylsilane to a dried product of the colloidal silica, a peak area value calculated using a formula of a colloidal silica peak area/a polydimethylsilane peak area is 15 or less, the peak areas being determined by an obtained solid-state 29Si-CP/MAS-NMR spectrum. The present invention further provides a method for producing the colloidal silica.
Claims11
A colloidal silica produced by using an alkyl silicate as a starting material,
- wherein, with respect to a sample prepared by adding, as an internal standard, 1 wt. % of polydimethylsilane to a dried product of the colloidal silica, a peak area value calculated using a formula of a colloidal silica peak area/a polydimethylsilane peak area is 15 or less, the peak areas being determined by measuring a solid-state 29Si-CP/MAS-NMR spectrum of the dried product.
A method for producing a colloidal silica, comprising the steps of:
- 1) preparing a mother liquid comprising an alkali catalyst and water;
- and
- 2) adding, to the mother liquid, a hydrolyzed liquid obtained by hydrolyzing an alkyl silicate,
- wherein the hydrolyzed liquid is added to the mother liquid at a rate of not greater than 41 g of silica/hour/kg of mother liquid.
A method for producing a colloidal silica, comprising the steps of:
- 1) preparing a mother liquid comprising an alkali catalyst, water and seed particles;
- and
- 2) adding, to the mother liquid, a hydrolyzed liquid obtained by hydrolyzing an alkyl silicate,
- wherein the hydrolyzed liquid is added to the mother liquid at a rate of not greater than 4.2×10−3 g of silica/hour/m2 of seed particle surface area.
Dependencies are inferred from the claim text.