Dispersion liquid of silica particles and production method therefor

Patent metadata

Field	Value
Publication number	US-11427730-B2
Application number	US-201816764050-A
Country	US
Kind code	B2
Filing date	Nov 15, 2018
Priority date	Nov 16, 2017
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

Provided is a dispersion liquid of silica particles, comprising silica particles having an average particle diameter of 5 to 300 nm determined from an electron micrograph and a density of 1.20 g/cm3 or more determined from a specific surface area determined by a BET method using nitrogen adsorption, wherein the dispersion liquid has a pH of less than 8, a silica concentration of 12 to 40% by mass, and a viscosity in terms of a silica concentration of 20% by mass of 40 mPa·s or less. When this silica particle is used as an abrasive, it is possible to realize a sufficient polishing speed and a smooth polished surface on which occurrence of scratches is suppressed.

First claim

The invention claimed is:

1. A dispersion liquid of silica particles, comprising silica particles having an average particle diameter of 5 to 300 nm determined from an electron micrograph, and a density of 1.20 g/cm 3 or more and less than 1.60 g/cm 3 determined from the average particle diameter and a specific surface area determined by a BET method using nitrogen adsorption, and an amount of carbon derived from an alkoxy group contained in the silica particles is 0.005% by mass or more and 0.50% by mass or less, wherein the dispersion liquid has a pH of less than 8, a silica concentration of 12 to 40% by mass, and a viscosity in terms of a silica concentration of 20% by mass of 40 mPa-s or less, wherein an amount of a compound containing silicon other than the silica particles in the dispersion liquid is 200 ppm or less, wherein a peak area showing Q4 structure, determined by 29 Si-NMR analysis from −100.0 to −120.0 ppm, is 70% to 90% of a peak area showing Q0 to Q4 structure, determined by 29 Si-NMR analysis from −73.0 to −120.0 ppm.

2. The dispersion liquid of silica particles according to claim 1 , wherein amounts of the following elements in the dispersion liquid are, per said silica particle, as follows:
(1) an amount of each of alkali metals, alkali earth metals, Fe, Ti, Zn, Pd, Ag, Mn, Co, Mo, Sn, Al and Zr is less than 0.1 ppm;
(2) an amount of each of Cu, Ni and Cr is less than 1 ppb; and
(3) an amount of each of U and Th is less than 0.3 ppb.

3. The dispersion liquid of silica particles according to claim 1 , wherein the dispersion liquid comprises ammonia, and a content of ammonia at a silica concentration of 20% by mass is less than 100 ppm.

4. A method for producing a dispersion liquid of silica particles, comprising: preparing a dispersion liquid containing silica particles by using alkoxysilane as raw material; aging by heating the dispersion liquid in the presence of alkali such that a density of the silica particles determined from an average particle diameter determined from an electron micrograph and a specific surface area determined by a BET method using nitrogen adsorption is 1.20 g/cm 3 or more 1.60 g/cm 3 or less, and removing the alkali from the dispersion liquid obtained by aging to once raise a viscosity in terms of a silica concentration of 20% by mass of the dispersion liquid to 60 mPa-s or more and then further removing the alkali to provide a pH of the dispersion liquid of less than 8, wherein an amount of carbon derived from an alkoxy group contained in the silica particles is 0.005% by mass or more and 0.50% by mass or less, an amount of a compound containing silicon other than the silica particles in the dispersion liquid is 200 ppm or less, wherein a peak area showing Q4 structure, determined by 29 Si-NMR analysis from −100.0 to −120.0 ppm, is 70% to 90% of a peak area showing Q0 to Q4 structure, determined by 29 Si-NMR analysis from −73.0 to −120.0 ppm.

5. The method for producing a dispersion liquid of silica particles according to claim 4 , comprising replacing an organic solvent of the dispersion liquid with water, after preparing the dispersion liquid and before aging the dispersion liquid.

6. The method for producing a dispersion liquid of silica particles according to claim 4 , wherein the aging is carried out at a pH of 8 or more.

Assignees

• Jgc Catalysts & Chemicals Ltd

Inventors

• Egami Miki
• Kumazawa Mitsuaki
• Arakane Hirotada
• Muraguchi Ryo
• Hirai Toshiharu

Classifications

• C01B33/18

  Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof (preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C) · CPC title

• C01P2006/10

  Solid density · CPC title

• C09G1/02 Primary

  containing abrasives or grinding agents {(abrasives as such C09K3/14; polishing of semi-conductors H10P52/40)} · CPC title

• C01P2006/80

  Compositional purity · CPC title

• C09K3/1463

  Aqueous liquid suspensions · CPC title