FUJIMI INCORPORATED

A method for manufacturing a silica sol according to an embodiment of the present invention includes: a step of preparing a silica sol reaction liquid by hydrolyzing and polycondensing an alkoxysilane or a condensate thereof using an alkali catalyst in a solvent; and at least one of a step of concentrating the silica sol reaction liquid by an ultrasonic atomization separation method and a step of replacing the silica sol reaction liquid with water by the ultrasonic atomization separation method.

Provided is a method for producing a silica sol capable of increasing the ratio of heteromorphized silica particles. A method for producing a silica sol according to an aspect of the present disclosure includes a step of preparing a first liquid including silica core particles having an average value of longest diameters of primary particles of 20 nm or less, and a step of preparing a second liquid including linked silica core particles by holding the first liquid for 72 hours or longer.

Provided is a method for producing a silica sol. A gel-like material cannot be generated and highly associated silica particles can be obtained. A method for producing a silica sol comprises a step of making a reaction liquid by mixing liquid (A) comprising an alkaline catalyst, water, a first organic solvent and silica particles for association with liquid (B) comprising at least one of tetramethoxysilane and a condensate thereof and a second organic solvent, wherein during the mixing, an addition rate of the liquid (B) is 8.5×10 −4 to 5.6×10 −3 (mol of silicon atoms in liquid (B)/mol of water in liquid (A)) per minute.

A silica sol which does not gelate, has a high purity, and contains a high concentration of silica particles is provided. A silica sol containing silica particles and water, wherein a product of an average primary particle size of the silica particles and an average circularity of the silica particles is 15.0 or more and 31.2 or less, a concentration of the silica particles is 20 mass % or more, a total organic carbon amount per silica particle is less than 10 mass ppm, when the concentration of the silica particles is 20 mass %, a viscosity at 25° C. is 300 mPa·s or less, and a concentration of a metal impurity is less than 1 mass ppm.

A method for manufacturing a silica sol according to an embodiment of the present invention includes: a step of preparing a silica sol reaction liquid by hydrolyzing and polycondensing an alkoxysilane or a condensate thereof using an alkali catalyst in a solvent; and at least one of a step of concentrating the silica sol reaction liquid by an ultrasonic atomization separation method and a step of replacing the silica sol reaction liquid with water by the ultrasonic atomization separation method.

Provided is a method for producing a silica sol. A gel-like material cannot be generated and highly associated silica particles can be obtained. A method for producing a silica sol comprises a step of making a reaction liquid by mixing liquid (A) comprising an alkaline catalyst, water, a first organic solvent and silica particles for association with liquid (B) comprising at least one of tetramethoxysilane and a condensate thereof and a second organic solvent, wherein during the mixing, an addition rate of the liquid (B) is 8.5×10 −4 to 5.6×10 −3 (mol of silicon atoms in liquid (B)/mol of water in liquid (A)) per minute.

Provided is a polishing composition in which a polishing speed of silicon germanium is sufficiently high and a selection ratio of the polishing speed of silicon germanium is sufficiently high. A polishing composition includes: abrasive grains; an inorganic salt; and an oxidizing agent, in which the number of silanol groups per unit surface area of the abrasive grains is more than 0/nm 2 and 2.0/nm 2 or less, and a pH of the polishing composition is 6.0 or more.

There is provided a method of producing anionically modified colloidal silica capable of polishing a silicon nitride film at a high speed and suppressing a polishing speed of a silicon oxide film. A method of producing anionically modified colloidal silica includes ion exchanging raw colloidal silica using an ion exchange resin (ion exchange step); and anionically modifying ion-exchanged raw colloidal silica to obtain anionically modified colloidal silica (modification step).

The silicon carbide powder is a powder of silicon carbide having an α-type crystal system, where the number of small corner portions among corner portions on a surface of a primary particle of silicon carbide constituting the powder of silicon carbide is 2.5 or less per one primary particle. The small corner portion is a corner portion, among corner portions present in a contour of the primary particle in a projection image of the primary particle, where twice a curvature radius of the corner portion is 1/5 or less of a Heywood diameter of the projection image of the primary particle.

The present invention provides a means capable of suppressing the formation of fine particles in a method for producing a silica sol. The present invention relates to a method for producing a silica sol, including synthesizing a silica sol by, in a reaction liquid containing an alkoxysilane or a condensate thereof, water, and an alkali catalyst, allowing the alkoxysilane or condensate thereof to react with the water in the presence of the alkali catalyst, wherein the alkali catalyst is not additionally supplied after the start of the synthesis until the finish time of the synthesis, and during 90% or more of the time between when 5 minutes have elapsed from the time point when the electrical conductivity of the reaction liquid reaches a local maximum for the first time and the finish time of the synthesis, the proportion of the value of the electrical conductivity of the reaction liquid is more than 90% relative to the value of the electrical conductivity at the time when 5 minutes have elapsed from the time point when the local maximum is reached.