A method for producing a dispersion liquid of silica particles, by simultaneously adding a liquid A containing silane alkoxide and a liquid B containing an alkali catalyst and water to a liquid I containing silica seed particles to cause the particles to grow, so as to produce silica particles; wherein the variation rate of the mole ratio of the alkali catalyst to silica components in the reaction system during a period from the start to the end of the addition relative to the initial mole ratio is 0.90 to 1.10; and the variation rate of the mole ratio of water to the silica components in the reaction system during a period from the start to the end of the addition relative to the initial mole ratio is 0.90 to 1.10.

A method for producing a dispersion liquid of silica particles, by simultaneously adding a liquid A containing silane alkoxide and a liquid B containing an alkali catalyst and water to a liquid I containing silica seed particles to cause the particles to grow, so as to produce silica particles; wherein the variation rate of the mole ratio of the alkali catalyst to silica components in the reaction system during a period from the start to the end of the addition relative to the initial mole ratio is 0.90 to 1.10; and the variation rate of the mole ratio of water to the silica components in the reaction system during a period from the start to the end of the addition relative to the initial mole ratio is 0.90 to 1.10.

This surface-treated sol-gel silica is characterized by containing sol-gel silica having an average particle size of 0.05 m or more and 2.0 m or less as measured by laser diffraction scattering and a surface treatment agent on the surface of the sol-gel silica. In a dispersion produced by dispersing 5 mass % of the sol-gel silica in ethanol by emitting ultrasonic waves at 40W for 10 minutes, the content of particles with particle sizes of 5 m or more is 10 ppm or less in a particle number size distribution obtained by a Coulter counter method.

This surface-treated sol-gel silica is characterized by containing sol-gel silica having an average particle size of 0.05 m or more and 2.0 m or less as measured by laser diffraction scattering and a surface treatment agent on the surface of the sol-gel silica. In a dispersion produced by dispersing 5 mass % of the sol-gel silica in ethanol by emitting ultrasonic waves at 40W for 10 minutes, the content of particles with particle sizes of 5 m or more is 10 ppm or less in a particle number size distribution obtained by a Coulter counter method.

A method for producing an active silicic acid solution in which the existing amount of foreign matters as plate-like fine particles is reduced and a method for producing a silica sol in which such foreign matters are reduced. The method fulfills the following condition; the existing amount of plate-like fine particles having a length of one side of 0.2 to 4.0 m and a thickness of 1 to 100 nm is measured to be 0% to 30% in accordance with measuring method A, the method including the steps of: preparing an active silicic acid solution by subjecting an alkali silicate aqueous solution having a silica concentration of 0.5% by mass to 10.0% by mass to cation-exchange to remove alkaline components; and filtering the active silicic acid solution through a filter whose removal rate of particles having a primary particle size of 1.0 m is 50% or more.

The present disclosure provides an aerogel composition which is intrinsically hydrophobic without surface modification by a hydrophobizing agent, is durable and easy to handle, which has favorable performance in aqueous environments, and which also has favorable combustion and self-heating properties. Also provided is a method of preparing an aerogel composition which is intrinsically hydrophobic without surface modification by a hydrophobizing agent, is durable and easy to handle, which has favorable performance in aqueous environments, and which has favorable combustion and self-heating properties.

The present disclosure provides an aerogel composition which is intrinsically hydrophobic without surface modification by a hydrophobizing agent, is durable and easy to handle, which has favorable performance in aqueous environments, and which also has favorable combustion and self-heating properties. Also provided is a method of preparing an aerogel composition which is intrinsically hydrophobic without surface modification by a hydrophobizing agent, is durable and easy to handle, which has favorable performance in aqueous environments, and which has favorable combustion and self-heating properties.

A method for producing a liquid dispersion containing irregular-shaped silica particles in which two or more primary particles are linked together, by simultaneously adding a liquid A containing silane alkoxide and a liquid B containing an alkali catalyst and water to a liquid I consisting substantially of an organic solvent to cause hydrolysis and polycondensation of the silane alkoxide, wherein the period from the start of the addition until the silica concentration of the reaction system at the end of the addition reaches 70% is 20% or less of the full reaction time period.

A method for producing a liquid dispersion containing irregular-shaped silica particles in which two or more primary particles are linked together, by simultaneously adding a liquid A containing silane alkoxide and a liquid B containing an alkali catalyst and water to a liquid I consisting substantially of an organic solvent to cause hydrolysis and polycondensation of the silane alkoxide, wherein the period from the start of the addition until the silica concentration of the reaction system at the end of the addition reaches 70% is 20% or less of the full reaction time period.

Provided is a dispersion containing high-purity silica particles and a method for producing the same. A first solution containing a silane alkoxide and a second solution containing fine bubbles having an average bubble diameter of 40 nm to 10 m are mixed. Thus, the silane alkoxide is hydrolyzed without using an alkaline catalyst in a liquid phase containing the fine bubbles, so that uniform silica particles having an average particle size of 3 to 10 nm are produced. Further, hydrolysis is carried out by adding a hydrolyzable metal compound to the dispersion containing the silica particles in the presence of the fine bubbles and the alkaline catalyst. Thus, the silica particles are grown, so that a uniform silica-based particle dispersion containing particles having an average particle size of more than 10 nm and 300 nm or less is produced.