An apparatus for manufacturing an aerogel sheet including: a supply roller around which a blanket is wound to form a roll; a conveyor belt transferring the blanket wound around the supply roller from one side to the other side thereof; a silica sol supply member injecting the silica sol to a surface of the blanket disposed on the conveyor belt to impregnate the blanket with silica sol; a catalyst supply member injecting a gelling catalyst to the surface of the blanket impregnated with silica sol to gelate the silica sol; a collection roller winding the blanket, which is transferred up to the other side by the conveyor belt, in the form of a roll; and a reaction vessel which accommodates the roll-shaped blanket collected by the collection roller and in which the accommodated blanket is aged, modified by injecting a coating solution, or dried at a high temperature.

An apparatus for manufacturing an aerogel sheet including: a supply roller around which a blanket is wound to form a roll; a conveyor belt transferring the blanket wound around the supply roller from one side to the other side thereof; a silica sol supply member injecting the silica sol to a surface of the blanket disposed on the conveyor belt to impregnate the blanket with silica sol; a catalyst supply member injecting a gelling catalyst to the surface of the blanket impregnated with silica sol to gelate the silica sol; a collection roller winding the blanket, which is transferred up to the other side by the conveyor belt, in the form of a roll; and a reaction vessel which accommodates the roll-shaped blanket collected by the collection roller and in which the accommodated blanket is aged, modified by injecting a coating solution, or dried at a high temperature.

Provided is a production method of a silica particle dispersion liquid which includes, preparing a linked silica particle by adding a liquid A containing alkoxysilane and a liquid B containing an alkali catalyst to a liquid containing water, an organic solvent, and an alkali catalyst in a container. The preparing a linked silica particle includes initially adding an alkali catalyst, the initially adding an alkali catalyst includes decreasing a molar ratio of an alkali catalyst to silica in the liquid in the container to 0.15 to 0.60 by adding the liquid A containing alkoxysilane to the liquid in the container, and increasing the molar ratio by 0.2 or more by adding the liquid B to the liquid having the decreased molar ratio in the container.

Provided is a production method of a silica particle dispersion liquid which includes, preparing a linked silica particle by adding a liquid A containing alkoxysilane and a liquid B containing an alkali catalyst to a liquid containing water, an organic solvent, and an alkali catalyst in a container. The preparing a linked silica particle includes initially adding an alkali catalyst, the initially adding an alkali catalyst includes decreasing a molar ratio of an alkali catalyst to silica in the liquid in the container to 0.15 to 0.60 by adding the liquid A containing alkoxysilane to the liquid in the container, and increasing the molar ratio by 0.2 or more by adding the liquid B to the liquid having the decreased molar ratio in the container.

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.

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.

The method for producing a polishing composition according to the present invention includes mixing a dispersion containing silica and a solution containing a silane coupling agent having a cationic group at a concentration of 0.03% by mass or more and less than 1% by mass to obtain a dispersion containing cationically modified silica.

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.

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.

Methods for forming and controlling morphology cracks in silicon dioxide (SiO.sub.2) film comprising: preparing SiO.sub.2precursor solution comprising solvent, precursor of SiO.sub.2, precursor of metal oxide nanocrystals, water, and acid; coating the solution onto substrate; drying the solution atop the substrate at a temperature between about 20° C. to 100° C. between 1 minute to 24 hours to form SiO.sub.2 film having uniformly dispersed metal oxide nanocrystals, wherein shorter drying times yield substantially spherical shaped metal oxide nanocrystals and longer drying times yield rod and disc shaped metal oxide nanocrystals; and thermally treating the SiO.sub.2 film between about 60° C. to 500° C. between 1 minute to 24 hours to form cracked mesh SiO.sub.2 film, wherein two cracks initiate from rod shaped metal oxide nanocrystals, three to four cracks initiate from spherical shaped metal oxide nanocrystals, and four or more cracks initiate from disc shaped metal oxide nanocrystals. Other embodiments are described and claimed.