Silica-based sols

Aqueous silica-based sol comprising a nitrogen-containing organic compound having up to 25 carbon atoms and silica-based particles with a specific surface area of at least 700 square meters per gram of silica, the silica-based sol having a molar ratio of SiO2 to N of from 2:1 to 40:1.

Aqueous silica-based sol having a specific surface area of at least 100 square meters per gram of aqueous sol and comprising a nitrogen-containing organic compound having up to 25 carbon atoms and silica-based particles with a specific surface area of at least 300 square meters per gram of silica, the silica-based sol having a molar ratio of SiO2 to N of from 2:1 to 40:1.

Process for the production of an aqueous silica-based sol which comprises incorporating a nitrogen-containing organic compound having up to 25 carbon atoms in a silica-based sol containing silica-based particles with a specific surface area of at least 300 square meters per gram of silica and having an S-value in the range of from 10 to 60%.

Process for the production of an aqueous silica-based sol which comprises incorporating a nitrogen-containing organic compound having up to 25 carbon atoms in a silica-based sol containing silica-based particles with a specific surface area of at least 700 square meters per gram of silica, the obtained silica-based sol having a molar ratio of SiO2 to N of from 2:1 to 40:1.

Process for the production of an aqueous silica-based sol which comprises incorporating a nitrogen-containing organic compound having up to 25 carbon atoms in a silica-based sol containing silica-based particles with a specific surface area of at least 300 square meters per gram of silica and concentrating the aqueous silica-based sol obtained to a specific surface area of at least 100 square meters per gram of aqueous sol, the obtained silica-based sol having a molar ratio of SiO2 to N of from 2:1 to 40:1.

Process for the production of paper from an aqueous suspension containing cellulosic fibres, and optional fillers, which comprises adding to the suspension an aqueous silica-based sol comprising an organic nitrogen-containing compound having up to 25 carbon atoms and at least one charged organic polymer, forming and draining the suspension on a wire.

Aqueous silica-based sol comprising a nitrogen-containing organic compound and silica-based particles with a specific surface area of at least 300 square meters per gram of silica and having an S-value within the range of from 10 to 60%, the silica-based particles having colloidal borosilicate, aluminum-modified silica or aluminum silicate.