Patent ID: 7608644

Claim:
An aqueous silica-containing composition comprising an anionic naphthalene sulphonate formaldehyde condensate and aggregated or microgel formed anionic silica-based particles, wherein the composition has a weight ratio of naphthalene sulphonate formaldehyde condensate to total amount of silica-based particles within the range of from 0.2:1 to 99:1, and wherein the amount of naphthalene sulphonate formaldehyde condensate and total amount of silica-based particles is at least 0.01% by weight, based on the total weight of the aqueous silica-containing composition, and with the provisos that the composition contains substantially no cellulose-reactive sizing agent and the composition is not a cellulosic papermaking stock, wherein the anionic naphthalene sulphonate formaldehyde condensate has a conductivity of less than 15 mS/cm measured at an anionic naphthalene sulphonate formaldehyde condensate content of 10% by weight.