Patent ID: 7691234

Claim:
A process for production of paper from an aqueous suspension containing cellulosic fibres, and optionally fillers, which process comprises adding to the fibre suspension a cationic polymer and an aqueous composition comprising anionic organic polymeric particles and colloidal anionic silica-based particles having a specific surface area within the range from 300 to 1000 m 2 /g, the anionic organic polymeric particles being obtained by polymerising one or more ethylenically unsaturated monomers together with one or more polyfunctional branching agents and/or polyfunctional crosslinking agents, the anionic organic polymeric particles and the colloidal anionic silica-based particles being present in the aqueous composition in an amount of at least 0.01% by weight based on the total weight of the aqueous composition, the colloidal anionic silica-based particles being silica, aluminium-modified silica or amine-modified silica and being contained in a sol having an S-value within the range from 5 to 60% before mixing with the anionic organic polymeric particles.