Aqueous composition

A method for preparation of an aqueous, which comprises mixing colloidal anionic silica-based particles with anionic organic polymeric particles obtained by polymerising one or more ethylenically unsaturated monomers together with one or more polyfunctional branching agents and/or a polyfunctional crosslinking agents, thereby obtaining an aqueous composition containing the colloidal anionic silica-based particles and the anionic organic polymeric particles in an amount of at least 0.01% by weight based on the total weight of the aqueous composition.

A process for production of paper from an aqueous suspension containing cellulosic fibers, and optionally fillers, which process comprises adding to the fiber 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 m2/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 within the range of from 1 to 45% 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.