Manufacture of paper and paperboard

摘要

A process for making paper or paperboard wherein the process comprises forming a cellulosic suspension, flocculating the suspension, draining the suspension on a screen to form a sheet and then drying the sheet. The suspension is flocculated using a flocculation system comprising a siliceous material and organic microparticles, which have a diameter of less than 750 nanometer, wherein the cellulosic suspension is treated by inclusion of a further flocculating material into the suspension prior to introducing the polymeric microparticles and siliceous material wherein said further flocculating material is a cationic material being represented by a natural or synthetic polymer being selected from the group consisting of water soluble, substantially linear or branched polymer, a crosslinked polymer or a mixture of a crosslinked and water soluble polymer. Organic microparticles are formed of anionic copolymers containing up to 99 parts by weight of a non-ionogenic monomer and from 100 to 1 part by weight of an anionic monomer, based on the total weight of both the anionic and non-ionogenic monomers.