Patent ID: 8052841

Claim:
A process for the manufacturing of paper, said process comprising the steps of: pre-treating a portion of a filler amount intended for a stock with anionic colloidal particles having an average particle size in water of less than 100 nm and having a specific area (BET) in the range of 30-1,000 m 2 /g by combining an aqueous slurry or a sol of said inorganic colloidal particles and a filler slurry having a concentration of 20-50%, wherein the weight proportion of inorganic colloidal particles in the total weight of said particles and the pre-treated portion of filler amount is in the range of 0.5-20 kg/t and wherein a stock formed by the combination has a total consistency in the range of 3-20 g/l, combining the aqueous slurry of pre-treated filler with an aqueous suspension containing cellulose fibers to form the stock, comprising the steps of: treating the formed stock at least with a cationic retention agent which is a cationic polyacrylamide or acrylamide copolymer having a molecular weight of at least 500,000 g/mol, and filtering the treated stock to form a web and drying the web to form said paper.