Patent ID: 8262858

Claim:
A method of enhancing the effectiveness of optical brighteners in papermaking processes comprising: i) providing bleached pulp; ii) forming an aqueous stock suspension comprising the bleached pulp; iii) draining the stock suspension to form a sheet; iv) treating the sheet with an oxidant composition comprising one or more oxidizing agents at about 0.0005 to about 2 weight percent on oven-dried pulp, one or more optical brighteners, and optionally one or more chelants, optionally one or more reducing agents, or combinations thereof, and wherein said oxidizing agents are selected from the group consisting of hydrogen peroxide, organic peroxyacids, inorganic peroxides, superoxides and peroxide-superoxides, organic and inorganic peroxyacids and salts thereof, peroxyhydrates, water-soluble organic peroxides, nitrosodisulfonates, hypochlorites, hypobromites, chlorites, chlorates, bromates, perehlorates, chlorine dioxide, chloroamines, chloroamides, chlorosulfamides, bromoamines, bromoamides, bromosulfamides, chlorosulfonic acid, bromosulfonic acid and chlorine and wherein said bleached pulp material has a minimum ISO brightness of 84.4 and the oxidant composition excludes starch when the oxidant comprises hydrogen peroxide, organic peroxyacids, inorganic peroxides, superoxides and peroxide-superoxides, organic and inorganic peroxyacids and salts thereof, peroxyhydrates, and water-soluble organic peroxides; and v) drying the sheet, wherein the aqueous stock suspension comprises a thick stock and a thin stock and the oxidizing agents are added to the thick stock and the optical brighteners are added to the thin stock.