Process for manufacturing pulp, paper and paperboard products

Abstract

A process for bleaching mechanical wood pulp is provided comprising subjecting the wood pulp to at least one bleaching stage with one or more bleaching agents in the presence of one or more optical brightening agent, wherein the bleaching agents are selected from the group consisting of oxidative bleaching agents other than chlorine based bleaching agents such as chlorine dioxide, elemental chlorine or a combination thereof, reductive bleaching agents or any combination of two or more thereof.

1 . An improved process for manufacturing brightened mechanical pulp comprising treating the pulp with one or more optical brightening agents in the presence of one or more bleaching agents, wherein the bleaching agents are selected from the group consisting of bleaching agents other than chlorine based bleaching agents. 
     
     
         2 . A process according to  claim 1  wherein said pulp is treated in the presence of active bleaching agents. 
     
     
         3 . A process according to  claim 1  wherein said pulp is treated in the presence of spent bleaching agents. 
     
     
         4 . A process according to  claim 1  wherein said bleaching agent comprises peroxide. 
     
     
         5 . A bleached mechanical pulp having an ISO brightness equal to or greater than about 90 and pulp mixtures comprising such mechanical pulp. 
     
     
         6 . An improved process for forming bleached mechanical pulp of the type comprising:
 (a) a mechanical refining stage wherein wood chips are mechanically refined to form mechanical refined wood pulp; and   (b) a bleaching stage wherein said mechanical refined wood pulp is bleached in one or more bleaching stages to form a bleached mechanical refined wood pulp;   the improvement comprising bleaching the mechanical refined wood pulp with one or more bleaching agents in the presence of one or more optical brightening agent, said bleaching agents selected from the group consisting of oxidative bleaching agents other than chlorine based bleaching agents such as chlorine dioxide, elemental chlorine or a combination thereof, reductive bleaching agents or any combination of two or more thereof.   
     
     
         7 . An improved pulping and paper making process of the type comprising:
 (a) a mechanical refining stage wherein wood chips are mechanically refined to form mechanical refined wood pulp,   (b) a bleaching stage wherein said mechanically refined wood pulp is bleached in one or more bleaching stages to form bleached mechanical refined aspen wood pulp,   (c) a furnish forming stage wherein an aqueous paper making stock furnish comprising said bleached mechanical refined wood pulp is formed;   (d) a furnish depositing stage wherein said furnish is deposited on a forming wire of a paper making machine to form a wet paper web; and   (e) a wet paper web drying stage wherein said wet paper web to form a first dried paper web,   the improvement comprising bleaching the mechanical refined wood pulp with one or more bleaching agents in the presence of one or more optical brightening agent, said bleaching agents selected from the group consisting of oxidative bleaching agents other than chlorine based bleaching agents such as chlorine dioxide, elemental chlorine or a combination thereof, reductive bleaching agents or any combination of two or more thereof.   
     
     
         8 . A paper or paper board web comprising bleached mechanical pulp having an ISO brightness equal to or greater than about 90.