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 id 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.  
     
     
         9 . The paper or paper board web according to  claim 8  having from 10 to 20% bulk enhancement.  
     
     
         10 . A process for manufacturing brightened 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.    
     
     
         11 . The process according to  claim 10 , wherein the pulp is a mixture of mechanical and chemical fibers.  
     
     
         12 . The process according to  claim 11 , wherein the mechanical fibers have a Canadian Standard Freeness of at least 200 csf and a shive content of not more than 0.5%.  
     
     
         13 . The process according to  claim 12 , wherein the mechanical fibers are CTMP.  
     
     
         14 . The process according to  claim 13 , further comprising 
 pre-treating the chemical fibers with at least one bleaching stage in the presence of at least one chlorine based bleaching agent.    
     
     
         15 . The process according to  claim 14 , wherein the pulp comprises from 20 to 80 wt % of mechanical fibers and from 20 to 80 wt % to of chemical fibers based upon the total dry weight of the fibers.  
     
     
         16 . The process according to claims  15 , wherein from 0.5 to 10 wt % of bleaching agent based upon the total dry weight of the pulp and from 0.1 to 2 wt % of optical brightener based upon the total dry weight of the pulp is used in the treatment of the pulp.  
     
     
         17 . The process according to  claim 16 , wherein said treating is performed in the presence of from 1.0 to 8.0 wt % of stabilizer based upon the total dry weight of the pulp.  
     
     
         18 . The process according to  claim 17 , wherein the treating is for a time period of from 0.5 to 10 hours at a temperature of from 25 to 120° C., at a fiber consistency of at least 10%.  
     
     
         19 . A mixture of mechanical and chemical fibers made from the process according to  claim 18  and having an ISO brightness that is at least 90 ISO points.  
     
     
         20 . A paper or paperboard substrate, comprising the mixture of mechanical and chemical fibers according to  claim 19  and having an ISO brightness that is at least 90 ISO points.