Method of providing a paper fibre composition

Abstract

The present invention relates to a method of production of a paper fibre composition, comprising the steps of: a) Providing a vessel, b) Providing Na2S03 in the range of 12-122 kg/bdt combined with NaOH in the range of 0-97 kg/bdt, or NaHSO3 in the range of 10-100 kg/bdt combined with NaOH in the range of 10-100 kg/bdt to said vessel, c) Providing wood, preferably softwood chips to said vessel for pre-treatment, d) Providing heat and pressure to said vessel in order be able control the vessel to have a temperature T comprised in the range of 160° C.-184° C., e) Controlling the retention time t for the wood chips, in relation to the temperature T of the content of the vessel, wherein T is controlled to be within the range of step d) and t is controlled to be in the range of 2-27 min, preferably in the range of 2-25 min, more preferred in the range of 5-20 min, f) Providing a defibration device coupled to the outlet of said vessel, the defibriation device being a refiner, mill, defibrator, fiberizer, or the like, g) Providing the pre-treated wood chips to the defibration device, h) Providing an energy consumption of 75-1000 kWh/bdt in said defibration device. The invention also relates to a paper fibre composition prepared by the method and a paper or paperboard or molded pulp made from the paper fibre composition.

1 . Method of production of a paper fibre composition, comprising the steps of:
 a) Providing a vessel,   b) Providing Na 2 SO 3  in the range of 12-122 kg/bdt combined with NaOH in the range of 0-97 kg/bdt, or NaHSO 3  in the range of 10-100 kg/bdt combined with NaOH in the range of 10-100 kg/bdt to said vessel,   c) Providing wood, preferably softwood chips to said vessel for pre-treatment,   d) Providing heat and pressure to said vessel in order be able control the vessel to have a temperature T comprised in the range of 160° C.-184° C.,   e) Controlling the retention time t for the wood chips, in relation to the temperature T of the content of the vessel, wherein T is controlled to be within the range of step d) and t is controlled to be in the range of 2-27 min, preferably in the range of 2-25 min, more preferred in the range of 5-20 min,   f) Providing a defibration device coupled to the outlet of said vessel, the defibriation device being a refiner, mill, defibrator, fiberizer, or the like,   g) Providing the pre-treated wood chips to the defibration device,   h) Providing an energy consumption of 75-1000 kWh/bdt in said defibration device.   
     
     
         2 . Method according to  claim 1 , wherein the amounts of step c) is controlled to be within the ranges of: 
       
         
           
                 
                 
                 
                 
               
                     
                 
                   Na 2 SO 3   
                   24-97 kg/bdt combined with NaOH 
                   0-73 
                   kg/bdt or 
                 
                   NaHSO 3   
                   20-80 kg/bdt combined with NaOH 
                   20-80 
                   kg/bdt. 
                 
                     
                 
             
                
               
               
                
                
                
               
            
           
         
       
     
     
         3 . Method according to  claim 1 , wherein the amounts of step c) is kept within the ranges of: 
       
         
           
                 
                 
                 
                 
               
                     
                 
                   Na 2 SO 3   
                   12-57 kg/bdt combined with NaOH 
                   0-44 
                   kg/bdt or, 
                 
                   NaHSO 2   
                   10-47 kg/bdt combined with NaOH 
                   10-47 
                   kg/bdt. 
                 
                     
                 
             
                
               
               
                
                
                
               
            
           
         
       
     
     
         4 . Method according to any of the claims above, wherein paper test sheets made from the paper fibre composition gives a Tensile index of 18-150 Nm/g, preferably of 25-150 Nm/g, even more preferred of 40-150 Nm/g. 
     
     
         5 . Method according to any of the  claims 1  or  2  or  4  above wherein the following recipes are applied:
 30-80 kg/bdt NaHSO 3 ; 28-56 kg/bdt NaOH; t=5-20 min; T=160-180° C.; or 
 36-97 kg/bdt Na2SO3; 0-45 kg/bdt NaOH; t=5-20 min; T=160-180° C. 
 
     
     
         6 . Method according to any of the claims above wherein the temperature t is comprised in the range 175-184° C. 
     
     
         7 . Method according to any of the claims above wherein the temperature t is comprised in the range 160-175° C. 
     
     
         8 . Method according to any of the claim above wherein there is a further step provided
 i) a further treatment step where further defibration is added, in the range of 1-2500 kWh/bdt, to said paper fibre composition.   
     
     
         9 . Paper fibre composition made according to the method according to any of the  claims 1 - 8 . 
     
     
         10 . Paper or paperboard or molded pulp, comprising a paper fibre composition according to  claim 9 . 
     
     
         11 . Paper or paperboard or molded pulp according to  claim 10 , wherein the paper fibre composition is directly used in said paper or paperboard. 
     
     
         12 . Paper or paperboard or molded pulp according to any of the  claims 10 - 11 , wherein the Paper or paperboard or molded pulp comprises the paper fibre composition according to  claim 9 , but that the paper fibre composition is exposed to further treatment in order to change the properties, wherein said further treatment comprises further mechanical treatment, such that the paper fibre composition has a Tensile index that is higher than 50 Nm/g but lower than 150 Nm/g.