Method for the production of improved pulp

Abstract

Compositions and method for improving properties of pulp produced or reducing the digester cycle time in alkaline chemical pulping processes in which an effective amount of at least one selected phosphonate or carboxylate compound or mixtures thereof is admixed with the alkaline aqueous mixture in the digester of the chemical pulping process. The compositions and method are especially well suited for use in the Kraft pulping process.

1 . A method for improving properties of pulp produced, reducing the digester cycle time, or reducing the pulping or bleaching chemicals required in alkaline chemical pulping processes comprising adding to the alkaline aqueous mixture in the digester of said chemical pulping process, an effective amount of said at least one compound having the formula:  
       (MOOC—CH 2 ) 2 —N(CH 2 ) 2 —N(CH 2 COOM)-(CH 2 ) 2 N—(CH 2 COOM) 2 ,  
     wherein M is independently selected from hydrogen, alkali metal, alkaline earth metal or ammonium.  
   
   
       2 . The method of  claim 1  wherein M is independently selected from hydrogen or an alkali metal.  
   
   
       3 . The method of  claim 2  wherein M is sodium or potassium when M is an alkali metal.  
   
   
       4 . The method of  claim 1  wherein said compound is a mixture of at least one compound having the formula (MOOC—CH 2 ) 2 —N(CH 2 ) 2 —N(CH 2 COOM)-(CH 2 ) 2 N—(CH 2 COOM) 2  with at least one compound selected from the group consisting of phosphonates having the formula:  
       X 2 NCH 2 PO 3 M 2 , and  
     phosphonates having the formula:  
     
       
         
         
             
             
         
       
     
     wherein X is independently selected from H, R, —CH 2 PO 3 M 2  wherein R is an alkyl group or —NX 2  substituted alkyl group having 2 to 6 carbon atoms, R′ is an alkyl group having 1 to 17 carbon atoms and R′ is optionally branched, optionally unsaturated, and optionally substituted with SO 3 M, Y is selected from —PO 3 M 2 , H or R′, and Z is selected from —OH or —NR 1 R 2  wherein R 1  and R 2  are independently selected from hydrogen or alkyl having 1 to 2 carbon atoms.  
   
   
       5 . The method of  claim 1  wherein said chemical pulping process is a Kraft process.  
   
   
       6 . The method of  claim 1  wherein the pulp from said digester is recovered, washed and subsequently bleached.  
   
   
       7 . The method of  claim 6  wherein said washed pulp is bleached using a bleaching process selected from DED, DEDED, DE op D, DE op P, ODED, OZEP, DEDP or CEH.  
   
   
       8 . The method of  claim 1  wherein the pH of said alkaline aqueous mixture is at least 9.  
   
   
       9 . The method of  claim 8  wherein the pH of said alkaline aqueous mixture is about 12 to 14.  
   
   
       10 . The method of  claim 1  wherein said alkaline aqueous mixture further comprises anthroquinone.  
   
   
       11 . A method for improving properties of pulp produced in alkaline chemical pulping processes comprising adding to the alkaline aqueous mixture in the digester of said chemical pulping process, an effective amount of at least one compound having the formula:  
       (MOOC—CH 2 ) 2 —N(CH 2 ) 2 —N(CH 2 COOM)-(CH 2 ) 2 N—(CH 2 COOM) 2 ,  
     wherein M is independently selected from hydrogen, alkali metal, alkaline earth metal or ammonium.  
   
   
       12 . A method for reducing the digester cycle time or reducing the pulping or bleaching chemicals required in alkaline chemical pulping processes comprising adding to the alkaline aqueous mixture in the digester of said chemical pulping process an effective amount of at least one compound having the formula:  
       (MOOC—CH 2 ) 2 —N(CH 2 ) 2 —N(CH 2 COOM)-(CH 2 ) 2 N—(CH 2 COOM) 2 ,  
     wherein M is independently selected from hydrogen, alkali metal, alkaline earth metal or ammonium  
   
   
       13 . A pulp prepared according to the process of  claim 1 .  
   
   
       14 . A pulp prepared according to the process of  claim 6 .  
   
   
       15 . An aqueous composition for improving properties of pulp produced, reducing the digester cycle time, or reducing the pulping or bleaching chemicals required in alkaline chemical pulping processes, said composition comprising the alkaline composition of the digester of said process and an effective amount of at least one compound having the formula:  
       (MOOC—CH 2 ) 2 —N(CH 2 ) 2 —N(CH 2 COOM)-(CH 2 ) 2 N—(CH 2 COOM) 2    
     wherein M is independently selected from hydrogen, alkali metal, alkaline earth metal or ammonium.  
   
   
       16 . The composition of  claim 15  wherein M is independently selected from hydrogen or an alkali metal.  
   
   
       17 . The composition of  claim 16  wherein M is sodium or potassium when M is an alkali metal.  
   
   
       18 . The composition of  claim 15  wherein said compound is a mixture of at least one compound of having the formula:  
       (MOOC—CH 2 ) 2 —N(CH 2 ) 2 —N(CH 2 COOM)-(CH 2 ) 2 N—(CH 2 COOM) 2 ,  
     with at least one compound selected from the group consisting of phosphonates having the formula:  
       X 2 NCH 2 PO 3 M 2 , and  
     phosphonates having the formula:  
     
       
         
         
             
             
         
       
     
     wherein X is independently selected from H, R, —CH 2 PO 3 M 2  wherein R is an alkyl group or —NX 2  substituted alkyl group having 2 to 6 carbon atoms, R′ is an alkyl group having 1 to 17 carbon atoms and R′ is optionally branched, optionally unsaturated, and optionally substituted with SO 3 M, Y is selected from —PO 3 M 2 , H or R′, and Z is selected from —OH or —NR 1 R 2  wherein R 1  and R 2  are independently selected from hydrogen or alkyl having 1 to 2 carbon atoms.  
   
   
       19 . The composition of  claim 15  wherein the pH of said alkaline aqueous mixture is at least 9.  
   
   
       20 . The composition of  claim 19  wherein the pH of said alkaline aqueous mixture is about 12 to 14.  
   
   
       21 . The composition of  claim 15  wherein said alkaline aqueous mixture further comprises anthroquinone.  
   
   
       22 . An aqueous composition for improving properties of pulp produced in alkaline chemical pulping processes, said composition comprising the alkaline composition of the digester of said process and an effective amount of at least one compound having the formula:  
       (MOOC—CH 2 ) 2 —N(CH 2 ) 2 —N(CH 2 COOM)-(CH 2 ) 2 N—(CH 2 COOM) 2 ,  
     wherein M is independently selected from hydrogen, alkali metal, alkaline earth metal or ammonium.  
   
   
       23 . An aqueous composition for reducing the digester cycle time or reducing the pulping or bleaching chemicals required in alkaline chemical pulping processes, said composition comprising the alkaline composition of the digester of said process and an effective amount of at least one compound having the formula:  
       (MOOC—CH 2 ) 2 —N(CH 2 ) 2 —N(CH 2 COOM)-(CH 2 ) 2 N—(CH 2 COOM) 2 ,  
     wherein M is independently selected from hydrogen, alkali metal, alkaline earth metal or ammonium.