Freeness of paper products

Abstract

The present invention provides for the optimisation of conditions for treating pulp with a catalyst and hydrogen peroxide to produce a Freeness value (SR) in a web produced from the treated pulp such that the energy required in mechanical agitation of the pulp is reduced.

1 . A method for the treatment of a cellulose pulp suspension comprising:
 (i) subjecting cellulose pulp fibres to an aqueous solution of a preformed manganese transition metal catalyst and hydrogen peroxide at pH from 6 to 13, wherein the manganese transition metal catalyst is present at a concentration from 0.0001 to 1 kg/tonne oven-dry pulp, and the hydrogen peroxide is present at a concentration from 0.1 to 100 kg/tonne oven-dry pulp;   (ii) subjecting the cellulose pulp fibres treated by step (i) to a refining process until a Shopper Riegler (SR) value of from 10 to 90° is reached and the resultant pulp is processed into paper, tissue or board; and   wherein the manganese transition metal catalyst is a mononuclear Mn(II), Mn(III), Mn(IV) or dinuclear Mn(II)Mn(II), Mn(II)Mn(III), Mn(III)Mn(III), Mn(III)Mn(IV) or Mn(IV)Mn(IV) transition metal catalyst, having a ligand of formula (I):   
       
         
           
           
               
               
           
         
         
           p is 3; 
           R is independently selected from the group consisting of: hydrogen, C 1 -C 6 -alkyl, CH 2 CH 2 OH, CH 2 COOH, and pyridin-2-ylmethyl; and 
           R 1 , R 2 , R 3 , and R 4  are independently selected from the group consisting of: H, C 1 -C 4 -alkyl, and C 1 -C 4 -alkylhydroxy. 
         
       
     
     
         2 . The method according to  claim 1 , wherein the manganese transition metal catalyst is present at a concentration from 0.0005 to 0.2 kg/tonne oven-dry pulp and the hydrogen peroxide is present at a concentration from 0.1 to 25 kg/tonne oven-dry pulp. 
     
     
         3 . The method according to  claim 1 , wherein R is independently selected from the group consisting of: hydrogen, CH 3 , C 2 H 5 , CH 2 CH 2 OH, and CH 2 COOH. 
     
     
         4 . The method according to  claim 1 , wherein R, R 1 , R 2 , R 3 , and R 4  are independently selected from: H and Me. 
     
     
         5 . The method according to  claim 1 , wherein the catalyst is derived from 1,4,7-trimethyl-1,4,7-triazacyclononane (Me 3 -TACN). 
     
     
         6 . The method according to  claim 1 , wherein the pulp is subjected to a refining process until a Shopper Riegler (SR) value of from 10 to 30° is reached, to produce tissue paper. 
     
     
         7 . The method according to  claim 1 , wherein the pulp is subjected to a refining process until a Shopper Riegler (SR) value of from 15 to 50° is reached, to produce printing and writing paper. 
     
     
         8 . The method according to  claim 1 , wherein the pulp is subjected to a refining process until a Shopper Riegler (SR) value of from 50 to 90° is reached, to produce tracing and transparent paper. 
     
     
         9 . The method according to  claim 1 , wherein mechanical pulp is subjected to a refining process until a Shopper Riegler (SR) value of from 20 to 80° is reached. 
     
     
         10 . The method according to  claim 1 , wherein the catalyst and hydrogen peroxide is added to the cellulose pulp fibres in a device selected from the group consisting of: a pulper, a high density pulp chest, a pulp washer, a pulp latency chest, a pulp levelling chest, a pulp mixing chest, a pulp refiner, a pulp dilution tank, and a pulp stock chest. 
     
     
         11 . The method according to  claim 10 , wherein the pulp refiner is selected from the group consisting of: beaters, Hollander beaters, shallow-angle conical refiners, medium-angle conical refiners, wide-angle conical refiners, single-disc refiners, double-disc refiners, and multi-disc refiners. 
     
     
         12 . The method according to  claim 1 , further comprising bleaching the cellulose pulp fibres, wherein the manganese transition metal catalyst and hydrogen peroxide in step (i) is added during the bleaching. 
     
     
         13 . The method according to  claim 12 , wherein the manganese transition metal catalyst and hydrogen peroxide is added to the cellulose pulp fibres in a device selected from the group consisting of a pulp mixer, a pulp bleaching tower, a pulp retention pipe, a pulp washer, a pulp storage tower, a steam mixer, and a pulper. 
     
     
         14 . The method according to  claim 1 , wherein the cellulose pulp fibres have been previously subjected to a bleaching stage. 
     
     
         15 . The method according to  claim 1 , wherein the aqueous solution of step (i) further comprises from 0.01 to 50 kg/ton oven dry pulp of an organic sequestrant selected from: an aminophosphonate sequestrant and a carboxylate sequestrant. 
     
     
         16 . The method according to  claim 15 , wherein the organic sequestrant is selected from the group consisting of: diethylenetriamine penta(methylene phosphonic acid sodium salt), MGDA (methylglycindiacetate), GLDA (glutamic acid diacetate), IDS (iminodissucinate), EDDS (ethylenediaminedisuccinate), EDTA (ethylenediamine-tetraacetate), and DTPA (diethylenetriamine-pentaacetate). 
     
     
         17 . A method according to  claim 1 , wherein an energy input into the refining process is monitored and based upon an energy input threshold for cellulose pulp fibres to be processed into paper, tissue, or board. 
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . Paper, tissue or board obtained by a method according to  claim 1 .