One stage method for acid metal removal and bleach

Abstract

There is provided a process for chemically pretreating reclaimed cellulose fibres to be used in the production of moulded bodies from regenerated cellulose, wherein the pretreatment includes one stage, in which stage acid metal removal and acid oxidative bleaching are carried out together. Advantages include that the propensity of the regenerated cellulose to clog when flowing in a tube and through a nozzle is reduced. This is believed to be an effect of an efficient metal removal. The need for additional bleaching steps and/or metal removing steps is reduced or even eliminated. A one-stage method is more efficient, faster and less costly compared to a multi-stage method according to the prior art. From an environmental perspective, acidic metal removal is preferred over removal by chelating agents such as EDTA.

1 . A process for chemically pretreating reclaimed cellulose fibres to be used in production of moulded bodies from regenerated cellulose, wherein the pretreatment includes one stage, in which stage acid metal removal and acid oxidative bleaching are carried out together. 
     
     
         2 . The process according to  claim 1 , wherein at least one acid selected from the group consisting of hydrochloric acid, formic acid, citric acid, acetic acid or any mixture thereof, is present during the stage. 
     
     
         3 . The process according to  claim 1 , wherein at least one weak acid with a pKa above 3 and below 7 is present during the one stage. 
     
     
         4 . The process according to  claim 1 , wherein acetic acid is present during the one stage. 
     
     
         5 . The process according to  claim 1 , wherein sulphuric acid is not present during the one stage. 
     
     
         6 . The process according to  claim 1 , wherein sulphuric acid is present during the one stage. 
     
     
         7 . The process according to  claim 1 , wherein hydrogen peroxide is present during the one stage. 
     
     
         8 . The process according to  claim 1 , wherein ozone is present during the one stage. 
     
     
         9 . The process according to  claim 1 , wherein the one stage with both acid metal removal and acid oxidative bleaching is the only acid chemical metal removal step in the process. 
     
     
         10 . The process according to  claim 1 , wherein the one stage is carried out during a time in the interval from 1 to 60 minutes. 
     
     
         11 . The process according to  claim 1 , wherein the temperature during the one stage is in the interval 30-75° C. 
     
     
         12 . The process according to  claim 1 , wherein a subsequent production of moulded bodies from regenerated cellulose is carried out with one method selected from the group consisting of the Viscose process, the Lyocell process, or the Modal process. 
     
     
         13 . The process according to  claim 1 , wherein the one stage is carried out during a time in the interval from 1 to 120 minutes. 
     
     
         14 . The process according to  claim 1  wherein the pH during the one stage is in the interval 1.5 to 4.5.