Process for producing differentiated cellulose fibers comprising an enzymatic treatment in association with an acid step

Abstract

The present invention refers to a process for producing cellulose of market eucalyptus fibers having distinct features through the use of at least one enzymatic treatment with hydrolytic enzymes, such as for example, xylanases, cellulases or mixtures thereof, in association to at least one acidic treatment step. These treatments may be applied into different steps of the fibers process producing, wherein all of them happen before drying.

1 . A process for producing cellulose fibers, characterized by comprising the association of at least one enzymatic treatment with at least one acid step throughout the process for obtaining cellulose fibers. 
     
     
         2 . The process according to  claim 1 , characterized in that the enzymatic treatment uses at least one hydrolytic enzyme. 
     
     
         3 . The process according to  claim 2 , characterized in that the hydrolytic enzyme is selected from the group consisting of cellulases, xylanases and mixtures thereof. 
     
     
         4 . The process according to any one of  claims 1  to  3 , characterized in that the retention time ranges from 40 to 240 minutes, the pH of the medium ranges from 5.5 to 8.5 and medium temperature ranges from 40 to 90° C., and hydrolytic enzyme charge ranges from 0.10 to 2.0 kilogram of enzyme/ton cellulose. 
     
     
         5 . The process according to any one of  claims 1  to  4 , characterized in that medium temperature during the enzymatic treatment ranges from 50 to 90° C. when the hydrolytic enzyme is xylanase. 
     
     
         6 . The process according to any one of  claims 1  to  4 , characterized in that medium temperature during the enzymatic treatment ranges from 40 to 80° C. when the hydrolytic enzyme is cellulase. 
     
     
         7 . The process according to any one of  claims 1  to  4 , characterized in that medium temperature during the enzymatic treatment ranges from 40 to 80° C. when the hydrolytic enzyme is a mixture of xylanases and cellulases. 
     
     
         8 . The process according to any one of  claims 1  to  7 , characterized in that the enzymatic treatment is applied before the bleaching sequence of the fibers and the retention time is from 40 to 240 minutes. 
     
     
         9 . The process according to any one of  claims 1  to  7 , characterized in that the enzymatic treatment is applied after the bleaching sequence of the cellulose fibers and the retention time is from 40 to 240 minutes in a reactor before the market cellulose drying process. 
     
     
         10 . The process according to any one of  claims 1  to  9 , characterized in that the acid step is applied sequentially before or after the enzymatic treatment. 
     
     
         11 . The process according to any one of  claims 1  to  7 , characterized in that the enzymatic treatment is applied during the bleaching sequence in order to differentiate the properties of the cellulose fibers. 
     
     
         12 . The process according to any one of  claims 1  to  11 , characterized in that in the acid step, the time retention ranges from 20 to 200 minutes, the temperature in the medium ranges from 80 to 95° C. and the pH of the medium ranges from 3 to 4.5. 
     
     
         13 . The process according to any one of  claims 1  to  12 , characterized in that the association between the enzymatic treatment and the acid step occurs with or without washing of the cellulose fibers between the same. 
     
     
         14 . The process according to any one of  claims 1  to  13 , characterized in that the used fibers are cellulose fibers of the eucalyptus market. 
     
     
         15 . Cellulose fibers characterized by being produced by a process as defined in any one of  claims 1  to  14 .