Process for making pulp

Abstract

A process for making pulp includes providing plant fiber raw material. The plant fiber raw material can be wood fiber or gramineae plant fiber. The plat fiber raw material is cooked to make a pulp. A TEMPO catalytic oxidation system is added to the pulp to oxidize the pulp fiber. The oxidized pulp fiber is then bleached.

1 . A process for making pulp, comprising:
 providing plant fiber raw material;   cooking the plant fiber raw material to make a pulp;   adding a TEMPO catalytic oxidation system into the pulp to oxidize the pulp fiber; and   bleaching the oxidized pulp.   
     
     
         2 . The process as claimed in  claim 1 , wherein the plant fiber raw material is selected from the group consisting of wood fiber, gramineae plant fiber, and any combination thereof 
     
     
         3 . The process as claimed in  claim 1 , wherein the process further includes a step of washing the pulp and a step of filtering the pulp after the step of cooking and before the step of adding a TEMPO catalytic oxidation system into the pulp. 
     
     
         4 . The process as claimed in  claim 1 , wherein the process further includes a step of bleaching the pulp after the step of cooking the plant fiber raw material, the TEMPO catalytic oxidation system is added into the pulp after the step of bleaching the pulp. 
     
     
         5 . The process as claimed in  claim 1 , wherein the TEMPO catalytic oxidation system contains a catalyst, an assistant catalyst, and an oxidant; the catalyst is TEMPO ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) or a derivative thereof; the weight of catalyst is about 0.01% to about 2% of the dry weight of the pulp fiber; the assistant catalyst consists of iodides, bromides, borates, or a mixture thereof; the weight of assistant catalyst is about 0.1% to about 10% of the dry weight of the pulp fiber; the oxidant is chlorine dioxide, hydrogen peroxide, chlorite, or hypochlorite; the content of the oxidant is in the range from about 0.2 mmol to about 1.5 mmol per gram of pulp fiber by dry weight. 
     
     
         6 . The process as claimed in  claim 5 , wherein the derivative of TEMPO is  4 -(acetylamino)-TEMPO. 
     
     
         7 . The process as claimed in  claim 1 , wherein the pH value of the pulp is kept to be between about 9.5 and about 10.5, and the temperature of the pulp is kept to be about 0° C. to about 110° C. during the oxidation process. 
     
     
         8 . The process as claimed in  claim 1 , wherein the pH value of the pulp is kept to be between about 9.5 and about 10.5, and the temperature of the pulp is kept to be about 20° C. to about 70° C. during the oxidation process. 
     
     
         9 . The process as claimed in  claim 1 , wherein the oxidation step is performed for a time period from about 10 to about 180 min. 
     
     
         10 . The process as claimed in  claim 1 , wherein the pulp contains carboxyl groups and aldehyde groups; the content of the carboxyl groups in the pulp is in the range from about 0.1 mmol to about 1.5 mmol per gram of pulp fiber by dry weight; the content of the aldehyde groups in the pulp is in the range from about 0.05 mmol to about 0.7 mmol of per gram pulp fiber by dry weight. 
     
     
         11 . A process for making pulp, comprising:
 providing plant fiber raw material;   cooking the plant fiber raw material to make a pulp;   adding an oxidant into the pulp to oxidize the pulp fiber, the oxidant being selected from the group consisting of periodate, nitrite, sodium chlorate, and sodium hypochlorite; and   bleaching the oxidized pulp.   
     
     
         12 . The process as claimed in  claim 11 , wherein the plant fiber raw material is selected from the group consisting of wood fiber, gramineae plant fiber, and any combination thereof. 
     
     
         13 . The process as claimed in  claim 11 , wherein the process further includes a step of washing the pulp and a step of filtering the pulp after the step of cooking and before the step of adding an oxidant into the pulp. 
     
     
         14 . The process as claimed in  claim 11 , wherein the process further includes a step of bleaching the pulp after the step of cooking the plant fiber raw material, the oxidant is added into the pulp after the step of bleaching the pulp. 
     
     
         15 . The process as claimed in  claim 11 , wherein the pulp contains carboxyl groups and aldehyde groups; the content of the carboxyl groups in the pulp is in the range from about 0.1 mmol to about 1.5 mmol per gram of pulp fiber by dry weight; the content of the aldehyde groups in the pulp is in the range from about 0.05 mmol to about 0.7 mmol per gram of pulp fiber by dry weight.