Biological De-Inking Method

Abstract

A method of de-inking wastepaper by pulping the paper in the presence of an enzyme is disclosed. The enzyme dislodges the ink particles from the paper fibers. The preferred enzymes are the acid resistant carbohydrases. The de-inking medium is an aqueous solution of the enzyme, preferably maintained at a pH less than about 7 and at a temperature between about 20° C. and about 60° C. No conventional chemical de-inking agents are required. The dislodged ink particles may be removed by any conventional method, such as flotation or washing.

1 - 20 . (canceled) 
     
     
         21 . A method of de-inking waste printed paper, comprising
 a) pulping at a pH between 3 and 8 waste printed paper with an enzyme capable of dislodging ink particles from the waste printed paper in an aqueous medium at a pH between 3 and 8, wherein ink is dislodged from the waste printed paper by action of the enzyme; and   b) removing the dislodged ink particles from the resulting pulp containing medium.   
     
     
         22 . The method of  claim 21  wherein dislodged ink particles are removed by flotation. 
     
     
         23 . The method of  claim 21  wherein dislodged ink particles are removed by washing. 
     
     
         24 . The method of  claim 21  wherein the amount of enzyme used is in the range of 0.005 to 5 percent-by-weight based on the dry weight of the wastepaper. 
     
     
         25 . The method of  claim 21 , wherein said enzyme is selected from the class consisting of cellulases, pectinases, and mixtures thereof. 
     
     
         26 . The method of  claim 21  wherein said enzyme is selected from the group consisting of cellulases derived from  Trichoderma viride, Aspergillus niger , hemicellulases, other carbohydrases and mixtures thereof. 
     
     
         27 . The method of  claim 21  wherein alkali is not added to the aqueous medium. 
     
     
         28 . The method of  claim 21  wherein the pulping occurs at a wastepaper pulp consistency of about 12% or greater. 
     
     
         29 . The method of  claim 21  wherein the pulping occurs for a period of less than about 1 hour. 
     
     
         30 . The method of  claim 21  wherein the temperature of the pulping is in a range of from room temperature up to about 60 C. 
     
     
         31 . A method of recycling waste printed paper, comprising:
 a) pulping waste printed paper;   b) contacting at a pH between 3 and 8 waste printed paper at high wastepaper pulping consistency with an enzyme capable of dislodging ink particles from the waste printed paper in an aqueous medium at a pH between 3 and 8, wherein ink is dislodged from the waste printed paper by action of the enzyme; and   c) removing dislodged ink particles from the resulting pulp containing medium.   
     
     
         32 . The method of  claim 31 , wherein the enzyme is a cellulase selected from the group of cellulases derived from  Trichoderma viride, Aspergillus niger  or mixtures thereof wherein the cellulase is used in an amount between 0.005 and 5.0 percent-by-weight based on the dry weight of the waste printed paper, the contacting being carried out at a temperature between room temperature and about 60° C. 
     
     
         33 . The method of  claim 31  wherein the amount of enzyme used is in the range of 0.005 to 5 percent-by-weight based on the dry weight of the wastepaper. 
     
     
         34 . The method of  claim 31  wherein said enzyme is selected from the class consisting of cellulose, pectinase, and mixtures thereof. 
     
     
         35 . The method of  claim 31  wherein said enzyme is a cellulase-selected from the group consisting of cellulases derived from  Trichoderma viride, Aspergillus niger , hemicellulases, other carbohydrases and mixtures thereof. 
     
     
         36 . The method of  claim 31  wherein the ink particles are removed by flotation or washing. 
     
     
         37 . The method of  claim 31  wherein alkali is not added to the aqueous medium. 
     
     
         38 . The method of  claim 31  wherein the pulping occurs at a wastepaper pulp consistency of between 12% and 15%. 
     
     
         39 . The method of  claim 31  wherein the pulping occurs for a period of less than about 1 hour. 
     
     
         40 . The method of  claim 31  wherein the temperature of the pulping is in a range of from room temperature up to about 60 C. 
     
     
         41 . A method of biologically de-inking waste printed paper comprising:
 a) pulping the waste printed paper with an enzyme capable of dislodging ink particles from the waste printed paper in an aqueous medium at an acidic range or neutral range pH, and wherein the ink is dislodged from the waste printed paper by action of said enzyme; and   b) removing dislodged ink particles from the resulting pulp containing medium.   
     
     
         42 . The method of  claim 31  wherein the enzyme enhances removal of materials selected from the group consisting of heavily coated inks, highly polymerized inks, non-impact inks, and cured polymer resins. 
     
     
         43 . The method of  claim 42  wherein the enzyme is effective to enhance removal of cured polymer resins. 
     
     
         44 . The method of  claim 31  wherein the enzyme is effective to debond fiber bonding. 
     
     
         45 . The method of  claim 25  wherein the enzyme degrades by enzymatic hydrolysis. 
     
     
         46 . The method of  claim 31  wherein the enzyme degrades by enzymatic hydrolysis. 
     
     
         47 . The method of  claim 41  wherein the enzyme degrades by enzymatic hydrolysis. 
     
     
         48 . The method of  claim 21  wherein the enzyme is an acid resistant cellulase. 
     
     
         49 . The method of  claim 21  wherein the wastepaper is disintegrated in a conventional pulper. 
     
     
         50 . The method of  claim 49  wherein the consistency of the pulp in the conventional pulper is between 4 and 7%.