Method of producing and the use of microfibrillated paper

Abstract

The present invention relates to a method of producing a cellulose based paper, the paper itself and the use thereof where the paper exhibits enhanced mechanical properties. The method involves providing a suspension of well dispersed modified cellulose at a low concentration. The properties and the chemical structure of the paper make it suitable for in vivo applications such as implant material.

1 . A method of producing paper comprising:
 providing nanofibrils of cellulose;   modifying said nanofibrils;   providing a suspension of said modified nanofibrils at a concentration of less than 0.5 weight %; said nanofibrils being well dispersed in the suspension;   filtering, dewatering and drying the nanofibrils.   
     
     
         2 . The method of  claim 1  wherein the cellulose is derived from plants. 
     
     
         3 . The method according to any one of  claims 1 - 2  wherein the modified nanofibrils comprise charged groups. 
     
     
         4 . The method of  claim 3  wherein the charged groups are anionic, cationic or zwitterionic. 
     
     
         5 . The method of  claim 3  wherein the formation of charged groups is a result of treatment with radicals or halogen acids. 
     
     
         6 . The method of  claim 3  wherein the formation of charged groups is a result of treatment with 2,2,6,6-tetramethyl-1-piperidinyloxy radicals. 
     
     
         7 . The method of  claim 1  wherein the cellulose is produced by bacteria. 
     
     
         8 . The method of  claim 7  wherein the bacteria are cultured under dynamic conditions. 
     
     
         9 . The method of  claim 7  wherein the bacteria are cultured under static conditions. 
     
     
         10 . The method according to any of  claims 7 - 9  wherein the modified nanofibrils comprise a coating of at least one polymer. 
     
     
         11 . The method of  claim 10  wherein the polymer is present in the culture medium. 
     
     
         12 . The method of  claim 10  wherein the polymer is a water soluble polysaccharide. 
     
     
         13 . The method of  claim 10  wherein the polymer is a hydroxyaliphatic cellulose. 
     
     
         14 . The method of  claim 1  wherein the nanofibrils have been treated with enzymes and/or by mechanical beating. 
     
     
         15 . The method of  claim 1  wherein the nanofibrils have a lateral dimension of 15 nm or less. 
     
     
         16 . The method of  claim 1  wherein the distribution of lateral dimensions of the nanofibrils is 15-25 nm. 
     
     
         17 . A paper comprising a structure of cellulose nanofibrils characterized by nanofibrils that are modified and aggregated to bundles. 
     
     
         18 . The paper of  claim 17  wherein the cellulose nanofibrils are derived from plants. 
     
     
         19 . The paper according to any of  claims 17 - 18  wherein the cellulose nanofibrils comprise charged groups. 
     
     
         20 . The paper of  claim 19  wherein the charged groups are anionic, cationic or zwitterionic. 
     
     
         21 . The paper of  claim 18  wherein the average degree of polymerisation for the cellulose is greater than 400, preferably greater than 800 and most preferably greater than 1000. 
     
     
         22 . The paper of  claim 17  wherein the cellulose nanofibrils are derived from bacteria. 
     
     
         23 . The paper of  claim 22  wherein the cellulose nanofibrils are coated with at least one polymer. 
     
     
         24 . The paper of  claim 23  wherein the at least one polymer is a water soluble polysaccharide. 
     
     
         25 . The paper according to any of  claims 23 - 24  wherein the at least one polymer is a hydroxyaliphatic cellulose. 
     
     
         26 . The paper of  claim 17  wherein the cellulose nanofibrils have a lateral dimension of 15 nm or less. 
     
     
         27 . The paper of  claim 17  wherein the cellulose nanofibrils have a lateral distribution dimension of 15-25 nm. 
     
     
         28 . The paper of  claim 17  wherein the paper has a thickness of 40 μm or less. 
     
     
         29 . The paper of  claim 17  wherein the paper has a tensile strength of at least 250 MPa. 
     
     
         30 . The paper of  claim 17  wherein the cellulose nanofibrils form a filter paper. 
     
     
         31 . The paper of  claim 17  wherein the cellulose nanofibrils form a biodegradable scaffold, suture, implant material or drug delivery vehicle. 
     
     
         32 . The paper of  claim 17  wherein the cellulose nanofibrils form a speaker membrane, battery membrane or bullet proof material.