Process for production of film comprising microfibrillated cellulose

Abstract

A film comprising microfibrillated cellulose, nanoparticles, and a retention polymer. The nanoparticles are nanosilica nanoparticles that are anionic at neutral or alkaline pH and have at least one dimension less than 100 nm; and the retention polymer is starch. According to the present invention a high amount of nanoparticles is used as an additive, optionally together with a retention polymer.

1 . A film comprising:
 microfibrillated cellulose;   nanoparticles, wherein said nanoparticles are nanosilica nanoparticles that are anionic at neutral or alkaline pH and have at least one dimension less than 100 nm; and   a retention polymer, wherein said retention polymer comprises starch,   wherein the film has an oxygen transmission rate <200 cc/m 2 *day measured at 50% RH, 23° C., and a grammage of 10-50 gsm.   
     
     
         2 . The film according to  claim 1 , wherein the amount of nanoparticles in the film is at least 5 kg/ton dry film. 
     
     
         3 . The film according to  claim 2 , further comprising:
 a coating, provided on at least one side of the film,   
     
     
         4 . The film according to  claim 3 , further comprising: a tie layer between the film and the coating. 
     
     
         5 . The film according to  claim 1 , further comprising:
 a coating, provided on at least one side of the film,   
     
     
         6 . The film according to  claim 5 , further comprising: a tie layer between the film and the coating. 
     
     
         7 . The film according to  claim 1 , wherein said retention polymer further comprises polyaminoamide, epichlorohydrin, cationic polyacryl amide, copolymers of cationic polyacryl amide, and mixtures thereof. 
     
     
         8 . A product comprising:
 a surface having a film, wherein the film comprises
 microfibrillated cellulose; 
 nanoparticles, wherein said nanoparticles are nanosilica nanoparticles that are anionic at neutral or alkaline pH and have at least one dimension less than 100 nm; and 
 a retention polymer, wherein said retention polymer comprises starch, 
 wherein the film has an oxygen transmission rate <200 cc/m 2 *day measured at 50% RH, 23° C., and a grammage of 10-50 gsm 
   
     
     
         9 . The product according to  claim 8 , wherein the amount of nanoparticles in the film is at least 5 kg/ton dry film 
     
     
         10 . The product according to  claim 9 , further comprising:
 a coating, provided on at least one side of the film,   
     
     
         11 . The product according to  claim 10 , further comprising: a tie layer between the film and the coating. 
     
     
         12 . The product according to  claim 8 , further comprising:
 a coating, provided on at least one side of the film,   
     
     
         13 . The product according to  claim 12 , further comprising: a tie layer between the film and the coating. 
     
     
         14 . The product according to  claim 8 , wherein said retention polymer further comprises polyaminoamide, epichlorohydrin, cationic polyacryl amide, copolymers of cationic polyacryl amide, and mixtures thereof.