Re-dispersed microfibrillated cellulose

Abstract

Methods of improving the re-dispersibility of dried or at least partially dried microfibrillated cellulose, methods of re-dispersing dried or at least partially dried microfibrillated cellulose, compositions comprising re-dispersed microfibrillated cellulose and the use of re-dispersed microfibrillated cellulose in an article, product or composition; and methods of improving the physical and/or mechanical properties of re-dispersed dried or partially dried microfibrillated cellulose.

1 - 18 . (canceled) 
     
     
         19 . A method of improving the physical and/or mechanical properties of re-dispersed dried or partially-dried microfibrillated cellulose, the method comprising:
 providing an aqueous composition of microfibrillated cellulose, wherein the microfibrillated cellulose is obtained from a chemical pulp, or a chemithermomechanical pulp, or a mechanical pulp, or a recycled pulp, or a papermill broke, or a papermill waste stream, or waste from a papermill, or any combinations thereof;
 dewatering the aqueous composition of microfibrillated cellulose by a belt press or a high pressure automated belt press to produce a dewatered microfibrillated cellulose composition; 
 drying the dewatered microfibrillated cellulose composition by a hot air swept mill or dryer, a dryer-pulverizer, an extended classifier mill, a cell mill, an air swept tubular dryer, or a multirotor cell mill to produce a dried or partially-dried microfibrillated cellulose composition; 
 whereupon re-dispersing the dried or partially-dried microfibrillated cellulose composition into a liquid medium, the microfibrillated cellulose has a tensile index and/or viscosity which is at least 50% of the tensile index and/or viscosity of the aqueous composition of microfibrillated cellulose prior to drying, where, the comparison of tensile index and/or viscosity is carried out by equalizing the concentration of the aqueous composition of the microfibrillated cellulose prior to drying and the liquid medium of the microfibrillated cellulose after dispersion, and is carried out by using microfibrillated cellulose having a fiber steepness of 20 to 50 for microfibrillated cellulose before drying. 
   
     
     
         20 . The method according to claim  1 , further comprising re-dispersing the dried or at least partially-dried microfibrillated cellulose in the liquid medium. 
     
     
         21 . The method according to claim  1 , wherein said microfibrillated cellulose additionally comprises an inorganic particulate material. 
     
     
         22 . The method according to  claim 21 , wherein the inorganic particulate material comprises a platy mineral, kaolin and/or talc. 
     
     
         23 . The method according to  claim 21 , wherein the inorganic particulate material additionally comprises inorganic particulate material other than a platy mineral. 
     
     
         24 . The method according to  claim 21 , wherein the inorganic particulate material is calcium carbonate. 
     
     
         25 . The method according to claim  1 , wherein said dried or partially-dried microfibrillated cellulose is re-dispersed in the presence of one or more additives selected from the group consisting of one or more salt, one or more sugar, one or more glycol, urea, carboxymethyl cellulose and guar gum. 
     
     
         26 . The method according to  claim 25 , wherein the one or more sugar is selected from one or more of monosaccharides, disaccharides, oligosaccharides and polysachharides. 
     
     
         27 . The method according to  claim 25 , wherein the one or more salt comprises sodium chloride. 
     
     
         28 . The method according to  claim 25 , wherein the one or more glycol comprises ethylene glycol. 
     
     
         29 . The method according to  claim 21 , the wherein inorganic particulate material is added at one or more of the following stages: (i) prior to or during manufacture of the aqueous composition comprising microfibrillated cellulose; (ii) following manufacture of the aqueous composition comprising microfibrillated cellulose; (iii) during dewatering of the aqueous composition of microfibrillated cellulose; (iv) during drying of the aqueous composition of microfibrillated cellulose; (v) prior to re-dispersing of the dried or at least partially-dried microfibrillated cellulose; and (vi) during re-dispersing of the dried or at least partially-dried microfibrillated cellulose. 
     
     
         30 . The method according to claim  1 , said method further comprising using the re-dispersed microfibrillated cellulose in, or in the manufacture of, an article, product or composition. 
     
     
         31 . The method according to claim  1 , wherein the aqueous composition of the dewatered microfibrillated cellulose prior to drying or at least partially drying has a solids content of up to 50 wt. %. 
     
     
         32 . The method according to claim  1 , wherein the aqueous composition of the dewatered microfibrillated cellulose prior to drying or at least partially drying has a solids content of up to 30 wt. %. 
     
     
         33 . The method according to claim  1 , wherein the aqueous composition of the dewatered microfibrillated cellulose prior to drying or at least partially drying has a solids content of up to 20 wt. %. 
     
     
         34 . The method according to claim  1 , wherein the liquid medium is aqueous or non-aqueous. 
     
     
         35 . The method according to  claim 34 , wherein the liquid medium comprises water. 
     
     
         36 . The method according to  claim 19 , wherein said re-dispersing of the dried or at least partially-dried microfibrillated cellulose comprises using a mixer or a refiner. 
     
     
         37 . The method according to  claim 19 , wherein said re-dispersing of the dried or at least partially-dried microfibrillated cellulose comprises using a mixer or a refiner. 
     
     
         38 . The method according to  claim 19 , wherein said re-dispersing of the dried or at least partially-dried microfibrillated cellulose comprises using a hot air swept mill or dryer. 
     
     
         39 . The method according to claim  211 , wherein said re-dispersing of the dried or at least partially-dried microfibrillated cellulose comprises using a hot air swept mill or dryer 
     
     
         40 . The method according to  claim 19 , wherein said re-dispersing of the dried or at least partially-dried microfibrillated cellulose comprises using a cell mill. 
     
     
         41 . The method according to  claim 21 , wherein said re-dispersing of the dried or at least partially-dried microfibrillated cellulose comprises using a cell mill. 
     
     
         42 . The method according to  claim 19 , wherein said re-dispersing of the dried or at least partially-dried microfibrillated cellulose comprises using a multirotor cell mill. 
     
     
         43 . The method according to  claim 19 , wherein said re-dispersing of the dried or at least partially-dried microfibrillated cellulose comprises using a multirotor cell mill. 
     
     
         44 . The method according to  claim 19 , wherein the partially dried mirofibrillated cellulose composition is dewatered and dried to reduce water content by about at least 30% by weight of the aqueous composition comprising microfibrillated cellulose prior to dewatering and drying. 
     
     
         45 . The method according to  claim 19 , wherein the partially dried mirofibrillated cellulose composition is dewatered and dried to reduce water content by about at least 40% by weight of the aqueous composition comprising microfibrillated cellulose prior to dewatering and drying. 
     
     
         46 . The method according to  claim 21 , wherein the partially dried mirofibrillated cellulose and inorganic particulate material composition is dewatered and dried to reduce water content by about at least 30% by weight of the aqueous composition comprising microfibrillated cellulose and inorganic particulate material composition prior to dewatering and drying. 
     
     
         47 . The method according to  claim 21 , wherein the partially dried mirofibrillated cellulose and inorganic particulate material composition is dewatered and dried to reduce water content by about at least 40% by weight of the aqueous composition comprising microfibrillated cellulose and inorganic particulate material composition prior to dewatering and drying.