Re-dispersed microfibrillated cellulose

1. A method of improving the physical and/or mechanical properties of re-dispersed dried or partially dried microfibrillated cellulose, the method comprising:

a. Providing an aqueous composition of microfibrillated cellulose;

b. dewatering the aqueous composition by one or more of:

i. dewatering by belt press,

ii. a high pressure automated belt press,

iii. centrifuge,

iv. tube press,

v. screw press, and

vi. rotary press;

to produce a dewatered microfibrillated cellulose composition;

c. drying the dewatered microfibrillated cellulose composition by one or more of:

i. a fluidized bed dryer,

ii. microwave and/or radio frequency dryer,

iii. a hot air swept mill or dryer, a cell mill or a multirotor cell mill, and

iv. freeze drying;

to produce a dried or partially dried microfibrillated cellulose composition; and

(d) re-dispersing the dried or at least partially dried microfibrillated cellulose in a liquid medium;

wherein 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 at a comparable concentration and a fibre steepness of from 20 to 50.

2. The method of claim 1 , wherein said microfibrillated cellulose additionally comprises an inorganic particulate material.

3. The method of claim 2 , wherein the inorganic particulate material comprises a platy mineral, kaolin and/or talc.

4. The method of claim 3 , wherein the inorganic particulate material additionally comprises inorganic particulate material other than a platy mineral.

5. The method of claim 2 , wherein the inorganic particulate material is calcium carbonate.

6. The method of claim 2 , 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; during dewatering of the aqueous composition of microfibrillated cellulose; 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.

7. The method of claim 2 , wherein the aqueous composition of the dewatered microfibrillated cellulose prior to drying or at least partially drying comprises up to about 80% of the solids as inorganic particulate material.

8. The method of 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 salts, one or more sugars, one or more glycols, urea, carboxymethyl cellulose and guar gum.

9. The method of claim 8 , wherein the one or more sugars is selected from the group consisting of monosaccharides, disaccharides, oligosaccharides and polysaccharides.

10. The method of claim 8 , wherein the one or more salts comprise or is sodium chloride.

11. The method of claim 8 , wherein the one or more glycols comprise or is ethylene glycol.

12. The method of 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 about 50 wt. %.

13. The method of 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 about 20 wt. %.

14. The method of claim 1 , wherein the liquid medium is aqueous or non-aqueous.

15. The method of claim 14 , wherein the liquid medium is water.

16. The method of claim 1 wherein said re-dispersing of the dried or at least partially dried microfibrillated cellulose comprises using a refiner.

17. The method of claim 1 , wherein said a dried or partially dried microfibrillated cellulose composition has a fibre steepness from about 20 to about 50.

18. The method of 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 about 30 wt. %.