Microfibrillated cellulose containing pulp sheets with improved mechanical properties

Patent metadata

Field	Value
Publication number	US-12385185-B2
Application number	US-202117469185-A
Country	US
Kind code	B2
Filing date	Sep 8, 2021
Priority date	Sep 11, 2020
Publication date	Aug 12, 2025
Grant date	Aug 12, 2025

Abstract

A method of manufacturing a partially-dried sheet comprising, consisting essentially of, or consisting of, microfibrillated cellulose suitable for use as a binder, or a dried sheet comprising, consisting essentially of, or consisting of, a blend of microfibrillated cellulose and a pulp suitable for use as a pulp source, wherein said sheet may be redispersed with a high shear disperser, mixer or refiner operated at energy inputs of about 10 kWh/t to about 2,000 kWh/t, wherein the sheet upon re-dispersion in a aqueous medium maintains, or is not substantially degraded in, tensile index, compared to the dried sheet prior to drying and re-dispersion.

First claim

What is claimed is:

1. A method of manufacturing a partially-dried market pulp sheet or a dried market pulp sheet comprising microfibrillated cellulose for use as a binder, the method comprising the steps of:
a. preparing a pulp slurry in a range of about 0.5 wt. % to about 30 wt. % total solids;
b. preparing a slurry comprising microfibrillated cellulose;
wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50;
c. mixing the pulp slurry and the slurry comprising microfibrillated cellulose, wherein the content of microfibrillated cellulose in the pulp slurry is about 0.5 wt. % to about 99.5 wt. % of the total dry mass of the pulp slurry and slurry comprising microfibrillated cellulose;
d. forming a market pulp sheet comprising microfibrillated cellulose and pulp from the pulp slurry and slurry comprising microfibrillated cellulose;
e. dewatering and drying the market pulp sheet to a desired moisture content;
wherein the moisture content of the dewatered and dried market pulp sheet in step e is in the range of about 20% by weight to about 85% by weight moisture; or wherein the moisture content of the dewatered and dried market pulp sheet in step e is about 20% by weight or less; and
f. repulping dewatered and dried market pulp sheet of step e by redispersing the dewatered and dried market pulp sheet in an aqueous medium with a disperser, mixer, or refiner operated at energy inputs of about 10 kWh/t to about 2,000 kWh/t, wherein the tensile strength (FLT Index) repulped market pulp compared to market pulp formed from a comparable amount of microfibrillated cellulose prior to dewatering and drying in step e is not reduced by more than 15%.

2. The method according to claim 1 , wherein the partially-dried market pulp sheet or the dried market pulp sheet further comprises one or more inorganic particulate material.

3. The method according to claim 2 , wherein the microfibrillated cellulose is obtained by a co-grinding microfibrillation process wherein a fibrous substrate comprising cellulose is microfibrillated in an aqueous environment in a grinding apparatus in the presence of one or more inorganic particulate material, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5 and, optionally, wherein the microfibrillating is performed in the presence of a grinding medium which is to be removed after completion of grinding.

4. The method according to claim 3 , wherein the fibrous substrate comprising cellulose has a Canadian Standard Freeness equal to or less than 450 cm 3 .

5. The method according to claim 3 , further comprising a grinding medium.

6. The method according to claim 5 , wherein the grinding medium is present in an amount of at least about 10% by volume of the aqueous medium.

7. The method according to claim 5 , wherein the grinding medium is present in an amount up to about 70% by volume of the aqueous medium.

8. The method according to claim 5 , wherein the grinding medium comprises particles having an average diameter ranging from about 0.5 mm to about 6 mm.

9. The method according to claim 5 , wherein the grinding medium comprises particles having a specific gravity of at least about 2.5.

10. The method according to claim 5 , wherein the grinding medium is selected from the group consisting of alumina, zirconia, zirconium silicate, aluminum silicate or the mullite-rich material which is produced by calcining kaolinitic clay at a temperature in the range of from about 1300° C. to about 1800° C.

11. The method according to claim 10 , wherein the grinding medium is the mullite-rich material which is produced by calcining kaolinitic clay at a temperature in the range of from about 1300° C. to about 1800° C.

12. The method according to claim 3 , wherein the fibrous substrate comprising cellulose is present in the aqueous medium at an initial solids content of at least about 5 wt. %.

13. The method according to claim 3 , wherein the grinding is performed in a tower mill or a screened grinder.

14. The method according to claim 13 , wherein the screened grinder is a stirred media detritor.

15. The method according to claim 13 , wherein the screened grinder comprises one or more screens having a nominal aperture size of at least about 250 um.

16. The method according to claim 3 , wherein the grinding is performed in a cascade of grinding vessels.

17. The method according to claim 2 , wherein microfibrillated cellulose is present in an amount of about 0.5 wt. % to about 50 wt. % of the total dry mass of the dewatered and dried market pulp sheet of step e.

18. The method according to claim 2 , wherein microfibrillated cellulose is present in an amount of about 0.5 wt. % to about 10 wt. % of the total dry mass of the dewatered and dried market pulp sheet of step e.

19. The method according to claim 2 , wherein the one or more inorganic particulate material comprises a platy mineral, kaolin and/or talc.

20. The method according to claim 2 , wherein the one or more inorganic particulate material is calcium carbonate or kaolin, or mixtures thereof.

21. The method according to claim 20 , wherein the calcium carbonate is ground calcium carbonate, precipitated calcium carbonate, or mixtures thereof.

22. The method according to claim 2 , wherein the inorganic particulate material is selected from the group consisting of an alkaline earth metal carbonate or sulphate, a calcium carbonate, a magnesium carbonate, a dolomite, a gypsum, a bentonite, a hydrous kandite clay, a kaolin, a halloysite, a ball clay, an anhydrous (calcined) kandite clay, a metakaolin, a fully calcined kaolin, a talc, a mica, a perlite, a sepiolite, a huntite, a diatomite, a magnesite, a silicate, a diatomaceous earth, a brucite, an aluminum trihydrate, and combinations thereof.

23. The method according to claim 2 , wherein the method further comprises use of the re-dispersed dried sheet in, or in the manufacture of, an article, product or composition.

24. The method according to claim 1 , wherein microfibrillated cellulose is present in an amount of about 0.5 wt. % to about 50 wt. %. of the total dry mass of the dewatered and dried market pulp sheet of step e.

25. The method according to claim 1 , wherein microfibrillated cellulose is present in an amount of about 0.5 wt. % to about 10 wt. % of the total dry mass of the dewatered and dried market pulp sheet of step e.

26. The method according to claim 1 , wherein microfibrillated cellulose is present in an amount of about 0.5 wt. % to about 75% wt. % of the dewatered and dried market pulp sheet of step e.

27. The method according to claim 1 , wherein microfibrillated cellulose is present in an amount of about 0.5 wt. % to about 90 wt. %. of the dewatered and dried market pulp sheet of step e.

28. The method according to claim 1 , wherein microfibrillated cellulose is present in an amount of about 20 wt. % to about 40 wt. % of the dewatered and dried market pulp sheet of step e.

29. The method according to claim 1 , wherein microfibrillated cellulose is present in an amount of about 10 wt. % to about 20 wt. % of the dewatered and dried market pulp sheet of step e.

30. The method according claim 1 , wherein, the microfibrillated cellulose is obtained from a pulp selected from the group consisting of a chemical pulp

Assignees

• Fiberlean Tech Ltd

Inventors

• Reeve-Larson Thomas
• Windebank Mark
• Ingle Daniel
• Paradis Mark
• Skuse David R

Classifications

• D21F7/003

  Indicating or regulating the moisture content of the layer · CPC title

• D21H17/68

  siliceous, e.g. clays · CPC title

• D21D1/20

  Methods of refining · CPC title

• D21H17/675

  Oxides, hydroxides or carbonates · CPC title

• D21H11/04

  Kraft or sulfate pulp · CPC title