Foam assisted drying process of nano- and microfibrillated cellulose

Patent metadata

Field	Value
Publication number	US-12077650-B2
Application number	US-201917297091-A
Country	US
Kind code	B2
Filing date	Nov 22, 2019
Priority date	Nov 26, 2018
Publication date	Sep 3, 2024
Grant date	Sep 3, 2024

Abstract

According to an example aspect of the present invention, there is provided a method for foam assisted drying of nano- and microfibrillated cellulose, which is easily up-scalable and cost-efficient.

First claim

The invention claimed is:

1. A method for drying nano- or micro-fibrillated cellulose comprising at least the steps of:
mixing together unmodified or modified nano- or micro-fibrillated cellulose and a foaming agent and foaming the mixture,
spreading the foamed mixture on a substrate that does not adhere to the foamed mixture and does not absorb into the foamed mixture, and
drying the foamed mixture.

2. The method according to claim 1 , further comprising drying the nano- or micro-fibrillated cellulose into a maximum dry content of 99 wt-%.

3. The method according to claim 1 , wherein the foaming agent is selected from anionic, non-ionic or amphoteric materials or material mixtures.

4. The method according to claim 3 , wherein the foaming agent is selected from sodium dodecyl sulphate (SDS) or polyvinyl alcohol (PVA), or is a mixture of SDS and PVA.

5. The method according to claim 1 , wherein the foaming agent is used at a volume ratio of 1 to 5%.

6. The method according to claim 1 , wherein the cellulose and foaming agent are further mixed with pressurized air and foamed using a foam generator.

7. The method according to claim 6 , wherein the air pressure is adjusted between 6 and 10 bars.

8. The method according to claim 1 , further comprising drying the nano- or micro-fibrillated cellulose into a maximum dry content of 99 wt-% with a drier, selected from infrared or air driers, or their combination.

9. A nano- or micro-fibrillated cellulose material, wherein it the nano- or micro-fibrillated cellulose material has been dried according to the method of claim 1 .

10. The nano- or micro-fibrillated cellulose material according to claim 9 , wherein the nano- or micro-fibrillated cellulose material has been milled into aggregates.

11. The nano- or micro-fibrillated cellulose material according to claim 9 , wherein it increases z-strength of at least 19%, when compared to a reference cellulose material without nano- or micro-fibrillated cellulose material addition.

12. A water dispergation of the nano- or micro-fibrillated cellulose material according to claim 9 having a maximum consistency of 20%.

13. Use of the nano- or micro-fibrillated cellulose material according to claim 9 as an enhancer in composite materials and/or structures, in paints and/or coatings, in films, in rheology modifiers, in emulsions and/or dispersions, in medical, cosmetic and/or pharmaceutical applications, in paper and/or board applications and/or in hygiene and/or absorbent products.

14. The method according to claim 2 wherein the foaming agent is selected from anionic, non-ionic or amphoteric materials or material mixtures.

15. The method according to claim 14 , wherein the foaming agent is selected from sodium dodecyl sulphate (SDS) or polyvinyl alcohol (PVA), or is a mixture of SDS and PVA.

16. The method according to claim 1 , wherein the foaming agent is used at a volume ratio of 1 to 2%.

17. The method according to claim 2 , further comprising mixing together native or modified nano- or micro-fibrillated cellulose and a foaming agent with pressurized air and foaming the mixture by using a foam generator.

18. The method according to claim 3 , further comprising mixing together native or modified nano- or micro-fibrillated cellulose and a foaming agent with pressurized air and foaming the mixture by using a foam generator.

19. The method according to claim 1 , wherein the method obtains re-dispersibility of the unmodified or modified nano- or micro-fibrillated cellulose.

20. The nano- or microfibrillated cellulose material of claim 9 , wherein the unmodified or modified nano- or micro-fibrillated cellulose is re-dispersible.

Assignees

• Teknologian Tutkimuskeskus Vtt Oy

Inventors

• Kinnunen-Raudaskoski Karita
• Hjelt Tuomo
• Lehmonen Jani

Classifications

• D21H21/56

  Foam · CPC title

• D21H11/18 Primary

  Highly hydrated, swollen or fibrillatable fibres · CPC title

• C08J2301/02

  Cellulose; Modified cellulose · CPC title

• C08J2201/0502

  the liquid phase being organic · CPC title

• C08J9/30

  by mixing gases into liquid compositions or plastisols, e.g. frothing with air · CPC title