Method for producing cellulose nanofiber dry solid

Patent metadata

Field	Value
Publication number	US-10988549-B2
Application number	US-201616065213-A
Country	US
Kind code	B2
Filing date	Dec 22, 2016
Priority date	Dec 25, 2015
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

A method for producing a dry solid of cellulose nanofiber, the method comprising (A) preparing a dispersion in which cellulose nanofiber with an average fiber diameter of 2 to 500 nm is dispersed in a mixed solvent of water and a water-soluble organic solvent; and (B) drying the dispersion.

First claim

The invention claimed is:

1. A method for producing a dry solid of cellulose nanofiber, the method comprising:
step (A) of defibrating a cellulose material in water to obtain an aqueous dispersion of cellulose nanofiber, and mixing the aqueous dispersion of cellulose nanofiber with a water-soluble organic solvent to obtain a mixture comprising the cellulose nanofiber, water, and the water-soluble organic solvent, wherein the cellulose nanofiber has an average fiber diameter of 2 to 500 nm, wherein a weight ratio of the water to the water-soluble organic solvent in the mixture is 1:100 to 10:1, and wherein the water-soluble organic solvent is a lower alcohol having 1 to 4 carbons; and
step (B) of drying the mixture under temperature ranging from 50 to 160° C.

2. The method according to claim 1 , wherein mixing the aqueous dispersion of cellulose nanofiber with a water-soluble organic solvent in step (A) comprises precipitating cellulose nanofiber.

3. The method according to claim 1 , wherein the dry solid further comprises a water-soluble polymer.

4. The method according to claim 3 , wherein mixing the aqueous dispersion of cellulose nanofiber with a water-soluble organic solvent in step (A) comprises mixing the aqueous dispersion of cellulose nanofiber with the water-soluble polymer and the water-soluble organic solvent.

5. The method according to claim 4 , wherein an amount of the water-soluble polymer to be mixed is 1 to 100 wt % against an absolute dry solid content of the cellulose nanofiber.

6. The method according to claim 2 , wherein mixing the aqueous dispersion of cellulose nanofiber with a water-soluble organic solvent in step (A) comprises adding dropwise the aqueous dispersion of cellulose nanofiber into the water-soluble organic solvent to precipitate cellulose nanofiber.

7. The method according to claim 1 , wherein an amount of carboxyl group in the cellulose nanofiber in step (A) is 0.6 to 3.0 mmol/g against an absolute dry weight of the cellulose nanofiber.

8. The method according to claim 1 , wherein a degree of carboxymethyl substitution per glucose unit of the cellulose nanofiber in step (A) is 0.01 to 0.50.

9. The method according to claim 1 , wherein a degree of cation substitution per glucose unit of the cellulose nanofiber in step (A) is 0.02 to 0.50.

10. The method according to claim 1 , wherein a weight ratio of the water to the water-soluble organic solvent in the mixture in step (A) is 1:100 to 1:1.

11. A method for producing a cellulose nanofiber dispersion comprising redispersing the dry solid of cellulose nanofiber obtained by the method according to claim 1 in a dispersion medium.

12. The method according to claim 2 , wherein the dry solid further comprises a water-soluble polymer.

13. The method according to claim 12 , wherein mixing the aqueous dispersion of cellulose nanofiber with a water-soluble organic solvent in step (A) comprises mixing the aqueous dispersion of cellulose nanofiber with the water-soluble polymer and the water-soluble organic solvent.

14. The method according to claim 13 , wherein an amount of the water-soluble polymer to be mixed is 1 to 100 wt % against an absolute dry solid content of the cellulose nanofiber.

15. The method according to claim 14 , wherein mixing the aqueous dispersion of cellulose nanofiber with a water-soluble organic solvent in step (A) comprises adding dropwise the aqueous dispersion of cellulose nanofiber into the water-soluble organic solvent to precipitate cellulose nanofiber.

16. The method according to claim 15 , wherein an amount of carboxyl group in the cellulose nanofiber in step (A) is 0.6 to 3.0 mmol/g against an absolute dry weight of the cellulose nanofiber.

17. The method according to claim 15 , wherein a degree of carboxymethyl substitution per glucose unit of the cellulose nanofiber in step (A) is 0.01 to 0.50.

18. The method according to claim 15 , wherein a degree of cation substitution per glucose unit of the cellulose nanofiber in step (A) is 0.02 to 0.50.

19. The method according to claim 1 , wherein the dry solid has a restoration rate of Brookfield viscosity being 68% or more, and a restoration rate of transparency being 89% or more when redispersed in a dispersion medium.

Assignees

• Jujo Paper Co Ltd

Inventors

• Nakatani Takeshi
• Sato Shinji

Classifications

• C08L1/286

  substituted with acid radicals, e.g. carboxymethyl cellulose [CMC] (C08L1/282 takes precedence) · CPC title

• C08L1/04

  Oxycellulose; Hydrocellulose {, e.g. microcrystalline cellulose} · CPC title

• C08B11/12 Primary

  substituted with carboxylic radicals {, e.g. carboxymethylcellulose [CMC]} · CPC title

• D01F2/00

  Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title