Method of modifying nanofibrillar cellulose composition

Patent metadata

Field	Value
Publication number	US-9809655-B2
Application number	US-201414907405-A
Country	US
Kind code	B2
Filing date	Jun 24, 2014
Priority date	Jul 26, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

The invention relates to a method for modifying nanofibrillar cellulose composition, comprising—preparing fibrous dispersion of ionically charged nanofibrillar cellulose (NFC), and—applying heat treatment at a temperature of at least 90° C. to the fibrous dispersion until the viscosity of NFC starts to decrease. The viscosity of the heat-treated NFC is reversible by applying shear forces to the NFC.

First claim

The invention claimed is:

1. A method for modifying nanofibrillar cellulose composition, comprising
preparing fibrous dispersion of ionically charged nanofibrillar cellulose (NFC),
applying heat treatment at a temperature of at least 90° C. to the fibrous dispersion until first sign of negative growth of the viscosity value of the nanofibrillar cellulose.

2. The method according to claim 1 , wherein the applying heat treatment decreases the zero shear viscosity of the nanofibrillar cellulose composition below 100 Pa·s, as measured in 0.5% concentration of NFC.

3. The method according to claim 1 , wherein the heat treatment is performed under a pressure set sufficiently high to prevent liquid medium of the dispersion, such as water, from boiling.

4. The method according to claim 1 , wherein the heat treatment is performed at a temperature in the range of 90-180° C..

5. The method according to claim 1 , wherein the ionically charged nanofibrillar cellulose is oxidized nanofibrillar cellulose obtained by oxidizing cellulose through N-oxyl mediated catalytic oxidation followed by fibrillating the oxidized cellulose.

6. The method according to claim 5 , wherein the oxidized cellulose has the carboxylate content of at least 0.5 mmol COOH/g pulp.

7. The method according to claim 5 , wherein the oxidized cellulose has the carboxylate content of 0.5 - 2.5 mmol COOH/g pulp.

8. The method according to claim 5 , wherein the oxidized cellulose has the carboxylate content of 0.7-1.2 mmol COOH/g pulp.

9. The method according to claim 5 , wherein the oxidized cellulose has the carboxylate content of 0.9-1.1 mmol COOH/g pulp.

10. The method according to claim 1 , wherein the ionically charged nanofibrillar cellulose is carboxymethylated nanofibrillar cellulose.

11. The method according to claim 10 , wherein the carboxymethylated nanofibrillar cellulose has the degree of substitution in the range of 0.05 - 0.3.

12. The method according to claim 10 , wherein the carboxymethylated nanofibrillar cellulose has the degree of substitution in the range of 0.10 to 0.25.

13. The method according to claim 1 , the method further comprises applying shear forces to the heat-treated nanofibrillar cellulose, wherein the zero-shear viscosity of the nanofibrillar cellulose is higher after applying the shear forces, when measured at the concentration of 0.5%.

14. The method according to claim 1 , the method further comprises applying shear forces to the heat-treated nanofibrillar cellulose, wherein the zero-shear viscosity of the nanofibrillar cellulose, to which the shear forces were applied, is at least 80% of the zero-shear viscosity before the heat treatment, when measured at 0.5%.

15. The method according to claim 1 , wherein the heat treatment is performed in a pressurized chamber where the gas composition is adjusted so that there is less oxygen or no oxygen.

16. The method according to claim 15 , wherein the gas composition is adjusted by adding some other gas such as nitrogen.

17. The method according to claim 1 , wherein the nanofibrillar cellulose composition is an aqueous gel (hydrogel).

18. The method according to claim 1 , wherein the applying heat treatment decreases the zero shear viscosity of the nanofibrillar cellulose composition below 10 Pa·s, as measured in 0.5% concentration of NFC.

19. The method according to claim 1 , wherein the applying heat treatment decreases the zero shear viscosity of the nanofibrillar cellulose composition below 5 Pa·s, as measured in 0.5% concentration of NFC.

20. The method according to claim 1 , wherein the heat treatment is performed at a temperature in the range of 100-150° C..

21. The method according to claim 1 , wherein the heat treatment is performed at a temperature in the range of 120-140° C..

Assignees

• Upm Kymmene Corp

Inventors

• Laukkanen Antti
• Nuopponen Markus
• Lille Martina

Classifications

• D21H11/18

  Highly hydrated, swollen or fibrillatable fibres · CPC title

• C09D101/02

  Cellulose; Modified cellulose · CPC title

• D21H21/18

  Reinforcing agents · CPC title

• C08B15/08

  Fractionation of cellulose, e.g. separation of cellulose crystallites · CPC title

• D21H19/00

  Coated paper (coated fibreboard D21J1/08); Coating material (recording sheets characterised by the coating used to improve ink, dye or pigment receptivity B41M5/50) · CPC title