Method and a device for producing nanofibrillar cellulose

Patent metadata

Field	Value
Publication number	US-10808356-B2
Application number	US-201414890392-A
Country	US
Kind code	B2
Filing date	May 13, 2014
Priority date	May 14, 2013
Publication date	Oct 20, 2020
Grant date	Oct 20, 2020

Abstract

In a method for producing nanofibrillar cellulose, cellulose based fiber material in dispersion is processed for separating fibrils. The method includes a first step where the fiber material is supplied to a disperser, where it flows through several counter-rotating rotors in such a way that the material is repeatedly subjected to shear and impact forces by the effect of the different counter-rotating rotors, and a second step, where the fiber material obtained from the first step is supplied to a homogenizer, where it is subjected to homogenization by the effect of pressure.

First claim

The invention claimed is:

1. A method for producing nanofibrillar cellulose, wherein cellulose based fiber material in dispersion is processed for separating fibrils, the fiber material being pulp, the method comprising:
a first step where the fiber material is supplied to a disperser, where the fiber material flows through several counter-rotating rotors in such a way that it is repeatedly subjected to shear and impact forces by the effect of different counter-rotating rotors to reduce the fiber material at least partly to nanofibrillar cellulose and in which fibrils or fibril bundles are separated from the fiber material, the resulting fiber material being non-homogeneous and including fiber fragments not disintegrated to fibrils; and
a second step, where the fiber material obtained from the first step is supplied to a homogenizer without dilution, where it is subjected to homogenization by the effect of pressure,
wherein the fiber material is treated at a consistency of 1-8 wt-% in the first step or in both the first and second steps and wherein the nanofibrillar cellulose has a fibril diameter smaller than about 200 nm.

2. The method according to claim 1 , wherein in the first step, the fiber material is supplied through the several counter-rotating rotors outwards in radial direction with respect to a rotation axis of the rotors in such a way that the fiber material is repeatedly subjected to shear and impact forces by the effect of blades of the different counter-rotating rotors, whereby the fiber material is simultaneously fibrillated at least partly, wherein the fibrillation is effected by means of impact energy utilizing a series of frequently repeated impacts having varying directions of action.

3. The method according to claim 1 , wherein in the second step, the homogenization pressure is 200 to 1000 bar.

4. The method according to claim 1 , wherein in the first step, the passage of the fiber material through the disperser is repeated one or more times and/or in the second step, the passage of the fiber material through the homogenizer is repeated one or more times.

5. The method according to claim 1 , wherein in the first step, the fiber material is passed through the disperser 1-3 times, and in the second step, the fiber material is passed through the homogenizer 1-3 times.

6. The method according to claim 1 , wherein the nanofibrillar cellulose is produced continuously by passing the fiber material continuously through the disperser or dispersers connected in series and by passing the fiber material continuously through the homogenizer or homogenizers connected in series.

7. The method according to claim 1 , wherein the fiber material is processed in the second step in the same consistency as obtained from the first step.

8. The method according to claim 1 , wherein the fiber material is treated in the second step at a consistency of 1.5-6 wt %.

9. The method according to claim 1 , wherein in the fiber material supplied to the first step, the internal bonds of the fiber have been weakened by chemical or enzymatic pretreatment.

10. The method according to claim 9 , wherein the cellulose is anionically or canonically modified cellulose.

11. The method according to claim 9 , wherein the cellulose is oxidized cellulose containing carboxyl groups.

12. The method according to claim 9 , wherein the cellulose is carboxymethylated cellulose.

13. The method according to claim 1 , wherein the nanofibrillar cellulose obtained from the second step has a Brookfield viscosity of at least 5,000 mPa·s, measured at a consistency of 0.8% and at 10 rpm.

14. The method according to claim 1 , wherein the fiber material obtained from the second step has a turbidity value lower than 90 NTU, measured at a consistency of 0.1%.

15. The method according to claim 1 , wherein the nanofibrillar cellulose obtained from the second step has a zero shear viscosity in the range of 1,000 to 100,000 Pa·s, and a yield stress in the range of 1 to 50 Pa, determined by a rotational reometer at a consistency of 0.5 wt %.

16. The method according to claim 1 , wherein in the second step, the homogenization pressure is 300 to 650 bar.

17. The method of claim 16 , wherein the homogenizer comprises an inlet and outlet for fiber material and between the inlet and outlet, a narrow through-flow gap, said homogenizer further comprising means configured to create pressure in the fiber material dispersion before said through-flow gap to cause shearing and impact forces on the fiber material dispersion flowing through said through-flow gap.

18. The method according to claim 1 , wherein in the second step, the homogenization pressure is 310 to 450 bar.

19. The method according to claim 1 , wherein the fiber material is treated at a consistency of 2-5 wt-% in the first step or in both the first and second steps.

20. The method according to claim 19 , wherein the fiber material is treated in the second step at a consistency of 2.5-4 wt %.

21. The method according to claim 1 , wherein the nanofibrillar cellulose obtained from the second step has a Brookfield viscosity of at least 15,000 mPa·s, measured at a consistency of 0.8% and at 10 rpm.

22. The method according to claim 1 , wherein the nanofibrillar cellulose obtained from the second step has turbidity value of 5 to 90 NTU, measured at a consistency of 0.1%.

23. The method according to claim 1 , wherein the nanofibrillar cellulose obtained from the second step has a zero shear viscosity in the range of 5,000 to 50,000, and a yield stress in the range of 3 to 15 Pa, determined by rotational reometer at a consistency of 0.5 wt %.

24. The method of claim 1 , wherein an outlet of the disperser is directly connected to an inlet of the homogenizer such that the fiber material exiting the disperser is directly conveyed to the homogenizer.

25. The method of claim 1 , Wherein the homogenizer comprises an inlet and outlet for fiber material and between the inlet and outlet, a narrow through-flow gap, said homogenizer further comprising means configured to create pressure in the fiber material dispersion before said through-flow gap to cause shearing and impact forces on the fiber material dispersion flowing through said through-flow gap.

26. A device for producing nanofibrillated cellulose from cellulose-based fiber material, comprising:
a disperser comprising an inlet and outlet for fiber material and between the inlet and outlet, several counter-rotating rotors configured to subject fiber material dispersion repeatedly to shear and impact forces by the effect of different counter-rotating rotors;
a homogenizer comprising an inlet and outlet for fiber material and between the inlet and outlet, a narrow through-flow gap, said homogenizer further comprising means configured to create pressure in fiber material dispersion before said through flow gap to cause shearing and impact forces on the fiber material dispersion flowing through said through-flow gap; and
the outlet of the disperser being directly connected to the inlet of the homogenizer such that the fiber material exiting the disperser is directly conveyed to the homogenizer,
wherein the nanofibrillated cellulose has a fibril diameter smaller than about 200 nm.

27. The device according to claim 26 , wherein the device comprises two dispersers connected in series and the outlet of the last disperser is directly connected to the

Assignees

• Upm Kymmene Corp

Inventors

• Nuopponen Markus
• Tamper Juha
• Tienvieri Taisto

Classifications

• C08B15/08 Primary

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

• D21H11/18

  Highly hydrated, swollen or fibrillatable fibres · CPC title

• B02C13/20

  with two or more co-operating rotors · CPC title

• D21C9/007 Primary

  by mechanical or physical means · CPC title

• Y02W30/64

  Paper recycling · CPC title