Method for fractionation of highly refined cellulose

Patent metadata

Field	Value
Publication number	US-2024141588-A1
Application number	US-202218548367-A
Country	US
Kind code	A1
Filing date	Mar 8, 2022
Priority date	Mar 10, 2021
Publication date	May 2, 2024
Grant date	—

Abstract

The present invention relates to a method for fractionation of a highly refined cellulose pulp into a fine fraction and coarse fraction, said method comprising: a) providing a highly refined cellulose pulp suspension comprising highly refined cellulose pulp having a Schopper-Riegler (SR) number in the range of 40-98 as determined by standard ISO 5267-1 and a content of fibers having a length >0.2 mm of at least 7 million fibers per gram based on dry weight; b) subjecting the highly refined cellulose pulp suspension to dewatering in a belt filter; c) collecting the dewatered retentate as the coarse fraction; and d) collecting the filtrate as the fine fraction; wherein the collected fine fraction contains 2-50 wt % of the solids of the highly refined cellulose pulp suspension provided in step a).

First claim

1 . A method for fractionation of a highly refined cellulose pulp into a fine fraction and a coarse fraction, said method comprising:
a) providing a highly refined cellulose pulp suspension comprising highly refined cellulose pulp having a Schopper-Riegler (SR) number in a range of 40-98 as determined by standard ISO 5267-1 and a content of fibers having a length >0 2 mm of at least 7 million fibers per gram based on a dry weight; b) subjecting the highly refined cellulose pulp suspension to dewatering in a belt filter; c) collecting a dewatered retentate as a coarse fraction; and d) collecting a filtrate as a fine fraction; wherein the fine fraction contains 2-50 wt % of the solids of the highly refined cellulose pulp suspension provided in step a).

2 . The method according to claim 1 , wherein the highly refined cellulose pulp provided in step a) has a Schopper-Riegler (SR) number in a range of 50-98, as determined by standard ISO 5267-1.

3 . The method according to claim 1 , wherein the fine fraction contains 5-40 wt % or 10-30 wt % of the solids of the highly refined cellulose pulp suspension provided in step a).

4 . The method according to claim 1 , wherein a consistency of the highly refined cellulose pulp suspension provided in step a) is in a range of 0.1-1.5 wt %.

5 . The method according to claim 1 , wherein a consistency of the retentate collected in step c) is at least 5 wt %.

6 . The method according to claim 1 , wherein the coarse fraction has a Schopper-Riegler (SR) number below 95, as determined by standard ISO 5267-1.

7 . The method according to claim 1 , wherein the fine fraction is able to pass through a 200 mesh screen.

8 . The method according to claim 1 , wherein the belt filter comprises a wire belt having an air permeability above 4000 m 3 /m 2 /hour at 100 Pa.

9 . The method according to claim 1 , wherein a belt of the belt filter moves at rate of at least 50 m/min.

10 . The method according to claim 1 , wherein a dwell time of the highly refined cellulose pulp on a belt of the belt filter is below 7 seconds.

11 . The method according to claim 1 , wherein the belt filter is a single-wire or twin-wire type belt filter.

12 . The method according to claim 1 , wherein a portion of cellulose fines obtained from the fine fraction is added to the coarse fraction to obtain a highly refined cellulose pulp with a decreased water retention, or an increased homogeneity, or both.

13 . The method according to claim 12 , wherein an amount of cellulose fines added to the coarse fraction in is less than an amount of cellulose fines collected in step d).

14 . The method according to claim 12 , wherein a pulp obtained after addition of the portion of the cellulose fines has a lower Schopper-Riegler (SR) number than the highly refined cellulose pulp provided in step a).

15 . The method according to claim 12 , wherein a pulp obtained after addition of the portion of the cellulose fines has a lower water retention value (WRV) than the highly refined cellulose pulp provided in step a).

16 . A highly refined cellulose pulp with a decreased water retention, or, an increased homogeneity, or both, obtained by the method according to claim 12 .

17 . (canceled)

18 . A barrier film comprising: the a highly refined cellulose pulp of claim 16 .

Assignees

• Stora Enso Oyj

Inventors

• Heiskanen Isto
• Backfolk Kaj
• Kankkunen Jukka
• Kauppi Anna

Classifications

• D21F11/00

  Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines · CPC title

• D21C9/18 Primary

  De-watering (de-watering in general F26B); {Elimination of cooking or pulp-treating liquors from the pulp}(D21C9/002, D21C9/02 take precedence; paper-making machines D21F; strainers in digesters D21C7/00; presses in general B30B) · CPC title

• D21C11/0042

  Fractionating or concentration of spent liquors by special methods (concentration by evaporation D21C11/10) · CPC title

• D21D99/00 Primary

  Subject matter not provided for in other groups of this subclass · CPC title

• D21H11/18 Primary

  Highly hydrated, swollen or fibrillatable fibres · CPC title