Method for making a film comprising mfc

Patent metadata

Field	Value
Publication number	US-2019276621-A1
Application number	US-201716461897-A
Country	US
Kind code	A1
Filing date	Nov 16, 2017
Priority date	Nov 18, 2016
Publication date	Sep 12, 2019
Grant date	—

Abstract

Method for making a film that comprises microfibrillated cellulose, wherein the film has low OTR values and especially suitable for a tropical environment. The method comprising the steps of providing a suspension comprising microfibrillated cellulose (MFC), forming a film from said suspension, wherein the film having a solid content above 40%, preferably above 50%, treating the film with flame or plasma treatment, such that a surface activation takes place on the film, and cooling the film, wherein the surface of the film having a decreased OTR value and a high moisture resistance.

First claim

1 . Method for making a film comprising microfibrillated cellulose (MFC), wherein the film has low oxygen transmission rate (OTR) values and especially suitable for a tropical environment, the method comprising the steps of:
providing a suspension comprising microfibrillated cellulose (MFC), forming a film from said suspension, wherein the film has a solid content above 40%, preferably above 50%, heating the film quickly with flame treatment or plasma treatment, such that a surface activation takes place on the film, and cooling the film, wherein the surface of the film has a decreased OTR value and a high moisture resistance.

2 . Method according to claim 1 , wherein the cooling step is performed by placing the film in a storage below 40° C.

3 . Method according to claim 1 , wherein the cooling step is performed by placing the film on at least one chilling element.

4 . Method according to claim 3 , wherein the cooling step is performed by placing the film in a chill roll nip.

5 . Method according to claim 4 , wherein the line pressure in the nip is in the range 0-100 kN/m.

6 . Method according to claim 1 , the time between the heat treatment and the cooling is less than 2 s.

7 . Method according to claim 1 , wherein the heat treatment of the film is shorter than 10 s.

8 . Method according to claim 1 , wherein the MFC film web temperature during the heat treatment is in the range 80-200° C.

9 . Method according to claim 1 , wherein that the MFC film web temperature after the cooling step is below 35° C.

10 . Method according to claim 1 , wherein the content of microfibrillated cellulose in the MFC film is at least 50 wt % (weight %), as calculated on the total weight of the dried film.

11 . Method according to claim 1 , wherein the film after the cooling step has a moisture content <15%, and wherein the film has a basis weight of less than 40 g/m 2 .

12 . A film comprising microfibrillated cellulose, wherein the film has low OTR values and especially suitable for a tropical environment, wherein the film is made in accordance with claim 1 .

13 . Method according to claim 1 , wherein the cooling step is performed by placing the film on a chill roll.

14 . Method according to claim 1 , wherein the time between the heat treatment and the cooling is less than 1 s.

15 . Method according to claim 1 , wherein the time between the heat treatment and the cooling is less than 0.5 s.

16 . Method according to claim 1 , wherein the heat treatment of the film is shorter than 6 s.

17 . Method according to claim 1 , wherein the heat treatment of the film is shorter than 3 s.

18 . Method according to claim 1 , wherein the content of microfibrillated cellulose in the MFC film is above 70 wt %, as calculated on the total weight of the dried film.

19 . Method according to claim 1 , wherein the content of microfibrillated cellulose in the MFC film is above 90 wt %, as calculated on the total weight of the dried film.

20 . Method according to claim 1 wherein the film after the cooling step has a moisture content <10%, and wherein the film has a basis weight of less than 40 g/m 2 .

Assignees

• Stora Enso Oyj

Inventors

• Heiskanen Isto
• Backfolk Kaj
• Saukkonen Esa
• Ribu Ville
• Lyytikäinen Katja

Classifications

• D21H25/04

  Physical treatment, e.g. heating, irradiating (D21H25/18 takes precedence; dryer section of machines for making continuous webs of paper D21F5/00) · CPC title

• D21H11/18 Primary

  Highly hydrated, swollen or fibrillatable fibres · CPC title

• C08J2301/02

  Cellulose; Modified cellulose · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• B32B2307/7244

  Oxygen barrier · CPC title