Multilayer film comprising highly refined cellulose fibers

Patent metadata

Field	Value
Publication number	US-2023135217-A1
Application number	US-202117995447-A
Country	US
Kind code	A1
Filing date	Apr 14, 2021
Priority date	Apr 15, 2020
Publication date	May 4, 2023
Grant date	—

Abstract

The present invention relates to a method for manufacturing a multilayer film comprising highly refined cellulose fibers, the method comprising the steps of: a) forming a first wet web by applying a first pulp suspension comprising highly refined cellulose fibers on a first wire; b) partially dewatering the first wet web to obtain a first partially dewatered web; c) forming a second wet web y applying a foamed second pulp suspension comprising highly refined cellulose fibers and a foaming agent on a second wire; d) partially dewatering the foamed second wet web to obtain a second partially dewatered web; e) joining the first and second partially dewatered web to obtain a multilayer web; and f) further dewatering, and optionally drying, the multilayer web to obtain a multilayer film comprising highly refined cellulose fibers.

First claim

1 . A method for manufacturing a multilayer film comprising highly refined cellulose fibers, the method comprising the steps of:
a) forming a first wet web by applying a first pulp suspension comprising highly refined cellulose fibers having a Schopper-Riegler (SR) value of 65 or higher, as determined by standard ISO 5267-1, on a first wire; b) partially dewatering the first wet web to obtain a first partially dewatered web; c) forming a second wet web by applying a foamed second pulp suspension comprising highly refined cellulose fibers having a Schopper-Riegler (SR) value of 65 or higher, as determined by standard ISO 5267-1, and a foaming agent on a second wire; d) partially dewatering the foamed second wet web to obtain a second partially dewatered web; e) joining the first partially dewatered web and the second partially dewatered web to obtain a multilayer web; and f) further dewatering, the multilayer web to obtain a multilayer film comprising highly refined cellulose fibers, wherein the multilayer film has a Gurley Hill value of at least 10,000 s/100 ml, as measured according to standard ISO 5636/6, and a density above 600 kg/m 3 .

2 . The method according to claim 1 , wherein a dry solids content of the first pulp suspension is in a range of 0.1-0.7 wt %.

3 . The method according to claim 1 , wherein dry solids content of the foamed second pulp suspension is in a range of 0.1 -15 wt %.

4 . The method according to claim 1 , wherein a density of the foamed second pulp suspension is below 800 kg/m 3 .

5 . The method according to claim 1 , wherein the foamed second pulp suspension comprises a foamed aqueous mixture of highly refined cellulose fibers and a foaming agent.

6 . The method according to claim 5 , wherein the foaming agent is a polymeric foaming agent.

7 . The method according to claim 5 , wherein the foaming agent is an amphiphilic polymer.

8 . The method according to claim 5 , wherein foaming agent is selected from a group consisting of: polysaccharides, hydrophobically modified polysaccharides, proteins, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, and mixtures thereof.

9 . The method according to claim 5 , wherein the foaming agent is a polysaccharide selected from a group consisting of: cellulose, starch, hemicellulose, and mixtures thereof.

10 . The method according to claim 5 , wherein the foaming agent is polysaccharide selected from a group consisting of: cellulose acetate, hydrophobically modified cellulose acetate (CA), ethyl(hydroxyethyl)cellulose (EHEC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), sodium carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), sulfoethylcellulose, starch, and mixtures thereof

11 . (canceled)

12 . The method according to claim 5 , wherein the foaming agent has a molecular weight above 5,000 g/mol.

13 . The method according to claim 5 , wherein the foamed second pulp suspension comprises foaming agent in a range of 0.1-80 wt % based on a total dry weight of the foamed second pulp suspension.

14 . (canceled)

15 . (canceled)

16 . The method according to claim 1 , wherein the first pulp suspension, the second pulp suspension, or both comprises at least 50 wt % highly refined cellulose fibers, based on a total dry weight of said pulp suspension.

17 . The method according to claim 1 , wherein the first pulp suspension, the second pulp suspension, or both is formed from a cellulose furnish having a Schopper-Riegler (SR) value in a range of 65-99.

18 . The method according to claim 1 , wherein the highly refined cellulose fibers microfibrillated cellulose (MFC).

19 . The method according to claim 18 , wherein the first pulp suspension, the second pulp suspension, or both comprises 50-99 wt % MFC, based on a total dry weight of said pulp suspension.

20 . The method according to claim 1 , wherein the first pulp suspension comprises 1-50 wt % unrefined or slightly refined cellulose fibers, having a Schopper-Riegler (SR) value below 30, as determined by standard ISO 5267-1, based on a total dry weight of the first pulp suspension.

21 . The method according to claim 1 , wherein the foamed second pulp suspension comprises 1-50 wt % of long fibers having a mean fiber length above 0.5 mm, based on a total dry weight of the pulp suspension.

22 . The method according claim 21 , wherein said long fibers are selected from a group consisting of unrefined or slightly refined cellulose fibers, regenerated cellulose fibers, and thermoplastic polymer fibers.

23 . The method according to claim 1 , wherein a basis weight of the first wet web, the second wet web, or both based on a total dry weight of said wet web is less than 50 g/m 2 .

24 . (canceled)

25 . (canceled)

26 . (canceled)

27 . (canceled)

28 . (canceled)

29 . The method according to claim 1 , wherein a basis weight of the multilayer web based on a total dry weight of the web is in the range of 10-100 g/m 2 .

30 . (canceled)

31 . The method according to claim 1 , wherein a KIT value of the multilayer film is at least 6, as measured according to standard ISO 16532-2.

32 . (canceled)

33 . The method according to claim 1 , wherein the multilayer film has a Gurley Hill value of at least 25,000 s/100 ml, as measured according to standard ISO 5636/6.

34 . (canceled)

35 . (canceled)

36 . (canceled)

37 . (canceled)

Assignees

• Stora Enso Oyj

Inventors

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

Classifications

• D21F11/002

  by using a foamed suspension · CPC title

• D21H27/30

  Multi-ply (for surface covering D21H27/18; making on paper-making machines D21F9/00, D21F11/00) · CPC title

• B32B2307/7242

  Non-permeable · CPC title

• B32B2307/7244

  Oxygen barrier · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title