US 12,258,711 B2
Multilayer film comprising highly refined cellulose fibers
Isto Heiskanen, Imatra (FI); Kaj Backfolk, Lappeenranta (FI); Katja Lyytikäinen, Imatra (FI); Jukka Kankkunen, Imatra (FI); and Anna Kauppi, Lappeenranta (FI)
Assigned to Stora Enso OYJ, Helsinki (FI)
Appl. No. 17/995,447
Filed by Stora Enso OYJ, Helsinki (FI)
PCT Filed Apr. 14, 2021, PCT No. PCT/IB2021/053069
§ 371(c)(1), (2) Date Oct. 4, 2022,
PCT Pub. No. WO2021/209915, PCT Pub. Date Oct. 21, 2021.
Claims priority of application No. 2050425-4 (SE), filed on Apr. 15, 2020.
Prior Publication US 2023/0135217 A1, May 4, 2023
Int. Cl. D21F 9/00 (2006.01); D21F 11/00 (2006.01); D21H 11/18 (2006.01); D21H 17/29 (2006.01); D21H 21/06 (2006.01); D21H 27/38 (2006.01)
CPC D21F 9/006 (2013.01) [D21F 11/002 (2013.01); D21H 11/18 (2013.01); D21H 17/29 (2013.01); D21H 21/06 (2013.01); D21H 27/38 (2013.01)] 23 Claims
 
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/m3.