US 12,467,202 B2
Method for manufacturing films comprising highly refined cellulose fibers
Isto Heiskanen, Imatra (FI); and Kaj Backfolk, Lappeenranta (FI)
Assigned to Stora Enso OYJ, Helsinki (FI)
Appl. No. 17/998,235
Filed by Stora Enso OYJ, Helsinki (FI)
PCT Filed May 10, 2021, PCT No. PCT/IB2021/053949
§ 371(c)(1), (2) Date Nov. 8, 2022,
PCT Pub. No. WO2021/229406, PCT Pub. Date Nov. 18, 2021.
Claims priority of application No. 2050548-3 (SE), filed on May 11, 2020.
Prior Publication US 2023/0349099 A1, Nov. 2, 2023
Int. Cl. D21F 1/80 (2006.01); D21F 11/02 (2006.01); D21H 11/18 (2006.01)
CPC D21F 1/80 (2013.01) [D21F 11/02 (2013.01); D21H 11/18 (2013.01)] 28 Claims
 
1. A method for manufacturing a film comprising highly refined cellulose fibers in a paper machine, the method comprising the steps of the following sequence:
a) forming a wet web by applying an aqueous pulp suspension comprising highly refined cellulose fibers having a Schopper-Riegler (SR) value of 65 or higher, on a wire;
b) dewatering the wet web on the wire to obtain a dewatered web comprising highly refined cellulose fibers,
wherein the dewatering comprises membrane assisted dewatering using a gas permeable membrane temporarily applied to the wet web, wherein the gas permeable membrane has an air permeability lower than an air permeability of the wire,
wherein the air permeability of the gas permeable membrane is less than 75% of the air permeability of the wire, and
wherein the wet web is pressed between the gas permeable membrane and the wire; and,
c) drying the dewatered web to obtain a film comprising the highly refined cellulose fibers, the film having a grammage in a range of 20 to 100 g/m2 and a density above 600 kg/m3,
wherein the film is transparent or translucent to visible light, and
wherein the film has a KIT value of at least 10, as measured according to standard ISO 16532-2.