Method for manufacturing films comprising highly refined cellulose fibers

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.