Multilayer film comprising highly refined cellulose fibers

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.