A METHOD FOR PRODUCING A BARRIER SUBSTRATE COMPRISING A MICROFIBRILLATED CELLULOSE FILM AND A POLYMER FILM

• Main Authors: Karppinen, Anni, Backfolk, Kaj, Nylén, Otto
• Format: Patent
• Language: English
• Published: 19.03.2024
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; CHEMISTRY; COMPOSITIONS BASED THEREON; COMPOSITIONS OF MACROMOLECULAR COMPOUNDS; GENERAL PROCESSES OF COMPOUNDING; IMPREGNATING OR COATING OF PAPER; LAYERED PRODUCTS; LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT ORNON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PAPER NOT OTHERWISE PROVIDED FOR; PAPER-MAKING; PERFORMING OPERATIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; PRODUCTION OF CELLULOSE; PULP COMPOSITIONS; TEXTILES; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; WORKING-UP

The present invention relates to a method for producing a barrier substrate comprising a microfibrillated cellulose (MFC) film and a polymer film. The method comprises providing a suspension comprising 50-100 weight-% MFC based on total dry weight and having a dry content of 1-40 weight-%. A wet MFC film is formed of the suspension by casting on a non-porous support and the wet MFC film positioned on the support is dewatered and/or dried to a dry MFC film having a moisture content of 20 weight-% or less. A polymer film is applied on the dry MFC film positioned on the support to form an intermediate substrate, which is pressed in at least one nip to form the barrier substrate. The invention relates also to a barrier substrate obtained by the method, a laminate comprising the barrier substrate and a paper or paperboard substrate, and a packaging material comprising the barrier substrate or the laminate.