Barrier-coated cellulose-based substrate, laminated packaging material and packaging container comprising the cellulose-based substrate

A method for producing a gas-barrier coated material, by coating a substrate material with a layer of reduced graphene oxide, comprising the steps of:

• a) providing a substrate material,
• b1) providing a mixed aqueous composition of a dispersion comprising from 0.5 to 15 weight-% graphene oxide and from 0.1 to 5 weight-% a nanocellulose compound, the graphene oxide including monolayer flakes of graphene oxide and multilayer graphene oxide platelets, having up to 20, stacked monolayer flakes of graphene oxide,
• b2) adding from 0.5 to 10 weight-% of a reducing agent to the mixed aqueous composition and allowing the reducing agent to reduce the graphene oxide to form an aqueous gas-barrier coating composition comprising well dispersed and reduced graphene oxide,
• c) coating the aqueous gas-barrier coating composition of reduced graphene oxide obtained from step b2) onto a surface of the substrate material, and
• d) drying the wet coated substrate material obtained from step c), by forced evaporation, to obtain a dry layer of layered reduced graphene oxide particles or flakes on the surface of the substrate material, to form the gas-barrier coated material.