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

A method for producing an oxygen barrier material for a packaging material, by coating a substrate material web with a layer of reduced graphene oxide, the method comprising:

• a) coating an aqueous composition onto a substrate material web to form a wet coating on the substrate material web, the aqueous composition that is coated onto the substrate material web including from 0.1 to 15 weight-% of graphene oxide, from 0 to 5 weight-% of additives and from 85 to 99.9 weight-% of water, the graphene oxide including monolayer flakes of graphene oxide and multilayer graphene oxide platelets, having up to 20 stacked monolayer flakes of graphene oxide,
• b) drying the wet coating on the substrate material web by forced evaporation to obtain a first dry layer of layered graphene oxide particles or flakes on the substrate material web,
• c) applying an aqueous solution of a reducing agent onto the first dry layer of graphene oxide on the substrate material web to form a wet aqueous coating of the reducing agent on the substrate material web,
• d) directly following step c) drying the wet aqueous coating of the reducing agent, by forced evaporation to obtain a second dry layer of reducing agent on the substrate material web,
• e) forming a barrier-coated substrate material web with a dry layer of reduced graphene oxide by exposing the first dry layer of layered graphene oxide particles or flakes to the second dry layer of reducing agent for a minimum predetermined time at a minimum pre-determined temperature, and
• performing a further step f) and/or a further step g) before step e),
• wherein the step f) is coating or laminating the substrate material web with a further layer of a polymer to cover the second dry layer of the reducing agent, and
• wherein the step h) is winding the coated and dried, substrate material web onto a reel.