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

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

• a) providing and forwarding a substrate material web,
• b) coating the substrate material web while it is being forwarded with a first layer of an aqueous composition comprising reducing agent and water-dispersible polymer,
• c) drying the first layer, by forced evaporation, to form a first dry layer comprising reducing agent and water-dispersible polymer,
• d) providing an aqueous composition comprising graphene oxide including monolayer flakes of graphene oxide and multilayer graphene oxide platelets, having up 20 stacked monolayer flakes of graphene oxide,
• e) coating the aqueous composition of graphene oxide onto the substrate material web while it is being forwarded,
• f) drying the wet coating of aqueous graphene oxide on the substrate material web, by forced evaporation, to obtain a second dry layer of layered graphene oxide particles or flakes,
• g) allowing the reducing agent of the first dry layer to reduce the graphene oxide of the second layer to form a barrier-coated substrate material web with a dry layer of reduced graphene oxide,
• wherein steps c) and d) can take place before or after steps d), e) and f), such that either the first dry layer or the second dry layer may be formed first.