Barrier-coated fibrous cellulose substrate and laminated packaging material

Barrier-coated cellulose-based fibrous substrate, for use as oxygen barrier in a heat sealable laminated packaging material for oxygen-sensitive food products, comprising a fibrous cellulose substrate having a grammage from 30 to 80 g/m2, and a density from 700 to below 900 kg/m3, a first gas barrier coating, applied on a first side of the fibrous cellulose substrate by dispersion or solution coating of an aqueous oxygen barrier composition followed by drying by evaporation, wherein the barrier-coated cellulose-based fibrous substrate further has a steam-resistant base coating, comprising from 25 to 96 weight-% of inorganic particles and from 4 to 75 wt-% of a polymer binder, per dry weight, positioned beneath the first gas barrier coating and applied by aqueous dispersion coating onto, directly adjacent and contacting the first side of the fibrous cellulose substrate, the thus barrier-coated fibrous cellulose substrate providing gas barrier properties in the heat sealable laminated packaging material.