Foldable paper-based substrates coated with water-based coatings and process for coating foldable paper-based substrates

A process for preparing a coated foldable paper-based substrate from a foldable paper-based substrate having two surfaces, the process comprising:

• applying a primer coat having a viscosity from about 4500 cP to about 10000 cP measured on a Brookfield viscometer at 20 rpm with a spindle 3, to one of the surfaces of the paper-based substrate, wherein the primer coat comprises a wax-free aqueous dispersion of a styrene-butadiene copolymer, a styrene-acrylate copolymer, a styrene-acrylonitrile copolymer, a styrene-acrylonitrile-acrylate copolymer or any mixtures thereof, said wax-free aqueous dispersion being characterized in that a dry film thereof has a flexibility measured as the percentage of elongation-to-break of at least 1100% for a film thickness from about 1.0 to about 2.5 mm,
• applying a top coat having a viscosity from about 40 cP to about 10000 cP measured on a Brookfield viscometer at 20 rpm with a spindle 3, over the primer coat, wherein top coat is blocking resistant and comprises an aqueous dispersion of a polymer or copolymer capable of providing at least one of water resistance, grease or oil resistance, heat resistance, an odor barrier, a moisture barrier, or heat sealability to the coated foldable paper-based substrate, wherein said top coat is characterized in that a dry film thereof has a flexibility measured as the percentage of elongation-to-break of at least 570% for a film thickness from about 1.5 to about 2.5 mm, and
• drying the coats thereby forming the coated foldable paper-based substrate;
• wherein applying the primer coat and top coat is performed using a curtain coater or a slot die coater.