Method for improving the barrier properties of a paper substrate

Method for improving the water and/or oil resistance of a paper substrate comprising:

• i) providing a paper substrate;
• ii) applying to the paper substrate a water-based barrier coating composition having a solids content from 10 to 55 wt % (% by weight) and comprising from 50 to 95 wt % of an aqueous polymer dispersion having a solids content from 20 to 50 wt % and obtained by emulsion polymerization of:
• a) from 0 to 40% by weight of at least one ethylenically unsaturated monomer selected among styrene or substituted styrene,
• b) from 15 to 55% by weight of at least one ethylenically unsaturated monomer selected among C Cio-alkyl (meth)acrylates or cycloalkyl (meth)acrylates,
• in the absence of ethylenically unsaturated acid monomers and in the presence of
• c) from 45 to 80% by weight of degraded starch having a molecular weight Mn of 500 to 30,000 Da,
• wherein the percentage amounts of (a), (b) and (c) are referred to the sum of (a)+(b)+(c).