Repulpable, water repellant paperboard

A method of making a water-repellant fibrous web which comprises:

• providing a fibrous web;
• applying to the surface of said web an aqueous coating which comprises a polystyrene-butabiene polymer copolymerized with a monomer having carboxylic acid pendant groups, pigments, a wax component selected from the group consisting of paraffin wax and polyethylene wax emulsions and mixtures thereof, and a cross-linking agent which provides zinc ions;
• and
• reacting the cross-linking agent with the carboxylic acid groups of the polymer to cause the formation of ionic cross-linkages between the carboxylic acid groups of adjacent polymer chains and provide a substantially pin-hole free continuous coating on the surface of the web;
• wherein said pigments are selected from the group consisting of aluminum trihydrate, barium sulfate, calcium carbonate, mica (potassium aluminum silicates), nepheline syenite (sodium potassium aluminosilicate), finely ground silica sand and other natural and synthetic type of silicates, talc (magnesium silicates), wollastonite (calcium metasilicates), bentonite (montmorillonite, smectite) and clay.