Liquid Formulation
Polymeric formulations applied in liquid form to paperboard substrates create a continuous surface layer that resists water and grease penetration. Applying an aqueous barrier coating to packaging boards provides a recyclable alternative to traditional polyethylene extrusion, preventing moisture migration from or into the packaged product. This process relies on water-soluble or water-dispersible synthetic polymers that form a tight matrix upon drying.
The liquid formulation must balance viscosity with solid content to ensure uniform distribution under high-speed blade or air-knife applicators, preventing pinholes that compromise the protection of the packaged goods.
Barrier Performance
Resistance to liquid transmission represents the primary functional benchmark for treated paperboard surfaces. A typical aqueous barrier coating uses polymer particles, mineral pigments and functional additives to block the passage of liquids while maintaining the compostability of the underlying cellulose fibres. Low coating weight or uneven drying can leave pinholes in the polymer film, which leads to localized barrier failure when the board is exposed to fatty or damp foods.
Converting Requirement
Downstream processing of coated paperboard requires specific heating and gluing parameters to ensure package integrity. Because the cured aqueous barrier coating resists moisture, standard water-based adhesives cannot easily penetrate the surface. Converters use hot-melt adhesives to bypass this resistance.
