Coating Function
Polymeric dispersion formulations applied to paperboard surfaces produce water resistance without requiring extruded polyethylene film layers. The application of an aqueous barrier creates a continuous dried film across cellulose fibres to inhibit liquid penetration and moisture vapour transport. Blade or rod coaters meter this water-borne acrylic or styrene-butadiene latex onto paper substrates during web processing.
The coating seals surface pores while preserving recyclability in repulping operations.
Application Boundary
Thermal exposure during heat-sealing operations soft-points latex polymers and degrades joint tightness. When temperature thresholds are exceeded, the polymer matrix thins along seam edges. Substrate performance drops rapidly in saturated steam conditions.
Performance Variance
Pinhole defects arising from uneven coat weights reduce resistance against liquid penetration during extended contact times. Standard application targets range from three to eight grams per square metre of dry coat weight to achieve uniform film coverage without compromising repulpability. Lower coat weights permit exposed cellulose fibres to wick water into the inner board matrix through capillary action, which causes structural softening and delamination along package creases.
Higher coat weights increase chemical cost and can cause blocking during roll storage on converting lines. Rheology control additives prevent pinholes by maintaining stable leveling properties as wet film dries. Moisture vapour transmission rate measurements confirm film integrity across convertor production lots.
