Barrier Integrity
Paperboard grades engineered with specialized chemical or plastic surface treatments resist the migration of grease and moisture into the cellulose matrix. High barrier folding boxboard provides a necessary defense for food packaging when content contact poses a risk of oil staining or structural degradation. These materials combine traditional mechanical pulp layers for thickness with external sealant layers to lock in product quality.
Dense physical barriers prevent sensory loss from oxidation while stopping volatile compounds from exiting the carton.
Manufacturing Process
Extrusion coating or dispersion application occurs during the finishing phase to modify the substrate surface properties. Mills apply these layers under strict tension to avoid curling which complicates later precision cutting. Consistent coverage rates determine the ultimate effectiveness of the barrier during high speed assembly on filling lines.
Inconsistent coat weights lead to premature failure at the score lines where bending stresses the coating structure.
Substrate Performance
Technical requirements for these boards prioritize resistance levels against specific chemical agents often quantified by the Kit test or Cobb test results. Conversion equipment relies on the predictable response of the treated surface to adhesives because standard starch glues struggle to bond with non-porous layers. Producers frequently select specialized heat-sealable resins to eliminate the need for liquid adhesives during the formation of the carton base.
Correct application of these polymers ensures that a box retains its hermetic seal under prolonged environmental exposure.
