Protective Function
Paperboard treated with functional coatings represents a specialized class of packaging substrate engineered to resist the penetration of moisture, grease, or gases. Known as barrier board, this material relies on polymeric, aqueous, or metallized layers to protect both the packaged product and the structural integrity of the carton itself. It is widely specified for food, cosmetics, and dry goods packaging where environmental isolation is required.
The efficacy of the protective barrier is typically quantified through water vapor transmission rates or grease resistance indices, which dictate the suitability of the substrate for specific shelf life requirements. When these rates exceed predefined limits, the substrate cannot prevent spoiling or carton softening.
Structural Composition
Coated cellulosics derive their resistant properties from the application of chemical treatments or film laminates onto a solid bleached sulfate or folding boxboard base. While barrier board historically depended on extruded polyethylene films, modern converting processes increasingly utilize water-based dispersion coatings to facilitate repulping during recycling. These formulations are applied during the board manufacturing process or during subsequent converting operations.
The resulting composite must balance barrier density with the flexibility required to withstand creasing without fracturing the protective layer.
Processing Constraint
Adhesive selection presents challenges during carton converting. Because barrier board possesses a modified surface, standard water-based adhesives often fail to form a reliable bond. Converters must deploy specialized hot-melt formulations or mechanical sealing methods.
