Barrier Coating
Protective polymers or aqueous dispersions applied to paperboard substrates establish functional resistance against moisture, grease and vapor transmission during packaging conversion. Barrier paperboard coatings modify surface energy to prevent liquid penetration while preserving the mechanical folding characteristics required for folding carton production. Extrusion polyethylene layers, fluorochemical treatments and dispersion formulations create distinct functional thresholds on the outer substrate plane.
Converting facilities apply these protective formulations during wet end operations or off machine secondary processing steps to satisfy specific product shelf life demands.
Functional Specification
Substrate porosity and smoothness dictate the minimum coat weight necessary to achieve pinhole free coverage across fibrous topologies. Coated paperboard grades must withstand high temperature sealing jaws on vertical form fill seal packaging machinery without transferring polymers to heating elements. Surface tension measurements below thirty eight dynes per centimeter prevent proper ink wetting and adhesive bonding during subsequent converting stages.
Water vapor transmission rates and grease resistance test times quantify the ultimate barrier efficacy of the finished packaging material.
Conversion Tolerance
Coating thickness variations alter caliper dimensions and subsequently affect creasing depth requirements during die cutting operations. Excessive polymer application reduces tear resistance along score lines and triggers board cracking on high speed packaging lines. Minimizing curl requires balanced moisture retention between the coated top sheet and the untreated reverse side of the paperboard.
Precision control systems regulate coat weight distribution across the web width to prevent localized pinholes and maintain consistent seal integrity.
