Functional Barrier Qualification for Mineral Oil Hydrocarbon Migration in Board
Functional barrier qualification requires gas chromatography verification of saturated and aromatic hydrocarbon migration below detection limits on creased board.
Barrier Layer Coat Weight
Coating Mass
Dry coating quantity measured in grams per square metre defines the thickness and continuous coverage of functional polymer or bio-polymer formulations applied onto paperboard substrates. A precise barrier layer coat weight ensures that pinholes or voids do not form across the fiber surface during blade or curtain coating operations. Where the mass falls below three grams per square metre, moisture vapour transmission rates rise rapidly because exposed cellulose fibers draw liquid through capillary channels.
Film Integrity
Substrate porosity and surface roughness dictate the minimum pickup required to establish an uninterrupted seal across recycled board grades. Heavy coat weights increase production cost and cause drying defects such as blistering or skinning during infrared oven passage. A double-coated arrangement splits the total application into two passes, allowing a base primer to smooth the topography before the barrier layer coat weight is applied in a secondary station.
Splitting the application prevents coat failure along fold lines when converting folding boxboard into frozen food cartons.
Substrate Tolerance
Gravimetric testing following standard drying protocol isolates the dry weight of the coating polymer from wet slurry measurements. Online infrared gauges provide real-time scanning across the machine width to maintain cross-direction uniformity within tight limits.