Greaseproof and Barrier Stocks for Fills That Defeat Plain Kraft
High-density refining and fluorine-free dispersion coatings block lipid migration and moisture breakdown where unrefined kraft papers fail under aggressive fills.
Fluorine-Free Barrier Sizing
Chemical Sizing
Bio-based and synthetic polymer treatments applied to paper fibers provide liquid and grease resistance without using per- and polyfluoroalkyl substances. Paper mills apply fluorine-free barrier sizing to produce oil-resistant paperboard for food packaging applications. These sizing agents utilize acrylic polymers or modified starches to coat cellulose fibers and reduce surface porosity.
Treatment occurs either at the wet end of the paper machine or via surface application at the size press.
Oil Resistance
Surface tension modification blocks hydrocarbon penetration by forming a dense physical barrier across the cellulosic web. Alternative chemistry relies on film-forming polymers to achieve grease holdout without creating hazardous persistent fluorinated compounds. Mill laboratories measure grease resistance using kit test liquids and vegetable oil penetration assays under elevated temperatures.
Achieving high kit test ratings without fluorochemicals requires higher polymer pick-up weights and precise control of drying profiles.
Food Contact
Regulatory compliance mandates that oil-resistant barrier formulations meet food contact standards without leaching harmful synthetic additives into food items. Paperboard treated with non-fluorinated formulations undergoes migration testing with food simulants like tenax and rectified olive oil. Converting plants use these treated boards to manufacture fast food wrappers and takeaway containers.
The absence of perfluorinated chemistry ensures that repulping operations can reprocess post-consumer packaging waste without contaminating recycled fiber streams. Fluorine-free barrier sizing enables paper mills to satisfy stringent environmental standards while delivering functional oil and grease resistance for sustainable packaging.