Polyurethane Soft Touch Film Selection for Folding Cartons
Polyurethane soft-touch films provide superior scratch resistance and score fold integrity compared to BOPP but require higher temperature control and lower web yields.
Dynamic Coefficient of Friction
Surface Friction
Sliding resistance describes the kinetic opposition encountered when two manufactured paperboards move against each other under a constant normal load. Measured during continuous web feed operations, the dynamic coefficient of friction dictates how reliably a sheet travels through high-speed converting machinery without tearing or skewing. Excessive resistance causes jamming along folding carton guides, whereas inadequate drag leads to misregistration during multi-color offset printing runs.
Laboratory testers quantify this property by dragging a sled across a horizontal board surface at a controlled speed, recording the steady-state force required to maintain motion. Converting plants establish strict acceptable bands for this parameter to prevent production downtime caused by erratic web tension.
Addictive Modification
Surface additives applied during wet end processing or size press application alter the sliding behavior of paperboard substrates. Aqueous dispersions containing polyethylene waxes or fluorochemical agents lower the kinetic sliding force to help corrugated blanks slide smoothly into automatic erecting machinery. Calcium carbonate fillers increase surface roughness and modify the microscopic contact area between adjacent sheets, raising the frictional value accordingly.
Coat weight uniformity directly influences sliding consistency, because localized variations in binder migration create unpredictable drag profiles across a master roll. Converters must monitor these chemical additions closely because excessive lubrication compromises subsequent glue adhesion during carton sealing operations.
Mechanical Tolerance
Production specifications for folding carton blanks require tight control bands to ensure reliable feeding in high-speed packaging lines. Automatic blister packing machines demand predictable sliding resistance so that blister cards do not slip past indexing lugs or double-feed into the sealing station. Packaging engineers balance the kinetic sliding value against stacking stability, because lower friction increases the risk of palletized corrugated loads shifting during transit.
Finished goods manufacturers verify this frictional performance using inclined plane methods before accepting large paperboard shipments from the mill.
Standardized Laboratory Methods for Evaluating Matte Print Coating Burnishing
Standard laboratory burnish evaluation uses controlled sled friction and 60-degree delta gloss measurements to quantify matte coating asperity degradation.