Mineral Coating Pigment Packing Micro Geometry and Pore Volume Distribution
Pigment micro-geometry and particle packing dictate coat pore volume distribution, controlling ink vehicle absorption rate, print gloss, and coat strength.
Paperboard Stiffness Yield
Bending Resistance
Force required to bend a paperboard sheet through a specified angle, measured relative to the basis weight of the material. In the manufacturing of folding cartons, paperboard stiffness yield determines the structural integrity and bulge resistance of the finished package. This metric represents the efficiency with which a mill uses wood fibre to achieve the necessary strength and stiffness.
Structural Parameter
Board thickness, or caliper, represents the most influential factor in this calculation, because bending stiffness increases with the cube of the sheet’s thickness. Mills optimize this property by using multi-ply forming, where bulky, high-yield mechanical pulps are placed in the center of the board, and dense, strong chemical pulps are placed on the outer layers. This layered structure acts like a steel I-beam, which maximizes stiffness while minimizing the overall weight of the package.
A high paperboard stiffness yield enables the production of lightweight boxes that can withstand the stacking pressures of storage and transport.
Converting Outcome
Cartons made from board with inadequate stiffness are prone to bulging during automatic filling and may collapse when stacked on pallets. This failure causes damage to the enclosed product and disrupts retail displays. Maintaining consistent stiffness is essential for the smooth operation of high-speed packaging lines.