Inter-Ply Bond Measurement Standards in Recycled Paperboard Production
Inter-ply bond standards mandate TAPPI T 541 or ISO 16260 testing under strict ISO 187 conditioning to prevent converting delamination on recycled paperboard.
Multi-Ply Recycled Board
Layered Composition
Packaging substrates manufactured by joining several distinct layers of recovered paper fibres provide structural thickness at a lower material cost. A multi-ply recycled board typically consists of a high-quality outer liner and thick core plies made from mixed paper. This structure optimizes stiffness and is widely used for folding cartons and tubes.
Fibre Fractionation
Producing high-performance boards from recycled stock requires sorting the recovered material into different fibre fractions. Long fibres from corrugated boxes are directed to the outer plies or core layers to provide tearing resistance and bending stiffness. Short fibres from office waste are placed in the intermediate layers where bulk is more important than tensile strength.
This fractionation allows the mill to tailor the physical properties of each layer, ensuring the finished board can withstand the high-pressure runs of printing, creasing and high-speed folding on automated carton lines.
Board Stiffness
The stiffness of the board increases with the cube of its thickness, making multi-ply construction highly efficient. By using bulky, less refined recycled fibres in the center, mills can increase the caliper without adding excessive weight or cost. The outer plies are then heavily refined and calendered to create a smooth surface for high-quality printing.
This design ensures that the finished carton possesses the rigidity needed to protect its contents during transit.