Multi-Ply Secondary Substrate
Multi-layered paperboard grades manufactured predominantly from recovered secondary cellulose fibres are engineered for folding carton applications. Typically designated in European trade standards as white lined chipboard or duplex and triplex board, the substrate features a top surface plied from bleached virgin or high-grade de-inked pulp, a core of mixed recycled waste fibres, and a grey or kraft reverse side. Mineral pigment coatings applied to the top liner furnish provide smoothness and ink holdout for commercial printing operations.
The grade delivers cost-effective structural packaging for dry foods, household goods, and consumer hardware. It stops competing with pure virgin grades when ultra-high sensory purity or low-temperature moisture resistance is strictly demanded.
Mechanical Attributes
Incorporating recycled fibres alters the bulk density, tensile stiffness, and creasing behaviour of the finished board compared to virgin solid bleached sulphate. Because recycled fibres have undergone previous drying and re-pulping cycles, their internal cell walls are hornified, resulting in lower natural bonding strength and reduced dimensional elasticity. This requires converters to adjust scoring rule geometries to achieve clean internal ply delamination without surface liner cracking during die-cutting.
Package designers must also specify higher board calipers to achieve equivalent box compression strength and top-load performance on automated packing lines.
Regulatory Suitability
Using recycled paperboard in direct food contact packaging requires barrier integration to prevent the migration of volatile contaminants. Secondary fibre cores inherently contain residues of printing inks, adhesives, and mineral oils from past lifecycle uses. Converters address migration risks by applying functional barrier coatings, incorporating virgin inner liners, or inserting sealed barrier pouches inside the outer carton.
Routine screening tests ensure that residual chemical migrants remain fully compliant with European and global food safety statutory thresholds.
