Fiber Composition
Multi-layered packaging material produced from recovered paper and board fibers provides a sustainable option for carton manufacturing. This grade, termed recycled multiply board, is made by combining several wet webs of recycled pulp on a multi-cylinder paper machine. It allows the use of different pulp grades in the outer and inner layers to balance cost and performance.
Layer Structure
Outer layers typically consist of higher-quality recycled fibers to provide a smooth printing surface and good creasing characteristics. In contrast, the internal plies use cheaper mixed waste to build bulk and stiffness. This multi-ply structure is susceptible to delamination if the bonding between the wet webs is not maintained during the pressing and drying stages.
Mechanical Stiffness
Stiffness is a defining property of this grade and is managed by adjusting the thickness of the center plies. High-speed packaging lines require a minimum stiffness to prevent the panels of the carton from bulging when filled with product. Regular testing of the ply bond strength and bending resistance ensures that the board can withstand the mechanical stresses of both printing and product distribution.
This monitoring allows converters to maintain consistent performance even when the quality of the incoming recovered fiber varies. It prevents unexpected downtime during high-volume production runs.
