Viscoelastic Creep Compliance and Interfacial Fracture Energy in Paperboard Laminates
Creep compliance dictates long-term carton deformation, while interfacial fracture energy governs delamination under score bending and pallet loads.
Paperboard Laminates
Composite Structure
Multilayer packaging materials combine paperboard with polymer layers or metal foils to produce a composite sheet with high stiffness and barrier properties. These paperboard laminates prevent the migration of gases and liquids while maintaining structural rigidity for carton formation. They are widely used for liquid packaging board and aseptic food containers.
Barrier Function
Base board provides the necessary thickness and bending resistance, while the extruded coatings supply moisture resistance and heat-sealable surfaces. In paperboard laminates, the combination of materials must be balanced to prevent curl during printing and converting. Adhesion between the distinct layers depends on surface pre-treatments like corona discharge or chemical primers.
Inadequate layer adhesion causes delamination, which destroys the integrity of the barrier.
Production Process
Converting speed and product shelf-life are heavily influenced by the uniformity of the laminated structure. During high-speed extrusion coating, the polymer thickness must be controlled to prevent pinholes and ensure a consistent seal. Aluminium foil layers are often incorporated to block light and oxygen, which protects sensitive liquid products from oxidation.
Recovering and recycling the wood fibres from these multi-material sheets requires specialized hydrapulping techniques to separate the polymer and metal from the pulp. Optimising the laminate structure allows producers to minimize polymer use while ensuring product protection.