Multi Ply Packaging Grade
Multi-layered folding boxboard manufactured primarily from recovered paper fibers features a bright, coated top surface over a grey or brown recycled core. Recycled white lined chipboard delivers an economical, rigid packaging material designed for retail consumer cartons, dry food packaging and secondary pharmaceutical packaging. Designated broadly under European packaging classifications as WLC or GD grades, this substrate combines virgin chemical pulp or sorted deinked office waste on the printing face with mixed recovered fibers in the internal plies.
Multiple mineral coating layers applied to the top liner optimize the surface for offset lithography, flexography and foil stamping. Bulking treatments and mechanical refining strategies compensate for the degraded stiffness and lower tear strength inherent to repeatedly recycled cellulose fibers.
Multi Layer Sheet Architecture
Papermakers build this multi-ply board on specialized multi-forming machines that combine different recycled furnish streams across individual forming wires. The bleached top liner utilizes sorted white ledger paper or virgin bleached chemical pulp to achieve an ISO brightness typically ranging between eighty and eighty-five percent. Beneath the white face lies an underliner ply designed to mask the dark, mottled appearance of the structural core.
The bulky center plies, making up the bulk of sheet grammage, utilize unbleached mixed recovered papers, old corrugated containers and mechanical fiber fragments. A thin back liner, often tinted grey or buff, forms the interior surface of the folded carton. Starch spraying between plies reinforces internal bond strength, preventing delamination during high-speed scoring, creasing and automated carton erection.
Converting Performance Boundaries
Moisture variations across the recycled plies make this board grade sensitive to ambient humidity swings, causing hygroscopic curl and box distortion on filling lines. Trace contaminants from recycled feedstock, such as mineral oil hydrocarbons from offset printing inks, necessitate functional internal barrier coatings or distinct barrier bag liners when packaging sensitive food products. Creasing demands precise die setup, as over-creasing fractures the brittle recycled core plies while under-creasing leads to misaligned carton flaps.
Squeezing maximum bending stiffness from shorter recycled fibers requires board mills to maintain sheet thickness, meaning recycled grades require higher basis weights than virgin fiber boards to achieve equivalent stacking performance.
