THERMOFORMABLE PAPERBOARD-BASED LAMINATE AND A METHOD FOR MANUFACTURING SAID LAMINATE

Patentradars sammanfattning

Stora Enso's invention provides a thermoformable, compostable paperboard-based laminate comprising 50–99 wt% kraft fibers and 1–50 wt% recycled fibers (e.g., from used beverage cartons/food service board) that have been treated to remove fines and refined to a Schopper-Riegler value of 14–30. At least one barrier layer of semicrystalline polyhydroxyalkanoate (PHA) with strain-at-break ≥5% is applied to the paperboard, yielding a laminate with ≥3% MD and ≥5% CD stretchability suitable for deep-draw thermoforming. The key novelty lies in the specific recycled-fiber preparation route—washing and/or fractionation to deplete fines, followed by controlled refining—which unexpectedly preserves or improves stretchability and strength despite incorporating challenging FSB/UBC-derived fibers.

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