PLA/PBAT Pencil Lead Casing with Oyster Shell Fillers

The patent applies composite materials by combining PLA with PBAT and mineral fillers (oyster shells, shellfish shells, or ground glass) to create a lead casing material that achieves both biorenewable substitution and sufficient mechanical properties. The specific formulation uses 5-50% mineral filler, 20-80% PLA, and 5-50% PBAT, where the mineral filler provides structural reinforcement while PLA and PBAT provide flexibility and biodegradability, resolving the contradiction between reliability and adaptability.

The patent applies parameter changes by systematically varying the proportions of PLA, PBAT, and mineral filler to optimize the balance between impact resistance and composition complexity. The patent specifies that PLA content should be 20-80% and PBAT content should be 5-50%, with mineral filler at 5-50%, allowing adjustment of mechanical properties while controlling processing behavior and material complexity within defined ranges.

The patent applies local quality by specifying that mineral fillers should be finely ground to a particle size of 0.1-2 mm and uniformly distributed throughout the polymer matrix. This local optimization of filler characteristics ensures that the fillers enhance flexural resistance through their distributed reinforcement effect while maintaining extrusion quality by preventing aggregation and ensuring homogeneous material flow during manufacturing.