Mineral Reinforcement of HMW-HDPE Film, 1998 Polymers, Laminations & Coatings Conference Proceedings

LLDPE-based pelleted concentrates were used to add 0, 10, & 2Owt.% fine-ground surface-treated calcium carbonate (CaCO,) mineral to three different high-molecular weight HDPE film resins. These dry blends were extruded into film on a 65mm grooved-feed extruder fitted with a 1OOmm die and 1.2mm die gap. Stalk height, blow-up ratio (BUR), and extruder screw RPM also were varied to determine how the addition of CaC03 affected film property response to variation in these process conditions.

Mineral addition yielded output rate increases of 8% at 10% CaCQ and 17% at 20% CaCQ while simultaneously decreasing melt pressure and motor load (current). Certain combinations of base resin processing conditions, and mineral loading yielded increases in dart impact strength without a loss in tensile yield stiffness. Other advantages of CaCQ reinforcement of HMW-HDPE lihns included an increase in film coefficient of friction with CaCO, addition, which improves stacking of liner or merchandise bags.