Patent attributes
A multilayer blown film with improved strength or toughness comprising a layer comprising a metallocene polyethylene (mPE) having a high melt index ratio (MIR), a layer comprising an mPE having a low MIR, and a layer comprising a HDPE, and/or LDPE. Other embodiments have skin layers and a plurality of sublayers. At least one sublayer includes an mPE, and at least one additional sublayer includes HDPE and/or LDPE. The mPE has a density from about 0.910 to about 0.945 g/cm3, MI from about 0.1 to about 15, and melt index ratio (MIR) from about 15 to 25 (low-MIR mPE) and/or from greater than 25 to about 80 (high-MIR mPE). A process is related to supplying respective melt streams for coextrusion at a multilayer die to form a blown film having the inner and outer skin layers and a plurality of sublayers, wherein the skin layers and at least one of the sublayers comprise mPE and at least one of the sublayers comprise HDPE, LDPE or both. Draw-down, blow-up ratios and freeze-line distance from the die are controlled to facilitate a high production rate.
