The resin designated LG Chem LUCENE mLLDPE HP2018BI is a metallocene-catalyzed ethylene-alpha-olefin copolymer supplied in pellet form for blown-film extrusion. The polymer occupies the 0.918 g/cm³ density class and has a nominal melt flow rate of 2.0 g/10 min, measured at 190 °C under a 2.16 kg dead weight in accordance with ISO 1133-1:2022. The single-site catalyst architecture narrows the molecular weight distribution and produces a more uniform comonomer placement than conventional Ziegler-Natta linear low-density polyethylene of equivalent density. The grade is typically supplied with a balanced slip and antiblock package, although the specific additive loading should be confirmed against the lot-specific certificate of analysis because the producer uses the suffix BI for internal additive and lot-control identification.

What typical property profile is reported for HP2018BI under standard film test protocols?

The following values are extracted from producer technical literature and represent typical values, not contractual specification limits. They were obtained on 50 µm monolayer blown film produced at a blow-up ratio of 2.5:1 and a melt temperature near 200 °C.

Because the melt flow rate is a dead-weight extrusion value and not an intrinsic viscosity, it should be correlated with shear rheology only through capillary or rotational rheometry. The density value establishes the packaging film class, while the melting endotherm under ISO 11357-3:2018 at 10 °C/min shows a principal peak at 121 °C and a secondary shoulder associated with the comonomer distribution. The Vicat softening temperature is obtained with a 10 N load at a 50 °C/h heating rate under ISO 306:2022 Method A50.

Blown-film conversion of HP2018BI is carried out on single-screw extruders with grooved feed bushings or smooth-bore barrels and barrier screws. Recommended screw L/D ratios fall between 24:1 and 30:1 because the resin exhibits a shear-thinning response that is less pronounced than that of high-pressure low-density polyethylene. On a 55 mm smooth-bore extruder with an L/D ratio of 30:1 and a 120 mm spiral mandrel die set to a 2.0 mm die gap, melt temperatures from 195 °C to 205 °C maintain bubble stability at blow-up ratios between 2.2:1 and 2.8:1. The frost line is commonly held at 7 to 10 die diameters above the air ring. Frost line positions below that range increase bubble flutter, while higher positions raise haze by slowing surface quenching. Adapter and die pressures for this configuration typically fall between 350 bar and 420 bar; converters using 45 mm grooved-feed extruders operate at the upper end of that range because the barrier section generates additional viscous dissipation. The resin should be purged from the barrel before shutdown with a lower-MFR LDPE to prevent start-up torque overload in grooved feed sections.

A narrower comonomer distribution and lower seal-initiation threshold than conventional Ziegler-Natta LLDPE

The structural distinction between HP2018BI and conventional linear low-density polyethylene originates in the catalyst system. Single-site metallocene catalysis distributes the alpha-olefin comonomer more evenly across the chain-length distribution, lowering the low-molecular-weight fraction that in Ziegler-Natta butene-based LLDPE contributes to extractables and limits low-temperature sealing performance. In film evaluations using 50 µm monolayer blown film, the reported dart impact of 850 g under ISO 7765-1:2004 Method A is higher than typical published values for butene-based Ziegler-Natta LLDPE of equivalent 0.918 g/cm³ density, which frequently fall below 500 g in the same geometry. The improvement is attributed to higher tie-molecule concentration and the absence of a highly crystalline high-density homopolymer fraction.

The heat seal initiation threshold is also lower. The grade is reported to reach a seal strength of 4.0 N/15 mm at approximately 105 °C under a dwell time of 0.5 s and seal bar pressure of 0.3 MPa when evaluated according to ASTM F2029. Comparable conventional LLDPE films may require temperatures 10 °C to 15 °C higher to reach the same seal strength. Published data for commercial hot-tack equipment using this specific grade are limited, and the seal temperature window should be validated on the target packaging line because seal-bar geometry, film gauge, and dwell time shift the threshold.

Applications in which HP2018BI is converted include frozen food bags, high-clarity bread bags, heavy-duty sacks, and lamination films where a lower seal-initiation temperature protects heat-sensitive contents. Drop-impact retention on heavy-duty sacks is evaluated by inclined-plane impact or shaker protocols, and cold-temperature flexibility is commonly assessed after freezer conditioning at −30 °C followed by a dart impact test. The producer’s food-contact statement references FDA 21 CFR 177.1520(c) for olefin polymers, subject to migration limits and end-use restrictions, and European Commission Regulation (EU) No 10/2011 for plastic materials intended for food contact. The grade is listed in the manufacturer’s REACH compliance documentation; converters remain responsible for overall packaging compliance because process additives and lamination adhesives fall outside the base resin statement.

When surface condensation or stall-rate purging requires intervention before film conversion, the following boundaries apply. Polyethylene does not absorb bulk water, but surface condensation on pellets stored in humid warehousing can generate contact-clarity defects in thin film. If opened sacks are exposed to relative humidity above 60 % for more than 48 h, the resin should be passed through a dehumidified hopper at 70 °C for 2 h to remove surface moisture. The grade is not recommended for deep-draw thermoforming requiring high melt strength because the 2.0 g/10 min melt flow rate and narrow molecular weight distribution provide less extensional hardening than low-MFR LDPE or high-pressure autoclave grades. Additive packages containing high levels of amines should be evaluated before compounding because such systems can shift slip-agent bloom kinetics and alter the coefficient of friction; published data on this specific formulation are limited. Blending with high-pressure LDPE at 10 % to 20 % addition improves bubble stability and output but increases haze and lowers dart impact, and seal initiation must be revalidated for each blend ratio.

The grade differs from lower-density LUCENE film resins because the 0.918 g/cm³ density balances stiffness and toughness for heavy-duty and freezer packaging, whereas lower-density grades prioritise toughness and sealing at the expense of modulus. Compared with higher-flow cast-film or extrusion-coating grades, HP2018BI remains in the blown-film melt-flow window where bubble stability and output on grooved-feed extruders are maintained without excessive melt-temperature fluctuation. It is not positioned as a primary injection-moulding resin because the narrow molecular weight distribution reduces melt strength and can produce flow hesitation in thick sections. Converters transferring existing Ziegler-Natta LLDPE formulations should not assume identical screw speed and air-ring settings; the lower extruder back-pressure response of the metallocene grade may require adjustment of die gap, frost line height, or air-ring aperture to maintain the same bubble cooling rate.

Processing boundary conditions on grooved-feed and smooth-bore blown-film extruders

Stable bubble geometry is achieved only when the melt temperature is controlled within the 180 °C to 210 °C window. Below 175 °C melt pressure rises above 450 bar on a 65 mm grooved-feed extruder with an L/D ratio of 30:1, while above 215 °C bubble instability and surface oxidation risk increase. Screen packs with 80 mesh or finer filtration are standard on films below 40 µm because gel particles from thermal degradation or additive agglomeration become visible in high-clarity packaging. The residence time in the die should not exceed 10 min at 200 °C; longer residence times promote crosslinking and gel formation. For start-up, a low-MFR LDPE purge is used to stabilise the pressure profile before the metallocene resin is introduced. For unsupported film below 30 µm, the die gap is commonly reduced to 1.6 mm to 1.8 mm and the blow-up ratio is increased to 2.8:1 to 3.0:1, but the exact settings depend on the spiral mandrel geometry and air-ring type.

The compliance position of the base resin is summarised in the following table. Converters must verify that downstream additives, printing inks, and adhesives do not invalidate the regulatory status of the final package.

The operational limits of HP2018BI in multi-layer coextrusion are not fully described by monolayer film data. When the grade is placed in the skin layer of a three-layer structure, the processing window is wider because the core layer carries the melt strength and bubble stability. When it is placed in the core layer at high layer ratios above 60 %, the bubble can become less stable at frost line heights below 7 die diameters. Published data for this specific three-layer configuration are limited, and converter trials using the target die geometry remain the controlling data source.