LG Chem HDPE ME5000 is a high-density polyethylene injection-molding resin within the LUTENE-H series. The grade is positioned by a nominal melt flow index of 5.0 g/10 min under 190°C/2.16 kg loading according to ISO 1133-1:2022 and a nominal density of 0.954 g/cm³ according to ISO 1183-1:2019. The product is supplied in pellet form for rigid injection-molded articles requiring a controlled balance between melt flow, stiffness, impact resistance, and environmental stress-crack resistance. Typical applications include industrial pails, crates, tote boxes, caps, closures, and general technical moldings with wall thickness generally in the range of 1.5 mm to 4.0 mm. The values presented below are representative datasheet values and are not specification limits; lot-specific values are controlled by the manufacturer certificate of analysis.

LG Chem HDPE ME5000 Grade Classification and Nominal Property Set

Mechanical data for injection-molded HDPE are dependent on specimen preparation, mold temperature, shear history, and conditioning time. Tensile yield and flexural modulus values should be compared only among specimens produced under identical conditions and tested according to the same standard. The elongation at break value above 500% indicates ductile failure under the stated tensile conditions, but it does not predict part-level impact performance in the presence of weld lines, sharp corners, or molded-in stress.

What Processing Boundaries Govern Injection Molding of ME5000?

The melt temperature range for general injection molding is 200°C to 240°C, with the preferred operating band between 210°C and 230°C. Barrel temperature profiles should be arranged with the rear zone from 180°C to 200°C, the central zone from 200°C to 220°C, and the front zone and nozzle from 210°C to 230°C. Melt temperatures above 280°C should be avoided because the stabilizer package is not intended for prolonged exposure at elevated temperatures, and oxidative degradation can generate discoloration, viscosity shifts, and surface defects. The recommended hot-runner manifold temperature, where applicable, is 220°C to 240°C; hot-runner systems with dead spots should be assessed for resin hold-up because stagnant HDPE melt can degrade rapidly at the upper end of the processing window.

Mold surface temperature is normally set between 20°C and 40°C. At the lower boundary, cycle time is shortened and ejection may be improved for stiff geometries, but surface gloss decreases and flow marks can appear in thin-wall sections. At 40°C, surface replication improves and internal stress is reduced, but cooling time increases for wall thickness above 3.0 mm. Mold temperature non-uniformity should be controlled to less than 10°C across the cavity because differential shrinkage in an HDPE with 0.954 g/cm³ density and a crystallization temperature near 117°C to 122°C can generate bowing in rectangular crates and dimensional variation exceeding the 0.5% post-molding tolerance band commonly used for industrial containers.

Injection velocity should be set to achieve a cavity filling time of 1.0 s to 2.5 s for wall thickness between 2.0 mm and 3.0 mm. Peak injection pressures are commonly observed between 70 MPa and 100 MPa on machines with screw diameters from 35 mm to 60 mm. Hold pressure is normally 50% to 80% of peak injection pressure and must be maintained until gate freeze. If hold pressure is released before gate freeze, the gate acts as a pressure relief path and sink marks form at thick bosses or rib intersections. Gate freeze time for sprue-gated parts with a gate diameter of 2.5 mm to 3.5 mm should be determined by pressure-drop monitoring or acoustic methods rather than by a fixed timer, because the actual freeze time varies with melt temperature and mold temperature.

LG Chem HDPE ME5000 does not require drying at ambient conditions because its water absorption is near 0.01% under ISO 62:2008. However, pellets stored in cold warehouses can carry surface condensation when loaded directly into a room-temperature hopper. In that condition, pre-drying at 70°C for 1 h to 2 h in a desiccant or hot-air dryer is sufficient to suppress surface splay. Drying must not exceed 90°C or 4 h because prolonged heating can sinter pellets and bridge the hopper throat on single-screw machines.

Purging after processing can be conducted with a polyolefin purge compound or a lower-flow HDPE. Purge temperatures should not exceed 240°C. If barrel shutdown exceeds 15 min, the barrel temperature should be reduced to 160°C to 180°C to limit thermal degradation in the residual melt pool. Start-up after an extended shutdown should include a fresh polyethylene purge before the production material is reintroduced.

In injection-molded industrial pails with a nominal capacity of 20 L, LG Chem HDPE ME5000 is used for body and handle geometries where wall thickness is typically 2.0 mm to 2.8 mm and where drop impact after filling must be maintained at low ambient temperatures for regulated packaging. The combination of 5.0 g/10 min melt flow and 0.954 g/cm³ density permits complete cavity filling in multi-cavity tools without raising the melt temperature to the point where odour or degradation risk becomes significant. Gate design for pail bodies is typically a centrally located sprue or hot-tip gate with a retained gate diameter of 3.0 mm or larger; smaller gates restrict flow and increase shear heating, which can locally lower viscosity and create visible flow lines at the gate.

Crates and tote boxes with grid-rib construction require attention to sink marks at rib intersections. For free-standing ribs with a base radius of 0.6 mm to 0.8 mm, rib thickness should be limited to 0.55 to 0.65 times the adjacent wall thickness to avoid visible sink opposite the rib. With ME5000, a rib-to-wall ratio of 0.60 maintains ejection force within the limits of standard ejector pins and reduces the risk of excessive top-load deformation. Higher-flow HDPE grades may fill rib intersections more easily, but they can reduce environmental stress-crack resistance and top-load creep in service environments exposed to dairy, meat, or citrus processing fluids.

Closures and caps produced from ME5000 are typically limited to industrial threaded closures rather than thin-wall beverage closures. The melt flow index of 5.0 g/10 min is lower than the 18 g/10 min or higher flow grades normally required for high-speed beverage caps with wall thickness below 1.0 mm. For industrial threaded closures with wall thickness of 2.0 mm to 3.5 mm, the grade provides adequate thread formation and low creep under torque. The recommended core temperature in closure molds is 30°C to 40°C; core temperatures below 20°C can generate high ejection forces and stress whitening in internal threads.

When ME5000 Replaces ME4000 or ME8000 in Multi-Cavity Tools

The primary distinction between LG Chem HDPE ME5000 and the adjacent LUTENE-H grades is controlled by melt flow. ME4000 at 4.0 g/10 min is selected where higher molecular weight contributes to greater impact strength and environmental stress-crack resistance at the cost of higher injection pressure. ME8000 at 8.0 g/10 min is selected for shorter cycle times and reduced clamp force, but with lower environmental stress-crack resistance and a higher tendency to stress whitening under impact. ME5000 occupies an intermediate position in this range. Because the melt flow index increases from 5.0 g/10 min to 8.0 g/10 min when substituting ME8000, the apparent shear viscosity at 220°C is reduced; however, the standard datasheet does not provide a capillary viscosity curve, so the exact pressure reduction on a given tool must be measured directly.

For ESCR-sensitive packaging, the lower-flow grades including ME4000 and ME5000 are generally preferred over ME8000 and ME9180 because higher molar mass fractions increase the time to craze initiation in the presence of surfactant solutions. Comparative testing under ASTM D1693-15 Method B in 10% Igepal CO-630 at 50°C is used to establish differences, but the values are geometry-dependent and cannot be transferred from one wall thickness to another. When converting an existing ME8000 tool to ME5000, the melt temperature should be increased by 5°C to 10°C to compensate for the higher viscosity, and hold pressure should be increased by 5% to 15% to maintain packing. These adjustments should be validated with short-shot studies and gate freeze measurements on the production tool.

Published data for weld-line strength, tensile creep modulus, and coefficient of friction of this exact grade in specific application geometries is limited. Material qualification should therefore include weld-line Izod impact and drop-impact tests on the production tool. The results from standard laboratory Izod specimens do not sufficiently represent the impact response of molded parts with weld lines, ribs, and gate orientation effects.

In extrusion and blow-molding operations, LG Chem HDPE ME5000 is not the preferred grade. The melt flow index of 5.0 g/10 min can produce inadequate melt strength, parison sag, and wall thickness variability in blow molding. For extrusion blow molding, grades with lower melt flow and specific molecular architecture should be selected instead. In injection molding, mechanical recycling of ME5000 regrind can be incorporated into operations at levels up to 30% by weight with virgin resin, but this must be treated as a tool-specific practice. Regrind from dark industrial crates may shift density slightly and lower notched impact if contamination from mineral fillers or other polymers is present.

Regulatory and handling boundaries are summarized in the following matrix. Compliance for food-contact applications is not established by the resin supply alone; the final article must be tested under the intended food-contact conditions.

Processors should verify all regulatory statements against the current manufacturer product safety data sheet and certificate of analysis, because resin formulations and additive packages may be adjusted while the grade designation remains unchanged. The operational limits stated here are based on published material data and standard injection-molding practice for HDPE of this melt flow and density class; however, published data for this specific configuration is limited for certain specialized applications, and production trials remain the definitive qualification method.