LyondellBasell HDPE M6062 is a high-density ethylene-based injection molding resin supplied as free-flowing pellets. The grade is specified for rigid packaging and industrial containers, including open-top pails, crates, caps, and thin-wall housewares, where the selection criterion is a balance of medium melt flow, stiffness, and cold-temperature impact resistance. In commercial operations, M6062 is processed on conventional reciprocating-screw injection molding machines with cold-runner or hot-runner molds. Because the product is intended for injection molding, it should not be substituted into extrusion blow molding or blown film lines without process revalidation. The values reported in this document are representative data from the manufacturer’s published literature and are not lot-specific certificates of analysis.

Specifications, Test Methods, and Lot-to-Lot Verification

The following representative values define M6062 within the supplier’s injection molding product envelope. Mechanical and regulatory compliance should be verified against the specific lot certificate of analysis and the current technical data sheet.

Because M6062 is an injection molding grade, the supplier data sheet may not include long-term environmental stress crack resistance under ASTM D1693-21 or high-load melt index under ISO 1133-1 at 5.0 kg or 21.6 kg. Published data for this specific configuration is limited; therefore, end-use qualification for aggressive liquid packaging or continuous exposure to stress-cracking agents should be performed on actual molded parts. Melt flow rate ratio values are also not to be inferred from the standard 2.16 kg condition alone.

When the Grade Is Run on Reciprocating Screw Injection Molding Lines

Processing is typically conducted at melt temperatures between 210 °C and 260 °C. Lower melt temperatures below 200 °C can increase screw torque, reduce melt homogeneity, and produce visible flow lines in thick bosses or hinge areas. Barrel temperatures above 280 °C accelerate oxidative chain scission, and the resulting molecular weight loss is commonly observed on the production floor as reduced notched Izod impact and increased gate blush. Mold temperature is kept between 10 °C and 40 °C for general-purpose parts; a mold temperature above 40 °C is used only where high gloss, improved weld-line strength, or reduced frozen-in stress is required, and it increases cooling time.

Reciprocating screws with a general-purpose polyolefin profile and an L/D ratio of 20:1 to 24:1 are adequate. A compression ratio of 2.2:1 to 2.8:1 and a sliding-ring non-return valve are standard on production lines to maintain shot-to-shot weight consistency below ±0.5%. Back pressure is typically held between 5 bar and 15 bar hydraulic to avoid over-shear. Recovery speed should be set so that screw recovery completes before the cooling timer expires; otherwise, the next shot is delayed and melt residence time increases. For thin-wall containers with wall stock below 1.0 mm, filling velocities are increased to the machine’s maximum safe rate, with fill times typically below 1.0 s; however, cavity venting must be sufficient to avoid diesel-effect burn marks at the end of flow.

Hot-runner manifolds and nozzle tips are set no higher than 260 °C to minimize resin degradation in the gate region. Cold-runner tools with sprue diameters of 4.0 mm to 6.0 mm reduce pressure loss. Gate freeze must occur before screw recovery and before holding pressure is released; otherwise, molten resin can flow back from the cavity, causing sink marks and variable packing density. A sealing purge with low-MFR HDPE or a commercial polyolefin purge compound is recommended before shutdown. Simultaneous processing with chlorinated polymers such as PVC or PVDC is avoided because thermal decomposition products can corrode tooling and accelerate HDPE degradation.

Melt temperature profiling is not uniform. A flat barrel profile from 200 °C at the feed throat to 250 °C at the nozzle is acceptable; a reverse profile with the rear zone above 250 °C can cause bridging in the feed throat. The nozzle should be held in the middle of the melt range to avoid cold slug. Hot-runner systems with externally heated manifolds should maintain thermal uniformity of ±5 °C across nozzle tips; otherwise, unbalanced filling occurs in high-cavitation tools. On a 16-cavity hot-runner closure line, a worn check ring permits melt backflow during injection, reducing shot density and increasing fill time. When fill time shifts by more than 0.1 s in a thin-wall tool, cavity pressure at gate freeze can fall below 300 bar, causing variable part weight.

Part ejection can be limited by HDPE’s low surface energy. Draft angles of 1° to 3° are typical for rigid sidewalls, and textured surfaces require an additional 1° to 2° of draft per 0.025 mm of texture depth. Mold release is generally not required for HDPE if ejection temperatures are below 70 °C. If release is marginal, an external mold release is used at low amounts; excessive release agent can contaminate food-contact surfaces and interfere with post-mold printing or adhesion.

Colorants and additive masterbatches affect melt behavior in proportion to their carrier resin and loading. A 3 wt% color masterbatch can shift the effective melt flow rate by several tenths of a g/10 min; therefore, the quoted MFR of natural M6062 is not the final compound property. Dispersion quality should be checked by film inspection or by melt filter pressure rise in an extruder, but for injection molding the practical controls are part surface appearance and mechanical consistency.

In pails, crates, and open-top logistics containers, M6062 is used where stacking stiffness and cold-temperature drop resistance are required. Notched Izod impact at 23 °C does not predict performance at -20 °C; therefore, molded containers should be tested under ASTM D5276-19 or an equivalent loaded-container drop protocol. For thin-wall packaging, part warpage is controlled less by resin choice than by gate placement, mold temperature uniformity, and packing pressure profile. Differential shrinkage between flow direction and transverse direction produces edge lift in flat lids; molds with center gating or balanced multi-gating reduce this. Post-mold shrinkage can occur for 48 h after demolding and is typically an additional 0.005 mm/mm; stacking dimensions should be verified no earlier than 24–48 h after molding.

Short shots in multi-cavity tools are typically corrected first by increasing melt temperature within the 210–260 °C window, then by raising injection velocity, rather than by increasing back pressure. Cavity imbalance above 10% between first-filled and last-filled cavities in a 16-cavity cold-runner stack mold is often due to runner shear heating, not resin lot variation. M6062’s narrow molecular weight distribution lowers shear thinning compared with broad-MWD grades; therefore, tooling designed for broad-MWD HDPE may require larger gates or runner diameters. Warpage in flat lids is driven by differential shrinkage; the flow-direction shrinkage is lower than the transverse-direction shrinkage. A mold temperature difference of 10 °C across the cavity halves is enough to produce visible sidewall bowing in a 1.5 m long crate. Cooling-circuit flow should be balanced to keep cavity surface temperature within ±3 °C.

At -20 °C, HDPE impact performance depends on molecular weight, comonomer type, and cooling rate. M6062 retains ductile behavior in many pail applications, but published data for notched Izod at -30 °C is limited. Molded parts should be conditioned according to ASTM D618-22 for at least 40 h at 23 °C and 50% relative humidity before mechanical testing. For cold-chain containers, drop testing at -20 °C after 48 h of conditioning is recommended; brittle splits at the gate or weld line are the primary failure mode on production lines.

What Distinguishes M6062 from Other HDPE Process Families?

M6062 occupies the medium-flow injection molding envelope. Its melt mass-flow rate is substantially higher than fractional melt blow molding or pipe grades and lower than very high-flow thin-wall injection grades. The molecular weight distribution is narrow enough to reduce melt elasticity and shorten packing decays, but it does not provide the high melt strength required for continuous parison extrusion or large-part blow molding.

The major technical distinction is not merely melt flow rate but molecular weight distribution. Blow molding grades with a broad or bimodal distribution exhibit high melt strength and parison sag resistance; M6062 does not. High-flow injection grades with MFR above 30 g/10 min fill thinner walls at lower pressure but sacrifice notched Izod impact and environmental stress crack resistance. M6062 therefore occupies the intermediate zone where cycle time, drop resistance, and top-load stiffness are co-optimized for reusable industrial containers. Differences among injection grades within the same supplier family are often encoded in the final digits; M6062 should not be assumed interchangeable with adjacent grades unless the lot certificate and processing window are compared. Published direct mechanical comparison data among those grades is limited, so substitution should be validated through mold-fill studies and mechanical testing of actual parts.

Food-contact use is subject to the olefin polymer provisions of FDA 21 CFR 177.1520 and, for the European Union, Regulation (EU) No 10/2011, including overall migration and specific migration limits when the final article is tested under the intended food type, time, and temperature. The base resin can be manufactured under current good manufacturing practices, but the grade is not automatically certified for direct food contact; the converter must obtain the supplier’s regulatory status letter and validate the finished article. Regulatory compliance is not a property of the pellet alone. It is a property of the complete article, including pigments, additives, and processing aids. For European food-contact articles, overall migration testing is conducted under the food simulants assigned by Regulation (EU) No 10/2011; for fatty foods, olive oil or 95% ethanol simulants may be required.

Storage is conducted below 50 °C, away from direct sunlight and strong oxidizing agents. Drying is normally unnecessary because HDPE is not hygroscopic; however, if surface condensation is present after outdoor storage, a desiccant dryer at 80 °C for 2 h or a hopper dryer at 80 °C for 1–2 h removes surface moisture. The material is not recommended for continuous exposure to strong oxidizing acids, aromatic hydrocarbons, or chlorinated solvents at elevated temperatures. Continuous contact with surfactants can accelerate environmental stress cracking, particularly at molded-in stress concentrations such as weld lines, gate vestiges, and sharp corners. Stress cracking is a time-dependent failure mode; a part that survives a 24 h room-temperature contact test may still fail after 30 days. Therefore, for liquid packaging that contains wetting agents, the converter should validate on commercial tooling rather than on a compression-molded plaque. For outdoor service, carbon black at 2.0 wt% to 2.5 wt% is a common UV stabilizer for industrial crates; the base M6062 grade is typically natural, and weatherable black versions require a specified masterbatch.