In high-cavitation thin-wall dairy container production, LyondellBasell HDPE L5800I is used as a high-flow injection molding resin where short fill times and controlled residual stress are critical. The melt mass-flow rate of 58 g/10 min at 190°C under 2.16 kg load, determined to ISO 1133-1:2022, allows filling of sidewall sections as thin as 0.45 mm in tools with up to 24 cavities without exceeding a peak injection pressure of 900 bar. Melt temperature is maintained between 210°C and 240°C; mold temperature is held at 10°C to 20°C to accelerate solidification and reduce cycle time. Fill times between 0.25 s and 0.35 s are common on 250-ton hydraulic clamp machines, but screw recovery must be evaluated because the low melt viscosity can allow pellet bypass at screw speeds above 120 min⁻¹. A back pressure of 5 to 12 bar is applied to stabilize shot size. White pigmentation is obtained with a titanium dioxide masterbatch letdown of 2 wt% to 4 wt%; dispersion is checked by pressure rise across the breaker plate. The finished dairy cups and margarine tubs are evaluated for overall migration under EU Regulation (EU) No 10/2011 at 10 mg/dm² and for food-contact suitability under 21 CFR 177.1520.

What Limits High-Speed Injection of L5800I in Multi-Cavity Overcap Tooling?

Stack molds with 32 to 64 cavities shift the overcap production bottleneck from melt filling to gate seal and part ejection. L5800I is specified for non-carbonated beverage and dry food overcaps with skirt wall thickness between 0.6 mm and 0.8 mm. The nominal density of 0.958 g/cm³, measured to ISO 1183-1:2019, provides adequate cap stiffness for removal without excessive brittle failure. Valve-gated hot runners are preferred because the low melt viscosity produces drool and stringing with open nozzles; nozzle shut-off pressure is maintained above 80 bar to prevent leakage during screw recovery. Fill times of 0.2 s to 0.3 s are typical. The principal constraint is environmental stress-crack resistance. Under ASTM D1693 in 100% Igepal CO-630, L5800I exhibits lower ESCR than low-MFR closure grades. The material is therefore restricted to caps for water, diluted beverages, and dry powder applications; designs for surfactant-containing liquids, dishwasher detergents, or carbonated beverage closures require substitution with a higher molecular weight grade or validation under the specific pack condition. Cap inner diameter control within ±0.05 mm is attainable only when mold cooling is uniform and ambient humidity is controlled below 70% RH.

Thin-wall storage crates and housewares are molded from L5800I under cold-warehouse distribution conditions with sidewall thicknesses of 1.5 mm to 2.0 mm. Rear barrel zones are set between 190°C and 210°C, the center zone between 210°C and 230°C, and the nozzle at 230°C to 245°C to prevent melt starvation at high screw recovery rates. Clamp force is calculated at 4 to 5 kN/cm² of projected part area. Because L5800I exhibits high flow, sink marks over ribs are a critical defect: the rib-to-wall thickness ratio is kept below 0.6:1, and gate placement avoids heavy section-to-thin section transitions. A blend of 5 to 10 wt% LLDPE is introduced at the feed throat to raise low-temperature impact resistance, but the blend raises melt viscosity and requires a melt-temperature increase of 10°C to 15°C. Notched Charpy impact under ISO 179-1/1eA at -20°C is substantially lower than at 23°C; published data for this specific configuration is limited.

When a 70/30 Regrind Blend of L5800I Is Molded into Double-Wall Cosmetic Jars

Double-wall cosmetic jars with outer wall thickness of 1.2 mm to 1.6 mm permit regrind ratios up to 30% by mass only after granulate is passed through a 2.0 mm screen and dried to surface moisture below 0.05%. The high MFR of L5800I masks minor viscosity increase from molecular weight degradation, but a regrind-containing melt is still checked by melt mass-flow measurement under ISO 1133-1:2022; experience shows an increase of less than 1.5 g/10 min at 30% regrind. Titanium dioxide masterbatch at 2.5 wt% letdown is added at the throat. Dispersion is monitored via pressure differential across a 23 cm² breaker plate, with a maximum permitted rise of 35 bar before screen pack replacement. Melt temperature is held at 215°C to 235°C; mold temperature is kept below 25°C to preserve surface gloss. The finished jars are intended for non-food cosmetic creams; packaging safety is verified under Regulation (EC) No 1223/2009 Article 17, with overall migration tested to EU Regulation (EU) No 10/2011 as a conservative surrogate.

Non-hazardous industrial pails of 5 to 20 L capacity are molded from L5800I when cycle time must not exceed 9 s at a nominal sidewall thickness of 1.6 mm to 1.9 mm. Deep-draw pail tooling requires vent depths of 0.02 mm to 0.03 mm and cold-slug wells sized to handle the fast melt front without jetting. Packing pressure is set between 55 MPa and 70 MPa; holding time is truncated at 4 s to 6 s because gate freeze occurs rapidly. The high flow is beneficial for filling the handle attachment region without weld-line fracture, but L5800I alone is generally not sufficient for UN-certified dangerous goods packaging. Drop-impact and top-load requirements for filled pails at -18°C are stringent; impact modification or wall thickening is often required, and published data for this specific configuration is limited. Heavy metal migration in packaging is controlled under Directive 94/62/EC with a combined Pb, Cd, Hg, Cr(VI) limit of 100 mg/kg.

Tamper-evident overcaps for pharmaceutical and nutraceutical containers are molded with L5800I only in desiccant-free, single-use designs. The grade's high MFR permits filling of thin flexible spring legs in child-resistant closures; however, the resin is not suitable for long-term contact with aqueous parenteral or ophthalmic products. Polyethylene monograph testing under Ph. Eur. 3.2.2 and USP 661.1 is required for primary packaging components; supplier documentation should be checked for peroxide and catalyst residues. Melt temperature is kept below 240°C to minimize organoleptic transfer. Since the material is a high-flow injection grade, closure designs should avoid sharp internal corners because notch sensitivity reduces drop performance at refrigeration temperatures of 2°C to 8°C.