Mitsui Chemicals HDPE 6900 enters extrusion blow moulding lines for UN-certified large-volume industrial containers as a high-ESCR feedstock for aggressive liquid chemical packaging. Incoming melt flow rate is measured under ISO 1133-1:2022 at 190 °C / 21.6 kg and compared against the supplier certificate of analysis; deviation outside the agreed release band triggers segregation. The grade is processed in reciprocating screw or accumulator machines with screw L/D between 24 and 30 and compression ratio 3.0–4.0:1. Barrel zones are maintained at 180–220 °C, die head temperature at 190–210 °C, and mould surface temperature at 10–25 °C. Parison programming employs 20–40 wall-thickness points to prevent corner thinning below 1.8 mm in 20–30 L jerrycan shoulders. Blow pressure is set at 0.6–1.0 MPa, clamp force is 80–300 kN for 15–30 L formats, and cycle time is 45–90 s. Regrind addition is limited to 20–30 wt% with grinding fines below 1 wt% to reduce die-bushing gel deposition; carbon black masterbatch for outdoor storage is added at 2.0–3.0 wt%, while non-UV colourant masterbatch is used at 0.5–2.0 wt%. Compliance standards for this route are UN Model Regulations Chapter 6.1, ADR/RID Chapter 6.1, ISO 16101:2004, and for dual-use food-contact packaging, 21 CFR 177.1520(c). Terminal products include UN 3H1/3H2 polyethylene jerricans of 10–30 L, UN 1H1/1H2 drums of 120–220 L, and IBC inner bottles of 500–1000 L.

Operational boundary: the accumulator head dead spots must be inspected at shutdown intervals not exceeding 72 h because gel accumulation in the helical channel can generate black specks in the parison. Do not exceed melt temperature 230 °C for residence times above 5 min; oxidative gel formation accelerates in that zone and can produce inconsistent parison length control.

What Changes When Blow Moulding Thin-Walled Agrochemical Bottles With 6900?

When the monolayer bottle format is reduced below 1.0 mm nominal wall, the same melt strength becomes a processing constraint, and parison pre-cooling is introduced before the mould closes. On continuous shuttle blow moulding machines with 1–2 parison heads, parison programming is set to 8–20 points and die ovalization is adjusted to 0.2–0.8 mm. Pre-cooling air is supplied at 0.05–0.15 MPa, and final blow pressure is 0.5–0.9 MPa. Clamp force ranges from 150–400 kN for 500 mL–5 L bottles. UV stabilizer masterbatch is dosed at 0.3–0.6 wt%, colourant at 0.5–1.5 wt%, and slip/antiblock masterbatch at 0.2–0.5 wt% for cap release. Post-mould fluorination may be required for solvent-based emulsifiable concentrate formulations with high xylene content; the barrier treatment is performed at 0.1–1.0 vol% F₂ in nitrogen, and bottles must be purged after treatment to remove hydrogen fluoride residuals. Compliance standards for this segment include FAO/WHO pesticide packaging performance requirements, 21 CFR 177.1520(c) where incidental food contact is possible, and company-specific permeation protocols aligned with ASTM F739-20 for solvent permeation resistance testing. Terminal products are agronomic pesticide bottles, plant growth regulator bottles, and micronutrient foliar containers with TPE or PP child-resistant overcaps. Operational boundary: avoid amine-based antistatic masterbatches because amine migration alters surface charge and can interfere with solvent-based product stability.

In blown film extrusion for high-stiffness industrial liners and food-contact freezer sheets, 6900 is dry-blended with LLDPE at 20–40 wt% to reduce machine-direction tear propagation while retaining melt stability. The blend ratio is controlled gravimetrically because deviations above ±1.5 wt% shift dart drop and tear resistance measurably. Slip/antiblock masterbatch is added at 1–3 wt%, and polymer processing aid is dosed at 0.1–0.4 wt% to lower die-lip deposit on long runs. The film line uses a single-screw extruder with L/D 25–30 and die gap 1.5–2.5 mm; blow-up ratio is maintained at 2.0–3.5, frost line height at 6–12 die diameters, and melt temperature at 210–240 °C. Automated gauge control is set to ±5% of nominal thickness. Compliance standards are FDA 21 CFR 177.1520(c) and EU Regulation (EC) No 10/2011 Annex I, with overall migration limit of 10 mg/dm² under EN 1186-1:2002. Mechanical acceptance is anchored to ASTM D882-18 tensile, ASTM D1922-15(2020) Elmendorf tear, and ASTM D1709-22 Method A dart drop. Terminal products are industrial liners 50–200 µm, freezer sheets, temporary construction films, and medium-duty carrier bags.

Corrugated Drainage Pipe and Cable Conduit Extrusion

The corrugating line for non-pressure drainage pipe processes 6900 through a grooved-feed single-screw extruder with L/D 30–36 and melt temperature range 200–230 °C. The outer corrugation is formed in an annular corrugator under vacuum 0.02–0.05 MPa; block cooling water is kept at 15–30 °C to ensure consistent pitch. Carbon black masterbatch is added at 2.0–3.0 wt% for weathering resistance, antioxidant masterbatch at 0.2–0.5 wt%, and processing aid at 0.05–0.15 wt%. The minimum melt temperature is 200 °C to avoid unmelting and gel formation; the maximum residence time at temperatures above 240 °C should not exceed 5 min to prevent oxidative degradation. Compliance for this process route includes ISO 21138-1:2019, EN 13476-1:2018, ASTM F2306/F2306M-19, and IEC 61386-1:2008 for cable conduit. Terminal products are DN/OD 110–200 mm SN4/SN8 corrugated drainage pipe, perforated land drainage pipe, and cable conduits of 50–150 mm.

When Twin-Sheet Thermoforming Demands Higher Melt Strength

Returnable logistic pallets and dunnage trays are produced by twin-sheet thermoforming of sheet extruded from 6900, with flat-die width 1,200–2,000 mm and polished roll stack temperatures 60–100 °C. The sheet is formed at surface temperatures of 165–195 °C; lower temperatures produce insufficient sheet draw, while temperatures above 200 °C cause sag and wall thinning. Post-industrial regrind from punched pallet blanks is metered at 10–30 wt%, colourant is added at 0.5–2.0 wt%, UV stabilizer at 0.3–1.0 wt%, and black masterbatch at 2.0–3.0 wt% for outdoor returnable assets. Compressed air or vacuum for twin-sheet forming is applied at 0.06–0.09 MPa, and clamp tonnage is 800–1,200 kN for two-sheet parts. Compliance standards are ISO 8611-1:2021 for pallet performance, ASTM D638-22 for tensile yield, ASTM D256-23e1 for notched impact, and REACH plus RoHS 2011/65/EU for hazardous substance control. Terminal products are returnable pallets 800 × 1200 mm, dunnage trays, interlayer sheets for automated warehouse systems, and automotive logistics trays. Operational boundary: do not add PP regrind at any ratio; PP creates discrete phase domains and reduces thermoforming draw consistency.