Extrusion Blow Moulding Envelope for Rigid Food-Contact Containers

HE6067 enters monolayer food-contact blow moulding as a high-density polyethylene with a melt flow rate of 0.7 g/10 min measured at 190°C under 2.16 kg load according to ISO 1133-1:2022 and a density of 0.956 g/cm³ according to ISO 1183-1:2019. The melt rheology provides sufficient parison hang time for shuttle and long-stroke machines producing containers from 0.2 L to 5 L. The die head is set to 195–205°C, the die gap is held at 1.5–2.0 mm for bottle weights between 20 g and 120 g, and the blow-up ratio is limited to 2.2:1–2.8:1. Production equipment for this grade typically includes a single-screw extruder with a 24:1–30:1 L/D barrel, barrier screw, and Maddock mixing element. Head pressure at the breaker plate is monitored below 25 MPa to limit shear heating. Cooling water in the mould circuit is held at 8–12°C, and blow air is introduced at 0.5–0.7 MPa to reduce post-mould neck shrinkage.

The additive formulation for monolayer food-contact bottles uses 97.5–99.0 wt% HE6067 with 1.0–2.5 wt% LDPE-based white masterbatch. The LDPE carrier must not exceed 2.5 wt% because additional low-molecular-weight polyethylene depresses environmental stress-crack resistance in the shoulder and pinch-off weld. A processing aid may be added at 0.1–0.3 wt% only when the specific grade appears on the positive list of the destination market. Compliance includes FDA 21 CFR §177.1520, EU Regulation (EU) No 10/2011 Annex I with an overall migration limit of 10 mg/dm², and GB 4806.6-2016. Terminal finished product types include refrigerated milk bottles up to 2 L, yogurt bottles, condiment squeeze bottles, and snack-food jars. Hot-fill applications with product temperatures above 80°C are outside the operational boundary for HE6067 because sidewall deformation and neck ovality exceed acceptable limits.

Surfactant-rich household cleaning formulations impose a specific environmental stress-cracking load on HDPE sidewalls. Non-ionic ethoxylated surfactants and terpene solvents act as stress-cracking agents; in a 2 L trigger-spray bottle moulded from HE6067, the shoulder/body transition is maintained at 0.6–0.9 mm wall thickness and the main body at 0.5–0.8 mm. A 12-zone parison programmer is required to offset wall-thickness variation greater than ±0.1 mm at the pinch-off weld. Melt temperature at the die is controlled at 195–205°C; excursions above 210°C increase parison sag, while operation below 190°C produces shark-skin melt fracture at the die exit. The critical compliance test is environmental stress-crack resistance under ASTM D1693-15e1 condition B in 10% Igepal CO-630 at 50°C. Retained ESCR must be measured on the actual bottle, not on compression-moulded plaques, because the pinch-off weld and thread area reduce F50 time compared with the resin datasheet value.

The formulation for this service is constrained to 99.0–99.5 wt% HE6067 with 0.5–1.0 wt% colour masterbatch; higher pigment loadings increase the crack initiation rate. A fluoroelastomer processing aid at 0.03–0.08 wt% is used only on high-output lines where die lip build-up causes streaking. Products made under this envelope include detergent bottles, fabric softener bottles, multi-surface cleaner trigger bottles, and bathroom cleaner bottles. Containers intended for oxidising solutions above 12% sodium hypochlorite are outside the unlined monolayer boundary and require fluorination or an internal barrier layer, because neck-area stress cracking under top-load can cause premature ruptures.

What Limits ESCR Retention When HE6067 Is Blended with Post-Consumer Resin?

The incorporation of post-consumer recycled HDPE into HE6067 for non-food blow moulding is operationally permitted but shifts the slow crack growth threshold. Published data for this specific HE6067/PCR configuration is limited; converters must establish lot-specific ESCR on the actual bottle geometry before freezing the formulation. The standard blend band for non-food containers is 70–80 wt% HE6067 with 20–30 wt% washed and ground post-consumer HDPE. For low-risk non-food products the recycled fraction is occasionally extended to 50 wt%, but the drop impact margin at −18°C narrows. A 0.5–1.0 wt% blue masterbatch is added, and antioxidant carry-over from the recycled fraction is compensated by adding 0.05–0.15 wt% of a phosphite antioxidant masterbatch.

Processing uses a 30:1 L/D single-screw extruder with a continuous melt filter of 120–200 mesh to remove residual gel particles. Melt temperature is held at 195–205°C. The die gap is increased by 0.2–0.3 mm relative to virgin-only operation because the filter raises head pressure by 0.5–1.5 MPa. Compliance is anchored to EU Packaging and Packaging Waste Directive 94/62/EC, REACH Annex XVII, and ISO 14021:2016 for recycled content claims. Terminal products are restricted to non-food household chemical bottles, industrial packaging, and waste containers. Food-contact use is excluded unless the recycled fraction meets a valid EU novel-technology approval or an FDA letter of no objection for the specific recycling process.

A three-roll polishing stack processing HE6067 at 200–230°C melt temperature produces sheet from 0.5 mm to 1.5 mm thickness. Compared with blow moulding, this route demands a lower melt-temperature spread across the die exit. Die bolt adjustment is used to maintain gauge variation within ±0.03 mm. The resin addition ratio is 100 wt% HE6067 for natural translucent sheet or 97.0–98.5 wt% HE6067 with 1.5–3.0 wt% white masterbatch for opaque food trays. For thermoforming, the sheet is heated to 120–130°C surface temperature and formed with plug-assisted tooling at a draw ratio not exceeding 2.5:1. Below that threshold the melt strength of HE6067 minimises corner thinning. Three-roll stack temperatures are held at 70–85°C for the polished roll and 50–65°C for the second roll to control sheet crystallinity.

Compliance for food-contact sheet falls under FDA 21 CFR §177.1520 and EU Regulation (EU) No 10/2011, with the same overall migration limit of 10 mg/dm². Terminal parts include thermoformed freezer trays, dairy product trays, cosmetic packaging trays, and disposable protective packaging for industrial components. Published data for deep-draw HE6067 sheet beyond a draw ratio of 2.5:1 is limited; converters should evaluate plug material and dual-sheet thermoforming separately before committing to production.

When UN Certification Requires −18°C Drop Performance in Blow-Moulded Jerricans

UN-certified jerrican production from HE6067 moves the critical design parameter from ordinary ESCR to low-temperature impact after full-scale drop testing. Accumulator blow moulding machines with clamp forces of 50–150 t are used for 10–30 L containers, with a 2.5–3.5 mm die gap and melt temperature held at 190–205°C. The parison is programmed across 10 points so the sidewall remains at 0.8–1.2 mm and the corners at 1.4–2.0 mm. Wall-thickness deviation greater than ±0.2 mm at the handle juncture causes drop-test failures at the injection pinch line. Mould cooling water at 8–12°C and internal blow air at 0.4–0.7 MPa are used to stabilise neck dimensions.

The formulation is set at 98.5–99.5 wt% HE6067, 0.5–1.5 wt% carbon black masterbatch for outdoor UV resistance, and 0.05–0.15 wt% hindered amine stabiliser masterbatch. Carbon black loadings above 1.5 wt% reduce the −18°C drop impact margin. Compliance is tested under ADR Chapter 6.1 and UN Model Regulations Chapter 6.1. The container is conditioned for 24 h at −18°C, filled to 98% capacity with water/glycol, and dropped from the packing-group-specified height. Terminal finished products include jerricans for lubricants, agrochemical concentrates, water-treatment chemicals, and automotive fluids. Containers for packing group I liquids are outside the standard HDPE jerrican boundary unless additional outer packaging or supplementary approval is provided.

Pharmaceutical and personal care packaging lines require organoleptic neutrality and tight lot-to-lot control of odour, taste, and extractables. HE6067 is processed in closed extrusion blow moulding cells with HEPA-filtered blow air at 0.3–0.5 MPa and melt temperature maintained between 195°C and 205°C. The addition ratio for white bottles is 99.0–99.5 wt% HE6067 with 0.5–1.0 wt% white masterbatch pre-approved under USP <661.1> and Ph. Eur. 3.1.3 for polyolefins. Natural bottles are moulded at 100 wt% HE6067. Slip agents and antistatic additives are excluded because migration into the fill product changes the extractable profile and can fail the 10 mg/dm² overall migration limit under EU Regulation (EU) No 10/2011.

Terminal products are limited to non-sterile oral and topical packaging, such as shampoo bottles, conditioner bottles, body wash containers, vitamin and nutraceutical bottles, and non-sterile topical cream containers. The resin is not intended for parenteral or ophthalmic primary containers. Any clean-room claim must be validated against ISO 14644-1 air cleanliness class and the selected terminal disinfection method. Extractables testing per USP <661.1> and Ph. Eur. 3.1.3 is performed on the finished container, not on the resin alone, because extrusion heat history can generate low-molecular-weight species that affect the result.