PetroChina Jilin HDPE 0855 is a blow-moulding-grade high-density polyethylene specified at a melt flow rate of 0.55 g/10 min under ISO 1133-1:2022 and a density of 0.958 g/cm³ under ISO 1183-1:2019; certificate-of-analysis verification is required because melt flow rate drift beyond ±0.05 g/10 min alters parison sag and pinch-off weld integrity. In household detergent and personal-care bottle production, the grade is processed on shuttle-type extrusion blow moulders with grooved-feed extruders of 50 mm to 70 mm screw diameter and 24:1 length-to-diameter ratio. The barrel temperature profile is set from 160 °C at the feed section to 185 °C at the metering section, with head and die zones maintained at 180 °C to 195 °C; melt temperature measured at the die exit is kept below 205 °C to suppress oxidative chain scission. A die gap of 1.2 mm to 2.0 mm and a die land length of 12 to 18 times the gap are used to control die swell, which in this MFR class is typically 1.3 to 1.6 times the annular gap. The parison programmer closes the die gap by 40% to 60% near the tail pinch-off and opens it by 10% to 20% in the bottle body zone to compensate for container shoulder thinning. Mould temperature is maintained at 8 °C to 15 °C, and blow air pressure is set at 0.6 MPa to 0.8 MPa; multiple blow-air steps with delayed exhaust reduce post-mould shrinkage below 1.5% in the threaded neck area. Terminal bottle sizes range from 250 mL to 2 L, with typical sidewall thickness between 0.6 mm and 1.0 mm and a target article mass of 28 g to 58 g for a 1 L bottle. Compliance for these non-food containers is evaluated under EU 10/2011 only if food contact is claimed; otherwise the relevant framework is EU 94/62/EC packaging essential requirements and REACH Article 33 for SVHC disclosure. Mechanical acceptance testing includes tensile yield strength in the range 22 MPa to 28 MPa under ISO 527-2:2012, flexural modulus of 950 MPa to 1,200 MPa under ISO 178:2019, and Charpy notched impact above 6 kJ/m² at -30 °C under ISO 179-1:2023. Environmental stress cracking resistance is checked under ASTM D1693-21 condition B in 100% Igepal CO-630 at 50 °C, with an F50 of at least 40 h for detergent packaging. Pre-drying at 80 °C for 2 h is applied only when ambient relative humidity exceeds 60% to avoid surface splay on the parison.

What Controls Wall Thickness Integrity in UN 3H1 Jerry Can Moulding?

In 10 L to 30 L jerry can production, the limiting process variable is parison sag, which is controlled by the melt strength associated with the 0.55 g/10 min melt flow rate of HDPE 0855 under ISO 1133-1:2022. Accumulator-head extrusion blow moulding machines are specified with screw diameters of 80 mm to 120 mm and 24:1 to 30:1 L/D, and the head shot capacity is matched to the article weight so that the accumulator fill time remains below 85% of the cooling time. The die gap is set at 1.8 mm to 2.5 mm, and the head temperature is held at 180 °C to 195 °C; a parison programmer applies 20% to 40% gap reduction at the handle pinch-off and 10% to 15% gap reduction at the bottom pinch-off to prevent thick weld beads. A blow pressure of 0.8 MPa to 1.0 MPa and mould temperature of 10 °C to 20 °C are standard, with a cycle time of 60 s to 90 s for a 20 L container weighing 1.2 kg to 1.6 kg. The sidewall thickness is specified at 2.0 mm ±0.2 mm, increasing to 2.4 mm minimum at handle bridges and corners, because UN drop tests concentrate impact energy at these regions. Compliance for dangerous goods transport requires the finished jerry can to be certified as UN 3H1 packaging under the UN Model Regulations; the tests listed below are applied to production samples. Environmental stress cracking resistance under ASTM D1693-21 condition B is specified because high-stress areas at the pinch-off weld are exposed to aggressive liquids such as aliphatic hydrocarbons and surfactant formulations. Published data for this specific grade under every UN test condition is limited on public datasheets, so certification must be performed on the actual moulding line.

When Regrind Reaches 30 wt% in Three-Layer Coextrusion

Melt flow drift during closed-loop regrind handling creates a process conflict in three-layer A-B-A blow moulding when recovered HDPE 0855 exceeds 30 wt% of the total shot weight. The virgin layers are specified as the outer and inner skins at 25% each of the total thickness, while the core layer carries 50% of the wall thickness and contains the recovered material. Regrind is generated from flash, top and tail waste, and rejected containers, granulated to a screen size of 8 mm and blended at 70/30 virgin-to-regrind mass ratio as a baseline. The process conflict arises because repeated extrusion at melt temperatures above 195 °C increases the melt flow rate of the recovered stream by 0.1 g/10 min to 0.3 g/10 min per pass under ISO 1133-1:2022; once the blended MFR exceeds 0.75 g/10 min, parison drawdown accelerates and die swell decreases from 1.4 to 1.2, reducing sidewall thickness at the shoulder by 0.1 mm to 0.2 mm. The corrective action is to lower the die-head temperature by 5 °C to 10 °C, close the parison programmer gap by 0.2 mm in the bottle body zone, and increase blow pressure to 0.8 MPa. If the regrind fraction is raised above 50 wt%, the core layer exhibits visible black speck contamination and the Charpy notched impact under ISO 179-1:2023 drops below 5 kJ/m² at -30 °C, so this configuration is limited to non-food, non-dangerous-goods packaging. Terminal products include recycled-content bottles for household chemicals, automotive care products, and industrial cleaning compounds. Compliance for the recycled layer is assessed under EU 94/62/EC packaging essential requirements and REACH; if harmonised food-contact migration is claimed, the recycled layer must meet EU 2022/1616 and the virgin HDPE layer must have its own suitable migration compliance under EU 10/2011. Published data for this specific grade in three-layer regrind structures is limited, so in-process monitoring by capillary rheometry at 190 °C is recommended.

Automotive under-hood reservoirs blow moulded from HDPE 0855 are exposed to continuous service temperatures near 80 °C and intermittent contact with windshield washer fluids containing methanol or ethanol at 30 vol% to 50 vol%. The grade is processed on three-dimensional blow moulding machines with parison manipulation, and the melt temperature is limited to 200 °C to reduce odour formation from oxidation. The pinched weld at the parison parting line is specified at 2.5 mm minimum because fracture in washer reservoirs typically initiates at this location during vibration testing under ISO 16750-3. Mould cooling is maintained at 12 °C to 18 °C, and internal air pressure during cooling is held at 0.7 MPa to minimise sink marks around the filling neck. Heat-ageing resistance is checked by conditioning mouldings for 500 h at 80 °C and measuring tensile strength retention under ISO 527-2:2012; a retained yield stress above 20 MPa is required. Windshield washer fluid immersion under ASTM D543-21 at 60 °C for 168 h is specified to produce less than 1.5% mass change. Terminal parts include windshield washer reservoirs, coolant overflow bottles, and hydraulic fluid reservoirs for commercial vehicles; these are designed with ribbing to limit deformation at 0.1 MPa internal pressure. Published data for this specific grade in 3D blow moulding applications is limited, so pre-production trials on the target OEM tool are mandatory.

Fluorination and Permeation Control in Agrochemical Container Systems

For agricultural chemical containers of 5 L to 20 L, HDPE 0855 is processed on accumulator-head blow moulders with in-line fluorination of the parison inner surface. The fluorination gas is a nitrogen-diluted fluorine mixture with fluorine concentration below 1 vol%; the reaction is carried out at the die head and parison interior for a controlled exposure time of 1 s to 5 s, producing a fluorinated barrier layer that reduces solvent permeation by 80% to 95% relative to untreated HDPE when measured gravimetrically at 40 °C after 14 days under ASTM D543-21. The bottle wall thickness is specified at 2.0 mm minimum, and the handle pinch-off is reinforced to 2.6 mm because agrochemical formulations often contain xylene, cyclohexanone, or heavy aromatic naphtha in concentrations up to 60 wt%. Process temperatures are held at 180 °C to 195 °C; higher die-head temperatures accelerate fluorine uptake but also increase the risk of surface discolouration and melt fracture. The containers are evaluated under ASTM D1693-21 condition B for environmental stress cracking resistance and under UN 6.1.5.3 at -18 °C for drop impact. Terminal products include crop protection chemical bottles, adjuvant bottles, and concentrated emulsion packaging. The fluorinated surface is not a food-contact layer and must not be reground into food-contact packaging; if the containers are to be shipped as dangerous goods, the completed package is tested as UN 3H1 with the specific formulation. Published data for fluorine barrier performance of this exact grade is limited, so fill-condition permeation testing is required for each solvent system.

Thick-Walled Injection Moulding Remains Narrow in Scope

When HDPE 0855 is processed on injection moulding equipment, the 0.55 g/10 min melt flow rate under ISO 1133-1:2022 restricts the process to thick-walled industrial articles such as cable joint closures, pump housings, and industrial closures. Melt temperature is set at 200 °C to 220 °C, and injection velocity is profiled as 20 mm/s to 40 mm/s to prevent jetting; hold pressure is maintained at 40 MPa to 60 MPa for 6 s to 10 s per 1 mm of nominal wall thickness. Mould shrinkage is compensated at 1.5% to 2.5% under ISO 294-4. The low melt flow rate produces high melt viscosity, so injection pressure at the screw tip often reaches 120 MPa to 160 MPa; this demands clamp force calculations above 2 kN per projected square centimetre. Terminal products do not carry food-contact claims unless separate migration compliance under EU 10/2011 is demonstrated on the finished article. Published data for this specific grade in thin-wall injection moulding is limited and the application is generally confined to articles with flow length-to-thickness ratios below 150:1.

Sheet extrusion lines running HDPE 0855 are typically configured with 90 mm to 120 mm single-screw extruders with 30:1 L/D and barrier screws. Flat die temperatures are maintained at 190 °C to 210 °C, and the polishing stack roll temperature is set at 60 °C to 80 °C with an air gap below 100 mm to suppress draw resonance. Thermoforming of extruded sheet from 2 mm to 6 mm thickness requires radiant heating at 220 °C; the 0.55 g/10 min melt flow rate delays sheet sag during heating, but the forming window narrows because the sheet cools rapidly once the mould closes. Terminal parts include industrial dunnage trays, battery liners, and reusable transport packaging. Flexural modulus is measured under ISO 178:2019, and dimensional stability after 24 h at 60 °C is assessed under ISO 11501. The sheet is not UV-stabilised as a base grade, so outdoor service requires a carbon black masterbatch at 2 wt% to 2.5 wt% or an approved UV stabiliser package. Published data for this specific grade in thermoforming is limited; pre-production forming trials are necessary to set the correct plug-assist speed and mould temperature.