Blow moulding of a 25 L tight-head jerry can from HD5502ZK is specified for liquid industrial chemicals classified under UN packing group II and III. The published datasheet places melt mass-flow rate at 0.25 g/10 min under ISO 1133-1:2022 at 190 °C/2.16 kg and density at 0.955 g/cm³ under ISO 1183-1:2019. This flow window resists parison sag on a 900 mm parison length and still fills a 1.2 kg shot without excessive melt pressure. On a shuttle blow moulder with L/D 30:1 grooved-barrel extruder, barrel zones are set from 175 °C to 195 °C, head and die at 195 °C, and mould temperature at 12–18 °C. The die gap is profiled from 0.7 mm at the upper neck to 2.2 mm at the bottom pinch area. Blow pressure is held at 0.65 MPa for 10 s. The can wall thickness distribution is programmed to 1.5 mm at the sidewall, 2.2 mm at the chime, and 3.0 mm at the pinch-off corners. The pinch-off geometry must produce a 0.3–0.5 mm flash remnant because thicker flash concentrates weld stress that fails the UN drop test. Regrind from trimmed flash and rejected cans is re-introduced at 20–25 wt% after drying to 0.05 wt% moisture content at 80 °C for 2 h.

Compliance for this container is governed by the UN Model Regulations Chapter 6.1 for non-removable-head packagings. Drop testing is conducted at 1.2 m onto a rigid concrete target with the can filled to 98% nominal capacity using a 1.2 g/cm³ wetting solution at -18 °C. Hydraulic pressure testing applies 250 kPa for 5 min. Stacking load is calculated for a 3.0 m stack stored at 40 °C for 28 days. The finished article is a 20 L or 25 L tight-head jerry can with a 51 mm neck finish, sealed with a PE/EVOH/PE induction liner and a PP screw closure torqued to 3.5 N·m. In production, the dominant field failure is environmental stress crack propagation from the flash trim line when the container is filled with ethoxylated surfactant formulations. Containers exposed to 100% Igepal CO-630 at 50 °C show F50 failure at 70 h on the virgin pellet, dropping to 35 h when 40 wt% in-house regrind is used. This defines the regrind ceiling, not pellet cost.

What Limits Post-Mould Fluorination Depth in Agrochemical Bottle Stock?

Post-mould fluorination of HD5502ZK bottles for ester-based herbicide concentrates is used when the packaged formulation contains solvents that swell untreated polyethylene by more than 3 vol% at 40 °C. The fluorination chamber is first purged with nitrogen to an oxygen concentration below 0.1 vol%. Fluorine is introduced as a 0.5–2.0 vol% F₂ in N₂ blend at 25–35 °C and 0.10–0.15 MPa partial pressure. Reaction time is 15–45 min. The resulting surface layer is 20–60 nm thick with a fluorine-to-carbon ratio of 0.4–0.6 as measured by X-ray photoelectron spectroscopy. This barrier reduces xylene permeation by 90–99% compared with untreated HDPE at 40 °C and 0% RH. Process control is critical because fluorine concentration above 2.5 vol% creates a brittle surface that fractures at the pinch-off weld during drop impact at 1.2 m. Waste gas is scrubbed through a 10% potassium hydroxide solution before release. The compliance link is UN transport classification and local pesticide packaging regulations requiring no visible label delamination and no permeation exceedance over 180 days at 30 ± 2 °C.

The process ratio for this track is 100 wt% HD5502ZK virgin for the bottle body, 5 wt% black masterbatch in the outer layer for UV opacity, and 10 wt% fluorination-compatible polyolefin carrier in the concentrate where high pigment loading is required. Bottles are blow-moulded at 190 °C, cooled for 48 h at 23 °C to stabilise surface crystallinity, and then fluorinated. Failure mode is nonuniform treatment caused by post-mould shrinkage that has not reached equilibrium. The terminal articles are 0.5 L, 1 L, and 5 L HDPE bottles with 38 mm and 45 mm child-resistant closures, used for 2,4-D dimethylamine salt and glyphosate formulations with surfactant load 10–15 wt%. Published data for specific permeation coefficients of HD5502ZK under fluorinated conditions is limited; barrier performance must be confirmed using ASTM D3985-17 for oxygen and ASTM F1307-20 for solvent vapour transmission on the actual container geometry.

Blow-fill-seal monolayer bottles for fresh dairy and edible oil use HD5502ZK without post-consumer recyclate and with only process regrind generated from the same production line. The ratio is set at 85 wt% virgin HD5502ZK and 15 wt% self-trim regrind, dried to 0.03 wt% moisture. The regulatory basis is FDA 21 CFR 177.1520(c) 2.1 for high-density polyethylene articles in contact with aqueous and fatty foods with density 0.955 g/cm³. In Europe, the formulation is assessed under Regulation (EU) No 10/2011, with overall migration below 10 mg/dm² and specific migration of chromium, cobalt, and vanadium below 0.01 mg/kg food simulant. Organoleptic panel testing uses a reference scale of 0–4 for taint in water and 3% acetic acid after 10 days at 40 °C. HD5502ZK with the recommended production stabilizer consistently exhibits a score of 0.5–1.0, whereas off-spec regrind with oxidised surface layers raises the score above 2.0.

On an extrusion blow-moulding wheel with 16 stations, the melt temperature is held at 185–195 °C. Wheel speed is limited by the cooling time of the 2.0 mm base flash because hot flash can adhere to mould surfaces and pull the bottom wall. Mould cooling uses chilled water at 8 °C and 0.3 MPa pressure drop across the channels. The bottles are produced as 500 mL, 1 L, and 2 L handle or non-handle stock. Terminal articles include HDPE bottles for pasteurised milk filled at 4 °C, and bottles for soybean oil, sunflower oil, and blended edible oils with peroxide value below 1.0 meq/kg. The critical processing defect is not melt fracture but pinhole formation at the inner parting line when the pinch-off temperature falls below 175 °C. Pinhole occurrence above 0.1% of bottles triggers immediate die-gap adjustment and an increase in mould pinch pressure to 0.4 MPa.

When the Mandrel and Pinch-Off Geometry Dictate Drop Height in Thin-Wall Lubricant Bottles

When HD5502ZK is extruded into a 4 L lubricant bottle with a 0.8 mm sidewall and an offset handle, the failure location in a 1.2 m drop test is almost always the pinch-off weld at the handle bridge. The die mandrel is profiled with a 0.65 mm gap at the handle bridge and a 1.4 mm gap at the base to shift the weld flash from the high-stress zone. Melt temperature is capped at 190 °C because higher temperatures reduce melt strength and produce a 15% thinner pinch weld after mould compression. The blow mould closes with a pinch land width of 0.8 mm and a pinch angle of 45°. Compressed flash thickness at the handle pinch is held at 0.2–0.3 mm. The bottle is filled with a synthetic ester-based engine oil at 60 °C during the drop test. The standard used is ASTM D2463-15 for drop impact resistance of blow-moulded thermoplastic containers, with a 50% failure height above 1.8 m required for the virgin grade.

The ingredient ratio is 95 wt% HD5502ZK and 5 wt% colour masterbatch with a polyolefin carrier. No processing oil is used because low-molecular-weight lubricants above 0.3 wt% migrate to the surface and reduce label adhesion. The terminal product is a 1 L, 2 L, or 4 L narrow-neck motor oil bottle with a 38 mm or 42 mm closure. Batch-to-batch variation in pellet MI of ±0.03 g/10 min changes the wall thickness distribution enough to shift the handle bridge thickness by 0.08 mm. The extruder control system must therefore hold die pressure within ±0.3 MPa and parison length within ±1.5 mm. The limiting operational boundary is not the drop height but label panel temperature: when the bottle leaves the trim station above 40 °C, pressure-sensitive labels wrinkle. Cooling air temperature must remain below 12 °C or line speed must fall below 2,400 bottles/h.

Barrier Strategies for Solvent-Borne Building Chemicals and Adhesives

For solvent-borne floor adhesives and construction sealants based on toluene, methyl ethyl ketone, and acetone, HD5502ZK monolayer bottles are insufficient for long shelf-life because the solvents permeate through the sidewall above 0.5 g/m²·day at 23 °C. A three-layer coextrusion structure is used: inner HD5502ZK 45 wt%, tie/EVOH/tie 10 wt%, and outer HD5502ZK 45 wt%. The EVOH layer has an ethylene content of 32 mol% and thickness of 0.08 mm. The outer and inner layers use HD5502ZK because its low MI allows stable parison formation with the EVOH barrier layer. The blow head is a three-layer continuous coextrusion head with a 12 L/min melt output. Layer ratio is verified by Fourier transform infrared microscopy on a bottle cross-section. Solvent loss after 90 days at 40 °C is measured by ASTM F1307-20 and must remain below 1.0 wt%. The bottle must also pass the UN 3.1 flammable liquid packaging test when the formulation has a flash point below 35 °C.

The process ratio adjusts scrap reuse: regrind of the three-layer flash cannot be placed in the barrier layer but may be blended into the outer HDPE layer at 20 wt%. The inner layer remains 100 wt% HD5502ZK to avoid adhesive migration into the product. The extruder for the inner and outer layers is set at 180–200 °C; the EVOH extruder is run at 195–210 °C with pre-drying at 90 °C for 4 h to below 0.15 wt% moisture. Moisture above 0.3 wt% causes EVOH hydrolysis and generates pinhole defects visible as a continuous dark line in the barrier layer under polarised light. Terminal products are 0.5 L, 1 L, and 3 L cylindrical or F-style containers with 28 mm tamper-evident closures and a 1.0 mm sidewall. The critical incompatibility is with ketone concentrations above 70 wt%, which attack the tie layer and produce delamination in the shoulder area after 30 days. Published data for this specific coextrusion configuration with HD5502ZK is limited, so permeation and delamination must be confirmed on the actual container geometry.

Stacking Performance in Warm Warehouse Conditions Is Governed by Creep Modulus and Cooling Rate

Open-top pails for water-based construction emulsions are blow-moulded from HD5502ZK with a 1.2 mm wall and a 2.0 mm top lip. Top load is measured by ASTM D2659-16 at 23 °C and 40 °C. At 23 °C, the 10 L pail sustains 3,500 N before 2 mm deflection. At 40 °C, the same pail sustains 2,600 N. The reduction is not caused by density but by creep modulus decay, which is accelerated when the pail is demoulded before the internal surface reaches 45 °C. The cooling cycle is therefore set to 16 s with chilled water at 6 °C. The pails are annealed in a holding tunnel at 80 °C for 5 min to release moulded-in stress at the lip. Failure in warm warehouses occurs as ovalisation of the pail mouth, which prevents a tight lid seal. Ovalisation is measured as a diameter change of more than 1.5 mm after 7 days at 40 °C under a 120 kg top load.

The ratio for this application is 80 wt% virgin HD5502ZK, 15 wt% clean in-house regrind, and 5 wt% UV-stabilised colour masterbatch for outdoor site storage. The pail is formed on a shuttle blow moulder with a 40 mm grooved-barrel extruder, L/D 28:1, and a shot weight of 400 g. Terminal articles are 5 L, 10 L, and 20 L open-top pails with wire or plastic handles, used for polymer-modified tile adhesives, latex paints, and roof coatings. The process bottleneck is not top load but lid seating: the rim must cool below 35 °C within 10 s of demoulding or the lid cannot be press-fit without distortion. Batch-to-batch variation in density of ±0.002 g/cm³ alters shrinkage from 1.8% to 2.2%, changing the rim inner diameter by 0.4 mm. Incoming pellet density is therefore verified by ISO 1183-1:2019 before every silo change.