Extrusion blow moulding of 1 L to 5 L industrial chemical containers from TAISOX 8001 is carried out on single-station shuttle machines with a general-purpose PE screw of 24:1 to 32:1 L/D, a compression ratio of 2.5:1 to 3.5:1, and a clamp force of 200 kN to 800 kN. Barrel set points are normally 180°C at the feed throat, 195°C in the transition zone, and 205°C at the metering zone; the die head is held at 200°C to 215°C to obtain a parison exit temperature of 190°C to 210°C measured by IR pyrometer. For a 1 L narrow-neck bottle with a target sidewall thickness of 0.9 mm, the die gap is set at 2.0 mm to 2.4 mm and blow pressure is applied at 0.6 MPa to 0.8 MPa. The resin’s nominal melt flow index of 0.8 g/10 min when tested to ISO 1133-1:2022 at 190°C under 2.16 kg and density of 0.954 g/cm³ when tested to ASTM D1505-18 provide sufficient parison hang strength at these temperatures, but die swell increases if the die temperature drops below 195°C. In bleach and quaternary ammonium disinfectant packaging, environmental stress crack resistance is evaluated under ASTM D1693-15 Method B in 10% Igepal CO-630 at 50°C; internal release criteria commonly require an F50 value above 100 h for surfactant products and above 200 h for hypochlorite concentrates, but final decisions are tied to bottle burst and drop tests. Top-load strength of the finished container is measured by ASTM D2659-16 at 23°C and 50% relative humidity; acceptance limits are product-specific and derived from distribution stacking loads rather than a single fixed value. Cooling water at 8°C to 15°C is used for the mould, and a blow time of 8 s to 12 s followed by exhaust of 1 s to 2 s prevents post-mould longitudinal shrinkage above 1.5% after 24 h at 23°C.

What Limits Wall Uniformity in Three-Layer Coextrusion with PCR HDPE?

When TAISOX 8001 is used as the skin layer in a three-layer structure with post-consumer recycled HDPE in the core, the limiting factor is not the resin’s melt flow index alone but the shear-viscosity difference between the virgin skin and the PCR core at the feedblock temperature of 205°C to 215°C. Post-consumer streams vary from 0.3 g/10 min to 1.0 g/10 min under ASTM D1238-23, and if the core viscosity is more than 20% lower than the skin viscosity, interfacial instability appears as wavy parison walls and a loss of top-load stiffness. Coextrusion heads with a spiral mandrel or a side-fed feedblock require pressure-balanced flow channels; a pressure differential greater than 1.0 MPa between the skin and core extruders at the die entrance is used as a troubleshooting threshold because it produces visible layer instability in 30 g to 60 g bottles. Screen packs with 60/80/100 mesh are inserted after the breaker plate on the PCR extruder to remove aluminium foil and label particles; pressure drop across the pack is monitored and replacement is scheduled when differential pressure exceeds 8 MPa, because beyond this point viscous heating raises melt temperature by 5°C to 10°C and generates gel particles. Layer ratios of 20% virgin cap, 60% PCR core, and 20% virgin inner layer are typical for detergent bottles, but the inner layer must remain free of post-consumer odour and must comply with REACH Article 33 when SVHC-containing legacy additives are present. Top-load strength of the finished bottle is measured by ASTM D2659-16; bottles with visible layer waviness are rejected before testing because column crush failure appears at the pinch-off seam.

Control point	Measured variable	Method or equipment	Typical setting or limit
Skin extruder die zone	Melt temperature	IR pyrometer	200°C to 215°C
PCR core extruder	Screen pack pressure drop	Melt pressure transducer	Max 8 MPa
Die entrance	Skin-core pressure differential	Coextrusion feedblock probes	Max 1.0 MPa
Finished bottle	Top-load strength	ASTM D2659-16	Product-specific; failure mode documented

UN-certified packaging for Packing Group II and III liquid agrochemical formulations requires a hydrostatic pressure test at 100 kPa for 30 minutes and a drop test at 1.2 m for Packing Group II products with relative density greater than 1.2, depending on capacity. TAISOX 8001 bottles in the 1 L to 5 L range are blow-moulded with a minimum wall thickness of 0.8 mm, and the closure thread must withstand a stripping torque of 1.2 N·m to 1.8 N·m during laboratory qualification for 38 mm HDPE closures. The parison programmer sets axial wall thickness at 4.0 mm near the neck, 2.6 mm along the body, and 3.2 mm at the bottom pinch-off to reinforce the seam where drop impact at -18°C produces wedge cracks. Environmental stress crack resistance is evaluated according to ASTM D1693-15 Method A in 10% nonylphenoxypoly(ethyleneoxy)ethanol at 50°C; qualification protocols for xylene-containing emulsifiable concentrates impose an F50 limit above 200 h because aromatic solvents reduce the resin’s crack resistance. The mould temperature is kept at 15°C to 20°C to balance crystallinity and ESCR; lower mould temperatures accelerate cycle time but reduce ESCR at the handle attachment. The finished container is conditioned for 48 h at 23°C and 50% RH before burst testing at 1.5 times the UN test pressure to account for residual stress relaxation.

Sheet Thermoforming Crystallinity Gradients Require Controlled Roll Stacks

In sheet extrusion from TAISOX 8001 on a 90 mm single-screw extruder with a 30:1 L/D barrier screw and a 1.2 m wide coat-hanger die, the melt temperature at the die exit is maintained at 205°C to 220°C, and the sheet is calibrated through a three-roll stack with the top roll at 60°C, the middle roll at 70°C, and the bottom roll at 50°C. These roll temperatures produce a controlled crystallinity gradient through the 2.0 mm sheet that improves thermoforming uniformity. The sheet is heated to 155°C to 170°C with ceramic IR heaters before forming into dunnage trays; a draw ratio of 2.5:1 to 4.0:1 is used, and wall thickness variation at the tray corners is held to ±0.2 mm. Flexural stiffness of the formed part is checked by ISO 178:2019 at a test speed of 2 mm/min; published data for this specific configuration is limited, so first-article parts should be correlated with mould temperature and sheet thickness.Large-volume blow moulding of 120 L to 220 L inner bottles for composite IBCs uses TAISOX 8001 on accumulator-head machines with a shot capacity of 15 kg to 30 kg, a 100 mm to 150 mm extruder screw, and a clamp force of 2500 kN to 4000 kN. Parison hang strength is the controlling variable because the parison mass exceeds 10 kg and the drop time before mould closing is 5 s to 10 s. The axial wall programmer sets a 9.0 mm neck section, a 4.5 mm sidewall, and a 6.0 mm bottom pinch zone; blow pressure is applied at 0.7 MPa to 0.9 MPa. Mould cooling water at 10°C to 15°C removes heat from the 4 mm to 6 mm wall, but a cooling time of 120 s to 240 s is required for thick sections to reach demoulding temperature below 75°C. After moulding, the bottle is trimmed at the pinch-off tail and tested by a hydraulic pressure test at 100 kPa for 30 minutes; drop impact at 1.6 m at -18°C is performed on the filled IBC inner bottle to verify weld integrity. The resin’s density of 0.954 g/cm³ and melt flow index of 0.8 g/10 min provide the stiffness needed for the composite frame, but the moulder must confirm that the grade’s ESCR under ASTM D1693-15 Method B exceeds the specific chemical compatibility requirement for the intended filling liquid.

When Recyclate Fractions Shift Melt Flow Stability Across Production Runs

The maximum closed-loop regrind addition in TAISOX 8001 blow moulding is set by the melt flow shift and gel accumulation, not by a fixed blend ratio. When 20 wt% to 30 wt% of edge trim and rejected bottles are reintroduced after shredding and air classification, the melt flow index of the blend may move from 0.8 g/10 min by 0.1 g/10 min to 0.3 g/10 min under ASTM D1238-23. This shift changes parison die swell by 2% to 5% and wall thickness distribution by 0.1 mm to 0.3 mm; therefore, the parison programming curve is re-zeroed after every 10% change in regrind content. Extruder head pressure at the die inlet is maintained at 25 MPa to 35 MPa; an increase above 40 MPa at constant screw speed indicates gel build-up at the screen pack and requires a pack change. For non-food industrial bottles, addition of 0.5 wt% to 1.0 wt% calcium stearate may be used as a lubricant, but this additive reduces environmental stress crack resistance under ASTM D1693-15 and is not used in hypochlorite contact layers. For indirect food contact applications, the final article must comply with FDA 21 CFR 177.1520(c) with the specified density and maximum extractables conditions; the moulder must also demonstrate that the recyclate fraction does not introduce substances that are not cleared under the same regulation. REACH Article 33 communication obligations apply if the supplied regrind contains SVHC at concentrations above 0.1% by weight in the final article.

Application route	Compliance reference	Test method or condition	Typical control limit
Chemical packaging, UN Packing Group II/III	UN Model Regulations Chapter 6.1	Hydraulic pressure 100 kPa	30 min, no leak
Indirect food contact	FDA 21 CFR 177.1520(c)	Density and extractives	As specified in regulation
EU industrial packaging	REACH Article 33	SVHC screening	≤ 0.1 wt% in article
Top-load strength	ASTM D2659-16	Column crush at 23°C, 50% RH	Product-specific; report failure mode
Environmental stress crack resistance	ASTM D1693-15 Method B	10% Igepal CO-630 at 50°C	F50 > 200 h for aggressive chemical formulations