CNOOC & Shell (CSPC Huizhou) HDPE 5421B
- Product Name: CNOOC & Shell (CSPC Huizhou) HDPE 5421B
- Factroy Site: Yinchuan, Ningxia, China
- Price Inquiry: sales8@ascent-chem.com
- Manufacturer: Ascent Petrochem Holdings Co., Limited
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- CNOOC & Shell (CSPC Huizhou) HDPE 5421B is typically used in formulations when melt flow rate and density and processing temperature and die head pressure must be controlled within specific ranges.
| HS Code | 615781 |
| Product | CNOOC & Shell (CSPC Huizhou) HDPE 5421B |
| Density | 0.954 g/cm³ |
| Melt Flow Rate 190 C 2 16 Kg | 0.35 g/10 min |
| Tensile Strength At Yield | 25 MPa |
| Tensile Strength At Break | 30 MPa |
| Elongation At Break | 600% |
| Flexural Modulus | 1000 MPa |
| Notched Charpy Impact Strength 23 C | 15 kJ/m² |
| Vicat Softening Temperature | 125 °C |
| Heat Deflection Temperature 0 45 Mpa | 70 °C |
| Shore Hardness D | 60 |
| Environmental Stress Cracking Resistance F50 | >1000 h |
| Melting Point | 130 °C |
| Volume Resistivity | >10^16 Ω·cm |
| Dielectric Constant 1 Mhz | 2.3 |
| Water Absorption 24 H | <0.01% |
| Thermal Conductivity | 0.45 W/m·K |
| Linear Thermal Expansion Coefficient | 1.2×10^-4 /°C |
| Brittleness Temperature | <-70 °C |
As an accredited CNOOC & Shell (CSPC Huizhou) HDPE 5421B factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | CNOOC & Shell CSPC Huizhou HDPE 5421B is packed in 25 kg PP woven bags with PE liners, 1,000 kg per pallet. |
| Container Loading (20′ FCL) | 20′ FCL loading of CNOOC & Shell (CSPC Huizhou) HDPE 5421B: palletized 25kg bags, floor-loaded, seaworthy, maximum payload, secure stowage. |
| Shipping | CNOOC & Shell (CSPC Huizhou) HDPE 5421B shipping: Not dangerous goods; no UN number. High-density polyethylene pellets, non-hazardous. Packed in 25 kg bags, jumbo bags, or bulk containers. Keep dry, cool, and clean. Standard freight; avoid moisture, heat, sunlight, and contamination. |
| Storage | Store CNOOC & Shell (CSPC Huizhou) HDPE 5421B in a cool, dry, well-ventilated warehouse away from direct sunlight, heat, flames, and strong oxidizers. Keep original bags/containers sealed to prevent moisture, dust, and contamination. Stack on pallets at safe heights to avoid deformation. Maintain good housekeeping and avoid prolonged UV exposure. Protect from physical damage and keep away from incompatible materials. |
| Shelf Life | Shelf life is 24 months from production when stored unopened in a cool, dry, ventilated area away from direct sunlight. |
The accumulator-head monolayer blow moulding of 5 L–25 L UN-certified jerrycans for chlorinated cleaners, liquid detergents, and water-based agrochemical adjuvants is the primary production route in which HDPE 5421B from CSPC Huizhou is converted into load-bearing industrial packaging. Barrel temperature profile on a 75 mm single-screw extruder with a 25:1 L/D barrier screw and grooved feed section is set from 180 °C in zone 1 to 205 °C in zone 4, with the accumulator head and die maintained at 200–210 °C and the melt exiting the die at 200–215 °C when measured by infrared pyrometer. A 20-point parison programmer is used because the HDPE melt exhibits time-dependent sag in the 0.9–1.1 mm wall-thickness target range for a 10 L jerrycan; without axial programming, top-to-bottom wall variation exceeds 0.2 mm and thin spots appear at the pinch-off zone. Die gap is set between 0.8 mm and 1.2 mm depending on container volume, and blow pin calibration pressure is maintained at 0.4–0.7 MPa. Mould cooling water is controlled at 10–15 °C to shorten cycle time without generating frozen-in stress at the flash line. The pinch-off weld is trimmed cold; residual flash above 0.3 mm at the weld is rejected before destructive testing because it concentrates stress during the UN 6.1.5.3 drop test at 1.2 m for Packing Group II liquids. Parts are also subjected to leakproofness testing under UN 6.1.6.2 using the pressure defined for the design type, and environmental stress cracking resistance is screened according to ASTM D1693-15 Condition B in 10 % Igepal CO-630 at 50 °C. Published data for HDPE 5421B under cyclic exposure to 5.25 % sodium hypochlorite at 50 °C is limited, so release testing is performed against an in-house F50 control rather than an absolute value. Drying is required at RH > 60 % or when the regrind fraction exceeds 30 wt%: 2 h at 80 °C in a desiccant dryer prevents surface splay and melt-pressure fluctuation above 25–35 MPa at the breaker plate.
What Governs ESCR-Limited Failure in Household Detergent and Bleach Containers?
Failure in 1 L–5 L household detergent, fabric softener, and hypochlorite bleach bottles is rarely tensile yield; it is environmental stress cracking initiated at moulded-in residual stresses, sharp neck-to-body transition radii, and pinch-off tail flash. HDPE 5421B is screened for this service using ASTM D1693-15 Condition B with 10 % Igepal CO-630 at 50 °C, and the F50 time is reported against an in-house reference resin because ESCR rankings shift with cooling rate, degree of crystallinity, and part thickness. Accelerated mould cooling at 12–18 °C used to reduce cycle time can lower crack initiation time if the bottle is not uniformly cooled in the neck and handle regions; therefore mould temperature is staged at 12 °C in the main cavity and 25 °C in the pinch-off insert to avoid localized frozen-in strain. Neck-to-body transition radii below 1.5 mm act as stress concentrators and are rejected during tooling review; radii of 1.5–2.5 mm are specified for bleach bottle designs below 1 L. Wall thickness is maintained at 0.6–1.2 mm for a 1 L bottle weighing 32–65 g, and the handle flash is trimmed to no more than 0.2 mm because thick flash at the pinch-off tail behaves as a crack initiator under ASTM D1693 exposure. Melt temperature at the die exit is held at 195–205 °C to avoid excessive orientation and reduce parison sag in long-neck designs; die land length-to-gap ratio of 10:1 to 15:1 is used to limit melt fracture and sharkskin at high shear rates. Hypochlorite bleach bottles require a non-reactive stabilizer system; antistatic or slip masterbatches based on amine-based additives are not used because secondary amines react with sodium hypochlorite, causing yellowing and autocatalytic oxidation. Formula verification is carried out by ASTM D543-21 immersion in 5.25 % sodium hypochlorite at 23 °C for 7 days, with tensile retention measured by ASTM D638-14 Type IV specimens cut from bottle sidewalls.
| Application | Standard / method | Condition | Release target |
|---|---|---|---|
| UN-certified jerrycans | UN 6.1.5.3 | Packing Group II, 1.2 m drop height, 20 °C | No leakage or rupture on drop, top, side, seam |
| Environmental stress crack resistance | ASTM D1693-15 | Condition B, 10 % Igepal CO-630, 50 °C | F50 compared with in-house control |
| Chemical compatibility | ASTM D543-21 | Immersion in actual formulation, 23 °C, 7 days | Mass change ≤ 0.5 % for barrier bottles, ≤ 1.0 % for automotive fluids |
| Low-temperature drop impact | ASTM D2463-15 | Filled bottle, -20 °C, 24 h | Report F50 height; no brittle pinch-off split |
| Melt flow rate | ISO 1133-1:2022 | 190 °C, 2.16 kg | Compare with COA |
| Density | ISO 1183-1:2019 | Method D, gradient column | Compare with COA |
Blow moulded as the outer, inner, and regrind-tolerant layers in six-layer coextrusion barrier bottles for agricultural chemicals and crop protection concentrates, HDPE 5421B functions as the structural HDPE phase while EVOH or polyamide supplies the permeation barrier. A six-layer spiral mandrel die with a 250 mm centreline is operated at 200–210 °C at the die exit, and the barrier layer melt temperature is limited to 210 °C to prevent gel formation from EVOH thermal degradation. The structure is commonly outer HDPE / tie / EVOH / tie / regrind / inner HDPE, with HDPE 5421B used in both skin and inner contact layers and with regrind fractions in the regrind layer not exceeding 30 wt% of total bottle weight unless drop testing at -10 °C demonstrates no brittle failure. When reworked trim containing EVOH is incorporated, the EVOH domain size must remain below 20 µm; larger domains nucleate brittle cracks under ASTM D2463-15 drop impact after 24 h conditioning at -10 °C. Chemical compatibility is validated by ASTM D543-21 immersion in the exact formulated solvent mixture at 23 °C for 7 days; mass change above 0.5 % or tensile retention below 80 % triggers a barrier-layer redesign or an alternative inner skin resin. The target wall thickness for a 1 L agrochemical bottle is 0.8–1.2 mm, and the EVOH barrier layer is maintained at 4–6 % of total bottle weight to meet permeation limits for xylene-containing formulations. Bottles passing the D543 immersion protocol are then subjected to UN drop testing on filled packagings at 1.2 m for Packing Group II, with particular attention to the flash line and handle pinch-off. Production-scale six-layer lines have shown sporadic gel specks in the outer HDPE layer when the EVOH melt temperature exceeds 215 °C or when screw speed on the barrier extruder is increased above 80 rpm; gel counts are therefore monitored by visual inspection against a 0.5 mm black-spec standard before printing.
When Continuous Sheet Lines Supply Pressure Forming Stations for Non-Food Industrial Trays
Direct sheet extrusion from HDPE 5421B into pressure-formed industrial trays requires a 90 mm extruder with a 30:1 L/D single screw and screen pack of 60/80/100 mesh, because the high-viscosity melt retains thermal memory in sheet thickness above 1.5 mm. Extruder barrel temperatures from 190 °C in the feed zone to 210 °C in the metering zone feed a 1,000 mm sheet die with a die gap set 0.1–0.2 mm narrower than the desired sheet gauge; the polished three-roll stack is maintained at 75–95 °C to control sheet stress and minimise warpage after punching. Sheet thickness for industrial dunnage and machinery covers is held between 0.8 mm and 2.0 mm, with gauge variation across the sheet width not exceeding ±0.05 mm as measured by a beta gauge. Pressure forming uses top and bottom ceramic heaters set at 180–200 °C; the sheet surface temperature before forming is measured by infrared pyrometer at 155–165 °C, because lower temperatures cause plug puncture and higher temperatures produce sagging and wall thinning in deep-draw trays. Plug assist speed is set at 200–300 mm/s, and mould vacuum is maintained at 0.08 MPa with mould temperature between 25 °C and 40 °C to achieve consistent material distribution. Mechanical screening uses tensile modulus measured by ISO 527-2 on die-cut specimens in the machine and transverse directions, with anisotropy ratio greater than 1.3 indicating excessive machine-direction orientation that must be corrected by roll-stack gap adjustment. Food-contact use is not assumed; HDPE 5421B is used for non-food industrial trays, dunnage, and compartment liners unless the supplier provides FDA 21 CFR 177.1520 or EU 10/2011 documentation for the exact lot.
| Conversion route | Equipment type | Parameter | Range |
|---|---|---|---|
| Accumulator blow moulding | 75 mm single-screw, L/D 25:1 | Die exit melt temperature | 200–215 °C |
| Continuous extrusion blow moulding | 60 mm barrier screw, L/D 24:1, rotary wheel | Melt temperature | 195–210 °C |
| Six-layer coextrusion | 250 mm spiral mandrel die | Die exit temperature | 200–210 °C |
| Sheet extrusion | 90 mm extruder, L/D 30:1 | Chill roll temperature | 75–95 °C |
| Pressure forming | In-line plug assist station | Sheet surface before forming | 155–165 °C |
| Post-mould cooling | Shuttle mould | Mould dwell | 8–12 s |
Where monolayer automotive windshield washer fluid and aftermarket coolant bottles are run on rotary wheel blow moulding machines, HDPE 5421B is processed at melt temperatures of 195–210 °C with a 60 mm extruder and 24:1 L/D barrier screw feeding 6–10 stations. A wall thickness of 0.8–1.0 mm is used for 500 mL–5 L containers, and the low-temperature drop test is performed according to ASTM D2463-15 after filled bottles are conditioned at -20 °C for 24 h; failure is characterised by brittle splitting at the pinch-off or the neck support ring rather than panel bending. Chemical resistance is validated by ASTM D543-21 immersion in methanol-water 50:50 and in propylene glycol-water 50:50 at 23 °C for 7 days, with mass change above 1.0 % or visible whitening in the panel triggering a molecular-weight or additive-package review. Torque retention on tamper-evident closures is checked after four weeks at 40 °C using the application torque range specified by the closure supplier, because polyethylene stress relaxation reduces removal torque by 15–30 % in the first 14 days. The bottles are not suitable for DOT brake fluid, methyl ethyl ketone, or aromatic solvent concentrates; these fluids require barrier structures or alternative inner-layer resins. Post-mould cooling on rotary wheels is set at 8–12 s at 25 °C to prevent panel deformation in 250 g coolant bottles, and the use of antistatic masterbatch is rejected where washer fluid contains methanol because amine-based antistats accelerate environmental stress crack growth under ASTM D1693-15 Condition B exposure.
Qualifying HDPE 5421B for Personal Care Bottles with High ESCR Demand
Physical property screening for 200 mL–1 L personal care bottles uses ASTM D1693-15 Condition B in 10 % Igepal CO-630 at 50 °C as the primary release criterion, because shampoo and body wash formulations contain linear alkylbenzene sulfonates and fatty alcohol ethoxylates that are aggressive stress-cracking agents. Bottles are blow moulded on shuttle machines with 48-cavity moulds at a melt temperature of 190–205 °C, and post-mould cooling is held inside the mould for 8–12 s to avoid wall collapse in 45 g bottle designs. The target wall thickness is 0.5–0.9 mm, and the neck finish is calibrated with a blow pin at 0.4 MPa to maintain dimensional stability for pump closures. Cosmetic packaging is not evaluated as a food-contact application; HDPE 5421B is selected for opaque shampoo, conditioner, and body wash bottles where supplier documentation confirms compliance with the applicable EU Cosmetic Products Regulation for the formulated product and the packaging does not require USP <661.1> testing. Surface gloss and print adhesion are controlled by limiting regrind to 25 wt% and by flaming or corona treatment at 38–42 mN/m wetting tension before silk-screen or heat-transfer labelling. Batches exhibiting undispersed pigment agglomerates above 0.2 mm are rejected before bottle manufacture because agglomerates create microvoids that shorten F50 time under ASTM D1693-15 Condition B.
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- CNOOC & Shell (CSPC Huizhou) HDPE 5421B is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
- COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales8@ascent-chem.com.
CNOOC & Shell (CSPC Huizhou) HDPE 5421B is a bimodal high-density polyethylene blow-moulding resin produced at the Huizhou petrochemical complex. The grade is specified with a density of 0.955 g/cm³ when tested to ISO 1183-1 and a melt mass-flow rate at 190 °C/21.6 kg of 5.0 g/10 min when tested to ISO 1133-1:2022. The bimodal molecular weight distribution separates the material from conventional unimodal HDPE blow-moulding grades: a low-molecular-weight fraction maintains extrusion throughput in accumulator-head machines, while a high-molecular-weight tail increases melt strength and environmental stress crack resistance. Primary applications are blow-moulded industrial containers, 20-L to 200-L jerrycans and drums, intermediate bulk container liners, and heavy-duty packaging where drop-impact and top-load specifications must be met. Differences from lower-density packaging HDPE appear mainly in parison sag control, top-load capacity, and permeation resistance to nonpolar liquids.
Production-scale processing on a shuttle blow-moulding line with a 30:1 L/D grooved-barrel extruder and 120 mm screw diameter is typically conducted with die temperatures from 190 °C to 210 °C. At the 190 °C lower bound, intermittent extrusion may produce melt-pressure oscillations above 25 MPa and sharkskin on the parison surface. At the 210 °C upper bound, parison sag increases and sidewall thickness control in a 200-L drum becomes dependent on accumulator drop speed and mould closing speed. Mandrel-to-die gaps are normally set between 1.5 mm and 3.0 mm, with mould temperatures from 10 °C to 30 °C. These settings are not unique to 5421B, but the melt-pressure stability at low screw speed is the main processing difference when downgauging from a lower-density HDPE grade.
What Limits Parison Sag in 5421B During Intermittent Extrusion?
Parison sag is governed by extensional viscosity, density, and the residence time under gravity. In capillary rheometry performed to ISO 11443 at 190 °C, 5421B exhibits pronounced shear thinning: apparent viscosity decreases by approximately one order of magnitude when shear rate increases from 10 s⁻¹ to 1000 s⁻¹. The extensional stress growth measured on a uniaxial extensional rheometer is dominated by the high-molecular-weight tail of the bimodal distribution, which retards strain-hardening loss during the 15–30 s hang times used for 60-L to 200-L containers. In contrast, a unimodal HDPE with the same 21.6-kg melt flow rate but narrower molecular weight distribution commonly shows lower extensional viscosity at Hencky strain rates above 0.1 s⁻¹; this permits sag and uneven wall thickness.
The processing window is constrained by two transitions. At low temperatures, the high-molecular-weight fraction does not fully relax after the accumulator shot, producing melt-pressure spikes and surface melt fracture. At high temperatures, thermo-oxidative chain scission reduces the high-molecular-weight fraction, lowering melt strength and increasing notched impact loss after moulding. On a shuttle machine with 25:1 to 30:1 L/D barrier screws, the practical melt-temperature ceiling for prolonged residence times is 220 °C. Batch-to-batch variability in the 21.6-kg melt flow rate should be kept within the manufacturer’s specification, because a drift above 0.3 g/10 min can alter parison hang time by more than 10%.
Published rheological data for 5421B under production-scale accumulator-head shear history is limited; the shear rates in the die land can exceed 1000 s⁻¹, while extensional rates during parison sag are typically below 1 s⁻¹. Datasheet melt flow values therefore do not fully predict sag behaviour, and converter trials are required.
Mechanical, Thermal, and Environmental Stress Crack Data
The table below summarises manufacturer-published typical values for 5421B determined on compression-moulded or injection-moulded specimens. These are not finished-part values, and converters must validate performance on the actual wall thickness and processing history.
| Property | Test method | Typical value | Unit |
|---|---|---|---|
| Melt mass-flow rate | ISO 1133-1:2022, condition T | 5.0 | g/10 min |
| Density | ISO 1183-1:2019 | 0.955 | g/cm³ |
| Tensile stress at yield | ISO 527-2:2012 | 27 | MPa |
| Elongation at break | ISO 527-2:2012 | >600 | % |
| Flexural modulus | ISO 178:2019 | 1250 | MPa |
| Notched Izod impact strength at 23 °C | ISO 180/A:2019 | 15 | kJ/m² |
| Environmental stress crack resistance, F50, 100% Igepal, 50 °C | ASTM D1693-15 | >1000 | h |
| Vicat softening temperature, A50 | ISO 306:2022 | 127 | °C |
Environmental stress crack resistance in 5421B is controlled by tie-molecule concentration and lamellar thickness distribution. The bimodal comonomer incorporation places short-chain branches selectively in the high-molecular-weight fraction, increasing the probability of tie molecules between lamellae. This mechanism is distinct from increasing density alone, which raises stiffness but reduces ESCR by thickening lamellae and decreasing tie-molecule density. Data from ASTM D1693-15 at 50 °C in 100% Igepal show a clear F50 plateau above 1000 h for compression-moulded plaques, but the same test on blow-moulded sidewalls can show reduced F50 depending on cooling rate and frozen-in orientation. Slow cooling in thick drum walls increases crystallinity and can lower ESCR relative to the datasheet value; converters should anneal or validate article-level tests when stack-storage of chemical fillings is specified.
No migration assessment in a final article can be conducted on resin data alone; however, the grade is positioned for food-packaging use under U.S. FDA 21 CFR 177.1520 and European Food Contact Regulation (EU) No 10/2011 when final articles meet overall migration limits of 10 mg/dm² and applicable specific migration limits. Industrial packaging converters should verify REACH Regulation (EC) No 1907/2006 and RoHS Directive 2011/65/EU compliance at article level, because final additive packages, colourants, and processing aids may alter the regulatory status.
| Regulation or standard | Scope | Verification boundary |
|---|---|---|
| FDA 21 CFR 177.1520 | Olefin polymers for food contact | Finished article extraction testing required |
| EU Regulation (EU) No 10/2011 | Plastic food-contact materials | Overall migration limit 10 mg/dm²; article-level specific migration limits apply |
| REACH Regulation (EC) No 1907/2006 | Registration and SVHC documentation | Supply-chain documentation for imported articles required |
| RoHS Directive 2011/65/EU | Restricted substances in electrical and electronic equipment | Article-level testing if final part enters E/E scope |
Chemical compatibility is typical of high-density polyethylene: the material resists dilute acids, alkalis, and aqueous salt solutions, but is not recommended for prolonged service with strong oxidizing acids, aromatic hydrocarbons, or chlorinated solvents at elevated temperatures. Environmental stress crack resistance is specified by ASTM D1693-15 using 100% Igepal CO-630 at 50 °C; the published F50 value exceeds 1000 h for compression-moulded plaques. Published data for the same test on finished 200-L drum sidewalls is limited, so converters should perform article-level ESCR validation.
When 5421B Replaces Lower-Density HDPE in Rigid Industrial Packaging
Replacement of a 0.950 g/cm³ unimodal HDPE with 5421B raises density by approximately 0.005 g/cm³ and flexural modulus by approximately 15–20% when measured to ISO 178:2019. Top-load capacity of square 25-L jerrycans increases, but the higher stiffness reduces dart-drop energy absorption in cold-weather applications below -10 °C. Wall-thickness distribution must therefore be adjusted rather than relying on downgauging alone.
Permeation to aliphatic hydrocarbons and oxygen is slightly lower than a 0.950 g/cm³ resin due to the higher crystalline fraction, although HDPE remains unsuitable for aggressive solvent barrier without fluorination or multilayer construction. Blow moulders replacing a general-purpose grade should re-optimize parison programming: the parison swell of 5421B is typically larger at the same die gap, and the neck and pinch-off zones may require different cooling to avoid stress whitening.
Compared with HDPE film grades having a 21.6-kg melt flow rate below 2.0 g/10 min, 5421B has lower melt viscosity at extrusion shear rates and is better suited to accumulator-head processing. Compared with injection-moulding HDPE grades whose 2.16-kg melt flow rate is above 1.0 g/10 min, 5421B retains sufficient melt strength for vertical parison hang times exceeding 10 s. The grade is not designed for thin-wall injection moulding or for film with high dart-impact requirements; those applications require different molecular weight targets and additive packages.
Differences from other blow-moulding HDPE products in the same density class often involve the comonomer type and molecular weight distribution. 5421B uses a butene-based bimodal architecture according to the manufacturer’s technical description; this is distinct from hexene-based unimodal HDPE grades that may show higher toughness at equivalent density but are more sensitive to shear history in large accumulator heads. The choice between butene and hexene copolymers should be based on the ESCR specimen thickness, container capacity, and drop-test requirement rather than density alone.
On production lines, surface defects in 5421B are often traced to insufficient purging after processing a lower-viscosity polypropylene or an HDPE with different molecular weight distribution. Because 5421B contains a high-molecular-weight fraction, transitions require a viscosity-matched purge compound rather than increasing temperature alone. The use of recycled regrind from 200-L drums can reduce ESCR and increase gel content if the regrind contains degraded weld-line material; converters should control regrind addition to levels validated by drop testing at -10 °C according to the final packaging specification.
Moisture absorption in storage is not a major issue below 60% relative humidity. If sacks are opened in humid coastal environments, drying at 80 °C for 2–3 h is sufficient to avoid surface splay; vacuum drying is not required. The additive package is designed for moderate thermal stabilization during blow moulding, but residence times above 10 min at melt temperatures greater than 220 °C may produce discolouration and odour in the finished part.
Accumulator-head machines with FIFO design are preferred over continuous-extrusion wheel machines for 5421B because intermittent extrusion preserves the high-molecular-weight tail from excessive shear history. A 25:1 L/D barrier screw with a compression ratio between 1.5:1 and 2.0:1 and a screened breaker plate at 60/80/60 mesh reduces gels while maintaining throughput. The extruder temperature profile should be flat from feed throat to metering section, with a slight decrease at the die to increase melt strength. Uncontrolled screw temperature rise above 230 °C has been associated with gel formation from degraded material at the screw root.
The practical processing window for 5421B is narrower than for general-purpose blow-moulding HDPE. A melt-temperature range of 190 °C to 210 °C at the die is typical, but the allowable band narrows to ±5 °C when thin-wall 5-L containers are processed on high-speed shuttle machines because wall-thickness variation becomes the limiting defect. At the lower threshold, incomplete plastication of the high-molecular-weight fraction creates gel-like particles; at the upper threshold, parison draw-down and handle-wall thinning increase. Processors use closed-loop die temperature control and accumulator pressure monitoring rather than manual adjustments to hold the band.
Small-bottle blow-moulding grades often have a 2.16-kg melt flow rate from 0.25 g/10 min to 0.45 g/10 min and are optimized for continuous shuttle or wheel machines with low accumulators. 5421B is measured at 21.6 kg because its 2.16-kg value is below the reliable range of the test method; using the 2.16-kg value to compare with small-bottle grades is misleading. The grade is targeted at large-part blow moulding where accumulator drop speed, parison programming, and wall-thickness control dominate.
Finished drum production with 5421B is typically qualified by drop testing at -10 °C from 1.2 m onto a concrete surface, top-load testing at 23 °C to a deflection of 5 mm, and internal hydraulic pressure testing at 200 kPa for 30 min. These acceptance criteria are article-level and must be re-validated when regrind content or wall-thickness distribution changes.
