Lotte Chemical HDPE HIVOREX 5200B is a high-molecular-weight high-density polyethylene resin supplied in pellet form for extrusion blow moulding. The grade is differentiated by a low melt flow index, normally controlled below 0.50 g/10 min at 190°C and 2.16 kg according to ISO 1133-1:2022, and a base density within 0.952–0.958 g/cm³ determined under ISO 1183-1:2019. These properties place the material in the large-part blow moulding segment, where parison stability and environmental stress crack resistance dominate over injection cycle time. The grade is not designed as a high-flow injection moulding resin and is not supplied with a complete hydrostatic design basis for pressure pipe.

The property envelope above is compiled from general technical literature for high-molecular-weight HDPE blow moulding grades and should be replaced with the manufacturer’s lot-specific certificate of analysis before tool design or performance specification. Published values for this specific configuration may vary with comonomer type, molecular weight distribution, and sample preparation. The melt flow index and density are the critical incoming quality control parameters; a shift of more than 0.03 g/10 min in melt flow index or 0.002 g/cm³ in density across lots can alter parison sag and container wall thickness distribution.

What Limits Parison Stability and Screw Output at Low Melt Flow?

In extrusion blow moulding, parison sag is governed by zero-shear viscosity and molecular weight distribution. HIVOREX 5200B maintains a low melt flow index, which increases melt strength and reduces parison drawdown, but the same characteristic raises screw torque and melt temperature. On a single-screw extruder with L/D 24:1 to 30:1 and a barrier screw geometry, the recommended barrel temperature profile is 180–205°C from feed throat to metering zone. Die head temperatures are normally set at 190–200°C to avoid melt fracture; die swell tends to increase with lower melt temperature and can be managed through die gap programming. When melt temperature exceeds 210°C for prolonged residence, parison drawdown increases and drop impact performance may shift. Weight consistency on shuttle machines with 120–160 kN clamp force for containers up to 30 L is typically maintained below ±1.5% by closed-loop parison length control and accumulator discharge position.

Surface moisture deserves attention when granules are stored at relative humidity above 60%. Although high-density polyethylene does not absorb significant water, surface condensation can generate splay, pinholes, and weld-line weakness. A dry-air hopper with −20°C dew point and inlet air at 60–80°C for 1–2 h removes surface water. Screw speed above 80 min⁻¹ on a 60 mm diameter extruder can generate shear heating and reduce melt viscosity outside the intended processing window; therefore, output is often limited by melt temperature rather than available torque.

Rheological checks before startup are performed by capillary rheometry at 190°C and apparent shear rates from 10 s⁻¹ to 1,000 s⁻¹. In this range, the grade exhibits pseudoplastic behaviour; apparent viscosity may fall from roughly 10,000 Pa·s at 10 s⁻¹ to below 1,000 Pa·s at 1,000 s⁻¹, depending on molecular weight distribution. The power-law index is typically in the 0.35–0.45 range for high-molecular-weight HDPE at melt temperatures near 190°C. These measurements are used to set die gap and accumulator discharge profiles, because a steeper viscosity curve reduces die swell but also lowers melt strength at high shear. Capillary rheometry data for the specific lot should be obtained from the supplier or measured on a laboratory capillary rheometer before first production.

Large industrial containers are the primary conversion route for HIVOREX 5200B. The resin is blow moulded into jerry cans, tight-head drums, open-top pails, and automotive fluid reservoirs with capacities from 5 L to 200 L. Wall thickness is generally specified at 1.2–4.0 mm depending on UN dangerous goods packaging requirements. Cold impact resistance at −18°C is evaluated by drop tests such as ASTM D5276 or ISO 16495; the high molecular weight enhances pinch-off weld strength at the container parting line. On accumulator machines with 600–800 kN clamp force for 200 L drums, parison weight is commonly held at 8–12 kg and cycle time at 60–90 s, with die gap programming adjusted for wall thickness control. These operating figures are drawn from general blow moulding practice rather than a single grade-specific datasheet and must be validated by trial runs on the target machine.

Mould cooling time for thick-walled parts is dominated by the part thickness squared. For HDPE containers with nominal wall thickness 3.0 mm, cooling time may be 20–40 s at mould temperature 10–20°C; for 200 L drums with wall thickness up to 4.0 mm, cooling time commonly exceeds 60 s. Using chilled water at 8–12°C improves heat transfer and reduces cycle time, but excessively low mould temperatures can create frozen-in stress and increase warpage. The cooling circuit should be designed for Reynolds numbers above 10,000 in the mould channels to maintain turbulent flow and uniform heat removal.

Molecular Architecture Contrasts with Other HDPE Grades

Compared with injection moulding HIVOREX grades, 5200B has a markedly lower melt flow index and higher melt strength. Injection moulding HDPE grades are typically supplied at melt flow rates above 4.0 g/10 min to fill thin walls at high shear rates; 5200B is specified below 0.50 g/10 min, which makes injection moulding feeding inconsistent and increases moulded-in stress. Conversely, the low flow of 5200B supports long parison lengths and large die diameters during accumulator blow moulding. Compared with bimodal PE100 pipe grades, 5200B is primarily controlled for blow moulding performance, not for long-term hydrostatic strength under ISO 9080. Substitution into pressure pipe applications is therefore not recommended without a full pipe qualification programme covering hydrostatic strength, slow crack growth, and rapid crack propagation resistance under ISO 13479 and ISO 13477.

In terms of molecular structure, commercial grades of this type are produced with controlled comonomer incorporation to balance stiffness and ESCR. The density range of 0.952–0.958 g/cm³ indicates a moderate level of short-chain branching; higher density grades above 0.960 g/cm³ provide greater top-load strength but lower ESCR. Lower density film grades below 0.945 g/cm³ are unsuitable for blow moulding because they have lower melt strength and lower top-load capacity. The specific comonomer type and distribution are proprietary to the manufacturer and are not disclosed in typical grade datasheets.

When 5200B Sustains Contact with Aggressive Fluids and Weathering

Environmental stress crack resistance is a critical performance parameter for blow moulded containers holding surfactants, agricultural chemicals, and automotive fluids. ESCR is typically evaluated using bent-strip specimens under ASTM D1693-15 with 100% Igepal CO-630 at 50°C. High-molecular-weight blow moulding grades commonly exhibit F50 failure times above 600 h, but the exact lot value should be taken from the certificate of analysis. Moulded-in residual stress, pinch-off weld geometry, and cooling rate strongly influence crack propagation. Slow cooling in thick container walls increases crystallinity and lowers ESCR; mould temperatures are therefore kept below 30°C to limit spherulite size. For outdoor exposure, the base resin is not inherently UV-stabilised. A carbon black masterbatch addition of 2.0–2.5 wt% with particle size below 50 nm or a hindered amine light stabiliser package is required to maintain impact properties under ISO 4892-2 or ASTM D2565 weathering protocols.

Natural and pre-coloured forms may differ in processing behaviour. Carbon black masterbatch addition at 2.0–2.5 wt% increases melt viscosity slightly and may require 5–10°C higher die temperature to maintain surface finish. Colour concentrates based on incompatible carriers can reduce ESCR and pinch-off strength; therefore, carrier compatibility with HDPE should be verified using a small-scale bottle trial and ESCR testing on moulded parts.

For automotive under-hood fluids, long-term chemical resistance should be evaluated according to OEM specifications such as SAE J2260 or internal fuel resistance protocols. Published data for the specific HIVOREX 5200B configuration in these service fluids is limited; qualifications are typically performed on the moulded part rather than on resin compression moulded plaques.

For food-contact packaging, suitability under FDA 21 CFR 177.1520 and Regulation (EU) No 10/2011 must be confirmed through the supplier’s regulatory statement for the specific lot and conversion conditions. For dangerous goods packaging, the moulded container must meet the performance requirements of the UN Model Regulations and be certified by a competent authority; resin selection is only one element of that approval. The grade should not be used in direct contact with strong oxidising acids or halogenated solvents unless chemical resistance data have been generated on moulded parts at the intended service temperature.

On production lines, typical failure modes include parison curl, die lines, poor pinch-off weld strength, and melt fracture. Parison curl is often caused by non-uniform die temperature around the circumference; a die temperature variation of more than 5°C can create visible wall thickness asymmetry. Die lines are caused by scratches or polymer degradation in the die land; cleaning with a high-MI HDPE purge is standard. Poor pinch-off strength is linked to low melt temperature, inadequate clamp pressure, or excessive mould flash. These observations are reported from converting operations and are not grade-specific but highlight the practical constraints of low-melt-flow blow moulding.

Incoming inspection should prioritise melt flow index, density, and pellet size distribution. A single lot with a pellet size distribution shift can affect feeding stability on grooved-feed extruders. Moisture content is generally below 0.05 wt% by Karl Fischer titration, but surface condensation is checked separately. The certificate of analysis should report melt flow index, density, tensile yield stress, flexural modulus, notched impact, and ESCR. If the vendor does not report ESCR on every lot, a reduced testing frequency may be justified by process capability data. In extrusion blow moulding, the main operational boundary is the narrow melt temperature window. Overheating above 210°C or excessive residence time can reduce melt strength and generate gels. Conversely, processing below 180°C can produce melt fracture and high die swell. The resin should not be blended with low-viscosity HDPE or LLDPE at addition levels above 5–10 wt% without verifying parison sag and pinch-off weld strength on the target container. Lot-to-lot variation in melt flow index and density should be controlled by incoming inspection; otherwise wall thickness distribution may exceed the capability of the parison programmer. Published data for this specific configuration is limited in public literature, so process parameters should be established through design of experiments on the production line rather than extrapolated from standard HDPE grades.