High-Density Polyethylene in Asian Film and Blow Moulding Supply Chains

High-density polyethylene (HDPE) grades supplied by Lotte Chemical and other Asian producers for film and blow moulding applications are not differentiated primarily by density or melt flow alone. Lotte and other Asian HDPE grades in film and blow markets are separated by molecular weight distribution, comonomer type, branching frequency, catalyst residue, and additive stabilisation. In blown film, representative Asian HDPE grades are specified at a melt index of 0.04 g/10 min to 0.50 g/10 min under ISO 1133-1:2022, condition 190 °C/2.16 kg, with polymer density from 0.947 g/cm³ to 0.961 g/cm³ under ISO 1183-1:2019. Lotte film grades and comparable South Korean, Chinese, Thai, and Malaysian resins commonly occupy the high-molecular-weight portion of this range because elevated melt strength is required to maintain bubble stability at low stalk heights. Extrusion blow moulding grades are formulated between 0.28 g/10 min and 0.45 g/10 min with density from 0.954 g/cm³ to 0.960 g/cm³ to provide low sag and adequate environmental stress crack resistance. Lotte Chemical produces HDPE at its Yeosu and Daesan sites in South Korea, with regional capacity in Malaysia through Lotte Chemical Titan, and competes with Sinopec, PetroChina, Hanwha TotalEnergies, LG Chem, PTT Global Chemical, and SCG Chemicals for converter qualifications in film and blow moulding accounts.

High-stalk film processing requires bimodal architecture and controlled comonomer sequencing

The high-stalk process used for Asian HDPE film, especially on converter lines targeting thin-gauge strength and low gel formation, operates with a stalk height of 6 to 8 die diameters and a blow-up ratio usually between 3.0 and 4.5. Resins supplied by Lotte Chemical and competing Korean producers such as Hanwha TotalEnergies and LG Chem rely on bimodal molecular weight distribution produced by cascade or dual-reactor polymerisation. The high-molecular-weight fraction contributes melt strength; the low-molecular-weight fraction depresses high-shear viscosity and improves extruder throughput. Published data for some specific Lotte film-grade configurations is limited in open literature, but comparable Asian bimodal film resins with a high-load melt index of 6 g/10 min to 10 g/10 min at 190 °C/21.6 kg show directionally improved secant modulus when comonomer addition is biased toward the high-molecular-weight chains. Film stiffness is commonly evaluated under ASTM D882, secant modulus at 1% strain, where measured values for 25 µm film typically fall between 700 MPa and 950 MPa in the machine direction depending on resin density and crystallinity.

Asian high-density film grades are also compared through dart drop impact resistance under ASTM D1709 Method A. Values for 12.5 µm to 25 µm film commonly range from 150 g to 600 g depending on density, comonomer type, and frost line height. Elmendorf tear values measured under ASTM D1922 are strongly anisotropic: machine-direction tear for high-stalk film is generally lower than transverse-direction tear, with supplier data often quoting MD values below 30 g for 25 µm film and TD values above 400 g. Lotte film grades designed for high stalk are generally processed at die gaps from 1.0 mm to 2.0 mm with melt temperatures between 190 °C and 220 °C. Operating the melt below 180 °C raises extruder discharge pressure and may produce melt fracture on conventional single-screw extruders with L/D ratios of 25:1 to 30:1. On a 450 mm spiral mandrel die, output rates for high-molecular-weight film grades typically range from 180 kg/h to 260 kg/h, but the upper limit depends on screw geometry, backpressure, and the resin’s zero-shear viscosity.

What limits extrusion blow moulding performance in the 0.954–0.960 g/cm³ band?

In extrusion blow moulding, Lotte’s blow moulding grade family and equivalent grades from Sinopec, PTT Global Chemical, and SCG Chemicals balance density, melt index, and environmental stress crack resistance. The upper density limit of 0.960 g/cm³ raises topload stiffness and moisture barrier, but it lowers ESCR and drop impact. The lower density limit near 0.954 g/cm³ improves stress crack resistance but reduces modulus. Comparative testing under ASTM D1693 Condition B using 100% Igepal CO-630 at 50 °C bath temperature is the most widely used acceptance criterion in Asian blow moulding specifications. F50 failure times above 100 h are typical for container grades below 0.957 g/cm³, while grades at 0.959 g/cm³ or higher may fall below this threshold if molecular weight distribution is narrow. Lotte and Korean suppliers often report ESCR by ISO 16770 full-notch creep test for jerrycan grades, but published direct comparisons are limited because test geometry and stress level are product-specific.

On accumulator-head machines, parison sag is governed by zero-shear viscosity and extensional hardening. A blow moulding grade with melt index 0.35 g/10 min and density 0.956 g/cm³ from Lotte or a Thai supplier exhibits die swell between 35% and 55% at shear rates representative of a 50 mm annular die gap of 1.0 mm to 1.5 mm. Parison length variation before mould closure is generally held below ±3 mm for containers of 20 L to 30 L. Failure to control parison sag leads to uneven wall thickness below 0.5 mm at chime corners, reducing topload strength under ASTM D2659. Published field data for some Lotte 5000-series blow moulding grades remains limited; converter validation typically involves capillary rheometry at 190 °C and a shear rate sweep from 100 s⁻¹ to 1000 s⁻¹. Batch-to-batch variation in melt viscosity for Asian blow moulding grades is often specified within ±0.03 g/10 min in melt index, but that window may still require accumulator-head timer or parison programmer adjustments when switching between Lotte, Chinese, and Southeast Asian suppliers.

When butene is replaced by 1-hexene in thin-gauge film formulations

Asian HDPE film grades are produced with either 1-butene or 1-hexene comonomer. 1-Hexene-based films generally exhibit higher dart impact and tear resistance at equivalent density. Lotte and competing Korean film grades often designate butene-based products for lower-cost retail bag applications, while 1-hexene grades are positioned for high-toughness liners and shipping sacks. The resin selection decision under identical melt index and density conditions is not symmetrical; substituting a 1-butene grade with a 1-hexene grade can improve ASTM D1709 dart impact by 20% to 40% at 0.948 g/cm³, but may increase tack and require adjustment of frost line height. Melt strength measured as elongational viscosity at 150 °C may differ by 10% to 25%, affecting bubble stability at stalk heights below 5 die diameters. The replacement also affects output: because shear viscosity is influenced by comonomer type, an extruder with a 90 mm barrier screw may require screw speed increases of 5 rpm to 15 rpm to maintain equivalent throughput.

Processors switching from butene to 1-hexene film grades should also observe gel formation rates, especially when running recycled edge trim or post-consumer reclaim. 1-Hexene copolymers generally have lower crystallinity at equal density, which reduces yield stress but improves puncture resistance. Tensile yield strength under ISO 527-2 for blown film in the 0.948 g/cm³ to 0.953 g/cm³ range is commonly reported from 22 MPa to 27 MPa. At the same time, the low-temperature brittleness temperature under ASTM D746 may shift by 5 °C to 10 °C in favour of 1-hexene grades. The choice of comonomer therefore affects both film mechanical properties and extrusion stability, and Asian converters frequently qualify a butene grade and a 1-hexene grade in parallel for separate end-use specifications.

Rheology and mould fill data for Lotte blow moulding grades in multi-cavity operations

Multi-cavity blow moulding lines running Lotte HDPE container grades require consistent shear viscosity across barrel heaters and accumulator heads. The following table summarises typical supplier-published property envelopes for Asian HDPE film and blow moulding classes. Values represent nominal ranges from manufacturer technical data, not unified production specifications.

Film and blow moulding grades from Lotte and other Asian producers are stabilised with hindered phenolic antioxidants and phosphite systems; the additive package influences colour and organoleptic properties under FDA 21 CFR 177.1520 for food-contact film applications. Blow moulding grades for agrochemical containers often require antistatic and UV stabilisation, with some Thai and Korean suppliers specifying xenon-arc weathering under ASTM D2565 at 2000 h, but exact stabiliser chemistry remains proprietary. Incompatibility with unsaturated oils and some amine-based colourants is documented for HDPE, and converters avoid sustained melt temperatures above 230 °C because oxidative degradation accelerates and gel formation increases. Pre-drying is required at relative humidity above 60% for talc-filled or post-consumer recyclate blends; natural virgin HDPE does not normally absorb moisture beyond 0.01% by weight under ambient conditions. These operational boundaries apply across Lotte film and blow grades as well as competing Asian HDPE grades when resin changes are validated on production-scale equipment. Published data for some specific Lotte configurations remains limited, making direct converter trials on the target extruder or accumulator-head machine the controlling qualification step.