DL Chemical HDPE DAELIM POLY HD5502FA is a high-density polyethylene extrusion grade supplied in pellet form and intended for thin-gauge film conversion. The resin is manufactured by DL Chemical Co., Ltd. under the DAELIM POLY product line. The HD prefix indicates the polyethylene architecture, while the suffix is used by the producer for film-grade stabilization and packaging nomenclature. In practice, the resin appears most frequently in high-stiffness blown film, cast film, and lamination web applications where melt strength, moisture barrier, and gauge control are used to manage the higher extruder backpressure associated with high-molecular-weight HDPE.

No single set of process parameters governs all conversion lines. The following sections describe the grade through its melt rheology, film bubble stability, heat-seal behaviour, regulatory exposure, and storage boundaries. The remarks are based on publicly available technical data sheet values and standard conversion practice; lot-specific certificates supersede all generic statements.

Melt Rheology and Screw Torque Response in a High-Viscosity Film Grade

The resin is characterized by a representative melt flow index of 0.35 g/10 min when tested under ASTM D1238 at 190 °C with a 2.16 kg load. This value places HD5502FA in the high-viscosity portion of the HDPE film range, below general-purpose extrusion grades that may report 0.7 g/10 min to 1.2 g/10 min. Corresponding solid-phase density is typically 0.955 g/cm³ by ASTM D1505, which is ordinary for a high-density film resin but higher than metallocene-enhanced HDPE grades designed for puncture-dominated service.

On a grooved-feed blown film extruder with 30:1 L/D screw, the melt flow index is not a direct predictor of torque; groove-barrel feed efficiency and screw geometry dominate. Processors routinely set barrel temperatures from 180 °C to 220 °C and hold adapter and die zones at 190 °C to 215 °C to avoid melt fracture at the die lip. Melt temperatures below 170 °C can produce unmelts and high-frequency gauge bands, while residence times above 240 °C for more than 10 min may initiate oxidative gel formation if the antioxidant package is depleted. Screw speed is frequently limited by extruder drive current before melt temperature becomes limiting, particularly on lines with 75 mm or smaller screw diameters.

Molecular weight distribution is relevant to backpressure and film surface quality. The grade is conventionally regarded as a Ziegler-Natta high-density polyethylene with a moderately broad distribution, giving it better melt strength than narrow-distribution metallocene grades but lower draw-down uniformity in very thin cast film. Gel permeation chromatography data are not always reported on commercial certificates; users seeking polydispersity values should request batch-specific technical service data from DL Chemical. The melt strength contribution of HD5502FA is most visible in bubble tension control, where a thicker molten stalk can be maintained without excessive sag.

Because HD5502FA has a density near 0.955 g/cm³, its moisture-barrier contribution in monolayer film is governed by crystallinity rather than by orientation alone. Water vapour transmission rate on 25 µm film is typically within the HDPE range of 4 g/m²/day to 6 g/m²/day when measured at 38 °C and 90 % RH by ASTM F1249; specific values are thickness- and anti-block-dependent. The same density yields a flexural stiffness suitable for cereal liners and produce bags, but the film is not intended for applications requiring high clarity or low-temperature impact equivalent to LLDPE-rich blends. In practice, processors run the resin as a core layer in coextruded structures to combine stiffness with sealant-layer toughness.

Hopper bridging is rarely observed in dry conditions. In warehouses with relative humidity above 60 %, surface moisture can produce screw feed fluctuations and melt pressure variation. Pre-drying in a desiccant-bed hopper dryer at 70 °C for 2 h is recommended only when condensation is visible or when film gauge variation exceeds ±5 % on a 25 µm target; blanket drying of hydrophobic HDPE is not necessary under normal indoor storage.

What Limits Bubble Stability in Monolayer Blown Film at Blow-Up Ratios Above 3:1?

Bubble stability in HD5502FA depends on the relationship between melt strength, die lip set-up, and cooling air. The resin tolerates blow-up ratios from 2.8:1 to 4.5:1, but at ratios above 3.5:1 the higher melt viscosity can reduce bubble oscillation if frost-line height is controlled between 6 and 9 die diameters. A high-stalk bubble geometry is preferred over a low-stalk pocket configuration because it stabilizes the molten web before crystallization. Die gap settings between 1.2 mm and 2.0 mm are common; narrower gaps increase shear rate at the lip and may require higher melt temperatures to avoid sharkskin.

In coextruded structures, the resin is placed in the core or stiffness layer. The higher molecular weight of HD5502FA relative to fractional-melt injection grades contributes to bubble tension and reduces draw resonance, but it also raises die pressure. On a 90 mm grooved-feed extruder with a 250 mm die, die pressures of 280 bar to 380 bar are within normal operating range, depending on die gap and output. Screen pack condition matters: pressure drops across a fouled 100/60/100/40 mesh pack can consume 30 bar to 60 bar and alter gauge control.

Amine-based processing additives should not be substituted into the formulation without supplier review because the residue may interact with the resin's stabilization package during high-temperature recycle. For colouring, a precompounded concentrate based on HDPE or LLDPE carrier is preferred over wax-heavy masterbatches, which can reduce bubble stability at addition levels above 3 wt%. Concentrate addition should be followed by a stable feed stream; inconsistent masterbatch dosing on a single-screw line with a 25:1 L/D screw can generate gauge banding that is mistaken for resin lot variation.

If Downstream Sealing Performance Is Critical, How Does the Grade Rank Against Other HDPE Film Resins?

HD5502FA is not a seal-initiation leader. Its high density and crystallization behaviour produce seal initiation temperatures that are generally 5 °C to 10 °C higher than LLDPE-rich sealants and roughly equivalent to conventional HDPE film grades. On a laboratory heat-seal unit operating at 0.3 MPa seal pressure and 0.5 s dwell, the resin typically requires jaw temperatures above 130 °C to reach measurable seal strength. Heat-seal strength is determined under ASTM F88; hot-tack performance under ASTM F1921 is lower than that of metallocene LLDPE, so converters using vertical form-fill-seal machines at speeds above 60 packs/min should evaluate hot-tack with the specific packaging film structure.

Compared with high-flow HDPE injection moulding grades, HD5502FA has substantially lower melt flow and higher environmental stress crack resistance. The environmental stress cracking resistance is commonly assessed by ASTM D1693 using 10 % Igepal at 50 °C; published values for HDPE film grades in this density range can exceed 300 h to 1000 h, though exact lot data should be confirmed. This ESCR behaviour differentiates the grade from low-molecular-weight HDPE grades that may fail within 50 h under the same condition in formulated detergent packaging.

Compared with metallocene-enhanced HDPE film grades, HD5502FA typically offers similar density and stiffness but lower dart impact at equal film thickness. The processing difference is also observable: the melt strength supports stable bubbles in thick-web HDPE sacks but limits the ultra-thin downgauging window below 12 µm. If puncture and dart performance are dominant, a coextruded LLDPE skin or a metallocene HDPE core may be required; the correct comparison should be made on fabricated film, not pellet data alone. The table below consolidates representative values for routine lot-release and film performance testing.

The matrix is not a certificate of analysis. Film mechanical values shift with film thickness, blow-up ratio, frost-line height, and masterbatch loading. For converter qualification, a film-based trial using the intended layer structure and target gauge is required before setting incoming inspection limits. The resin should be released against melt flow index and density only when film lines are stable and the converter has validated the relationship between resin lot data and finished film performance.

When extrusion coating replaces blown film lamination in packaging substrates, HD5502FA can be processed at melt temperatures from 260 °C to 300 °C. The resin's melt strength reduces neck-in relative to LDPE but does not eliminate it; edge bead and die width adjustment remain necessary. In monolayer extrusion coating on paperboard, the high density contributes to moisture resistance and abrasion resistance but limits fibre tear adhesion compared with LDPE. Adhesion is routinely checked with tape-peel tests based on ASTM D3359 or equivalent converter-specific protocols, and corona treatment of the HDPE surface is normally required above 38 mN/m as measured by ASTM D2578 for lamination.

Pre-drying is not generally required before extrusion coating unless the resin has been stored in an open silo at high humidity. The melt delivery system should avoid dead spots where residence time can exceed 15 min above 240 °C. In blown film recycle loops, edge trim and rejected rolls can be reintroduced at up to 20 wt% without unacceptable viscosity shift if the regrind is clean and sieved through a 4 mm screen; higher regrind levels may reduce bubble stability and increase gel count. If gel count rises, the first check should be screen pack condition and feed-throat temperature rather than resin melt flow.

Regulatory Boundaries Under Food-Contact and Heavy-Metal Leaching Standards

HD5502FA is supplied with certificates of analysis and regulatory statements according to the producer's product stewardship system. In food-contact evaluation, polyethylene grades of this density are commonly referenced against FDA 21 CFR § 177.1520 for olefin polymers, with the usual limitation that the food type and temperature use condition must be selected within the specified table. For the European Union, EU Regulation 10/2011 applies to plastic materials and articles intended to come into contact with food; specific migration limits are assessed according to EN 1186 migration methods and EN 13130 substance-specific methods. Overall migration for high-density polyethylene is generally not a limiting issue, but converters must verify the final article using the intended time and temperature conditions rather than relying on resin compliance alone.

For non-food industrial packaging, the resin is normally covered by REACH SVHC screening and the producer's safety data sheet. It is not formulated with heavy metal-based pigments or flame retardants, and lead, cadmium, mercury, and hexavalent chromium content is typically below the limits in IEC 62321 when tested on the finished colourless article. RoHS Directive 2011/65/EU applies only to electrical and electronic equipment and not to packaging, but many converters request a heavy-metal declaration for customer specifications; the declaration should be obtained from the producer for the specific lot.

Storage should be in original packaging, away from direct sunlight, at temperatures below 40 °C. Shelf life from the production date is commonly 12 months when stored in unopened bags; after opening, the resin should be consumed in a dry process area. The main incompatibility is prolonged melt exposure to oxygen at temperatures above 240 °C, which consumes the antioxidant package and can generate gel specks. If a line stoppage exceeds 20 min, the extruder should be purged with a lower-viscosity HDPE or LDPE at reduced temperature before restarting; do not use PVC or acetal purge compounds without confirming screw and barrel compatibility.

Lot-to-lot variance in melt flow index is typically controlled within ±0.05 g/10 min, but changes in anti-block or slip masterbatch can produce larger observable differences in film coefficient of friction than a resin lot shift. Coefficient of friction is measured by ASTM D1894 or ISO 8295, with film-to-film static values influenced by surface bloom. For high-speed packaging lines, coefficient of friction control is usually achieved by adding slip masterbatch at the hopper rather than by selecting HD5502FA alone. Published data for this specific configuration is limited when converter-specific slip packages, gauge profiles, and film structures are not disclosed; qualification trials remain the only reliable basis for setting production control limits.