Reliance LLDPE J24FS040 is a linear low-density polyethylene resin supplied by Reliance Industries Limited as translucent pellets. The grade is a butene-comonomer ethylene copolymer stabilized for repeated thermal processing in extrusion and injection moulding. The primary specification values are a melt mass-flow rate of 4.0 g/10 min when determined at 190°C under 2.16 kg load in accordance with ISO 1133-1:2022, and a density of 0.924 g/cm³ when measured by ISO 1183-1:2019. The resin occupies an intermediate rheological position within the producer’s LLDPE range. It is neither a heavy-duty blown-film resin with a melt mass-flow rate of 1.0 g/10 min nor a high-flow injection-moulding grade above 20 g/10 min. The flow-to-density balance positions the product for cast film, extrusion lamination, thin-wall injection moulding, and masterbatch carrier systems in which head pressure and cycle time are reduced without moving to a high-melt-flow grade that sacrifices low-temperature impact resistance.

Nominal property data are summarised below. The values are drawn from the producer’s technical literature and are typical, not specification limits; lot-specific values are reported on the certificate of analysis and may vary within standard test reproducibility.

What Limits Melt Temperature and Output Stability on Cast Film Lines?

In cast-film processing, the grade is run on single-screw extruders with screw length-to-diameter ratios of 24:1 to 30:1 and barrier or Maddock mixing sections. Barrel zone set points range from 180°C to 220°C, and melt temperature at the die exit is maintained below 240°C. Operation above 240°C accelerates oxidative degradation of the butene branches, raises the seal initiation temperature, and increases the probability of gel specks in thin film. The material does not require desiccant drying when stored below 60% relative humidity. If pellets are transferred from an unheated warehouse to a warm processing hall, condensation on pellet surfaces can occur; hopper drying at 60–70°C for 1–2 h is applied prior to extrusion.

Chill-roll temperature is maintained between 20°C and 35°C. When roll temperature exceeds 45°C, the low-density amorphous fraction remains tacky, increasing blocking tendency and haze. Die gap settings of 0.5–0.8 mm allow thin-gauge drawing with a 4.0 g/10 min melt; however, the lower extensional viscosity relative to a 1.0 g/10 min film grade increases neck-in and draw resonance at higher line speeds. Air-knife assistance at the die exit and an air gap below 150 mm are used on production lines to hold gauge uniformity within ±5%. When sharkskin melt fracture appears on a 0.5 mm die gap, the first corrective action is not an increase in screw speed; adaptor and die temperatures are raised by 5–10°C within the permitted upper limit, because the defect is governed by die exit shear stress.

For cast film at 50 µm thickness, seal initiation temperature and hot tack are evaluated using ASTM F1921 and ASTM F2029 rather than only ASTM D1709. The lower molecular weight fraction that produces the 4.0 g/10 min flow also reduces seal initiation temperature relative to a 1.0 g/10 min resin, but hot-tack strength may decline at line speeds above 150 m/min.

On blown film lines, the 4.0 g/10 min melt flow produces low bubble stability and a narrow air-ring window. The grade is not intended for heavy-gauge blown film above 100 µm; at that thickness, bubble oscillation and pinhole formation can occur unless the die is operated with a low stalk and blow-up ratio below 2.5:1. These limitations distinguish it from 1.0 g/10 min LLDPE film grades used for dunnage, agricultural film, and heavy-duty sacks.

When J24FS040 replaces a 1.0 g/10 min LLDPE in extrusion lamination, head pressure at constant screw speed decreases because of the higher melt mass-flow rate. The pressure reduction permits higher throughput on torque-limited extruders, but melt curtain stability is lower. Lines with air gaps above 150 mm may show edge neck-in greater than 10%, and the melt curtain may oscillate at line speeds above 150 m/min. Compensation on production equipment includes narrowing the die gap from 0.8 mm to 0.5 mm and shortening the air gap. Adhesion to primed substrates is governed by melt surface oxidation; die temperatures of 200–220°C are held for polypropylene and polyamide substrates, while higher temperatures improve wet-out but can degrade seal performance. Chill roll pressure and back-up roll hardness of 70–80 Shore A are used to consolidate the laminate without over-compressing the substrate.

Thin-Wall Injection Moulding Behaviour and Shrinkage Control

Thin-wall containers, caps, and closures moulded from J24FS040 are processed with barrel temperatures from 200°C to 230°C and mould temperatures between 15°C and 40°C. The lower mould temperature is used to shorten cycle time; higher mould temperature improves surface gloss but increases post-moulding shrinkage. Because the resin has a density of 0.924 g/cm³, its flexural modulus is lower than high-density polyethylene, and parts exhibit a Shore D hardness of approximately 55 when tested under ISO 868. Shrinkage after 24 h is typically 1.0–1.5% in the flow direction and 0.8–1.3% transverse to flow; the exact value depends on packing pressure, gate freeze time, and cooling layout. Published data for this specific configuration is limited, and a tool trial is required to establish the shrinkage map for multi-cavity tools.

For thin-wall containers with a projected area of 0.1 m², machines with clamp force of 800–1000 kN have been used, but the actual requirement depends on flow length, wall thickness, and gate design. The material can be processed on conventional general-purpose polyethylene screws with compression ratios of 2.5:1 to 3.5:1. Back pressure above 20 bar may shear-heat the melt and promote gate blush. In hot-runner manifolds, residence time at melt temperature above 230°C should not exceed 10 min to avoid generation of oxidised gel specks in transparent articles.

For thin-wall parts below 1.0 mm, gate diameter is set to 0.8–1.2 mm, and the gate should freeze after the packing stage to avoid sink marks. Multi-cavity tools with unbalanced runners show flow-front hesitation if the runner diameter is below 6 mm; this is more pronounced with a 4.0 g/10 min melt than with a 20 g/10 min grade because of higher viscosity.

In masterbatch carrier applications, the 4.0 g/10 min melt flow permits high loadings of carbon black, titanium dioxide, or slip/antiblock concentrates without excessive torque on twin-screw extruders with co-rotating screws of 40:1 length-to-diameter ratio. Set point temperatures of 160–190°C are typical; higher barrel temperatures reduce viscosity but increase additive migration and pellet-surface tack. Batch-to-batch variation in carrier density and melt flow should be monitored against the certificate of analysis, because a shift of ±0.001 g/cm³ in density alters the let-down ratio and the stiffness of the final article.

Regulatory conformity is end-use-specific. The base polyethylene is within the scope of FDA 21 CFR 177.1520 for olefin polymers when the finished article meets the extractive limitations applicable to the intended food-contact conditions. For European food-contact applications, compliance with Commission Regulation (EU) No 10/2011 requires specific migration testing under the intended food simulant, contact time, and temperature. The grade is manufactured to limits for heavy metals and phthalates required by REACH Annex XVII, but converters must verify that downstream additives, masterbatches, and processing aids do not shift the final article outside the applicable positive list. No statement in this document is a certification of food-contact suitability for a particular finished product; end-product compliance is validated under ISO 17025-accredited testing.

When J24FS040 Replaces a 1.0 g/10 min Grade in Lamination Lines

In lamination lines, the difference between J24FS040 and a 1.0 g/10 min LLDPE is not limited to viscosity. The 4.0 g/10 min melt also contains a larger fraction of low-molecular-weight chains that lower the melt strength and broaden the residence-time distribution in the die. On production lines, this is observed as greater neck-in, lower draw resonance resistance, and a narrower air-gap stability window. The advantage is a measurable reduction in head pressure and motor load at the same screw speed, which allows the higher-flow grade to be used on smaller extruders for the same laminate width.

Compared with a 1.0 g/10 min LLDPE, J24FS040 has lower dart impact and Elmendorf tear resistance in heavy film structures because butene branches produce a lower tie-molecule density than octene branches at equivalent density. Dart impact is measured by ASTM D1709, and Elmendorf tear by ASTM D1922. The grade is therefore selected for cast film and lamination where draw and adhesion control dominate over puncture resistance, rather than for heavy-duty sacks or agricultural film where 0.5 g/10 min or 1.0 g/10 min octene grades are technically preferable. When compared with high-flow injection-moulding LLDPE grades above 20 g/10 min, J24FS040 has lower melt flow and higher viscosity, which can require higher injection pressures but gives better environmental stress crack resistance under ASTM D1693.