SABIC LLDPE 118L is a butene-based linear low-density polyethylene with an ISO 1133-1:2022 melt mass-flow rate of 1.0 g/10 min at 190 °C/2.16 kg and an ISO 1183-1:2019 density of 918 kg/m³.

For heavy-duty industrial liner production, the resin is dry-blended with a high-pressure LDPE of 0.3–0.7 g/10 min melt mass-flow rate at 15–25 wt% to moderate melt extensibility and stabilize the bubble against gauge banding on oscillating haul-off assemblies. A typical starting recipe for 150–200 µm shipping sacks contains 78 wt% SABIC LLDPE 118L, 20 wt% LDPE, and 2 wt% white or carbon black masterbatch. Processing is carried out on a single-screw extruder with a 30:1 L/D ratio, a barrier screw fitted with a Maddock mixing section, and a 60/100/60 mesh screen pack. Barrel temperature zones from feed to metering are 170–185 °C, 190–205 °C, and 205–215 °C, with the adaptor and die maintained at 210–220 °C. A die gap of 1.8–2.5 mm is used with a blow-up ratio of 2.5:1–3.2:1 and a frost line height of 5–8 die diameters. Melt fracture onset is monitored visually as line speed increases; the exact threshold varies with die geometry and melt temperature, and published data for this specific configuration is limited. Because the resin is non-hygroscopic, pre-drying is not required unless pellets have been stored under high-condensation conditions; surface condensation can be cleared with a 60 °C hopper dryer for 30 min.

Finished film is slit into tube or sheet form and converted into valve sacks, open-mouth liners, and 25 kg drum liners. Mechanical acceptance testing is performed according to ASTM D1709-22 for dart drop impact, ASTM D1922-09(2019) for Elmendorf tear, and ISO 527-3:2018 for tensile properties. When used as FIBC liners, the film is evaluated against the end-user certificate for ISO 21898:2004 or equivalent packing group requirements; the 118L fraction contributes low-temperature puncture resistance but does not alone ensure the sift-proofness of the outer woven fabric. Seal failure in 35–50 µm edge fold areas is the dominant rejection mode on continuous bag converters, so weld seam strength must be verified on the converting line.

What Stabilizer Loadings Permit Three-Season Greenhouse Exposure?

In three-layer greenhouse film coextrusion, SABIC LLDPE 118L is assigned to the central layer at 65–75 wt% of total formulation, with 15–25 wt% high-pressure LDPE and 5–10 wt% EVA containing 14–18% vinyl acetate. The EVA fraction improves the machine-direction tear balance and permits a more uniform surface distribution of anti-drip additives in the inner skin. UV durability is achieved with a hindered amine light stabilizer at 0.4–0.8 wt%, a benzophenone or hydroxyphenyl-triazine UV absorber at 0.2–0.4 wt%, and a phosphite/hindered phenol thermal stabilizer package at 0.15–0.25 wt%. Anti-drip agents based on polyglycerol esters are dosed at 1.0–1.5 wt% in the inside layer; infrared-retention fillers are added only where the cultivation programme specifies reduced night-time heat loss, and the resulting PAR transmission is verified by ISO 13468-1:2019 while haze is measured by ASTM D1003-21.

Extrusion uses a three-layer blown film die of 200–350 mm diameter, a blow-up ratio of 2.2:1–2.8:1, and internal bubble cooling with a layflat width tolerance of ±3%. Melt temperatures in the 118L-rich core are maintained at 195–215 °C; die temperatures above 220 °C can deactivate certain UV stabilizer systems and should be avoided unless the stabilizer supplier confirms volatility limits. Films exposed to sulfur fumigation or halogenated crop protection products require a chemical resistance check; the active stabilizer package must be selected for acidic decomposition products because not all HALS types retain performance in elemental sulfur-rich greenhouse atmospheres. Finished greenhouse film is tested under EN 13206:2017 and accelerated weathering per ISO 4892-2:2013. End products include three-season tunnel covers, low tunnels, and side-roll greenhouse curtains.

In vertical form-fill-seal lines for frozen food, a three-layer A/B/C film uses SABIC LLDPE 118L in the sealant layer at 30–40% of a 60–80 µm total structure. The sealant layer is blended with 10–20 wt% of a metallocene plastomer or very-low-density polyethylene with a density of 0.902 g/cm³ to lower seal initiation temperature to 85–95 °C while retaining low-temperature ductility. The outer layers are formulated with 20–30 wt% 118L and 70–80 wt% LDPE or HDPE depending on stiffness, printability, and coefficient of friction requirements. Extrusion is carried out on a 55–75 mm three-layer blown film line with 24:1–30:1 L/D screws, a die gap of 1.5–2.2 mm, a blow-up ratio of 2.0:1–2.8:1, and melt temperatures of 190–210 °C. The print skin is corona-treated to 38–42 mN/m according to ASTM D2578-17; the sealant side remains untreated to avoid blocking and to preserve seal strength. Puncture resistance at freezer temperatures is measured by ASTM D3420-21 at −18 °C, and tensile properties by ISO 527-3:2018.

Seal performance is evaluated on a laboratory heat sealer with 0.5 N/mm² jaw pressure, 0.5 s dwell, and a 5 mm flat jaw; hot-tack testing follows ASTM F1921-20. The butene-based linear fraction provides a seal plateau between 95 °C and 125 °C; above 130 °C the seal interface may shift into viscous flow, so faster form-fill-seal lines should lower jaw temperature rather than increase dwell to avoid edge thinning. Food contact compliance is not a resin-only property: the converter must review the SABIC product stewardship statement, the anti-fog or slip masterbatch, and the final structure under Regulation (EU) No 10/2011 and 21 CFR 177.1520 for olefin polymers. End products include frozen vegetable pouches, seafood bags, and ice-cream pillow packs.

When Vapour Control Sheeting Is Installed Below Concrete Slabs

For below-slab vapour control, the governing specification is ASTM E1745-17. Formulations for 150–300 µm film include 85–95 wt% SABIC LLDPE 118L, 5–15 wt% reprocessed polyethylene film of known density and melt index, and 2–3 wt% carbon black masterbatch for UV shielding during storage and installation. Blown film extrusion uses a 90–120 mm die, internal bubble cooling, and a segmented air ring with automatic gauge control; flat width is typically 1.5–3.0 m, with layflat variation held at ±4% or better. Barrel and die temperatures are set to achieve a melt temperature of 190–210 °C, and the die gap is 1.8–2.5 mm. Winding is performed on 76 mm cores with taper tension to prevent blocking and telescoping in 50–100 m roll lengths.

Class A, B, and C vapour retarder performance under ASTM E1745-17 is verified through tensile strength per ASTM D882-18, puncture resistance per ASTM D1709-22, and water vapor permeance per ASTM E96/E96M-22. A Class A retarder under this standard is specified at 0.1 perm or less; because 118L is a butene-based LLDPE, the verified permeance depends on thickness, draw-down ratio, and the quality of the recycled fraction. Sealing, overlap, and installation details follow ASTM D4397-16 for polyethylene sheeting. Operational boundary: the film is not a chemical-resistant membrane; contact with hydrocarbon-based form-release agents, solvents, or aggressive ground gases requires a barrier layer evaluation outside the scope of standard polyethylene sheeting. End products include under-slab vapour retarder, crawl-space ground cover, and temporary building enclosure film.

Avoiding Melt Fracture in Double-Bubble Collation Lines

When double-bubble collation shrink lines process SABIC LLDPE 118L, the formulation incorporates 20–40 wt% 118L into an LDPE-rich structure to raise Elmendorf tear and maintain shrink-force consistency. The primary tube is extruded at 190–205 °C through a 50–70 mm extruder with a 24:1–30:1 L/D and a die gap of 1.2–1.8 mm; the tube is quenched below 35 °C, reheated to 105–115 °C, and stretched in the machine direction 3.5:1–5.0:1 and transverse direction 3.0:1–4.5:1 in a double-bubble tower. Web handling requires air turners and adjustable spreader bars to avoid edge fold-over. The orientation window narrows when the 118L fraction exceeds 40 wt% because the linear butene chains increase melt elasticity; melt fracture appears as a regular chevron pattern on the second bubble and is managed by lowering draw rate or raising reheat zone temperature by 2–5 °C. Shrink measurements are performed after 120 °C immersion according to ASTM D2732-20; tear is measured per ASTM D1922-09(2019); haze is measured per ASTM D1003-21.

The addition of 118L alters the transverse direction shrink-force balance, so the air ring and secondary bubble blower settings are trimmed to maintain an MD/TD shrink ratio acceptable for the bottle pack geometry. At 30 wt% 118L, the film typically retains sufficient optical clarity for printed multipack sleeves; above 35 wt%, haze may rise and require evaluation under ASTM D1003-21. Food contact structures are assessed under Regulation (EU) No 10/2011 and 21 CFR 177.1520 with the final additive package. End products include 6×1.5 L water bottle collation packs, canned food tray overwrap, and carbonated soft drink multipacks. Operational limit: at 118L fractions above 40 wt%, transverse shrink force decreases and can create register drift on high-speed packaging lines; published data for this specific configuration is limited, so line trials are required.

Extruder Pressure Fluctuations and Post-Consumer Recycle Blends

In refuse sack extrusion with post-consumer recycle, the formulation contains 50–70 wt% SABIC LLDPE 118L, 20–40 wt% recycled polyethylene film scrap, and 0–10 wt% LDPE for bubble support. The recycled fraction is melt-filtered through a continuous screen changer with 120–200 µm aperture screens, because low-melt-index butene LLDPE combined with unpurified PCR can produce pressure excursions and elevated gel counts. Film thickness ranges from 40 µm for lightweight bin liners to 120 µm for wheelie-bin refuse sacks. Extrusion uses a 65–80 mm extruder with a 25:1–30:1 L/D, a die gap of 2.0–2.5 mm, a blow-up ratio of 2.8:1–3.5:1, and a melt temperature of 195–210 °C. Gauge variation is controlled by an internal bubble cooling system; modern lines hold layflat variation to ±5% or better on 800–1200 mm flat widths.

Finished sacks are tested according to EN 13592:2017 for household refuse sacks, with dart drop impact per ASTM D1709-22 and Elmendorf tear per ASTM D1922-09(2019). The 118L fraction maintains low-temperature dart impact for outdoor collection at −20 °C; the recycled fraction shifts rheology unpredictably if it contains degraded LDPE, so each lot is sampled for MFR under ISO 1133-1:2022 before blending. Operational boundary: PCR streams containing paper labels, adhesives, or nylon strapping should be melt-filtered to 80 µm or lower to avoid screen blockage; silicon-based anti-block masterbatch in the reclaimed film can reduce surface tension during corona treatment. End products include 35 L household refuse sacks, 120 L trash bags, and 240 L wheelie-bin liners.