Blown film lines converting SABIC LLDPE 6118NSF into 30–40 µm bakery and confectionery contact film typically run a 180–210 °C four-zone barrel profile, a screen pack of 60/80/100 mesh, and a 200–300 mm die with a 2.0–2.4 mm die gap. The resin, specified at 0.918 g/cm³ by ISO 1183-1:2019 and 1.0 g/10 min by ISO 1133-1:2022, produces a melt that requires careful bubble stabilisation at blow-up ratios from 2.5:1 to 3.0:1; frost line heights below 5–7 die diameters are maintained to prevent transverse-direction film wander and gauge bands outside ±5%. For contact with dry bakery goods at room temperature, the formulation base is normally 100 wt% or an 85:15 dry blend with LDPE of MFR 0.7 g/10 min to raise melt strength. When the base resin is supplied without a slip and antiblock package, converters meter 1–2 wt% of a 5% erucamide slip masterbatch and 2–3 wt% of a 20% silica antiblock masterbatch to reach a kinetic coefficient of friction of 0.15–0.30 after 48–72 h migration, measured under ASTM D1894-14. Compliance for food contact rests on FDA 21 CFR 177.1520(c) for the olefin polymer base and EU No 10/2011 overall migration below 10 mg/dm² in the intended food simulant; any slip, antiblock, or processing aid additive must be drawn from the positive list of EU No 10/2011 or a relevant national inventory. Without the metered additive package, film can exhibit blocking on the rewind and coefficient of friction values above 0.70, causing telescoping of slit rolls in horizontal form-fill-seal infeeds. Production-scale failures observed on this grade class include reel blocking in warehouses above 60% RH and gel formation when melt temperature exceeds 230 °C for more than 10 min in the die adapter.

In frozen-food packaging, 6118NSF is converted at 50–80 µm for IQF vegetable pouches and frozen meat bags by dry-blending 20–30 wt% metallocene LLDPE of density 0.918 g/cm³ and MFR 1.0 g/10 min. The line configuration is typically a 60 mm grooved-feed extruder with L/D 30:1, internal bubble cooling, and a 250–350 mm die with 2.0–2.2 mm die gap; melt temperature is held at 195–210 °C to limit oxidative gel formation while maintaining sufficient melt strength for a 2.0:1–2.5:1 blow-up ratio. Converter acceptance criteria commonly specify dart impact resistance above 120 g at -25 °C by ASTM D1709-16 and Elmendorf tear strength above 150 g in machine direction and 300 g in transverse direction by ASTM D1922-23. These values are not supplied as product guarantees; they are acceptance thresholds used on frozen-food packaging lines and must be verified on the specific film structure. Corona treatment of the inner surface to 38–42 mN/m is necessary for water-based inks and solventless lamination; higher treatment levels above 46 mN/m can increase fibrillation and degrade seal initiation by oxidising the polyethylene surface. For low-temperature sealing, the frozen bag is sealed at jaw temperatures of 120–140 °C, with seal strength measured by ASTM F2029-16. Published data for the specific 6118NSF/mLLDPE frozen-food laminate configuration is limited, but production records indicate that brittle failure is rare above -30 °C when the mLLDPE addition remains above 20 wt%. Substituting all mLLDPE with LDPE reduces dart impact and increases haze, which is not acceptable for see-through frozen vegetable bags.

What Limits Down-Gauging to 20 µm on High-Speed Form-Fill-Seal Lines?

Converter specifications for 20 µm dry-powder and snack bags running on vertical form-fill-seal machines frequently require a minimum dart impact of 90 g by ASTM D1709-16, transverse-direction Elmendorf tear of at least 200 g by ASTM D1922-23, and hot-tack strength of 6–8 N/15 mm at 120 °C by ASTM F1921-18, Method A. The melt properties of 6118NSF make 20 µm gauges achievable only when machine-direction drawdown is limited; at a blow-up ratio of 2.5:1 and die gap 2.0 mm, a high frost line above 8 die diameters creates a tear anisotropy above 2.0, so the frost line is normally held at 4–5 die diameters to preserve transverse-direction impact balance. Runability problems on high-speed form-fill-seal lines are dominated by seal-through contamination and low hot tack when the film dwell time is below 0.3 s; processors add 10–20 wt% LDPE to lower seal initiation and 10 wt% HDPE to stiffen the web, but HDPE addition above 10 wt% reduces dart impact below the 90 g threshold. Barrel temperatures are held to 180–205 °C, die temperature to 195–205 °C, and the die gap is opened to 2.2 mm only if bubble stability allows; opening the gap to reduce gel formation raises transverse-direction gauge variation in thin films and should be accompanied by die rotation or automatic air ring control. Film production records from vertical form-fill-seal converting show that batch-to-batch variation in dart impact can exceed ±15 g when recycled edge trim is blended above 15 wt%, so the regrind fraction is controlled and melt-filtered through a 100 mesh screen pack to prevent sealing-jaw contamination.

When 6118NSF Is Dry-Blended with HALS for Single-Season Agricultural Silage Film

With die gaps above 2.4 mm and blow-up ratios below 2.4:1, single-season silage film based on 6118NSF is extruded at 150–200 µm gauge with a carbon black-loaded outer ply and a white inner ply on three-layer coextrusion blown film equipment. The outer black layer typically contains 6–8 wt% carbon black masterbatch, 0.10–0.25 phr of a high-molecular-weight HALS, and 0.05–0.15 phr of a UV absorber; the white inner layer contains 5–7 wt% TiO₂ white masterbatch and the same HALS loading. Melt temperature is capped at 200–220 °C and residence time in the die and adapter is kept below 12 min, because HALS degradation accelerates above 230 °C and carbon black increases viscous heating. Equipment behaviour differs from unpigmented film lines: screw torque rises by 10–15%, melt pressure through a 300 mm die increases by 15–25 bar, and die-lip build-up from UV stabiliser migration can require cleaning every 24 h at high output. Acceptance testing for single-season silage film normally requires tensile elongation at break by ISO 527-3:2018 and weathering exposure by ISO 4892-2:2013; after 800 h xenon arc exposure at 60 W/m² in the 300–400 nm range, retained elongation above 50% is a common converter requirement. Uncontrolled moisture uptake by carbon black masterbatch above 60% RH can create microvoids and surface roughness in the black layer, so the masterbatch is predried at 60–70 °C for 2 h when storage humidity exceeds that limit. Published film-level retention data for 6118NSF with specific HALS packages is limited, and outdoor lifetime claims must be validated by real-time weathering in the target geographic region rather than by accelerated testing alone.

Heavy-Duty Industrial Sack Coextrusion and Extruder Torque Constraints

During coextrusion of 80–150 µm heavy-duty sacks for resin pellets, fertiliser, and construction aggregate, 6118NSF is placed in the skin layers as a 60:20:20 blend with LDPE and HDPE, while the core uses 40 wt% 6118NSF and 60 wt% HDPE of density 0.952 g/cm³ and MFR 0.5 g/10 min. The main core extruder is normally a 90 mm grooved-feed machine with L/D 30:1, a barrier screw with dispersive mixing head, and a 400 mm die with 2.0–2.4 mm die gap; the bubble is stabilised with internal bubble cooling and a calibrating basket at BUR 2.0:1–2.5:1. Core melt temperature is maintained at 205–220 °C, and the pressure before the screen changer can reach 280–350 bar when the HDPE fraction exceeds 60 wt%. Batch-to-batch torque variation on the core extruder is a known processing bottleneck; a reversal of the first barrel zone to 170 °C and a water-cooled feed throat are used to maintain solids conveying and prevent pellet slip in the grooved feed section. Converter specifications often require stacked finished sacks to survive the ISO 7965-2:2013 drop test at 1.2 m with filled mass of 25 kg, plus minimum dart impact of 150 g by ASTM D1709-16 and minimum transverse-direction Elmendorf tear of 350 g by ASTM D1922-23. If skin layers contain no slip masterbatch, the surface coefficient of friction can exceed 0.65 and palletised sacks may slide during stretch-hood wrapping; converters add 1.0–1.5 wt% of a 5% erucamide slip masterbatch to the outer skin only to avoid seal compromise in the core. Processing limitations include the incompatibility of excessively high core HDPE content above 70 wt% with the tear threshold, and the need to keep the die-lip purge cycle below 8 h when running at maximum output to prevent oxidised melt deposits.

Slitting and converting a 25–40 µm sealant web made from a 70:30 blend of 6118NSF and LDPE for printed snack laminates begins after the roll has cooled for 24 h to allow shrinkage relaxation; this prevents edge curl and blocking in the sealant layer. The blown film is produced with a 2.0 mm die gap, BUR 2.5:1, and melt temperature 190–205 °C on a 45 mm extruder with L/D 28:1. The LDPE fraction is lower melt index than 6118NSF, usually 0.7 g/10 min by ISO 1133-1:2022, and lowers seal initiation while reducing dart impact slightly. A converter-mandated seal strength of 8–12 N/15 mm is measured by ASTM F2029-16 at 120–140 °C jaw temperature and 0.5 s dwell with 0.5 MPa jaw pressure. Hot-tack values by ASTM F1921-18 must remain above 5 N/15 mm for high-speed vertical pouch machines; adding mLLDPE at 10–20 wt% improves hot tack but reduces clarity and raises cost, so the blend is tuned per printing line. Surface treatment of the outer adhesive-receiving side is set to 38–42 mN/m for solventless adhesive coat weights of 2.0–2.5 g/m²; treatment below 36 mN/m causes laminating voids, while treatment above 46 mN/m can produce surface oxidation that interferes with heat seal strength after 7 days. The finished three-layer laminate normally comprises a 12 µm polyester print web, printed image, adhesive, and the 6118NSF-based sealant web; end-use products include flow-wrap snack pouches, sachet lamination, and lightweight replaceable bag-in-box films. The operational boundary for this structure is the low stiffness of the sealant web below 25 µm, which increases web flutter in high-speed slitters above 400 m/min unless 10 wt% HDPE is added to raise secant modulus.