Braskem LL218 is specified as a cast-film linear low density polyethylene grade with a nominal density of 0.918 g/cm³ and a melt flow rate of 1.0 g/10 min under ISO 1133-1:2022 at 190 °C and 2.16 kg. In pallet unitization stretch webs, the cast-film conversion is normally specified at a die gap of 0.6–1.0 mm, melt temperature 240–260 °C, and chill roll temperature 18–25 °C; a vacuum box or air knife is positioned 0.5–2 mm from the roll surface to force the melt curtain against the chill roll before the nip. At 100 phr of LL218, the melt blend typically contains a non-migratory cling additive at 0.5–2.0 wt%, synthetic silica or calcined kaolin antiblock at 0.05–0.25 wt%, and erucamide slip concentrate at 500–1,500 ppm. If a cast line runs above 500 m/min, fluoropolymer processing aid is added at 0.03–0.08 wt%; below this level, sharkskin melt fracture may appear as transcrystalline microtear along the die exit and cannot be corrected by raising the melt temperature alone. Film property compliance is evaluated by ASTM D5748-19 for puncture, ASTM D882-18 and ISO 527-3:2018 for tensile yield and break, ASTM D1894-14 for kinetic and static COF, and ASTM D1922-15 for Elmendorf tear in the transverse direction. The terminal web is converted into hand pallet wrap at 12–20 µm, machine wrap at 17–30 µm, and pre-stretched rolls where a 150–250% pre-stretch ratio is applied inline. Chill roll plate-out from migratory slip systems becomes visible as a whitish haze band at the web edges when chill roll temperature drops below 18 °C; production-scale converters routinely roughen the chill roll or add plate-out control masterbatch at 0.1–0.5 wt% to extend run time between roll cleanings.

What Limits Low-Odour Sealant Web Performance in Form-Fill-Seal Liquid Packaging?

In a coextruded form-fill-seal sealant web, Braskem LL218 is processed as the food-contact seal layer at 100 phr, combined with a low-migration slip/antiblock masterbatch at 1–2 wt%, while total erucamide content is constrained below 500 ppm to limit odour contribution in low-flavour dairy and liquid packaging. The cast coextrusion process ordinarily runs at a die temperature of 240–260 °C, a chill roll temperature of 30–35 °C, and a line speed of 120–250 m/min for structures where a polyamide or EVOH barrier layer is encapsulated with tie resin; corona treatment is maintained at 38–44 mN/m to ensure lamination or printing adhesion. Heat-seal performance is measured under ASTM F1921-18 for hot tack and ASTM F88/F88M-15 for seal strength on a finished 3-ply structure. Regulatory compliance for the sealant layer is evaluated against FDA 21 CFR 177.1520, EU Regulation (EU) No 10/2011 including overall migration below 10 mg/dm² under EN 1186-1:2002, EC 1935/2004, and Regulation (EU) No 2023/2006 for good manufacturing practice. Terminal converted items include liquid dairy pouches, bag-in-box liners for syrups and oils, and stand-up pouches for sauces and household chemicals; the sealant web is not recommended for retort conditions above 121 °C unless a high-temperature seal resin is substituted, because LL218 will begin to soften and lose seal integrity at the seal-jaw interface. Published data for this specific configuration is limited when the product is used in aseptic hydrogen peroxide sterilisation at concentrations above 35 %; qualification must include migration screening and peroxide residue analysis.

Agricultural Bale Wrap with UV Stabilizer Loading Limits and Pre-Stretch Recovery

Bale wrap and silage cover webs cast from LL218 are typically run as the cling surface layer in a three-layer construction, with the core and opposite skin formulated to carry oxygen-barrier or reflectance function where needed. At 100 phr of LL218 in the surface layer, stabiliser addition is limited to 0.2–0.5 wt% hindered amine light stabiliser, 0.1–0.3 wt% UV absorber, 0.5–1.5 wt% colour or white masterbatch, and 0.5–1.5 wt% cling additive; exceeding 0.8 wt% total UV additive in the surface layer can reduce cling uniformity and cause roll telescoping during winding. The cast line is configured with pre-stretch rollers operating at 50–70% elongation, melt temperature 235–255 °C, chill roll temperature 20–25 °C, and line speed 250–400 m/min; edge trim is reintroduced into the core layer at up to 10 wt%, but higher levels create gel accumulation at the die lip and reduce tear propagation resistance. Film mechanical and oxygen-barrier properties are not assigned solely to LL218; for silage wrapping where oxygen transmission below 100 cm³/m²·day·bar is required, a coextruded core of EVOH or polyamide must be inserted. Compliance for bale wrap is assessed according to EN 14932:2018, with tensile, tear, and UV ageing requirements specified by the end user; REACH compliance is required for all stabiliser chemistries. Finished products include 25 µm five-to-seven-layer round bale wraps, 30–40 µm silage pit covers, and oxygen-barrier variants for high-moisture chopped forage. Published data for this specific configuration is limited for long-term outdoor weathering beyond 12 months because UV additive loading, crop storage conditions, and wrap layer count interact with photodegradation in ways that cannot be predicted from single-layer accelerated aging alone.

For temporary masking of polycarbonate sheet, anodised aluminium, and brushed stainless steel during fabrication, a 50–80 µm cast LLDPE web is produced from LL218 as a three-layer coextrusion with a low-tack adhesive skin. The base formulation uses 100 phr LL218, a fluoropolymer processing aid at 0.03–0.08 phr, and a non-yellowing antioxidant masterbatch at 0.1–0.3 wt%; the adhesive surface is corona treated to 40–44 mN/m before off-line or in-line application of a pressure-sensitive adhesive at 5–15 g/m² coating weight. The cast film process runs with a textured chill roll or embossing roll at 18–22 °C, a die gap of 0.6–0.9 mm, and a melt temperature of 235–255 °C; lower chill roll temperatures are used to produce matte surface topography that reduces air entrapment under the applied film. Peel adhesion is measured on stainless steel after 24 h dwell according to ASTM D3330/D3330M-04, haze and clarity by ASTM D1003-13, and tensile properties by ISO 527-3:2018. The terminal products are cut into rolls of 1,050–2,100 mm width and supplied as temporary masking for laser cutting, bending, and transit. Adhesive compatibility with polycarbonate and coated aluminium must be validated by the converter because migration of low-molecular-weight processing aids from an unmodified LL218 surface can generate residues after 30–60 days of UV exposure; published data for this specific configuration is limited, so film-to-substrate trials with the actual adhesive and surface finish are mandatory. This is not a food-contact use, and no FDA 21 CFR or EU Regulation (EU) No 10/2011 compliance should be inferred unless the adhesive system itself is qualified separately.

When Cast LLDPE Replaces Blown Film in Air-Cushion Dunnage and Bulk Container Liners

The substitution of blown film with cast LL218 in air-cushion dunnage and flexible bulk-container liners is driven by gauge uniformity and seal initiation. At 100 phr LL218, the cast web typically incorporates regenerated clean edge trim into the core at 10–15 wt%, with a slip/antiblock masterbatch at 1–2 wt% to prevent blocking after winding at 60–100 µm. The production process uses a single-layer cast line with automatic thickness control, chill roll temperature 20–25 °C, melt temperature 230–250 °C, and inline corona treatment at 38–42 mN/m before heat sealing. Seal strength is assessed according to ASTM F88/F88M-15, tensile and elongation by ASTM D882-18 and ISO 527-3:2018, and dart impact by ASTM D1709-16. The converted webs are used as inflatable air cushions, dunnage bags for freight restraint, and liners for non-hazardous bulk granular and powder products in corrugated intermediate bulk containers. Because cast film has lower machine-direction tearing resistance than blown film at equal gauge, converters should not expect LL218 to pass the same edge-tear abuse tests without increasing film thickness by 10–20% or specifying a higher-alpha-olefin resin for the sealant layer.

For flexible liners inside FIBCs, steel drums, and corrugated boxes, LL218 is cast at 60–120 µm with an antistatic masterbatch added at 1–3 wt%, a slip/antiblock masterbatch at 0.5–1.5 wt%, and the balance LL218 at 100 phr. Surface resistivity is controlled to below 10¹¹ Ω/square at 12% relative humidity and 23 °C according to IEC 61340-5-1, while tensile and puncture properties are tested under ASTM D882-18 and ISO 527-3:2018. The cast film is produced with melt temperature 235–255 °C, chill roll temperature 18–22 °C, die gap 0.7–1.0 mm, and slit into panels for drum liners, FIBC liners, and corrugated box liners. The antistatic additive system is migratory; haze increases over 30 days of warehouse storage, and converters should condition slit rolls at 23 ± 1 °C and 50 ± 5% RH for 24 h before welding to stabilise surface resistivity. For packaging of combustible dusts, the final fabricated liner must additionally be assessed under IEC 60079-32-2 for electrostatic hazards, not solely by film surface resistivity.