Cast film extrusion of LL4800N, a butene-based linear low-density polyethylene copolymer with nominal melt flow rate 4.8 g/10 min under ISO 1133-1:2022 and nominal density 0.918 g/cm³, is most demanding in pallet unitisation operations where rotating ring wrappers apply pre-stretch ratios between 200% and 300%. The resin is loaded as the base polyethylene fraction at 95–98 wt%, with a combined polyisobutylene cling masterbatch and slip/antiblock package totalling 2–5 wt%; the cling masterbatch is typically a 10 wt% PIB concentrate in an LLDPE carrier and is allocated to the skin layer only, not the core layer, so that roll unwind force remains stable after two weeks of roll storage. Regulatory and normative anchors for this non-food film are primarily ASTM D5458-95(2020) for cling force, ASTM D5459-18 for machine-direction elastic recovery, permanent deformation, and stress retention under stretch-wrap conditions, ASTM D5748-19 for puncture resistance, and REACH verification for tackifier and processing-aid substances. The cast-film line uses a 90 mm single-screw extruder with a 30:1 L/D barrier screw, a coat hanger die at 0.6 mm die gap, and a melt temperature held at 240–255°C; the air gap between die exit and primary chill roll is maintained below 25 mm to limit neck-in, while the chill roll runs at 18–24°C and an air knife or electrostatic pinning device prevents the web from lifting above 300 m/min. At line speeds above 400 m/min, edge bead and melt resonance become the main process limits, and operators suppress them by locally increasing die lip temperature or adjusting die lip gaps over the outer 50 mm rather than by raising the entire melt temperature. Terminal roll stock is slit into 300 mm hand rolls of approximately 2 kg, 500 mm machine rolls of 12–20 kg, and pre-stretched cores at 15–17 µm for long-haul palletising.

What Physical Limitations Appear When LL4800N Functions as a Food-Contact Sealant Web?

In a three-layer cast coextrusion structure, LL4800N is positioned as the sealant skin at 70–85 wt% of the sealant layer, with 15–30 wt% of an ethylene-vinyl acetate copolymer or plastomer to reduce seal initiation and improve hot-tack across contaminated seal areas; the core layer may contain LL4800N at 100 wt% or blended with 10–20 wt% LDPE to protect against roll blocking. Food-contact compliance is governed by FDA 21 CFR 177.1520(c) for olefin polymers and by EU Regulation 10/2011 as amended by 2020/1245, with overall migration below 10 mg/dm² verified on the finished laminate rather than on the pellet; additive-specific migration from the EVA or plastomer layer must be checked under Annex II of EU Regulation 10/2011, and the processor must maintain documentation under Regulation (EC) No 2023/2006 on good manufacturing practice. The downstream process begins with a 1.0 mm die gap cast coextrusion line, melt temperature 230–245°C, primary chill roll at 15–20°C, and film gauge between 20 µm and 60 µm; the sealant skin is corona-treated to 40–44 mN/m before being laminated to BOPP or PET through solventless adhesive, and the finished reel is conditioned for 48 h at 23°C before slitting to allow additive migration and crystallinity to stabilise. A documented limitation is that LL4800N does not supply oxygen barrier function, so gas-flush or extended shelf-life packages require a barrier core or coating; published data for exact hot-tack values of LL4800N in this specific coextruded sealant configuration is limited, and converters therefore validate seal strength on their own line according to ASTM F88/F88M rather than relying on resin-level data. Terminal products include form-fill-seal pillow pouches for leafy greens, flow-wrap bakery overwrap, and non-barrier lidding film for fresh produce trays.

Agricultural Silage Wrap, Oxygen Transmission, and UV Stabilizer Loading

For baled forage conservation, LL4800N is used in monolayer or three-layer cast silage wrap at 30–50 µm thickness, with the resin loaded at 95–99 wt%; the remaining 1–5 wt% is split between a HALS/UV stabilizer masterbatch at 0.2–0.6 wt% and a white, black, or tinted pigment concentrate at 1–4 wt% depending on layer position and regional UV exposure. Compliance for this application is anchored to EN 13207:2018 for thermoplastic silage films used in agriculture, with additional verification under REACH for stabilizer substances and ISO 527-3:2018 for tensile properties on cast film. The cast-film process uses a die gap of 0.7 mm and a melt temperature of 240°C ±5°C, with the primary chill roll at 20–25°C to establish a smooth outer surface; the film is wound with a controlled taper between 10% and 30% tension reduction from core to outer layers to prevent blocking in storage. During bale wrapping, the film is applied at 55–70% pre-stretch, but the material does not perform as an oxygen barrier; its silage preservation function relies on physical exclusion of air and maintaining at least four film layers over the bale. Terminal products include round bale wrap, clamp silage cover film, and stack-cover sheets, with maximum service life determined by the stabilizer package rather than by the LLDPE backbone.

Where FIBC and octabin liners require a cast web with high dart impact and low gel count, LL4800N is run at 100 wt% or at 85–95 wt% with a fractional-melt LDPE added only when back-to-back film contact produces unwind blocking on two-drum winders. The compliance set for industrial liner film includes ASTM D1709-16a for dart drop impact, ASTM D882-18 and ISO 527-3:2018 for tensile properties, and ASTM D1922 for tear resistance; REACH documentation is maintained for the base resin and slip or processing stabilizers. The cast line operates at 50–125 µm gauge, die gap 0.8–1.2 mm, melt temperature 230–250°C, and chill roll temperature 20–25°C; in-line edge trim is ground, pelletized, and returned to the feed at up to 15 wt% without measurable loss in film appearance. Terminal products include octabin liners, FIBC liners for hygroscopic powders, drum liners, and long-length container liners for dry bulk.

When Cast Film Must Balance Peel Adhesion and UV Exposure

A coextruded surface protection film made with LL4800N in the carrier web is built as a two-layer or three-layer structure in which the backing layer contains 75–90 wt% LL4800N and 10–25 wt% LDPE for stiffness and melt strength, while the adhesive layer is an EVA or POE copolymer at 10–20 wt% of total film thickness; the exact blend is shifted by application because peel adhesion must remain below the maximum specified by the surface owner, and removal is verified after ageing. Normative references include ASTM D3330/D3330M for peel adhesion at 180° angle and 300 mm/min crosshead speed, ISO 527-3:2018 for tensile behaviour, and ASTM G154 for UV-aged film removal; REACH and RoHS documentation applies when the film is used on appliance or building-product surfaces entering the EU market. The cast line is run with a 0.5 mm die gap, melt temperature 235°C, and a matte-finish chill roll at 18–22°C; the film is aged at ambient temperature for at least 72 h before slitting, because peel adhesion increases during crystallisation and the value measured immediately after winding is not representative of final performance. Terminal products include cast protection film for pre-coated aluminium coil, polished stainless steel sheet, glass panels, and PVC window-profile extrusion.

Stretch Hooder Film Mechanics in High-Speed Logistics

Stretch hooder lines operate with thicker cast film than pallet stretch film, typically 60–150 µm, because the hood must retain elasticity during vertical stretching and recovery over pallet corners. LL4800N is blended at 70–85 wt% with LDPE at 15–30 wt% to increase melt tension and reduce sag before the chill roll; no cling additive is required because stretch hooding uses the film's elastic recovery to clamp the load rather than self-adhesion. Compliance for this non-food industrial film is based on ISO 527-3:2018 for tensile properties, ASTM D882-18 for machine-direction and transverse-direction tensile behaviour, and REACH verification for processing stabilisers and masterbatch carriers. The cast line runs a die gap of 0.8–1.2 mm, melt temperature 240–250°C, primary chill roll at 20–25°C, and line speed controlled to 100–200 m/min; because of the high thickness, edge bead removal and tension-zone profiling on the winder become critical to avoid gauge bands and telescoped rolls. Terminal products include stretch hooder film for palletised construction materials, beverage pallets, appliance outer packaging, and airbag-cushioned logistics loads.