On cast film lines configured with a 90 mm, 30:1 L/D barrier screw and a 2,500 mm-wide coat-hanger die equipped with automatic die bolt adjustment, Borealis Borstar® LE6027 is run as the core layer resin in a three-layer A/B/A pallet stretch film structure. The addition ratio of LE6027 in the core layer is maintained at 60–80 wt% of the total web, while the two skin layers are diluted with a C8-LLDPE or metallocene-catalysed plastomer at 10–20 wt% per layer to regulate cling and tear behaviour. Melt temperatures along the extruder profile are set between 180 °C and 260 °C, the die gap is adjusted to 0.5–0.8 mm, and the primary chill roll temperature is held at 18–24 °C to prevent blocking while preserving web flatness. On lines with a primary chill roll diameter of 750 mm and winding speeds above 500 m/min, the dominant process limitation becomes draw resonance and edge neck-in, which are managed by keeping the draw ratio below 30:1 and by setting the air gap between die lip and chill roll at 40–60 mm. Compliance for industrial pallet wrap in the European Union requires REACH Regulation 1907/2006 Article 33 SVHC disclosure; when the wrap is placed in direct contact with food packaging, the finished article is assessed under Regulation (EU) No 10/2011 using overall migration conditions in Annex III, with a limit of 10 mg/dm². Puncture resistance is verified under ASTM D5748 and cling under ASTM D5458; pre-stretched rolls are tested at a pre-stretch ratio of 2.0:1–2.5:1. Finished product types include hand stretch rolls from 300 mm to 500 mm width, machine-wrap rolls up to 500 mm width, and pre-stretched rolls for high-speed automated pallet wrappers. Moisture-induced pinholes are reported when ambient RH exceeds 60% at the hopper; below this threshold no pre-drying is required.

Why Does Blown Film Extrusion of LE6027 Require a Low Frost-Line Height for Dart Impact Retention?

The primary processing conflict in high-clarity blown film production is the inverse relationship between frost-line height and dart drop retention. When a monolayer or three-layer blown film line with a 120 mm die, 2.0 mm die gap, and blow-up ratio of 2.2:1–2.8:1 runs Borstar® LE6027 at 80–100 wt% in the polymer layer, raising the frost-line height above 1.2 m reduces dart drop measured per ASTM D1709 from approximately 150 g to below 110 g at 50 µm; the frost-line height is therefore kept between 0.8 m and 1.2 m unless additional mLLDPE is introduced at 10–20 wt% to recover impact. Melt temperature is bounded at 190–230 °C, with external air-ring cooling and a dual-lip air ring used to stabilise the bubble when the melt strength of the bimodal molecular weight distribution is deliberately reduced by higher melt temperatures. For food-contact bread bags and frozen food pouches, compliance is demonstrated under FDA 21 CFR 177.1520(c) 3.2a for olefin polymers and under Regulation (EU) No 10/2011 with an overall migration limit of 10 mg/dm²; slip and antiblock masterbatches are limited to 1–3 wt% because higher loadings create die lip buildup and visible haze in the finished film. Tensile properties are verified by ISO 527-3 and tear resistance by ISO 6383-2. Terminal product types include bread bags, frozen vegetable pouches, garment over-wrap, and paperboard window lamination.

Lamination webs containing 70–90 wt% Borestar® LE6027 in a sealant layer fail cohesively rather than adhesively when seal initiation temperature is driven below 105 °C, so EVA or mLLDPE is incorporated at 10–30 wt% to lower the heat-seal threshold without sacrificing hot tack. The sealant web is produced on a three-layer blown film line with a die gap of 1.2–1.6 mm, melt temperature of 190–225 °C, and blow-up ratio of 2.0:1–2.5:1; after edge trimming, the film is corona-treated to a surface energy of 38–42 mN/m measured by ISO 8296 and adhesive-laminated to oriented PET or biaxially oriented nylon under conditions specified by the adhesive supplier. For direct food contact in the European Union, the lamination is assessed under Regulation (EU) No 10/2011 with overall migration and specific migration of additives, using simulant A for aqueous foods and simulant D2 for fatty foods; in the United States, the sealant layer complies with 21 CFR 177.1520(c) 3.2a subject to end-testing of the adhesive under 21 CFR 175.105. Seal strength is verified by ASTM F2029 and hot tack by ASTM F1921; the addition of LE6027 above 90 wt% is not recommended where seal initiation below 95 °C is required, because the bimodal molecular weight distribution increases crystalline memory and delays sealing. Terminal product types include stand-up pouches, flow-wrap packaging for frozen confectionery, and inner sealant plies in high-speed horizontal form-fill-seal lines. Published data for this specific configuration of LE6027 in retortable pouches is limited; retort qualification must be performed on the final laminate structure, not on the monolayer film.

Greenhouse Cover Films: UV Stabiliser Masterbatch Dosage and the Bimodal MWD Bubble Stability Limit

At greenhouse film lines in temperate cropping regions, three-layer blown film equipment with a 160 mm die, 1.8 mm die gap, and blow-up ratio of 2.2:1–3.0:1 processes Borstar® LE6027 at 20–50 wt% in the core layer, with the balance split between LDPE and EVA to maintain bending stiffness and heat retention. The addition ratio of UV stabiliser masterbatch is 8–12 wt% of polymer mass, anti-drip masterbatch 1–2 wt%, and IR absorber 2–5 wt%; these loadings are let down through a gravimetric dosing unit because the bimodal molecular weight distribution of LE6027 reduces dispersion uniformity when concentrates are introduced at the screw feed section. Melt temperature is held at 190–230 °C to avoid thermal degradation of the HALS package, while the internal bubble cooling air temperature is kept below 35 °C to maintain cooling capacity. Compliance for greenhouse covers in the European Union is specified under EN 13206:2017 for thermoplastic films used in agricultural and horticultural applications, with accelerated weathering performed under ISO 4892-2 using UVA-340 lamps at 0.76 W/m² irradiance at 340 nm and black-standard temperature of 65 °C. Tensile retention after weathering is verified by ISO 527-3 and tear resistance by ISO 6383-2; amine-based UV stabilisers are avoided because they interact with the anti-drip concentrates and deposit plate-out on the collapsing frame. Finished product types include single-season tunnel covers, greenhouse side sheets, and silage stretch covers where the film is applied at a thickness of 150–200 µm.

When LE6027 Replaces a Conventional C4-LLDPE in Heavy-Duty Sack Extrusion, the Screw Design Becomes the Limiting Factor

The substitution of a conventional C4-LLDPE with Borstar® LE6027 in heavy-duty sack extrusion shifts the process bottleneck from bubble cooling to screw plastication. On a 75 mm, 25:1 L/D single-screw extruder running a 200 kg/h three-layer line, increasing LE6027 content in the core layer from 50 wt% to 80–100 wt% raises melt pressure from approximately 260 bar to 310 bar and increases motor load by 12–18%, requiring a screw with a longer compression section and no more than 5% melt temperature override above the set point. The die gap is set at 1.8–2.5 mm, the blow-up ratio at 2.5:1–3.5:1, and the melt temperature at 190–230 °C; bubble stability is maintained with a dual-lip air ring and an internal bubble cooling system when film thickness exceeds 120 µm. Compliance for heavy-duty sacks used in the construction and chemical sectors is verified by tensile testing under ISO 527-3, dart drop under ASTM D1709, and full-sack drop testing under ISO 7965-2; where the sack is intended for UN-certified dangerous goods, testing follows the UN Manual of Tests and Criteria Part III 21.2. Slip and antiblock masterbatches are limited to 0.5–2 wt% because higher loadings reduce sack-to-sack friction below the level required for safe palletised storage. Terminal product types include flexible intermediate bulk container liners, form-fill-seal heavy-duty sacks for granular chemicals, and construction rubble bags with thickness from 80 µm to 200 µm. Published data for this specific configuration of LE6027 in UN-certified sacks is limited; certification must be confirmed by drop testing on the final sack geometry and closure system.

If collation shrink film is coextruded with a skin layer containing 20–40 wt% Borestar® LE6027 and a core of LDPE, the film must retain a free shrink value measured under ASTM D2732 of at least 40% in the machine direction and 15% in the transverse direction at 135 °C while avoiding melt fracture at high die throughput. The blown film line uses a 1.4–1.8 mm die gap, a blow-up ratio of 3.0:1–4.0:1, and melt temperature of 185–215 °C; the addition of LE6027 above 40 wt% reduces ultimate shrink and increases haze, so the skin layer is capped with a low-density sealant resin to maintain shrink force. For beverage multipacks and canned goods overwrap, compliance is assessed under FDA 21 CFR 177.1520 for food-contact packaging and under Regulation (EU) No 10/2011 where the printed film is imported into the European Union; volatile organic compound residues from printing are controlled under REACH 1907/2006 Article 33 and applicable national packaging directives. Shrink tension is measured by ASTM D2838 and haze by ASTM D1003; the finished film is slit to 400–800 mm widths and supplied as centre-fold or single-wound rolls for shrink tunnels operating at 140–160 °C. Terminal product types include bottle multipack collation, canned goods overwrap, and light-duty distribution packaging where shrink force must not distort thin-wall PET bottles.