Borealis LDPE NAV102 is assessed in five downstream extrusion-coating and extrusion-lamination environments. The resin is characterised by a melt mass-flow rate of 8.0 g/10 min at 190 °C/2.16 kg per ISO 1133-1:2022, and a density of 0.918 g/cm³ per ISO 1183-1:2019. The application scope is deliberately limited to established processes in which the resin is melt-extruded as a thin web and immediately combined with paper, board, aluminium foil, or oriented polymer film. Processing is performed on single-screw extruders with L/D 24:1–30:1 and barrier screws; grooved feed sections are not required but can stabilise output. NAV102 does not require pre-drying in dry warehousing, but granulate stored in unheated silos at relative humidity above 60% may accumulate surface condensation and should be pre-dried at 60–80 °C for 2 h to avoid steam-induced pinholes. The compliance anchors and process windows summarised below apply to all five scenarios unless more restrictive end-use rules are stated in the specific application block.

Which laminating step in liquid packaging board demands a low-neck-in LDPE coating layer?

In aseptic and gable-top liquid packaging board, NAV102 is applied directly to paperboard or to the aluminium foil barrier web rather than being processed as a separate film. The coating weight per side typically falls between 12 g/m² and 20 g/m² when the total board grammage is 300–400 g/m²; the LDPE layer therefore represents approximately 8–12 wt% of the finished laminate. In a four-layer brick pack, the balance of the structure is composed of bleached or unbleached board, aluminium foil at 6.35 µm where barrier is specified, and a tie or inner coating layer. The resin is normally run as 100% NAV102 in each coating layer. Edge-trim reclaim may be returned to the extruder at up to 15 wt% after grinding and densification, but higher fractions can introduce gel particles that disturb the melt curtain and reduce heat-seal consistency.

Compliance is governed by EU 1935/2004, EC 2023/2006, EU 10/2011, and FDA 21 CFR 177.1520. Liquid packaging converters additionally audit the paperboard supplier's declaration of compliance under BRCGS Packaging Materials and verify that the finished carton meets overall migration limits under the intended hot-fill, cold-fill, or ambient distribution conditions. On the extrusion line, a single-screw extruder with L/D 24:1–30:1 feeds a coat-hanger die with an internal deckle width of 1200–2600 mm. Melt temperature at the die is held between 285 °C and 315 °C; at temperatures above 315 °C, oxidative chain scission can reduce drawdown and generate odour-active aldehydes that may be rejected by converters for direct food packaging. The air gap is set at 180–250 mm. Shorter gaps increase adhesion to paperboard, while longer gaps provide greater neck-in control. Line speed ranges from 250 m/min to 450 m/min for coating weights below 15 g/m².

Neck-in must be monitored continuously on this application because a deviation above ±5 mm from the substrate edge produces uncoated board zones and downstream side-seam or top-seal failure in the carton. Board reel moisture is maintained at 5–7% before the coating station; higher moisture reduces adhesion and creates steam-induced pinholes. When coating onto aluminium foil, ozone pre-treatment of the melt curtain is used at 0.5–1.5 mg/L to promote interfacial adhesion, and peel strength is generally required above 1.5 N/25 mm when tested as a T-peel adhesion on aluminium foil by ISO 11339. Terminal products include gable-top milk cartons, juice cartons, aseptic brick packages for dairy, beverage, and liquid food products, and portion-control cuplet stock.

Extrusion lamination of aluminium foil for heat-sealable sachet webs

Flexible packaging producers run NAV102 as the sealant layer against aluminium foil at coating weights from 15 g/m² to 25 g/m², corresponding to a nominal LDPE thickness of approximately 16–27 µm. In a three-layer or four-layer sachet structure, the LDPE layer typically represents 10–18 wt% of the final laminate, with aluminium foil at 7–9 µm and an outer printed BOPET or BOPP web. The process is extrusion lamination rather than extrusion coating: the melt curtain is introduced between the foil and a pre-printed polymer film in a nip formed by a counter-pressure roll and a water-cooled chrome chill roll. The chill roll surface temperature is held at 12–20 °C to limit post-crystallisation haze and to stabilise the sealed-surface gloss.

Compliance references for food sachet webs include EU 10/2011, EC 2023/2006, and FDA 21 CFR 177.1520. When the sachet content is a dry acidic powder or a fatty food, converters perform migration modelling on the LDPE layer using worst-case surface-to-volume ratios from the filled pack. Melt temperature at the die is typically 290–320 °C. At temperatures below 285 °C, adhesion to aluminium foil can fall below the required peel strength; above 320 °C, the resin may generate odour and surface defects due to oxidative degradation. Ozone treatment of the melt curtain is used at 0.5–1.5 mg/L to promote carbonyl formation at the foil interface. Edge trim from this process is reclaimed at up to 10–15 wt% after densification; higher reclaim fractions increase gel counts in the melt curtain and can cause web breaks above 200 m/min.

The NAV102 sealant layer has a seal initiation temperature of approximately 95–105 °C and reaches a plateau seal strength above 4 N/25 mm at 120–140 °C under a 0.3 MPa jaw pressure and 0.5 s dwell; the exact NAV102-specific seal initiation curve has limited published data, so converters validate the operating window on the finished sachet line using ASTM F88/F88M. Terminal products are single-serve sachets, stick packs, soup and spice pouches, powdered beverage sachets, and confectionery wrap stock. Packages with fatty or hygroscopic contents require a barrier check of the foil layer for pinholes after lamination because flexural cracking of the aluminium foil is the dominant field-failure mode.

In the conversion of bleached and unbleached kraft papers for frozen food wrapping, vacuum-packed meat board, and low-cost paper sacks, NAV102 is applied as a single-side extrusion coating at 12–25 g/m². The coating layer represents 10–20 wt% of the coated paper weight depending on whether the substrate is 40 g/m² or 80 g/m² kraft. The resin is normally used as 100% of the extrusion layer; silica anti-block or Erucamide slip masterbatch may be added by the converter at 0.5–1.5 wt% only when downstream reel blocking is observed. The governing compliance anchors are FDA 21 CFR 176.170 for paper and paperboard in contact with aqueous and fatty foods, EU 10/2011, EC 2023/2006, and BfR Recommendation XXXVI for paper-based food-contact materials.

The extrusion process operates with a paper pre-heat station to reduce surface moisture to 4–6% before coating. Melt temperature is maintained between 280 °C and 310 °C; line speed is usually limited to 200–400 m/min because faster lines increase coating-weight variation across the deckle. The die gap is set at 0.5–0.8 mm, and the air gap is reduced to 150–200 mm to improve adhesion to porous kraft. A matt chrome chill roll at 15–25 °C is used to produce a low-gloss surface that resists blocking during reel winding. Pinhole formation is monitored by a wetting solution or optical pinhole detector; coating weights below 12 g/m² on rough kraft exhibit a statistically higher pinhole count when the fibre roughness exceeds 3.0 µm Rz.

The finished coated paper is converted on form-fill-seal or bag-making machines. Seal strengths above 2.5 N/25 mm at 115–135 °C are typically needed for frozen-food bags to survive drop loading at -20 °C; this is a limitation of LDPE-based coated paper because low-temperature toughness is not the primary design function of NAV102. Terminal products include frozen vegetable inner liners, poly-coated butcher paper, paper sacks for hygroscopic powders, and layer pads for moist or chilled meat transit packaging.

When the sealant web is laminated directly to BOPET or BOPP in aluminium-free food lidding

For aluminium-free lidding films and transparent pouch structures, NAV102 is extruded as the middle tie layer between a reverse-printed BOPET or BOPP outer web and a coextruded or monolayer LDPE sealant film. The extrusion lamination coating weight is typically 10–15 g/m², which is 8–12 wt% of a final laminate consisting of 12 µm BOPET, 10–15 g/m² NAV102, and 30–50 µm sealant LDPE. The formulation is frequently run as 100% NAV102 in the tie layer. If the sealant film is omitted, the NAV102 layer itself can function as the heat-seal medium at thicknesses of 20–30 µm, but the sealing window narrows and hot-tack performance becomes the controlling variable on high-speed pouch machines.

Adhesion to BOPET or BOPP requires either ozone treatment or a primer-based adhesion promoter because LDPE alone shows limited functional-group reactivity with non-polar oriented films. Ozone is injected at the melt curtain at 0.5–1.5 mg/L; when adhesion to BOPET is specified above 2.0 N/25 mm, converters may apply a solvent-free polyurethane primer at 0.1–0.3 g/m² dry coat before the lamination nip. The extrusion line uses a melt temperature between 290 °C and 320 °C, chill roll temperature 15–25 °C, and line speed from 150 m/min to 350 m/min. Hot-tack strength is measured by ASTM F1921, and the lamination bond is measured by ISO 11339 or ASTM F88/F88M. Compliance is assessed under FDA 21 CFR 177.1520, EU 10/2011, and EC 2023/2006; since lidding films contact aqueous or fatty foods, specific migration modelling is required for the primer chemistry if one is used.

Terminal products are transparent pouch webs, lidding films for fresh-cut produce and dairy cups, and aluminium-free barrier laminates for dry snacks. The operational boundary of this application is set by the narrow hot-tack window when the NAV102 layer is used without an additional sealant film: dwell times below 0.3 s can reduce hot-tack below the level required to hold package gussets closed during filling, so production lines operating above 80 pouches/min should validate hot-tack under actual jaw temperature and dwell rather than relying only on static seal strength.

Paper cup and folded carton side-seam coating uses NAV102 at a coating grammage of 10–20 g/m² on one or both sides of the board, with the LDPE layer representing 5–12 wt% of the finished cup stock. The board is usually a polyethylene-coated bleached kraft or solid bleached sulphate at 180–280 g/m²; the LDPE coating creates the liquid barrier and the heat-sealable seam layer that is activated during cup forming. The compliance framework for hot beverage serving uses FDA 21 CFR 176.170, EU 10/2011, EC 2023/2006, and specific end-use testing for hot fill or hot contact under EU 10/2011 Article 17 temperature/time conditions. If the cup is used for liquid food above 70 °C, the converter must hold documented exposure testing at the upper-use temperature.

On the coating line, NAV102 is processed at 285–315 °C melt temperature and coated at speeds from 250 m/min to 400 m/min with an air gap of 180–250 mm. The side-seam heat-seal process in cup forming uses heated side-seam clamps at 120–180 °C and pressure dwells below 0.2 s; the seal must withstand hot water at 85–90 °C for at least 30 min without delamination. A production-scale bottleneck occurs when the extrusion coating weight varies by more than ±2 g/m² across the web, because the side-seam heat-seal window shifts and leakers increase at speeds above 150 cups/min. Unlike liquid packaging board, cup stock is frequently converted with two-side coating; the outer layer is required for condensation resistance and the inner layer for liquid resistance. The outer layer often contains a proportion of a higher-density polyethylene or a processing aid to reduce melt curtain sag, but NAV102 is generally used neat on the inner food-contact layer. Print adhesion on the outer LDPE side requires corona treatment above 40 mN/m or a water-based primer before flexographic printing. Terminal products include single-wall and double-wall paper cups, paper food tubs, soup containers, and folded paperboard cartons for ice cream and dairy desserts.