Borealis Stamylex™ 1046F is a linear low-density polyethylene film grade with a nominal density of 919 kg/m³ per ISO 1183-1 and a melt flow rate of 1.0 g/10 min at 190 °C/2.16 kg per ISO 1133-1:2022. In frozen IQF vegetable packaging, the grade is run in an A/B/A three-layer blown film structure where the core layer contains 60–70 wt% Stamylex 1046F and 30–40 wt% LDPE with an MFR of 0.25–0.5 g/10 min to increase melt integrity; each skin layer is blended at 50 wt% Stamylex 1046F with 50 wt% LDPE of density 0.921–0.924 g/cm³. The ratio is not increased beyond 70 wt% in the core because bubble breathing on 250 mm dies becomes measurable at higher concentrations. Compliance for this direct food contact structure requires EU Regulation (EU) No 10/2011 with overall migration below 10 mg/dm² according to EN 1186-1:2002, as well as olefin polymer clearance under FDA 21 CFR 177.1520(c) with extractable limits aligned to 21 CFR 176.170(c). Pellet drying is not required at ambient relative humidity below 60%; if silo condensation is observed, a desiccant hopper set at 60 °C for 2 h with a dew point of -20 °C removes surface moisture without thermal degradation.

Conversion is performed on a three-layer coextrusion line with a die diameter of 250–300 mm, die gap 1.8–2.4 mm, blow-up ratio 2.0–2.8, and frost-line height 600–900 mm; melt temperatures are held between 215 °C and 230 °C to avoid resin oxidation while maintaining adequate film optics. Internal bubble cooling with exhaust dew point below 5 °C stabilizes the bubble at output rates of 25–35 kg/h. A blow-up ratio of 2.0–2.4 yields balanced dart impact and machine-direction tear resistance; exceeding 2.8 BUR on this grade without additional LDPE reduces bubble stability on conventional air-ring systems. The finished product is a gusseted freezer bag or pillow pouch for portioned frozen vegetables, with surface treatment maintained at 38–42 dyne/cm before flexographic or rotogravure printing.

What Limits Bubble Stability When 1046F Is Blended with LDPE on a 350 mm Die for Heavy-Duty Shipping Sacks?

Heavy-duty shipping sack film based on Borealis Stamylex™ 1046F is formulated at 70–85 wt% 1046F with 15–30 wt% LDPE of melt index 0.2–0.4 g/10 min. The inclusion of LDPE below 15 wt% is insufficient to suppress high-frequency bubble oscillation on a 350 mm annular die, while LDPE above 30 wt% lowers tear propagation resistance to an extent that sack integrity tests according to ASTM D1922-15a fall below the 120 g acceptance threshold on 120 µm film. The production line is a mono-layer blown film extruder with a 350 mm die, 2.2–2.6 mm die gap, internal bubble cooling, and a dual-lip air ring; lay-flat width is set between 700 mm and 1,100 mm by adjusting blow-up ratio from 3.0 to 3.8. Melt temperature is kept at 215–240 °C, and the frost line is raised to 1,000–1,400 mm to shift molecular orientation toward the transverse direction, reducing pipe-splitting on FFS lines. Melt temperature above 245 °C is avoided because gel formation in the film increases and die lip deposit rates accelerate under continuous production.

Regulatory compliance for non-food industrial sacks rests on Regulation (EC) No 1907/2006 and Directive 94/62/EC packaging material recovery provisions; mechanical qualification uses ASTM D1709-16a dart impact, ASTM D882-18 tensile, and ISO 527-3 elongational break. Film thickness is set at 120–180 µm depending on fill weight, with 150 µm specified for 25 kg resin sacks. The terminal product is a gusseted form-fill-seal sack for polymer granules, fertilizers, or industrial additives, with valve closure or open mouth dependent on downstream FFS clamp configuration.

In greenhouse cover converting, Stamylex 1046F is let down into a monolayer blown film formulation at 80–90 wt% with ethylene-vinyl acetate copolymer of 12–18% VA content at 10–20 wt% to raise light transmission and low-temperature flexibility; a hindered amine light stabilizer masterbatch is added at 5–7 wt%, and a silica antiblock masterbatch is added at 3–5 wt%. The governing specification is EN 13206:2017 for thermoplastic greenhouse coverings, with tensile retention after artificial weathering tested under ISO 4892-2 and ISO 527-3, and haze under ASTM D1003-21. UV masterbatch below 5 wt% is not recommended for multi-season covers intended for latitudes above 45°; converter-validated photosynthetically active radiation transmission above 85% at 160 µm thickness is used as an internal quality gate before commercial shipment.

Processing is completed on a blown film line with a 400 mm die, die gap 2.0–2.5 mm, blow-up ratio 1.8–2.2, melt temperature 220–240 °C, and lay-flat widths up to 3,000 mm for greenhouse arch covers. Because EVA increases oxygen permeability and can lower tear propagation in LLDPE/EVA blends, pressurised air flow is tuned to maintain a constant stalk height of 1,200–1,500 mm; sudden changes in cooling air temperature below 10 °C produce gauge bands that are rejected under ISO 4591 thickness mapping. The terminal product is a multi-season greenhouse cover, silage clamp cover, or bale wrap; when used as silage wrap the formulation is modified with carbon black or UV barrier masterbatch to reduce oxygen ingress below 0.1 m³/m²/day/atm as a control point for anaerobic fermentation systems.

Lamination Sealant Layers in Complex Flexible Packaging Structures

A sealant web based on Borealis Stamylex™ 1046F is prepared at 85–95 wt% 1046F with 5–15 wt% LDPE or polyolefin plastomer to depress seal initiation temperature to 85–105 °C for low-distortion sealing against oriented PET or aluminium foil. The web is produced on a three-layer blown film coextrusion line with die diameter 250 mm, die gap 1.6–2.0 mm, blow-up ratio 2.0–2.4, melt temperature 215–230 °C, and final film thickness 40–80 µm. The resulting sealant film is adhesive-laminated to reverse-printed PET at 12 µm or aluminium foil at 7–9 µm using a solventless polyurethane adhesive at 1.8–2.2 g/m² coat weight. Food contact clearance for the sealant web requires FDA 21 CFR 177.1520(c) and EU Regulation (EU) No 10/2011 with test conditions assigned by food simulant type: 10 days at 40 °C for aqueous foods, 10 days at 60 °C for alcoholic foods up to 20% alcohol, and 10 days at 20 °C for dry foods.

Seal strength is verified on the laminate using ASTM F88/F88M-21, with minimum seal strength of 18 N/15 mm at 120 °C seal jaw setting. The compliance matrix below applies to converters supplying the EU and United States food packaging sectors; the absence of a listed verification does not remove responsibility for converter-specific migration screening under the finished laminate configuration.

The terminal product is a stand-up pouch, three-side seal sachet, or lidding sealant layer for dried food, frozen food, or liquid condiments. The sealant web is not recommended for retort steam sterilization above 121 °C because seal integrity decline is observed on accelerated ageing under ASTM F1980-21 in high-acid packaged media.

Because Stamylex 1046F retains high elongational viscosity at low melt temperatures, stretch hood film manufacturers run the grade at 70–85 wt% with 15–30 wt% VLDPE or polyolefin plastomer of density 0.900–0.910 g/cm³ in a three-layer coextruded blown stretch line to achieve machine-direction permanent set below 40% after 200% elongation. The resin combination is processed on a 450 mm die with 2.0–2.4 mm die gap, blow-up ratio 3.5–4.0, melt temperature 215–235 °C, and film thickness 80–130 µm. The line is configured with high-gloss cooling at 12–15 °C to reduce ambient blocking of the cling-free outer layers; when temperature drops below 5 °C, the drawn film becomes prone to transverse thickness variation beyond ±8% on 3,000 mm lay-flat.

Mechanical qualification follows ASTM D5459-16a for machine-direction elastic recovery and permanent set, ASTM D882-18 for tensile, and ISO 527-3 for elongation at break. For pallet unitization the film is fabricated into gusseted stretch hoods with a lay-flat width of 1,600–2,400 mm and is applied by stretch-hood machines at clamp speeds up to 1.2 m/s; the grade is not intended for high-speed cast stretch wrapping below 15 µm gauge due to its melt flow index and melt elasticity. The terminal product is a heavy-duty stretch hood for building material pallets, bagged cement, or garden products.

When a Converter Runs 1046F in High-Clarity Collation Shrink Film Below 200 °C Melt Temperature

In collation shrink film for beverage cans and rigid food containers, Borealis Stamylex™ 1046F is compounded in a 50–70 wt% blend with 30–50 wt% LDPE of density 0.921–0.924 g/cm³ to control the shrink window and reduce free shrink onset below 120 °C. The film is converted on a double-bubble line rather than a single-bubble line because the second bubble orientation fixes both machine-direction and transverse-direction shrink at 4.0:1 and 4.5:1 ratios respectively; the first bubble melt temperature is maintained at 190–220 °C, while the second orientation bubble is heated to 115–130 °C with external air pressure trimmed to prevent gauge bands below 8% deviation. Die diameter is 200–250 mm, die gap 1.4–1.8 mm, and final film thickness is 35–60 µm. Lower melt temperature below 190 °C causes unmolten particle formation in the first bubble, while exceeding 220 °C narrows the shrink window and increases blocking on the second bubble collapsing frame.

Compliance for collation shrink in retail distribution is based on Directive 94/62/EC and Regulation (EU) No 10/2011 if the film contacts packaged food; shrink tension and shrink percentages are quantified under ISO 14616:2019 and ASTM D2732-20. Published data for the specific combination of 1046F in a 200 mm double-bubble line is limited, so converter-specific shrink-curve development is required before commercial qualification. The terminal product is a clear or printed collation shrink wrap for canned beverages, bottled water, or multipack rigid containers.