Borealis Borstar® FB4250T is specified in blown film converting where a bimodal linear low-density polyethylene must combine a melt flow rate of 0.4 g/10 min (190 °C, 2.16 kg, ISO 1133-1:2022) with a density of 0.923 g/cm³ (ISO 1183-1:2019). The route scope below is limited to established blown film downstream sectors; it excludes injection moulding, blow moulding, and extrusion coating. Each application section records the regulatory premise, the blend ratio window, the production equipment, and the terminal article type.

Application route	EU/international reference	US reference	Relevant test method
FFS heavy-duty sacks	EU Regulation (EU) 10/2011; ADR 6.1.5.2.4	FDA 21 CFR 177.1520(c); US DOT 49 CFR Part 178	ISO 527-3:2018; ASTM D1709-16a
Frozen-food lamination sealant web	EU Regulation (EU) 10/2011 Annex II	FDA 21 CFR 177.1520(c)	ASTM F88/F88M-21
Agricultural greenhouse/silage covers	EN 13206:2017; REACH Regulation (EC) 1907/2006	No direct food-contact reference	EN ISO 4892-2:2013; ISO 527-3:2018
Collation shrink film	REACH Regulation (EC) 1907/2006; EU Regulation (EU) 10/2011 where food-contact	Application-dependent	ISO 14616:1997
UN 13H3 sacks	ADR 6.1.5.2.4; REACH Regulation (EC) 1907/2006	US DOT 49 CFR Part 178	ASTM D5748-19; ASTM D1922-15(2020)
Heavy-duty container liners	REACH Regulation (EC) 1907/2006; EU Regulation (EU) 10/2011 where food ingredient	FDA 21 CFR 177.1520(c)	ASTM D1709-16a; ISO 527-3:2018

What Limits Bubble Stability When FB4250T Is Processed on High-Stalk Form-Fill-Seal Film Towers?

High-stalk blown film lines with grooved-feed extruders and screw L/D ratios of 30:1 to 37:1 are the primary conversion route for form-fill-seal heavy-duty sacks. The resin is normally processed at a melt temperature of 190 °C to 215 °C, with a die gap of 1.0 mm to 1.4 mm and a blow-up ratio between 3.0:1 and 4.0:1. Bubble stability becomes the limiting factor when the frost-line height exceeds 8 die diameters or when the extrusion rate is pushed above 350 kg/h on a 300 mm die; below these limits, the grade maintains a stable neck and avoids melt fracture. In a neat 100 wt% FB4250T formulation, the film typically achieves machine-direction tensile values above 35 MPa when tested at 500 mm/min according to ISO 527-3:2018, and dart impact values above 150 g using ASTM D1709-16a method A. Where converters require additional melt strength for lightweighting from 80 µm to 60 µm, a blend of 80 wt% FB4250T with 20 wt% high-pressure LDPE with a melt flow rate below 1.0 g/10 min is substituted; this blend reduces film modulus but raises the bubble's axial stability. Regulatory compliance for food-contact dry goods is based on EU Regulation (EU) 10/2011 Annex I and FDA 21 CFR 177.1520(c), with overall migration testing conducted according to EN 1186-1:2002; for non-food chemical precursors, transportation requirements are set by UN 13H3 where applicable. The downstream finished articles include FFS sacks for cement, granular fertilizer, petrochemical masterbatch, and industrial salts.In lamination converting, the sealant web is produced on three-layer blown film lines where FB4250T forms the inner sealing layer at a thickness of 20 µm to 30 µm within a 45 µm to 70 µm total web. The formulation blends 60 wt% FB4250T with 30 wt% metallocene-catalysed hexene LLDPE and 10 wt% LDPE to widen the heat-seal plateau; a higher FB4250T fraction above 70 wt% reduces hot-tack strength when the web is subjected to dwell times below 0.3 s on rotary pouch equipment. Production conditions include a melt temperature of 185 °C to 200 °C, a die gap of 0.8 mm to 1.2 mm, and a blow-up ratio of 2.0:1 to 2.8:1 to limit transverse orientation. Heat-seal strength is measured on a 25 mm wide specimen in accordance with ASTM F88/F88M-21; converters commonly require seal initiation below 105 °C at a jaw pressure of 0.3 MPa to qualify the web for cold-chain pouches. The downstream converting step uses solventless polyurethane adhesive lamination onto biaxially oriented polyester or polyethylene terephthalate, followed by slitting to 400 mm to 1,200 mm reels. EU food-contact compliance for this structure is evaluated under EU Regulation (EU) 10/2011 Annex II, and US compliance under FDA 21 CFR 177.1520(c). Terminal finished products are primarily frozen seafood and vegetable pouches, lidding film for modified-atmosphere trays, and industrial ingredient pouches.

Dosing HALS and UVA Masterbatches into FB4250T for Wide-Span Greenhouse and Silage Cover Films

Addition of the stabiliser masterbatch is performed by gravimetric dosing at the extruder feed throat to maintain a final formulation of 88 wt% FB4250T, 6 wt% LDPE, and 6 wt% additive masterbatch, of which the hindered amine light stabiliser component is 0.3 wt% to 0.5 wt% and the UV absorber component is 0.2 wt% to 0.4 wt%. The film is produced on a monolayer blown film line with internal bubble cooling, a 300 mm die, a die gap of 1.2 mm to 1.6 mm, and a blow-up ratio between 3.0:1 and 4.0:1 to balance machine-direction and transverse-direction tensile strength. Thickness ranges from 120 µm to 200 µm for greenhouse covers and from 60 µm to 120 µm for silage sheets, with frost-line height set higher than for food films to stabilise the large-diameter bubble. Accelerated weathering is assessed according to EN ISO 4892-2:2013 cycle A1, with tensile elongation at break measured according to ISO 527-3:2018; agricultural films are required to retain at least 70% of initial elongation after 6,000 hours of artificial weathering in many EU purchase specifications. The relevant product standard is EN 13206:2017, which covers thermoplastic films for use in agriculture and horticulture; where the film is used as a silage cover inside farms, no direct food-contact migration testing is required, but the masterbatch must comply with the environmental provisions of REACH Regulation (EC) 1907/2006. Terminal finished articles include greenhouse outer covers, silage clamp covers, and temporary crop storage liners.Where shrink force must remain below 2.0 N/cm on collation shrink lines for beverage multipacks, FB4250T is converted as part of a multilayer blown structure rather than as a neat monolayer. The formulation for the structural layer is 70 wt% FB4250T and 30 wt% high-pressure LDPE, while the outer skins are built from metallocene-catalysed hexene LLDPE to raise free-shrink above 50% at 120 °C. Blown film production uses a die gap of 0.8 mm to 1.0 mm, a blow-up ratio of 3.5:1 to 4.5:1, and a low melt temperature of 180 °C to 195 °C to preserve molecular orientation; the bubble is then collapsed and annealed through a series of temperature-controlled rollers before edge trim. Compression shrink force is measured on a 100 mm × 100 mm specimen after 30 s in an oil bath at 120 °C, with the test performed in accordance with ISO 14616:1997. Compliance for collation shrink films is generally limited to REACH Regulation (EC) 1907/2006 and, for direct food-contact bundled packs, EU Regulation (EU) 10/2011 when the film contacts unwrapped food surfaces. Terminal product forms are collation shrink hoods for mineral water bottles, soft drink multipacks, and logistics shrink films for corrugated tray consolidation.

When a UN 13H3 Dangerous Goods Sack Requires Both Puncture Resistance and Low Creep

Blending 15 wt% to 20 wt% of a high-density polyethylene with FB4250T raises the plane-strain creep resistance of a hazardous-goods sack without removing the essential tubular bubble stability during conversion. The production route is a high-output three-layer blown film line in which the core layer comprises 80 wt% FB4250T and 20 wt% HDPE, while the outer layers are composed of neat FB4250T to maintain sealing integrity. Extrusion occurs through a 250 mm to 400 mm die with a die gap of 1.0 mm to 1.3 mm, a blow-up ratio of 3.0:1 to 3.6:1, and a melt temperature of 190 °C to 210 °C. The finished converter tests puncture resistance according to ASTM D5748-19 and Elmendorf tear according to ASTM D1922-15(2020); a 100 µm sack film generally requires a machine-direction tear value above 8 N and a puncture resistance above 50 N to pass the UN drop and stacking protocols specified in ADR 6.1.5.2.4 for 13H3. Because these sacks carry pigments, carbon black masterbatch, or low-toxicity chemical powders, food-contact regulatory approval is not required, but the final article must satisfy REACH Regulation (EC) 1907/2006 and, for export to North America, US DOT 49 CFR Part 178 packaging specifications. Terminal finished products are UN 13H3 valve sacks and open-mouth sacks for organic pigments, carbon black, flame retardants, and construction chemicals.

Heavy-Duty Container Liners in 250–400 µm Basis Weight with Low Gel Count and High Dart Impact

Extruder screw geometry on high-output three-layer lines is set with barrier screws and mixing sections to deliver a melt temperature of 195 °C to 215 °C, a 300 mm to 500 mm die, a die gap of 1.2 mm to 1.5 mm, and a blow-up ratio of 2.2:1 to 3.0:1; this route is used for container liners that must withstand filling with bulk powders or liquids. The formulation is 90 wt% FB4250T and 10 wt% LDPE, with no calcium carbonate or regrind above 5 wt% because gel counts in the liner wall are directly correlated with leak-site formation on filling stations. Dart impact resistance for a 300 µm liner is measured according to ASTM D1709-16a method B, with acceptance typically above 400 g; tensile modulus is measured according to ISO 527-3:2018, and the expected modulus in the machine direction is above 230 MPa. Regulatory documentation for non-food bulk chemical packaging includes REACH Regulation (EC) 1907/2006 and, for materials exported as food ingredient liners, FDA 21 CFR 177.1520(c) or EU Regulation (EU) 10/2011. The downstream terminal product types include FIBC liners, drum liners, intermediate bulk container liners, and flexible tank liners for liquid polyol and latex intermediates.