Borealis Borstar FB2230 is processed on conventional high-stalk blown film lines with grooved-feed extruders in the 50 mm to 90 mm screw diameter range and L/D ratios between 24:1 and 30:1. The resin is a bimodal linear low-density polyethylene with a nominal density of 0.923 g/cm³ and a nominal melt flow rate of 0.20 g/10 min at 190 °C under a 2.16 kg load, as specified by ISO 1133-1. The bimodal molecular weight distribution separates the high-molecular-weight fraction that stabilizes the bubble from the low-molecular-weight fraction that reduces extrusion pressure. Film thickness in heavy-duty industrial sacks is held between 100 µm and 200 µm. Typical die gap settings are 1.8 mm to 2.2 mm. Blow-up ratio is commonly maintained between 2.2:1 and 3.0:1. Melt temperature at the die is kept from 210 °C to 230 °C. Internal bubble cooling is recommended when output exceeds the air-ring cooling capacity, typically above 180 kg/h on a 250 mm die. For heavy-duty shipping sack film, FB2230 is used at 100 % or in blends with a low-density polyethylene carrier resin at 10 wt% to 20 wt% to adjust dart impact and bubble stability. Antiblock masterbatch is added at 1 wt% to 2 wt%, and slip masterbatch at 0.5 wt% to 1.0 wt%, depending on sack handling friction requirements. Fluoropolymer processing aid is introduced at 0.03 wt% to 0.05 wt% when die lines or sharkskin appear. Dart drop impact is evaluated according to ASTM D1709. Tensile properties are measured according to ISO 527-3. Tear resistance is measured according to ISO 6383-2. Terminal structures include FIBC inner liners, hazardous material sacking, and industrial bulk packaging. Excessive regrind above 20 wt% reduces dart impact because oxidized edge trim introduces gel bodies and local stress concentrations. Film blocking in wound rolls is minimized by controlling frost line height and antiblock dosage.

Agricultural Silage Film Is Not a Single-Layer Commodity

Agricultural silage film is specified less by optical clarity than by puncture propagation resistance and oxygen barrier retention under weathering. Borealis Borstar FB2230 is run in thin-gauge silage wrap between 25 µm and 50 µm. A typical formulation is 70 wt% FB2230, 20 wt% LDPE, and 10 wt% ethylene-vinyl acetate. Polyisobutylene tackifier is dosed at 1 wt% to 3 wt% of final film weight. Hindered amine light stabilizer and benzophenone UV absorber are incorporated through a 5 % masterbatch at 0.3 wt% to 0.6 wt% active content, depending on expected sun exposure. EN 13207 is the reference standard for silage film performance. Puncture resistance is tested under ASTM D5748. Tensile strength and elongation are measured according to ISO 527-3. Oxygen transmission rate is verified by ISO 15105-2. The production line uses a 70 mm extruder with L/D 30:1 and a 200 mm die. Blow-up ratio is set between 2.8:1 and 3.5:1. Frost line height is raised 4 to 6 die diameters above the air ring to stabilize the bubble. Terminal products include round bale silage wrap and clamp silage sheets.

Low-temperature drop impact in frozen food pouches is limited by the brittle-ductile transition of the polyethylene layer. Borealis Borstar FB2230 is used as the core or skin layer in coextruded frozen food film at total thickness from 40 µm to 80 µm. The core layer typically contains 70 wt% to 90 wt% FB2230, with the balance being a metallocene LLDPE sealing grade. The sealant layer is a separate metallocene LLDPE or a plastomer-modified LLDPE. Film is fabricated on a high-stalk line with a die temperature of 195 °C to 215 °C. Lower melt temperatures reduce oxidative degradation and off-taste formation. Blow-up ratio is maintained between 2.5:1 and 3.5:1. Frost line height is set 2 to 4 die diameters above the air ring for gloss and impact balance. Dart impact is tested to ISO 7765-2. Tensile and seal strength are tested to ISO 527-3 and ASTM F88. The final film must comply with EU Commission Regulation 10/2011 for overall migration and FDA 21 CFR 177.1520 for olefin polymers. Pellets do not require drying below 60 % relative humidity. Above that threshold, surface moisture can create micro-voids and sharkskin on the inner layer. Terminal products include frozen vegetable pouches, quick-frozen seafood bags, and boneless meat liners.

Why Does Extrusion Lamination Demand a Melt Curtain with a Defined Neck-In Window?

In woven polypropylene sack lamination, the melt curtain exits a flat die and is drawn into a nip between a chill roll and a pressure roll. The primary process conflict is the neck-in of the polyethylene melt. Curtain width loss determines edge trim and final laminate width. Borealis Borstar FB2230 is used as the extrusion coating resin because the bimodal molecular weight distribution provides higher melt tension than conventional LLDPE grades. Equipment on full-scale lines includes a 90 mm extruder with L/D 30:1 and a 2000 mm flat die. Melt temperature at the die is held between 290 °C and 320 °C. The air gap is set between 150 mm and 250 mm. Line speed ranges from 100 m/min to 250 m/min depending on substrate type and coat weight. A typical coat weight is 15 g/m² to 30 g/m². Draw ratio is maintained below 2.5:1 to minimize draw resonance. Ozone treatment of the melt curtain is applied at generator output levels specified by the coating line supplier to create polar sites on the polymer surface and raise adhesion to woven polypropylene. When adhesion remains insufficient, a tie resin or a blend of FB2230 with 20 wt% maleic anhydride-grafted LLDPE is used. Thermal degradation above 320 °C generates gel bodies that appear as unmelts in the laminate. Tensile properties of the coated web are tested to ISO 527-3. Terminal products include woven polypropylene cement sacks, fertilizer bags, and industrial kraft paper laminates. Exact neck-in values are not transferred across die widths; published data for this specific configuration is limited.

Carrier bag production on high-speed rotary die lines is constrained by bubble flutter when the film gauge is below 25 µm. Borealis Borstar FB2230 is blended with 20 wt% to 30 wt% LDPE for processability on these lines. Film thickness is typically 15 µm to 30 µm. Die gap is set at 1.6 mm to 2.0 mm. Blow-up ratio is held at 2.2:1 to 2.8:1 to avoid excessive transverse orientation. Frost line height is kept at 1 to 2 die diameters above the air ring to stabilize the bubble. Antiblock masterbatch is added at 0.5 wt% to 1.0 wt% to prevent blocking on the roll. Slip masterbatch is added at 0.3 wt% to 0.8 wt%. Dart impact is tested according to ISO 7765-2. Tear resistance is measured according to ISO 6383-2. Tensile properties are measured according to ISO 527-3. The film is converted into t-shirt bags, loop-handle bags, and fruit and vegetable bags. High take-off speeds above 120 m/min require internal bubble cooling and careful control of frost line height.

Stretch Hood Film Puncture and Holding Force Balance

Pallet unitization films are specified by a minimum puncture resistance and a defined elastic recovery after machine-direction stretching. Borealis Borstar FB2230 is deployed in the main layer of multi-layer stretch hood films. Total film thickness is 50 µm to 80 µm. A typical formulation is 65 wt% to 75 wt% FB2230, 10 wt% to 20 wt% LDPE, and 10 wt% to 15 wt% metallocene LLDPE. The metallocene component improves stretchability and elastic recovery. Puncture resistance is measured according to ASTM D5748. Holding force and elongation at break are tested according to ASTM D882 and ISO 527-3. Cling is tested according to ASTM D5458. Blow-up ratio is set between 3.0:1 and 4.0:1 to generate balanced machine-direction and transverse mechanical properties. Melt temperature at the die is held from 200 °C to 220 °C. Terminal products include stretch hood film for pallet loads of construction blocks, beverage crates, and chemical drums.