Borealis Queo VLDPE 8210 is introduced into the sealant layer of a three-layer cast coextrusion for high-speed vertical form-fill-seal food packaging at a layer ratio of 15/70/15 and a total film thickness of 70 µm. The sealant layer is a pellet blend of 70 wt% LDPE and 30 wt% 8210; the core is a C4-LLDPE with 0.918 g/cm³ density and 1.0 g/10 min MFR, and the outer layer is a polypropylene-based heat-resistant web for horizontal sealing heads. A 90 mm single-screw extruder with barrier screw and L/D 30:1 feeds the sealant layer, a 120 mm extruder feeds the core, and a 65 mm extruder feeds the outer layer. Melt temperature at the die is controlled at 235 °C, with a die gap of 0.8 mm and a chill roll temperature of 18 °C. Seal initiation temperature is measured by ASTM F1921-12 hot-tack and ASTM F88/F88M-21 seal strength on a laboratory sealer with 0.5 MPa jaw pressure and 0.5 s dwell time. The low density of 0.882 g/cm³ and MFR of 1.0 g/10 min (ISO 1183-1, ISO 1133-1) allow the sealant layer to form a continuous melt seal at sealing jaw temperatures below 95 °C, which shortens dwell time on packaging machines. Finished pouches for dry foods and confectionery flowwrap exhibit a seal strength plateau above 12 N/15 mm when the sealant layer contains between 20 wt% and 40 wt% 8210; below 20 wt% the hot-tack window narrows, and above 40 wt% blocking on the roll increases unless a synthetic silica antiblock masterbatch is used at 2,000–4,000 ppm. The sealant layer is corona treated to 40 mN/m and must not exceed 46 mN/m because excessive oxidation promotes surface tack. The film is assessed for overall migration under EU Regulation (EU) No 10/2011 Annex I and for olefin polymer compliance under FDA 21 CFR 177.1520(c). The main process limitation is the low melt strength of 8210 at high addition; when the cast film line accelerates above 120 m/min, neck-in at the die edge can exceed 35 mm on a 2,400 mm die unless the chill roll is positioned within 25 mm of the die lip and the sealant layer melt temperature is reduced to 225 °C.

What limits puncture retention when 8210 is blended at 20 wt% with C4-LLDPE?

A three-layer blown film for heavy-duty shipping sacks and agricultural silage bags is produced with 8210 in the outer layers at 20 wt% of the layer composition. The base resin is a C4-LLDPE with MFR 0.9 g/10 min and density 0.920 g/cm³. The film has a total thickness of 150 µm, a layer ratio of 1:2:1, and a lay-flat width of 1,600 mm. Extrusion is run on a 70 mm grooved-feed extruder with L/D 30:1, a die diameter of 350 mm, die gap 1.8 mm, blow-up ratio 2.8:1, and frost line height 700 mm. The output is 180 kg/h. Addition of 8210 lowers overall crystallinity and increases Elmendorf tear propagation measured by ASTM D1922-15 in machine direction. At 20 wt%, the bubble is stable because the high-comonomer fraction is diluted; above 30 wt%, tubular bubble stiffness decreases and width variation increases beyond ±15 mm, creating creasing at the bottom fold during sack conversion. Puncture retention is assessed by dart drop impact per ISO 7765-1 at 23 °C and at -18 °C for frozen agricultural product. At low temperature, the contribution of 8210 is more pronounced because its low crystallinity retards embrittlement; however, the blend is limited to 30 wt% by bubble stability, not by film toughness. The finished sacks are filled with 25 kg of petrochemical granules or fertilizer and are dropped from 1.2 m according to ISO 7965-1; film failure initiates at the heat-sealed bottom gusset rather than in the bubble wall when 8210 is present. Processing with 8210 requires the first barrel zone to remain below 150 °C to prevent early melting of the low-density phase, which would cause pellet bridging in the hopper. The bubble should not be subjected to intensive cooling below 12 °C with high ambient humidity because surface condensation can increase slip additive migration and reduce sealing performance. REACH registration under EC 1907/2006 is maintained for non-food sack applications.

A three-layer stretch hood film with nominal thickness 90 µm and film width 1,200 mm is produced with 8210 in the outer layers at 25 wt% of the layer composition. The core remains a C6-LLDPE with MFR 0.8 g/10 min and density 0.917 g/cm³. The blown line uses a 75 mm extruder with barrier screw and L/D 28:1, die diameter 400 mm, BUR 3.2:1, and lay-flat width control by an ultrasonic width sensor. The low density of 8210 lowers the tensile modulus of the outer plies; secant modulus at 1% strain is determined by ISO 527-3 and is used to adjust the stretch ratio on the pallet wrapping machine. A stretch ratio of 1.9:1 is applied by the hood applicator, and the residual holding force is checked after 24 h at 23 °C using a load retention fixture. The use of 8210 in the outer layers reduces blocking force on the pallet, but the film requires a slip/antiblock masterbatch at 1,500 ppm to maintain film unwinding from the reel. Coefficient of friction is measured by ASTM D1894-14 on both surfaces; kinetic COF is held below 0.35 on the outer layer. The main processing conflict is the low melting point of 8210: if the frost line height is below 600 mm, the outer layer can block at the collapsing frame, producing film wrinkles and gauge bands. The frost line is therefore raised to 700 mm during hot summer production. Terminal use is pallet unitization for cement bags and construction materials, where the hood must retain tension during outdoor storage. The film is non-food contact and must comply with REACH EC 1907/2006 SVHC screening; no specific food-contact migration testing is required for this end use. When the line speed is increased above 200 m/min, the bubble becomes more sensitive to draughts; a tower enclosure is required to maintain gauge tolerance within ±5% across the lay-flat.

When ethylene oxide sterilisation cycles demand low-temperature impact retention

A coextruded three-layer film for medical device overwrap uses 8210 as the sealant layer at 40 wt% with LDPE. The film is produced by cast coextrusion at a total thickness of 60 µm and a layer ratio of 20/60/20; the sealant layer is the inside layer contacting the paper or nonwoven lid. A 65 mm extruder with L/D 30:1 feeds the sealant layer at a melt temperature of 220 °C; the chilled roll is maintained at 20 °C to avoid haze and curl. Low seal initiation is required because the medical device inside the pouch is heat-sensitive; the sealant layer is specified by a heat-seal curve per ASTM F1921-12 and ASTM F88/F88M-21, with hot-tack and seal strength measured after sealing at 105 °C and 0.5 MPa for 0.8 s. The use of 8210 shifts the seal initiation temperature below that of a pure LDPE sealant layer, but the seal strength after storage at 5 °C must be validated because low-temperature crystallisation can reduce peel seal strength. Ethylene oxide sterilisation is carried out at 55 °C with 60% RH and 3 h exposure, followed by forced degassing at 45 °C for 24 h; seal strength retention is measured before and after sterilisation. The lower melting point of 8210 means that the sealant layer must not be exposed to steam sterilisation at 121 °C or 134 °C, as the seal area can distort under load. Low-temperature impact retention is evaluated by ISO 8570 cold-crack temperature; films with 8210 retain flexibility at -30 °C without cracking when folded over a mandrel. Packaging validation follows ISO 11607-1:2019 for packaging systems for terminally sterilized medical devices, including seal integrity by dye penetration and bubble emission per ASTM F2096. Cytotoxicity is assessed per ISO 10993-5:2009 using L929 cell culture. The finished products are wound care pouches and surgical drape overwrap, where the seal must be peelable without tearing the nonwoven lid. The sealant layer is corona treated to 38 mN/m; higher treatment can cause the low-molecular-weight fraction in 8210 to migrate to the seal surface and reduce seal strength after 12 months at ambient storage. The main lot-to-lot variation to control is the comonomer distribution of 8210; if the octene content varies, the seal initiation temperature can shift by 2–3 °C, which is critical for high-speed medical pouch lines.

Screw speed, back pressure and melt temperature windows in 25:1 L/D single-screw compounding

Process conditions for compounding 8210 begin with a 75 mm single-screw compounder having L/D 25:1, screw speed 80 min⁻¹, back pressure 12 MPa, barrel zones 160–210 °C, and melt temperature 215 °C. Borealis Queo VLDPE 8210 is used as an impact modifier in a compound with HDPE and calcium carbonate for injection moulded flexible industrial fittings. The formulation is 65 wt% HDPE, 20 wt% 8210, 10 wt% calcium carbonate masterbatch, and 5 wt% pigment masterbatch. The low melting point of 8210 requires that it be introduced into a side feed port after the first mixing zone; if it is dry-blended with HDPE and fed from the main hopper, the 8210 phase melts first and wets the screw, reducing throughput and causing melt pressure instability. The compound is pelletised by an underwater die-face cutter with die plate temperature 220 °C and water temperature 30 °C. The notched impact resistance of the moulded parts is measured by ASTM D256-23 at -40 °C; the addition of 8210 improves impact resistance at low temperature relative to the HDPE control, but the flexural modulus decreases, which must be accepted for flexible conduit fittings. The melt flow rate of the compound is determined by ISO 1133-1 at 190 °C/2.16 kg; the target is 0.5–0.7 g/10 min for injection moulding of thick-walled parts. Terminal products are flexible cable grommets and industrial conduit fittings, where compliance with RoHS Directive 2011/65/EU and REACH EC 1907/2006 is required. The operational boundary is the upper melt temperature: above 240 °C, the VLDPE component can generate gels in the die plate, requiring filter pack change after 72 h of continuous operation. The compound should be dried only if relative humidity exceeds 85%; otherwise, drying at 70 °C for 3 h may cause pellet blocking in the hopper.

Extruded flexible tubing and cap liners operate below a 0.1 GPa flexural plateau

Flexible tubing for peristaltic pumps and pharmaceutical cap liners is extruded from 8210 or a blend of 8210 with LDPE. Tube extrusion runs on a 45 mm single-screw extruder with L/D 24:1 and a pin-and-die sizing head. Die temperature is 190 °C, melt pressure 18 MPa, and draw ratio 1.2:1. The low crystallinity of 8210 maintains a low flexural modulus and high strain at break. Tensile properties are determined by ISO 527-2 at 23 °C; strain at break for this grade generally exceeds 700% depending on specimen geometry and cooling conditions. The low plateau modulus is the critical design variable for peristaltic pump tubes because the tube must rebound to its original cross-section after repeated compression. A comparative fatigue test is run on a peristaltic pump head at 200 min⁻¹ for 100 h; tubes made from 8210 show lower permanent set than tubes made from LDPE of the same wall thickness. The cap liner application uses a solid web of 8210 extruded at 0.4 mm thickness and die-cut into discs; the liner is inserted into pharmaceutical vial caps to form a seal against the bottle land. Sealability is measured by torque retention after 24 h at 40 °C and compression set per ASTM D395-18 method B at 23 °C. Regulatory compliance for pharmaceutical contact includes USP 661.1 plastic packaging systems and FDA 21 CFR 177.1520. The main incompatibility is with long-term exposure to strong oxidizing agents or aliphatic solvents, which can swell the low-crystallinity matrix. The tubing must not be used in continuous contact with steam above 80 °C or with ethanol-containing formulations above 40% without specific migration testing. For tube sizing, the vacuum calibration tank should be kept at 25 °C with a water flow rate of 20 L/min per die to prevent tube ovality below 0.5 mm on a 6 mm outside diameter.