In three-layer blown-film lines configured for direct food-contact packaging, Dow FLEXOMER VLDPE 2345 with nominal density 0.910 g/cm³ (ISO 1183) and melt flow rate 0.5 g/10 min at 190 °C/2.16 kg (ASTM D1238) is used in the skin layers at 80–100 wt%, while the core layer comprises an LDPE or butene-LLDPE heat-seal resin at 0–20 wt% and a slip/antiblock masterbatch at 1–3 wt% depending on final thickness. The regulatory basis for food contact is EU Regulation (EU) No 10/2011 Annex I with an overall migration limit of 10 mg/dm² and US FDA 21 CFR 177.1520(c); migration testing is performed under the frozen-food simulant and time-temperature conditions assigned for long-term storage at or below -18 °C. The downstream process is a three-layer coextrusion blown-film line: a 90 mm grooved-feed extruder with 30:1 L/D running at 220–260 kg/h, a die gap of 1.5–2.5 mm, melt temperature 193–221 °C, blow-up ratio 2.2–2.8, and frost-line height 300–500 mm. Production-scale field data show that raising blow-up ratio above 2.8 while holding frost-line height below 300 mm destabilises bubble position and produces visible frost-line oscillation; melt temperature below 190 °C increases gel counts at the core/skin interface because the LDPE-rich core remains inhomogeneous. Finished product types include frozen vegetable pouches, ice-cream bags, and fish-block packaging, where the property requirement is film impact strength tested to ASTM D1709 and low-temperature seal integrity tested to ASTM F88.

What governs puncture resistance in cast stretch-film cling layers?

Cast-film trials with a five-layer coextrusion line running a cling-layer formulation of 15–30 wt% FLEXOMER VLDPE 2345 in an octene-LLDPE matrix, with the opposite skin layer carrying 1–2 wt% antiblock masterbatch, show that the VLDPE fraction controls both cling force and low-speed puncture. Compliance for industrial palletisation is REACH Regulation (EC) No 1907/2006; if used as food-contact bundling film, EU Regulation (EU) No 10/2011 and FDA 21 CFR 177.1520(c) apply, but the non-tackified cling formulation is selected to avoid migration species that would otherwise require additional specific migration testing. Production is cast-film coextrusion through a 1300 mm slot die at melt temperatures 230–260 °C, die lip gap 0.5–1.0 mm, chill-roll temperature 20–30 °C, air gap 8–15 cm, and line speeds from 300 m/min to 600 m/min; edge trim regrind is maintained at or below 20 wt% to prevent gel accumulation. Measurement under ASTM D5748 shows that cling force increases with the FLEXOMER fraction, but machine-direction stretch force measured under ASTM D5459 declines when the VLDPE addition exceeds 30 wt%. On production equipment, air gaps above 15 cm at 600 m/min produce neck-in and edge-thickness variation; chill-roll temperatures above 30 °C produce blocking risk on the finished roll. Finished goods include machine and hand pallet wrap, silage bale wrap, and stretch hoods.

Sealant-web extrusion coating and the draw-resonance boundary

To keep seal initiation temperature below 110 °C on high-speed paperboard lamination lines, FLEXOMER VLDPE 2345 is applied in the sealant web at 70–100 wt%, with the balance 0–30 wt% LDPE when melt strength must be increased for drawdown. The coating weight is 15–25 g/m² on aluminium-foil or paperboard substrates. Food-contact status relies on US FDA 21 CFR 177.1520(c) and 21 CFR 175.300 for the applied resinous coating; EU Regulation (EU) No 10/2011 applies with the overall migration limit of 10 mg/dm². The production route is tandem extrusion coating through a 0.5–0.8 mm slot die, melt temperature 260–300 °C, screw 30:1 L/D, line speed 200–400 m/min, and chill-roll temperature 15–25 °C. Draw resonance is the limiting defect: above 350 m/min, neat FLEXOMER VLDPE 2345 on a 1200 mm line has shown oscillating coating-weight bands; adding 20–30 wt% LDPE or lowering melt temperature to 260 °C suppresses the oscillation. Foil substrates require corona pre-treatment to 38–42 dyn/cm before coating to stabilise adhesion. Finished product types include aseptic paperboard carton sealant layers, laminated pouch sealant webs, and coated-lid stock.

Rotational molding of low-temperature agricultural tanks uses FLEXOMER VLDPE 2345 ground to a particle-size distribution of 300–500 µm (35–50 mesh) as a 100 wt% powder; outdoor or coloured molding adds 2–3 wt% carbon black masterbatch or 0.2–1.0 wt% inorganic pigment. Compliance for potable-water contact is evaluated under NSF/ANSI/CAN 61, while REACH Regulation (EC) No 1907/2006 applies to the industrial chemical registration; food-contact tanks are assessed under EU Regulation (EU) No 10/2011 and FDA 21 CFR 177.1520(c). Molding is carried out in a biaxial rotational machine with a 4:1 rotation ratio, oven air temperature 280–320 °C, peak internal air temperature 205–235 °C, and cycle time 18–25 min; cooling uses forced air for 5–8 min followed by water mist. On production lines, peak internal air temperature below 200 °C produces incomplete sintering at corner sections and visible pinholes, while peak internal air temperature above 240 °C accelerates oxidative degradation and lowers environmental stress-crack resistance tested under ASTM D1693. Finished product types include agricultural sprayer tanks, marine buoys, and insulated cold-chain containers.

When FLEXOMER VLDPE 2345 is let down into flexible geomembrane core layers

Flat-die calendering of flexible geomembrane sheet at 1.0–1.5 mm thickness uses 100 wt% FLEXOMER VLDPE 2345 with 2.0–3.0 wt% carbon black masterbatch to achieve the 2.0–3.0% carbon black dispersion measured under ASTM D1603. The relevant performance specification is GRI-GM17 for LLDPE/VLDPE geomembranes, with tensile properties tested under ASTM D6693, notch constant tensile load under ASTM D5397, and oxidative induction time under ASTM D3895. Extrusion processing uses a 150 mm flat-die line with melt temperature 210–240 °C, polishing-stack roll temperature 60–90 °C, and line speed 4–10 m/min to produce sheet 0.5–2.0 mm thick. Seamage is performed by hot-wedge welding at 350–450 °C, with weld speed 1.0–2.5 m/min, and seam peel tested under ASTM D6392; field inspection shows that sustained wedge temperatures above 450 °C cause local sheet thinning and notched failure in the heat-affected zone. The natural resin does not require pre-drying; opened carbon black masterbatch stored above 60% RH should be pre-dried at 80 °C for 2 h to prevent moisture-induced surface defects. The applicational boundary is temperature-dependent: continuous exposure above 60 °C is not recommended because the lower softening point of VLDPE relative to HDPE reduces dimensional stability. Finished product types include landfill lining, canal liners, and decorative ponds.

Medical-device sterile barrier sealant layer formulation

Because peelable sterile-barrier seals must retain seal integrity after gamma irradiation and ethylene oxide sterilisation, multilayer blown or cast film for form-fill-seal applications incorporates 10–30 wt% FLEXOMER VLDPE 2345 in the sealant skin layer, with the remaining 70–90 wt% based on LDPE or LLDPE and the sealant layer thickness set at 15–30 µm. Packaging-system compliance is established under ISO 11607-1:2019 for materials and formed sterile barrier systems, ISO 11607-2:2019 for process validation, and EN 868-5 for paper and film pouch constructions; US FDA 21 CFR 177.1520(c) and EU Regulation (EU) No 10/2011 apply to medical fluid or incidental food contact with the film. Film production runs on coextrusion blown or cast lines at melt temperature 190–230 °C, with die gap 1.0–2.0 mm; subsequent pouch sealing on hospital tray sealers uses sealing temperature 120–140 °C, dwell time 0.3–0.5 s, and pressure 350–550 kPa. Machine validation records show that seal initiation temperature decreases by 8–12 °C when FLEXOMER VLDPE 2345 addition rises from 10 wt% to 30 wt%, but the same increase reduces film modulus sufficiently to require wider seal bars above 400 mm pouch width. Steam sterilisation at 121 °C approaches the upper working limit and requires package stability testing; gamma irradiation at 25–50 kGy is generally compatible. Finished product types include Tyvek-lidded pouches, form-fill-seal pouches, and sterilisation reel stock.