ATTANE 4401 is an ethylene-octene very low density polyethylene with a density of 0.904 g/cm³ determined by ASTM D792-20 and a melt mass-flow rate of 1.0 g/10 min at 190 °C and 2.16 kg per ASTM D1238-20, Procedure A. The differential scanning calorimetry peak melting temperature is approximately 122 °C at a heating rate of 10 °C/min per ASTM D3418-21. The low crystalline fraction alters low-temperature toughness, heat-seal response, cling generation, and mineral-filler acceptance. Downstream processing is concentrated in cast and blown film, sealant webs, heavy-duty liners, stretch hood film, and halogen-free compound. The scenarios below separate these uses by layer structure, machine settings, test standards, and terminal article geometry.

What Limits Puncture Propagation in Cast Machine Stretch Film?

Cast machine stretch film lines running ATTANE 4401 position the resin in the core or skin layers to increase puncture resistance and cling without reducing line speed. On a three-extruder cast line with 75 mm extruders, 30:1 L/D barrier screws, and a 2,000 mm slot die with 0.7 mm lip gap, the melt temperature is held between 250 °C and 280 °C. The air gap is set at 80–120 mm, and the chill roll is kept at 18–24 °C. A starting skin layer formulation is 70 wt% ATTANE 4401 with 30 wt% of a 0.917 g/cm³ octene LLDPE and 1.0 wt% cling masterbatch. Film puncture resistance is measured by ASTM D5748-19 with a 1.0 in probe at 250 mm/min. Cling force after 40 h conditioning at 23 ± 2 °C is measured by ASTM D5458-95(2012). If melt temperature exceeds 285 °C, oxidative degradation of the low-crystallinity skin reduces cling force and deposits gel specks on the roll. Line speeds below 250 m/min increase neck-in, while speeds above 450 m/min may initiate draw resonance unless edge pinning and die-lip temperature are tightly controlled. Terminal rolls are 10–30 μm film used in pre-stretch hand wrap and machine wrap.

Wind-up tension profile is tapered from 120 N/m at core to 60 N/m at 400 mm roll diameter because the low-density skin continues to relax during storage. A line-speed increase from 250 m/min to 450 m/min raises shear heating in the extruder melt film. Barrel zones are therefore held at 190 °C in the feed section and 260 °C at the metering section to limit melt temperature overshoot. Pre-stretch performance is screened by force ratios derived from ASTM D5458-95(2012) on a laboratory peel tester with 300 mm/min draw. When the skin layer contains more than 30 wt% cling masterbatch, roll blocking occurs during storage at 40 °C. Blocking is detected by coefficient of friction per ASTM D1894-14 and unwind force per ASTM D5458-95(2012).

On a three-layer blown film line equipped with 75 mm grooved-feed extruders and a 300 mm die, ATTANE 4401 is used in the core or skin layer of frozen vegetable and seafood packaging. The die gap is set to 1.4 mm, the blow-up ratio is held at 2.6:1, and the frost line is positioned 500–700 mm above the air ring. Die melt temperature is controlled at 200–220 °C; lower temperatures reduce odour development in food-contact film. The collapsing frame and nip speed are adjusted to maintain gauge variation below ±5% on a 50 μm film. Low-temperature impact resistance is evaluated by ASTM D1709-16a Method A after 24 h conditioning at −20 °C. Seal strength is generated on a laboratory jaw sealer at 120 °C, 0.3 MPa, and 0.5 s dwell, and measured by ASTM F88/F88M-21. The seal initiation temperature of the VLDPE layer is 8–12 °C lower than that of a 0.918 g/cm³ LLDPE of similar melt index, which reduces heat-up time on packaging lines. If ambient relative humidity exceeds 70%, granules are pre-dried at 80 °C for 2 h to prevent moisture streak defects. Terminal products include pillow bags, gusseted bags, and lidding film for frozen ready meals.

The food-contact film formulation avoids additive packages that raise overall migration above 10 mg/dm² under EN 1186-1 with 10% ethanol at 40 °C for 10 days. Production-scale bubble failures on this resin appear as sagging between the air ring and frost line when the extruder throughput exceeds 150 kg/h per die. The melt strength of the 0.904 g/cm³ fraction requires a lower melt temperature or a higher frost line to restore bubble symmetry. Reverse-side seal strength remains stable at 115–125 °C, but dwell times below 0.3 s produce weld failures in high-speed vertical form-fill-seal machines.

High-dart liners require low crystallinity, not simply molecular weight.

Heavy-duty sack and FIBC liner film uses ATTANE 4401 in the middle layer of a three-layer structure to increase line-speed toughness without raising film density. A production blown-film line with 90 mm extruders and a 350 mm die runs the VLDPE layer at 30 wt% between two HDPE-rich skins. The die gap is widened to 1.8 mm, the blow-up ratio is lowered to 2.0:1, and the frost line is moved to 700–900 mm to relax machine-direction orientation. Dart impact is measured by ASTM D1709-16a Method B on 80 μm film. Elmendorf tear is measured by ASTM D1922-15 in both machine and transverse directions. Low-temperature puncture at −20 °C is determined with ASTM D3763-18 using a 12.7 mm hemispherical striker. The lower crystallinity of ATTANE 4401 shifts brittle failure to lower temperatures; however, the same density reduction lowers yield strength in load-bearing applications. Any replacement of HDPE by VLDPE beyond 40 wt% must be qualified by compression testing per ASTM D642 on the finished sack. Terminal articles include drum liners at 100–150 μm, box liners at 80–120 μm, and FIBC inner liners at 80–100 μm.

Edge trim and start-up scrap from the VLDPE-containing liner are re-introduced at up to 20 wt% regrind. This practice must not exceed 20 wt% because the HDPE skins and the low-crystallinity core generate melt-flow instability at the layer interface when the regrind fraction is too high.

When laminators replace a conventional LLDPE sealant web with ATTANE 4401 in three-layer PE or in foil/PE laminations, the lowest melt crystallization component in the structure becomes the sealing interface. The sealant layer is extruded at 20–40 μm onto aluminium foil or primed polyester on a tandem extrusion lamination line with a 1,200 mm slot die and an air gap of 100 mm. Heat seal curves are generated on a laboratory gradient heat sealer with 25 mm heated bars, 0.5 MPa jaw pressure, and 0.5 s dwell, following ASTM F2029-16 for specimen preparation and ASTM F88/F88M-21 for seal strength. Hot tack is evaluated by ASTM F1921-12 using a 200 N load cell and a seal speed of 200 mm/s. The VLDPE seal initiation window is 8–12 °C lower than that of a 0.918 g/cm³ octene LLDPE. This allows form-fill-seal lines to reduce dwell time and raise cycle speed without sacrificing hermeticity. Finished pouches are tested for leak integrity by ASTM F2096-11 at 10 kPa internal pressure. Terminal formats include stand-up pouches for coffee, spouted pouches for liquid detergent, and medical device header bags.

Extrusion lamination with ATTANE 4401 at low coat weights below 20 μm requires a minimum adhesion tie layer of 2 μm ethylene-acrylic acid or ethylene-methyl acrylate because the non-polar VLDPE surface does not anchor directly to foil without a polar layer. When the sealant layer is used in medical packaging, the substrate is tested for microbial barrier per ASTM F1608-16 after porous closure. This provides quality assurance for terminal device header bags.

If a 0.904 g/cm³ density base is selected for mineral-filled cable compound

Because the crystalline fraction in ATTANE 4401 is lower than in conventional LLDPE, the resin is used as a base polymer for low-smoke zero-halogen cable sheathing. On a co-rotating twin-screw extruder with 44:1 L/D and 12 barrel zones, polymer is fed into barrel 1 at 180 °C; magnesium hydroxide or alumina trihydrate is side-fed at barrel 5 at 150–200 phr. Screw speed is held at 300–400 rpm and melt temperature at the die is kept below 200 °C to prevent filler dehydration. The compound is pelletised through a strand die with 3 mm holes. Tensile properties are measured on 1 mm pressed plaques per ASTM D638-14 Type IV. Thermal ageing is performed for 168 h at 100 °C in an air-circulating oven per IEC 60811-401. Low-temperature bending at −25 °C is evaluated by IEC 60811-504. The terminal product is halogen-free flame-retardant insulation for 600 V instrumentation and control cable; published data for this specific resin-filler ratio remain proprietary to compounders.

Stretch hood film: low-temperature elastic recovery under MD restraint

Stretch hood machines apply biaxial elongation to the film at cold storage temperatures down to −10 °C. ATTANE 4401 is incorporated as the core layer of a three-layer blown film at 40–60 wt%. The die gap is 1.6 mm, the blow-up ratio is 2.0:1, and the frost line is set at 600–800 mm above the air ring. Film thickness is 80–120 μm. Elastic recovery is measured by ASTM D5459-02 using a 100% extension hold cycle. Dart impact is measured by ASTM D1709-16a Method B after 24 h conditioning at −20 °C. Elmendorf tear per ASTM D1922-15 is balanced between machine and transverse directions by changing die gap and frost line; machine-direction tear resistance is kept above the transverse value to prevent zippering at the pallet corners. Lower crystallinity improves folding at the corner film gathers, but it also increases creep under sustained load. Terminal products include pallet covers for beverage trays, building materials, and white goods.

Surface protection films coextruded on a cast line at 800 m/min line speed use ATTANE 4401 in the core layer between two low-crystallinity skin layers loaded with anti-static additive. The core is 30–40 μm and the skins are 5–10 μm, giving a total gauge of 40–60 μm. Corona treatment raises the surface energy to 42–46 mN/m measured by ISO 8296 before the adhesive coating station. Secant modulus at 1% strain is measured by ASTM D882-18. Elongation at break measured by ASTM D882-18 exceeds 500% for the uncoated substrate. Peel adhesion from stainless steel is measured by ASTM D3330/D3330M-04 Method A after 24 h dwell. The low density of the resin reduces bending stiffness, allowing the film to follow recessed contours on automotive body panels at 23 °C. When application temperature is below 10 °C, the film is preheated to 35 °C to avoid crease formation. Terminal uses include temporary protection of automotive painted surfaces, stainless steel sheet, and electronic enclosure windows.