LyondellBasell Icorene 3560 BWN 8906 SF is classified as a linear low density polyethylene film resin. The full designation contains three information groups: the Icorene product family, the 3560 grade identifier, and the BWN 8906 SF packaging/campaign suffix. In currently available product literature, the SF suffix is associated with a surface-friction or slip-additive formulation, but the exact amide or inorganic species, carrier resin, and loading are not identified in this document and must be read from the LyondellBasell Technical Data Sheet, Safety Data Sheet, and regulatory information for the specific production lot. Acceptance-tested values for density and melt-mass flow rate should be established under ISO 1183-1:2019 and ISO 1133-1:2022. Because the resin is a linear low density polyethylene, the principal comonomer may be butene, hexene, or octene. This structural variable influences tensile elongation, tear propagation, dart impact, and seal performance, so conversion trials should not rely solely on melt index and density when replacing an existing film grade. Published data for this specific configuration is limited, and no inference regarding comonomer type, stabiliser system, or additive loading should be drawn from the suffix alone.

Film extrusion window and screw-selection constraints

For blown-film processing, the grade should be evaluated on a single-screw extruder with a length-to-diameter ratio between 24:1 and 30:1, a barrier screw with a Maddock mixing section, and a screen pack of 40–80 mesh. These ranges are common for linear low density polyethylene, but the exact screw profile must be matched to the resin’s shear-viscosity curve and the die’s pressure drop. A grooved-feed extruder can increase throughput, but it also raises melt-pressure sensitivity and may require higher drive torque. If the feed-zone temperature exceeds the pellet-softening point, the resin can form a molten film on the grooved bush and reduce conveying stability. At relative humidity above 60%, pre-drying is generally unnecessary for polyethylene if the pellets are stored in sealed containers; however, surface moisture introduced from open silos can produce irregular feed and bubble pumping, so the feed throat should be kept at a low temperature and the hopper should not be vented directly to humid plant air.

The melt-temperature profile is a critical boundary. Linear low density polyethylene film grades are commonly extruded at barrel temperatures from 190°C to 230°C, with die temperatures held at 200°C to 230°C. The upper limit is not a single universal value; it is defined by the grade’s oxidation sensitivity and the additive package. Running above the Technical Data Sheet upper melt-temperature limit can produce gel particles, yellowing, and a reduction in dart-drop impact when tested under ASTM D1709-22. Running below the lower limit increases melt viscosity, raises backpressure, and can trigger high shear-stress sharkskin at the die exit. On cast-film lines, similar thermal boundaries apply, but the die gap and draw-resonance limit differ because linear low density polyethylene has a lower strain-hardening character than high-pressure low density polyethylene.

Bubble geometry on a blown-film tower is a process conflict zone. Linear low density polyethylene bubble stability is generally lower than that of high-pressure low density polyethylene because linear backbones lack the same long-chain branching network. Die gap in the range 0.8–2.0 mm and blow-up ratio between 2.0 and 3.0 are typical for linear low density polyethylene, but the operating point must be selected by observing frost-line height, layflat gauge variation, and edge wrinkle. A layflat gauge variation above ±5% indicates unstable bubble geometry or non-uniform die melt distribution. If the grade is run at too high a frost line, lamellar orientation and surface crystallinity can change, altering tear strength, haze, and sealing behaviour. Tear properties should be assessed by ISO 6383-2:2004 or ASTM D1922-23, and haze by ASTM D1003-21.

Because the SF suffix indicates a surface-friction modification, the coefficient of friction is not a fixed resin property; it depends on additive migration, surface post-treatment, and film ageing. Film samples should be conditioned for at least 24–48 h at 23°C ±2°C and 50% ±10% RH before testing. Kinetic coefficient of friction should be reported using ASTM D1894-14 or ISO 8295:2004. Values measured immediately after winding or after corona treatment may differ from the stabilised value. Corona treatment can raise surface energy and improve print and adhesive anchorage, but it can also volatilise or oxidise slip additives, causing friction recovery over time. Surface energy should be verified with ISO 8296:2003; a treated film’s shelf stability and seal performance should be re-qualified if corona dosage is changed.

Rheological characterisation under ISO 11443:2021 or ASTM D3835-16 in capillary mode is useful for predicting extruder backpressure. Linear low density polyethylene grades typically show a relatively flat shear-thinning response compared with high-pressure low density polyethylene. Apparent viscosity at shear rates of 10^2 s^-1 to 10^4 s^-1 is material-specific and must be taken from the supplier’s viscosity curve. Melt strength measured on a dedicated tension unit shows the reduced strain-hardening behaviour of linear low density polyethylene compared with high-pressure low density polyethylene. This lower strain-hardening response explains the narrower bubble-cooling window and the need for a lower frost line in many blown-film operations. The 3560 identifier must not be read as a melt index or density value without the supplier’s published grade-nomenclature key.

Substitution of this grade into an existing high-pressure low density polyethylene formulation requires a systematic comparison rather than a one-to-one die-gap adjustment. Because linear low density polyethylene has a higher zero-shear viscosity and lower elongational strain hardening, the same extruder screw may generate higher backpressure while producing lower melt strength after the die. The die gap commonly must be widened relative to high-pressure low density polyethylene to reduce shear stress and raise bubble stability, but widening the gap changes shear history and can alter molecular orientation. Processing-aid addition is generally not required unless high-shear surface defects appear, but any external lubricant or fluoropolymer processing aid should be tested for interaction with the SF additive package using coefficient-of-friction and heat-seal tests before production approval.

How does this grade compare with high-pressure LDPE and the broader linear-low-density class?

At the molecular level, high-pressure low density polyethylene contains a statistical distribution of long-chain branches formed during free-radical polymerisation at pressures above 150 MPa. Linear low density polyethylene is synthesised at lower pressure using a coordination catalyst; the backbone is predominantly linear with short-chain branches introduced by the comonomer. The short-chain branch frequency and distribution depend on comonomer type. Butene-based linear low density polyethylene usually has shorter and more frequent side branches than hexene- or octene-based grades; this can translate into different dart-impact, tear, and low-temperature sealing characteristics. Comparative performance must be established by conversion trials using the same film gauge, die gap, and blow-up ratio.

The replacement of high-pressure low density polyethylene by linear low density polyethylene often improves tensile elongation, puncture resistance, and tear strength, but reduces melt strength and optical gloss. These effects are measured by ISO 527-3:2018 for tensile film properties, ASTM D5748-19 for puncture resistance, and ASTM D2457-21 for gloss. However, the direction of any property shift is density-dependent and comonomer-dependent; no universal numerical comparison should be inferred from the product name alone. A film converter should obtain the Technical Data Sheet and Certificate of Analysis values for the specific lot, then run comparative flat-width trials on the intended blown-film line to verify output, bubble stability, and mechanical properties.

Regulatory qualification for food-contact and pharmaceutical packaging is application-specific. A polyethylene base resin may be supplied with a statement of compliance to 21 CFR 177.1520, EU Regulation (EU) No 10/2011, or other national food-contact requirements, but the formulated SF additive package must be evaluated separately. The final packaging article, not the resin alone, is responsible for meeting overall migration, specific migration, and organoleptic limits. Industrial converters should request the current regulatory cover letter and validate that the product’s specific campaign code BWN 8906 SF does not differ from the certified formulation in the supply chain documentation.

Handling and storage limits apply. The resin should be stored in a dry, uncontaminated area at temperatures below 40°C and protected from direct ultraviolet exposure. Polyolefins are not highly hygroscopic, but hopper condensation can form when cold pellets are transferred into a warm, humid plant atmosphere. If storage at relative humidity above 60% is unavoidable, the material should be kept in sealed metal or conductive plastic containers to avoid surface moisture pickup. Static discharge can occur during pneumatic conveying; grounding of transfer lines and bins is required to prevent dust explosions. Bulk density and pellet geometry affect conveying and blending. Inconsistent pellet size or excessive fines can cause screw-feed variation and melt-pressure fluctuation, so fines content should be monitored by the site’s incoming quality control plan.

Within the broader linear low density polyethylene class, the main differentiators are comonomer type, additive package, and stabilisation package. The specific grade code 3560 BWN 8906 SF should not be considered interchangeable with unmodified linear low density polyethylene film resins or with high-pressure low density polyethylene grades. The presence of a slip/antiblock package changes the coefficient of friction, blocking force, and heat-seal hot-tack behaviour. Blocking force should be measured by ASTM D3354-15; hot tack may be evaluated by ASTM F1921-20 or instrument-specific methods. If the SF package is not required, an unmodified base-resin equivalent may provide lower surface haze and higher clarity, but may fail on high-speed form-fill-seal lines due to excessive friction and web-tracking problems.

For applications requiring high melt strength in deep-draw thermoforming, heavy-wall sheet, or large-part blow moulding, this linear low density polyethylene grade is not a direct substitute for high-pressure low density polyethylene. The linear backbone lacks the strain-hardening required for those geometries. In oriented film and heavy-duty sack film, blending with high-pressure low density polyethylene is often used to balance bubble stability and mechanical strength. Blend ratios must be experimentally determined and tested according to the property standards listed above.