In blown film extrusion of heavy-duty industrial sacks made from Clearflex® FF 106 A, the exact melt flow rate and density from the current Versalis technical datasheet define the final set-points. The processing ranges below are class-wide for film-grade LLDPE with melt flow rate between 0.9 g/10 min and 1.1 g/10 min at 190 °C and 2.16 kg. For this narrow-molecular-weight linear resin, the die gap is normally set between 1.2 mm and 1.8 mm. The melt temperature at the die lip is held between 190 °C and 220 °C. Temperatures above 230 °C reduce melt strength and increase gel formation. Bubble stability is maintained with a blow-up ratio between 2.0:1 and 2.6:1. Blow-up ratios above 3.0:1 commonly produce bubble oscillation because linear-chain extensional viscosity cannot dampen internal air pressure fluctuations. Frost line height is set between 6 and 9 die diameters to balance quench rate and orientation. The film gauge for heavy-duty sacks ranges from 80 µm to 150 µm. Dart impact resistance is tested according to ASTM D1709 Method A. Tensile properties are measured by ASTM D882. Elmendorf tear resistance is measured by ASTM D1922. On a grooved-feed extruder with 25:1 L/D, barrel temperatures are profiled from 170 °C at the feed zone to 210 °C at the metering zone. Back-pressure is kept below 350 bar to limit shear heating. The processing window for stable bubble geometry is restrictive: a change of ±5 °C in die lip temperature or ±0.3 in blow-up ratio shifts frost line height and creates gauge variation greater than ±8%.

Why Does Cast Film Chill Roll Crystallization Determine Pre-Stretch Uniformity?

In cast film production for pallet stretch wrap, the primary chill roll sets quench rate and crystalline morphology. Chill roll temperature is maintained between 18 °C and 28 °C. Surface temperatures above 35 °C slow nucleation and produce film with lower gloss retention and inconsistent elongation. The melt curtain is extruded through a flat die with a die gap between 0.4 mm and 0.8 mm. The film is pinned to the chill roll by air knife or electrostatic edge pinning. Line speeds for LLDPE cast stretch film normally range from 300 m/min to 600 m/min. Above 600 m/min, draw resonance appears as periodic thickness bands unless edge pinning and melt temperature are adjusted. Final film thickness is typically 12 µm to 30 µm. Pre-stretch ratio on pallet wrappers is set between 200% and 300%. The film must survive this elongation without localized necking. Tensile elongation at break is tested by ISO 527-3. Puncture resistance is measured by ASTM D5748. Cling force between layers is measured by ASTM D5458. When a cling additive is compounded, migration to the surface is time-dependent and temperature-dependent. Equilibrium cling is generally reached only after 24 h of aging at 23 °C. A low chill roll temperature improves clarity but increases internal stress. Subsequent pre-stretch above 250% may initiate transverse micro-tears at the film edges. Published data for this specific configuration is limited; the ranges cited are class-wide for LLDPE cast stretch film.

Sealant webs for flexible packaging laminates use Clearflex® FF 106 A in the seal layer because low seal initiation temperature and adequate hot-tack strength reduce jaw dwell time. A monolayer sealant web or a coextruded structure with a sealant skin of 10 µm to 30 µm is produced by blown or cast extrusion. Heat seal strength is measured by ASTM F88. Hot-tack strength is measured by ASTM F1921. Coefficient of friction is measured by ISO 8295. Seal initiation temperature for LLDPE film grades generally falls between 95 °C and 110 °C. At sealing jaw temperatures above 130 °C, seal strength reaches a plateau but the film becomes susceptible to thinning at the seal root. Slip and antiblock additives are dosed between 500 ppm and 1,500 ppm to control coefficient of friction below 0.25. Higher slip doses reduce friction but can increase migration of erucamide into food simulants. Additive migration in the polymer matrix is controlled by the solubility limit of erucamide in LLDPE; above 1,500 ppm, surface bloom occurs rapidly and reduces seal strength. Compliance is evaluated under FDA 21 CFR 177.1520(c) for olefin polymers and EU Regulation No 10/2011 Annex I. Overall migration limit is 10 mg/dm² under test condition OM2. The following table lists the control points.

When High-Tenacity LLDPE Replaces LDPE in Agricultural Silage Covers

When this film grade is used in silage covers and agricultural barrier films, replacement of LDPE alters tear propagation behaviour and UV stabilizer demand. A silage cover of 150 µm to 250 µm thickness is produced by blown film extrusion. The film is often coextruded with a white outer layer and a black inner layer. Carbon black is added as a UV stabilizer at 1.0 wt% to 2.5 wt%. For non-black greenhouse films, hindered amine light stabilizers are used at 0.2 wt% to 0.6 wt%. Tensile strength and elongation after UV exposure are measured by ISO 527-3. Tear resistance is measured by ASTM D1922. Haze and light transmission are measured by ASTM D1003. The critical operational boundary is UV stabilization. Without adequate hindered amine light stabilizer, film embrittlement can occur within 6 months of high-UV outdoor exposure. LLDPE has lower oxygen barrier than EVOH or PA. Silage films function by restricting air infiltration and maintaining anaerobic conditions rather than by intrinsic oxygen transmission rate. Thickness integrity and puncture resistance therefore carry more weight than gas barrier. Additive compatibility is constrained: avoid brominated flame retardants and certain sulfur-containing stabilizers because they can interfere with hindered amine light stabilizer regeneration. Bubble gauge uniformity must remain below ±10% because thin spots become preferential failure points under wind load. Corona treatment is applied to raise wetting tension to at least 38 mN/m for adhesive tape sealing. Wetting tension is measured by ISO 8296. Published data for this specific outdoor exposure is limited; the listed stabilizer loadings are class-wide for agricultural LLDPE film.

On form-fill-seal bagging lines for polymer pellets, fertilizers, and fine chemicals, seal through dust contamination is the primary reliability variable. Bags made from Clearflex® FF 106 A are filled at rates between 20 bags/min and 30 bags/min. The film must resist puncture from sharp particles and retain seal strength through product contamination. Seal strength is measured by ASTM F88. Puncture resistance is measured by ASTM D5748. Dart impact resistance is measured by ASTM D1709. Film thickness for heavy-duty form-fill-seal bags is generally 100 µm to 180 µm. The critical threshold is dust loading in the seal area. A dust loading above 0.5 mg/cm² can reduce seal strength by more than 40% unless seal bar temperature and dwell time are increased. Seal bar temperature is typically set between 120 °C and 150 °C. Dwell time is set between 0.5 s and 1.5 s. Seal pressure is set between 2 bar and 4 bar. Coefficient of friction must be maintained between 0.20 and 0.35. Below 0.20 the bag may slip during transfer. Above 0.35 the bag may jam in the fill spout. If slip additive exceeds 1,500 ppm, seal strength may drop below the minimum required for 50 kg bag drop resistance. Bag drop performance is tested by ISO 7965-1.

Stretch Hood, Collation Shrink, and Secondary Packaging Mechanical Abuse Requirements

In secondary packaging, Clearflex® FF 106 A is used where pallet containment and load retention are governed by stiffness, puncture resistance, and stretch or shrink recovery. Stretch hood film thickness ranges from 80 µm to 120 µm. The film is stretched on automatic stretch hood equipment at a stretch ratio between 55% and 85%. Recovery force after stretching is evaluated by tensile stress retention or by ISO 14616 for shrink force. Puncture resistance is measured by ASTM D5748. Tear propagation resistance is measured by ASTM D1922. For collation shrink film, LLDPE is blended with LDPE to control shrink tension and seal temperature. Shrink temperature for LLDPE-containing collation film is generally between 120 °C and 150 °C. Above 160 °C, the film tends to melt-seal to itself and create machine waste. The main processing conflict is orientation memory: LLDPE has a narrow re-crystallization window, and unbalanced machine-direction/transverse-direction orientation leads to curl. Film curl above 5 mm per linear metre disrupts automatic sleeve application. Gauge uniformity should be held within ±8% to avoid non-uniform recovery force distribution. Mechanical properties are evaluated by ASTM D882 for tensile modulus and ASTM D1922 for tear resistance. Published data for this specific grade in stretch hood configuration is limited; the ranges are class-wide for LLDPE-based secondary packaging films.