In cast stretch film for pallet unitization, ATTANE SL4100G is delivered from bulk silos through a gravimetric blender to a single-screw extruder with 30:1 L/D ratio and a barrier screw designed for VLDPE. The resin has nominal density 0.912 g/cm³ and melt flow rate 1.0 g/10 min at 190 °C under 2.16 kg, measured according to ISO 1183-1:2019 and ISO 1133-1:2022. The melt is fed to a coat-hanger die with die gap 0.45–0.80 mm; line speeds above 500 m/min require an air knife and vacuum box to stabilize the web before the matte chill roll. A production formulation for ULDPE-based stretch film typically contains 70–80 wt% SL4100G and 20–30 wt% of a hexene- or butene-based LLDPE; the LLDPE component raises elastic recovery and stretch force while the VLDPE contributes puncture resistance and cling. Film thickness is controlled at 15–23 µm by chill roll speed and die lip adjustment. Chill roll temperature is held at 18–24 °C to minimize blocking; edge trim is recycled through a fluff feeder at up to 15 wt% without causing melt uniformity loss. Puncture resistance is measured by ASTM D5748-95 (2019), cling by ASTM D5458-95 (2020), coefficient of friction by ASTM D1894-14, and tensile behavior by ASTM D882-18. Process temperatures from feed throat to die are set between 180 °C and 260 °C; operation above 280 °C should be avoided because molecular weight degradation can raise gel count and reduce dart impact. If pellets are stored in unheated warehouses below 10 °C and moved into a warm production bay, condensation on pellet surfaces can cause bubble defects in cast film; pre-warming or controlled silo residence is required above 60% relative humidity. For indirect food packaging or industrial pallet wrap, REACH Regulation (EC) No 1907/2006, Article 33 SVHC communication and Packaging and Packaging Waste Directive 94/62/EC heavy metal limits for lead, cadmium, mercury, and hexavalent chromium to 100 ppm aggregate are typically required.

How Does Low-Seal-Temperature Performance Affect Vertical Form-Fill-Seal Throughput for Frozen Food Pouches?

Vertical form-fill-seal lines for frozen vegetables, seafood, and ice cream require a sealant web that forms a stable seal before the fill product cools the seal area. SL4100G is used in the inner sealant layer of a three-layer blown film structure; a representative layer ratio is 25–35% sealant, 5–8% tie, and a barrier core of EVOH at 8–12%, with the remainder an outer LLDPE or LDPE. The sealant layer blend is 60–80 wt% SL4100G with 20–40 wt% LDPE; the LDPE diluent raises melt tension for bubble stability and lowers the backpressure on the inner extruder. Because SL4100G has a lower seal initiation than conventional LLDPE, VFFS converters report cycle time reduction when seal bar temperature is 15–25 °C lower at equivalent dwell time. Seal strength is measured according to ASTM F88/F88M-21 after specimens are conditioned at -18 °C and 23 °C; hot tack force is measured with ASTM F1921/F1921M-18 at 100 °C and 150 °C. Blown film processing conditions for the sealant layer include die melt temperature 190–220 °C, blow-up ratio 2.0:1–2.5:1, and frost line height 8–12 die diameters. Food-contact compliance for the sealant layer follows FDA 21 CFR 177.1520(c)3.2a and EU Regulation (EU) No 10/2011 with overall migration below 10 mg/dm². Terminal products include frozen food pouches, ice cream bags, and seafood IQF films. The EVOH barrier requires an anhydride-grafted polyethylene tie layer; insufficient tie layer thickness below 5% of total gauge can lead to interlayer delamination under freezer flex-cracking.

Blown film extrusion for heavy-duty industrial sacks uses SL4100G as a toughness modifier in the core or inner layer of a three-layer coextrusion. Barrel temperature profiles are set between 190 °C and 230 °C for VLDPE to avoid over-shear in the metering section; die melt temperature is maintained below 235 °C to prevent flow instability at high backpressure. Blow-up ratio is held at 2.0:1–2.5:1, and frost line height is adjusted to 8–12 die diameters. The blend ratio ranges from 35–50 wt% SL4100G with 50–65 wt% hexene LLDPE or HDPE, depending on sack stiffness and stacking strength requirements. Terminal products include flexible intermediate bulk container liners, chemical export sacks, and construction aggregate bags. Impact resistance is checked by ASTM D1709-15 Method A/B; Elmendorf tear is measured by ASTM D1922-15; environmental stress crack resistance is measured by ASTM D1693-15 at 50 °C with 10% Igepal CO-630. Flexible intermediate bulk container liners must be evaluated against UN Model Regulations Chapter 6.5 where dangerous goods transport is involved. The main processing constraint is that high-shear screw sections can generate excessive melt temperature and surface defects; therefore, grooved feed extruders with moderate compression ratios produce more stable film than high-compression LLDPE screws.

Extrusion Lamination Sealant Webs for Liquid Stand-Up Pouches

Liquid stand-up pouch lamination places the sealant web in direct contact with aggressive product formulations, so surface cleanliness and seal integrity are controlled more tightly than in dry food packaging. SL4100G is used as a cast sealant layer at 30–60 µm thickness, either coextruded onto a primary web or extrusion-coated through a flat die at melt temperature 260–280 °C. For aluminium foil adhesion, an ethylene-acrylic acid tie resin and ozone treatment are common; for metallized polyester, an adhesion promoter or primer may be required. The sealant blend is 70–90 wt% SL4100G with 10–30 wt% mLLDPE to adjust hot tack and seal strength under contaminated seal conditions. Heat sealability is characterized by ASTM F2029-00; seal strength is measured by ASTM F88/F88M-21 after lap-seal preparation at 140–160 °C, 1.0 s dwell, and 0.28 MPa jaw pressure. Bond strength to foil or polyester is measured by ASTM D1876-08 with 180° peel at 50 mm/min. Migration compliance is governed by EU Regulation (EU) No 10/2011 with the overall migration limit of 10 mg/dm²; specific migration of additives must be verified against the positive list. Terminal products include refill pouches for edible oil, liquid detergent, and commercial cleaning concentrates. Slip and antiblock masterbatches must be selected for lamination; high levels of migratory erucamide above 500 ppm in the sealant surface can lower bond strength and increase seal contamination during high-speed pouch conversion.

Agricultural stretch film for round bale silage is produced by three-layer cast coextrusion with a layer ratio of 10%/80%/10%. The core layer contains 80–90 wt% SL4100G for puncture resistance and retention after field exposure; the skin layers contain LLDPE or EVA and a polyethylene-based tackifier masterbatch to provide adhesion to the wrapped bale. Film thickness is controlled at 25–40 µm. Holding force and stretch force are measured according to EN 13206:2017 for thermoplastic stretch films intended for sealing bales. Puncture resistance is measured by ASTM D5748-95 before and after accelerated weathering according to ISO 4892-2 cycle; UV stabilization with HALS is mandatory because unprotected VLDPE loses impact properties after outdoor weathering. Oxygen transmission rate of the planar film is measured by ASTM D3985-17 at 23 °C and 0% relative humidity; increased wrap layers from 4 to 6 reduce oxygen transport at the bale surface. Published data for this specific resin grade under long-term silage acid contact is limited; converters must test bag leakage and mechanical retention with their specific silage inoculant and UV additive package.

When Gamma Sterilization Is Not Selected for Medical Device Overwrap

For medical device overwrap and sterile barrier pouches, SL4100G can be processed as a monolayer or coextruded cast film. The film is converted into lidding webs or pouches with Tyvek or medical-grade polyester. Because terminal sterilization is part of the converter’s validation burden, the choice of ethylene oxide over gamma irradiation is driven by oxidative stability. Ethylene oxide sterilization is preferred for this resin grade; gamma doses above 25 kGy may induce oxidative degradation and reduce tensile impact in polyethylene films unless a custom stabilizer system is validated by the converter. Film thickness is typically 40–80 µm. Tensile properties are measured by ISO 527-3:2018; seal strength of the finished pouch is checked according to ISO 11607-1:2019 and ASTM F88/F88M-21. Biocompatibility data are generated by the converter according to ISO 10993-5 and ISO 10993-10; the resin supplier does not provide USP <88> Class VI certification for this grade. The film can be blended with 10–20 wt% mLLDPE to increase dart impact while maintaining clarity; however, high mLLDPE content above 30 wt% can narrow the sealing window and raise seal initiation. Cleanroom film extrusion requires low gel counts and controlled handling; automatic surface inspection is used to reject film with gels above 100 µm. Published data for the specific configuration of this grade under high-dose gamma sterilization is limited.

Stretch Hood Film Retention Forces Decrease When Chill Roll Pinning Is Inadequate

Stretch hood film lines require stable neck-in control because SL4100G has a low melting point near 123 °C and low zero-shear viscosity compared with conventional LLDPE. The cast film line is configured with a 1.0–1.5 mm die gap, air knife pressure of 0.02–0.05 MPa, and electrostatic pinning to force the melt onto the chill roll. The film is produced at 80–120 µm thickness with a blend ratio of 50–70 wt% SL4100G and 30–50 wt% LLDPE to balance elongation at break and holding force. Holding force and stretch force are measured according to EN 13206:2017 or ISO 527-3:2018 at 200 mm/min crosshead speed. Unstable chill roll pinning produces transverse thickness variation above ±5%, which causes edge tear and uneven hooding on palletized building materials. Terminal products include stretch hoods for brick, ceramic tile, and white goods. When exported to the EU, stretch hood film is classified as packaging and must conform to 94/62/EC heavy metal limits. The main operational boundary is the low melt temperature; running at melt temperature above 280 °C can produce die-lip build-up and gel specks in thicker gauges. When low air knife pressure is used, the neck-in may exceed 20 mm per side, causing gauge loss at the film edge. Published data for this specific configuration at different line speeds is limited; converters must verify transverse gauge stability with their own pinning equipment.