In cast stretch-film converting, MarFlex® 7120S is typically metered through a three-layer flat-die extrusion line with a 0.45–0.7 mm die gap, a 2,000–3,200 mm coat-hanger die, and an air-knife-assisted polished chill-roll stack maintained at 18–25 °C. The resin is allocated to the skin and core layers at 70–85 wt% of total throughput, with 15–30 wt% of a narrower-molecular-weight mLLDPE or an autoclave LDPE used to suppress draw resonance and reduce neck-in; a polyisobutylene cling masterbatch is dosed at 1.0–3.0 wt%, delivering an active cling additive level of 0.5–2.0 wt% in the outer layers. Melt temperature is held between 220 °C and 250 °C because lower temperatures increase die-lip build-up and higher temperatures accelerate oxidative degradation of the polyisobutylene cling component. Draw ratios may exceed 40:1 on cast lines running at 300–600 m/min, and edge trim is re-fed at a maximum of 5–8 wt% to avoid gel specks. Compliance for non-food pallet wrap is assessed under ASTM D5458-08 for cling, ASTM D5748-95(2019) for puncture resistance, ASTM D882-18 for tensile properties, and EU Directive 94/62/EC heavy-metal limits requiring lead, cadmium, mercury, and hexavalent chromium each below 100 mg/kg. Terminal formats include hand stretch film, machine stretch film, pre-stretched cast film, and tinted or printed pallet wrap for logistics identification.

What Happens to Seal Strength When MarFlex® 7120S Is Coextruded with LDPE in Frozen-Food Webs?

A three-layer blown-film line producing frozen-food webs coextrudes MarFlex® 7120S with LDPE at 70–85 wt% 7120S and 15–30 wt% LDPE to stabilize the bubble while preserving low-temperature dart impact. The film is processed through a 1.0–2.0 mm die gap at a blow-up ratio of 2.0–2.8, a frost-line height of 300–700 mm, and a melt temperature of 185–210 °C. Food-contact compliance is established under FDA 21 CFR §177.1520(c) for olefin polymers, with use conditions assigned under 21 CFR §176.170(c), and under EU Regulation (EU) No 10/2011 using overall migration limits of 10 mg/dm² or 60 mg/kg food simulant. Frozen aqueous foods are simulated with simulant A (10% ethanol), while fatty-frozen applications may require simulant D2. Seal strength measured by ASTM F88/F88M-21 typically remains above 2.0 N/15 mm after a 0.5 s dwell at 105–130 °C, but low-temperature seal integrity must be verified at -18 °C because under-stretched LLDPE sealant layers can display brittle peel. Dart impact is assessed under ASTM D1709 Method A, and Elmendorf tear under ASTM D1922-15. Converted products include frozen vegetable pouches, IQF poultry bags, deep-freeze seafood pouches, and ice-cream wrappers.

Stretch Hood Logistics Film and the Sub-250 µm Tear Propagation Threshold

When pallet-load stabilisation film is blown at thicknesses below 250 µm, transverse-direction tear propagation becomes the controlling failure mode, and MarFlex® 7120S is placed in the core layer at 50–70 wt% with 20–35 wt% C6 mLLDPE and 10–20 wt% LDPE. Cling additives are typically omitted because the film is stretched mechanically over the load rather than relying on self-adhesion; slip and antiblock masterbatch is limited to 0.05–0.2 wt% to prevent blocking during storage. The blown-film process uses a 300–600 mm die, a die gap of 1.2–2.4 mm, a blow-up ratio of 2.0–2.6, and a frost-line height of 600–1,200 mm, with internal bubble cooling maintaining air temperature at 10–15 °C. Frost-line deviation greater than ±50 mm causes uneven transverse elongation and can shift the tear-propagation threshold by more than 15%, so automated frost-line control is specified. Mechanical conformance is measured under ISO 527-3:2018 for tensile properties, ASTM D1922-15 for Elmendorf tear, ASTM D1709 Method B for high-energy dart impact, and pallet-load stability is validated under EUMOS 40509. Terminal products include stretch hoods for palletized beverage bottles, chemical drums, building-material units, and white-goods packaging.

Because silage bale wrap must retain a cling seal after twelve months of UV exposure, MarFlex® 7120S is typically blended with LDPE at 75–90 wt% 7120S and 10–25 wt% LDPE, with a UV masterbatch added at 4–8 wt% to achieve 0.4–0.8 wt% HALS active and 1.5–2.5 wt% TiO2 or carbon black. Cling performance is generated by a polyisobutylene or long-chain polybutene masterbatch at 1.0–3.0 wt% in the outer layers. The three-layer blown-film process operates at a blow-up ratio of 2.0–3.0, a die gap of 1.0–2.0 mm, and a melt temperature of 185–220 °C; slit rolls are wound at 500 mm or 750 mm widths for round-bale wrappers. Film is supplied in thicknesses from 25 µm to 150 µm, with the 25–40 µm range used for round bales and thicker gauges used for silage bags and pit silo covers. Regulatory compliance for non-food agricultural film is evaluated under EN 13207:2018, including tensile at break, tear resistance, and accelerated UV aging under ISO 4892-2:2013; REACH SVHC communication obligations apply to the masterbatch components. Terminal products include round-bale silage wrap, silage bags, pit silo covers, and long-term forage storage liners.

Heavy-Duty Shipping Sacks with Form-Fill-Seal Dust Containment

Form-fill-seal shipping sacks for polymer pellet and chemical powder export specify MarFlex® 7120S at 60–80 wt% with 15–30 wt% HDPE for stiffness and 5–10 wt% LDPE for processability; slip and antiblock masterbatch is added at 0.1–0.5 wt%. The blown-film line uses a die gap of 1.5–2.5 mm, a blow-up ratio of 1.8–2.4, a melt temperature of 190–230 °C, and a screen pack of 100–150 mesh to capture oxidized gels. Conformance for industrial packaging is verified by ASTM D1709 Method B dart impact, ASTM D1922-15 tear resistance, and ISO 527-3:2018 tensile properties; dangerous-goods sacks must satisfy the performance tests assigned under the UN Model Regulations by the competent authority. Terminal products include 25 kg FFS pillow pouches, heavy-duty liners for bulk bags, valve sacks, and chemical pellet shipping sacks.

When a Cast PP Sealant Web Is Replaced by an LLDPE Sealant Layer

A cast lamination line that moves from a polypropylene sealant web to an LLDPE sealant layer must recalibrate heat-seal jaw temperature from a typical PP range of 135–160 °C to an LLDPE range of 105–125 °C; MarFlex® 7120S is employed at 70–90 wt% with 10–30 wt% of an ethylene-α-olefin plastomer having density 0.865–0.885 g/cm³ to lower seal initiation and improve hot tack. Slip and antiblock are maintained at 0.05–0.2 wt% to avoid seal contamination. The cast process uses a 0.45–0.7 mm die gap, a polished chill roll at 15–22 °C, and a sealant-layer thickness of 20–50 µm; corona discharge is applied to 38–42 mN/m before lamination against BOPP, PET, or aluminium foil. Seal strength is tested under ASTM F88/F88M-21, hot-tack is assessed under ASTM F1921-18, and food-contact status follows FDA 21 CFR §177.1520(c) and EU Regulation (EU) No 10/2011 with migration limits of 10 mg/dm² or 60 mg/kg. Terminal products include three-side-seal pouches, stand-up pouches, sachets, and lidding films for chilled and dry-food formats.

Coextruded pressure-sensitive masking backings for temporary surface protection are produced by dry-blending MarFlex® 7120S with 10–25 wt% LDPE or an olefin elastomer and processing on a cast line at a melt temperature of 200–230 °C; the draw ratio is kept below 35:1 to minimize machine-direction stiffness that would increase unwinding force. Film thickness is controlled at 20–80 µm, and corona treatment to 38–44 mN/m is applied before a solvent- or water-based acrylic adhesive is coated. Peel adhesion is measured under ASTM D3330/D3330M-04 and ISO 8510-2:2007, with REACH SVHC documentation required for the adhesive and backing system. Published data for the specific combination of MarFlex® 7120S backing and high-solids acrylic adhesive is limited, so coated-roll qualification under production-scale unwind tension and aging conditions is required before shipment. Terminal products include temporary protective film for stainless steel coil, aluminium profiles, polycarbonate sheet, appliance panels, and automotive interior parts.