Marlex® 7104 LLDPE is specified for flat-die sheet extrusion lines in which low-temperature puncture resistance, weldability, and melt stability operate as co-dependent variables. On sheet lines from 1.2 m to 3.0 m die width, the melt temperature band is maintained at 210°C–240°C; chill-roll temperatures below 55°C produce surface haze, and temperatures above 85°C increase roll-face blocking. The downstream scenarios below are separated by formulation objective, conversion equipment, and end-use compliance boundary, not by generic polyethylene type.

When 1.5 mm Geomembrane Sheet Is Run on a 2.4 m Flat-Die Line

Marlex® 7104 is loaded at 95.0–97.5 wt% in black geomembrane sheet, with carbon black masterbatch metered to hold final carbon black at 2.0–3.0 wt% as required by GRI-GM13 and the oxidative resistance clauses of ASTM D5397. On a 2.4 m coat-hanger die fed by a 30:1 L/D single-screw extruder, melt temperature at the die lip is kept at 210°C–240°C, and polished chill rolls are held between 65°C and 85°C; chill-roll temperature drift greater than ±3°C is associated with transverse gauge bands above 0.05 mm. The converter-side additive system meters antioxidant masterbatch at 0.10–0.30 wt%; hindered phenolic/phosphite architecture is used to maintain oxidative induction time above 100 min at 200°C under ASTM D3895. Mechanical certification for a 1.0 mm sheet normally references ASTM D638 tensile yield at or above 11 MPa, ASTM D1004 tear strength at or above 45 N for 0.75 mm sheet, ASTM D4833 puncture resistance at or above 240 N for 1.0 mm sheet, and ASTM D5397 notched constant tensile load of at least 400 h. Edge-trim regrind is limited to 20 wt% because each heat history lowers oxidative induction time by 15–25 min per pass; when regrind exceeds 20 wt%, the antioxidant masterbatch must be re-dosed upward and the batch re-qualified. Carbon black above 3.5 wt% reduces wedge-weld peel strength below 80 N/cm under ASTM D6392 because the viscosity rise slows interdiffusion across the weld plane. Terminal products include landfill base liners, landfill cap sheets, heap leach pads, evaporation pond liners, wastewater lagoon covers, and double-containment sump liners.

Food-contact sheet extrusion based on Marlex® 7104 typically blends the resin with 15–30 wt% LDPE or 5–15 wt% HDPE to improve thermoforming melt strength and die-cutting rigidity. The resin blend is metered with slip/antiblock masterbatch at 1.0–2.0 wt%, yielding final erucamide concentrations of 300–800 ppm and synthetic silica concentrations of 500–1200 ppm; these additives reduce film-to-film blocking during roll winding and assist vacuum-forming release. Compliance under FDA 21 CFR 177.1520(c) paragraphs 3.1a and 3.2a covers olefin polymers for direct food contact, while EU harmonized testing is performed according to Regulation (EU) No 10/2011 Annex III and Annex V with simulant D1 for fatty foods and simulant A for aqueous foods. On a flat-die sheet line with 0.25–0.80 mm die gap, melt temperatures are kept at 205°C–230°C, and the cast sheet exits into a three-roll stack with roll temperatures of 55°C–75°C to balance surface gloss against post-trim shrinkage. Downstream thermoforming uses plug-assisted pressure/vacuum stations at sheet surface temperatures between 115°C and 130°C; cycle times for shallow trays are 3–8 s, with plug speed limited below 250 mm/s because Marlex® 7104 begins to exhibit draw-induced thinning at higher plug displacement rates. Terminal products include low-temperature frozen food trays, ice cream cup lids, fresh produce punnets, and thin-walled dairy portion cups that require sub-zero impact toughness rather than hot-fill resistance. The operational boundary is fixed: continuous exposure above 65°C or hot-fill pasteurization above 75°C is outside the product envelope because the Vicat softening point of the sheet falls below the thermal load exerted by steam or immersion retort. Edge-trim regrind is constrained to 15 wt% in food-contact layers unless migration testing is repeated, because variability in contaminant carryover from post-industrial scrap can invalidate the compliance declaration.

Can 0.25 mm Underslab Vapor Retarder Meet ASTM E1745 Class A After Post-Consumer Regrind Dilution?

The formulation for underslab barrier sheet is maintained at 96.0–98.0 wt% Marlex® 7104, 2.0–3.0 wt% carbon black masterbatch, and 0.10–0.20 wt% hindered phenolic/phosphite stabilizer masterbatch; the carbon black concentration is set not for UV resistance but for opacity and pinhole visibility during installation. Flat-die extrusion at 0.20–0.50 mm thickness uses melt temperatures of 210°C–240°C and chill rolls at 60°C–80°C, after which the web is slit to 2.4–6.0 m panels. Under ASTM E1745, Class A requires water vapor permeance no greater than 0.1 perm when tested by ASTM E96 desiccant method at 23°C and 50% RH; tensile strength and puncture resistance are measured by ASTM D882 and ASTM D1709 respectively, and the sheet must retain these values after conditioning. The use of post-consumer regrind is not automatically excluded but is limited to 10 wt%; at higher addition, the melt flow index drift across the die can exceed 0.15 g/10 min, creating microtears that raise water vapor transmission above the 0.1 perm limit. Terminal products are underslab vapor retarders, radon barriers, crawl space liners, foundation protection layers, and below-grade waterproofing membranes. The product is not designed for direct UV exposure beyond 30 days unless a separate UV-stabilized cap layer is added to the sheet structure.

Within agricultural sheet conversion, black/white coextrusion positions Marlex® 7104 in the black core and black skin layers, where the resin is diluted to 96.0–97.0 wt% with a carbon black masterbatch targeting 2.0–3.0 wt% carbon black. The white layer is a separate LLDPE/LDPE blend loaded with 5–8 wt% TiO₂ masterbatch; total thickness for silage clamp covers is 0.10–0.25 mm, while 0.20–0.50 mm sheet is converted into greenhouse blackout and ground-cover applications. UV stabilization uses 0.30–0.60 wt% high-molecular-weight HALS masterbatch in the outer layers because sheet exposed to more than 800 h of QUV-A under ISO 4892-3 should retain at least 50% of original elongation. Mechanical acceptance data are generated under ISO 527-3 for tensile properties and ISO 6383-2 for tear resistance; silage oxygen barrier claims are qualified by ASTM D3985 at 23°C and 0% RH, though published data for this specific Marlex® 7104/black-white structure is limited and must be confirmed by a film permeability trial. Extrusion uses a flat-die line with die width up to 6.0 m and melt temperature 210°C–235°C; the first chill roll is held at 60°C–75°C to prevent the black layer from differential shrinkage that induces curl greater than 5 mm/m. Products include silage clamp covers, bunker silo sheets, white-on-black mulch, fumigation barrier, and greenhouse light-deprivation covers.

Thermoformed Dunnage, Antistatic Masterbatch Dilution, and Sheet Flatness Control

Marlex® 7104 is used at 100 phr with 10–30 wt% clean internal edge-trim regrind in industrial dunnage sheet from 1.5 mm to 4.0 mm. Where electrostatic discharge is controlled, antistatic masterbatch is metered at 1.0–3.0 wt% to bring surface resistivity into 10^9–10^11 Ω/sq under ASTM D257; the antistat package should be pre-dispersed in an LLDPE carrier with melt index within 0.20 g/10 min of the base resin to prevent localized resistivity streaks at the die lip. Flat-die extrusion runs at 210°C–235°C, and the vertical three-roll stack is held at 65°C–80°C; roll-stack alignment wedge pressure varied more than 0.05 mm across the web produces sheet bow above 5 mm per linear meter after slitting. Downstream conversion on shuttle or rotary thermoformers requires sheet surface temperature of 120°C–135°C, plug assist speed below 250 mm/s, and mold temperature of 20°C–40°C; cycle times for 2.0 mm dunnage trays are typically 8–20 s. Terminal products include returnable dunnage trays, layer pads for automotive stamping, divider sheets for glass container handling, pallet top frames, and protective interleaving. The material is not food-contact compliant when reprocessed scrap exceeds 15 wt% unless the converter re-validates under FDA 21 CFR 177.1520(c).

Secondary containment liner extrusion uses Marlex® 7104 as a 100 phr base with 2.0–3.0 wt% carbon black masterbatch and 0.20–0.40 wt% antioxidant/acid neutralizer masterbatch; post-consumer regrind is excluded from the formula because contaminant carryover changes chemical resistance stability and weld fusion. The sheet is produced at 1.0–3.0 mm through a flat die with melt temperature 215°C–235°C and textured chill rolls at 65°C–85°C to create a rough surface for concrete adhesion or anchor profile. Chemical resistance screening follows ASTM D543 immersion practice; tensile yield retention after 30 days in representative acid, alkali, and hydrocarbon media is specified by the end user, and published data for Marlex® 7104 under all immersion environments is limited, so a plant-specific coupon program is required before final liner release. Installation geometry references EPA 40 CFR 264.193 where chemical storage bunds must contain 10% of total tank volume or 100% of the largest tank, whichever is greater. Field seaming uses hot wedge welding at 250°C–300°C; weld strength is checked by ASTM D6392 peel and shear, while vacuum box continuity is performed under ASTM D5820 for installations requiring leak testing. Terminal products include concrete bund liners for chemical storage, secondary containment sump liners, reactor containment area membranes, and acid/alkali tank linings. The product envelope excludes service with concentrated oxidizing acids above 40°C unless an oxidation-resistant protective cap layer is coextruded.