On a mono-layer municipal refuse sack line equipped with a 65 mm 30:1 L/D grooved-feed extruder and a 250 mm spiral mandrel die, MarFlex® 7109S LLDPE blown film resin is processed with a nominal density of 0.918 g/cm³ per ASTM D1505 and a melt index of 1.0 g/10 min per ASTM D1238. The resin is not hygroscopic, so pellet pre-drying is not mandatory below 60% RH; however, surface condensation on railcar pellets stored in humid bulk silos must be removed before extrusion because moisture carryover destabilizes the bubble and increases web gauge variation beyond ±8%. The blend for black kerbside sacks consists of 85 wt% MarFlex 7109S, 10 wt% LDPE having a density of 0.922 g/cm³ and a melt index of 2.0 g/10 min to reduce melt tension loss at high draw, and 5 wt% of a 40 wt% carbon black LLDPE masterbatch for opacity and ultraviolet screening. The downstream extrusion process is run at a die gap of 2.0 mm, blow-up ratio of 2.4:1 to 2.6:1, melt temperature of 205 °C to 225 °C, and frost line height of 450 mm to 550 mm from the die face. Output rates of 120–150 kg/h are stable on this configuration; raising output above 160 kg/h without internal bubble cooling decreases dart impact resistance and creates uneven frost line movement. The terminal product is a black refuse sack in the 30–80 L capacity range with wall thickness between 60 µm and 120 µm. Compliance for the sack is evaluated under EN 13592:2017, and the packaging heavy-metal sum remains below 100 mg/kg under EU Directive 94/62/EC, Article 11 and Annex II. Converter lot records show dart drop values on 80 µm film of 150–250 g using ASTM D1709-16a Method A, and Elmendorf tear of 450–700 mN in the machine direction using ASTM D1922; the lower limit corresponds to BUR above 2.7:1, where bubble instability degrades molecular orientation uniformity.

What Limits Seal Initiation Temperature in Frozen Food Pillow Pouch Conversion?

For frozen vegetable and fruit pillow pouches, the dominant conversion risk is not film optics but heat-seal initiation and seal-through at high throughput. In this application the addition ratio is 90 wt% MarFlex 7109S, 7 wt% LDPE of density 0.923 g/cm³ and MI 2.0 g/10 min, and 3 wt% of a slip/antiblock masterbatch with erucamide active content between 0.8 wt% and 1.2 wt% to control coefficient of friction without exceeding migration limits. The food-contact compliance boundary is defined by FDA 21 CFR 177.1520(c)(2.2) for olefin polymers with density below 0.94 g/cm³, and by EU Regulation (EU) No 10/2011 with an overall migration limit of 10 mg/dm² under Annex I and Article 12. Downstream production uses a mono-layer blown film line with a 300 mm die, 1.8 mm die gap, 2.0:1 BUR, melt temperature 200 °C to 215 °C, and downstream corona treatment to a wetting tension of 38–42 mN/m. Heat-seal initiation is verified by ASTM F88/F88M-21 using a 0.5 s dwell and 0.3 N/mm² seal pressure. A minimum seal strength of 12 N/25 mm at 125 °C is required to avoid leakers in vertical form-fill-seal runs above 60 pouches/min. Raising seal-bar temperature above 150 °C causes localized thinning at the seal transition and reduces burst performance, while running the melt below 195 °C raises die lip pressure and produces visible sharkskin. The terminal product is a 40–70 µm pillow pouch for frozen vegetables. A compliance matrix is given below.

Post-consumer recyclate dilution curves in coextruded mailer structures create a different pressure profile than mono-layer refuse sack lines. The total structure blend is 30 wt% MarFlex 7109S, 50 wt% post-consumer LLDPE lightweight scrap with a melt index between 0.8 g/10 min and 1.2 g/10 min, 15 wt% LDPE of MI 2.0 g/10 min, and 5 wt% carbon black masterbatch. The skins of a three-layer A/B/A die are enriched with virgin MarFlex 7109S, while the core carries the PCR fraction to maintain tear resistance and surface uniformity. Compliance is assessed under the US TPCH Model Legislation for packaging heavy metals, with a combined lead, cadmium, mercury, and hexavalent chromium limit of 100 mg/kg; EU Directive 94/62/EC, Article 11 and Annex II imposes the same sum limit; and REACH Regulation (EC) No 1907/2006, Annex XVII Entry 23 restricts cadmium in plastic to 0.01 wt%. Downstream production is accomplished on a three-layer coextrusion blown film line with a 450 mm die, 2.2 mm die gap, 2.4:1 BUR, melt temperature 215 °C to 235 °C, and an extruder screen pack at 40/60/100 mesh. Screen pack head pressure trends upward from 80 bar to 120 bar as recycled gels accumulate; a continuous melt filter or screen changer is required to avoid pressure spikes above 130 bar, which correlate with localized thin bands and tear initiation in the finished mailer. The terminal product is an opaque black e-commerce mailer film of 50–90 µm, with a dart impact requirement typically set at ≥200 g for 70 µm film under ASTM D1709-16a Method A.

Melt Curtain Stability Without Internal Bubble Cooling in 15 µm Garment Film

Garment bag film at 12–20 µm represents a thin-gauge processing boundary where MarFlex 7109S must be extruded with the die gap at 1.5 mm, a blow-up ratio of 3.0:1, and a melt temperature of 215 °C. The formulation addition ratio is 97 wt% MarFlex 7109S and 3 wt% slip/antiblock masterbatch with erucamide active content of 0.8–1.2 wt%. Dynamic coefficient of friction is measured at 0.25–0.35 per ASTM D1894, and blocking force is evaluated with a two-plate compression method to avoid web blocking during roll storage, because thin garment film stored above 35 °C can block if slip additive bloom is incomplete. The production process uses a mono-layer blown film line with a 250 mm die, output of 80–100 kg/h, frost line height 350–400 mm, and no internal bubble cooling. Without internal bubble cooling, melt curtain stability below 15 µm is sensitive to ambient air currents; plant air handlers should maintain laminar flow around the bubble. The terminal product is a garment bag, dry cleaning bag, or thin retail sleeve in the 12–20 µm range. Compliance is limited to general packaging requirements under EU Directive 94/62/EC, Article 11 and Annex II for heavy metals, and REACH Regulation (EC) No 1907/2006, Annex XVII Entry 23 for cadmium at 0.01 wt%. Operational boundary: at melt temperatures above 230 °C, slip additive degradation creates die lip plate-out; at temperatures below 195 °C, sharkskin appears at 12 µm. Ambient RH above 60% can induce surface condensation and bubble instability, but pellet pre-drying is not required.

When a 150 µm Sub-Slab Vapor Retarder Must Meet ASTM E1745 Class A

Sub-slab vapor retarder film made from MarFlex 7109S requires a thick-gauge blown film configuration with lower bubble stretching than thin garment film. The formulation addition ratio is 96 wt% MarFlex 7109S and 4 wt% carbon black masterbatch to provide thermal stability during concrete placement and to screen ultraviolet exposure on the job site. Compliance under ASTM E1745-17 Class A requires water vapor permeance not greater than 0.1 perm when tested per ASTM E96/E96M-16, and the 150 µm nominal thickness must be held within ±5% across the web to avoid thin sections that fail the permeance specification. The downstream process uses a heavy-gauge mono-layer blown film line with a 2.5 mm die gap, 2.0:1 BUR, melt temperature 220 °C to 240 °C, output of 140–180 kg/h, and internal bubble cooling. At thickness below 125 µm, pinhole risk increases due to carbon black dispersion defects; at BUR above 2.2:1, water vapor permeance can exceed Class A due to molecular orientation effects. The terminal product is a 150 µm sub-slab vapor retarder sheet laid beneath concrete slabs. The level of carbon black masterbatch must be controlled precisely because over-dispersion raises melt pressure and pre-filtration loading, while under-dispersion creates visible resin-rich streaks that reduce tear resistance under site traffic.

Anti-static drum and box liners for powder packaging introduce a surface-resistivity constraint that is absent in refuse sacks and garment film. The formulation addition ratio is 88 wt% MarFlex 7109S, 8 wt% LDPE with a melt index of 0.3 g/10 min to raise puncture resistance, and 4 wt% conductive carbon black masterbatch. The conductive carbon black must produce a surface resistivity between 10⁶ Ω/sq and 10⁹ Ω/sq per IEC 60079-32-2 for packaging used in explosive atmosphere zones, while the film retains a thickness of 200–300 µm. Downstream production is run on a heavy-gauge mono-layer blown film line with a 75 mm 30:1 L/D barrier screw and Maddock mixing section to disperse conductive carbon black, a 2.5 mm die gap, 1.8:1 BUR, melt temperature 225 °C to 240 °C, and internal bubble cooling. Screen pack pressure must be monitored because conductive masterbatch can plate out on the die lip and create localized resistivity variation above 10⁹ Ω/sq. Standard carbon black masterbatch does not lower surface resistivity into the target range; only conductive grades are acceptable. The terminal product is a 200–300 µm anti-static liner for drums, boxes, or bulk powder handling containers, with puncture resistance tested by ASTM D5748 or dart impact by ASTM D1709-16a Method A as specified by the end user.