Marlex D173 is a film-grade linear low density polyethylene with a nominal density of 0.917 g/cm³ per ASTM D1505 and a melt index of 1.0 g/10 min at 190°C/2.16 kg per ASTM D1238. In single-screw extrusion, barrier screws with 24:1 to 30:1 L/D are preferred because the resin’s molecular weight distribution can raise melt pressure at screw speeds below 25 rpm. Pre-drying is generally not required when silo and hopper moisture remain below 50% RH, but hopper dryers set at 60°C to 70°C should be used if condensation risk exists above 70% RH. Cast film conversion typically imposes melt temperatures of 220°C to 250°C, whereas blown film lines operate more effectively at 185°C to 215°C to maintain bubble geometry. Gravimetric dosing is necessary when masterbatch density differs from the resin by more than 0.15 g/cm³ to prevent pellet segregation in the feed throat.

When D173 Replaces a Conventional Butene LLDPE in Cast Stretch Film

On a three-layer cast stretch film line, D173 is typically assigned to the core layer at 60 wt% to 75 wt% of total mass flow, with the cling skin composed of a metallocene LLDPE and 2 wt% to 5 wt% polyisobutylene masterbatch, while the release skin carries 0.5 wt% to 1.2 wt% erucamide slip and 1000 ppm to 3000 ppm silica antiblock. The die gap is set at 0.5 mm to 0.8 mm because D173 exhibits less neck-in than butene-based LLDPE at equivalent melt temperature. Melt temperature at the feedblock is held at 235°C to 245°C. The chill roll temperature is maintained at 18°C to 22°C with an air knife positioned to quench the web within 5 mm to 10 mm of the die exit. Line speed is typically 250 m/min to 600 m/min, producing final film thicknesses from 10 µm to 20 µm. Operational boundary: increasing melt temperature above 260°C to improve clarity may volatilize low-molecular-weight fractions and increase die-lip build-up rates; chill roll temperatures above 25°C reduce pre-stretch retention. Industrial pallet wrap is not placed in direct food contact, but it falls under the European Packaging and Packaging Waste Directive 94/62/EC with a maximum total concentration of lead, cadmium, mercury, and hexavalent chromium below 100 ppm. Terminal products include 12 µm to 23 µm machine-grade pallet wrap and 8 µm to 10 µm hand-applied wrap after down-gauging. Dart impact after pre-stretching should be validated in-line using ASTM D1709-A, because published data for this specific configuration is limited.

Blown coextrusion for frozen vegetable, seafood, and bakery bags positions D173 in the sealant layer at 30 wt% to 45 wt% of total film mass, with the outer layer composed of HDPE or MDPE for abuse resistance and the core carrying a D173-rich blend to preserve interlayer adhesion. The sealant layer is dry-blended with 70 wt% D173, 20 wt% metallocene LLDPE, and 10 wt% LDPE to shift the seal initiation temperature below 110°C on jaw sealers with 0.3 s to 0.5 s dwell time. Die gap is set at 1.8 mm to 2.2 mm. Blow-up ratio is maintained at 2.2:1 to 2.8:1, and frost line height is held at 5 to 8 die diameters to stabilize the bubble without excessive machine-direction orientation. Melt temperature is 190°C to 205°C. Layer distribution is verified by transmission IR rather than weight-based calculation, because the melt density difference between HDPE and D173 can distort layer ratio estimates. Compliance for direct food contact is governed by 21 CFR 177.1520(c)(3.2a) for olefin polymers, and by Regulation EU 10/2011 with an overall migration limit of 10 mg/dm² under simulant D2 for frozen aqueous foods. Terminal films range from 40 µm to 80 µm, and bags are filled at −20°C to −30°C. The seal strength after freezer storage should be checked by ASTM F88/F88M at an initial peel speed of 300 mm/min, because cold-temperature crystallization can reduce interfacial seal strength if the film is quenched too rapidly; published data for this specific configuration is limited.

Silage Film UV Stabilizer Loading and Oxygen Barrier Stability

For silage bale wrap and clamp sheet, D173 is compounded with a HALS/benzotriazole ultraviolet package at 0.4 wt% to 0.8 wt% total stabilizer, together with 2 wt% to 4 wt% rutile titanium dioxide masterbatch in the white skin of a white/black/white coextrusion. The black core uses 2 wt% to 3 wt% carbon black masterbatch to block ultraviolet penetration and suppress fungal growth on wet forage. In this configuration, D173 is used at 100 phr base resin in each layer, with the black core thickness at 20% to 30% of total thickness and the white skins equally divided. The blown film die gap is set at 1.4 mm to 2.0 mm, blow-up ratio at 2.4:1 to 3.2:1, and melt temperature at 190°C to 210°C. Frost line height is raised to 9 to 12 die diameters to reduce orientation and improve tear resistance, which matters when wrap is stretched around angled bale corners. Compliance is evaluated against EN 13207:2018 for silage films. Tensile yield and elongation are measured under ISO 527-3 at 500 mm/min, tear resistance under ISO 6383-2, and dart impact under ISO 7765-2. Terminal products include 50 µm to 75 µm white/black/white bale wrap and 150 µm pit cover sheets. Dispersion quality is checked by optical microscopy on cast film prints at 100× because local UV masterbatch depletion can produce photodegradation punctures after 12 months of outdoor exposure.

For heavy-duty industrial sacks loaded with polymer granules or mineral fillers, a monolayer blown film made from 70 wt% to 90 wt% D173 and 10 wt% to 30 wt% recycled LLDPE is run on a high-stalk bubble with a die gap of 2.0 mm to 2.5 mm. Blow-up ratio is kept at 2.0:1 to 2.5:1, and frost line height is raised to 10 to 12 die diameters to produce a balanced machine-direction and transverse-direction tear profile after bag sealing. Melt temperature is held at 185°C to 205°C; if the recycled fraction contains more than 5 wt% of mixed-film contamination, a screen changer with 80 mesh filtration is installed before the die to prevent gel streaks. The formulation includes 0.5 wt% to 1.0 wt% hindered phenol/phosphite antioxidant masterbatch and 2000 ppm to 5000 ppm silica antiblock, with slip additive limited to 500 ppm to 1000 ppm to avoid heat-seal strength loss on hot-bar sealers. Drop impact is evaluated under ASTM D1709-A, and tear resistance under ASTM D1922. Terminal products include 50 µm to 120 µm polymer granule sacks, mineral filler sacks, and industrial dust bags. When the sack is used to package food-grade raw materials, the inner layer must comply with 21 CFR 177.1520(c) and EU 10/2011; otherwise the application remains non-food industrial packaging under 94/62/EC.

How Does D173 Perform as a Sealant Web Against PET and Aluminum Foil in Solventless Lamination?

D173 is used as a heat-seal web for dry-food and snack laminations when the structure is 12 µm PET adhesive-laminated to 7 µm aluminum foil followed by a 20 µm to 30 µm D173 sealant film. The sealant web is produced on a three-layer cast line with a die gap of 0.6 mm to 0.9 mm, chill roll temperature 18°C to 23°C, and melt temperature 230°C to 245°C. The layer formulation comprises 80 wt% to 90 wt% D173 and 10 wt% to 20 wt% metallocene plastomer to reduce seal initiation temperature for high-speed vertical form-fill-seal machines running at 80 to 140 bags/min. Slip and antiblock loadings are tuned to 800 ppm to 1200 ppm erucamide and 3000 ppm to 6000 ppm synthetic silica to maintain kinetic coefficient of friction below 0.25 on horizontal form-fill-seal guides. Hot-tack force is measured by ASTM F1921 at 120°C to 135°C seal bar temperature with 0.2 s dwell and 0.5 N/mm² sealing pressure. Lamination bond strength after solventless adhesive cure is tested under ASTM F904, and food-contact compliance is verified against 21 CFR 177.1520 and EU 10/2011 with an overall migration limit of 10 mg/dm². Terminal products include stand-up pouches for nuts, dried fruits, and confectionery, where the sealant layer must survive 30 mm drops at −5°C without longitudinal seal rupture. If the sealant web is run below 220°C melt temperature, melt curtain sag can disrupt gauge uniformity; above 250°C, die-lip build-up tends to increase after 4 h of continuous operation.

In municipal refuse and commercial can liner conversion, D173 is dry-blended with post-industrial recyclate at 60 wt% to 80 wt% and extruded on grooved-feed single-screw machines with 30:1 L/D at 180°C to 200°C. Die gap is set at 1.2 mm to 1.6 mm, blow-up ratio is 2.5:1 to 3.5:1, and frost line height is maintained at 4 to 6 die diameters to preserve the higher machine-direction modulus required for bottom-seal packaging lines. The formulation includes 0.5 wt% to 2.0 wt% zeolite or silica antiblock and 500 ppm to 1200 ppm slip masterbatch. Film gauge is monitored in-line via capacitive sensors because variations greater than ±5% cause roll deformation in high-speed converter unwind stands. Melt pressure at the screen changer is limited to 350 bar to prevent excessive shear heating, and if pressure exceeds this boundary, the recycled fraction is reduced by 5 wt% increments. Tensile properties are checked by ISO 527-3 at 100 mm/min, and puncture resistance by ASTM D5748 or equivalent. Terminal products include 30 L to 120 L refuse sacks and 20 L to 40 L can liners for commercial kitchens.