Dow ELITE MDPE 5940G is processed as a blown film resin with a density of 0.940 g/cm³ per ASTM D1505 and a melt index of 0.85 g/10 min per ASTM D1238 at 190°C/2.16 kg. The resin is run on monolayer and coextruded blown film lines with die gaps from 1.5 mm to 2.5 mm. Recommended melt temperatures fall between 193°C and 221°C; blow-up ratios of 2.0:1 to 3.2:1 are adjusted according to the anisotropy balance required by the converting operation. The downstream segments below are arranged by major application category, each with independent layer structures, additive loadings, process settings, and compliance markers. Numerical ranges are converter-level values from industrial blown film lines; they are configuration-sensitive and do not replace resin manufacturer specification limits.

Why 20–30 wt% MDPE 5940G Replaces LDPE in Heavy-Duty Sack Monolayers

Heavy-duty sacks for mineral fillers, cement, resins, and dry chemical powders are extruded as 150–200 µm monolayers in which LDPE-rich formulations require high dosing of impact modifiers to maintain drop-fill resistance. In converter trials on a 75 mm screw diameter blown film line with L/D 30:1 and a 350 mm die equipped with dual-lip air ring, replacing 25 wt% LDPE with MDPE 5940G increases dart impact measured under ASTM D1709/A by 35–50% at constant total thickness, while keeping melt pressure at the die head between 32 MPa and 40 MPa. The melt profile is set at 190°C in the feed zone, 204°C in the metering zone, and 216°C at the die. Die gap is set to 2.0 mm, blow-up ratio to 2.5:1, and frost line height to 700–900 mm. Output is capped at 180–220 kg/h to avoid bubble instability at high draw. Seal performance for valve sacks is checked on a rotary heat-sealer at 130–140°C and 0.35 MPa dwell pressure for 0.8 s. When sacks are certified for dangerous goods, the finished bag construction must pass UN 13H3 design-type tests under ADR 6.1.5.2.4; the MDPE monolayer alone does not provide sufficient puncture resistance for sharp-edged fillers unless the minimum 150 µm thickness is maintained. Melt temperatures above 240°C trigger molecular weight degradation and a measurable reduction of dart impact, while die-lip oxidation becomes visible at outputs above 220 kg/h.

Silage wrapping film and greenhouse side sheeting produced on a three-layer Reifenhäuser blown film line with 60 mm/75 mm/60 mm screw diameters and L/D 30:1 use MDPE 5940G in the core layer at 30–40 wt% of total film weight. The resin function is slow-puncture resistance under wind-induced flapping and bale stacking. A typical layer structure is white/black/white with 8–12 wt% TiO₂ masterbatch in the outer layers and 3–4 wt% carbon black masterbatch in the core; MDPE 5940G is dry-blended with mLLDPE and a PE-g-MAH carrier for carbon black dispersion. Melt temperature is held at 205–215°C, die gap at 2.2 mm, blow-up ratio at 2.4:1 to 2.8:1, and film thickness at 150–250 µm. Weathering resistance is governed by EN 13206:2017 for greenhouse covering films and EN 13207:2017 for bale-wrap silage films; UV stabilization packages based on HALS and benzotriazole are added at 0.3–0.6 wt%, and field exposure beyond 12 months requires quarantine weathering tests. Carbon black masterbatch must be pre-dried at 70°C for 4 h when ambient RH exceeds 60% to prevent bubble pinholes. Drawdown ratio exceeding 12:1 induces transverse direction tear reduction measured under ASTM D1922; therefore, die gap reduction below 1.8 mm is not recommended for this construction.

Frozen Food Packaging Layer Structures and Seal Performance at −20°C

At −20°C, three-layer coextruded films for frozen vegetables, meat, and prepared meals are run with MDPE 5940G in the internal core or sealant layer because the resin retains ductility below freezing. A common structure is 25 wt% MDPE 5940G, 50 wt% mLLDPE, and 25 wt% LDPE, extruded at total thickness 50–70 µm on a three-layer blown film line with internal bubble cooling and die diameter 400 mm. Melt temperature is set to 210–220°C, die gap to 1.8 mm, blow-up ratio to 2.2:1, and frost line height to 450–600 mm. Sealing is tested under ASTM F88/F88M-21 on a laboratory heat sealer at 130°C, 0.3 MPa for 0.5 s; seal strength is 3.0–4.2 N/15 mm for 50 µm film. Hot tack per ASTM F1921 at 110–125°C must exceed 1.5 N/15 mm to prevent seal creep during vertical form-fill-seal filling of frozen products. Low-temperature dart impact under ASTM D1709/B after conditioning at −18°C for 24 h retains 85–92% of the 23°C value. The migration status for frozen food contact is defined by FDA 21 CFR 177.1520(c) 3.2a and EU Regulation (EU) No 10/2011 with an overall migration limit of 10 mg/dm² under OM2 testing for aqueous and low-acid simulants. The use of regrind above 20 wt% reduces dart impact by 15–25% and is not recommended in sealant layers.

When MDPE 5940G Enters a Three-Layer Lamination Sealant Web

In lamination sealant webs for stand-up pouches containing dry mixes, frozen seafood, and pet food, MDPE 5940G is used in the blown film sealant skin that is later bonded to BOPET or BOPP reverse-printed film. The sealant web is produced as a three-layer coextrusion with 25–30 wt% MDPE 5940G in the sealant skin, 50 wt% mLLDPE in the core, and 20–25 wt% LDPE in the outer skin. The blown film line is operated with die gap 1.6 mm, blow-up ratio 2.0:1, melt temperature 205–215°C, and dual-lip air ring cooling at 15–20°C. The MDPE-containing sealant skin shifts seal initiation temperature upward by 5–8°C relative to a pure LDPE sealant, but provides higher hot tack and puncture resistance after lamination. Adhesion to solvent-based polyurethane laminating adhesives requires corona treatment to 42–46 mN/m surface energy before lamination; corona above 50 mN/m causes surface oxidation without additional bond strength. Seal integrity is assessed under ASTM F88/F88M-21 and burst resistance under ASTM F1140/F1140M-21. Food contact compliance is maintained under FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011 for dry and aqueous food categories; high-fat foods above 20% fat content require fatty food simulant D2 testing under the same regulation. The use of mLLDPE in the core provides interlayer compatibility, but MDPE 5940G should not be blended into the outer lamination skin above 35 wt% because bond strength to polyurethane adhesive decreases by 10–15%.

For post-consumer recycled LLDPE streams used in non-food industrial liners, MDPE 5940G at 30–50 wt% functions as a property restorer to raise tensile impact and tear resistance that are lost through recycled content variability. The formulation is dry-blended with washed LLDPE recyclate and 2–3 wt% process stabilizer masterbatch, then extruded on a 90 mm screw diameter blown film line with L/D 33:1 and a 500 mm die. Melt temperature is set to 200–215°C, die gap to 2.4 mm, blow-up ratio to 2.8:1, and film thickness to 100–150 µm. Because PCR carries unpredictable moisture and volatile residues, vented screw zone vacuum of −0.08 MPa must be maintained to prevent gel defects. Tensile strength retention is measured under ASTM D882-18; the addition of 30 wt% MDPE 5940G raises machine-direction tensile strength at break from 18–22 MPa for 100% PCR film to 24–28 MPa for the blend. Elmendorf tear under ASTM D1922 improves by 20–30%. Environmental compliance is governed by REACH Annex XVII restrictions on recycled plastics; the base resin contact compliance is documented under FDA 21 CFR 177.1520 for possible secondary use, but non-food industrial liners do not fall under EU Regulation (EU) No 10/2011.

Low-Temperature Dart Impact Retention in Bag-in-Box Liners after 1,000 Flex Cycles

Bag-in-box liners for liquid concentrates, sauces, and dairy products are coextruded as two-ply films with MDPE 5940G in the inner contact layer at 40 wt% total thickness. The film is produced on a three-layer line with an 80 mm primary extruder and 60 mm satellite extruders, die gap 2.0 mm, blow-up ratio 2.5:1, melt temperature 210–220°C. Total liner thickness ranges from 65 µm to 90 µm, with an MDPE-rich inner layer providing flex crack resistance. Flex crack resistance is tested under ASTM F392/F392M-11(2020) using a Gelbo flex tester for 1,000 cycles at 23°C and −5°C; a 70 µm liner containing 40 wt% MDPE 5940G shows no visible pinholes after 1,000 cycles, while a standard LDPE/LLDPE control may develop 5–15 pinholes depending on layer distribution. Oxygen permeation after flexing is measured under ASTM D3985-17 at 23°C and 0% RH; values for the 70 µm liner are typically 1,000–1,500 cm³/(m²·day·atm). For oxygen-sensitive liquids, a 5 µm EVOH barrier layer is incorporated between two PE plies. The liner must comply with FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011 for liquid food simulant B (3% acetic acid) and simulant D2 for fatty emulsions. Contact with solvent-based cleaning agents or high-alcohol concentrates above 20% ethanol by volume is outside the recommended service window because MDPE 5940G is not a barrier resin; oxygen and limonene permeability increase at temperatures above 35°C.