ExxonMobil HDPE HTA-001 is processed on high-speed blown film lines for thin-gauge T-shirt sacks as a high molecular weight, high-density polyethylene with a nominal density of 0.950 g/cm³ under ASTM D1505-18 and a melt index of 0.05 g/10 min at 190 °C/2.16 kg under ASTM D1238-20. The material is plastified in a single-screw extruder with a grooved feed section and L/D ratio of 25:1 to 30:1, operating with barrel temperatures from 180 °C to 210 °C and melt temperature at the die of 190–220 °C. The die gap is set between 0.8 mm and 1.2 mm, blow-up ratio is held at 3.0:1–4.0:1, and frost line height is maintained at 8–12 times the die diameter to stabilise the high-stalk bubble. Online capacitive thickness sensors control gauge variation within ±5% of target, and wicketing or roll conversion follows the film winder without intermediate slitting contamination.

Formulation for thin-gauge grocery sacks uses HTA-001 at 100 parts by weight as the base polymer, with a polyethylene-based slip masterbatch at 0.05–0.2 phr, a silica or synthetic antiblock masterbatch at 0.1–0.3 phr, and a fluoroelastomer processing aid at 0.02–0.05 phr. If limited downstream bag softness or tear resistance is required, octene-LLDPE is added at 5–15 phr, but addition above 15 phr measurably reduces film modulus and can destabilise the high-stalk bubble at high blow-up ratios. Processing aid levels below 0.02 phr are associated with sharkskin on the die lip at high throughput; levels above 0.05 phr can cause plate-out and transfer to downstream nip rolls.

Compliance for retail and food-adjacent sacks is established under FDA 21 CFR 177.1520, EU 10/2011, and ISO 11833-1. Mechanical properties are tested by ASTM D882 for tensile, ASTM D1922 for Elmendorf tear, and ASTM D1709 for dart impact. Terminal products include 8–15 µm T-shirt grocery sacks, merchandise bags, and retail checkout bags produced on high-speed bag-making lines operating above 250 cycles/min.

What Limits Dart Impact in Heavy-Duty HDPE Liner Film at 80 µm?

Dart impact in heavy-duty high-density liner film is controlled by the blend ratio of the high molecular weight HDPE phase to the linear low-density polyethylene phase. HTA-001 contributes stiffness, bubble stability, and creep resistance; octene-LLDPE contributes low-temperature impact and tear propagation resistance. At a film thickness of 80 µm, the polymer phase comprises HTA-001 at 80–95 phr and octene-LLDPE at 5–20 phr. Additives are dosed as carbon black masterbatch at 1–3 phr, hindered phenolic/phosphite antioxidant at 0.1–0.3 phr, slip/antiblock masterbatch at 0.1–0.3 phr, and polymer processing aid at 0.02–0.05 phr. When LLDPE content exceeds 20 phr, modulus declines below the range required for rigid liner performance, and the bubble neck becomes less stable under high-stalk geometry.

Processing is performed on a blown film line with an extruder L/D of 30:1, a die gap of 1.2–1.8 mm, blow-up ratio of 2.5:1–3.5:1, and melt temperature of 200–225 °C. Frost line height is set at 6–10 times the die diameter, lower than for thin-gauge sacks, because thicker film creates a greater enthalpy sink and requires a shorter melt-stretching zone. Dart impact testing follows ASTM D1709, Method A for 50–100 µm film; Elmendorf tear follows ASTM D1922; tensile testing follows ISO 527-3 and ASTM D882. Published production data for HMW-HDPE/LLDPE blends indicate that dart impact increases nonlinearly with LLDPE content up to 20 phr, after which gauge variation and bubble flutter can offset the toughness gain. The practical lower service temperature limit for unblended HTA-001 liner is approximately -20 °C; LLDPE modification extends ductile failure to lower temperatures but reduces stiffness and increases blocking tendency.

The dominant production-scale failure mode is bubble flutter at high LLDPE addition and low melt temperature. Operators correct this by raising melt temperature no higher than 230 °C, reducing blow-up ratio, or lowering maximum line speed. Carbon black dispersion is verified by ASTM D5596; poor dispersion produces microgel aggregates that reduce dart impact and create visible specks in the film. Terminal products include 50–120 µm construction debris liners, industrial can liners, chemical packaging liners, and heavy-gauge agricultural bulk bags. The material is not recommended for applications requiring elastomeric stretch recovery because the high-density phase exhibits limited elastic recovery after yield.

High-Stalk Bubble Geometry and Gauge Uniformity for Thin-Gauge HMW-HDPE

Blown film lines running HTA-001 at thicknesses below 12 µm use high-stalk bubble geometry because the high molecular weight tail increases melt relaxation time and resists draw resonance. Die gap is set between 0.6 mm and 1.0 mm, blow-up ratio between 3.5:1 and 5.0:1, and melt temperature between 190 °C and 210 °C. Frost line height is raised to 10–14 times the die diameter to create a distinct neck and to generate machine-direction orientation. Internal bubble cooling is operated with chilled air at 5–15 °C, and external air-ring flow is adjusted to prevent bubble oscillation at the frost line. Gauge uniformity is monitored with a traversing capacitance or beta gauge; variation outside ±5% typically results in downstream bag-converting misfeeds and inconsistent seal strength.

The formulation for ultra-thin film uses HTA-001 at 95–100 phr, with optional octene-LLDPE at 0–5 phr for improved puncture resistance. Slip masterbatch is dosed at 0.05–0.15 phr, antiblock masterbatch at 0.1–0.4 phr, and processing aid at 0.02–0.05 phr. Additive loadings are kept low because excessive antiblock above 0.4 phr reduces dart impact and can generate die lip abrasion. The combination of low melt temperature and high frost line height reduces gel formation and allows down-gauging to 8 µm without losing bubble stability on production lines with automatic air-ring control.

Compliance is tested under ISO 11833-1 for film properties, ASTM D882 for tensile properties, ASTM D1922 for tear, and ASTM D1709 for dart impact. For food-adjacent applications, FDA 21 CFR 177.1520 and EU 10/2011 apply. Terminal products include 8–12 µm point-of-sale bags, produce bags, and high-speed overwrap films. Operational boundary: down-gauging below 8 µm requires reduced extruder output and increased blow-up ratio, but film stiffness and handle remain adequate only if the high molecular weight fraction is preserved by limiting melt temperature below 210 °C.

Food-contact cereal liners and bakery bag films based on HTA-001 require low-gel extrusion conditions and controlled slip migration. The polymer phase is used at 100 parts by weight with erucamide slip masterbatch at 0.05–0.1 phr, synthetic silica antiblock at 0.1–0.3 phr, antioxidant at 0.05–0.2 phr, and polymer processing aid at 0.02–0.05 phr. Melt temperature is maintained at 190–210 °C to limit gel formation and off-taste precursors; die gap is set at 0.8–1.2 mm, blow-up ratio at 3.0:1, and film thickness at 15–30 µm. The extruder is purged with LDPE after shutdown because the high molecular weight fraction can retain thermally oxidised material in the die land if residence time exceeds 8 min.

Compliance is based on FDA 21 CFR 177.1520, EU 10/2011, REACH, and organoleptic testing under EN 1622. Overall migration is tested by EN 1186-1, and specific migration limits are evaluated using food simulants corresponding to the intended contact class. Surface treatment by corona discharge to 38–42 mN/m is required if the film is printed; surface energy decays within hours if the film is stored above 30 °C before printing. Terminal products include cereal box liners, bakery bags, napkin overwrap, and secondary food-contact liners. The operational boundary is additive loading: erucamide above 0.1 phr can produce bloom that interferes with ink adhesion and heat-seal strength.

When HTA-001 is modified with octene-LLDPE for cold-temperature industrial sacks

When HTA-001 is modified with octene-LLDPE for cold-temperature industrial sacks, the formulation objective is to retain high-density stiffness while shifting the ductile-to-brittle transition downward. The polymer phase comprises HTA-001 at 80–90 phr and octene-LLDPE at 10–20 phr. Antioxidant masterbatch is added at 0.1–0.3 phr, slip/antiblock masterbatch at 0.1–0.3 phr, carbon black or white masterbatch at 2–4 phr, and polymer processing aid at 0.02–0.05 phr. The resulting film is extruded at 75–150 µm thickness with die gap 1.5–2.0 mm, blow-up ratio 2.5:1–3.5:1, and melt temperature 200–225 °C. The frost line height is set at 5–8 times the die diameter, which is lower than thin-gauge high-stalk operation because the thicker film requires higher cooling time before nip flattening.

Mechanical qualification is performed by ASTM D1709 for dart impact, ASTM D1922 for Elmendorf tear, ISO 527-3 for tensile, and ASTM D2732 for free shrink where applicable. At low temperature, impact testing is conducted after conditioning at -20 °C for 24 h; the ductile failure mode is preferred over brittle splitting in bulk packaging operations. Published data for this specific HTA-001/LLDPE configuration is limited, so industrial qualification requires full-scale Sack testing rather than extrapolation from small-film specimens.

Compliance for industrial sacks follows ISO 21898 for flexible intermediate bulk containers, EN 13592 for household plastic sacks, and transport-related requirements under ADR where the package is used for chemical powders. Terminal products include 75–150 µm cold-storage bulk sacks, construction aggregate sacks, and heavy chemical packaging liners. The primary incompatibility is with high levels of low-density waxes, which can migrate to the film surface and reduce the coefficient of friction stability required for automatic bag filling.

Printed lamination base film without low-molecular-weight wax addition

Printed lamination base film produced from HTA-001 is formulated without low-molecular-weight waxes because wax bloom can reduce lamination bond strength and ink adhesion after film ageing. The compound uses HTA-001 at 100 parts by weight, white masterbatch at 3–6 phr, slip/antiblock masterbatch at 0.2–0.5 phr, antioxidant at 0.05–0.2 phr, and polymer processing aid at 0.02–0.05 phr. The film is blown at 20–40 µm thickness with die gap 0.8–1.2 mm, blow-up ratio 2.5:1–3.5:1, and melt temperature 190–215 °C. After winding, the film is corona treated in-line to a wetting tension of 38–42 mN/m measured by ISO 8296, and lamination is performed on solventless or solvent-based adhesive lines within 24 h of treatment to avoid decay.

Compliance for laminate structures is based on EU 10/2011 for plastic food-contact materials, FDA 21 CFR 177.1520 for the polyethylene layer, and REACH for adhesives and printing inks. Bond strength is tested by ASTM F904 or DIN 53357. Published data for this specific film and adhesive system is limited; adhesion must be validated after 7-day curing at 23 °C/50% RH and after pasteurisation or hot-fill simulation if the final pouch is thermally treated. Terminal products include printed lamination film for stand-up pouches, sachets, and barrier laminate inner layers. The exclusion is explicit: no wax-based slip additive should be introduced above 0.05 phr, because even minor bloom can produce bond-strength loss at the laminate interface.