Borealis HDPE HE2557 is processed as a high-density polyethylene blown-film resin. Density is measured under ISO 1183-1:2019; melt mass-flow rate is measured under ISO 1133-1:2022 at 190 °C/2.16 kg. The downstream application scope is restricted to actual converting segments of retail carrier film, dry food liners, waste containment liners, multi-wall sack inner liners, and building vapor retarders. Each segment records the applicable compliance instruction, the formulation loading of HE2557, the downstream manufacturing process, and the terminal product type. The content is formulated for B2B raw material specification, not for consumer-facing product claims.

What Processing Window Supports Thin-Gauge Carrier Bag Film Without Melt Fracture?

At the die exit, the HE2557 melt is drawn upward through a long neck before lateral expansion on high-stalk HDPE blown-film lines used for thin retail carrier film. Typical melt temperatures are 200–230 °C; die gaps are set at 0.8–1.2 mm; blow-up ratios are held between 4:1 and 5:1. The stalk is maintained at 5–7 die diameters and the frost line at 8–10 die diameters. On grooved-feed extruders with L/D 25:1–30:1 and barrier screws, die-temperature deviation above ±5 °C produces visible gauge bands because the freeze-line geometry shifts. Melt filtration through 80–100 µm packs is standard to limit die-lip deposits from edge-trim regrind. Film gauge is typically 7–15 µm.

HE2557 is loaded at 85–100 wt%; clean edge-trim regrind may replace 0–15 wt% without moving the operation into the unstable high-stalk region. Post-consumer recyclate above 10 wt% generally raises gel counts and narrows bubble stability. A carrier-grade masterbatch containing slip and antiblock is dosed at 2–5 wt%. Regulatory compliance for non-food retail bags rests on EU Directive 94/62/EC, with the sum of lead, cadmium, mercury, and hexavalent chromium below 100 mg/kg in the packaging article, plus applicable REACH Annex XVII restrictions. Where the bag contacts unpackaged produce, FDA 21 CFR 177.1520(c) applies. Tensile yield is determined under ASTM D882, Elmendorf tear under ASTM D1922, and dart impact under ASTM D1709. Terminal products include T-shirt carry-out bags, produce bags, and thin retail sacks.

High-stalk bubble instability is the main production bottleneck when the line runs above 150 kg/h, particularly on 65–90 mm extruders. If melt-flow variation deviates outside the supplier’s certified interval, the stalk height changes beyond the air-ring sensing range and gauge variation exceeds ±6%, which causes downstream printing misregister. The MD/TD tensile yield ratio is held between 1.5:1 and 2.5:1 to balance bag opening force and sag; adjustment is made through blow-up ratio and frost-line height rather than screw speed alone. Melt-pressure fluctuation at the die inlet should remain below ±10 bar for consistent gauge output.

A monolayer HDPE web destined for breakfast cereal liners, cracker sleeve liners, and dry powder sachets is typically converted at 20–30 µm with a blow-up ratio of 3:1–4:1 and a die gap of 1.0–1.5 mm. The high-density backbone contributes deadfold and high film modulus, which are primary performance properties for boxed dry food liners. The film is usually corona-treated in-line to 36–42 dyn/cm before printing or lamination. Extrusion is performed at 200–220 °C melt temperature on lines with internal bubble cooling to prevent gauge scatter above ±4% at the high stalk heights needed for this density class. Pre-drying is not required because HDPE is not hygroscopic; feedstock stored under condensation conditions with relative humidity above 60% RH should be purged with dry air in the hopper to avoid surface moisture streaks.

HE2557 can be used at 100 wt% when maximum moisture vapour resistance and deadfold are specified; alternatively, 70–90 wt% HE2557 with 10–30 wt% LDPE or LLDPE reduces film modulus and improves dart impact but shifts the moisture barrier away from the HDPE-only configuration and softens deadfold. Slip is controlled with erucamide at 500–1,000 ppm and antiblock with synthetic silica at 1,000–2,000 ppm. Direct food contact compliance is assessed under FDA 21 CFR 177.1520(c) and EU Regulation (EC) No 10/2011; overall migration must not exceed 10 mg/dm² under Annex V. Water vapour transmission rate is evaluated under ASTM F1249, and tensile properties under ASTM D882. Terminal products include breakfast cereal liners, cracker sleeve liners, dry soup pouches, and mineral powder sachets.

In waste containment liners, the extrusion line is typically a grooved-feed single-screw extruder with L/D 25:1–30:1, a barrier mixing section, and a dual-lip air ring with internal bubble cooling for gauge control at 20–60 µm thickness. Melt temperature is held between 210–230 °C; die gap is set at 1.2 mm; blow-up ratio is maintained between 3:1 and 4:1. The central conversion conflict is the difference between high-density film stiffness and low tear propagation resistance: HE2557 provides tensile yield and load-bearing capacity, but Elmendorf tear under ASTM D1922 falls below that of LLDPE-rich film. Where tear resistance is contractually required, 10–20 wt% LLDPE is introduced, which narrows the high-stalk bubble stability window and may require a reduction in frost-line height.

HE2557 is loaded at 70–100 wt%; LLDPE enters at 0–20 wt%; post-industrial or post-consumer HDPE regrind enters at 0–30 wt% only if melt filtration at 100 µm or finer is active and the incoming recyclate is tested for gel and moisture contamination. Carbon black masterbatch is dosed at 2–3 wt% for opacity and outdoor resistance; a UV stabiliser masterbatch may be added at 2–3 wt% where sacks are stored under direct sunlight. Regulatory compliance is non-food: REACH Regulation (EC) No 1907/2006 Annex XVII restrictions and EU Directive 94/62/EC heavy-metal limits apply to the finished packaging. Where the liner is used inside dangerous-goods outer packaging, the complete package must be evaluated under the applicable UN performance test for the planned packing group; the liner alone does not carry a UN mark. Terminal products include industrial refuse sacks, waste collection liners, and high-gauge stockroom disposal sacks.

Multi-wall Paper Sack Inner Liner Extrusion and Surface Corona Treatment

Tubular HDPE liner for multi-wall paper sacks is produced at 20–40 µm with gusseting and in-line perforation to release air during filling. The film is blown at a blow-up ratio of 3:1 and a die gap of 1.0–1.3 mm, with melt temperature between 200 °C and 220 °C. Corona treatment is required for subsequent adhesive lamination or ink adhesion, with surface tension controlled between 38 dyn/cm and 42 dyn/cm; higher treatment levels increase blocking tendency in roll storage. Acclimatisation after cold storage is required for 24 h before slitting and insertion to prevent condensation-induced slip variation.

HE2557 is used at 100 wt% when the sack is filled with moisture-sensitive food powders or mineral powders because the high-density film provides low water vapour transmission; for applications requiring a lower heat-seal initiation temperature, 80–90 wt% HE2557 with 10–20 wt% LDPE is used. Antiblock and slip are controlled in the same ranges as dry-food film, but antistatic masterbatch may be required at 1–3 wt% where the sack is filled with fine dust. Direct and indirect food-contact status follows FDA 21 CFR 177.1520(c) and EU Regulation (EC) No 10/2011, with overall migration below 10 mg/dm². When the liner is used for non-food chemical powders, the relevant safety data sheet and REACH requirements govern compatibility. Terminal products include inner liners for pet food sacks, flour and sugar sacks, powdered detergent sacks, and dry mineral and construction powder sacks.

When a Vapor Retarder Must Pass ASTM E96 Procedure A with Limited Permeance Data

Where HE2557 is converted into a building vapor retarder, the governing measurement is moisture vapor transmission under ASTM E96 Procedure A, commonly reported at a test condition of 23 °C with a desiccant chamber. The film is supplied at 100–200 µm for underslab and crawl-space membranes; production is performed on blown-film lines with internal bubble cooling, die gap 1.2–1.5 mm, blow-up ratio 2.5:1–3.5:1, and melt temperature 210–230 °C. Because building code vapor retarder requirements vary and published data for HE2557 in this exact configuration is limited, the permeance value must be confirmed by third-party testing of the finished film at the specified thickness rather than inferred from resin class.

HE2557 is used at 100 wt%, with carbon black masterbatch at 2–3 wt% or a UV-stabilised additive package where the membrane is exposed to ultraviolet light during construction delays. The addition of recycled HDPE is not recommended for code-critical vapor retarder membranes because recyclate-driven gel counts can create pinhole defects that compromise the desiccant-method permeance result. Mechanical strength is checked under ASTM D882 and impact resistance under ASTM D1709; no direct food-contact standards apply, but REACH and local building product declarations remain applicable. Terminal products include underslab vapor barriers, crawl-space membranes, and wall vapor retarders.