Bapolene® 142A is a high-pressure low-density polyethylene film resin with a nominal melt flow rate of 2.0 g/10 min at 190 °C under 2.16 kg load per ASTM D1238-20 or ISO 1133-1:2022. The nominal density is 0.922 g/cm³ per ASTM D1505-18 or ISO 1183-1:2019. Heavy-duty industrial liners in the 80–150 μm range are converted on single-layer blown film lines equipped with a 60 mm grooved-feed extruder and a 30 L/D barrier screw. Feed throat temperature is kept at 35–45 °C to prevent pellet bridging in the grooved section. Zone temperatures from feed to die are set at 160 °C, 175 °C, 185 °C, 190 °C, and 195 °C. A 1.8 mm die gap is used for a final 100 μm liner. Screen pack configuration is 60/80/100 mesh. Head pressure is held below 350 bar. A pressure rise above 350 bar at constant screw speed indicates melt filtration blockage or pellet-size instability. Blow-up ratio is held between 1.8:1 and 2.2:1. Frost-line height is maintained at 5–8 die diameters. Above this range, the bubble oscillates and gauge bands form at the fold edges. Capacitance thickness profiling should be run continuously because LDPE melt strength can mask minor melt delivery instability until tear or puncture testing. Gauge variation is held to ±5% on a well-centred bubble. Above 8%, thin spots become failure zones in tear and puncture testing. Puncture resistance is evaluated by drop-dart impact per ASTM D1709-16A. Elmendorf tear resistance is measured by ASTM D1922-15. The end product is used for construction debris, industrial waste, and medical waste liners. No food-contact claim applies to this segment. REACH Regulation (EC) No 1907/2006 applies to the supplied resin. Downstream converters must perform SVHC screening for any added masterbatch.

Coextruded Food-Contact Film at 30 μm Gauge with EVA Skin Layers

Food packaging structures use 142A in the core or outer layer of three-layer blown film. The layer ratio is typically 20/60/20 or 10/80/10. Skin layers are EVA with 18 wt% vinyl acetate for low-temperature seal initiation. Melt temperature is maintained at 190–200 °C. At 200 °C, the melt strength of 142A stabilizes the bubble. Above 210 °C, the as-supplied stabilizer package can undergo oxidative depletion. The film is not intended for retort or hot-fill above 85 °C. Seal initiation occurs near 105 °C on a 30 μm film with EVA skins. Heat-seal strength is measured by ASTM F88/F88M-15. Hot tack is evaluated by ASTM F1921. The olefin base is covered under 21 CFR 177.1520. Finished articles must meet FDA conditions of use. In the European Union, the finished structure must meet the overall migration limit of 10 mg/dm² per EU 10/2011. Regrind is allowed only if generated from the same food-contact line and free of printing ink. Amide-based slip agents in EVA skins can raise seal initiation temperature. Compatibility must be tested before qualification. LDPE does not provide oxygen barrier. If oxygen or aroma barrier is required, the structure must include aluminium foil, EVOH, or PVDC. Terminal products include frozen vegetable pouches, bakery film, and cheese wrap.

Regulatory checks for 142A-based food films are summarized in the matrix below.

Silage wrap at 25 μm gauge is made using 142A as the base resin. The as-supplied pellet is not marketed as a cling-containing grade. Polyisobutylene or a metallocene polyolefin plastomer tackifier is added at 2–6 wt%. HALS-based UV stabilizer is added at 0.3–0.6 wt% for one-season weathering. The film is extruded on a 70 mm high-output blown film line with internal bubble cooling. Melt temperature is held at 185–195 °C. Blow-up ratio is set at 2.5:1 to balance machine-direction and transverse-direction stretch. During wrapping, the film is pre-stretched 60–70%. The film must not be corona treated. Corona treatment increases surface energy and can cause overly aggressive cling, resulting in difficult roll unwind. Tensile strain at break is measured by ASTM D882-18. UV retention of tensile elongation is assessed by ASTM G154-16 with UVA-340 lamps for 500 h. Finished rolls stored above 30 °C can undergo cling migration. This produces layer blocking and uneven unwind tension on the wrapper. Field failures usually appear at the overlap seam where cling force is lowest. The terminal product is round bale wrap for haylage and corn silage.

Can 142A Serve as a 15 wt% LDPE Component in LLDPE-Rich Collation Shrink Film?

Shrink bundling lines for bottles and cartons demand stable bubble geometry and low melt fracture. 142A is dry-blended with metallocene LLDPE at 15–25 wt% LDPE fraction. The dry blend is fed to a 50 mm smooth-bore extruder with a barrier screw. Melt temperatures are maintained at 200–210 °C. A dual-lip air ring is used. Blow-up ratio is set at 2.0:1 to 2.5:1. Frost-line height is kept at 9–12 die diameters to increase machine-direction orientation. The LDPE fraction raises bubble stability and reduces neck-in. The LLDPE fraction retains dart impact strength. Silica antiblock is added at 0.5–1.0 wt% to prevent blocking on the reel. Haze is measured by ASTM D1003-13. Free shrink is measured by ASTM D2732-14 after 10 s immersion in a 120 °C bath. On a 50 μm film, the LDPE fraction can raise shrink tension. At addition levels above 25 wt%, dart impact can decline sharply. Published dart impact data for this exact dry blend is limited. Converter trials are required before commercial settings are fixed. The terminal application is bundling of canned goods and multipack cartons.

When 142A is Used as the Sealant Layer in Adhesive-Laminated Structures

Single-serve sachets and barrier pouches use a blown 142A-based sealant web laminated with adhesive to oriented polyester or biaxially oriented polypropylene. The construction is often printed film, adhesive, aluminium foil, adhesive, and a 30–50 μm sealant web. The sealant web is produced in a separate blown film step. Melt temperature is kept at 185–195 °C. Gels are the primary rejection criterion. Gel particles from degraded resin produce pinholes in thin foil laminates and reduce seal integrity. Seal strength is measured by ASTM F88/F88M-15. Seal initiation occurs near 105–115 °C depending on gauge and dwell time. For food use, the olefin base is covered by 21 CFR 177.1520 or EU 10/2011. The structure is not intended for high-fat foods above 60 °C. LDPE can swell with fatty simulants, increasing overall migration test results. For pharmaceutical packaging, the converter must verify pharmacopoeial requirements separately. Terminal structures are sachets, lid stock, and barrier pouches.

Surface protection film for powder-coated aluminium profiles uses a 40 μm coextruded web with a 142A backing layer and an EVA-based adhesion layer. The backing is produced on a cast film line at 220–240 °C melt temperature. Cast film is preferred for low gel counts and uniform thickness. The outer surface may be corona-treated to 40–42 dyn/cm wetting tension per ASTM D2578 for printing or coating. The adhesion layer is not corona-treated. Adhesion is tested per ASTM D3330/D3330M-02(2017) at 180° peel angle. Controlled peel strength is necessary to avoid adhesive transfer to the profile after 3 months of outdoor storage. The base resin has limited UV resistance. It must be UV-stabilized for extended exterior exposure. Contamination with dust or silicone from the extrusion floor can reduce peel uniformity. Peel force drift of more than 0.2 N/25 mm across a coil is used as a rejection limit. The terminal product is temporary protection for window frames and aluminium extrusions.

In pallet stretch-hood conversion, 142A is used as a melt-strength modifier in a metallocene LLDPE-rich film at 60–80 μm. The LDPE fraction is typically 10–20 wt%. The film is blown on a 1200 mm die with internal bubble cooling. Melt temperature is set at 190–205 °C. Blow-up ratio is kept at 2.0:1–2.4:1. Frost-line height is lowered to 7–9 die diameters to improve impact resistance. The film must maintain yield stress high enough to secure pallet loads during transport. Tensile yield is measured by ASTM D882-18. Puncture resistance is measured by ASTM D5748-95. Gauge variation is monitored by capacitance thickness measurement. Gauge variation above ±5% produces uneven stretch force around the pallet. The terminal application is pallet unitization for construction materials and industrial bags.