In blown stretch film lines equipped with 45:1 L/D grooved-feed extruders and 1,800–2,500 mm slot dies, Clearflex VLDPE CL D0 is metered as a minority-phase impact modifier into Ziegler-Natta LLDPE formulations at 15–30 wt%. The grade, characterized by a density below 0.910 g/cm³ per ISO 1183 and a melt flow rate in the 1.0–2.5 g/10 min window per ISO 1133-1, lowers the crystalline fraction after chill-roll solidification and modifies elastic recovery measured at 200% elongation per ASTM D5459. At 15 wt% addition, gauge variation across a 20 µm film remains within ±0.8 µm on calender rolls maintained at 18°C; at 25–30 wt% addition, the film is used only for pre-stretch units exceeding 250% because the lower modulus reduces roll hardness and increases telescoping risk on high-speed wrappers. Melt temperature is held at 215–245°C, die pressure at 90–140 bar, and line speed at 450–650 m/min. The cast film’s puncture resistance before stretch is typically above 0.9 J per ASTM D5748, and retained puncture at 200% pre-stretch remains above 0.35 J. Unwind tension on finished rolls must be kept below 8 N per 500 mm web width when the CL D0 fraction exceeds 25 wt%, otherwise roll telescoping is observed after 72 h storage at 35°C.Formulation for a 23 µm machine film is 70 wt% hexene LLDPE with density 0.918 g/cm³ and MFR 1.0 g/10 min, 25 wt% Clearflex VLDPE CL D0, 5 wt% high-clarity antistatic masterbatch, and 2,000 ppm erucamide slip to achieve a kinetic coefficient of friction below 0.18 per ASTM D1894. The CL D0 component shifts the MD tensile modulus from 160 MPa to 120 MPa and increases MD elongation at break above 450% per ASTM D882. Production experience on three-layer cast lines indicates that barrel temperature in the feed zone must remain below 60°C to prevent pellet bridging and melt starvation when CL D0 is dry-blended without a gravimetric mixer; pre-drying at 70°C for 2 h is required only when storage relative humidity exceeds 60% to avoid moisture-related edge pinning and bubble formation at the die lip. The end product is machine stretch wrap for intralogistics and beverage tray unitisation, not intended for direct food contact, and is evaluated for heavy metals by RoHS 2011/65/EU Annex II screening only when recycled-content backers are used.

Which blend ratio shifts seal initiation below 90 °C in coextruded sealant webs?

In three-layer coextruded pouch films with a sealant skin of 12–18 µm, Clearflex VLDPE CL D0 is dry-blended into a 1.0 g/10 min hexene LLDPE at 30–50 wt% to depress seal initiation temperature. Differential scanning calorimetry per ISO 11357-3 shows a shoulder in the melting endotherm between 90°C and 105°C, which controls the onset of interfacial fusion and reduces the minimum seal contact temperature required to form a load-bearing bond. At 40 wt% addition, seal initiation temperature, defined as the temperature at which 4.4 N/25 mm seal force is achieved on a laboratory heat sealer, drops by 8–14°C relative to the neat LLDPE control. Hot-tack force measured on a J&B Hot-Tack Tester 4000 per ASTM F1921 increases from 1.8 N/25 mm to 3.2 N/25 mm at 105°C at a dwell time of 0.5 s and a cooling time of 0.1 s. Above 50 wt% CL D0, the hot-tack plateau widens but blocking occurs on the inner seal layer after 7 days of roll storage at 35°C; anti-blocking masterbatch addition above 8,000 ppm is then necessary to maintain roll unwinding without fibre tear.The seven-layer blown film line uses a 350 mm annular die with 2.2 mm die gap, blow-up ratio 2.2, frost line height 850 mm, and melt temperature 210°C for the seal skin. Throughput is 220 kg/h with internal bubble cooling maintaining frost line stability. The sealant layer formulation is 60 wt% hexene LLDPE, 35 wt% Clearflex VLDPE CL D0, 5 wt% polypropylene-based anti-block masterbatch, and 1,500 ppm migrating slip. The seal strength after flat-bar sealing measured per ASTM F88 remains above 18 N/25 mm for a 15 µm seal layer at 115°C, and the oxygen barrier EVOH core is not affected when the tie layer is selected from anhydride-modified polyethylene grades. For direct food contact, the sealant complies with FDA 21 CFR 177.1520(c) 3.2a and EU Regulation (EU) No 10/2011 Annex I with an overall migration limit of 10 mg/dm². End products include fresh-cut salad pouches, frozen seafood bags, and vertical form-fill-seal snack packages; published data for this specific configuration is limited when sealant thickness drops below 8 µm, so pilot trials are required for ultra-thin seals.

Application zone	CL D0 addition	Process condition	Property threshold	Test method
Cast stretch film	25 wt% in hexene LLDPE	Melt 230°C, line 600 m/min	Retained puncture above 0.35 J at 200% pre-stretch	ASTM D5748
Coextruded sealant web	35 wt% in hexene LLDPE	Seal bar 115°C, dwell 0.5 s	Seal strength above 18 N/25 mm	ASTM F88
Extrusion lamination	15 wt% in autoclave LDPE	Melt 305°C, line 250 m/min	Neck-in below 40 mm	Die-edge measurement
Frozen food core layer	30 wt% in hexene LLDPE	Die gap 2.2 mm, BUR 3.0	Dart impact at -18°C above 250 g	ISO 7765-1 method A

In tandem extrusion lamination of 12–20 g/m² polyethylene sealant webs onto aluminium foil or PET at 200–300 m/min, Clearflex VLDPE CL D0 is added at 10–20 wt% to autoclave LDPE with a melt flow rate of 7.5 g/10 min to reduce neck-in and improve fibre tear bond strength. The blend is processed through a 90 mm single-screw extruder with 30:1 L/D and a 1,200 mm slot die, with adapter and die zones at 285–305°C. At 15 wt% addition, neck-in measured from the die edge to the coated web is reduced from 55 mm to 38 mm at 250 m/min, while bond strength to 12 µm PET increases from 1.2 N/15 mm to 2.1 N/15 mm per ASTM F904. Above 20 wt% addition, draw resonance appears at line speeds above 260 m/min because the lower zero-shear viscosity and broader relaxation spectrum reduce melt tension; raising the die temperature by 5–8°C restores stability without requiring a wider die gap. Chill roll temperature is maintained at 15°C, and the melt curtain is quenched within 150 mm of the die exit to limit oxidative surface degradation.The applied coating weight is controlled gravimetrically, and the molten web is quenched on a 400 mm diameter chill roll at 15°C. Formulation is 85 wt% autoclave LDPE of 7.5 g/10 min, 15 wt% Clearflex VLDPE CL D0, 250 ppm phenolic antioxidant, and 150 ppm phosphite antioxidant. For food-contact sachets and retort lidding, the structure complies with EU Regulation (EU) No 10/2011 Annex I and FDA 21 CFR 177.1520(c) 3.1a; specific migration of primary aromatic amines is not applicable because no aromatic amine-based additives are introduced. End products are laminated stand-up pouches, detergent sachets, and aseptic cup lids. Pre-drying at 80°C for 1 h is used when line stops exceed 30 min and ambient relative humidity exceeds 60%, because surface moisture on the pellets increases pinhole frequency in the coated web.

Frozen Food Core Layer Tear Resistance and Subzero Puncture Retention

In five-layer frozen vegetable packaging produced at 60–80 µm total thickness, Clearflex VLDPE CL D0 is compounded as 25–40 wt% of the core layer to maintain tear and puncture integrity after frozen storage at -25°C for 90 days. The film is extruded on a blown film line with internal bubble cooling, 300 mm die, die gap 2.0–2.4 mm, blow-up ratio 2.8–3.2, frost line height 900–1,100 mm, and melt temperature 195–210°C. At 30 wt% CL D0 in a hexene LLDPE core, Elmendorf tear strength in the machine direction remains above 10 N per ASTM D1922, and dart impact at -18°C remains above 250 g per ISO 7765-1 method A. The low-density phase reduces the ductile-to-brittle transition temperature of the core by disrupting the crystalline lamellae, which is measurable as a 6–10°C shift in the low-temperature impact curve obtained per ISO 8256. Energy to break at -25°C remains above 3 J for the CL D0 core blend, compared with 1.5 J for an unmodified hexene LLDPE control of equivalent melt index.The structure has an outer skin of HDPE for abuse resistance, a tie resin, EVOH barrier, and an inner sealant of metallocene LLDPE. The core formulation is 70 wt% hexene LLDPE, 30 wt% Clearflex VLDPE CL D0, 3,000 ppm processing aid, and 2,500 ppm silica anti-block. The film structure is not intended for direct food contact from the core layer, but the food-contact layers comply with EU Regulation (EU) No 10/2011. End products include frozen spinach bricks, mixed vegetable pouches, and ready-to-cook frozen dumpling bags. Blocking between film layers at -20°C is avoided by keeping the core layer CL D0 content below 40 wt%; above 40 wt%, the film exhibits measurable roll blocking after 30 days of cold storage because the softer core deforms under winding tension and increases the contact area at the film interlayer.

When Geomembrane Welding Requires Low-Temperature Dwell Time

In flat die geomembrane sheet lines producing 1.0–2.5 mm thick high-density polyethylene membranes, Clearflex VLDPE CL D0 is let down at 5–15 wt% to improve wedge-weld peel strength at 0°C ambient. The lower crystallinity of CL D0 slows recrystallisation after the hot wedge passes, extending the available welding window by 6–10°C at a travel speed of 1.2 m/min. Stress-crack resistance on notched specimens per ASTM D1693 using 10% Igepal CO-630 at 50°C is above 500 h for the 95 wt% HDPE/5 wt% CL D0 blend versus 120 h for unmodified 0.5 MI HDPE. The blend is produced on a 52:1 L/D co-rotating twin-screw extruder at 230°C, pelletised, and then extruded through a 120 mm single-screw flat die line at 260°C with polished rolls set to 40°C. Low-temperature flexibility is monitored by bend tests at -20°C; the blend does not exhibit surface cracking after a 180° bend around a 50 mm mandrel, while unmodified HDPE shows stress whitening.Formulation for a 1.5 mm membrane is 93 wt% HDPE with density 0.945 g/cm³, 5 wt% Clearflex VLDPE CL D0, and 2 wt% carbon black masterbatch with UV stabiliser package. For European intended use, the compound is registered under REACH Regulation (EC) No 1907/2006 and does not include Substances of Very High Concern; RoHS 2011/65/EU screening is performed for landfill-sited membranes because of potential exposure to leachate heavy metals. End products include landfill liner base layers, temporary pond liners, and canal lining membranes. Published data for this specific configuration is limited; welder speed and temperature settings must be revalidated when the CL D0 addition exceeds 10 wt% because the softer melt lowers the wedge re-melt pressure and can create asymmetric weld bead profiles.

Carrier Resin Behaviour Is Governed by Low-Crystalline Chain Mobility in High-Pigment Masterbatch Mixing

For 40–60 wt% carbon black or 50–70 wt% titanium dioxide masterbatch production on co-rotating twin-screw extruders with 26–40:1 L/D and downstream side stuffing, Clearflex VLDPE CL D0 acts as a low-crystallinity carrier that accepts filler without the viscosity collapse observed with high-MFR wax-based carriers. The resin is fed in the main hopper and the pigment is side-stuffed at a melt temperature of 180–200°C, with specific energy input kept below 0.22 kWh/kg to limit oxidative chain scission. The resulting masterbatch has a melt flow rate of 2–8 g/10 min depending on filler loading, measured at 190°C/2.16 kg per ISO 1133-1, and is let down at 3–6 wt% into blown and cast polyethylene film grades. Filler dispersion is assessed by filter pressure value per EN 13900-5; a 40 wt% carbon black masterbatch targets a pressure rise below 1.5 bar on a 14 µm screen pack after 60 min. The compounding line is operated with barrel temperatures from 90°C at the feed zone to 190°C at the die, screw speed of 350–450 rpm, and side-feeder speed ratio adjusted to maintain 60–70% torque.The use of CL D0 as the carrier lowers the compounding melt temperature by 8–12°C compared with a 2 MI LDPE carrier, reducing pigment degradation and volatile emission. The masterbatch is not used as a direct food-contact article; it is incorporated into films and moulded parts that must comply with the relevant food-contact regulations in the final diluted state. End products include carbon black masterbatch for agricultural film, titanium dioxide masterbatch for dairy packaging, and additive masterbatches for stretch hood. Avoid combinations with polyethylene waxes melting above 110°C at levels above 2 wt%, because high-melting waxes phase-separate on the screw elements and cause plate-out on the die face, increasing die lip cleaning frequency on downstream blown film lines.

Application	EU compliance	US compliance	Test method
Cast stretch film	RoHS 2011/65/EU Annex II screening only with recycled content	Not direct food contact	ASTM D5748, ASTM D882
Coextruded sealant web	Regulation (EU) No 10/2011 Annex I, OML 10 mg/dm²	FDA 21 CFR 177.1520(c) 3.2a	ASTM F88, ASTM F1921
Extrusion lamination	Regulation (EU) No 10/2011 Annex I	FDA 21 CFR 177.1520(c) 3.1a	ASTM F904
Frozen food core layer	Regulation (EU) No 10/2011 for food-contact layers	Core layer not direct contact	ISO 7765-1 method A, ASTM D1922
Geomembrane	REACH Regulation (EC) No 1907/2006	Not applicable	ASTM D1693
Pigment masterbatch carrier	REACH Regulation (EC) No 1907/2006	Final article compliance after let-down	EN 13900-5