In machine-applied cast stretch film lines operating at 400–700 m/min, Clearflex VLDPE CL B0 is introduced into the cling layer of a 3-layer A/B/A coextruded structure. The grade has nominal density 0.900 g/cm³ and melt flow rate 1.0 g/10 min at 190 °C/2.16 kg; these parameters require resin handling systems that avoid prolonged silo residence above 40 °C because pellet blocking can develop before the extruder throat. The cling layer formulation normally contains 30–60 wt% CL B0 with a C8-LLDPE carrier, and the core layer incorporates 10–20 wt% CL B0 to raise puncture propagation resistance without sacrificing drawdown. Processing on a cast line with a 30:1 L/D barrier screw and die gap between 0.5 mm and 0.8 mm requires melt temperatures held between 240 °C and 260 °C; excursions above 260 °C increase the probability of oxidized gel formation when edge-trim regrind is reintroduced into the core layer. The chill roll is controlled at 15–25 °C, and vacuum-box or electrostatic edge pinning is used to stabilize the web against transverse wrinkling. Compliance-relevant performance is checked under ASTM D5459 for stretch force retention, ASTM D5748 for puncture resistance, ASTM D1894 for cling coefficient of friction, and ISO 527-3 for tensile behavior. The converted end product is 12–25 µm machine pallet wrap, where CL B0 contributes to sustained peel cling and high extensibility under pre-stretch ratios in the range of 200–300%, although winding tension must be reduced relative to conventional LLDPE films to prevent blocking on the core. Operators report that when chill roll temperature exceeds 25 °C, cling-layer transfer to the metal surface increases and web break frequency rises at speeds above 600 m/min.

How does CL B0 lower EVA demand in domestic cling film while retaining hand adhesion?

Domestic cling film formulations based on CL B0 are processed either by cast extrusion at 190–220 °C with a chill roll set at 15–20 °C or by blown film with a blow-up ratio of 2.5:1–3.0:1 and a die gap of 1.2–2.0 mm. The resin is typically blended at 70–90 wt% with 10–25 wt% LDPE and 0.5–1.5 wt% anti-fog/processing aid masterbatch; the high inherent cling of CL B0 reduces the need for EVA or polyisobutylene tackifiers that can raise extractables and compromise organoleptic neutrality. For direct food contact, the grade is assessed under FDA 21 CFR 177.1520 and EU Commission Regulation 10/2011, with migration testing conducted in accordance with the prescribed food simulants for aqueous and fatty contact where applicable. End products are 10–12 µm household cling films and catering wraps with finger-pressure adhesion to glass, ceramic, and polyethylene terephthalate containers. The material is not intended as the sole oxygen barrier in modified-atmosphere packaging, and its low melting point limits continuous service to chilled or room-temperature food storage. In high-speed cast lines, the absence of a chill roll release agent can generate cling-layer transfer to the roll surface, so converters either add a low-level internal release aid or operate with polytetrafluoroethylene-coated nip rolls.

Coextruded Sealant Layer Architecture with CL B0 in PP-Based Lidding Systems

In lidding film structures for polypropylene and polyethylene terephthalate trays, CL B0 is employed in the sealant layer at 15–40 wt% blended with mLLDPE or LDPE to lower seal initiation temperature and improve seal-through-contamination response on filling lines. The sealant layer is coextruded at 5–15 µm onto a barrier core—typically EVOH or polyamide—and is positioned on the inner surface through a feedblock or multi-layer die. Processing windows are maintained at 220–250 °C melt temperature, with corona treatment of the outer surface to a wetting tension of at least 38 mN/m for subsequent printing or lamination. Seal performance is evaluated under ASTM F88 for seal strength and ASTM F1921 for hot tack; food-contact compliance relies on FDA 21 CFR 177.1520 and EU 10/2011. The resulting converted articles include 30–80 µm lidding films, stand-up pouches, and preformed sachets for dairy, produce, and snack applications, provided that sealant-layer thickness is not reduced below 5 µm on high-speed vertical form-fill-seal lines where jaw dwell times fall below 0.3 s. A practical boundary observed on such lines is that seal strength retention after contaminated sealing depends on the sealant layer achieving a minimum 38 g/25 mm hot tack under ASTM F1921; lower values produce peelable failures at the package corners.

When pallet loads require five-sided protection and vertical application over variable load heights, CL B0 is incorporated into a 3-layer blown stretch-hood structure at 20–50 wt% in the external and core layers, with 10–20 wt% high-molecular-weight LDPE added to stabilize bubble geometry. The blown film line is configured with a die diameter of 250–400 mm, die gap of 1.8–2.5 mm, blow-up ratio of 3.0:1–4.0:1, and melt temperature of 190–215 °C; the lower melt temperature offsets the reduced melt strength of VLDPE and prevents bubble flutter when the frost line is positioned 3–6 die diameters above the air ring. Compliance for non-food industrial load packaging is documented under REACH and the Packaging and Packaging Waste Directive 94/62/EC, while performance is verified under ASTM D5459 for elastic recovery and stretch force retention, ASTM D5748 for puncture propagation resistance, and ISO 527-3 for tensile elongation. Converted end products are gusseted stretch hoods with thicknesses of 80–160 µm, used on automatic horizontal or vertical stretch-hood machines to secure building materials, household goods, and beverage loads. The material is not recommended for outdoor storage beyond the packaging service life because VLDPE lacks UV stabilization unless a compounded UV masterbatch is added at the converter’s formulation stage.

When Frozen Distribution Requires Sub-Zero Film Impact Resistance

Blown film lines producing frozen food bags and form-fill-seal pouches run CL B0 at 10–25 wt% in an LLDPE/LDPE dry blend to retain dart impact energy at -18 °C while avoiding the stiffness increase associated with high-density polyethylene modification. The process uses a melt temperature of 170–200 °C, a die gap of 1.5–2.2 mm, and a blow-up ratio of 2.2:1–3.0:1; the frost line is raised only enough to reduce film haze without creating excessive orientation that would lower Elmendorf tear in the machine direction. Low-temperature impact is tested under ASTM D1709 or ISO 7765-1, seal integrity under ASTM F88, and food-contact status under FDA 21 CFR 177.1520 and EU 10/2011. End products are 40–80 µm frozen vegetable, seafood, and ice cream bags, plus printed pillow pouches for freezer-to-microwave applications where the sealant layer does not exceed the melting point of the resin during reheating. If oxygen barrier is required for product shelf life greater than 3–6 months, the structure must include an EVOH or polyamide barrier layer because CL B0 by itself provides insufficient gas barrier. Operators running high-stalk film lines with CL B0 have observed that melt temperatures below 170 °C produce unmolten domains in the die land, while melt temperatures above 200 °C can destabilize the bubble and increase gauge variation beyond ±5%.