On high-output cast stretch film lines, Versalis Clearflex VLDPE MQ F0 is preferably allocated to the outer cling layers rather than the core, because the low crystalline fraction of the grade reduces the energy needed to activate cling under pre-stretch. The converter verifies density and melt-flow-rate consistency on every silo discharge using ISO 1183-1 and ISO 1133-1:2022 at 190 °C and 2.16 kg. In a five-layer A/B/C/B/A cast structure, the two outer A layers are formulated with 20–35 wt% MQ F0 blended into a C6-LLDPE with melt index 2.5–3.5 g/10 min, while the B sub-skin layers are 10–15 wt% each and the C core is a higher-melt-strength LLDPE or LDPE/LLDPE blend. The tackifier system is added only to the outer layers at 0.8–2.0 wt% polyisobutylene or 0.5–1.5 wt% sorbitan monooleate, and synthetic silica antiblock is maintained at 0.1–0.3 wt%. The antioxidant package is 0.03–0.06 wt% primary phenolic stabiliser plus 0.05–0.10 wt% phosphite processing stabiliser. On a typical cast line with a 2,000 mm die, the operating window is 240–270 °C melt temperature, 0.55–0.90 mm die gap, 150–250 mm air gap, and chill-roll temperature 18–26 °C. Line speed for 17–23 µm machine film is 500–700 m/min. The main failure mode is die-lip build-up from low-melt-strength resin fractions; the die should be purged every 4 h or at polymer lot changes to avoid gauge bands. Finished machine film is evaluated by ASTM D5748 for puncture resistance, ASTM D5458 for peel cling, and ISO 527-3 for machine-direction elongation.

Finished pallet wrap is commonly supplied as 450 mm wide rolls of 23 µm film; pre-stretch at the customer machine can reach 200–250%. Food-contact pallet wrap used as secondary packaging falls under EU 10/2011 with an overall migration limit of 10 mg/dm² and FDA 21 CFR 177.1520 for olefin polymer articles. If the wrap does not directly contact food, the converter may use the compliance letter for the food-contact grade as supporting documentation only.

What Controls Seal Initiation in High-Speed Flexible Packaging Lines?

A sealant web based on MQ F0 is compounded into the inner layer of multilayer blown film where the critical variable is hot-tack force at short dwell, not only seal initiation temperature. The sealant layer is melt-blended at 60–80 wt% with a fractional-melt C6-LLDPE at 20–40 wt%, an antiblock masterbatch at 0.05–0.10 wt% active synthetic silica, and a slip masterbatch at 0.03–0.05 wt% erucamide; the antiblock-to-slip ratio is maintained above 2:1 to prevent seal-strength loss from surface bloom. In a three-layer coextrusion blown-film line with die diameter 200–350 mm, blow-up ratio 2.0–2.5, die gap 1.6–2.2 mm, and mass output 220–300 kg/h, the sealant layer is positioned on the inside of the bubble to reduce melt-pressure-induced roughness and to avoid excessive cooling on the outer bubble skin. Melt temperature is held at 185–205 °C; sustained operation above 210 °C produces gel flecks from degradation of the low-crystalline fraction. The sealant layer should not be drawn below 8 µm finished thickness; at lower thickness the sealant web loses hot-tack force and fails at gusset creases. The terminal pouch structures are 45–70 µm total thickness and seal at packaging speeds exceeding 80 pouches/min on vertical form-fill-seal machines. Seal initiation for metallocene VLDPE sealants is commonly reported in the 85–100 °C range under laboratory conditions, although published grade-specific SIT data for Clearflex VLDPE MQ F0 is limited; converters must validate the value with ASTM F1921 using 0.5 s dwell and 0.27 MPa sealing pressure. Final seal strength is measured by ASTM F88 after 24 h ageing and should exceed 2,000 g/25 mm for high-speed snack and dry powder applications. Direct food contact compliance rests on FDA 21 CFR 177.1520 for olefin polymers, EU 10/2011 with overall migration below 10 mg/dm², and good manufacturing practice under EC 2023/2006.

When MQ F0 is selected as the sealant coating in extrusion lamination on aluminium foil or metallised polyester, the converter operates at a higher melt temperature than in blown film to lower melt viscosity and promote substrate wetting. A typical line employs a 90 mm single-screw extruder with L/D 30:1, die width 1,100–1,400 mm, die gap 0.5–0.8 mm, and air gap 200–250 mm. The resin is blended with 10–25 wt% LDPE to raise neck-in resistance and with 0.02–0.05 wt% processing stabiliser to survive the higher heat history; melt temperature is set at 270–300 °C and line speed at 150–300 m/min. Coating weight is controlled to 20–30 g/m² for aluminium foil sachets; below 15 g/m² pinhole density increases sharply due to edge tearing and incomplete substrate wetting. Slip and antiblock additives are intentionally omitted from grades used in retort lamination because migration to the seal interface after steam retorting reduces seal strength. Terminal products are pharmaceutical sachets, stick packs, and condiment sachets. Seal strength after lamination is required above 1,800 g/25 mm per ASTM F88. For food contact, the structure falls under EU 1935/2004, EU 10/2011 with an overall migration limit of 10 mg/dm², and GMP under EC 2023/2006; for pharmaceutical sachets the converter must additionally assess printing ink and adhesive layers because the PE coating alone does not determine the full migration profile.

For converters supplying European and North American food-contact markets, the following documents apply to films containing Clearflex VLDPE MQ F0 as the food-contact layer.

Heavy-Duty Liner Extrusion: Avoiding Gauge Variation at High Draw-Down

Draw-down behaviour changes once the extruder is operated above 150 kg/h with a low-density grade such as MQ F0 in the blend, because the resin contributes low melt tension and increases bubble instability if the stalk is too short. The grade is introduced at 15–30 wt% into a C6-LLDPE matrix in a monolayer or three-layer blown-film line with die diameter 250–400 mm, BUR 2.0–2.8, frost line height 800–1,200 mm, die gap 1.5–2.2 mm, and melt temperature 180–200 °C. The terminal product is an 80–150 µm heavy-duty liner, drum liner, or FIBC inner liner in which the VLDPE fraction improves low-temperature flex-crack resistance. Release tests are based on ISO 7765-1 dart impact and ISO 6383-2 Elmendorf tear; a 100 µm industrial liner commonly requires dart impact above 200 g and tear strength above 5 N/mm, although published data for this specific configuration is limited and must be confirmed on the converter’s own line. The main extrusion conflict is gauge variation at high draw-down; increasing VLDPE content above 30 wt% often causes wide transverse-direction thickness variation unless the air ring is operated with an inward lip set and the frost line is raised. Non-food industrial liners are not subject to food-contact migration limits, but REACH candidate-list screening applies under EC 1907/2006.

If the Film Must Survive −25 °C Distribution, Structure the Core Layer Differently

For films intended to withstand −25 °C distribution, the low-crystalline fraction of MQ F0 is used to maintain sub-zero ductility, but the film structure must be stiffer in the core to prevent elongation-related registration faults on packaging machines. A five-layer blown structure places MQ F0 at 20–35 wt% in the sealant layer and 5–15 wt% in the core layer, with the remaining resin a 1.0 MI C6-LLDPE. Blow-up ratio is kept low at 1.8–2.2, melt temperature at 175–195 °C, and die gap at 1.5–2.0 mm. The terminal products are pre-formed frozen food bags, vacuum pouches for individually quick-frozen vegetables, and ice-block liners. The film is conditioned at −25 °C for 24 h before dart impact testing according to ISO 7765-1, and seal strength is measured after 48 h at −20 °C according to ASTM F88. The specific failure mode at sub-zero is sealant-layer brittle fracture at the seal shoulder; to prevent it, the sealant layer should be at least 8 µm thick and should not contain migratory slip or tackifier packages. Food contact compliance for frozen food films follows EU 10/2011 and FDA 21 CFR 177.1520; overall migration must remain below 10 mg/dm².

Mechanical recycling lines running post-consumer PP often contain residual polyethylene; the metallocene-catalysed VLDPE Clearflex MQ F0 can be introduced as a non-peroxide impact modifier in recycled polypropylene compounds for low-temperature notched impact. In a co-rotating twin-screw extruder with L/D 40:1 and barrel set points of 190–220 °C, addition of 5–15 wt% VLDPE to post-consumer PP homopolymer or copolymer improves impact dissipation at the expense of stiffness; the stiffness trade-off is determined by ISO 178 flexural modulus before and after compounding because published data for MQ F0 in recycled PP modification is limited. The screw profile requires two mixing zones with kneading-block staggering of 45° and 90° to disperse the VLDPE domains below 2–5 µm; coarser morphology produces weld-line weakness in injection-molded parts. Injection moulding is performed at clamp force above 1,500 kN, injection speed 80–120 mm/s, and mould temperature 25–40 °C. Terminal products are returnable transport crates, automotive interior trim panels, and appliance fascia parts. Notched Charpy impact is measured by ISO 179-1 at 0 °C, and the impact increase from a 10 wt% addition depends on the contamination level and viscosity ratio of the PCR feedstock; pilot-scale compound trials are required before commercial production. The compound must be stabilised with 0.05–0.10 wt% secondary antioxidant to survive repeated heat histories. Industrial articles made from recycled PP compounds are outside the direct food-contact scope of FDA 21 CFR 177.1520 and EU 10/2011 unless a functional barrier is demonstrated; REACH candidate-list screening under EC 1907/2006 remains applicable.