At a nominal density of 0.920 g/cm³ per ISO 1183-1:2019 and a melt mass-flow rate of 2.0 g/10 min per ISO 1133-1:2022 at 190°C under 2.16 kg, Evolue SP2320 is processed on cast film extrusion lines for pallet unitization stretch wrap. The melt temperature at the flat die exit is held between 245°C and 260°C to control oxidative gel formation while retaining sufficient melt fluidity for thin-gauge drawdown. On a 90 mm extruder with 30:1 L/D and a barrier screw, melt pressure before the screen pack reads 90–120 bar. The die gap is set at 0.5 mm, and the melt web is pinned to a 20°C chill roll by a vacuum box and an air knife operating at 4–6 bar. Line speed reaches 450–650 m/min without draw resonance. The core-layer formulation for machine stretch film is 72–80 wt% Evolue SP2320, 15–20 wt% C6-LLDPE of 0.918 g/cm³ density, 3–5 wt% VLDPE of 0.902 g/cm³ density, 2–4 wt% polyisobutylene tackifier with molecular weight 2,000–4,000 g/mol, and 0.3 wt% erucamide. Edge trim of 3–5 cm per side is generated at these line speeds, and in-line recycling is limited to 12 wt% because higher reclaim levels raise gel count and reduce clarity in the wound roll. The terminal article is a 15–23 µm machine stretch film pre-stretched to 200% on turntable wrappers. Food-contact suitability is governed by FDA 21 CFR 177.1520 for olefin polymers and EU No 10/2011 with an overall migration limit of 10 mg/dm² per EN 1186-1:2002, provided the tackifier and slip additives comply with their specific migration limits. Cast film production using SP2320 typically records melt temperature variation of less than ±2°C across the die width when automatic lip adjustment is deployed, but die-lip build-up from polyisobutylene at loadings above 4 wt% shortens the cleaning interval from 72 h to 48 h.

The sealant web function of Evolue SP2320 is derived from a narrow comonomer distribution and low extractables at the sealing surface rather than from calcium carbonate loading. On a 25 µm monolayer film sealed at 0.5 MPa for 0.5 s, seal initiation temperature is observed at 96°C per ASTM F2029-16. Hot tack strength reaches 4.5 N/25 mm at 115°C per ASTM F1921-18. CaCO₃ is omitted from this construction because a 2 wt% loading raises haze from 4% to 8% on a 45 µm film and alters the conductive heat-seal response. The formulation uses 800–1,200 ppm synthetic amorphous silica as antiblock, 600–1,000 ppm erucamide as slip, and 400–800 ppm polymer processing aid to reduce die-lip deposit on long runs. The sealant layer is coextruded on a 3-layer blown film line with an 80 mm 30:1 L/D extruder. Melt temperature is held at 200–210°C. Die gap is 2.0 mm, blow-up ratio is 2.2:1, and frost line height is set at 8 die diameters. The sealant layer occupies 20% of the total 45 µm structure. The terminal use is a lamination sealant web for dry-food pouches, typically bonded to 12 µm PET with a polyurethane adhesive. Seal strength of the finished lamination is measured per ASTM F88/F88M-15 after 0.5 s dwell. The narrow sealing plateau of SP2320 requires seal bar temperature control within ±5°C at high packaging speeds above 80 pouches/min; below 100°C the seal remains weak, while above 135°C film thinning at the seal radius becomes measurable.

What Controls Seal Initiation Temperature in CaCO₃-Free Sealant Webs?

Hot tack and seal initiation are controlled by the melting distribution of the narrow-branched metallocene chains and by the migration kinetics of erucamide to the surface. On production lines, the practical hot tack window of Evolue SP2320 is narrower than that of a conventional LDPE sealant, but the plateau is sufficient for vertical form-fill-seal operations running 40–60 cycles/min. The seal bar temperature is set to 115–125°C for 25–35 µm sealant thickness. The film is corona treated to 38 mN/m before lamination. Surface treatment decay is the main cause of intermittent lamination bond loss; roll storage beyond 6 months at warehouse temperature above 30°C requires retreatment control. The compliance matrix for this sealant web is anchored below.

RoHS is not the primary food-contact instrument, but it is applied when the sealant web is converted into packaging for consumer electronics accessories. The sealant film is not recommended for direct contact with high-fat liquid foods because the erucamide migration rate can approach the specific migration limit before the shelf-life endpoint. Published data for long-term migration of this grade into 95% ethanol at 40°C for 10 days is limited; converters therefore qualify the finished pouch, not the pellet, against the intended food simulant.

Double-Bubble Orientation with LDPE Blends and Shrink Force at 80°C

Collation shrink bundling of 330 mL cans and 500 mL PET bottles uses 40–50 µm film with balanced machine-direction and transverse-direction shrink. Evolue SP2320 is let down with LDPE to widen the second-bubble orientation window and to prevent bubble sagging at the water quench. The formulation is 60 wt% Evolue SP2320 and 40 wt% LDPE with melt index 0.3 g/10 min and density 0.923 g/cm³. A 70 mm extruder with a double-flight feed section runs first-bubble melt temperature at 185–195°C. The first bubble is water quenched at 12°C. Orientation in the second bubble occurs at 110–118°C, with machine-direction draw ratio 4.5:1 and transverse-direction bubble ratio 4.0:1. Shrink force at 80°C is measured under ISO 14616:1997, and commercial collation film reports 8–12 mN/mm in the machine direction. The terminal film has machine-direction shrinkage of 60% at 120°C and transverse-direction shrinkage of 20%. Compliance for non-direct food contact is governed by EU 94/62/EC with heavy-metal sum below 100 mg/kg. The processing boundary is defined by SP2320 content: above 70 wt%, the second bubble shows instability at the nip due to the low melt strength of the metallocene fraction, and below 50 wt%, the shrink force at 80°C drops below the level required to hold bottle multipacks during tunnel transit.

In multi-span greenhouse structures, a 150–200 µm three-layer covering film must retain tensile strength after 24 months of UV exposure and repeated wind loading. Evolue SP2320 is compounded with a stabilizer masterbatch containing 5000 ppm hindered amine light stabilizer and 3000 ppm benzotriazole UV absorber. The layer distribution is 10/80/10, with the stabilizer-rich outer layers protecting the SP2320 core. A 100 mm 30:1 L/D grooved-feed extruder processes the core layer at 210°C. The die gap is 2.4 mm, blow-up ratio is 2.8:1, and frost line height is set at 9 die diameters. Output is 350 kg/h. The terminal article is a 180 µm single-span greenhouse cover. Weathering verification uses ISO 4892-2 cycle 1 with irradiance 0.51 W/m² at 340 nm and black panel temperature 65°C. After 6000 h, tensile retention above 70% is required for installation in high-altitude agricultural zones. Compliance is assessed under EN 13206:2017 for mechanical properties and thickness tolerance. The main field limitation is dust accumulation on the film surface, which can reduce photosynthetically active radiation transmission by 12% within six months; this is a surface fouling effect and not a polymer degradation mechanism. Anti-drip additive exudation in SP2320-based film is slower than in EVA-based alternatives, but the condensation beading effect may require a higher loading of nonionic surfactant masterbatch.

When 180 µm Layer Thickness Must Retain Puncture Resistance at -20°C

Heavy-duty sack production for 25 kg to 50 kg polymer granules and fertilizer fill requires puncture resistance at sub-zero storage. Evolue SP2320 is coextruded as the core layer in a 3-layer film of total thickness 180 µm. The layer structure is 15% outer LDPE-rich layer, 70% SP2320 core, and 15% inner C4-LLDPE layer. Carbon black masterbatch is added at 2 wt% to the core only to maintain surface friction without contaminating seal welds. Process conditions use a 90 mm extruder, die gap 2.4 mm, blow-up ratio 2.0:1, frost line height 6 die diameters, and melt temperature 215°C. Output is 300 kg/h. The low blow-up ratio is required because the metallocene fraction reduces melt strength; above 2.5:1, lateral bubble oscillation becomes measurable at the collapsing frame. The tubular film is gusseted and surface-treated to 38 mN/m. The terminal article is an inner liner for flexible intermediate bulk containers. Compliance for FIBC packaging is referenced to ISO 21898:2004 for safe working load and drop test verification. Published data for specific sub-zero puncture values on this grade is limited; production lots are tested per ISO 7765-2 with a puncture speed of 50 mm/min at -20°C. The critical processing limit is bubble stability, not extruder plastication: high molecular weight LDPE addition above 10 wt% restores bubble geometry but reduces the metallocene-derived seal integrity at the bottom seam.

For frozen vegetable pillow packs, a 60 µm tubular film is converted on a 3-layer blown line with 93 wt% Evolue SP2320, 5 wt% LDPE, 1.5 wt% synthetic silica, and 0.5 wt% erucamide. Die gap is 2.0 mm, blow-up ratio is 2.5:1, frost line height is 8 die diameters, and melt temperature is 205°C. The film is corona treated to 40 mN/m. Coefficient of friction after 72 h conditioning is 0.15–0.25 per ISO 8295:1995. Dart drop at -25°C is measured on 60 µm film per ASTM D1709-16a Method A. Sealing through frozen particulate at -18°C requires a seal bar temperature of 125°C to produce 22 N/25 mm seal strength per ASTM F88/F88M-15. The terminal articles are 1 kg and 2.5 kg frozen vegetable pouches. Compliance is maintained under FDA 21 CFR 177.1520 and EU No 10/2011. No plasticizer is present in the formulation. The operational limitation is erucamide bloom at low storage temperatures: below 10°C, slip migration slows and the film may exhibit temporarily higher coefficient of friction until the packaged product reaches ambient distribution temperature. The film also requires a minimum seal bar temperature of 120°C when moisture frost is present on the sealing jaw, because the water film absorbs heat from the seal interface and delays polymer melt fusion.