Braskem LF 0720/21 AF enters agricultural blown film structures at 70–100 wt% of the polyethylene fraction, with the remaining portion constituted by a UV-stabilizer masterbatch at 5–10 wt% and a slip/antiblock concentrate at 1–2 wt% depending on cover length, roll diameter, and seasonal UV load. The nominal density of 0.920 g/cm³ and melt flow rate of 0.70 g/10 min measured under ISO 1133-1:2022 at 190 °C/2.16 kg place the material in the butene-comonomer LLDPE blown film class with sufficient melt strength for a 45–80 mm grooved-feed extruder running an L/D ratio of 30:1 and a die gap between 1.6 mm and 2.4 mm. The downstream process is monolayer or three-layer blown film extrusion with internal bubble cooling; blow-up ratio is held at 2.2:1–2.8:1, frost line height is maintained at 600–1000 mm above the die exit, and melt temperature is limited to 185–210 °C to avoid oxidative degradation of the anti-fog additive package. Compliance for these films is assigned under EN 13206:2017 for thermoplastic agricultural and horticultural films, with weathering evaluation performed according to ISO 4892-2:2013 xenon-arc methods when the compound contains UV stabilizers. Terminal product types include 120–180 µm low tunnel cladding, 150–200 µm silage stretch covers, and 80–120 µm horticultural side curtains; the AF anti-fog function matters most in enclosed structures where night-time temperature drops create internal condensation on the film surface and reduce light transmission in the 400–700 nm photosynthetically active range.

What Limits Dart Impact When LF 0720/21 AF Is Recompounded with Post-Industrial Recyclate in Thick Construction Liners?

In thick construction liners, the principal process conflict is the trade-off between post-industrial recyclate content and retained dart impact under moderate asphalt or subgrade contact conditions. Braskem LF 0720/21 AF is dosed at 65–80 wt%, high-pressure LDPE at 15–25 wt%, and cleaned post-industrial LLDPE reclaim at 10–20 wt%; carbon black or mineral colour concentrate is added at 2–4 wt% only after the reclaim stream has passed a 2.5 mm screen pack to remove gel bodies larger than 250 µm. The blown film line is configured as a 65–90 mm grooved-feed single-screw extruder with L/D 30:1, die gap 2.0–2.8 mm, blow-up ratio 2.0:1–2.4:1, and internal bubble cooling with an external air ring pressure differential of 15–25 mbar. Frost line is set at 900–1200 mm to stabilize the thick gauge band of 150–300 µm; melt temperature is maintained at 190–210 °C and die pressure is monitored with a 350–450 bar melt transducer to detect screen-pack blockage before gauge variation exceeds ±5%. Mechanical compliance for these liners follows ASTM D4397-16, with dart impact measured under ASTM D1709 Method A, tear resistance under ASTM D1922, and tensile properties under ASTM D882. The terminal products include 200–300 µm temporary construction containment liners, 150 µm sub-slab vapor barriers, and waste enclosure covers. The operational boundary is recyclate content: above 20 wt%, low-temperature puncture resistance becomes inconsistent because the reclaimed resin carries unknown comonomer distributions and antioxidant depletion history; published data for this specific reclaim configuration is limited, so each lot must be screened for melt flow rate and gel count before line introduction.

When Anti-Fog Migration Is the Binding Constraint in Cold-Chain Leaf Greens Packaging

Below 4 °C, condensate control becomes the limiting variable in fresh produce packaging, and LF 0720/21 AF is placed as the food-contact skin layer at 100 wt%, while the core layer is compounded from 70 wt% LF 0720/21 AF and 30 wt% LDPE to maintain bubble symmetry on a three-layer coextrusion line. The die gap is narrow at 1.4–1.8 mm, the blow-up ratio is set to 2.2:1–2.6:1, and the frost line height is clamped at 450–700 mm to control crystal orientation and surface haze, which is measured under ASTM D1003 and targeted below 8% for display clarity. The anti-fog package migrates through the LLDPE matrix to the inner film surface over 24–72 h after extrusion; this migration is retarded by excessive crystallinity and accelerated by film thickness reduction, so film gauge is set at 40–60 µm and melt temperature is capped at 195 °C to prevent additive volatilization. Downstream packaging lines use vertical form-fill-seal equipment with heat seal temperatures between 115 °C and 130 °C and dwell times of 0.3–0.7 s; seal strength is verified under ASTM F88/F88M-21 and must exceed 1.5 N/15 mm for wet-product distribution. Food contact compliance is established through FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011; the overall migration limit of 10 mg/dm² applies to film surfaces and heat-sealed edges. Terminal products include cut salad pillow packs, fresh herb bags, and retail produce pouches in the 30–60 µm range.

At a frost line height of 7–10 die diameters, the frozen food web is blown from a 1.8–2.0 mm die gap at a blow-up ratio of 2.0:1–2.4:1 to produce 50–80 µm film with sufficient low-temperature toughness for IQF distribution. The formulation uses 80 wt% Braskem LF 0720/21 AF and 20 wt% high-pressure LDPE; the LDPE component contributes long-chain branching that raises melt strength and suppresses bubble oscillation on high-output three-layer lines running at 180–220 kg/h. Melt temperature is held between 190 °C and 210 °C, and the frost line is stabilized by an internal bubble cooling pressure of 10–20 mbar plus an external air ring with chilled air at 5–15 °C. Dart impact is measured under ASTM D1709 Method A after conditioning at −18 °C for 24 h; Elmendorf tear is measured in both machine and transverse directions under ASTM D1922, and tensile load at break is measured under ASTM D882. Food contact compliance is established under FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011. The lower service boundary is −25 °C; below that point, impact dimples appear at contact points on sharp-edged frozen product, and an octene-copolymer skin layer or a tougher film grade is required. Terminal products include IQF vegetable pouches, frozen seafood bags, and frozen meat overwrap in the 50–80 µm thickness range.

Lamination Base Webs for Rotogravure Surface Print: Corona Wetting, Solvent Retention, and Seal Integrity

Flexographic and rotogravure lamination webs are compounded from 70–80 wt% LF 0720/21 AF and 20–30 wt% LDPE, with a polymer processing aid at 1.0–2.0 wt% to control melt fracture when the line speed exceeds 120 m/min. The blown film line uses a 1.5–2.0 mm die gap, blow-up ratio 2.0:1–2.5:1, and melt temperature 180–200 °C; corona discharge treatment is applied after the collapsing frame to achieve a surface tension of 40–44 dyn/cm measured under ASTM D2578-23. The treated web is then either in-line flexo-printed or shipped as rollstock for adhesive lamination onto barrier substrates; the polar surface must remain stable for 7–14 days prior to printing, so corona units are run with a 1.5–2.2 kW power draw at 30–50 m/min and the film is re-checked for receding contact angle. Compliance is tied to EU Packaging Directive 94/62/EC Annex II for heavy metal concentration below 100 ppm combined and to REACH Regulation (EC) No 1907/2006 Annex XVII restrictions for phthalates and aromatic amines in printing inks and adhesives. Terminal products include 30–70 µm printed lamination webs, stand-up pouch outer layers, and flow-wrap packaging. The operational boundary is set by corona over-treatment: above 46 dyn/cm, surface oxidation generates low-molecular-weight species that can interfere with polyurethane adhesive crosslinking and reduce delamination bond strength under ASTM D1876 peel testing.

FIBC Inner Liners for Hygroscopic Powders and the Problem of Film-Blocking at 80 µm

FIBC inner liners extruded from Braskem LF 0720/21 AF are run at 95–98 wt% resin with a slip/antiblock masterbatch at 2–5 wt%; the masterbatch is selected to bring the kinetic coefficient of friction measured under ASTM D1894-24 into the 0.20–0.35 range at 23 °C ± 2 °C. The production line is a 50–65 mm single-screw blown film extruder with a 1.8–2.2 mm die gap, blow-up ratio 1.8:1–2.2:1, and melt temperature 185–205 °C; the film is drawn to 80–120 µm and wound with taper tension from 80 N to 40 N across the roll diameter to prevent blocking at the core. The primary failure mode in this application is film-to-film blocking during hot storage or long warehouse residence; the slip/antiblock package mitigates blocking by reducing contact area and by depositing a low-friction surface layer, but overdosing above 5 wt% reduces seal strength and creates visible haze. Compliance is established under FDA 21 CFR 177.1520 for direct food contact when the liner is used for food powders, and under EU Regulation (EC) No 1935/2004 for EU-bound articles. Terminal products include 80–120 µm liner tubes, gusseted liners, and form-fitted inserts for 500–1000 kg flexible intermediate bulk containers. The upper melt temperature is limited to 215 °C; above this point, slip additive decomposition increases plate-out on the air ring and reduces heat-seal strength due to surface contamination.