During five-layer cast stretch film extrusion on a 75 mm barrier screw with 30:1 L/D ratio, Braskem LH118 is introduced into the middle layer at 15–25 wt% of total film weight. The grade is specified with nominal melt flow rate of 1.0 g/10 min at 190 °C/2.16 kg per ISO 1133-1:2022 and density of 0.918 g/cm³ per ASTM D1505-18. In this position, LH118 provides higher melt strength than a 2.0 g/10 min metallocene LLDPE and contributes to control of neck-in when the melt curtain exits a 0.6–0.8 mm die gap. Extruder barrel setpoints from feed throat to melt adapter are commonly held at 180 °C, 210 °C, 230 °C, and 245 °C; the chill roll temperature is fixed between 18 °C and 24 °C to reduce blocking while retaining cling transfer.A common formulation for a 23 µm machine film is 60 wt% metallocene LLDPE at 0.918 g/cm³ and 2.0 g/10 min, 25 wt% LH118, 10 wt% high-pressure LDPE at 0.923 g/cm³ and 0.8 g/10 min, and 5 wt% polyisobutene tackifier masterbatch. Cling is measured as peel force after 24 h conditioning at 23 °C under 50% relative humidity using ASTM D5458-12; films stored below 5 °C commonly exhibit cling force reduction greater than 25% because polyisobutene migration to the surface is retarded at lower temperature. Edge trim from this structure can be reintroduced at up to 15 wt% in the core layer, though trim derived from high-butene LLDPE structures may raise haze above 3.5% measured by ASTM D1003-13.Line speed is the principal processing conflict for cast film using LH118 in the core. At speeds above 600 m/min, transverse-direction thickness variation increases unless edge pinning and vacuum box settings are adjusted. Published data for LH118 at speeds above 800 m/min in this exact five-layer configuration is limited. On lines equipped with 700–1000 mm diameter chill rolls, winder tension is normally set to 12–17 N/m of web width to prevent telescoping and hard roll edges. End products include pre-stretched hand wrap, turntable wrap, and machine film; puncture resistance tested by ASTM D5748-19 and load retention by ASTM D5459-12 should be verified on the finished roll rather than predicted from dart impact data alone.

What Limits LH118 Loadings in Three-Layer Frozen-Food Blown Film?

Three-layer frozen-food lines running sealant skins of Braskem LH118 on a 250 mm die typically set die gap between 1.6 mm and 2.2 mm, blow-up ratio from 2.2 to 2.8, and frost line height of 500–750 mm above the die exit. The sealant layer usually represents 25–35 wt% of total film thickness, with the core and outer skin containing metallocene LLDPE or EVA for low-temperature impact resistance. Melt temperature at the adapter is maintained at 190–215 °C; operation above 230 °C leads to visible gel formation in the sealant layer after 4–6 h of continuous running on production-scale lines.Seal performance is evaluated on vertical form-fill-seal machines with dwell times between 0.2 s and 0.4 s. Heat seal initiation for a 70 µm film containing 30 wt% LH118 in the sealant layer is typically observed between 105 °C and 120 °C; below 105 °C, the failure mode shifts from cohesive peel to interfacial peel, which is unacceptable for frozen-food pouches handled at −25 °C. Hot tack force measured under ASTM F1921-12 at 0.2 s dwell is generally lower than a metallocene LLDPE reference; therefore LH118 is used as a sealant modifier rather than a direct replacement when package fill weights exceed 1 kg.Direct food contact compliance for the finished film must satisfy 21 CFR 177.1520(c)3.1 for olefin polymers. The applicable extractive limits depend on food type and use condition; frozen foods generally fall under use condition E or F. For export to EU markets, the film must also meet the overall migration limit of 10 mg/dm² under EU Regulation 10/2011, with fatty food simulant D2 at 20 °C for 10 days or equivalent test conditions. End products include printed pillow pouches for IQF seafood, vegetables, and marinated meat portions.Rotating wrapper arms on silage bale applicators expose LH118-based films to pre-stretch tensions above 70% elongation, which creates a specific set of retained mechanical requirements not captured by standard cast-film cling tests. A typical three-layer formulation for a 25 µm high-tension wrap uses 65 wt% Braskem LH118, 20 wt% high-pressure LDPE, 10 wt% metallocene LLDPE, and 5 wt% UV/colour masterbatch. The blown film line is run with a 2.5 m die circumference, melt temperature between 190 °C and 215 °C, and blow-up ratio of 2.0–2.4 to balance tear propagation in machine and transverse directions.EN 13206:2017 is the reference specification for bale wrap films in the EU; it sets requirements for retained elongation at break, puncture resistance, and cling after UV exposure. The weathering stabiliser package typically contains hindered amine light stabiliser at 0.15–0.25 wt% active. In production, insufficient HALS concentration is detected by carbonyl index increase at 1715 cm⁻¹ in FTIR after QUV-A weathering according to ISO 4892-3:2016. Films that develop a significant carbonyl index increase after 2000 h exposure tend to develop longitudinal splits on wrapper arms during high pre-stretch application; retained dart impact per ASTM D1709-15a and tear propagation per ASTM D1922-15 should be measured after UV ageing, not only on unexposed film.

Melt Curtain Neck-In and Die Lip Oxidation on Woven PP Lamination Lines

Braskem LH118 is melt-laminated onto woven polypropylene at blend fractions of 20–40 wt% with high-pressure LDPE. Below 20 wt% LH118, the coated PP fabric may show inadequate low-temperature flex resistance, while above 40 wt% the melt curtain becomes difficult to control at coating weights below 18 g/m². Processing is performed on a 90 mm single-screw extruder with compression ratio of 2.5:1, barrel temperatures from 180 °C to 260 °C, and die temperatures between 280 °C and 310 °C. These high die temperatures open the PP fabric surface for mechanical interlocking, but they also accelerate LLDPE degradation during residence times above 3 min; screw cooling is applied to keep the feed zone temperature below 65 °C.Adhesion is assessed by peel testing according to ASTM F88/F88M-15 after lamination. Without tie resin, peel force at the PP-coating interface is frequently below 5 N/15 mm, and failure is interfacial. Maleic anhydride grafted LLDPE at 3–5 wt% raises peel force through covalent bonding to the woven PP. Amine-functional silane coupling agents are avoided in this structure because primary amine residues at die temperatures above 280 °C can promote catalytic degradation and die lip build-up. End products include FIBC inner liners and flat-bottom valve sacks; the FIBC structure is validated under ISO 21898:2004 for safe working load classification.

Application	Reference	Measured property	Operational limitation
Cast stretch film	ASTM D5458-12	Cling force after 24 h at 23 °C	Below 5 °C storage reduces cling force by more than 25%
Frozen-food sealant film	ASTM F1921-12	Hot tack at 0.2 s dwell	Lower than metallocene LLDPE reference
Silage bale wrap	ISO 4892-3:2016	Carbonyl index at 1715 cm⁻¹	Significant increase after 2000 h indicates embrittlement risk
Woven PP lamination	ASTM F88/F88M-15	Peel force at PP interface	Below 5 N/15 mm without tie resin

For heavy-duty shipping sack film on a bottom-seal conversion line, LH118 is used at 25 wt% with 70 wt% blown-film-grade LLDPE and 5 wt% white masterbatch; the film is extruded at 190–210 °C melt temperature and tested for dart impact per ASTM D1709-15a and Elmendorf tear per ASTM D1922-15 before conversion into 40–50 kg sack dimensions.