ASRENE LLDPE UF1820T, supplied by Lotte Chemical Titan, is a pelletised linear low density polyethylene extrusion grade with density specification windows of 0.916–0.920 g/cm³ under ASTM D1505 and melt flow index specification windows of 1.8–2.2 g/10 min under ASTM D1238 at 190 °C/2.16 kg. The nominal values reported are 0.918 g/cm³ and 2.0 g/10 min. The grade is positioned for monolayer cast film, lamination film, produce bags, carrier bags, and coextruded packaging where toughness, seal initiation, and optical clarity are specified. The molecular architecture differs from high-pressure LDPE through reduced long-chain branching; this raises tensile elongation at break and dart impact at equivalent film thickness but lowers melt tension. Compared with high-pressure LDPE, the product requires lower extruder back pressure because of its narrower molecular weight distribution, but the cast-film die gap must be reduced by 20–30% to maintain web width. Published data from Lotte Chemical Titan does not disclose the precise comonomer type or catalyst system; published data for this specific configuration is limited, and conversion houses must verify the grade on production equipment because cast-film properties shift with die gap, chill-roll temperature, and line speed. Pellets are supplied in 25 kg bags and in bulk containers; typical bulk density is 0.56 g/cm³.

What film-property values are obtained after conversion to 40 µm cast film?

Typical values published for 40 µm cast film are generated on a 65 mm single-screw extruder with a barrier screw, 28:1 L/D, a 300 mm slot die with 0.5 mm die gap, and a chill-roll temperature of 30 °C. These values are not specification limits; they are lot-to-lot envelopes. The principal film properties are listed in the following table.

The film-property balance is sensitive to chill-roll temperature and line speed. Raising the chill-roll temperature from 30 °C to 45 °C increases haze from 5% to 8% under ASTM D1003 because slower quenching reduces surface nucleation. Increasing haul-off speed from 100 m/min to 150 m/min typically raises machine-direction elongation from 700% to 850% but lowers dart impact by 10–20% under ASTM D1709/A. Melt temperature above 255 °C is not recommended; oxidative chain extension can form gel defects above 200 µm at counts exceeding 10 particles/m² on 100 µm cast film, measured optically.

Film thickness has a non-linear effect on tear. At 20 µm, transverse Elmendorf tear under ASTM D1922 is generally 6–7 g/µm, whereas at 40 µm the normalised value declines to approximately 8.8 g/µm because of constrained tear geometry in the test fixture. Below 20 µm, pinhole defects under a 50 g dart with 25.4 mm diameter become the limiting failure mode. Converters downgauging to 12 µm should validate seal integrity by dye-penetration testing rather than relying on tensile data alone.

On a production cast-film line equipped with a 75 mm single-screw extruder, 30:1 L/D barrier screw with spiral Maddock mixing, a 1.4 m die, and 0.6 mm die gap, the barrel set points from feed throat to die are typically 190 °C, 210 °C, 220 °C, 230 °C, and 240 °C. The die adapter and die-body zones are held at 240 °C; the measured melt temperature at the discharge flange is kept between 220 °C and 250 °C. Specific energy input under these conditions ranges from 0.22 kWh/kg to 0.26 kWh/kg. At a feed-zone set-point of 185 °C and screw speed of 95 rpm, screw torque oscillation increases to ±7%, and melt-pressure variation at the screen pack rises above ±0.8 MPa. If the die gap is opened to 0.8 mm, edge neck-in exceeds 30 mm per side; at 0.5 mm gap and 120 m/min line speed, web width on a 1.4 m die is maintained at 1.35 m with electrostatic pinning at the chill roll. Melt pressure at the breaker plate with a 100/200/100 mesh screen pack is 18–22 MPa at 120 rpm. Screen life is typically 8 h when the feedstock is free from recycled content; gels from thermally degraded prior material reduce screen life to 4 h and appear as >200 µm specks in the film.

Blown-film trials on a 250 mm die with a dual-lip air ring and internal bubble cooling show that UF1820T is limited to a blow-up ratio of 2.2:1 and a frost-line height below 6 die diameters. Exceeding a 2.5:1 blow-up ratio at 80 µm produces bubble flutter and film-gauge variation greater than ±10%, measured with a capacitance gauge. The product is therefore specified primarily for cast-film and lamination processes rather than high-stalk blown-film lines. If blown-film conversion is required, a 10–15 wt% addition of high-pressure LDPE restores bubble stability at the expense of a 2–3% increase in haze per 10 wt% LDPE addition.

When UF1820T replaces a high-pressure LDPE or a C4-LLDPE in lamination film

Replacement of high-pressure LDPE in a 20 µm lamination layer changes the failure mode under ASTM D1922 from a low-extension propagating tear to a higher-energy ductile tear. Transverse-direction Elmendorf tear increases from approximately 6 g/µm to 11 g/µm, but melt tension falls by more than 30%, increasing neck-in unless the die gap is reduced from 0.7 mm to 0.5 mm. Against a C4-butene LLDPE of equivalent density and melt index, UF1820T shows a lower seal-initiation temperature under ASTM F88 at 0.5 s dwell and 0.3 MPa bar pressure; the difference is commonly 5–10 °C. Hot tack narrows above 130 °C, and the grade is not recommended as the sole sealant layer in vertical form-fill-seal machines running above 60 packs/min without a lower-viscosity skin layer. In three-layer cast-film structures, UF1820T is commonly used as the core layer at 60–80 wt% with outer skins of LDPE or EVA. When a 30 µm film is run with a 10% EVA skin, seal initiation under ASTM F88 is controlled by the skin; the UF1820T core contributes mechanical toughness and does not reduce clarity if the skin-to-core ratio is below 4:1.

Slip and anti-block masterbatches are pre-blended at 2–4 wt% through a gravimetric dosing hopper. At 4 wt% silica-based anti-block masterbatch, haze under ASTM D1003 increases from 5% to 8%, and dart impact under ASTM D1709/A falls from 120 g to 95 g. Amide slip additives above 1 wt% lower the coefficient of friction below 0.2 under ASTM D1894 but produce surface bloom; this bloom interferes with corona treatment, and treatment dose must be raised from 2.0 kW to 3.0 kW on a 1 m-wide treater at 100 m/min to maintain a surface energy of 38 mN/m under ASTM D2578.

Regulatory, storage, and additive-compatibility limitations

Lot certificates for ASRENE LLDPE UF1820T normally confirm conformance with EU 10/2011 and FDA 21 CFR 177.1520 for olefin polymers, subject to the specified food-contact conditions of use. The grade does not require pre-drying under ambient storage below 35 °C and relative humidity below 60%; if bags are exposed to condensation, hopper drying at 60 °C for 2 h removes surface moisture. The product should not be combined with nitrogen-containing primary amine process aids, which can cause surface bloom and corona-treatment instability under high-humidity storage. Continuous service temperature is limited to 70 °C for packaging applications unless oxidative-induction-time testing under ASTM D3895 demonstrates otherwise. The resin should also be protected from ultraviolet exposure during long-term outdoor storage because polyethylene will yellow and lose impact strength; published data for outdoor weathering of this specific grade is limited, so accelerated testing under ASTM G154 is required before UV-stabilised packaging applications.

Warehouse storage life is stated by the supplier as 3 years at ambient temperatures below 35 °C in unopened, UV-protected bags. Pallets should be stacked no more than 3 high to prevent particle crushing in bottom bags; crushed pellets can increase fines above 0.1 wt% and cause feed throat flow irregularities. A lot-to-lot density variation of ±0.002 g/cm³ can shift seal initiation temperature by 2–3 °C; therefore, converters running critical seal-peel specifications should verify each delivered lot under ASTM F88.