TotalEnergies Lumicene Supertouch mLLDPE 16ST15 is a metallocene-catalysed linear low-density polyethylene resin supplied as pellets. The product designation corresponds to a nominal density of 0.916 g/cm³ tested according to ISO 1183-1 and a nominal melt flow rate of 1.5 g/10 min at 190 °C under 2.16 kg load tested according to ISO 1133-1:2022. The material is specified for cast stretch film, collation shrink film, and coextruded sealant layers where controlled comonomer distribution, low gel count, and consistent optical clarity are required. It belongs to the Supertouch family produced with single-site catalyst technology, and the base grade is formulated without slip or antiblock additives.

Molecular Architecture and Catalytic Uniformity

The polymer architecture of 16ST15 differs from conventional LLDPE in molecular weight distribution and comonomer placement. The single-site metallocene catalyst reduces the low-molecular-weight, high-comonomer fraction that in Ziegler-Natta resins contributes to extractable species and gel formation during high-shear extrusion. The melt flow rate of 1.5 g/10 min reflects a balance between processability on cast film lines and melt extensibility for high draw ratios. The melt index, however, is not a complete descriptor of processability: at equivalent MFR, a narrow-distribution metallocene resin displays a lower shear-thinning exponent than a conventional LLDPE. This means die pressure and motor load can remain elevated in smooth-bore dies even when the melt index matches. The density of 0.916 g/cm³ is achieved through controlled alpha-olefin comonomer insertion; the resulting solid-state morphology has a higher concentration of tie chains than a Ziegler-Natta LLDPE of equal density, which is the principal reason for increased puncture and dart impact energy. Gel permeation chromatography can characterise the molecular weight distribution; the manufacturer does not publish Mw/Mn values for this grade, but metallocene LLDPE resins in this density class generally exhibit values below 2.5. Differential scanning calorimetry according to ISO 11357-3 is used to determine the melting peak; published data for the exact melting temperature of this specific grade is limited, though metallocene LLDPE of 0.916 g/cm³ typically exhibits a peak between 120 °C and 125 °C.

What Processing Conditions Govern Stable Cast Film Operation?

On production cast film lines, 16ST15 is processed on single-screw extruders with L/D ratios from 30:1 to 33:1 and barrier screws fitted with spiral Maddock or Egan mixing sections. A starting barrel profile for a 75 mm extruder is feed zone 180–200 °C, compression 220–230 °C, metering 240–250 °C, and die 250–260 °C. These temperatures are starting points, not fixed specifications; the optimum depends on throughput, die width, and the desired draw ratio. Die gaps from 0.5 mm to 0.7 mm are standard for cast film thicknesses between 10 µm and 30 µm. Melt temperature should not exceed 270 °C for sustained periods because oxidative degradation generates carbonyl species that reduce optical quality. At the low-temperature boundary, melt temperatures below 235 °C can increase die lip shear stress and initiate sharkskin melt fracture, particularly with narrow die gaps. Chill roll temperatures from 20 °C to 30 °C are applied to stabilise gloss and prevent blocking. The air gap should be kept below 25 mm; at line speeds above 350 m/min, a larger air gap can induce draw resonance because the resin has lower melt strength than high-pressure LDPE. Melt pressure before the screen pack should be monitored against a clean-screen baseline. A pressure increase above 25% from the baseline usually indicates screen pack blinding or gel accumulation. A 60/100/60 mesh screen pack is an effective starting filter, but backpressure rises more rapidly when contaminated pellets or high-gel regrind are introduced.

Edge instability is often the first visible failure mode when the polymer is too cold. The defect appears as periodic edge wavering rather than complete film break. Raising the die zone temperature by 5–10 °C or increasing line speed to raise web tension can stabilise the edge, provided the melt temperature remains below the 270 °C ceiling. If moisture has condensed on pellets, small oval gels and lens-like fish eyes appear in the film. Such material should be dried with desiccant air at 70 °C for 2–4 h before use. Edge trim and off-spec film can be recycled back into the core layer at levels up to 20 wt% if the material is clean and free of surface moisture; higher regrind levels can increase gel count and reduce dart impact measured under ASTM D1709.

Capillary rheometry according to ISO 11443 is used to measure shear viscosity at processing-relevant shear rates. In cast film die flow, apparent shear rates are commonly in the range 100–1000 s⁻¹. At these shear rates, narrow-distribution metallocene LLDPE displays lower shear thinning than conventional LLDPE; therefore, an extruder sized for a Ziegler-Natta grade may require additional torque reserve. Production-scale cast film extruders with a 75 mm barrel and 30:1 L/D have been used to process this grade at throughputs between 250 kg/h and 400 kg/h, but the specific output depends on screw design and die width. If a retrofit from conventional LLDPE is planned, a screw motor with 15–20% unused torque is recommended as a starting margin. Direct comparison of die pressure should be made on the same line and filter condition because differences in adaptor geometry and screen pack loading can confound the effect of molecular structure.

Machine stretch film and hand stretch film constitute the largest use of 16ST15. In cast stretch lines, the resin is processed as a monolayer or as the core layer in a three-layer ABA coextrusion with a cling layer and a release layer. The core layer can represent 70–80 wt% of total film thickness in many structures, but the exact ratio is a film design variable rather than a resin property. Evaluations for this use include puncture resistance under ASTM D5748, dart impact under ASTM D1709, Elmendorf tear under ASTM D1922, tensile strength and elongation under ISO 527-3, and haze under ASTM D1003. Stretch wrapping performance is assessed on rotary or turntable wrappers with pre-stretch ratios commonly set between 200% and 300%; holding force is recorded by load-cell decay after wrapping a pallet. The grade is also used in collation shrink and display packaging, where shrinkage and holding force are measured by thermal shrinkage methods specified in ASTM D2732 and ISO 14616. In coextruded sealant layers, hot-tack strength can be evaluated under ASTM F1921. Published data for a specific film structure is limited; the converter should verify target values on the intended line because cooling rate, draw ratio, and layer distribution affect final mechanical properties.

Because the base resin contains no slip or antiblock, the coefficient of friction is controlled by the cling and release layers. Film-to-film coefficient of friction is measured under ASTM D1894; converters should verify static and kinetic values on wound film because storage time and winding tension affect surface morphology. On-line thickness profiling with a beta gauge or infrared scanner is recommended, with gauge variation maintained below ±5% to avoid localised thinning that reduces puncture performance under ASTM D5748.

When This mLLDPE Grade Replaces Ziegler-Natta LLDPE in High-Stretch Film

When 16ST15 is substituted for a Ziegler-Natta LLDPE with the same nominal density and melt index, the difference appears most clearly in property balance rather than in one isolated value. Dart drop impact measured under ASTM D1709 is generally higher at equal gauge because the uniform comonomer distribution permits more effective stress distribution across the film plane. Machine-direction Elmendorf tear under ASTM D1922 is commonly lower than that of a Ziegler-Natta grade of identical density, while transverse-direction tear is often higher. Optical response, measured as haze under ASTM D1003 and 45° gloss under ASTM D2457, is typically improved because the low-molecular-weight, highly branched fraction that scatters light is reduced. Seal initiation temperature and hot-tack strength under ASTM F1921 are shifted to lower temperatures relative to conventional LLDPE at the same density, which is relevant for sealant layers in coextruded laminates. On the extrusion side, die pressure and motor load can be higher than a Ziegler-Natta LLDPE of identical melt index because the narrower molecular weight distribution gives a lower shear-thinning exponent. A measurable pressure rise is common on smooth-bore cast film dies; the exact magnitude should be validated by line trial. Blending with LDPE is used to increase melt strength and reduce draw resonance, but the addition of LDPE reduces clarity and dart impact in proportion to the added long-chain branching.

Relative to lower-density ethylene-octene plastomers, 16ST15 has a higher tensile modulus and lower surface tack, which is a useful balance for machine film where high holding force is required. Relative to higher-density LLDPE grades, the 0.916 g/cm³ density lowers seal initiation temperature and improves puncture under ASTM D5748, but reduces tensile modulus. The resin is also distinct from LDPE in molecular architecture: absence of long-chain branching limits melt extensibility in high-speed extrusion but reduces heavy-gel formation from high-pressure reactor residue.

For food-contact applications, the finished article must satisfy FDA 21 CFR 177.1520 for olefin polymers and EU Regulation 10/2011 for plastics intended to contact food. Compliance is determined on the final film or laminate, not on the neat resin alone. The resin should be stored in unopened packaging below 40 °C, protected from direct sunlight and standing water. Recommended storage humidity is below 60% RH. If pellets are moved from cold storage into a humid production hall, condensation can introduce moisture-induced gels; pallets should be held in ambient conditions for 24 h before opening or dried with desiccant air at 70 °C for 2–4 h. The base resin is not formulated for prolonged outdoor UV exposure; if outdoor weathering is required, a suitable UV stabilizer masterbatch must be added and verified by accelerated weathering under ISO 4892-2 or ASTM G154.