The resin designated SABIC SUPEER mLLDPE 8118L is a metallocene-catalyzed linear low-density polyethylene supplied in pellet form for blown film extrusion. The grade is defined by a nominal density of 0.918 g/cm³ measured according to ASTM D1505 and a nominal melt flow rate of 1.0 g/10 min at 190 °C/2.16 kg measured according to ASTM D1238. The metallocene catalyst system produces a narrow molecular weight distribution and a more uniform short-chain branching distribution than conventional Ziegler-Natta LLDPE at equivalent density. The product is applied in thin-gauge film structures where puncture, low-temperature toughness, and optical clarity are controlled requirements.

What nominal mechanical and thermal values are published for the grade?

Material property data reported by the manufacturer include a peak melting temperature of 122 °C by ASTM D3418 and a Vicat softening temperature of 105 °C by ASTM D1525. At 25 µm blown film thickness, comparative data are typically generated on a single-layer line having a 50 mm screw, 24:1 length/diameter ratio, 1.6–2.0 mm die gap, and blow-up ratio 2.0:1 to 2.5:1. Representative nominal values include machine-direction tensile strength at break of 50 MPa and transverse-direction tensile strength at break of 44 MPa measured by ISO 527-3. Elongation at break is approximately 600% in the machine direction and 700% in the transverse direction. Dart impact by ASTM D1709A is commonly reported in the range 900–1,200 g at 25 µm. Elmendorf tear by ASTM D1922 is approximately 110 g machine direction and 380 g transverse direction. Haze measured by ASTM D1003 is below 10%, and 60° gloss by ASTM D2457 exceeds 70 GU. These are comparative nominal values, not specification limits; the certificate of analysis for each lot governs commercial acceptance.

Because the metallocene resin lacks long-chain branching, bubble stability during blown film extrusion is lower than that of a low-density polyethylene of similar melt index. On single-layer lines with barrel diameter 55–75 mm and 24:1 to 30:1 length/diameter ratio, start-up barrel temperatures are typically 170–190 °C, adapter and die temperatures 190–210 °C, and melt temperatures 195–215 °C. A die gap of 1.6–2.4 mm, blow-up ratio of 2.0:1 to 2.5:1, and frost-line height of 1–3 die diameters are common baseline settings. If cooling air velocity is too high or frost-line height too low, the bubble can develop breath oscillation and film thickness variation. Published data for this specific configuration is limited; these ranges represent industrial practice for narrow-molecular-weight-distribution mLLDPE rather than manufacturer-guaranteed processing limits.

The narrow molecular weight distribution reduces shear thinning. At equivalent screw speed, the mLLDPE exhibits higher die-wall shear stress than broad-MWD LLDPE, and sharkskin melt fracture can begin at lower apparent shear rates. Fluoroelastomer processing aids at 100–500 ppm are commonly used to suppress surface roughness. When the die gap is below 1.6 mm or melt temperature is below 190 °C, the onset of sharkskin moves to lower output. Data from production-scale blown film lines with 75 mm grooved-feed extruders indicate that melt fracture and surface haze can first appear on the bubble near the frost-line region and may be eliminated by raising die temperature or adding processing aid before reducing screw speed.

Primary application fields and equipment-specific usage limits

In frozen food packaging, the grade is used in seal-web structures at 20–40 µm because the low density and uniform comonomer distribution lower seal initiation temperature and maintain puncture resistance at freezer temperatures. Vertical form-fill-seal machines fitted with impulse sealing jaws commonly use seal temperatures in the range 110–130 °C depending on dwell, pressure, and sealant thickness. In hygiene film applications such as backsheet lamination, the resin is incorporated at 15–30 µm and may be blended with 5–15 wt% LDPE to stabilize the bubble without eliminating the optical advantage. Collation shrink film lines using the grade require higher blow-up ratios and lower output rates than LDPE-rich blends; the resin contributes toughness but not the high shrink force needed for heavy bundled loads unless blended with LDPE or incorporated into coextruded skins.

For food-contact applications, the converter must verify compliance under 21 CFR 177.1520 for olefin polymers and EU Regulation No 10/2011 for plastic materials intended to come into contact with food. The supplier’s food-contact status does not automatically cover the finished structure, because migration behavior is influenced by layer composition, thickness, and converting aids. Non-food film applications such as protective masking and industrial liners use the grade when near-neutral organoleptic transfer is required. Published data for specific masking configurations is limited; adhesion build-up and unwind force depend on the pressure-sensitive adhesive chemistry rather than the backing film alone.

Amine-based antistatic additives may increase haze and plate-out in film converting; the grade should be evaluated with the specific slip and antiblock package under production conditions. Pre-drying is not normally required when bags are sealed and stored below 30 °C; however, condensation from temperature cycling at relative humidity above 60% can introduce surface moisture and cause pinholes at thicknesses below 30 µm. The resin is not designed for rotational molding or pipe extrusion; the narrow molecular weight distribution and low die swell make it unsuitable for large-part blow molding.

When SUPEER 8118L is substituted for a conventional C4-LLDPE in high-clarity blown film

Substitution of a Ziegler-Natta C4-LLDPE with SUPEER 8118L changes the processing and property balance in measurable ways. The metallocene grade typically gives lower haze at equivalent density and thickness because the narrow comonomer distribution reduces large crystalline aggregates. Falling-dart impact and low-temperature puncture are generally higher at the same thickness. Melt strength is lower, and the shear-thinning response is less pronounced; die pressure and motor load may not decrease as much with increasing screw speed. Extruder setups originally optimized for C4-LLDPE often require a wider die gap or a processing aid to maintain the same output without sharkskin.

Compared with tubular LDPE of the same melt index, the 8118L grade has higher tensile elongation and higher Elmendorf tear resistance but lower melt strength and less bubble stability. In coextruded structures, it is therefore placed in core or seal layers while LDPE skins support the bubble. Compared with high-density metallocene grades, the 0.918 g/cm³ density gives lower stiffness and lower heat deflection but greater impact resistance at low temperatures. The narrow molecular weight distribution can reduce extractable low-molecular-weight species; this property is relevant for food packaging where organoleptic neutrality is specified, but final extractables must be measured on the finished film according to FDA or EU protocols.

Capillary rheometry of metallocene LLDPE with melt flow rate 1.0 g/10 min typically shows apparent viscosity at 210 °C and shear rate 100 s⁻¹ in the range 800–1,200 Pa·s. For shear rates above 1,000 s⁻¹, the apparent viscosity falls toward 100–200 Pa·s. The power-law index is higher than for broad-MWD LLDPE because of reduced shear thinning. This means that output gains obtained by increasing screw speed are partly offset by higher die pressure and higher melt temperature. Extrusion engineers therefore operate the grade within a narrower screw-speed window or use a wider die gap to keep melt temperature below 230 °C, above which oxidative degradation and gel formation can increase.

Batch-to-batch variation in metallocene film resins is usually tighter than in Ziegler-Natta grades because the single-site catalyst reduces differences in comonomer distribution. In practice, converters monitor melt flow rate and density on incoming lots and record die pressure at constant screw speed as an indirect check on routing. A shift in die pressure greater than 5–10% at constant conditions can indicate a change in molecular weight or the presence of contamination. Film haze and dart impact are also sensitive to re-extrusion of edge trim; trim levels above 15% can reduce dart impact if trim is degraded or contaminated with dust.

The resin is supplied as free-flowing pellets with bulk density approximately 0.54 g/cm³ and is packaged in 25 kg moisture-proof bags or bulk containers. Incoming lots should be inspected for melt flow rate and density before silo blending. The comonomer identity is not always disclosed in public grade summaries, but the metallocene catalyst architecture and density place the material in the class of low-density mLLDPE film resins with narrow composition distribution. Users comparing alternative metallocene grades should request comonomer type and additive package from the supplier if sealing, organoleptic, or extractables performance is critical.