Designated as a butene-based linear low-density polyethylene film resin, SABIC LLDPE 122NJ is characterised by a nominal melt flow rate of 2.0 g/10 min measured at 190 °C under a 2.16 kg load in accordance with ASTM D1238 or ISO 1133-1:2022, and a nominal density of 0.918 g/cm³ at 23 °C in accordance with ASTM D1505 or ISO 1183-1:2019. The grade is positioned for blown-film and cast-film converting where this melt-viscosity and density balance permits thin-gauge drawing at sustained line speeds. Producer documentation describes an additive package based on slip and anti-block agents, which alters film surface coefficient of friction and film-to-film separation in wound rolls. This additive package distinguishes 122NJ from neat LLDPE grades requiring separate let-down of slip or anti-block concentrates at the hopper. Applications most commonly associated with SABIC LLDPE 122NJ in trade literature include general-purpose film, refuse sacks, liners, carrier bags, and protective packaging for secondary distribution.

What melt rheology and density parameters define this grade?

The 2.0 g/10 min melt flow rate indicates that the resin exhibits lower apparent melt viscosity at typical extrusion shear rates than a 1.0 g/10 min grade of equivalent density. The density of 0.918 g/cm³ places 122NJ in the mid-density LLDPE range; short-chain branching derived from butene comonomer reduces crystalline order relative to high-density polyethylene while retaining a higher crystalline melting range than very-low-density ethylene copolymers. The melt index-density pairing produces a viscosity profile suitable for medium-to-high throughput film extrusion, but exact tensile values are thickness- and orientation-dependent. Film properties must be measured on the final article under ASTM D882 or ISO 527-3 rather than inferred from resin pellet data alone. Melt flow rate and density reported on the producer’s certificate of analysis should be checked for lot-to-lot drift; if melt flow rate moves outside the producer-specified tolerance, extruder backpressure, throughput, and gauge uniformity will shift.

The melt rheology of a 2.0 g/10 min LLDPE is typically described in capillary rheometry by a viscosity at 100 s⁻¹ and 190 °C in the range of 700 Pa·s to 900 Pa·s for similar butene copolymers; direct data for 122NJ should be obtained from the producer’s rheology database because molecular weight distribution and additive slip shift the curve. The power-law index in the shear-rate range from 100 s⁻¹ to 1000 s⁻¹ commonly falls between 0.45 and 0.55 for this class. A lower power-law index corresponds to stronger shear thinning and greater pressure reduction at high screw speed. In extrusion, the screw speed required to reach a constant die pressure with 122NJ may be 10 % to 25 % higher than for an MFR 1.0 grade, depending on barrel geometry and die restriction.

When slip and anti-block additives are present, their effects are not instantaneous after extrusion. Slip agents migrate to the film surface at a rate governed by solubility, diffusion, and storage temperature. At 23 °C, ≥ 48 hours may be needed to approach equilibrium coefficient of friction; at 40 °C, migration accelerates. Quality release plans for 122NJ should therefore specify a conditioning interval before measuring coefficient of friction under ASTM D1894. Anti-block particles create microscopic surface roughness that reduces blocking at the expense of some optical haze. Haze measured under ASTM D1003 and gloss measured under ASTM D2457 therefore reflect both base-resin crystallinity and anti-block concentration, and they are also sensitive to melt temperature and frost-line position.

Extruder pressure, output, and bubble-stability interactions in blown-film conversion

Blown-film extrusion of SABIC LLDPE 122NJ on a single-screw extruder with L/D ratio between 24:1 and 30:1 typically uses a barrel-temperature profile rising from 180 °C in the feed zone to 220 °C at the die head; die temperatures between 210 °C and 230 °C reduce melt fracture at high screw speed. Die gap is normally set between 1.0 mm and 1.5 mm, with blow-up ratios from 2.0:1 to 3.0:1. At the low end of the temperature window, the 0.918 g/cm³ density supports a relatively stiff bubble, but the 2.0 g/10 min melt may exhibit lower melt strength than a 1.0 g/10 min butene grade. Frost-line height and internal bubble cooling must therefore be stabilised when the line is operated above 70 % of maximum screw speed.

On a grooved-feed extruder optimised for high-density polyethylene, the barrel profile must be flattened to prevent overfeeding and excessive melt pressure. The lower crystalline melting point of LLDPE produces earlier plastication and a shorter compression zone than HDPE. If melt temperature is allowed to exceed 260 °C for extended periods, thermal degradation of the antioxidant system and slip additive can generate yellowing, odour, and gel particles. Die-lip deposit formation is another boundary: accumulated low-molecular-weight fractions and degraded additives can produce edge tear and bubble instability. Die cleaning frequency may increase when processing 122NJ at high melt temperatures or with heavily pigmented masterbatches.

Cast-film extrusion of SABIC LLDPE 122NJ uses an extrusion temperature from 200 °C to 250 °C and chill-roll temperatures of 15 °C to 30 °C. The 0.918 g/cm³ density generates a crystalline setting rate that can create visible shear-induced surface haze if the chill-roll is too warm or the air gap is too long. Vacuum box and air-knife settings must be adjusted to maintain contact with the chill roll. The 2.0 g/10 min melt flow supports penetration into embossing patterns and high-speed winding, but the broader molecular weight distribution of a conventional butene LLDPE may limit downgauging below approximately 12 µm when compared with a metallocene grade of similar density.

When 122NJ replaces a lower-melt-index butene grade in high-output lines

Substitution of SABIC LLDPE 122NJ for an MFR 1.0 grade of equivalent density reduces extruder head pressure at constant screw speed, permitting either higher screw speed or lower melt temperature. The trade-off is bubble stability: the lower extensional viscosity of the 2.0 g/10 min melt more readily initiates bubble deformation under cross-air disturbances, especially at blow-up ratios above 3.0:1. In applications where dart impact and tear resistance are critical, the lower molecular weight associated with higher melt flow generally reduces energy absorption; ASTM D1709 and ASTM D1922 values for 122NJ will generally fall below those of a 1.0 g/10 min grade at equivalent thickness and draw conditions. Conversely, the higher melt flow improves flow through narrow die lips and can reduce melt-temperature sensitivity in thin-gauge cast film.

Relative to a hexene-based LLDPE of the same 0.918 g/cm³ density, SABIC LLDPE 122NJ may exhibit lower dart impact retention, lower Elmendorf tear, and somewhat higher haze at comparable film gauge and blow-up ratio. The difference arises because butene branches are shorter than hexene branches, generating fewer tie-chain entanglements capable of bearing high-speed impact loads. Processors compensate by increasing film gauge or blending with hexene LLDPE; blend ratios are generally adjusted in 10 wt% increments until the target ASTM D1709 dart value is achieved. Published data for this specific blended configuration is limited, and final blend performance must be verified on the production line.

Pre-drying is not normally required for unopened pellets stored at relative humidity below 60 %. Above that threshold, surface moisture can increase die-lip deposits and create bubble instability; the resin should be dried at 50 °C to 70 °C for at least 2 hours if condensation has occurred. Processing temperature should not remain above 260 °C for extended periods, because thermal degradation of the slip additive and antioxidant system can generate yellowing, odour, and gel particles. Some amine-based antifog additives may interfere with surface migration of the slip package; compatibility should be verified through a 24-hour let-down trial before production.

Food-contact use of polyethylene grades is regulated under FDA 21 CFR 177.1520 for olefin polymers and under Regulation (EU) No 10/2011. SABIC LLDPE 122NJ is typically represented by the producer as suitable for food-contact applications subject to the limitations of those regulations; however, the final manufactured article and its additive package must be assessed for specific migration limits. The grade is a polymer within the scope of REACH; a current safety data sheet should be consulted for residual monomer or processing-aid reporting thresholds. For industrial packaging, RoHS hazardous substance restrictions generally do not apply to polyolefin substrates unless conductive fillers or flame-retardant masterbatches are added.

Typical converting applications for SABIC LLDPE 122NJ are general-purpose merchandise bags, industrial liners, garment bags, and protective sheet where the film is run at thicknesses from 15 µm to 100 µm. On a blown-film line, the resin is often blended with 10 wt% to 20 wt% low-density polyethylene to improve bubble stability and optical quality; on cast-film lines, the 2.0 g/10 min melt index supports high-speed winding and contact with chilled-roll embossing. Final articles must be tested under end-use conditions; resin-level properties do not replace film-level ASTM D882 tensile, ASTM D1922 tear, or ASTM D1709 impact tests.