SABIC SUPEER mLLDPE 7358TA is a metallocene-catalysed ethylene-alpha-olefin copolymer supplied as free-flowing pellets for thin-gauge blown and cast film. The numerical designation 7358TA carries grade-specific melt flow, density, and additive-package information that must be verified against the SABIC Technical Data Sheet and certificate of analysis before commercial use. Public technical documentation identifies a nominal melt index of 1.0 g/10 min under ASTM D1238 at 190 °C with 2.16 kg and a nominal density of 0.918 g/cm³ under ASTM D1505. These two values place the resin within the linear-low-density polyethylene class. The metallocene catalyst system, however, produces a narrower molecular weight distribution and a more uniform short-chain branching distribution than conventional Ziegler-Natta linear-low-density polyethylene of the same melt index and density.

For specification control, the primary release parameters are melt index and density. Melt index is determined under ASTM D1238 or ISO 1133-1:2022 at 190 °C and 2.16 kg. Density is measured after conditioning under ASTM D1505 or ISO 1183-1. Molecular weight distribution, long-chain branch content, and comonomer distribution are not routinely reported on the certificate of analysis; these data may be available from SABIC technical service under non-disclosure agreement. The suffix “TA” identifies a specific film additive formulation within the SUPEER 7358 series. It should not be assumed that 7358TA and other suffix variants are interchangeable. Slip agent level, antiblock type, and processing aid presence change coefficient of friction, blocking force, haze, and printability. Public SABIC documentation describes 7358TA as a film-grade resin, but the exact additive composition is proprietary.

What Distinguishes the Catalyst Architecture from Conventional LLDPE?

The primary structural difference is the distribution of short-chain branches. In Ziegler-Natta LLDPE, higher molecular weight chains typically contain fewer comonomer units, while lower molecular weight chains contain more comonomer. This non-uniformity creates a broad melting range, lower clarity, and a higher mass fraction of extractable low molar mass chains. Metallocene catalysis distributes comonomer more uniformly across chain lengths. At equivalent density, the consequence is lower haze, higher dart impact toughness, and more consistent seal initiation. However, the narrower molecular weight distribution also reduces melt elasticity. 7358TA generates less die swell and exhibits less shear thinning than a fractional-melt-index Ziegler-Natta resin. This difference must be considered during die selection, bubble stabilisation, and output-rate optimisation.

Because comonomer insertion is more controlled, 7358TA generally shows lower gel counts and a more stable extruder pressure profile over extended runs. The metallocene catalyst also reduces low molecular weight tail fractions that can contribute to organoleptic issues in food packaging. Film produced from 7358TA is therefore less likely to impart taste or odour to packaged goods than films based on conventional C₄ or C₆ Ziegler-Natta LLDPE. The improvement is measurable through sensory panel evaluation according to DIN 10955 or equivalent internal protocols; however, sensory performance depends heavily on additive package, printing inks, and storage conditions.

When 7358TA is processed on a single-screw blown film extruder with an L/D between 24:1 and 30:1, the low shear sensitivity of the metallocene resin shifts the energy balance toward conductive heating from the barrel rather than dissipative mixing in the screw. A barrier screw with a Maddock mixing section and a compression ratio between 2.8:1 and 3.5:1 is generally used to avoid partially unmelted pellets reaching the screen pack. Extruder specific energy consumption is reported higher than for LDPE but lower than for comparable Ziegler-Natta LLDPE of the same melt index. Field observations vary with screw wear, die build-up, and cooling-air temperature.

Die melt temperature should be maintained between 190 °C and 230 °C, with the lower end selected only when film appearance is acceptable and the higher end reserved for reduced melt fracture or blends containing high-density polyethylene. At die temperatures below 175 °C, pressure drop across the screen pack may increase sharply, and surface defects described as sharkskin can appear because the metallocene polymer has low extensional viscosity at the die exit. A die gap of 1.8 mm to 2.5 mm is commonly used in blown film. A narrower die gap raises shear rate and may increase melt temperature above the set point. Bubble geometry is normally held at a blow-up ratio of 2.0:1 to 3.0:1 and a frost-line height of 1.5–2.5 times the die diameter. For dies above 150 mm, internal bubble cooling is generally required to prevent bubble flapping and gauge-band defects. Published data for 7358TA in extrusion coating trials is limited; the operating window above is based on the 0.918 density mLLDPE class and should be confirmed by line trials against the SABIC processing guide.

Batch-to-batch variation in metallocene film resins is generally lower than in Ziegler-Natta grades because the catalyst produces a narrower molecular weight distribution. Film producers should still monitor head pressure and die pressure at constant throughput. A pressure deviation greater than 5–8 % from the qualified lot, without a change in melt temperature or screen pack, indicates a formulation or feed-material change and warrants quarantine before further conversion.

Optical, Seal, and Mechanical Property Comparisons

In thin-film property comparisons, differences between 7358TA and conventional LDPE or Ziegler-Natta C₄/C₆ LLDPE can be quantified using standard test methods. Haze is measured under ASTM D1003; gloss under ASTM D2457 at 45°; dart impact under ASTM D1709A; Elmendorf tear under ASTM D1922; and film tensile under ASTM D882. Metallocene LLDPE films based on a nominal 0.918 g/cm³ density typically exhibit improved dart impact and lower haze than Ziegler-Natta LLDPE films of the same melt index and gauge. The magnitude of improvement is gauge-dependent. At 25 µm, dart impact may increase by 30–60 % relative to a conventional butene LLDPE. At 50 µm, the percentage shift is often smaller because total puncture resistance is increasingly controlled by film thickness rather than catalyst architecture.

Representative public data for metallocene LLDPE of 0.918 density and 1.0 MI typically show dart impact of 1,000–1,400 g at 25 µm, haze below 10 %, and gloss above 75 at 45°. However, published data for the exact 7358TA formulation is limited. The SABIC Technical Data Sheet and certificate of analysis should be used for specification purposes. Film properties are influenced by die gap, drawdown ratio, cooling rate, additive package, and sample gauge. Haze under ASTM D1003 is thickness-sensitive, so 7358TA should be compared only at equal gauge and preferably equal frost-line conditions.

Seal response is another differentiator. The homogeneous comonomer distribution lowers hot-tack and seal initiation temperature relative to Ziegler-Natta grades. Packaging converters can therefore reduce heat-seal jaw temperature or increase line speed on form-fill-seal equipment without sacrificing seal integrity. Hot-tack strength is measured according to ASTM D1921 or instrument-specific methods. Seal initiation temperature is usually defined as the point where seal strength reaches 4 N/25 mm under a given dwell and pressure. For a 0.918-g/cm³ metallocene LLDPE of 1.0 g/10 min MI, seal initiation typically falls below 100 °C. The exact value for 7358TA must be taken from SABIC laboratory data because additive package and film gauge change heat transfer. Published data for this specific configuration is limited unless the converter runs a matrix of dwell times from 0.2 s to 1.0 s and sealing pressures from 0.3 MPa to 0.6 MPa.

When 7358TA Is Combined with Blending Partners in Film Structures

Blending 7358TA with LDPE is common for bubble stability and tear balance. Addition of 10–20 wt% LDPE increases melt strength and reduces bubble flapping, but haze may rise and gloss may fall. Conversely, replacing LDPE with 7358TA in a sealant layer can reduce seal initiation temperature but may increase coefficient of friction if the film is corona-treated and stored under high humidity. 7358TA should not be combined with high levels of low-molecular-weight tackifier or amine-based antistatic additives without validation. Amine-based additives may migrate to the film surface and compete with the slip agent in the “TA” package; this can increase blocking force in warm storage.

In a three-layer coextrusion structure, 7358TA may be specified in the core or skin layer to improve toughness and optics, while an LDPE or HDPE skin may be retained for machinability and thermal resistance. The maximum recommended working concentration is governed by the final coefficient of friction and blocking force, not by the catalyst system. The resin is not a drop-in replacement for high-pressure LDPE in applications requiring high melt strength, such as broad-bubble blown film with high frost-line height or heavy-shrink collation film.

Food-contact status for 7358TA is based on compliance with U.S. FDA 21 CFR 177.1520(c) for olefin polymers in contact with food and with European Commission Regulation (EU) No 10/2011 as amended. Overall migration testing according to EN 1186 may be required for final articles, and specific migration of the additive package should be evaluated under EN 13130 or equivalent. The grade is not supplied with a blanket “FDA approved” statement. Converters are responsible for verifying that the final article meets all applicable food-contact conditions, including food type and temperature.

Handling conditions for 7358TA follow general storage rules for polyolefin pellets. Sacks should be stored at 5–40 °C, away from direct sunlight and sources of ozone or combustion gases. No pre-drying is normally required. At relative humidity above 60 %, however, condensation on cold pellets can occur when ambient air temperature rises quickly. In such conditions, a 2–4 h hopper dryer at 50–60 °C or a dried-air conveying system prevents surface moisture from generating film fish-eye defects. The resin should not be exposed to flame, cutting sparks, or welding sparks during conveying because fine polyethylene dust is combustible at airborne concentrations below the lower explosive limit.

After extrusion, rolls should be aged for a minimum of 48 h at 20–25 °C before coefficient-of-friction testing. Otherwise the measured dynamic slip can be artificially high because the slip agent has not fully migrated to the film surface. This aging protocol is particularly relevant on high-speed form-fill-seal lines, where immediate testing of freshly slit reels may produce false rejection of acceptable film.