SABIC LLDPE 6135NE is a linear low-density polyethylene resin based on an ethylene/butene-1 copolymer and supplied in pellet form. The grade is a non-slip, non-antiblock extrusion material; the suffix NE in SABIC product nomenclature generally denotes a natural-grade resin that is not pre-formulated with surface-modifying additives, although thermal stabilisation is present. Two specification values are commonly referenced for material selection: density of 0.918 g/cm³ determined according to ISO 1183-1:2019, and melt mass-flow rate of 0.9 g/10 min measured at 190 °C under 2.16 kg load according to ISO 1133-1:2022. The low melt flow rate, relative to commodity film grades at 1.0 g/10 min, indicates a higher average molecular weight and contributes to greater melt strength and bubble stability in blown-film processing. The intended application field is blown-film extrusion for heavy-duty sacks, carrier bags, freezer films, laminated substrates, and other flexible packaging structures in which puncture resistance and additive flexibility are required.

Because the base resin contains no slip or antiblock package, it is not an all-in-one packaging film grade. The clean additive slate is advantageous where converters require control over coefficient of friction, blocking, seal performance, or organoleptic properties. In practice, slip masterbatch is dosed at 0.5–2.0 wt% and antiblock masterbatch at 0.5–3.0 wt%, depending on film gauge, line speed, and packaging equipment. The absence of pre-existing migratory slip agents avoids interference with high-integrity seal layers and permits tailored frictional performance for vertical form-fill-seal, horizontal form-fill-seal, or laundry bag applications. The trade-off is that neat film from SABIC LLDPE 6135NE has a higher coefficient of friction than pre-formulated grades and is generally unsuitable for automated packaging lines without surface modification. The coefficient of friction is process-dependent and should be characterised by ISO 8295 after additive dispersion and film ageing.

Specification envelope and standardised test data

The nominal specification envelope is defined primarily by density and melt flow rate. Density at 0.918 g/cm³ places the material in the LLDPE range used for flexible but tough film structures, while the melt flow rate of 0.9 g/10 min supports higher melt strength than grades with melt flow rates near 1.0 g/10 min. The table below lists the basic product definition parameters.

The single-point melt flow rate does not fully define the molecular weight distribution. In blown-film LLDPE, the practical difference between 0.9 g/10 min and 1.0 g/10 min is moderate, but it appears as higher extruder backpressure, improved bubble stability, and slightly reduced drawdown speed. The density set point of 0.918 g/cm³ also controls the balance between stiffness and low-temperature flexibility. Because the comonomer is butene-1, the short-chain branches are shorter than those produced by hexene-1 or octene-1 copolymers at equal density. This has a direct consequence for film toughness: tie-chain formation is less efficient than in hexene-based LLDPE of similar density and melt flow rate. Therefore, SABIC LLDPE 6135NE is positioned as a high-molecular-weight butene LLDPE with good process stability and moderate impact performance, rather than as a maximum-toughness film material.

During blown-film extrusion, the resin is processed at die melt temperatures between 190 °C and 220 °C on lines with 30:1 to 40:1 length-to-diameter screws. Because LLDPE has a narrow molecular weight distribution and higher shear viscosity than LDPE, die gaps are usually set at 2.0–2.5 mm to reduce melt fracture risk. Blow-up ratios from 2.0:1 to 3.0:1 and frost-line heights of 2–4 die diameters are applied to stabilise the bubble. Film thicknesses from 20 µm to 120 µm are common for this resin class, depending on cooling capacity, die diameter, and haul-off speed. Published product-specific processing data for every configuration is limited; the stated window is derived from standard industrial practice for 0.918 g/cm³ butene LLDPE. Pre-drying is not normally required because polyethylene is not hygroscopic. Storage at relative humidity above 60% does not introduce bulk moisture, but surface condensation should be avoided if the pellets are exposed to temperature cycling.

What limits the use of a non-slip butene LLDPE in high-speed packaging lines?

The main limitation is frictional behaviour on packaging machinery. On vertical form-fill-seal equipment, film-to-metal friction coefficients above approximately 0.5 can cause product drag, film wander, and misregistration. Neat SABIC LLDPE 6135NE is therefore modified at the converter with slip and antiblock concentrates. Slip masterbatch based on erucamide or oleamide is added at 0.5–2.0 wt%; synthetic silica or talc antiblock concentrates are added at 0.5–3.0 wt%. Dispersion of the masterbatch is critical because uneven slip distribution produces visible bands, seal variation, and inconsistent packaging machine performance. The material itself does not contain preloaded migratory slip agents, so the slip performance is not limited by a fixed formulation. This is a deliberate difference from grades supplied as ready-to-run film resins with fixed slip and antiblock levels.

Sealing behaviour is another boundary condition. Butene-based LLDPE generally has lower hot-tack strength than hexene-based LLDPE or metallocene LLDPE at comparable density. SABIC LLDPE 6135NE can be used in sealant layers, but it is not optimised for extremely short seal dwell times or very high sealing jaw temperatures. Package qualification should include seal strength by ASTM F88 and hot-tack by ASTM F1921. Published product-specific hot-tack data for this grade is limited; converters should evaluate the grade against the specific packaging line because sealing performance depends on polymer structure, additive migration, film gauge, and jaw configuration. The lack of pre-added slip can be beneficial in avoiding excessive migration into seal areas, but it places the burden of additive control on the converter.

When substituting 6135NE into hexene-rich or metallocene film structures

The grade differs from other SABIC LLDPE blown-film resins primarily in comonomer type, melt flow rate, and additive package. The table below shows the usual differentiation against two SABIC LLDPE grades with similar density.

Compared with SABIC LLDPE 6118NE, the lower melt flow rate of 6135NE gives higher melt viscosity and improved bubble stability, but also increases extruder backpressure at constant screw speed. The high-shear viscosity difference is smaller than the low-shear difference because of shear-thinning behaviour. Against SABIC LLDPE 6218NE, the controlling variable is comonomer type. Hexene-based LLDPE generally develops higher dart drop impact and Elmendorf tear at equivalent gauge because the longer short-chain branches increase tie-chain concentration. The lower melt flow rate of 6135NE does not fully compensate for the comonomer disadvantage in highly demanding puncture applications. In coextruded structures, 6135NE is frequently placed in the core layer for stiffness and melt strength, while hexene-rich or metallocene skins provide sealing, optics, or toughness. In monolayer film, blending 6135NE with 15–30 wt% hexene LLDPE is a common method to raise dart impact without sacrificing stiffness; the exact blend ratio depends on film gauge, blow-up ratio, frost-line height, and end-use requirements.

Compared with metallocene LLDPE, SABIC LLDPE 6135NE is a Ziegler-Natta butene grade and therefore has a different balance of optics, toughness, and processability. Metallocene grades often provide higher clarity and higher dart impact at equal density, but may exhibit narrower processing windows and different shear-rate response. The melt strength of 6135NE is adequate for stable bubble operation, but the resin is not intended to replace metallocene grades in premium transparent packaging where haze and gloss are critical. The selection of 6135NE is therefore appropriate when additive flexibility, higher melt strength, and moderate cost are more important than maximum clarity or maximum toughness.

Regulatory compliance follows the polyolefin food-contact framework. In the United States, the base olefin polymer may be evaluated under 21 CFR 177.1520 for olefin polymers in food-contact articles, provided the finished film meets extractives limitations and conditions of use. In the European Union, plastic food-contact materials are assessed under EU 10/2011, with overall migration limits depending on film thickness, food simulant, and contact time. SABIC supplies regulatory documentation covering REACH SVHC disclosure and, where applicable, RoHS Directive 2011/65/EU; the converter must verify the current lot-specific declaration before use. The grade is not UV-stabilised and should not be used for prolonged outdoor exposure unless carbon black or a hindered-amine light-stabiliser masterbatch is added. Additive compatibility should be confirmed with the masterbatch supplier because some amine-based additives can influence organoleptics or sealing behaviour. No chlorine- or sulfur-containing additives are intentionally introduced; combustion products are those of a hydrocarbon polyolefin.