Linear low-density polyethylene (LLDPE) is an ethylene/α-olefin copolymer whose density and melt flow rate define the main processing boundaries for converters. The domestic Sinopec LLDPE range spans a density of 0.915–0.940 g/cm³ when tested according to ISO 1183-1 and a melt flow rate of 0.5–50 g/10 min at 190 °C/2.16 kg according to ISO 1133-1:2022 or ASTM D1238-20. Butene-1, hexene-1, and octene-1 modification routes are used within the domestic portfolio. The resulting short-chain branch distribution controls stiffness, tear resistance, impact strength, and processability. This technical overview addresses Sinopec LLDPE: Domestic Grade Range and Export Availability without promotional interpretation. The range includes grades for blown film, cast film, extrusion coating, injection molding, rotational molding, and compounding. Export availability is linked to batch certificate of analysis documentation, packaging format, and destination-country regulatory declarations. Typical film grades are supplied as free-flowing cylindrical pellets with a bulk density of 480–540 kg/m³; antioxidant packages are compounded to limit oxidative degradation during storage and conveying. Moisture content on delivery is commonly specified below 0.05 wt% by EN ISO 15512, a threshold that reduces steam-induced surface defects during high-shear extrusion. The following sections separate grade selection by processing route and export documentation requirements.

What Distinguishes Butene- and Hexene-Modified Film Grades Under High-Stalk Extrusion?

In high-stalk blown film extrusion, the choice between butene-1 and hexene-1 comonomer changes the short-chain branch length from C4 to C6. At equivalent density, this architectural difference alters tie-molecule concentration and mechanical response. General-purpose blown film grades are frequently butene copolymers with a nominal density of 0.918–0.922 g/cm³ and a melt flow rate of 1.8–2.2 g/10 min. High-toughness film grades, often produced with hexene-1, are supplied at lower melt flow rates of 0.8–1.2 g/10 min to preserve melt strength during high-stalk processing. The measured dart drop failure mass may shift from 90–120 g to 150–220 g on 50 μm film when comparing a butene and a hexene grade at similar density; these values are sensitive to blow-up ratio and frost line height and are obtained according to ASTM D1709-15 Method A.

On blown film lines equipped with die diameters of 200–350 mm and die gaps of 1.4–2.0 mm, typical melt temperatures are 190–230 °C. Die pressure remains dependent on output and die geometry; operators may record 20–40 MPa at production rates of 80–160 kg/h on a 65 mm extruder. For high-stalk operation, the frost line height is normally maintained 500–900 mm above the air ring; lower positions stabilize the bubble but can sacrifice impact strength. At a blow-up ratio of 3:1, film thickness variation coefficient is generally below 5% when the gauge control system is properly tuned. Blending with low-density polyethylene at 10–20 wt% improves bubble stability but can reduce machine-direction tear strength. At a shear rate of 100 s⁻¹, the viscosity of such a blend may be 5–15% lower than that of neat LLDPE, depending on the LDPE grade. Tear propagation resistance is measured by ASTM D1922-15 or ISO 6383-2; film haze is measured by ASTM D1003-13 and is generally below 12% for clear butene film and below 8% for optimized high-clarity grades. Hexene-modified LLDPE frequently exhibits Elmendorf tear strength 10–40% higher than a butene counterpart at equal thickness.

A processing constraint appears when the frost line height is reduced too aggressively: bubble instability can create gauge variation exceeding ±10% of target thickness. The processing window for high-stalk hexene LLDPE can be narrower than for butene products, requiring more precise air ring adjustment and bubble cage control. Published data for specific commercial substitutions is limited; therefore, grade-specific runs should confirm dart impact and tear at the intended blow-up ratio.

Injection molding grades within the domestic Sinopec LLDPE range are characterized by melt flow rates of 20–50 g/10 min at 190 °C/2.16 kg and densities between 0.924 g/cm³ and 0.930 g/cm³. These products are formulated for thin-wall containers, lids, and closures where processability must be balanced against stress-crack resistance. A grade with a melt flow rate of 30 g/10 min can fill a standard spiral flow mold to 400–600 mm at 2 mm wall thickness under 70–100 MPa injection pressure; published data for this specific configuration is limited, and the value should be confirmed on the target machine. Tensile yield strength falls near 10–12 MPa under ISO 527-2, flexural modulus near 260–350 MPa under ISO 178, and notched Izod impact at 23 °C above 25 kJ/m² under ISO 180/A. Environmental stress crack resistance measured by ASTM D1693-15 can exceed 1,000 h for higher molecular weight injection grades but is significantly reduced at the upper end of the melt flow range.

Extrusion coating and cast film grades occupy an intermediate melt-flow region of 4.0–15 g/10 min with densities of 0.916–0.924 g/cm³. In extrusion coating, neck-in and draw-down are controlled by molecular weight distribution and melt elasticity. Output and substrate adhesion are evaluated on pilot coaters before commercial runs. Flame treatment or corona treatment of the substrate is typically required; surface tension of treated substrates should exceed 38 mN/m under ISO 8296. The use of hexene-1 in this segment improves puncture resistance but may slightly reduce drawdown speed relative to butene-1 grades at equal melt flow rate.

The rotational molding segment uses lower melt flow rates of 3–6 g/10 min and densities of 0.924–0.935 g/cm³. A critical processing parameter is the sintering rate of the ground powder, governed by particle size distribution and crystallization behavior. Mold cavity temperatures of 250–280 °C are common; total cycle time is wall-thickness dependent. The material must withstand long residence at elevated temperature. Oxidation induction time determined by ISO 11357-6 at 210 °C is usually specified above 20 min for rotational molding grades, though the exact value varies with antioxidant package. Incompatibility with high-acidity service media should be assessed by exposure testing rather than inferred from melt flow properties alone.

Grade Designation Logic Across Domestic Production Sites

Alphanumeric designations on Sinopec LLDPE grade certificates encode reactor technology and target melt flow rate or density ranges. Prefixes such as DFDA and DNDA are associated with gas-phase or solution-phase production at domestic sites, but numerical suffixes are not universal across all facilities. The controlling specification is the site-specific certificate of analysis, not the grade name alone. For film grades, batch-to-batch variation is commonly controlled within ±0.001 g/cm³ for density and ±0.3 g/10 min for melt flow rate. The certificate lists density, melt flow rate, comonomer type, tensile yield, and additive loading. Table 1 summarizes representative domestic ranges by processing route.

These ranges are not grade-specific guarantees; each lot CoA remains the enforceable specification. A processor evaluating two sites producing the same nominal designation should compare CoA values before line qualification because additive packages may differ.

For export shipments, Sinopec LLDPE is packed in 25 kg multilayer paper or woven polyethylene bags with automated fill weight control of ±0.1 kg. Flexible intermediate bulk containers of 500–1,250 kg and fiberboard IBCs are used for high-volume converters. Bulk pellet loading from coastal terminals typically runs at 150–300 t/h, although terminal-specific equipment can shift this rate. The material is classified under HS code 3901.40 in many jurisdictions, but the destination tariff schedule must confirm the applicable code. Export documentation includes commercial invoice, packing list, certificate of analysis, safety data sheet, certificate of origin, and bill of lading. The CoA provides batch-specific melt flow rate, density, tensile properties, and ash content. The safety data sheet identifies the material as non-hazardous under OSHA 29 CFR 1910.1200; handling precautions include controlling pellet dust and removing spills to prevent slip hazards. During container transit, the resin should not be stacked in direct sunlight or exposed to temperatures above 60 °C for extended periods, as surface tack and pellet agglomeration are possible. Orders are executed under INCOTERMS 2020 FOB or CIF terms, with title transfer defined in the sales contract.

When Export Documentation Must Align with EU and North American Compliance Regimes

Grade compliance declarations are not generic across all destinations. For food-contact applications, LLDPE without intentionally added heavy metals can be evaluated under FDA 21 CFR 177.1520 and European Union Regulation (EU) No 10/2011. The EU regulation imposes an overall migration limit of 10 mg/dm² of food-contact surface area, but specific migration limits for additives depend on formulation disclosure. For electrical and electronic equipment, RoHS Directive 2011/65/EU requires lead ≤1,000 mg/kg, cadmium ≤100 mg/kg, mercury ≤1,000 mg/kg, hexavalent chromium ≤1,000 mg/kg, and PBB/PBDE each ≤1,000 mg/kg. REACH Regulation (EC) No 1907/2006 requires substances of very high concern not to be present above 0.1 wt% per article. Table 2 summarizes the compliance matrix.

Limitations apply to resin-level certification. Migration compliance under EU Regulation (EU) No 10/2011 depends on final part thickness, contact time, food simulant, and downstream processing history. The pellet itself is not a final article for migration testing; converters must test the finished package. Published data for specific Sinopec LLDPE export formulations may be limited. Consequently, certification requires batch formulation disclosure rather than reliance on a generic resin type. For food-contact applications involving fatty simulants, the additive package and antioxidant migration must be evaluated separately, and certain processing aids may require positive listing.

On single-screw blown film extruders with 24:1–30:1 L/D and barrier screw geometry, LLDPE requires higher motor torque than LDPE at equivalent output. The screw should be designed with a compression ratio of 2.5:1–3.5:1 and mixing elements to complete homogenization without excessive melt temperature. For cast film and extrusion coating, melt temperature is maintained below 260 °C to slow antioxidant depletion and minimize odor-active degradation products. At a melt temperature of 240 °C and a head pressure of 15–25 MPa, the die residence time distribution becomes critical. Converters should not exceed 20 min hold-up during machine stoppage for high-melt-flow grades with limited antioxidant levels. Pre-drying is not routinely required; however, if ambient relative humidity exceeds 60% and cold pellets are exposed to plant air, condensation on pellet surfaces can cause surface defects. Purging with LDPE with a melt flow rate of 0.5–2.0 g/10 min after high-viscosity LLDPE reduces residual gel particles. Apparent shear viscosity at 200 °C decreases from approximately 1,500 Pa·s at 10 s⁻¹ to below 200 Pa·s at 1,000 s⁻¹ for a film grade measured by capillary rheometry according to ISO 11443. These data support screw selection and die land length calculation but do not replace grade-specific rheological trials.