Sinopec Qilu Petrochemical Co., Ltd.

Sinopec Qilu Petrochemical Co., Ltd. operates an integrated naphtha cracking and downstream conversion complex in Zibo, Shandong Province, with production organized around C2, C3, and C4 value chains. The company supplies suspension polyvinyl chloride (PVC) resins, high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), solution-polymerized polybutadiene rubber (BR), emulsion and solution styrene-butadiene rubber (SBR), and C4-derived chemical intermediates. Product designations are assigned for specific application segments: PVC resins are commonly supplied as SG-3, SG-5, SG-7, and SG-8 models under GB/T 5761-2018, while polyethylene grades are differentiated by melt flow rate and density class rather than a single model code. Shipments are made as powder, pellet, or bale with certificate-of-analysis documentation tied to polymerization line and production lot. Published data for exact model-level performance is limited to producer technical datasheets and type-test certificates.

The integrated ethylene supply at the site reduces monomer transport exposure and allows recycled monomer streams to be routed back into the polymerization units. This is a difference from non-integrated polymer producers that purchase vinyl chloride monomer, ethylene, or butadiene on the merchant market. In lot release terms, integration alone does not guarantee lower gel count or better color, but it can reduce batch-to-batch monomer variability and provides lot traceability back to the steam cracker. The process is operated under the Sinopec quality management system with test methods listed on each certificate of analysis.

What Differentiates Ethylene-Integrated Suspension PVC from Carbide-Based Resin?

The Qilu PVC route begins with ethylene-based vinyl chloride monomer, whereas a substantial share of Chinese suspension PVC is produced from acetylene generated through calcium carbide hydrolysis. Ethylene-based VCM generally delivers resin with lower total ash and lower residual carbide-derived impurities, but the practical effect depends on the specific stabilization and filtration steps. Under GB/T 5761-2018, prime suspension PVC is commonly described by apparent density 0.45–0.55 g/cm³, volatile matter ≤0.30%, and K-value 66–68 for SG-5 grades. Plasticizer absorption for SG-5 is typically 20–26 g DOP/100 g resin, while SG-3 grades intended for high-impact products may trend lower because of higher molecular weight and higher gelation temperatures.

Processing of suspension PVC on counter-rotating twin-screw extruders is usually run with screw speed 20–40 min⁻¹ and barrel temperatures 170–195°C. The feed zone is held lower to prevent premature gelation before the vent; compression zones are set to complete gelation before the die. Processing above 210°C without sufficient organotin, calcium-zinc, or lead-based stabilizer coverage can cause rapid dehydrochlorination and color shift within 3–5 min at the die. For cable insulation compounds, plasticizer loading of 40–60 phr dioctyl phthalate, diisononyl phthalate, or trimellitate is used, and the dry blend is sieved through 0.125 mm mesh before plastication to remove undispersed resin agglomerates.

Compared with imported Northeast Asian suspension PVC, Qilu resin may differ in fish-eye count, particle size distribution, and plasticizer absorption. These properties affect extrusion speed, screen pack buildup, and gloss. Purchasers should not substitute a different K-value grade without adjusting stabilizer level and processing temperatures. A change of 5 K-value units can shift fusion time and melt viscosity enough to require re-establishment of torque and haul-off conditions on the intended twin-screw line.

Foamed PVC profiles require a resin with low fish-eye count and consistent K-value because the foam structure is sensitive to fusion rate. A melt temperature window of 165–185°C is typical for rigid PVC foam extrusion, with the decomposing blowing agent and stabilizer package set so that gas release matches melt seal. Overfeeding the screw by 5–10% may be required to maintain head pressure. Qilu resin of the SG-7 or SG-8 class may be used in thin-wall foam profiles; these grades have lower K-value and lower gelation temperature than SG-5, permitting higher output but requiring stricter temperature control to avoid early decomposition.

For polyethylene, HDPE and LLDPE grades are characterized by density under ISO 1183-1:2019 and melt mass-flow rate under ISO 1133-1:2022. HDPE blow molding grades may specify melt flow rate 0.25–0.45 g/10 min at 190°C/2.16 kg and density 0.953–0.957 g/cm³; film-grade LLDPE may use octene or butene comonomer, with density 0.916–0.924 g/cm³ and melt flow rate 0.8–1.2 g/10 min. These are broad grade envelopes, not lot acceptance limits. Differences from other polyethylene producers often arise from molecular weight distribution, comonomer distribution, catalyst residue, and pellet shape. A narrow molecular weight distribution with low gel count is preferred for high-speed film lines operating above 150 m/min; a broader distribution can improve blow molding parison sag and reduce melt fracture at high shear rates.

On blown film lines, LLDPE bubble stability depends on die gap 1.8–2.5 mm, blow-up ratio 2.0–3.0, and frost line height 200–400 mm. At winder speeds above 150 m/min, gel counts above 100 per m² may increase web break frequency. In blow molding, melt temperature is usually kept between 190°C and 230°C; a low melt flow rate grade may require higher barrel temperature but raises the risk of resin degradation at the die if residence time exceeds 10 min. These are process interactions observed on production-scale lines, not fixed recommendations for every grade.

Injection molding grades are selected for environmental stress crack resistance, impact strength, and warpage. High-density injection grades may be specified with melt flow rate 5–10 g/10 min at 190°C/2.16 kg and density 0.950–0.955 g/cm³. These grades process on standard reciprocating-screw injection machines with clamp force from 500 to 2500 kN, barrel temperatures 200–240°C, and mold temperatures 20–60°C. Differences from competing products in this segment are usually observed in low-temperature impact failure mode and warpage direction; the user should compare notched Izod impact data under ISO 180:2023 across the same mold geometry.

Polyethylene Pressure Pipe Qualification Data and Extrusion Boundaries

HDPE pressure pipe grades require hydrostatic design basis testing under ISO 9080:2012 and GB/T 18252-2020. A PE 100 classification is not a batch release test; it is an extrapolated minimum required strength of 10.0 MPa at 20°C for 50 years. Qilu HDPE pipe resins supplied into this segment should be qualified by the producer’s type-test certificate and by lot-level melt flow rate, density, and carbon black dispersion. Pipe extrusion commonly uses single-screw grooved-feed extruders with screw diameter 60–120 mm, length-to-diameter ratio 30:1–36:1, and barrel temperatures 190–230°C. Die head zones are held at 200–220°C to control sag in large-diameter pipe. Melt temperature above 240°C should be avoided because oxidative degradation can reduce slow crack growth resistance, even when short-term melt flow rate remains unchanged.

Differences from PVC-U pressure pipe include lower notch sensitivity at low temperature but higher thermal expansion; installation requires expansion loops or anchors. Compared with ductile iron, HDPE is less suited to continuous aboveground exposure unless the grade contains 2.0–2.5 mass% carbon black or a UV stabilizer package accepted for the application. Users should conduct oxidative induction time testing under ISO 11357-6:2018 at 210°C with oxygen and compare values with the pipeline operator’s minimum. Published data for specific Qilu resin performance in chlorinated water at elevated temperatures is limited; long-term qualification testing on the intended pipe line is required.

Differences between Qilu Ziegler-Natta LLDPE and metallocene LLDPE from other suppliers are primarily in comonomer distribution. Metallocene grades typically offer narrower composition distribution, which improves dart impact and clarity, while Ziegler-Natta grades may provide better bubble stability and lower extrusion pressure. The user should not assume that a density and melt flow rate match is sufficient for film conversion; drawdown, seal initiation temperature, and hexane extractables also depend on catalyst chemistry and comonomer type.

When Polybutadiene Rubber Is Used in Tire Tread and High-Impact Polystyrene Modification

Polybutadiene rubber from Qilu is used in tire tread and sidewall compounds, high-impact polystyrene modification, conveyor belts, and footwear. High-cis polybutadiene grades commonly specify cis-1,4 content ≥96%, Mooney viscosity ML(1+4)100°C between 40 and 70, and gel content below 0.5 mass% under ISO 2476:2014. In tire tread formulations, BR is blended with natural rubber and SBR in internal mixers with fill factor 0.70–0.75. The BR component reduces heat buildup and improves abrasion resistance, but content above 30 phr can lower green tack and tear strength. Mixing with silica-filled compounds should keep dump temperature below 160°C to control silanization and avoid premature scorch. For high-impact polystyrene modification, rubber is dissolved in styrene before thermal or graft polymerization; rubber content is typically 5–10 mass%, and solution viscosity must remain within recirculation loop limits to avoid pump cavitation.

Styrene-butadiene rubber grades are specified under ISO 2322:2014 with bound styrene commonly 22–25 mass% and Mooney viscosity controlled for the downstream mixer. In molded rubber goods, lower Mooney grades in the 40–50 range improve flow into complex cavities, while higher Mooney grades provide better tensile properties but require higher mixing energy. A change of 5 units in Mooney viscosity can affect dump temperature in an internal mixer by 3–5°C; therefore, the mixing procedure should be re-established when the grade changes, even if the polymer is from the same producer. Emulsion SBR and solution SBR differ in molecular architecture and formulation response. Emulsion SBR generally contains residual fatty acid and rosin soaps, which can affect cure rate; solution SBR offers lower vinyl or higher vinyl content depending on catalyst modification. For solution SBR, the datasheet should be evaluated for vinyl content, coupling ratio, and oil extension before compounding.

Chemical intermediates from the same C4 stream include methyl tert-butyl ether and raffinate fractions. Methyl tert-butyl ether for gasoline blending is specified by purity, methanol content, and distillation range; typical oxygenate blending purity is ≥98.0 mass% with methanol <1.0 mass%. Raffinate streams are separated for butene-1 recovery and alkylation feed; butene-1 comonomer quality affects LLDPE density control, film clarity, and extractables. The raffinate stream is often consumed within the Sinopec pipeline system rather than sold as a standard product, so published composition data is limited.

Lot release data alone does not qualify a polymer for pressure pipe service

The table below summarizes the primary specification references that are applied to Qilu product families during downstream qualification. Lot release data must be read alongside type-test certificates and application-specific long-term tests.

For all shipment types, the user must confirm the certificate of analysis against the intended process. A PVC dry blend that processes acceptably on a twin-screw line may fail on a single-screw line because of lower shear heating and gelation. A polyethylene film grade with melt flow rate 0.8–1.2 g/10 min may not provide enough melt strength for blow molding. A polybutadiene rubber grade with high cis-1,4 content may cold flow during storage in hot climates if stacking and temperature limits are ignored. These operational limits are product-specific and must be checked against the producer’s technical datasheet, not inferred from the producer name or site integration. Where published data for a specific model designation is limited, qualification trials on the intended production line are required.