CSPC LLDPE 2505H is produced by CNOOC and Shell Petrochemicals Company Limited. The grade is a butene-copolymer linear low density polyethylene film extrusion resin positioned for blown film, cast film, heat-seal layers, and demanding packaging structures where a balance of draw-down, tear resistance, and low-temperature sealing is required. The following application scenarios are written for converters running production-scale extrusion, bag-making, and lamination lines. Where published data for a specific converter configuration is limited, the text states that limitation rather than generating unverifiable performance claims.

In food-contact lamination converting, CSPC LLDPE 2505H is selected as a sealant web against biaxially oriented polypropylene, polyester, or polyamide print webs. For a 50 µm three-layer pouch film, the sealant layer containing the resin is typically set at 40–50 % of total thickness. A 90 mm single-screw extruder with a 30:1 L/D barrier screw and a 1.5 mm die gap is used for blown film, with melt temperature at the die not exceeding 210 °C to limit gel formation. Seal initiation temperature is measured on a laboratory heat sealer with flat PTFE jaws at 0.5 s dwell and 0.5 MPa jaw pressure; converter data for butene-copolymer LLDPE sealants generally fall between 90 °C and 110 °C for a 1.0 N/15 mm seal strength threshold, but the exact value for this grade must be confirmed on the converter’s own film because seal initiation is affected by film gauge, coextrusion quench rate, and slip additive migration. Food-contact compliance in the European Union requires the finished laminate to satisfy overall migration under Regulation (EU) No 10/2011 using simulant A or E according to the packaged food category. In the United States, the sealant film may be covered under 21 CFR 177.1520(c) provided the finished article meets the extractables limits applicable to the intended temperature and food type. The resin should not be blended with maleated adhesion-promoting tie resins unless a coextruded tie layer is positioned between the sealant web and the print web; otherwise heat-seal strength can become delamination-limited rather than cohesive-failure limited. End products include frozen vegetable pouches, liquid condiment sachets, stand-up pouch side gussets, and consumer goods pouches where seal integrity through folding and filling is critical.

What Controls Bubble Stability When the Resin Is Extruded into Heavy-Duty Industrial Liners?

Bubble stability in heavy-duty industrial liners is governed by die gap, blow-up ratio, frost line height, and air-ring configuration. A monolayer line running 100 % CSPC LLDPE 2505H usually operates with a die gap of 2.0 mm, a blow-up ratio of 2.0:1 to 2.8:1, and a dual-lip air ring with chilled air at 8–12 °C. The lower melt tension of the butene-copolymer resin can create bubble sag and gauge bands at line speeds above 45 m/min; a 24:1 L/D single-screw extruder with a 90 mm screw and a Maddock shear mixing section provides homogenization while avoiding excessive screw speed. Melt temperature at the adapter is controlled between 175 °C and 195 °C; above 210 °C surface oxidation can generate gel particles visible in 80 µm film. Frost line height is set from 300 mm to 600 mm above the die, depending on plant ambient temperature and output. Film thickness for industrial liners is commonly 100–200 µm. The end product is tested for dart impact under ASTM D1709, Elmendorf tear under ASTM D1922, and puncture propagation resistance under ASTM D5748. For chemical drum liners, the converter must evaluate permeability and stress cracking against the specific filled chemical; no resin certificate alone establishes UN packaging compliance. Packaging lines report that 100 % LLDPE formulations reduce bubble chatter relative to LDPE-rich blends but increase melt temperature sensitivity; when melt temperature exceeds 195 °C, gauge variation measured by an on-line capacitance gauge increases. Published data for this specific resin configuration is limited; trial runs with a 120 mm die are recommended before committing to line speed targets.

Greenhouse film converting with CSPC LLDPE 2505H begins with a masterbatch let-down at 2–5 wt% of a hindered amine light stabilizer–containing polyolefin masterbatch at the hopper; the exact ratio depends on the active ingredient concentration and target UV exposure duration under ISO 4892-2. A profile blown film line with an 80 mm screw and 1.8 mm die gap is used for 120–200 µm film. The bubble is stabilized with a high-pressure double-lip air ring and internal bubble cooling; without internal bubble cooling, output is limited on 100 mm dies. Blow-up ratio is held at 2.0:1 to 2.4:1 to maintain machine-direction tensile strength. Film aging is tested under ISO 4892-2 cycles, and tensile retention after 3,000 hours is typically specified by buyers rather than provided by the resin supplier. If the film is coextruded as a three-layer cover with ethylene vinyl acetate copolymer outer layers, the core containing CSPC LLDPE 2505H may be blended with 20–30 wt% metallocene LLDPE to increase dart impact, but this blend shifts heat seal behavior if the film is later used for closures. Condensation on the inner greenhouse surface can reduce light transmission; anti-fog additives are added at the converter’s own formulation responsibility because CSPC does not supply compounded film. For mulching films, carbon black masterbatch is used at 3–5 wt%, and the black film then requires separate end-use testing because the masterbatch can alter film tensile elongation and weathering. End products include tunnel and multi-span greenhouse covers, low tunnels, and mulching films. If the same film is later sold into food-contact applications after being marketed as agricultural film, Regulation (EU) No 10/2011 compliance is not directly transferable; the carbon black masterbatch and UV stabilizers must be evaluated separately.

When a Cast Film Line Replaces a Blown Film Line for Industrial Overwrap

On a cast film line, CSPC LLDPE 2505H runs at melt temperature 190–220 °C with a coat-hanger die and a 25:1 L/D single-screw extruder. In 20–50 µm industrial overwrap film, the nominal density of 0.918 g/cm³ delivers low haze and limited seal-through-contamination behavior. Chill roll temperature is a process variable: setting the primary chill roll at 18–25 °C increases output but may reduce hot tack performance, whereas 25–32 °C improves seal strength in tests but raises blocking risk on the wound reel. Converters often add 3–8 wt% of a polyolefin plastomer to reduce unwind noise and improve tensile elongation, but this raises cost and changes coefficient of friction. Coefficient of friction is measured under ISO 8295; the finished film typically requires a slip additive package because the resin alone does not guarantee coefficient of friction targets. If the overwrap is used for food trays, US clearance relies on 21 CFR 177.1520 and the final film must meet the intended-use extractables; EU compliance is based on Regulation (EU) No 10/2011 with simulant E for polyolefins. The absence of an orientation step means film splitting in the transverse direction can occur below 15 µm; converters therefore select thicker gauge or blend with 10–20 wt% LDPE. End products include paper towel packs, bottled water tray overwrap, and hygiene nonwoven roll overwrap. Published data for this specific cast film configuration is limited; converter-run design-of-experiment studies on a 1.5 m-wide cast line are required to set the optimum chill roll gap and air knife position.

Heat Seal Layer Formulation in High-Speed Vertical Form-Fill-Seal Lines

In vertical form-fill-seal packaging lines, CSPC LLDPE 2505H is specified as a sealant layer in 40–90 µm coextruded films. A three-layer structure may comprise a polyamide or polyester outer layer, a metallocene LLDPE core for abuse resistance, and a CSPC LLDPE 2505H seal layer at 15–25 % of total film thickness. The sealant extruder should use a barrier screw with a compression ratio between 2.8:1 and 3.2:1, and melt temperature at the die should not exceed 210 °C. On a high-speed vertical form-fill-seal machine with a dwell time of 0.2–0.5 s, hot tack performance is more important than final seal strength; hot tack is measured according to ASTM F1921. Seal temperature set points on a standard fin-seal jaw fall between 100 °C and 130 °C for a 1.0 N/15 mm threshold, but the actual jaw temperature must be calibrated because thermocouple placement varies. Production experience indicates that film blocking on the fill tube occurs when the sealant layer exceeds 25 % of the structure and packaging room relative humidity is above 70 %. Polyethylene does not require resin drying, but surface condensation on chilled film rolls must be managed by staging. End products include granular detergent pouches, frozen vegetable bags, and powdered beverage sachets. For food contact, the converter must confirm compliance of the entire multilayer structure under Regulation (EU) No 10/2011 and 21 CFR 177.1520, not merely the sealant resin.

A Torque-Limited Draw-Down Regime Observed in Agricultural Stretch Film Extrusion

Draw-down to 10–18 µm on a blown stretch film line imposes a torque limit on the extruder drive when running CSPC LLDPE 2505H alone. On a 70 mm single-screw extruder with a 28:1 L/D intensive mixing section, screw speed is often reduced by 10–20 % relative to LDPE to avoid excessive melt temperature and gel formation. The die gap is set at 1.2 mm, blow-up ratio at 2.3:1, and melt temperature at 190–200 °C. For pallet stretch film, the polymer is blended with 20–30 wt% of a lower density polyolefin plastomer to improve puncture propagation resistance under ASTM D5748. Tackifier masterbatch at 0.5–2.0 wt% may be added by the converter for hand wrap grades, but this changes coefficient of friction and unwind tension. The film is produced as non-crosslinked; service temperature above 40 °C is not recommended for pre-stretched applications because residual creep can lead to load destabilization. End products include machine pallet wrap, hand wrap, and silage stretch film. For silage film, final compliance with agricultural film specifications requires testing of oxygen transmission rate according to ASTM D3985 and UV stability under ISO 4892-2, neither of which is defined by the polyethylene resin alone.