Sinopec Guangzhou Petrochemical Company Limited supplies LLDPE 2001 as a butene-1 comonomer linear low-density polyethylene produced by gas-phase polymerisation. The pellet is intended for general-purpose blown film extrusion, including thin-gauge packaging, agricultural greenhouse film, lamination film, and heavy-duty shipping sacks. Its nominal melt mass-flow rate of 2.0 g/10 min at 190 °C under 2.16 kg according to ISO 1133-1:2022 and nominal density of 0.920 g/cm³ according to ISO 1183-1:2022 classify the grade at the low-density end of the LLDPE film range. Because the comonomer is butene-1 rather than hexene-1 or octene-1, the short-chain branch distribution is relatively broad, giving a balance between dart impact and melt strength that is typical of Ziegler-Natta butene LLDPE. The resin is supplied as pellets with a slip and antiblock additive package; the exact additive actives and loading are not publicly disclosed and may vary by supply contract. The additive package differentiates LLDPE 2001 from natural reactor powder and from grades that rely entirely on downstream masterbatch dosing. Published inline rheology data for this specific grade are limited; developers should therefore validate the grade on the target extrusion line rather than predict film performance from MFR and density alone.

The molecular architecture contains short-chain branches but fewer long-chain branches than high-pressure LDPE. In processing terms, this reduces shear thinning and increases extruder backpressure relative to LDPE at the same melt index. LLDPE 2001 should not be treated as a direct drop-in replacement for LDPE in all equipment; screw drive torque and die pressure should be checked when retrofitting an existing line.

Which Lot-Acceptance Properties Govern Film-Grade LLDPE 2001?

The principal resin-level properties used in purchase specifications are melt mass-flow rate, density, visual contamination, and additive concentration. The table below records the published nominal data commonly used for incoming inspection. Film-level mechanical and optical values are not customarily certified on the resin certificate because they are dominated by die geometry, frost line height, take-up tension, and cooling air temperature. A change in density of 0.001 g/cm³ has a larger effect on film stiffness and blocking than a melt mass-flow rate shift of 0.3 g/10 min. Converters therefore compare new lots against preceding certificates and repeat film trials when the density or additive level changes. The producer’s test methods follow ISO 1133-1:2022 for melt mass-flow rate and ISO 1183-1:2022 for density; certificates of analysis remain the controlling document.

The grade is not intended for high-speed cast film lines running at melt temperatures above 240 °C, because residence-time-sensitive oxidative degradation can increase gel formation. For blown film lines, a starting melt temperature of 190 °C to 220 °C is usually sufficient; the melt temperature should be confirmed with an immersion probe rather than inferred from zone set points. Lot-to-lot variability in slip additives can alter film surface coefficient of friction even when MFR and density remain within specification. Incoming inspection should therefore include a film surface check on a laboratory extruder or small production line when a new lot is introduced.

On the blown film die, LLDPE 2001 is processed on single-screw extruders with diameters from 45 mm to 75 mm and length-to-diameter ratios of 24:1 to 30:1. A barrier screw with a Maddock mixing section provides better dispersion of the slip and antiblock package than a simple three-zone screw. The starting cylinder temperature profile is typically 165 °C/180 °C/195 °C/205 °C/210 °C from feed throat to adapter; the die is held at 210 °C to 220 °C. Die gap is generally set between 1.2 mm and 1.8 mm, and the blow-up ratio is maintained between 2.0:1 and 2.7:1. With a 200 mm die, a frost line height of 5 to 7 die diameters produces a stable bubble without excessive orientation. If the line has internal bubble cooling, the frost line can be lowered to 3 die diameters to increase output, but this narrows the dart impact window. Field experience on air-cooled monolayer lines indicates that the practical maximum haul-off speed for 20 µm film is usually limited by bubble flutter and blocking, not by melt delivery; the exact limiting speed depends on tower design, air ring, and ambient humidity. Operators should record frost line vertical position and screen pressure at each haul-off speed to define the stable operating window before production runs.

When LLDPE 2001 Is Compared with DFDA-7042 or Metallocene LLDPE

DFDA-7042 and LLDPE 2001 occupy the same butene-copolymer film segment. The nominal melt mass-flow rate of DFDA-7042 is commonly reported at 2.0 g/10 min and density at 0.918 g/cm³; the practical differences are therefore additive-related, lot-consistency-related, and specification-window-related, not large differences in polymer architecture. LLDPE 2001 is often supplied with a slip and antiblock package, whereas DFDA-7042 may be purchased as a natural pellet that requires separate masterbatch addition. Compared with metallocene LLDPE of similar density, LLDPE 2001 has a broader molecular weight distribution and a broader comonomer composition distribution. These structural characteristics reduce dart impact at equal gauge and increase haze relative to metallocene products, but they improve melt strength and bubble stability on air-cooled lines without internal bubble cooling. The extruder torque at identical melt temperature is usually lower for LLDPE 2001 than for metallocene LLDPE; this allows retrofit to older LDPE film lines with marginal drive torque. For converters requiring low haze, low extractables, and high dart impact at 20 µm, metallocene grades remain the benchmark. For processors seeking a wide processing window, lower backpressure, and compatibility with both low and medium output towers, LLDPE 2001 is evaluated as the broader-processing alternative.

The broader molecular weight distribution of LLDPE 2001 can be inferred from the shear viscosity curve on a capillary rheometer. The melt flow ratio is not typically disclosed, but processing behavior reported on film lines shows that higher melt strength relative to metallocene LLDPE is obtained at equivalent MFR and density. This is consistent with lower sensitivity to frost line movement and lower risk of bubble snap at high stalk heights. The resin is therefore sometimes selected for thin-gauge film when the tower lacks internal bubble cooling and the operator must maintain a stable bubble with a slight stalk.

Film property comparisons are generated by the entire extrusion history, not by the pellet certificate alone. When LLDPE 2001 is converted into 50 µm monolayer film at a blow-up ratio of 2.5:1, tensile properties should be measured according to ISO 527-3:2018, Elmendorf tear according to ISO 6383-2:1983, and dart impact according to ASTM D1709. The film typically exhibits higher machine-direction tensile strength than transverse-direction tensile strength because of haul-off orientation. At 20 µm gauge, machine-direction tensile strength is often in the range of 40 MPa to 50 MPa, while transverse-direction tensile strength is commonly lower by 10 % to 20 %, although actual values vary with frost line height, die gap, and ambient temperature. Optical haze measured per ASTM D1003 is typically higher than for metallocene LLDPE films of the same thickness, especially when the frost line is held high. For direct food-contact applications, the final packaging must be evaluated against FDA 21 CFR 177.1520, EU Regulation 10/2011, and GB 9685; the resin certificate does not confer finished-article compliance. Migration testing is the responsibility of the converter because printing inks, adhesives, and process aids alter the overall migration profile.

LLDPE 2001 enters three broad application categories on packaging lines. In garbage bag and carrier bag production, the resin is commonly extruded into 15 µm to 25 µm monolayer films at high stalk heights; machine-direction tensile strength and melt strength determine the length of bag that can be wound before film splits. In agricultural greenhouse film, the resin is often blended with UV stabilizers and anti-drip agents; the additive package of the resin must be checked against the masterbatch carrier because excessive antiblock can increase haze in the visible light transmission band. In lamination films, LLDPE 2001 is surface-treated to a wetting tension of at least 38 mN/m before lamination to paper or aluminum foil; corona treater power and line speed are adjusted to compensate for slip additive migration. The same resin can be used in coextruded structures but is normally placed in the skin layer rather than the tie layer; tie layers require maleic anhydride-grafted polyolefins, and LLDPE 2001 lacks the required reactive functionality.

Storage, Handling, and Purging Boundary Conditions

LLDPE 2001 is not hygroscopic, but cold pellet condensation can generate surface moisture when the resin is moved into a warm, humid warehouse at relative humidity above 85 %. If condensation is visible, the pellets should be dried for 2 h at 40 °C to 50 °C with a drying air dew point below -20 °C. Feed throat temperature should be maintained below 60 °C to prevent pellet softening and bridging. Material changeover from HDPE or metallocene LLDPE should include a purge step with a low-viscosity polyolefin at 180 °C to 210 °C, followed by a full die purge to remove residues. The grade is incompatible with PVC or polyamide residues at melt temperatures above 220 °C; their degradation products can create black specks and gel particles. For long production runs, screen packs of 60/80/100 mesh are typical; total head pressure on a 50 mm extruder is normally below 35 MPa. An increase beyond 45 MPa at constant screw speed indicates screen blinding or severe gel accumulation and requires a filter change before optical haze limits are exceeded.

Pre-drying is not required under normal indoor storage at relative humidity below 60 %. If the resin is stored in outdoor silos and transferred during rain, pellet surface moisture may not be fully removed by the feed throat; silo discharge and conveying air humidity should therefore be monitored. Additive migration to the pellet surface can increase the coefficient of friction in the hopper; maintaining pellet temperature below 55 °C during storage reduces bridging risk.

During high-output line operation, the melt pressure drop across the screen changer is usually the first indication of additive agglomeration or contamination. When LLDPE 2001 is run at a die throughput above 40 kg/h on a 65 mm extruder, a clean screen pack of 60/80/100 mesh typically yields a head pressure below 35 MPa; a rise of more than 10 MPa within a shift suggests filter blinding or melt gel accumulation. Edge trim and start-up scrap from LLDPE 2001 can be reintroduced at levels up to 15 wt % without measurable loss of bubble stability, provided the reclaimed film is ground below 8 mm and kept free of moisture. Addition above 20 wt % may produce visible gels and a measurable reduction in dart impact because of multiple heat histories and oxidative degradation of the slip and antiblock package. The limiting factor in post-industrial reclaim is not pellet yield but contaminant loading; printed film, labels, or silicone-coated release liners should be excluded from the reclaim stream because they degrade at processing temperatures used for LLDPE 2001 and can cause film holes.