Japan Polyethylene HARMOREX NF366A is a metallocene-catalyzed linear low-density polyethylene resin in the HARMOREX product family. The grade is intended for tubular blown film and related film conversion processes in which low seal initiation temperature, high dart impact after orientation, and controlled extractable content are specified. Publicly listed values from the producer include a nominal melt flow rate of 1.0 g/10 min determined at 190 °C under 2.16 kg load in accordance with ISO 1133-1:2022, and a nominal density of 0.916 g/cm³ determined in accordance with ISO 1183-1:2019. The resin is distinct from conventional Ziegler-Natta butene linear low-density polyethylene: the single-site catalyst used in HARMOREX NF366A distributes α-olefin comonomer more uniformly across the molecular weight distribution, shifting the balance among stiffness, sealability, tear resistance, and optical haze relative to standard LLDPE and low-density polyethylene grades.

Because NF366A occupies the 0.916 g/cm³ density class used in food packaging, agricultural film, and lamination sealant webs, the base resin is generally supplied with food-contact declarations based on FDA 21 CFR 177.1520(c) and Commission Regulation (EU) No 10/2011 Annex I when no non-compliant slip or antiblock additive is introduced. The same regulatory position may not apply automatically to formulated compounds containing added masterbatch, processing aid, or reclaimed content. Lot-specific certificates and declaration confirmations should be obtained from the resin supplier for the exact additive package.

How Does Metallocene Comonomer Distribution Alter Property Balance?

In a Ziegler-Natta butene LLDPE, the comonomer is preferentially incorporated into lower-molecular-weight chains. Short-chain branching concentrates in fractions that depress melting point and seal initiation, while the higher-molecular-weight tail remains more linear and crystallizable. This heterogeneity creates a broad crystallite thickness distribution and non-uniform plastic response under impact. HARMOREX NF366A, by contrast, is produced with a metallocene catalyst system that places the α-olefin comonomer more evenly along chains of different molar mass. The resulting crystalline superstructure contains a narrower distribution of lamellae, and the amorphous phase is more uniformly connected by tie molecules. That structural change lowers the seal initiation temperature for a given density and improves dart impact propagation resistance, but it also narrows the processing window for melt temperature and shear rate because the molecular weight distribution is not as broad as that of autoclave LDPE.

The following table compares class-typical values for NF366A with conventional butene LLDPE and LDPE film resins. Values marked as class-typical are taken from public polymer science reference data and converter trials, not from a guaranteed lot-specific certificate.

Published data for NF366A-specific dart impact values are limited in public summary documents; converter validation on the target film line is required because dart impact results depend on die geometry, blow-up ratio, frost line height, and ambient air conditions. The class-typical ranges are provided to distinguish the metallocene performance envelope from conventional grades.

The structural difference also appears in seal strength after contaminated seal geometry. Because NF366A can crystallize into thinner lamellae at the film surface, the seal initiation temperature is reduced, while the melting temperature of the bulk film remains high enough to retain stiffness. In contrast, a butene LLDPE of the same density may require either a lower density or an LDPE blend to achieve equivalent seal initiation, which can reduce modulus and tensile strength. Hexene LLDPE produced with conventional Ziegler-Natta catalysts can approach the seal initiation of metallocene LLDPE in some formulations, but the narrow molecular weight distribution of NF366A tends to lower extractable content and improve organoleptic behavior when melt temperature is controlled.

When a 40-L/D Grooved-Feed Extruder Runs NF366A at High Backpressure

In production-scale blown film, NF366A is usually processed on a single-screw extruder with an L/D ratio between 30:1 and 40:1, equipped with a barrier screw and spiral mandrel or crosshead die. The melt temperature is typically maintained between 190 °C and 215 °C at the die exit. Because the resin has a narrow molecular weight distribution and a density of 0.916 g/cm³, it generates lower shear thinning than autoclave LDPE; a grooved-feed section or an intensively cooled feed throat assists stable pellet transport. The die gap is usually set from 1.6 mm to 2.0 mm for 25–50 µm films to limit melt fracture and to preserve impact properties through molecular orientation.

Replacement of LDPE with NF366A raises backpressure more than an equivalent melt-index branched LDPE at the same screw speed. The observed increase reflects the more linear molecular architecture and higher viscosity at elevated shear rates. Head pressure rises of 10–25% relative to a branched LDPE can be expected when replacing the LDPE component in a blend. When die inlet pressure exceeds the adapter or clamp mechanical limit, screw speed should be reduced rather than melt temperature increased without limit, because excessive heat history above 240 °C can extract volatile low-molecular-weight species and increase odor or taste carryover in food packaging.

Bubble stability is generally improved at a blow-up ratio of 2.0:1 to 2.8:1, while higher blow-up ratios can produce excessive transverse orientation and an increase in tear anisotropy. The frost line height is commonly maintained at 6–10 die diameters above the air ring. At low frost line heights, some converter data indicate reduced dart impact and elevated haze because the crystalline structure is quenched before adequate chain relaxation. The resin shows lower melt strength than autoclave LDPE, so large-diameter lines may require vacuum bubble stabilizers or internal bubble cooling to maintain a stable neck at higher output.

Resin handling follows standard polyethylene practice. Pre-drying is not generally required when pellet temperature and storage humidity remain below 60% relative humidity; however, condensation on cold pellets introduced directly into a heated hopper can create surface moisture that appears as film bubbles and melt pressure fluctuations. If heavy moisture exposure is suspected, a desiccant dryer at 60–70 °C for 2–3 h is applied before extrusion. NF366A should not be combined with high levels of peroxide masterbatches in reclaim streams because the resulting radical chain modification may alter the narrow molecular weight distribution and reduce the seal initiation advantage.

Crystallinity, Density, and the Seal Plateau

Because NF366A is a metallocene LLDPE with a nominal density of 0.916 g/cm³, its sealing behavior is governed by the melting and recrystallization of thin lamellae at the film surface. Under heat sealer dwell conditions of 0.5 s and 0.5 N/mm² jaw pressure, the seal initiation temperature for 25 µm film is typically in the 95–105 °C range when measured according to ASTM F2029-22. Conventional butene LLDPE films of the same thickness and density class typically begin to form measurable seal strength near 105–115 °C; autoclave LDPE may seal at 95–105 °C but with lower hot tack strength. NF366A therefore offers a seal plateau that is closer to LDPE than to conventional butene LLDPE.

Hot tack measurements under ASTM F1921/F1921M-12(2023) on a packaging-grade film substrate generally show no loss of seal integrity at contaminated seal geometry as the film cools below 90 °C. However, published data for the specific NF366A formulation in coextruded surfaces are limited. When the grade is used as a sealant web in a blown film coextrusion line, the heat seal strength at 120 °C, 0.5 s, and 0.2 MPa jaw pressure can exceed 8 N/15 mm using ASTM F88/F88M-21. The exact value depends on film thickness, seal bar shape, and interlayer thickness. Optical properties are controlled by surface roughness and crystallite size; the metallocene resin does not automatically produce low haze if the die lip is dirty or if excessive process temperature induces oxidation.

At thicknesses below 20 µm, the difference between NF366A and a conventional butene LLDPE becomes more visible in pinhole testing. The uniform comonomer distribution reduces the density of large spherulitic structures and decreases the probability of localized brittle failure. That said, the property advantage should be quantified by dart impact, Elmendorf tear, and slow puncture, not inferred solely from density. Slow puncture force values in the 30–60 N range are commonly reported for 25 µm metallocene LLDPE films tested at 23 °C with a 12.7 mm diameter probe according to a modified ISO 7765-1:1988 setup; these values must be verified on the specific line.

Food-contact and chemical-regulatory status is a key differentiator when NF366A is evaluated against generic LLDPE grades of non-specified catalyst origin. The base olefin polymer is generally suitable for food-contact applications under FDA 21 CFR 177.1520(c) and Commission Regulation (EU) No 10/2011 Annex I, provided that the film is produced from the manufacturer’s approved base resin and that the additive package meets the restrictions. Migration testing may be required depending on the food type and temperature profile. For high-fat or high-temperature microwave contact, overall migration values below 10 mg/dm² can be demonstrated only after extraction testing under the specified food simulant conditions.

NF366A as a base resin is not classified as hazardous under REACH EC 1907/2006, and contains no intentionally introduced heavy metals; compliance with RoHS Directive 2011/65/EU is declared on a material or component basis. The product should not be assigned to direct skin contact or implantable medical use unless tested to the applicable ISO 10993 series. These statements are not a substitute for lot-specific specifications.

In a coextruded or laminated structure, NF366A is employed as the sealant layer because its lower seal initiation temperature allows the packager to shorten dwell time or reduce jaw temperature. The grade also reduces extractable migration into the sealed cavity compared with a high-branched LDPE of similar density when processed within the recommended temperature window. In adhesive lamination, corona treatment is applied to the substrate face to raise surface free energy from 30–32 mN/m to at least 38–42 mN/m before deposition of a solventless polyurethane adhesive, with wetting tension monitored by ISO 8296:2003. Failure to achieve consistent treatment can produce interlayer delamination at lap seals or during thermal abuse testing. Oxidized low-molecular-weight species generated by excessive melt temperature should be controlled because these species can interfere with primer adhesion and increase the coefficient of friction over time.

In heavy-duty sack applications, the higher dart impact of NF366A relative to butene LLDPE permits downgauging from 50 µm to 40 µm in some constructions, provided the transverse tear resistance and stiffness remain acceptable. This downgauging claim must be validated on the end-user’s packaging equipment because seal bar performance and warehousing compression differ between formats. Published data for NF366A-specific sack constructions are limited.