Lotte Chemical HDPE HIVOREX 7000F is a high-density polyethylene film resin in the low melt flow rate segment of the HIVOREX product range. Published producer literature lists a nominal density of 0.954 g/cm³ under ASTM D1505 and a melt flow rate of 0.04 g/10 min under ASTM D1238 at 190°C/2.16 kg. The grade is positioned for high-stalk blown-film extrusion, where bubble stability and drawdown are governed by high melt viscosity rather than low shear viscosity. It is supplied in pellet form and processed on mono-layer or co-extruded blown-film lines into thin-gauge HDPE articles such as T-shirt bags, waste sacks, agricultural film, and industrial liner skins. The same published literature indicates tensile yield stress near 29 MPa under ASTM D638 and elongation at break above 500%; actual lot values must be taken from the certificate of analysis. Because of the low melt flow rate, the product falls outside the recommended processing window for injection moulding and rotational moulding, where multi-cavity filling requires substantially higher flow.

On a production blown-film line with a barrier screw and L/D ratio of 25:1 or greater, the resin is typically extruded through a die gap of 1.2 mm to 1.8 mm. Blow-up ratios between 3:1 and 4:1 with a high-stalk bubble allow the film to orient in the machine direction before frost-line impingement. Frost-line height is normally held at 5 to 8 die diameters to achieve gauge consistency and reduce sag. In this configuration, film thickness below 15 µm is drawable without reverting to LLDPE-based formulations. The high melt viscosity raises die-head pressure by comparison with medium-melt-index HDPE film grades; extruder drive sizing, screen-pack pressure drop, and die body pressure rating must therefore be checked before scaling from a 55 mm laboratory line to a 90 mm production line. Published data for laboratory-to-production scale-up on this specific grade is limited, so validation runs are necessary.

What melt temperature and screw configuration are required for stable output?

Because the shear viscosity is high, barrel-zone set points between 180°C and 210°C and die-head set points of 210°C to 230°C are used to keep die entrance pressure within the rated pressure of typical spiral mandrel dies. Shear heating can add 10°C to 20°C to the melt stream, so melt temperatures measured at the die entry often exceed barrel set points even without external heating. The feed zone is frequently water-cooled to preserve solids conveying and prevent bridging above the feed throat when backpressure rises above 300 bar; grooved-feed extruders increase pressure stability at the cost of higher drive torque. Extruders below 0.15 kW per kg/h of specific drive power may experience screw-speed plateaus before target output is reached. Screw speed should be adjusted to limit melt temperature below 245°C; above this threshold, oxidation-induced gel formation and die-lip deposit can increase. If a screen changer with 100 mesh filtration is used, the additional pressure drop should be added to the die pressure calculation because high-viscosity HDPE films are sensitive to upstream pressure fluctuations. No published processing window replaces the need for a design-of-experiments trial across barrel profile and frost-line height on the target line.

Film property statements for HIVOREX 7000F must be anchored to test methods and gauge. Under ASTM D882, machine-direction yield stress commonly cited is near 29 MPa; elongation at break is reported above 500% for laboratory films. Dart drop values under ASTM D1709 for 25 µm film are strongly influenced by bubble stability and gauge uniformity rather than resin alone; converter data often fall between 100 g and 200 g for acceptable film, while poor stalk control can push values below 80 g even though the resin is unchanged. Elmendorf tear under ASTM D1922 is anisotropic: machine-direction tear exceeds transverse-direction tear in high-stalk HDPE film, which makes orientation and bubble geometry part of the specification. Water vapor transmission of 25 µm HDPE film is lower than that of an equal-gauge LLDPE or LDPE film under ISO 15106, but a single numeric claim is meaningful only when test temperature and relative humidity are fixed. The product is not inherently UV-stabilized; outdoor exposure requires a masterbatch containing hindered amine light stabilizer and carbon black at levels sufficient for the intended weathering class under ASTM D5208 or ISO 4892-2 exposure cycles.

Material identity and the specification envelope represented in conversion lines

The identity of HIVOREX 7000F as a low-melt-flow, high-density film resin is defined by two primary numerical boundaries. The first boundary is the melt flow rate, which at 0.04 g/10 min places the grade below medium-MI HDPE film resins and far below injection-moulding grades having values of 5 g/10 min or greater. The second boundary is the density, which at 0.954 g/cm³ produces higher flexural stiffness than C6 or C8 linear low-density polyethylene film resins. These two boundaries control both conversion economics and mechanical performance. A typical property table produced from the supplier’s published data contains the following values.

The values in the table are not lot-specific and carry the tolerances of the test methods. For example, density by ASTM D1505 can vary in the third decimal by ±0.001 g/cm³ between production campaigns without altering film performance. Melt flow rate determined by ASTM D1238 at 190°C/2.16 kg has reproducibility limits that can span ±0.005 g/10 min; converters should set incoming raw-material limits on the basis of internal process capability rather than a single nominal value.

Primary conversion routes for HIVOREX 7000F are high-stalk blown-film extrusion into retail carrier bags, produce rollstock, refuse sacks, industrial liners, and agricultural mulch films where stiffness and downgauging are economical. In a retail bag conversion line, the high modulus of the film reduces bag side-seal deformation during automatic wicket punching; machine-direction tensile strength measured under ASTM D882 supports the punching force without elongation beyond the wicket spacing. In refuse sacks, downgauging from 25 µm to 18 µm is feasible only when the film maintains tear propagation resistance under ASTM D1922 and the converter’s bag drop tests confirm field handling. Co-extruded structures place HIVOREX 7000F in the core or outer skins because its high melt strength stabilizes the HDPE layer against draw resonance when paired with LLDPE or metallocene LLDPE skins. Since the resin is unpigmented, carbon black masterbatch is used for UV-resistant sacks and white masterbatch for retail packaging; masterbatch let-down ratios of 3% to 6% are common but require dispersive mixing to avoid fisheye gels. The low MFR does not prevent blending with LLDPE up to 20% to modify tear balance, provided the blending ratio is kept constant by gravimetric dosing.

Comparative position among HDPE film, injection molding, and LLDPE materials

HIVOREX 7000F differs from medium-melt-index HDPE film grades and from injection-moulding or rotational-moulding HDPE in distinct operational ways. Compared with a medium-MI HDPE film grade at 0.2 g/10 min to 0.5 g/10 min, the 0.04 g/10 min melt flow rate of 7000F increases bubble stability and drawdown in high-stalk equipment but reduces mass throughput per unit screw speed. Compared with an injection-moulding HDPE at 10 g/10 min, the same density of 0.954 g/cm³ produces similar rigid stiffness, but the melt viscosity is far too high for spiral flow or thin-wall filling; processing in an injection machine is not recommended. Compared with a C6-LLDPE film resin of density 0.920 g/cm³, the HDPE film is stiffer and has lower dart impact under ASTM D1709, but superior moisture barrier under ASTM E96 or ISO 15106. The choice of HIVOREX 7000F is therefore driven by stiffness, downgauging, and bubble stability requirements, not by puncture or clarity. Grade substitution must be verified against the supplier’s technical data sheet and a processing trial because different HIVOREX grades carry different melt flow and density envelopes.

The resin should be stored in sealed silos or bags at 25°C ± 10°C and protected from direct sunlight. HDPE pellets are not hygroscopic enough to require routine desiccant drying; however, surface condensation at relative humidity above 60% can introduce moisture into the feed throat and increase oxidation potential at melt temperature. Open-air hopper residence times should be minimized when ambient dew point approaches the pellet temperature. Antioxidant protection is formulated for normal extrusion temperatures; repeated reprocessing above 20% regrind can reduce dart impact and increase gel formation unless melt temperature is held below 245°C and screen packs are changed at a defined pressure-rise limit. The grade is not the first selection where constant-load stress-crack resistance is the controlling requirement; published comparative data on this specific film configuration is limited, and notched constant tensile load testing per ASTM D5397 may be necessary when aggressive detergent-containing liquids contact the film in service.

When lot-to-lot variation shifts extrusion pressure and motor load

Production lots of low-MI HDPE film resins can exhibit small shifts in melt rheology due to molecular weight distribution and additive package. If feed pressure at the breaker plate increases by more than 15% for a fixed screw speed and barrel profile, the first response is not barrel-temperature reduction but a verification of die gap, screen-pack loading, and lot-specific melt flow rate. A lot at the lower end of the melt flow rate tolerance may require screw-speed reduction of 10% to 20% to stay below extruder drive current limits. Bubble stability can remain acceptable even when melt flow rate varies by ±0.005 g/10 min, but frost-line height and blow-up ratio must be retuned. On multi-layer lines, layer ratio control by gravimetric feeders is the primary safeguard against layer-to-layer viscosity mismatch, because an HDPE layer with higher viscosity than the adjacent LLDPE skin can create interfacial instability and optical haze. Statistical process control of melt temperature, die pressure, and frost-line position is the only reliable method for distinguishing resin lot variation from machine drift; melt pressure at the die plate should be recorded at 1 Hz or faster during trial runs. Published data for this specific configuration is limited, so incoming inspection should include capillary rheometry at 190°C and 210°C rather than relying solely on melt flow rate.

Regulatory status of HIVOREX 7000F must be confirmed with Lotte Chemical for each market. In food-contact applications, HDPE olefin polymers are covered under FDA 21 CFR 177.1520 when the resin is produced in compliance with the applicable olefin polymer specifications; the converter remains responsible for end-use migration testing under 21 CFR 176.170 or 21 CFR 177.1520 as appropriate. For the European Union, compliance with Regulation (EU) No 10/2011 requires a declaration of compliance and a migration limit assessment for the final film. REACH registration under Regulation (EC) No 1907/2006 and SVHC content below 0.1% w/w must be verified by the supplier or importer. RoHS Directive 2011/65/EU restrictions apply to electrical and electronic equipment; the grade itself is not an electrical product, but converters supplying E&E packaging may need to demonstrate absence of restricted substances under Harmonized Standard EN 50581.