Hanwha HDPE 870F is a high-density polyethylene blown-film grade supplied as pellets by Hanwha TotalEnergies Petrochemical Co., Ltd. The nominal density is 0.951 g/cm³ when measured to ASTM D1505 or ISO 1183-1, and the melt flow rate is 0.30 g/10 min at 190 °C under 2.16 kg load, ASTM D1238 / ISO 1133-1. These values define a fractional-melt, high-molecular-weight resin with a crystallinity-driven modulus higher than linear low-density polyethylene grades of equivalent melt flow rate. The base pellet is not formulated with slip or antiblock additives; surface friction modification is introduced during conversion as additive masterbatch to allow customised coefficient-of-friction control. The resin is intended for thin-gauge blown film between 10 µm and 80 µm, where its melt strength supports stable bubble formation at blow-up ratios that would destabilise lower-viscosity HDPE film grades. Lot-to-lot variation in density is typically ±0.001 g/cm³, and the melt flow rate should be referenced against the certificate of analysis for the specific production campaign.

What Die Gap and Blow-Up Ratio Stabilise the 0.951 g/cm³ Bubble?

On a grooved-feed single-screw extruder with 65 mm screw diameter and L/D 30:1, the recommended barrel profile is 180/190/200/205/210 °C from feed to die adapter, with die temperature held at 210 °C. The melt temperature measured at the die entry should be kept between 195 °C and 215 °C; excursions above 220 °C initiate oxidative gel formation and bubble flutter on film thinner than 25 µm. A spiral mandrel die with 200 mm diameter and 1.2 mm to 1.6 mm die gap permits head pressures of 25 MPa to 35 MPa, which are sufficient to homogenise the melt but low enough to avoid melt fracture at shear rates below the critical stress threshold. Blow-up ratio is typically set at 3.0:1 to 4.5:1; below 3.0:1 the film exhibits excess machine-direction orientation and reduced dart impact, while above 4.5:1 bubble contact with the air ring becomes uneven on single-lip cooling systems.

Frost line height is controlled at 5 to 8 die diameters. On a 200 mm die, this corresponds to 1.0 m to 1.6 m above the die face, with higher frost lines increasing transverse tear strength but reducing machine-direction stiffness. Output on a 65 mm extruder with a 200 mm die typically ranges from 80 kg/h to 110 kg/h when cooling air is supplied at 10 °C to 18 °C. Higher output requires a dual-lip air ring or internal bubble cooling to remove heat from the high-density melt, because the limiting factor is not screw recovery but bubble cooling capacity. Melt pressure variation should remain within ±0.5 MPa; broader fluctuations indicate unstable feed-section temperature or grooved-bush wear.

In thin-gauge sack production, the grade is run at 15–20 µm thickness. At 15 µm, the extrusion line is sensitive to die-lip build-up caused by low-molecular-weight species accumulating after approximately 6–8 hours of continuous operation. Operators should schedule die-lip cleaning after each shift when running at temperatures above 210 °C. An air gap of 1.5 mm to 2.0 mm between die exit and first cooling air contact is preferred to delay solidification until the bubble reaches the desired diameter.

Mechanical Property Benchmarks on a 25 µm Monolayer Line

The following representative values are obtained on a monolayer blown film line using a 25 µm specimen and are cited with their associated test methods. The numbers are supplier technical literature values, not absolute process guarantees; converters must verify performance on the installed line because gauge variation and orientation balance alter the final properties. Published data for this specific configuration is limited where indicated.

The yield tensile of 24 MPa is lower than that of high-stiffness HDPE grades with density 0.958 g/cm³ or greater, but the elongation at break above 600 % and the F50 dart impact of 140 g on 25 µm film make the grade preferable for applications requiring puncture resistance rather than maximum flexural modulus. The melt flow rate of 0.30 g/10 min also means the 870F film exhibits higher machine-direction tear resistance than HDPE grades with melt flow rates above 1.0 g/10 min, because higher molecular weight raises the failure energy of oriented tie molecules. The softening point of 122 °C allows hot-fill contact in non-pressure applications limited by distortion rather than melting. At equal gauge, the 0.951 g/cm³ grade shows higher moisture vapour transmission than a 0.958 g/cm³ HDPE grade because of the lower crystalline phase fraction.

Against linear low-density polyethylene film grades of comparable melt index, 870F has a higher tensile yield strength and lower dart impact, which is a direct consequence of high-density polyethylene crystallinity. Against high-density polyethylene grades with melt flow rates of 0.7–1.2 g/10 min, 870F shows higher melt strength and lower throughput capability, making it more stable on high-stalk film lines but less suited to high-output lines with narrow die gaps. If melt fracture occurs at die gaps below 1.2 mm, addition of a fluoropolymer processing aid at 200–400 ppm is effective; levels above 800 ppm can reduce interlayer adhesion in coextruded film structures.

When 870F Replaces a 0.958 g/cm³ HDPE in Heavy-Duty Sacks

In applications such as heavy-duty sacks, converter evaluations often consider replacing a 0.958 g/cm³, 0.5 g/10 min HDPE film grade with 870F to improve tear resistance at the expense of stiffness. At equal 25 µm thickness, 870F typically shows a reduction in tensile yield strength of approximately 8–12 % relative to the higher-density grade and an increase in Elmendorf tear of roughly 15–20 % in the transverse direction. The lower crystallinity of the 0.951 g/cm³ grade reduces secant modulus as measured by ISO 527-3; if sack stacking strength is the critical requirement, the converter must increase film gauge by 5–10 % to recover bending stiffness. Conversely, for frozen-food liners or heavy-duty industrial liners subject to puncture from sharp particulate, the 870F film at equal gauge outperforms the higher-density grade in F50 dart impact.

This trade-off is structurally governed by the density difference and the resulting amorphous phase fraction. The processing window is also narrower: the lower density, higher molecular weight resin generates higher melt pressure at equal screw speed and requires a wider die gap by approximately 0.2–0.4 mm to prevent sharkskin. On a 65 mm grooved-feed extruder, the replacement can reduce maximum stable output by 5–10 % if the die is not changed, because pressure limits are reached earlier. The grade is unsuitable for injection moulding applications because the melt flow rate of 0.30 g/10 min is far below injection grade HDPE values of 8–20 g/10 min, resulting in excessive mould filling pressure and short shot sensitivity.

Compliance Matrix for Food-Contact and Industrial Packaging

The polymer used in 870F is a high-density polyethylene that can be used in food-contact applications when the finished article meets extraction limits under 21 CFR 177.1520 and, for European markets, Regulation (EU) No 10/2011. Converters must perform overall migration testing on the finished article because compliance of the base resin does not automatically extend through processing aids, printing inks, or adhesives. The grade is not supplied with a global migration certificate covering all film constructions.

When 870F is used in direct food contact, the processor must control the regrind fraction. Post-industrial regrind from the same film line can be reintroduced at up to 20 wt% without measurable loss of dart impact if the regrind is dried and free of paper label contamination. Higher regrind levels increase gel counts and lower transverse tear strength. The resin should be stored at ambient temperature below 50 °C and protected from UV exposure for periods longer than 6 months; extended storage can cause surface oxidation that appears as yellowing at the die lip. If stored at relative humidity above 60 %, preconditioning in a hopper dryer at 70–80 °C for 2 hours removes surface moisture and prevents bubble pinholes. The upper service temperature for the final film should not exceed 80 °C in continuous load-bearing applications, because the creep modulus of high-density polyethylene declines above this threshold.