ExxonMobil HDPE HD 56200 is a high density polyethylene resin intended for blown film extrusion. The nominal specification values are a density of 0.956 g/cm³ when measured according to ASTM D1505 and a melt index of 0.20 g/10 min when measured according to ASTM D1238 at 190 °C under a 2.16 kg load. These values place the grade in the high molecular weight HDPE film category, where a low melt index corresponds to higher melt viscosity, improved bubble stability, and greater resistance to draw resonance on long-stalk film lines.

The resin is used in cereal liners, dry food pouches, snack food overwrap, and multi-wall bag liners. Film performance is evaluated under ASTM D882 for tensile properties, ASTM D1922 for Elmendorf tear, ASTM D1709 for dart drop impact, and ASTM F1249 for water vapor transmission. Because the density is above 0.940 g/cm³, the material is classified as high density polyethylene under ISO 1183-1:2019 and ASTM D1505 density criteria.

HD 56200 is distinguished from injection-molding HDPE grades by its melt index. Injection-molding HDPE grades are often specified in the 20 g/10 min to 50 g/10 min range to fill thin-wall molds at economical cycle times. At 0.20 g/10 min, HD 56200 has a higher molecular weight and a higher melt viscosity; it is not suitable for thin-wall injection molding because fill pressure and cycle time increase beyond typical machine limits. Blow-molding HDPE grades with melt flow rates of 0.30 g/10 min to 0.80 g/10 min are formulated for parison sag resistance and die swell; HD 56200 is formulated for film bubble stability, and substitution into blow molding should be verified on the target machine because die swell and parison geometry differ.

What Processing Window Applies to Blown Film Lines Running HD 56200?

Production-scale blown film lines running high molecular weight HDPE generally employ grooved feed sections and barrier screws with an L/D ratio of 24:1 to 30:1. Melt temperature measured at the die is maintained between 190 °C and 220 °C. At die temperatures below 180 °C, melt pressure rises and throughput becomes limited by available screw torque. At die temperatures above 230 °C, bubble stability decreases because thermal degradation reduces melt strength. The die gap is set at 1.2 mm to 2.0 mm, and a blow-up ratio of 4:1 to 6:1 is used with a high-stalk bubble. The frost line is typically maintained between 400 mm and 800 mm above the die face. These ranges are drawn from HMW-HDPE film extrusion practice; published data for this specific configuration is limited, and the exact set points must be optimized on the line because output rate, air temperature, and die diameter interact with the resin.

A reverse barrel temperature profile is common for HD 56200. The feed zone is set at 160 °C to 180 °C, the compression zone at 190 °C to 210 °C, and the die at 200 °C to 220 °C. The reverse profile accounts for shear heating generated by the high melt viscosity. On cast film lines, HD 56200 is not normally specified because the low melt index can generate elevated die pressure and surface roughness in flat dies; blown film remains the primary conversion route.

At low shear rates typical of bubble stretching, the melt viscosity of HD 56200 is high because of the 0.20 g/10 min melt index. Under capillary rheometry at 190 °C, high molecular weight HDPE resins with similar melt indices display pronounced shear thinning. Although the supplier datasheet does not publish a complete viscosity curve for HD 56200, capillary rheometry can be performed by the converter using ASTM D3835 to determine pressure drop in the die and to set screw speed limits. Published data for this specific configuration is limited; die pressure and melt temperature should be measured directly on the line.

On lines with 90 mm to 120 mm extruders and die diameters of 250 mm to 400 mm, output stability is maintained by controlling die temperature and frost line. Field reports indicate that frost line heights above 800 mm can produce bubble sway when the cooling air system has an ambient air temperature above 30 °C. This is a production-scale observation, not a universal limit.

If Moisture Barrier and Modulus Are Weighted Above Tear Resistance

The high density of HD 56200 makes it suitable for structures where water vapor transmission and film stiffness are limiting factors. Compared with linear low density polyethylene film resins with densities of 0.918 g/cm³ to 0.930 g/cm³, the 0.956 g/cm³ density of HD 56200 produces a higher crystalline fraction and a longer diffusion path for water vapor. The trade-off appears in tear and impact properties: machine direction Elmendorf tear and dart drop impact are lower than those of LLDPE at equivalent thickness. The selection therefore depends on the package failure mode. When flex-crack leakage under product load is the dominant failure, the higher modulus of HD 56200 resists film deformation. When puncture by sharp edges is the dominant failure, an LLDPE-rich structure or an HDPE-LLDPE blend is usually required.

Comparative evaluation should include tensile yield and elongation under ASTM D882, Elmendorf tear under ASTM D1922, dart drop impact under ASTM D1709, and water vapor transmission under ASTM F1249 at 38 °C and 90 % relative humidity. A change in film thickness from 25 µm to 50 µm does not alter density, but it reduces water vapor transmission through the increased thickness path. Published data for this specific configuration is limited; converter-side testing on the intended film structure remains necessary because water vapor transmission and impact are influenced by film gauge uniformity, extrusion temperature profile, and cooling rate.

Property Verification and Standards Cross-Reference

The product datasheet values for density and melt index are determined under ASTM D1505 and ASTM D1238. The ISO equivalents are ISO 1183-1:2019 and ISO 1133-1:2022. Film properties are measured under ASTM D882 for tensile properties, ASTM D1922 for Elmendorf tear, ASTM D1709 for dart drop impact, and ASTM F1249 for water vapor transmission. The thickness of test films is verified under ASTM D6988. These methods provide the data used for lot release and conversion line qualification.

In a production environment, the melt index value of 0.20 g/10 min is a critical control point because it correlates with bubble stability and film tensile strength. A shift of 0.02 g/10 min above the nominal value can indicate a lower molecular weight and may reduce melt strength. A shift below nominal can indicate higher molecular weight and may increase extruder amperage and die pressure. Lot-to-lot variation is therefore monitored with ASTM D1238 before conversion.

These values are nominal supplied properties and should not be interpreted as release limits unless stated in an agreed specification document.

Field observations on HMW-HDPE blown film lines indicate that bubble oscillation and edge wrinkles are the principal process failure modes. These failures become more frequent when the die gap is above 2.4 mm or when the blow-up ratio exceeds 6:1. Maintaining frost line height below 800 mm and die temperature between 200 °C and 220 °C reduces oscillation. A low-stalk bubble configuration used for many LLDPE lines produces insufficient melt relaxation and poor gauge uniformity with HD 56200; a high-stalk configuration is required.

The table is a comparative classification, not a replacement for direct testing. The injection molding HDPE range is given for unfilled narrow-molecular-weight grades; filled or specialty injection grades may fall outside the stated melt index range.

Within the HDPE film density range, a reduction from 0.956 g/cm³ to 0.949 g/cm³ decreases modulus and water vapor barrier but increases dart impact and tear resistance. A difference of 0.005 g/cm³ to 0.007 g/cm³ is commercially significant because it shifts the balance between stiffness and toughness. Converters that require a softer, tougher HDPE film select a density below 0.950 g/cm³; converters that require a moisture barrier select a density near or above 0.955 g/cm³. HD 56200 is positioned at the barrier end of that range.

For food-contact use, the converter must verify compliance under 21 CFR 177.1520 for olefin polymers. The grade is supplied as a pellet, and any slip or antiblock additive content is specified only in formulated subgrades. REACH and RoHS status must be confirmed against the specific lot documentation because regulatory status can change with manufacturing site and additive package. The resin should be stored in closed containers at ambient temperature and protected from UV exposure to prevent molecular weight changes. Pre-drying is not normally required when containers remain closed, but at relative humidity above 60 %, surface moisture can be absorbed and should be removed in a hopper dryer at 70 °C for 2 h to 4 h before extrusion.

Prolonged contact with strong oxidizing acids at elevated temperature can cause chain scission and a reduction in melt viscosity. Aromatic and chlorinated hydrocarbons swell the polyethylene matrix and should not be used for hot cleaning of film dies or extruder parts when residual resin is present. The resin is insoluble in water and resistant to polar solvents under normal conditions.

When HD 56200 is used in a multi-wall bag liner at 50 µm thickness, the film is evaluated for gauge uniformity, dart impact, and water vapor transmission. The converter typically runs the film at a blow-up ratio of 4:1 and a frost line height of 600 mm; deviations from these conditions require revalidation of film properties because gauge distribution affects all measured values. Published data for this specific configuration is limited, so production trials remain the definitive assessment.