Hanwha HDPE 7600 is a high-density polyethylene injection-molding grade supplied by Hanwha TotalEnergies Petrochemical as pelletized resin. The product is identified by CAS registry number 9002-88-4 and is released with a nominal density of 0.956 g/cm³ under ASTM D1505-18 or ISO 1183-1:2019 and a melt index of 7.0 g/10 min at 190 °C under a 2.16 kg load, tested to ASTM D1238-20 or ISO 1133-1:2022. The resin is intended for thin-walled injection-molded articles, caps, closures, housewares, crates, and general molded goods in which rapid cavity filling and short cycle time are process constraints. The high melt flow reduces filling pressure, but it also limits use in blown film, extrusion blow molding, and pressure-pipe extrusion because the melt strength and long-term hydrostatic strength requirements of those processes cannot be satisfied by this molecular-weight distribution.

The melt index of 7.0 g/10 min places the grade among high-flow injection HDPE resins. Under injection shear rates of 10³–10⁵ s⁻¹, the apparent viscosity of linear polyethylene decreases by more than one order of magnitude, which reduces runner and gate pressure losses. Capillary rheometry at 190 °C shows pronounced shear thinning; therefore mold-filling calculations cannot use the melt index alone. A gate-seal study is required to establish the hold-pressure profile because gate freeze-off occurs earlier with high-flow HDPE than with lower-flow grades.

Differential scanning calorimetry according to ISO 11357-3:2018 typically records a crystalline melting peak between 131 and 135 °C, with crystallization onset near 116–120 °C during cooling at 10 °C/min. The density of 0.956 g/cm³ corresponds to a crystalline fraction above 60%, as estimated from density-crystallinity relationships used in ASTM D3418-21. This high crystallinity contributes to flexural modulus and low gas permeability but reduces notched impact toughness and environmental stress-crack resistance relative to medium-density ethylene copolymers.

What specification values are commonly released for Hanwha HDPE 7600?

The values in this table are supplier-published typical values for natural-colored material and should not be interpreted as lot release limits. Conditioning before mechanical testing is typically 40 h at 23 °C and 50 % relative humidity according to ISO 291:2008. Tensile measurements use a type 1A specimen at 50 mm/min, flexural measurements use a 2 mm/min test speed, and Vicat softening is recorded at a heating rate of 50 °C/h with a 10 N load. Actual values of molded parts vary with gate design, flow orientation, molded-in stress, regrind content, and pigment loading.

On conventional reciprocating-screw injection-molding machines, the barrel-temperature profile is typically set from 180 to 230 °C from feed throat to nozzle, with a melt temperature during normal operation of 220–240 °C. Mold temperatures of 20–40 °C are used for thin-wall articles to accelerate solidification. General-purpose screws with an L/D ratio of 20:1 to 24:1 and compression ratio of 2.5:1 to 3:1 are acceptable; back pressure is normally kept below 10 MPa to limit viscous heating and polymer degradation. Excessive nozzle drooling is a known process limitation of high-flow HDPE; decompression relief and a correctly sized nozzle tip are required.

Drying is generally unnecessary for HDPE unless pellet surfaces have been exposed to condensation. If splay appears on the surface of molded articles, the feedstock should be held in a desiccant hopper at 80 °C for at least 2 h, especially when relative humidity exceeds 60%. For hot-runner molds, melt temperature should not exceed 250 °C; prolonged residence times above this temperature produce oxidative discoloration and generate low-molecular-weight fractions that may increase overall migration.

Gate-seal time at a wall thickness of 1.2 mm is often observed in the range of 1.5–3.0 s when using a side gate of 0.8 mm diameter. Gate diameters below 0.5 mm can trigger jetting because the low melt viscosity of the 7.0 g/10 min grade cannot maintain stable fountain flow under high injection speed; the resulting weld-line defects reduce notched impact strength and environmental stress-crack resistance. For this reason, edge gates or submarine gates should be sized from short-shot and cavity-pressure data rather than from standard orifice formulas developed for lower-flow grades. Published data for this specific configuration is limited; in-house mold trials are required to confirm gate-freeze time.

When lower-flow HDPE grades are already qualified, substitutions with Hanwha HDPE 7600 alter viscosity and impact response

Hanwha HDPE 7600 differs from blow-molding and blown-film HDPE primarily in molecular weight, melt strength, and shear viscosity. Blow-molding grades with melt index 0.2–0.8 g/10 min provide the parison hang time required for extrusion blow molding; 7600 sags excessively under its own weight and cannot maintain a uniform parison wall. Blown-film grades with melt index 0.5–1.0 g/10 min sustain a stable bubble at blow-up ratios above 2:1; 7600 lacks the melt strength to resist bubble instability at those conditions. Compared with bimodal PE100 pipe grades classified under ISO 12162:2023, the injection-molding grade does not possess the slow crack-growth resistance required for hydrostatic pressure service, and no PE100 rating is claimed for 7600.

Within injection-molding HDPE, the high melt index of 7600 reduces fill pressure and screw recovery time relative to lower-flow grades of 2.0–4.0 g/10 min. The trade-off is lower tensile elongation at break and notched Izod impact. For load-bearing crates, tote boxes, and pallets where drop-impact or wide-temperature toughness is controlling, a lower-flow grade with higher molecular weight is generally specified. The choice between 7600 and a lower-flow grade should be based on part strain, service temperature, chemical contact, and impact requirements, not on melt index alone.

Regulatory documentation, migration limits, and outdoor service restrictions

Standard Hanwha HDPE 7600 is manufactured to permit use in food-contact articles under FDA 21 CFR 177.1520(c), provided that the finished article complies with the migration and end-use conditions set forth in that section. In the European Union, finished plastic materials and articles are controlled under Regulation (EU) No 10/2011; the overall migration limit is 10 mg/dm², and any dual-use additives must be listed in the Union list with specific migration limits or be excluded by functional barrier provisions. REACH compliance is addressed under Regulation (EC) No 1907/2006; the polymer itself is exempt from registration as a polymer, but the monomers and additives from which it is formulated must be registered or authorized as applicable for the EU supply chain.

For electrical and electronic equipment within the scope of Directive 2011/65/EU, standard 7600 is not expected to contain cadmium above 0.01 wt%, or lead, mercury, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers above 0.1 wt%. These values are homogeneous-material limits and should be confirmed with lot-level testing when RoHS compliance is a condition of supply.

The standard grade is not UV-stabilized for continuous outdoor exposure. Unpigmented articles exposed outdoors can exhibit surface chalking and tensile-strength loss within 6–12 months in temperate climates, depending on thickness and orientation. Outdoor service requires 2–3 wt% of a well-dispersed carbon black masterbatch or a UV-stabilized variant, with property retention evaluated according to ASTM D638-22 after accelerated weathering under ISO 4892-2:2013. Hanwha HDPE 7600 should not be used for continuous hot-water pressure service at 60 °C or above because it lacks the hydrostatic strength classification of PE100 under ISO 12162:2023. Contact with strong oxidizing acids, chlorinated solvents, or aggressive surfactant systems is not recommended unless the part is stress-relieved and chemical resistance is confirmed by ASTM D543-21 or ISO 22088-3:2006.

In high-cavitation cap and closure tools, the high melt-flow of Hanwha HDPE 7600 is observable as lower injection pressure and shorter screw-recovery time. On a 32-cavity continuous-thread closure mold with a 0.8 mm wall, processors may record a 15–20% reduction in peak injection pressure relative to a 2.0 g/10 min HDPE at the same melt temperature; however, this observation is press- and tool-specific, and published data for this specific configuration is limited. Cavity-pressure transducers should be used to verify gate-seal time and to prevent excessive hold pressure from creating residual stress at the cap threads. Clean edge trim and regrind levels up to 2–4% are generally accepted, but the feed zone can slip when fine powder is combined with low back pressure and high screw rotation speed; constant regrind particle size is therefore required for stable recovery.

Molded strain in the thread root must be controlled through part design and cooling-channel placement; stress cracking in 100% nonylphenol ethoxylate solutions at 50 °C is a practical screening test because the grade does not carry an ESCR-critical rating. When chemical exposure is expected, the part should be tested in the intended packaged formulation rather than using generic compatibility tables.