Dow HDPE 17450N: Datasheet, Typical Applications and Processing Notes

High-density polyethylene resin grade 17450N supplied by Dow is classed as an extrusion blow moulding material for rigid containers in which melt strength, density, and environmental stress crack resistance must be controlled within tight limits. The technical datasheet for the grade should be read as a production-window document: the listed values are typical nominal values that support incoming resin quality checks, but they are not contractual specification limits unless the supplier certificate of analysis states otherwise.

The material is a high-density polyethylene copolymer with a nominal density of 0.945 g/cm³ and a melt flow rate of 0.95 g/10 min at 190 °C/2.16 kg. Moisture absorption in pellet form is low, and the resin is normally processed without pre-drying. If condensation is present after cold outdoor storage, a dehumidified hopper dryer set at 70 °C for 1–2 h is sufficient; the air supply should be kept below 80 °C because pellet surface tack can generate feed-throat bridging.

How the 17450N Datasheet Values Are Verified

The table below lists representative datasheet values and the standards used to generate them. The tensile and flexural data are intended for material selection rather than for product design; finished container performance must be tested on blow-moulded samples with the actual wall thickness and process orientation.

The density of 0.945 g/cm³ is positioned at the lower end of the high-density range. The controlled short-chain branching associated with the comonomer reduces crystallinity enough to improve environmental stress crack resistance while preserving top-load stiffness. A shift of 0.002 g/cm³ in density may be small in absolute terms, but it can indicate an additive or comonomer change that alters stress-crack resistance and bottle drop impact. For incoming quality control, density is measured after conditioning per ISO 1183-1:2019 and should be included in lot release testing.

The melt flow rate test is run by ISO 1133-1:2022 at 190 °C under a 2.16 kg piston load. A single MFR point does not fully describe parison behaviour, but it is useful for tracking thermal history after repeated extrusion. In a converter’s laboratory, the same test can be used on dried regrind to detect shear-induced degradation; an increase of 0.1 g/10 min above the virgin pellet value is often accompanied by a measurable reduction in ESCR.

The notched ESCR test by ASTM D1693 in 100 % Igepal CO-630 at Condition B is a common stress-cracking screen. The F50 value is the time at which 50 % of the specimens fail. Because of the statistical spread inherent in ESCR testing, a development study should use at least 10 plaques per lot and compare failures using a probability plot rather than relying on a single F50 value. The datasheet value of >600 h is a typical pass criterion for household and industrial chemical bottles.

Compliance statements for food-contact applications should be confirmed against FDA 21 CFR 177.1520 and EU Regulation 10/2011. The base resin does not contain intentionally added cadmium, lead, mercury, or hexavalent chromium; however, pigment masterbatch, UV stabilizers, and processing aids can alter the final article’s regulatory status under RoHS and national packaging waste legislation.

Derating the Screw Speed Window by Melt Temperature and Die Pressure

On continuous shuttle blow moulding equipment, the screw speed window is limited by melt pressure and shear heating. A typical starting extruder for 17450N is a grooved-feed screw with an L/D of 24:1 to 30:1 and a compression ratio of 2.5:1 to 3.2:1. The maximum back pressure before the breaker plate should remain below 35 MPa; higher pressure usually indicates an over-tight screen pack, excessive screw speed, or a melt temperature that is too low.

The preferred die melt temperature is 190 °C to 205 °C. Below 170 °C, parison surface roughness and high motor torque can occur because the melt viscosity rises sharply. Above 230 °C, parison hang strength decreases and thermo-oxidative chain scission may begin; oxidation induction time measured by ISO 11357-6 is a sensitive indicator of this damage. A barrel profile that is front-loaded can produce local overheating while the die heater band shows a lower setpoint. Therefore, thermocouple placement in the head should be checked before changing screw speed.

For a 65 mm extruder, the metering zone is typically set at 195–205 °C, and the die head at 195–210 °C. The screw speed is adjusted to match the shuttle cycle time. Large containers often require a screw speed of 35–60 rpm on this barrel size, but the actual speed depends on shot weight and extruder throughput. If the screw speed is increased beyond the plasticating capacity, the melt may arrive at the head with an inhomogeneous temperature profile and produce parison curl.

Parison programming is necessary for containers with height-to-diameter ratios above 2:1. The die gap is modulated from the neck to the tail to compensate for parison sag and blow-up differences. On a 100-point controller, the neck segment may use a die gap of 1.0–1.5 mm, the body segment 1.8–2.3 mm, and the tail pinch-off 0.5–0.8 mm. The final wall thickness in the container chime should remain above 0.70 mm unless the performance specification explicitly allows a lower value.

Mould cooling is a process variable that influences cycle time, warpage, and top load. Aluminium tooling with conformal cooling channels supplied at 8–12 °C is common. Coolant above 15 °C increases cycle time and can shift the final crystallinity in thick sections, reducing top-load stability. The blow air pressure is typically 0.6–1.0 MPa, with high-flow blow pins used to force the parison into the mould corners before the polymer freezes.

Accumulator-head machines require a slower plastication cycle and a fast shot displacement. The fill speed of the accumulator is adjusted so that the melt is not held at high temperature for prolonged periods. A shot-to-shot delay of more than 10 min at 205 °C can change parison weight and should be avoided during sampling. When the line stops, the head should be purged before restarting to remove oxidised resin from stagnant zones.

In blow-moulded containers for liquid detergents, fabric softeners, motor oil, and household chemical concentrates, the grade is selected when the packaged formulation contains moderate stress-cracking agents. A finished bottle qualification does not rely on resin ESCR alone; it combines ASTM D1693 coupon testing, bottle drop impact per ASTM D2463, and top-load or stack-creep evaluation at 40 °C and 70 % relative humidity. The drop test should be performed at -18 °C for products that may be stored in unheated warehouses or transported in winter conditions.

The grade is also used in UN-rated packagings under 1H1 and 1H2 designations. Qualification of the finished container and closure system is conducted according to the applicable dangerous goods transport regulation, such as 49 CFR 178 in the United States or the UN Model Regulations. The resin itself does not confer UN certification; the container design, wall thickness distribution, closure torque, and filling temperature determine the pass/fail result.

For agricultural chemical containers, the UV resistance of the finished article must be considered separately. The base grade without UV stabilizer should not be specified for outdoor service beyond 12 months in high-solar-radiation regions. In multi-layer containers requiring oxygen barrier, EVOH or polyamide barrier layers can be coextruded with 17450N only when anhydride-modified polyolefin tie layers are used. Direct melt contact between HDPE and EVOH or polyamide is not expected to provide consistent interlayer peel strength in production.

In automotive aftermarket packaging, wide-mouth containers with thread finishes require precise parison programming because thread roots are formed at high local blow-up ratios. The neck insert temperature should be kept at 10–15 °C to freeze the finish dimensions; if the neck insert is too warm, the bottle threads may distort during demoulding and cause cap leakage.

Weight Swell, Diameter Swell, and Motor Load in Continuous Shuttle Presses

Parison swell is a primary variable in die tooling design. Weight swell is the ratio of the extruded parison weight per unit length to the weight per unit length calculated from the die gap. Diameter swell is the ratio of the parison outside diameter to the die bushing diameter. For this grade, the low melt flow rate of 0.95 g/10 min favours high weight swell and moderate diameter swell; die gaps must therefore be chosen to avoid an over-thick parison in the centre of the container.

Die land length influences swell. A longer land reduces die swell and improves melt temperature uniformity at the die exit. Land lengths of 12–18 mm for die gaps of 1.2–2.5 mm provide a practical range for containers from 1 L to 20 L. A die insert that is too short can produce a rough parison surface and inconsistent weight distribution around the circumference.

Motor load is monitored at the extruder gearbox. For a 60 mm screw, a sustained increase of >5 A at constant screw speed is a fault indicator for blocked screen packs or feed-area bridging. The use of a 20/40/60 mesh screen pack is common. A 40/60/80 configuration may be used when the melt contains few gels, but finer screens increase pressure drop and are usually unnecessary for blow moulding of containers.

Regrind from flash and rejected containers may be blended with virgin material at up to 30 wt% when the scrap is clean, dry, and generated from the same grade. Higher regrind fractions can lower ESCR and change drop impact. If coloured regrind is mixed into natural resin, the colourant carrier should be a compatible polyethylene; incompatible pigments can create gel-like defects in the parison. The regrind stream should be screened and passed through a metal detector before re-extrusion.

Blow-up ratio should be selected so that the ratio of container width to die diameter remains between 1.8:1 and 2.5:1 for oblong shapes. Excessive blow-up ratios above 3.0:1 create thinning at the pinch-off and reduce top load. A parison that is too wide for the tool can fold during mould closure, producing a visible weld line and a weak section in the container wall.

When Low-Acid Organics Require Stress-Crack Resistance

Environmental stress crack resistance in HDPE is a system property. The coupon test ASTM D1693 uses a notched specimen in a detergent solution, but it does not replicate the residual stresses present in a blow-moulded container. For low-acid organic liquids or surfactant formulations, the container should be tested with the actual packaged liquid at 50 °C and 70 % relative humidity. Through-wall cracking often starts in the bottom chime or at the pinch-off where wall thickness can fall below 0.7 mm. A localised thin section can cause failure even when the resin passes the coupon ESCR test.

In coextruded structures, the HDPE skin layer should not be allowed to starve. A minimum outer layer of 0.5 mm is typically required to preserve stress-crack performance in a three-layer bottle. The barrier layer must be pre-dried when EVOH is used, and the die temperature should remain below 205 °C to reduce tie-layer degradation. Layer interface instability can be detected by mapping wall thickness with an ultrasonic wall-thickness gauge; thickness variation of more than 10 % around the circumference indicates a die-centring or layer-distribution problem.

Oxidative damage caused by repeated processing cycles creates low-molecular-weight species that act as crack initiators. A foul odour at the die, an increase in melt flow rate, or an increase in yellowness index after multiple recycling cycles indicates that the material has been thermally degraded. Before such regrind is used in UN-rated or high-value containers, it should be tested by melt flow rate per ISO 1133-1:2022 and oxidation induction time per ISO 11357-6. If the oxidation induction time falls below an internally established minimum, the scrap should be diverted to less critical applications or discarded.