Hifax Sequel 1980 FP BLK is a reactor-grade thermoplastic polyolefin (TPO) supplied as black, free-flowing pellets. It is built on a heterophasic polypropylene copolymer backbone in which an ethylene-propylene rubber (EPR) phase is generated directly in the polymerisation cascade, giving the material a balance of high melt fluidity, controlled linear thermal expansion, and impact resistance well below 0 °C. The suffix “BLK” denotes a pre-dispersed carbon black masterbatch, delivering integral UV stability and a uniform jet-black appearance without post-compounding. This grade is configured for injection-moulded automotive semi-structural and appearance parts where thin-wall geometry, low warpage, and system-cost reduction compared to engineering thermoplastics are the primary design drivers.
What Separates In-Reactor TPOs from Melt-Blended Impact Copolymers?
The defining feature of the Sequel 1980 FP architecture is the morphology locked in during sequential gas-phase and bulk polymerisation. Unlike melt-compounded impact copolymers, where EPR domains are dispersed by twin-screw extrusion and typically exhibit a broad, co-continuous size distribution, the in-reactor route yields a bimodal particle population with primary domain diameters in the range 0.3–0.7 µm and a secondary population below 0.2 µm, as observed by transmission electron microscopy after RuO4 staining. The total rubber fraction, determined by temperature-rising elution fractionation, sits at 25–28 wt%. This microstructure translates into a sharp ductile-to-brittle transition well below −40 °C while maintaining a flexural modulus above 1700 MPa (ISO 178). Melt-blended TPOs of equivalent stiffness typically require 5–8 wt% higher rubber loading to approach the same low-temperature notched impact energy, incurring a penalty in heat deflection temperature and surface hardness. The narrower particle size dispersion also reduces shear-induced agglomeration inside hot-runner nozzles, a failure mode that can cause streaking and intermittently reduced elongation at break in painted components.
Melt Rheology and Crystallisation Kinetics Under High-Shear Injection
Flow behaviour is characterised by a melt volume-flow rate of 28 cm³/10 min (ISO 1133-1, 230 °C, 2.16 kg) and a pseudoplasticity index such that apparent viscosity at 1000 s⁻¹ is approximately 60 Pa·s at 240 °C. This high fluidity enables filling of ribs with a thickness of 1.2 mm over a flow length exceeding 800 mm at a melt temperature of 245 °C and an injection speed of 80 mm/s on a 2500 kN hydraulic clamp. Fast solidification is driven by a nucleated PP homopolymer matrix; isothermal DSC at 120 °C reveals a crystallisation half-time of 6–8 s, permitting a total cycle time of 22–28 s for a 2.0 mm nominal wall thickness when using a mould temperature of 40 °C. Freeze-off at the gate occurs within 1.5 s of hold-pressure transition, requiring that the switchover position be set by screw-cushion decay rather than timer to ensure consistent packing. Operators report that barrel residence times exceeding 8 minutes at the upper temperature limit of 250 °C induce enough chain scission to lower notched Izod impact by 12–15 %; therefore, shot size should utilise at least 40 % of the barrel capacity.
For uncoated exterior black components, the carbon black masterbatch provides a UV screening factor such that the base polymer at 2.5 mm depth experiences less than 1 % of incident 300–380 nm radiation. Accelerated weathering per SAE J2527 with a Type S borosilicate inner-outer filter combination and a 0.55 W/m² irradiance at 340 nm yields a ΔE colour shift below 3.0 after 1500 kJ/m². Long-term thermal stabilisation is provided by a synergistic combination of a high-molecular-weight hindered amine light stabiliser (HALS) and a hindered phenolic primary antioxidant; oven ageing at 150 °C per ISO 188 retains 70 % of the original tensile elongation at break after 1000 h. Interior VOC and fogging behaviour has been assessed according to VDA 278 and DIN 75201, with fogging reflectance above 90 % and total VOC emission below 80 µg/g, making the grade suitable for instrument panel substrate applications where condensate on the windscreen is a regulated criterion.
When Replacing ABS in Instrument Panel Retainers: Processing Adjustments and Shrinkage Tolerance
Direct substitution of ABS with Hifax Sequel 1980 FP BLK for a structural instrument-panel retainer imposes a mould-shrinkage differential that must be accommodated. The copolymer exhibits a linear mould shrinkage of 1.1–1.3 % (ISO 294-4, parallel to flow) compared with 0.5–0.7 % for a typical heat-resistant ABS. Existing tooling cut to ABS shrinkage will therefore produce a dimensionally oversize part; steel-safe modifications and additional hold-pressure profiling are required. A hold pressure of 40–50 MPa (hydraulic) applied for 6–8 s across a pin-gated design reduces post-mould warpage to below 0.8 mm over a 600 mm span. Density advantage is 0.98 g/cm³ versus 1.05 g/cm³ for ABS, delivering a mass reduction of roughly 7 % that contributes to fuel-efficiency targets. Surface scratch visibility must be managed: an Erichsen scratch test with a 1.0 mm hemispherical stylus at 10 N load produces a ΔL of 1.2–1.5 on a grain depth of 30 µm (VDI 3400 texture No. 24). Finer grain patterns may reveal stress whitening around the scratch due to micro-cavitation of the EPR phase; design studios therefore specify a grain geometry with a minimum radius of 15 µm at the trough to suppress light scattering.
| Property | Standard | Sequel 1980 FP BLK | Std PP Impact Copolymer | Melt-Compounded TPO |
|---|---|---|---|---|
| Melt volume-flow rate | ISO 1133-1 (230 °C,2.16 kg) | 28 cm³/10 min | 12–15 cm³/10 min | 18–22 cm³/10 min |
| Flexural modulus | ISO 178 | 1800 MPa | 1300 MPa | 1400 MPa |
| Tensile yield stress | ISO 527-2 | 27 MPa | 25 MPa | 22 MPa |
| Notched Charpy impact at 23 °C | ISO 179-1/1eA | 30 kJ/m² | 8–10 kJ/m² | 25 kJ/m² |
| Notched Charpy impact at −30 °C | ISO 179-1/1eA | 7 kJ/m² | 3–4 kJ/m² | 6 kJ/m² |
| HDT (0.45 MPa) | ISO 75-2 | 95 °C | 85 °C | 80 °C |
| CLTE, flow direction (−30 to +80 °C) | ISO 11359-2 | 80×10⁻⁶ K⁻¹ | 100×10⁻⁶ K⁻¹ | 90×10⁻⁶ K⁻¹ |
For parts requiring paint adhesion, surface preparation is essential because polypropylene copolymer surfaces arrive with a dispersive energy component of approximately 30–32 mN/m. Activation to a polar contribution of at least 8 mN/m, yielding a total surface energy above 40 mN/m, is necessary before application of a waterborne polyolefin adhesion promoter. Flame treatment using a propane-air mixture at an equivalence ratio of 0.95, with a treatment speed of 150 mm/s and a conical burner distance of 8 mm, has been validated to raise surface oxygen content to 12–15 at% as quantified by X-ray photoelectron spectroscopy. Alternatively, a blown-arc plasma at 500 W output, with a 10 mm gap and a traverse rate of 100 mm/s, produces comparable wettability. After coating with a 2K polyurethane topcoat, adhesion is evaluated per ISO 2409 cross-cut after a 240-hour water soak at 40 °C; a rating of Gt0 is achievable when pre-treatment parameters are maintained within the stated window. Delamination failure traced to insufficient activation manifests as blistering along the polymer-coating interface, identifiable by scanning acoustic microscopy.
Long-Term Thermal Durability and Underhood Compatibility Boundaries
The grade carries a Relative Thermal Index of 110 °C for mechanical impact (UL 746B, generic classification for TPO with this stabiliser package), making it a candidate for underhood components such as cooling-fan shrouds and radiator support brackets. Oxidative induction time at 190 °C exceeds 25 min (ISO 11357-6). After 1000 h of air-oven exposure at 135 °C, notched Charpy impact retention is reported above 60 % of the as-moulded value. Contact with aggressive engine fluids narrows the usage envelope. While immersion in synthetic engine oil (5W-30) at 125 °C for 500 h per ASTM D543 results in a weight swell below 8 % and negligible crazing, prolonged contact with hot ethylene glycol–water mixtures at temperatures above 90 °C can cause environmental stress cracking at moulded-in residual stress concentrations. Therefore, the material is not recommended for integral coolant conduits or thermostat housings. Copper-stabilant heat-transfer salts are tolerated without catalytic degradation, as shown by a 1000 h copper-contact ageing test at 140 °C yielding less than 15 % loss of tensile yield strength.
| Parameter | Range | Preferred Setpoint |
|---|---|---|
| Melt temperature (nozzle) | 220–250 °C | 240 °C |
| Mould temperature | 30–60 °C | 40 °C |
| Injection velocity (screw) | 40–120 mm/s | 80 mm/s |
| Hold pressure (hydraulic) | 30–60 MPa | 45 MPa |
| Hold time | 5–12 s | 8 s |
| Back pressure (hydraulic) | 5–10 MPa | 7 MPa |
| Screw speed | 30–80 rpm | 50 rpm |
| Decompression (suck-back) | 3–5 mm | 4 mm |
| Pre-drying | Not required at ambient RH; at RH > 60%, dry 2 h at 80 °C | |
The black masterbatch introduces a modest anisotropy into the moulding. Carbon black aggregates orient during high-shear filling, producing a weld-line tensile strength reduction of approximately 30 % relative to bulk strength when two flow fronts meet at angles below 45°, as measured by ISO 179-2 on double-gated bars. The weld-line impact factor (defined as the ratio of notched Charpy at the weld to that of the bulk) is typically 0.6–0.7. Mitigation requires raising melt temperature to the upper limit of 250 °C to extend the time available for polymer chain diffusion and positioning gate locations such that weld lines fall in areas of low service stress. Where this is impossible, designers impose an additional safety factor of 2.5 on the local peak principal stress derived from linear-elastic CAE, a value derived from a database of thermographic fatigue tests on similarly pigmented reactor TPOs.
