BADAFLEX® SEBS-Comp. TPE-S 70A 1403LD UV is a UV-stabilised styrenic block copolymer compound supplied by Bada AG for injection moulding, extrusion, and multi-shot overmoulding operations where a nominal 70 Shore A hardness is specified. The material belongs to the TPE-S class defined in ISO 18064:2022, with a styrene–ethylene/butylene–styrene architecture providing physical crosslinking through phase-separated polystyrene domains. The 1403LD UV suffix identifies a low-density production variant carrying a weathering stabiliser package. The grade is characterised by durometer testing under ISO 48-4:2018 or ASTM D2240-15 with a 15 s reading. Published data for this specific configuration is limited in open literature; therefore, the numerical ranges presented below are class-typical for SEBS-based TPE-S at Shore A 70 unless a Bada AG lot certificate is explicitly referenced. The material requires no vulcanisation and can be processed on conventional thermoplastic equipment.

What Distinguishes BADAFLEX® SEBS-Comp. TPE-S 70A 1403LD UV from Non-UV SEBS and Fully Cured TPV?

The ultraviolet stabiliser package in the 1403LD UV variant is intended to delay photo-oxidation of the ethylene/butylene midblock and the onset of surface microcracking. Non-UV SEBS compounds in this hardness class can undergo significant colour shift under xenon arc exposure, whereas UV-stabilised black grades commonly hold ΔE below 3.0 after 500 h at 0.35 W/m² at 340 nm with a black panel temperature of 65 °C in accordance with ISO 4892-2:2013. Compared with fully cured PP/EPDM TPV, the SEBS platform has a lower continuous-use temperature ceiling because the polystyrene endblock glass transition limits dimensional stability in hot environments. A TPV can often sustain static air exposure at 120–135 °C, while SEBS-based compounds are typically restricted to 90 °C or less under continuous mechanical load. The SEBS grade compensates with lower density, typically 0.89–0.95 g/cm³ under ISO 1183-1:2019, better colourability, and easier bonding to styrenic substrates such as PS and ABS. Against flexible PVC, the SEBS compound removes ortho-phthalate plasticiser migration as a failure mode and provides halogen-free composition for disposal or incineration constraints. Against a Shore A 70 TPU, the SEBS material may show lower tensile strength and abrasion resistance, but it avoids ester hydrolysis in hot, humid environments and generally exhibits lower density and improved dielectric stability.

At the processing stage, the grade should be treated as a shear-thinning pseudoplastic rather than a simple viscosity-controlled melt. Published processing guidelines for SEBS TPE-S compounds in this hardness band specify a melt-temperature window of 180–230 °C for injection moulding and 170–210 °C for profile extrusion. If the melt stream exceeds 250 °C, thermal degradation of the styrenic endblock and chain scission of the midblock produce splay, gas nucleation, and permanent loss of mechanical properties. Mould or sizing dies are typically maintained at 20–50 °C. Pre-drying in a desiccant dryer at 70–80 °C for 2–4 h is required after open storage at RH > 60%; the moisture target is <0.05% by ISO 15512. On 25–30 L/D reciprocating-screw injection machines, screw rotation should be limited to 80–120 min⁻¹ for 40 mm screw diameters to prevent excessive shear heating. Production-scale observations show that oversized hot-runner drops and long residence time can yellow natural grades; black UV-stabilised lots are less sensitive. For profile extrusion, a vented barrel with a vacuum of -0.06 MPa is adequate when the feedstock is dry, but splay at the die lip still indicates surface moisture or excessive melt temperature.

When the Grade Is Used in External Sealing Profiles, Compression-Set Data Restrict the Application Envelope

Compression set under ISO 815-1:2019 is the controlling property for seal lips, gaskets, and weatherstrip profiles. Class-typical compression set at 70 h / 23 °C is 20–35%, while the value at 70 h / 70 °C rises to 50–70%. A dynamic seal that must recover after continuous high-temperature compression at 70 °C therefore requires either a lower deflection design or periodic redressing. At 23 °C and 50% deflection, a Shore A 70 SEBS compound can develop a closing force of 5–15 N/cm of lip length, but the result is strongly geometry-dependent. Wall thicknesses below 1.0 mm should be avoided in seals subjected to repeated flex cycles above 10⁵ cycles because fatigue crack propagation can initiate at surface imperfections. For building glazing gaskets, the material is suitable only when the joint movement does not exceed 2–4 mm and when weathering is validated on the actual profile geometry.

Mechanical Property Benchmarks Are Shear-History Dependent and Cannot Be Compared Without Specimen Geometry

Tensile properties for SEBS compounds can only be interpreted when specimen preparation and test speed are fixed. The tensile and tear ranges above follow constant-rate extension at 500 mm/min for injection-moulded plaques conditioned at 23 °C for 72 h. Compression-moulded bars may give lower values. Hardness is not an intrinsic material constant but an indentation resistance measurement after 15 s; immediate readings on a Shore A durometer are typically 2–5 points higher. Melt flow rate measured at 200 °C / 5 kg captures only a single point on the shear-thinning flow curve. Capillary rheometry under ISO 11443 across 50–1000 s⁻¹ is needed to evaluate gate shear stress and hot-runner pressure drop. The presence of a UV stabiliser package can influence surface gloss; a texture depth of VDI 24 or finer may be necessary to avoid visible flow-line contrast on visible exterior surfaces.

With regard to multi-shot overmoulding onto polypropylene or polystyrene, the SEBS compound can form a cohesive melt bond when the substrate surface is activated by flame, corona, or low-pressure plasma. Interfacial adhesion is not guaranteed by melt temperature alone; surface energy should exceed 38 mN/m measured by contact angle according to ISO 19403 or an equivalent method. In overmoulding trials on 40 t rotating-platen machines, cycle-time increases of 10–20% are observed when using a 20 mm screw because SEBS compounds are more shear-sensitive and heat-retentive than rigid PP. The process should use a short cushion of 3–6 mm and back pressure of 2–5 MPa to keep melt density uniform across cavities.

Outdoor Weathering, Xenon Arc Exposure, and Gloss Retention Limits

For exterior automotive or building profiles, weathering validation should follow ISO 4892-2:2013 with daylight filters, 0.35 W/m² at 340 nm, black panel 65 °C, and a 102 / 18 min dry/spray cycle. After 500 h, UV-stabilised dark-coloured SEBS compounds in this class often retain 80–90% of original gloss and exhibit ΔE below 3.0. After 1000 h, light-coloured or thin-walled parts may show chalking, particularly if the titanium dioxide pigment system is not adequately surface-treated. For automotive exterior components, SAE J2527 can be applied with extended daylight filters, but correlation with real Florida exposure remains geometry-dependent. The weathering package is distributed within the SEBS midblock; surface migration under high humidity can be minimised by adequate melt homogenisation, but the grade should not be used for load-bearing exterior skins without part-specific weathering validation on the finished geometry.

Chemical resistance follows the general SEBS pattern. The compound is compatible with water, dilute acids, bases, alcohols, and many glycol-based coolants at room temperature, but it swells strongly in aliphatic and aromatic hydrocarbon fluids. Under ISO 1817:2015 immersion in toluene at 23 °C for 72 h, mass change can exceed 30% for unfilled SEBS compounds, and mechanical properties may drop sharply. The grade is therefore excluded from fuel-wetted, solvent-wetted, or high-aromatic service. Thermo-oxidative resistance in air decreases above 90 °C; continuous exposure at 110 °C for 168 h can increase hardness by 3–5 Shore A points. Candidate applications include exterior trim clips, mirror gaskets, wiring grommets, garden equipment overmoulds, and UV-exposed soft-touch grips, provided each part is validated under its own thermal and UV load. Lot-to-lot variation for melt viscosity should be monitored by ISO 1133-1:2022 and by part mass distribution; unexplained mass variation above 0.5% across cavities typically indicates gate freeze or melt-temperature drift.