Bada AG BADAFLEX® SEBS-Comp. TPE-S 75A 1967 is a thermoplastic elastomer compound based on a selectively hydrogenated styrene-ethylene/butylene-styrene block copolymer. The suffix 75A identifies a nominal hardness of 75 Shore A under ISO 7619-1; the 1967 code is an internal series marker and does not by itself define filler type, oil content, or lot-specific rheology. Published compositional detail for this specific configuration is limited, but the product class typically comprises SEBS triblock copolymer, paraffinic or naphthenic process oil, polyolefin modifier, and a stabilizer package. The saturated ethylene/butylene midblock is the primary structural difference from SBS-based TPE-S compounds: the absence of main-chain unsaturation reduces autoxidation and UV-induced embrittlement in service.

Within the 75 Shore A hardness class, the grade is used for parts requiring elastic recovery, low-temperature flexibility, and thermoplastic re-processability. Because the material belongs to the TPE-S category, melt processing is possible on conventional thermoplastic injection-moulding and extrusion equipment; thermoset curing, sulfur crosslinking, or peroxide cure systems are not required. The absence of a vulcanization stage distinguishes it from rubber compounds and TPV products, reducing cycle time and permitting controlled regrind reuse.

At the morphological level, the SEBS block copolymer forms a microphase-separated network in which polystyrene end-blocks act as physical crosslinks. This network is thermoreversible; heating above the styrene glass transition softens the structure and permits melt flow, while cooling restores elasticity. The ethylene/butylene midblock provides a low-temperature loss peak generally between -50 and -40 °C, while the styrene-rich phase transition occurs near 90–100 °C. Because the physical crosslinks are reversible, the material cannot match thermoset rubber or a well-vulcanized TPV for high-temperature creep resistance and compression set above 100 °C. This structural constraint drives most substitution decisions.

What mechanical and thermal boundaries are associated with a 75 Shore A SEBS compound?

Table 1 presents representative physical property ranges for commercial 75 Shore A SEBS TPE-S compounds. The ranges are not a substitute for the Bada AG certificate of analysis because filler selection, oil molecular weight, and stabilizer loading can shift individual values. Hardness tolerance across production lots is commonly controlled within ±3 Shore A.

The tensile and tear ranges shown above correspond to SEBS compounds with moderate oil content and no reinforcing filler. If a candidate application specifies tensile strength above 12 MPa or tear strength above 35 kN/m under ISO 37 or ISO 34-1, a harder SEBS grade, a TPU, or a filled TPV should be evaluated instead. Compression set testing at 70 °C is a more discriminating quality indicator for sealing applications than room-temperature set, because the ethylene/butylene midblock softens at elevated temperature and exhibits time-dependent stress relaxation. At ambient temperature, low-strain recovery is rapid; after 70 h at 70 °C, residual set rises into the 35–55 % range, which limits continuous use in high-compression dynamic seals.

The practical low-temperature service limit is generally between -40 and -50 °C for thin-section parts, depending on oil content and deformation rate. The upper continuous service temperature for a 75 Shore A SEBS TPE-S compound is typically 100 °C; short excursions to 120 °C may be tolerated only if the part is not under continuous compressive load and if stabilizer content is adequate. Heat aging should be assessed by ISO 188 at 100 °C for 168 h rather than by visual color change alone. Published data for this specific configuration is limited, and long-term heat aging must be confirmed on the final production lot.

Before production, melt flow rate should be measured under ISO 1133-1:2022 at 230 °C and 5 kg as a batch-release check. Commercial 75 Shore A SEBS TPE-S compounds typically fall between 5 and 30 g/10 min, but this value is not an intrinsic quality target because filler and oil compounding shift viscosity. A change of more than 15 % from an approved lot should trigger review of residence time, drying conditions, and regrind content.

Pre-drying at 70–80 °C for 2–4 h is recommended when pellet moisture exceeds 0.05 wt% or when ambient relative humidity exceeds 60 %. Although SEBS itself is hydrophobic, the process oil and any mineral filler can carry moisture that produces splay, surface channels, and inconsistent gloss in injection-moulded parts. Desiccant dryers with a dew point of -20 °C or lower are preferred; hot-air hopper dryers are acceptable only if residence time is tightly controlled to prevent oil migration and pellet agglomeration.

Injection moulding start-up parameters for a 75 Shore A SEBS compound usually fall within a melt-temperature range of 180–230 °C, with the lower portion of the range used for thick sections and the upper portion for thin-wall flow lengths. Mould temperature should be maintained at 20–50 °C; surface gloss, adhesion to PP inserts, and fill precision degrade when the cavity wall drops below 20 °C. Injection velocity should be selected to produce a short fill time without jetting, and hold pressure is normally 30–60 % of peak injection pressure. Melt temperatures above 240 °C can initiate viscosity drift and yellowing; residence time should be kept below 10 min at the upper end of the melt-temperature window. If the melt pool is left idle for more than 10 min, the first several shots should be discarded because yellowing and viscosity shift occur preferentially in the stagnant boundary layer.

For extrusion and compounding, general-purpose polyolefin screw geometry with L/D between 24:1 and 30:1 and compression ratio between 2.5:1 and 3.5:1 is adequate. High-shear mixing is not required; excessive shear heating in a twin-screw extruder above 250 °C can cause post-extrusion surface defects and stabilizer depletion. Purging with low-flow polypropylene or polyethylene is effective when transitioning from PA, PET, or TPU melts, provided the machine is flushed until purge melt appears clear and viscosity returns to the expected band. Gate design should avoid small pin gates with excessively high shear. Tab, fan, or diaphragm gates with a land thickness of 0.5–1.0 mm provide lower pressure loss and reduce shear heating. Hot-runner systems can be used if the manifold is designed for shear-sensitive TPE and free of dead spots; hot-runner temperatures should not exceed 230 °C.

Lot-release testing should include hardness, density, melt flow rate, tensile strength, elongation at break, tear strength, and compression set. Fourier transform infrared spectroscopy or differential scanning calorimetry can confirm backbone identity and styrene content; a significant shift in styrene glass transition or melt viscosity indicates lot drift. For medical or food-contact applications, extractables and leachables risk assessment should include HPLC or GC-MS analysis after simulated use.

When this SEBS grade replaces SBS, TPU, or TPV in multicomponent assemblies

Against SBS-based TPE-S compounds of the same hardness, the Bada AG SEBS product exhibits a measurable advantage in heat and UV resistance because the saturated ethylene/butylene midblock does not contain the double-bond sites that drive oxidative chain scission. Comparative oven ageing under ISO 188 at 100 °C for 168 h generally shows lower hardness drift and better elongation retention for SEBS systems. This substitution is appropriate for outdoor soft-touch grips, window encapsulations, and automotive interior parts that must pass extended heat aging; it is not justified solely on cost, because SEBS grades typically carry a higher raw-material cost than SBS equivalents.

Compared with a 75 Shore A thermoplastic polyurethane, the SEBS compound has lower density, typically 1.10–1.20 g/cm³ versus 1.15–1.25 g/cm³ for TPU, which reduces part weight when multiplied across high-cavity production. It also provides superior hydrolytic stability in warm-water environments; ester-based TPU can undergo chain scission after prolonged immersion at 60–80 °C, whereas SEBS does not rely on hydrolytically sensitive ester linkages. The trade-off is lower tensile strength and abrasion resistance. Applications requiring DIN 53516 abrasion loss below 50 mm³ or tensile strength above 12 MPa generally warrant TPU, not TPE-S.

Relative to dynamically vulcanized TPV products based on PP/EPDM, a 75 Shore A SEBS compound usually offers better colorability, lower density, and a softer surface touch, but it will not match the high-temperature compression set and oil resistance of a well-formulated TPV. For static seals below 70 °C, the SEBS grade can be used; for dynamic seals exposed to hot engine oil or continuous temperature above 100 °C, an EPDM-based TPV or solid silicone should be considered. Selection should be made on the basis of ISO 815 compression set, ISO 1817 volume change in test fluids, and ISO 188 heat aging, not on Shore A hardness alone.

In two-component injection moulding, adhesion to PP and PE substrates is generally strong when the substrate surface reaches 40–80 °C at the interface; bonding to PC/ABS is not intrinsic and usually requires mechanical interlock, surface activation, or a tie layer. The grade can be considered for soft-touch grips, seals, gaskets, protective covers, consumer goods, and medical device components only where the final article passes application-specific performance testing. For grips, abrasion resistance should be tested by DIN 53516; for sealing applications, compression set after 70 h at 70 °C per ISO 815 is mandatory. For medical devices, cytotoxicity should be established by ISO 10993-5 with extraction according to the intended contact duration and ratio.

Chemical resistance follows the expected SEBS profile. The compound is not recommended for continuous immersion in aromatic hydrocarbons, chlorinated solvents, ketones, esters, or strong oxidizing acids. Short-term contact with dilute aqueous acids and bases is generally tolerated at room temperature. Volume change in test fluids should be measured by ISO 1817 for 72 h at the expected service temperature; volume swell above 30 % typically indicates loss of dimensional stability and mechanical properties. If a part must withstand contact with aliphatic mineral oil or grease, an NBR/TPV or TPU should be selected instead.

Formulators should avoid adding peroxide crosslinking agents or sulfur cure packages because the saturated midblock will not undergo conventional sulfur curing; such additions create extractable by-products without meaningful property gain. Amine-based additives should be evaluated for interaction with the stabilizer system before plant trials. Reprocessing is possible at up to 20–30 % regrind in non-appearance parts, provided the regrind is dry and free of contamination. Higher regrind fractions may reduce tensile elongation and surface consistency, especially in light colors.

Finished-part performance should include tear propagation testing on notched specimens, because Shore A hardness alone does not predict tear resistance in thin-wall cross-sections. For snap-fit features, permanent set after repeated deflection should be tested using a custom fixture that simulates 10⁵ cycles at the service temperature; no universal ISO method exists for snap-fit fatigue in TPE-S, but ISO 3384 stress relaxation can provide comparative data. Outdoor applications require UV-stabilized black or pigmented versions. Natural or light-colour grades may require additional UV packages tested by ISO 4892-2 or ASTM G154 for the intended exposure class. Colour consistency across lots should be verified by spectrophotometric ΔE measurements under D65/10° conditions; published data for this specific configuration is limited.

Regulatory documentation must be verified before food-contact or medical submission

Conformity statements for this specific Bada AG grade must be obtained from the supplier. Table 2 lists the standard documentation commonly requested for SEBS TPE-S compounds in regulated applications; it does not confirm that grade 1967 meets all thresholds.

For EU food-contact assessment, overall migration is measured in food simulants A, B, D2, or E according to the intended food category under EN 1186 migration test methods. The overall migration limit of 10 mg/dm² applies; specific migration limits apply to process oil and antioxidant components. For fatty foods, a low-migration paraffinic oil is required. For FDA 21 CFR 177.1810, the polymer itself may be recognized, but end-use extraction limits depend on food type and temperature. The designation 1967 should not be interpreted as a food-contact, medical-grade, or drinking-water approval without a written statement from Bada AG.

If medical use is intended, the material must be evaluated not only for cytotoxicity under ISO 10993-5 but also for sensitization, irritation, and systemic effects according to ISO 10993-1. Raw material data cannot replace device-level biocompatibility testing on the final geometry, material combination, and sterilization cycle. For electrical and electronic applications, RoHS 2011/65/EU screening is usually performed by XRF or ICP on selected lots, but the supplier’s written declaration is required for batch-level evidence. The absence of high-risk substances in the formulation is not equivalent to a certification unless documented under the applicable regulatory scheme.