The compound designated Bada AG BADAFLEX® SEBS-Comp. TPE-S 30D 5116 2K S1 is a styrenic block copolymer thermoplastic elastomer based on a saturated ethylene/butylene midblock. The alphanumeric suffix identifies a nominal hardness of 30 Shore D, a manufacturer-specific series code, a two-component injection moulding indication, and an additional S1 suffix whose exact meaning is not defined in publicly available documentation. SEBS-based TPE-S grades of this hardness fall between soft-touch elastomers and semi-rigid overmoulding compounds, and hardness is normally recorded by ISO 868 or ASTM D2240 with indentation read after 15 s. The saturated midblock differentiates the product from SBS-based TPEs because the absence of main-chain unsaturation reduces the tendency toward ozone attack, thermo-oxidative chain scission, and radical crosslinking during melt processing. Published data for this specific configuration is limited; therefore, load-bearing and regulated-application selections should be confirmed against the current Bada AG technical datasheet rather than inferred from generic SEBS class behaviour.

How Does the Saturated SEBS Midblock Alter Thermo-Oxidative Stability Relative to Unsaturated SBS?

In an unsaturated SBS triblock, the butadiene midblock contains vinyl groups and in-chain double bonds that act as initiation sites for hydroperoxide formation, chain scission, and crosslinking under sustained heat or ultraviolet radiation. SEBS replaces those vulnerable sites with a hydrogenated ethylene/butylene midblock, which shifts degradation toward slower thermo-oxidative chain scission at the styrene/midblock junctions and at tertiary carbon sites. For a compound of 30 Shore D, the higher styrenic content required to reach the Shore D range also raises the hard-domain glass transition temperature; this improves modulus retention at moderate temperature but can increase injection pressure requirements and reduce melt elasticity at the wall. Ageing studies on SEBS compounds commonly use 70 °C or 80 °C dry-heat ovens with tensile retention measured by ISO 37 Type 2 dumbbells at 200 mm/min. The BADAFLEX® grade does not carry off-the-shelf oxidation induction time or retained-tensile data in public literature; competitive comparisons against SBS should therefore be limited to the structural difference in main-chain unsaturation and verified by lot-specific testing.

Hardness at 30 Shore D places the material in the semi-rigid portion of the styrenic TPE range, above conventional SEBS soft-touch grades supplied in the 40–80 Shore A range. Durometer conversions are empirical and unreliable; the original Shore D value should be retained for specification, and cross-scale comparisons are not acceptable for lot release. The property matrix for a SEBS compound of this type is normally constructed from the following methods.

Tensile specimens are conditioned for at least 24 h at 23 °C and 50 % relative humidity before testing; moulded plaques should be cut parallel and perpendicular to flow to detect anisotropy caused by hard-domain orientation. A nominal Shore D value of 30 does not exempt the compound from conditioning, because absorbed ambient moisture and internal stress from two-shot cooling can shift small-strain modulus without altering the durometer reading proportionally. Chemical resistance is also influenced by the oil plasticiser and by the saturated midblock. Contact with non-polar solvents and mineral oils can extract low-molecular-weight oil fractions, resulting in mass loss and hardness increase over time; extraction is measured gravimetrically or by ISO 1407. For repeated food-contact applications, compliance must be evaluated on the final part using Regulation (EU) No 10/2011 or FDA 21 CFR 177.2600 where applicable. No compliance claim is made here for this specific BADAFLEX® grade.

Processing window constraints are not governed by barrel temperature alone

SEBS compounds of Shore D 30 generally process by injection moulding on conventional reciprocating-screw machines, but the high hard-segment content favours a low-compression screw with an L/D ratio of 20:1 to 25:1 and compression ratio of 2.0:1 to 2.6:1. Barrel zone settings class-typical for SEBS are 180–230 °C, with the nozzle held at 190–230 °C; mold temperature is normally 20–50 °C for thin-wall single-shot parts, but a temperature near the upper boundary is used for second-shot adhesion onto polypropylene. Back pressure of 0.5–1.0 MPa is preferred to minimise shear heating while avoiding unmelted pellets. If residence time exceeds 8 min at melt temperature above 240 °C, the probability of chain scission and odour generation increases. The processing window for the BADAFLEX® SEBS-Comp. TPE-S 30D 5116 2K S1 must be confirmed from the manufacturer’s technical datasheet, because colour concentrates or the 2K S1 formulation can lower the thermal stability onset.

Melt-mass-flow rate is recorded according to ISO 1133-1 at the temperature and load specified in the grade datasheet. For SEBS compounds in the Shore D 30 range, comparison of MFR at 230 °C under 2.16 kg and 5.0 kg loads is useful because the flow-rate ratio indicates shear sensitivity. Capillary rheometry at 100 s⁻¹ and 1000 s⁻¹ is preferred for thin-wall 2K filling simulation; published data for this specific configuration is limited, so mold-filling studies should be performed on the production barrel before gate dimensions are fixed. Spiral-flow testing on an injection-moulding machine of 800 kN clamp force with a 2 mm × 10 mm channel provides a direct comparison between candidate lots, but the results are machine-specific and should not be used for inter-plant specification.

During twin-screw compounding of a Shore D 30 SEBS-based TPE-S, oil absorption and dispersion are controlled by screw speed and melt temperature. A corotating twin-screw extruder with L/D ratio between 36:1 and 44:1 is suitable for the SEBS matrix and mineral-oil plasticiser; side-feeding is used for heat-sensitive additives or fillers. Specific energy input is recorded in kWh/kg, and a lower specific energy can reduce chain degradation while requiring longer residence time for homogeneous phase distribution. Lot traceability should be maintained through extrusion because SEBS compound properties shift with oil batch and styrenic block ratio.

Visual and dimensional defects observed on production lines for two-shot SEBS components include gate blush, sink marks over substrate ribs, and interfacial silver streaks. Gate blush is addressed by lowering injection velocity or increasing mold temperature to 40–50 °C. Sink marks are controlled by pack pressure and by placing ribs at least 0.7 mm below the nominal wall. Interfacial silver streaks are most often associated with moisture or with low substrate preheat; a moisture specification of 0.02 % and a substrate surface temperature of 70 °C are practical control points. These process windows are class-typical for SEBS/PP two-component moulding and must be revalidated for the specific BADAFLEX® grade and substrate grade.

Drying is performed in a desiccant dryer at 60–80 °C for 2–3 h when the compound has been stored under uncontrolled warehouse conditions. Although SEBS itself is not hygroscopic, polar additives, black concentrates, or talc fillers used in modified grades can introduce moisture; residual moisture above 0.02 % becomes visible as splay on the surface of a 30 Shore D part and can inhibit interfacial bonding in 2K moulding. A dew-point meter at the dryer outlet should read −30 °C or lower. If the material is supplied in moisture-barrier foil bags, sealed storage is recommended after opening at relative humidity above 60 %.

When a 30 D Hardness Grade Is Selected for Two-Component Overmoulding on Polypropylene

The BADAFLEX® SEBS-Comp. TPE-S 30D 5116 2K S1 designation indicates suitability for two-component processing, but adhesion to a substrate is not an intrinsic material property; it is a process-dependent response of the interface. In polypropylene overmoulding, the PP substrate is moulded first, cooled below its deformation temperature, and then exposed to the second-shot SEBS melt. The substrate temperature at the moment of overmoulding should remain above 70 °C for adequate chain interdiffusion; below that threshold the SEBS surface freezes before penetrating the PP skin layer, producing a weak boundary line that can fail in peel. If the PP substrate is allowed to cool to 30 °C, a higher melt temperature in the range of 220–240 °C may partially compensate, but only within the thermal stability limit of the SEBS compound. Adhesion can be tested on a two-shot plaque by a 180° peel fixture at 50 mm/min or by a modification of ISO 527-2; because no single ISO method defines 2K interfacial bond strength, comparative data across laboratories are not interchangeable.

The gate and runner system is selected from melt-flow behaviour rather than from the Shore D value alone. For a two-shot application, a cold-runner subsystem for the SEBS second component often uses a film gate of 0.5–1.0 mm thickness; gate depth below 0.3 mm can induce premature freeze-off because the compound cools rapidly against a metal substrate. Hold pressure should be set between 40 % and 60 % of peak injection pressure, and gate-seal time should be determined by weight-sorting cavity samples over 0.2 s intervals until weight stabilises. Injection speed is profiled in a medium-high range of 50–150 mm/s for a 2 mm wall; excessive shear above 10,000 s⁻¹ may generate melt temperature spikes at the non-return valve and degrade the styrenic blocks. Clamp force is calculated from the projected area of both shots; a typical two-component tool running this hardness class may require 4–6 kN/cm² of projected area, but the exact value is part-specific.

Differences from other product groups are best stated as property and processing trade-offs. Compared with SBS-based TPE-S, the SEBS structure provides a lower concentration of main-chain unsaturation, which is reflected in improved retention of elongation after hot-air ageing at 70 °C for 168 h; however, SEBS typically has higher melt viscosity at equivalent wall thickness because of greater chain entanglement. Compared with a soft TPU of similar Shore D 30, the SEBS compound normally has lower density measured by ISO 1183-1 and less sensitivity to moisture-induced hydrolysis, but lower abrasion resistance and lower tensile strength. Compared with a TPV, the BADAFLEX® 2K SEBS grade can be processed at lower melt temperatures and may offer better colour consistency in light colours, while compression set at 100 °C may be higher. Comparative claims must be anchored to specific test methods: tensile properties by ISO 37, abrasion by ISO 4649, compression set by ISO 815-1, and density by ISO 1183-1.

Two-Component Adhesion Test Variables and the Absence of a Single ISO Method

Interfacial bond evaluation in a two-shot SEBS/PP part is influenced by substrate surface cleanliness, substrate temperature, second-shot melt temperature, packing pressure, and the thermal gradient across the interface. Common acceptance procedures use a peel sample cut to 25 mm width and separated at 180° at a crosshead speed of 50 mm/min; lap-shear specimens are machined from two-shot plaques and pulled according to the geometry of ISO 527-2, but the recorded force is a system value rather than a material property. In production, destructive tests are supplemented by cross-sectional microscopy at 50× to detect delamination, void formation, or substrate skin-layer fracture. For the BADAFLEX® SEBS-Comp. TPE-S 30D 5116 2K S1, published data for this specific configuration is limited, so processors should establish internal acceptance criteria using the actual mould texture and gate geometry. No conclusion should be drawn from laboratory coupons unless the cooling rate and hold-pressure-time profile match the production tool.

In multicomponent tooling where the soft component is injected second, gate placement is selected at the thickest section of the overmoulded geometry to maintain molecular contact during packing. If the gate is placed at a thin lip edge, premature freeze-off can reduce interfacial strength by 20 % or more compared with a centre-gated patch, although this value is geometry-specific. Ejection force for a 30 Shore D SEBS overmoulded part is lower than for a filled polypropylene but higher than for a 50 Shore A soft-touch grade; draft angles of at least 1.5° on the soft-component cavity are typically specified. The exact grade-specific data should be obtained from the Bada AG technical datasheet before tool design is frozen.