Bada AG BADAFLEX® SEBS-Comp. TPE-S 30A 1020 is introduced for components requiring a nominal hardness of 30 Shore A combined with the melt reprocessability of a styrenic block copolymer. The product belongs to the TPE-S class. Its elastomeric midblock is saturated through hydrogenation; this structural feature reduces oxidative chain scission and crosslinking relative to unhydrogenated SBS compounds, especially under prolonged UV exposure and intermittent heat. The material is supplied in standard pellets suited to desiccant or hot-air drying and to volumetric or gravimetric feeding on injection moulding machines and single-screw extruders. The grade is manufactured as a compound, not as a pure SEBS polymer, meaning that processing oils, stabilizer packages, and possibly mineral fillers are already incorporated; this shifts melt rheology and surface tack from the base resin and must be considered when qualifying alternate sources. Colour concentrates for low-hardness compounds should be selected with matched styrenic or olefinic carriers, because high-melting masterbatch vehicles can increase local hardness and produce visible specking. At this hardness, measurement of penetration depth and tensile set is strongly influenced by specimen thickness and conditioning; comparison should therefore be made only using identical sample preparation.

What Separates This SEBS Compound from SBS and TPV Alternatives?

One structural distinction is the saturated aliphatic midblock. In unsaturated SBS, the polybutadiene segment contains double bonds that act as initiation points for oxidative degradation; accelerated weathering according to ISO 4892-2 generally shows earlier surface cracking and faster loss of elongation for SBS grades than for hydrogenated SEBS formulations of equivalent hardness. The absence of carbon-carbon double bonds also improves resistance to ozone and to many cleaning agents. In comparison with TPV, the TPE-S material contains no vulcanised rubber phase; vulcanization kinetics are absent from the processing operation. That means recompounding of sprues and runners is thermally simpler, and colour change can be performed with standard thermoplastic purging procedures rather than by removal of cured material. TPVs in this hardness range are less common and generally provide lower compression set at elevated temperature; the trade-off is that the SEBS compound usually offers lower melt temperature requirements, better flow in thin-walled sections, and wider acceptance of masterbatch colours. Against TPU, the SEBS compound normally exhibits lower density and better hydrolytic stability, while TPU grades provide higher tensile strength, abrasion resistance, and load-bearing capability. The nominal hardness of 30 Shore A is achieved without the use of high loadings of plasticizer in well-formulated SEBS compounds; over time this reduces the risk of exudation and hardness increase compared with softer PVC or some SBS/TPE compounds.

Hardness, Tensile Response, and Compression Set Under ISO 37

Conditioning for mechanical testing should follow ISO 291 at 23 ± 2 °C and 50 ± 5 % relative humidity. Hardness is measured according to DIN EN ISO 868 on a prepared plaque of sufficient thickness; the nominal value is 30 Shore A, and commercial tolerance is frequently ±3 points for this hardness class. Tensile properties are evaluated according to ISO 37 using type 5A dumbbells and a crosshead speed of 500 mm/min. Typical production-window values for 30 Shore A SEBS compounds fall between 2.0 MPa and 5.0 MPa for tensile stress at break and between 500 % and 800 % for elongation at break. Tear strength measured to ISO 34-1 is commonly in the range 8 kN/m to 15 kN/m. Compression set according to ISO 815-1 after 22 h at room temperature is typically 20 % to 35 %, whereas values after 22 h at 70 °C can reach 45 % to 70 %, reflecting the absence of covalent crosslinks.

Each lot should be assessed against the certificate of analysis. Published data for this specific Bada configuration is limited, and the above windows derive from SEBS compounds of equivalent hardness; grade-specific values take precedence when supplied by the manufacturer.

For hot-runner injection moulding, barrel temperatures are commonly profiled from feed throat 160–180 °C, compression zone 180–200 °C, metering zone 190–210 °C, and nozzle 200–220 °C. Mould temperatures between 15 °C and 45 °C are used for fast cycle time, but when overmoulding onto PP, the higher end of this range improves adhesion. General-purpose three-zone screws with L/D 20–25 and compression ratio 2.0–2.5 are suitable; high-compression screws above 3.0 can generate excessive shear and should be avoided unless a low screw speed is confirmed. Peripheral screw speed is normally kept between 0.1 m/s and 0.3 m/s. Back pressure in the range 2–8 bar is sufficient for homogenization, but higher back pressure combined with long metering zones may raise melt temperature by shear and lead to surface defects. Melt cushion should be maintained at 3–6 mm to keep the screw from bottoming and to provide consistent packing pressure. Valve-gate hot-runner systems can process this low-hardness grade if gate diameters are at least 1.5 mm; smaller gates may produce splay, jetting, or premature gate freeze. Injection speed is set from moderate to high: fill times of 0.5–2.0 s for thin-walled parts are common, but excessively high velocity can trap air in thick sections. Tooling can be mounted in machines with clamp force from 500 kN upward; smaller systems may be acceptable for small parts. For extrusion, single-screw machines with L/D 30–40 and a cooling mandrel or water bath are used; melt temperatures are often 170–200 °C, and die head pressure should be limited to avoid melt fracture. If surface moisture is suspected, pellets can be dried at 60–70 °C for 2–3 h in a desiccant dryer; hot-air drying is acceptable only for short periods because prolonged exposure above 80 °C may cause pellet blocking. Regrind from clean sprues and runners can be added at up to 20 wt% without major property drift; higher fractions, especially at low hardness, may alter surface tack and tensile set. Purging is performed with polyethylene or polypropylene after shutting off the hot-runner manifold to reduce residence time. Production-scale equipment behaviour shows that blocking of vacuum hopper lines and cold feed zones is more likely at high ambient humidity; compressed-air loaders with dry air are preferred when relative humidity exceeds 60 %.

When Overmoulding Onto Polypropylene Without Pretreatment Is Required

Adhesion of SEBS-based TPE to PP occurs through melt diffusion and non-polar compatibility rather than through chemical cure. No primer is generally required for overmoulding onto PP homopolymer or copolymer, provided the PP surface is clean and at a temperature above 60–80 °C at the time of contact. Peel strength measured according to VDI 2019 depends on melt temperature, injection speed, and pack pressure; adhesion typically improves when the TPE melt reaches the PP surface at 200–220 °C and the cavity is packed briefly before cooling. Processing at the lower limit of the melt-temperature window results in a thicker frozen skin and weaker melt-substrate interaction. For polyamide, PC/ABS, or polyester substrates, adhesion is not intrinsic; a two-component primer, plasma activation, or adhesion-modified interlayer is required, and even then published data for this specific grade is limited. Mould surface finishes below VDI 24 reduce ejection difficulty, because low-hardness grades can stick in deep texturing. Ejectors should have broad heads and be positioned away from thin ribs; mechanical extraction can damage the part if surface peel forces exceed the local tear strength.

In low-pressure ergonomic grips, the low Shore A hardness contributes to contact-stress reduction without relying on plasticizer migration; compression force deflection can be checked according to ISO 3386-1 at 25 % deflection. Applications for this hardness class include toothbrush handle inlays, shaver and power-tool soft lies, cable stress-relief sleeves, anti-slip feet, and low-force seals. The material is suited to thin-wall overmoulding where flow length-to-thickness ratios are moderate; in sections above 5 mm void formation can occur if packing pressure is insufficient, so vacuum-vented tools or gas counterpressure are recommended for thick cushions and anti-fatigue matting. Surface quality is affected by gate type and location; submarine gates and tunnel gates can generate shear lines in soft compounds if gate land length exceeds 0.5 mm. For matte finishes, a mould texture of VDI 24–30 is typical; gloss is influenced by mould temperature and packing pressure. Abrasion resistance is moderate compared with TPU; when abrasion is a critical requirement, testing should be performed to ISO 4649 using a reference compound rather than assuming equivalence.

Why Short Contact with Aromatic Solvents Must Be Limited

SEBS compounds are hydrocarbon elastomers and swell in aromatic solvents, esters, ketones, and many mineral-oil-based greases. Volume swell according to ISO 1817 after immersion in aggressive fluids can exceed 100 % depending on temperature and exposure time; seals and gaskets should therefore be restricted to water, dilute acids, dilute bases, or dry environments unless fluid compatibility is tested on finished parts. Alcohols and some glycols are generally less aggressive, but long-term exposure can still extract stabilizers and increase surface hardness. Continuous service in air above 80 °C can accelerate oxidative degradation of the styrenic and aliphatic phases, causing yellowing and loss of elongation; short-term excursions to 100 °C may be tolerated only if the component is not load-bearing. Contact with oxidizing acids, halogenated solvents, and strongly polar solvents should be avoided. The material should not be specified for fuel-contact seals, engine oil seals, or brake fluid seals without specific fluid-immersion qualification to ISO 1817, because failure may occur rapidly.

Because commercial availability of specific compliance statements depends on the lot and the production plant, industrial users should request current REACH SVHC declarations, the RoHS 2011/65/EU certificate for the supplied lot, and a statement on substances of very high concern above 0.1 % w/w under Article 33 of REACH. Food-contact compliance cannot be assumed from the SEBS chemistry alone; only the formal supplier declaration for this specific grade under Regulation (EU) 10/2011 or 21 CFR 177.1640 can justify food-contact use. Medical device qualification requires grade-specific testing to ISO 10993-5 and ISO 10993-10; published data for this specific configuration is limited, and users should not rely on data from other BADAFLEX grades. Storage in sealed containers at ambient temperatures below 40 °C, protected from UV light and moisture, is recommended. If bags are opened in high-humidity environments exceeding 60 % RH, drying at 60–70 °C for 2–3 h reduces surface splay and steam-induced porosity. Pellets should not be left uncovered in pneumatic conveying lines for more than 24 h, because surface moisture absorption and dust accumulation can cause processing defects.