Bada AG BADAFLEX® SEBS-Comp. TPE-S 20A 1563 is classified under ISO 18064 as a styrene-ethylene-butylene-styrene thermoplastic elastomer compound, designated TPE-S. The nominal hardness 20 Shore A is measured after 15 s at 23 °C on the ISO 868 or ASTM D2240 scale and places this grade in the very low hardness segment of the BADAFLEX SEBS-Comp range. The 1563 suffix is an internal formulation identifier; it does not correspond to a standard ISO designation but distinguishes the specific SEBS/polyolefin, filler, or oil-extended formulation within the manufacturer’s series. The compound is directionally appropriate for seals, gaskets, dampers, grips, and overmoulds where low closing force, haptic compliance, and elastic recovery under low stress are required. It is not intended as a load-bearing engineering plastic, and design calculations must not substitute a harder TPE-S without reassessing tensile and tear envelopes.

Because Bada AG supplies this material against lot-specific certificates of analysis rather than a single open-internet datasheet, exact density, tensile, and rheology values for 1563 must be obtained from the COA. For preliminary feasibility work, commercial SEBS TPE-S materials at 20 Shore A commonly show density in the range 0.87–0.93 g/cm³ under ISO 1183-1, elongation at break above 500% under ISO 37, and tensile strength normally below 6 MPa. These are feasibility values, not acceptance criteria, and should be replaced by the supplier’s certified lot values before tooling release.

The two-phase morphology of a TPE-S compound depends on styrene domains acting as physical crosslinks and an ethylene-butylene midblock providing entropic elasticity. At 20 Shore A, the styrene domain content is relatively low and the formulation may incorporate aliphatic process oil. The thermally reversible domain network permits repeated processing but also imposes lower upper service temperature and higher compression set compared with a vulcanized rubber or crosslinked TPV. The glass transition of the ethylene-butylene midblock is typically below −45 °C, which supports low-temperature flexibility unless a highly crystalline polyolefin continuous phase raises stiffness. Published data for this specific configuration is limited; therefore, end-use qualification should be performed on the finished article.

What Limits the Processing Window for a 20 Shore A SEBS Compound?

The processing window for a 20 Shore A SEBS compound is constrained less by melt temperature than by screw conveying, melt strength, and thermo-oxidative degradation at high shear. On single-screw extruders with L/D 30:1 to 40:1, the feed zone should remain below 160 °C because the soft compound can plasticate against the root of the screw and stall the solid-conveying zone. A low-compression screw with compression ratio 2.0:1 to 2.5:1 and a grooved barrel section are normally specified. Melt temperatures for soft SEBS grades are generally set between 180 °C and 230 °C, but the exact profile for BADAFLEX SEBS-Comp. TPE-S 20A 1563 must be confirmed with Bada AG because it depends on the oil-extension level, polyolefin continuous-phase ratio, and stabilizer package. Above approximately 240 °C, thermo-oxidative chain scission can reduce melt strength enough to cause strand breaks, die drips, or loss of elastic recovery in finished parts. If the compound has been stored under relative humidity above 60%, pre-drying at 70–80 °C for 2–4 h until moisture is below 0.05% is recommended. While SEBS does not hydrolyze like polyester TPU, moisture in highly oil-extended compounds can create splay, surface voids, and intermittent gassing at the die.

In injection molding, a reciprocating-screw machine with a general-purpose polyolefin screw is normally used. The barrel profile is often set from 160 °C at the feed zone to 200 °C at the nozzle, with mold temperature between 20 °C and 50 °C. The injection velocity should be high enough to prevent premature freeze-off in thin sections but not so high that blind ribs trap gas. For typical wall thicknesses of 1.0–3.0 mm, holding pressures of 20–50 MPa may be sufficient; excessive hold pressure on very soft grades can produce flash because the material fills and packs at low viscosity. Hot-runner valve gates require careful selection because soft SEBS compounds can string, drool, or smear at shut-off when the manifold is held above 220 °C. Sprues and runners can be reground at 10–20% addition, but repeated heat exposure may shift hardness upward and raise gel content due to degradation of the oil phase. If visible splay occurs, reduce regrind and verify residual moisture with a loss-on-drying method.

Melt flow rates reported for commercial soft SEBS compounds vary with oil content; no universal MFR value is applicable. The COA should state the melt flow rate under ISO 1133-1:2022 with the specified temperature and load, because the same nominal hardness may be achieved by formulations with very different flow. Capillary rheometry is more useful for tooling simulation; at 200 °C and shear rates around 100 s⁻¹, soft SEBS compounds often display pseudoplastic behavior with apparent viscosity below 1,000 Pa·s. Such values are not a substitute for grade-specific rheology data. Mold shrinkage should be measured according to ISO 294-4. Depending on part thickness, gate geometry, and flow orientation, shrinkage may fall between 0.5% and 1.2%, but the very low hardness and high elongation can mask anisotropic shrinkage if parts are ejected too hot. Dimensional checks should be performed on parts conditioned at 23 °C and 50% relative humidity for at least 24 h.

Comparative Property Profile and Standard Test Indicators

Because the manufacturer’s published data for 1563 is limited in open technical literature, the following table lists typical ranges for commercial SEBS TPE-S at 20 Shore A. They are intended for preliminary screening. The actual lot certificate of analysis governs.

The most critical use-specific values for sealing and grip applications are tensile stress at 100% strain and compression set. A very soft compound may show 100% modulus below 1.5 MPa, which means the seal will not generate high recovery pressure in a deep gland. Compression set after 70 °C/24 h in the range of 35–60% is common for soft SEBS compounds, but part performance depends on groove volume fill, temperature cycle, and closure force. The property should be ordered to ISO 815-1:2019 method B at the actual service temperature, not at a single standard condition.

For weather-exposed parts, the compound’s UV stabilizer package governs retention. Both the SEBS midblock and the process oil are susceptible to oxidative degradation unless appropriate antioxidants or hindered amine stabilizers are present. Outdoor approval should be based on retained tensile properties and color shift after ISO 4892-2 exposure, with a defined maximum change in hardness and elongation. Elongation retention is often more sensitive than hardness to UV and thermal aging in soft SEBS.

When Silicone or TPU Would Be Selected Instead of a 20 Shore A SEBS

SEBS TPE-S at 20 Shore A offers thermoplastic processability and lower density than TPU, but continuous service above 70–80 °C commonly accelerates compression set and oil migration. Silicone rubber remains the appropriate choice in autoclave, hot-water, or oxidative environments above 100 °C. Polyester or polyether TPU is preferred when tear resistance, abrasion, fuel contact, and oil swelling are decisive; TPU density of 1.10–1.25 g/cm³ is substantially higher, so a weight-critical soft part may favor SEBS. Compared with TPV, the SEBS compound can reach lower hardness with smoother surface tactility and higher flow, but TPV typically has lower compression set and better hot-oil resistance because the EPDM phase is crosslinked. Compared with plasticized PVC, SEBS compounds avoid phthalate and low-molecular-weight ester plasticizer concerns and retain low-temperature flexibility, but they may still contain hydrocarbon process oil that can exude under sustained compression or contact with polycarbonate and painted surfaces. Oil migration must be evaluated when the part is assembled against PC/ABS or coated metal because environmental stress cracking and surface fogging may develop.

Within the BADAFLEX SEBS-Comp range, a 20 Shore A grade trades modulus and tear resistance for lower hardness. If load-bearing capacity, abrasion resistance, or fatigue endurance is required, a harder SEBS grade should be evaluated in parallel. In overmoulded parts, bond strength to polypropylene depends on the substrate melt temperature, PP crystallinity, insert temperature, and mold temperature. A mold temperature above 40 °C and adequate host PP melt temperature improve interdiffusion. The SEBS compound should not be selected for prolonged immersion in aromatic hydrocarbons, strong acids, or steam; TPV or silicone should be specified after chemical compatibility testing. For ergonomic parts, coefficient of friction and haptic behavior should be evaluated by ASTM D1894 or a controlled panel study, because softness alone does not define grip performance.

Food-contact, potable-water, and medical uses require end-use qualification. The base styrenic block copolymer may be covered under FDA 21 CFR 177.1810 or the EU EC 10/2011 positive list; however, the compound may contain additives or process oils that are not automatically cleared. Migration testing according to EN 1186 or FDA guidance must be performed on the finished article. Steam sterilization is not recommended for this softness class unless the manufacturer explicitly qualifies the formulation; SEBS often shows unacceptable compression set and dimensional change after repeated autoclave cycles.

On production lines, key incoming QC checks for this grade include Shore A hardness, melt flow rate under ISO 1133-1, density, and residual moisture. Hardness should be recorded after 15 s at 23 °C on a 6 mm plaque according to ISO 868; thin sheets can read harder because of the supporting surface. Hardness variation across a multicavity tool often reflects nonuniform cooling or inconsistent pack pressure. Pitting, soft spots, or surface sharkskin usually point to moisture, oil-rich particles, or gate-induced degradation. Draft angles of 2–5° are recommended for soft and textured surfaces, and air blow-off may be required because the low modulus material can distort during ejection. Storage bags must remain closed away from heat sources, and regrind moisture must be controlled before reuse.