TSRC Taipol^® SEBS 6150 is a linear styrene-ethylene/butylene-styrene block copolymer supplied in dense pellet form. The grade designation 6150 identifies a non-functionalized, medium-styrene hydrogenated SEBS whose hard polystyrene end-blocks form physical crosslinks below the glass transition, allowing re-melt processing without sulfur or peroxide cure. Bound styrene is typically 30 wt%, as determined by the supplier’s Fourier-transform infrared method, and the hydrogenated midblock consists of ethylene-co-1-butene segments with a glass transition near -45 °C under dynamic mechanical analysis at 1 Hz per ISO 6721-1. The difference from unhydrogenated TSRC SBS grades is the absence of the strong trans-1,4-butadiene infrared absorption near 965 cm^-1, confirming that main-chain unsaturation has been reduced to trace levels. Typical property values are summarized below; they are representative and are not specification limits unless converted into lot-specific release criteria on the certificate of analysis.

In a production-scale twin-screw compounding line configured with a 40:1 L/D ratio co-rotating extruder, the grade is fed through gravimetric hoppers at 60–80 kg/h, with barrel setpoints from feed to die of 180 °C, 190 °C, 200 °C, 210 °C and 215 °C. The die plate is maintained at 210 °C because hardblock domain dissolution is incomplete below 190 °C and thermo-oxidative scission accelerates when the melt exceeds 245 °C. Screw speeds below 250 rpm can generate insufficient shear heating; above 500 rpm the measured melt temperature can exceed barrel setpoints by 15–20 °C. Screen packs with 60 mesh filters are used before a strand die having 3 mm nozzles. The water bath is held at 35–45 °C to prevent pellet deformation without overcooling the strand surface.

Drying is required when ambient relative humidity exceeds 60%. A desiccant dryer with a dew point below -30 °C and setpoint of 80 °C for 2 h reduces residual moisture below 0.05% as determined by Karl Fischer titration. Failure to dry the pellets in such conditions produces splay and surface haze in injection-molded plaques of 2 mm thickness when the melt temperature is below 200 °C.

Regulatory declarations for SEBS 6150 are application-dependent. The checklist below summarizes the standards frequently referenced for the grade; each statement must be confirmed against the supplier’s current safety data sheet and product stewardship bulletin.

When SEBS 6150 Replaces SBS in UV-Exposed Automotive Seals

The substitution of the hydrogenated grade for an unhydrogenated styrene-butadiene-styrene material is justified by ozone and ultraviolet exposure data generated under ASTM D1149 and ASTM D4329. In outdoor seal tests, SBS grades develop surface cracking through double-bond oxidation after short ozone exposure, whereas the ethylene/butylene midblock in SEBS 6150 does not support the same chain-cleavage pathway. The remaining difference is not merely surface aesthetics; retention of tensile elongation after accelerated weathering is used as a release criterion. For a 2 mm compression-molded plaque exposed to UV-A at 340 nm and 0.35 W/m² irradiance, SEBS 6150 retains a higher fraction of initial elongation at break than SBS after the same exposure interval when tested to ISO 37. Published data for this specific grade in complex extruded profiles remain limited, so end-use qualification under SAE J1960 or equivalent is recommended before production release.

For outdoor automotive seals, the grade is compounded with polypropylene and paraffinic oil to produce a soft thermoplastic elastomer without crosslinking. The key operational limit is upper service temperature: because physical crosslinks soften above the polystyrene glass transition, sustained load-bearing above 90 °C is not equivalent to a peroxide-cured EPDM. The material therefore substitutes for SBS or lower-performing EPDM in interior and exterior low-tension seal profiles, but not in high-temperature underhood applications.

For two-shot injection molding of olefinic grips, the substrate is typically a polypropylene homopolymer with a melt flow rate of 20–40 g/10 min. Melt temperature for the SEBS 6150 layer is set at 190–220 °C; mold temperature is controlled at 30–60 °C. Clamp force is estimated at 3–5 kN/cm² of projected area, and holding pressure is maintained at 40–60% of the injection pressure. Direct melt adhesion to the polypropylene surface is possible but peel strength is process-sensitive; the addition of 10–20 wt% maleic anhydride-grafted polypropylene to the TPE layer is common where structural adhesion is required. The compatibilizer enhances interfacial entanglement by reducing the interfacial tension between the hard phase and the substrate. Without compatibilizer, peel strength determined by ASTM D903 may remain below 1 N/mm; with 10–20 wt% functionalized PP, values in the range 3–5 N/mm are often obtained, though published data for this specific SEBS grade are limited.

What Limits Oil Extension Above 150 phr in Soft-Touch Compounds?

Oil extension of SEBS 6150 is practiced because the ethylene/butylene midblock absorbs paraffinic white oils without immediate phase separation. On a 40:1 L/D twin-screw extruder, 100 phr of a 40 cSt white oil at 40 °C lowers Shore A hardness from 62 to 18 and reduces tensile strength to 4 MPa when measured to ISO 37. The limiting variable is not only mechanical softening but migration kinetics: above 150 phr oil, the compound may exhibit exudation within 72 h at 70 °C. The paraffinic oil is initially dispersed as a mixed phase; when the midblock reaches saturation and the cooling rate is too low, oil diffuses to the surface and causes visual blooming and inconsistency in Shore A readings. This operational boundary can be shifted by using a higher-molecular-weight SEBS or by crosslinking a portion of the oil phase with a free-radical donor, but such modifications change the re-meltability and should not be assumed for SEBS 6150 without compounding trials.

In low-voltage cable sheathing compounds, SEBS 6150 is used with mineral-filled polypropylene and process oils in formulations tested to IEC 60332-1-2. The hydrogenated midblock provides low-temperature flexibility down to -40 °C as measured by the low-temperature brittleness test of ISO 812. Compared with EPDM-based thermoset sheathing, the SEBS formulation can be stripped and reprocessed; however, the compound does not match the hot-set test performance of a crosslinked EPDM at 200 °C.

Compression Set, Oil Retention, and Upper Service Temperature

SEBS 6150 is selected for consumer grips where short-term service temperature remains below 90 °C. Compression set at 70 °C for 22 h is 25–35% according to ASTM D395; at 100 °C the value increases to 50–60%, which is a known limitation of non-crosslinked styrenic block copolymers. The grade is not resistant to continuous contact with aromatic solvents, chlorinated hydrocarbons, strong mineral acids, or oxidizing media; such exposure swells the midblock and can reduce tensile strength below the original design margin. Regrind ratios up to 20 wt% are common in injection molding when the regrind is dry, free of oil exudate, and not thermally degraded. Above 20 wt% regrind, lot-to-lot variation in melt mass-flow rate can shift the filling pressure by more than 10% and should be tracked with ISO 1133-1.