Bada AG supplies the BADAFLEX® SEBS-Comp TPE-S 50A 5247 UV 2K S1 as a pelletised thermoplastic styrenic block copolymer compound. Under ISO 18064, the designation TPE-S identifies a styrenic block copolymer family; the SEBS-Comp portion specifies a hydrogenated styrene-butadiene-styrene compound whose saturated ethylene/butylene midblock reduces oxidative degradation compared with unsaturated SBS. The grade code contains 50A, corresponding to a nominal hardness of 50 Shore A when moulded and measured according to ISO 48-4 or ASTM D2240. The 5247 segment is an internal series identifier within the BADAFLEX portfolio. The UV suffix denotes stabilisation for extended light exposure, while 2K S1 indicates a two-component moulding configuration intended for direct adhesion to polyolefinic substrates in multi-shot injection processes. Manufacturer-published product-specific data for this configuration is limited; therefore, property values for tensile strength, elongation at break, tear resistance, compression set, density, and melt viscosity are not represented as grade-specific in this introduction. Validation according to ISO 37, ISO 34-1, ISO 815-1, ISO 1183-1, and ISO 1133-1 is required on production tooling.

What Adhesion Mechanism Operates in Two-Component SEBS Moulding?

Two-component adhesion in a TPE-S 50 Shore A grade is governed by interfacial melt fusion and molecular interdiffusion rather than solvent welding or primer application. When the SEBS compound is injected as the second shot onto a polypropylene or reactor TPO substrate, the molten mass must raise the interface temperature of the first shot sufficiently to permit chain entanglement across the boundary. The ethylene/butylene midblock provides a low-entanglement molecular segment capable of interdiffusion with the polyolefin substrate, while the styrenic end-blocks form physical crosslink domains that reconstitute upon cooling. Published data for this specific BADAFLEX 5247 configuration is limited; general SEBS class behaviour indicates that melt temperatures below 170 °C may produce weak interfacial weld lines, whereas melt temperatures above 240 °C risk thermal degradation of the oil-extended phase. The 2K S1 suffix is understood as the manufacturer’s series marker for polyolefin adhesion; independent peel testing should follow an in-house constant-rate method at 100 mm/min, with failure mode reported as adhesive, cohesive, or mixed. No single global standard fully governs two-component thermoplastic elastomer peel adhesion; reporting should be accompanied by substrate identification, mould temperature, and first-shot surface temperature.

On reciprocating-screw injection moulding machines with screw L/D ratios between 20:1 and 25:1, the melt is prepared through a three-zone screw with a moderately low compression ratio of 2.0:1–2.5:1 to limit shear heating. Barrel settings for SEBS TPE-S 50 Shore A class are typically staged from 160 °C in the feed section to 200–220 °C at the nozzle, with mould temperature held at 25–50 °C. The actual BADAFLEX 5247 parameter set should be derived from supplier trials because the 2K S1 adhesion modifier may shift melt viscosity. Pre-drying is not generally required if pellets are stored in closed containers below 60% relative humidity; when surface condensation is observed, drying at 60–80 °C for 2–4 h is a class-wide practice. For two-component application, the first-shot substrate should be moved in the tool only enough to reposition the core, with interface temperature maintained above 120 °C where possible to prevent premature skin solidification. Injection speed should be moderate to avoid jetting and trapped gas at the end of flow; short-shot studies and cavity pressure monitoring with piezoelectric sensors are recommended. The compound should not be processed with PVC or polar engineering thermoplastics without separation because the olefin-rich matrix can plasticise and lose mechanical integrity.

UV Stabilisation and Accelerated Weathering Test Parameters

Ultraviolet stabilisation in the BADAFLEX TPE-S 50A 5247 UV 2K S1 grade is expected to be based on hindered amine light stabilisers or UV absorbers combined with the saturated SEBS midblock. Saturated midblocks provide inherently better oxidative resistance than unsaturated SBS grades; however, weathering is still influenced by oil type, filler content, pigment, and surface effects. Accelerated weathering should be specified according to ISO 4892-2:2013, Method A, cycle 1, using xenon arc light at 60 W/m² between 300 nm and 400 nm, black-standard temperature 65±3 °C, with 102 min dry and 18 min water spray. Colour change is measured against ISO 105-A02 grey scale and specular gloss per ISO 2813 on plaques moulded under ISO 294-1. Published product-specific weathering data for the 5247 UV configuration are limited; exterior-grade applications should therefore be validated on production colour concentrates and actual tooling surfaces, not on natural pellets alone.

Unlike unsaturated SBS TPE-S grades, the hydrogenated midblock in the SEBS-Comp 5247 configuration resists oxidative embrittlement during outdoor exposure. Compared with TPE-U, the density is lower for a given 50 Shore A hardness, which reduces part weight in high-volume automotive interior or exterior trim. Compared with plasticised PVC, the grade should not require phthalate plasticisers, which simplifies REACH and automotive material declarations. Within the BADAFLEX SEBS range, the 5247 UV 2K S1 configuration differentiates itself from standard 50 Shore A grades by the inclusion of light stabilisation and the two-component adhesion package. The S1 designation indicates a modified soft-phase composition for direct polyolefin bonding in multi-shot injection moulding, whereas standard 50 Shore A grades may require mechanical anchoring or surface treatment. These distinctions are based on supplier naming logic and class-level SEBS formulation chemistry rather than product-specific numerical data.

When Multi-Cavity Tooling Demands Balanced Flow and Skin Layer Integrity

When multi-cavity tooling demands balanced flow and skin layer integrity, the thermal shear history must be controlled to prevent surface delamination and gate blush in SEBS-based TPE-S 50 Shore A compounds. SEBS melts are pseudoplastic; viscosity decreases with increasing shear rate. Class-level capillary rheometry at 200 °C shows shear-thinning behaviour typical of oil-extended SEBS, with apparent viscosity possibly ranging from 80 Pa·s to 200 Pa·s at 1000 s⁻¹, but product-specific data for BADAFLEX 5247 UV 2K S1 are not published. Mould filling should use a short first-stage pressure and controlled holding pressure to avoid flash. Gate designs should use direct or fan gates with a minimum depth of 0.8 mm for soft 50 Shore A grades; tunnel gates may create high shear and surface roughness. The two-component interface should be located away from knit lines, as trapped air can reduce adhesion. Maximum shear rate should be kept below 50,000 s⁻¹ in the gate area for SEBS class; above this threshold, melt fracture or aesthetic defects may appear. On production-scale equipment, hot-runner systems with externally heated manifolds and valve gates are preferred; internally heated hot runners can cause stagnation and gel formation in UV-stabilised compounds.

For service environments involving repeated flexure and contact with polar solvents, the grade should not be specified without stress relaxation and creep data. SEBS TPE-S compounds are olefinic and exhibit broad compatibility with polypropylene and polyethylene, but they can swell in aromatic hydrocarbons, esters, ketones, and chlorinated solvents. The hydrogenated midblock resists attack by ozone and weathering better than SBS, but continuous exposure to hot mineral oil may extract low-molecular-weight processing oils and increase hardness. Continuous service temperature is generally limited to approximately 80 °C for soft styrenic TPEs; above this threshold, compression set under ISO 815-1 may increase. Low-temperature flexibility is typically retained to -40 °C for 50 Shore A SEBS class, but product-specific brittle point is not published. The compound should not be co-moulded with polycarbonate or PMMA without chemical compatibility trials because aromatic structures and residual monomers can migrate to the interface. If post-moulding assembly uses adhesives, surface energy is typically low; corona or plasma treatment may be necessary to raise surface tension above 38 mN/m.

REACH, RoHS, and Food-Contact Compliance Boundaries

The BADAFLEX® SEBS-Comp TPE-S 50A 5247 UV 2K S1 is subject to European REACH Article 33 communication obligations for substances of very high concern present above 0.1 mass %. The grade should be checked against the candidate list current at the date of supply. RoHS 2011/65/EU Annex II restricts lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers; a compliant TPE-S compound of this class should have concentrations below the homogeneous material limits, but a batch-specific compliance declaration from Bada AG is required. For food-contact status, no blanket approval should be assumed. A TPE-S grade may fall under US FDA 21 CFR 177.1810 for styrene block copolymers used in food contact if the formulation meets the specification and end-use extraction testing is completed. For automotive interior applications, VOC and odour requirements according to VDA 278 and VDA 270 should be evaluated. Published data for this specific configuration is limited; pharmaceutical and potable-water-contact use is not supported by the available public documentation.