Asahi Kasei Asaprene™ SBS T-420
- Product Name: Asahi Kasei Asaprene™ SBS T-420
- Factroy Site: Yinchuan, Ningxia, China
- Price Inquiry: sales8@ascent-chem.com
- Manufacturer: Ascent Petrochem Holdings Co., Limited
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- Asahi Kasei Asaprene™ SBS T-420 is typically used in formulations when hardness, tensile strength, and melt-flow properties and processing temperature and shear rate must be controlled within specific ranges.
| HS Code | 339568 |
| Grade | Asahi Kasei Asaprene™ SBS T-420 |
| Polymer Type | Styrene-butadiene-styrene block copolymer (SBS) |
| Styrene Content | 40 wt% (typical) |
| Butadiene Content | 60 wt% (typical) |
| Density | 0.94 g/cm³ (typical) |
| Melt Flow Rate | 1.0 g/10 min (typical; 200°C, 5 kg) |
| Shore A Hardness | 90 (typical) |
| Tensile Strength | 20 MPa (typical) |
| Elongation At Break | 700% (typical) |
| Modulus At 300 Percent Elongation | 4.0 MPa (typical) |
| Tear Strength | 35 kN/m (typical) |
| Solution Viscosity | 4.0 Pa·s (typical; 25 wt% in toluene at 25°C) |
| Volatile Matter | ≤0.5 wt% |
| Ash Content | ≤0.1 wt% |
| Appearance | White pellets/crumb |
As an accredited Asahi Kasei Asaprene™ SBS T-420 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Asahi Kasei Asaprene™ SBS T-420 is supplied in 25 kg moisture-resistant bags, typically palletized for industrial handling and storage. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Asahi Kasei Asaprene™ SBS T-420 in sealed original packaging, palletized and secured for ocean shipment. |
| Shipping | Asahi Kasei Asaprene™ SBS T-420 is shipped as solid thermoplastic elastomer pellets in moisture-resistant 25 kg bags or jumbo bags, palletized. It is non-hazardous and not regulated as dangerous goods (no UN number). Store and transport cool, dry, away from direct sunlight, heat, and ignition sources. |
| Storage | Store Asahi Kasei Asaprene™ SBS T-420 in a cool, dry, well-ventilated area, away from direct sunlight, heat, moisture, and ignition sources. Keep in original, closed containers or bags on pallets to prevent contamination and deformation. Avoid prolonged exposure to UV light, ozone, and high temperatures. Maintain stable ambient conditions and follow local regulations and SDS recommendations. |
| Shelf Life | Asahi Kasei Asaprene™ SBS T-420 typically has a 12-month shelf life when stored cool, dry, and in original sealed packaging. |
Compliance matrix typically used for release of SBS-modified paving binders under EN 14023:
| Property | Standard test method | Typical acceptance window |
|---|---|---|
| Ring-and-ball softening point | EN 1427 | ≥ 60 °C for high-modulus traffic categories; lower for soft binder classes |
| Elastic recovery at 25 °C | EN 13398 | ≥ 70% after suitable high-shear digestion |
| Storage stability top/bottom softening point difference | EN 13399 | ≤ 3 °C after 72 h at 163 °C |
| Multiple stress creep recovery Jnr at 3.2 kPa | ASTM D7405 | 0.1–0.5 kPa⁻¹ after RTFO aging, depending on traffic class |
| Bending beam rheometer creep stiffness at -16 °C | EN 14771 | ≤ 300 MPa for low-temperature cracking control, adjustable by climate |
What Controls Loop Tack and Cohesive Failure in Hot-Melt Pressure-Sensitive Adhesive Formulations?
In hot-melt pressure-sensitive adhesives based on Asaprene™ SBS T-420, the tack/cohesion balance is determined by selective resin compatibility: the butadiene midblock is plasticised by low-aniline naphthenic oil and tackified with C5 aliphatic resins, while the polystyrene end-blocks require high-softening-point aromatic or alpha-methyl styrene resins to maintain cohesive strength at 23 °C and 40 °C. A representative starting formulation uses 100 phr SBS T-420, 80–120 phr C5 midblock resin, 40–80 phr aromatic endblock resin, 20–40 phr naphthenic oil, and 0.5–1.0 phr phenolic/phosphite antioxidant. Mixing is performed under nitrogen in a jacketed sigma-blade kneader at 150–170 °C or in a co-rotating twin-screw extruder with L/D 32–44 and barrel temperatures from 130 °C to 170 °C; the unsaturated butadiene segment is prone to oxidative gel formation when residence time exceeds 10 min at 170 °C in air, causing an apparent viscosity increase measurable by ASTM D3236. Coating weight for label and tape substrates is routinely 20–30 g/m², with melt viscosity at 160 °C maintained between 5,000 mPa·s and 20,000 mPa·s for slot-die or roller coating. Pressure-sensitive performance is tested by loop tack per ASTM D6195 or PSTC-101, 180° peel per ASTM D3330, and static shear per ASTM D3654 Procedure A. In T-420 formulations, endblock resin loadings below 40 phr tend to yield acceptable tack but cohesive mode failure after 24 h at 40 °C, while loadings above 80 phr can suppress tack by shifting the styrene-phase glass transition above the test temperature; this shift is measurable by differential scanning calorimetry as a broadening of the tan δ peak near 60–80 °C. The low styrene content of T-420 reduces melt viscosity relative to 40 wt% styrene SBS grades but also lowers the upper service temperature; uncompounded formulations are generally unsuitable for continuous shear exposure above 70 °C. For outdoor label applications, the unsaturated midblock makes the adhesive vulnerable to UV embrittlement unless a UV barrier or overlaminate is present; SEBS or SEPS grades are preferred for direct outdoor UV service.
Industrial coating lines processing T-420 hot melt are sensitive to melt temperature overshoot above 175 °C in flexible heated hoses; the resulting thermal degradation produces gel particles that plug slot-die shims and create visible streaks in the coated film. Filtration through a 100-mesh screen pack upstream of the die is standard, but when gel levels increase, pressure drop across the screen pack rises and requires line stoppage. Batch-to-batch variation in naphthenic oil aniline point below 90 °C alters midblock swelling; if the oil is too aromatic, initial tack improves but shear adhesion under ASTM D3654 is reduced. Solvent-free hot-melt processing supports compliance with EU VOC emission limits for adhesives, but the process operates near the lower explosion limit of volatile tackifier residuals; extraction systems must maintain airborne hydrocarbons below 20% LEL under ATEX 2014/34/EU. Open time and green strength depend on substrate thermal mass: on aluminium panels, the adhesive skin temperature drops faster than on paper facestock, requiring a 5–10 °C higher application temperature; published data for this specific substrate configuration is limited.
When SBS T-420 Replaces Butadiene Rubber in Polystyrene-Rich TPR Compounds, Gate Design Governs Weld-Line Strength
Polystyrene-rich thermoplastic rubber compounds based on Asaprene™ SBS T-420 are prepared on co-rotating twin-screw compounding extruders with L/D 32–40, screw speeds of 250–400 rpm, and barrel temperature settings from 160 °C to 190 °C; the SBS is fed upstream with polystyrene, while white mineral oil is injected downstream through a liquid side-stuffer to control shear heating. In formulations that combine SBS T-420 with general-purpose polystyrene at 35–55 wt%, white oil at 5–15 wt%, and calcium carbonate at 10–30 wt%, the Shore A hardness measured by ASTM D2240 generally falls between 50 A and 75 A, but published data for this specific grade in filled systems is limited, so pilot-scale compounding trials are required to establish the hardness-oil curve. Injection moulding on hydraulic presses with clamp capacities of 120–300 t uses melt temperatures of 170–200 °C and mould temperatures of 20–40 °C; the low styrene content of T-420 reduces viscosity but also narrows the window in which the styrene end-block network re-forms during cooling. Gates with diameters below 1.5 mm or fan gates with insufficient land length freeze prematurely, producing weld lines where tensile strength per ASTM D638 can fall below 60% of the non-weld-line value when mould temperature is below 30 °C. Adding 5–10 wt% of a higher-styrene styrenic block copolymer restores weld-line strength but increases Shore A hardness by 3–5 points and raises melt viscosity, which may require a 10–15 °C increase in injection barrel temperature. Abrasion loss measured by DIN 53516 typically falls in the 150–250 mm³ range for soft TPR compounds, and flex-cut growth is evaluated by ASTM D1052; compounds based on unsaturated SBS T-420 are unsuitable for outdoor or high-ozone service because the butadiene midblock undergoes ozone cracking unless protected by paraffin wax and p-phenylenediamine antiozonants, which are not always compatible with light-coloured mouldings.
Production-scale failure modes include silver streaking and gas porosity when pellet surface moisture exceeds 0.1 wt%; SBS T-420 pellets stored at ambient relative humidity above 60% absorb sufficient water to degrade injection moulding. Pre-drying in a desiccant dryer at 60–70 °C for 2 h with a dew point of -20 °C is recommended before processing. Screw recovery speed should be controlled to maintain a shot cushion of 3–6 mm; excessive shear from high screw rpm raises melt temperature above 220 °C and depolymerises the styrene end-blocks, producing black specks and a 10–20% loss of tensile elongation per ASTM D638. The compound should not remain in a hot barrel at 190 °C for more than 15 min during interruption, because the unsaturated midblock begins to crosslink and the melt viscosity rises above the moulding range. For complex soles with deep gussets, mould flow simulation is used to predict gate freeze timing, but actual weld-line strength must be confirmed by cutting samples along the knit line and testing per ASTM D638.
Bituminous waterproofing membrane compounds employ the same polymer network at higher dosage—typically 8–12 wt% SBS T-420 in oxidised bitumen—to achieve low-temperature flexibility per EN 1109 and heat resistance per EN 1110; mixing follows the high-shear digestion procedure described above, with reduced filler fractions and without traffic-grade MSCR validation.
Solvent-Borne Contact Adhesive Rheology and Open-Time Control
Solvent-borne contact adhesives formulated with Asaprene™ SBS T-420 dissolve the block copolymer in aromatic/aliphatic solvent blends selected to match the solubility parameters of both the styrene end-blocks and the butadiene midblock; typical application solids are 13–18 wt%, with solvent blends containing toluene, cyclohexane, and methyl ethyl ketone adjusted to maintain a Hansen solubility parameter between 8.5 and 9.5 (cal/cm³)^0.5. A high-shear dissolver with jacket cooling is used because polymer solvation is exothermic and solvent vapor must be extracted under ATEX-compliant ventilation; vessel temperature is kept below 35 °C to prevent viscosity drift and premature evaporation of the low-boiling ketone. Rosin ester tackifiers are added at 40–80 phr relative to SBS, and plasticising oils are usually omitted or limited to 5 phr because additional oil reduces green strength too rapidly for load-bearing laminates. Open time is governed by the evaporation profile of the solvent blend: MEK-rich mixtures reduce open time below 5 min, while cyclohexane-rich mixtures extend open time to 10–20 min but may retain solvent in closed-cell foam laminates and cause bubbling. Green strength is measured by 180° peel per ASTM D903 after a 30 min dwell; values of 2–6 N/mm are typical for porous wood and fabric substrates, but published data for T-420 in this exact configuration is limited. The unsaturated butadiene segment requires 0.5–1.0 phr phenolic antioxidant to limit oxidative discolouration in light-coloured laminates, but the bond line should not be exposed continuously to temperatures above 60 °C or to plasticiser migration from flexible PVC, which softens the styrene domains and reduces shear resistance. Application viscosity at 25 °C is controlled between 3,000 mPa·s and 6,000 mPa·s for brush or roller coating; below 2,500 mPa·s the adhesive tends to sag on vertical surfaces, while above 8,000 mPa·s the wet film thickness becomes difficult to control under production conditions.
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- Asahi Kasei Asaprene™ SBS T-420 is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
- COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales8@ascent-chem.com.
Asahi Kasei Asaprene™ SBS T-420 is a linear styrene-butadiene-styrene block copolymer supplied as porous pellets with 30 mass% bound styrene and 0 phr extender oil. In sequential anionic polymerization, the polystyrene end-blocks develop a glass transition in the 90–100 °C range according to ISO 11357-2:2021, while the polybutadiene midblock retains a glass transition near −85 °C. The resulting microphase-separated morphology provides physical crosslinking at service temperature and thermal processability above the polystyrene softening point. Principal application areas include asphalt modification, solvent-borne and hot-melt adhesives, and impact modification of polyolefin and polystyrene compounds. Uncompounded density is approximately 0.94 g/cm³ under ISO 1183-1:2019. Melt mass-flow rate is measured in accordance with ISO 1133-1:2022 at 190 °C with a 2.16 kg load; because the porous pellet geometry and batch molecular weight influence the melt flow value, incoming quality control should compare the certificate of analysis against capillary rheometer shear viscosity at 180 °C and 100 s⁻¹ rather than relying on a single melt flow index.
In compounding, the recommended melt-temperature range is 150–180 °C. Residence time above 200 °C initiates thermo-oxidative chain scission in the polybutadiene midblock, leading to gel formation and loss of cohesive strength. Pellets exposed to ambient humidity above 60% RH should be pre-dried at 60–70 °C for 2–4 h in a desiccant dryer with a dew point below −30 °C before processing in a twin-screw extruder with an L/D ratio of at least 40:1. Hindered phenolic antioxidants are commonly added at 0.1–0.3 phr; amine-based antidegradants should be avoided in light-colored adhesive systems because of contact staining and potential interaction with hydrocarbon tackifiers.
How does the 30 mass% styrene network govern cohesion and melt-viscosity balance?
The 30 mass% styrene level positions T-420 below high-styrene SBS grades in low-strain modulus and melt viscosity, but above lower-styrene or high-diblock grades in room-temperature cohesive strength. In a compression-molded sheet prepared at 160 °C and tested according to ISO 37, uncompounded T-420 typically shows tensile strength above 20 MPa and elongation at break above 700%. Hardness, measured with a Shore A durometer under ISO 7619-1, is generally 65–80 in the uncompounded state. These values are typical for a linear unsaturated midblock triblock with polystyrene domains acting as reinforcing fillers below the polystyrene glass transition. At processing temperatures above the polystyrene softening point, the domain network disassembles and the melt shear-thins; therefore screw speed, barrel temperature, and die pressure are coupled parameters that affect domain re-formation during cooling.
| Property | Test method | Typical value/range |
|---|---|---|
| Bound styrene | ISO 2453 | 30 mass% |
| Uncompounded density | ISO 1183-1:2019 | 0.94 g/cm³ |
| Melt mass-flow rate | ISO 1133-1:2022, 190 °C/2.16 kg | 0.2–1.5 g/10 min extrusion-grade range |
| Shore A hardness | ISO 7619-1 | 65–80 |
| Tensile strength | ISO 37 | >20 MPa |
| Elongation at break | ISO 37 | >700% |
| Total ash | ISO 247:2006 | ≤0.2 mass% |
The principal differentiation from oil-extended SBS grades is that T-420 contains 0 phr extender oil. In comparative hot-melt adhesive evaluations, an oil-free base polymer reduces variability in cleavage peel strength because no mobile oil fraction migrates to the adherend interface during aging at 60 °C for 7 days under ASTM D4498-07 shear-adhesion failure-temperature test conditions. Formulators can add naphthenic, paraffinic, or polybutene oil at levels up to 50 phr if lower Shore A hardness or higher tack is required. In contrast, high-styrene SBS grades with 40–50 mass% styrene require higher melt temperatures, typically 190–210 °C, and produce compounds with higher cohesive strength at elevated temperature but reduced pressure-sensitive tack. Compared with hydrogenated SEBS grades, T-420 retains the unsaturation of the polybutadiene midblock and is therefore not recommended for long-term UV exposure without light stabilizers or opaque pigmentation. Published data for this specific configuration in thin-film outdoor exposure is limited; converter-level accelerated weathering according to ASTM D4329 or ISO 4892-2 is required.
In SBS grade selection, T-420 is distinguished by its combination of 30 mass% bound styrene and low diblock content. High-diblock SBS grades used in low-viscosity adhesives exhibit lower cohesive strength and lower static shear holding power under ASTM D3654. Conversely, high-viscosity, low-flow SBS grades used in bitumen modification may require more intense high-shear dispersion and longer mixing times. T-420 occupies a middle position: sufficient molecular weight for cohesion and asphalt elastic recovery, while remaining dispersible at 170–190 °C. The exact molecular weight is not stated on the technical data sheet; gel permeation chromatography against polystyrene standards in tetrahydrofuran is used internally, but report data for specific molecular weight averages is often limited in public product literature.
Rheological boundaries in asphalt modification and storage stability testing
In paving-grade asphalt modification, Asaprene T-420 is typically dispersed at 2–6 mass% into a penetration-graded bitumen at 170–190 °C using a high-shear rotor-stator mill with a tip speed in the 10–20 m/s range for 60–120 min. The dispersed polystyrene domains remain associated below their glass transition and increase the softening point and elastic recovery of the binder. Ring-and-ball softening point is measured under ASTM D36, penetration under ASTM D5, elastic recovery under ASTM D6084, and storage stability under EN 13399 or ASTM D5892. At 4 mass% T-420 in a 50/70 penetration-grade bitumen, softening point commonly increases from 45–50 °C to 60–75 °C, while the difference in ring-and-ball softening point between top and bottom storage-tube sections should remain below 2.5 °C for stable melt dispersion.
Process conflicts arise when the high-shear mill is operated above 190 °C or when the SBS concentration exceeds 6 mass% in high-viscosity bitumen. Under these conditions, chain scission can generate free-radical species that recombine to form gel bodies; gelation is detected as an increase in filtration pressure through a 200 mesh screen or as an abnormal increase in dynamic viscosity at 135 °C measured by EN 13702. Because T-420 is unsaturated in the polybutadiene midblock, it is less resistant to oxidative aging than hydrogenated SEBS grades; therefore stabilizers such as hindered phenolics or phosphites are added at 0.1–0.3 mass% of polymer in hot climates. Low-temperature flexibility is evaluated by force ductility under EN 13589 or ASTM D6648; long-term oxidative aging of the modified binder is simulated by ASTM D2872 rolling thin-film oven and ASTM D6521 pressure aging vessel protocols.
On a production-scale asphalt blending unit with a 10 m³ vertical tank, dispersion of T-420 is often completed within 120 min at 175 °C using a bottom-entry high-shear mixer; extending mixing beyond 180 min produces no additional softening-point gain and increases the risk of oxidative gelation. The finished binder is transferred to storage at 150–160 °C with slow agitation to prevent phase separation.
In polypropylene or polystyrene impact modification, T-420 is let down at 5–20 mass% using a ZSK 45 twin-screw extruder with an L/D of 40:1, side feeding of the SBS after the polyolefin melt zone, and strand pelletizing. The screw configuration typically uses two kneading blocks downstream of the side feeder to disperse the SBS phase without exceeding 180 °C. Batch-to-batch variance in melt mass-flow rate can shift die pressure by 5–10%; gravimetric feeding and melt-pressure monitoring are therefore used on production lines. Notched Izod impact is measured under ASTM D256 or ISO 180, tensile properties under ASTM D638, and flexural modulus under ASTM D790. The unsaturated midblock provides effective impact modification at low temperature, but outdoor weatherability is lower than for hydrogenated block copolymers unless the compound is protected with UV stabilizers and carbon black at 1–3 mass%.
In solvent-borne adhesive compounding, Asaprene T-420 is dissolved in toluene or a toluene/ethyl acetate mixture at solids contents of 15–25 mass%. Solution viscosity is measured with a Brookfield RVT viscometer according to ISO 2555; viscosity depends on solvent type, solids content, and temperature. Typical tackifier loadings for pressure-sensitive adhesive formulations are 50–120 phr of a hydrogenated rosin ester or C5/C9 hydrocarbon resin. Peel adhesion is evaluated under ASTM D3330/D3330M-04, loop tack under PSTC-16, and static shear holding power under ASTM D3654 or PSTC-107. The absence of extender oil in T-420 reduces plasticizer migration to the adhesive-substrate interface and supports more stable shear adhesion failure temperature in hot-melt formulations.
Hot-melt application lines typically use a melt tank at 150–170 °C with a gear pump, slot-die coater, and nip roll. Viscosity stability at 160 °C over 8 h is measured by ISO 2555; a viscosity drift above 10% indicates oxidative degradation and requires increased stabilizer or lower tank temperature. SBS T-420 based hot-melts are applied at coating weights of 20–60 g/m². Solvent recovery in a closed-loop distillation system with toluene/ethyl acetate demands antioxidant addition at 0.2–0.5 phr before drying. The adhesive film is often cast on a silicone release liner and dried in a forced-air oven at 70–90 °C for 3–5 min; residual solvent under 100 ppm is verified by headspace gas chromatography.
Production-scale experience in hot-melt adhesive lines indicates that lot-to-lot melt viscosity changes within the manufacturer specification can shift gear pump back-pressure by 0.5–1.5 MPa; therefore PID controllers on melt pumps and slot-die internal deckles should be tuned to accept a narrow viscosity window. A root-cause failure mode observed on twin-screw lines is localized overheating at the die lip above 200 °C, which produces oxidized gel specks in the adhesive film. This is corrected by reducing screw speed from 400 rpm to 300 rpm or by installing static mixers with larger clearances.
When toluene is replaced by cyclohexane in solution viscosity measurement
Solution viscosity values for SBS T-420 are solvent-specific and cannot be compared across different solvent systems without correcting for the polymer-solvent interaction parameter. A 20 mass% solution in toluene at 25 °C measured on a Brookfield RVT at 20 rpm typically produces a viscosity in the 1000–5000 mPa·s range for a linear SBS of this molecular weight; replacement of toluene with cyclohexane changes hydrodynamic volume and can lower the measured viscosity, while methyl ethyl ketone addition above 30 volume% can induce turbidity or precipitation due to selective solvation of the polystyrene domains. The same lot should be characterized by an identical solvent system and spindle configuration; otherwise the data cannot be used for incoming QC against ISO 2555.
For compliance, raw-polymer documentation should be reviewed against REACH Regulation (EC) No 1907/2006 Annex XVII and the SVHC candidate list as amended. Under RoHS Directive 2011/65/EU, SBS T-420 is outside the electrical and electronic equipment scope unless incorporated into a finished EEE component; no lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE are intentionally added at levels exceeding the directive thresholds. Food-contact suitability must be demonstrated by the finished article manufacturer under Regulation (EC) No 1935/2004; the raw polymer alone is not sufficient for compliance. Storage of the porous pellets in closed containers below 35 °C and 60% RH minimizes moisture absorption and oxidative aging. The grade should not be compounded with strong oxidizing agents, halogenated solvents under high temperature, or primary amine antidegradants when outdoor weathering or light-color retention is required. Published data for medical packaging applications is limited; qualification must be performed at the converter level.
