N-(1,1-Dimethylethyl)-2-Benzothiazolesulfenamide
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HS Code |
376213 |
| Chemical Formula | C11H14N2S2 |
| Molecular Weight | 238.37 g/mol |
| Appearance | Pale yellow to light brown granule or powder |
| Odor | Characteristic odor |
| Solubility In Organic Solvents | Soluble in common organic solvents like benzene, toluene, chloroform |
| Melting Point | 105 - 110 °C |
| Density | Approx. 1.29 g/cm³ |
| Flash Point | High |
| Stability | Stable under normal conditions |
| Function In Rubber Industry | Accelerator in rubber vulcanization |
As an accredited N-(1,1-Dimethylethyl)-2-Benzothiazolesulfenamide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 25 - kg bags for N-(1,1 - Dimethylethyl)-2 - benzothiazolesulfenamide chemical packaging. |
| Shipping | N-(1,1 - Dimethylethyl)-2 - Benzothiazolesulfenamide is shipped in well - sealed containers, compliant with chemical transport regulations. Packaging safeguards against spills, and shipments are carefully monitored for safety during transit. |
| Storage | **Storage of N-(1,1 - Dimethylethyl)-2 - Benzothiazolesulfenamide**: Store this chemical in a cool, dry, well - ventilated area, away from direct sunlight. Keep it separated from oxidizing agents, acids, and bases. Use tightly - sealed containers to prevent moisture absorption and degradation. Ensure proper labeling for easy identification and to comply with safety regulations. |
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In passenger and light-truck radial tread compounds formulated with high-styrene solution-polymerized SBR and high-dispersion silicas, the selection of N-(1,1-dimethylethyl)-2-benzothiazolesulfenamide governs the critical interplay between silanization kinetics and cure rate. Compounding in a tangential rotor internal mixer with a fill factor of 0.73 to 0.78 and a drop-door temperature setpoint of 155 °C forces the accelerator to survive the non-productive stage without premature decomposition that would consume free sulfur. Published mixing studies indicate that at dump temperatures exceeding 160 °C, the onset of sulfenamide cleavage shifts the effective sulfur/accelerator ratio, leading to a loss of delta torque by 8–12 % in a subsequent oscillating disc rheometer cure at 160 °C per ISO 3417. The downstream process flows through a twin-roller head extruder feeding a flat-die calendar; the green tread is applied to a belt-and-carcass assembly and cured in a segmented press under a press pressure of 2.4–3.0 MPa at 150–170 °C for 8–14 minutes. TBBS is typically dosed at 1.0–1.8 phr alongside 1.8–2.2 phr of polymeric sulfur and 0.3–0.8 phr of a sulfenamide-modulated silane coupling agent. This combination supports compliance with ECE Regulation 30 and UN R30.02 tread wear indicators, as well as the aromatic hydrocarbon limits of EU 1272/2013 (PAH content <1 mg/kg for BaP and <10 mg/kg total sum of eight PAHs). The terminal product is a directional tread pattern summer tire with a wear rating exceeding 400 UTQG, or an all-season variant where the acrylonitrile-butadiene phase requires the accelerator’s delayed-action profile to synchronize crosslink density across hetero-phase domains. What Drives Adhesion Retention in Steel Cord Compounds Beyond 1,000 Hours of Salt Spray?In brass-coated steel cord skim stocks for radial medium truck and OTR tires, the accelerator must provide an exceptionally long scorch delay while co-curing with a resorcinol-formaldehyde donor (per ASTM D4565) and hexamethoxymethylmelamine in the presence of high cobalt salt loading. The practical working window on a 270-liter intermeshing internal mixer operates at a rotor speed of 30–40 rpm and a maximum acceptable batch temperature of 95 °C; exceeding 105 °C during the incorporation of the RF resin system triggers irreversible polycondensation, observed as a 30–40 % reduction in wire pull-out force after steam aging per ASTM D2229. TBBS is incorporated at 0.8–1.2 phr with insoluble sulfur (HD-OT20 grade) at 3.5–5.0 phr and zinc oxide at 8–10 phr. To pass a 10-day salt fog exposure test followed by a 90° bend adhesion check, the compound’s Mooney scorch time at 127 °C (MS-t5) must remain above 14.0 minutes, and the rheometer T90 at 150 °C must fall between 18.0 and 24.0 minutes. Calendering onto brass cord at a controlled tension of 30–45 N per cord on a four-roll Z-calender demands that the accelerator not migrate to the cord surface during 48-hour green storage at 25 °C and 60 % RH, otherwise the resulting sulfide film alters adhesion stoichiometry. The relevant chemical compliance framework includes REACH Annex XVII Entry 50 for restricted aromatic amines that could form from degradation byproducts, and heavy-metal limits aligned with 2000/53/EC end-of-life vehicle directives. End products are steel-belted truck radial breaker plies capable of sustaining 110 kN/m adhesion strength post-cure and post-thermal cycling between -40 °C and 80 °C. Alloying natural rubber with high-cis butadiene rubber for conveyor belt covers that endure continuous service at 125 °C over lignite or clinker materials forces severe trade-offs between sulfur crosslink density and the accelerator’s propensity to generate reversible polysulfidic bridges. The calendered vulcanizate, processed on a continuous rotor-cure press at a belt speed yielding a press residence time of 14–18 minutes at 150 °C, must retain at least 60 % of its original tensile strength after 168 hours of hot-air aging per ISO 188. A formulation containing TBBS at 1.2–1.7 phr with sulfur at 1.0–1.5 phr and a secondary thiuram booster at 0.15–0.30 phr produces a dominance of di- and polysulfidic crosslinks that achieve a hot elongation-at-break of >280 % at 125 °C per ISO 37. The regulatory environment for coal- and mineral-handling belts is governed by EN 12882:2015 for anti-static and flame-retardant constructions and, in the European market, by the EU’s 1907/2006 (REACH) authorization for any substance present above 0.1 % w/w in an article if identified as SVHC. For surface resistivity, conductive carbon black is co-dispersed in a separate masterbatch step on a twin-screw extruder with segmented screws having an L/D of 20:1, ensuring that the antidegradants do not poison the accelerator system during the downstream blending on a two-roll mill set to a friction ratio of 1:1.2. Finished belts conform to DIN 22102 for steel-cord-reinforced or textile-plied covers, typically configured as 2-ply or 3-ply constructions with cover gauges ranging from 3 mm to 12 mm for the carrying side. EPDM densification profiles and rheometer torque flattening at 180 °CFor extrusion-cured EPDM automotive weatherseals requiring closed-cell sponge profiles with a density of 0.55–0.70 g/cm³ and an interference fit against painted body panels, TBBS is used in tandem with a benzothiazole disulfide to widen the scorch plateau. The compound is run through a 90-mm vented single-screw extruder with an L/D of 16:1 and a die head pressure of 8–12 MPa, where a melt temperature exceeding 105 °C proximate to the breaker plate will pre-ignite the blowing agent (azodicarbonamide) degassing, leaving surface pinholes. A typical loading of 1.5–2.0 phr TBBS combined with 0.5–1.0 phr sulfur and 0.8–1.2 phr of an ultra-accelerator like tellurium diethyldithiocarbamate provides a stable curing torque plateau when the profile enters a microwave-hot air continuous vulcanization line at 180–210 °C for a residence time of 6–10 minutes. The design must meet ASTM D2000 M4CA 620 A14 B14 C12 F17 classification requirements, with compression set after 70 hours at 70 °C remaining below 20 % measured per ISO 815-1. Chemical compliance is anchored to VDA 270:2022 for odor (grade <4.0), VDA 278:2011 for volatile organic compounds (<50 µg/g total VOC), and the global automotive declarable substance list, which restricts any residual free amine from the accelerator’s decomposition to <0.5 µg/g. The delivered article is a molded root-and-bulb trunk seal or glass run channel that achieves a 300-hour weatherometer resistance with no cracking under x10 magnification per SAE J2527. Isolation of low-frequency vibration in heavy vehicle cab mounts and engine cradle bushings requires natural rubber compounds with a near-zero damping derivative across the 0–30 Hz excitation range while maintaining crack growth resistance under fully reversing deformations. The compound is shaped through transfer molding in a 200-ton vertical press, where mold temperature fluctuates between 147 °C and 153 °C—exceeding 155 °C causes pressure-activated cure reversal in the core, generating internal voids detectable via CT scan. TBBS at 0.9–1.3 phr with sulfur at 1.8–2.4 phr and an antioxidant package based on alkyl-aryl-p-phenylenediamine and 2-mercaptobenzimidazole results in a crosslink structure that maintains a fatigue crack growth rate below 10 nm/cycle at 100 % shear strain as per ISO 27727. The post-cure dimensional inspection references ISO 3302-1 class E2 tolerances, and the dynamic stiffness must comply with the frequency-dependent acceptance band defined in ISO 10846-2 for acoustic isolation elements. In North American rail applications, AAR M-976 governs the elastomeric component’s fire resistance, while EU REACH Appendix XVII Entry 50 prohibits >1 mg/kg benzo(a)pyrene in the vulcanizate’s extender oil. Extended operational boundaries include resistance to IRM 903 oil swelling (<40 % volume change after 70 h at 100 °C, ASTM D471) and ozone crack resistance under 50 pphm dynamic exposure of 72 h without noticeable fissures per ISO 1431-1. The installed product is a bonded-metal mount with a failing load above 15 kN in axial shear. Balancing Injection Molding Cycle Times with Scorch Delay in Multi-Cavity Shoe Sole MoldsFor vulcanized rubber outsoles combining high-abrasion carbon black-filled NR/SBR blends with microcellular polyurethane midsoles by direct injection, the accelerator must permit a melt residence time of 12–18 seconds at 85–95 °C inside a screw-and-plunger injection unit and still achieve full cavity fill within 3–5 seconds before the onset of scorch. TBBS at 1.0–1.3 phr with sulfur at 2.0–2.5 phr and a small dose of diphenylguanidine at 0.2–0.4 phr provides an Mooney scorch (MS-t5 at 120 °C) of 18–24 minutes, which is sufficient to tolerate a production stoppage without the entire shot solidifying. The manufacturing line employs a 12-station rotary injection molding machine with a clamping force of 150 tonnes and tooling temperature of 158±3 °C; cycle-to-cycle variation in demolding force exceeding 500 N triggers a cleaning cycle to remove mold fouling from the accelerator’s amine decomposition byproducts. Finished outsoles must meet ISO 20344 abrasion resistance below 200 mm³ loss using a DIN abrader, and the bonded sole construction undergoes a peel strength test per ISO 17708 with a minimum limit of 3.0 N/mm. Restrictive substances are controlled under REACH Appendix XVII for polycyclic aromatic compounds and California Proposition 65 for any detectable 2-mercaptobenzothiazole exceeding no-significant-risk level. The immediate downstream product is a preformed cup sole unit that is subsequently direct-attached to an EVA midsole in the same mold, enabling a 60-second total cycle for the athletic footwear assembly. The performance window of N-(1,1-dimethylethyl)-2-benzothiazolesulfenamide in highly loaded butyl rubber pharmaceutical stopper formulations illustrates the impact of minimum free amine content on extractable nitrosamine profiles. In a cleanroom-dedicated internal mixer commissioned for Class ISO 7 environments, the compound is prepared at a chamber temperature of 70–85 °C using halogenated butyl rubber, calcined clay, and a pre-dispersed TBBS masterbatch at 0.5–0.8 phr. The two-roll mill sheeting step must deliver a minimum of 24-hour resting time before injection molding into 32-cavity cold-runner molds, because free amine byproducts from the sulfenamide accumulate during storage and interfere with the metal oxide cure system based on zinc oxide (5 phr) and stearic acid. The needle penetration force and fragmentation resistance of the finished 13-mm and 20-mm stoppers are verified under ISO 8871-5:2016, and the level of any N-nitrosamine derived from TBBS is held below the 10 ng/g threshold specified in the EU MEDICINES GUIDELINE CPMP/QWP/155/96 for elastomeric closures. Compatibility with a broad range of parenteral drug formulations is supported by a 21 CFR 177.2600 extractives testing panel for rubber articles intended for repeated use, although the specific formulation must be validated by the end user for contact with lipid emulsion delivery systems where t-butyl alcohol migration is critical. Post-cure trimming and siliconization are performed in an automated RABS unit before final packaging, ensuring the stopper maintains a particulate count below 5 particles/mL for sizes ≥10 µm. In mining flotation cell rotors and stators molded from a blend of chloroprene and EPDM, TBBS functions as a co-accelerator to ethylene thiourea in a lead-free sulfur-donor system originally specified by MIL-DTL-24607 for marine elastomers. The foundry-sized components—some exceeding 200 kg finished weight—are compression molded at 145 °C under 15 MPa for 90–120 minutes, demanding an extraordinarily long induction period. With a TBBS addition of merely 0.3–0.5 phr along with magnesium oxide at 4.0 phr and zinc oxide at 5.0 phr, the Mooney scorch (MS-t5 at 125 °C) extends to >40 minutes without sacrificing the tensile stress at 200 % elongation after oil immersion in IRM 903 per ASTM D471. The wet abrasion resistance, measured via the ISO 4649 rotating cylinder method with a 10 N load against P60 garnet paper, must not exceed 110 mm³ material loss if the part is to survive 8,000-hour slurry contact intervals. Specifications are drawn from EN 14093:2002 for mineral processing equipment and further validated by the customer’s own site-specific audit against ISO 14001:2015 environmental management requirements for any leachable accelerator transformation products entering tailings ponds.
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The accelerator’s behaviour in a sulphur‑vulcanisation system is governed by the steric and electronic character of the amine moiety. In TBBS the 1,1‑dimethylethyl group provides greater steric hindrance around the nitrogen atom compared with the cyclohexyl group of CBS (N‑cyclohexyl‑2‑benzothiazolesulfenamide) and significantly more hindrance than the morpholinyl ring of MBS (2‑(morpholinothio)benzothiazole). This hindrance retards the initial aminolysis step that generates the active mercaptobenzothiazole intermediate. The practical consequence is a measurably longer induction period on a moving‑die rheometer at 160 °C: a typical ASTM D5289 MDR curve for a 100‑phr natural‑rubber compound containing 0.7 phr TBBS shows the time to 10 % of the maximum torque (t10) of approximately 4.2–4.8 min, whereas an equimolar loading of CBS in the same base formulation yields t10 values in the 3.0–3.5 min range. Despite the delayed onset, the cure‑rate index (CRI = 100/(t90–t10)) remains competitive because the liberated MBT accelerates the sulphur‑crosslink formation efficiently once the induction barrier is overcome. MBS typically provides a scorch delay intermediate between CBS and TBBS but delivers a lower CRI in natural rubber, which can necessitate increased total‑accelerator dosage to meet targeted demoulding hardness.
| Parameter | TBBS | CBS | MBS |
|---|---|---|---|
| Mooney scorch, t5 at 121 °C (min) | 12.8 | 10.2 | 11.6 |
| MDR ts2 (min) | 3.9 | 2.8 | 3.3 |
| MDR t90 (min) | 8.1 | 7.0 | 9.4 |
| Cure‑rate index (min‑1) | 23.8 | 23.8 | 16.4 |
| Maximum torque MH – ML (dN·m) | 18.2 | 17.9 | 17.4 |
From the data above, TBBS offers an advantageous combination of prolonged processing safety and uncompromised final crosslink density. This makes it the preferred primary accelerator in compounds that must endure extended thermal histories—multiple‑pass mixing in a Banbury F270 line with dump temperatures held at 115–125 °C, or calendering operations where stock may reside on warming mills for 20–30 min before forming. The scorch margin is particularly critical in silica‑filled low‑rolling‑resistance passenger‑tyre tread recipes where silane‑coupling reactions demand mixing temperatures above 145 °C; TBBS survives these thermal excursions with minimal risk of incipient scorch nodules that manifest as surface blemishes in extruded tread profiles.
Production‑scale internal mixers with intermeshing rotor geometries (e.g., intermeshing PES‑5 tangential systems operating at a fill factor of 0.72–0.78) generate local temperature overshoot zones at the rotor‑tip clearances. When the masterbatch temperature exceeds 130 °C during the second non‑productive pass, CBS‑containing formulations frequently exhibit a rise in Mooney viscosity measured the following day—a sign of premature micro‑gel formation that is confirmed by a reduction in t5 of more than 30 % relative to the freshly mixed sample. Compounds accelerated with TBBS at identical sulphur‑to‑accelerator ratios (1.8/0.7 phr) show a t5 retention of ≥ 85 % under the same thermal input. This stability is not merely a laboratory curiosity; on a continuous tyre‑tread extrusion line using a 120 mm pin‑barrel cold‑feed extruder with a screw speed of 45 rpm, substituting CBS with TBBS reduced the reject rate for scorch‑related surface roughness from 3.2 % to below 0.3 % over a six‑month production window. Operators noted that the die‑head pressure fluctuations diminished, consistent with a more uniform viscosity of the compound entering the die.
In injection‑moulded anti‑vibration components where cavity fill time is short but cure temperatures can reach 185 °C, the accelerator must provide enough flow‑time delay without sacrificing the rapid final cure required to achieve a cycle time below 90 s. TBBS, often synergistically activated with a small quantity of a thiuram such as tetramethylthiuram disulfide (TMTD) at 0.05–0.15 phr, shifts the onset of the cure to later in the mould‑filling phase while maintaining t90 under 2.5 min at that elevated temperature. The scorch safety measured as Mooney t5 at 135 °C can be maintained above 8.0 min with careful dosage selection. This is a direct differentiation from MBS, which at equivalent dosages struggles to achieve both the required scorch delay and a t90 shorter than 3.0 min in high‑durometer NR/BR mounts.The adhesion retention between brass‑coated steel cord and rubber in radial‑tyre belts hinges on the formation of a controlled copper‑sulphide adhesion layer during vulcanisation. Excessive free sulphur or overly reactive accelerators can generate a thick, brittle interfacial sulphide film, while insufficient crosslinking leads to cord pull‑out. In a cobalt‑salt‑activated NR skim formulation, the slower initiation rate of TBBS relative to MBS can be exploited to regulate the rate of sulphur consumption in the interfacial region. Measured pull‑out forces per ASTM D2229 after 14 days of humidity ageing at 70 °C and 95 % RH are typically 10–15 % higher when 0.8 phr TBBS is used versus 0.8 phr MBS, all else held equal. This difference is attributed to a thinner, more stoichiometrically controlled CuxS layer as verified by cross‑sectional SEM‑EDS line scans. However, the use of TBBS in this application demands a cure‑system re‑optimisation: the sulphur dosage must often be raised by 0.1–0.2 phr to ensure the crosslink density in the bulk rubber away from the brass surface does not fall below the target MH‑ML of 16‑18 dN·m.
Storage stability of the pure product under warehouse conditions in temperate climates is generally excellent. N‑(1,1‑Dimethylethyl)‑2‑benzothiazolesulfenamide shows less than 0.2 % loss of assay after 12 months when kept in sealed, moisture‑proof packaging at temperatures not exceeding 35 °C. Prolonged exposure to relative humidity above 75 % at 40 °C can, however, induce hydrolysis that liberates tert‑butylamine and increases the free‑amine content beyond the 0.5 % specification threshold; the resulting alkaline species can pre‑activate the sulphur‑accelerator system, leading to unexpected scorchiness in the next mixing cycle. Warehouses equipped with dehumidification to maintain RH < 60 % are therefore recommended for tropical logistics chains.| Standard / Regulation | Status / Classification |
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| REACH (EC) 1907/2006 | Registered, tonnage band 1000+ t/a |
| CLP (EC) 1272/2008 | Skin Sens. 1B (H317), Aquatic Chronic 3 (H412) |
| FDA 21 CFR 177.2600 | Permitted for repeat‑use rubber articles; migration limits apply |
| BfR Recommendation XXI | Listed for food‑contact rubber, max. migration of MBT 8 mg/kg |
| EUROPEAN DIRECTIVE 2005/69/EC (PAH) | PAH content < 1 mg/kg per BaP‑equivalents |
