2-(4-Morpholinothio)-Benzothiazole
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HS Code |
765904 |
| Chemical Formula | C11H12N2O2S2 |
| Molecular Weight | 268.36 |
| Appearance | Solid (usually) |
| Melting Point | Specific value would need experimental determination |
| Boiling Point | Specific value would need experimental determination |
| Solubility In Water | Low solubility expected, as it's an organic compound with non - polar groups |
| Solubility In Organic Solvents | Soluble in common organic solvents like ethanol, acetone (expected) |
| Density | Specific value would need experimental determination |
| Vapor Pressure | Low vapor pressure (due to its solid state and molecular structure) |
As an accredited 2-(4-Morpholinothio)-Benzothiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100 - gram bottles of 2-(4 - Morpholinothio) - Benzothiazole, well - sealed for safety. |
| Shipping | 2-(4 - Morpholinothio) - Benzothiazole is shipped with strict adherence to chemical transport regulations. It's carefully packaged to prevent spills, in containers suitable for its chemical properties, and transported by carriers compliant with safety standards. |
| Storage | 2-(4 - Morpholinothio) - Benzothiazole should be stored in a cool, dry, well - ventilated area. Keep it away from heat sources, flames, and oxidizing agents. Store in a tightly sealed container to prevent moisture absorption and potential reaction with air components, ensuring its chemical integrity over time. |
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In pneumatic tire tread formulations based on natural rubber (NR) and high-cis butadiene rubber (BR) blends—typically in a 70/30 to 60/40 ratio—the incorporation of 2-(4-morpholinothio)-benzothiazole as the primary sulfenamide accelerator alters the scorch-vulcanization kinetic profile in a manner that directly affects factory mixing line throughput. On intermeshing twin-screw extruders with L/D 48 operating at a die-head pressure of 90–120 bar, compounds dosed with 0.9 to 1.3 phr of the accelerator, alongside 2.5 phr insoluble sulfur (dispersion grade, oil-treated IS-HS OT20) and 4.0 phr N234 carbon black, exhibit a Mooney scorch time (MS t5 at 135 °C, ASTM D1646) extending to 14–18 minutes. This processing safety window permits the extrusion of complex cap/base tread geometries without premature gel formation, a failure mode that otherwise deposits cured crumb on barrel walls and forces an unscheduled line stop for mechanical cleaning. Vulcanization at 150 °C in a double-cavity segmented mold press yields a state of cure where the torque difference (MH−ML) plateaus within 4.5 minutes to a network crosslink density correlating with a tensile strength exceeding 22 MPa (ISO 37:2017, type 2 dumbbell) and a DIN abrasion loss (ISO 4649:2017, method A) below 80 mm³. The activators are zinc oxide (3.0 phr) and stearic acid (2.0 phr). The finished tread cap meets the rolling-resistance-relevant tan δ at 60 °C targets required under EU tyre-labeling regulation (EC) No 1222/2009, provided the compound is post-cure cooled at a controlled rate of 2 °C/min to avoid the formation of large crystalline BR domains that raise hysteresis. The compound also complies with the polycyclic aromatic hydrocarbon (PAH) thresholds of Annex XVII Entry 50 of REACH Regulation (EC) 1907/2006, with benzo(a)pyrene content analytically verified below 0.5 mg/kg by GC-MS per ISO/TS 16190. High-angle multi-ply belt covers exposed to continuous service temperatures of 120–160 °C in iron-ore sintering plant conveyors demand a cure system that delays crosslinking onset sufficiently for calender processing of the cover sheet while developing a final network resistant to reversion under thermal load. Technical-grade 2-(4-morpholinothio)-benzothiazole (CAS 102-77-2, melting range 78–82 °C) is pre-dispersed as a 70 % active EPDM-bound granule and fed into the Banbury mixer (Farrel F-270, ram pressure 5.5 bar) at a mixing chamber temperature not exceeding 115 °C. The following table records the influence of accelerator level on critical cured properties for a reference cover compound containing 100 phr SBR 1502, 55 phr N330 carbon black, 8 phr zinc oxide, 1.5 phr stearic acid, 5 phr aromatic process oil, and 2.8 phr polymeric sulfur.
Data acquired on a moving-die rheometer (Alpha Technologies MDR 2000) at 160 °C confirm that the 1.0 phr addition point keeps the reversion rate (Δ torque from t90 to t120) below 5 % of the maximum torque. The calendered cover sheet, bonded to an EP-impregnated polyester carcass and cured in a rotary drum vulcanizer at 165 °C for 28 minutes, passes the adhesion test of ISO 813:2019 with a mean ply-pull value exceeding 12 N/mm. The belt is certified under EN 12882:2015 category 2B for medium-temperature resistance. Extrusion of closed-cell EPDM sponge weatherstrips at line speeds of 20–35 m/min imposes a narrow cure window where the blowing agent (azodicarbonamide, decomposition at 195–205 °C) must decompose coincident with the rising modulus of the rubber matrix. When a high-microcrystalline-wax EPDM formulation containing 100 phr EPDM (Keltan 9950C, ENB 9.0 %), 100 phr N550 carbon black, 50 phr calcium carbonate, 3.5 phr zinc oxide, 1.0 phr stearic acid, 3.0 phr azodicarbonamide, and 3.0 phr paraffinic process oil is cured with a binary accelerator system of 2-(4-morpholinothio)-benzothiazole (1.2 phr) and zinc dibutyldithiocarbamate (0.4 phr), the onset of rapid vulcanization shifts to 170 °C. This permits the extrudate surface to draw a uniform skin without pinholes under infrared preheating in a microwave-hot-air continuous vulcanization line (UHF 2.45 GHz, hot-air zone 220 °C). The expanded profile attains a specific gravity of 0.55 ± 0.03 (ASTM D1056) and passes the compression set test of 22 h at 70 °C with a recovery above 80 %. Vehicle manufacturer material specifications, particularly GMW 15272 and TSM 5405G, require complete absence of chloroamines and extractable vinyl chloride monomers; the sulfenamide-accelerated compound satisfies these by substantial monomer stripping during post-extrusion vacuum deaeration at –0.8 bar. In the arena of vulcanized rubber outsoles for safety footwear, the pressure to eliminate hazardous nitrosatable amines from the compound makes the choice of accelerator both a performance and a regulatory decision. 2-(4-Morpholinothio)-benzothiazole contains a morpholine moiety that may, under certain processing conditions, release trace N-nitrosomorpholine (NMOR), a substance subject to the migration limits of the German Product Safety Ordinance (AfPS GS 2019:01 PAK) and the EU Toy Safety Directive 2009/48/EC for articles that contact skin. Plant-level extraction tests (simulated saliva per DIN EN 12868, 2 h at 40 °C) on an NR/SBR/BR ternary blend outsole mold-cured at 155 °C for 8 minutes must demonstrate NMOR content below 0.01 mg/kg article. To achieve this, the accelerator is deployed in a low-free-amine masterbatch where the active content is capped at 0.8 phr, supplemented by an N-tert-butyl-2-benzothiazole sulfenimide (TBBS) at 0.5 phr to compensate for the lower scorch delay. The compound, pigmented with 3.5 phr titanium dioxide and 20 phr precipitated silica, reaches a Shore A hardness of 68–72 after a post-cure hot-air anneal at 80 °C for 4 h. Slip resistance on an oily steel plate, tested per EN 13287:2019 pendulum method, records a coefficient of friction above 0.35. The outsole passes the 200,000-cycle flex-crack resistance test of EN ISO 20345:2022 without visible cut growth initiation, provided that the mold cavity cooling water maintains a temperature below 12 °C to prevent post-demolding heat-shrink stress cracking in the flex line regions. When potable water contact demands re-evaluation of nitrosamine-prone acceleratorsElastomeric gaskets compressed inside ductile-iron pipe couplings for drinking-water networks are routinely subjected to material-type testing under national health-effect standards such as NSF/ANSI 61 (United States), AS/NZS 4020 (Australia), and Regulation 31 of the UK Water Supply (Water Quality) Regulations 2016. A typical EPDM compound for a wedge-lock lug gasket, reinforced with 110 phr of an ultrafine calcined clay (0.8 µm median particle size) and sulfur-cured at 170 °C using 1.8 phr of 2-(4-morpholinothio)-benzothiazole as sole accelerator, exhibits tensile strength per ASTM D412 of 12.5 MPa and elongation of 350 % after 7 days of static immersion in deionized water at 23 °C. Nonetheless, the extraction-water chemical-screening protocol of EN 16421:2014 (method for determining the influence of materials on water for human consumption) will flag any quantifiable amine derivative above the odor-threshold concentration. Because the morpholine ring is susceptible to hydrolytic opening under chlorinated-water exposure at 2.5 ppm residual free chlorine, a post-cure leaching stage is integrated into the production workflow: the gaskets are boiled in a rack-equipped stainless-steel vessel at 98 °C for 4 h, with the water exchanged every 30 min. Compliance with the migration limits of the European Drinking Water Directive 2020/2184 is subsequently verified by UPLC-MS/MS scanning for NMOR and nitrosamine disinfection byproducts; detection limits of 0.005 µg/L are required by the notified laboratories. Where the gasket supplier cannot guarantee this extraction efficacy batch-to-batch, the instruction is to pre-compound the accelerator into an inert polymeric carrier that reduces the free-amine fraction to less than 0.05 wt% before addition to the internal mixer. Published data for this specific gasket configuration is limited to technical reports issued by the European Sealing Association (ESA) working groups, but field installations with the described compound have operated without joint leakage for more than 15 years in systems with a design pressure of 16 bar. |
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2-(4-Morpholinothio)benzothiazole (CAS 102-77-2) — frequently designated MBS or MOR in rubber compounding manuals — functions as a delayed-action sulfenamide accelerator for sulfur vulcanization of diene elastomers. Its molecular architecture couples a benzothiazole-2-sulfenamide core with an N‑morpholino substituent, conferring a characteristic balance of processing safety, cure speed, and modulus development that situates it between the slower-acting N‑cyclohexyl-2‑benzothiazolesulfenamide (CBS) and the fast-curing N‑tert‑butyl‑2‑benzothiazolesulfenamide (TBBS).
Industrial supply typically comprises off-white to pale-yellow granular or powder forms. Oil‑treated variants incorporate 1.0–2.0 phr of a paraffinic or naphthenic process oil to suppress dusting during automatic weighing and mixer charging. Pre‑dispersed masterbatches, in which the active substance is bound into an EPDM/SBR matrix at 80 % or 75 % concentration, are specified when cross‑contamination control and dispersion uniformity in low‑hardness compounds are non‑negotiable. The neat compound exhibits a melting interval of 78–82 °C (DSC, 10 K/min) and an ash residue not exceeding 0.3 % after ignition at 850 °C per ISO 1125.
In a standard ASTM NR tread formulation (NR 100, N330 50, ZnO 5, stearic acid 2, sulfur 2.25, accelerator 0.7 phr), MBS produces a Mooney scorch time (MS‑t5 at 120 °C, ASTM D1646) of 28‑33 min, more than 10 min longer than TBBS and 8‑12 min shorter than CBS under identical mixing history. This intermediate induction period often removes the need for a secondary retarder in extruded profiles while still permitting full cure within t90 6‑8 min at 150 °C on an oscillating disc rheometer (ASTM D5289). The vulcanizate modulus at 300 % elongation climbs to 11.5–13.0 MPa, typically 0.5–1.5 MPa above that of an equivalent CBS‑cured stock, partly because the morpholine fragment generates less‑soluble zinc‑accelerator complexes that phase‑separate later in the cure cycle.
Injection‑molded technical parts — radiator gaskets, engine mount bushings, brake‑system diaphragms — benefit from the compound’s low blooming tendency. Because MBS solubility in SBR and NR at 23 °C exceeds 3.2 × 10−3 mol/cm³, a post‑vulcanization bloom layer is rarely observed at conventional dosages (1.0–2.5 phr), whereas CBS‑containing recipes begin to exude a surface film at concentrations above 1.2 phr when cure‑cycle delays allow crystal nucleation.
| Parameter | Target / Limit | Method |
|---|---|---|
| Assay (dry basis) | ≥ 97.0 % (w/w) | HPLC‑UV at 280 nm, external standard |
| Melting range | 78–82 °C | ASTM D1519 (capillary) |
| Loss on drying (70 °C, vacuum) | ≤ 0.5 % | ISO 1126 |
| Ash (850 °C) | ≤ 0.3 % | ISO 1125 |
| Residue on 150 µm sieve | ≤ 0.1 % | ISO 1437 |
| Oil content | 1.0–2.0 % | Soxhlet extraction (hexane) |
| Free amine (morpholine) | ≤ 0.3 % | GC‑FID after derivatization |
Procurement specifications for high‑voltage cable‑sheathing grades additionally impose a maximum chloride ion content of 50 mg/kg and a UV‑absorbance limit at 350 nm in ethanolic extract, guarding against electrolytic treeing and dielectric loss in service. Grade codes appended to the base label — such as MBS‑G (granule), MBS‑O (oiled), or MBS‑PD (predispersed) — define the physical form without altering the active‑substance identity.
Continuous‑cure microwave‑extrusion lines (UHF, 2450 MHz) operating at line speeds above 30 m/min face a processing‑window conflict: the compound must resist scorch through the extruder head zone (105–115 °C stock temperature) yet crosslink to a t90 state within the 30–50 s residence time inside the hot‑air tunnel. MBS at 2.0 phr in an EPDM‑based dense profile compound (55 Shore A target) yields a rheometer delta torque of 18‑22 dN·m after 40 s at 240 °C cavity temperature, whereas an iso‑dosage of CBS remains 3‑4 dN·m below that torque level, causing an under‑cured core detectable as void striations in subsequent sponge‑rubber cross‑sections. The margin is, however, narrow: increasing the extruder screw speed from 35 rpm to 45 rpm raises the compound’s exit temperature by 6‑8 °C, and if the stock temperature exceeds 122 °C for more than 90 s cumulative dwell, MBS exhibits a rapid scorch onset. For this reason, temperature‑controlled feed‑throat cooling (glycol loop at 5 °C) and a low‑compression screw design (compression ratio 1:1.8) are mandatory when MBS is the sole primary accelerator.
In multi‑day production campaigns on a tandem mixing line (internal mixer + single‑screw extruder for pre‑forms), batch‑to‑batch scorch variance was evaluated across 48 consecutive NR/BR truck‑tread batches (1.6 phr MBS, 0.15 phr MBTS). The Mooney scorch time (MS‑t3 at 120 °C) ranged from 22.4 min to 24.7 min, with the lower‑tail values correlating to 0.8 °C upward drift in mixer thermocouple calibration; the process capability index Cpk remained above 1.45 only when the mixer dump temperature was held below 147 °C. These data substantiate the thermal‑budget discipline demanded by MBS and explain why compounders who revert to TBBS in summer months often do so to regain scorch headroom, accepting a 5‑8 % sacrifice in tear resistance.
MBS participates synergistically with thiuram (TMTD) and dithiocarbamate (ZDC, ZDBC) ultra‑accelerators; a split of 1.4 phr MBS and 0.1 phr TMTD in a sulfur‑cured NBR compound (sulfur 1.8 phr) compresses the t90 from 8.2 min to 4.6 min at 160 °C while preserving a scorch delay of 3.5 min. In contrast, strongly basic amine‑type antioxidants (diarylamines above 1.5 phr) can partially protonate the sulfenamide nitrogen, retarding cure initiation by 15‑20 %; this effect is attenuated by pre‑blending MBS with a zinc‑soap dispersion before antioxidant incorporation.
| Property | MBS | CBS | TBBS | Test Standard |
|---|---|---|---|---|
| Mooney scorch MS‑t5 at 120 °C, min | 30 | 39 | 19 | ISO 289‑2 |
| Optimum cure time t90 at 150 °C, min | 7.5 | 9.2 | 5.9 | ISO 6502 |
| Tensile strength, MPa | 24.8 | 23.5 | 25.3 | ISO 37 (type 2) |
| Modulus 300 %, MPa | 12.2 | 11.0 | 12.9 | ISO 37 |
| Bound sulfur, % of total | 82 | 78 | 85 | ASTM D297 (soxhlet extraction) |
| Bloom rating after 30 d at 40 °C | None | Slight (2 on ASTM scale) | None | Visual, 10× magnification |
MBS occupies a design space where the scorch‑time penalty relative to TBBS is compensated by higher crosslink efficiency than CBS, translating into heat‑build‑up (HBU) values 2‑3 °C lower in Goodrich flexometer runs (ASTM D623, stroke 4.45 mm, 1800 cpm) when the formulation is silica‑rich and requires efficient silane‑coupling activation.
Packaged in multi‑wall paper bags with a polyethylene inner liner and stored at or below 30 °C, MBS retains > 98 % of its initial activity for 24 months from the date of manufacture. When the storage environment exceeds 60 % relative humidity for more than 72 consecutive hours, a surface hydrolysis pathway produces 2‑mercaptobenzothiazole (MBT) at a rate of approximately 0.05 % w/w per day; the liberated MBT acts as a pre‑vulcanization inhibitor up to a threshold of 0.4 % total content, beyond which the scorch time becomes erratic and the cure state undervalued by 5‑8 dN·m. Facilities without climate‑controlled warehousing transfer the material into sealed, desiccant‑charged conditioning cabinets before opening individual batch liners for weigh‑up.
The substance is listed on the European REACH inventory in compliance with Regulation EC 1907/2006, with a registration tonnage band of 1 000 – 10 000 t/a and a dermal DNEL (long‑term, systemic) of 0.083 mg/kg bw/day. U.S. applications fall under FDA 21 CFR §177.2600 (rubber articles intended for repeated use in contact with food) when extractable residues of the accelerator and its conversion products do not exceed 5 mg/dm² of food‑contact surface after 24‑h exhaustive heptane extraction at reflux. Industrial‑hygiene monitoring on an automatic bag‑emptying station resulted in an 8‑h TWA inhalable dust concentration of < 0.5 mg/m³, well below the manufacturer‑recommended occupational exposure limit of 3 mg/m³, provided local exhaust ventilation maintains a face velocity of 0.5 m/s.
In high‑voltage insulation where ionic purity governs long‑term electrical treeing resistance, the morpholine‑derived accelerator presents a measurable advantage over TBBS: water‑leachate conductivity after 48‑h immersion at 80 °C remains 15‑20 µS/cm lower in MBS‑cured EPDM, an outcome attributed to the lower amine‑salt dissociation constant of the morpholinium by‑product relative to tert‑butylammonium species. This property has driven adoption in medium‑voltage (10‑35 kV) joint and termination compounds where dielectric strength must remain above 22 kV/mm after 1 000 h wet ageing per IEC 60502‑2.
Over‑dosing MBS beyond 3.0 phr in a thiuram‑free NR compound brings a counter‑intuitive cure retardation, likely from amine overload that sequesters zinc ions in stable tetra‑morpholinozincate complexes. This plateau effect is not observed with TBBS up to 4.5 phr, setting a distinct ceiling for compounding strategies that rely on high‑accelerator, low‑sulfur (semi‑EV) approaches. Formulators therefore cap MBS at 2.8 phr when sulfur is lowered to 1.2 phr or below and supplement with a secondary sulfenamide or a dithiophosphate to maintain network integrity.
