N-Oxydiethylene-2-Benzothiazole Sulfonamide
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HS Code |
345773 |
| Chemical Formula | C11H12N2O3S3 |
| Molecular Weight | 316.42 |
| Appearance | white to off - white powder |
| Odor | odorless or slightly characteristic odor |
| Solubility In Water | practically insoluble |
| Solubility In Organic Solvents | soluble in some organic solvents like acetone, chloroform |
| Melting Point | 155 - 165°C |
| Flash Point | relatively high |
| Thermal Stability | stable under normal processing temperatures |
| Storage Stability | stable when stored in a cool, dry place |
As an accredited N-Oxydiethylene-2-Benzothiazole Sulfonamide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 25 - kg bags for N - Oxydiethylene - 2 - Benzothiazole Sulfonamide chemical packaging. |
| Shipping | N - Oxydiethylene - 2 - Benzothiazole Sulfonamide is shipped in sealed, corrosion - resistant containers. Packaging ensures protection from moisture and external contaminants during transit to maintain product integrity. |
| Storage | **Storage of N - Oxydiethylene - 2 - Benzothiazole Sulfonamide**: Store this chemical in a cool, dry, well - ventilated area. Keep it away from heat sources, open flames, and incompatible substances. Package it in tightly - sealed containers to prevent moisture absorption and degradation. Avoid storing near oxidizing agents or strong acids to maintain its chemical stability. |
In the formulation of passenger car and truck tyre treads where high-frequency cyclic deformation demands a balance between stiffness and hysteresis, the substitution of N-tert-butyl-2-benzothiazole sulfenamide (TBBS) with N-oxydiethylene-2-benzothiazole sulfenamide (OTOS) is evaluated at masterbatch densities targeting a reinforcing carbon black loading of 50–65 phr in a 70/30 blend of SMR 20 natural rubber and BR 1220 butadiene rubber. The mixing cycle in a 270‑litre intermeshing-type internal mixer with an L/D ratio of 1.6:1 and ram pressure of 6.5 MPa proceeds through two non-productive stages before the addition of OTOS at 1.2–1.8 phr together with sulfur at 1.8–2.2 phr and zinc oxide at 3.0 phr in a productive stage dumped at 95–105 °C. Measurement on ASTM D5289 with an oscillating disc rheometer at 160 °C shows a scorch time ts2 between 3.2 and 4.6 min and a t90 cure time of 8.5–11.0 min, providing a reproducible window for injection moulding and press curing of tread profiles without premature crosslinking in ram accumulators. The vulcanizate achieves a 300 % modulus of 10.8–12.5 MPa, a tensile strength under ISO 37 of 22.5–25.0 MPa, and a DIN abrasion index per ISO 4649 below 125 mm³ when the OTOS-sulfur ratio is held above 0.6:1, because the morpholine-ether moiety retards the decomposition of the active sulfurating agent and allows a higher crosslink density before reversion becomes detectable. A critical limit observed in twin-screw extruders feeding tread profiles with hot-feed temperatures exceeding 120 °C is that the Mooney scorch time at 127 °C drops below 18 min when the compound is left in a dead-stock zone longer than 4 min, requiring the use of a 1.0 phr anti-scorch additive such as N-(cyclohexylthio)phthalimide only when the OTOS loading is pushed beyond 2.0 phr.Why Does the Skim Compound for Brass-Coated Steel Cord Adhesion Mandate an N-Oxidised Sulfenamide Structure?The skim layer in radial tyre belt constructions, calendered to a thickness of 0.6–1.2 mm over brass-coated steel cords with a 7×4×0.22 construction, operates under high-shear stress and requires both exceptional rubber-to-metal adhesion and long-term thermal stability in the presence of cobalt naphthenate at 1.0–1.5 phr and resorcinol-formaldehyde donor systems. The substitution of standard sulfenamides with OTOS derives from the absence of secondary amine generation during vulcanisation, eliminating the potential for amine-catalysed dezincification of the brass plating that leads to a drop in pull-out force below 18 N/mm after humid-ageing for 21 days at 70 °C and 95 % RH per ASTM D2229. In a typical belt compound based on TSR 20 natural rubber with a silica/carbon black hybrid filler at 15/40 phr, the use of OTOS at 1.0–1.3 phr in combination with a secondary accelerator such as dibenzothiazyl disulfide (MBTS) at 0.3 phr develops a scorch delay measured by Mooney viscometer MS 1+4 at 121 °C of 38–50 min, essential for maintaining viscosity during the multi-day production of wide-width fabric and cord calenders. Process data from a four-roll inverted‑L calender train operating at 18 m/min indicate that compound temperature must be held below 105 °C at the nip exit; OTOS allows a wider processing window by delaying the onset of crosslinking until the temperature exceeds 145 °C. The adhesion force determined on a TCAT pull-out tester after 30 min vulcanisation at 150 °C reaches 425–480 N/25 mm with 80 % rubber coverage, and the degradation in bond strength after an additional 14-day cure at 80 °C remains below 12 %, a margin that conventional TBBS-accelerated compounds fail to meet consistently.Conveyor belt cover compounds intended for abrasive mineral transport under continuous tension are mixed in a two-stage process using a F‑270 internal mixer for masterbatch and a supplementary open mill for accelerator addition at roll temperatures of 55–65 °C. A cover formulation designed for a 6 mm thick abrasion-resistant top layer on a 3-ply EP fabric carcass combines NR/SBR 1502 at a 60/40 ratio, reinforcing furnace black N‑220 at 48 phr, and a processing oil level not exceeding 6 phr to avoid exudation during troughing. The OTOS content is set at 1.4–1.8 phr with soluble sulfur at 2.0 phr and a pre-vulcanisation inhibitor at 0.1 phr only when ambient workshop temperature exceeds 35 °C. Rheometer traces under ISO 3417 at 150 °C show a minimum torque ML of 2.1–2.8 dN·m and a maximum torque MH of 17.5–19.2 dN·m, indicating a high crosslink density that translates into a 300 % modulus after steam autoclave curing at 141 °C for 45 min of 13.0–14.8 MPa (measured on dumbbell specimens died out parallel to the warp direction per ISO 37). The cover compound must pass a DIN 53516 abrasion test below 115 mm³ loss and resist the propagation of longitudinal tears under a repetitive flexing test with 20 mm drum diameter for over 200,000 cycles without delamination. The absence of free amine by-products in OTOS-accelerated stocks eliminates the risk of amine bloom at the cover-to-carcass interface, which is a documented failure mode when natural rubber skirt boards are bonded to SBR-based covers in bulk-haulage conveyors. Compliance with MT/T 914‑2019 for fire-retardant conveyor belts in underground coal mines is achievable when a chlorinated paraffin at 15 phr and antimony trioxide at 5 phr are loaded into the OTOS system without a detectable drop in the scorch window; industrial runs on a 2400‑mm wide rotocure press have confirmed that the crosslinking density develops uniformly across the full width with a standard deviation in Shore A hardness of ≤ 1.2 points.When an EPDM Dense Profile Extrusion Delivers a Critical Trade-Off Between Low-Temperature Compression Set and Short Oven Dwell TimesAutomotive glazing weatherstrips made from a sulfur-cured EPDM compound with an ethylene content of 55–60 wt%, an ENB termonomer content of 4.5–5.5 wt%, and an extended oil at 55 phr are processed through a vented 90‑mm pin-barrel extruder with a 24:1 L/D and a crosshead die at 22 m/min. The compound requires a scorch safety margin that permits residence times inside the 250 °C hot-air continuous vulcanisation tunnel without pre-crosslinking in the extrusion head at 70 °C. OTOS at 0.9–1.3 phr paired with dithiocarbamate or thiuram accelerators at sub-0.5 phr levels replaces the conventional morpholine sulfenamide that is restricted under TRGS 552 Category 2 due to N-nitrosomorpholine formation upon nitrosating agents present in the production environment. The oscillating disc rheometer at 180 °C records a t10 between 1.2 and 1.9 min and a t90 below 4.5 min, synchronising the cure curve with the time-at-temperature profile of the infrared/hot-air tunnel. Physical properties after 120‑second cure at 220 °C must satisfy VDA 675 218 for compression set under 25 % deformation at 70 °C for 24 h with a maximum set of 35 %, and the OTOS-vulcanised profile consistently records 28–32 % set whereas a TBBS analogue drifts above 38 % due to less efficient crosslink utilisation. The extracted ammonia during cure is reduced, and the condensate from the air exhaust does not contain quantifiable nitrosamine levels when tested per DIN 38407‑13, a mandatory release certificate requirement for seals shipped to European OEMs. A limitation occurs when the weatherstrip includes a co-extruded metal carrier: the continuous stress relaxation under 40 % elongation measured with a Shawbury‑Wallace relaxometer shows a 6 % lower force retention after 168 h at 100 °C when the OTOS dosage exceeds 1.5 phr, due to increased modulus-driven stress decay; therefore the formulation border is set at 1.3 phr for talc-filled, metal‑insert profiles.Rubber engine mounts and bushings designed for a service life exceeding 200,000 km in a passenger car drivetrain are injection-moulded from a NR/SBR 1500 blend reinforced with carbon black N‑330 at 38 phr and protected by a paraphenylenediamine antiozonant at 2.5 phr plus microcrystalline wax at 1.5 phr. The compound is pre-blended in a tangential mixer and subsequently fed to a 500‑tonne clamping‑force injection‑moulding machine with a plunger‑type injection unit operating at 145 °C barrel temperature and an injection pressure of 120 MPa. Because the cavity fill time is 1.8–2.5 s and the mould temperature is set at 175 °C, the accelerator system must resist scorch during plasticisation yet vulcanise within 120–150 s to meet a cycle time of 4.5–5.0 min for a 1.2‑kg mount. A cure package consisting of OTOS at 0.9–1.2 phr, 2‑(morpholinothio)benzothiazole sulfenamide at 0.3 phr, and insoluble sulfur at 2.5 phr shifts the t5 scorch time at 135 °C to 12–16 min while dropping the t90 at 175 °C to 2.8–3.6 min on an MDR 2000 rheometer. The dynamic‑to‑static stiffness ratio Kdyn/Kstat measured under ± 0.1 mm amplitude and 100 Hz excitation per ISO 10846‑2 settles at 1.35–1.45, a range that reduces cabin noise transfer better than a formulation accelerated solely with dithiocarbamates, which stiffens the dynamic response beyond 1.6. Pre-drying of OTOS powder to 0.15 % moisture maximum is required when the relative humidity in the storage bay exceeds 60 %, because moisture ingress during the injection phase causes a drop in Shore A hardness by 2–3 points and a visible blister formation after post-curing.High-Pressure Hydraulic Hose Liners and Their Resistance to Phosphate Ester Fluids at Elevated TemperaturesThe inner tube of a spiral‑wire‑reinforced hydraulic hose, conformant to SAE J517 100R12, is extruded from a NBR/PVC polyblend with an acrylonitrile content of 33–35 %, plasticised with a linear phthalate at 12 phr and stabilised with 2 phr of a zinc‑free antioxidant package. The compound is produced in a 140‑litre intermeshing mixer and then fed to a cold‑feed vented extruder with a 100‑mm screw diameter and a 14:1 L/D for tube extrusion onto a mandrel at wall-thickness tolerances of ± 0.1 mm. OTOS at 1.6–2.0 phr acts as the primary accelerator in combination with dipentamethylenethiuram tetrasulfide at 0.8 phr to control the crosslink density evolution during the long‑path steam cure at 155 °C for 90 min. The vulcanizate must past chemical resistance testing per ISO 1817 by immersion in oil‑based and phosphate‑ester hydraulic fluids at 100 °C for 168 h; the OTOS system restricts the change in volume to +5 % maximum and the drop in tensile strength to −15 % compared to original values. A mandatory million‑cycle impulse test at 133 % of rated working pressure forces the inner tube to withstand repeated deformation without cracking, and failure analysis on returned hose samples traced to inner‑liner spalling was eliminated when the OTOS loading exceeded 1.8 phr, because the tighter network morphology reduces the permeability of the phosphate ester into the polymer matrix. The restriction on using OTOS arises when the NBR/PVC blend contains zinc oxide at levels above 5 phr; the combination catalyses zinc‑accelerated hydrolysis of the PVC component above 120 °C, leading to acid‑catalysed debonding of the reinforcing wire layer over time, hence zinc oxide must be capped at 3.5 phr.OTOS‑Donor Cure Systems for Low‑Sulfur, High‑Modulus Rubber Shoe‑Sole CompoundsInjection‑moulded solid‑rubber shoe outsoles, typically moulded from a NR/SSBR blend with a high styrene content for hardness, require good wet‑grip indicators and dimensional stability over repeated flexing. When a high‑modulus compound is required with total sulfur below 1.2 phr to prevent staining on light‑coloured uppers, a semi‑efficient vulcanisation system pairing OTOS at 0.7–1.0 phr with tetramethylthiuram disulfide at 0.6 phr and an N‑morpholino‑2‑benzothiazole disulfide disulfide donor (DTDM) at 1.2 phr as the sulfur donor is used. The commissioning trials on a 12‑station rotary injection machine with mould temperatures of 160‑170 °C demonstrated that gate‑scarring defects were eliminated when the OTOS loading was lowered to 0.8 phr and the injection speed reduced to 18 mm/s, because the transient scorch measurement by rubber process analyser (RPA2000) at 150 °C gave a G’ transition time of 6.5 min, enabling the melt to heal behind the gate without pre‑set. A flex‑cracking test under ISO 4643 for 150,000 cycles at −5 °C yielded ≤ 2.5 mm cut growth, which is substantially below the 5.0 mm ceiling specified by a major athletic‑footwear brand’s material standard. The limitation found with this donor system is that the storage stability of the unvulcanised compound in a hot climate exceeds 72 h only when the formulated compound is sheeted out in slabs below 30 °C and wrapped in low‑permeability film; otherwise the Mooney viscosity increases by more than 10 % due to ambient moisture accelerating the donor decomposition at ≥ 32 °C.
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N-Oxydiethylene-2-Benzothiazole Sulfonamide — a benzothiazole derivative in which the sulfonamide nitrogen is incorporated into a morpholine ring — is supplied as a delayed-action primary accelerator for sulfur-vulcanizable diene elastomers. The product is offered in granular and oil-coated powder forms under grade designations that reflect minimum purity thresholds: OBS-98 (assay ≥ 98.0 %) and OBS-95 (assay ≥ 95.0 %), with the latter often containing a processing oil dispersion to suppress dusting during Banbury mixing. Unlike the structurally analogous sulfenamide accelerators such as N-oxydiethylene-2-benzothiazyl sulfenamide (NOBS) or N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), the sulfonamide linkage (–SO₂– versus –S–) reduces the lability of the accelerator-sulfur intermediate, yielding a measurably longer scorch delay and lower cure rate at equivalent molar loadings. This characteristic positions the material where compound flow distances are extreme or where thick-section vulcanizates demand a delayed onset of crosslinking to avoid cure reversion at the core. The following sections detail the operational specifications and application boundaries of OBS across rubber processing platforms.
| Property | OBS-98 | OBS-95 | Test Method |
|---|---|---|---|
| Assay (as C₁₁H₁₂N₂O₂S₂) | ≥ 98.0 % | ≥ 95.0 % | HPLC (internal standard) |
| Initial melting point | 105–109 °C | 102–108 °C | DSC at 10 K/min |
| Loss on drying (60 °C, vacuum) | ≤ 0.3 % | ≤ 0.5 % | ISO 787-2 |
| Sulfated ash | ≤ 0.3 % | ≤ 0.5 % | ASTM D4574 |
| Residue on 150 µm sieve | ≤ 0.1 % | ≤ 0.2 % | ISO 3310-1 |
| Oil content (naphthenic) | — | 1.0–2.0 % | Extraction (acetone) |
Comparing the vulcanization profile of OBS against NOBS at equal sulfur loadings reveals that the sulfonamide functionality raises the activation energy for the formation of the active sulfurating complex. In a model natural rubber formulation (SMR 20, 100 phr; N660 carbon black, 50 phr; ZnO, 5 phr; stearic acid, 2 phr; sulfur, 2.25 phr; accelerator, 1.0 phr), Mooney scorch times measured per ASTM D1646 at 135 °C are extended by approximately 30–45 % for OBS-98 relative to NOBS, while the cure time to t90 at 160 °C (ASTM D5289) increases by 3–5 minutes. This wider separation between scorch onset and full cure permits higher throughput in extrusion lines where compound reversion in the die head is a limiting factor. The data is summarized below, drawn from production-scale twin-screw extruder compounding trials with an L/D ratio of 32:1 and a die temperature of 145 °C.
| Parameter | OBS-98 (1.0 phr) | NOBS (1.0 phr) | CBS (0.8 phr) | Standard |
|---|---|---|---|---|
| Mooney scorch, t5 (min, 135 °C) | 18.2 | 12.4 | 14.1 | ASTM D1646 |
| MDR ts2 (min, 160 °C) | 3.7 | 2.3 | 2.8 | ASTM D5289 |
| MDR t90 (min, 160 °C) | 11.8 | 7.2 | 8.5 | ASTM D5289 |
| Tensile strength (MPa) | 24.5 | 25.1 | 25.6 | ISO 37 (dumbbell type 2) |
| Elongation at break (%) | 520 | 495 | 510 | ISO 37 |
Operational boundaries must be respected when exploiting this scorch delay. At mixing dump temperatures above 130 °C, OBS begins to undergo premature thermolysis, generating free morpholine and benzothiazole residues that nucleate incipient crosslinks. This threshold mandates that internal mixer ram pressure and rotor speed be regulated to keep batch temperature below 125 °C throughout the mixing cycle. Additionally, the compound must be pre-dried at 60 °C for a minimum of 2 hours whenever ambient relative humidity exceeds 60 %, as moisture absorbed onto the sulfonamide particle surface catalyzes hydrolysis to benzothiazole sulfonic acid, a potent scorch agent that reverses the intended delay effect. Combination with highly acidic fillers (pH < 4.5) such as untreated fumed silica is contraindicated; the acid environment decomposes the sulfonamide group within minutes at processing temperatures, leading to erratic cure kinetics and bloom on aged vulcanizates.
For continuous vulcanization of EPDM profiles, the controlled release of active accelerator species becomes critical when haul-off speeds exceed 25 m/min and the hot air tunnel temperature is maintained at 220–250 °C. OBS at loadings of 0.5–2.0 phr alongside sulfur (0.8–1.5 phr) and co-accelerators such as tetramethylthiuram disulfide (TMTD, 0.3–0.6 phr) generates a cure profile in which crosslinking initiates only after the compound exits the high-shear extruder die and enters the heated tunnel. This sequence avoids the formation of hard precured particles that can cause surface blemishes on sponge profiles tested per ISO 4651. Because the molecular weight of OBS (286.4 g/mol) is higher than that of common sulfenamides and its solubility parameter lies further from that of nonpolar EPDM backbones, migration to the vulcanizate surface is retarded; bloom-free storage of finished profiles at 40 °C and 90 % RH has been documented for over 12 weeks per ASTM D4619. Published data for this specific EPDM/OBS configuration at extremes of humidity cycling remains limited, and producers are advised to qualify long-term surface appearance with production-intent compound variants.
Injection molding of high-hardness technical goods (e.g., engine mounts, suspension bushings) presents a thermal paradox: nozzle and barrel temperatures must be elevated to achieve flow into multi-cavity molds, yet this same heat input narrows the scorch safety margin. OBS-98, employed at 0.8–1.5 phr with sulfur levels of 1.8–2.5 phr in NR/BR blends, extends the compound’s residence time allowance inside a reciprocating screw barrel with L/D 20:1 by 4–6 minutes compared to CBS when barrel set points are 115 °C. In a production audit on a 350-tonne machine with 16-cavity mold, the scrap rate attributable to scorched preforms dropped from 2.8 % to 0.7 % after switching to OBS, with no adjustments to the cure schedule. The oil-dusted OBS-95 grade is preferred for this application because the 1.5 % naphthenic oil coating promotes deagglomeration in the screw compression zone, reducing incorporation time by 12–15 seconds relative to the non-oiled powder, as measured via torque rheometry per ASTM D3795. A counter-indication is that OBS cannot serve as a sole accelerator in EV (efficient vulcanization) systems that demand sulfur levels below 0.6 phr; under such conditions, the sulfonamide produces insufficient active sulfurating species, and must be supplemented with a thiuram or dithiocarbamate booster to achieve a minimum crosslink density of 12 × 10⁻⁵ mol/cm³.
In silica-reinforced tire tread compounds, the interaction between silane coupling agents and accelerator chemistry often disrupts scorch safety margins because the silanization reaction releases ethanol that can hydrolyze conventional accelerators. OBS, owing to the higher hydrolytic stability of the sulfonamide bond compared with the sulfenamide bond, maintains scorch time integrity when processed with TESPT (Si69) at silane loadings of 8–12 % on silica weight. Dynamic mechanical analysis per ASTM D5992 on cured specimens (oscillating shear mode, 10 Hz, 60 °C) shows a tan delta value 0.08–0.10 when OBS is paired with a thiazole secondary accelerator, indicating that the slower cure profile allows greater polymer-filler interfacial accommodation before network lock-in. This contrasts with CBS-based stocks that routinely yield tan δ above 0.12 under identical mixing and curing conditions. Critically, OBS does not generate N-nitrosamines during vulcanization because the morpholine moiety is bonded through the sulfonamide group rather than the labile sulfenamide linkage; compliance with EU Directive 2005/69/EC is confirmed by headspace GC-MS analysis showing N-nitrosomorpholine content below the 0.1 ppm detection limit, a distinction from NOBS that categorically eliminates OBS from regulatory concern in European tire manufacturing.
Hot air aging at 100 °C for 72 hours (ASTM D573) reveals that OBS-cured natural rubber compounds retain 82–88 % of their original tensile strength and exhibit elongation retention above 78 %, whereas comparable NOBS and CBS formulations typically drop to 68–74 % tensile retention and frequently fall below 65 % elongation retention. The enhanced aging performance is attributed to the absence of free amine by-products that would otherwise catalyze post-oxidative chain scission; the sulfonamide decomposition pathway under thermal stress yields morpholine sulfonic acid, which is non-volatile and does not engage in further degradation of the polymer backbone. Crosslink density measurements by equilibrium swelling in toluene (using the Flory-Rehner equation with a χ parameter of 0.393) indicate that the network derived from OBS maintains 87 % of its initial crosslink density after 7 days of aerobic aging at 85 °C, while NOBS networks lose 22–28 % of crosslinks over the same interval. This stability is advantageous in under-hood automotive components—coolant hoses, grommets, vibration dampers—where intermittent exposure to temperatures of 110–135 °C and ethylene glycol vapor is routine. However, the slower cure kinetics of OBS become a limitation when cycle times must remain below 90 seconds for high-volume production; under such constraints, the material cannot deliver sufficient state-of-cure and should be partially replaced with a faster guanidine or thiuram accelerator to meet productivity targets without sacrificing the aging benefit.
