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DESCRIPTION
N-Cyclohexyl-2-benzothiazole sulfenamide, commonly referred to as CBS or CBS accelerator, is an important chemical compound widely used in the rubber industry as a vulcanization accelerator.
N-Cyclohexyl-2-benzothiazole sulfenamide is part of the sulfenamide class of accelerators, known for their ability to enhance the cross-linking of rubber with sulfur during vulcanization.
Cas Number: 95-33-0
SYNONYMS
Cyclohexylbenzothiazole sulfenamide,N-Cyclohexylbenzothiazole-2-sulfenamide,N-(Cyclohexyl)-2-benzothiazolesulfenamide,CBS Accelerator,Santocure-CBS (Trade name),Accelerator CBS,N-Cyclohexylbenzothiazole sulfenamide,2-Benzothiazolesulfenamide, N-cyclohexyl-
N-Cyclohexyl-2-Benzothiazole Sulfenamide (CBS) is a critical vulcanization accelerator widely used in the rubber industry.
N-Cyclohexyl-2-benzothiazole sulfenamide has garnered significant attention due to its efficiency in improving the mechanical properties of vulcanized rubber.
In this article, we provide a detailed analysis of CBS, including its chemical properties, synthesis methods, applications, environmental impact, and advancements in research.
The goal is to offer a comprehensive overview for researchers and industrial professionals working in materials science and rubber technology.
The vulcanization process is a cornerstone of modern rubber manufacturing.
It involves the introduction of cross-links between polymer chains to improve elasticity, durability, and thermal stability.
Accelerators like CBS play an essential role in this process, enhancing the reaction rate and enabling better control over the properties of the final product.
By reducing the energy and time required for vulcanization, CBS allows manufacturers to achieve consistent quality and efficiency in rubber production.
This article delves deeply into CBS's chemistry, applications, and the challenges associated with its use.
Chemical Properties of CBS
Molecular Structure
CBS, with the chemical formula C13H16N2S2, is a sulfenamide-based compound.
Its structure comprises a benzothiazole ring attached to a cyclohexyl group through a sulfenamide linkage.
The molecular weight of CBS is approximately 268.4 g/mol.
This specific structure allows CBS to act as an effective precursor for generating active sulfur species during vulcanization.
The benzothiazole ring provides stability, while the cyclohexyl group enhances solubility in rubber matrices.
Physical Properties
Appearance: CBS appears as a pale yellow to light brown crystalline powder, often used in a finely ground form for uniform mixing.
Melting Point: The melting point ranges from 97–103 °C, indicating moderate thermal stability.
Solubility: While CBS is slightly soluble in water, its solubility in organic solvents like acetone, benzene, and ethanol makes it suitable for various industrial applications.
Stability: CBS remains stable under ambient conditions but decomposes upon prolonged exposure to elevated temperatures or strong acids, forming benzothiazole derivatives.
Chemical Reactivity
The sulfenamide functional group in CBS is highly reactive under vulcanization conditions.
Upon heating, it generates free radicals and active sulfur species that facilitate cross-linking in rubber.
The delayed-release mechanism of CBS minimizes premature vulcanization, making it a preferred choice for industrial rubber production.
Synthesis of CBS
Precursor Chemicals
The primary precursors for CBS synthesis are 2-mercaptobenzothiazole (MBT) and cyclohexylamine.
MBT is synthesized from aniline and carbon disulfide through a sequence of reactions involving nitration, reduction, and cyclization.
Cyclohexylamine is derived from cyclohexanol or cyclohexanone through reductive amination.
Industrial Synthesis Process
Reaction Stage: MBT is treated with cyclohexylamine in the presence of sulfenylating agents like sulfur chloride or sulfur dichloride.
The reaction typically occurs in a solvent medium, such as toluene or xylene, under controlled temperature and pressure conditions.
Purification Stage: The crude product is purified using recrystallization or solvent extraction techniques.
Solvents like ethanol or methanol are commonly employed to remove impurities and ensure high purity.
Quality Control: The synthesized CBS undergoes rigorous quality control to confirm its structural integrity and purity.
Techniques like Nuclear Magnetic Resonance (NMR), Infrared (IR) spectroscopy, and High-Performance Liquid Chromatography (HPLC) are used for characterization.
Challenges in Synthesis
Despite its widespread use, the synthesis of CBS presents challenges, including environmental concerns related to waste byproducts.
Innovations in green chemistry and alternative synthetic routes are being explored to mitigate these issues.
Applications of CBS
Role in Vulcanization
CBS is a primary accelerator in the vulcanization process, significantly enhancing the reaction kinetics.
It reduces the activation energy required for sulfur cross-linking, allowing rubber to achieve desired mechanical properties.
CBS’s delayed-action mechanism provides manufacturers with greater control over processing times, reducing the risk of scorch.
Industrial Use Cases
Automotive Tires: CBS is extensively used in the production of tires due to its ability to enhance durability, wear resistance, and heat dissipation.
It contributes to the overall safety and performance of tires.
Industrial Belts and Hoses: Rubber belts and hoses require high tensile strength and elasticity, which CBS helps achieve.
Consumer Goods: Products like footwear, rubber mats, and seals benefit from the superior properties imparted by CBS during vulcanization.
Specialty Applications: CBS is also used in high-performance rubber materials for aerospace and defense applications, where precise mechanical and thermal properties are critical.
Advances in Research
Improved Synthesis Techniques
Researchers are exploring greener and more efficient methods for synthesizing CBS.
Techniques such as microwave-assisted synthesis and solvent-free reactions have shown potential to reduce environmental impact while maintaining high yields.
Alternative Accelerators
While CBS remains a dominant accelerator, alternatives like organic peroxides, ionic liquids, and hybrid accelerators are gaining attention.
These alternatives aim to combine performance with sustainability but face challenges in achieving cost-effectiveness and scalability.
Material Innovations
Integrating CBS with nanomaterials, such as carbon nanotubes and graphene, has led to significant enhancements in the mechanical, thermal, and electrical properties of vulcanized rubber.
Such innovations are paving the way for advanced rubber composites with multifunctional capabilities.
N-Cyclohexyl-2-Benzothiazole Sulfenamide (CBS) continues to be a cornerstone of the rubber industry, offering unmatched performance as a vulcanization accelerator.
Despite its environmental challenges, ongoing research into sustainable synthesis methods and alternative accelerators promises a more eco-friendly future.
This article highlights CBS’s critical role in materials science and underscores the importance of innovation in addressing the evolving demands of industry and environmental sustainability.
SAFETY INFORMATION ABOUT N-CYCLOHEXYL-2-BENZOTHIAZOLE SULFENAMIDE
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
