THIOUREA SULFENAMIDE

Thiourea sulfenamide is a non-staining, primary accelerator for natural and synthetic rubbers such as EPDM, SBR, Nitrile, and Butyl, and is more efficient than other sulfenamide accelerators.
Thiourea sulfenamide is a vulcanizing agent and delayed accelerator, and has better scorch safety than Willing M and Willing MDB.
Thiourea sulfenamide can be utilized to produce excellent economical, semi-EV cure systems, with a preferred dosage ratio of 2 parts Thiourea sulfenamide to 1 part of another sulfenamide like BBTS or CBTS.

CAS Number: 13752-51-7
EC Number: 237-335-9
Molecular Formula: C9H16N2O2S2
Molecular Weight: 248.37

Synonyms: 4-[(4-Morpholinylthio)thioxomethyl]-morpholine, ACCELERATOR OTOS, CURE-RITE 18, N-OXYDIETHYLENE THIOCARBAMYL-N-OXYDIETHYLENE SULFENAMIDE, morpholin-4-yl morpholine-4-carbodithioate, 4-((4-morpholinylthio)thioxomethyl)-morpholin, 4-((morpholinothiocarbonyl)thio)-morpholin, 4-((morpholinothiocarbonyl)thio)morpholine;4-[(4-Morpholinylthio)thioxomethyl]-morpholine;Thiocarbamyl sulfenamide;OTOS, N-Oxydiethylenethiocarbamyl-N-oxydiethylene sulfenamide 4-[(4-Morpholinylthio)thioxomethyl]-morpholine ,4-[(4-Morpholinylthio)thioxomethyl]-morpholine,ACCELERATOR OTOS,CURE-RITE 18,N-OXYDIETHYLENE THIOCARBAMYL-N-OXYDIETHYLENE SULFENAMIDE,morpholin-4-yl morpholine-4-carbodithioate,4-((4-morpholinylthio)thioxomethyl)-morpholin,4-((morpholinothiocarbonyl)thio)-morpholin,4-((morpholinothiocarbonyl)thio)morpholine, Acceleratorotos, 13752-51-7, OTOS, Cure-Rite18, Morpholine,4-[(4-morpholinylthio)thioxomethyl]-, morpholin-4-ylmorpholine-4-carbodithioate

Thiourea sulfenamide is a chemical compound commonly used as an accelerator in the vulcanization of rubber.
Thiourea sulfenamide belongs to the sulfenamide class of accelerators, known for their delayed action and scorch safety, which helps prevent premature curing during rubber processing.

Structurally, Thiourea sulfenamide contains a thiourea group and a sulfenyl linkage bonded to an amine, contributing to its reactivity in sulfur-based curing systems.
Thiourea sulfenamides are particularly effective in improving the crosslinking efficiency, mechanical strength, and aging resistance of rubber materials such as natural rubber (NR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), and ethylene propylene diene monomer (EPDM).

Thiourea sulfenamides are typically found as pale yellow powders or granules and are only slightly soluble in water.
While highly useful industrially, they should be handled with care, as they may cause skin or eye irritation and must be stored under dry, ventilated conditions away from oxidizing agents.

Thiourea sulfenamide compounds are an important class of chemicals used primarily in the rubber industry.
They serve as accelerators in the vulcanization process of rubber.
Vulcanization is a chemical process that involves the addition of sulfur or other equivalent curatives or accelerators to rubber to improve its elasticity and strength.

Thiourea sulfenamide is a non-staining, primary accelerator for natural and synthetic rubbers such as EPDM, SBR, Nitrile and Butyl.
Thiourea sulfenamide is more efficient than other sulfenamide accelerators.

As a result, a 25% reduction in the sulfenamide portion of an accelerator system is possible when Thiourea sulfenamide is used.
This substitution will result in no loss of cure rate while maintaining good physical properties

Thiourea sulfenamide is a specialized chemical compound widely used in the rubber industry as an accelerator in the sulfur vulcanization process.
Belonging to the broader class of sulfenamide accelerators, thiourea sulfenamides are valued for their delayed action and high scorch safety, which allow for improved processing times and reduced risk of premature vulcanization (also known as “scorching”) during mixing and molding operations.

Structurally, thiourea sulfenamides are characterized by the presence of a thiourea functional group (–CSNH₂), which is bonded through a sulfenyl linkage (–S–) to an amine moiety.
Thiourea sulfenamide structure gives the compound a balance between reactivity and stability, making it an ideal secondary accelerator when used in conjunction with primary accelerators such as thiazoles or other sulfenamides.

In practical applications, thiourea sulfenamides are commonly employed in the formulation of synthetic and natural rubber compounds, including natural rubber (NR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), and ethylene propylene diene monomer (EPDM) rubber.
When added to rubber formulations, they enhance the efficiency of crosslinking by interacting synergistically with sulfur and other accelerators, resulting in vulcanizates with superior mechanical strength, heat resistance, elasticity, and aging performance.
This makes them especially useful in the production of tires, industrial belts, hoses, seals, and other high-performance rubber goods where durability and resilience are critical.

Thiourea sulfenamides are typically available in the form of white to pale yellow powders or granules.
They are generally stable under standard storage conditions but are only sparingly soluble in water and are more soluble in certain organic solvents.

Despite their usefulness, these compounds must be handled with caution.
They can act as skin and eye irritants and may pose health risks if inhaled or ingested.
Therefore, proper personal protective equipment (PPE), such as gloves and goggles, should be used during handling, and the material should be stored in a cool, dry, and well-ventilated environment away from sources of ignition and incompatible substances, particularly oxidizing agents.

Overall, thiourea sulfenamides represent a critical component in modern rubber chemistry, offering a fine balance of processing safety and cure performance.
Their continued use and development are essential for meeting the growing demands of high-quality, durable elastomeric products in automotive, industrial, and consumer markets.

Applications of Thiourea sulfenamide:
Thiourea sulfenamide is a primary accelerator for NR,SBR,EPDM etc.
Thiourea sulfenamide is a vulcanizing agent and delayed accelerator, and has better scorch safety than Willing M, Willing MDB.
Thiourea sulfenamide's critical temperature is 149οC.

Thiourea sulfenamide can be utilized to produce excellent economical, semi-EV cure systems.
The preferred dosage ratio is 2 parts Thiourea sulfenamide to 1 part of another sulfenamide like BBTS or CBTS.

Sulfur loading should be kept low, 0.4 to 0.6 PHR.
Thiazoles may be used in place of the sulfenamides to speed up the cure rate and reduce reversion in natural rubber.

Heat aging and compression set properties are outstanding.
Processing properties are excellent, providing fast cure rates with good scorch safety.

Thiourea sulfenamide is also available as a polymer bound dispersion (Akrochex OTOS-70/EPR/C-LB).
Polymer bound or encapsulated dispersions are a proven means of upgrading plant safety, efficiency, quality and raw material control. 

Rubber Industry:

Tires:
They are extensively used in the production of tires due to their ability to improve the mechanical properties of the rubber.

Industrial Rubber Goods:
Other applications include belts, hoses, gaskets, and various molded goods where enhanced durability and performance are required.

Chemical Intermediates:
In some cases, they are used as intermediates in the synthesis of other chemical compounds.

Chemical Structure and Composition

Thiourea sulfenamides typically have the following general structure:
R1N−C(=