CBS; Rubber accelerator

CBS is a sulfonamide accelerator suitable for natural rubber and synthetic rubber. CBS can provide fast and efficient mixing without burning or destroying physical properties. Quality CBS provides high tensile strength vulcanization and is retarded at normal temperatures.

This accelerator (benzothiazil sulfenamides) is one of the first group of six rubber accelerators, Sulfenamides, and it is the main accelerator of rubber curing.

CBS rubber curing accelerator

Benzothiazil sulfenamides are in the first group of these substances and are the main sulfur curing accelerators that are used in the rubber industry today. The role of these materials in baking is that they delay the time of cross-linking so that baking does not take place at the processing temperature. For example, mixing, extrusion, etc. Once the compound rubber is at curing temperature, these materials enhance the curing speed.

CBS is one of these accelerators. CBS, also known as CZ, is a medium to fast primary sulfonide accelerator suitable for EPDM, NBR, SBR, NR, IR, HR. Using this product at normal temperature is a more effective and safer process and a shorter washing time. The reason of rapid mixing does not cause burning or destroy physical properties. This substance is used as a secondary accelerator in combination with other accelerators as a vulcanization regulating agent that slows down vulcanization. It is available in three forms: powder, oily powder, granular, white or light gray, which can be provided according to the customer’s request, and it has a slight odor and is non-toxic. Due to its bitterness, it cannot be used in products that are in frequent contact with food. It is used as a secondary accelerator along with other accelerators.

CBS CBS is considered as a regulator of vulcanization and slows down its process. In this way, during the operation of the crosslink, it creates a delay in the baking process so that the baking is not done at the temperature of the process. Once the rubber mixture is at curing temperature, CBS enhances the curing speed. After cooking, it has very good physical properties and is completed quickly.

This accelerator is hardly soluble in benzene, toluene, acetone, chloroform, ethyl acetate. It is completely insoluble in water. CZ activity is enhanced with accelerators such as thiuram alkali accelerator and dithiocarbamate.

CBS is bitter and should not be used in products that are in constant contact with food products.

Soluble in benzene, toluene, acetone, chloroform, ethyl acetate, hardly soluble in alcohol and insoluble in water, and its activity can be enhanced by the alkaline accelerators thiuram and dithiocarbamate. Due to its bitterness, it cannot be used in products that are in frequent contact with food.

CBS is used in the production of various rubber products such as rubber, rubber hose, rubber shoes, all kinds of cables and cable insulation, as well as conveyor belts.

How do rubber accelerators help to cure it?

Accelerators affect sulfur curing mechanism and tire compound curing speed. In industrial rubber compounding process, the scorch time (formation of mixture molecules) must be long enough to prevent the rubber from burning before the mold cavity is completely filled. Of course, this process should not be too long, because the speed of production will decrease. An accelerator that has a completely safe cooking temperature and is able to cook quickly can be considered as an ideal option.

The addition of secondary accelerators can provide faster curing in rubber curing systems. The choice of an accelerator in the sulfur curing system determines the type of cross-links structure produced and thus the properties of the desired material. The selected accelerator affects the curing speed, the safety of the process, as well as the number and type of cross-links formed.

Cyclohexyl benzothiazyl sulfenamide or “CBS” is commonly used for cross-linking rubber-sulfur compounds. Now, the use of ultra-fast accelerators such as tetramethyl thiuram disulfide (TMTD) and zinc diethyl dithiocarbamate (ZDEC) has begun to improve the curing properties and other properties of rubbers such as NR (natural rubber layers).

How is CBS activated?

Sulfur curing mechanism with sulfenamide accelerator begins with the formation of various sulfurizing complexes including accelerator, activator and sulfur. After that, the intermediate species react with the rubber molecules to form the substance needed to form crosslinks and persulfonyl radicals are formed. Persulfonyl radicals can be adsorbed to other rubber molecules to form three-dimensional networks or re-react with sulfur-releasing complex species to form chain radicals ready for cross-linking. A step in which persulfonyl radicals react with sulfur-releasing complexes provides sufficient safety for rubber flow and mold cavity filling. Sulfenamide accelerators form a significant amount of sulfur-releasing complexes, this process delays the start of the curing process due to the reaction of persulfonyl radicals with sulfur-releasing complexes and, as a result, changes the cross-links structure and ultimately changes the mechanical properties. The mixture becomes rubbery. The formation of these bonds will cause the diversity of the structure of transverse connections in terms of the formation of mono, di and polysulfide bridges, and of course, a relatively favorable balance in the properties of rubber compounds including sulfenamide accelerators.

they prepare. The CBS accelerator has the fastest curing speed and the lowest activation energy compared to other sulfonamide accelerators, because the CBS accelerator produces a higher amount of amine species than other sulfonamide accelerators, and also has a complex structure with zinc ions. It forms sulfur as a ligand in cooking.

Solubility of CBS in different solvents

CBS soluble in benzene, toluene, acetone, chloroform, ethyl acetate is hardly soluble in alcohol and insoluble in water, and its activity can be enhanced by alkaline accelerators thiuram and dithiocarbamate.

What are the uses of CBS?

CZ rubber accelerator is used as a medium fast primary accelerator for natural rubber, isoprene rubber, styrene butadiene rubber and nitrobutadiene rubber. It is used in the manufacture of rubber, rubber inner tube, rubber belts, rubber shoes, cables and other industrial rubber products. It is used as a secondary accelerator in combination with other accelerators to adjust the speed of vulcanization. It is mainly used in the production of rubber, rubber hose, rubber shoes and cables, etc. types of rubber products. Mechanical types such as protectors, casings, air hoses, conveyor belts, driving belts, hoses, cable insulation are also used.

How to store and pack CBS

CBS is available in 25 and 20 kg packages in the market and should be kept in a dry and cool place, and the shelf life of CBS is 12 months.

Technical specifications of tetramethyl thiuram disulfide

Chemical name N-Cyclohexyl-2-benzothiazole sulfenamide

Molecular formula C13H16N2S2

Molecular weight: 264.4 g/mol

Specific weight: 1.29

Initial melting point: 97 degrees Celsius

Melting point: 99 degrees Celsius

Humidity: maximum 5%

Ash: maximum 5%

Free amines: 0.5% max

Oil amount: 1-2%

Sulfur: 24/7-23%