We know that the tire production process has long and complicated steps.One of the most important steps is the cooking step.In this step, different additives are added to the rubber mixture, each of which plays a special role in the production process according to their category.Accelerators are one of the most widely used additives in tires, which have different types.In this article, we try to know more about CBS.
Why do we need accelerators in rubber curing? Curax
Cross-linking or curing is a set of chemical reactions in which sulfur, carbon or hydrogen covalent bonds are created between polymer chains.The first sulfurization of rubber was done by Charles Goodyear in 1839 on natural rubber with elemental sulfur for 5 hours.
In the initial cooking, the rubber was cooked for 5 hours at a temperature of 141 degrees Celsius and a sulfur content of phr 3.By increasing zinc oxide as an activator, the curing time was reduced to 8 hours and by increasing the accelerator to 0.5 phr to 1 to 3 minutes.In fact, before the use of accelerators in the formulation of rubber compounds, cured rubber was not of commercial importance. The first organic accelerator was used in 1906.
After this year, various accelerators have been discovered and used.Accelerators are divided into primary and secondary groups.Primary accelerators are usually selected from the Sulfenamides group, which exhibit effective and safe curing.Secondary accelerators are used together with the primary accelerator to increase the curing speed, especially for manufacturing rubber industrial parts.
There are six main categories for classifying rubber accelerators in the industry, which separate them based on their application as well as their chemical structure:
How do rubber accelerators help to cure it?
Accelerators affect sulfur curing mechanism and tire compound curing speed.In industrial rubber mixing 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 characteristics of rubbers such as NR (natural rubber layers).
Benzothiazilsulfenamides 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 processing temperature is more effective and safer and has 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.And it is available in three forms: powder, oily powder, granule, 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.
Pars Khurshid Industrial Group is an importer and supplier of all kinds of raw materials for the rubber industry.Antioxidants, accelerators, ferroalloys and types of natural rubber are products of Pars Khurshid.
CBS is available in three forms: powder, oily powder, granular, white or light gray, which can be presented in different colors according to its application.CBS is odorless and non-toxic
Mbts Rubber Accelerator Sulfur curing mechanism with sulfenamide accelerator starts 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 after the reaction of persulfonyl radicals with sulfur-releasing complexes and, as a result, changes the cross-links structure and ultimately changes the mechanical properties of the mixture. It becomes rubbery.The formation of these bonds will cause the diversity of the structure of the transverse joints in terms of the formation of mono, di and polysulfide bridges, and of course, they provide a relatively favorable balance in the properties of rubber compounds including sulfenamide accelerators.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 is insoluble in water, and its activity can be enhanced by the 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.
Looking to learn more about the CBS Baking Accelerator?Contact the technical experts of Pars Khurshid.
How to store and pack CBS
CBS can be sold 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
Initial melting point: 97 degrees Celsius
Technical specifications of CBS Pars Shamim Rah Khurshid:
Appearance: light yellow to light pink granules
Pars Khurshid importer and supplier of rubber accelerators
The goal of Pars Khurshid is to improve the quality of the products produced in the rubber industry, therefore, by importing all kinds of raw materials of the rubber industry with high quality and global standards, it will contribute to this improvement.All kinds of antioxidants, accelerators and natural rubber as well as ferroalloys are available in Pars Khurshid's product portfolio with a wide variety.