The rubber accelerator refers to a rubber vulcanization accelerator. The vulcanization of rubber is mainly carried out using sulfur, but the reaction of sulfur with rubber is very slow, so vulcanization accelerators have emerged. The addition of the accelerator to the rubber compound can promote the activation of the vulcanizing agent, thereby accelerating the crosslinking reaction between the vulcanizing agent and the rubber molecule, thereby achieving the effects of shortening the vulcanization time and lowering the vulcanization temperature. The main use of vulcanization accelerators are mainly sulfenamides, thiazoles, thiurams, and some terpenoids, thioureas and dithiocarbamates. Among them, sulfenamides have the best comprehensive performance and are the most widely used.
The rubber accelerator is an after-effect accelerator for natural rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber and reclaimed rubber. It is usually used in the manufacture of cables, tapes, rubber shoes, inner tubes, bright colors, etc., especially for alkalis. Strong carbon black rubber compound. It is safe at operating temperature, strong in scorch resistance, fast in vulcanization speed and high in tensile strength, which can increase the proportion of synthetic rubber used. Low toxicity and high efficiency, it is an ideal substitute for NOBS and has excellent comprehensive performance. It is called standard accelerator. Widely used in the production of radial tires. It can be used in combination with aldehyde amines, anthraquinones, and thiuram accelerators. When used in combination with the scorch retarder PVI, it forms a good vulcanization system. Mainly used in the manufacture of tires, rubber shoes, hoses, tapes and cables.
The vulcanization mechanism of rubber is still mixed. This is because in the production of rubber products, there are insoluble natural rubber samples and a large number of simultaneous reactions, making it difficult to vulcanize rubber molecules into complex polymer networks. The mechanism can be roughly divided into two types: free radical mechanism and ion mechanism. Researchers such as Bacon and Famer et al. believe that the allylic resonance of the rubber makes it easy to replace the hydrogen on the adjacent methylene group of the double bond.
Therefore, in the vulcanization process of rubber, the sulfur double radical scavenging hydrogen on the rubber a-methylene group is the beginning of the reaction. That is, the process of the reaction is a free radical process. Bateman et al. believe that the power supply of the double bond on the rubber causes the -SS- bond of S8 to break and decompose into ions, that is, the vulcanization process is an ion reaction process. So far, the more mature research is the vulcanization promoting mechanism of thiazole zinc salt and zinc dithiocarbamate.