What is scorch retarder and its role in the rubber industry

Anti-scorching agent: A substance that prevents the rubber compound from producing early vulcanization during processing.

English name: anti-scorching agent; vulcanization retarder

Generally, it includes nitroso compounds (such as N-nitrosodiphenylamine), organic acids (such as benzoic acid, phthalic anhydride, etc.) and thioimines (such as N-cyclohexylthioortho-benzene). Diimide) and the like. Commonly used are oxalic acid, succinic acid, lactic acid, phthalic anhydride, salicylic acid, benzoic acid, oleic acid, etc., of which phthalic anhydride and salicylic acid are used more. However, these substances affect the physical and mechanical properties of the finished product and should not be used more. In recent years, the new scorch retarder CTP (N-cyclohexylthiophthalamide) has excellent anti-coke effect, and the scorch time can be effectively controlled by the usual holding amount.

The purpose of using a scorch retarder in rubber compounds

In the rubber industry, with the development of production and the improvement of the performance of rubber products, the problem of increased heat generation during rubber processing has appeared. Therefore, ensuring safety during processing has become a very important issue. The main method currently used is to add a small amount of scorch inhibitor (or scorch inhibitor, retarder) during the process to improve the safety of the process and increase the storage life of the glue or glue. When adjusting the vulcanization system is difficult to achieve the required operational safety, the addition of the scorch retarder can easily meet the requirements for the scorch performance of the rubber compound. Although the amount of the scorch retarder is very small, it has more or less adverse effects on the properties of the rubber compound after being blended into the rubber compound, so it is generally not used as much as possible.

Rubber processing and scorch retarder

During the storage and processing, the rubber will undergo early vulcanization (crosslinking) due to heat and lose its fluidity and reprocessing ability. This is the scorch phenomenon. The scorch of rubber is one of the common problems in rubber processing. Especially in the high-temperature, fast and efficient processing technology of modern features and the use of compounding agents (such as reinforcing resin, meta-white system adhesive, fine particle carbon black, etc.) which are easy to cause scorch, the scorch problem is more likely to occur. . Scorch can be solved by adjusting the vulcanization system, but care should be taken to cause changes in the properties of the compound; cooling can be used to improve the storage or processing conditions of the compound, but complex equipment is required. It is now widely accepted that the use of a scorch retarder is the easiest way to prevent scorch. Therefore, the scorch inhibitor is an important operational aid for rubber processing safety.