1. Anti-scorch agent

Also known as vulcanization retarder, or scorch inhibitor and retarder, it is a substance that prevents early vulcanization of rubber compounds during processing. English name: anti-scorching agent; vulcanization retarder.

2. The purpose of using anti-scorch agent

In the rubber industry, with the development of production and the improvement of the performance of rubber products, the problem of increasing heat generation of rubber during processing has appeared one after another. Therefore, how to ensure the safety during processing has become an important issue. The main method used now is to add a small amount of anti-scorch agent during the process to improve the safety of the processing process and increase the storage life of the rubber compound or glue. The scorch agent can often easily meet the requirements for the scorch performance of the rubber compound. During storage and processing, the rubber compound will undergo early vulcanization (crosslinking) and lose its fluidity and ability to reprocess due to the action of heat, which is the phenomenon of scorch. Scorching of rubber compounds is one of the common problems in rubber processing. In the modern high-temperature, fast and efficient processing technology and the use of compounding agents that are easy to cause scorching (such as reinforcing resins, meta-formaldehyde system binders) , fine particle carbon black, etc.), the scorch problem is more likely to occur. Scorch can be solved by adjusting the vulcanization system, but be careful to cause changes in the properties of the rubber compound; the storage or processing conditions of the rubber compound can be improved by cooling, but complex equipment is required, and it is simple and easy to use an anti-scorch agent to prevent scorch method. Therefore, the anti-scorch agent has become an important operational aid for the safety of rubber processing.

3. Classification of anti-scorch agents and common products

Generally, it includes organic acids (such as benzoic acid, phthalic anhydride, etc.), nitroso compounds (such as N-nitroso diphenylamine, etc.) and thioimides (such as N-cyclohexylthio phthalobenzene) Dicarboximide) etc. Commonly used are oxalic acid, succinic acid, lactic acid, phthalic anhydride, salicylic acid, benzoic acid, oleic acid, etc. Among them, 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 often. Some accelerators also have the effect of preventing scorch on certain rubbers (such as TMTM and TMTD for neoprene). The commonly used anti-scorch agent CTP (N-cyclohexylthiophthalamide) has a good anti-scorch effect, and the scorch time can be effectively controlled by using the usual dosage.

① Organic acids. Such as salicylic acid, benzoic acid, phthalic acid, phthalic anhydride. Such chemicals have weak anti-scorch ability and large selectivity for accelerator varieties, which will reduce the vulcanization speed and vulcanizate performance, and have a stimulating effect on the skin. Among them, phthalic anhydride is more commonly used, which can be used for light-colored rubber products, and is only effective for alkaline accelerators DPG and MBT accelerators, but not for NOBS and TMTD.

②Nitroso compounds. N-nitrosodiphenylamine, N-nitroso-phenyl-β-naphthylamine, N-nitroso-2,2,4-trimethyl-1,2-dihydroquinoline polymer. Among them, N-nitrosodiphenylamine (NDPA) is commonly used. Different from organic acids, this kind of anti-scorch agent has better anti-scorch effect on commonly used thiazole and sulfenamide accelerators.

③Thioimides. It is a series of compounds containing S-N bonds, and different R groups can obtain scorch retarders with different properties. Among them, the anti-scorch agent CTP (PVI) is a better anti-scorch agent. All anti-scorch agents should meet the requirements of rubber processing performance, that is, have good anti-scorch performance; the selectivity of co-accelerator and coke species is small, insensitive to other compounding agents, and has no adverse effect on the vulcanization characteristics of the rubber compound and the performance of the vulcanizate , stable storage and good operating performance, no caking, no flying, easy to disperse, no frost, and meet the requirements of process safety and hygiene.

④Environmentally friendly anti-scorch agent E

It is a good environment-friendly anti-scorch agent for natural rubber and synthetic rubber. Applicable to EPDM, NBR and HNBR, prolong the scorch time without affecting the vulcanization speed. It is suitable for thiuram vulcanization system and can be used as a second accelerator to reduce vulcanization time and improve production efficiency. No pollution, no discoloration can be used for light-colored products. At the same time, the vulcanization crosslinking density of EPDM and NBR compounds is increased, the tensile stress is increased, and the compression deformation is reduced. No harmful substances are produced during the vulcanization process. For automobile sealing strip, dosage: 0.5-1.5 servings.

Contact information:

Jason
Henan Xuannuo Chemical Co., Ltd
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