Antioxidants
The auxiliaries that suppress the thermal oxidation degradation of polymer resins as the main function belong to the category of antioxidants. Antioxidants are the most important type of plastic stabilizing auxiliaries. Almost all polymer resins are involved in the application of antioxidants. According to the mechanism of action, traditional antioxidant systems generally include primary antioxidants, auxiliary antioxidants, and heavy metal ion passivators.
The main antioxidant is mainly used to capture the peroxy radicals of polymers. It is also known as "peroxy radical scavenger" and "chain-terminated antioxidant", involving two major aromatic amine compounds and hindered phenolic compounds. Series products. The auxiliary antioxidant has the function of decomposing the polymer peroxygen compound, also known as "peroxide decomposer", including thiodicarboxylic acid esters and phosphite compounds, usually used in conjunction with a primary antioxidant. Heavy metal ion passivation agent commonly known as "anti-copper agent", can complex transition metal ions, to prevent its catalyzed oxidation degradation of polymer resin, typical structures such as hydrazide compounds.
In recent years, with the deepening of the theoretical research of polymer anti-oxidation, the classification of antioxidants has also undergone certain changes. The most prominent feature is the introduction of the concept of “carbon radical scavenger”. The radical scavenger is different from the traditional primary antioxidants. They can capture polymer alkyl radicals, which is equivalent to adding a line of defense in the traditional antioxidant system.
Such stabilizing auxiliaries are currently reported to include mainly aryl benzofuranone compounds, bisphenol monoacrylate compounds, hindered amine compounds, and hydroxylamine compounds, and their primary antioxidants and auxiliary antioxidants. The ternary anti-oxidation system composed of the agent can significantly improve the anti-oxygen stabilization effect of the plastic products. It should be noted that amine antioxidants are stain-staining and are mostly used in rubber products, while phenolic antioxidants and their composite antioxidants, which are composed of ancillary antioxidants and carbon radical scavenger, are mainly used in plastics and cosmetics. Color rubber products.
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