Antioxidants are additives that inhibit or delay the degradation of polymers by the action of oxygen or ozone in the atmosphere, and are some of the most widely used additives in rubber.
The classification of antioxidants used in rubber tires are the following.
1. Aromatic amine antioxidants.
Aromatic amine antioxidants, also known as rubber antioxidants, are the main antioxidants used in the processing of rubber tires. Important aromatic amine antioxidants are diphenylamine, p-phenylenediamine and dihydroquinoline and other compounds and their derivatives or polymers, available in natural rubber, styrene-butadiene rubber, neoprene.
Aromatic amine antioxidants performance characteristics: significant antioxidant effect, low price, can make the product discoloration (limit their application in light-colored and white products.)
2, hindered phenolic antioxidants.
Hindered phenolic antioxidant is the main antioxidant for rubber tires, according to the molecular structure is divided into monophenols, biphenols, polyphenols, nitrogen heterocyclic polyphenols and other varieties. In the use of rubber tire processing is mainly used in monophenols, bisphenol antioxidants, such as BHT, 2246, bisphenol A and other products.
Hindered phenolic antioxidants (monophenols, bisphenols) performance characteristics: significant thermal oxidation effect, will not pollute the product, volatility and migration, easy to color.
3, sulfite and sulfur-containing antioxidants.
In the rubber tire processing with auxiliary antioxidants are mainly sulfite and sulfur-containing antioxidants.
Sulfite and sulfur-containing antioxidants performance characteristics: can decompose peroxide, chelate metal and Lewis acid, and other antioxidants have a good synergistic effect, while giving rubber tires thermal stability and light stability, passivation of harmful metals, slow polymerization.
4、Compound antioxidant.
Different types of primary and secondary antioxidants or the same type of antioxidants with different molecular structures, there are differences in the function and application effect, a variety of the length of the composite antioxidant from two (or more) different types or different varieties of the same type of antioxidant compounding, in the rubber tire processing can be complementary to the strengths and weaknesses of the minimum amount of addition, the lowest cost and achieve the best anti-thermal oxygen aging effect.