This paper describes four p-phenylenediamine antioxidants, namely antioxidants 6PPD, 7PPD, 77PD and EPPD. their basic properties, synthesis methods and scope of use in rubber products are summarized. In particular, these four antioxidants are more closely related to each other than to other antioxidants because of the similarity in their synthesis methods and the complementary nature of their static ozone resistance and dynamic oxidation resistance.

In recent years, China's rubber and rubber auxiliary industry has been developing rapidly, at the same time, rubber auxiliaries represented by p-phenylenediamine antioxidants are developing in the direction of cleanliness and multifunctionality. The traditional p-phenylenediamine antioxidants are 6PPD and 4010NA, and there has been an overcapacity.

Antioxidant 6PPD is a highly efficient multifunctional low-toxicity product, mainly used in the rubber industry, is currently the most important varieties of p-phenylenediamine antioxidants. In natural and synthetic rubber, antioxidant 6PPD has good protection against ozone and flexural aging, and good protection against oxygen, heat and other general aging and copper, manganese and other harmful metals.

Antioxidant 7PPD is a kind of anti-ozone protective agent with excellent performance for all kinds of rubbers, which is generally used in conjunction with some other antioxidants.

Antioxidant 77PD as natural rubber and various synthetic rubber effective anti-ozone protective additives, its static anti-ozone aging effect is very good, obviously better than the anti-ozone aging performance of the antioxidant 4010NA and 6PPD, especially suitable for long-term static conditions in the wire and cable, hoses, tapes and other outdoor use of rubber products, also can be used in the general industrial rubber products.

Rubber antioxidant EPPD, as an emerging green rubber antioxidant, is a mixture of p-phenylenediamine rubber antioxidant, which is made of antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (antioxidant 6PPD) and N-(1,4-dimethylpentyl)-N'-phenyl-p-phenylenediamine (antioxidant 7PPD) compounded in a certain proportion.