Commonly used antioxidants for rubber and selection principles
Anti-aging agents for rubber
There are many types of antioxidants, and each antioxidant has several house aging effects at the same time.

According to the chemical structure, they can be divided into: amines, phenols, heterocycles and other categories.

According to the protective effect can be divided into: anti-oxidation, anti-ozone, anti-fatigue, anti-harmful metals and anti-UV antioxidants.

The following chemical structure of the antioxidant classification is introduced.

1. Amine antioxidants.

Protection effect is the most prominent, the most varieties.

The main protective effect: thermal oxygen aging, ozone aging, thermal heavy metals and UV catalytic oxidation and fatigue aging have significant protective effect.

This type of antioxidant can be subdivided into: ketamine, aldehyde amine, diaryl secondary amine, diphenylamine, p-phenylenediamine and alkyl aryl secondary amine six types.

Ketamine
a. Anti-aging agent AW (reaction product of acetone and p-aminophenetole, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline))

Mainly used to prevent ozone aging and fatigue aging, while having good heat and oxygen aging properties, suitable for dynamic rubber products. With wax, antioxidant 4010 and other good effect, suitable for SBR, used in the manufacture of automotive tires, rubber shoes and other rubber products.

b. Anti-aging agent BLE (acetone and diphenylamine high temperature condensate)

Thermal oxygen aging, fatigue aging has a good protective effect, but also to improve the adhesive force of rubber and metal, pollution, not for light-colored products, more applications in the tire industry, in the hose, tape and other industrial products are also used.

c. Anti-aging agent RD (2,2,4-trimethyl-1,2-dihydroquinoline polymer)
Good compatibility in the rubber material, not easy to spray, there is a slight pollution, excellent protection against thermal and oxygen aging, poor protection against ozone aging and fatigue aging.



Aldehydes and amines

a. Anti-aging agent AH (acetaldehyde - α naphthylamine condensate)

Has excellent protection effect of thermal oxygen aging, has the effect of passivation of copper, iron, manganese and other heavy metal ions, pollution is more serious, there is an unpleasant odor in the vulcanized rubber made.


b. Anti-aging agent AP (3-hydroxybutyral-α-naphthylamine)

With good resistance to thermal and oxygen aging, used in the manufacture of wires, cables, rubber shoes, industrial products, etc.

Diaryl secondary amines
a. Anti-aging agent A (N-phenyl-α-naphthylamine)
b. Anti-aging agent D (N-phenyl-β-naphthylamine)

Diphenylamine
Less variety, less outstanding performance, less application.

p-phenylenediamine
This is the latest and is the most important class of antioxidants, this type of antioxidants for all types of aging have excellent protection performance, mainly to prevent ozone, fatigue and thermal oxygen aging, especially in the prevention of ozone, fatigue aging is not compared to other antioxidants. The main varieties are.

a. Anti-aging agent 4010 (CPPD)
Heat, oxygen, high-energy radiation and copper damage has a significant protective effect against ozone and flexural fatigue aging has excellent performance, better than the effect of antioxidant A and D, easy to disperse in the rubber, but the amount of more than 1 part will produce spray frost, pollution, not for light-colored products.

b. Anti-aging agent 4010NA (IPPD)
It has excellent protection effect on ozone and flex fatigue aging, good protection effect on thermal oxygen aging and photo-oxidation aging, and also has the effect of passivating heavy metal ions, its protection effect is more comprehensive than 4010 and has wider application.

It is suitable for NR, SBR, BR, CR, ZR and latex.

c. Antioxidant H (DPPD)
Anti-aging agent H is silver-white flake crystals, easy to oxidize and change color in the air and sunlight. Ozone and flexural fatigue aging has good protection, thermal oxygen aging and harmful metal catalytic aging also has good protection, and anti-cracking effect.

(6) alkyl aryl secondary amines
This type of antioxidant is less polluting, can be used for light-colored products, but the protection effect is poor. The main varieties are.
a. Anti-aging agent DPD
b. Anti-aging agent CMA

2. Phenolic antioxidants
This type of antioxidant can be divided into: replace a phenolic class, multi-phenolic class, sulfide di-substituted phenolic class and alkylene-supported di-substituted phenolic class.

①One element phenolic
Anti-aging agent 264
②Alkylene-disubstituted phenols
③Thiobisubstituted phenols
④Polyols

The effectiveness of antioxidants and binary phenols are generally similar. One of the most commonly used varieties of antioxidants DOD.

3. Heterocyclic and other types of antioxidants
Heterocyclic antioxidants in the main varieties of benzimidazole type and dithiocarbamates, the most important is the antioxidant MB and its zinc salt MBZ.

4. Non-migratory antioxidants
Harsh conditions will make the rubber in the antioxidant is easy to volatilization and extraction, so that it quickly consumed, affecting the protective effect. Therefore, it is necessary to study the non-volatile, non-extractable, non-polluting, non-toxic antioxidants, so a series of non-migratory antioxidants have emerged.
①reactive antioxidant
a. Chemical bonding of antioxidant and R during processing
b. Grafting of antioxidants onto rubber before processing.
c. Monomer with protective function copolymerized with rubber monomer.

②High molecular weight antioxidants