There are many factors that cause rubber aging. Studies have shown that the main factors are oxygen, ozone, trace metals, sunlight, ultraviolet rays and mold corrosion. Flexural fatigue mainly increases the contact area between rubber molecules and oxygen, thereby accelerating its aging.
In order to prevent the aging of rubber and products, a special component is added to the formula, which is an anti-aging agent!
Anti-aging agent heat resistance
The thermal aging of rubber is a kind of oxidative aging caused by free radicals, and amine or phenolic free radical blockers have a better effect on preventing this aging. For products requiring high heat resistance, heat-resistant antioxidants such as diphenylamine and TMDQ can be selected. Further, more excellent heat resistance can be obtained by using these radical inhibitors in combination with a peroxide decomposer such as an antioxidant MBI.
Flex Cracking Resistance
Flexural cracking is the result of oxidative aging on the surface of the product due to free radical reaction. To prevent this form of aging, the choice of amine or phenolic antiozonants (free radical inhibitors) has a role to play. Among them, the effect of large surface mobility is excellent.
Ozone resistance
Antiozonants include p-phenylenediamine, TMDQ, thiourea and protective wax, etc. Generally, the contaminating p-phenylenediamine compound and the non-polluting thiourea compound and paraffin are used together to obtain excellent performance. Effect. However, thiourea compounds have a tendency to remarkably accelerate scorch. In addition, since ozone aging occurs on the surface of a product, an antiozonant with a large surface migration is excellent in the effect. Recently, high molecular weight antiozonants are also being developed in order to make the antiozonants work continuously.
Resistance to Harmful Metal Aging
Anti-harmful metal aging agents can be divided into metal ion blocking agents and metal surface inerts. The former has excellent effect of p-phenylenediamine and bisphenol compounds, and the latter has thiol compounds (such as anti-aging agent MB) and triazine compounds. In order to obtain more excellent resistance to detrimental metal aging, the above-mentioned antioxidants can generally be used in combination with heat-resistant antioxidants.
Photocrack and aging resistance
Carbon black is an excellent UV absorber. Therefore, the anti-photoaging agent is unnecessary for carbon black compounding, and it is indispensable for light-colored products (carbon black is only used as a colorant). For the anti-photoaging combination, the first anti-aging agent and the second anti-aging agent are generally used together. Among the antioxidants, p-phenylenediamine antioxidants are particularly excellent in anti-photoaging effect, but have serious pollution. Among the non-polluting photoaging agents, phenolic, hindered amine antioxidants and paraffin wax are excellent in effect. Among the phenolic antioxidants, antioxidant DTBM P (2,6-di-tert-butyl-4-methylphenol), antioxidant sP (styrenated phenol), antioxidant MBMTB[2,2'-methylene Bis(4-methyl-6-tert-butylphenol)] and anti-aging agent MBETB[2,2fluoromethylenebis(4-ethyl-6-tert-butylphenol)] had better anti-photocracking and aging effects Excellent.
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