Thermal aging of rubber is a kind of oxidative aging caused by free radicals. Amine or phenol free radical retardant is effective in preventing this aging. For products requiring high heat resistance, diphenylamine and TMDQ are available. In addition, the combination of these free radical inhibitors and peroxide decomposers such as anti-aging agent MB can provide better heat resistance.
2、Flex cracking resistance
Flexural cracking is the result of oxidative aging of product surface caused by free radical reaction. To prevent this form of aging, the selection of amines or phenols (free radical inhibitors) has a role. Among them, the effect of surface migration is excellent.
3、The ozone resistance
Anti-ozone agents include p-phenylenediamine, TMDQ, sulfur diamine and protective wax, etc. Generally, the combination of polluting p-phenylenediamine and non-polluting sulfur diamine and paraffin can obtain excellent results. However, sulfur compounds have a significant tendency to accelerate coke burning. In addition, ozone aging is produced on the surface of products, so the surface migration of anti-ozone agent is excellent. Recently, high-molecular weight anti-ozonants have been developed to make them more sustainable.
4、Anti-aging of harmful metals
Anti - harmful metal aging agents can be divided into metal ions blocking agents and metal surface inert agents. The former has excellent effects of p-phenylenediamine and bisphenol compounds, while the latter has mercaptan compounds (such as anti-aging agent MB) and triwort compounds. In order to obtain better anti-aging properties of harmful metals, the aforesaid anti-aging agent can be used with heat-resistant anti-aging agent.
5、Aging resistance to light cracking
Carbon black is an excellent uv absorber. Therefore, anti-light aging agent is not necessary for the combination of carbon black, and it is indispensable for light products (carbon black is used only as coloring agent). For anti - aging, generally take the first anti - aging agent and the second anti - aging agent. Among the antiaging agents, the antiaging effect of phenylenediamine is particularly excellent, but there is serious pollution. Among the non-polluting anti-photoaging agents, phenols, blocked amine anti-aging agents and paraffin are the most effective. Among the phenol anti-aging agents, the anti-aging agent DTBM P (2, 6-dibutyl-4-methylphenol), the anti-aging agent SP (styrene phenol), the anti-aging agent MBMTB[2, 2-methyl-6-butylphenol] and the anti-aging agent MBETB[2, 2-methyl-6-butylphenol] had better anti-light cracking aging effect.
After vulcanizing, paraffin which is mixed with adhesive material will spout on the surface of the product to form a physical protective film, effectively preventing the ozone cracking of the product. The state of the paraffin on the surface of the product depends on its composition, the rubber formulation (rubber and additives) used, and the temperature. Therefore, it is important to select paraffin that meets the conditions of use.