(1) What is the choice of raw rubber?

In terms of thermal oxygen aging, the effects of various antioxidants in NR, IR, SBR, BR, and NBR are similar, although the aging resistance of these rubbers is very different. The ozone resistance and flex protection are also generally similar, but there are some deviations: for example, in terms of ozone protection, NBR is more susceptible to ozone attack than SBR; 4030 is much more resistant to bending fracture in BR than in NR, of course There are some other examples. In low unsaturation rubbers (EPDM, IIR, partially unsaturated HNBR), antioxidants show less effect than highly unsaturated rubbers. In this case, RD and MB type antioxidants are usually selected. In peroxide curing systems, the interaction of antioxidants with peroxides should be considered. The best antioxidant in CR vulcanizate is 3100, MB type antioxidant has a promoting effect here, RD will weaken the scorch safety.

(2) Are there requirements for non-pollution or contact pollution?

Antioxidant products include serious pollution type (4020), non-pollution type (BHT, DS) and moderate pollution type. All amine products migrate, with the smallest degree of migration for TMQ/RD. Non-migratory products, while satisfactory, do not provide protection against breakage.

(3) What problems must be prevented?

How can surface problems (fractures, chalking, cracking) or product problems such as hardening, softening, loss of strength and similar problems be avoided? Since all products are more or less resistant to oxidative ageing, they are classified according to their ability to protect against surface effects (cracks). None of the completely non-polluting products has strong resistance to bending and fracture. The selection of antioxidants must also consider the type of rubber. Should protective wax be used together? Rubber products are pre-stressed and other factors.

(4) What is the effect of anaerobic aging (non-oxidative)?

In some thermal aging processes, antioxidants cannot provide corresponding protection, such as reversion, cyclization (two-stage vulcanization and creep crosslinking, etc.). In this case, some special curing systems need to be considered: low sulfur, thiuram or peroxide curing systems. In peroxide vulcanization, special antioxidants must be selected.

(5) Is resistance to hydrolysis required in addition to resistance to oxidative degradation?

MB and MB2 can improve the good protective effect in the water vapor aging of diene rubber. Rubbers containing hydrolyzable groups, such as Levapren and Urepan, are preferably protected by carbodiimide. Desmopan materials, especially polyester types, must use a hydrolyzing agent. Stabilizers are added during the production of all polyester grades.

(6) Does it come into contact with food?

Consult the Rubber Group of the Health, Safety, Environment, Quality (HSEQ) Regulatory Agency for FDA and BgVV regulations related to food contact applications.