Anti-ozone agents
Antiozonants to the undesirable hardening and embrittlement of elastomers , particularly rubber , under the action of ozone decrease.
Ozone normally occurs in the atmosphere in concentrations ≤ 50 ppb . In the presence of pollutants and UV light , the ozone concentration near the ground can rise to 400 ppb. The double bonds in rubber are attacked by ozone through ozonolysis , especially if the rubber object is also exposed to a critical stretch. Then cracks form, which increase exponentially with elongation. Substituted p -phenylenediamines are mainly used as ozone protection agents, such as:
- Dialkyl p -phenylenediamines,
- Alkyl-aryl- p -phenylenediamines or
- Diaryl- p- phenylenediamines.
Individual evidence
- ^ Fritz Röthemeyer, Franz Sommer: Kautschuktechnologie , Carl Hanser Verlag Munich Vienna, 2nd edition, 2006, pp. 342–343, ISBN 978-3-446-40480-9 .