Around 1910 the first type of antioxidants were discovered, mainly naturally existing materials like creosote, asphalt, and coal tar pitch. These were used until roughly 1925 when phenol, cresol, hydroquinone and aniline were used as antioxidants. Between 1925 and 1940 a big number of patents on
antioxidants were issued, most of them based on secondary aromatic amine derivatives. It was not until after 1940 when an increasing worldwide production of synthetic rubber, and consequently the development of tires based on synthetic rubber, called for a more demanding type of antioxidant, not only protecting the rubber goods and tires against oxygen and heat, but also against the severe
cracking caused by ozone. The result was the d~velopment of a new class of antioxidants, p-phenylendiamine derivates, which was soon after called antiozonant, due to their ability to protect rubber goods against cracking. With the development of non staining antioxidants, it was possible to protect rubber against deterioration, caused by oxygen, heat, light and certain metals, like copper and manganese, and still maintain the natural color of the rubber. These non staining antioxidants are more or less hindered phenolic antioxidants and are the subject of the following presentation.