Rubber products are subject to various aging under the practical use condition than plastics, such as heat aging, oxidative degradation, ozone cracking and fatigue failure etc.

In this article, autoxidation mechanism including chain initiation, chain propagation and chain termination, and heat oxidative degradation mechanism of various rubbers are explained from the viewpoint of chemical reaction.

Amine antioxidants have a tendency to contaminate the rubber, and are often expressed as staining antioxidants, therefore, the use of them is avoided for the products where discoloration is a problem. However, in view of various deterioration preventing effects which amine antioxidants, many of them are used in various rubber products such as tires, rubber vibration isolator, and hoses.

This article explains the effect of adding amine antioxidants and various amine type antioxidants based on evaluation data.

Anti-aging agents for rubber are widely acknowledged as an auxiliary material indispensable for protecting rubber from internal and external deterioration factors, achieving required performance and extending product life. The phenolic antioxidant is used as a primary antioxidant together with the amine antioxidant, and it is particularly used for a rubber product which dislikes coloring, discoloration and migration stain. In addition, the phenolic antioxidant has been increasing in type and application with the development of resins and oils. It is difficult to be classified with a chemical structure. In the first half of this article, we will pick up some of phenolic antioxidants and explain the structure and function. And, in the second half of the article, we would like to report on the results from the compounding technique, mainly on heat resistance and discoloration, about the effect actually used for rubber.

Polymer degradation is associated by autoxidation reaction induced by heat, light, mechanical stress, and etc. This article describes mechanistic aspects of polymer autoxidation, particularly focusing on a photo-oxidation, and the role of light stabilizers in the prevention of undesirable photo-degradation.

Ultraviolet absorbers (UVA) and hindered amine light stabilizers (HALS) are typical additives that prevent the photo-degradation of plastics. UVA absorbs ultraviolet light with high energy to suppress the light-induced dissociation reaction and generation of radicals. The energy dissipation process of absorbed light by UVA depends on the chemical structures, such as benzotriazole, triazine, cyanoacrylate and so on.

In the meanwhile, HALS works as an radical scavenger to avoid the initiation of the autoxidation reaction induced by the exposure to the ultraviolet light. Most of the commercially available HALS have characteristic N-H or N-methyl (Me) group, which may interact with acidic additives, such as sulfur-containing antioxidant, pigments, and inorganic fillers, to lead an antagonistic action of antioxidation. Recently developed NO-alkyl HALS form a less salt with acidic additives than N-H and N-Me HALS does, because of the lower basicity of NO-alkyl group. An appropriate choice of light stabilizers is necessary to prevent the photo-degradation of polymers effectively.

Waxes used for antiozonant are mainly used by mixing petroleum wax. The wax blended in the rubber blooms to the rubber surface to form a protective film. Bloom speed of wax, protective film thickness and crystal state determine the superiority or inferiority of ozone resistance. This is the influence of the normal paraffin component of wax and the distribution of molecular weight. We will explain these in this review.