Anti-aging agent

In the process of use and storage of high polymers and their products, such as plastics, rubber, synthetic fibers, etc., due to the influence of the environment, their chemical composition and structure will be under the combined action of heat, oxygen, water, chemical medium, light and microorganisms. A series of changes occur, physical properties will be correspondingly deteriorated, sticky, hard, brittle, stiff, cracked, color-generating or losing strength. These changes are collectively referred to as aging. Anti-aging agent refers to a substance that can delay the aging of polymer compounds. Most of these substances can inhibit oxidation, and some can inhibit the action of heat and light, thereby prolonging the service life of the product. The reasons for the aging of the polymer are various, and the corresponding antioxidants are also various. Generally, antioxidants, antiozonants, free radical terminators, harmful metal inhibitors, ultraviolet light stabilizers, mildew inhibitors, stabilizers, light stabilizers, retarders and polymerization inhibitors can be used as anti-aging agents. Moreover, different polymers have different antioxidants under different environmental conditions. According to their chemical properties, they can be classified into the following five categories. 1. Ketoamine condensates: These condensates are effective against air and ozone aging. Low temperature condensates such as acetone and diphenylamine have good anti-aging properties to the polymer. The condensate of acetone and phenylethylnaphthylamine is a light brown non-toxic powder which is soluble in acetone and dichloroethane. Suitable for natural rubber adhesives, neoprene adhesives and nitrile adhesives. 2. Aldehyde condensate: The aldehyde amine condensate has moderate effectiveness against air aging. Suitable for natural rubber adhesives and synthetic rubber adhesives. The increase in the amount increases the heat resistance of the adhesive. A condensate such as an aldehyde with naphthylamine is a non-toxic orange or deep red resinous solid. 3. Aromatic amines: Aromatic amines are a special anti-aging agent. Different anti-aging agents have different special effects. For diene-type adhesives (natural rubber or some synthetic rubber adhesives), phenyl-2-naphthylamine and phenyl-β-naphthylamine are often used. For example, m-toluene diamine is moderate in air aging resistance and heat aging resistance, but has high anti-aging effect in uncured rubber gluing. 4. Aromatic diamines: Diphenylamine derivatives are excellent airborne antioxidants whose effectiveness is related to the nature of the substituents. 5. Quinoline derivatives: Quinoline derivatives are effective against air and ozone aging. Most of the antiozonants are derivatives of p-phenylenediamine.