The addition of a trace amount of an antioxidant to the polyurethane raw material or formulation can block the thermal oxidation of the polyurethane. The role of the antioxidant is to prevent the oxygen chain-induced polymer chain scission reaction and decomposition of hydrogen peroxide.

Hindered phenolic compounds are the most commonly used antioxidants for polyurethane materials. For example: 1,3,5-trimethyl-2,4,6-tris(3',5'-di-tert-butyl)-4-hydroxybenzylbenzene, 2-(2'-hydroxy-3'- Tert-alkylbenzyl)anisole, tetrakis[L-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoic acid] pentaerythritol ester (antioxidant 1010), Lu (3,5-di-uncle Butyl butyl 4-hydroxyphenyl) propionate (antioxidant 1076), 2,6-di-tert-butyl-4-methylphenol (antioxidant 264), and the like. Phosphite antioxidants are also commonly used, such as tris(2,4-di-tert-butylphenyl) phosphite.

The aromatic isocyanate raw materials such as diphenylmethane diisocyanate are affected by light, heat, oxygen and moisture during storage and use, and the color will turn yellow, and chemical reaction will occur to form some infusibles to make isocyanate content. decline. The addition of antioxidants and antioxidants such as triphenyl phosphinate, tridecyl phenylphosphinate, and tris(2,4-di-tert-butylphenyl) phosphite can reduce this phenomenon. The use of a phosphonate in combination with a substituted phenol improves the weatherability and UV resistance of the polyurethane. The above phosphonate antioxidant is also often used in combination with the antioxidant 2246 and the antioxidant 300 [4,4'-thiobis(6-tert-butyl)-3-cresol].