Like other polymer materials, polyurethane foam will age and turn yellow under the action of external factors such as light and heat, and the physical properties of the material will decline. Adding antioxidants such as antioxidants and UV absorbers will delay this effect.
Adding a small amount of antioxidants to polyurethane raw materials or formulations can block the thermal oxidation of polyurethane. The role of antioxidants is to prevent the oxygen-induced chain scission reaction of the polymer and the 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'- tertiary alkyl benzyl) anisole, tetrakis [Lu-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester (antioxidant 1010), Lu (3,5-di-tert. Butyl-4-hydroxyphenyl) octadecyl propionate (antioxidant 1076), 2,6-di-tert-butyl-4-methylphenol (antioxidant 264), etc. Phosphonite antioxidants are also commonly used, such as tris(2,4-di-tert-butylphenyl) phosphite and the like.
Aromatic isocyanate raw materials such as diphenylmethane diisocyanate are affected by light, heat, oxygen, moisture and other factors during storage and use, and the color will turn yellow, and chemical reactions will occur to generate some infusible substances, which will increase the isocyanate content. decline. This phenomenon can be reduced by adding antioxidants and antioxidants such as triphenyl phosphite, trinonyl phenyl phosphinate, and tris(2,4-di-tert-butylphenyl) phosphite. The combined use of phosphonate and substituted phenol can improve the weather resistance and UV resistance of polyurethane. The above-mentioned phosphonate antioxidants are often used together with antioxidant 2246, antioxidant 300 [4,4'-thiobis(6-tert-butyl)-3-cresol], etc., and the effect is good.