Effect of Various Additives on the Photodegradation of Polyurethanes

Abstract

Conventional polyurethanes based on aromatic diisocyanates such as diphenylmethane-p,p’-diisocyanate (MDI) and tolylene diisocyanate (TDI) have been used substantially and world-wide in the manufacture and use of urethane materials because of their excellent physical properties, polymerizability and price. However, they are sensitive to ultraviolet light.^1,2 In order to overcome the shortages of aromatic polyurethanes, some polyurethanes having antiquinoid or non-quinoid diurethane structures, including aliphatic structures, have been developed. The improvement of photo-stability of polyurethanes was also achieved by the use of various UV stabilizers.³ We have been studying the photodegradation and stabilization of polyurethanes,^4–9 and have found that some fluorescent dyes such as stilbene derivatives and coumarin derivatives were effective retarders for the photodegradation of the polyurethanes. Therefore, various types of related fluorescent dyes were prepared, and the effectiveness of these compounds was determined by the measurement of changes in the residual mechanical strength and the results compared with those of commercial products.