19 июля, 2015 
Malyar CIBA-GEIGY Corporation, Ardsley, New York, U. S.A.
Antioxidants (including hindered phenols, phosphites, and thioethers) are commonly used in hot-melt adhesive (HMA) and sealant formulations [1-4]. Relatively high levels of antioxidants are used (typically, 0.5 to 1.0%) in some adhesives (e. g., hot melts) to protect the polymers from oxidation when they are subjected to high temperatures during compounding and processing. The presence of these additives further protects the adhesive during the final end-use application. Antioxidants are also used in adhesive subjected to less severe processing (e. g., solvent — and water-based adhesives) to protect the adhesives during storage and end use. The thermal stabilization of adhesives is addressed in Chapter 19.
Some applications require exposure of sealants and adhesives to ultraviolet (UV) radiation. While the conventional antioxidants mentioned above will provide some protection against UV-initiated oxidation, many applications necessitate the incorporation of ‘‘light stabilizers” to reduce photoinduced polymer degradation. Two general classes of light stabilizers are used, ultraviolet absorbers (UVAs) and hindered amine light stabilizers (HALSs). In this chapter we discuss the stabilization mechanism of each of these classes and the relative importance of each of these stabilizers in preventing degradation of a thin — film adhesive versus a ‘‘thick’’ sealant. Although we focus on the fundamental aspects of the UV stability of adhesives, several examples are given to illustrate how these principles can be put into practice.
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