Hindered amine light stabilizers thermal stabilizing activity

Elimination of the yellowing introduced by the stable nitroxyl radicals was essential for commercial development of these excellent stabilizers. Since phenolic antioxidants are necessary for the thermal stabilization of polymers during processing, we turned our attention to ways in which unfavorable interactions between the hindered phenols and the stabilizing nitroxyl radicals could be avoided. In this section we describe the discovery of the light-stabilizing activity of hindered amine compounds, an improved synthetic method for these compounds, the synthesis of a number of derivatives, and the evaluation of their stabilizing activity. 

In addition, we attempted to prepare piperidine compounds bonded with a hindered phenol moiety, since phenolic antioxidants are essential for processing and long-term stabilization. The proposed compounds were expected to have light-stabilizing activity and at the same time thermal stabilizing activity in the polymers. Bifunctional compounds were also synthesized. The corresponding diols were obtained by the reaction of the amines with ethylene oxide (Chart 11). The stabilizing activities of the above compounds are summarized in Table V. 

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