Hindered amine light stabilizers synthesis

Since their initial production by our laboratories about ten years ago, hindered amine light stabilizers (HALS) have become established as excellent light stabilizers of polymers. This review deals with their synthesis, evaluation and development. 

Uvasil 299. [Enichem Synthesis SpA] Hindered amine light stabilizer. 

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. 

Synthesis and Stabilizing Activity of Hindered Amines. As mentioned previously, the hindered piperidine compounds showed excellent light-stabilizing activity in polypropylene. In order to find more efficient compounds, various derivatives of 2,2,6,6-tetramethyl-4-oxopi-peridine (42) were synthesized and tested. In this section we describe some typical examples from the great number of derivatives prepared in our laboratory. 

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