| abstract |
Substituted piperazinedione carboxylic acids and metal salts thereof are stabilizers for synthetic polymeric materials normally subject to deterioration caused by ultraviolet light. The acids may be formed by reacting together the alkali or alkaline earth metal salts of a substituted piperazinedione and of a halo-alkanoic acid and then acidifying. The metal salts of the acids are readily prepared by reacting the acids or their salts with a reactive form of the metal or metal complex. Polymeric compositions containing these stabilizers may also contain a hindered phenolic compound. A typical embodiment is 6(15-(7,15-diazadispiro(5,1,5,3)hexadecane-14,16-dione))hexanoic acid. |