N-alkoxy hindered amine

Another newer version of HALS is exemplified by hydroxy-substituted N-alkoxy hindered amines, i.e., molecules with at least one active moiety of the structure >N-OR-(OH). A very wide range of such additives has been covered in a family of patents assigned to Ciba Speciality Chemicals [193-198], and claims for applications include aromatic polyesters. These additives are said to have as good as or better UV stabilising ability and antioxidant properties as the earlier HALS. The hydroxyl group(s) is said to impart additional advantages not possible with the NOR types, e.g., antistatic attributes, and better pigment dispersion in polar polymers. 

Ciba Specialty Chemicals has demonstrated that an N-alkoxy hindered amine light stabiliser can increase the effectiveness of halogenated flame retardants, reducing the amoimt of flame retardant required. Its Tinuvin FR can improve light stability and flame retardancy in exterior polypropylene articles, including outdoor furniture. The same company also offers easily dosable grades of UV stabiliser, to provide better control over dosing, and hence reduced costs. 

Work with an N-alkoxy hindered amine (NOR) has shown that it can exhibit synergistic behaviour when used in combination with conventional brominated and phosphorus FRs in polyolefin fibres and moulded articles, according to Ciba Specialty Chemicals. 

Xie, H., Lai, X., Zhou, R., Li, H., Zhang, Y., Zeng, X., Guo, J. Effect and mechanism of N-alkoxy hindered amine on the flame retardancy, UV aging resistance and thermal degradation of intumescent flame retardant polypropylene. Polym. Degrad. Stab. 118, 167-177 (2015)... 

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