Synthesis and properties of a hindered amine light stabilizer used in automotive varnish
A hindered amine light stabilizer(HALS)TM-3 was designed and synthesized.N-butyl-4,6-dichloro-N-(2,2,6,6-tetramethyl-4-piperidinyl)-1,3,5-triazine-2-amine(intermediate Ⅰ)was firstly synthesized from nucleophilic substitution reaction of cyanuric chloride and N-butylamino-2,2,6,6-tetramethylpiperidinyl,which was then reacted with N,N-bis(2,2,6,6-tetramethylpiperidin-4-yl)-hexane-1,6-diamine to produce N2,N2'-(hexane-1,6-diyl)bis[N4-butyl-6-chloro-N2,N4-bis(2,2,6,6-tetramethylpiperidin-4-yl)-1,3,5-triazine-2,4-diamine](intermediate Ⅱ).Finally,target compound 6,6'-{hexane-1,6-diylbis[(2,2,6,6-tetramethylpiperidin-4-yl)azanediyl]}bis{4-[butyl(2,2,6,6-tetramethylpiperidin-4-yl)amino]-1,3,5-triazin-2-ol}(TM-3)was obtained by hydrolyzation of intermediate Ⅱ,and characterized by 1HNMR,13CNMR,HRMS,UV-Vis absorption spectra and TGA for structure and property analyses.The light stability of TM-3 and bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate(HALS770)in automotive varnish coatings was further evaluated.The results showed that TM-3 displayed strong UV-Vis absorption at 210 nm and good thermal stability by maintaining thermal stability below 400℃and withstanding higher temperatures.TM-3 exhibited better solubility in aqueous organic solvents compared with HALS770.After 800 h of simulated ultraviolet irradiation,sample 4 with TM-3 added showed a chromatic aberration of 6.01 and a gloss loss rate of 4.6%,while sample 5 with HALS770 added displayed a chromatic aberration of 6.72 and a gloss loss rate of 6.7%,indicating that TM-3 had better light stability than HALS770.
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