Synthesis And Improvement Of Hindered Amine Light Stabilizers Chimassorb 944

Hindered amine light stabilizers (HALS) are a new class of light stabilizers developed at the end of 1970s, which have been one of the most intensively studied classes of stabilizers during the last several decades due to their high photo-stabilization efficiency.According to the characteristics of cyanuric chloride, three different synthetic processes, namely two-step, three-step and four-step processes, for synthesis of Chimassorb 944 were designed and examined systematically in this thesis. According to the two-step synthetic process, the intermediate 1, which was obtained from the substitution of one chlorine atom on triazine ring with amine, was charged into an autoclave together with N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)-1,6- hexanediamine. The desired polymer was obtained by programmed temperature. Three chlorine atoms on triazine ring were substituted one by one under different reaction conditions in three-step synthetic process and the desired polymer was obtained. However, according to the four-step synthetic process, two intermediate were obtained by treatment of the intermediate 1 with N,N'-bis-(2,2,6,6-tetramethyl- 4-piperidyl)-1,6-hexanediamine at low temperature and at high temperature in an autoclave respectively. Condensation of these two obtained intermediates in an autoclave afforded the target polymer. The results indicated that the two-step synthetic process was more efficient. The obtained Chimassorb 944 was qualified as the advanced level of the kindred products. The numerical average molecular weight was between 2000 and 3000, the polydispersity was about 2.0, the transparency was over 95% under 425nm.In order to lower the consumption of N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)- 1,6-hexanediamine, and minimize the amount of insoluable by-products in the polymerization step, we improved the existed three routes by means of using t-octyl amine as the end-capping group. For getting the t-octyl amine end-capped polymers , t-octyl amine was added at different stage of three-step, two-step and four-step processes, respectively. Experiment results showed that the consumption of N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexanediamine and the amounts of by-products could be controlled. However, numerical average molecular weight of the product could not reach the standard we needed. So it is important to investigate the mechanisms of the reaction in the further work, and improved these synthesis processes, successfully.