Development Of Rubber Vulcanization Accelerator NS

A new method to synthesize vulcanization accelerator N-tert-buthylbenzothiazole -2-sulfenamide (NS) in aqueous phase is here studied. NS was chemically synthesized by reaction of the reductive mixture of wet accelerator 2-mercaptobenzothiazole (M) and tert-buthylamine with certain amount of oxidant sodium hypochlorite. For the sake of better dispersions of all these reactants in aqueous phase, wet accelerator M rather than accelerator M itself was chosen to be the raw material.Effects of molar ratios of reactants, concentrations, reaction temperature and time on NS yield and purity were systemically investigated. Furthermore, L9(34) orthogonal method was applied to optimize the detailed reaction parameters. The suitable parameters was as follows: tert-buthylamine / 2-mercaptobenzothiazole (mol/mol) 1.6, sodium-hypochlorite / 2-mercaptobenzothiazole (mol/mol) 1.3,feeding water / 2-mercaptobenzothiazole (mol/mol) 40, reaction temperature of oxidation 65℃, oxidant time of sodium hypochlorite 2.5hr, sodium hypochlorite≥15%, thermal temperature 65℃, thermal time 0.5hr, stirring speed of reaction 80 r/min. In addition, it is shown that the reflux of the mother liquid will benefit for the fully use of raw materials as well as decrease of waste emissions.NS yield up to 93% was obtained in a long-period-running. The obtained samples satisfied both the Chinese Quality Standard of Accelerator NS and Quality Standard of Accelerator Santocure TBBS of FLEXSYS Company.The analyses of the synthesized NS sample by IR, LC-MS and HPLC showed that it has a high purity. Rubber vulcanized with the sample can obtain better or same physic and mechanic properties comparing with CBS, NOBS and TBBS.