Study On The Control Mechanism Of Continuous Synthesis Of Pigment Yellow 14

Azo pigments account for a large proportion in the entire pigment industry and have a high market share.At present,the production of azo pigments in China mainly adopts batch process,which has high production energy consumption and much waste water.In order to solve this practical problem,this paper designed a continuous reaction device,studied the continuous synthesis process of Pigment Yellow 14,and further explore the continuous control mechanism of Pigment Yellow 14.A method for indirectly calculating the mass concentration of DCB diazonium salt by measuring the mass concentration of dye M was established.And the stability of diazonium salt was studied by this method.The results showed that the diazonium solution can be kept at 10 ? for 7 h.And when the temperature more than 18 ?,the diazonium salt concentration will drop significantly even placed a short time.In addition,the decomposition rate of the diazonium salt is affected by the concentration of zinc acetate.Especially,8 wt% zinc acetate has a strong inhibitory effect on the decomposition of diazonium salt.The DCB slurry preparation process was explored before the continuous diazotization reaction.The results show that with the increase of the beating rate,the beating temperature and the beating time,the DCB slurry particles become smaller,the viscosity of the DCB slurry gradually increases,and the slurry becomes more stable.The following favorable conditions were obtained: the concentration of DCB slurry was 70 g/L,the beating speed was 600 r/min,the beating temperature was 30 ?,and the beating time was 2 h.The results of the diazotization reaction showed that the continuous treatment could greatly reduce the amount of HCl with the same yield.When the molar ratio of DCB hydrochloride to HCl is 1:4,the continuous diazotization yield can still be maintained above 97 %,but the intermittent diazotization is far apart.Continuous diazotization is less affected by temperature and can achieve a yield of 94 % under normal temperature feed conditions,while batch diazotization is sensitive to temperature.In addition,the concentration of the reactants in the batch reaction should not be too high,but continuous diazotization can overcome this disadvantage.The preparation process of coupling agent AAOT slurry was explored before the continuous coupling reaction.The results showed that the concentration of the slurry increaseed,the slurry particles gradually became larger,the viscosity of the slurry gradually increased,and the slurry was more stable.When the pH of the coupling agent slurry is less than 8,as the pH gradually increases,the binder slurry particles become smaller,the viscosity of the coupling agent slurry increases,and the slurry becomes more stable.The optimum conditions of the coupling agent AAOT slurry were obtained through experiments: the rotation speed was 400 r/min,the coupling agent concentration was 60 g/L,and the pH of the coupling agent was 8.The results of the coupling reaction showed that the coupling yield was less affected by temperature during the continuous reaction,and the yield was basically stable at 97 % in the range of 3?25 ?.In addition,the coupling yield has an increasing tendency with alkali enhancement under certain conditions.When the pH of the coupling agent slurry was 5,the coupling yield was 92.3 %,and when the pH of the coupling agent slurry reached 8,the coupling yield reached 98.5 %.