Study On Continuous Synthesis Process Of Pigment Red 146 And Pigment Yellow 12

Pigment Red 146 and Pigment Yellow 12 are representative varieties of azo pigments.At present,the domestic production of azo pigments adopts batch process with traditional tank reactors,which has a lot of room for development in improving production efficiency,reducing production cost and improving green,safety and environmental protection of production.Compared with traditional reactors,microreactors have good mass and heat transfer effects,can accurately control reaction conditions,strengthen reaction efficiency,and can also greatly improve production safety.It has huge advantages.With 3-amino-4-methoxybenzanilide(Red base KD)as diazonium component,N-(4-chloro-2,5-dimethoxyphenyl)-3-hydroxy-2-naphthalene amide(Naphthol AS-LC)as coupling component,the self-designed tubular micromixer was used to carry out the continuous synthesis process of Pigment Red 146.The effect of mass concentration of Red base KD,reaction temperature,material flow rate and the amount of hydrochloric acid on diazotization were investigated.The influence of p H,reaction temperature,material flow rate and holding temperature on azo-coupling reaction was explored.The continuous process of diazotization was carried out under the condition that the mass concentration of Red base KD was 70 g/L,n(HCl):n(Red base KD)=2.5:1,the reaction temperature was 20 ℃,and the flow rate was 50 L/h,the yield reached 98.6 %.The continuous process of azo-coupling reaction was carried out under the condition that the reaction temperature was 20 ℃,p H=5.0,and the flow rate was 50 L/h,the yield reached 98.4 %,the color was closest to the standard sample,and the particle size was significantly smaller than batch method.Compared with batch process,the continuous process not only improves the yield,but also reduces the energy consumption and material cost,improves the overall production efficiency.It has a broad industrialization prospect.The monoazo component of Pigment Yellow 12 was independently synthesized.The purification method of Pigment Yellow 12 and its monoazo component was determined and they are characterized.The pure product of Pigment Yellow 12 and its monoazo component were mixed in different proportions,the crystal form,ultravioletvisible absorption spectrum and the color of the mixed sample were measured.The influence of monoazo component on the aggregate structure and color properties of Pigment Yellow 12 were analyzed.It is determined that the maximum allowable monoazo component in Pigment Yellow 12 is 2.64 %.The Pigment Yellow 12 product was synthesized under the optimal process conditions of batch method and continuous method.The color properties of the samples were measured and the product composition was calculated to verify the reliability of the optimal process conditions and the superiority of the continuous process.