Study On Synthesis Technology Of Pigment Yellow 14

Pigment yellow 14 is one of the important types of benzidine yellow,it has the advantages of high coloring power,bright color and low price,has been widely used in packaging printing ink,polyolefin plastic,rubber,viscose fiber liquid coloring and other aspects.The industrial production of pigment yellow 14 mainly adopts stirred tank reactor,due to its synthetic process of diazotization and coupling reaction belongs to strong exothermic reaction,it is easy to local heat accumulation in the reactor,not only make the instability of the diazonium salt decomposition,but also create safety problems,and low purity of pigment,the average particle size,particle size distribution wide,It seriously affects its application performance.This paper intends to use typical process strengthening equipment-high gravity reactor diazotization and coupling reactor,give full play to the advantages of high gravity equipment to greatly enhance the mixing and transfer process between materials,solve local hot issues in the reaction process,and improve the safety and product quality of the production process.In this paper,the synthesis conditions of pigment yellow 14 were studied by single factor experiment in stirred reactor and high gravity reactor,and the product was analyzed by UV absorption spectrometer,particle size analyzer and scanning electron microscope.The main research results are as follows:(1)The optimum technological conditions for the synthesis of pigment yellow 14 in stirred tank reactor were determined.Diazotization reaction: the molar ratio of benzidine hydrochloride to hydrochloric acid1:4.5,benzidine hydrochloride to sodium nitrite 1:2.7,at the same time reaction temperature 5℃,reaction time 30 min and stirring speed 300 rpm.Coupling reaction: reaction temperature of 10 ℃,reaction time of60 min,p H 4～4.2,stirring speed of 500 rpm.Under the above conditions,the yield of pigment yellow 14 was 97.7% and the average particle size was 220 nm.(2)Determine the optimal process conditions for the synthesis of pigment yellow 14 in the high gravity reactor(the molar ratio of materials is consistent with that in the stirred tank).Diazotization reaction: reaction time 6 min,RPB speed 1200 rpm,reaction temperature 5 ℃.Coupling reaction: reaction time 20 min,reaction temperature 10℃,p H 4～4.2,RPB speed 1200 rpm.Under the above conditions,the yield of pigment yellow 14 can reach 92.1% with an average particle size of 120 nm.Compared with the stirred tank reactor,the products produced by the high gravity reactor have the advantages of high purity,significantly shorter reaction time,small average particle size,narrower particle size distribution and small color difference.