Production system and process method for continuously synthesizing bisazo pigment

Abstract

The invention belongs to the field of pigment synthesis, and particularly relates to a production system and a process method for continuously synthesizing a bisazo pigment. The method comprises the following steps: carrying out diazotization reaction on a hydrochloric acid solution of a diazo component and a sodium nitrite solution in a membrane dispersion microreactor to prepare a diazonium saltsolution A; preparing a coupling component solution B from a coupling component and sodium hydroxide; preparing acetic acid and sodium acetate into a buffer solution C with the pH value of 4.3; and simultaneously introducing the solution A, the solution B and the solution C into a double-sided microporous dispersion microreactor according to a certain flow ratio, carrying out a coupling reactionto generate a bisazo pigment crude product, and further treating the crude product to obtain the azo pigment product. The continuous diazotization reaction is realized by adopting the membrane dispersion microreactor, the continuous coupling reaction is realized by adopting the double-sided microporous dispersion reactor, and the continuous synthesis of the bisazo pigment is realized through the two reactions. The invention has the advantages of simple process, short reaction period, easiness in temperature control and easiness in pH adjustment.

Description

technical field [0001] The invention belongs to the field of pigment synthesis, and in particular relates to a production system and a process method for continuously synthesizing disazo pigments. Background technique [0002] Azo pigments refer to a class of synthetic pigments containing azo groups in their molecules. They are the main category of organic pigments, accounting for about 40% of the total organic pigments. According to the number of azo groups contained in the pigment molecules, it can be divided into monoazo pigments and disazo pigments. Among them, disazo pigments are widely used in the fields of ink industry, high-grade automobile topcoat, advanced engineering plastics, resins and fiber products. It is a disazo pigment with great market influence and strong technical representativeness. Its continuous production technology It can be popularized and applied to the production of other disazo pigments. [0003] The production process of azo pigments mainly i...

AI Technical Summary

Problems solved by technology

According to the sensitivity of the coupling reaction to pH changes, if the pH change is not well controlled during the two-step coupling reaction, side reactions are prone to occur, such as the self-coupling reaction of diazonium salts to generate monocouples. Precipitation and coating of nitrogen compounds, etc., these situations will have a great impact on the quality of pigments

[0004] The traditional batch method for synthesizing disazo pigments, due to factors such as uneven heat and mass transfer in the batch reactor, will lead to the decomposition of diazonium salts and self-coupling reactions, which will cause the particle size of the pigment particles to increase. Wider particle size distribution, lower pigment yield and quality, will also lead to large differences in shade and intensity between batches of pigments produced

And according to the batch synthesis method of azo pigment yellow 14 disclosed by Chinese patent (CN106752254A), it can be seen that the reaction time used by the method of batch synthesis needs at least 2 hours, and the change of the pH of the coupling reaction system needs to be monitored at any time. Greatly reduced production efficiency

Regarding the continuous synthesis of azo pigments, related reports include: (1) Yang Lintao, Shenyang Chemical Industry Research Institute, etc., used binary mixing microchannel and ternary mixing microchannel reactors to carry out continuous synthesis of azo pigments (dyeing and Dyeing, Vol. 54 No. 2, April 2017) However, the process given in the report is the process of feeding two reaction liquids, and there are no specific process parameters, nor does it involve specific microchannel reactors Structural parameters

(2) Chinese invention patent (CN104479394A) discloses a method for the continuous synthesis of azo pigments in a branched spiral tube, utilizing the efficient mixing effect of the secondary flow of the spiral tube to strengthen the coupling reaction, but there is no The synthesis process of disazo pigments is specifically mentioned, and the branched helical tube reactor still cannot solve the problem of difficult pH control in the production process of disazo pigments, so this reactor is not suitable for disazo pigments with high requirements for color light continuous synthesis of

(3) Chinese invention patent (CN102618063B) discloses a reactor with a scaling helical structure for the continuous synthesis of azo dyes, but this structure is not suitable for the synthesis of azo pigments because the pigments will deposit in the scaling structure, clogged pipe

The above structure is more suitable for the synthesis process of products with low viscosity, such as the preparation of inorganic nanoparticles, but it is not suitable for the synthesis process of pigments, because the existence of structures such as collection chambers will lead to the deposition of reactants and pigments, and block the pipeline

And if the reactor is used in the synthesis process of disazo pigments, the problem of pH regulation in the reaction process cannot be solved, and it will still lead to poor shade, transparency and strength of disazo pigment products.

[0006] Based on the above research progress, it can be seen that there is still no specific microreactor device and process route for the continuous synthesis of disazo pigments in microreactors to achieve continuous synthesis of high transparency and high strength disazo pigments.

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