Preparation method for pigment orange 64 with high color intensity

Abstract

The invention discloses a preparation method for pigment orange 64 with high color intensity. The preparation method comprises the following steps: (1) 5-amino-6-methylbenzimidazolone is dissolved in water and hydrochloric acid with the mass concentration of 30 percent, and diazotization is carried out through a sodium nitrite solution with the mass concentration of 40 percent, so that a diazonium salt solution is prepared; (2) barbituric acid is dissolved through aqueous alkali, so that a coupling liquid is prepared; (3) a surfactant and a buffering agent are dissolved in water, so that a buffered solution is prepared; (4) the diazonium salt solution and the coupling liquid are added into the buffered solution at the same time for a coupling reaction, and filtering is carried out, so that a pigment orange 64 pigment crude product is obtained; (5) the pigment crude product is added into an organic solvent, pulping is carried out, the temperature is risen to be 70 DEG C to 120 DEG C and then maintained for 1 to 8 hours, and suction filtration, washing and drying are carried out, so that a pigment orange 64 finished product is obtained. The method has the advantages that the surfactant is added for coupling, coupling reaction parameters are optimized, and a pigment crude product filter cake is pigmented in water and the weak solvent to prepare the C.I. pigment orange 64 with high color intensity.

Description

technical field [0001] The invention relates to the technical field of pigment preparation, in particular to a preparation method of high coloring strength pigment Orange 64. Background technique [0002] Pigment orange 64 (Chinese name: 5-[(2,3-dihydro-6-methyl-2-oxo-1H-benzimidazol-5-yl)azo]-2,4,6(1H, 3H,5H)-pyrimidinetrione) belongs to benzimidazolones, is a yellowish orange high-grade organic pigment with the following molecular structure: [0003] [0004] This pigment variety is a very important orange organic pigment. Due to the cyclic amide substituent group (-NHCONH-) in the molecular structure, the imino group (-NH-) and the carbonyl group (=O) in the molecule Intermolecular hydrogen bonds are formed between pigment molecules. Generally, the solvent resistance and heat resistance of azo pigments are poor, because their molecules do not contain hydrogen bonds, the distance between molecules is relatively large, and the binding force of the entire crystal is onl...

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Problems solved by technology

[0007] British patent (GB1008166) discloses a synthetic method of orange benzimidazolone organic pigments. Pyridine is used as a reaction medium during pigmentation processing, but pyridine is not only poisonous but also has an unpleasant odor, which is harmful to the operator's body and mind. Health is harmful; U.S. Patent (US4870164) adopts a kind of material called montmorillonite to carry out pigmentation processing to coupling product, but this montmorillonite is difficult to obtain in China, thereby has no general significance; Patent CN1569968A discloses a kind of benzene The synthetic method of imidazolone C.I.P.O.36 uses N,N-dimethylformamide (DMF) as a solvent for pigmentation processing, because N,N-dimethylformamide has been listed as a substance of very high concern (SVHC) by the European Union , so if the pigment does not contain this substance, it can only be rinsed with a large amount of water, which not only wastes waste water resources, but also has a high ammonia nitrogen content in the sewage, which is difficult to biochemically treat, and the treatment cost of sewage will also increase accordingly; patent CN102391664A discloses A kind of synthetic method of pigment orange 64 is that diazonium salt is slowly added in the coupling component, because the diazonium salt coupling ability is poor, there must be a large amount of diazonium salt in excess state in the reaction process, and the whole coupling reaction is In the process from strong alkali to weak acidity, the diazonium salt is easily destroyed under alkaline conditions, and the pH value changes greatly during the reaction process, the product particles formed are in different states, and the coloring power of the synthesized product is low; patent CN101955685A discloses A method for synthesizing Pigment Orange 64 is to quickly add diazonium salt to the coupling components. The crude pigment is not processed by pigmentation, but the pH is adjusted to 12-14 with KOH, and then quickly precipitated with hydrochloric acid. The product not only has low tinting strength, but also has a dark shade, so it cannot be used for coloring high-end products

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