Preparation method of black reactive dye with high color fixing rate

The invention relates to a preparation method of a black reactive dye with high color fixing rate. The preparation method comprises the following steps: Step 1, an acid coupling reaction is carried out to obtain an acid coupling substance; Step 2, an alkali coupling reaction is carried out to obtain an alkali coupling substance, and uniform stirring is carried out for later use; Step 3, 100 g of an ice-water mixture and 30ml of technical hydrochloric acid are added into a beaker, the mixture is added at the temperature of 0-15 DEG C for 30 min while stirring is carried out, potassium iodide starch paper is controlled to bluish at the temperature of 5-20 DEG C, reaction lasts for 2 h, and sulfamic acid is used to eliminate excess nitrous acid so as to obtain a diazonium salt suspension; the above diazonium salt suspension is added into the acid coupling substance, uniform stirring is carried out, temperature is controlled to 15-20 DEG C and the alkali coupling substance is added, pH is adjusted to 4.5-6.5, stirring is carried out for 1-3 h, and direct spray-drying is carried out to obtain the black dye.