Preparation method for pigment orange 64 with high color intensity

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.