▎ 摘　　要

NOVELTY - Preparing hydrophilic carbon black comprises e.g. (i) dispersing uniformly graphene oxide and furnace carbon black in water to obtain dispersion liquid, (ii) soaking dispersion liquid obtained in step (i) in a nitric acid solution with a mass fraction of 2-2.5% at a constant temperature of 25 degrees C for 1.5 hours, and (iii) subjecting carbon black dispersion soaking liquid obtained in step (ii) into solid-liquid separation and drying to obtain hydrophilic carbon black. The pH of the furnace carbon black is 7-10, the carbon black concentration of the carbon black dispersion liquid is 20-100 g/l, the dibutyl phthalate absorption of the furnace carbon black is 80-100 cm3/100 g, the nitrogen adsorption specific surface area of the furnace method carbon 100-160 m2/g, the average particle size of the furnace carbon black is 25-30 nm, the furnace carbon black is in contact with the nitric acid solution by stirring, and the method is mechanical stirring or ultrasonic stirring. USE - The hydrophilic carbon black is useful for preparing building pigments (claimed). ADVANTAGE - The carbon black: has excellent hydrophilicity and dispersion stability in water. DETAILED DESCRIPTION - Preparing hydrophilic carbon black comprises (i) dispersing uniformly graphene oxide and furnace carbon black in water to obtain dispersion liquid, (ii) soaking dispersion liquid obtained in step (i) in a nitric acid solution with a mass fraction of 2-2.5% at a constant temperature of 25 degrees C for 1.5 hours, and (iii) subjecting carbon black dispersion soaking liquid obtained in step (ii) into solid-liquid separation and drying to obtain hydrophilic carbon black. The pH of the furnace carbon black is 7-10, the carbon black concentration of the carbon black dispersion liquid is 20-100 g/l, the dibutyl phthalate absorption of the furnace carbon black is 80-100 cm3/100 g, the nitrogen adsorption specific surface area of the furnace method carbon 100-160 m2/g, the average particle size of the furnace carbon black is 25-30 nm, the furnace carbon black is in contact with the nitric acid solution by stirring, and the method is mechanical stirring or ultrasonic stirring, the solid-liquid separation is centrifugal separation or filtration separation. INDEPENDENT CLAIMS are also included for: (1) hydrophilic carbon black obtained by above method; and (2) preparing building pigment comprising (i) grinding hydrophilic carbon black to obtain colored layer coating, (ii) taking pearlescent pigment as sheet substrate, the pearlescent pigment is natural mica, synthetic mica, silicon dioxide sheet or aluminum oxide sheet as substrate, and (iii) mixing coloring layer coating and silane coupling agent and coating on the sheet substrate to obtain pigment.