In order to improve the hydrophilicity of C.I. pigment red 31 and make it more suitable for water-based ink

2-hydroxy-3-naphthoyl-(4’-chlorine-2’

5’-dimethoxy) aniline (naphthol AS-LC) was selected to participate in the coupling agent preparation of 2-hydroxy-3-naphthoyl m-nitroaniline (naphthol AS-BS)

and then carry out the coupling reaction with the diazonium salt 3-amino-4-methoxy benzoyl aniline (red base KD). Thus the hydrophilic C.I. pigment red 31 was obtained. The contact angle

SEM

color capability and thermogravimetric analysis show that the crystal morphology of the pigment modified by naphthol AS-LC can be changed from long strip to disk shape. When the dosage is 5%(mol)

the contact angle between pigment and water can be reduced to 53.4°

the pigment particle size and particle size distribution narrow down

the hydrophilic property can be best. The coupling of naphthol AS-LC and naphthol AS-BS results the pigment hues convert into red and blue to some extent

and the color difference (ΔE) is small

with a value of 0.52. The pigment crystal begins to decompose when it is heated to 270℃ in nitrogen

it is obvious that the pigment has reached the standard of high temperature resistant pigment. Compared with traditional pigment

The dispersity

rheological properties and other printability of the pigment prepared by this method are obviously better.