DISAZO PIGMENT COMPOSITION, ITS PREPARATION AND IMPROVEMENT OF PIGMENT

摘要

PROBLEM TO BE SOLVED: To prepare a printing ink excellent in transparency and fluidity by incorporating, as necessary ingredients, a specific disazo pigment and a specific asymmetrical disazo compound. SOLUTION: The objective disazo pigment composition comprises, as necessary ingredients, a disazo pigment represented by formula I and an asymmetrical disazo compound represented by formula II, characterized in (1) that at least a part of the asymmetrical disazo compound is homogeneously adsorbed on a primary particle of the disazo pigment, or contained in the crystal structure of the disazo pigment, (2) that it comprises 98.0-72.3 wt.% of the disazo pigment and 2.0-27.8 wt.% of the disazo compound and (3) that the asymmetric disazo compound is >=93 pts.wt. based on 100 pts.wt. of the total of the disazo compounds. In the formulae I and II, Z1 is phenyl optionally bearing a substituent such as methyl, a halogen or the like; and Z2 is phenyl bearing a substituent such as a carboxylic acid group, a sulfonic acid group or the like and optionally a substituent such as methyl, halogen or the like.