Patent ID: 7855041

Claim:
A pigment preparation comprising the monoazo pigment of the formula (I) and a pigment dispersant in an amount of 0.1% to 40% based on the weight of the monoazo pigment of the formula (I), wherein the pigment dispersant is composed of disazo compounds, at least 30% by weight of the disazo compounds constituting an asymmetric disazo compound of the formula (II) Y—X-A-X—Z (II), wherein A is biphenylene, 3,3′-dichlorobiphenylene, 3,3′-dimethoxybiphenylene, 3,3′-dimethylbiphenylene or 2,2′-dichloro-3,3′-dimethoxybiphenylene; X is a group —NH—CO—CH(COCH 3 )—N═N—,—N═N—CH(COCH 3 )—CO—NH— or —N═N—; Y is substituted or unsubstituted phenyl, pyrazolin-5-on-4-yl, 1-phenyl-pyrazolin-5-on-4-yl, 2-hydroxynaphth-1-yl or 2-hydroxy-3-(phenylamino-carbonyl)naphth-1-yl, the substituents being C 1 -C 4 alkyl, C 1 -C 4 alkoxy, nitro, halogen or C 1 -C 4 alkoxycarbonyl, and Z has the definition of Y and is additionally substituted by a sulfonic acid group in the form of the ammonium salt.