Method of preparing complex-azo pigment and complex-azo pigment thereof

A method of preparing a complex-azo pigment having plural pigment components including at least one azo pigment represented by the following formula (a), comprising:

• converting an azo compound having a carboester group represented by formula (I) into an azo compound represented by formula (a) by chemically, thermally or photolytically decarboesterifying a carboester group represented by formula (I):
• A(E)n (I)
• wherein A represents a residue of an azo compound, bonded with n E groups through one or more heteroatoms N or O and forming a part of the residue A, the E group(s) independently representing a hydrogen atom or a carboester group represented by formula (b),
• —C(═O)—O—R1 (b)
• wherein R1 represents a substituted or unsubstituted alkyl group having 3 to 15 carbon atoms, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted cycloalkenyl group,or a substituted or unsubstituted aralkyl group, wherein all E groups are not hydrogen atoms at the same time, and n represents an integer of from 1 to 9,
• A(H)n (a)
• wherein A in (a) is the same as in formula (I), H represents a hydrogen atom, and n represents an integer of from 1 to 9.