Near-infrared ray absorbing polyazo compound

Abstract

A polyazo compound capable of effectively absorbing near-infrared rays, which can be produced from readily available raw materials is provided, which comprises at least one --OH group or at least one group derived from --OH group at p-position of the azo group in the molecule of the polyazo compound. This compound can be produced by diazotizing a substituted or nonsubstituted aromatic monocyclic or polycyclic compound or heterocyclic compound, each having a diazotizable primary amino group, and successively coupling the resulting diazo component with an azo component having a diazotizable primary amino group, the last azo component being such that --OH group or a group derived from --OH group be present at p-position to the azo group resulting from the azo component.