| abstract |
The present invention discloses an azo compound represented by the following formula (1), its salt or its copper complex salt compound (In this formula, R1 and R2 independently represent a hydrogen atom, a sulfonic acid group, a lower alkyl or a lower alkoxy; R3-R6 independently represent a hydrogen atom, a lower alkyl or a lower alkoxy; R7 represent a lower alkoxy radical or lower alkoxy; and n represents 0 or 1). |