Red colorant composition and magenta inkjet ink composition with stable pH

A magenta inkjet ink composition with good pH value stability, comprising:

• at least one reactive red colorant;
• at least one azo red dye having formula (I):
• wherein
• R1 is hydrogen or an aliphatic radical having from 1 to 6 carbon atoms;
• n is 2, 3, or 4;
• X is NR3R4 wherein
• R3 and R4 are independently hydrogen, aralkyl, unsubstituted aryl or an aryl substituted by COOM or SO3M;
• or
• R3 and R4 form a ring with or without inclusion of a hetero atom;
• or
• X is SR5 in which R5 is alkyl from 1 to 6 carbon atoms, C2 to C6 substituted alkyl where the substituents are OH, OCH3, COOM, or SO3M;
• or
• X is OR6 in which R6 is hydrogen or an aliphatic radical having from 1 to 6 carbon atoms;
• R7 is hydrogen, alkyl of 1 to 6 carbon atoms, C2 to C6 substituted alkyl where the substituents are CN, COOM, OH, COOCH3, COOCH2CH3;
• unsubstituted aryl or aryl substituted by CH3 or halogen;
• and
• M is hydrogen, a metal atom, an ammonium or ammonium substituted with alkyl, alkoxyalkyl and hydroxyalkyl each having 1 to 12 carbon atoms;
• and
• an aqueous solution medium.

An inkjet printing method comprising the following steps:

• providing a magenta inkjet ink composition including at least one reactive red colorant, at least one azo red dye, and an aqueous solution medium;
• and
• ejecting the magenta inkjet ink composition onto a print medium,
• wherein the azo red dye has formula (I)
• wherein
• R1 is hydrogen or an aliphatic radical having from 1 to 6 carbon atoms;
• n is 2, 3, or 4;
• X is NR3R4 wherein
• R3 and R4 are independently hydrogen, aralkyl, unsubstituted aryl or an aryl substituted by COOM or SO3M;
• or
• R3 and R4 form a ring with or without inclusion of a hetero atom;
• or
• X is SR5 in which R5 is alkyl from 1 to 6 carbon atoms, C2 to C6 substituted alkyl where the substituents are OH, OCH3, COOM, or SO3M;
• or
• X is OR6 in which R6 is hydrogen or an aliphatic radical having from 1 to 6 carbon atoms;
• R7 is hydrogen, alkyl of 1 to 6 carbon atoms, C2 to C6 substituted alkyl where the substituents are CN, COOM, OH, COOCH3, COOCH2CH3;
• unsubstituted aryl or aryl substituted by CH3 or halogen;
• and
• M is hydrogen, a metal atom, an ammonium or ammonium substituted with alkyl, alkoxyalkyl and hydroxyalkyl each having 1 to 12 carbon atoms.