Gallium naphthalocyanine salts for use as improved infrared dyes

Abstract

There is provided an IR-absorbing naphthalocyanine dye of formula (I): wherein M is Ga(A1); A1 is an axial ligand selected from —OH, halogen, —OR3, —OC(O)R4 or —O(CH2CH2O)eRe wherein e is an integer from 2 to 10 and Re is H, C1-8 alkyl or C(O)C1-8 alkyl; R1 and R2 may be the same or different and are selected from hydrogen or C1-12 alkoxy; R3 is selected from C1-12 alkyl, C5-12 aryl, C5-12 arylalkyl or Si(Rx)(Ry)(Rz); R4 is selected from C1-12 alkyl, C5-12 aryl or C5-12 arylalkyl; Rx, Ry and Rz may be the same or different and are selected from C1-12 alkyl, C5-12 aryl, C5-12 arylalkyl, C1-12 alkoxy, C5-12 aryloxy or C5-12 arylalkoxy; and each B is independently selected from a base, wherein BH+ has a pKa of between 4 and 9. The dye is suitable for use in IR-absorbing inkjet inks, providing compatibility with known CMYK inks together with an optimally red-shifted λmax.

Dependencies are inferred from the claim text.