NEAR-INFRARED (NIR) TRANSPARENT NEUTRAL BLACK SOLID SOLUTION PIGMENT

The present invention relates to a solid solution comprising (a) at least one compound according to formula (I), and (b) at least one compound according to formula (II), or at least one compound according to formula (III), or a mixture of at least one compound according to formula (II) and at least one compound according to formula (III), wherein R1 and R2 may, independently of one another, stand for -(CH2)n-X, wherein X stands for hydrogen, methyl, a C1-C5 alkoxyl, hydroxy, phenyl, C1-C5 alkylphenyl, C1-C5 alkoxyphenyl, hydroxyphenyl, halogenated phenyl, pyridyl, C1-C5 alkylpyridyl, C1-C5 alkoxypyridyl, halogenated pyridyl, pyridylvinyl or naphthyl; wherein n stands for 0, 1, 2, 3, 4 or 5; R3 and R4 may, inde- pendently of one another, stand for phenylene, C1-C5 alkylphenylene, C1-C5 alkoxyphenylene, hydroxyphenylene, halogenated phenylene, pyridinediyl, C1-C5 alkylpyridinediyl, C1-C5 alkoxy- pyridinediyl, halogenated pyridinediyl, anthraquinonediyl or naphthalenediyl, wherein the 2 ni- trogen atoms bound to R3 according to formula (II) and (III) form a 5-membered or a 6- membered heterocycle with 2 atoms of an aromatic ring of R3; wherein the 2 nitrogen atoms bound to R4 according to formula (II) and (III) form a 5-membered or a 6-membered heterocycle with 2 atoms of an aromatic ring of R4; X1 to X8 may, independently from one another, stand for hydrogen, C1-C5 alkyl, C1-C5 alkoxy, hydroxy, phenyl or halide. The present invention further relates to a process for producing the solid solution. Furthermore, the present invention relates to a solid solution obtainable or obtained according to said process and to the use of the inventive solid solution, in particular as as a NIR transparent black colorant in a NIR non-absorbing component.