An ink set contains a first ink containing a compound in which a pyrazolone ring and a thiazole ring are bonded and a second ink containing a compound in which a pyrazolone ring and a pyridinedione ring are bonded. A thermal transfer recording sheet has a first ink layer containing a compound in which a pyrazolone ring and a thiazole ring are bonded and a second ink layer containing a compound in which a pyrazolone ring and a pyridinedione ring are bonded.

An ink-jet ink set includes a black ink containing carbon black; a cyan ink containing a first cyan dye; a magenta ink containing a first magenta dye; a yellow ink containing a first yellow dye; and a gray ink containing a second cyan dye, a second magenta dye, and a second yellow dye. The cyan ink, the magenta ink, the yellow ink, and the gray ink have a ROD of 65% or more, the ROD being defined by Equation (A). The gray ink has an OD value of 1.40 to less than 2.30, the OD value being defined by Equation (B).

An object of the present invention is to provide a thermal transfer recording sheet that enables images having a wide color gamut, a high chroma, and good lightfastness, in which the degree of catalytic fading is reduced, to be formed. The thermal transfer recording sheet includes a base material and a colorant layer on the base material. The colorant layer includes a yellow dye layer, a magenta dye layer, and a cyan dye layer. The dye layers each include, as a dye, a compound having a specific structure.

Provided is a pigment dispersion excellent in the dispersibility of C.I. Pigment yellow 185. The pigment dispersion includes C.I. Pigment yellow 185 and a compound represented by the following formula (1), which are dispersed in a dispersing medium: ##STR00001##

The present invention refers to dyes of the formula (I) and mixtures thereof ##STR00001##
a process for their production and to their use.

The invention relates to compounds of the formula (I):

##STR00001## in which R.sup.0 is C.sub.1-C.sub.6-alkyl or CF.sub.3; R.sup.1 is sulfo, carboxyl, C.sub.1-C.sub.4-alkylenesulfo, C.sub.1-C.sub.4-alkylenecarboxy, CONH.sub.2, CONH(C.sub.1-C.sub.4-alkyl) or CN, R.sup.2 is C.sub.1-C.sub.18-alkyl, C.sub.2-C.sub.18-alkenyl, hydroxy-C.sub.1-C.sub.18-alkyl, or (C.sub.1-C.sub.6-alkylene-O).sub.mR where R is defined as H, C.sub.1-C.sub.16-alkyl or hydroxy-C.sub.1-C.sub.16-alkyl and m is a number from 1 to 20, R.sup.3 is H, sulfo, carboxyl, C.sub.1-C.sub.6-alkyl or C.sub.1-C.sub.6-alkoxy, R.sup.4 is H, C.sub.1-C.sub.6-alkyl or C.sub.1-C.sub.6-alkoxy, R.sup.5 is OH, OM, C.sub.1-C.sub.6-alkyl, unsubstituted C.sub.6-C.sub.10-aryl or C.sub.1-C.sub.6-alkyl-, halogen-(e.g. F, Cl, Br), carboxyl- or sulfo-substituted where the compounds of the formula (I) contain at least one anionic radical from the group of sulfo and carboxyl having the countercation M.sup.+, where M.sup.+ is an alkali metal cation or an organic cation.

The compounds of the formula (I) are especially suitable for use in color filters.

The invention relates to a colorant composition comprising at least one compound of the formula (I) and at least one pigment, in which the compounds of the formula (I) have the following formula:

##STR00001##

in which R.sup.0 is C.sub.1-C.sub.6-alkyl or CF.sub.3; R.sup.1 is sulfo, carboxyl, C.sub.1-C.sub.4-alkylenesulfo, C.sub.1-C.sub.4-alkylenecarboxy, CONH.sub.2, CONH(C.sub.1-C.sub.4-alkyl) or CN, R.sup.2 is C.sub.1-C.sub.18-alkyl, C.sub.2-C.sub.18-alkenyl, hydroxy-C.sub.1-C.sub.18-alkyl, or (C.sub.1-C.sub.6-alkylene-O).sub.mR where R is defined as H, C.sub.1-C.sub.16-alkyl or hydroxy-C.sub.1-C.sub.16-alkyl and m is a number from 1 to 20, R.sup.3 is H, sulfo, carboxyl, C.sub.1-C.sub.6-alkyl or C.sub.1-C.sub.6-alkoxy, R.sup.4 is H, C.sub.1-C.sub.6-alkyl or C.sub.1-C.sub.6-alkoxy, R.sup.5 is OH, OM, C.sub.1-C.sub.6-alkyl, unsubstituted C.sub.6-C.sub.10-aryl or C.sub.1-C.sub.6-alkyl-, halogen- (e.g. F, Cl, Br), carboxyl- or sulfo-substituted C.sub.6-C.sub.10-aryl,
where the compounds of the formula (I) contain at least one anionic radical from the group of sulfo and carboxyl having the countercation M.sup.+, where M.sup.+ is an alkali metal cation or an organic cation.

The colorant compositions are especially suitable for use in color filters.