Solubilized yellow dyes for inks with improved ozone and light stability

#The present invention relates to new dyes and their use in ink jet printing.

#Ink jet printing is a non-impact method for producing images by the deposition of ink droplets in a pixel-by-pixel manner to an image-recording element in response to digital signals. There are various methods that may be utilized to control the deposition of ink droplets on the image-recording element to yield the desired image. In one process, known as continuous ink jet, a continuous stream of droplets is charged and deflected in an imagewise manner onto the surface of the image-recording element, while unimaged droplets are caught and returned to an ink sump. In another process, known as drop-on-demand ink jet, individual ink droplets are projected as needed onto the image-recording element to form the desired image. Common methods of controlling the projection of ink droplets in drop-on-demand printing include piezoelectric transducers and thermal bubble formation. Ink jet printers have found broad applications across markets ranging from industrial labeling to short run printing to desktop document and pictorial imaging.

#The inks used in the various ink jet printers can be classified as either dye-based or pigment-based. A dye is a colorant, which is dissolved in the carrier medium. A pigment is a colorant that is insoluble in the carrier medium, but is dispersed or suspended in the form of small particles, often stabilized against flocculation and settling by the use of dispersing agents. The carrier medium can be a liquid or a solid at room temperature in both cases. Commonly used carrier media include water, mixtures of water and organic solvents and high boiling organic solvents, such as hydrocarbons, esters, ketones, etc.

#The invention has numerous advantages such as improved ozone and light fastness. The ink composition also has better fade resistance. The dyes of the present invention are easily synthesized by known methods, and have multiple advantages over known dye classes. Visually, the dyes appear bright yellow with very little orange tone. The inks formulated with these dyes give consistently pleasing colors and color reproduction in photographic ink jet applications. The dyes of this invention have superior light fastness and stability toward ozone compared with other dye classes, in particular when printed on porous silica or alumina based media. These and other advantages will be apparent from the detailed description below.

#The present invention solves the aforementioned problems by providing a dye and an ink for inkjet recording which can be used to produce a high quality image with preferred hue and improved light and ozone fastness. The dye is represented by the general Formula I:

#wherein R1 represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, an alkylthio group, an arylthio group an acyl group, a substituted acyl group, a carboxyl group, a carbamoyl group, or a heterocyclic group; Za represents one of —N═, —NH— or —C(R8)═; and Zb and Zc each independently represents one of —N═ or —C(R8)═; R8 represents a hydrogen, a substituted or unsubstituted alkyl or a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group or a heterocyclic group; R2 represents a hydrogen, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a halogen, a cyano group, a carboxyl or substituted carboxyl group, an acyl group, a substituted acyl group, a carbamoyl group, a nitro group, an alkyl or aryl sulfone, a sulfonic acid, a substituted or unsubstituted primary or secondary alkyl sulfonamide, a substituted or unsubstituted aryl sulfonamide or a heterocyclic group; R3 may be hydrogen or any non-metallic group; R4, R5, R6 may be H or any non-metallic group with the proviso that at least one of R4 or R6 represents any ionizable group which is capable of imparting water solubility to the dye; R5 may be present in any other position on the aromatic ring that is not occupied by R4 or R6; Any two of either R4 and R5 or R5 and R6 may be part of a carbocyclic or heterocyclic ring that is fused to the aromatic ring attached to the pyrazole nitrogen, with the proviso that at least one group capable of imparting water solubility to the dye is present in any position of either fused ring; R5 may be part of a carbocyclic or heterocyclic ring that is fused to the aromatic ring attached to the pyrazole nitrogen in any two adjacent positions not occupied by R4 or R6 with the proviso that at least one of R4 or R6 represents any ionizable group which is capable of imparting water solubility to the dye.