Radiation-sensitive mixture comprising IR-absorbing, anionic cyanine dyes and recording material prepared therewith

A positive-working, radiation-sensitive mixture comprising:

• an organic, polymeric binder which is insoluble in water but soluble or at least swellable in aqueous alkaline solution, and
• at least one IR-absorbing anionic cyanine dye, of the formula (I)
• wherein
• n is 2 or 3,
• R1 to R8 independently of one another, are a hydrogen or halogen atom, a sulfonate, carboxylate, phosphonate, hydroxyl, (C1-C4) alkoxy, nitro, amino, (C1-C4) alkylamino or di(C1-C4) alkylamino group or a (C6-C10) aryl group which in turn may be substituted by one or more halogen atoms and/or one or more sulfonate, carboxylate, phosphonate, hydroxyl, (C1-C4) alkoxy, nitro, amino, (C1-C4) alkylamino and/or di(C1-C4) alkylamino groups,
• R9 and R10 independently of one another, are a straight-chain or branched (C1-C6) alkyl, a (C7-C16) aralkyl or a (C6-C10) aryl group, each of which in turn may be substituted by one or more halogen atoms and/or one or more sulfonate, carboxylate, phosphonate, hydroxyl, (C1-C4) alkoxy, nitro, amino, (C1-C4) alkylamino and/or di(C1-C4) alkylamino groups,
• Z1 and Z2 independently of one another, are a sulfur atom, a di(C1-C4) alkylmethylene group or an ethene-1,2-diyl group and
• X+ is a cation,
• with the proviso that the dye contains from 2 to 4 sulfonate, carboxylate and/or phosphonate groups but altogether not more than two sulfonate groups.