Abstract: The invention relates to a recording material having a substrate and a radiation-sensitive, water-insoluble layer which contains a component absorbing IR radiation and which, after the action of infrared radiation, becomes soluble or at least swellable in an aqueous alkaline developer. A top layer which is opaque to white light but transparent to radiation in the IR range and can be removed with water or an aqueous solution is present on the radiation-sensitive layer. The recording material is substantially insensitive to daylight. By imagewise exposure to IR radiation and subsequent development with an aqueous alkaline developer, it is possible to produce a printing plate for offset printing from the recording material. If the top layer is washed off beforehand, the recording can also be carried out using conventional UV radiation.

Abstract: A positive-working or negative-working radiation-sensitive mixture includes as an IR absorbing component a carbon black pigment having a primary particle size smaller than 80 nm. The carbon black pigment is predispersed in a polymer containing acidic units having a pK.sub.a of less than 13. The radiation-sensitive component may include an ester of (i) a 1,2-naphthoquinone-2-diazide-4-sulfonic acid or a 1,2-naphthoquinone-2-diazide-5-sulfonic acid and (ii) a compound having at least one phenolic hydroxyl group, such as 3 to 6 phenolic hydroxyl groups. After imagewise radiation exposure, the recording material including the radiation-sensitive mixture can be developed without difficulties in an aqueous alkaline solution without leaving residual coating on the areas that became soluble or that remained soluble upon exposure.