Radiation-sensitive elements and their storage stability

A radiation-sensitive element comprising

• (a) a substrate with at least one hydrophilic surface and
• (b) a radiation-sensitive coating on at least one hydrophilic surface of the substrate, wherein the coating comprises:
• (i) at least one free-radical polymerizable monomer, oligomer, polymer or mixture thereof with at least one ethylenically unsaturated group each,
• (ii) at least one photoinitiator or sensitizer, which is capable of absorbing radiation of a wavelength in the range of 250 to 1,200 nm,
• (iii) at least one stabilizer compound comprising at least one group capable of inhibiting free-radical polymerization, and at least one other group capable of sorption at the hydrophilic surface of the substrate, and
• (iv) optionally at least one additive comprising coinitiators which form free radicals after the excitation of the photoinitiator or sensitizer with radiation of a wavelength of 250 to 1,200 nm, binders, dyes, plasticizers, chain transfer agents, leuco dyes, inorganic fillers, surfactants or polymerization inhibitors not suitable for sorption at the surface of the substrate.

A process for the production of a radiation-sensitive element comprising the steps of:

• (a) providing an optionally pretreated substrate having a hydrophilic surface;
• (b) applying a radiation-sensitive mixture comprising
• (i) at least one free-radical polymerizable monomer, oligomer, polymer or mixture thereof with at least one ethylenically unsaturated group each,
• (ii) at least one photoinitiator or sensitizer, which is capable of absorbing radiation of a wavelength in the range of 250 to 1,200 nm,
• (iii) at least one stabilizer compound comprising at least one group capable of sorption at the hydrophilic surface of the substrate, and at least one other group capable of inhibiting free-radical polymerization,
• (iv) a solvent or solvent mixture, and
• (v) optionally at least one additive comprising coinitiators which form free radicals after the excitation of the photoinitiator or sensitizer with radiation of a wavelength of 250 to 1,200 nm, binders, dyes, plasticizers, chain transfer agents, leuco dyes, inorganic fillers, surfactants or polymerization inhibitors not suitable for sorption at the surface of the substrate;
• and
• c) drying.

A process for the production of a radiation-sensitive element comprising the steps of:

• (a) providing an optionally pretreated substrate having a hydrophilic surface;
• (b) applying a mixture that is not radiation-sensitive comprising at least one solvent and at least one stabilizer compound comprising at least one group capable of sorption at the substrate and at least one group capable of inhibiting free-radical polymerization;
• (c) drying;
• (d) applying a radiation-sensitive mixture comprising
• (i) at least one free-radical polymerizable monomer, oligomer, polymer or mixture thereof with at least one ethylenically unsaturated group,
• (ii) at least one photoinitiator or sensitizer, which is capable of absorbing radiation of a wavelength in the range of 250 to 1,200 nm,
• (iii) a solvent or solvent mixture, and
• (iv) optionally at least one additive comprising coinitiators which form free radicals after the excitation of the photoinitiator or sensitizer with radiation of a wavelength of 250 to 1,200 nm, binders, dyes, plasticizers, chain transfer agents, leuco dyes, inorganic fillers, surfactants or polymerization inhibitors not suitable for sorption at the surface of the substrate;
• and
• (e) drying.

Lithographic printing form produced by a process comprising the steps of:

• (a) providing a radiation-sensitive element comprising:
• (1) a substrate with at least one hydrophilic surface and
• (2) a radiation-sensitive coating on at least one hydrophilic surface of the substrate, wherein the coating comprises:
• (i) at least one free-radical polymerizable monomer, oligomer, polymer or mixture thereof with at least one ethylenically unsaturated group each,
• (ii) at least one photoinitiator or sensitizer, which is capable of absorbing radiation of a wavelength in the range of 250 to 1,200 nm,
• (iii) at least one stabilizer compound comprising at least one group capable of inhibiting free-radical polymerization, and at least one other group capable of sorption at the hydrophilic surface of the substrate, and
• (iv) optionally at least one additive comprising coinitiators which form free radicals after the excitation of the photoinitiator or sensitizer with radiation of a wavelength of 250 to 1,200 nm, binders, dyes, plasticizers, chain transfer agents, leuco dyes, inorganic fillers, surfactants or polymerization inhibitors not suitable for sorption at the surface of the substrate.
• (b) image-wise exposure of the element with radiation of a wavelength adjusted to the absorber contained in the radiation-sensitive coating;
• (c) optionally heating the irradiated element;
• (d) removing the unexposed areas of the coating with an aqueous alkaline developer;
• and
• (e) optionally heating the developed printing form or subjecting it to overall exposure or both.