Photohardenable films having high resolution containing nitroso dimers

Claim 1

A photohardenable film consisting essentially of: (a) a substantially solid organic composition comprising an addition-polymerizable, nongaseous ethylenically unsaturated compound capable of forming a high polymer by free-radical initiated chain-propagating addition polymerization, and a macromolecular organic polymeric binder, (b) 0.04-3% by weight, based on the total film material, of solvent-soluble nitroso dimer which is a noninhibitor of free-radical polymerization but dissociates to nitroso monomer which is an inhibitor of free-radical polymerization, contains a dinitroso group, and is characterized by a dissociation constant of 10 -2 -10 -10 in solution at 25° C. and a rate of dissociation having a half-life of at least 0.5 minute in solution at 25° C., and (c) 1.0-10% by weight, based on the total film material, of an organic, radiation-sensitive free-radical generating system based on a 2,4,5-triarylimidazolyl dimer and a free-radical producing electron doner system, with the proviso that the weight ratio of nitroso dimer to free-radical generating system is no greater than 2:1, said free-radical generating system being proportioned to give said film at its particular thickness a mean optical density of 0.02-1.25 to radiation in the spectral region in which the free-radical generating system absorbs radiation.