DOUBLE-EXPOSURE METHOD FOR PRODUCING REVERSE IMAGES IN PHOTOPOLYMERS

摘要

For the production of reverse images, a photosensitive element comprising a polymerizable (or crosslinkable) material and two photoinitiators responsive to different wavelengths of actinic radiation is exposed successively to actinic radiation of wavelengths appropriate for the two photoinitiators. The first exposure is imagewise and the second is nonimagewise. A polymerization inhibitor is present during both exposures. The method is useful in the graphic arts where a positive-working system is required, e.g., for relief or planographic printing plates, direct positive copying films, and the like.