| 摘要 |
A positive-working imaging element is described comprising a support coated first with a negative-working, solvent-developable, photohardenable stratum, then over-coated with a second negative-working, solvent-developable, photohardenable stratum; the second stratum serves as a mask for the first stratum since it contains ingredients which strongly absorb radiation actinic to the first stratum. The second stratum is imagewise exposed, solvent developed, and the resulting actinically opaque image used as a negative in exposing the first stratum, which is solvent developed to remove the composition in unexposed, but not in exposed areas. Optionally, a separating layer can be present between the photohardenable strata and a cover layer can be present over the second stratum. Positive-working low relief images suitable for lithographic printing plates, printed circuit resists, and contact-speed lithographic films are obtained from the elements of this invention. |
