Integral membrane layer formed from a photosensitive layer in an imageable photoresist laminate

An integral membrane can be formed in sheet-like photosensitive laminate structures. The process for forming the structure involves coating a first relatively thin photosensitive layer on a substrate or carrier film, then forming a second relatively thicker photosensitive layer (when compared to the first layer) on the first layer. The structure is exposed by directing appropriate actinic radiation against the substrate, film or carrier layer under controlled conditions such that only the first layer is substantially exposed to radiation resulting in polymerization or crosslinking and a substantial reduction in the solubility of the first layer. The relatively thinner less soluble layer then acts as a peelable integral release layer in the photosensitive structure. The thicker second layer can then be imagewise exposed to actinic radiation, and then used conventionally in imaging processes such as sandblasting.