Photopolymerisation process with two exposures of a single layer

A process for production of an image which comprises

• (1) exposing to actinic radiation a layer, supported on a carrier, of a liquid composition containing a compound (A) having in the same molecule both at least one group of formula ##STR47## and at least one group of formula ##STR48## such that the layer solidifies and becomes essentially nontacky due to photopolymerisation of (A) through the group or groups of formula I but remains substantially photocrosslinkable, and subsequently P1 (2) exposing as through an image-bearing transparency consisting of substantially opaque and substantially transparent areas at least part of the layer so solidified to a substantially greater amount of actinic radiation such that the further exposed part or parts of the photopolymerised layer undergo photocrosslinking through the group or groups of formula II, and
• (3) developing the image by dissolving in a solvent parts of the layer which have not become substantially photocrosslinked, where
• R denotes a hydrogen atom or a methyl group,
• a is zero or an integer of from 1 to 4,
• R.sub.1 denotes a methyl group, or, if a is 1, may alternatively denote an allyl group,
• R.sup.2 denotes a hydrogen atom, a carboxyl group, a carbonyloxyalkyl group (which may be interrupted in the chain by an ether oxygen atom), a carbonyloxyalkene group joined through an oxygen atom to a group of formula I, the alkyl or alkylene group having up to 8 carbon atoms, or together with one of the indicated free valencies, R.sup.2 denotes a cyclic imide group of structure ##STR49## and X denotes a methylene bridge, a methylene bridge substituted by one or two of the aforesaid methyl groups R.sup.1, a methylene bridge substituted by the allyl group R.sup.1, or an oxygen atom.