Abstract: A layer of a liquid composition containing a compound (A) having in the same molecule at least one (meth)acryloyl group and at least one bicyclo[2.2.1]hept-2-ene-6-yl unit is exposed to actinic radiation so that the layer solidifies due to photopolymerisation of (A) through the (meth)acryloyl group(s), remaining, however, photocrosslinkable. When desired, the solidified layer is exposed, as through a negative, to a substantially greater amount of actinic radiation, the parts so further exposed becoming more highly photocrosslinked through the bicyclo[2.2.1]hept-2-ene-6-yl unit(s) and hence insoluble. An image is produced which can be developed by means of suitable solvents. Examples of (A) include 3-(methacryloyloxy)-2-hydroxypropyl bicyclo[2.2.1]hept-2-ene-6-carboxylate and 2-(acryloyloxy)ethyl methyl-5-carboxybicyclo[2.2.1]hept-2-ene-6-carboxylate.

Abstract: New aromatic sulfonylsulfoxonium salts are of formula ##STR1## where q is 1 to 4,R denotes an aliphatic, cycloaliphatic, or aromatic group,R.sup.6 denotes H, an alkyl or aralkyl group, or a group --COR.sup.9, --CO--NH--(CO).sub.r --R.sup.10, or --SO.sub.2 --R.sup.11, where r is zero or 1,one, but not both, of R and R.sup.6 denoting an aromatic group,R.sup.7 denotes an alkyl, alkenyl, cycloalkyl, cycloalkylalkyl, or aralkyl group,R.sup.8 has the same meaning as R.sup.7 but may alternatively represent a dialkylamino group or, if R.sup.7 denotes alkyl, it may alternatively represent an arylamino group,R.sup.9, R.sup.10, and R.sup.11 each denote an alkyl, aryl, or aralkyl radical of 1 to 25 carbon atoms,t is 1, 2, or 3, andZ.sup.- denotes a t-valent anion of a protic acid.The salts, e.g., dimethyl-p-toluenesulfonylmethylsufoxonium hexafluorophosphate, are useful as catalysts for the polymerization of cationically polymerizable materials by means of actinic radiation and/or heat.

Abstract: Diepoxides which may be photopolymerized in the presence or absence of a photosensitizer contain a group having conjugated unsaturation attached to a nitrogen heterocycle, such as a hydantoin or barbituric acid residue, forming part of an advanced diepoxide. The resultant photopolymer may be crosslinked by heating in the presence of a curing agent for epoxide resins.The diepoxides are of use in the production of printing plates and printed circuits, especially multilayer printed circuits.