Abstract: A radiation sensitive plate comprises a substrate coated with a photopolymerisable composition. The composition comprises a polymerisable compound containing ethylenic unsaturation, a perester photoinitiator and optionally an optical sensitiser. The substrate may be a sheet of grained and anodised aluminum and the plate is useful in the production of lithographic printing plates.

Abstract: A radiation-sensitive compound, which comprises a polymer including a plurality of azide-substituted aromatic ester groups and a plurality of carboxylic or sulphonic acid groups capable of imparting to the compound solubility in aqueous or alkaline medium. After image-wise exposure, the compound can be developed using an aqueous or alkaline developer. The compound is useful in the production of radiation sensitive plates for the manufacture of lithographic printing plates which can be baked to improve printing life.

Abstract: A polymeric compound is derived from a polyhydric material and has pendant sulphonate groups of the general formula ##STR1## and pendant alkyl urethane groups of the formula ##STR2## where X is an aliphatic, aromatic, carboxylic or heterocyclic group; Y is hydrogen, halogen or an alkyl, aryl, alkoxy, aryloxy or aralkyl group, CO.sub.2.sup.- Z.sup.+, CO.sub.2 R or SO.sub.3.sup.- Z.sup.+ ; Z.sup.+ is a cationic counter ion and R is hydrogen alkyl, alkylene, aryl or aralkyl group.

Abstract: A radiation sensitive plate comprises a substrate coated with a photopolymerizable composition. The composition comprises a polymerizable compound containing ethylenic unsaturation, a perester photoinitiator and optionally an optical sensitiser. The substrate may be a sheet of grained and anodized aluminum and the plate is useful in the production of lithographic printing plates.

Abstract: A printing plate precursor comprises a substrate coated with a radiation sensitive composition comprising a photoinitiator and a photopolymerizable urethane acrylate or methacrylate. The urethane acrylate or methacrylate is produced by partial acrylation or methacrylation of a tetrafunctional polyol and the remaining hydroxy groups of the polyol are reacted with a di or polyisocyanate.

Abstract: Perester compounds suitable for causing the polymerisation of addition polymerisable compounds on exposure to radiation have the general formulae ##STR1##

Abstract: A printing plate precursor comprises a substrate coated with a radiation sensitive composition overcoated with a barrier layer to prevent oxygen inhibiting photopolymerization of the composition. The barrier layer comprises a polymer and an amphoteric compound.

Abstract: Radiation sensitive material suitable for the production of radiation sensitive plates for lithographic printing plate manufacture is based on a polymer including a plurality of structural units represented by the formula: ##STR1## in which, R represents H or CH.sub.3 ; each R.sub.1, which may be the same or different represents H or alkyl; R.sub.2 represents a single bond or a substituted or unsubstituted divalent radical; Ar represents a substituted or unsubstituted divalent radical derived from an aromatic or heteroaromatic compound; X represents O, S or NH; A represents an anion; Y represents a carbonyl oxy or aromatic radical; and n is an integer equal to or greater than 1.

Abstract: A radiation sensitive compound contains at least two groups having the structure ##STR1## in which Ar represents a divalent or other polyvalent radical derived from an aromatic or heteroaromatic compound; X and X' which may be the same or different, each represents O, S or an imino group, provided that at least one of X and X' is an imino group; Y represents O or S; R represents a single bond or a divalent or other polyvalent radical and A.sup.- is an anion. Radiation sensitive compositions comprising the compound and optionally a resin may be used to produce radiation sensitive plates for lithographic printing plate production.