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: 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.