Photopolymerisable layered composite for producing flexo printing elements

A process for producing a photopolymerizable, cylindrical, continuous, seamless, flexographic printing element from a laminate comprising

• a) a photopolymerizable relief-forming layer comprising an elastomeric binder, ethylenically unsaturated monomers, a photoinitiator, and optionally further additives;
• b) an optionally photopolymerizable elastomeric substrate layer comprising an elastomeric binder, optionally ethylenically unsaturated monomers, a photoinitiator, and optionally further additives;
• wherein said photopolymerizable relief-forming layer a) has a hardness of 30 to 70° Shore A and said optionally photopolymerizable elastomeric substrate layer b) has a hardness of from 75° Shore A to 70° Shore D in the photopolymerized state, and wherein said optionally photopolymerizable elastomeric substrate layer b) has a hardness of at least 5° Shore A greater than that of said photopolymerizable relief-forming layer a), comprising:
• (i) cutting the edges of the laminate to be joined to size by means of mitre cuts;
• (ii) pushing on and locking a hollow cylinder on a rotatably mounted support cylinder;
• (iii) applying an adhesion-promoting layer to the outer surface of the hollow cylinder;
• (iv) mounting the laminate cut to size, with the optionally photopolymerizable elastomeric substrate layer b), on the hollow cylinder provided with the adhesion-promoting layer, the ends provided with the mitre cut resting substantially one on top of the other but not overlapping;
• (v) optionally peeling off a cover sheet from said photopolymerizable relief-forming layer a);
• (vi) joining the cut edges by bringing the surface of the photopolymerizable layer on the hollow cylinder into contact with a rotating calender roll with heating until the cut edges are joined to one another;
• and
• (vii) removing the processed hollow cylinder from the support cylinder.