PHOTOSENSITIVE, FLEXO PRINTING ELEMENT AND METHOD FOR THE PRODUCTION OF NEWSPAPER FLEXO PRINTING PLATES

摘要

A photosensitive flexo printing element for production of newspaper printing plates has a total thickness of 300-1000 mm and contains an organically-developable photopolymerizable layer with a plasticizer content of 5-50 wt%, in which the elastomeric binder shows a wt.-average mol. wt. of 80000-150000 and a Shore A hardness of 50-80. Photosensitive flexo printing elements for the production of newspaper printing plates, comprising: (A) a flexible metallic base with an adhesive layer; (B) an organically-developable photopolymerizable layer (elastomeric binder, unsaturated monomers, photoinitiator (system) and plasticizer); (C) a transparent substrate layer; and (D) optionally a strippable protective film. The total thickness of the element is 300-1000 microns, the binder shows a wt.-average mol. wt. of 80000-150000 and a Shore A hardness of 50-80 and the plasticizer content of layer (B) is 5-50 wt%. Independent claims are also included for: (1) a method for the production of flexo printing plates for newspaper printing by exposing an element as described above to light so as to form an image, removing the substrate layer and developing with organic solvent(s) and then drying the layer at 105-160[deg]C; (2) printing forms obtained by this method; (3) flexo printing elements as described above in which layer (C) is a layer in which images can be formed digitally; (4) a method for the production of flexo printing plates by direct laser engraving involving (a) photocrosslinking over the whole surface of the flexo printing element and (b) engraving a relief print to a depth of at least 0.03 mm in the crosslinked relief layer with a laser, the transparent substrate layer (C) being removed before stage (a), between stages (a) and (b), or after stage (b).