VLAKDRUKPLAAT ALSMEDE WERKWIJZE VOOR HET VERLENEN VAN GEWENSTE DRUKPARTIJEN AAN DE PLAAT.

摘要

The adherence of the oleophilic polymer printing surface of a lithographic printing plate to the support of the lithographic printing plate is improved by an anchoring layer formed from a hydrophobic oleophilic ester colloid which is capable of being rendered hydrophilic by treatment with an aqueous alkali solution. After an image-wise exposure of the photosensitive layer of the presensitized photosensitive sheet used to prepare the lithographic printing plate and removal of the non-polymerized (non-image) portions of the photosensitive layer the plate is contacted with an aqueous alkali solution to render those portions of the anchoring layer, which have been exposed by removal of the non-polymerized portions of the photosensitive layer, hydrophilic. Accordingly, the portions of the anchoring layer underlying the oleophilic hardened polymeric printing surface remain hydrophobic oleophilic and therefore can increase the number of satisfactory printings which can be made from the lithographic printing plate.