Lithographic printing plates having a thin releasable interlayer overlying a rough substrate

A method of manufacturing a lithographic printing plate, comprising:

• (a) providing a substrate with tough and/or porous surface on at least one side, said rough and/or porous surface comprising a microscopic structure selected from the group consisting of irregular peaks, valleys, holes, and pores that are capable of mechanical interlocking with a coating deposited thereon;
• (b) depositing a releasable interlayer on the rough and/or porous surface of said substrate, said releasable interlayer being soluble or dispersible in a liquid selected from the group consisting of water, fountain solution, ink, aqueous and solvent plate developers, organic solvents, and press cleaners;
• wherein said releasable interlayer is substantially conformally coated on the microscopic structures of the substrate surface and is thin enough in thickness so that, the releasable interlayer coated substrate has microscopic surface profiles similar to those of the substrate, and a coating on the releasable interlayer is capable of bonding to the substrate through mechanical interlocking and is incapable of being removed without deforming or breaking the coating or the substrate surface structures even if the releasable interlayer is dissolved away;
• and
• (c) depositing on the releasable interlayer a radiation-sensitive layer, said radiation-sensitive layer exhibiting an affinity or aversion substantially opposite to the affinity or aversion of said substrate to at least one printing liquid selected from the group consisting of ink and an abhesive fluid for ink.

A method of lithographically printing images on a receiving medium, comprising:

• (a) providing a lithographic printing plate comprising:
• (i) a substrate with rough and/or porous surface on at least one side, said rough and/or porous surface comprising a microscopic structure selected from the group consisting of irregular peaks, valleys, holes, and pores that are capable of mechanical interlocking with a coating deposited thereon;
• (ii) a releasable interlayer deposited on the rough and/or porous surface of said substrate, said releasable interlayer being soluble or dispersible in ink (for waterless plate) or in ink and/or fountain solution (for wet plate);
• wherein said releasable interlayer is substantially conformally coated on the microscopic structures of the substrate surface and is thin enough in thickness so that, the releasable interlayer coated substrate has microscopic surface profiles similar to those of the substrate, and a coating on the releasable interlayer is capable of bonding to the substrate through mechanical interlocking and is incapable of being removed without deforming or breaking the coating or the substrate surface structures even if the releasable interlayer is dissolved away;
• and
• (iii) a radiation-sensitive layer capable of hardening or solubilization upon exposure to an actinic radiation, the non-hardened or solubilized areas of said radiation-sensitive layer being soluble or dispersible in ink (for waterless plate) or in ink and/or fountain solution (for wet plate), and said radiation-sensitive layer exhibiting an affinity or aversion substantially opposite to the affinity or aversion of said substrate to at least one printing liquid selected from the group consisting of ink and an abhesive fluid for ink;
• (b) exposing the plate with an actinic radiation to cause hardening or solubilization of the exposed areas;
• (c) directly placing the exposed plate on a printing press equipped with ink (for waterless plate) or with both ink and fountain solution (for wet plate);
• and
• (d) operating said printing press to contact said exposed plate with ink or with ink and/or fountain solution to remove the non-hardened or solubilized areas, and to lithographically print images from said plate to the receiving medium.

A substrate-release layer component, suitable for the manufacture of lithographic printing plates by further depositing a radiation-sensitive layer on the release layer to form a pre-sensitized plate or by imagewise transferring an image-forming material from an external material source onto the release layer to form an imaged plate, comprising:

• (a) a substrate with rough and/or porous surface on at least one side, said rough and/or porous surface comprising a microscopic structure selected from the group consisting of irregular peaks, valleys, holes, and pores that are capable of mechanical interlocking with a coating deposited thereon;
• and
• (b) a release layer deposited on the rough and/or porous surface of said substrate, said release layer being soluble or dispersible in a liquid selected from the group consisting of water, fountain solution, ink, aqueous and solvent plate developers, organic solvents, and press cleaners;
• wherein said release layer is substantially conformally coated on the microscopic structures of the substrate surface and is thin enough in thickness so that, the release layer coated substrate has microscopic surface profiles similar to those of the substrate, and a coating on the release layer is capable of bonding to the substrate through mechanical interlocking and is incapable of being removed without deforming or breaking the coating or the substrate surface structures even if the release layer is dissolved away.