Patent classifications
B41C1/1041
Relating to printing
A method of preparing a printing form precursor for printing, or a printed circuit board precursor or a semiconductor precursor, the method comprising the step of applying electromagnetic radiation having a pulse duration of not greater than 110.sup.6 seconds, in an imagewise manner, to an imagable surface of the precursor. The imaging process may cause ablation of the coating of the precursor or permit its development in a developer. In each case the imaging radiation needs not be tuned to imaging chemistry (if any) present in the coating. Alternatively the imaging process may induce a change of hydrophilicity or hydrophobicity, or other change of state, of an uncoated substrate.
Lithographic developer composition and method of use
Lithographic printing plates are formed by imagewise exposing a single-layer or dual-layer positive-working lithographic printing plate precursor. The precursor has an outermost ink receptive layer containing a phenolic resin. The exposed precursor can be processed using a silicate-free developer composition having a pH of at least 12.5. This composition also includes an alkali metal hydroxide; a coating protecting agent that is a quaternary ammonium salt or phosphonium salt, or a mixture thereof, and a moderator for the coating protecting agent that is represented by the following general formula (I): ##STR00001##
wherein m is at an integer of at least 1 and up to and including 10 and M represents one or more counterions sufficient to balance the negatively-charged sulfonate groups.
Method of printing using a reimageable printing plate with an aluminum oxide surface
A printing form precursor comprises a printing surface which comprises an inorganic metal compound, the printing surface being hydrophobic and capable of being made hydrophilic by energy but capable of becoming hydrophobic again, for reuse, if desired. An associated method of printing includes steps of subjecting the printing surface imagewise to energy so as to locally increase its hydrophilicity sufficient to make the surface differentiated in its acceptance of an oleophilic a printing ink; applying the ink to the printing surface and printing from the printing surface; causing or allowing the printing surface to undergo a reduction in hydrophilicity sufficient again to make the printing surface uniform in its acceptance of a printing ink; and, if wished, repeating these steps on multiple occasions. Thus the invention achieves the goal of providing a printing form precursor which does not need a chemical developer, and which can be used multiple times, to print different images.