Laser-imageable printing members and methods for wet lithographic printing
AssigneePresstek, Inc.
InventorsThomas E. Lewis, Kenneth R. Cassidy
Life of this patent
Estimating the term…
Abstract
Lithographic printing constructions and methods of imaging them. The constructions include a grained-metal substrate, a protective layer that can also serve as an adhesion-promoting primer, and an ablatable oleophilic surface layer. In operation, imagewise pulses from an imaging laser interact with the surface layer, causing ablation thereof and, probably, inflicting some damage to the underlying protective layer as well. The imaged plate may then be subjected to a solvent that eliminates the exposed protective layer, but which does no damage either to the surface layer or to the unexposed protective layer lying thereunder.
Claims31
A lithographic printing member directly imageable by laser discharge, the member comprising:
- a. an ink-accepting first layer characterized by ablative absorption of imaging radiation;
- b. a second layer underlying the first layer, the second layer not being characterized by ablative absorption of imaging radiation and being compatible with but not excessively soluble in a cleaning solvent;
- and
- c. a hydrophilic metal substrate,
- d. the first layer and the substrate not being soluble in the cleaning solvent.
The member of 1 wherein the substrate is chromium having a textured surface topography.
A lithographic printing member directly imageable by laser discharge, the member comprising:
- a. an ink-accepting first layer characterized by ablative absorption of imaging radiation;
- b. a second layer underlying the first layer, the second layer being hydrophilic and compatible with but not excessively soluble in a cleaning solvent;
- and
- c. a hydrophilic metal substrate,
- d. the first layer and the substrate not being soluble in the cleaning solvent.
A lithographic printing member directly imageable by laser discharge, the member comprising:.
- a. an ink-accepting first layer characterized by ablative absorption of imaging radiation;
- b. a second layer underlying the first layer, the second layer not being characterized by ablative absorption of imaging radiation and being compatible with but not excessively soluble in a cleaning solvent;
- and
- c. a hydrophilic metal substrate,
- wherein the second layer is polymeric.
A lithographic printing member directly imageable by laser discharge, the member comprising:
- a. an ink-accepting first layer characterized by ablative absorption of imaging radiation and comprising a nitrocellulose compound;
- b. a second layer underlying the first layer, the second layer being compatible with but not excessively soluble in a cleaning solvent;
- and
- c. a hydrophilic metal substrate.
A lithographic printing member directly imageable by laser discharge, the member comprising:
- a. an ink-accepting first layer characterized by ablative absorption of imaging radiation;
- b. a second layer underlying the first layer, the second layer being compatible with but not excessively soluble in a cleaning solvent;
- and
- c. a hydrophilic metal substrate,
- wherein the second layer is selected from the group consisting of polyvinylphosphonic acid, polyvinylmethylphosphonic acid, phosphoric acid esters of polyvinyl alcohol, polyvinylsulfonic acid, polyvinylbenzenesulfonic acid, sulfuric acid esters of polyvinyl alcohol, and acetals of polyvinyl alcohols formed by reaction with a sulfonated aliphatic aldehyde.
A lithographic printing member directly imageable by laser discharge, the member comprising:
- a. an ink-accepting first layer characterized by ablative absorption of imaging radiation;
- b. a second layer underlying the first layer, the second layer being compatible with but not excessively soluble in a cleaning solvent;
- and
- c. a hydrophilic metal substrate,
- wherein the second layer is selected from the group consisting of polyvinyl pyrrolidone, cellulose ethers, casein, and gelatins.
A lithographic printing member directly imageable by laser discharge, the member comprising:
- a. an ink-accepting first layer characterized ablative absorption of imaging radiation;
- b. a polymeric, hydrophilic second layer underlying the first layer and not being characterized by ablative absorption of imaging radiation;
- and
- c. a hydrophilic metal substrate.
A method of imaging a lithographic printing member comprising the steps of:
- a. providing a lithographic printing member comprising:
- i. an ink-accepting topmost layer characterized by ablative absorption of laser radiation;
- ii. a second layer underlying the first layer, the second layer being compatible with but not excessively soluble in a cleaning solvent;
- and
- iii. a hydrophilic metal substrate,
- b. spacing at least one laser source opposite the printing member;
- c. guiding the output of the at least one laser source to focus on the printing member;
- d. causing relative movement between the at least one laser source and the printing member to effect a scan of the printing member by the laser output;
- and
- e. selectively exposing, in a pattern representing an image, the printing member to the laser output during the course of the scan so as to remove at least the top layer, thereby directly producing on the plate an array of image features.
Dependencies are inferred from the claim text.