Claims
- 1. A lithographic plate whose affinity for ink may be altered by ablation of one or more layers, said plate being a layered structure including a metal substrate, a current-limiting layer laminated to the metal substrate, a conductive layer disposed on the current-limiting layer, and an ink-adhesive polymeric coating overlying the conductive layer.
- 2. The plate of claim 1 wherein the metal substrate is aluminum or an alloy of aluminum.
- 3. The plate of claim 1 wherein the metal substrate is steel.
- 4. The plate of claim 1 wherein the metal substrate is 0.004 to 0.02 inch thick.
- 5. The plate of claim 2 wherein the first surface of the metal substrate is anodized.
- 6. The plate of claim 1 wherein the first surface of the metal substrate is plated with at least one additional metal.
- 7. The plate of claim 1 wherein the current-limiting layer is substantially non-conductive.
- 8. The plate of claim 1 wherein the current-limiting layer has a volume resistivity between 0.5 and 1000 ohm-cm.
- 9. The plate of claim 1 wherein the current-limiting layer is a material selected from the group consisting of thermoset systems polyurethanes, aziridine cross-linked systems, epoxy-based systems, polyimide systems, polyamide-imide systems, polyamide systems, plastisols, organisols, extrusion coatings, oleophilic silicones and oleophilic fluoropolymers.
- 10. The plate of claim 5 wherein the current-limiting layer is a plastisol or an organisol which contains a component having an affinity for metal.
- 11. The plate of claim 1 wherein the thickness of the current-limiting layer ranges between 0.0001 and 0.002 inch.
- 12. The plate of claim 1 wherein the ink-adhesive coating is silicone or a fluoropolymer.
- 13. The plate of claim 1 wherein the ink-adhesive coating contains a dispersion of particles consisting essentially of at least one conditionally conductive compound.
- 14. The plate of claim 1 wherein the conductive layer is selected from the group consisting of aluminum, zinc, and copper.
- 15. The plate of claim 14 wherein the conductive layer is 200 to 700 angstroms thick.
- 16. The plate of claim 1 further comprising a primer coat applied to the first surface of the metal substrate.
- 17. The plate of claim 1 further comprising a primer coat applied to the current-limiting layer.
- 18. A lithographic plate whose affinity for ink may be altered by ablation of one or more layers, said plate including an ink-adhesive surface layer, a conductive layer thereunder, and a heat-resistant, current-limiting, ink-receptive layer underlying the conductive layer and laminated to a metal substrate.
- 19. The plate of claim 18 wherein the metal substrate is aluminum or an alloy of aluminum.
- 20. The plate of claim 18 wherein the metal substrate is steel.
- 21. The plate of claim 18 Wherein the metal substrate is 0.004 to 0.02 inch thick.
- 22. The plate of claim 18 wherein the ink-adhesive coating is silicone or a fluoropolymer.
- 23. The plate of claim 18 wherein the ink-adhesive coating contains a dispersion of particles consisting essentially of at least one semiconductor whose conductivity is enhanced by the presence of an electric field.
- 24. The plate of claim 18 wherein the conductive layer is selected from the group consisting of aluminum, zinc, and copper.
- 25. The plate of claim 24 wherein the conductive layer is 200 to 700 angstroms thick.
- 26. The plate of claim 18 wherein the current-limiting layer is substantially non-conductive.
- 27. The plate of claim 18 wherein the current-limiting layer is polyester.
- 28. The plate of claim 18 wherein the current-limiting layer has a volume resistivity between 0.5 and 1000 ohm-cm.
- 29. The plate of claim 28 wherein the current-limiting layer is conductive polycarbonate.
- 30. The plate of claim 18 wherein the thickness of the current-limiting layer ranges between 0.0005 and 0.01 inch.
- 31. The plate of claim 18 further comprising a primer coat applied to the current-limiting layer.
- 32. A lithographic plate whose affinity for ink may be altered by ablation of one or more layers, said plate including an ink-adhesive layer surface layer, a conductive layer thereunder, a metal substrate and a current limiting adhesive, the conductive layer being laminated to the metal substrate by means of the current limiting adhesive being applied to a sufficient thickness to limit a flow of electric current to the metal substrate.
- 33. The plate of claim 32 wherein the laminating adhesive is oleophilic and present in sufficient quantity to insulate the metal substrate from the effects of high-energy discharges directed at the surface layer.
- 34. The plate of claim 32 wherein the laminating adhesive is selected from the group consisting of epoxies, hot-melt adhesives, polyurethanes and silicone compounds.
- 35. The plate of claim 34 wherein the laminating adhesive is a polyurethane compound containing polyester groups.
- 36. The plate of claim 32 further comprising a barrier sheet disposed on the ink-adhesive surface layer.
- 37. The plate of claim 36 wherein the barrier sheet is a material selected from the group consisting of polyolefins and polyesters.
- 38. The plate of claim 32 further comprising a heat-resistant, current-limiting, ink-receptive layer disposed between the laminating adhesive and the conductive layer.
- 39. The plate of claim 38 wherein the ink-receptive layer has a volume resistivity between 0.5 and 1000 ohm-cm.
RELATED APPLICATION
This is a continuation-in-part of Ser. No. 07/661,526, filed Feb. 25, 1991, which is a continuation-in-part of Ser. No. 07/442,317, filed Nov. 28, 1989, now U.S. Pat. No. 5,109,771, which is itself a continuation-in-part of Ser. No. 07/234,475, filed Aug. 19, 1988, now U.S. Pat. No. 4,911,075.
US Referenced Citations (27)
Continuation in Parts (3)
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Number |
Date |
Country |
Parent |
661526 |
Feb 1991 |
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Parent |
442317 |
Nov 1989 |
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Parent |
234475 |
Aug 1988 |
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