Lithographic imaging and printing without defects of electrostatic origin
Embodiments of the present invention involve three-layer printing members having a central layer that is non-conductive yet abalatable at commercially realistic fluence levels. In various embodiments, the central layer is polymeric with a dispersion of nonconductive carbon black particles therein at a loading level sufficient to provide at least partial layer ablatability and water compatibility of the resulting ablation debris.
1. A lithographic printing member comprising:
(a) a first layer presenting a hydrophilic or oleophobic lithographic affinity;
(b) a second layer for ablating in response to an imaging pulse, the second layer consisting essentially of a polymeric matrix and, dispersed therein, nonconductive carbon black particles at a loading level sufficient to confer at least partial ablatability with formation of water-compatible imaging debris; and
(c) a third layer presenting an oleophilic lithographic affinity, the second layer being disposed between the first and third layers.
2. The member of claim 1 wherein the water-compatible imaging debris producible from the second layer is removable by contact with an aqueous liquid.
3. The member of claim 1 wherein the loading level is sufficient to confer at least partial ablatability at a fluence of 400 mJ/cm 2 or less.
4. The member of claim 1 wherein the loading level is sufficient to confer at least partial ablatability at a fluence of 300 mJ/cm 2 or less.
5. The member of claim 1 wherein the third layer is a polyester substrate.
6. The member of claim 1 wherein the third layer is polyester and further comprising a metal sheet to which the third layer is attached.
7. The member of claim 1 wherein the third layer is a metal sheet.
8. The member of claim 1 wherein the first layer comprises silicone.
9. The member of claim 1 wherein the first layer comprises polyvinyl alcohol.
10. The member of claim 1 wherein the loading level is at least 25 wt %.
11. The member of claim 1 wherein the loading level is at least 35 wt %.
12. The member of claim 1 wherein the loading level is at least 40 wt %.
13. The member of claim 1 wherein the second layer has a dry coating weight of at least 0.2 g/m 2 .
14. The member of claim 1 wherein the second layer has a dry coating weight of at least 0.8 g/m 2 .