Ablation-type lithographic imaging with enhanced debris removal
View Patent ↗Sequentially subjecting an imaged ablation-type printing member having a silicone topmost layer to, first, a cleaning liquid that is not a solvent for silicone, followed by subjecting to a second cleaning liquid that is a silicone solvent, conditions the printing member for subsequent printing with high-solids inks.
1. A method of printing with an ablation-type printing member having a silicone topmost layer, the method comprising the steps of:
(a) selectively exposing the printing member to imaging radiation so as to effect imagewise ablation of the imaging layer and consequent de-anchoring of the topmost layer to thereby create, on the printing member, an image region including ablation debris;
(b) without further exposure to imaging radiation, subjecting the printing member to a first cleaning liquid that is not a solvent for silicone to remove a portion of the ablation debris;
(c) following step (b), subjecting the printing member to a second cleaning liquid that comprises or consists essentially of a solvent for silicone, thereby creating an imagewise lithographic pattern on the printing member;
(d) following the removal step, applying a high-solids ink to the printing member; and
(e) transferring the applied ink from the printing member to a recording medium,
wherein neither first cleaning liquid nor the second cleaning liquid is ink.
2. The method of claim 1 further comprising repeating steps (d) and (e) a plurality of times to complete cleaning of the printing member before commencing printing, whereupon the ink adheres only to imaged portions of the printing member.
3. The method of claim 1 wherein the ink is a 100%-solids ink.
4. The method of claim 3 wherein the ink is a UV-curable ink.
5. The method of claim 4 wherein the ink consists essentially of pigment and acrylic monomers.
6. The method of claim 1 wherein the first cleaning liquid is an aqueous liquid containing no organic solvent.
7. The method of claim 6 wherein the first cleaning liquid is plain tap water.
8. The method of claim 1 wherein the second cleaning liquid consists essentially of an aqueous component and an organic component.
9. The method of claim 8 wherein the aqueous component itself consists essentially of water.
10. The method of claim 8 wherein the aqueous component represents no more than 95 wt % of the second cleaning fluid.
11. The method of claim 8 wherein the aqueous component represents no more than 80 wt % of the second cleaning fluid.
12. The method of claim 8 wherein the organic component comprises an alcohol.
13. The method of claim 12 wherein the alcohol is phenoxyethanol.
14. The method of claim 12 wherein the alcohol is 2-butoxyethanol (butyl cello solve).
15. The method of claim 12 wherein the alcohol is 2-ethoxyethanol.
16. The method of claim 8 wherein the organic component comprises an animal or vegetable oil.
17. The method of claim 8 wherein the organic component comprises a hydrocarbon solvent.
18. The method of claim 8 wherein the second cleaning liquid consists essentially of an animal or vegetable oil.
19. A method of imaging an ablation-type printing member having a silicone topmost layer, the method comprising the steps of:
(a) selectively exposing the printing member to imaging radiation so as to effect imagewise ablation of the imaging layer and consequent de-anchoring of the topmost layer to create, on the printing member, an image region including ablation debris;
(b) without further exposure to imaging radiation, subjecting the printing member to a first cleaning liquid that is not a solvent for silicone to remove a portion of the ablation debris;
and
(c) following step (b), subjecting the printing member to a second cleaning liquid that comprises or consists essentially of a solvent for silicone, thereby creating an imagewise lithographic pattern on the printing member,
wherein neither first cleaning liquid nor the second cleaning liquid is ink.
20. The method of claim 19 further comprising the steps of:
(d) following the removal step, applying a high-solids ink to the printing member;
(e) transferring the applied ink from the printing member to a recording medium; and
(f) repeating steps (d) and (e) a plurality of times.
21. The method of claim 19 wherein the second cleaning liquid comprises a surfactant.
22. The method of claim 19 wherein the second cleaning liquid comprises a defoamer.
23. The method of claim 19 wherein the second cleaning liquid comprises D-limonene.