ABLATION-TYPE LITHOGRAPHIC IMAGING WITH SILICONE ACRYLATE LAYERS
In ablation-type printing plates involving silicone acrylate top layers, curing at high oxygen levels not only substantially reduces or eliminates toning, but does not adversely affect plate durability or printing performance.
1 . A method of making an ablation-type printing member, the method comprising the steps of:
(a) providing a precursor structure having an oleophilic surface;
(b) coating a silicone acrylate over the precursor; and
(c) following step (b), curing the silicone acrylate by electron-beam exposure at an ambient oxygen level of at least 100 ppm.
2 . The method of claim 1 wherein the ambient oxygen level is at least 200 ppm.
3 . The method of claim 1 wherein the ambient oxygen level is at least 300 ppm.
4 . The method of claim 1 wherein the ambient oxygen level is at least 1000 ppm.
5 . The method of claim 1 wherein the electron-beam exposure delivers a dose of at more than 2 MRad.
6 . The method of claim 1 wherein the electron-beam exposure delivers a dose of at least 7 MRad.
7 . The method of claim 1 wherein the electron-beam exposure delivers a dose of at least 14 MRad.
8 . The method of claim 1 wherein the precursor comprises an ablation-resistant, oleophilic substrate and an ablatable imaging layer thereover.
9 . The method of claim 1 wherein the silicone acrylate is an acrylate-modified polydimethylsiloxane polymer.
10 . An ablation-type printing member comprising:
(a) an ablation-resistant oleophilic layer;
(b) above the oleophilic layer, an ablatable imaging layer; and
(c) above the imaging layer, a silicone acrylate layer that has been cured by electron-beam exposure at an ambient oxygen level of at least 100 ppm.
11 . The printing member of claim 10 wherein the silicone acrylate is an acrylate-modified polydimethylsiloxane polymer.