Ablation-type lithographic imaging with silicone acrylate layers

Abstract

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.