Method for printing a pattern on a substrate

Abstract

The invention provides a method for printing a pattern of ink on a substrate, such as corrugated paperboard, with a relief printing form made from a photosensitive element. The method includes forming an in-situ mask for the photosensitive element, exposing the element to actinic radiation through the in-situ mask in an environment having an inert gas and a concentration of oxygen between 190,000 and 100 ppm, and treating the exposed element to form the relief printing form having a pattern of printing areas. Printing is accomplished by securing the relief printing form to a print press, applying the ink to the printing areas on the printing form, and contacting the ink from the printing areas to the substrate to transfer the pattern of ink onto the substrate.

1 . A method for printing a pattern of ink on a substrate comprising.
 a) providing a relief printing form from a photosensitive element comprising a photopolymerizable layer containing a binder, an ethylenically unsaturated compound and a photoinitiator, with steps comprising:
 i) forming an in-situ mask adjacent the photopolymerizable layer; 
 ii) exposing the photopolymerizable layer to actinic radiation through the mask in an environment having an inert gas and a concentration of oxygen between 190,000 ppm and 100 ppm; and 
 iii) treating the element from step ii) to form the relief printing form having a pattern of printing areas; 
   b) securing the printing form onto or adjacent a print cylinder;   c) applying the ink to the printing areas of the printing form; and   d) contacting the ink from the printing areas to the substrate, thereby transferring the pattern of ink onto the substrate.   
     
     
         2 . A method for preparing a relief printing form from a photosensitive element, comprising the steps of:
 a) forming an in-situ mask adjacent to a photopolymerizable layer in the photosensitive element, wherein the photopolymerizable layer comprises a binder, an ethylenically unsaturated compound and a photoinitiator;   b) exposing the photosensitive element to actinic radiation through the in-situ mask in an environment having a concentration of oxygen less than atmospheric but greater than an environment that is completely free of oxygen or greater than an environment composed completely of an inert gas; and   c) treating the photosensitive element from step b) to form the relief printing form.   
     
     
         3 . The method of  claim 2  wherein the treating step c) is selected from the group consisting of:
 i) processing the element with at least one washout solution selected from the group consisting of solvent solution, aqueous solution, semi-aqueous solution, and water; and 
 ii) heating the element to a temperature sufficient to cause areas to melt, flow, or soften. 
 
     
     
         4 . The method of  claim 2  wherein the forming the in-situ mask step a) is selected from the group consisting of:
 i) imagewise exposing a laser-radiation sensitive layer on or adjacent the photopolymerizable layer to infrared laser radiation to form the in-situ mask above the photopolymerizable layer; and 
 i) imagewise applying an actinic radiation opaque material on or above the composition layer to form the in-situ mask. 
 
     
     
         5 . The method of  claim 2  wherein the substrate is corrugated paperboard.