Solvent-free flexographic imaging and printing with photoresponsive printing members

Abstract

Flexographic printing members amenable to aqueous (or organic) development do not exhibit the deleterious effects on printing performance characteristic of some conventional alternatives. Embodiments of the invention utilize a photopolymerizable layer comprising, consisting of, or consisting essentially of a photopolymerization initiator and a water-dilutable (but not water-soluble) monomer.

What is claimed is: 
     
         1 . A method of preparing a printing member, the method comprising the steps of:
 providing a printing member comprising (i) an imaged photomask having an imagewise pattern of opaque and non-opaque regions, the opaque regions substantially blocking passage therethrough of actinic radiation, (ii) a support, and (iii) disposed between the photomask and the support and in contact with opposed surfaces thereof, a layer of photopolymer polymerizable by actinic radiation, the photopolymer consisting essentially of an initiator and a water-dilutable but not water-soluble monomer;   exposing the precursor to actinic radiation through the photomask to cause polymerization of the photopolymer; and   developing the printing member with an aqueous medium or an organic solvent to remove only unexposed portions of the photopolymer layer.   
     
     
         2 . The method of  claim 1 , wherein the photopolymer is capable of emulsification in water. 
     
     
         3 . The method of  claim 1 , wherein the water-dilutable but not water-soluble monomer is an aliphatic urethane acrylic oligomer. 
     
     
         4 . The method of  claim 1 , wherein the photopolymer layer also includes a hydrolyzable binder. 
     
     
         5 . The method of  claim 4 , wherein the hydrolyzable binder is a rubber. 
     
     
         6 . The method of  claim 5 , wherein the rubber is butadiene maleic anhydride copolymer. 
     
     
         7 . The method of  claim 1 , wherein the photopolymer layer further comprises a dye. 
     
     
         8 . The method of  claim 1 , wherein the photopolymer layer further comprises an anti-oxidant. 
     
     
         9 . The method of  claim 1 , wherein the printing member is a flexographic printing member. 
     
     
         10 . The method of  claim 1 , wherein the printing member is a letterpress printing member. 
     
     
         11 . A printing member comprising:
 a laser-ablatable layer comprising a material that absorbs laser radiation;   a support; and   disposed between the laser-ablatable layer and the support and in contact with opposed surfaces thereof, a layer of photopolymer polymerizable by actinic radiation, the photopolymer comprising an initiator and a water-dilutable but not water-soluble monomer, wherein the photopolymer is developable by organic and aqueous solvents and combinations thereof.   
     
     
         12 . The printing member of  claim 11 , wherein the laser-ablatable layer is ablatable by IR radiation. 
     
     
         13 . The printing member of  claim 12 , wherein the laser-ablatable layer consists essentially of a polymer and carbon black dispersed therein. 
     
     
         14 . The printing member of  claim 11 , wherein the photopolymer layer also includes a hydrolyzable binder. 
     
     
         15 . The printing member of  claim 14 , wherein the hydrolyzable binder is a rubber. 
     
     
         16 . The printing member of  claim 15 , wherein the rubber is butadiene maleic anhydride copolymer. 
     
     
         17 . The printing member of  claim 16 , wherein the butadiene maleic anhydride copolymer is a butadiene/styrene/maleic anhydride copolymer. 
     
     
         18 . The printing member of  claim 15 , wherein the rubber is polyisoprene maleic anhydride rubber. 
     
     
         19 . The printing member of  claim 11 , wherein the photopolymer layer further comprises a dye. 
     
     
         20 . The printing member of  claim 11 , wherein the photopolymer layer further comprises an anti-oxidant.