Ablatable elements for making flexographic printing plates

Abstract

Relief images can be formed from a laser-ablatable element having a laser-ablatable layer that is from about 300 to about 4,000 μm in thickness. The laser-ablatable layer includes a film-forming material that is a laser-laser-ablatable material or the film-forming material has dispersed therein a laser-ablatable material. The laser-ablatable material is a polymeric material that when heated to 300° C. at a rate of 10° C./minute, loses at least 60% of its mass to form at least one predominant low molecular weight product. The laser-ablatable material can also comprise at least 0.01 weight % of a depolymerization catalyst that is a Lewis acid or organometallic based catalyst. The element can be imaged by ablation at an energy of at least 1 J/cm 2 to provide a relief image.

1 . A method of making an element having a relief image, comprising:
 A) providing a laser-ablatable layer in an imagable element, the laser-ablatable layer having a thickness of from about 300 μm to about 4000 μm and comprising a film-forming material,   wherein said film-forming material is a laser-ablatable material or said film-forming material has dispersed therein a laser-ablatable material,   said laser-ablatable material being a polymeric material that when heated to 300° C. at a rate of 10° C./minute, loses at least 60% of its mass to form at least one predominant low molecular weight product, and   B) imagewise directly ablating said laser-ablatable layer with a laser at an energy of at least 1 J/cm 2  to provide a relief image in the element that has a relief depth of at least 100 μm.   
     
     
         2 . The method of  claim 1  wherein said laser-ablatable layer includes an infrared absorbing material and said imagewise directly ablating is carried out using an infrared laser at an energy of from about 20 J/cm 2  to about 1000 J/cm 2 . 
     
     
         3 . The method of  claim 1  wherein said laser-ablatable material is a poly(cyanoacrylate) that forms a cyanoacrylate as the predominant low molecular weight product, or a polycarbonate or polycarbonate block copolymer that forms a cyclic alkylene carbonate as the predominant low molecular weight product. 
     
     
         4 . The method of  claim 1  wherein the laser imaging is at a wavelength of from about 800 to about 1100 nm. 
     
     
         5 . The method of  claim 1  wherein said laser-ablatable layer further comprises a depolymerization catalyst for said laser-ablatable material. 
     
     
         6 . The method of  claim 5  wherein said depolymerization catalyst is an acid or base generator, a Lewis acid, or an organometallic based catalyst in an amount of at least 0.01 weight % based on the dry weight of the laser-ablatable material. 
     
     
         7 . The method of  claim 5  wherein said depolymerization catalyst is zinc-containing organometallic based catalyst. 
     
     
         8 . The method of  claim 1  wherein said film-forming material is said laser-ablatable material and comprises at least 10 weight % of said laser-ablatable layer. 
     
     
         9 . The method of  claim 1  wherein said film-forming material comprises said laser-ablatable material dispersed within said film-forming material. 
     
     
         10 . The method of  claim 1  wherein said film-forming material is a first laser-ablatable material and has dispersed therein a second laser-ablatable material. 
     
     
         11 . The method of  claim 1  comprising multiple layers, at least one of which comprises said laser-ablatable material. 
     
     
         12 . The method of  claim 1  wherein the laser-ablatable layer is disposed on a substrate for the element. 
     
     
         13 . The method of  claim 12  wherein the substrate for the element is a polyester film or a polyester film laminated to a metal support, or a polyester film that is laminated to a compliant or adhesive support. 
     
     
         14 . The method of  claim 1  wherein said laser-ablatable layer comprises a radiation absorbing material in an amount of at least 1 weight %. 
     
     
         15 . The method of  claim 1  wherein said laser-ablatable layer further comprises a depolymerization catalyst that is an acid or base generator, a Lewis acid, or an organometallic based catalyst, and said radiation-absorbing material is a carbon black or infrared radiation absorbing dye. 
     
     
         16 . The method of  claim 1  wherein the laser-ablatable layer further comprises insert particulate materials, inert microspheres, or microvoids, or any combination thereof. 
     
     
         17 . The method of  claim 1  wherein the laser-ablatable layer further comprises inert microspheres or silica particles, or both inert microspheres and silica particles. 
     
     
         18 . The method of  claim 1  wherein the laser-ablatable layer further comprises inert microspheres in an amount of from about 1 weight % to about 40 weight % of the dry laser-ablatable layer. 
     
     
         19 . A method of printing an ink, comprising:
 forming a relief image in a laser-ablatable element comprising a laser-ablatable layer in an imagable element, the laser-ablatable layer having a thickness of from about 300 μm to about 4000 μm and comprising a film-forming material, wherein said film-forming material is a laser-ablatable material or said film-forming material has dispersed therein a laser-ablatable material, said laser-ablatable material being a polymeric material that when heated to 300° C. at a rate of 10° C./minute, loses at least 60% of its mass to form at least one predominant low molecular weight product,
 by imagewise directly ablating said laser-ablatable layer with a laser at an energy of at least 1 J/cm 2  to provide a relief image in the element that has a relief depth of at least 100 μm, 
   inking the relief image in the element, and   transferring the ink from the relief image to a substrate.