Apparatus and method for thermally developing flexographic printing elements

Abstract

An improved apparatus for thermally developing a flexographic printing element to reveal a relief image on the surface and a method of using the apparatus to expose and develop a flexographic printing element. The apparatus typically comprises means for softening or melting non-crosslinked photopolymer on the imaged and exposed surface of the flexographic printing element; at least one roll that is contactable with the imaged surface of the flexographic printing element and capable of moving over at least a portion of the imaged surface of the flexographic printing element to remove the softened or melted non-crosslinked photopolymer on the imaged and exposed surface of the flexographic printing element; and means for maintaining contact between the at least one roll and the imaged and exposed surface of the flexographic printing element. The means for softening or melting non-crosslinked photopolymer on the imaged and exposed surface of the flexographic printing element comprise a heater positioned adjacent to the imaged surface of the flexographic printing element and/or heating the at least one roll that contactable with the imaged surface of the flexographic printing element. The apparatus may also contain an exposure device to crosslink and cure the imaged surface of the flexographic printing element prior to thermal development.

1 - 44 . (canceled)  
   
   
       45 . An apparatus for exposing and developing a flexographic printing element, the apparatus comprising: 
 means for supporting, and preferably rotating, a printing element;    means for exposing a surface of the printing element to actinic radiation to selectively crosslink and cure a portion of the surface of the printing element; and    means for thermally developing the exposed surface of the printing element comprising:    a) means for softening or melting non-crosslinked photopolymer on the exposed surface of the printing element;    b) at least one element that is contactable with the surface of the printing element and capable of moving across at least a portion of the length of the printing element to remove the softened or melted non-crosslinked photopolymer; and    c) means for maintaining contact between the at least one contactable element and the printing element.    
   
   
       46 . The apparatus according to  claim 45 , further comprising means for detacking and post-curing the printing element, wherein said means for detacking and post-curing the printing element are capable of moving over at least a portion of the printing element.  
   
   
       47 . The apparatus according to  claim 45 , wherein the means for exposing the surface of the printing element to actinic radiation comprise one or more ultraviolet lights.  
   
   
       48 . The apparatus according to  claim 45 , wherein the means for exposing the surface of the printing element and the at least one contactable element are mounted on a carriage, and said carriage is capable of traversing the length of the printing element as the printing element rotates.  
   
   
       49 . The apparatus according to  claim 45 , wherein a blotting material is positionable on at least a portion of the at least one contactable element, and the blotting material is capable of removing non-crosslinked polymer on the surface of the printing element when the at least one contactable element contacts and moves across at least the portion of the printing element.  
   
   
       50 . The apparatus according to  claim 49 , wherein the blotting material is looped under and around at least the portion of the at least one contactable element that contacts the surface of the printing element.  
   
   
       51 . The apparatus according to  claim 50 , comprising means for supplying the blotting material to the at least one contactable element.  
   
   
       52 . The apparatus according to  claim 50 , comprising a rewind device to carry away the blotting material that contains the removed non-crosslinked polymer.  
   
   
       53 . The apparatus according to  claim 45 , comprising a doctor blade positionable adjacent to the at least one contactable element that is capable of wiping removed non-crosslinked polymer from the surface of the at least one contactable element when the at least one contactable element contacts and moves across at least the portion of the printing element.  
   
   
       54 . The apparatus according to  claim 45 , wherein the means for maintaining contact between the at least one contactable element and the printing element comprises an air cylinder or a hydraulic cylinder that is capable of forcing the at least one contactable element against the printing element.  
   
   
       55 . The apparatus according to  claim 45 , wherein the means for softening or melting non-crosslinked photopolymer on the exposed surface of the printing element comprises heating the at least one contactable element and/or positioning a heater adjacent to the exposed surface of the printing element.  
   
   
       56 . A method of exposing and developing a flexographic printing element, the method comprising the steps of: 
 a) supporting and rotating the printing element on a support;    b) exposing a surface of the printing element to one or more sources of actinic radiation to crosslink and cure selected portions of the surface of the printing element;    c) melting or softening non-crosslinked polymer on the exposed surface of the printing element;    d) causing contact between the surface of the printing element and at least one contactable element; and    e) moving the at least one contactable element against the printing element as the printing element rotates in a first direction and simultaneously moving the at least one contactable element across at least a portion of the length of the printing element to remove non-crosslinked photopolymer from the exposed surface of the printing element.    
   
   
       57 . The method according to  claim 56 , comprising a step of detacking and post-curing the printing element.  
   
   
       58 . The method according to  claim 56 , wherein the one or more sources of actinic radiation traverse the length of the printing element.  
   
   
       59 . The method according to  claim 56  wherein the at least one contactable element moves back and forth across the length of the printing element multiple times.  
   
   
       60 . The method according to  claim 59 , wherein the at least one contactable element moves across the length of the printing element in a spiral or stepwise manner.  
   
   
       61 . The method according to  claim 56 , wherein causing contact between the printing element and the at least one contactable element comprises using an air cylinder or a hydraulic cylinder to maintain contact between the at least one contactable element and the surface of the printing element.  
   
   
       62 . The method according to  claim 56 , wherein at least the portion of the at least one contactable element that is in contact with the surface of the printing element is covered with a blotting material to remove non-crosslinked polymer from the surface of the printing element.  
   
   
       63 . The method according to  claim 62 , wherein the blotting material is looped under and around at the least the portion of the at least one contactable element that is in contact with the surface of the printing element.  
   
   
       64 . The method according to  claim 62 , wherein the blotting material is selected from the group consisting of paper, screen mesh, and absorbent fabric.  
   
   
       65 . The method according to  claim 56 , wherein the non-crosslinked polymer remaining on the at least one contactable element after removal from the surface of the printing element is removed from the at least one contactable element by wiping the at least one contactable element with a doctor blade positioned adjacent to the at least one contactable element.  
   
   
       66 . The method according to  claim 56 , wherein the non-crosslinked photopolymer on the exposed surface of the printing element is melted or softened by heating the at least one contactable element that contacts the exposed surface of the printing element and/or positioning a heater adjacent to the exposed surface of the printing element.  
   
   
       67 . The method according to  claim 56 , wherein the printing element is a cylindrical printing element or a substantially planar printing plate wrapped around a cylindrical carrier sleeve.  
   
   
       68 . An apparatus for exposing and developing a flexographic printing element, comprising: 
 a) means for supporting, and preferably rotating the printing element; and    b) at least one reciprocating carriage capable of traversing the length of the printing element wherein the at least one reciprocating carriage has mounted thereon: 
 i) means for exposing a surface of the printing element to actinic radiation to selectively crosslink and cure the surface of the printing element; and  
 ii) at least one element that is contactable with the surface of the printing element and capable of removing non-crosslinked photopolymer on the exposed surface of the printing element.  
   
   
   
       69 . The apparatus according to  claim 68 , comprising means for softening or melting the non-crosslinked photopolymer so that it is removable by the at least one contactable element.  
   
   
       70 . The apparatus according to  claim 68 , comprising means for maintaining contact between the at least one contactable element and the printing element.  
   
   
       71 . The apparatus according to  claim 68 , further comprising means for detacking and post-curing the printing element, wherein the means for detacking and post-curing are mounted on the at least one reciprocating carriage.  
   
   
       72 . The apparatus according to  claim 68 , wherein a blotting material is positionable on at least a portion of the at least one contactable element that is capable of removing non-crosslinked photopolymer on the surface of the printing element when the at least one contactable element contacts and moves across at least the portion of the printing element.  
   
   
       73 . The apparatus according to  claim 68 , comprising a doctor blade positionable adjacent to the at least one contactable element that is capable of wiping removed non-crosslinked polymer from the surface of the at least one contactable element when the at least one contactable element contacts and moves across at least the portion of the printing element.  
   
   
       74 . The apparatus according to  claim 69 , wherein the means for softening or melting non-crosslinked photopolymer on the exposed surface of the flexographic printing element comprises heating the at least one contactable element and/or positioning a heater adjacent to the exposed surface of the flexographic printing element.