Exposure processing method of a planographic printing plate and apparatus for executing the same method

Abstract

The present invention provides an exposure processing method of a planographic printing plate including: providing an image recording layer containing a polymerizable compound which is solid at room temperature, a polymerization initiator, and a light-to-heat converting agent, and a microcapsule encapsulating at least one of the monomer and the polymerization initiator, such that the light energy quantity absorbed in the lower part of the image recording layer is more than the light energy quantity absorbed in the upper and middle parts of the image recording layer; exposing the image recording layer; and thereafter post-heating the image recording layer at a temperature in a range equal to or above the melting point of the monomer and below the glass transition point of the wall of the microcapsule. As a result, the printing resistance of a planographic printing plate is enhanced.

1 . An exposure processing apparatus comprising: 
 an exposure processing unit for exposing by emitting light onto an image recording layer provided on a support of a planographic printing plate; and    a post-heating unit for heating the image recording layer of the exposed planographic printing plate,    wherein the image recording layer includes upper, middle and lower parts, these three parts of the image recording layer each having uniform thickness in the depth direction, and the image recording layer has a light absorption coefficient distribution in the depth direction adapted so that the light energy quantity absorbed in the lower part of the image recording layer may be more than the light energy quantity absorbed in the upper part and middle part of the image recording layer.    
   
   
       2 . The exposure processing apparatus of  claim 1 , wherein the image recording layer contains a polymerizable compound which is solid at room temperature, a compound generating a polymerization initiator, and a compound absorbing image recording light, and the post-heating unit heats the polymerizable compound at a temperature equal to or above its melting point.  
   
   
       3 . The exposure processing apparatus of  claim 2 , wherein the polymerizable compound which is solid at room temperature is encapsulated in a microcapsule having a wall of higher glass transition point than the melting temperature of the polymerizable compound, and the heating temperature in the post-heating unit is set below the glass transition point.