Lithographic printing plate precursor

#The present invention relates to a lithographic printing plate precursor, more specifically a lithographic printing plate precursor capable of plate-making by scanning exposure based on digital signals and developable with water, or loadable on a printing machine without development and printable.

#A lithographic printing plate generally comprises a lipophilic image area which receives an ink in a printing process and a hydrophilic non-image area which receives fountain solution. As such a lithographic printing plate precursor, a PS plate comprising a hydrophilic support having provided thereon a lipophilic photosensitive resin layer (an image-recording layer) has so far been widely used. A plate-making method of a lithographic printing plate precursor generally comprises the steps of performing mask exposure through a lith film and then dissolving and removing a non-image area with a developing solution to thereby obtain a desired printing plate.

#Digitized techniques of electronically processing, accumulating and outputting image data using a computer have prevailed in recent years, and various image output systems corresponding to these digitized techniques have been put to practical use. With such a tendency, a computer-to-plate technique of directly making a printing plate without using a lith film by scanning exposing digitized image data with highly directional active radiant rays such as laser beams is earnestly desired, and it has become an important technical problem to obtain a printing plate precursor adaptable to this purpose.

#The present invention is described in detail below with reference to the specific examples, but it should not be construed as the present invention is limited thereto.

#Synthesis of Latex Solution (1)

#Eight (8) grams of the following monomer (1), 1 g of divinylbenzene, and 0.45 g of sodium dodecylsulfate were put in a three necked flask having a capacity of 1,000 ml, the content of the flask was dissolved with 28 g of distilled water and stirred under nitrogen flow with maintaining the temperature at 65° C. for 30 minutes. A solution obtained by dissolving 18.6 mg of 2,2′-azobis(2-amidinopropane) dihydrochloride in 2 g of distilled water was added to the above solution and stirring was continued at the same temperature for 6 hours. After termination of the reaction, the reaction mixture was filtrated through a glass filter, thereby latex solution (1) was obtained. The concentration of the solid contents of the thus-obtained latex solution (1) was 20 wt % and the average particle size of the latex was 87 nm.