| 摘要 |
PURPOSE:To enable characters and images to be easily printed with a high resolving power, by a method wherein, a film or sheet of an olefin high-molecular compound containing a polyalkylene halide is provided with sulfonic group on the surface thereof, and in an infrared absorption spectrum on the surface of the film or the sheet the strong absorbance of the band with a wave number of about 1200 and the absorbance of the band with a wave number of nearly 1050, which is attributed to the sulfonic group, are defined in a specific ratio. CONSTITUTION:A plate material is composed of a film or sheet which is made of a high- molecular compound containing a polyalkylene halide and provided with sulfonic group on the surface thereof by sulfonation. In the infrared absorption spectrum on the surface of the film or sheet, the strong absorbance of the band with a wave number of about 1200 and the absorbance of the band with a wave number of nearly 1050, which is attributed to sulfonic group, are in a ratio of 0.6. With the requirement of sulfonation that an oxidizing- type sulfonating agent such as sulfonic anhydride is used in the reaction, the plate material constructed as to have the strong absorbance of the band with a wave number of about 1200 can be obtained. This band is produced by a sulfonic group adjacent to a polyene construction having three conjugated double bonds. Good photosensitivity and thermosensible properties are obtained when the amount of these sulfonic acid groups is 0.6 and more in a light absorbance ratio as compared with the amount of a generally used sulfonic acid groups being attributed to the wave number of 1050.
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