| 摘要 |
A planographic printing plate precursor of the present invention comprises: a support and a positive recording layer arranged on the support. the positive recording layer containing resin and an infrared absorber and being constituted of two or more sub-layers, wherein the solubility of the positive recording layer to an aqueous alkali solution is increased by exposure to infrared laser light, and for the positive recording sub-layer of the two or more positive recording sub-layers that is nearest to the support (the lower layer), the ratio of the dissolution speed to an aqueous alkali solution in the lateral direction to the dissolution speed in the depth direction is less than 1. Such a ratio of the dissolution speeds can be achieved by forming a dispersed phase in the lower layer and/or high-temperature drying when forming the lower layer. According to the invention, there is provided a positive planographic printing plate precursor for infrared laser for direct plate making, which is excellent in scratch resistance and in discrimination of formed images.
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