Heat-sensitive lithographic printing plate and image forming method

摘要

A negative-working CTP plate which is superior in resolution and printing resistance of the image area of a press plate is provided, which is obtained by forming a latent image on a heat-sensitive layer in a heat-sensitive lithographic printing plate comprising a substrate having a hydrophilic surface and a heat-sensitive layer made of an alkali-soluble polymer formed on the surface of the substrate, using heat generated upon irradiation with laser light, and developing the heat-sensitive layer using an alkaline developing solution. In the heat-sensitive lithographic printing plate comprising a substrate having a hydrophilic surface, and a heat-sensitive layer made of an alkali-soluble polymer formed on the surface of the substrate, an advancing contact angle (θ) of the surface of the heat-sensitive layer with water at 25 DEG C is within a range from 70 DEG to 110 DEG , a receding contact angle (θ) of the surface of the heat-sensitive layer with water at 25 DEG C after heating at 150 DEG C for 3 minutes is larger than a receding contact angle (θ) of the surface of the heat-sensitive layer with water at 25 DEG C before heating, and a difference in receding contact angle before and after heating, (θ -θ), is larger than 1 DEG and is smaller than 40 DEG .