Abstract: A polymer powder includes a polyamide, wherein a melting point determined in differential scanning calorimetry is 190° C. or higher, a difference between the melting point and a melting onset temperature, which is defined in differential scanning calorimetry as a lowest temperature among temperatures at each of which a first temperature differential value of Heat Flow (W/g) observed between a peak top temperature of an endothermic peak, observed when 10 mg of powder is heated at a rate of 20° C./min from 30° C. in a nitrogen atmosphere, and a temperature point of ?50° C. from the peak top, becomes ?0.2 (W/g.° C.), is less than 30° C., and a D50 particle size is 1 ?m or more and 100 ?m or less.

Abstract: A quality control method for a planographic printing plate having disposed on a substrate a photosensitive layer formed by a resin soluble in an aqueous alkali solution and a compound that absorbs light to generate heat, the quality control method having the steps of: (A) exposing, to an ultraviolet ray, a gray scale for evaluating a positive type planographic printing plate made by exposure to an ultraviolet ray, followed by development with a standard developing solution having a standard formula, and measurement of the sensitivity of the gray scale processed by the standard developing solution; (B) exposing, to an ultraviolet ray, a gray scale for evaluating a positive type planographic printing plate made by exposure to an ultraviolet ray in the same manner as in the step (A), followed by development with a developing solution to be evaluated, and measurement of the sensitivity of the gray scale processed by the developing solution to be evaluated; (C) comparing the sensitivity of the gray scale processed

Abstract: A dry PS plate comprises a substrate having provided thereon in order a primer layer, a light-sensitive layer and a silicone rubber layer wherein the primer layer comprises a film forming polyurethane resin and a diazonium salt polycondensate. The dry PS plate is excellent in the adhesion strength between the substrate and the light-sensitive layer. The adhesion is surely maintained even after imagewise exposure to light and the subsequent development. The dry PS plate shows excellent image reproduction and the resulting dry lithographic plate is excellent in printing durability as well as resistance to scratch.

Abstract: The present invention relates to a presensitized plate for use in making a lithographic plate requiring no dampening water and comprising, on a support, a light-sensitive resin layer and a silicone rubber layer, in this order, wherein the silicone rubber layer is crosslinked by addition reaction of an .fwdarw.SiH group with a --CH.dbd.CH-- group and wherein the light-sensitive resin layer comprises: (1) a monomer or oligomer having at least one photopolymerizable or photo-crosslinkable and olefinically unsaturated double bond, (2) an organic solvent-soluble polyurethane resin having a glass transition temperature of 20.degree. C. or below and being capable of forming a film, and (3) a photopolymerization initiator. According to the present invention, the PS plate has excellent image-forming properties and printing properties.