Abstract: A light-sensitive composition for use with lithographic printing plates is described which comprises (1) a light-sensitive, organic solvent soluble and substantially water-insoluble diazo resin which is the reaction product of a water-soluble, light-sensitive condensate of an aromatic diazonium compound and an organic condensing agent with a halogenated Lewis acid or a salt thereof, (2) a substantially water-insoluble, film forming organic high-molecular weight compound having an acid value of from 10 to 200, (3) a polynuclear aromatic sulfonic acid or a salt thereof, and (4) a salt-forming organic dye compound.

Abstract: A presensitized lithographic printing plate precursor is described, comprising an aluminum support that has been rendered hydrophilic having provided thereon a light-sensitive layer composed of a light-sensitive composition comprising (1) an organic solvent-soluble and substantially water-insoluble diazo resin, (2) a substantially water-insoluble, film-forming polymeric compound, and at least one of (3a) an organic solvent-soluble polymeric compound having a sulfonic acid group or a sulfonic acid salt group in its side chain and (3b) a substituted or unsubstituted dipicolinic acid or a salt thereof, the total amount of (3a) and (3b) components being about 1 to about 100% by weight, based on the weight of the diazo resin.

Abstract: A light-sensitive printing plate is disclosed. The printing plate is comprised of a support base having a light-sensitive layer positioned thereon and a matting layer comprised of a micropattern of protuberances. The protuberances are present in a regular or randomly mixed manner on the light-sensitive layer and are comprised of a copolymer. The copolymer includes a monomer (unit a) with a sulfonic acid group, a monomer (unit b) selected from the group consisting of alkyl acrylates having 1 to 10 carbon atoms in the alkyl moiety thereof and alkyl methacrylates having 4 to 10 carbon atoms in the alkyl moiety thereof and a monomer (unit c) copolymerizable with monomer (unit a) and monomer (unit b), monomer (unit c) as a copolymer having a glass transition point of 60.degree. C. or above. The matting layer does not cause staining of a film original when superposed thereon and is resistant to rubbing or pressure and provides a surface which can be vacuum contacted with a film in a short period of time.

Abstract: A light-sensitive composition particularly suitable for making light-sensitive lithographic printing plates is described composed of a mixture of a sensitizer and a photo-crosslinkable polymer, or a mixture of a sensitizer, a compound including a light-sensitive azido group and a polymer reactive with a decomposate of azido groups to be formed upon exposure to light, and a sensitizer represented by the formula (I) ##STR1## wherein A represents a non-metallic atomic group necessary for forming a heterocyclic ring containing nitrogen; R.sub.1 represents an alkyl group or a substituted alkyl group; R.sub.2 represents hydrogen, an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group; and Y and Z each represents an oxygen atom or a sulfur atom.