Abstract: A heat-sensitive lithographic printing plate precursor comprising a support having thereon two image-forming layers each containing a polymer insoluble in water and soluble in an aqueous alkaline solution, wherein an upper layer of the image-forming layers contains a copolymer including a monomer unit represented by formula (A) defined in the specification.

Abstract: The invention provides a photosensitive composition including (A) a vinyl polymer containing a copolymerization component having a carboxyl group, having a content of the carboxyl group in a molecule of 2.0 meq/g or higher and having a solubility parameter less than 21.3 MPa1/2, (B) a polymer compound including a phenolic hydroxyl group, and (C) an IR absorber.

Abstract: An infrared-sensitive photosensitive composition comprising: (A) a resin; (B) a novolak resin; and (C) a light-to-heat converting substance, wherein the resin (A) has, as copolymer components, at least: (1) a (meth)acrylic acid or a monomer represented by formula (I) as defined herein; and (2) at least one compound selected from the group consisting of a (meth)acrylic ester, a (meth)acrylamide derivative, and a styrene derivative.

Abstract: The present invention relates to a presensitized plate useful for making a lithographic printing plate comprising an intermediate layer and a photopolymerizable photosensitive layer on an aluminum substrate in this order, wherein the roughness of a surface of said aluminum substrate (Ra) is in the range of 0.2 to 0.55 &mgr;m and the intermediate layer comprises a polymer compound comprising at least one monomer unit having a sulfonic acid group and a method for making a lithographic printing plate by imagewise exposing the presensitized plate described above and developing the imagewise exposed presensitized plate with a developer comprising an inorganic alkali salt and a nonionic surfactant comprising a polyoxyalkylene ether group. The presensitized plate or the method of the present invention provides a lithographic printing plate showing good contrast between an image area and non-image area, no background contamination during printing, good stability with time and good printing durability.

Abstract: A heat-sensitive lithographic printing plate precursor comprising a support having thereon two image-forming layers each containing a polymer insoluble in water and soluble in an aqueous alkaline solution, wherein an upper layer of the image-forming layers contains a copolymer including a monomer unit represented by formula (A) defined in the specification.

Abstract: A plate-making method of a lithographic printing plate is disclosed, which comprises the steps of exposure of a photosensitive lithographic printing plate having the acid value of a photosensitive layer of 1.0 meq/g or less with a laser beam, and then development with a developing solution having a pH value of 13.0 or less at a developing speed in an unexposed domain of 0.05 &mgr;m/s or more and at an osmotic speed of a developing solution in an exposed domain of 0.1 &mgr;m/s or less.

Abstract: A plate-making method of a lithographic printing plate is disclosed, which comprises the steps of exposure of a photo-sensitive lithographic printing plate having the acid value of a photosensitive layer of 1.0 meq/g or less with a laser beam, and then development with a developing solution having a pH value of 13.0 or less at a developing speed in an unexposed domain of 0.05 &mgr;m/s or more and at an osmotic speed of a developing solution in an exposed domain of 0.1 &mgr;m/s or less.

Abstract: The invention provides a photosensitive composition including (A) a vinyl polymer containing a copolymerization component having a carboxyl group, having a content of the carboxyl group in a molecule of 2.0 meq/g or higher and having a solubility parameter less than 21.3 MPa1/2, (B) a polymer compound including a phenolic hydroxyl group, and (C) an IR absorber.

Abstract: An infrared-sensitive photosensitive composition comprising:

Abstract: The present invention relates to a presensitized plate useful for making a lithographic printing plate comprising an intermediate layer and a photopolymerizable photosensitive layer on an aluminum substrate in this order, wherein the roughness of a surface of said aluminum substrate (Ra) is in the range of 0.2 to 0.55 &mgr;m and the intermediate layer comprises a polymer compound comprising at least one monomer unit having a sulfonic acid group and a method for making a lithographic printing plate by imagewise exposing the presensitized plate described above and developing the imagewise exposed presensitized plate with a developer comprising an inorganic alkali salt and a nonionic surfactant comprising a polyoxyalkylene ether group. The presensitized plate or the method of the present invention provides a lithographic printing plate showing good contrast between an image area and non-image area, no background contamination during printing, good stability with time and good printing durability.

Abstract: A plate-making method of a lithographic printing plate is disclosed, which comprises the steps of exposure of a photo-sensitive lithographic printing plate having the acid value of a photosensitive layer of 1.0 meq/g or less with a laser beam, and then development with a developing solution having a pH value of 13.0 or less at a developing speed in an unexposed domain of 0.05 &mgr;m/s or more and at an osmotic speed of a developing solution in an exposed domain of 0.1 &mgr;m/s or less.

Abstract: A support is laminated with a light-sensitive layer and a silicone rubber layer in this order, wherein the light sensitive layer comprises (a) a resol resin, (b) a novolak resin, (c) an infrared absorber, and (d) a compound which generates an acid with heat, thereby providing a light-sensitive lithographic printing plate requiring no fountain solution for direct print-making, which can directly record digital date of computers, etc. with solid lasers or semiconductor lasers having light emitting regions from near infrared to infrared.

Abstract: A positive-working light-sensitive composition comprises a diazonium salt represented by the following general formula (I) and an alkali-soluble polymer: ##STR1## wherein R.sup.1 represents a substituted or unsubstituted alkyl group having 3 to 18 carbon atoms; R.sup.2 represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted phenoxy group or a halogen atom; A represents an organic group; X.sup.-- represents a counterion or an anion; n is an integer ranging from 1 to 4 and m is an integer ranging from 1 to 3, provided that the sum of n and m is equal to 4. The positive-working light-sensitive composition has high sensitivity and can ensure the formation of clear images.

Abstract: A presensitized plate for use in making a lithographic printing plate requiring no dampening water comprises a substrate provided thereon with in order: (1) a photopolymerizable light-sensitive layer which comprises a monomer or an oligomer having at least one photopolymerizable olefinically unsaturated double bond, an organic solvent-soluble polyurethane resin or polyamide resin which is solid at room temperature and has film-forming ability and a photopolymerization initiator; (2) a crosslinked silicone rubber layer; and (3) a transparent cover coat layer, wherein the photopolymerization initiator comprises dialkylaminoarylcarbonyl compounds and at least one member selected from the group consisting of xanthones, thioxanthones, acrydones, benzophenones which do not carry a dialkylamino group, benzanthrones and anthraquinones and the transparent cover coat layer is formed from a biaxially oriented polypropylene film having a thickness ranging from 6 to 22 .mu.

Abstract: A photopolymerizable composition comprises an addition polymerizable compound having at least one ethylenically unsaturated double bond and a photopolymerization initiator, wherein it comprises a compound represented by the following general formula (I) as the photopolymerization initiator: ##STR1## (wherein R.sub.1 and R.sub.2 may be the same or different and each independently represents a substituted or unsubstituted alkyl, aryl or alkenyl group or R.sub.1 and R.sub.2 may form a non-metallic ring together with the sulfur atoms to which they are bonded; n is 0, 1 or 2; G.sub.1 and G.sub.2 may be the same or different and each represents a hydrogen atom, a cyano group or a substituted or unsubstituted alkoxycarbonyl, aryloxycarbonyl, acyl, arylcarbonyl, alkylthio, arylthio, alkylsulfonyl, arylsulfonyl or fluoroalkylsulfonyl group, provided that G.sub.1 and G.sub.2 do not simultaneously represent hydrogen atoms or G.sub.1 and G.sub.