Abstract: The present invention relates to a light-sensitive composition comprising (a) a photo-crosslinkable polymer having a maleimido group at a side chain and (b) a sensitizer such as the following compounds: ##STR1## The present invention provides a light-sensitive composition having very high sensitivity; providing excellent images during only a short exposure time; and being sensitive to light of long wave length.

Abstract: A light-sensitive composition comprises (A) a polymer comprising structural units represented by the following general formula (I): ##STR1## (wherein R.sup.1 represents a hydrogen atom or a methyl group; R.sup.2 represents a hydrogen atom, an alkyl group or an aryl group; and Z represents a bivalent connecting group having at least 3 non-metallic atoms in the main chain); (B) a monomer or an oligomer having at least two polymerizable ethylenically unsaturatred double bonds; and (C) a photopolymerization initiator. The light-sensitive composition has high sensitivity and is excellent in stability of sensitivities such as storage stability, temperature dependency and latent image sensitization.

Abstract: Disclosed is a novel diazo resin which has at least one repeating unit represented by the following general formula (I): ##STR1## wherein R.sup.2 represents a hydrogen atom, an alkyl group or an alkoxy group, a hydroxyl group, a carboxy ester group or a carboxyl group: R.sup.1 represents a carboxyl group or a group having at least one carboxyl group; R.sup.3 and R.sup.4 each represents a hydrogen atom or an alkyl group or an alkoxy group; X.sup.31 represents an anion; and Y represents --NH--, --O-- or --S--. The diazo resin is useful for a presensitized plate for use in making a lithographic printing plate when it is incorporated into a light-sensitive layer or an underlayer on a substrate. According to the present invention, a presensitized plate using the diazo resin has excellent properties such as high sensitivity, good adhesion between the substrate and the light-sensitive layer and can thus provide a lithographic printing plate having a high printing durability and free of background contamination.

Abstract: A light-sensitive composition which comprises, (a) an ethylenically unsaturated addition polymerizable compound, (b) an alkaline water-soluble or swellable, and film-forming polymer, (c) a photopolymerization initiator, (d) a negative working diazo resin, and (e) at least one compound selected from the group consisting of a higher fatty acid and a higher fatty acid amide which are solid at ordinary temperatures.The light-sensitive composition is hardly influenced by oxygen and is suitable for a presensitized plate from which a printing plate is to be prepared.

Abstract: A light-sensitive composition comprises a photo-crosslinkable polymer having a photo-dimerizable unsaturated bond and a sensitizer represented by the following general formula (I): ##STR1## wherein R.sub.1 and R.sub.2 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group or a substituted or unsubstituted allyl group, provided that R.sub.1 and R.sub.2 may form a ring together with the carbon atoms to which they are attached; n represents 0, 1 or 2; and G.sub.1 and G.sub.2 each independently represents a hydrogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted aryloxycarbonyl group, a substituted or unsubstituted acyl group, a substituted or unsubstituted arylcarbonyl group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group or a fluoroalkylsulfonyl group, provided that G.sub.1 and G.sub.

Abstract: A presensitized plate for use in making a lithographic printing plate which comprises an aluminum substrate provided thereon with a light-sensitive layer comprising a polymer having at least two photodimerizable unsaturated double bonds in the molecule, wherein the light-sensitive layer further comprises a compound having at least one photodimerizable unsaturated double bond and at least one phosphinyl group in each molecule as well as a molecular weight of not more than 2,000. The presensitized plate shows excellent sensitivity and makes it possible to provide a lithographic printing plate showing high printing durability.

Abstract: The present invention relates to a photosensitive composition suitable for the use in the preparation of a photosensitive lithographic plate. The photosensitive composition comprises (1) a polymer having a maleimido group in its side chain and being capable of being photocrosslinked, such as a copolymer of methyl methacrylate/N-[2-(methacryloyloxy)-ethyl]-2,3-dimethylmaleimide/methacryl ic acid=15/65/20 (weight ratio) and (2) a diazo resin such as dodecylbenzenesulfonate of condensate of p-diazodiphenylamine and formaldehyde.

Abstract: A polyimide powder which can provide a molding having excellent both strength and heat resistance by heat-press molding, and a method for producing such polyimide powder are disclosed. The polyimide powder comprises spherical polyimide particles having a particle size distribution of from 0.5 to 20 .mu.m and a mean particle diameter of from 1 to 15 .mu.m, and comprising a repeating unit represented by the formula ##STR1## wherein Ar represents an aromatic diamine residue.

Abstract: A polyimide/metallic foil composite film having a curvature radius of at least 25 cm and which is substantially free from curling is described, comprising coating a solution of a polyimide precursor in an organic polar solvent on a 1 to 500 .mu.m thick metallic foil, the polyimide precursor being prepared by reacting a diamine component comprising p-phenylenediamine and an aromatic tetracarboxylic acid component comprising 3,3',4,4'-biphenyltetracarboxylic dianhydride or its derivative; heat-drying the above-prepared coating in the state that the metallic foil is fixed; and then heating it at a high temperature to form a 5 to 200 .mu.m thick polymide film. This composite film does not substantially curl in either the lengthwise and widthwise directions and is very suitable for use in the production of an electrical circuit board.

Abstract: A process for producing a polyimide/metallic foil composite film having a curvature radius of at least 25 cm and which is substantially free from curling is described, comprising coating a solution of a polyimide precursor in an organic polar solvent on a 1 to 500 .mu.m thick metallic foil, the polyimide precursor being prepared by reacting a diamine component comprising p-phenylenediamine and an aromatic tetracarboxylic acid component comprising 3,3',4,4'-biphenyltetracarboxylic dianhydride or its derivative; heat-drying the above-prepared coating in the state that the metallic foil is fixed; and then heating it at a high temperature to form a 5 to 200 .mu.m thick polyimide film. This composite film does not substantially curl in either the lengthwise and widthwise directions and is very suitable for use in the production of an electric circuit board.

Abstract: A desensitizing gum for a lithographic printing plate and a gumming up process thereof are disclosed. The gum is comprised of water having dispersed therein 5 to 35 wt %, based on the total weight of the gum, of a film-forming, water-soluble compound selected from the group consisting of enzyme-decomposed dextrine and enzyme-decomposed etherified dextrine. The desensitizing gum exerts a desensitizing action on non-image areas of a lithographic printing plate and does not cause image blinding of image areas even when the plate is stored for a long period of time.

Abstract: An improved lithographic printing plate and a process for production thereof, involving exposure to light, development, and burning-in treatment of a presensitized printing plate precursor, are disclosed, the improvement comprising applying an aqueous solution containing at least one compound selected from the group consisting of malic acid and salts thereof onto the printing plate precursor prior to the burning-in treatment; by the improvement, a lithographic printing plate having excellent printing durability can be produced.