Abstract: A method of development is disclosed, wherein printing plate precursors capable of being exposed with an infrared laser can be developed over a prolonged period without causing image defects, etc. The method comprises conducting the development of a photosensitive lithographic printing plate precursor using an automatic developing apparatus having a substantially closed developing tank in which a developing solution is introduced and a conveying means for conveying the plate precursor disposed within the developing tank.

Abstract: Provided are a developer suitable for both positive working and negative working photosensitive lithographic printing plates for lithography and a replenisher thereof which comprise as a development stabilizer at least one compound selected from the group consisting of sugars, oximes, phenols and fluorinated alcohols in a proportion of at least 0.01 mole/l and have their pH values in the range of 11.0 to 13.5 by containing an alkali agent and a developer for photosensitive lithographic printing plates which comprises (1) a compound represented by formula (A) or (B) described in the present specification, (2) at least one compound selected from the group consisting of phenols, sugars, oximes and fluorinated alcohols which have buffering effect in the pH range of 11.5 to 13.5 and (3) a specific alkali agent, and has a pH of 11.5 to 13.5.

Abstract: A presensitized plate for use in making a lithographic printing plate comprises a substrate; a photosensitive layer and a mat layer whose projections have an average diameter of not more than 100 .mu.m, an average height of not more than 10 .mu.m and whose coated amount ranges from 5 to 200 mg/m.sup.2, the photosensitive layer and the mat layer being applied onto the upper surface of the substrate; and a coating layer of an organic polymeric compound having a glass transition point of not less than 20.degree. C. and a thickness ranging from 0.01 to 8.0 .mu.m, the coating layer being applied onto the back face of the substrate. The presensitized plate makes it possible to solve the problem of the formation of scratches and the adhesion of the photosensitive layer to the back face of the PS plate even when a large number of PS plates are transported and/or stored while putting them in piles without sandwiching the PS plate between interleaves.

Abstract: A method for preparing a lithographic printing plate comprises imagewise exporting a PS plate comprising an aluminum substrate having an anodized layer and a light-sensitive layer applied on one side of the substrate and then developing the PS plate with a developer comprising an aqueous solution of an alkali metal silicate, while compensating changes in the developer due to the development of the PS plate by supplementing, to the developer, a replenisher comprising an aqueous solution of an alkali metal silicate, wherein the PS plate is provided with a coating layer containing an organic polymeric compound on the back face and the replenisher is an aqueous solution of an alkali metal silicate having a ratio: [SiO.sub.2 ]/[M.sub.2 O] (wherein [SiO.sub.2 ] means molar concentration (mol/l) of SiO.sub.2 and [M.sub.2 O] is molar concentration (mol/l) of oxide M.sub.2 O of an alkali metal (M)) ranging from 0.3 to 1.0 and an SiO.sub.2 content ranging from 0.5 to 4.0% by weight.

Abstract: A PS plate comprises an aluminum substrate having anodized layers on both sides, a photosensitive layer on one side of the substrate and a coating layer of a metal oxide obtained by hydrolyzing and polycondensing an organic or inorganic metal compound on the side of the substrate opposite to that carrying the photosensitive layer. The PS plate is processed by a method comprising the steps of imagewise exposing it to light and then developing the imagewise exposed plate with an alkali aqueous solution containing an alkali metal silicate and having a pH of not less than 12. The PS plate and the method for processing the same permit substantial reduction of the amount of a replenisher for development to be supplemented and ensure a stable processing of the plate over a long time period without accompanying formation of insolubles in a developer. The PS plates never cause adhesion and peeling off of the photosensitive layers even when they are put in stacks.

Abstract: A method for processing a photosensitive copying material comprises the steps of imagewise exposing to light a photosensitive copying material which comprises in order (i) a first photosensitive organic coating layer whose solubility in a developer varies through irradiation with light rays and (ii) a second organic coating layer containing a water-insoluble and organic solvent-soluble polymeric compound having an film-forming ability and then developing the imagewise exposed copying material, wherein the imagewise exposed material is dipped in the developer and then water-washed to remove the first and second organic coating layers on non-image portions. According to this method, the ability of the developer to process photosensitive copying materials is substantially improved, the amount of the waste liquor can substantially be reduced and a problem of environmental pollution can effectively be solved.

Abstract: A PS plate comprises an aluminum plate which is surface-roughened and then anodized so that the amount of an anodized layer formed is not less than 1.0 g/m.sup.2 ; a hydrophilic layer which is applied onto the anodized layer and which comprises at least one compound selected from the group consisting of:(A) substituted or unsubstituted aliphatic or aromatic phosphonic acids having one or two phosphonic acid residues in the molecule and salts thereof; and(B) substituted or unsubstituted aliphatic or aromatic phosphinic acids having one or two phosphinic acid residues in the molecule and salts thereof,wherein the substituent of the compounds (A) and (B) being at least one member selected from the group consisting of hydroxyl, alkoxy, aryloxy, carboxyl, alkyl, aryl, allyl, acyl, acyloxy, nitro and cyano groups and halogen atoms; and a layer of a positive-working light-sensitive composition formed on the hydrophilic layer.

Abstract: A method for preparinq a lithographic printing plate comprising the steps of imagewise exposing, to light, a negative-working presensitized plate for use in making a lithographic printing plate which comprises a substrate provided thereon with a light-sensitive layer comprising an aromatic diazonium compound having at least one member selected from the group consisting of carboxyl groups, phenolic hydroxyl groups, sulfonic acid residues, sulfinic acid residues and phosphorus atom-containing oxyacid residues and developing the imagewise exposed presensitized plate with a developer which comprises an aqueous solution of an alkali metal or ammonium silicate having a ratio: [SiO.sub.2 ]/[M], wherein [SiO.sub.2 ] and [M] represent the molar concentrations of SiO.sub.2 and the alkali metal or ammonia in the developer respectively, ranging from 0.15 to 0.75 and an SiO.sub.2 content ranging from 1.0 to 4.

Abstract: A method of making a lithographic printing plate comprises the steps of imagewise exposing to light a presensitized plate which comprises a hydrophilized substrate provided thereon with an organic layer comprising at least one compound selected from the group consisting of substituted or unsubstituted aliphatic or aromatic compounds represented by the following general formula:R.sup.1 (PO(OH.sub.2).sub.n (I) orR.sup.1 (PO(OH)(R.sup.2)).sub.n (II)wherein n is 1 or 2, if n is 1, R.sup.1 and R.sup.2 each represents a substituted or unsubstituted alkyl, alkoxy, aryloxy, aryl, acyl or acyloxy group and if n is 2, R.sup.1 represents a substituted or unsubstituted alkylene or arylene group and R.sup.

Abstract: A method for manufacturing lithographic printing plates which comprises developing a presensitized plate for use in making lithographic printing plates imagewise opposed to light with an alkaline developer utilizing an automatic developing machine and then treating the developed presensitized plate with a finisher, wherein an initial pH of the finisher ranges from 2 to 8 and a pH of the finisher is controlled during running in proportion to concentration of the developer included in the finisher. The method makes it possible to prevent the formation of gel-like insoluble matters in the bath for treatment with the finisher due to the presence of the developer carried over from a developing bath and to stably process a large amount of lithographic printing plates over a long time period.

Abstract: A desensitizing gum lithographic plate finisher comprises water-soluble starch modified with urea-phosphoric acid containing 0.01 to 3% by weight of bound phosphorus and having a viscosity determined on 20% by weight aqueous solution at 30.degree. C. ranging from 15 to 300 cps. The plate finisher can also be used as an aqueous phase of an emulsion type plate finisher. The finisher has high desensitizing ability and excellent low temperature storability and does not cause any reduction in the ink receptivity of image areas of lithographic printing plates.

Abstract: Disclosed is a method for the manufacture of a lithographic printing plate where a photosensitive lithographic printing plate precursor is imagewise exposed, a determined about of a developer is supplied to the exposed surface and the developer is the disposed of. A surfactant is added to the developer so that the surface tension of the developer is about 50 dyne/cm or less at 25.degree. C. By the addition of the surfactant, a stable and economical development of an exposed plate is possible with a small amount of the surfactant-containing developer.

Abstract: This invention provides a developing method for photosensitive materials, in particlar for a positive photosensitive lithographic printing plate, which enables an efficient development with minimum consumption of the developing liquid. The developing method of the present invention comprises the steps of: conducting a preparatory development by applying a developing liquid to an exposed photosensitive layer of a photosensitive material, the developing liquid being supplied in an amount of necessary for each developing cycle; removing the developing liquid; discarding the developing liquid; and again applying a developing liquid to the photosensitive material to complete the development.

Abstract: A desensitizing gum containing water-soluble carboxy alkylated starch wherein the carboxy alkyl group number of said carboxy alkylated starch is from 0.03 to 0.5. The desensitizing gum has desensitizing ability comparable to gum arabic.

Abstract: A desensitizing gum comprising an aqueous solution containing at least one of film-forming starches modified with phosphoric acid or its derivatives. The desensitizing gum has good desensitizing ability and can easily be removed from a printing plate finished therewith after prolonged storage.

Abstract: A photosensitive composition containing a 2-halomethyl-5-substituted-1,3,4-oxadiazole compound represented by the following general formula (I): ##STR1## wherein A represents a substituted or unsubstituted aromatic residue; X represents a hydrogen atom, a cyano group, an alkyl group or an aryl group; Y represents a chlorine atom or a bromine atom; and n represents an integer of 1 to 3.The free radical generating agent represented by the general formula (I) has a photosensitive wavelength range from near ultraviolet range to visible range, high photo-decomposition sensitivity and good compatibility with other components present in the photosensitive composition.The photosensitive composition is suitable for use in light-sensitive printing plates or photo-resists.

Abstract: A light-sensitive planographic printing plate comprising a layer of a photo-polymerizable composition provided on at least one side of a base, wherein said photo-polymerizable composition comprises:(A) a polymer having at least one group represented by the general formula (I) ##STR1## wherein R.sub.1 to R.sub.5 each represent a member selected from the group consisting of a hydrogen atom, a halgen atom, a carboxyl group, a sulfo group, a nitro group, a cyano group, an amido group, an amino group and a substituted or unsubstituted alkyl group, aryl group, alkoxy gruop, aryloxy group, alkylamino group, arylamino group, alkylsulfonyl group and arylsulfonyl group and Z represents an oxygen atom, a sulfur atom, NH or NR, wherein R represents an alkyl group; and a carboxyl group on the side chain;(B) a monomer or oligomer having at least two polymerizable ethylenically unsaturated double bonds;(C) a photo-polymerization initiator, and(D) a diazo resin.

Abstract: A method for forming an image on a light-sensitive material with a light-sensitive layer composed of a photopolymerizable composition, and an apparatus for carrying out the method are described. This method comprises exposing imagewise, heating, and developing a number of light-sensitive materials while the time interval between the heating and developing steps is maintained at a definite level. Changes in sensitivity of the light sensitive material are prevented and images of high sensitivity are obtained.

Abstract: A presensitized printing plate which has a photopolymerizing composition layer provided on at least one side of a support, with the photopolymerizing composition being constituted with (A) a polymer containing in its side chains groups represented by the following general formula (I) and carboxylic groups: ##STR1## (wherein R.sub.1 to R.sub.5 each represents a hydrogen atom, a halogeno group, a carboxyl group, a sulfo group, a nitro group, a cyano group, and amido group, an amino group, or an unsubstituted or a substituted alkyl, aryl, alkoxy, aryloxy, alkylamino, arylamino, alkylsulfonyl or arylsulfonyl group; and Z represents an oxygen atom, a sulfur atom, --NH-- or --NR-- (R=alkyl)), (B) a monomer or an olygomer having at least two polymerizable ethylenically unsaturated double bonds, and (C) a photopolymerization initiator.

Abstract: The formation of spots when making a printing plate using a presensitized printing plate comprising a silver halide light-sensitive layer formed on an aluminum support having an aluminum oxide film on the surface directly or over a non-silver light-sensitive intermediate layer is effectively prevented by incorporating a mercapto compound in one of the layers.