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 concentrated dampening water composition for lithographic printing comprises a) 0.1 to 10% by weight of a hydrophilic polymeric compound having a film-forming ability; b) 0.01 to 15%, by weight of a pH buffering agent; c) 5 to 80% by weight of a water-miscible organic solvent having a boiling point of not less than 140.degree. C. and whose 1% by weight aqueous solution has a surface tension of not more than 60 dynes/cm; d), 0.05 to 10% by weight of a compound, for instance, represented by the following general formula (III); and e) 30 to 80% by weight of water:R.sup.8 --Z.sup.1 (R.sup.9)(R.sup.10)--R.sup.7.X.sup.1 (III)wherein R.sup.7 to R.sup.10 each represents a C.sub.1-12 alkyl, cyclic alkyl, hydroxyalkyl, benzyl or substituted or unsubstituted phenyl group; Z.sup.1 represents N, P or B; X.sup.1 represents an anion or cation selected from the group consisting of halogen, nitrate, sulfate, phosphate, hydroxyl, PF.sub.6.sup.-, BF.sub.4.sup.-, Li.sup.+, Na.sup.+, K.sup.+ and NH.sub.4.sup.+.

Abstract: A dampening water composition for lithographic printing plate comprises a hydrophilic polymer having a film-forming ability, a pH-buffering substance and at least one compound selected from the group consisting of benzimidazole and derivatives thereof. The dampening water composition can effectively suppress the corrosion of copper or copper alloy-plated rolls of a printing press as well as cast iron or nickel-plated cast iron parts thereof without impairing printing effects and printability.

Abstract: Disclosed is a dampening solution composition for lithographic printing. The solution has a dynamic surface tension ranging from 20 to 50 dyne/cm at 15.degree. C. at most 1.times.10.sup.-1 seconds after a new surface of the solution is formed on the surface of a printing plate; a viscosity ranging from 1.05 to 5.0 cSt at 15.degree. C.; and an emulsification ratio when mixed with ink which is higher by 2 to 30% than that of pure water mixed with ink.

Abstract: A photo-sensitive printing plate processing apparatus for processing a photo-sensitive printing plate upon which an image has been exposed is provided wherein, adjacent to a main developing tank where the photo-sensitive printing plate is conveyed, immersed in developing solution and developed, on either the upstream or downstream side with respect to the direction of conveyance of the photo-sensitive printing plate, an auxiliary developing tank is provided for applying developing solution to the photo-sensitive printing plate and performing auxiliary developing thereof and therefore allowing definite developing of the photo-sensitive printing plate to be achieved.

Abstract: A light-sensitive material processing apparatus for processing an image-wise exposed light-sensitive material by immersing the light-sensitive material in a processing solution while the light-sensitive material is being automatically conveyed. The apparatus includes a scraping brush constituted by a shaft and a synthetic resin-made elongated brush wound spirally around an outer periphery of the shaft. Accordingly, the light-sensitive layer of the light-sensitive material is scraped off by the scraping brush to effect processing.

Abstract: A dampening water composition for lithographic printing which comprises 0.1 to 5% by weight of at least one member selected from the group consisting of monoalcohols or diols of alkanes or alkenes having 5 to 11 carbon atoms, to which 1 to 10 moles of ethylene oxide and/or propylene oxide are added. The dampening water composition is not toxic, has not a possiblity of causing a fire and pollution of working atmosphere and, therefore, the use of a local exhaust installation is not necessary. Moreover, it is excellent in characteristics as dampening water such that it does not cause contamination of metering roll, has good bleeding properties, emulsifying properties and stability in continuous processing as well as low foaming properties. Thus, the composition makes printing operation quite stable.

Abstract: The present invention relates to a concentrated dampening water for a lithographic printing plate characterized by comprising:(a) 0.5 to 50% by weight of, as a nonionic surfactant, at least one compound selected from the group consisting of ethylene oxide and/or propylene oxide adduct of 2-ethyl-1,3-hexanediol and ethylene oxide and/or propylene oxide adduct of acetylene alcohol or acetylene glycol,(b) 1 to 30% by weight of 4-hydroxy-4-methyl-2-pentanone and/or a compound of the following formula [I], [III] or [III]: ##STR1## wherein R represents a methyl group, an ethyl group, a propyl group or a butyl group, and(c) 30 to 75% by weight of water.

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: A photo-sensitive printing plate automatic developing apparatus for conveying a photo-sensitive printing plate upon which an image has been exposed, along a conveyor route while developing it in a developing tank, and then performing at least one of the following processes of washing, rinsing and desensitizing, is provided on the side of the developing tank from which the photo-sensitive printing plates are inserted, and is provided with a pair of insertion rollers that hold said photo-sensitive printing plate and conveys photo-sensitive printing plate downwards at an angle of 20.degree. or less to the horizontal, and a pair of squeeze rollers to squeeze the developing solution on the surface of said photo-sensitive printing plates while holding and conveying them after they have been conveyed drawings, in a state where the maximum radius of curvature of the photo-sensitive printing plate in the developing solution of said developing tank is from 200 mm to 900 mm.

Abstract: A method for supplementing a replenisher for developer which comprises developing a large number of PS plates imagewise exposed to light with a developer composed of an aqueous solution containing electrolytes in an automatic developing machine, characterized by determining an AC impedance of the developer contained in the automatic developing machine, obtaining a correction impedance from the measured impedance value and rate of replacement and supplementing a desired amount of the replenisher to the developer when the correction impedance reaches a predetermined value. This method makes it possible to maintain a desired activity of the developer even when a large number of PS plates are processed and to relax the restriction on the incorporation of optional devices such as an autofeeder into the automatic developing machine.

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: A devleoping device for photosensitive materials, particularly, for photosensitive materials used flat printing plates, in which the consumption rate of the developing solution is significantly reduced. The developing solution is applied to the exposed surface of the heated photosensitive material and excess portions thereof quickly removed before the temperature of the photosensitive material is significantly lowered or the temperature of the developing solution significantly raised. The excess portons of the developing solution are recycled.

Abstract: An emulsion type desensitizing gum comprises at least one polybasic acid monoester derivative of polysaccharide. The desensitizing gum exhibits high shelf stability and the lithographic printing plate to which the desensitizing gum has been applied hardly causes the background contamination of printed matters and is excellent in both the ink receptivity of the image areas and the desensitizing ability of the non-image areas.

Abstract: An electrophotographic lithographic printing plate is described, comprising an electrically conductive support and a photoconductive layer on the support, said layer being made mainly of a photoconductive zinc oxide and a resin binder, wherein in the surface of the photoconductive layer, the degree of exposure of photoconductive zinc oxide is from 10% to 70%.

Abstract: An electrophotographic photoreceptor having on a conductive support an interlayer and a photoconductive photoreceptive layer in that order, with the interlayer containing at least one colloidal substance selected from colloidal silica and colloidal alumina, and an organic solvent soluble resin which is composed of(A) a polymer having an acid value of from 10 to 100 and containing repeating units represented by formula (I) and (II) ##STR1## wherein R.sub.1 represents H or CH.sub.3 ; R.sub.2 represents H, --CH.sub.3, --C.sub.2 H.sub.5, or a chloromethyl group; and n represents an integer of 1 to 10; ##STR2## wherein R.sub.3 represents H or --CH.sub.3 ; and (B) at least one polymer selected from a homopolymer and a plural copolymer having a glass transition point (Tg) of from -70.degree. to 20.degree. C., which can be utilized as a lithographic printing material having long press life.