Abstract: The present invention provides a finisher for a lithographic plateobtained by a DTR process comprising (a) hydrophobizing agent(s) in a total concentration between 0.1 g/l and 10 g/l, (a) surface-active compound(s) and (a) polyglycol(s) or (a) carbohydrate(s), characterized in that said finisher further comprises a non-proteinic hydrophilic film-forming binder selected from the group consisting of dextrin, maltodextrin and dextran in a concentration between 10 and 200 g/l.

Abstract: The lithographic affinity characteristics of a material, such as a polymer, are affected--and thereby selectively modulated--through implantation of one or more metallic materials, typically in the form of ions and/or atoms (or molecules). The desired characteristics are achieved by bulk chemical modification of the material rather than by texturing or deposition of a new surface layer. In the case of a polymer system, for example, the metal impregnates the matrix, penetrating to an observable depth without substantial surface accumulation.

Abstract: The invention utilizes ink jet liquid droplets from one or more printer heads to form an image upon the surface of a printing plate corresponding to digital information depicting the image as provided by a digital computer system which is in digital communication with the printer heads. The droplets from the printer head comprise resin forming reactants which polymerize on the plate surface, alone or in combination with reactants precoated on the plate, to form a printable hard resin image. The resin image so formed provides a lithographic printing plate useful for extended print runs.

Abstract: Provided is a composition curable by active energy rays, comprising a cationic polyacryloyl compound having two or more acryloyl groups and one or more cation groups in a molecule, represented by any of General Formulae (1) to (6) ##STR1## wherein Z.sub.1 to Z.sub.6 represent independently a residue derived from a polyhydric alcohol or a polyepoxide,K.sub.1 represents independently a radical of the formula ##STR2## K.sub.2 represents a radical of the formula ##STR3## R.sub.1 represents independently a radical of the formula ##STR4## wherein R.sub.3 is independently H-- or CH.sub.3 --, and R.sub.2 represents independently a radical of the formulaCH.sub.2 .dbd.CHCOO--, or CH.sub.2 .dbd.C(CH.sub.3)COO--.

Abstract: The present invention provides a method for making a lithographic printing plate according to the silver salt diffusion transfer process comprising the steps of:image-wise exposing an imaging element comprising on a support a photosensitive layer comprising a silver halide emulsion and an image receiving layer containing physical development nuclei,developing said imaging element in the presence of developing agent(s) and silver halide solvent(s) using an alkaline processing liquid andneutralizing a thus obtained developed imaging element using a neutralization solution having a pH between 4 and 10.5 and comprising a hydrophobizing agent and a buffer characterized in that said neutralization solution comprises a salt of sulfurous acid.

Abstract: Disclosed is a process for treating a plate surface of a lithographic printing plate, which comprises, after exposing and developing a lithographic printing plate having a support and at least a silver halide emulsion layer and a physical development nuclei layer provided on the support, treating the plate surface of the lithographic printing plate with a plate surface-treating solution containing at least one water-insoluble compound having a mercapto group or a thione group and a compound represented by the following formula (1): ##STR1## wherein A represents a vinyl monomer unit having a carboxyl group, B represents a copolymerizable ethylenic unsaturated monomer unit, M represents a cation, k represents 30 to 90 mole %, m represents 10 to 50 mole %, and n represents 0 to 50 mole %.

Abstract: An amine compound-containing, but cyanogen-free, desensitizing solution for offset printing, characterized by containing phytic acid (inositol hexaphosphate) and/or a metal and/or ammonium salts of phytic acid, and at least one selected from the group consisting of amine compounds represented by the following general formulae (1) and (2); a carboxylic acid or carboxylate containing (3); an urea (5) and/or an urethane (6) containing (4); an amide compound represented by (8) and/or an imide compound (9), each containing an amino group (7); and a heterocyclic compound at least one nitrogen atom and having an inorganic/organic value of 0.1 to 4.0 inclusive.

Abstract: There are disclosed a process for preparing a printing plate which comprises the steps of providing, on a support, a layer containing a water-soluble polymer which becomes water-insoluble by a metal ion, and feeding the metal ion imagewisely from the surface of the layer to form an image pattern comprising the hardened water-soluble polymer on the support, anda plate for preparing a printing plate which comprises a support and a layer containing a water-soluble polymer which becomes water-insoluble in contact with a metal ion provided on the surface of the support.

Abstract: An electrocoagulation printing apparatus comprises a positive cylindrical electrode having a central longitudinal axis extending horizontally and a passivated surface defining a positive electrode active surface, the positive electrode being formed of an electrolytically inert metal; a drive mechanism for rotating the positive electrode about the longitudinal axis thereof at a substantially constant speed; a coating device for coating the positive electrode active surface with an olefinic substance and a metal oxide to form on the surface micro-droplets of olefinic substance containing the metal oxide; and a printing head for forming on the olefin and metal oxide-coated positive electrode active surface a plurality of dots of colored, coagulated colloid by electrocoagulation of an electrolytically coagulable colloid in the presence of a coloring agent, the dots of colored, coagulated colloid being representative of a desired image.

Abstract: The present invention provides a method for making an offset printing plate according to the silver salt diffusion transfer process comprising the steps of exposing and developing an imaging element comprising in the order given on a hydrophilic surface of a support (i) an image receiving layer and (ii) a photosensitive layer comprising a photosensitive silver halide emulsion, removing the layer(s) on top of the image receiving layer thereby exposing the imaged surface of the support and treating said exposed imaged surface of the support with a finisher having a temperature between 30.degree. C. and 60.degree. C.

Abstract: The present invention discloses the use of rubber and surfactant to enhance the durability and resolution of on-press developable lithographic printing plates. The rubber is preferably incorporated into a photoresist as discrete particulate rubber. To ensure a uniform and stable dispersion, the rubber is suspended in the photoresist by means of a surfactant having an HLB approximately between 7.0 and 18.0.

Abstract: A method for producing an erasable printing form by making the outer layer of the printing form from a material containing strong micro-dipoles, preferably a ferroelectric material, in particular a ferroelectric ceramic. In wet offset printing, the non-printing areas of the printing form are rendered hydrophilic by a hydrophilizing agent and they are maintained during the entire printing process. Plate cleaners can, for example, be used as the hydrophilizing agents. The printing form can be erased by a nonpolar solvent and can be reused again by rendering the non-printing areas hydrophilic again.

Abstract: The present invention provides a method for making a lithographic printing plate according to the silver salt diffusion transfer process comprising the steps of:image-wise exposing an imaging element comprising on a support a photosensitive layer comprising a silver halide emulsion and an image receiving layer containing physical development nuclei,developing said imaging element in the presence of developing agent(s) and silver halide solvent(s) using an alkaline processing liquid andtreating the thus obtained developed imaging element using a finishing liquid having a pH of at least 8.5 being substantially free of oxidizing compounds.Less useless copies are generated at the start of the printing process using a printing plate obtained according to the method of the present invention.

Abstract: The present invention provides a treating solution for lithographic printing plates having ink receptive silver images in which the compound having a mercapto group or a thione group and an oleophilic group which is added to improve ink-receptivity can be solubilized without damaging the ink-receptivity and with using no solvent and in which hydrophilic colloid particles are excellent in time stability. The solution contains at least one alkanolamine and a compound having a mercapto group or a thione group and an oleophilic group and being free from sulfo group and carboxyl group. Preferably, the solution additionally contains an amino acid and hydrophilic colloid particles which are inorganic fine particles having an average particle size of 0.1 .mu.m or less.

Abstract: A desensitizing solution for lithographic platemaking which mainly comprises phytic acid or a salt thereof is disclosed, said desensitizing solution containing a polyether polyamine or a derivative thereof represented by formula (I): ##STR1## wherein k, m, x, and y each represent an integer of 1 or more; and R.sub.1 represents a hydrogen atom or C.sub.n H.sub.2n R.sub.2, wherein n is an integer of 1 or more, and R.sub.2 represents a hydrogen atom, an NR.sub.3 R.sub.4 (wherein R.sub.3 and R.sub.4 each represent a hydrogen atom or an alkyl group), a chlorine atom, a fluorine atom, an iodine atom, a bromine atom, a hydroxyl group, a carboxyl group or a carbamoyl group,or a polyamine derivative represented by formula (II): ##STR2## wherein X represents a halogen atom; p and each represent an integer of from 2 to 6; and r represents an integer of from 3 to 2000. The desensitizing solution exhibits satisfactory desensitizing characteristics without causing environmental pollution.

Abstract: The present invention provides a finisher comprising (a) hydrophobizing agent(s) in a total concentration between 0.1 g/l and 10 g/l, (a) surface-active compound(s) and (a) polyglycol(s), characterized in that said polyglycol(s) comprise(s) at least 50% by weight ethyleneoxide groups and/or propyleneoxide groups whose total sum is at least 7 and is (are) present in said finisher in a total amount of at least 10 g/l and there is further provided a method for making an offset printing plate according to the silver salt diffusion transfer process therewith.

Abstract: Process for the manufacture of a lithographic printing plate comprising the steps of:(1) information-wise projecting droplets of liquid, onto a receiving material having a hydrophilic surface to form a silver image by bringing into working relationship on said hydrophilic surface a reducible silver compound (A), a reducing agent (B) for said silver compound and physical development nuclei (C) that catalyze the reduction of said silver compound to silver metal, and(2) hydrophobizing the silver image that has been obtained through said step (1) e.g. by overall contacting the printing surface with a hydrophobizing substance for said silver image or hydrophobizing said silver image by imagewise depositing said hydrophobizing substance thereon.

Abstract: The present invention provides a conversion liquid for converting silver areas of a silver based printing plate into ink repellant areas while rendering background areas of said silver based printing plate ink accepting, said conversion liquid comprising a hydrophobizing compound capable of adsorbing to said hydrophilic background areas and a hydrophilizing compound capable of adsorbing to said silver areas and/or a bleaching compound capable of oxidizing the silver in said silver based printing plate.

Abstract: The present invention provides a method for making a lithographic printing plate according to the silver salt diffusion transfer process using a photographic material comprising on a support a silver halide emulsion layer and a layer containing physical development nuclei comprising the steps of:image-wise exposing said photographic material anddeveloping a thus obtained image-wise exposed photographic material by guiding said image-wise exposed photographic material through an alkaline processing liquid in 15 s or less; characterized in that said alkaline processing liquid comprises a hydrophobizing compound having a mercapto group that has a pK.sub.a of 4.5 or less.

Abstract: To compensate for tolerances and variations in tolerances in a recording system in which a thermal transfer foil is passed between a image recording element (3) and a printing form carrier (1), the thermal transfer foil, for example of a polyester base (9), has an intermediate layer (8) applied thereto on which a meltable substance layer (7, 7'), for example on a polyethylene base, is located. The intermediate layer (8) is thermally volume expandable, by including therein either a foaming agent or moisture or other gas which, upon application of heat, causes foaming or the formation of gas or steam bubbles to expand its volume. Tolerances 6 of up to about 1 mm, thus, can be compensated and pressure variations and surface variations between the thermal image recording element (3) and the form carrier (1) are no longer critical.

Abstract: To permit elimination of dampening rollers or an entire dampener in a lithographic, preferably offset printing machine, the printing form is formed as a cylindrical sleeve or jacket (3) fitted over a core (2), in which the cylindrical sleeve or jacket is formed with a plurality of interconnected pores (5), essentially uniformly distributed over the surface (4) and forming, within the sleeve or jacket, a connected pore fluid transfer network. Dampening fluid is then applied to the interior of the sleeve or jacket, for example from a chamber (6) between the cylindrical core (2) and the inner surface of the sleeve or jacket. The outer surface (4) can be imaged with oleophilic substances, for example by a thermal transfer process. To remove the images, for re-use of the printing form without removal from a printing machine, hot gases for example steam can be applied to the interior of the sleeve or jacket, so that the oleophilic substances at the outside will loosen for easy removal, or spall off.

Abstract: The present invention discloses a universal chemical system for offset printing comprising a plate coating, a fountain concentrate solution, an alcohol replacement solution, a roller coating, and a plate wash. The system uses the same types of chemicals throughout to achieve a system compatible throughout. The plate coating comprises deionized water, citric acid, sodium phosphate dibasic, gum arabic, magnesium nitrate solution, glycerine, and propyl alcohol. The fountain concentrate solution contains water, citric acid, sodium citrate, sodium phosphate dibasic, sodium benzoate, gum arabic, glycerine, ethyl hexandiol, and erio green B supra. The alcohol replacement solution contains deionized water, diethylene glycol, propasol P, glycerine, and dowanol PM. The roller coating contains deionized water, citric acid, disodium phosphate, gum arabic, glycerine, and propyl alcohol. The plate wash contains water, citric acid, dowanol EB, dowanol PM, maphos 8135, phosphoric acid, and erio glaucine a supra.

Abstract: A method for transferring a viscous substance, including the steps of: providing a viscous substance capable of changing its adhesiveness corresponding to the polarity of a voltage applied thereto; disposing the viscous substance between a first electrode and a second electrode; and applying a voltage to the viscous substance plural times, thereby to reduce the adhesiveness of the viscous substance to the first electrode.

Abstract: An image forming apparatus and method for forming an image includes a recording material which changes its adhesiveness in response to the polarity of the voltage applied thereto. Such a recording material can include negatively or positively changeable or inorganic particles, gas-generating solvents, a substance having a gel or sol state, and a dissociative electrolyte. The recording material is positioned between a pair of electrodes. At least one of the electrodes includes an electroconductive member and a pattern comprising an insulating material disposed on the electroconductive member. A voltage is then applied between the pair of electrodes to attach the recording material to one of the electrodes. Also provided is a pressure applicator for transferring to a transfer-receiving medium the recording material attached to the electrode.

Abstract: A method for supplying a viscous substance includes providing a viscous substance capable of changing its adhesiveness corresponding to the polarity of a voltage to be applied thereto; supplying the viscous substance between a pair of electrodes; and applying a pulse voltage between the pair of electrodes thereby to attach to at least one of the pair of electrodes the viscous substance of which amount corresponds to the effective duration factor of the pulse voltage.

Abstract: There is provided a method and apparatus for forming an image which includes providing a recording composition capable of changing its adhesivity corresponding to the polarity of a voltage applied thereto between a pair of electrodes. The recording composition has a transfer characteristic having a tendency to change by loss of at least one component of the recording composition. A voltage is applied between the pair of electrodes to attach the recording composition to one of the pair of electrodes to attach the recording composition to one of the pair of electrodes. Any such change in the transfer characteristic of the recording composition is detected during the process. In response to any change in the transfer characteristic additional component is added to the recording composition to compensate for that change.

Abstract: The present invention provides a processing composition which is used for lithographic printing plate where silver image is used as ink receptive area for enhancing ink receptivity of the silver image. This composition contains an organic compound having two or more mercapto groups or thion groups and, in combination therewith, an aromatic sulfonic acid formalin condensate, an anionic surfactant having a polyoxyethylene group, an aromatic carboxylic acid, a hydrosulfite compound, a water-soluble polymer having a carboxyl group and having a number-average molecular weight of about 20,000 or less, a hydroxyaryl fatty acid, or an organic disulfide compound. If this composition additionally contains an oxidizing agent, it can further improve printing endurance of the printing plate.

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: A xeroprinting master is formed by depositing a corona charge injection modifying material on a master substrate which includes a charge transport layer. The material can block the injection of charge that would otherwise inject into the charge transport layer or it can inject charge that would otherwise remain on the surface of the master. Preferably, the deposit is made by a conventional printer such as an ink jet, impact or thermal printer and the resulting deposit is not fused before use in xeroprinting.

Abstract: An aqueous lithographic conditioner solution or fix composition for use with lithographic plates made by the silver salt diffusion transfer process comprises (a) an oleophilic argentophile, (b) a quaternary ammonium surfactant and (c) a quaternary ammonium surfactant solubilized by the addition of alkyleneoxy units, the proportions and nature of the components being such as to provide the desired solution.

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 method for making lithographic printing plates which comprises imagewise exposing a presensitized plate for use in making lithographic printing plates to light, then developing and thereafter subjecting the developed plate to burning-in pretreatment, the method characterized in that the burning-in pretreatment is performed after applying, to the developed plate, an aqueous solution containing at least one organic solvent whose solubility in water at 25.degree. C. is not less than 0.5% by weight and whose surface tension measured on 0.5% by weight distilled water solution at 25.degree. C. is not more than 65 dyn/cm. The method can provide lithographic printing plates free of greasing, ink spreading on half-dot image portions, in particular shadow portions and excellent in ink receptivity of image areas. In addition, the method can be automated by making use of a spray-circulation type processing apparatus.

Abstract: A silver master plate recovery solution for a silver salt photographic plate for offset printing is disclosed which comprises (a) a hydrazine component for reducing the silver oxide layer of an image area, (b) a quaternary ammonium salt cationic activator and (c) water. The mixing ratio of the quaternary ammonium salt cationic activator is 3.0 to 20.0 wt % on the basis of the hydrazine component. The silver master plate recovery solution reduces the silver oxide layer of the image area of a silver salt photographic plate which has passed the stock time, thereby recovering the ink receptivity of the image area.

Abstract: Method of preparing a contoured plate by selectively hardening a photopolymer plate in a zone which is adjacent the lower surface of the plate and increases continuously in thickness from one portion of the plate to another by a first exposure of the upper surface of the plate to a quantity of light energy which increases continuously per unit area of the surface from said one portion of the plate to the other. Discrete portions of the upper surface of the plate are masked in the portions on which it is desired to form a recessed design, and the non-masked portions of the plate are hardened by a second exposure of its upper surface to light energy, so that the masked portions remain unhardened from their upper surface to the upper region of said hardened zone. The unhardened portions are removed to provide a recessed design in the upper surface of the plate. The design varies continuously in depth independently of the width of the design.

Abstract: An ink jet image transfer lithographic apparatus is coupled to a source for supplying graphics and textual material to an ink jet printhead. The ink jet printhead melts a hydrophobic solid ink and sprays the ink onto a lithographic plate in a predetermined pattern. The solid ink solidifies upon contact with the plate. The plate is then mounted in a lithographic press for lithographic printing. As an alternative, the ink jet printhead may be mounted in a lithographic press for imaging a lithographic plate mounted in the lithographic press or for spraying ink directly onto the plate cylinder of the press. A succession of lithographic plates may be provided around the plate cylinder of the lithographic press and each plate discarded after use, leaving a clean plate on the plate cylinder.

Abstract: A printing system incorporating a re-usable ink image transfer surface. A material which forms a thin hydrophobic layer is arranged by various techniques over a substantially hydrophilic transfer surface in a configuration which defines the desired latent image in terms of exposed, contiguous hydrophilic and hydrophobic areas. In some cases, a hydrophilic layer may be in direct contact with the hydrophobic layer. Depending upon the configuration of the layers, either an aqueous or oleo ink may be used to develop and print an image. If desired, the layer configuration may be replaced by a different configuration without substantial interruption to the printing process. No photo-induced chemical reaction or latent image developing steps are required at any time. The ink image transfer surface may be a planographic gravure cylinder or a gravure roll.

Abstract: A material is provided for adding image areas to grained lithographic offset plates. A polyester resin with imbedded fibers changes the surface characteristics of the printing plate from an oily ink repellant condition to an oily ink receptive condition. In a preferred embodiment, a resin of PBT or PET is provided in generally solid form which may be shaped to a desired form for application to the plate. Corrections may be made to a plate either on or off a printing press and at any stage of the print run.

Abstract: Inks containing at least one keto-ether, such as 4-meth-4-methyl-2-pentanone, are able to print on resinous block copolymers, such as butadiene/styrene block copolymer, having an anti-blocking agent incorporated therein, such as a micro crystalline wax.

Abstract: A lithographic printing plate having metallic silver image areas is treated with a proteolytic enzyme and an oleophilizing compound to improve ink receptivity.

Abstract: A method for the preparation of electrostatic masters, and product prepared thereby, said masters having improved water and pick resistance for lithographic printing. The method comprises applying a barrier coat formulation to a substrate wherein the formulation contains an aqueous dispersion of a copolymer of at least about 60% ethylenically unsaturated polymerizable monomer having non-polar functionality and about 3 to about 40% of a polymerizable olefinically unsaturated monomer having polar functionality.

Abstract: A plate for lithography or offset printing comprising a flexible substrate and a water-resistant coating layer formed on the flexible substrate, said water-resistant coating layer being composed of a water-insoluble resin binder and an inorganic pigment dispersed in said binder, and the water-resistant coating layer including an oleophilic ink-supporting portion composed of particles consisting essentially of at least one member selected from triiron tetroxide and .gamma.-type diiron trioxide, the particles being embedded in at least a part of the surface of the coating layer, and an etched hydrophilic ink-repelling portion composed of the inorganic pigment.

Abstract: This invention is directed to a composition useful for making a fountain solution for lithographic printing operations which comprises trisodium phosphate, sodium metasilicate, tetrapotassium pyrophosphate, a nonionic detergent which is a condensation product of ethylene oxide with an alkylamine, and dialkylpolysiloxane. The invention is further directed to a method for making such a fountain solution which comprises combining any of the compositions of the invention with water.

Abstract: An electrostatic master having improved water, cockle and pick resistance for lithographic printing, and method for making the same, comprising a base, a barrier coat applied to said base, and a photoconductive layer containing a photoconductive material and binder applied to said barrier coat. The barrier coat preferably comprises a copolymer of at least 60% ethylenically unsaturated polymerizable monomer having non-polar functionality and about 3 to about 40% of a polymerizable olefinically unsaturated monomer having polar functionality. The barrier coat preferably contains about 2.5 to about 50% plastic particles based on the weight of the barrier coat. The barrier coat achieves improved water resistance at low coat weights, and thus can be applied without substantial change in conductivity.

Abstract: A method for producing prints having continuous tone gradation which includes the steps of selectively placing solvents on a semi-opaque substrate having a surface altering the surface of the substrate enabling the substrate to hold a colorant, placing colorant on the areas of the substrate so treated, thereby producing continuous tone gradations, transferring an image of the continuous tone gradation substrate onto a conventional print plate and printing prints from the print plate. The steps of transferring can be done either by direct contact printing or by an intermediate conventional negative. The most preferred embodiment includes ethyl alcohol as the solvent, cellulose acetate as the substrate and india ink as the colorant. Multicolor prints can be made from varying density print plates produced by differing exposure times of transferring the image and overprinting the plates using differing inks.

Abstract: The invention provides a novel planographic printing plate suitable for dry planographic printing without supply of dampening water and a method for the preparation thereof. The inventive printing plate has, on one surface of a base plate, a layer of an organopolysiloxane composed of the areas where fresh surface of the organopolysiloxane is exposed bare as the ink-repellent non-image areas and the areas where the surface of the organopolysiloxane layer has been subjected to the treatment with low temperature plasma to be oleophilic or ink-receptive as the image areas of the printing plate. According to the inventive method, the pattern-wise exposure of the organopolysiloxane layer to the plasma atmosphere is performed by first providing a pattern-wise layer of a plasma resistant protective resist layer on the organopolysiloxane layer followed by the plasma treatment and removal of the resist layer.

Abstract: An agent for protecting the surface of a lithographic printing plate which is an emulsion comprising an oil phase containing a plasticizer having a solidifying point of 15.degree. C. or less and a surfactant, and an aqueous phase having dissolved therein a hydrophilic high molecular weight compound.

Abstract: A system for producing lithographic printing plates by image transfer from either a right way or a wrong way reading recording member, which comprise a conductive base having first and second register means thereon the register means being arranged and positioned respectively so that the first engages and locates an image receiving member and a recording member on the base and the second engages and locates an offset member on the base, the register means being spaced apart to allow access to the first register means while the offset member is engaged on the second register means, a roller having at least a conductive core arranged to move over the base outwards from the register means and return, and means to apply an electrical field between the roller and base and to change the polarity to prevent electrostatic image transfer during the outward movement of the roller and to cause electrostatic image transfer during the return movement of the roller.

Abstract: Process for etching a nickel-polyester layered offset plate, which is made by electroless nickel-plating of polyester and subsequently coated on the nickel-layer by a photoresist layer. After exposure of the photoresist layer under a transparent master and development of the offset-plate, the offset-plate is etched by an aqueous etching solution containing copper(II) ions, as the only etching agent together with Cl.sup.- ions. An offset printing plate is prepared from the etched nickel-polyester layered plate. The nickel layer of the nickel-polyester layered plate is etched with the aqueous etching solution. The etching solution additionally contains:(a) a salt which is inert as against the nickel-polyester layered plate, or 10 to 40 weight percent of an organic solvent, which is miscible or nonmiscible with water and which is inert as against the nickel-polyester layered plate, and 60 to 90 weight percent of de-ionized water; and(b) a wetting agent or pyridine.

Abstract: The present invention provides a lithographic printing plate, which is made by exposing a photographic material having a silver halide photosensitive emulsion layer, developing the exposed material and treating the developed material with a conversion liquid comprising a solvent for a silver halide and an organic compound capable of forming a compound which is more stable and has a lower solubility than a soluble silver complex formed by said solvent.

Abstract: A photolithographic plate, method for preparation thereof, and salt compound useful in the preparation, the method involving the treatment of a metallic silver image on a substrate with a homogeneously stable acidic aqueous salt solution comprising a ferricyanide anion for oxidizing the metallic silver and an organic cation capable of forming a water-insoluble, inherently oleophilic complex with oxidized silver, the cation being derived from a protonatable nitrogen-substituted hydrocarbon compound containing a formal imine group therein which is in resonant association with adjacent groups within the hydrocarbon compound.