Abstract: A developer for a presensitized plate for use in making a lithographic printing plate requiring no dampening water comprises: (1) 1 to 39% by weight of at least one alcohol derivative selected from the group consisting of those represented by the following general formula (I): ##STR1## (wherein R.sup.1 represents an alkyl or alkenyl group having 4 to 12 carbon atoms; R.sup.2 represents a hydrogen atom or a methyl group; and n is an integer ranging from 1 to 6); (2) 1 to 39% by weight of at least one water-soluble organic solvent having a boiling point of not less than 100.degree. C.; and (3) 60 to 98% by weight of water. If this developer is used, foaming is hardly caused during the development processing a PS plate requiring no dampening water, it has excellent developing ability and half tone dot reproduction and can provide an excellent lithographic printing plate free of defects such as scratch marks.

Abstract: The present invention relates to a presensitized plate for use in making a lithographic plate requiring no dampening water and comprising, on a support, a light-sensitive resin layer and a silicone rubber layer, in this order, wherein the silicone rubber layer is crosslinked by addition reaction of an .fwdarw.SiH group with a --CH.dbd.CH-- group and wherein the light-sensitive resin layer comprises: (1) a monomer or oligomer having at least one photopolymerizable or photo-crosslinkable and olefinically unsaturated double bond, (2) an organic solvent-soluble polyurethane resin having a glass transition temperature of 20.degree. C. or below and being capable of forming a film, and (3) a photopolymerization initiator. According to the present invention, the PS plate has excellent image-forming properties and printing properties.

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 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 presensitized plate, for use in making a lithographic printing plate requiring no dampening water, comprises a substrate, a light-sensitive resin layer applied thereon and a silicone rubber layer formed on the light-sensitive layer which is cross-linked through a reaction of SiH groups with --CH.dbd.CH-- groups, the light-sensitive resin layer comprising:(1) a monomer or an oligomer having at least one photopolymerizable (meth)acryloyl group and at least one allyl group;(2) a photopolymerization initiator; and optionally(3) a polymeric compound having film-forming ability; and(4) a monomer or an oligomer having at least one photopolymerizable (meth)acryloyl groups and free of allyl groups.According to the presensitized plate, the adhesion between the addition type silicone rubber layer and the light-sensitive resin layer is greatly improved and excellent image-forming properties of the presensitized plate are thus ensured.

Abstract: A photopolymerizable composition is provided containing a polymerizable compound having an ethylenically unsaturated bond, a photopolymerization initiator, and if necessary, a linear organic high molecular weight polymer. The photopolymerization initiator comprises a combination of (a) an organic compound represented by formula (I): ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4, which may be the same or different, each represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted heterocyclic group, and at least two of said R.sup.1, R.sup.2, R.sup.3, and R.sup.4 may combine to form a cyclic structure, with the proviso that at least one of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is an alkyl group, and wherein Z.sym. represents an alkali metal cation or a quaternary ammonium cation, and (b) an organic dye having no counter anion.

Abstract: A light-sensitive composition which is developable with an aqueous alkaline solution, comprising (a) at least one light-sensitive resin obtained by adding an active mercaptocarboxylic acid to a part of carbon-carbon unsaturated bonds of a polymer having at least two photodimerizable unsaturated double bonds adjacent to an aromatic nucleus in the main chain thereof and (b) optionally at least one negative-working diazo resin. The light-sensitive composition makes it possible to prepare a light-sensitive plate capable of developing with an aqueous alkaline solution without forming insoluble substances in the developer during the development and the adhesive force between the substrate and the light-sensitive layer of the plate is increased, which in turn substantially improves the printing durability of the lithographic printing plate as a final product.

Abstract: A photopolymerizable composition containing a polymerizable compound having an ethylenically unsaturated bond, a photopolymerization initiator, and if necessary, a linear organic hibh molecular weight polymer. The photopolymerization initiator comprises a combination of (a) at least one organic boron compound anion salt of an organic cationic dye, andd (b) a compound represented by formula (I): ##STR1## wherein x represents a halogen atom; Y represents --CH.sub.3, --NH.sub.2, --NHR', --N(R').sub.2, or --OR' wherein R' represents an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group; and wherein R represents --CX.sub.3, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, or a substituted alkenyl group.

Abstract: A process for producing a photosensitive lithographic plate comprises coating onto a substrate having a hydrophilic surface a solution of a negative working photosensitive composition containing a photosensitive diazo resin and a linear organic polymer dissolved in a solvent mixture comprising:(a) at least 10 wt. % of 1-methoxy-2-propanol,(b) an amino group-free polar solvent having a boiling point under 1 atm of 50.degree. to 100.degree. C. and a dielectric constant at 20.degree. C. of at least 5.5, and(c) 2 to 50 wt. % of methyl lactate,and drying the coated solution.

Abstract: A color measuring apparatus including a photoelectric conversion device for outputting basic color signals corresponding to quantities of light of basic color components of a sample, respectively, a calculating device for calculating a color value of the sample in a predetermined colorimetric system, a target setting device for setting a target color value of the sample in the predetermined colorimetric system, a region setting device for setting a predetermined region containing the target color value, a region decision device for deciding whether or not the color value falls within the predetermined region, an approximation decision device for deciding whether or not the color value has most approximated to the target color value and an output device for outputting a result of the decision of the approximation decision device.

Abstract: Disclosed is a process for preparing an image-bearing plate for use in a lithographic printing plate, a photoresist or the like. The process comprises, after imagewise exposing a light-sensitive plate comprising a support having provided thereon a light-sensitive layer comprising a compound capable of producing an acid upon irradiation with actinic rays, a compound having at least one acid-decomposable group, and an alkali-soluble resin, treating the exposed plate with hot water of at least 25.degree. C. for a period of at least 10 seconds, prior to development. It is possible to achieve high sensitivity regardless of the interval between the exposure and the development.

Abstract: The present invention relates to a photosensitive lithographic plate necessitating no damping water, which plate has an excellent image reproducibility and stability in the lapse of time. The plate comprises, on a support, a photosensitive layer and a silicone rubber layer in this order, the silicone rubber layer being formed by addition reaction of an SiH group with a --CH.dbd.CH- group to cause crosslinking, and the photosensitive layer comprising:(1) a polymer comprising at least a structural formula (I): ##STR1## wherein R represents a hydrogen atom or a methyl group; R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.

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 light-sensitive composition for use with lithographic printing plates is described which comprises (1) a light-sensitive, organic solvent soluble and substantially water-insoluble diazo resin which is the reaction product of a water-soluble, light-sensitive condensate of an aromatic diazonium compound and an organic condensing agent with a halogenated Lewis acid or a salt thereof, (2) a substantially water-insoluble, film forming organic high-molecular weight compound having an acid value of from 10 to 200, (3) a polynuclear aromatic sulfonic acid or a salt thereof, and (4) a salt-forming organic dye compound.

Abstract: A developing solution for developing a light-sensitive lithographic plate having a o-quinonediazide compound-containing light-sensitive layer is disclosed. The developing solution is comprised of an aqueous solution containing alkali silicate and an alkali aqueous solution-soluble compound of a metal selected from the group consisting of Sn, Pb, Fe, Co and Ni. The developing solution provides excellent resolving power, has excellent development stability, processing capability and adaptability with respect to automatic developing machines.

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: A cyan-free desensitizing solution for use in offset printing comprising as the effective ingredients:(a) at least one member selected from the group of an ammonium salt and amine salt of inositol hexaphosphate ester;(b) a water-soluble cationic polymer; and(c) a low molecular weight electrolyte.

Abstract: An improved process for restoring the hydrophilic property of stained non-image areas in a lithographic printing plate is described, which comprises treating said lithographic printing plate with a plate cleaner, wherein the improvement comprises using a plate cleaner comprising an aqueous solution containing a silicate and at least one surface active agent selected from the group consisting of cationic surface active agents and amphoteric surface active agents.

Abstract: A presensitized lithographic printing plate precursor is described, comprising an aluminum support that has been rendered hydrophilic having provided thereon a light-sensitive layer composed of a light-sensitive composition comprising (1) an organic solvent-soluble and substantially water-insoluble diazo resin, (2) a substantially water-insoluble, film-forming polymeric compound, and at least one of (3a) an organic solvent-soluble polymeric compound having a sulfonic acid group or a sulfonic acid salt group in its side chain and (3b) a substituted or unsubstituted dipicolinic acid or a salt thereof, the total amount of (3a) and (3b) components being about 1 to about 100% by weight, based on the weight of the diazo resin.

Abstract: A method of replenishing a developer during the development of photosensitive plates in a conveyor-type automatic developing machine connected to a replenishing device in which the dissolution of the photosensitive layer in the non-image area of a photosensitive plate is measured with a sensor. The sensor is positioned at a certain point in the developing zone of the machine, and, when the measured dissolution reaches a certain level, the replenishing device is automatically actuated to supply a predetermined amount of replenisher to the developer.