Abstract: A method and composition for developing a relief image formed by exposing a portion of a photopolymerizable layer to actinic radiation and removing the portion of the photopolymerizable layer not exposed to actinic radiation by washing the unexposed portion with a developer composition comprising a monoterpene, N-methylpyrrolidone and, optionally, an aromatic alcohol. A nonionic surfactant can also be included in the developer composition.

Abstract: The remover solution of the invention comprises (A) from 35 to 80% by weight of an alcoholic solvent such as ethylene glycol monoethyl ether, (B) from 10 to 40% by weight of an organic solvent which is a halogenated hydrocarbon solvent, e.g., 1,2-dichlorobenzene and methylene chloride, an ether solvent, e.g., tetrahydrofuran, or an aromatic solvent, e.g., benzene and xylene, and (C) from 0.1 to 25% by weight of a quaternay ammonium compound such as tetramethyl ammonium hydroxide and trimethyl hydroxyethyl ammonium hydroxide. Different from conventional remover solutions which only can swell cured photoresist compositions, the inventive remover solution has a power to completely dissolve a cured photoresist layer to give a quite satisfactory result in the removing works of patterned photoresist layers in the manufacture of semiconductor devices.

Abstract: In a process for treating a radiation sensitive member which includes image-wise exposure to radiation, development and burning-in of the member, after the development and prior to the burning-in, an aqueous solution including ethyl hexyl sulphate is applied to the member.

Abstract: A new liquid cleaner composition is provided for the mild and gentle removal of polymeric materials from sufaces without leaving any residues. The said new cleaner composition is an emulsion of the water-in-oil type comprising an aqueous phase finely dispersed in a continuous phase selected from the group consisting of nonflammable, fire-retardant, high-boiling, and fire-retardant and high-boiling organic phases, the volume ratio of the finely dispersed aqueous phase to the continuous organic phase being in the range of from 90:10 to 10:90. The new liquid cleaner composition can contain alcohols, surface-active agents and further useful additives. The new liquid cleaner composition is most preferably used in the process for preparing photopolymerized flexographic relief printing plates as the developer for washing out the non-irradiated and thus non-photopolymerized areas of the imagewise irradiated relief-forming recording layers of the said flexographic relief printing plates.

Abstract: Negative-acting photohardenable compositions are useful in flexographic printing plate manufacture without the use of solvent development. Unhardened composition is softened and absorbed by an absorbent sheet. Absorbed composition can be removed from the sheet and recycled.

Abstract: A developer composition for presensitized plates for use in making lithographic printing plates comprises water, an alkali silicate and at least one compound having at least one aryl group, at least one oxyalkylene group and at least one sulfate ester group or sulfonic acid group. The composition is excellent in developing stability and processability. It is less foamable and seldom generates deposits even when it is deteriorated. Moreover, the composition makes it possible to develop both positive- and negative-working PS plates.

Abstract: A resist exposed to patterned radiation at 193 nm forms a highly crosslinked barrier layer in the exposed regions of the resist surface. The complementary surface regions are silylated in a silicon-containing reagent, and the exposed regions are readily removed by a oxygen RIE plasma. The laser exposure is a reciprocal process allowing precise control. Pattern definition is enhanced by limiting the exposure and the silylation to the surface of the resist.

Abstract: A continuous process for the manufacture of photopolymer plates having a precise and constant thickness in which the components of the photopolymer layer are melted in a screw extruder, the melt is conveyed to the sheet die by means of a gear pump and then into a roll gap of a calender, wherein the melt leaving the sheet die does not form a rotating bead in the calender gap downstream therefrom. The photopolymer plates prepared in this manner have high homogeneity of the components of the photopolymerizable mixture, have a highly precise and constant thickness, are transparent, do not tend to form specks and guarantee a long shelf life.

Abstract: In a novel process for the production of a flexographic relief printing plate from a photosensitive recording element which containsA) a dimensionally stable substrate andB) at least one photopolymerizable recording layer havingb.sub.1) at least one elastomeric polymer as a binder,b.sub.2) at least one photopolymerizable monomer which is compatible with the binder (b.sub.1) andb.sub.3) at least one photopolymerization initiator,by(1) imagewise exposure of the photopolymerizable recording layer (B) to actinic light and(2) washout (development) of the unexposed and therefore nonphotopolymerized parts of the imagewise exposed recording layer (B) with an organic developer with formation of a relief layer,the organic developer used contains, based on its total amount, from 10% to 95% by volume of at least one mineral oil fraction from which aromatics have been removed and which has a boiling range of 150.degree. to 260.degree. C. and a flashpoint above 45.degree. C.

Abstract: A developer composition comprises an aqueous alkaline solution which contains at least one alkali-soluble mercapto compound and/or thioether compound. The developer composition is excellent in developing properties and provides lithographic printing plates which do not cause background contamination of non-image areas during printing, when it is used in developing PS plates. It can be stored for a long time. The developer composition further makes it possible to develop both negative and positive working PS plates if its pH value is not less than 12.

Abstract: Compositions and methods for developing quinone diazide positive-working photoresists. The compositions consist essentially of an aqueous solution of a tetraalkylammonium hydroxide and an adjunct having a structure selected from: ##STR1## wherein n is 0 or 1; m is 1 or 2; and each R.sup.1 and R.sup.2 is independently selected from hydrogen, methyl, or ethyl, but in Structure I the two R.sup.2 's are not both ethyl. The methods involve use of this composition to develop the indicated photoresists. The addition of an adjunct of the indicated type prevents the formation of irregular deposits on the edges of unexposed portions of the photoresist lines when the photoresist is developed. Selection of these adjuncts also increases the uniformity of line widths of photoresist lines developed according to the present invention, and increases the process latitude of the developer.

Abstract: A relief printing plate whose photopolymerized relief layer has a non-tacky surface is produced by (1) imagewise exposure of a photopolymerizable relief-forming recording layer which contains one or more polymeric binders containing acid groups, (2) washing out (development) of the unexposed and therefore non-photopolymerized parts of the imagewise exposed relief-forming recording layer with a developer and (3) aftertreatment of the resulting photopolymerized relief layer with a basic aftertreatment solution.

Abstract: A method of developing a waterless light-sensitive lithographic printing plate having a support and, provided thereon, a light-sensitive layer comprising a diazo resin and a silicone gum layer with a developer is disclosed. The developer comprises an organic carboxylic acid or salt thereof, water, and at least one of a sulfite and a surfactant.

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 flexographic printing plate which is resistant to ozone cracking and where the flexible recording layer has an anisotropy factor AF of <1.5 is produced from a photosensitive mixture consisting of A) one or more elastomeric binders,B) a mixture ofB1) from 5 to 20% by weight of one or more photopolymerizable organic compounds which are compatible with (A) and contain two or more olefinic double bonds andB2) from 1 to 15% by weight of one or more monoolefinically unsaturated organic compounds which are compatible with (A) and whose homopolymer has a glass transition temperature which is below room temperature,C) from 0.1 to 10% by weight of one or more photoinitiators andD) from 0 to 27% by weight of conventional assistants and additives,the anisotropy factor AF of the flexible recording layer being defined as the ratio of the moduli of elasticity at 100% elongation of strips measuring 2.times.

Abstract: There are disclosed an aqueous alkaline developer for light-sensitive lithographic printing plate commonly processing a negative-type light-sensitive lithographic printing plate having a light-sensitive layer containing a diazo compound and a positive-type light-sensitive lithographic printing plate having a light-sensitive layer containing an o-quinonediazide compound, which comprises containing an alkali agent, 0.1 to 10% by weight of a water-soluble reducing agent, a sodium, potassium or ammonium salt of an organic carboxylic acid, and a non-ionic or cationic surfactant, and having a pH in the range of 12.5 to 13.5, and also a developer composition for light-sensitive material, which comprises an aqueous solution containing a compound represented by the formula (I) shown below: ##STR1## wherein R.sub.1 represents an alkyl group or an alkoxy group each having 2 to 5 carbon atoms, or a hydroxyalkyl group having 2 to 5 carbon atoms; and R.sub.

Abstract: Compositions and methods for developing quinone diazide positive-working photoresists. The compositions consist essentially of an aqueous solution of a tetraalkylammonium hydroxide and an adjunct having a structure selected from: ##STR1## wherein n is 0 or 1; m is 1 or 2; and each R.sup.1 and R.sup.2 is independently selected from hydrogen, methyl, or ethyl, but in Structure I the two R.sup.2 's are not both ethyl. The methods involve use of this composition to develop the indicated photoresists. The addition of an adjunct of the indicated type prevents the formation of irregular deposits on the edges of unexposed portions of the photoresist lines when the photoresist is developed. Selection of these adjuncts also increases the uniformity of line widths of photoresist lines developed according to the present invention, and increases the process latitude of the developer.

Abstract: Disclosed are novel dry, non-tacky photopolymer precursors or isocyanate-free urethane oligomers which are the reaction products of heat reactive phenolic resins and unsaturated monoisocyanates, e.g. a methylol containing resole and isocyantoethyl methacrylate. The reaction product combined with a haloalkyl triazine photosensitizer and an inert organic solvent provides an excellent coating for a variety of substrates used in the printing and publishing industry, e.g. grained, anodized aluminum lithoplates. The presensitized lithographic plates can be used in aqueous alkaline based development processes and exhibit an increased resistance to solvent attack during the development and printing processes.

Abstract: A process for substantially improving dimensional stability in photopolymeric flexographic relief printing plates wherein the surface of the printing plate is post-exposed to a high intensity radiation source having broad wavelength emission in the 200 to 700 nm range.

Abstract: A light-sensitive composition for the preparation of printing plates is described, which contains a water-insoluble binder which is soluble in aqueous-alkaline solutions; a light-sensitive component which is an o- or p-quinone diazide, a diazonium salt polycondensation product or a mixture ofa) a compound which eliminates an acid on exposure to light andb) a compound having at least one C--O--C group which can be split by acid; and a thermo-crosslinking compound which is a cyclical acid amide of the general formula: ##STR1## wherein R denotes a hydrogen atom or an alkyl group. The printing plates can be baked at lower temperatures than plates without a crosslinking agent, but nevertheless have a long shelf life.

Abstract: A developer composition which comprises in admixture:a. from about 0.1% to about 10% of sodium, potassium or lithium benzoate; andb. from about 0.1% to about 2.5% of sodium or potassium tetraborate; andc. from about 0.1% to about 10.0% of sodium or potassium citrate; andd. from about 0.1% to about 10.0% of sodium or potassium octyl sulfate; ande. from about 0.1% to about 20.0% of sodium or potassium salicylate; andf. from about 0.2% to about 10.0% of a solvent composition, which solvent composition consists essentially of one or more compounds selected from the group consisting of benzyl alcohol and phenoxyethanol; andg. an optional antifoam component in an amount of from about 0.005% to about 0.075%; andh. sufficient water to formulate an effective developer;wherein said percentages are based on the weight of the developer composition.

Abstract: A method for processing an electrophotographic lithographic printing precursor comprising a photoconductive layer provided on a conductive substrate, the photoconductive layer having a toner image formed thereon by an electrophotographic process, comprising measuring electronically the area of the nonimage area to be processed, treating the precursor with a processing fluid from a processing fluid reservoir to remove the nonimage area of the photoconductive layer, and adding replenisher by automatic means in accordance with the area of the measured nonimage area.

Abstract: The process of developing an image-wise exposed positive-working photoresist-coated substrate comprising the steps of:(1) coating said substrate with a radiation-sensitive composition useful as a photoresist; said composition comprising an admixture of:(a) at least one alkali-soluble binder resin;(b) at least one photoactive compound; and(c) a sufficient amount of at least one solvent to dissolve (a) and (b); subject to the proviso that said photoactive compound (b) is a mixture of fully and partially esterified o-naphthoquinone diazide esters of a polyhydroxyaromatic compound having at least four hydroxyl groups capable of being esterified by said diazide groups.

Abstract: The invention is a method for preparing a photographic element which comprises imagewise exposing a photographic element, and removing the non-image areas thereof by contacting said element with a composition consisting essentially of in admixture:a) from at least about 5% to about 30% by weight of the developer of benzyl alcohol; andb) from about 1% to about 20% by weight of the developer of one of more compound selected from the group consisting of sodium xylene sulfonate and sodium cumene sulfonate; andc) from about 5% to about 40% by weight of the developer of potassium toluene sulfonate; andd) water in sufficient amount of formulate effective developer for imagewise exposed photographic elements.

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: The invention provides a process for making a lithographic printing plate utilizing silver image as ink receptive area which is markedly improved especially in printing endurance. The process comprises subjecting a light-sensitive material for lithographic printing plate to imagewise exposure and development and then treating the resulting silver image with an oxidizing agent and a monocyclic compound comprising a nitrogen-containing single ring and having substituents on at least two atoms constituting said ring, said substituents being capable of reacting with silver ion. The oxidizing agent and the monocyclic compound may be contained separately or together in a stop solution, a fixing solution, an etch solution or damping solution or especially prepared solution.

Abstract: A light-sensitive composition comprising an admixture of:(a) at least one alkali-soluble binder resin;(b) at least one photoactive compound;(c) a sufficient amount of a solvent mixture comprising ehtyl lactate and ethyl 3-ethoxy propionate to dissolve (a) and (b);wherein the amount of said binder resin is from about 60% to 95% by weight, the amount of said photoactive compound is from about 5% to about 40% by weight, both based on the total solids content of said light-sensitive composition, and wherein the weight ratio of ethyl lactate to ethyl 3-ethoxy propionate is from about 30:70 to 80:20.

Abstract: A single-phase homogeneous composition for the protection of lithographic printing plate surfaces is provided which comprises an aqueous solution of(a) a hydrophilic film forming compound which is essentially cold-water soluble,(b) a hydrophilizing agent(c) a wet film forming agent,(d) a nonionic surfactant,(e) a greasing agent,and(f) one or more desensitizing salts.

Abstract: The present invention relates to an improved process for preparing a photopolymerized flexographic relief printing plate or a photoresist from a photosensitive element comprising a photopolymerizable layer consisting essentially of(A) at least one polymer as the binder,(B) at least one photopolymerizable monomer compatible with said binder (A) and(C) one photoinitiator, by(i) imagewise exposing said photopolymerizable layer of said element to actinic light and(ii) washing out the unexposed, non-photopolymerized parts of said layer with a developer, thereby obtaining a photopolymerized flexographic relief printing plate or a photoresist.The improvement of said process comprises: washing out the non-photopolymerized parts of the irradiated photopolymerizable layer with the developer which consists essentially of at least one hydrogenated petroleum fraction having a flashpoint above 45.degree. C. and a boiling range of from 160.degree. to 220.degree. C.

Abstract: A developer composition which comprises an aromatic compound having hydroxyl groups at the 1- and 3-positions thereof and free of any electron attractive group or a salt thereof, an alkaline agent and water. The developer composition can effectively be used, as a developer, in a method for making lithographic printing plates which comprises the steps of: exposing, to light, a presensitized plate for use in making a lithographic printing plate provided with a water-insoluble image-forming layer formed on a substrate and developing the plate to remove non-image portions. Lithographic printing plates manufactured according to the method provide printed matter free of background contamination. If the pH value of the developer is controlled to not less than 12, both positive-working and negative-working presensitized plate can be treated therewith.

Abstract: A process for producing an ozone-resistant flexographic printing form based on a photopolymerizable elastomeric mixture is described, which comprises applying to a developed and optionally post-treated flexographic printing form a treatment reagent containing as the essential constituent at least one polyglycol ether of the general formula I ##STR1## in which R.sub.1 and R.sub.2 are alkyl, especially (C.sub.1 -C.sub.3)-alkyl,R.sub.3 is hydrogen or alkyl, especially (C.sub.1 -C.sub.3)-alkyl,A, B, C can be identical or different and areand D oxa-n- or -iso-alkylene, especially oxa-n- or -iso-(C.sub.1 -C.sub.5)-alkylene and1+m+n+o is 3 to 40.

Abstract: The invention relates to a method of forming of a patterned photopolymer coating on a printing roller in which a photopolymer coating, present on said roller, and covered by a light-sensitive intermediate layer is exposed in a first stage to form an image of opaque and translucent parts in said intermediate layer.Subsequently the photopolymer layer is exposed via the image formed in the intermediate layer, after which the photopolymer layer is developed.Between abovementioned exposures, in case of a relatively thick, flexible, photopolymer, a period is waited to ensure that depressed parts of the photopolymer layer have returned to their original state.The invention also relates to a printing roller thus obtained.

Abstract: The peeling solution for photo- or electron beam-sensitive resin according to the present invention consists of an aqueous solution consisting of hydrogen peroxide and a compound represented by the general formula (I) ##STR1## wherein R.sub.1 is H or an alkyl group of 1-2 carbon atoms, R.sub.2 is H or an alkyl group of 1-3 carbon atoms, and R.sub.3 is H or an alkyl group of 1-3 carbon atoms.

Abstract: An aqueous developing composition including(a) a nontoxic developing vehicle which is a non-solvent for any of the components of the lithographic plate;(b) a first surfactant comprising a sodium, lithium or potassium salt of xylene sulfonic acid;(c) a second surfactant comprising a sodium, lithium or potassium salt of toluene, ethyl benzene, cumene or mesitylene sulfonic acid,(d) a third surfactant comprising a sodium, lithium or potassium salt of an alkyl benzene sulfonic acid, the alkyl group containing at least 10 carbon atoms or an alkyl naphthalene sulfonic acid, the alkyl group containing from 1 to 4 carbon atoms;(e) a cold water soluble film forming agent;(f) an alkanol amine desensitizing agent; and(g) an acid to control the pH of the developing composition.

Abstract: The alkali blue dry toner comprises 60 to 98 weight percent alkali blue pigment particles, 1 to 20 weight percent of di- and tri-decyl phosphate esters of free acids, and 1-20 weight percent of dehydroabietyl amine. The toner exhibits a high strength and soft texture in comparison with prior art pigment compositions made from similar ingredients.

Abstract: A composition useful for the protection of actinic light-exposed presensitized lithographic printing plates. The composition contains an effective amount of the di-potassium salt of hydroxyethylidene diphosphonic acid dissolved in water. The composition is applied to the surface of the revealed substrate of the plates after they have been developed but before treatment to heat, to prevent surface contamination from the heat treatment.

Abstract: A method for coating a printing screen with a sealer to avoid pinholing and damage to the screen from extended use. The method includes coating the inside of the screen with a photo emulsion, exposing the emulsion to the image to be printed, and etching out the exposed screen. Next, applying to the outside surface of the etched out screen a sheet of easy removable pressure sensitive vinyl, and next treating the etched out screen with a sealing composition, which provides a protective barrier for that part of the screen that prevents ink from printing. The sealing composition is advantageously a two part epoxy resin or an air-moisture curing urethane polymer.

Abstract: Negative-acting flexographic printing plates display enhanced performance when backside irradiated with ionizing radiation instead of longer wavelength ultraviolet radiation. A better defined floor and more readily controlled floor is produced on the final printing plate.

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 system for the preparation of dot etched lithographic films, consisting essentially of a light sensitive silver halide material for tanning development and an etching solution, in which system the light sensitive material of various layers contains at least one colorant, e.g., pigment or dye with acid groups, which is stable in the processing baths and forms with bases salts soluble in organic solvents, and the etching solution contains a base that ionizes the colorant, and a solvent for the resulting ion pair.

Abstract: The invention provides a mixture suitable for treating a photographic composition which comprises from about 1 to about 10 parts by weight of a propylene glycol alkyl ether and from about 1 to about 10 parts by weight of a propylene glycol alkyl ether acetate.

Abstract: A burn-in gumming composition for irradiated and developed offset printing plates comprises water and a water-soluble polymer or copolymer for protecting the plate surface during the burning-in step and during long-term storage. The polymer or copolymer used contains sulfonic acid groups and/or alkali metal sulfonate or ammonium sulfonate groups.

Abstract: The invention relates to the use of a thermal transfer printer and of an ink ribbon containing a pigment or dye that absorbs light in the range from 350 to 450 nm for the direct production of a photomask from an electronically coded sources of information on a metal plate (PS plate) coated with a positively working photopolymer which is sensitive to light in the range from 350 to 450 nm, and, as surface layer, with a polymer which is soluble in alkaline solution and is permeable to light in the range from 350 to 450 nm, such that the image produced by the thermal transfer printer on the PS plate is used direct as photomask.

Abstract: A composition capable of removing the non-image areas of an imagewise exposed photographic element, consisting essentially of in admixture:(a) from at least about 5% to about 30% by weight benzyl alcohol; and(b) from about 1% to about 20% by weight of one or more compounds selected from the group consisting of sodium xylene sulfonate and sodium cumene sulfonate; and(c) from about 5% to about 40% by weight potassium toluene sulfonate; and(d) water.

Abstract: A light-sensitive composition comprises a diazo resin, a polymeric binder, and at least one compound having at least one structural unit selected from the group consisting of ureido bond, thioureido bond, urethane bond and thiourethane bond. The light-sensitive composition can suitably be used for preparing a presensitized plate for use in making lithographic printing plates and is excellent in developability with an aqueous alkaline developer.

Abstract: An aqueous damping solution for the offset printing process contains a hydrolysis product of a compound of the general formula ##STR1## wherein R.sup.1 and R.sup.2 are identical or different and are each hydrogen, alkyl of 1 to 9 carbon atoms or aryl of 6 to 12 carbon atoms, or a condensate of this hydrolysis product.

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 method of processing an imagewise exposed pre-sensitize lithographic printing plate which entails uniformly applying a desired amount of developer, that has not been substantially used to the surface of the printing plate by a developer supply member comprised of two plates and having a slit at the lowermost portion thereof, and then transferring the plate containing the developer to a developer storage tank, immersing the plate in the developer storage tank, and removing the developer from the plate.

Abstract: A developing method for printing plates employing waterless offset processes is disclosed. The plates comprise a support coated with a photosensitive layer based on a diazonium salt polycondensation product and a super-imposed ink-repellent, crosslinked silicone elastomer layer, whereby said developer is characterized in that it contains a predominant proportion of compounds of the general formula R--(O--CH.sub.2 --CH.sub.2 --).sub.n --O--R, where R denotes C.sub.m H.sub.2m+1, n denotes an integer from 1 to 25 and m denotes an integer from 1 to 5. The present invention is particularly suitable for developing printing plates where the photosensitive layer comprises a diazonium salt polycondensation product comprising recurrent A--N.sub.