US3597201A - Positive-working presensitized planographic printing plate - Google Patents

Positive-working presensitized planographic printing plate Download PDF

Info

Publication number
US3597201A
US3597201A US635687A US3597201DA US3597201A US 3597201 A US3597201 A US 3597201A US 635687 A US635687 A US 635687A US 3597201D A US3597201D A US 3597201DA US 3597201 A US3597201 A US 3597201A
Authority
US
United States
Prior art keywords
silver
emulsion
positive
gelatin
photographic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US635687A
Other languages
English (en)
Inventor
Dorothy J Beavers
William B Kendall
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Kodak Co
Original Assignee
Eastman Kodak Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Application granted granted Critical
Publication of US3597201A publication Critical patent/US3597201A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/06—Silver salts
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/485—Direct positive emulsions
    • G03C1/48515—Direct positive emulsions prefogged
    • G03C1/48523—Direct positive emulsions prefogged characterised by the desensitiser

Definitions

  • Positive-working presensitized printing plates comprising a support, a hardened gelatin photographic directpositive covered grain emulsion and a polyhydroxybenzene developing agent.
  • a halogen-accepting compound and a sulfonated compound may be added to the emulsion to increase sensitivity.
  • This invention relates to novel photographic elements, their preparation and use. In one of its aspects, this invention relates to novel positive-acting presensitized printing plates. In another of its aspects, the invention relates to using such plates in lithography without etching or washing off the hardened areas.
  • a positive-working presensitized printing plate comprising a support and a hardened gelatin photographic emulsion layer containing a particular type of reversal or direct-positive emulsion, as hereinafter described, in combination with a polyhydroxybenzene developing agent which oxidizes in the development reaction and renders gelatin oleophilic in unexposed areas, i.e., it forms an oleophilic image (ink-receptive image).
  • a process employing a positive-working presensitized printing plate comprising a hardened gelatin direct-positive photographic emulsion layer, as described hereinafter, and processing this plate after exposure with a polyhydroxybenzene developing agent which oxidizes in the presence of the gelatin in the silver halide emulsion to render gelatin in the unexposed areas oleophilic, i.e., it forms an oleophilic image (ink-receptive image).
  • a significant feature of this invention resides in the fact that only certain combinations of photographic directpositive emulsions and polyhydroxylbenzene developing agents can be employed in its practice.
  • positive-working presensitized printing plates employing photographic directpositive emulsions of a different type from that employed in the practice of this invention have a very low photographic speed and require very long exposures.
  • a polyhydroxybenzene developing agent which does not oxidize upon development to render the gelatin oleophilic in an unexposed area cannot be employed in the practice of this invention.
  • the silver halide emulsions used in the practice of this invention are photographic reversal or direct-positive emulsions containing grains comprising a central core of a water insoluble silver salt containing centers which promote the deposition of photolytic silver and an outer shell or covering for such core of a fogged or spontaneously developable water-insoluble silver salt.
  • the fogged shell of such grains develops to silver without exposure.
  • the direct-positive emulsion has adsorbed to the fogged grains a halogenaccepting compound having an anodic polarographic halfwave potential less than 0.85 and a cathodic polarographic halfwave potential which is more negative than -l.0.
  • a halogenaccepting compound having an anodic polarographic halfwave potential less than 0.85 and a cathodic polarographic halfwave potential which is more negative than -l.0.
  • certain high molecular weight organic compounds particularly sulfonated compounds as described hereinafter, can be used in combination with halogen-accepting compounds to effect an even greater increase in photographic speed or sensitivity.
  • the core emulsion is first chemically or physically treated by methods previously described in the prior art to produce centers which promote the deposition of photolytic silver, i.e., latent image nucleating centers.
  • centers can be obtained by various technuiques as described herein. Chemical sensitization techniques of the type described by Antoine Hautot and Henri Saubenier in Science et Industries Photographiques, Volume XXVIII, January 1957, pages 57-65, are particularly useful.
  • Such chemical sensitization includes three major classes, namely, gold or noble metal sensitization, sulfur sensitization, such as by a labile sulfur compound, and reduction sensitization, i.e., treatment of the silver halide with a strong reducing agent which introduces small specks of metallic silver into the silver salt crystal or grain.
  • the core emulsion When the core emulsion is chemically sensitized, it is preferably sensitized so that when examined according to normal photographic testing techniques by coating a test portion of the emulsion on a transparent support, exposing to a light intensity scale for a fixed time between 0.01 and 1 second and development for 6 minutes at 68 F. in Developer A, as hereinafter defined, it has sensitivity greater than the sensitivity of an identical test portion of the same emulsion (measured at a density of 0.1 above fog), which has been exposed in the same way, bleached 5 minutes in an aqueous 0.3 percent potassium ferricyanide solution at 65 F., and developed for 5 minutes at 65 F., in Developer B, as hereinafter defined. Developer A is the usual type of surface image developer and Developer B is an internal developer having high silver halide solvent activity.
  • DEVELOPER B Grams N-methyl-p-aminophenolsulfate 2.0 Sodium sulfite, desiccated 90. Hydroquinone 8.0 Sodium carbonate, monohydrate 52.5 Potassium bromide 5.0 Sodium thiosulfate 10.0
  • the core emulsions can be chemically sensitized by any method suitable for this purpose.
  • the core emulsions can be digested with naturally active gelatin, or sulfur compounds can be added, such as those described in Sheppard US. Patent 1,574,944 issued Mar. 2, 1926; Sheppard et al. U.S. Patent 1,623,499 issued Apr.
  • the core emulsions can also be chemically sensitized with gold salts as described in Waller et al. US. Pat. 2,399,083 issued Apr. 23, 1946, and Damschroder et al. US. Pat. 2,642,361 issued June 16, 1953.
  • Suitable com pounds are potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride and 2- aurosulfobenzothiazole methochloride.
  • the core emulsions can also be chemically sensitized with reducing agents, such as stannous salts (Carroll US. Pat. 2,487,850 issued Nov. 15, 1949), polyamines, such as diethylene triarnine (Lowe and Jones US. Pat. 2,518,- 698 issued Aug. 15, 1950), polyamines, such as spermine (Lowe and Allen US. Pat. 2,521,925, issued Sept. 12, 1950), or bis(betaaminoethyl)sulfide and its water-soluble salts (Lowe and Jones US. Pat. 2,521,926 issued Sept. 12, 1950).
  • reducing agents such as stannous salts (Carroll US. Pat. 2,487,850 issued Nov. 15, 1949), polyamines, such as diethylene triarnine (Lowe and Jones US. Pat. 2,518,- 698 issued Aug. 15, 1950), polyamines, such as spermine (Lowe and Allen US. Pat. 2,521,925, issued Sept. 12, 1950), or bis(bet
  • the core emulsions can also be treated during or after the formation of the silver salt With salts of polyvalent metals such as bismuth, the noble metals and/or the metals of Group VIII of the Periodic Table, such as ruthenium, rhodium, palladium, iridium, osmium, platinum and the like.
  • Representative compounds are ammonium chloropalladate, potassium chloroplatinate, sodium chloropalladite and the like.
  • the core emulsions can also be subjected to fogging by exposure to light either to low or high intensity light, to produce centers which promote the deposition of photolytic silver prior to forming the shell thereon.
  • the emulsions employed in practicing this invention can also contain spectral sensitizers such as the cyanines, merocyanines, complex (trinuclear) cyanines, complex (trinuclear) merocyanines, styryls and hemicyanines.
  • spectral sensitizers such as the cyanines, merocyanines, complex (trinuclear) cyanines, complex (trinuclear) merocyanines, styryls and hemicyanines.
  • Particularly good spectral sensitizers which can be used are the merocyanines disclosed in Brooker et al. US. Pats. 2,493,747 and 2,493,748 issued Jan. 10, 1950.
  • the shell of the grains comprising the emulsions used in practicing this invention is prepared by precipitating over the core grains a light-sensitive water-insoluble silver salt that can be fogged and which fog is removable by bleaching.
  • the shell is of sufficient thickness to prevent access of the developer used in processing the emulsions of the invention to the core.
  • the silver salt shell is surface fogged to make it developable to metallic silver with conventional surface image developing compositions. Substantially all of the silver halide grains in an emulsion are fogged prior to exposure and/or processing, i.e., such emulsions are uniformly fogged.
  • Such fogging can be effected by chemically sensitizing to fog with the sensitizing agents described for chemically sensitizing the core emulsion, high intensity light and like fogging means well known to those skilled in the art.
  • the shell is fogged, for example, reduction fogged with a reducing agent such as stannous chloride. Fogging by means of a reduction sensitizer, a noble metal salt such as gold salt plus a reduction sensitizer, high pH and low pAg silver halide precipitating conditions, and the like can be suitably utilized.
  • the core of the grains in the emulsion layer is a coarse grained silver salt and silver halide from a finer grained silver salt is deposited thereon by Ostwald ripening to form the shell.
  • coarse grained silver salts can be used to form a shell over a finer grained core when the shell-forming silver salt is more water-soluble than the core silver salt.
  • the silver halide shell is formed immediately after formation of the core without interrupting the precipitation.
  • emulsions used in the presensitized plates of this invention which can be termed covered grain emulsions, contain a population of grains which are substantially uniform in grain-size distribution, as contrasted with emulsion blends with contain at least two types of grains, which are separate and distinct in their physical, and frequently, photographic properties.
  • the grain size of these covered grain emulsions widely varies, typical emulsions having an average grain size of about 0.05 to 10 microns in diameter.
  • Such emulsions are generally coated at silver coverages in the range of about 10 to about 400 milligrams silver per square foot, preferably about 20 to 100 milligrams silver per square foot, and when exposed to an image and thereafter developed in a conventional surface image developer having low silver salt solvent action, form a reversal or direct-positive silver image.
  • the unexposed grains develop without substantial reduction of the imagewise exposed grains.
  • the silver halide grains employed in the practice of this invention are fogged sufiiciently to give a density of at least 0.5 when developed without exposure for five minutes in Developer A, described hereinbefore, when a directpositive emulsion layer containing such grains is coated at a coverage of about 50 to about 500 milligrams of silver per square foot of support.
  • halogen-accepting compounds employed in practicing the one embodiment of this invention referred to above are adsorbed to the fogged silver halide grains.
  • the halogen acceptors which give particularly good results in the practice of this invention can be characterized in terms of their polarographic halfwave potentials, i.e., their oxidation reduction potentials determined by polarography.
  • Cathodic measurements can be made with a 1X 1O molar solution of the halogen acceptor in a solvent, for example, methanol which is 0.05 molar in lithium chloride using a dropping mercury electrode with the polarographic halfwave potential of the most positive cathodic wa ve being designated E
  • Anodic measurements can be made with 1X10 molar aqueous solvent solution, for example, methanolic solutions of the halogen acceptor which are 0.05 molar in sodium acetate and 0.005 molar in acetic acid using a carbon paste or pyrolytic graphite electrode, with the voltommetric half peak potential for the most negative anodic response being designated E
  • the reference electrode can be an aqueous silver-silver chloride (saturated potassium chloride) electrode at 20 C.
  • Electrochemical measurements of this type are known in the art and are described in New Instrumental Methods in Electrochemistry, by Delahay, Interscience Publishers, New York, N.Y., 1954; Polarography, by Kolthofi and Lingane, 2nd Edition, Interscience Publishers, New York, N.Y., 1952; Analytical Chemistry, 36, 2426 (1964) by Elving; and Analytical Chemistry, 30, 1576 (1958) by Adams.
  • halogen accep tors Compounds which can be employed as halogen accep tors in the practice of this invention include organic or inorganic compounds having an anodic polarographic halfwave potential E less than 0.85 and a cathodic polarographic potential E which is more negative than 1.0.
  • a preferred class of halogen-accepting compounds is characterized by an anodic halfwave potential which is less than 0.62 and a cathodic halfwave potential which is more negative than -1.3.
  • a preferred class of halogen acceptors that can be used in the practice of this invention comprises the spectral sensitizing merocyanine dyes having the formula:
  • A represents the atoms necessary to complete an acid heterocyclic nucleus, e.g., rhodanine, 2-thiohydant0in and the like
  • B represents the atoms necessary to com.- plete a basic nitrogen containing heterocyclic nucleus, e.g., benzothiazole, naphthothiazole, benzoxazole and the like
  • each L represents a methine linkage, e.g.,
  • n is an integer from 0 to 2, i.e., 0, 1 or 2.
  • Specific examples of merocyanine dyes falling within the above formula include:
  • halogen-accepting compounds employed in practicing the one embodiment of this invention referred to above can be used in widely varying concentrations.
  • the halogen-accepting compounds are generally employed at concentrations in the range of about 100 rmilligrams to about 1.0 gram, preferably about 150 to about 600 milligrams per mole of silver halide.
  • the halogen accepting compounds described herein can be employed in combination with certain types of high molecular weight organic compounds to achieve an even greater increase in the photographic speed of direct-positive emulsions.
  • These compounds are sulfonated and comprise polynuclear aromatic compounds containing at least one sulfo group.
  • polynuclear aromatic as used herein is intended to mean 2 or more benzene rings fused together (for example, as in naphthalene, pyrene, etc.), or at least 2 benzene rings or aromatic rings directly joined together (for example, as in diphenyl, terphenyl, quaterphenyl, etc.), or through an aliphatic linkage.
  • Such sulfonated derivatives can conveniently be represented by the following general formula:
  • R represents a polynuclear aromatic group as defined above and M represents a cation such as a hydrogen atom or a water-soluble cation salt group (e.g., sodium, potassium, ammonium, triethylammonium, triethanolammonium, pyridinium, etc.).
  • a cation such as a hydrogen atom or a water-soluble cation salt group (e.g., sodium, potassium, ammonium, triethylammonium, triethanolammonium, pyridinium, etc.).
  • Calcofiuor White-MR This is the trade name for a his (s-triazin-2-y1amino)stilbene-2,2-disulfonic acid, sodium salt.
  • Leucophor B This is the trede name for a bis(s-triazin- 2-ylamino)stilbene-2,2-disulfonic acid, sodium salt.
  • Chyrsene-6-sulfonic acid sodium salt.
  • sulfonated derivatives may be used in any concentration effective for the intended purpose.
  • Good re sults are generally obtained by employing the compounds in concentrations in the range of about 0.02 to about 10 grams per mole of silver halide.
  • Silver halides are preferably utilized to prepare the core as well as the shell of the grains comprising the covered grain emulsions used in the practice of the invention.
  • Suitable silver halides include silver chloride, silver bromide, silver iodide, silver chlorobrornide, silver bromoiodide and siver chlorobromoiodide.
  • Other waterinsoluble silver salts for the core and/or shell include silver thiocyanate, silver phosphate, silver cyanide, silver carbonate and the like.
  • the ink-receptive areas of the printing plates on a background of hydrophilic material are obtained by alkaline activation of a silver salt, preferably silver halide, developing agent in the presence of a gelatin, silver salt emulsion layer.
  • a silver salt preferably silver halide
  • developing agent in the presence of a gelatin, silver salt emulsion layer.
  • the result is to form a silver image and oxidized developing agent in the region of development.
  • the element can then be inked in the developed areas with greasy printing ink and a positive print made therefrom in a lithographic press.
  • the gelatin in the emulsion layer can undergo additional hardening at the same time as development.
  • the hardening of the gelatin layer in the region of development is incidental to successful operation of the invention since some developing agents, such as catechol, hydroquinone and toluhydroquinone, which are known to be strong gelatin-tanning silver halide developing agents, are not useful in the sensitive elements of this invention because the oxidation products formed in the presence of the gelatin, silver salt emulsion layer do not form oleophilic images, Whereas other closely related silver salt developing agents such as chlorohydroquinone, are quite useful in the process of the invention.
  • some developing agents such as catechol, hydroquinone and toluhydroquinone, which are known to be strong gelatin-tanning silver halide developing agents
  • the developing agents employed in the practice of this invention include any developing agents which are capable of oxidation in the presence of the hardened gela tin present in the photographic emulsion layer to produce an image receptive to greasy printing ink, i.e., upon development, they render the gelatin in the unexposed areas oleophilic. They can be incorporated into one or more layers of the photographic element of this invention or they can be supplied from outside of the element, e.g., from solution or from a layer on a separate support.
  • the polyhydroxybenzene developing agents substituted with halogen, monocyclic aryl groups of the benzene series and alkyl groups of at least 2 and preferably from 2 to 6 carbon atoms have this property.
  • the 1,2-dihydroxybenzene developing agents substituted by halogen, monocyclic aryl of the benzene series and alkyl groups of at least 2 carbon atoms and preferably 2 to 6 carbon atoms are particularly useful in the process.
  • Developing agents possessing the necessary properties thus include certain polyhyroxybenzene developing agents such as pyrogallol and substituted polyhydroxybenzene developing agents, particularly dihydroxybenzenes substituted with, for example, halogen, alkyl groups of at least 2 and preferably from 2 to 6 carbon atoms and a monocyclic aryl group of the benzene series, e.g., o-chlorohydroquinone, o-bromohydroquinone, 4-phenyl catechol, 4-phenethyl catechol, 4-phenpropyl catechol, 4-t-butyl catechol, pyrogallol, 4- n-butylpyrogallol, nordihydroguiauretic acid, 4,.5
  • Esters of such developing agents e.g., formates and acetates of pyrogallol hydrolyze in alkaline solutions and can be used in the processes of the invention.
  • Such esters are intended to be included in the specification and claims where reference is made to polyhydroxybenzene developing agents.
  • an auxiliary developing agent such as monomethyl-p-aminophenol or a 3-pyrazolidone, which latter developing agents by themselves do not yield oleophilic images in the processes described, but which do appear to act synergistically with the polyhydroxybenzenes to t yield oleophilic images.
  • the developing agents are generally employed in the photographic elements at coverages of about 5 to about 200, preferably about to about 50 milligrams per square foot of support and are incorporated in a layer which is no farther from the support than the photographic emulsion layer, i.e., they are incorporated into the photographic emulsion layer or a layer between the emulsion layer and the support, e.g., an adjacent or contiguous layer.
  • these developing agents can be incorporated in a layer, e.g., a gelatin layer, on a separate support which is wetted with activator and brought into contact with the photographic emulsion layer during processing.
  • the silver salt emulsion layer should be substantially hardened in order to prevent the processed plate from adhering to printing blankets, papers, etc.
  • the emulsion should be as hard as a gelatin layer containing at least about 0.2 gram and preferably about 2 to grams of dry formaldehyde per pound of gelatin, i.e., it should have a melting point in water greater than 150 F. and preferably greater than 200 F.
  • gelatin can be the sole binding agent
  • various colloids can be used with gelatin as vehicles or binding agents in the photographic emulsion layers employed in the practice of this invention.
  • gelatin or a gelatin derivative which is primarily gelatin is used for at least a part, for example, at least 10%, by weight, of the binder in the photographic element.
  • Other binding agents that can be used with the gelatin include any of the hydrophilic colloids generally employed in the photographic field such as colloidal albumin, polysaccharides, cellulose derivatives, synthetic resins such as polyvinyl compounds, including polyvinyl alcohol derivatives, acrylamide polymers, and the like.
  • hydrophilic colloids In addition to the hydrophilic colloids,
  • the vehicle or binding agent can contain dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials. Suitable compounds of this type include Water-insoluble polymers of alkyl acrylates or methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, and the like.
  • the binding agent is generaly coated at a coverage in the range of about 50 to about 2000, preferably about 100 milligrams to about 1000 milligrams per square foot of support.
  • Typical flexible supports include those generally employed in printing plates, as exemplified by metals such as aluminum, paper, cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film, and related films or resinous materials and other related materials.
  • Supports such as paper which are partially acetylated or coated with an alpha-olefin polymer, particularly a polymer of an alpha-olefin containing 210 carbon atoms, as exemplified by polyethylene, polypropylene, ethylene-butene copolymers and the like, give good results.
  • the photographic elements of printing plates of this invention can include antihalation layers which are generally coated between a photographic emulsion layer and the support.
  • Suitable layers of this type include gelatin layers containing organic and inorganic pigments such as Napthol Red type pigments, colloidal carbon or silver, zinc oxide, titanium dioxide, iron oxide and the like, which can be dyed, if desired, with such dyes as the merocyanines and the like.
  • organic and inorganic pigments such as Napthol Red type pigments, colloidal carbon or silver, zinc oxide, titanium dioxide, iron oxide and the like, which can be dyed, if desired, with such dyes as the merocyanines and the like.
  • a dye and/or a pigment can be in the same layer with the polyhydroxybenzene developing agent when it is coated in a layer beneath the photographic emulsion layer.
  • Example l.A superior positive-working presensitized lithographic printing plate can be prepared using the covered grain emulsions described herein in combination with polyhydroxybenzene developing agents located in an adjacent layer beneath the photographic emulsion layer.
  • a gelatin silver chloride photographic emulsion is prepared simultaneously adding at C., over a period of about 20 minutes, 1000 milliliters of a 4 molar silver nitrate aqueous solution and 1000 milliliters of a 4 molar sodium chloride aqueous solution, to a Well-stirred aqueous solution of 1000 milliliters of 0.01 molar sodium chloride containing 40 grams of gelatin.
  • the shell of silver chloride is formed by adding to the core emulsion 500 milliliters of 40 molar silver nitrate aqueous solution and 500 milliliters of 4 molar silver chloride aqueous solution simultaneously over a period of 20 minutes. grams of gelatin, previously soaked in 340 milliliters of water, is stirred in and the emulsion cooled. During both additions of the silver nitrate and sodium chloride (i.e., to form both the core and the shell), the two solutions are added at approximately constant rates. Sufiicient silver chloride is formed in the shell to give a ratio of 4 moles of shell silver chloride to 1 mole of core silver chloride. The resulting covered grain emulsion is melted, the gelatin content increased to 160 grams per mole of silver chloride and water added to 4000 grams per mole of silver chloride.
  • thiourea dioxide Two milligrams of thiourea dioxide per mole are added to the emulsion at 40 C.
  • the emulsion is fogged by heating it to 55 C. and holding it for 40 minutes at this temperature. It is cooled immediately to 40 C.
  • the following additional additives are incorporated into one mole of the fogged emulsion: 100 grams gelatin, 200 milligrams of a thiazoline-rhodanine merocyanine green sensitizer, of the type described in Brooker et al. US. Patent 2,493,748 issued Jan. 10, 1950; 1 gram of a sulfonated triazinyl-stilbene of the type described in Formula II of McFall et al. US. Patent 2,933,390 issued Apr.
  • the emulsion is coated at a coverage of 72 milligrams of silver per square foot over a gelatin layer containing the developing agent 4-phenyl catechol.
  • the gelatin layer is prepared from a gelatin solution containing a dispersion of 4-phenyl catechol in tricresyl phosphate and is coated at 30 milligrams per square foot phenyl catechol and 0.58 gram per square foot gelatin on a polyethylene coated paper support.
  • the direct-positive photosensitive element obtained is exposed by projection to a line original in a conventional process camera. After seconds activation at 75 F. in an 8 percent potassium phosphate solution, the plate is stopped in a phoshoric acid bath. The plate is then printed on a lithographic press giving a positive lithographic print.
  • Example 2 The direct-positive photographic printing plates prepared according to this invention have much higher photographic speed than direct-positive plates previously described in the art.
  • the photographic direct-positive elements prepared according to this invention are considerably more sensitive than direct positive plates of the type described in Yackel et al. US. Pat. 3,146,104 issued Aug. 25, 1964.
  • a direct-positive photographic printing plate is prepared as described in Example 11 of U.S. Pat. 3,146,104 and exposed as described in Example 1 above.
  • the photographic element of Example 1 has more than ten times the sensitivity of the element prepared according to Example 11 of US. Pat. 3,146,104. In fact, this latter element does not have enough sensitivity to be exposed on conventional projection copying equipment and must be exposed on a contact printer.
  • Example 3 The printing plates disclosed herein exhibit several significant advantages over positive-working presensitized printing plates disclosed in the prior art.
  • a direct-positive element is prepared as described in Example 3 of Yackel et al. US. Pat. 3,146,104 issued Aug. 25, 1964. This element is exposed and printed as described in Example 1 above, This photographic element requires more than three times the 20 seconds used to process the element described in Example 1.
  • the photographic plates of this invention are of simple construction in comparison to that described in Example 3 of U8. Pat. 3,146,104 since they eliminate at least one layer.
  • Example 4 An emulsion is prepared as described in Example 1 except that the core emulsion is reduction sensitized into fog by adding an excess of silver nitrate and holding for 20 minutes at 70 C. at a pAg of 2.5 and a pH of 75. Following this treatment, the pH is adjusted to 5.5 and the pAg to 6.8. After the reduction sensitization, aqueous solutions of silver nitrate and potassium chloride are added simultaneously to the core emulsion over a period of 20 minutes at 70 C. to form a silver chloride shell over the reduction sensitized silver chloride core.
  • Suflicient silver chloride is formed in this shell to give a ratio of 4 moles of shell silver chloride to 1 mole of core silver chloride.
  • the emulsion is reduction sensitized to fog by adding 2 milligrams of thiourea dioxide per mole of slver halide and holding the resulting emulsion for 15 minutes at 55 C.
  • Example 1 The additional additives described in Example 1 are added and the emulsion is coated over a gelatin layer containing a polyhydroxybenzene developing agent as described in Example 1.
  • the photographic element When processed and printed on a lithographic printing press, as described in Example 1, the photographic element provides a direct-positive print of good quality.
  • Example 5 the developing agent can be incorporated into the photographic emulsion layer which gives a plate of very simple structure. Furthermore, the plate can contain an antihalation layer under the photographic emulsion layer. To illustrate these features, the procedure of Example 1 is repeated except that the photographic emulsion layer is coated at coverages per square foot of 72 milligrams silver, 15 milligrams of 4-phenyl catechol and 100 milligrams gelatin. The photographic emulsion layer is coated on a polyethylene coated paper support containing titanium dioxide and red pigments dispersed in the polyethylene for antihalation purposes.
  • Example 1 After exposure and processing, as in Example 1, the plate is printed on a conventional lithographic press to give a positive print.
  • Example 6 A gelatin layer containing a dispersion of 4-phenyl catechol dissolved in tri-o-cresyl phosphate is coated on conventional cellulose acetate film support at coverages of 30 milligrams of 4-phenyl catechol per square foot, 300 milligrams of tri-o-cresyl phosphate per square foot and 580 milligrams of gelatin per square foot.
  • the gelatin layer is overcoated with a fogged, directpositive silver chloride emulsion prepared using the procedure of Example 1 at coverages of 48 milligrams of silver per square foot and 96 milligrams of gelatin per square foot.
  • a gelatin antihalation layer containing 25 milligrams of gelatin per square foot and 15 milligrams of carbon per square foot is coated over the emulsion layer.
  • the direct-positive photosensitive element obtained is exposed through the base in a conventional process camera to a positive original. After 20 seconds activation at F. in an 8% potassium phosphate solution containing 0.1 gram of potassium bromide per liter, the plate is stopped in a phosphoric acid bath. The plate is then printed on a lithographic press to give a right reading positive lithographic print.
  • Example 7 A gelatin layer containing carbon black pigment in a dispersion of 4-phenyl catechol dissolved in tri-o-cresyl phosphate is coated on conventional polyethylene terephthalate film support (.004 inch thick). The layer is coated at coverages of 10 milligrams of carbon black, 30 milligrams of 4-phenyl catechol, 300 milligrams of tri-o-cresyl phosphate and 580 milligrams of gelatin per square foot of support. This layer is overcoated with a fogged, direct-positive silver chloride emulsion prepared according to the procedure of Example 1 and coated at coverages of 48 milligrams of silver and 96 milligrams of gelatin per square foot of support.
  • the direct-positive photosensitive element obtained is exposed, processed and printed as in Example 6 to give a right reading positive lithographic print.
  • Example 8 A gelatin layer containing carbon black pigment in a dispersion of 4-phenyl catechol dissolved in tri-o-cresyl phosphate is coated on conventional polyethylene terephthalate film support (.004 inch thick) having an antihalation backing layer with a density of 0.3.
  • the gelatin layer is overcoated with a fogged, direct-positive silver chloride emulsion prepared according to the procedure of Example 1 and coated at 48 milligrams of silver and 96 milligrams of gelatin per square foot.
  • the direct-positive photosensitive element obtained is exposed, processed and printed in the manner described in Example 6 to give a right reading positive lithographic print.
  • the plate offers many significant advantages over many other positive working plates heretofore available.
  • the plate has a relatively simple structure, does not require complex processing and can be processed quickly in stable processing solutions prior to printing.
  • a positive-working presensitized printing plate comprising a support, a hardened gelatin photographic emulsion layer containing grains comprising a central core of water-insoluble silver salt containing centers which promote deposition of photolytic silver and an outer shell covering said core comprising a fogged water-insoluble silver salt that develops to silver without exposure, and a polyhydroxybenzene developing agent which is a halogen-substituted, phenyl-substituted or 26 carbon atomcontaining alkyl-substituted polyhydroxy benzene devel oping agent and which oxidizes upon development of the emulsion layer to render gelatin oleophilic in an unexposed area.
  • said emulsion layer is a silver halide emulsion layer containing grains comprising a central core of silver halide containing centers which promote deposition of photolytic silver and an outer shell covering said core comprising a fogged silver halide that develops to silver without exposure.
  • halogenaccepting compound is a merocyanine dye.
  • RSO M wherein R represents a polynuclear aromatic group and M represents a hydrogen atom or a water-soluble cation salt group.
  • a process which comprises (a) exposing to a subject a positive-working presensitized printing plate comprising a support, a hardened gelatin photographic silver halide emulsion layer containing grains comprising a central core of silver halide containing centers which promote deposition of photolytic silver and an outer shell covering said core comprising a fogged silver halide that develops to silver without exposure and (b) developing the emulsion layer with a polyhydroxybenzene developing agent which is a halogen substittued, phenylsubstituted or 26 carbon atom-containing alkyl-substituted polyhydroxybenzene developing agent and which renders gelatin oleophilic in an unexposed area.
  • a polyhydroxybenzene developing agent which is a halogen substittued, phenylsubstituted or 26 carbon atom-containing alkyl-substituted polyhydroxybenzene developing agent and which renders gelatin oleophilic in an une
  • said printing plate contains a polyhydroxybenzene developing agent which is a halogen-substituted, phenyl-substituted or 2-6 carbon atom-containing aklyl-substituted polyhydroxybenzene developing agent and which oxidizes upon development to render gelatin oleophilic in an unexposed area and said step (b) is accomplished by contacting said exposed emulsion layer with an alkaline solution to produce a printing surface which is positive with respect to the subject.
  • a polyhydroxybenzene developing agent which is a halogen-substituted, phenyl-substituted or 2-6 carbon atom-containing aklyl-substituted polyhydroxybenzene developing agent and which oxidizes upon development to render gelatin oleophilic in an unexposed area
  • said step (b) is accomplished by contacting said exposed emulsion layer with an alkaline solution to produce a printing surface which is positive with respect to the subject.
  • said emulsion also contains a sulfonated compound having the formula RSO M wherein R represents a polynuclear aromatic group and M represents a hydrogen atom or a water-soluble cation salt group.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
US635687A 1967-05-03 1967-05-03 Positive-working presensitized planographic printing plate Expired - Lifetime US3597201A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US63568767A 1967-05-03 1967-05-03

Publications (1)

Publication Number Publication Date
US3597201A true US3597201A (en) 1971-08-03

Family

ID=24548715

Family Applications (1)

Application Number Title Priority Date Filing Date
US635687A Expired - Lifetime US3597201A (en) 1967-05-03 1967-05-03 Positive-working presensitized planographic printing plate

Country Status (6)

Country Link
US (1) US3597201A (en:Method)
BE (1) BE714416A (en:Method)
CH (1) CH493013A (en:Method)
DE (1) DE1772357B2 (en:Method)
FR (1) FR1562576A (en:Method)
GB (1) GB1223334A (en:Method)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3854949A (en) * 1971-03-10 1974-12-17 Eastman Kodak Co Silver halide photographic compositions and processes for obtaining positive images

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3854949A (en) * 1971-03-10 1974-12-17 Eastman Kodak Co Silver halide photographic compositions and processes for obtaining positive images

Also Published As

Publication number Publication date
DE1772357A1 (de) 1971-03-04
CH493013A (fr) 1970-06-30
GB1223334A (en) 1971-02-24
FR1562576A (en:Method) 1969-04-04
DE1772357B2 (de) 1973-05-03
BE714416A (en:Method) 1968-09-16

Similar Documents

Publication Publication Date Title
US3510348A (en) Direct positive recording film
US3501305A (en) Monodispersed photographic reversal emulsions
US3615533A (en) Heat and light sensitive layers containing hydrazones
US3600166A (en) Lithographic plate and process of making
US3615573A (en) Direct-positive composition containing individually and differently fogged silver halide emulsions
US3632340A (en) Cored direct positive silver halide emulsion developed with polyhydroxybenzene
JPS6015936B2 (ja) ハロゲン化銀写真感光材料
US3615443A (en) Presensitized planographic printing plate
US3446619A (en) Radiation sensitive silver-dye complexes
US3647463A (en) Direct-positive photographic elements containing multiple layers
JPS5863933A (ja) 画像形成方法
US3615517A (en) Direct-positive silver halide emulsion containing halogen conductor and electron acceptor developed with polyhydroxy benzene
US3597201A (en) Positive-working presensitized planographic printing plate
US3369902A (en) Lithographic plates sensitized with oxacarbocyanine and benzimidazole carbocyanine dyes
US3600177A (en) Liquid amides as silver halide developer solvents
US4149889A (en) Direct offset printing plate
US3796577A (en) Direct positive process involving uniform exposure of an imagewise exposed internally sensitive silver halide emulsion to high intensity radiation
US3586505A (en) Sensitizing silver halide emulsion layers
US3679424A (en) Fogged,direct-positive silver halide emulsion containing nitron
US3576634A (en) Lithographic printing plate containing a di(tetrahydrofurfuryl) ester
US4393128A (en) Light-sensitive lithographic printing plate precursor
US3326687A (en) Photographic colloid transfer system
US3591386A (en) Lithographic element and novel polymers contained therein
JPS6336649B2 (en:Method)
JPH07175218A (ja) リトグラフ用印刷版の製法