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
  • G03F7/063—Additives or means to improve the lithographic properties; Processing solutions characterised by such additives; Treatment after development or transfer, e.g. finishing, washing; Correction or deletion fluids

Definitions

• ABSTRACT A composition for treating a silver image, such as that obtained by the photographic silver salt diffusion transfer process on a hydrophilic surface, comprises an acidic aqueous solution containing:
• a long chain organic non-aromatic cationic compound such as a long chain organic quaternary ammonium compound, or a long chain organic sulphonium compound
• a printing plate comprising a hydrophilic surface having a silver image thereon which has been treated with this composition, and a process for preparing said plate comprising contacting a silver image on a hydrophilic surface with this composition, are taught.
• the present invention relates to lithographic processes and to lithographic printing plates made photographically. More particularly, this invention relates to a method of rendering oleophilic a silver image which has been produced by the photographic silver salt diffusion transfer process at a water accepting surface, such as the surface of a hydrophilic colloid layer or the surface of a hydrophilic pigment in a binder, so that the silver image accepts greasy printing ink. This invention also relates to the composition for treating the image and to the treated printing plates.
• the printing plate In lithography, a greasy ink is employed and the printing plate usually comprises a layer which, when wet with water, is hydrophilic and carries a line or dot image which is oleophilic.
• Various methods of obtaining a silver image on a lithographic printing plate blank can be used in a preferred process involving the photographic silver salt diffusion transfer process, in which diffusing silver halide complex contacts silver precipitating nuclei on the surface of a lightographic plate to deposit a sliver image.
• This silver image is then treated with a fix solution containing an olephilic compound which is adsorbed to the silver image to improve its affinity for a greasy printing ink.
• composition for treating the silver image, which composition contains:
• the acidic aqueous solution contains a water-miscible alcohol having one or more hydroxy groups; e.g., methanol, and/or isopropanol and/or isobutanol so as to increase the solubility of the solutes to the desired level.
• the long chain organic cationic compound is preferably cetyl trimethylammonium bromide; the iodide ions are supplied by potassium iodide, and the organic compound having a nitro group bonded to an aromatic nucleus is l-(2',4- dinitrophenyl) pyrdinium chloride or 8-nitroquinoline.
• a heterocyclic organic compound having a nitro group bonded to an aromatic nucleus is preferably employed as the component (0) when the silver image requires more oxidation as a step in the process of rendering the silver oleophilic. Whether or not more oxidation is required depends in part on the structure of the silver. If the silver is very porous the compound having a nitro group is likely to oxidize the silver too much. v
• a printing plate comprising a silver image on a hydrophilic surface, which has been treated with the above acidic aqueous fix solution in order to improve the affinity for greasy printing ink.
• a printing plate comprising a silver image on a hydrophilic surface, which image has been treated with the above acidic aqueous fix solution in order to improve the affinity for greasy printing ink.
• Long Chain Cationic Compound in the present invention there may be used as the long chain organic cationic compound any of the cationic surfactants described in chapters 2 and 3 of Cationic Surfactants, edited by E. .lungermann and published by Marcel Dekker Inc., New York, 1970,
• R represents a long alkyl chain of 12 to carbon atoms
• each of R, R" and R may be either a long alkyl chain or a smaller alkyl group of 1-20 carbon atoms
• X represents an anion
• Y represents a moiety containing an anion such as Z-CH CO6, or Z-CH CH OS6 in which Z is a halide ion.
• the compounds employed may contain additional groups in the long chain such as -CONH- and may contain more than one cationic N atom.
• Preferred long chain cationic compounds for use in this invention may be represented by formula I.
• R, R, R" and R' are each an alkyl group of l-ZO carbon atoms, at least one of R, R, R and R being an alkyl group containing at least 12 carbon atoms and X is a halogen ion other than iodide or a sulphate ion.
• heterocyclic organic compound for example, potassium, sodium, and the like, preferably potassium iodide; however, other iodide salts can be used as well as any compounds which provide iodide ions including organic materials which disassociate in aqueous solution.
• heterocyclic Organic Compound The heterocyclic organic compounds which are useful in this invention include those having one or two rings.
• Preferred heterocyclic organic compounds having a nitro group bonded to an aromatic nucleus may be represented by formulas II, III, IV and V.
• R R R R R is H, alkyl l-20 carbon atoms), N0 COOH, COOR' (R' is alkyl l-20 carbon atoms) at least one of R R and R being N0 III
• R Hal Rr- R1 R R7 is wherein R is CH R and R or R, and R complete a nitro-substituted aromatic carbocyclic ring fused onto the cyclic ammonium ring and each of R and R is an alkyl group (l-20 carbon atoms) or a halogensubstituted alkyl group (l-20 carbon atoms).
• Preferred compounds contain at least 10 carbon atoms. They are typically substituted with a group selected from the class consisting of alkyl, cyano, phenyl, halide, etc.
• Preferred organic cationic compounds having an aromatic group but no nitro group may be represented by formulas V and V1.
• R is alkyl, e.g., methyl, ethyl or cetyl (l carbon atoms); R, is H or a lower. alkyl group, e.g. methyl, etc. having [-5 carbon atoms; R is H or substituent such as cyano, alkoxycarbonyl (e.g., ethoxy carbonyl) or R and R, havethe values given above and either R and R,, or R and R complete a benzene ring fused onto the cyclic ammonium ring.
• R is a long chain alkyl group containing 12-20 carbon atoms and R is a substituent such as acyl, e.g., aceto.
• the cationic heterocyclic compounds which can be used include, for example:
• the iodide can be used in an amount within the range of about 4 to about 50 grams per liter, preferably about 6 to about 16 grams per liter.
• the organic heterocyclic compound which has a nitro group bonded to an aromatic nucleus or the aromatic cationic compound can be used in an amount within the range of about 0.5 to about 20, preferably about 4 to about 10 grams per liter.
• the pH of the aqueous solution should be such that strongly colored dyes are not formed, i.e., the solution should be acid but the pH is between about 1.5 to about 7, preferably between about 1.7 to about 6.
• the solution can be buffered at the desired pH and an organic acid; such as, for example, citric acid, lactic acid, acetic acid, etc. can be used for this purpose. Amounts of organic acid between 5 and grams per liter are useful. In a preferred embodiment, about 5 to about 40 grams per liter of an organic acid are used.
• a buffering capacity is desired on account of the residual alkali that is usually present on the water-accepting surface when the silver image has been formed thereon by the photographic silver salt diffusion transfer process.
• fix solution examples include thickness such as 2-methyl-2,4- pentanediol, hydroxyethylcellulose, carboxymethylcellulose, etc.
• thickness such as 2-methyl-2,4- pentanediol, hydroxyethylcellulose, carboxymethylcellulose, etc.
• the keeping or storage stability of the solution is good, but with some fix solutions after 2 to 4 weeks at room temperature, dark crystals begin to form on the bottom of the walls of the container holding the fix solution. These reddish-brown crystals do not dissolve on heating, nor do they interfere with the efficiency of performance of the solution. Crystal formation can be inhibited by raising the pH of the solution to a pH of 4.5 or higher or by adding an antioxidant to the solution or by adding extra solvent.
• the water-accepting surface may be the surface of a hydrophilic colloid layer or the surface of a layer of binder containing a hydrophilic pigment.
• hydrophilic colloids are gelatin, polyvinyl alcohol, alginates, carboxymethyl cellulose, etc.
• binder layers containing hydro- 7 philic pigments are synthetic hydrophobic polymer layers containing hydrophilic silica particles. Such layers are described, for example in Ormsbee, U.S. Pat. No. 3,344,741, issued Oct. 3, I967.
• Metal surfaces may also be used for the preparation of lithographic printing plates, including aluminum, zinc, etc.
• Particularly useful aluminum printing plates are those in which the aluminum surface has been treated to provide an inert hydrophilic surface.
• the surface can be anodized by employing acids; such as, sulfuric, oxalic, phosphoric, and the like.
• the surface is anodized as described in Rauner et al, U.S. Pat. No. 3,511,661, issued May 12, 1970.
• hydrophilic surface including polymeric materials; such as, cellulose esters, polyesters; such as, polyethylene terephthalate, polyamides, etc.
• Precipitating agents which are particularly useful for use in the hydrophilic layer for formation of the silver image by a black and white diffusion transfer process include nuclei which are useful as precipitating agents with a silver halide complex, including all of those which are commonly useful in the diffusion transfer process.
• Nuclei which can be employed include silver precipitating agents known in the art such as sulfides, selenides, polysulfides, polyselenides, heavy metals, thiourea, stannous halides, heavy metal salts, fogged silver halide, Carey Lea silver, and complex salts of heavy metals with a compound such as thioacetamide, dithiooxamide and dithiobiuret.
• Noble metal nuclei are particularly active and useful when formed by reducing a noble metal salt using a borohydride or hypophosphite in the presence of a colloid.
• the metal nuclei can be prepared in the presence of a proteinaceous colloid such as gelatin and coated on the receiving sheet. The same or a different colloid may be added if desired. It will be appreciated that the coating composition generally contains not only nuclei, but also reaction products which are obtained from reducing the metal salt.
• the nuclei or silver precipitating agent may be incorporated in the lithographic layer itself by adding a suitable silver precipitant to the coating composition including the silica, titanium dioxide, polymeric material, etc.
• a suitable silver precipitant including the silica, titanium dioxide, polymeric material, etc.
• a minimum of binder or dispersing agent is employed to contain the nuclei or silver precipitating agent.
• various colloids can be used as dispersing agents or as binders for the precipitating agents in the receiving layer. Any suitable colloids can be used. Particularly useful colloids are hydrophilic colloids which are used for binders in silver halide emulsions.
• suitable colloids are gelatin, preferably coated at a level in the range of about 71 00 mg/ft polymeric latices such as copoly(2-chloroethyl-methacrylate-acrylic acid) preferably coated in the range of 15-350 mg/ft in a polymeric vehicle containing two components I) polyvinyl alcohol, and (2) inter-polymer of nbutylacrylate, 3-acryloyloxypropane-l-sulfonic acid, sodium salt and 2-aceto-acetoxyethyl mcthacrylate, in a preferred range of about 10-300 mg/ft
• the precipitating agents can be formed in situ or can be applied by precipitating or evaporating a suitable precipitating agent on the surface.
• the hydrophilic layers in the lithographic plate blanks of our invention may also have therein particles, such as silica, bentonite, diatomaceous earth such as kieselguhr, powdered glass, micro crystalline asbestos and fullers earth.
• particles such as silica, bentonite, diatomaceous earth such as kieselguhr, powdered glass, micro crystalline asbestos and fullers earth.
• colloidal particles of metal oxides such as titanium dioxide, colloidal alumina, coarse aluminum oxide, zirconium oxide and the like may be used with the nuclei in the receiving layers.
• a silver halide emulsion is exposed to a light image after which it is contacted with a silver halide developing agent containing a silver halide complexing agent.
• the exposed emulsion is developed in the light struck areas and the unexposed silver halide is complexed with the silver halide complexing agent after which the emulsion is contacted against a receiving sheet and the silver halide complex diffuses imagewise to the receiving sheet containing a silver precipitant.
• an integral element in which an unhardened silver halide emulsion is located over the nucleated layer.
• the silver halide emulsion is developed employing a silver halide solvent to form a silver image in the nucleated layer.
• the unhardened silver halide emulsion is then removed, typically by using hot water.
• the silver image is then treated according to my invention to improve the oleophilic nature of the silver image;
• Example 1 A sheet of negative material is prepared as follows:
• Paper base weighing 135 grams per square meter is first made developer resistant by applying to one side a coating of pigmented polyethylene at the rate of grams per square meter and on the other side a coating of unpigmented polyethylene at the rate of 10 grams per square meter.
• This coated base is given a hydrophilic surface by subjecting the pigmented coating to a high voltage discharge.
• the hydrophilic surface is then coated with an orthosensitized high contrast silver chloride emulsion at a rate equivalent to 1.5 grams per square meter of silver nitrate, the gelatin content of the emulsion being 0.5 gram per square meter.
• the emulsion contains formaldehyde as a hardening agent.
• This sensitive element is exposed to a light image and passed in contact with a polyethylene coated paper receiver having thereon a hydrophilic lithographic coating over which has been coated a layer of silver precipitating nuclei through a solution composed of:
• the sheets are squeegeed together and separated after about seconds.
• the imaged receiver is then treated with the following fix solution of the invention, which is applied evenly with a cotton wool pad.
• Photographic silver halide emulsions, preparations, addenda, processing and systems which may be used in connection with preparing the image treated according to this invention are disclosed in Product Licensing index, Volume 92, December, 1971, Publication 9232, pages 107-110, paragraphs, 1-X1l, 1V-XV111, and XXIII.
• composition for improving the oleophilic character of a silver image comprising an acidic aqueous solution containing:
• R is alkyl having 12 to 20 carbon atoms
• each of R, R", and R' is alkyl having one to 20 carbon atoms
• Y is ZCH COO or ZCH CH OSO in which Z is a halide ion
• X is an anion
• said long chain alkyl compound is a ternary sulfonium compound containing a long alkyl chain of from 12 to 20 carbon atoms.
• composition of claim 2 wherein said compound is cetyl trimethyl ammonium bromide.
• a composition of claim 1 wherein said compound comprising a heterocyclic nucleus has the formula wherein R R R R and R are each H, alkyl having 1-20 carbon atoms, N COOH, COOR', (R is alkyl having l-20 carbon atoms) and at least one of R R and R is N0 X is a halogen ion.
• a composition of claim 1 wherein said compound comprising a heterocyclic nucleus has the formula R 1 69 Hz R1 X wherein R is CH- l, R and R., or R and R complete a nitro-substituted aromatic carboxylic ring fused on to the cyclic ammonium ring and each of R and R is an alkyl group l carbon atoms) or a halogensubstituted alkyl group (1 20 carbon atoms); X is a halogen ion.
• composition of claim 1 wherein said compound comprising a heterocyclic nucleus has the formula R: a V wherein R, or R is N0 the remaining group is H or CH, or a halogen-substituted methyl group.
• composition of claim 1 wherein said compound comprising a heterocyclic nucleus has the formula wherein R is alkyl (l-20 carbon atoms), R is H or an alkyl group (l-5 carbon atoms), R is H or cyano or alkoxy carbonyl, or R and R, have the values given above and R and R or R and R complete a benzene ring fused on to a cyclic ammonium ring; X is a halogen ion.
• a composition of claim 1 wherein said compound comprising a heterocyclic nucleus has the formula wherein R is a long chain alkyl group containing 12-20 carbon atoms and R is acyl.
• a lithographic element comprising a support having thereon a hydrophilic surface and having thereon a silver image having been treated with the acidic aqueous solution of claim 1.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)

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Citations (3)

• 0
  • BE BE788616D patent/BE788616A/xx not_active IP Right Cessation
• 1971
  • 1971-09-10 GB GB4227471A patent/GB1406030A/en not_active Expired
• 1972
  • 1972-09-07 JP JP8918272A patent/JPS5540857B2/ja not_active Expired
  • 1972-09-07 US US00287196A patent/US3819374A/en not_active Expired - Lifetime
  • 1972-09-07 IT IT28918/72A patent/IT967233B/it active
  • 1972-09-07 US US00287197A patent/US3832175A/en not_active Expired - Lifetime
  • 1972-09-08 FR FR7231843A patent/FR2250444A5/fr not_active Expired

Patent Citations (3)

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