Classifications

• • 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
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives

Definitions

• the present invention relates to a photosensitive silver halide material for obtaining black-and-white half-tone, dot or line, images having improved resistance to pressure desensitization.
• Photosensitive silver halide materials are commonly used in photolithographic industry to obtain half-tone, dot or line, high contrast images.
• An example of high contrast photographic element having white reflective support is a phototypesetting material intended to produce black type character image on a white background.
• An example of high contrast photographic element having a transparent support is lith film, so called because it is used as contact transparency for exposing lithographic printing plates. The illusion that some areas of a printed image are of intermediate density is created by the viewer's inability to resolve tiny dots or lines of maximum density and background areas of minimum density that separate them. Such images are referred to as half-tone images.
• Pressure sensitivity of the silver halide photographic material can be reduced by the incorporation of various addenda, such as, for example, the addenda described in Research Disclosure , Vol 176, December 1978, Item 17643, Section VI, K ; Research Disclosure , Vol 184, August 1979, Item 18431, Section II, H; Research Disclosure , Vol 308, December 1989, Item 308,119, Section VI, K-L; and E.J.Birr, Stabilization of Silver Halide Emulsion, Focal Press, London, 1974, pp. 133-134. Research Disclosure is published by Kenneth Mason Publications, Ltd., Emsworth, Hampshire P010 7DD, England. However, such addenda often affect photographic characteristics without having a substantial effect on pressure sensitivity.
• polyhydroxybenzene to reduce pressure sensitivity is limited in that the high quantity of said compound can deteriorate anti-blocking properties, in particular, it can increase the tendency toward tackiness of the emulsion.
• the present invention relates to a light-sensitive silver halide photographic material to obtain black-and-white half-tone, dot or line, images comprising a support and coated thereon one or more hydrophilic layers, at least one of said hydrophilic layers including a high chloride content silver halide emulsion, characterized in that said silver halide emulsion comprises a polyhydroxybenzene having the following formula: wherein n is 1,2 or 3, and in that the outermost hydrophilic layer comprises a polydialkylsiloxane.
• said polydialkylsiloxane corresponds to the following formula: wherein R1 is an alkyl group having 1 to 3 carbon atoms, R2 is an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 2 carbon atoms and n is a positive integer of from 0 to 2000.
• the present invention relates to a method for obtaining a half-tone, dot or line, image, wherein a silver halide photographic material, comprising a support and coated thereon one or more hydrophilic layers, at least one of said hydrophilic layers including a high chloride content silver halide emulsion, is image-wise exposed for forming said image, and subjected to a photographic process comprising an alkaline developing solution, characterized in that the high-chloride content silver halide emulsion of said photographic material comprises a polyhydroxybenzene derivative of formula wherein n is 1,2 or 3, and in that the outermost hydrophilic layer of said photographic material comprises a polydilakylsiloxane preferably having the following formula: wherein R1 is an alkyl group having 1 to 3 carbon atoms, R2 is an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 2 carbon atoms and n is a positive integer of from 0 to 2000.
• the present invention relates to a light-sensitive silver halide photographic material to obtain black-and-white half-tone, dot or line, images comprising a support and coated thereon one or more hydrophilic layers, at least one of said hydrophilic layers including a high chloride content silver halide emulsion, characterized in that said silver halide emulsion comprises a polyhydroxybenzene having the following formula: wherein n is 1,2 or 3, and in that the outermost hydrophilic layer comprises a polydilakylsiloxane preferably having the following formula: wherein R1 is an alkyl group having 1 to 3 carbon atoms, R2 is an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 2 carbon atoms and n is a positive integer of from 0 to 2000.
• the polyhydroxybenzenes according formula (I) above can be dihydroxybenzene derivatives, trihydroxybenzene derivatives, or tetrahydroxybenzene derivatives.
• dihydroxybenzene are 1,2-dihydroxybenzene, i.e., pyrocatechol, 1,3-dihydroxybenzene, i.e., resorcinol, 1,4-dihydroxybenzene, i.e., hydroquinone.
• trihydroxybenzene 1,2,3-trihydroxybenzene, i.e., pyrogallol, 1,3,5-trihydroxybenzene, i.e., phloroglucinol, 1,2,4-trihydroxybenzene, i.e., hydroxyhydroquinone.
• tetrahydroxybenzene 1,2,3,4-tetrahydroxybenzene, 1,2,4,5-tetrahydroxybenzene, 1,3,4,5-tetrahydroxybenzene.
• Said polyhydroxybenzenes can be unsubstituted or substituted with, for example, halogen, alkyl, alkoxy, amino, amido, sulfonamido, carboxy, and the like. Unsubstituted polyhydroxybenzenes are preferred.
• the polyhydroxybenzenes are added to the photographic emulsion comprising light sensitive silver halide grains and a carrying medium or binder in an amount of from 0.01 to 0.1 moles per mole of silver, preferably of from 0.03 to 0.07 moles per mole of silver.
• the polydialkylsiloxanes according to the formula (II) above are generally added to the carrying medium or binder which forms the outermost layer of the film as an aqueous dispersion in the presence of a suitable dispersing agent, preferably a non-ionic dispersing agent.
• a suitable dispersing agent preferably a non-ionic dispersing agent.
• An aqueous dispersion containing 35% by weight of the silicone polymer is preferred but dispersions containing 1 to 50% by weight of the polymer are suitable.
• Useful polydialkylsiloxanes include commercially available silicone oils such as the trialkyl and trialkoxy endblocked dialkylpolysiloxanes, e.g., dimethylpolysiloxane, diethylpolysiloxane, trimethoxy endblocked dimethylpolysiloxane and triethoxy endblocked dimethylpolysiloxane.
• the polydialkylsiloxanes have molecular weights of from 100 to 150,000, preferably of from 10,000 to 20,000 and a viscosity at 25°C of from 2 to 100,000 centistokes, preferably of from 200 to 800 centistokes.
• the polydialkylsiloxanes can be used in any concentration which is effective for the intended purpose.
• a suitable concentration is of from 0.01 to 0.1, preferably of from 0.02 to 0.08 grams per square meter of the photographic material.
• Suitable dispersing agents are generally of non-ionic type such as alkyl phenyl polyethylene glycol ethers, e.g., nonyl phenyl polyethylene glycol ether, and undecyl phenyl polyethylene glycol ether; alkyl and aralkyl polyether alcohols, e.g., iso-octyl phenyl polyethoxyethanol, nonyl phenyl polyethoxyethanol, and tetradecyl phenyl polyethoxyethanol.
• alkyl phenyl polyethylene glycol ethers e.g., nonyl phenyl polyethylene glycol ether, and undecyl phenyl polyethylene glycol ether
• alkyl and aralkyl polyether alcohols e.g., iso-octyl phenyl polyethoxyethanol, nonyl phenyl polyethoxyethanol, and tetradecyl phenyl polyeth
• Suitable dispersing agents include saponin and the oxyalkylene ethers of hexitol ring dehydration products, e.g., the polyoxyethylene sorbitan monolaurates, monostearates and monooleates which contain 2 to 20 oxyethylene groups divided in three chains; salts of alkyl-substituted aryloxy alkylene ether sulfonates, e.g., sodium p-t-octylphenoxyethoxyethyl sulfonate; sodium dodecyl, tetradecyl and octadecyl sulfates and the dioctyl ester of sodium sulfosuccinic acid. Certain soaps, e.g., morpholine oleate and sodium stearate, can also be used.
• the dispersing agents are used in amount of from 1 to 50%, preferably of from 2 to 20% by weight of the silicone oil.
• the polydialkylsioloxanes can be added in a suitable organic solvent, e.g., amyl acetate, benzene, carbon tetrachloride, ethyl ether, perchloroethylene, petroleum ether, or xylene.
• a suitable organic solvent e.g., amyl acetate, benzene, carbon tetrachloride, ethyl ether, perchloroethylene, petroleum ether, or xylene.
• the organic solvent must not adversely affect the physical or photographic properties of the photographic film.
• any hydrophilic binder known in the art can be used.
• Suitable binders include natural polymers, synthetic resins, polymers and copolymers, and other film forming media.
• the binders may range from thermoplastic to highly cross-linked, and may be coated from aqueous or organic solvents or emulsions.
• Gelatin is the preferred hydrophilic colloid for use in the present invention.
• other water-soluble colloidal substances or mixtures thereof can also be used.
• Exemplary hydrophilic colloidal substances include gelatine derivatives, such as phthalated gelatin and acetylated gelatine, cellulose derivatives, such as carboxymethyl cellulose, starch, casein, zein, synthetic hydrophilic colloids such as polyvinyl alcohol, polyvinyl pyrrolidone, copolymers of acrylic acid esters, acrylonitrile and acrylamides, etc.
• the amount of hydrophilic binder used in practice depends on the dispersing solvent amount and the coating thickness required. Since an excessive amount of binder can reduce maximum density and contrast, for the purpose of the present invention, the binder is advantageously used in an amount lower than 250 grams per mole of silver halide, preferably in an amount of from 20 to 200 grams per mole of silver halide.
• the silver halide emulsions used in the present invention are preferably monodispersed, but emulsions having a wide grain size distribution can also be used.
• the term "monodispersed” refers to an emulsion having a coefficient of variation lower than 45%, preferably lower than 35%, more preferably lower than 20%.
• the emulsions suitable in the present invention are of the type normally employed to obtain halftone, dot and line, images and are usually called lith emulsions.
• Lith emulsions contain preferably at least 50 mole % of silver chloride, more preferably at least 80% of silver chloride and at least about 5% mole of silver bromide.
• the silver halide grains can contain a small amount of silver iodide, in an amount that is usually less than about 5 mole %, preferably less than 1 mole %.
• Other references to lith materials can be found in Research Disclosure 235, November 1983, Item 23510, " Development Nucleation by Hydrazine and Hydrazine derivatives ".
• the silver halide grain average size is lower than about 0.7 ⁇ m, preferably lower than about 0.4 ⁇ m, more preferably lower than 0.2 ⁇ m.
• the term "grain size” refers to the diameter of a circle having the area of the same value as the average area projected by the silver halide crystals seen at the electron microscope.
• the silver halide grains may be those having a regular crystal form, such as a cube or an octahedron, or those having an irregular crystal form, such as a sphere or tablet, etc., or may be those having a composite crystal form. They may be composed of a mixture of grains having different crystal forms.
• the silver halide emulsion may be chemically sensitized with a sulfur sensitizer, such as allylthiocarbamide, thiourea, cysteine, etc.; an active or inert selenium sensitizer; a reducing sensitizer such as stannous salt, a polyamine, etc.; a noble metal sensitizer, such as gold sensitizer, more specifically potassium aurithiocyanate, potassium chloroaurate, potassium chloroplatinate, etc.; or a sensitizer of a water soluble salt such as, for instance, of ruthenium, rhodium, iridium, palladium and the like, more specifically, ammonium chloropalladate, sodium chloropalladite, etc.; each of such sensitizers being employed either alone or in a suitable combination.
• a sulfur sensitizer such as allylthiocarbamide, thiourea, cysteine, etc.
• an active or inert selenium sensitizer such
• the silver halide emulsion may be spectrally sensitized by making it, in addition to its blue light sensitivity, sensitive to, e.g., green light (ortho-sensitive) or sensitive to green and red light (pan-sensitive).
• green light ortho-sensitive
• red light pan-sensitive
• monomethine or polymethine dyes such as acid and basic cyanines, hemicyanines, streptocyanines, merocyanines, oxonoles, hemioxonoles, styryl dyes or others, as well as trinuclear or higher nuclear methine dyes, e.g., rhodacyanines or neocyanines can be used.
• Sensitizers of this kind have been described, for example, in F.M. Hamer, " The Cyanine Dyes and Related Compounds ", 1964 Interscience Publishers, John Wiley and Sons, New York, and in Research Disclosure 308, December 1989, Item 308119, Photographic Silver Halide Emulsions, Preparation , Addenda, Processing and System ", Section IV.
• the silver halide emulsions can be prepared using a single-jet method, a double-jet method, or a combination of these methods or can be matured using, for instance, an ammonia method, a neutralization method, an acid method, etc.
• water soluble salts are removed from the emulsion with procedures known in the art, such as ultrafiltration.
• the emulsions can contain optical brighteners, antifogging agents and stabilizers, filtering and antihalo dyes, hardeners, coating aids, plasticizers and lubricants and other auxiliary substances, as those described, for instance, in Research Disclosure 17643, V, VI, VIII, X, XI and XII, December 1978.
• the above described emulsions can be coated onto several support bases by adopting various methods, as described in Research Disclosure 17643, XV and XVII, December 1978.
• supports include films of a poly-alpha-olefin (such as polyethylene, polystyrene, etc.), a polyester (such as polyethyleneterephthalate, etc.), cellulose esters (such as cellulose triacetate, etc.), paper, synthetic paper or resin-coated paper and the like.
• a poly-alpha-olefin such as polyethylene, polystyrene, etc.
• a polyester such as polyethyleneterephthalate, etc.
• cellulose esters such as cellulose triacetate, etc.
• paper synthetic paper or resin-coated paper and the like.
• the above emulsions may also contain various additives conveniently used depending upon their purpose.
• additives include, for example, stabilizers or antifoggants such as azaindenes, triazoles, tetrazoles, imidazolium salts, polyhydroxy compounds and others; film hardeners such as of the aldehyde, aziridine, isoxazole, vinylsulfone, acryloyl, triazine type, etc.; developing promoters such as benzyl alcohol, polyoxyethylene type compounds, etc.; image stabilizers such as compounds of the chromane, cumaran, bisphenol type, etc.; and lubricants such as wax, higher fatty acid glycerides, higher alcohol esters of higher fatty acids, etc.
• coating aids modifiers of the permeability in the processing liquids, defoaming agents, antistatic agents and matting agents may be used. References for the kind and for the use of these additives can be found in Research Disclosure 308, December 1989, Item 308119, " Photographic Silver Halide Emulsions, Preparation, Addenda, Processing and System ".
• the photographic material of the present invention can include a hydrazine derivative to obtain high contrast images.
• a hydrazine derivative to obtain high contrast images.
• Any known hydrazine derivatives can be used, such as, for example, hydrazine derivatives described in Research Disclosure 235, November 1983, Item 23510, " Development Nucleation by Hydrazine and Hydrazine derivatives ".
• the present invention relates to a method for obtaining a half-tone, dot or line, image, wherein a silver halide photographic material, comprising a support and coated thereon one or more hydrophilic layers, at least one of said hydrophilic layers including a high chloride content silver halide emulsion, is image-wise exposed for forming said image, and subjected to a photographic process comprising an alkaline developing solution, characterized in that the high-chloride content silver halide emulsion of said photographic material comprises a polyhydroxybenzene of formula: wherein n is 1,2 or 3, and in that the outermost hydrophilic layer of said photographic material comprises a polydialkylsiloxane preferably having the following formula: wherein R1 is an alkyl group having 1 to 3 carbon atoms, R2 is an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 2 carbon atoms and n is a positive integer of from 0 to 2000.
• the present invention does not put any particular restriction on the developing process of the photosensitive material.
• any developing process can be adopted (comprising the developing, fixing and etching steps) which is used to process conventional photographic materials to be used in the lithographic field.
• Such developing process can be performed manually or by using automatic processors, at a processing temperature generally ranging from 18 to 50°C, but also outside said range, if desired.
• the developing solution can contain any known developing agent.
• developing agents which can be used alone or in mixture
• developing solutions can contain preservatives, alkali agents, buffering agents, antifoggants, water softening agents, hardeners, and the like.
• a suitable developing solution which can be used with the photographic material of the present invention is the so-called lith developing solution, which comprises a dihydroxybenzene developing agent, an alkali agent, a small quantity of free sulfite and a buffering agent for the sulfite ions (such as formaline and sodium bisulfite adducts and acetone and sodium bisulfite adducts) to monitor the free sulfite concentration, etc.
• lith developing solution which comprises a dihydroxybenzene developing agent, an alkali agent, a small quantity of free sulfite and a buffering agent for the sulfite ions (such as formaline and sodium bisulfite adducts and acetone and sodium bisulfite adducts) to monitor the free sulfite concentration, etc.
• the fixing solution can have any conventional composition.
• fixing agents which can be used comprise thiosulfates, thiocyanates and sulfur organic compounds, known as fixing agents.
• the fixing solution can further contain water-soluble alluminium salts as hardeners.
• the etching solution can have any conventional composition as well, and, for instance, the compositions described by C.E.K. Mees in " The Theory of the Photographic Process ", McMillan, 1954, pp.
• an etching solution which comprises, as a reducing agent, a permanganate, a ferric salt, a persulfate, a cupric acid, a ceric acid, a hexacyanoferate-(III) or a dichromate, alone or in combination and, possibly, an inorganic acid such as sulfuric acid, and an alcohol; or an etching solution can be used which comprises a reducing agent such as a hexacyanoferrate-(III), ethylenediaminotetracetatoferrate-(III) or the like and a silver halide solvent such as thiosulfate, thiocyanate, thiourea or a derivative thereof and, possibly, an inorganic acid such as sulfuric acid.
• Representative examples of etching solutions are Farmer's solultions comprising potassium ferrocyanide and sodium thiosulfate, an etching solution comprising persulfate, an etching solution comprising
• a cubic monodispersed 0.32 ⁇ m silver chlorobromide (40 mole percent bromide) was prepared as follows.
• a solution (A) consisting of 4.700 l water, 0.9 g adenine and 84 g of gelatin was initially introduced into a reaction vessel.
• the components used for the silver halide grain formation were a solution (B) of 5.379 l water and 2380 g silver nitrate and a solution (C) of 5.281 l water, 688 g KCl, 733 g KBr and 0.002 g Na3RhCl6 ⁇ 18H2O.
• Solutions (B) and (C) were introduced into the reaction vessel through two separate inlets simultaneously with a vigorous stirring for a period of 9 minutes with a flow rate of 51.0 ml/min while the pAg of the content into the vessel was maintained at 8.3 and the volume of the content in the vessel was increased from 4764 ml to 5682 ml and the temperature was maintained at 56°C.
• Step 2 was repeated to reduce the content in the reaction vessel from 5682 to 3288 ml.
• Step 4 was repeated.
• step 5 Fifty minutes after beginning, step 5 was repeated.
• Step 4 was repeated.
• step 5 Sixty five minutes after beginning, step 5 was repeated.
• Gelatin (1050 g) was added to the content in the reaction vessel while stirring at 45°C until the gelatin was dissolved.
• the resulting emulsion was gold and sulfur sensitized, optically sensitized at 630 nm, divided into six parts and each part added with a polyhydroxybenzene (additive), as reported in Table 1, and coated onto a polyethylene terephthalate support at a silver coverage of 4.08 m2.
• the coatings A-F were subjected to the pressure sensitivity test consisting in applying a special tungsten carbide stylus with variable weight loading on the surface of unprocessed film.
• the coatings were then processed in 3M RDC V lith developer and evaluated by measuring the minimum weigth necessary to make a visible line.
• the samples were evaluated according the following classification: Class Grams on stylus Rating A 200-170 Excellent A-B 170-140 Good B 140-110 Borderline B-C 110-85 Unacceptable C 85-50 " C-D 50-30 " D ⁇ 30 "
• a cubic monodispersed silver chlorobromide emulsion was prepared as described in the previous example 1, chemically and spectrally sensitized, added with hydroquinone as reported in Table 3 and coated according to Example 1.
• a gelatin protective layer comprising silicone was coated onto the emulsion layer as reported in Example 1. TABLE 3 Coating Additive Silicone g/m2 Type M/M Ag A - - - B - - 0.05 C Hydroquinone 0.05 - D Hydroquinone 0.05 0.05
• the coatings A-D were subjected to the pressure sensitivity test as described in the previous example 1.
• a cubic monodispersed silver chlorobromide emulsion was prepared as described in the previous example 1, chemically and spectrally sensitized, and coated using same antikinking agents disclosed in literature, such as polymers of US Patent No. 4,485,170, non-ionic surfactants of JP 62/264,042, and salts of palladium, iridium and tallium of JP 62/229,129.
• the coatings A-E were subjected to the pressure sensitivity test as described in the previous example 1.

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• Engineering & Computer Science (AREA)
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• 1991
  • 1991-09-26 IT ITMI912568A patent/IT1251885B/it active IP Right Grant
• 1992
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  • 1992-09-07 EP EP92115267A patent/EP0534218B1/de not_active Expired - Lifetime
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