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(11) | EP 0 226 184 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Nucleation development control agent for photographic silver halide materials and processes |
| (57) A nucleation development control agent that is an isothiuronium compound or a free
mercaptan aids nucleation development in a negative working photographic silver halide
material comprising a nucleating agent. The nucleation development control agent helps
increase image discrimination and helps reduce image development spread beyond unexposed
grains in close proximity to exposed silver halide grains. The nucleation development
control agent can be in this photographic material and or in an aqueous silver halide
developer solution for use in nucleation development of the imagewise exposed photographic
material. |
[0001] This invention relates to a negative-working photographic silver halide element, process and developer composition comprising a nucleation development control agent which enables increased image discrimination and enables reduced image development spread beyond unexposed silver halide grains in close proximity to exposed silver halide grains in the photographic element.
[0002] High-contrast negative-working photographic silver halide photographic elements, that is such elements which are capable of providing a developed image having a gamma higher than 10, are generally known as "lith" photographic elements. Conventional lith photographic elements contain high chloride photographic silver halide emulsions, that is photographic silver halide emulsions containing at least 50 percent by weight silver chloride based on total silver halide in the photographic element, typically in the form of silver chlorobromides and silver chlorobromoiodides. High contrast development of such exposed photographic elements is achieved by means of a phenolic developing agent, such as described by J.A.C. Yule in the Journal of the Franklin Institute, Vol. 239, pages 221-230 (1945).
[0003] High contrast negative-working photographic silver halide elements comprising nucleating agents are also known. Such elements are described in, for example, Canadian Patent 1,146,001 and U.S. 4,269,929. Such photographic silver halide elements are useful in the graphic arts, including photolithography. These elements upon exposure and processing involve nucleation development of an image.
[0004] As described in, for example, Canadian Patent 1,146,001, high contrast negative-working photographic silver halide elements can comprise a nucleating agent in a concentration sufficient to increase contrast and sufficient to promote infectious, imagewise development of unexposed photographic silver halide grains in close proximity to exposed photographic silver halide grains. Nucleation development occurs in forming an image in such photographic silver halide elements.
[0005] Nucleation development in a negative-working photographic silver halide element comprising a nucleating agent herein means rendering unexposed photographic silver halide grains developable by means of forming developable sites on the surface of the unexposed silver halide grains by a reductive process.
[0006] A problem has been encountered in negative-working photographic silver halide elements comprising photosensitive silver halide grains capable of forming a surface latent image, and a nucleating agent, such as a hydrazide nucleating agent, in a concentration sufficient to increase contrast and sufficient to promote infectious, imagewise development of unexposed silver halide grains in close proximity to exposed silver halide grains. The problem is that insufficient control of development during nucleation has been observed. As a result of insufficient control, development during nucleation spreads to an undesired extent to unexposed silver halide grains in close proximity to exposed silver halide grains in the photographic element. Insufficient control of nucleation development also results in less than desired image discrimination in the developed photographic element. The need for nucleation development control is particularly important in negetive-working photographic silver halide elements comprising nucleating agents and chemically sensitized photographic silver halide.
[0007] No compound, silver halide developer, and process have been available before now which enable sufficient control of nucleation development to enable increased image discrimination.
[0008] It has been found that the control of nucleation development is provided in a described photographic element, process and developer composition by means of a nucleation development control agent that is an isothiuronium compound or a free mercaptan, in a concentration sufficient to (1) increase image discrimination and (2) reduce image development spread beyond unexposed silver halide grains in close proximity to exposed silver halide grains in a negative-working photographic silver halide element.
[0009] The present invention provides a negative working photographic element comprising a support bearing a photographic silver halide emulsion layer comprising photosensitive silver halide grains capable of forming a surface latent image, and a nucleating agent in a concentration sufficient to increase contrast and sufficient to promote infectious, imagewise development of unexposed silver halide grains in close proximity to exposed silver halide grains. This photographic element comprises a nucleation development control agent as described.
[0010] A process according to the invention comprises development of an exposed negative-working photographic silver halide element comprising a support bearing a photographic silver halide emulsion layer comprising photosensitive silver halide grains capable of forming a surface latent image, and a nucleating agent in a concentration sufficient to increase contrast and sufficient to promote infectious, imagewise development of unexposed silver halide grains in close proximity to exposed silver halide grains. This process is carried out in the presence of the nucleation development control agent which is an isothiuronium compound or a free mercaptan, which is in the developer solution and/or the photographic silver halide element, but preferably in the developer solution.
[0011] The process, for example, comprises the step of: developing the photographic element in a silver halide aqueous alkaline developer solution at a pH of at least 10 comprising
(i) an alkaline activator,
(ii) a dihydroxybenzene silver halide developing agent,
(iii) a sulfite preservative,
(iv) an antifoggant concentration of an antifoggant, and
(v) a nucleation development control agent which is an isothiuronium compound or a free mercaptide in a concentration sufficient to (1) increase image discrimination and (2) reduce image development spread beyond unexposed silver halide grains in close proximity to exposed silver halide grains in said element.
[0012] Examples of useful isothiuronium compounds are described in U.S. 3,220,839. A preferred nucleation development control agent is an isothiuronium compound represented by the formula:
wherein
R is alkylene, such as alkylene containing 1 to 5 carbon atoms; and
Xθ is an anion which does not adversely affect nucleation development, such as SO e
[0013] The nucleation development control agent enables increased image discrimination and reduced image development spread beyond the unexposed silver halide grains in close proximity to exposed silver halide grains. This is particularly advantageous in the graphic arts because the nucleation development control agents reduce image spread during processing thereby preserving the fine lines and sharp dots required in the graphic arts. The nucleation development control agent also can reduce the occurence of spurious black spot fog, also designated as "pepper fog", in the photographic element.
[0014] The R alkylene herein can be unsubstituted or substituted with groups that do not adversely affect the nucleation development control properties of the nucleation development control agent, including such groups as alkyl, aryl or oxygen or nitrogen containing groups, such as carboxyl, carbonyl, carbamyl, hydroxyl, ether and ester groups.
[0015] Highly preferred nucleation development control agents are isothiuronium sulfonate compounds which are represented by the formula:
wherein
R is alkylene, such as alkylene containing 1 to 5 carbon atoms.
[0019] The isothiuronium compounds are prepared by methods of synthesis known in the organic compounds synthesis art. Useful methods for preparing such compounds are described in, for example German Patent 1,031,303 and U.S. 2,833,781.
[0020] The term free mercaptan herein means a mercaptan nucleation development control agent in the free mercaptan form or in its mercaptan salt form which does not adversely affect the desired nucleation development control properties. Preferred free mercaptan nucleation development control agents are represented by the formula:
wherein
M and M are individually hydrogen, or a metal or organic cation; and
R is alkylene containing 1 to 5 carbon atoms.
[0021] Particular examples of nucleation development control agents which are free mercaptan and/or mercaptan salt compounds are as follows:
[0022] Such free mercaptans and their salts are described in, for instance, Schramm et al, J. Am. Chem. Soc., 77, 6231 (1955).
[0023] The photographic silver halide grains in the photographic element are capable of forming a surface latent image, as opposed to being of the internal latent image-forming type photographic silver halide. The photographic silver halide grains are preferably in the form of a photographic silver halide emulsion, particularly a gelatino emulsion. Photographic silver bromide, silver bromoiodide, silver chlorobromide, silver chlorobromoiodide, silver chloride and other photographic silver halides capable of forming a surface latent image are examples of useful photographic silver halides. Generally the iodide content of the photographic silver halide is less than 10 mole percent silver iodide based on total silver halide.
[0024] The silver halide grains, when the silver halide emulsions are to be used for lith applications, preferably have a mean grain size of not larger than 0.7 micron, particularly less than about 0.7 micron. Silver coating coverages for photographic elements according to the invention generally are within the range of about 0.5 to about 10 grams per square meter of support.
[0025] Higher contrast images can be achieved by means of relatively monodispersed silver halide emulsions. Monodispersed emulsions have a large proportion of the silver halide grains falling within a narrow size-frequency distribution. Monodispersed silver halide emulsions herein mean those silver halide emulsions in which at least 90 percent (by weight or by number) of silver halide grains are within plus or minus 40 percent of the mean grain size.
[0026] Emulsion layers are useful having silver halide grains of any conventional geometric form, such as regular cubic or octahedral crystalline form, can be prepared by a variety of techniques, for example single-jet, double-jet (including continuous removal techniques), accelerated flow rate and interrupted precipitation techniques known in the photographic art. Double-jet accelerated flow rate precipitation techniques are preferred for forming monodispersed emulsions. Sensitizing compounds, such as compounds of copper, thallium, cadmium, rhodium, tungsten, thorium, iridium and mixtures thereof, can be present during precipitation of the silver halide emulsion.
[0027] The silver halide emulsions also comprise a binder. The concentration of binder varies widely, but generally is within the range of about 20 to about 250 grams per mole of silver halide, preferably about 50 to about 100 grams per mole of silver halide.
[0028] The binder comprises a hydrophilic colloid. Useful hydrophilic colloids include naturally occurring materials such as proteins, protein derivatives, cellulose derivatives such as cellulose esters, gelatin such as alkali-treated gelatin or acid-treated gelatin, gelatin derivatives such as acetylated gelatin, phthalated gelatin and the like, polysaccharides such as dextran, gum arabic, zein, casein, pectin, collagen derivatives, collodion, agar-agar, arrowroot, albumin and the like.
[0029] The binder optionally comprises hydrophobic colloid and synthetic polymeric materials which are hydrophilic or water-insoluble or only slightly water-soluble, such as a polymeric latex. Such materials are useful as supplemental grain peptizers and carriers. The synthetic polymeric materials preferably comprise about 20 to about 80 percent by weight of the binder.
[0030] Useful synthetic polymeric materials are selected from, for example, poly(vinyl lactams), acrylamide polymers, polyvinyl alcohol and its derivatives, polyvinyl acetyls, polymers of alkyl and sulfoalkyl acrylates and methacrylates, hydrolyzed polyvinyl acetates, polyamides, polyvinyl pyridine, acrylic acid polymers, maleic anhydride copolymers, polyakylene oxides, methacrylamide copolymers, polyvinyl oxazolidinones, maleic acid copolymers, vinylamine copolymers, methacrylic acid copolymers, acryloyloxyalkylsulfonic acid copolymers, sulfoalkylacrylamide copolymers, polyalkyleneimine copolymers, polyamides, N,N-dialkylaminoalkyl acrylates, vinyl imidazole copolymers, vinyl sulfide copolymers, halogenated styrene polymers, amineacrylamide polymers, polypeptides and the like. The binders described in connection with the emulsions are also useful in forming other layers of the photographic element, such as undercoating layers, interlayers and overcoating layers. Typically the binders are hardened with one or more photographic hardeners.
[0031] Addenda known to be useful in photographic silver halide emulsions, particularly those known to be useful in lith type photographic silver halide emulsions, are useful in the photographic silver halide emulsion layers. Such addenda are described in, for example, Research Disclosure, December 1978, Item 17643, published by Kenneth Mason Publications, Ltd., The Old Harbourmaster's, 8 North Street, Emsworth, Hampshire P0107DD, England; Canadian Patent 1,146,001, and U.S. Patent 4,269,929.
[0032] The photosensitive silver halide grains need not be chemically sensitized; however, the advantages of the invention are emphasized when chemically sensitized photosensitive silver halide grains are present in the photographic element. The photographic silver halide can be chemically sensitized by means of methods and compounds known in the photographic art. Such methods and compounds are described in, for example, Research Disclosure, December 1978, Item 17643 and Canadian Patent 1,146,001.
[0034] The nucleation development control agents are useful in any location during processing in the photographic element which enables the nucleation development control agent to be in reactive association with the photosensitive silver halide grains thereby enabling increased image discrimination and reduced image development spread. The nucleation development control agent can be in the silver halide emulsion layer, and/or in any other adjacent layer, such as an overcoat layer, emulsion layer, interlayer or undercoat layer, which enables the nucleation development control agent to be in such reactive association. A preferred location of the nucleation development control agent is in the developer solution; however, when the nucleation development control agent is in the photographic element prior to processing, it is preferably in a layer contiguous to the silver halide emulsion layer in order to insure that the nucleation development control agent does not adversely affect the sensitometric properties of the silver halide emulsion layer. The nucleation development control agent can be in the photographic element and/or a developer solution for processing the photographic element.
[0035] The nucleation development control agent is present in the developer solution and/or in the photographic element in any concentration which is sufficient to increase image discrimination and reduce image development spread beyond unexposed silver halide grains in close proximity to exposed silver halide grains, as described. This concentration is typically within the range of 1 x 10-4 to 3 x 10 -1 moles of nucleation development control agent per liter of development when the nucleation development control agent is in the developer, preferably with the range of 1 x 10 -3 to 3 x 10 moles per liter. The concentration of nucleation development control agent is typically within the range of 1 x 10-4 to 1 x 10 -1 moles of nucleation development control agent per mole of silver when the nucleation development control agent is present in the element, preferably 1 x 10-4 to 1 x 10-1 moles per mole of silver. An optimum concentration of nucleation development control agent can be selected depending upon such factors as the particular nucleation development control agent, the particular developer composition, the processing conditions, particular silver halide, other components in the photographic element, desired image and location of the nucleation development control agent in the element and/or in the developer.
[0036] A preferred photographic element comprises a nucleating agent which is a hydrazine nucleating agent as described in Canadian Patent 1,146,001. An example of such a hydrazine nucleating agent is represented by the formula:
wherein R1 is a phenyl nucleus having a Hammett sigma value-derived electron withdrawing characteristic of less than +0.30. Hammett sigma values are known in the organic compound art, such as described in Research Disclosure, October 1974, Item 12617 and Canadian Patent 1,146,001.
[0037] R1 can take the form of a phenyl nucleus which is either electron donating (electropositive) or electron withdrawing (electronegative); however, phenyl nuclei which are highly electron withdrawing produce inferior nucleating agents. The electron withdrawing or electron donating characteristic of a specific phenyl nucleus can be assessed by reference to Hammett sigma values. The phenyl nucleus can be assigned a Hammett sigma value-derived electron withdrawing characteristic which is the algebraic sum of the Hammett sigma values of its substituents (i.e., those of the substituents, if any, to the phenyl group). For example, the Hammett sigma values of any substituents to the phenyl ring of the phenyl nucleus can be determined algebraically simply by determining from the literature the known Hammett sigma values for each substituent and obtaining the algebraic sum thereof. Electron withdrawing substituents are assigned negative sigma values. For example, in one preferred form R can be a phenyl group which is unsubstituted. The hydrogen atoms attached to the phenyl ring each have a Hammett sigma value of 0 by definition. In another form the phenyl nuclei can include halogen ring substituents. For example, ortho- or para-chloro or fluoro substituted phenyl groups are specifically contemplated, although the chloro and fluoro groups are each mildly electron withdrawing.
[0038] Preferred phenyl group substituents are those which are not electron withdrawing. For example, the phenyl groups can be substituted with straight or branched chain alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-hexyl, n-octyl, tert-octyl, n-decyl and n-dodecyl. The phenyl groups can be substituted with alkoxy groups wherein the alkyl moieties thereof can be chosen from among the alkyl groups described above. The phenyl groups can also be substituted with acylamino groups. Illustrative acylamino groups include acetylamino, propanoylamino, butanoylamino, octanoylamino and benzoylamino.
[0039] In one particularly preferred form the alkyl, alkoxy and/or acylamino groups are in turn substituted with a conventional photographic ballast group, such as the ballasting moieties of incorporated couplers and other immobile photographic emulsion addenda. The ballast groups typically contain at least eight carbon atoms and can be selected from both aliphatic and aromatic relatively unreactive groups, such as alkyl, alkoxy, phenyl, alkylphenyl, phenoxy, alkylphenoxy and similar groups.
[0040] The alkyl and alkoxy groups, including ballasting groups, if any, preferably contain from 1 to 20 carbon atoms, and the acylamino groups, including ballasting groups, if any, preferably contain from 2 to 21 carbon atoms. Generally, up to about 30 or more carbon atoms in these groups are contemplated in their ballasted form. Methoxyphenyl, tolyl, such as p-tolyl and m-tolyl, and ballasted butyramido- phenyl nuclei are specifically preferred.
[0041] Although preferred hydrazine nucleating agents contain a formyl moiety, it is appreciated that otherwise comparable hydrazine compounds containing a benzoyl moiety which is substituted with a highly electron withdrawing substituent, such as a cyano group, are operative. Such compounds have, however, been found to be inferior to the hydrazine compounds containing a formyl moiety.
[0042] The following are illustrative of specifically preferred hydrazine nucleating agents useful in the practice of this invention:
D-1 1-Formyl-2-phenylhydrazine
D-2 1-Formyl-2-(4-methoxyphenyl)hydrezine
D-3 1-Formyl-2-(4-chlorophenyl)hydrazine
D-4 1-Formyl-2-(4-fluorophenyl)hydrazine
D-5 1-Formyl-2-(2-chlorophenyl)hydrazine
D-6 1-Formyl-2-(p-tolyl)hydrazine
D-7 1-Formyl-2-{-(2-,4-di-tert-pentylphenoxy)-butyramido]phenyl hydrazine
D-8 1-[4-(2-Formylhydrazino)phenyl]-3-[4-(2,4-di- tert-pentylphenoxy)butyl]urea
D-9 1-[4-(2-Formylhydrazino)phenyl]-3-hexylures
D-10 1-Formyl-2-(4-propoxyphenyl)hydrazine
D-11 1-Formyl-2-(4-octylthiophenyl)hydrazine
[0043] The hydrazine nucleating agent or combination of such agents are present in the photographic element in any concentration which enables nucleation development without adversely affecting the image, for example, in a concentration of from about 10-4 to about 10 -1 mole per mole of silver. A preferred quantity of the hydrazine compound is from 5 x 10-4 to about 5 x 10 2 mole per mole of silver. Optimum results are obtained when the hydrazine nucleating agent or combination of such agents are present in a concentration of from about 8 x 10-4 to about 5 x 10 -3 mole per mole of silver.
[0044] The hydrazine nucleating agent can be incorporated in a silver halide emulsion used in forming the photographic element. Alternatively the hydrazine compound can be present in a hydrophilic colloid layer of the photographic element, preferably a hydrophilic colloid layer which is coated to be contiguously adjacent to the emulsion layer in which the effects of the hydrazine nucleating agent are desired. The hydrazine nucleating agent can, of course, be present in the photographic element distributed between or among emulsion and hydrophilic colloid layers, such as undercoating layers, interlayers, and overcoating layers.
[0045] The layers of the photographic element can be coated on any support that is useful in the photographic art.
[0046] The photographic elements can be imagewise exposed with various forms of energy that enable formation of a developable image in the photographic silver halide Exposures can be monochromatic, orthochromatic or panchromatic.
[0047] The photographic silver halide contained in the photographic elements can be processed following exposure to form a visible image by associating the silver halide with an aqueous alkaline medium in the presence of a developing agent contained in the medium and/or the element. Processing formulations and techniques are known in the photographic art.
[0048] The photographic elements can be processed in conventional developers or specialized developers conventionally employed in conjunction with lith photographic elements to obtain very high contrast images provided that the nucleation development control agent is present in the developer and/or the photographic element. When the photographic elements contain incorporated developing agents, the elements can be processed in an activator, which can be identical to the developer in composition, but lacking a developing agent. Very high contrast images can be obtained at pH values in the range of from 11 to 12.3, preferably 11.3 to 12.0. Higher pH levels can, of course, also be used, although storage stability of the developer is reduced. It is also an advantage that relatively high contrast images can be obtained with concentrations of preservatives which help reduce aerial oxidation of the developing agents, such as alkali sulfites, for example sodium or potassium sulfite, bisulfite or metasulfite. This allows the developers to be stored for longer periods. Any preservative or preservative concentration conventional in lower contrast processing can be employed, such as, for instance, a sulfite ion concentration in the range of from about 0.15 to 1.2 mole per liter of developer.
[0049] Generally, any conventional developer composition can be employed. The photographic elements can, of course, be processed with conventional developers for lith photographic elements, as illustrated by Masseth U.S. Patent 3,573,914 and VanReusel U.K. Patent 1,376,600.
[0050] The developers are typically aqueous solutions, although organic solvents, such as diethylene glycol, can also be included to facilitate the solvency of organic components. The developers contain one or a combination of conventional developing agents, such as a polyhydroxybenzene, aminophenol, ara-phenylenediamine, ascorbic acid, pyrazolidone, pyrazolone, pyrimidine, dithionite, hydroxylamine or other conventional developing agents. It is preferred to employ hydroquinone and 3-pyrazolidone developing agents in combination. The pH of the developers can be adjusted with alkali metal hydroxides and carbonates, phosphates, borax and other basic salts. To reduce gelatin swelling during development, compounds such as sodium sulfate can be incorporated into the developer. Also, compounds such as sodium thiocyanate can be present to reduce granularity. Also, chelating and sequestering agents, such as ethylenediaminetetraacetic acid or its sodium salt, can be present.
[0051] The nucleation development control agent is useful in any silver halide developer solution useful for nucleation development of an exposed photographic silver halide element. An example of a preferred developer solution in which a nucleation development control agent is useful is described in U.S. Patent 4,269,929. A useful developer solution is, for example,
[0054] Such a developer comprises, at a pH of 10 to 12, a dihydroxybenzene silver halide developing agent, a 3-pyrazolidone silver halide developing agent, a sulfite preservative, a contrast promoting amount of an amino compound, and an effective concentration of a water-soluble nucleation development control agent according to the invention. Such a developer is particularly useful as a lith developer, that is a developer that is particularly useful in providing high contrast black-and-white silver images in a black-and-white photographic silver halide element ) designed to produce high contrast silver images.
[0055] Such developers are useful with various photographic silver halide emulsions, including high contrast silver chloride emulsions and/or other types of photographic silver halide emulsions, such as silver 5 bromoiodide emulsions.
[0056] A developer solution comprising a nucleation development control agent can also contain addenda known in the photographic art to be useful in photographic developer solutions. For example, the developer solution can contain solvents, buffers, sequestering agents, development accelerators, agents which reduce swell- ing of emulsion layers, hardeners, and the like.
[0057] A highly preferred process of high contrast development of an exposed photographic silver halide element as described comprises the step of:
developing the exposed photographic silver halide element in a silver halide aqueous alkaline developer solution comprising an effective concentration of a nucleation development control agent at a pH of at least 10. The developer solution in this process preferably comprises:
(i) an alkaline activator, such as KOH,
(ii) a dihydroxybenzene silver halide developing agent, such as hydroquinone,
(iii) a sulfite preservative, such as sodium sulfite or potassium sulfite,
(iv) an antifoggant concentration of an antifoggant, such as a methylbenzotriazole or mercaptotetrazole, and
(v) a nucleation development control agent, preferably an isothiuronium compound nucleation development control agent,
in a concentration sufficient to increase image discrimination and reduce image development spread beyond unexposed silver halide grains in close proximity to exposed silver halide grains in the photographic element.
[0058] Processing is carried out by means of manual processing or an automatic processor, such as a deep tank roller transport processor known in the photographic art. Processing temperature can be ambient or elevated, for example, a temperature within the range of about 19°C to about 43°C.
Example 1
[0060] A photographic film was prepared comprised of a poly(ethylene terephthalate) film support having coated thereon a silver bromoiodide gelatino emulsion (97.5 mole % silver bromide, 2.5 mole % silver iodide; coated at 43.1 mg of Ag/dm 2 and 26.9 mg gelatin/dm2). The silver bromoiodide gelatino emulsion was chemically sensitized by means of sulfur and gold compounds and spectrally sensitized by means of a spectral sensitizing dye to provide ortho spectral sensitivity. In addition to conventional coating aids and adjuvants, the following addenda were mixed with the emulsion prior to coating:
[0062] Strips of the resulting photographic film were imagewise exposed to light through a sensitometric continuous wedge and a screened test object by means of a white light tungsten light source to provide a developable latent image in the photographic film. Following the imagewise exposure step, the film strips were then developed for two minutes, with continuous agitation, at 32.2°C in an aqueous developer containing the following components:
[0063] Sufficient 50% NaOH to provide a pH of 11.25. After tray development in the above developing solution, the strips of film were fixed, washed and dried.
[0064] Following Table I provides the maximum and minimum diffuse transmission density values for the examples with the thiuronium compound noted in the left column added to the developer:
[0066] The dot quality values were based on a scale of 1 to 10 wherein 1 was unacceptably poor quality and 10 is excellent quality.
[0067] The data in Table I indicate that the nucleation development control agents No. 4 and No. 5 provide unexpectedly increased image discrimination. In addition, the halftone dot quality is unexpectedly improved.
Example 2
[0068] This illustrates use of a nucleation development control agent with a photographic silver chlorobromide emulsion which has been iridium-doped.
[0069] The procedure described in Example 1 was repeated with the exception that an ortho spectrally sensitized but chemically unsensitized photographic silver chlorobromide gelatino emulsion (20 mole % AgCl and 80 mole % AgBr) which was doped by means of K3IrBr6 and subsequently doctored with 11 potassium iodide per silver mole was used in place of the photographic silver bromoiodide gelatino emulsion of Example 1. The exposed photographic film strips were developed for one minute at 32.2°C. The results are summarized in following Table II.
[0070] These results further illustrate the improved image discrimination and dot quality provided by inclusion of the described nucleation development control agent.
Example 3
[0071] A photographic silver halide film was prepared as follows:
A poly(ethylene terephthalate) film was 2 coated with a gelatin layer (12.9 mg/dm2) containing 0.4 mg/dm 2 of 5-methylbenzotriazole (antifoggant), over which were coated two thin layers of an iridium-doped, ortho spectrally sensitized but chemically unsensitized gelatino silver bromoiodide emulsion (97.5 mole % AgBr; 2.5 mole % AgI) each layer containg 21.5 mg/dm 2 of Ag and 13.2 mg/dm2 of gelatin. The resulting film was then overcoated with a gelatin layer (16.1 mg of gelatin/dm2). The silver bromoiodide emulsion also contained the same ballasted phenylhydrazide development nucleator as in
Example 1.
[0072] The resulting photographic film was sensitometrically exposed to light to produce a developable latent image in the emulsion layers. The exposed photographic film was then developed for four minutes at 32.2°C by means of a developer composition the same as described in Example 1 except that the pH was changed from 11.25 to 11.45. The results of Example 3 are given in following Table III:
Examples 4-7
[0073] A photographic film was prepared as follows:
A subbed poly(ethylene terephthalate) film support was coated with a layer of a chemically unsensitized, but ortho spectrally sensitized silver bromoiodide gelatino emulsion (97.5 mole % AgBr, 2.5 mole % AgI) (43.0 mg/dm 2 of Ag; 26.4 mg/dm2 of gelatin) containing the 0.011 mg/dm 2 of the ballasted phenylhydrazide development nucleator D-8. The emulsion layer also contained other addenda as described in Example 1. The resulting photographic film was then overcoated with a gelatin overcoat (21.5 mg/dm2).
[0074] The resulting photographic film was sensitometrically exposed to light to produce a developable latent image in the film. The exposed film was then developed for two minutes at 32.2°C in a developer composition identical to that described in Example 1, except that the developer contained 1.41 x 10-2 M liter of the compounds listed in column A in following Table IV:
[0075] The results in Table IV demonstrate the improved image discrimination and improved dot quality provided by the developers containing nucleation development control agents.
[0076] The procedure described in this example was repeated with the exception that the described film samples after exposure were developed to establish a time series rather than being developed for a fixed time. The results obtained with and without (control) the addition of 3 grams/liter of Compound 4 are summarized in following Table V:
[0077] The relative speed obtained by development for one minute with the control developer was arbitrarily set at 100. This value was used as a reference to determine the relative speed obtained with the modified developer. The addition of Compound C-4 produced a loss in speed (sensitivity); however, the lower speed for the film containing Compound C-4 was not considered unsatisfactory in light of the fact the film speed remained basically constant even though development time was significantly changed in the series of tests. The maximum density, minimum density and dot quality remained basically constant for the film containing Compound C-4 which illustrates the excellent nucleation development control which a nucleation development control agent according to the invention provides.
Example 9
[0079] In this example the film was the same as Example 1 and the developer (containing Compound C-4) was the same as Example 6 with the exception that the concentration of the 2-diethylaminoethanol was reduced from 20 to 10 ml/liter.
[0080] In this example strips of the photographic film were imagewise exposed to an x-ray beam source through a 10 micron line test object. The resulting exposed film was then developed at 32.2°C in the developer composition with the addition of 3 grams per liter of nucleation development control agent Compound C-4. The results are summarized in folowing Table VI:
[0081] The information in Table VI indicates that the developed image line width is significantly less for the films developed in the developer composition containing Compound C-4 compared to the developed image line width for the control.
Examples 9-10
1. A negative working photographic element comprising a support bearing a photographic
silver halide emulsion layer comprising photosensitive silver halide grains capable
of forming a surface latent image and a nucleating agent in a concentration sufficient
to increase contrast and sufficient to promote infectious, imagewise development of
unexposed silver halide grains in close proximity to exposed silver halide grains,
characterized in that the element contains in the emulsion layer or a layer adjacent
thereto, a nucleation development control agent that is an isothiuronium compound
or a free mercaptan in a concentration sufficient to increase image discrimination
and reduce image development spread beyond unexposed silver halide grains in close
proximity to exposed silver halide grains.
2. A negative working photographic element as in claim 1 wherein the nucleation development
control agent is an isothiuronium compound represented by the formula:
wherein
wherein
R is alkylene containing 1 to 5 carbon atoms.
3. A negative working photographic element as in claim 1 wherein the nucleation development
control agent is
4. A process of development of an exposed photographic element comprising a support
bearing a photographic silver halide emulsion layer comprising photosensitive silver
halide grains capable of forming a surface latent image, and a nucleating agent in
a concentration sufficient to increase contrast and sufficient to promote infectious,
imagewise development of unexposed silver halide grains in close proximity to exposed
silver halide grains characterized in that the process comprises the step of: developing
the photographic silver halide element in reactive association with a nucleation development
control agent which is an isothiuronium compound or a free mercaptide in a concentration
sufficient to increase image discrimination and reduce image development spread beyond
unexposed silver halide grains in close proximity to unexposed silver halide grains.
5. A process as in claim 4 wherein the process comprises the step of: developing the
photographic silver halide element in a silver halide aqueous alkaline developer solution
at a pH of at least 10 comprising
(i) an alkaline activator,
(ii) a dihydroxybenzene silver halide developing agent,
(iii) a sulfite preservative,
(iv) an antifoggant concentration of an antifoggant, and
(v) a nucleation development control agent which is an isothiuronium compound or a free mercaptide in a concentration sufficient to increase image discrimination and reduce image development spread beyond unexposed silver halide grains in close proximity to exposed silver halide grains in said element.
6. A process as in claim 4 wherein the nucleation development control agent is an
isothiuronium compound represented by the formula:
wherein
wherein
R is alkylene containing 1 to 5 carbon atoms.
7. A process of high contrast development of an exposed photographic element comprising
a support bearing a photographic silver halide emulsion layer comprising chemically
sensitized photosensitive silver bromoiodide grains capable of forming a surface latent
image, and a hydrazine nucleating agent in a concentration sufficient to increase
contrast and sufficient to promote infectious, imagewise development of unexposed
silver bromoiodide grains in close proximity to exposed silver bromoiodide grains
characterized in that the process comprising the step of:
developing the silver halide element in a silver halide aqueous alkaline developer solution at a pH of at least 10 comprising
(i) an alkaline activator,
(ii) a dihydroxybenzene silver halide developing agent,
(iii) a 3-pyrazolidone silver halide developing agent,
(iv) an antifoggant concentration of an antifoggant,
(v) sulfite preservative, and
(vi) a nucleation development control agent in a concentration sufficient to (1) increase
image discrimination and (2) reduce image development spread beyond unexposed silver
bromoiodide grains in close proximity to exposed silver bromoiodide grains in said
element, wherein the nucleation development control agent is:
8. An aqueous alkaline silver halide developer solution for high contrast development
of photographic elements comprising photosensitive silver halide grains capable of
forming a surface latent image, and a nucleating agent in a concentration sufficient
to increase contrast and sufficient to promote infectious, imagewise development of
unexposed silver halide grains in close proximity to exposed silver halide grains;
characterized in that the developer solution comprises at a pH of at least 10:
(i) an alkaline activator,
(ii) a dihydroxybenzene silver halide developing agent,
(iii) a 3-pyrazolidone silver halide developing agent,
(iv) an antifoggant concentration of an antifoggant,
(v) sulfite preservative, and
(vi) a nucleation development control agent in a concentration sufficient to (1) increase
image discrimination and (2) reduce image development spread beyond unexposed silver
bromoiodide grains in close proximity to exposed silver bromoiodide grains in said
element, wherein said nucleation development control agent compound is: