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(11) | EP 0 181 728 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Light-sensitive silver halide photographic material |
| (57) 57 A light-sensitive silver halide photographic material having on a substrate at
least one silver halide emulsion layer and at least one hydrophilic colloid layer,
wherein a triphenyltetrazolium compound represented by the following General Formula
(1) is incorporated in at least one of said silver halide emulsion layer and said
hydrophilic colloid layer. General Formula (I):
wherein R1, R2 and R3 each represent a hydrogen atom or a group showing a negative value in Hamett's sigma value (σp). and X9 represents an anion; except that R1, R2 and R3 are hydrogen atoms at the same time. The light-sensitive silver halide photographic material is useful in lithography for forming dot images having very high contrast and also stable as being free from detorioration of its performance during storage under high temperature and high humidity. |
BACKGROUND OF THE INVENTION
[0001] This invention relates to a novel light-sensitive silver halide photographic material used for formation of photographic images. More particularly, it relates to a novel light-sensitive silver halide photographic material which is capable of forming dot images of high contrast and has high usefulness in the filed of lithography.
[0002] Heretofore, photographic images of very high contrast have been known to be formed by use of a light-sensitive silver halide photographic material. For instance, known is a method in which dot images or line originals of high contrast is obtained by treating a light-sensitive silver halide photographic material comprising a silver chlorobromide or silver chloroiodide emulsion which contains fine grains of silver halide grains having a mean grain size of about 0.5 p or less, having a narrow grain size distribution and uniform grain size, and has the content of silver chloride being, e.g., 50 moles or more, with use of an alkaline developing solution having low sulfite ion concentration and containing only hydroquinone as a developing agent.
[0003] This kind of light-sensitive silver halide photographic emulsion is known as a lith type light-sensitive silver halide photographic material, which is generally used during the lithographic procedures to convert the variation in concentrations of continuous gradation in an original to the aggregation of dots having larger to smaller areas in proportion to the concentrations. For such convertion, the lith type light-sensitive silver halide photographic material is used, whereby dot images are formed by photographing an original through means of a cross line screen or a contact screen, and then carrying out development with use of a so-called lith developer, or a lith type developing solution, which has very low sulfite ion concentration and, in addition, contains only a hydroquinone developing agent. Gamma of this lith type light-sensitive silver halide photographic material is 5 or 6 at most even when processed by an ordinary developing solution having high sulfite ion concentration, e.g., a commercially available developing solution for processing a photographic paper, thereby frequently generating fringes which must be prevented with utmost care for the purpose of the dot formation. Accordingly, it has been considered essential for the material to be used in combination with the above lith type developing solution when it is used for the halftone negative - positive. This lith type developing solution, which is disclosed in detail in J. A. C. Yule: J. Franklin Institute, Vol. 239, page 221 (1945), contains substantially only hydroquinone as a developing agent, and is a developing solution which plays a role as an antioxidant for the developing agent, having low sulfite ion concentration.
[0004] Such developing solution has inferior preservativity and is subject to autoxidation. Accordingly, in order for lithographers to obtain halftone negative and halftone positive immages always having high quality, it is required to control the developing solution to keep constant its degree of activity which may have decreased with lapse of time, thereby inevitably being accompanied with troublesome operations.
[0005] Since advantages from improvement in the preservativity of the lith type developing solution are very great, enormous efforts have been made for such improvement. However, the improvement having been made was absolutely insufficient as compared with developing solutions having high preservativity, such as Metol/hydroquinone developing solution and Phenidone/hydroquinone developing solution which are developing solutions for continuous tone.
[0006] Now, several attempts have been made to provide a method of forming high contrast images suitable for lithography development by use of a phenidone/hydroquinone type developing solution having high sulfite iron concentration. For instance, Japanese Unexamined Patent Publication No. 106244/1981 discloses that the high contrast images can be obtained by using a hydrazine compound and incorporating into a developing solution an amino compound in an amount by which the development may be promoted. Also, Japanese Patent Publications No. 17825/1984, No. 17818/1984, No. 17819/1984, No. 17820/1984, No. 17821/1984, No. 17826/1984, No. 17822/1984, etc. disclose light-sensitive silver halide photographic materials containing a tetrazolium compound.
[0007] However, in the former art using the hydrazine compound, it is required to adjust the pH of the developing solution to as high as about 12, and therefore there is a problem in the stability of the solution. Moreover, black dots called black pepper are generated at non-image portions, thereby causing serious drawbacks in the practical use.
[0008] Also, the tetrazolium compound disclosed in the latter arts, which, however, has no drawback as in the former art, can not be said to be very satisfactory in the light of high contrastiness and dot quality. This means that there is in fact a background that no prior art materials can be said to have attained sufficient performance corresponding to the recent trend to the remarkable improvements in the field of lithography. Thus, it has been sought after to make further improvement in the method for formation of high contrast images with use of the tetrazolium compound.
SUMMARY OF THE INVENTION
[0009] It is an object of this invention to provide a light-sensitive silver halide photographic material which may solve the above-mentioned problems in the silver halide emulsions employing the tetrazolium compound, and which has very high contrast and also is stable as being free from detorioration of its performance during storage under high temperature and high humidity.
[0010] As a result of intensive studies, the present inventors found that the above problems can be solved by providing a light-sensitive silver halide photographic material having on a substrate at least one silver halide emulsion layer and at least one hydrophilic colloid layer, wherein a triphenyltetrazolium compound represented by the following General Formula (I) is incorporated in at least one of said silver halide emulsion layer and said hydrophilic colloid layer, whereupon this invention has been accomplished.
[0011] General Formula (I):
wherein R1, R2 and R3 each represent a hydrogen atom or a group showing a negative value in Hamett's sigma value (σp), and X⊖ represents an anion; except that R1, R2 and R3 are hydrogen atoms at the same time.
[0012] Also, a light-sensitive silver halide photographic material which is stable as being free from detorioration of its performance even during storage under high temperature and high humidity, can be obtained by providing a light-sensitive silver halide photographic material having on a substrate at least one silver halide emulsion layer and at least one hydrophilic colloid layer, wherein the silver halide grains contained in said silver halide emulsion layer are those formed in the presence of a water soluble rhodium salt used in an amount of 1 x 10-7 to 5 x 10-7 mole per mole of silver halide and, at the same time, at least one triphenyltetrazolium compound represented by the following General Formula (I)' is incorporated in said at least one hydrophilic colloid layer.
[0013] General Formula (I)':
wherein R , R and R3 each represent a hydrogen atom or a group showing a negative value in Hamett's sigma value (ap), and X⊖ represents an anion; except that R1, R2 and R3 are hydrogen atoms at the same time.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] As mentioned above, it is required in this invention that the subsitutents R1, R2 and R3 in the phenyl groups of the triphenyltetrazolium compound represented by General Formula (I) or (I)' represent a hydrogen atom or a group showing a negative value in Hamett's sigma value (ap) which indicates an electron withdrawing degree, namely, an electron withdrawing group.
[0015] Hamett's sigma value in the phenyl substitution is seen from a number of papers, for instance, a report by C. Hansch et al, disclosed in Journal of Medical Chemistry, vol. 20, page 304, 1977. Groups having the negative sigma value may inlude, for example, methyl group (σp = -0.17; hereinbelow all in σp value), ethyl group (-0.15), cyclopropyl group (-0.21), n-propyl group (-0.13), iso-propyl group (-0.15), cyclobutyl group (-0.15), n-butyl group (-0.16), iso-butyl group (-0.20), n-pentyl group (-0.15), cyclohexyl group (-0.22), amino group (-0.66), acetylamino group (-0.15), hydroxyl group (-0.37), methoxyl group (-0.27), ethoxyl group (-0.24), propoxyl group (-0.25), butoxyl group (-0.32), pentoxyl group (-0.34), etc. These are useful as the substituents for the compound of General Formula (I) or (I)' of this invention.
[0016] Of the compounds according to General Formulae (I) and (I)', preferable compounds are the componds having the total carbon atom numbers when the respective carbon atom numbers in the substituents R1, R2 and R3 are totaled, of 4 or less, preferably 2 or less, in the light of the dot quality. Also, it is preferable that Rl, R2 and R3 are each substituted at the para position of the phenyl ring. On the other hand, also preferable are the compounds in which at least one of these substituents is a hydrogen atom, more specifically, any one of R1, R2 and R3 is a hydrogen atom, more preferably, R1 is a hydrogen atom. When any one of Rl, R2 and R3 is a hydrogen atom, it is preferred that at least one of the remaining two substituents represents an alkyl group. When both the two substituents are alkl groups, it is preferred that both of them are alkyl groups having the same carbon atoms, and it is further preferred that they are the same alkyl group.
[0017] Specific examples of the compounds represented by General Formula (I) or (I)' used in this invention inlude, but are by no means limited by, the following:
[0019] The tetrazolium compound used in this invention can be readily synthesized by a method dislcosed, for instance, in Chemical Reviews, Vol. 55, pp.335-483.
[0020] The tetrazolium compound of this invention may preferably be used in an amount ranging from about 1 mg to about 10 g, preferably from about 10 mg to about 2 g, and more preferably from about 10 mg to about 1 g, per mole of the silver halide contained in the light-sensitive silver halide photographic material of this invention.
[0021] The light-sensitive silver halide photographic material according to this invention comprises a substrate and at least one silver halide emulsion layer and at least one hydrophilic colloid layer provided by coating on the substrate. This silver halide emulsion layer may be either directly coated on the substrate or coated thereon by interposing a hydrophilic colloid layer containing no silver halide emulsion, and the hydrophilic colloid layer may be either coated on the silver halide emulsion layer or coated as a protective layer between the substrate and the silver halide emulsion layer. Further, the silver halide emulsion layers, when provided in plurality, may comprise silver halide emulsion layers each having different sensitivity, e.g., high sensitivity and low sensitivity. In this occasion, the silver halide emulsion layers may be provided between the layers with an intermideate layer of a hydrophilic colloid layer, or may be provided with an intermediate layer between a silver halide emulsion layer and a protective layer. The layer in which the tetrazolium compound of this invention is incorporated is the silver halide emulsion layer and/or the above-mentioned various kind of hydrophilic colloid layers.
[0022] The most preferred embodiment of this invention is a light-sensitive silver halide photographic material in which the tetrazolium compound of this invention is incorporateded in the silver halide emulsion layer and also the hydrophilic colloids contained in the silver halide emulsion layer and the hydrophilic colloid layer are gelatin derivatives.
[0023] In order to incorporate the tetrazolium compound of this invention in the silver halide emulsion layer and/or the hydrophilic colloid layer, there may be employed a method in which the tetrazolium compound is added by dissolving it in a suitable aqueous and organic solvent; a method in which the compound is added by dissolving it in a suitable aqueous and organic solvent and then mixing in a matrix of a hydrophilic colloids such as gelatin or gelatin derivatives, or after dispersing it in a latex. Any of these method may be employed in this invention.
[0024] The tetrazolium compound used in this invention can attain preferable image properties when used singularly. Also, this tetrazolium compound does not adversely affect the image properties even when two or more kinds of the compound are used in combination at an appropreate proportion. Further, the tetrazolium compound of this invention and the other tetrazolium compounds outside this invention may also be used in combination at an appropreate proportion.
[0025] As a preferred embodiment of this invention, the tetrazolium compound according to this invention may be incorporated into a silver halide emulsion layer. In another preferred embodiment of this invention, it is incorporated into a hydrophilic colloid layer directly adjacent to a hydrophilic colloid layer containing a silver halide emulsion, or into an adjacent hydrophilic colloid layer by interposing an intermediate layer.
[0026] As a still another embodiment, the tetrazolium compound according to this invention may be incorporated into a light-sensitive silver halide photographic material by dissolving it in a suitable organic solvent, for example, alcohols such as methanol and ethanol, ethers, esters, etc., and then directly applying the mixture thus obtained on an outermost layer of silver halide emulsion layers of the light-sensitive silver halide photographic material.
[0027] In this invention, a particularly preferable result can be obtained when an anion is used in combination as it bonds to the tetrazolium compound of this invention to lower the hydrophilicity of the compound. Such anion may include, for example, acid radicals of inorganic acids such as perchloric acids, acid radicals of organic acids such as sulfonic acids and carboxylic acids, and anion type activators. More specifically, it may include lower alkylbenzenesulfonate anions such as p-toluensulfonate anion, p-dodecylbenzenesulfonate anions, alkylnaphtha- lenesulfonate anions, laurylsulfate anions, tetraphenyl- borates, dialkylsulfosuccinate anions such as di-2-ethylhexylsulfosuccinate anion, polyether alcohol sulfuric acid ester anions such as cetylpolyethenoxysulfate anion, stearate anion, polyacrylate anion, etc.
[0028] These anions may be previously mixed with the tetrazolium compound of this invention and thereafter added to a hydrophilic colloid layer. Alternatively, they may be added singularly to a silver halide emulsion layer or a hydrophilic colloid layer containing or not containing the tetrazolium compound of this invention.
[0029] The water soluble rhodium salt which may be used in this invention may include rhodium dichloride, rhodium trichloride, ammonium hexachlororhodate, etc., and preferably, a halogen complex compound of trivalent rhodium, e.g., hexachlororhodium (III) acid or its salt or rhodium trichloride trihydrate.
[0030] In this invention, the amount of adding the water soluble rhodium salt may be 1.0 x 10-7 to 5.0 x 10-7 mole per one mole of silver halide. When the water soluble rhodium salt is in less than 1.0 x 10-7 mole, the stability under high temperature and high humidity which is an aim in this invention will become insufficient. On the other hand, when it is in more than 5.0 x 10-7, the desensitizing effect by the watersoluble rhodium salt to the silver halide will increase as well known to a person skilled in the art, thereby making it difficult to obtain desired sensitivity.
[0031] In this invention, the water soluble rhodium salt may be present at the time of formation of silver halide grains. The words "the time of formation" is herein meant to be a course during which the silver halide is emulsified and subjected to physical ripening, and it may be added at an optional time during this course and by a conventional manner. However, it is preferably added at the time of emulsification. More preferable is a method in which an emulsion is prepared by adding the water soluble rhodium salt in a halide solution. The distribution of rhodium ions in the silver halide emulsion should preferably be uniform for each of the silver halide grains. There is no particular limitation for its distribution in one grain, and its distribution at the surface of a grain and the inside of the grain may be uniform or its distribution may be partial to the surface side or the inside.
[0032] The silver halide used in the light-sensitive silver halide photographic material of this invention is preferably silver chlorobromide having the AgCl/AgBr ratio of 100/0 to 2/98, particularly preferably the one having the AgCl/AgBr ratio of 90/10 to 50/50.
[0033] Also, the silver halide grains are preferably of monodispersed type, having a mean grain size of from 0.15 µm to 0.40 µm and a grain size distribution coefficient, represented by (standard deviation in grain size distribution)/(mean grain size), of 15 % or less.
[0034] Preferably, the silver halide emulsion layer according to this invention may be prepared in the following manner. Namely, the silver halide emulsion in the silver halide emulsion layer may be prepared by a method of preparing a silver halide photographic emulsion by adding in an aqueous solution of hydrophilic colloid an aqueous solution of a water soluble silver salt and an aqueous solution of a water soluble halide in accordance with a double jet method, wherein said aqueous solution of a water soluble silver salt and said aqueous solution of a water soluble halide are added at an addition rate such that the rate of growth of silver halide grains in said aqueous solution of hydrophilic colloid does not exceed the critical growth rate, and EAg value of said aqueous solution of hydrophilic colloid is kept at substantially constant value set within the range of from 140 mV to 200 mV during a period corresponding to one-thirtieth (1/30) to one-fifth (1/5) of the whole addition period from initiation of mixing and, thereafter, kept at substantially constant value set within the range of from 80 mV to 140 mV during a period corresponding to at least a half (1/2) of the whole addition period.
[0035] The words "the rate of growth of silver halide grains does not exceed the critical growth rate" means that the supersaturated concentration at which new nuclei of silver halide grains are generated is not ocurred in a solution.
[0036] The critical growth rate herein mentioned can be determined by actually forming crystals in an actual system while varying the rate of addition of various silver ions and halogen ions, and making sampling from a reaction vessel to confirm the presence or absence of the generation of new nuclei by an electron microscopic observation.
[0037] The EAg value is a concept well known to a person skilled in the art, designating a silver potential which is indicated by a value measured with use of a metal silver electrode and a double junction type saturated Ag/Cl reference electrode.
[0038] For instance, the EAg value is disclosed in Japanese Unexamined Patent Publication No. 197534/1982.
[0039] The silver halide used in this invention may be sensitized by use of various kinds of chemical sensitizers. The sensitizers may include, for example, active gelatins, sulfur sensitizers (such as sodium thiosulfate, arylthiocarbamide, thiourea and arylisothiacyanate), selenium sensitizers (such as N,N-dimethylselenourea and selenourea), reduction sensitizers (such as triethylenetetramine and stannic chloride) and various noble metal sensitizers typically exemplified by potassium chloroorite, potassium orithiocyanate, potassium chloroorate, 2-orosulfobenzothiazol methylchloride, ammonium chloropalladate, potassium chloroplatinate, sodium chloropalladite, etc. Each of them may be used singularly or in combination of two or more kinds. When gold sensitizers are used, ammonium thiocyanate may be used as an auxiliary.
[0040] The silver halide emulsion used in this invention may be subjected to optical sensitization with use of one or more of sensitizing dyes to impart sensitivity to each of the desired light-sensitive wavelength region. The sensitizing dyes to be used may include various ones, and the optical sensitizing dyes advantageously usable in this invention may inlclude cyanines, merocyanines, trinulear or tetranuclear merocyanines, trinuclear or tetranuclear cyanines, styryls, holopolar cyanines, hemicyanines, oxonols, hemioxonols, etc. These optical sensitizing dyes are preferably those which contain in a part of the structure a basic radical such as thiazoline and thiazole or a nucleus such as rhodanine, thiohydanto- in, oxazolidinedione, berbituric acid, thioberbituric acid and pyrazolone, as a nitrogen-containing heterocyclic nucleus. Such nucleus may undergo alkyl, hydroxyalkyl, halogen, phenyl, cyano or alkoxy substitution. Also, these optical sensitizing dyes may have undergone condensation with a carbocyclic ring or a heterocyclic ring. When the above optical sensitizing dyes, in particular, the merocyanine type sensitizing dyes are used, an effect of widening the development latitude can be obtained in addition to the optical sensitization.
[0041] Also, the silver halide emulsion used in this invention may be stabilized by use of the compounds disclosed, for instance, in U.S. Patents No. 2,444,607, No. 2,716,062 and No. 3,512,982, West German Patent Publications No. 1,189,380, No. 2,058,626 and No. 2,118,411, Japanese Patent Publication No. 4133/1968, U.S. Patent No. 3,342,569, Japanese Patent Publication No. 4417/1972 No. 4417/1972, West German Patent Publication No. 2,149,789, Japanese Patent Publications No. 2825/1964 and No. 13566/1974; preferably, for example, 5,6-trimethylene-7-hydroxy-s-triazolo(1,5-a)pyrimidine, 5,6-tetramethylene-7-hydroxy-s-triazolo-(l,5-a)pyrimidine, 5-methyl-7-hydroxy-s-triazolo(l,5-a)pyrimidine, 7-hydroxy-s-triazolo(l,5-a)pyrimidine, 5-methyl-6-bromo-7-hydroxy-s-triazolo(l,5-a)pyrimidine, gallates (such as isoamyl gallate, dodecyl gallate, propyl gallate and sodium gallate), mercaptans (such as 1-phenyl-5-mercaptotetrazole and 2-mercaptobenzothiazole), benzotriazoles (such as 5-brombenzotriazole and 5-methylbenzotriazole), benzimidazoles (such as 6-nitrobenzimidazole).
[0042] The above silver halide and the tetrazolium compound may be present in a hydrophilic colloid layer, and the hydrophilic colloid particularly advantageously usable in this invention is gelatin. Hydrophilic colloids other than gelatin may include, for example, colloidal albumin, agar, gum arabic, alginic acid, hydrolyzed cellulose acetate, acrylamide, imidized polyamide, polyvinyl alcohol, hydrolyzed polyvinyl acetate, gelatin derivatives such as phenylcarbamyl gelatin, acylated gelatin and phthalated gelatin as disclosed in U.S. Patents No. 2,614,928 and No. 2,525,753, or graft polymers obtained by attaching to gelatin a copolymerizable monomer having an ethylene group, such as styrene acrylate, acrylate, methacrylic acid and methacrylate, as disclosed in U.S. Patents No. 2,548,520 and No. 2,831,767. These hydrophilic colloids may be applied to a layer containing no silver halide, for example, an antihalation layer, a protective layer, an intermediate layer, etc.
[0043] The substrate, or support material, used in this invention typically includes, for example, a baryta paper, a polyethylene-coated paper, a polypropylene synthetic paper, a glass plate, cellulose acetate, cellulose nitrate, a polyester film such as polyethyleneterephthalate, a polyamide film, a polypropylene film, a polycarbonate film, a polystyrene film, etc. These substrates are each selected optionally depending on the intended use of the light-sensitive silver halide photographic material.
[0044] The light-sensitive material according to this invention has, on the support material as mentioned above, at least one layer selected from the group of silver halide emulsion layer and hydrophilic colloid layer, wherein the tetrazolium compound of this invention is incorporated in said at least one layer. However, it is most preferred for the light-sensitive material to have the structure that the hydrophilic colloid layer is coated as a protective layer on the silver halide emulsion layer to have a desired film thickness, preferably of from 0.1 to 10 µm, particularly preferably from 0.8 to 2 µm.
[0045] In the silver halide emulsion layer and the hydrophilic colloid layer used in this invention, there may be optionally used various kind of photographic additives, for example, a gelatin plasticizer, a hardening agent, a surface active agent, an image stabilizing agent, a ultraviolet absorbent, an antistain agent, a pH adjuster, an antioxidant, an antistatic agent, a thickner, a graininess improver, a dyestuff, a moldant, a whitening agent, a development rate regulator, a matt agent, etc., so far as the effect of the invention is not impaired.
[0046] Of the above mentioned additives, those which are particularly preferably usable in this invention are, as the thickner or the plasticizer, the substances disclosed, for instance, in U.S. Patent No. 2,960,404, Japanese Patent Publication No. 4939/1968, West German Patent Publication No. 1,904,604, Japanese Unexamined Patent Publication No. 63715/1973, Japanese Patent Publication No. 15462/1970, Belgium Patent No. 762,833, U.S. Patent No. 3,767,410 and Belgium Patent No. 558,143, for example, a styrene/sodium maleate copolymer, dextran sulfate, etc.; the hardening agent may include an aldehyde type, an epoxy type, an ethyleneimine type, an active halogen type, a vinylsulfone type, an isocyanate type, a sulfonate type, a carbodiimide type, a mucochloric acid type and an acyloyl type hardening agents; the ultraviolet absorbent may include the compounds disclosed, for instance, in U.S. Patent No. 3,253,921 and British Patent No. 1,309,349, in particular, 2-(2'-hydroxy-5-tertiary butyl phenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tertiary butyl phenyl)- benzotriazole, 2-(2-hydroxy-3-tertiary butyl-5-butyl phenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di- tertiary butyl phenyl)-5-chlorobenzotriazole, etc; the dyestuff may include the compounds disclosed, for instance, in U.S. Patent No. 2,072,908, West German Patent No. 107,990, U.S. Patent No. 3,048,487 and U.S. Patent No. 515,988. These compounds may be contained in the protective layer, the emulsion layer or the intermediate layer. Further, the surface active agent which is used as a coating assistant, an emulsifier, an improver for permeability to treatment solutions, a defoaming agent or an agent to control various physical properties of light-sensitive materials may include the compounds disclosed in British Patents No. 548,532 and No. 1,221,980, U.S. Patents No. 2,992,101 and No. 2,956,884, French Patent No. 1,395,544 and Japanese Patent Publication No. 43125/1973, in particular, silica gel having grain size of 0.-5 to 20 µm, a polymer of polymethylmethacrylate having grain size of 0.5 to 20 µm, etc.
[0047] The light-sensitive silver halide photographic material containing the tetrazolium compound of this invention in the silver halide emulsion layer and/or the hydrophilic colloid layer can be developed in the presence of a compound represented by General Formula (II) below.
[0048] General Formula (II):
wherein R1 represents a nitro group at the 5- or 6-position, R2 represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, M represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom or a cation such as ammonium ion.
[0049] The compound represented by General Formula (II) may include, for example, 5-nitroindazole, 6-nitroindazole, etc., to which, however, this invention is by no means limited.
[0050] The compound represented by General Formula (II) may be added to a developing solution by dissolving it in an organic solvent such as diethylene glycol, triethylene glycol, ethanol, diethanolamine and triethanolamine, an alkali such as sodium hydroxide, an acid such as acetic acid, or may be added directly without such a procedure.
[0051] The compound represented by General Formula (II) may be contained in the concentration within the range of from about 1 mg to 1000 mg, preferably from about 50 mg to 300 mg, per one liter of the developing solution.
[0052] As a developing agent for the black and white light-sensitive silver halide photographic material according to this invention, the following may be mentioned. This developing agent may be used in combination with the above-mentioned compound represented by General Formula (II).
[0053] HO-(-CH=CH-)n-OH type developing agents: Typical example is hydroquinone. Other examples are catechol, pyrogallol and its derivatives, ascorbic acid, chlorohydroquinone, bromohydroquinone, isopropylhydroquinone, toluhydroqui- none, methylhydroquinone, 2,3-dichlorohydroquinone, 2,5-dimethylhydroquinone, 2,3-dibromohydroquinone, 2,5-dihydoxyacetophenone, 2,5-diethylhydroquinone, 2,5-di-p-phenethylhydroquinone, 2,5-dibenzoylamino- hydroquinone, 4-chlorocatechol, 3-phenyl-catechol, 4-phenyl-catechol, 3-methoxy-catechol, 4-acetyl- pyrogallol, 4-(2-hydroxybenzoyl)pyrogallol, sodium ascorbate, etc..
[0054] HO-(-CH=CH-)n-NH2 type developing agents: Typical example is ortho- or para-aminophenol or aminopyra- zolone. It include 4-aminophenol, 2-amino-6-phenylphenol, 2-amino-4-chloro-6-phenylphenol, 4-amino-2-phenylphenol, 3,4-diaminophenol, 3-methyl-4,6-diaminophenol, 2,4-diaminoresorcinol, 2,4,6-triaminophenol, N-methyl-p-aminophenol, N-β-hydroxyethyl-p-aminophenol, p-hydroxyphenylaminoacetic acid, 2-aminonaphthol, etc.
[0055] H2N-(-C=C-)n-NH2 type developing agents: They include, for example, 4-amino-2-methyl-N,N-diethyl-aniline, 2,4-diamino-N,N-diethylaniline, N-(4-amino-3-methylphenyl)-morpholine, p-phenylenediamine, 4-amino-N,N-dimethyl-3-hydroxyaniline, N,N,N,N-tetramethylpara- phenylenediamine, 4-amino-N-ethyl-N-(β-hydroxyethyl)-aniline, 4-amino-3-methyl-N-ethyl-N-(6-hydroxyethyl)-aniline, 4-amino-N-ethyl(β-methoxyethyl)-3-methylaniline, 4-amino-3-methyl-N-ethyl-N-(β-methylsulfone- amidoethyl)aniline, 4-amino-N-butyl-N-y-sulfobutyl- aniline, 1-(4-aminophenyl)-pyroridine, 6-amino-l-ethyl, 1,2,3,4-tetrahydroquinone, 9-aminojulolidine, etc.
[0056] Hetero ring type developing agents: These include 3-pyrazolidones such as 1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-4-methyl-4-hydroxymethyl-3-pyrazolidone and 1-phenyl-4-methyl-4-hydroxymethyl-3-pyrazolidone; 1-phenyl-4-amino-5-pyrazolone, 1-(p-aminophenyl)-3-amino-2-pyrazoline, 1-phenyl-3-methyl-4-amino-5-pyrazolone, 5-aminouracil, etc.
[0057] Besides the foregoing, the developing agents as disclosed in The Theory of the Photographic Process, Fourth Edition, pp 291-334, and Journal of The American Chemical Society, Vol. 73, page 3,100 (1951) may be effectively used in this invention. These developing agents may be used singularly or in combination of two or more kinds, but more preferred is to use two or more kinds.
[0058] Further, in the developing solution used in this invention, sulfite such as potassium sulfite and ammonium sulfite may be used as a preservative. Even if it is used, the effect of this invention will not be damaged, and this can be said to be one of the features of this invention. Hydroxylamines and hydrazide compounds may also be used as the preservative. In addition, it may be optioanlly carried out to control the pH of, and impart buffer action to, the developing solution by using alkali hydroxide, alkali carbonate or amine which is usually used in a black and white developing solution, and to add an inorganic development restrainer such as potassium bromide and an organice development restrainer such as benzotriazole, or to add an agent of capturing metal ions, such as ethylenetetradiamine (IV) acetic acid, a development accelarator such as methanol, ethanol, benzylalcohol, polyalkyleneoxide, a surface active agent such as sodium alkylarylsulfonate, natural saponin, saccarides and an alkyl ester of the above compound, a hardening agent such as glutaraldehyde, formalin and glyoxal, and an ion strength regulator such as sodium sulfate.
[0059] The developing solution used in this invention may further contain alkanol amines and glycols as organic solvents. The alkanol amines include, for example, monoethanol amine, diethanol amine and triethanol amine, and preferably used is triethanol amine. These alkanol amines may be used in an amount of 5 to 500 g, preferably 20 to 200 g, per one liter of the developing solution. Also, the above glycols include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, 1,4-butandiol, 1,5-pentandiol, etc., and preferably used is diethylen glycol. The glycols may be used in an amount of 5 to 500 g, preferably 20 to 200 g, per one liter of the developing solution. These organic solvents may be used singularly or in combination.
[0060] The light-sensitive silver halide photographic material according to this invention can achieve sensitivity characteristics very excellent in the storage stability by processing with use of the developing agent containing such a development restrainer as mentioned above.
[0061] The developing agent to be composed according to the above-mentioned has the pH value of 9 to 12, but a preferable pH value is 10 to 11 in the light of the preservability and the photographic characteristics.
[0062] The light-sensitive silver halide photographic material according to this invention may be processed under various conditions. As to the processing temperature, the developing temperature, for instance, is preferably 500C or lower, particularly preferably, 30°C or lower. The development may be completed in 3 minutes in general, particularly preferably in 2 minutes to often bring about desired results. Further, optionally employable processing steps other than the development are, for example, water wahing, stopping, stabilizing, fixing, and further optionally, prehardening, neutralization, etc., which may be omitted accordingly. Still further, these processing steps may be carried out in either the so-called development by hand such as dish development and frame development or the mechanical development such as roller development and hanger auto development.
Example 1
[0064] Silver chlorobromide emulsions were prepared by use of the following solutions, Solution A, Solution B and Solution C.
[0068] After keeping Solution A at 40oC, sodium chloride was added so as to give the EAg value of 160 mV.
[0069] Next, Solution B and Solution C were added by a double jet method using a mixing stirrer disclosed in Japanese Unexamined Patent Publications No. 92523/1982 and No. 92524/1982.
[0070] The addition of these solutions were carried out by gradually increasing the flow rate as shown in Table 1 over a whole addition period of 80 minutes while keeping constant the EAg value.
[0071] EAg value was changed from 160 mV to the EAg value of 120 mV after 5 minutes from the beginning of the addition by using 3 ml/lit. of an aqueous solution of sodium chloride. Thereafter this value was maintained until the mixing was completed.
[0072] To keep the EAg value constant, the EAg was controlled by using 3 moles/lit. aqueous solution of sodium chloride.
In measurement of the EAg value, used were a silver metal electrode and a double junksion type saturated Ag/AgCl reference electrode (To constitute the electrode was used a double juncsion disclosed in Japanese Unexamined Patent Publication No. 197534/1982.).
[0073] Also, in adding Solution B and Solution C was used a roller tube quantitative pump of a flow rate variable type (a pump capable of controlling the flow rate).
[0074] During the addition, electron microscopic observations were performed by sampling of the emulsions to confirm that no generation of new grains was recognized in the system.
[0075] Also during the addition, the system was controlled by use of a 3 % aqueous solution of nitrous acid to keep constant the pH value therein at 3.0.
[0076] After completion of the addition of Solution B and Solution C, the emulsion was subjected to Ostwald ripening, followed by desalting and water washing by a conventional method. Thereafter, 600 ml of an aqueous solution of ossein gelatin (containing 30 g of ossein gelatin) were added for dispersion with stirring at 55°C for 30 minutes to prepare 750 cc of the emulsion.
[0077] Thereafter, the emulsion was subjected to gold sulfur sensitization, and as a stabilizer 6-methyl-4-hydroxy-1,3,3a,7-tetrazaindene was added thereto. Further added as a sensitizing dye was 1-(8-hydroxyethyl)-3-phenyl-5-[(3-y-sulfopropyl-a-benzoxazolidine)-ethylidene]thio- hydantoin in an amount of 150 mg per one mole of Ag (hereinafter ".../Ag 1 mole"). The thus optically sensitized emulsion were divided into 20 fractions, to each of which was added a substituted triphenyltetrazolium chloride as shown in Table 2 at the addition rate of 700 mg/Ag 1 mole, to which further added were sodium triisopropylnaphthalenesulfonate in 600 mg/Ag 1 mole, saponin in 3.5 g/Ag 1 mole and a styrene/maleic acid copolymer in 2 g/Ag 1 mole, and then the emulsions were each applied on a polyethyleneterephthalate film by coating to have the thickness of Ag 4.0 g/m2. Further, as a protective layer, a gelatin layer (gelatin 1.2 g/m2) containing diethylsuccinate sulfonic acid (10 mg/m2) as a spreading agent and formalin (25 mg/m2) as a hardening agent was overlapped by coating, and then dried to obtain samples (Samples 1 to 20).
[0078] As shown in Table 2, Sample Nos. 1 to 10 are samples according to this invention, each containing a tetrazolium salt having the substituent of which the σp value is negative. In Sample No. 11, there is no substituent. Sample Nos. 12 to 20 are comparative samples each containing a tetrazolium salt having the substituent of which the ap value is positive, namely, CF3 (σp = 0.54), N02 (0.78) and COCH3 (0.50).
Two pieces were taken out from each of the samples obtained, one of which pieces was subjected to stepwise exposure by tangusten light while applying optical wedge with use of a sensitometer, and the other of which was subjected to halftone exposure by xenon light with use of a contact screen GN Type R (150L) produced by Dainippon Screen Mfg. Co., Ltd.
[0079] The above sample pieces were processed by means of a automatic processing machine having a developing tank of 40 lit. capacity, using a developing solution according to the prescriptions mentioned below and a commercially available fixing solution.
Composition A
[0083] When using the developing solution, the above were dissolved in 500 ml of pure water in the order of Composition A and Composition B to make up one liter.
[0084] Of the samples having been developed, as for the samples applied with the wedge exposure, photographic characteristic curves were drawn to measure the exposure range at toe portion and the gamma. The exposure range at toe portion was indicated by the exposure range from 0.1 to 0.5 in optical density (log E value) and the gamma was indicated by tan 0 value of straight line portion ranging from 1.0 to 2.5 in optical density.
[0085] As for the samples on which xenon light was used to carry out halftone photography with use of a lithographic camera, dot quality of the dots formed was evaluated.
[0086] The dot quality was evaluated by a five stage indication system in which a dot being small in fringe was indicated as 5 when the state of fringe (or fading) observed at the periphery of dots was visually judged as to the so-called 50 % dots which are equal in the dot portion area and the clear portion area. Namely, "5" means to be excellent and "1" means to be very poor. When the 50 % dot quality is not more than "3", such value can not in general be made acceptable.
[0087] Results of the above are shown in Table 3.
As shown in Table 3, the substitued triphenyltetrazolium compound of this invention resulted in very good toe sharpness (or toe chopping) and dot quality. All of Sample Nos. 12 to 20 in which the phenyl substituents are electron withdrawing groups are quite insufficient for use as light-sensitive materials for lithography. Also, Sample No. 11 wherein triphenyltetrazolium chloride is used is applicable, though unsatisfactorily, to practical use. However, the difference in its performance is clear when compared with those employing the compound of this invention.
[0088] Thus, the light-sensitive silver halide photographic material according to this invention, containing the tetrazolium compound having the electron donative substituent can achieve very high contrast and high dot quality, and has properties particularly excellent for the lithography.
Example 2
[0089] Silver chlorobromide emulsions were prepared by use of the following solutions, Solution A, Solution B and Solution C.
[0093] While keeping Solution A at 40°C, Solution B and Solution C were added by a double jet method with stirring by use of a mixing stirrer disclosed in Japanese Unexamined Patent Publications No. 92523/1982 and No. 92524/1982.
[0094] The addition of each of Solutions A and B was carried out by gradually increasing the flow rate as shown in Table 4 over a period of 80 minutes to form silver halide grains. EAg value of the emulsions was kept at 160 mV for the initial 5 minutes of the mixing, and adjusted to 120 mV after 5 minutes from the beginning of the mixing by using 3 moles/lit. of an aqueous solution of sodium chloride. Thereafter this value was maintained by the aqueous solution of sodium chloride.
[0095] After completion of the addition of Solution B and Solution C, the emulsion was subjected to Ostwald ripening, followed by desalting and water washing by a conventional method. Thereafter, 600 ml of an aqueous solution of ossein gelatin (containing 30 g of ossein gelatin) were added for dispersion with stirring at 55°C for 30 minutes to prepare 750 cc of the emulsion.
[0096] In measurement of the EAg value, used were a silver metal electrode and a double junction type saturated Ag/AgCl reference electrode (To constitute the electrode was used a double junction disclosed in Japanese Unexamined Patent Publication No. 197534/1982.).
[0097] Also, in adding Solution B and Solution C was used a roller tube quantitative pump of a flow rate variable type.
[0098] During the addition, electron microscopic observations were performed by sampling of the emulsions to confirm that no generation of new grains was recognized in the system.
[0099] Also during the addition, the system was controlled by use of a 3 % aqueous solution of nitrous acid to keep constant the pH value therein at 3.0.
[0100] Emulsions EM-1 to EM-7 were prepared while varying the amount of rhodium trichloride trihydrate in Solution C as shown in Table 5.
[0101] Electron microscopic observations on Emulsions EM-1 to EM-7 thus obtained were made to determine the side lengthwise mean grain size. As a result, all the samples showed cubic crystals and very good monodispersity.
[0102] These emulsions were subjected to gold sulfur sensitization, and as a stabilizer 6-methyl-4-hydroxy-1,3,3a,7-tetrazaindene was added thereto. Further added as a sensitizing dye was 1-(8-hydroxyethyl)-3-phenyl-5-((3-γ-sulfopropyl-α-benzoxazolidine)-ethylidene]thio- hydantoin in an amount of 150 mg per one mole of Ag.
[0103] Next, 2,3-di-p-toryl-5-phenyltetrazolium chloride (Exemprary Compound (2)) in amount of 700 mg, sodium p-dodecylbenzene sulfonate in amount of 400 mg, saponin in amount of 3.5 g and a styrene/maleic acid copolymer in amount of 2 g per one mole of Ag, respectively, were added to the emulsions, which were applied on substrates by coating so as to have the Ag amount of 4.0 g/m2 and the gelatin amount of 2.0 g/m2. Simultaneously, as a protective layer, a gelatin layer containing 30 mg/m2 of sodium 1-decyl-2-(3-isopentyl)succinate-2-sulfonate as a spreading agent and 25 mg/m2 of formalin as a hardening agent was overlapped by coating so as to have the gelatin amount of 1.2 g/m2).
[0104] Samples thus obtained were divided into two groups, one of which was left as it is, and the other of which was, after humidity-controlled at 25°C and relative humidity of 80 %, hermetically wrapped with a water-proof packaging material and heated at 50°C for 72 hours, in order to evaluate the stability of the performance. Both groups of the samples were applied with optical wedge and carried out the exposure by use of a tungsten light source.
[0105] The above test samples were processed by means of a automatic processing machine having a developing tank of 40 lit. capacity, using a developing solution according to the prescriptions mentioned below and a commercially available fixing solution.
Composition A
Composition B
[0110] When using the developing solution, the above were dissolved in 500 ml of pure water in the order of Composition A and Composition B to make up one liter.
[0111] As for the samples having been developed, photographic characteristic curves were drawn to measure the sharpness at the toe portion. The sensitivity was determined from a reciprocal number of the amount of exposure required for giving 2.5 in opotical density, and indicated by a relative sensitivity when the sensitivity of a sample prepared by use of EM-4 is regarded as 100. Also, the sharpness at the toe portion was indicated by the exposure region (log E value) of 0.1 to 0.5 in optical density. The smaller this value is, it means that the sample has desired characteristics as being excellent in the sharpness of the toe portion.
[0113] As shown in Table 6, it is seen that the emulsion according to this invention is an emulsion having very high contrast and of less deterioration of the performance under high temperature and high humidity. Also, EM-6 and EM-7 containing a large amount of water-soluble rhodium salt has a considerable difficulty in obtaining the sensitivity suited for practical uses.
Example 3
[0114] Samples having been coated with emulsions were obtained in the same manner as in Example 2 by using EM-4 used in Example 2, except that those which are shown in Table 7 were used as the tetrazolium salts to be used when a coating solution is prepared. The samples were subjected to halftone stepwise exposure by xenon light with use of an optical wedge. Developments were carried out in the manner according to Example 2 to evaluate the sensitivity and the quality of dot (dot quality) of each of the samples.
[0115] The Hamett's sigma values of the substituents in the above compound are: -CH3 (-0.17)" -OCH3 (-0.27), -CF3 (0.54), -N02 (0.78) and -COCH3 (0.50).
[0116] The dot quality was evaluated by a five stage indication system in which a dot being small in fringe was indicated as 5 when the state of fringe (or fading) observed at the periphery of dots was visually judged as to the so-called 50 % dots which are equal in the dot portion area and the clear portion area. Namely, "5" means to be excellent and "1" means to be very poor. When the 50 % dot quality is not more than "3", such value can not in general be made acceptable.
[0117] Further, the sensitivity was calculated from the amount of exposure required for forming 95 % dot concentration, and indicated by a relative sensitivity when the sensitivity of Sample No. 1 is regarded as 100.
[0118] Results of the above are shown in Table 8.
As shown in Table 8, it is seen that Samples 1 to 4 obtained in accordance with this invention have excellent dot quality as compared with Samples 5 to 8, and of far less detorioration of performance under high temperature and high humidity.
[0119] As is apparent from the foregoing Examples, the light-sensitive silver halide photographic material according to this invention has very high contrast and shows excellent dot quality when the halftone exposure is carried out. The stability of the quality with time lapse during storage is also very good.
1. In a light-sensitive silver halide photographic material having on a substrate
at least one silver halide emulsion layer and at least one hydrophilic colloid layer,
the improvement wherein a triphenyltetrazolium compound represented by the following
General Formula (I) is incorporated in at least one of said silver halide emulsion
layer and said hydrophilic colloid layer.
General Formula (I):
wherein R1, R2 and R3 each represent a hydrogen atom or a group showing a negative value in Hamett's sigma
value (σP), and X⊖ represents an anion; except that R1, R2 and R3 are hydrogen atoms at the same time.
2. The light-sensitive silver halide photographic material according to Claim 1, wherein
the compound represented by General Formula (I) is a compound represented by General
Formula (I)' shwon below:
General Formula (I)':
wherein R1. R2 and R3 each represent a hydrogen atom or a group showing a negative value in Hamett's sigma
value (σp), and X⊖ represents an anion; except that R1, R2 and R3 are hydrogen atoms at the same time.
3. The light-sensitive silver halide photographic material according to Claim 1, wherein
the compound represented by General Formula (I) is a compound represented by General
Formula (I)" shown below:
General Formula (I)":
wherein R1, R2 and R3 each represent a hydrogen atom or a group showing a negative value in Hamett's sigma
value (σp), and X⊖ represents an anion; except that R1, R2 and R3 are hydrogen atoms at the same time.
4. The light-sensitive silver halide photographic material according to Claim 1, wherein
any one of the substituents R1, R2 and R3 is a hydrogen atom.
5. The light-sensitive silver halide photographic material according to Claim 4, wherein
remaining two substituents in any of Rl, R2 and R3 other than the hydrogen atom are each an alkyl group.
6. The light-sensitive silver halide photographic material according to Claim 5, wherein
said two substituents are R2 and R3.
7. The light-sensitive silver halide photographic material according to Claim 5, wherein
each of said alkyl groups has the same carbon atoms.
8. The light-sensitive silver halide photographic material according to Claim 7, wherein
said alkyl groups are the same with each other.
9. The light-sensitive silver halide photographic material according to Claim 1, wherein
the total carbon atom numbers of the substituents R1, R2 and R3 in General Formula (I) is 4 or less.
10. The light-sensitive silver halide photographic material according to Claim 9,
wherein the total carbon atom numbers of the substituents R1, R2 and R3 in General Formula (I) is 2 or less.
11. The light-sensitive silver halide photographic material according to Claim 1,
wherein the compound represented by General Formula (I) is contained in the light-sensitive
silver halide photographic material in an amount of about 1 mg to about 10 mg per
one mole of silver halide.
12. The light-sensitive silver halide photographic material according to Claim 1,
wherein the X in General Formula (I) is an anion which lowers the hydrophilicity of
the compound of General Formula (I).
13. The light-sensitive silver halide photographic material according to Claim 1,
wherein the silver halide emulsion in said silver halide emulsion layer is silver
chlorobromide having the AgCl/AgBr ratio of 100/0 to 2/98.
14. The light-sensitive silver halide photographic material according to Claim 1,
wherein the silver halide emulsion in said silver halide emulsion layer has a mean
grain size of from 0.15 µm to 0.4 µm and a grain size distribution coefficient, represented
by (standard deviation in grain size distribution)/(mean grain size), of 15 % or less.
15. The light-sensitive silver halide photographic material according to Claim 1,
wherein the silver halide emulsion in said silver halide emulsion layer is prepared
by a method of preparing a silver halide photographic emulsion by adding in an aqueous
solution of hydrophilic colloid an aqueous solution of a water soluble silver salt
and an aqueous solution of a water soluble halide in accordance with a double jet
method, wherein said aqueous solution of a water soluble silver salt and said aqueous
solution of a water soluble halide are added at an addition rate such that the rate
of growth of silver halide grains in said aqueous solution of hydrophilic colloid
does not exceed the critical growth rate, and EAg value of said aqueous solution of
hydrophilic colloid is kept at substantially constant value set within the range of
from 140 mV to 200 mV during a period corresponding to one-thirtieth (1/30) to one-fifth
(1/5) of the whole addition period from initiation of mixing and, thereafter, kept
at substantially constant value set within the range of from 80 mV to 140 mV during
a period corresponding to at least a half (1/2) of the whole addition period.
16. The light-sensitive silver halide photographic material according to Claim 2,
wherein the silver halide grains contained in said silver halide emulsion layer are
formed in the presence of a water soluble rhodium salt used in an amount of 1 x 10-7 to 5 x 10-7 mole per mole of silver halide.
17. The light-sensitive silver halide photographic material according to Claim 15,
wherein the compound represented by General Formula (I)'is a compound represented
by General Formula (I)" shown below:
General Formula (I)":
wherein R1, R2 and R3 each represent a hydrogen atom or a group showing a negative value in Hamett's sigma
value (σp), and X⊖ represents an anion; except that R1, R2 and R3 are hydrogen atoms at the same time.
18. The light-sensitive silver halide photographic material according to Claim 15,
wherein said water soluble rhodium salt is a halogen complex compound of trivalent
rhodium.