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(11) | EP 0 391 356 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | High-speed light-sensitive silver halide photographic material having good graininess, and rapid processing method therefor |
| (57) A method for preparation of light sensitive silver halide emulsion and a photographic
material containing thereof are disclosed. The method comprises a step of adding to
a first silver halide emulsion a second silver halide emulsion containing a silver
halide grain having halide composition and a Bravais lattice that are different from
those of a silver halide grain of the first silver halide emulsion, and an aqueous
silver salt solution and an aqueous halide solution. The resulted silver halide emulsion
is suitable to provide a high-speed photographic material having a good grainess and
being capable of rapid processing. |
FIELD OF THE INVENTION
[0001] The present invention relates to a light-sensitive silver halide photographic material. It also relates to a rapid processing method used for such a light-sensitive material.
BACKGROUND OF THE INVENTION
[0002] With an increase in medical X-ray examinations, there is a strong demand for decreasing the radiation exposure, not only in the medical world but also as international public opinion. In order to comply with such a demand, it is needed to provide a photographic technique that may require a smaller radiation exposure and yet can achieve a high accuracy. For this reason, it has been sought to advance a technique that makes it possible to obtain a precise image using a small X-ray dose, i.e., a higher-speed photographic technique. At the same time, from the viewpoints of improving an accuracy in diagnosis, making preparations for emergencies, and also making short the time for everyday ordinary diagnosis, it is desired to make image quality higher and to make processing more rapid.
[0003] On the other hand, to cope with these demands, researches have been focused on a silver halide grain emulsion of a core/shell type having a silver iodide phase with a high silver iodide content, in particular, a silver iodide-rich core/shell grain containing 10 mol % or more of silver iodide in its inside.
[0004] For example, Japanese Patent Publications Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publications) No. 143331/1985, No. 3247/1987, and No. 7039/1987 disclose a core/shell emulsion having a high silver iodide content in the core. Japanese Patent O.P.I. Publications No. 35726/1985 and No. 198324/1985 also disclose a grain having in its inside a shell layer comprising a phase having been subjected to halogen substitution using an iodide.
[0005] Moreover, although the grains formed by growing silver halide using a soluble solution cause deterioration of graininess, the grains formed by the above halogen substitution can decrease the deterioration.
[0006] The decrease in the deterioration, however, can not be said to be satisfactory under the present circumstances in which an improvement of the graininess is desired.
[0007] On the other hand, as development time becomes shorter, an improvement of the graininess can be promised to a certain extent, accompanied by a lowering of density. This, however, can not be accepted as a matter of course in view of the demands for images.
[0008] On second thought, the formation, growth, in particular, growth to the core/shell grains, and preparation, of silver halide grains are roughly grouped into two types when viewed from the form of grain growth.
[0009] One of them is a system in which silver halide (hereinafter "AgX") is newly formed as amorphous fine grains in a suspending medium, the grains are brought to natural-selective growth by leaving them to the differences in the dissolution pressure that depends on i) the flocculating properties of fine grains turned to have relatively different sizes according to the locational fluctuation of formation conditions in the suspending medium and/or the time-sequential difference in formation time in the course that the fine grains are newly formed, ii) the solubility product and iii) the grain size, and the growth attributable to the dissolution pressure is made to chiefly take place as the surface activity to the flocculation is exhausted. This is herein called a dissolution pressure system. The step of the growth attributable to only the dissolution pressure is called the Ostwalt ripening.
[0010] Each grain of AgX crystal grains is presumed to undergo annealing, until the transition and other crystal defects are regulated to regular equilibrium. In regard to grains, however, the generation of new crystal nuclei necessarily brings about a broad grain distribution, and it is also difficult to assure uniformity in the compositional ratio of each AgX contained and the crystal form.
[0011] The other form of growth is a system in which, using as crystal growth nuclei the amorphous fine grains or crystal grains already present or existing in a suspending medium, newly formed AgX is cohesively adhered, or deposited, on their surfaces so that the existing grains may be coveringly enlarged. The grains are made to grow by feeding the newly formed AgX, necessarily in at least two stages, generally in multiple stages, or in a continuous form so that generation of new crystal nuclei can be prevented on account of the total surface areas of the existing grains.
[0012] In this system, not only the grains already having a stable size but also the originally newly formed inherent fine grains act as crystal growth nuclei on AgX successively newly formed, under control or adjustment of pAg, formation rate, or pH, so that a group of grains can be given which have grown with substantially uniform size.
[0013] A crystal-controlling agent may also be used in combination during the feeding of the newly formed AgX to the crystal growth nuclei, whereby the crystal phase can be reasonably arbitrarily selected.
[0015] As a method of preparing emulsions, it is optional to choose a method intermediate between the two typical methods described above, depending on the purpose.
[0016] In the steps for the preparation of these emulsions, the reaction by-products or excess compounds and additives resultingly dissolved and present in emulsions are removed when they may adversely affect the subsequent steps or the designing of characteristics. When they are removed, the coagulation method in which coagulating agents are commonly used is chosen in modern emulsion techniques.
[0017] Of the typical systems described above, the emulsions obtained by the dissolution pressure system may cause differences in the light receptivity, quantum efficiency, adhesion of additives, and developability because of the scattering of compositional ratio of AgX contained, between grains, and the differences in the surface condition of grains, thus bringing about a great scattering in the performance of finally finished emulsions.
[0018] The emulsions obtained by the crystal nucleus system can constitute a group of monodisperse grains, having uniform grain size and compositional ratio between grains and also capable of easy control of characteristics, therefore having a good reproducibility. Hence, they are widely used with admiration in recent years in which the demands for the photographic performance have become high and severe.
[0019] However, the monodisperse emulsions obtained by the use of crystal nuclei (seed crystals) according to the conventional crystal nucleus system are liable to be weak to pressure fog, to have a poor absorption of sensitizing dyes and to cause deterioration of graininess, depending on the concentration and distribution of silver iodide in grains, bringing about the disadvantage that the commercial value is impaired.
[0020] With a recent increase in the consumption of films, the processing for light-sensitive silver halide photographic materials is directed toward more rapid processing in answer to needs of users. This tendency is not exceptional in light-sensitive materials for medical use.
[0021] On the standpoint of the manufacturers, efforts have been made toward the achievement of rapid processing by making more active the halogen composition of light-sensitive materials themselves, or developing solution composition, and processing conditions.
[0022] However, as one of the problems that may accompany the achievement of more rapid processing, a stain may be produced on the resulting image. In particular, a processing time of about several seconds or less may result in an insufficiency of the time during which the coloring organic compounds added in a light-sensitive silver halide photographic material, for example, spectral sensitizers, anti-irradiation and antihalation dyes, and filter dyes are decolored and decomposed in a processing solution, or dissolved out of the light-sensitive material.
[0023] As a result, blotchy color stains remain on the silver image after the processing, so that not only no clear image can be obtained but also a serious negative effect leading to an erroneous diagnosis can be brought about in the case of light-sensitive materials for medical use.
[0024] In particular, it follows that the rapid processing for X-ray light-sensitive materials that require use of large quantities of coloring matters or dyes effective for the crossover cut, aiming at achievement of a high image quality, has very serious problems.
[0025] To cope with such difficulties, various proposals have been hitherto made. For example, it is known to give such structure that may make it easy for coloring matters or dyes to be dissolved out, or decrease the amount of a binder component, i.e., gelatin, in a light-sensitive material. Even with these techniques, however, no satisfactory results can be said to have been obtained in the recent rapid processing. Thus, in order to advance rapid processing, it has been strongly sought to give drastic settlement from the standpoint of the light-sensitive materials.
SUMMARY OF THE INVENTION
[0026] A first object of the present invention is to provide a high-speed light-sensitive silver halide photographic material having a good graininess.
[0027] A second object of the present invention is a method of preparing a silver halide emulsion used in the light-sensitive material.
[0028] A third object to the present invention is to provide a method of rapidly processing the above light-sensitive silver halide photographic material in a developing time of 20 seconds or less.
[0029] The method of preparing a silver halide emulsion of the present invention comprises the steps of adding, in a silver halide emulsion containing a silver halide grain with a small grain size, that serves as a seed;
i) a silver halide grain having silver halide composition and a Bravais lattice that are different from those of said seed; and
ii) an aqueous silver salt solution and an aqueous halide solution.
[0030] The addition of these brings about an increase in the grain size of seed grains. This is called "growth of seed grains". The resulting grains have the same Bravais lattice as the seeds.
[0031] The steps of adding i) and ii) may be simultaneously carried out, or any one of the steps may be started earlier than the other. In the step of adding i), the grains having the desired properties may be formed by adding silver halide grains separately prepared, or by adding in a short time an aqueous halide solution and an aqueous silver halide solution in an emulsion containing the seed grains. An example of the latter is shown in Em-3 in Example 1 described herein.
[0032] The grains thus obtained are used, after necessary steps, as a light-sensitive emulsion with the grain size as it stands. The grains may also optionally be grown to grains with a lager size by successively adding an aqueous halide solution and an aqueous silver halide solution. This process is called "shelling". The halide composition of shells formed by the shelling may be different from that of the original grains, but the Bravais lattice is so selected as to be identical.
[0033] Use of the above light-sensitive silver halide photographic material can attain rapid processing of a developing time of 20 seconds or less.
DETAILED DESCRIPTION OF THE INVENTION
[0034] It is known that AgX such as AgCI, AgBr, a mixed crystal of these, or AglBr containing up to 75 mol % of Agl forms a face-centered cubic lattice, and AgIBr comprising 90 mol % or more of Agl forms a hexagonal lattice. There are the above two kinds in the silver halide grain having a different silver halide composition and Bravais lattice, mentioned in the present invention. Since the Agl contained in a practical photographic emulsion is face-centered cubic, holding less than 75 mol % of the whole AgX, it is preferred to choose face-centered grains for the silver halide grains as the seed grains.
[0035] The hexagonal grains having a different Bravais lattice are converted into face-centered cubes by lattice conversion.
[0036] The grain growth in the present invention may be effected by any of the above dissolution pressure system and crystal nucleus system, but preferably by the crystal nucleus system in which seed crystals are used.
[0037] In obtaining the AgX photographic emulsion of the present invention, it is also possible to use a means by which a core/shell AgX emulsion is prepared by growing with a start from seed crystals, as in the method described in Japanese Patent O.P.I. Publication No. 138538/1985. In this case, there is a possibility that a grain has in its centeral part a region of a different halide composition from that of the core as a whole. In such an instance, the seed crystals may have halogen composition such as AgBr, AgBrl, AgICI, AgBrCI or AgCI, any of which can be used. Preferred is AgBrl having an Agl content of not more than 10 mol %, or AgBr.
[0038] In this instance, the seed crystals may also preferably hold a proportion of not more than 50 %, and particularly preferably not more than 10 %, in the whole AgX.
[0039] The broader the grain size distribution of the seed crystals is, the broader the grain size distribution of the grains having grown becomes. Hence, in order to obtain the monodisperse emulsion, it is preferred to use grains with a narrow grain size distribution at the stage of seed crystals.
[0040] The monodisperse emulsion thus obtained can be sufficiently subjected to a sensitizing treatment such as chemical sensitization, whereby a very high speed can be achieved, and, moreover, contrast reduction may occur only a little and contrast can be increased.
[0041] In the present invention, the silver iodide-rich hexagonal lattice grains that undergo the lattice conversion may be added prior to, or posterior to, the presence of the seed crystals in an emulsion mother liquor. They may be added according to rush addition or according to jet addition. The aqueous silver salt solution and the aqueous halide solution may be added according to the double-jet method or the triple-jet method.
[0042] The AgX photographic emulsion of the present invention may preferably have a pAg value of not more than 8.4, and more preferably not less than 7 and not more than 8.4, at the step of the addition of silver halide grains. It may also preferably have a pH value of not less than 9.8, and more preferably not less than 10 and not more than 11, at the time of internal phase growth.
[0043] The AgX grains of the above emulsion of the present invention may have any composition, as exemplified by silver halide such as silver chloroiodobromide or silver iodobromide.
[0044] The above emulsion of the present invention, or other emulsions optionally used in the light-sensitive material of the present invention, may be prepared by any method. For example, any of the acid method, the neutral method, and the ammoniacal method may be used. As the form of reacting a soluble silver salt with a soluble halide, any of the single-jet' precipitation, the double-jet precipitation, and a combination of these may be used. It is also possible to use a method in which grains are formed in the presence of excess silver ions (so-called reverse precipitation). A method in which the pAg in the mother liquor where AgX is produced is kept constant, i.e., so-called controlled double-jet method, can also be used as one form of the double-jet precipitation. Also preferred is a triple-jet method in which silver iodide has been added. As previously mentioned, this method makes it possible to obtain an AgX emulsion with regular crystal form and substantially uniform grain size.
[0045] In the present invention, two or more kinds of AgX emulsions separately formed may be used in a mixed form.
[0047] In the course of the formation of AgX grains or the physical ripening, a cadmium salt, a zinc salt, a lead salt, a thallium salt, an iridium salt or a complex salt thereof, a rhodium salt or a complex salt thereof, an iron salt, or an iron complex salt may also be made present together.
[0048] At the time of the formation of AgX grains, ammonia, thioether compounds, thione compounds, and so forth may be used as AgX solvents so that the growth of grains can be controlled.
[0049] In obtaining the emulsion, various compounds as exemplified by a crystal controlling agent, a stabilizer and a sensitizing dye may be made present together in the course of the formation of AgX by precipitation. This enables control of the properties of AgX grains.
[0050] In the present invention, there are no limitations on the time of addition (or position of addition) of the photographic dyes so long as they are added before completion of a desalting step, but they may preferably be added in the course of the physical ripening and/or in the course of the desalting step. They may more preferably be added after 50 % of silver used when the AgX is prepared has been added in the physical ripening and before the desalting step is completed. Particularly preferred is to add a spectral sensitizer in the desalting step. More preferred is to add the spectral sensitizer in the desalting step, thereafter add potassium iodide (KI) after chemical sensitization, and then again add a spectral sensitizer.
[0052] In general, AgX emulsions are commonly prepared through the step of forming AgX grains by means of double decomposition or the like of a soluble silver salt and a soluble halide in an aqueous gelatin solution, the step of physical ripening, the step of desalting, and also the step of chemical ripening.
[0053] In the desalting step, a series of operations of adding a coagulant, leaving the solution to stand, and carrying out decantation is carried out at least once, which is usually repeated several times, thereafter gelatin is commonly added and dispersed in the solution, and, after completion of the dispersion, the chemical ripening step follows.
[0054] There are various means for desalting, as exemplified by the noodle washing, known from old times, which is carried out by gelation of gelatin, and also the coagulation method (or flocculation) that utilizes inorganic salts comprising a polyvalent anion (for example, sulfates such as sodium sulfate), anionic surface active agents, anionic polymers (for example, polystyrene sulfonate), or gelatin derivatives (for example, aliphatic acylated gelatins, aromatic acylated gelatins, and aromatic carbamoylated gelatins).
[0055] In a preferred desalting means, sulfates (MgS04, NaS04-, etc.) are used as coagulants, or anionic polymers (polystyrene sulfonate polymers as described in Japanese Patent O.P.I. Publication No. 16086/1960, or vinyl polymers having a carboxylic acid on the side chain, as described in Japanese Patent O.P.I. Publication No. 32445/1987) are used.
[0056] Gelatins, in particular, those in which amino groups have been substituted, are known to cause coagulation depending on the pH, and this action can be utilized in desalting. The above pH may vary depending on the types of gelatins and the atmosphere. Commonly used is the pH near to the isoelectric point of gelatins, i.e., pH 1 to 5.
[0057] The pH for desalting in the present invention may not accord with the pH corresponding to the isoelectric point of gelatins, and may preferably be pH 3.0 to 9.5. It is also preferred to use any other gelatin coagulant in combination. In particular, it is effective to use a gelatin coagulant capable of readily coagulating the gelatins in the pH range according to the present invention.
[0058] As the gelatin coagulant used in the present invention, modified gelatins wherein 50 % or more of the amino groups in the gelatin molecule have been substituted can be advantageously used. Examples of substitution with respect of the amino groups of gelatins are described in U.S. Patents No. 2,691,582, No. 2,614,928, and No. 2,525,753.
[0059] Useful substituents include;
(1) acyl groups such as alkylacyl, arylacyl, acetyl, and substituted or unsubstituted benzoyl;
(2) carbamoyl groups such as alkylcarbamoyl and arylcarbamoyl;
(3) sulfonyl groups such as alkylsulfonyl and arylsulfonyl;
(4) thiocarbamoyl groups such as alkylthiocarbamoyl and arylthiocarbamoyl;
(5) straight or branched alkyl groups having 1 to 18 carbon atoms; and
(6) aryl groups such as substituted or unsubstituted phenyl or naphthyl, and aromatic heterocyclic rings such as pyridyl and furyl.
[0060] Particularly preferred gelatin coagulants are comprised of an acyl group (-COR ) or a carbamoyl group
[0061] The above RI and R each represent a substituted or unsubstituted aliphatic group as exemplified by an alkyl group having 1 to 18 carbon atoms, or an aryl group; and aryl group or an aralkyl group as exemplified by a phenethyl group. R2 represents a hydrogen atom, an aliphatic group, an aryl group or an aralkyl group. Particularly preferred is an instance in which RI is an aryl group and R2 is a hydrogen atom.
[0062] Examples of the gelatin coagulant are shown below by giving examples of amino group substituents.
[0064] There are no particular limitations on the amount for the addition of the gelatin coagulant used in desalting. However, the gelatin coagulant may suitably be added in an amount (by weight) of from 0.3 to 10 times, and particularly preferably in an amount (by weight) of from 1 to 5 times, the gelatin contained as a protective colloid at the time of desalting.
[0065] The coagulant used in the present invention include, for example, a polymeric coagulant represented by the following Formula I.
[0066] In the formula, R11 and R'2 may be the same or different, and each represent an alkyl group having 1 to 8 carbon atoms.
[0067] Z and Y each represent a -COOM group, a -COOR3 group, or a
group.
M represents a hydrogen atom, an alkali metal atom, or an ammonium group, and R3 represents an alkyl group having 1 to 20 carbon atoms, or an aryl group.
R4 and R5 each represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group, where R4 and R5 may combine each other to form a heterocyclic ring. The letter symbol n represents an integer of 10 to 104.
In the above Formula I, the alkyl group represented by R" and R12 includes alkyl groups having 1 to 8 carbon atoms, and may more preferably include those having 1 to 5 carbon atoms, as exemplified by a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group.
[0068] These alkyl groups may have a substituent. R3 represents an alkyl group having 1 to 20 carbon atoms, preferably including those having 1 to 12 carbon atoms, as exemplified by a methyl group, an ethyl group, a butyl group, a pentyl group, a heptyl group, an octyl group, and dodecyl group. These alkyl groups may have a substituent that can be substituted.
[0069] The aryl group include, for example, a phenyl group. R4 and R5 each represent an alkyl group having the same definition as R3. The heterocyclic ring formed when R4 and R5 combine each other is exemplified by a pyridyl group, a morpholino group, and imidazole group.
[0071] The above compounds are known as polymeric coagulants, and are readily available on the market.
[0072] The polymeric coagulant represented by the above Formula (I) may have a molecular weight of from 103 to 106, and preferably from 3 x 103 to 2 x 105, and may be added in an amount of from 1/50 to 1/4, and preferably from 1/40 to 1/10 in weight ratio, based on the gelatin contained in the emulsion.
[0073] In a working embodiment of the present invention, after any of these polymeric coagulants is added, the pH is adjusted so that the AgX emulsion is coagulated. The pH at which coagulation is carried out is not less than 3.0 and not more than 5.0.
[0074] There are no particular limitations on acids used in the pH adjustment, but may preferably be used organic acids such as acetic acid, citric acid, and salicylic acid, and inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid. Heavy metal ions as exemplified by a magnesium ion, a cadmium ion, a lead ion, and a zirconium ion may also used in combination with the polymeric coagulant.
[0075] Desalting may be carried out once, or may be repeated several times, When it is repeated several times, the polymeric coagulant may be added every time of desalting, or the polymeric coagulant may only be added at the beginning.
[0076] The spectral sensitizer may be added by any methods. For example, a solution obtained by dissolving the spectral sensitizer in water or an inorganic solvent may be added in the emulsion. A substantially water-insoluble spectral sensitizer can be used in the form of a dispersion obtained by dispersing it in a water-insoluble solvent. The spectral sensitizer may be added at one time in its total amount, or may be added dividedly into several portions. It may also be added continuously for a given time. As described in Japanese Patent O.P.I. Publication No. 196749/1985, it may also be added in the form of a dispersion obtained by dispersing a substantially water-insoluble spectral sensitizer in an aqueous solvent.
[0077] The pH of the emulsion at the time of the desalting step may preferably range from 3.0 to 9.5. In the course of that step, the spectral sensitizer may preferably be added at the time when the pH is from 6.0 to 9.5.
[0078] The pAg of the emulsion at the time of the desalting step may preferably range from 4.9 to 12.5. Similarly, the spectral sensitizer may preferably be added at the time when the pAg is from 8.0 to 12.5.
[0079] Various dyes can be used as the spectral sensitizer. For example, it is possible to use cyanine dyes, merocyanine dyes, composite cyanine dyes, composite merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes, or hemioxanol dyes.
[0080] Particularly useful dyes are cyanine dyes, merocyanine dyes, and composite merocyanine dyes. To these dyes, any of the nuclei usually utilized in the cyanine dyes can be applied as basic heterocyclic nuclei. More specifically, they inciude a pyrophosphoric nucleus, an oxazoline nucleus, a thiazoline nucleus, a pyrrole nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus, an imidazole nucleus, a tetrazole nucleus, a pyridine nucleus, and a nucleus formed by condensation of an alicyclic hydrocarbon ring to any of these nuclei, as well as a nucleus formed by condensation of an aromatic hydrocarbon ring to any of these nuclei, i.e., an indolenine nucleus, a benzindolenine nucleus, an indole nucleus, a benzoxazole nucleus, a naphtoxazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a benzoselenazole nucleus, a benzimidazole nucleus, a quinoline nucleus, etc. These nuclei may be substituted on a carbon atom.
[0081] To the merocyanine dyes or composite merocyanine dyes, heterocyclic nuclei of 5 or 6 members, such as a pyrazolin-5-one nucleus, a thiohydantoin nucleus, a 2-thioxazolidine-2,4-dione nucleus, a thiazolidine-2,4-dione nucleus, a rhodanine nucleus, and a thiobarbituric acid nucleus can be applied as nuclei having a ketomethylene structure.
[0083] Specifically, the dyes as described in, for example, RD (Research Disclosure) 17643, pp.22-24, RD 18716, p.648, right column ff. and the dyes as described in Japanese Patent O.P.I. Publication no. 80237/1986 can prefeably be used.
[0084] These sensitizing dyes may preferably be used in an amount of not less than 3 mg/m2, and particularly from 5 to 30 mg/m2.
[0088] The AgX emulsion is usually subjected to chemical sensitization so that the grain surfaces are sensitized. When, however, the chemical sensitization is carried out after the desalting step in the present invention, at least part of the spectral sensitizer has been already added in the emulsion as previously described.
[0089] The AgX emulsion is usually subjected to chemical sensitization so that the grain surfaces are sensitized, where the sensitization can be carried out using alone, or in combination, the sulfur sensitization that employs a compound containing sulfur capable of reacting with silver ions or an active gelatin, the reduction sensitization that employs a reducing substance, and the noble metal sensitization that employs a compound of a noble metal such as gold. Gold sensitization and sulfur sensitization may preferably be used in combination.
[0090] As sulfur sensitizers, thiosulfates, thioureas, thiazoles, rhodanines, and other compounds can be used. As reduction sensitizers, stannous chloride, amines, hydrazine derivatives, formamidinesulfinic acid, silane compounds, and so forth can be used. For the purpose of the noble metal sensitization, gold complex salts, as well as complex salts of the group VIII metals of the periodic table, such as platinum, iridium and palladium can be used.
[0091] Coating weight of silver may be of any weight, but may preferably be not less than 1,000 mg/m2 and not more than 15,000 mg/m2, and more preferably be not less than 2,000 mg/m2 and not more than 10,000 mg/m2.
[0092] As binders or protective colloids of the photographic emulsion according to the present invention, it is advantageous to use gelatin. Hydrophilic colloids other than that can also be used.
[0093] In the present invention, at least one emulsion layer comprised of the above emulsion according to the present invention is formed in the light-sensitive material. The emulsion layer is provided usually by coating the emulsion on a support. The emulsion layer may be formed on one side of the support, or may be formed on both sides thereof. As to the layer comprised of the emulsion according to the present invention, at least one layer may be present on either side of the support. A layer comprised of an emulsion other than the emulsion according to the present invention may also be present. A protective layer, an intermediate layer, and other non-light-sensitive layers may also be present as a matter of course.
[0094] The light-sensitive material of the present invention is a light-sensitive material having at least one light-sensitive AgX emulsion layer on at least one side of the support, wherein the photographic component layer on the side having the light-sensitive AgX emulsion layer is constituted in the following way:
(1) The coating weight of the total hydrophilic colloids is from 2.0 to 3.8 g/m2.
(2) The coating weight of silver halide is less than 3.2 g/m2 in terms of silver weight.
(3) The melting point in water, of the photographic component layer (infinite expansion temperature) is controlled to be 86. C or higher.
[0095] Use of the light-sensitive material prepared in accordance with the present invention can bring about the good results that the light-sensitive material has a high speed and at the same time has a good graininess, and also may cause faulty fixing, faulty washing and faulty drying with difficulty. A coating weight more than 3.5 g/m2, of the total hydrophilic colloids may bring about a good graininess but tends to cause a lowering of sensitivity and a lowering of maximum density. On the other hand, a coating weight of less than 2.0 g/m2 tends to readily bring about coating uneveness, or result in yellowish silver image after processing. A . coating weight more than 3.2 m2 of AgX grains in terms of silver may sometimes result in a poor fixing performance. Light-sensitive AgX grains preferable from the viewpoints of processing characteristics and sensitivity are grains having a grain size of from 0.2 to 1.6 um in terms of average grain size based on projection area diameters, having a silver iodide content of from 0.1 to 4.0 mol %, and containing not less than 96 mol % of silver bromide.
[0096] The melting point in water, of the light-sensitive AgX material of the present invention is not less than 86 C. A melting point less than 86 C may result in so low a film strength of the film in a processing solution that the hydrophilic colloid may adhere to delivery rollers or the transport performance may be deteriorated. The melting point mentioned in the present invention refers to a value measured in water having a specific resistivity of not less than 1 x 106 n'cm.
[0097] The light-sensitive AgX material of the present invention can be made to have the melting point of not less than 86 C by the use of, for example, a gelatin hardener. When not hardened, the light-sensitive material has a melting point of about 29 to 32 C.
[0098] Additives used in the step of preparing the emulsion of the present invention are, in addition to those previously described, described in Research Disclosures (RD) Vol. 176, No. 17643 (December, 1978) and Vol. 187, No. 18716 (November, 1976).
[0099] Developing processing of the light-sensitive material according to the present invention can be carried out according to the conventional method as described in the above RD No. 17643 or RD No. 18716.
[0100] The support that can be used in the light-sensitive material according to the present invention includes, for example, the supports as described in the above RD No. 17643, p.28, and RD No. 18716, p.647, left column. Suitable supports are plastic films, papers, etc., and the surfaces of these supports may be provided with an under coat layer or may be subjected to corona discharging, irradiation with ultraviolet rays, or the like. Then, the emulsion according to the present invention can be coated on one side or both sides of the support thus treated.
[0101] The present invention can be applied to all sorts of light-sensitive silver halide photographic materials, but is particularly suited for a high-speed black and white light-sensitive material.
[0102] In the case when the present invention is applied to medical X-ray radiography, used is a fluorescent screen (or X-ray intensifying screen) mainly composed of a fluorescent substance capable of emitting near ultraviolet light or visible light as a result of exposure to transmissive radiations.
[0103] The screens may preferably be brought into close contact with both sides of the light-sensitive material on both sides of which the emulsion of the present invention has been coated.
[0104] The transmissive radiations mentioned here refer to electromagnetic waves with high energy, and mean X-rays and gamma-rays.
[0105] The fluorescent screen refers to an intensifying screen comprising, for example, calcium tungstate as a main fluorescent component, or a fluorescent screen mainly composed of a terbium-activated rare earth compound.
[0106] As processing chemicals and other processing-related techniques, it is preferred to use the techniques as disclosed in Japanese Patent O.P.I. Publications No. 52848/1985, No. 136741/1985 and No. 36744/1986, .or the techniques as described in Maison, Photographic Processing Chemistry, Focal Press Inc.
[0107] As the processing chemicals, it is preferred to use those described in Japanese Patent O.P.I. Publication No. 23154/1988. As other additives, those described in Research Disclosure Vol. 176, 22-31 (RD 17643, 1978) can be preferably used.
[0108] The light-sensitive AgX material of the present invention is subjected to rapid processing using a roller transport type automatic processor with the following condition.
wherein t represents a length (unit: m) from the center of a first roller at the inlet of the roller transport type automatic processor to the center of a last roller at the drying section outlet, and T represents a time (unit: second) required for the light-sensitive material to pass on said t.
[0109] The above t can be obtained on the basis of, for example, a light-sensitive material having a photographic component layer on a polyethylene terephthalate support of 175 um thick.
[0110] The above T can be said to be the total time through which the top of a film is first inserted to the center of the first roller at the inlet of the roller transport type automatic processor, and thereafter the film passes through a developing tank, a cross-over guide, a fixing tank, a cross-over guide, a washing tank, a cross-over guide, and a drying section, until the top of the film comes out of the last roller at the drying section outlet [in other words, the quatient (sec.) obtained by dividing the total length (m) of the processing line by the line transport speed (m/sec.)].
[0111] Here, the reason why the time on the cross-over guide is included is that a processing step substantially proceeds there because a solution used in the processing anterior thereto is contained in a gelatin film even at the cross-over guide.
[0112] The number of all delivery rollers of the automatic processor used in the processing of the present invention may preferably be such that a value obtained by dividing the processing length t (m) of the automatic processor according to the present invention, by the number of rollers is in the range of from 0.01 to 0.04. The time required for each processing section may preferably be in the following range.
[0113] In the above processing of the present invention, the time taken for the developing and cross-over can be 20 seconds or less at longest. Substantially, it ranges from 20 to 7 seconds.
[0114] Rollers used may preferably range between 12 mm and 60 mm in diameter at the delivery portion, and between 30 cm and 110 cm in length. Rollers made of various materials can be used. For example, those of a Bakelite type (which may contain glass powder, metal powder or plastic powder) and those of a rubber type (such as Neoprene, isoprene or silicone rubber) can be used at the developing, fixing, washing and drying sections. At the cross-over guides or sqeeseeing section, it is preferred to use silicone rubbers having water repellency and resiliency, or synthetic leathers "Kurarino" (trade name; available from Kuraray).
[0115] The processing length ℓ of the roller transport type automatic processor ranges from 0.7 to 3.1. This can bring about preferable results. A length I smaller than 0.7 makes each processing step excessively short and makes small the number of the rollers used, resulting in a lowering of sensitivity, and also resulting in a poor transport performance. On the other hand, a length ℓ more than 3.1 may make the transport speed excessively high, not only tending to make scratches on films but also resulting in an abrupt lowering of the durability of the automatic processor.
[0116] A value less than 50, of the ℓ0.75 x T not only may result in an abrupt lowering of the sensitivity of processed films, but also may bring about the problem of aftercolor in the case of a film in which sensitizing dyes are used in an amount of 10 mg/m2 or more per one side of a support. The value of ℓ0.75 x T may preferably be not less than 76.
[0117] On the other hand, a value more than 124, of the ℓ0.75 x T tends to cause a great deterioration of the graininess of photographic images although the sentivity is little increased, and also bring about an increase in fog.
[0118] In order to improve transport performance, the delivery rollers may be provided with irregularities, for example, irregularities with valley depths preferably ranging from 0.05 to 1.0 mm.
[0119] In order to make small the drying load at the drying section, it is also preferred for the film to have a water content so controlled as to be not more than 20 g/m2 until it reaches a squeegee rack. For example, it can be effective to use the above water-repellent rollers, or, in reverse, to use rollers with a large water absorption. It is also good to design the processor so that part of drying air may be circulated to squeegee rollers.
[0120] At the drying section, it is preferred to control the distance from an air outlet of the drying air to the film so as to range from 1 to 10 mm. The temperature of the drying air may preferably be in the range of from 35 to 55 C. An infrared heater or microwave drying may also be used in combination at the same time.
3XAMPLES
Example 1
(Preparation of seed crystals)
[0122] While conditions in a reaction vessel were kept to be 60 C, pAg =. 8.0 and pH = 2.0, a monodisperse cubic emulsion of silver iodobromide grains having an average grain size of 0.3 µm and containing 2.0 mol % of silver iodide was obtained according to the double-jet method.
[0123] Observation with an electron microscope revealed that twin crystals were produced at a rate of 1 % or less in number. Grains of this emulsion were used as seed crystals to effect further growth in the following way.
[0124] Preparation of Em-1:
In an aqueous 2 wt.% gelatin solution kept at 40 C, the above seed crystals were dispersed in an amount corresponding to 7.87 % of the total silver weight. The resulting dispersion was adjusted to pH 9.8 by adding ammonia and acetic acid, and to pAg 7.3 using an aqueous ammoniacal AgN03 (1 N) solution. While the pH and pAg were kept constant, an aqueous 1 N ammoniacal AgN03 solution and an aqueous halide solution containing KBr (0.6N) and KI (0.4N) were added over a period of 30 minutes by the double-jet method, to form an AgBrl shell layer. (Step 1)
[0125] Next, using acetic acid and an aqueous KBr solution, the pH and the pAg were adjusted to pH 9.0 and pAg 9.0. Using an aqueous 3N ammoniacal AgN03 solution and an aqueous KBr solution, grains were made to grow to the extent corresponding to 90 % of the grain size after growth. Here, the pH and pAg were slowly lowered to 8.2 and 8.5, respectively. (Step 2)
[0126] With addition of an aqueous 3.5N KBr solution, the pAg was adjusted to 11 and, while the pH was slowly lowered to 8.0, an aqueous 3N ammoniacal AgN03 solution and KBr solution were added to effect further growth. A roundish tetradecahedral AgBrl emulsion having an average grain size of 0.70 µm and containing 2.2 mol % of Agl was thus obtained. (Step 3)
[0128] The AgX emulsion solution was kept at 40°C, to which the following compound (Exemplary Compound 11-1 as disclosed in Japanese Patent O.P.I. Publication No. 140322/1983) was added to effect sedimentation of AgX grains. After the supernatant was removed, pure water of 40°C was further added. MgS04 was then added, the AgX was again made to undergo sedimentation, and then the supernatant was removed.
[0129] This operation was once again carried out, followed by addition of gelatin in an amount of 15 g/mol AgX. An emulsion with pH 6.0 and pAg 8.5 was thus obtained (Step 4).
Compound (a)
[0131] Em-A:
Preparation of silver iodide emulsion:
In a reaction vessel, an aqueous 2 % gelatin solution was kept at 40°C, and the solution was adjusted to pH 9.5 by adding ammonia and acetic acid. An ammoniacal silver ion solution (0.5N) and an aqueous potassium iodide solution (0.5N) were added by the double-jet method, and the desalting was similarly carried out. An aqueous gelatin solution was further added, and the mixture was dispersed. Thereafter, the resulting emulsion was set to cool.
[0132] Em-2:
In an aqueous 2 wt.% gelatin solution kept at 40 C, the above seed crystals were dispersed in an amount corresponding to 7.87 % of the total silver weight. The resulting dispersion was adjusted to pH 9.8 by adding ammonia and acetic acid, and the pAg, to 7.3 using an aqueous ammoniacal AgNO3 (1 N) solution. While the pH and pAg were kept constant, an aqueous 1 N ammoniacal AgN03 solution, the Agl emulsion (Em-A) and an aqueous 1 N KBr solution were added over a period of 10 minutes by the triple-jet method. The aqueous AgNO3 solution and the Agl emulsion were added so as to be 3:1 in an addition rate ratio in terms of silver, and the aqueous KBr solution was added at a flow rate necessary for keeping the pAg constant.
[0133] Next, using acetic acid and an aqueous KBr solution, the pH and the pAg were adjusted to pH 9.0 and pAg 9.0. Using an aqueous 3N ammoniacal AgN03 solution and an aqueous KBr solution, grains were made to grow over a period of 20 minutes to the extent corresponding to 90 % of the grain size after growth. Here, the pH and pAg were slowly lowered to 8.2 and 8.5, respectively.
[0134] With addition of an aqueous 3.5N KBr solution, the pAg was adjusted to 11, and, while the pH was slowly lowered to 8.0, an aqueous 3N ammoniacal AgN03 solution and KBr were added to effect further growth. A roundish tetradecahedral AgBrl emulsion having an average grain size of 0.70 u.m and containing 2.2 mol % of Agl was thus obtained. Desalting was carried out in the same manner as in Em-1.
[0135] Em-3:
In a reaction vessel, an aqueous 2 % gelatin solution was kept at 40 C, and the solution was adjusted to pH 9.8 by adding acetic acid and ammonia. Thereafter, the above seed crystals were dispersed in an amount corresponding to 7.87 % of the total silver weight. The pAg was adjusted to 7.3 using an ammoniacal silver ion solution. While the pH and pAg were kept constant, a 2.0N ammoniacal silver ion solution and an aqueous 2.0N potassium iodide solution were rushly added. Thereafter, an aqueous 1.0N potassium bromide solution and a 1.0N ammoniacal silver ion solution were added over a period of 10 minutes so that the pAg 7.3 was maintained.
[0136] After the pH and pAg were adjusted to pH 9.0 and pAg 9.0 using acetic acid and an aqueous potassium bromide solution, a 3.0N ammoniacal silver ion solution and an aqueous 3.0N potassium bromide solution were simultaneously added, and grains were made to grow over a period of 20 minutes to the extent corresponding to 90 % of the grain size after growth. Here, the pH and pAg were slowly lowered to 8.2 and 8.5, respectively. With addition of an aqueous KBr solution, the pAg was adjusted to 11 and, thereafter, while the pH was slowly lowered to 8.0, an ammoniacal silver ion solution and a KBr solution were added. Desalting was carried out in the same manner as in Em-1. The desalted emulsion was dispersed in a gelatin solution. The resulting emulsion comprised roundish tetradecahedral grains having an average grain size of 0.70 am and containing 2.2 mol % of Agl, as in Em-2.
[0137] The resulting emulsion was subjected to chemical sensitization using gold sensitization and sulfur sensitization in combination, followed by addition of a sensitizing dye (sodium 3-[5-chloro-2-(2-[5-chloro-3-(3-sulfonate propyl)benzoxazoline-2-isodenmethyl]-1-butene)-3-benzoxazolio]propane sulfonate) in an amount of 150 mg per mol of silver halide, and further addition of 4-hydroxy-6-methyl-1,3,3a-tetrazaindene.
[0138] Next, using each emulsion, the additives as described later were added to give a coating solution. In the coating solution, the following Compounds (1) and (2) were added in addition to the additives described later, so as to be in the amounts, per mol of silver halide, as described below.
[0141] More specifically, Compound (1) was dissolved in an oil comprising Compound (2) and dispersed in a hydrophilic colloid solution according to the method as described in (3) of Example 1 disclosed in Japanese Patent O.P.I. Publication No. 285445/1986, and the resulting dispersion was added in an amount that may give the above amounts.
[0142] The above coating solution was coated together with the protective layer solution described later. Sample 1 to 3 each was thus obtained.
[0143] The coating solutions were coated on both sides of a 175 µm thick polyethylene terephthalate film at a speed of 60 m per minute using two sets of slide hopper coaters, so as to be 4.0 g/m2 in terms of silver and 2.0 g/m2 as hydrophilic colloid coating weight on the emulsion side, and so as to be 1.0 g g/m2 as gelatin coating weight on the protective layer, followed by drying for 2 minutes and 20 seconds to obtain samples. The polyethylene terephthalate film was previously coated as a subbing solution with an aqueous copolymer dispersion obtained by diluting to a concentration of 10 wt.% a copolymer comprising 3 kinds of monomers of 50 wt.% of glycidyl methacrylate, 10 wt.% of methyl acrylate and 40 wt.% of butyl methacrylate.
[0144] The resulting samples were each inserted between fluorescent intensifying screens KO-250 (produced by Konica Corporation), which was then irradiated with X-rays at a tube voltage of 130 KVP at 20 mA for 0.05 second, followed by exposure through a penetrometer B type (aluminum steps; available from Konica Medical Corporation). Thereafter, sensitivity and graininess were evaluated using an experimentally manufactured automatic processor as shown in Fig. 1 or Fig. 2 and also using processing solutions shown below (a developing solution and a fixing solution), with varied processing times.
[0145] In Figs. 1 and 2, the numeral 1 denotes a first roller at the inlet form which a light-sensitive material is inserted; 2, a final roller at the drying outlet; 3a, a developing tank; 3b. a fixing tank; 3c, a washing tank; 4, a light-sensitive material, an object to be processed; 5, a squeegeeing section; 6, a drying section; and 7, an air outlet of drying air. The graininess is indicated as a value of 1,000 times the standard deviation of density variations occurring when the sample is scanned with a microdensitometer. The moicrodensitometer used had an aperture size of 100 u.m x 200 am.
1.