JP2000171927A - Silver halide emulsion having improved sensitometry characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive silver halide emulsion for use in a photosensitive material having improved sensitometry characteristics, in particular sensitivity after coating. SOLUTION: The silver halide emulsion contains at least 50% flat platy silver halide grains. When the flat platy grains have an average aspect ratio of at least 1.2, at least 0.1 μm average equivalent circular grain diameter and <0.3 μm average grain thickness, the grains contain an organic hole trapping dopant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a light-sensitive emulsion for use in a light-sensitive material, wherein the emulsion contains tabular grains having improved light sensitivity.

[0002]

BACKGROUND OF THE INVENTION The photographic industry has always dealt with photographic materials, where it has been desired to achieve a satisfactory response to a well-defined minimum amount of light. This light energy should induce a chemical or physical activity that leads to a change in the exposed material that is immediately visualized or later visualized by additional processing, also referred to as processing steps. For quite some time there has been a strong and continuing need for photosensitive materials with improved sensitivity to respond to much lower amounts of light energy. One of the most important possibilities is found in photosensitive materials, where the first photoactivity change exists on an atomic or molecular scale, which in a second step visualizes the first light interaction in the material Therefore, it can be increased on the order of several times. The "two-step" mechanism of this imaging mechanism is encountered, for example, in silver halide materials forming the subject of the present invention. The sensitivity of this type of material is determined by the efficiency with which the various steps (also determined by minimizing the loss process) between light interaction with silver halide and the formation of a visible image can be performed. Is clear.
The present invention will therefore particularly focus on how the first molecular light-induced changes in silver halide crystals (also called latent images) are realized. It is indeed expected that an improvement in this process will result in the formation of a visible image with improved sensitometric properties after development.

[0003] The efficiency of latent image formation depends on many factors and can therefore be affected in many different ways. It is believed that the best results will actually be realized if each photoelectron in the silver halide crystal reaches the deepest electron trap, thereby forming a latent image. This means that recombination between holes and electrons created after light absorption is prevented as much as possible. Many solutions have been proposed for a long time, but all of them have had limited results so far. For example, as a first measure, the depth of the electron trap can be reduced to increase the capture probability. For example, chemical sensitization with sulfur, gold, selenium and other compounds or combinations thereof is therefore often used for this purpose.

Another method of preventing recombination of holes and electrons after generation is the temporary trapping of these species in local traps having intermediate trap depths. This can be done, for example, by creating strain within the crystal lattice by local incorporation of iodide in small areas or bands or cores of the grains. This method leads to increased sensitivity by reducing electron-hole recombination, and another important feature, such as developability, which is particularly desirable in modern photographic materials, is reduced by the presence of iodide.

[0005] Increasing the sensitivity of silver halide emulsions can also be achieved by increasing the efficiency of electron transfer from the spectral sensitizer to silver halide grains, which can in principle be performed with supersensitizers. .

[0006] Looking at the activity of sensitizing dyes, an increase in sensitivity can be achieved not only by increasing the efficiency of dye sensitization but also by reducing dye desensitization. The desensitization is caused by, for example, increasing the dye concentration on the surface of the particles. The combination of special cyanine and merocyanine dyes with an electron donating compound such as ascorbic acid, as described in US-A 4,897,343, is an effective means to achieve that purpose. An electron donating compound bound to a silver halide absorbing group or a sensitizing dye is used to obtain an additional sensitizing effect.

An example is US-A 5,436,121, US
No. 5,478,719 and US Pat. No. 4,607,006.

Another important way to reduce the recombination effect is to introduce into the silver halide crystals a defined complex, also referred to as a dopant, for example, a metal complex or a hole trap, such as a silver cluster. It is. Silver clusters are precipitated by pH and / or pAg by reduction sensitization by treating the emulsion crystals during precipitation with reducing agents such as tin compounds, polyamine derivatives, human azine, ascorbic acid and analogs, or without requiring the use of reducing substances. It can be made in the crystal by making well defined conditions in the vessel. US-A 3,892,574 describes a process in which small silver specks (which are so small that they do not give a spontaneously developable fog) are produced under reducing conditions during or before silver ripening precipitation or physical ripening. . The same can be said for the silver halide production process as described in US Pat. No. 3,957,490, in which at the end of the reduction time an oxidizing agent has been introduced into the silver halide emulsion before chemical sensitization. However, most of the above-mentioned methods cause more or less fogging and pose a serious problem.

In all of the above concepts, according to experimental evidence, these silver clusters are, for example, $ 10
It has been found that it can be easily formed on a {111} AgBr crystal face when compared to a 0 @ AgBr or {100} AgCl crystal face.

[0010]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide an emulsion for use in a light-sensitive material exhibiting sensitometric properties, especially sensitivity after coating.

It is a further object of the present invention to specifically provide photosensitive silver halide emulsions containing {111} tabular silver halide grains containing a new type of dopant.

It is yet another object of the present invention to provide a light-sensitive material containing silver halide emulsion grains in a light-sensitive layer which leads to an increased speed after processing of said material.

[0013] Further objects and advantages of the invention will become apparent from the description accompanying the examples given hereinafter.

[0014]

SUMMARY OF THE INVENTION The above object has at least five objects.
A photosensitive silver halide emulsion containing tabular silver halide grains in an amount of 0%, wherein said tabular grains have an average aspect ratio of at least 1.2, an average equivalent circular grain diameter of at least 0.1 μm, and 0%. In the case of having an average grain thickness of less than 0.3 μm, this is achieved by providing a photosensitive silver halide, characterized in that said grains comprise an organic hole trapping dopant.

In a particular example, the light-sensitive silver halide emulsion contains tabular silver halide grains having a core and an outermost shell, the outermost shell of which is an organic hole-trapping satisfying formula (I). Including dopants:

Embedded image In the formula, X and Y each independently represent O, S or Se, and R ¹ and R ² each independently represent hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted aralkyl, substituted Or represents an unsubstituted heteroaryl,
R ¹ and R ² may be the same or different and may form a ring, E represents a group linked to a carbon atom by a heteroatom having at least one free electron pair,
M ⁺ is a proton or an organic or inorganic counter ion; m and n each represent an integer; m is equal to 1 and n is equal to 1 or 2;

[0016]

DETAILED DESCRIPTION OF THE INVENTION While the invention will be described in connection with preferred embodiments thereof, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents included within the scope and spirit of the invention as defined by the appended claims.

The present invention as described above will be described in detail below. It has surprisingly been found that the sensitivity of photosensitive materials containing silver halide emulsions having tabular silver halide grains or crystals can be improved as described above by the introduction of organic molecules acting as organic hole trapping dopants. . In particular, it is preferred that the organic molecule is characterized by the following formula (I):

Embedded image The symbols in the general formula have the following meanings: X and Y each independently represent O, S or Se, and R ¹ and R ² each independently represent hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl Represents a substituted or unsubstituted aralkyl, a substituted or unsubstituted heteroaryl, wherein R ¹ and R ² may be the same or different, may form a ring, and E has at least one free electron pair Represents a group linked to a carbon atom by a heteroatom, M ⁺ is a proton or an organic or inorganic counter ion, m and n each represent an integer, m is equal to 1 and n is equal to 1 or 2.

Organic molecules satisfying formula (I) act as hole-trapping agents after occluding them into the silver halide lattice. The hole trapping agent is defined as a compound that emits one electron due to a reaction with a hole formed in a silver halide crystal lattice after absorption of a photon.

The substituted alkyl, aryl or aralkyl for R ¹ and R ^{2 in} formula (I) may also contain other functional substituents such as hydroxyl, amine, carboxyl, ether, carboxylic acid groups. This means that salts of polyacids such as oxalic acid, malonic acid, maleic acid, as well as salts of tri-, tetra- and higher carboxylic acids are included.

For "M ⁺ " in the formula (I), for example, all metals capable of forming a water-soluble salt with a sulfinic acid group according to the formula (II) can be used. In the present invention, alkaline earth metals, more preferably alkali metals, are possible.
On the other hand, ^{"M +"} can be an organic radical, more preferably a group of ^{N + R 3 R 4 R 5} R 6 (R 3 ~R 6 may be the same or different ^.R 3 ~ Each of R ⁶ is hydrogen,
(Eg, unsubstituted or substituted alkyl, unsubstituted or substituted aryl). Alternatively, an onium ion different from the previously provided ammonium cation is possible, in which case instead of on nitrogen a positive charge is placed on another element such as, for example, phosphor, selenium, iodide, tellurium, sulfur, and thus Represents a phosphonium, selenonium, iodonium, telluronium or sulfonium ion.

Another hole trapping compound which can be used in combination with the hole trapping compound according to the general formula (I) for incorporation into the tabular silver halide crystals of the emulsion according to the invention is formic acid or its (alkaline earth metal or Alkali metal) salts.

It is clear that the size of the molecule represented by formula (I) is important for providing effective incorporation in the silver halide matrix. In principle, the metal valency can be 1, 2 or more. It is preferred that the organic cation, such as the anion that is part of the compound represented by formula (I), be as compact as possible. However, there is no clear limitation due to the contamination.

Typical examples of hole trapping agents according to formula (I) are given below:

Embedded image

In a preferred embodiment of the general formula (I), X and Y are both oxygen, and thus the structure is identical for all the compounds described above (except for compounds VIII and XI, where Y is sulfur).

When X and Y each represent oxygen, formula (I) is represented by the following formula (II):

Embedded image In the formula, R ¹ and R ² , M ⁺ and E have the same meaning as described above. The smallest complex molecule according to formula (II) is CH ₃ SO ₂ H, and the smallest complex α-hydroxymethylsulfinic acid is H
OCH ₂ SO ₂ H. In a preferred embodiment, the emulsion according to the invention comprises Rongalite which is present as an organic hole-trapping dopant according to formula (I) as sulfinic acid or an inorganic or organic salt thereof, more preferably as α-hydroxymethylsulfinic acid or a salt thereof.

Α-Hydroxymethylsulfinic acid or its salts are commercially available (such as “Rongalit”) or are available from Mulliez and Naudy (Tetrahedron 49 (199).
3), pp. 2469-2476). In this document, reference is made to an older document describing the preparation of α-hydroxymethylsulfinic acid. Synthesis of α-aminomethylsulfinic acid is Mu
described by lliez et al. When R1 and R2 represent hydrogen, they are readily available from Rongalit (J. Org Chem. 61 (1996), p. 5648-5649). Further synthetic methods are described in WO 98/04522 and Tetrahedron,
50 (18), p. 5401-5412.

The amount of the organic hole trapping dopant preferably used in the tabular grain emulsion crystals of the present invention is from 10 ⁻² to 10 ⁻⁸ mol per mol of silver halide, most preferably 5 × 10 mol per mol of silver halide. 10 ^-3 ~
10 ⁻⁸ mol.

Another essential feature of the present invention is the site at which the organic hole trapping dopant is introduced into the crystal volume of the tabular grains or crystals according to the present invention. The site at which the dopant is introduced obviously depends on the time schedule during the precipitation of the crystal. In a preferred example, the tabular silver halide grains or crystals have organic hole trapping dopants incorporated in the outermost shell.

The formation of silver halide emulsions is most commonly carried out by introducing a soluble silver salt with a soluble halide as a reactant into an aqueous solution of a preferred binder such as gelatin, well known as a colloid stabilizer. Can be done. After the first nucleation step in which the nuclei are formed, a growth step will be performed with the continuous addition of both reactants. During the precipitation, the entire process can be performed at controlled conditions of pH and pAg.

An important factor in the present invention during the precipitation is the presence of an oxidizing agent during the addition of the compound according to formula (I) in the precipitation step. The oxidizing agent is preferably added before the organic hole trapping dopant is injected in the precipitation step of the silver halide emulsion crystals. The addition of the oxidizing agent can be carried out immediately or at a certain time, preferably under stirring conditions, to promote the homogeneity of the resulting solution added. Although the type of oxidant to be used depends on the oxidizing power required to obtain optimal hole trapping results, the actual experimental results will also be affected by the amount of oxidant selected. The most preferred oxidizing agent to be added to the solution of the compound having the structure given in general formula (I) before adding to the reaction vessel in which the silver halide is precipitated is p-toluenethiosulfonic acid or a salt thereof (which Sodium salt or other desired metal salt). The introduction of the oxidizing agent is preferably carried out immediately before the addition of the hole trapping agent.

Since the silver halide grains or crystals preferably have an organic hole trapping agent incorporated in the outermost shell, the oxidizing agent is added to a solution containing an organic hole trapping agent according to formula (I). It is evident that precipitation has been carried out to a certain extent before addition to the precipitation vessel (preferably where emulsions having tabular core-shell grains or crystals are precipitated) after stirring and before the solution is stirred.

A compound of the present invention satisfying the general formula (I),
And combinations of both can be introduced in various ways during the precipitation of the silver halide grains: via the silver salt inlet or via a separate third inlet system. Attention should be paid to the location of the third inlet used for the addition of the hole trapping agent of the present invention. This should be implemented in such a way that the hole trapping agent is supplied just below the surface of the solution in which the silver halide is precipitated. Further, the entrance itself should be located closer to the silver halide entrance than to the silver halide entrance. Injection of a hole trapping agent as close as possible to the silver salt inlet is preferred. However, combined simultaneous addition of a hole trapping agent and a silver salt solution through one inlet is one of the ultimate most preferred configurations that can be used in the present invention. This can be said for all system configurations where the solution of the hole trapping agent and the silver salt are mixed together before the formation of the silver halide itself.

The introduction of the organic hole-trapping dopant can be carried out over the entire precipitation step of the silver halide emulsion (for example, starting with the nucleation step and ending with the end of the growth step, the totality of the emulsion crystals thus formed. Lead to a homogeneous distribution of the dopant over the crystal volume), but as already mentioned in a preferred embodiment, the addition of the organic hole-trapping agent according to formula (I) together with or immediately after the addition of the oxidizing agent described above is sufficient for the total precipitation reaction It is preferably carried out when at least 5% of the total silver required (when the nucleation step is partially or completely completed) is used. In a preferred embodiment, the nucleation step is carried out together with or shortly after the introduction of the oxidizing agent (when at least 5%, more preferably 10% of the total silver halide is precipitated in the reaction vessel) of an organic compound according to general formula (I). It should be done completely before the introduction of the hole trapping agent. The introduction can be carried out at a constant flow rate or at an increasing, decreasing or fluctuating flow rate or a flow rate interrupted once or several times. This means that all types of concentration distributions of the compounds satisfying the formula (I) in the silver halide grains are possible. The amount of the organic hole trapping dopant to be incorporated is preferably a mol of silver halide.
Is a per ¹⁰ -8 ^~10 -2 mol.

The compound of formula (I) is introduced as an aqueous solution into the already formed silver halide emulsion, while the poorly soluble compound can be incorporated by using a water-soluble hydrophilic organic solvent. . If a solution of these compounds is added with either a silver salt solution or a (less preferred) halide salt solution, a separate introduction below or above the surface of the precipitating emulsion can be achieved by one or more injection means. Can be implemented. The position can be freely selected and optimized. The addition can be performed under hydrostatic pressure as a driving force or by a motor-driven injection system, which can be automatically or computer controlled as desired. However,
Attention should be paid to the location of the third inlet, if used, for the addition of the organic hole trapping agent of the present invention. The inlet should also be fitted in such a way that the hole trapping agent is supplied just below the surface of the solution in which the silver halide is precipitated. Expressing it in another way: The third inlet should be located closer to the silver salt inlet than the halide inlet. Although the injection of the hole trapping agent is preferably as close as possible to the silver salt inlet, the combined simultaneous addition of the hole trapping agent and the silver salt solution through one inlet is the ultimate for achieving the objects of the present invention. This is one of the most preferable configurations. This can be extended to any precipitation system in which the organic hole trapping agent and silver salt solution are mixed together before the formation of the silver halide emulsion crystals and doped with the organic hole trapping agent. When very low concentrations of the organic hole trapping agent are already leading to the desired sensitometric effect, a solution can even be made by mixing a solution of the aqueous silver nitrate solution and the organic hole trapping agent. In that case, the third inlet can be eliminated because it is a reducing agent.

The tabular silver halide emulsion grains or crystals as described above can be produced by various methods according to conventional methods. In short, these methods are always p
Following the initiation of the nucleation step with controlled Ag and pH conditions, one or more grain growth steps are performed after one or more physical ripening steps. In emulsion preparation, the reactants are added to the reaction vessel in the form of preformed silver halide nuclei or fine grains which are readily soluble in the precipitation medium or in the form of a solution of silver and halide salts. The individual silver and halide salt solutions may be surface or lower surfaces by an automated delivery system to maintain control of the pAg and / or pH in the reaction vessel and the rate of the reactant solution introduced into the reaction vessel, or by hydrostatic pressure. It can be added through a delivery tube. Adjustment of the pAg and pH values is crucial for the use of compounds satisfying formula (I) for the emulsions of the present invention, while said adjustment clearly determines the activity of these organic hole trapping dopants. Therefore, the pH is preferably set to 1 to 10, and most preferably 2 to 8. On the other hand, the pAg value is 2 to 9
Is preferably set to 3 to 8, and most preferably 3 to 8.

Reactant solutions or dispersions for the production of silver halide itself as taught for compounds used for incorporation into tabular silver halide emulsions according to the invention can be prepared at a constant rate or It can be added at a constantly increasing, decreasing or fluctuating rate, if desired, in combination with a stepwise delivery means.

The tabular silver halide photographic emulsion of the present invention thus produced contains silver halide crystals containing chloride, bromide or iodide alone or in combination, and depending on the precipitation conditions, {111} or ｛. Contains 100% crystal habit.
Other silver salts which can in principle be incorporated in limited amounts in the silver halide lattice are silver phosphate, silver thiocyanate, silver citrate and some other silver salts. The chloride and bromide salts can be combined in all ratios to form a silver chlorobromide salt. However, in forming an iodide halide having an iodide content dependent on the saturation limit of iodide in a silver halide lattice having a predetermined halide composition, the iodide salt is precipitated together with the chloride and / or bromide salt. Can be done. This means up to a maximum of about 40 mol% in silver iodobromide and up to 13 mol% in silver iodochloride (both based on silver). A preferred silver halide emulsion is 20 m
silver bromoiodide having an iodide content of not more than 8 mol%, silver chloroiodide having an iodide content of not more than 8 mol% and silver bromoiodide having a maximum of 40 mol% of a bromide and not more than 4 mol%. The composition of the halide may vary in the crystal in a continuous or discontinuous manner. Emulsions containing crystals composed of various zones with different halide compositions are used for some photographic applications. Structures that differ in halide composition between the central portion of the crystal and the rest (referred to as "core-shell emulsions") or structures that have two or more crystalline portions that differ in halide composition ("band emulsions") ) May occur. The change in halide composition can be caused by the direct precipitation of the corresponding halide salt solution when mixed with the aqueous silver nitrate solution or in the presence of so-called host grains, whereby on certain "basic" or "core" grains It can be realized in an indirect way by utilizing fine silver halide grains having a well-defined silver halide composition to form a "shell" or "band". This mechanism occurs as a result of Ostwald ripening, a physical ripening mechanism driven by differences in particle size and its solubility.
The addition of iodide (usually done by the addition of an inorganic iodide salt, and by the addition of an organic iodide releasing agent if slow iodide release is desired in the reaction) leads to increased iodide content by conversion, The halide ion replaces the soluble silver halide halide as bromide or chloride. However, the addition of iodide, whether or not it contains small amounts of bromide and / or chloride, is also possible by adding fine preformed grains of silver iodide.
The particles have a particle diameter of less than 100 nm, preferably less than 50 nm. Such fine grains are so-called "Lipman" emulsions.

One example that can be advantageously applied in the process for producing an emulsion according to the present invention, the addition of iodide with an organic agent releasing iodide ions is described, for example, in EP-A 0 564 141.
5,056,701, 0563708 and 065128
4 and US Pat. Nos. 5,482,826 and 5,736,312, which are advantageous for achieving a homogeneous distribution of iodide in the crystal volume of {111} tabular grains or crystals containing silver iodide. In the present invention, silver chloride-rich {111} tabular grains can be prepared as described in EP-A 0 678 772, according to which the average aspect ratio is at least 8: 1, from 0.08 μm to 0.8 μm. 2μ
silver bromoiodide or chloroiodochloride having {111} crystal faces, having an average grain thickness of less than m and at least 75 mol% chloride and 0.1 to less than 1 mol% iodide, based on silver. An emulsion comprising silver iodide tabular grains is claimed wherein at least 50% of the total projected area is provided by said tabular grains, said grains comprising a variable iodide formed by the introduction of an organic compound which releases iodide ions. Has a distribution. Alternatively, the iodide ion is US-A 5736
It can be released from iodate as described in 312. {100} containing enormous amount of chloride
In the production of tabular grain emulsions, iodide contains 3%
It is preferably introduced in the form of an iodide-releasing material before it is precipitated as performed in arch Disclosure 394010 (issued February 1, 1997).

One example that is advantageously applied within the present invention is:
The addition of iodide as fine silver iodide grains is described in JP-A04
251241 and 08029904 and EP-A 06
The process can be carried out as described for the production of {111} tabular grains at 62632 and 0658805, with the outermost phase rich in silver iodide being added to the {111} tabular grains rich in silver bromide. In particular, ultra-fine AgI particles are EP
-A 0621505 can be introduced as a seed emulsion or as described in EP-A 0517
434, can be used to prepare a core-shell emulsion, thus forming two phases in crystals of different composition. Low (0.00
# 5 to less than 0.3 mol%)
1-tabular silver bromoiodide or silver bromochloroiodide emulsions can be prepared as described in EP-A 0 475 191 to advantage for rapid processing applications. Silver chloride-rich {100} tabular emulsion grains in which AgI is introduced inside the grain volume are described in JP-A 08095182 and 08292.
511 can be manufactured.
Iodide release in the presence of a compound that modulates the rate of iodide release can be applied as described in US Pat. No. 5,807,663 to obtain a multilayer structure in silver halide tabular emulsion grains. .

More generally, emulsions having silver bromide-rich {111} tabular crystals according to the present invention are described in the patent literature apart from the addition of an organic hole trapping agent according to formula (I). It may be manufactured as follows. EP-A 0
Regions with different iodide concentrations can be present in the crystal volume as described in U.S. Pat.
Silver halide can be deposited epitaxially on tabular grains as described in P-A 0 699 948, or when iodide-rich regions are present at the crystal boundaries, as in EP-A 0 701 164 U.S. Pat. No. 5,693,983, wherein epitaxial deposition can be further located at surface sites, or where sophisticated epitaxial deposition is described for multiple tabular grain emulsions.
87. Alternatively, {111} tabular crystals having a lower surface iodide concentration at the corners compared to the edges can be produced as in EP-A 0736199. Substantially silver iodide-free tabular grains which are advantageous in speed, contrast and speed-graininess relationships can be prepared as in US Pat. No. 5,614,359. EP-A 0 699 948 and US-A 56 even for ultra-thin particles having a thickness of 0.07 μm or less.
41618.

Furthermore, according to the present invention, # 11 rich in silver chloride
Emulsions having 1｝ tabular crystals may be prepared as described in the patent literature apart from the addition of an organic hole trapping agent according to formula (I). EP-A already described above
Apart from the emulsions described in U.S. Pat. No. 6,678,772, the emulsions disclosed in Research Disclosure 388046 (issued August 1, 1996) can be used. That
Research Disclosure describes {111} tabular grain emulsions that have been treated with iodide for increased morphological stability and increased photographic performance. Further, a {111} tabular salt (bromo) silver iodide emulsion was prepared according to EP-A08
66362, which results in improved homogeneity. $ 1 rich in silver chloride
It is well known that a habit modifier is required to stabilize said crystal habit in order to produce 11 ° tabular silver halide crystals. A preferred crystal habit modifier is EP-A05
Azines or xanthoids as disclosed in 77173, aminoazine compounds as in EP-A 0 848 611, iodo-substituted 8-hydroxyquinolines as in EP-A 0694810, EP-A 069
Iod-substituted phenols as in 4809, US-
A 5691128 and the like. However, it is not limited to them. Adenine is EP
One of the most preferred as described in -A 0481133.

Since the crystal habit modifier is absorbed on the {111} crystal surface, competition between the modifier and the spectral sensitizer and / or stabilizer is sensitometric (reduced speed, gradation, etc.). And / or may have problems with reproducibility. Thus, according to the present invention, emulsions having {100} tabular crystals rich in silver chloride may be prepared as described in the patent literature apart from the addition of an organic hole trapping agent according to formula (I). {100} crystal is EP-A 0534395,0569971,058
4644,0584815,0617317,0617
320,0617321,0618482,06204
79,0645022,0645670,065366
9,0670514,0670515,067294
0,0762192,0767400,076856
7,0800108,0803139,084320
7,0911688,093277 and 094953
6 and US-A 5,292,632; 5,320,938;
356768; 5395746; 555882; 56
41620; 5654133; 5565315; 560
7828; 5663041; 5666530; 5695
Produced without the need for crystal habit modifying or stabilizing agents as described in 922 and 5707793.

Further details on the method of making silver halide emulsions according to the present invention apart from the addition of an organic hole trapping agent according to formula (I) can be found in Research Disclosure 38.
957, in particular in Section IC's September 1996 review. The emulsions of the present invention can be described in almost the same way, with those grains having outermost shells whose grains are only distinguished from the core part by the presence of an organic hole trapping dopant according to formula (I). It is very special about emulsions. In a preferred example, there is no difference in halide composition between the core and the shell (which occludes an organic hole trapping agent) as is common with emulsions used in the industry. Important for the present invention is the amount of silver present in the outermost shell containing the organic hole-trapping dopant satisfying formula (I), which is 9% of the total silver of all grains.
Less than 5%, preferably less than 65%, most preferably 45%
%.

Because of the reproducibility of grain distribution and the ability to calculate the amount of all types of compounds added to the emulsion, such as spectral sensitizers, stabilizers, etc., silver halide tabular crystals are " It is clear that it has a "monodisperse" distribution.

It is also clear that a monodisperse crystal habit is preferred: for {111} tabular crystals this is expressed as an amount of hexagonal particles of at least 90%, more preferably at least 95%. The light-sensitive silver halide emulsion according to the present invention should therefore contain tabular silver halide grains present in a quantity of at least 50%, more preferably at least 70%, even more preferably at least 90%. At least 1.2 particles,
More preferably an average aspect ratio of at least 5, even more preferably at least 8, 20 or less, an average equivalent circular particle diameter of at least 0.1 μm, more preferably at least 0.3 μm, even more preferably at least 0.5 μm, 50 μm or less. , 0.30 μm, more preferably less than 0.25 μm, even more preferably 0.07 to
Variations in the average grain thickness of all tabular grains having an average grain thickness of 0.20 μm, less than 0.30, more preferably 0.10 to 0.20, and / or an average equivalent circular grain diameter With a fluctuation of Monodispersion with respect to crystal diameter and / or thickness is highly preferred. This monodispersion is expressed as a variation in the average grain thickness and / or a variation in average crystal diameter of the individually measured tabular crystals from the entire tabular grain population, which is less than 0.30, more preferably Should be less than 0.20, for example, about 0.1
5 is most preferred.

The {111} tabular grains should have mostly hexagonal or mostly triangular grains and their mixing should be avoided as much as possible. In the present invention, a preferred method which can be used to prepare such emulsions having monodisperse hexagonal tabular grains is EP-A05
15106 and US-A 4,797,354 and 4996
137. When triangular grains (rich in silver bromide) are preferred, a preparation method as described in EP-A 0 754 964 and the corresponding US-A 5,733,715 is recommended. U.S. Pat.
0 and EP-A 0843208 and 0859273 are recommended to be used.
EP-A 022, particularly with respect to monodisperse core-shell emulsions
8914,0264954,0273411,0296
606,0312959,0326852,03595
06,0391560,0408752,041041
0,0416881,0421740,044345
3,0443475,0492519,050370
0,0517434,0543319,054791
2,055,735,0557695 and 066017
5 and US-A 4,439,520; 4,668,614;
689292; 4797354; 4806461; 48
35095; 4883748; 4977074; 503
2494; 5156944; 5244781; 5306
611; 5312727; 5368999; 54241
81; 5478714; 5587280 and 57926.
A production method as described in No. 01 can be advantageously used.

Which can be advantageously used in the present invention,
A special means for providing monodispersion of tabular grains in the preparation process is described in US-A 524,858, which describes a low temperature growth process.
7 describes the use of external static nucleating agents or recipients at very low stirring speeds.
No. 697, the use of a water-soluble polymer is proposed in the nucleation and Ostwald ripening steps of emulsion production.
A 5215879 discloses a polyalkylene oxide block copolymer surfactant (in addition to cationic starch used as a peptizer)
US Pat. No. 5,693,459 uses a special polymer having polyalkylene oxide units.
439787, 5712083 and 5773207,
EP-A 0 735 412, in which polyoxyalkylene siloxanes are added to the production process, and polyoxyalkylene block copolymers which are particularly rich in silver chloride {100}
EP-A09 used for producing tabular emulsion crystals
32077.

In a particular example, the tabular silver halide emulsions of the present invention incorporate, in addition to incorporating an organic hole-trapping dopant according to formula (I), an electron-trapping compound that can be introduced during precipitation. Said electron trapping compounds are well known to those skilled in the art and have the formula (I)
Are usually mixed simultaneously with silver halide grains having the same or different concentration distribution as the dopant according to the above. These electron trapping compounds, which are regularly stored in the silver halide crystal lattice, are preferably metal coordination complexes, which replace suitable amounts of silver and halide ions in the silver halide crystal lattice. These electron trapping dopants that are occluded in the lattice can be distinguished from metal complexes introduced into the emulsion as additives by EPR or ENDOR techniques. Ol for EPR technology and sample production
US-A 5,457,021 and H. Vercammen
, T. Ceulemans, D. Schoenmakers, P. Moens and DV
Proc.ICS & T of 49th Ann.Conf., by andenbroucke,
p.54 (Minneanapolis, May 19-24, 1996)
It is described in. The description of ENDOR technology is the same P.Moe
ns, H. Vercammen, D. Vandenbroucke, F. Callens and D. Schoenmakers in Proc. Ann. Conf., p. 56. These metal complexes mentioned above modify the crystal structure and further influence the properties of the crystals. Sensitivity, gradation, pressure sensitivity, high or low illumination reciprocity failure, stability, dye desensitization,
Many parameters, such as and some other sensitometric aspects of the light-sensitive silver halide emulsion can be varied by the choice of dopant, but the organic positive It can be varied in a manner very different from the way the hole trapping dopant works. The activity of the electron trapping dopant is influenced by the type of dopant, its concentration, its valency and its position in the crystal in the case of incorporation of said dopant in the form of a single metal ion. When a coordination complex or oligomer coordination complex is used, different ligands bound at the central metal ion can also be occluded in the crystal lattice, thus affecting the photographic properties of the silver halide material as well. (Research Disclosure, 38957 (1996), p.591, sect
ion ID).

In a further example, the emulsions of the present invention have an electron trapping agent that is occluded in silver halide. Only non-permanent traps from the different electron trapping agents that can be distinguished are important for the present invention. These traps have a partial positive charge and can capture photoelectrons for a very short time after their generation. They prevent photoelectrons from recombining with photoholes for a short period of time and can also increase the change in which electrons are used to form a latent image. Therefore, silver halide grains must be doped with a narrow electron trapping agent so that many photoelectrons can be used for the latent image forming process. When photoelectrons are generated by absorption of light, they are attracted by a net positive charge at the dopant site and are temporarily held at a binding energy equal to the local decrease in conduction band energy. Dopants that cause local bending of the conduction band to lower energies are referred to as narrow electron traps. This is because the binding energy that holds the photoelectrons at the dopant site is not enough to hold it permanently in place. For a dopant to be useful in forming a narrow electron trap, it must satisfy criteria that go beyond simply providing a net valency more than the net valency of the ions replacing it in the crystal lattice. For a dopant to be useful as a narrow electron trap, it must satisfy the following additional criteria: (1) its highest energy occupied orbital (HOMO) must be satisfied; (2) its lowest energy vacant orbital (LUMO) must be above the lowest energy level in the conduction band.

If conditions (1) and / or (2) are not satisfied, there will be orbits locally induced in the crystal lattice at energies lower than the conduction band minimum energy that induced locally dopants. The photoelectrons will be preferentially retained at this lower energy site, thus preventing effective transfer of the photoelectrons to the latent image forming site.

The activity of these dopants as narrow electron trapping agents can be evaluated by EPR spectroscopy and photoconductive techniques. Electron paramagnetic resonance (EP
R) technology is in fact the only technology apart from inductive technologies such as electron nuclear double resonance (ENDOR), which is the US-A
It allows for the unambiguous detection of the functionality of these narrow electron traps, as also cited in Olm et al. At 5503970. An investigation of the SET activity of the dopant by EPR should be performed on silver halide crystals that do not contain an organic hole-trapping dopant having the features of the present invention. The narrowly trapped photoelectrons give rise to an EPR signal, which consists of a signal line with a characteristic g-value for the local halide composition in the silver halide lattice. It is RS Eachus, MT Olm, R. Janes
And MCR Symons, Phy. Stat. Sol. 152 , 583
(1989) show that the g value of the narrowly trapped electrons in AgCl is 1.880 ± 0.001 and 1.49 ± 0.02 for AgBr. The g value in EPR is a characteristic of each type under study, for example, Electron Paramagnetic Resonanc
e: Techniques and Applications, Raymond S. Alger
Written, (1968), Interscience Publishers, New York
It can be calculated and measured as described in the publication. The width of the line as a function of temperature and concentration of the added dopant complex is described by H. Vercammen, D. Schoenmaker, D. Vand
enbroucke, Proceedings of the 1997 International
l Symposiumon Silver Halide Imaging, Victoria-B
C, Canada, 1997, p.125.
The reference quotes that the line width of the narrowly trapped electron EPR signal at 20K is 1.0 ± 0.1 mT for a 1 ppm dopant concentration. This parameter (line width) can be used as a thorough survey of the dopants that are effectively incorporated. In addition, only a line shape simulation as described in the last document can yield useful information about the intensity of the EPR line, which can give an indication about the presence of SET. The procedure following identification of the dopant in the present invention is almost identical to that proposed by M. Olm et al. (US-A 5,503,970). Emulsion powder was prepared as follows: gelatin was removed enzymatically, emulsion crystals sedimented; solution was decanted, sediment was washed; powder was dried before EPR characterization . These powders were sealed in quartz tubes and mounted in a cryostat in an EPR cavity. In this way the emulsion powder can be measured as usual at 2K. This low temperature is selected to eliminate other electronic or ionic events. Next, the powder was filtered using a color filter (SCHO
TT UV-DAD 8-1, λ _max = 365.9 nm, 44.9
% With a maximum transmission of 200% and HW = 8.7 nm).
It was exposed using a W XeHg lamp. After 1 minute exposure at 2K (while rotating the quartz tube to ensure complete illumination), the EPR spectrum is measured.

A computer program fits the Gaussian line shape to the recorded spectra of the test and reference emulsions and measures the intensity and line width of the signal near g = 1.88 (see the last reference cited above). If "arbitrary unit (ar
britary units) "(= au) at least 20% of the intensity of the lines measured with the reference emulsion powder
If increased, the dopant complex is a narrow electron trap.

A second method that can be used to detect the presence of narrow electron traps in silver halide crystals is room temperature or low temperature photoconductivity measurement if no organic hole trapping agent is present. If narrow electron traps are present in the crystal, the lifetime of photoelectrons will increase. The increased photoelectron lifetime of the doped emulsion as compared to the undoped reference is an important indication that the dopant is acting as a SET agent. Hua et al. (ICPS-98
Proceedings, vol 1, p.92-96) and A.Hirano (I
ICPS by CPS-98 Proceedings, vol 1, p.89-92)
-98 Conference (Antwerp, 7-11 September 1998).

Many examples of other dopants that meet the above criteria and can be used in the present invention are Research Disclosure 36
736, November 1994, pp. 657-660.

Particular attention should be paid to the use of narrow trapping agents as described in EP-A 0945, which is represented there by the general formula [ML _6-n F _n ] ^m- . In the formula, M is the period 4, 5 in the periodic table of the elements.
And 6, and metals selected from the group consisting of metals belonging to groups 7, 8, 9 and 10, wherein L is Cl, Br and I
Represents a mixture of at least two different halogen atoms or one halogen atom selected from the group consisting of: n is equal to a value satisfying the expression 1 ≦ n ≦ 6, and m is 1,2,3
Or the value of 4.

Many parameters such as sensitivity, gradation, pressure sensitivity, high or low light reciprocity failure, stability, dye desensitization, and some other sensitometric aspects of light sensitive silver halide emulsions Although it can be varied by the choice of dopants as known in the art, narrow electron traps (SET) particularly affect sensitivity in the present invention. The type of dopant, its concentration and location in the crystal are all critical for the activity of the dopant. The dopants are suitable for use in favor of sensitivity. When incorporated into a non-tabular silver halide crystal, it may be homogeneously divided over the entire grain volume, but is particularly preferred when incorporated into the shell of a cubic core-shell emulsion crystal to favor sensitivity. . There are many possibilities in the case of non-tabular grains, where the dopant may be incorporated into grains containing organic hole-trapping dopants having the properties for tabular grains of the present invention: regular Shaped crystals (cubes, octahedrons) are well known in addition to crystals having mixed crystal habits (eg, cubes with rounded edges). An application for Rongalite cubic particles is described, for example, in EP-A 0922994.

EP-A 03228 for the preparation of relatively monodisperse tabular grain emulsions having a core-shell structure
61 and 0552650, EP-A 09457 mentioned above.
55 and US-A 4,439,520, 4806462,
Methods for incorporating SETs, such as those described in 5348850 and 5374513, can be applied to achieve the objectives of the present invention.

According to the present invention there is also provided a photosensitive material, said material comprising a support and silver halide grains comprising silver halide grains prepared in the presence of an organic hole trapping dopant on at least one side thereof. Including a silver halide emulsion layer, said material further comprises silver halide tabular grains composed of at least one halide selected from the group consisting of chloride, bromide and iodide. For certain applications it is important to apply a well-defined amount of iodide on the crystal surface under controlled conditions to obtain reproducible sensitometric results after image-wise exposure and subsequent processing. It should be recommended. In that case, it is preferably carried out by using an iodide releasing agent or by using fine silver iodide emulsion grains (see the above-mentioned literature).

[0059] Hydrophilic colloids are used as protective colloids or binders for any layer or emulsion of the photographic material of the present invention. Gelatin is an advantageously used hydrophilic colloid. Conventional methods for producing lime-treated or acid-treated gelatin are described, for example, in "The Science and Technology of Gela
tin ”, edited by AGWard and A. Courts, Academic Pres
s 1977, pages 295 et seq. Gelatin is Bull.
Sci. Phot. Japan, Nr. 16, page 30 (1996).

A special type of pretreated gelatin is used as gelatin having a low calcium content and containing no calcium ions, for example as disclosed in JP-A 0107337, 06067329 and 07140576 and EP-A 0809135 and 0843207. May be done. EP-A 0227444,
0228256,0423840,0697618,0
843207, 0843208 and US-A 4942
120; 52,452 and 5,587,281, other pretreated gelatins such as gelatin rich in methionine or oxidized gelatin having a low methionine content, whether or not combined with alterations in calcium content. May be used.

However, gelatin is synthetic, semi-synthetic,
Alternatively, it may be partially or completely replaced by a natural polymer. Synthetic substituents for gelatin are, for example, polyvinyl alcohol, poly-N-vinylpyrrolidone, polyvinylimidazole, polyvinylpyrazole, polyacrylamide, polyacrylic acid and derivatives thereof, especially their copolymers.

Natural substitutes for gelatin are, for example, other proteins such as zein, albumin and casein, cellulose, saccharides, starch and alginates. Generally, semi-synthetic substitutes for gelatin are modified natural products such as gelatin derivatives obtained by grafting of polymerizable monomers onto gelatin by conversion of gelatin with alkylating or acrylate agents or pre-curing treatments. Precured gelatin having blocked functional groups, cellulose derivatives such as hydroxyalkylcellulose, carboxymethylcellulose, phthaloylcellulose, and cellulose sulfates and potato starch or EP-A 0756199,075
6198,0775858,0775859,0758
760 and US-A 5,607,828;
5; 5693459; 5726008 and 573371
8 is a modified (oxidized) starch as disclosed in US Pat. J
P-B-52-16365, Journal of The Society o
f Photographic Science and Technology of Japan, Vo
l.29 (1), 17, 22 (1966), ibid., Vol.30 (1), 10, 19 (19
67), ibid., Vol. 30 (2), 17 (1967), and ibid., Vol. 33
Further synthetic polymer compounds described in (3), 24 (1967) may be used as dispersion media. EP-A05343
95 may be used.

A part of the gelatin may be further substituted with a synthetic or natural polymer material. Certain synthetic polymers or copolymers, which have an effect on the monodispersity of the particle distribution, are advantageously used with or without combination with gelatin and / or other hydrophilic colloids, e.g.
PA-0633494 and 0784229 and US-
A 5215879; 5558663; 5712083
And those described in US Pat. No. 5,693,459 are advantageously used.

An important substitute for gelatin is EP-A
0392092,0517961,0528476
Silicas such as those described in EP 0 649 051 and 0704747, in particular EP-A 06777.
73 and 0767400 for producing tabular silver halide grains.

The emulsion can be coagulated and washed after precipitation to remove excess soluble salts. These methods are
Research Disclosure, No. 38957, issued September 1996, section III, with various alternatives such as diamond or ultrafiltration and ion exchange.

Additional gelatin or another hydrophilic colloid suitable as a binder material is added at a later stage of the emulsion preparation (eg, after washing) to optimize coating conditions and / or the required thickness of the coated emulsion layer. Can be established. Preferably a ratio of gelatin to silver halide in the range of 0.3 to 1.0 (silver halide is expressed as the equivalent of silver nitrate) is then obtained. Another binder may be added instead of or in addition to gelatin. Useful vehicles, vehicle extenders, vehicle-like additives and vehicle-related additives are described, for example, in Research Disclosure,
No. 38957 (1996), Chapter II.

The emulsions may be surface-sensitized emulsions which form a latent image mainly on the surface of the silver halide grains, or they are emulsions which form a latent image mainly inside the silver halide grains. be able to. The emulsions can also be negative working emulsions such as surface sensitized emulsions or unfogged internal latent image forming emulsions. However, non-fogged latent image forming type direct positive emulsions, which are positive working by development in the presence of a nucleating agent, and pre-fogged direct positive emulsions can be used in the present invention.

Sensitization can be performed in a number of different ways. Central chalcogen compounds (such as sulfur, selenium and tellurium), gold (such as platinum, palladium, rhodium, ruthenium, iridium and osmium)
It can be carried out by chemical sensitization with platinum group metals of the periodic system of elements or with these sensitizers, the reaction of which can be influenced by the pAg, pH and temperature of the medium in which the chemical sensitization takes place. The chemical sensitization can be arbitrarily performed in the presence of, for example, a thioether compound, a thiocyanate derivative, a stabilizer, a spectral sensitizer, and the like. The emulsions can also be sensitized by what is called reduction sensitization, which can be combined with the chemical sensitization methods described above, if desired. A complete description of all the possibilities of sensitization that can be used in the present invention can be found in Research Disclosure, No. 38957 (September 1996)
Month) and section IV.

The tabular silver halide emulsion of the present invention can be prepared by adding cyanine, merocyanine, tri-, tetra- and polynuclear cyanine and merocyanine, oxanol, hemioxonol, styryl, merostyril and the like after, before, during and after chemical sensitization. May be spectrally sensitized with dyes from various types, including polymethine dyes. Particular attention should be paid to the use of J-aggregated dyes in the present invention ("The Th
eory of Photographic Process ”, edited by THJames,
4th (1977) pp. 218-222 and T. Tani "Ph
otographic Sensitivity. Theory and Mechanisms ”, O
xford Univ. Press, New York-Oxford, 1995). These J-aggregating dyes are preferably used in combination with J-aggregating "tuning" compounds or products or agents. These special "modulating" compounds can change the J-aggregate to some desired size. This so-called “J
-Aggregation-modulating compounds "are well known and are described, for example, in (AAMue
nter et al., J. Phys. Chem., 96 (1992) 2783) Dyes or other compounds such as alcohols, surfactants, ketones, photographic stabilizers and various other products (eg, AH Herz, Phot. Sci. Eng., 18 (1974) 323). Important J preferably used in the present invention
-Aggregating-modifying compounds are photographic stabilizers.

In some situations, one or more spectral sensitizers may be used if the majority of the spectrum is to be covered. The combination of several spectral sensitizers was supersensitized (which means that in some areas of the spectrum the sensitization was greater than the sensitization resulting from the concentration of any one of the dyes alone or from the effect of adding the dyes) ) May be used to get Generally, supersensitization can be achieved by using selected combinations of spectral sensitizing dyes and other additives such as stabilizers, development accelerators or inhibitors, optical brighteners, coating aids, and the like. For example, EP-A 0
786690,0786691,0786692,08
09139 and 0862088, EP-A089087
3,9820141 (filed on April 29, 1998) and 98202081 (filed on June 22, 1998) and US-A 5,637,447; 5641618 and 569.
In particular applications, such as those described in 1127, spectrally sensitized emulsions made as described therein can be used as the silver halide emulsions of the invention. The only requirement is that special conditions be fulfilled with respect to the presence of the organic hole trapping agent according to formula (I).

A useful description of various other possibilities in spectral sensitization that is important with respect to the present invention is found in Research Dis
closure, No. 38957 (issued September 1996), section V
Can be found in

The photographic materials containing the silver halide emulsions according to the invention can contain various compounds which play a role in the material itself or subsequently in the processing, finishing or storage of the photographic material. These compounds can be stabilizers and antifoggants. Antifoggants prevent fogging while stabilizers have the function of stabilizing sensitometric properties. Antifoggants and stabilizers are used in the manufacture, storage or processing of photographic materials. Frequently used antifoggants and stabilizers can be, for example, azoles, mercaptopyrimidines, mercaptotriazines, azaindenes and the like. Further suitable examples are, for example, Re
Search Disclosure, No. 38957 (issued in September 1996), section VII.

The hydrophilic colloid layer (silver halide emulsion layer, backing layer, antihalation layer, etc.) of the photographic material in which the emulsion according to the present invention is used may be an inorganic or organic hardener (Resear).
ch Disclosure, No.38957 (issued September 1996), sec
tion IIB). In particular, the hardening of the tabular silver halide crystal is preferably carried out in a material having one or more photosensitive emulsion layers in which the hydrophilic layer is less than 300%, more preferably 20%.
It may be carried out to such an extent that it has a degree of swelling of less than 0%, even more preferably less than 150%, and has no negative effect on the covering power as expected according to US Pat. No. 4,414,304. The degree of swelling is 3 minutes at 20 ° C.
The total layer thickness of "t _s" after swelling of the material after immersion in deionized water is measured, and is determined the difference between the dry layer thickness "t _d" after computing. In order to achieve such a high degree of cure, the layer binder should of course be provided with an acceptable number of functional groups, which can give a sufficiently resistant layer by reaction with a suitable curing agent. Such functional groups include, in particular, amino groups, but can also be carboxyl groups, hydroxy groups, and active methylene groups. A hardener may be added to the stress-resistant layer covering one or more light-sensitive silver halide emulsion layers before or during the coating procedure, or to one or more of said emulsion layers. The binder of the photographic material, especially when the binder used is gelatin, is a suitable hardener, for example of the epoxide type, of the ethyleneimine type, of the vinylsulfone type (for example 1,3-vinylsulfonyl-2). -Propanol), chromium salts (e.g., chromium acetate and chromium alum), aldehydes (e.g., formaldehyde, glyoxal, and glutaraldehyde), N-methylol compounds (e.g., dimethylolurea and methyloldimethylhydantoin), dioxane derivatives (e.g., 2,3- Dihydroxy-dioxane),
Active vinyl compounds (eg, 1,3,5-triacryloyl-hexahydro-s-triazine), active halogen compounds (eg, 2,4-dichloro-6-hydroxy-s-)
Triazines), and mucohalic acids (e.g., mucochloric acid and mucophenoxychloric acid).
These curing agents can be used alone or in combination. The binder can also be hardened with a fast-acting hardener such as a carbamoylpyridinium salt. Formaldehyde and phloroglucinol can be added to the protective layer and the emulsion layer, respectively. More suitable possibilities for curing can be found in Research Disclosure, No. 38957 (issued September 1996), section IIB.

A fluorescent brightener (Research Disclosure, No. 38)
957 (issued in September 1996), section VI), light absorbing and scattering materials (Research Disclosure, No. 38957 (1)
(See September 996), section VIII), coating aid (see Research Disclosure, No. 38957 (issued in September 1996), section IXA), antistatic agent (Research Disc)
losure, No.38957 (issued September 1996), section IX
C), matting agent (ResearchDisclosure, No.38957 (1
Further compounds such as development modifiers (see Research Disclosure, No. 38957 (issued in September 1996), section XVIII) and tabular silver halide emulsions according to the present invention may be used. May be added to a material having a photosensitive emulsion layer having

The photographic material containing the tabular silver halide emulsion according to the present invention may further contain various other additives such as compounds improving the dimensional stability of the photographic material, UV absorbers and spacing agents. Additives suitable for improving the dimensional stability of photographic materials include, for example, water-soluble or poorly water-soluble synthetic polymers (eg alkyl (meth) acrylate, alkoxy (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylamide , Vinyl ester, acrylonitrile, olefin, and styrene polymers, or those described above with acrylic acid, methacrylic acid, α, β-unsaturated dicarboxylic acid, hydroxyalkyl (meth) acrylate, sulfoalkyl (meth) acrylate, and styrene (Copolymer of sulfonic acid). Suitable UV absorbers are, for example, US-A 3
Aryl-substituted benzotriazole compounds as described in 533794, US-A 3,314,794 and 3352
No. 681, 4-thiazolidone compounds, JP-
A benzophenone compounds as described in A 56-2784, cinnamic acid ester compounds as described in US-A 3,705,805 and 3,707,375, US-A 4045.
229, and US-A
Research also describes benzoxazole compounds, such as described in US Pat. No. 3,700,455, and suitable optical brighteners.
Disclosure, No. 38957 (issued September 1996), sectio
n As described in VI.

Spacing agents can additionally be present in the material comprising the tabular silver halide emulsion according to the present invention, the average grain size being 0.2 to 10 μm. These spacing agents can be soluble or insoluble in alkali. Alkali-insoluble spacing agents usually remain permanently in the photographic material, while alkali-soluble spacing agents are usually removed therefrom in an alkaline processing bath. Suitable spacing agents can be made, for example, from polymethyl methacrylate, from copolymers of acrylic acid and methyl methacrylate, and from hydroxypropyl methylcellulose hexahydrophthalate. Other suitable spacing agents are described in U.S. Pat. No. 4,614,708.

Any thickener may be used to adjust the viscosity of the coating solution prior to coating. The condition is that they do not particularly affect the photographic characteristics of the silver chloroiodide emulsion in the coated photographic material. Preferred thickeners are aqueous polymers such as polystyrene sulfonic acid, dextran, sulfate, polysaccharide, sulfonic acid groups,
Includes polymers having carboxylic or phosphoric acid groups and colloidal silica. Polymeric thickeners well known from the literature that cause thickening of the coating solution may be used in combination with colloidal silica. Patents relating to thickeners include, for example, US-A
3167410, Belgian Patent No. 558143 and J
PA 53-18687 and 58-36768. Negative effects on physical stability resulting from the addition of polymeric compounds can be avoided by removal of those compounds and by limiting the extra addition of colloidal silica as described, for example, in EP-A 0831362. it can. An alternative method for adjusting the viscosity, especially when no or only small amounts of gelatin are present, is described in EP-A 0813105, in which synthetic clays are combined with low amounts of anionic macromolecular polyelectrolytes. Used.

The photographic materials can be coated on various supports, which can be soft or hard. Examples of the soft material include plastic films (for example, polyester such as polyethylene terephthalate and polyethylene naphthalate, polyether, polycarbonate, and polyvinyl chloride) and paper, while examples of the hard material include glass and metal. The surface of the support is generally subjected to an undercoating treatment (corona discharge, ultraviolet irradiation, etc.) to increase the adhesion of the silver halide emulsion layer (Research Disclosure, No. 38957, published September 1996, section XV and references cited therein).

Photographic materials comprising a photosensitive layer having a tabular grain emulsion according to the present invention can be exposed to actinic radiation, particularly in the visible, near ultraviolet and near infrared regions of the spectrum, to form a latent image (Research Disclosure). , No.38957, 1
Published September 996, see section XVI). Various exposure means can be used for exposing the photographic material of the present invention. As light source, any optical light source that emits radiation corresponding to the wavelength range in which the photographic material is sensitive can be used. Examples of commonly used light sources include:
Examples include natural light, incandescent lamps, halogen lamps, mercury lamps, fluorescent lamps and all types of flash light sources. A light source that emits light in the ultraviolet to infrared region can be used as a recording light source. The photographic material can be exposed, for example, to a gas laser, a semiconductor laser, a light emitting diode or a plasma light source. Similarly, the material can be exposed to an LCD light source or to a fluorescent surface provided by a phosphor stimulated with X-rays or electron beams. In that case, the one-side coated silver halide photographic material is, for example, EP-A
0610609, 0712036 and 0874275
Exposure after contact with a so-called intensifying screen having a luminescent phosphor as is done in the mammographic diagnosis described in J. For medical x-ray applications such as chest imaging, it is made from a two-sided coated film material,
In that case, the screen is, for example, EP-A 0 592 724.
And on both sides of the material as described in US Pat. Such a film material may be formed symmetrically or asymmetrically as well as the screen pair in contact therewith. Even when the radiographic material is formed symmetrically, one or more emulsion layers can be coated on each side thereof, wherein the layers are sensitive to different wavelength ranges, and Exposure is, for example, US-A 538
As described in US Pat. No. 0636, this is effected by emission after exposure to X-rays of a mixture of phosphors giving emission in both different wavelength ranges. An asymmetric screen / film assembly that may be used is EP-A 0350883,040
7890, 0412730 and 576910. The difference in speed (sensitivity) and / or tone between the two layers on one or both sides of the support can be attributed to enhanced image quality (especially sharpness), reduced crossover (advantageous in image resolution), and / or enhanced exposure It is usually optimized to obtain latitude and improved curve shape.

Direct X-rays, β- or γ-rays are, for example, EP-A
It is further included as possible light sources, for example as applied in non-destructive testing applications as described in EP 0 575 286 and EP-A 0 890 873.

The latent image formed in the silver halide crystals after exposure can be processed to form a visible image.
Therefore, various methods are known and many developing, fixing and stabilizing agents have been described for forming photographic silver images. Know-how for processing photographic silver halide materials that can be used in principle in connection with the present invention is Research Disclosure, N.
o.176043, issued December 1978, section XIX-XXIV
And Research Disclosure, No. 38957, published September 1996, section XIX.

In the usual processing method, most of the materials are developed by a liquid containing hydroquinone as a main developing agent usually combined with a so-called auxiliary developing solution. In another processing method, hydroquinone is incorporated into the photographic material itself, while the processing solution is simply an alkaline solution. However, it is important to recognize that hydroquinone is questionable in various respects, especially in ecological and medical terms. The present invention also relates to ecological processing methods in which hydroquinone is at least partially replaced by ascorbic acid as a developing agent. Ascorbic acid is to be interpreted in a broad sense and includes ascorbic acid isomers, derivatives, salts and similar compounds, including some reductone and reductic acid derivatives. Most preferred compounds are ascorbic acid, iso-ascorbic acid, their salts and reductic acid. Useful combinations of developers containing ascorbic acid developing agents which should preferably be used within the scope of the invention are described in Research Disclosure, No. 37152, March 1995.
Monthly, pp. 185-224 and EP-A 07
No. 31,381,07313382 and 0732619 are described for many applications (graphics, radiography, etc.).

The photographic emulsions according to the invention can also be used in multilayer multicolor materials. These materials comprise a support and two or more silver halide emulsion layers having different spectral sensitivities. Multilayer color photographic materials generally comprise at least one red-sensitive emulsion layer, at least one green-sensitive emulsion layer and at least one blue-sensitive emulsion layer on a support.
The non-light-sensitive layer may be provided between two or more emulsion layers having the same color sensitivity. Otherwise, another emulsion layer having a different color sensitivity can be provided between two or more emulsion layers having the same color sensitivity. A light reflecting layer, such as a layer of silver halide grains, can be provided below the sensitive layer to increase sensitivity, especially below the high blue sensitive layer. Additional information useful in using the emulsions according to the present invention in color materials can be found in Research Disclosure, item No. 37038 (1).
Issued February 1, 995); item Nos. 39423 and 39433
(Both issued on February 1, 1997) and item No.40145
(Issued September 1, 1997) and EP-A 05820
00 and US-A 5,569,576. The silver halide materials may contain various types of couplers that are incorporated into color photographic materials to provide a color image after coupling with oxidized developer molecules. The red-sensitive emulsion layer generally contains a cyan coupler, the green-sensitive emulsion layer generally contains a magenta coupler, and the blue-sensitive emulsion layer generally contains a yellow coupler. Specific layers formed for color negative materials are described, for example, in EP-A 0582000 and 0736918. All information important for the application of the emulsions of the invention in these types of materials can be found in the Research Disclosure.
sure, No. 38957, published September 1996, section X. Much information on the various color applications that also fall within the scope of the present invention can be found in DE Application No.
50 (filed on October 10, 1998), No. 19845
642 (filed on October 5, 1998), No. 19843
082 (filed on September 19, 1998), No. 19831
281 (filed on July 13, 1998), No. 19751
447 (filed on November 20, 1997), No. 1974
7624 (filed October 29, 1997), EP-A
0070182, 0070183, 0083377,0
265590,0271066,02734111,03
69486,0421426,0426194,043
5295,0437859,0447534,0459
349, 0495364, 0517214, 05511
30,0557435,0557695,055931
1,0560036,0603654,062885
6,0677782,0684511,069762
6,0703493,0708932,070973
1,072147,0726493,081691
1,0845703, 0589273 and US-A 5
455146; 556571; 5593820; 56
72467; 5691130; 5698379; 570
2878; 5744290 and 5795706.

The process for forming a visible dye image for a color material comprises contacting the material with a color developing agent to reduce developable silver halide, oxidize the color developing agent,
That means in turn reacts normally with the coupler to form a dye (Research Disclosure, No. 38957, 1).
Published extensively in section XX, published September 996). More specific information is available from EP-A 0 295 716,
0318992,0326030,0589323,0
591883,0617322,0617324,06
17325, 0724190, 0838721, and U
SP 4695529; 49668835; 54551
46; 5478704; 5667949; 569837
9; 5750325.

According to a further preferred embodiment of the present invention there is provided a photothermographic recording material, said material comprising a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith, a binder and A support carrying a photoaddressable thermosensitive material further comprising an emulsion according to the invention as described above. The use of tabular silver halide emulsion grains in photothermographic materials and layer integration of such photothermographic materials is described, for example, in E.
No. 0844514, which gives a detailed description of a photothermographic dry silver recording material.

The present invention will now be described by way of the following non-limiting examples. In the following, the advantages which can be realized with the emulsion described in the present invention and the material coated with a photosensitive layer containing said emulsion will be clearly explained.

[0087]

EXAMPLES was prepared following solutions for the production of tabular silver bromide Emulsion: - solution (1.1): an aqueous solution of AgNO ₃ (1.96M) in 1500 ml - solution (1.2): an aqueous solution of KBr (1.96M) of 1500 ml - solution (1.3): gelatin 50g DI water 500 ml - solution (1.4): KBr 1.47 g of oxidized gelatin _{7.5g H 2 SO 4 (6N)} 14. 2 2856 ml of deionized water-solution (1.5): 40 ml of polystyrene sulfonic acid (20% by weight)-solution R1: 0.09 g of Na-Rongalit / l-solution R2: 0.18 g of Na-Rongalit / l Solution R3: 0.36 g of Na-longalit / l

Embedded image Rongalit sodium salt (hereinafter referred to as Na-longalit)

Precipitation Step -Comparative Emulsion (1) The pH of the solution (1.4) was adjusted to a value of 1.8 with a sulfuric acid solution, and the pBr was adjusted to 2.39 with KBr. Solutions (1.1) and (1.2) were maintained at room temperature, and solutions (1.3) and (1.4) were heated to 60 ° C.
7.35 ml of solution (1.1) and 7.35 ml of solution (1.2) were added to solution (1.4) in 9 seconds. After 2 minutes, the temperature was increased to 70 ° C. in 25 minutes before the solution (1.
3) was added and the pH was adjusted to 6 with NaOH.

After 6 minutes, the following steps were followed: a first neutralization step by adding the solution (1.2) at a rate of 7.5 ml / min for 330 seconds, a pAg of 8.85 A second neutralization step with 7.5 ml of solution (1.1) added in 1 minute, while the solution (1.2) is added at a rate controlled by a constant value of-constant increase At a speed (the final speed of 23.1 ml / min is almost three times greater than the starting speed of 7.5 ml / min)
A first growth step (solution (1.2) was added to maintain pAg at 8.86) for 3 minutes 22 seconds solution (1.1); 7.5 minute solution (1.1 3.) a third neutralization step by adding 56.25 ml of -7) in such a way that the pAg is brought to 7.38.
Fourth neutralization step by addition of solution (1.1) and solution (1.2) for 1 minute at a fixed rate of 5 ml / min,-constant starting at 7.5 ml / min and ending at 36.9 ml / min A second growth step (solution (1.2) where 911 ml of the solution (1.1) is added at increasing speed for 41 minutes and 2 seconds
Is added to maintain the pAg at 7.38), to bring the pH to 3.5 to agglomerate the emulsion and then add the solution (1.5), followed by desalting the emulsion 3 washing cycles.

After the washing procedure, gelatin and water were added to the precipitate to give an emulsion with 200 grams per kg of AgNO ₃ having a gelatin / silver nitrate ratio of 0.34. The pH and pAg values measured after peptization were 5.1 respectively.
And 7.85. The silver bromide emulsion thus produced has an average diameter d equivalent to a sphere having the same average volume as the deformed crystal of 0.7 μm and a thickness of 0.21 μm.
Hexagonal {111} tabular with at least 95% quantity
It had crystals . Variation for 0.15 grain thickness
The coefficients are calculated.

Emulsion (2) of the Invention Emulsion (2) was prepared in the same manner except that during the second growth step, a sodium salt solution of Rongalite (solution R1) added at a flow rate of 10 ml / min for 377 seconds. . The addition started 1579 seconds after the start of the solution (1.1).

Emulsions (3) and (4) of the invention Emulsions (3) and (4) in the same manner as Emulsion (2) of the invention, except that Rongalite solutions (R2) and (R3) were used for each emulsion. Was manufactured.

Coating Method The emulsion was coated at 40 ° C. after the addition of appropriate wetting and curing agents on the subbed PET base support. The amount of coated gelatin was 2.0 g / m ² and gelatin / A
The gNO ₃ ratio was 1.27. The pH and pAg of the coating solution were maintained at 6.1 and 8.66, respectively.

[0094] The emulsion using exposure and processing ^10-2 seconds Xenon flash was exposed through a step wedge document (constant = 0.15) and a color filter V405. 2 exposed photographic materials
Develop with G138® developer for 8 seconds at a temperature of 33 ° C. and fix for 22 seconds at 33 ° C. with a commercially available fixer G334® (1 part diluted with 4 parts deionized water). And washed at about 27 ° C. for 19 seconds. G138 and G33
4 is a registered trademark product (Agfa-Gevaert NV, Mortsel, Belgium).

The results listed in Table 4 describe the following parameters:-D _min is the fog level (expressed with an accuracy of 0.01) _{;-D max} is the maximum density (0.01 "Sens (0.2>fog)" means sensitivity in log (It) units realized at a density of 0.2 above fog level;-"Sens (80% D _max ) "is 80 of D _max
% Means the sensitivity in log (It) units realized in%;-"Sens (0.1>fog)" means the sensitivity in log (It) units realized in 0.1 density above the fog level Means:-"G" is 25% to 75% of the total density range above the fog
In meant the calculated gradation _{(contrast); - [HO-CH 2} -SO 2 -Na] Ron Garitto sodium concentration called the mol / mol AgNO ₃
Is displayed with.

From the results shown in Table 1 below, occlusion of Na-longalite in tabular silver halide crystals.
Clearly increase the sensitivity of chemically sensitized emulsions illuminated or exposed by light absorbed by the silver halide itself (Experiments Nos. 1-4).

[0097]

[Table 1]

Having described preferred examples of the invention in detail,
It will be apparent to those skilled in the art that numerous modifications may be made therein without departing from the scope of the invention as defined in the appended claims.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03C 1/498 501 G03C 1/498 501 (72) Inventor Joan Locfier 27 Sepfaert, Mortzel, Belgium 27 Agfa In Gevert Namurze Bennault Chap

Claims (6)

[Claims] 1. A photosensitive silver halide emulsion containing tabular silver halide grains present in at least 50% quantity, wherein said tabular grains have an average aspect ratio of at least 1.2, at least 0.1 μm. A light-sensitive silver halide emulsion having an average equivalent circular grain diameter and an average grain thickness of less than 0.3 μm, wherein the grains contain an organic hole trapping dopant. 2. The particles having a core and an outermost shell,
The emulsion of claim 1 wherein said organic hole trapping dopant is present in the outermost shell of said grains. 3. The emulsion according to claim 1, wherein the organic hole trapping dopant satisfies the following formula (I): In the formula, X and Y each independently represent O, S or Se, and R ¹ and R ² each independently represent hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted aralkyl, substituted Or represents an unsubstituted heteroaryl,
R ¹ and R ² may be the same or different and may form a ring, E represents a group linked to a carbon atom by a heteroatom having at least one free electron pair,
M ⁺ is a proton or an organic or inorganic counter ion; m and n each represent an integer; m is equal to 1 and n is equal to 1 or 2; 4. The emulsion according to claim 1, wherein said tabular silver halide emulsion grains further contain an electron trapping agent. 5. A silver halide photographic material comprising the photosensitive silver halide emulsion according to claim 1. 6. A photo-addressable organic silver salt comprising a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal relation therewith, a binder and the emulsion according to claim 1. -adressable) A photothermographic recording material comprising a support carrying a thermosensitive material.