JPH11212196A - Production of photosensitive emulsion having (100) tabular grain rich in silver chloride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing photosensitive silver halide tabular emulsion grains which are increased in the crystal habit, thickness and the homogeneity of the crystal diameter of the grains. SOLUTION: In the process for producing a photographic emulsion including the execution of at least three separate settling stages (a nucleation stage and two growth stages) followed by the execution of desalting; the emulsion contains the 100} tabular silver halide particles contg. a binder and at least 50 mol.% silver chloride. The tabular grains have >=2 average aspect ratio and the process consists in introducing >=1 crystal dislocation onto the nucleus formed after the end of the nucleation stage to impart anisotropic growth to the nucleus in the 100} tabular grains. The introduction of the crystal dislocation is executed within the time not longer than the time required for executing the first physical maturation stage after the nucleation stage in order to obtain the number of the dislocation lines of <5 on the same crystal face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a silver halide-rich light-sensitive silver halide emulsion having {100} tabular grains.

[0002]

BACKGROUND OF THE INVENTION High aspect ratio tabular grains exhibit several significant photographic advantages. Thanks to their particular morphology, one mole of silver halide
It is possible to adsorb a larger amount of spectral sensitizer for 1. As a result, such spectrally sensitized tabular grains exhibit improved speed-granularity relationships and a broad resolution between their blue and minus blue velocities. The sharpness of the photographic image can be improved using tabular grains, again due to the smaller light scattering properties when compared to conventional spherical emulsion grains. In color negative materials, for example, the conventional order of the photosensitive layers can be changed and the yellow filter layer can be omitted. In the developed black-and-white image, high covering power is obtained even at a high curing level.
Alternatively, if desired, reduced silver halide coverage can be achieved, which results in improved sharpness. In double coated radiographic materials, the presence of tabular grains is
It reduces so-called crossover, which is a major factor for sharpness in such materials. Furthermore, the silver coverage can be advantageously reduced in production costs and ecologically.

Emulsions are generally referred to as "tabular grain emulsions" when the tabular grains account for at least 50% of the total grain projected area.
It is understood that A grain is generally understood to be a tabular grain when the ratio of its equivalent circular diameter to the grain thickness is at least 2. The equivalent circular diameter of a grain is the diameter of a circle having an area equal to the projected area of the grain.

[0004] Descriptions of prior patents for high aspect tabular grains, eg US-A 4,434,226; 443.
9520; 4425425; 4425426; 4433
048 and Research Disclosure, Vol. 225, 198
The description of Item 22534, January 3rd, relates to a high sensitivity silver bromide or silver iodobromide {111} tabular grain emulsion. However, in many photographic applications, high sensitivity has become less important. In these cases, the use of chloride-rich emulsions is advantageous due to the high development and fixing rates preferred for their rapid processing applications. Representative examples include graphic arts contact materials, reproduction materials, hard copy materials, diffusion transfer reversal materials, and black and white or color print materials. However, when combined, high sensitivity and rapid processing adaptability are appreciated. Thus, there is still interest in combining the advantages of tabular grain structures with those of chloride-rich emulsions.

[0005] Chloride-rich silver halide tabular grains may have parallel planes in {111} crystal planes or {100} crystal planes (giving tabular {111} or tabular {100} crystal habits, respectively). it can.

[0006] In the earlier literature, US-A 440046
3: 4713323; 4804621; 518373
2: 5185239; 5178998; 5178997
And as described in EP-A 0481133.
Most attention was paid to the production of chloride-rich tabular grains having a 1｝ crystal habit.

The first document on tabular grains bounded by {100} parallel major faces was concerned with silver iodobromide emulsions. Bogg US-A 4063951 and
Mignot US-A 4,386,156 was the most important document.

[0008] In EP-A 0 534 395 Bruss
et al. disclose the first {100} tabular emulsion grains rich in chloride and their preparation, stating that the tabular grain fraction exhibiting {100} major faces is important. .
Improvements and modifications to the teachings of the tabular {100} emulsions, which are further rich in chloride, are described in US-A 5024931;
5264337; 5275930; 5292632; 5
310635; 5314798; 5320938; 53
56764; 5601967; 5707793; WO-
Applications 94/22051 and 94/22054 and EP-
A 0569971; 0584815; 058464
4: 0602878; 0616255; 061731
7; 0617320; 06173321; 061732
5; 0618492; 0618493; 0653659
And 0536669.

[0009] In conventional photographic materials for radiographic recording, high sensitivity (iodo) silver bromide tabular emulsions are generally used. However, due to the recent trend towards rapid processing applications, it is desirable to use chloride-rich silver halide emulsions. This is because the emulsion is, for example, EP-A06
This is because it exhibits faster developability as disclosed in US Pat.

One of the major problems encountered in the process of producing chloride-rich {111} tabular grains is crystal stability (crys).
This is a problem of tallographic stability, which means that in the manufacturing process of the particles, crystal habit modi
fier) after use, for example, in US-A 5,221,602.
Requires a cumbersome step of replacing the habit modifier with other compounds that are adsorbed on large crystal surfaces, as described in US Pat. Due to the process of adsorbing, desorbing and displacing various adsorbed compounds, there is a problem in the reproducibility and stability of the particles.

[0011] During the production of chloride-rich {100} tabular grains, the presence of such adsorbed habit modifiers is not required, as shown, for example, in EP-A 0 536 669. This is because excellent crystal stability can be obtained. Furthermore, improved sensitometric properties are obtained, especially with respect to sensitivity, when compared to equivalent non-tabular cubic emulsion crystals.

[0012] In order to benefit from all the properties provided by the tabular grains, it is always important to have the percentage of tabular grains within the overall emulsion crystal population as high as possible, so any improvement in that direction is appreciated. Obviously. Attempts to achieve that goal, especially for high chloride {100} tabular grains containing iodide ions, are described in US Pat. No. 5,413,904, which discloses that in a reaction vessel until grain nucleation occurs. It has been proposed that it is essential to delay the introduction of iodide ions. Furthermore, a means for improving good anisotropic properties, exhibiting very low growth rates in the thickness direction and thereby having excellent uniformity between the particles, is disclosed in US-A 57
07793.

The present invention further extends the teaching of chloride-rich tabular emulsion grains having a {100} crystal habit.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a silver chloride-rich, light-sensitive silver halide having a {100} major face, in which the grain habit, thickness and crystal diameter homogeneity are significantly increased. An object of the present invention is to provide a method for producing tabular emulsion grains.

Further objects of the present invention will become clear from the description hereinafter.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to provide at least three separate (dis)
tinct) a process for preparing a light-sensitive silver halide photographic emulsion, comprising performing a precipitation step and then desalting by flocculation and washing or by ultrafiltration, wherein the emulsion is a colloidally stabilized binder and at least {100} tabular silver halide grains containing 50 mol% silver chloride, wherein at least 60% of the total number of grains is provided by said tabular grains, wherein said tabular grains are at least 2%.
Having an average aspect ratio of at most 0.25 μm of average thickness with a coefficient of variation of at most 0.25, and an average equivalent circular crystal diameter of at least 0.3 μm with a coefficient of variation of at most 0.20; The separate precipitation steps are a nucleation step and two growth steps, wherein the method introduces one or more crystal dislocations on the nuclei formed in the nucleation step after the nucleation step, Further providing anisotropic growth of said nuclei in the shape-like grains, and performing the first physical ripening step after the nucleation step to obtain a number of dislocation lines of less than 5 in one same crystal plane. The physical ripening step between the growth of the dislocation-bearing nucleus in the first growth step and the introduction of the dislocation is performed within a time interval of 2 to 10 minutes,
More preferably, it is realized by providing a method for producing a light-sensitive silver halide photographic emulsion performed within a time interval of 5 to 10 minutes.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An essential feature is the precipitation of at least three separate precipitation steps in a reaction vessel.
The three separate precipitation steps are the following three steps in succession: Nucleation step 1-20% of the total amount of silver nitrate used, more preferably 5-1
Given 5%, silver and halide ions are introduced at a flow rate to obtain silver chloride-rich cubic nuclei with crystal edges of up to 0.25 μm. Therefore, if desired, up to 5 mol% bromide and / or up to 0.5 mol%
% Iodide (more preferably 0.05 to 0.3 mol
1%), an approximately equimolar addition of a halide salt (preferably a pure silver chloride salt) and a silver salt is carried out. The flow rate of the solution is selected in such a way as to obtain a crystal edge that determines the thickness of the resulting silver chloride-rich {100} tabular grains. In a preferred example, the crystal edge is 0.05 μm to 0.25 μm.
m, more preferably from 0.05 μm to about 0.20 μm.

2. First growing step The increasing flow rate of the silver salt and halide salt solution, preferably having or different from the composition as in the nucleation step, is for example said silver and halide at a constant flow rate for at least half of the total nucleation time. It is preferably carried out with a linearly increasing flow rate, especially after the solution has flowed. Typically, the flow rate at the end of the first growth step is up to about 5 times greater than at the start of the growth step, more preferably 1-3 times, even more preferably 1-2 times the start flow rate.

3. Second growing step The further increasing flow rate of the silver and halide solution, preferably having or different from the composition as in the first growing step, is preferably effected, for example, by a linearly increasing flow rate. Typically, the flow rate at the end of this second growth step is about 10 times greater than at the start of the growth step, more preferably 1-5 times.

In the first and second growth steps, these flow rates can be monitored, for example, by magnetic valves. During the growth process, pAg is preferably maintained at a constant value,
If desired, it can be varied to provide growth without further nucleation.

Preferably, the pH is established at a value between 2.0 and 10.0, more preferably between 3.0 and 9.0.

At least 60% of the number of particles formed,
It is most important to avoid the formation of additional new nuclei during the amphibious process to provide homogeneity such that more preferably at least 75%, even more preferably at least 90% are {100} tabular crystals. is there.

Apart from three separate growth steps, at least 50 mol%, more preferably at least 70 mo
silver chloride-rich desired {100} tabular grains having at least 1 mol%, even more preferably at least 90 mol% silver chloride, wherein said tabular grains have an average aspect ratio of at least 2,
Average thickness up to 0.25 μm with a coefficient of variation up to 0.25 and 0.3 μm with a coefficient of variation up to 0.30
m having an average equivalent circular crystal diameter of at least m) between the nucleation and the first growth step, wherein one or more dislocations are introduced on the nuclei formed in the nucleation step. Is an essential feature. The coefficient of variation is defined as the ratio between the standard deviation of the mean (thickness and crystal diameter, respectively) and the mean. This step comprises at least one ion which provides an ion selected from the group consisting of iodide ions, bromide ions, complex anions such as CN ⁻ , SCN ⁻ , SeCN ⁻ and complex metal ions satisfying the following formula (I). It is performed according to the method of the present invention by introducing the compound into a reaction vessel. [ML ₆ ] ⁿ⁻ (I) where M is an element from group VIII of the periodic system of elements (Table of Mendejew), preferably Ru ²⁺ , Os ²⁺ , Rh ³⁺ ,
Represents a metal ion that is Ir ³⁺ or Pt ²⁺ and represents L ₆
Represents six independently selected coordination complex ligands (provided that at least three of the ligands have a greater electronegativity than any halide ligand and at least four of the ligands And anionic ligands such as CN ⁻ , SCN ⁻ , and SeCN ⁻ , where n = 1, 2, 3, or 4.)

The introduction of dislocation lines in a crystal using a metal dopant is described, for example, in JP-A 07-712778, 07-.
219097,07-219097,07-12876
9 and 08-171159, and Research Disclosure
No. 377025, pp. 607-608, issued September 1, 1995.

Suitable Group VIII metal ions used in the process according to the invention for introducing crystal dislocations on the nuclei formed are, for example, Ru ²⁺ , Os ²⁺ , Rh ³⁺ , Ir ³⁺ or P ³
t ^{2 +} . Particularly preferred are ruthenium complex ion compounds, and more preferred are hexacyano-ruthenium salts. Group VIII metal ions useful in the method of the present invention are described in US-A 4981781 (Ru, Fe, Rh,
Os), 5024931 (Ru, Rh, Os, Ir, P
d, Pt), 5252456 (Pt, Ir) and 536
0712 and EP-A 0336426 (Ru, O
s), 0336427 (Ru, Os), 0415481
(Rh, Ir, Os, Ru, Fe, Co) as described in patent literature or as dopants in RD silver halide crystals. The most frequently occurring dopants in the literature are ruthenium, rhodium and iridium. Combinations of one or more dopants may be added in the same or different manufacturing steps of {100} tabular silver halide crystals rich in silver chloride.

According to the method as described in the present invention,
Preferably, the iodide and / or bromide ions are provided by an organic iodide or bromide releasing agent.
Such release agents are described, for example, in US-A 5,389,508,54.
82826, 5498516, 5524660 and 55
27664 and EP-A 0651284.

However, other techniques for making dislocations described in the method of the present invention are not excluded.

According to the method of the present invention, crystal dislocations are introduced into the nuclei formed in the nucleation step, and the anisotropic growth of said nuclei into {100} tabular grains as a function of the desired equivalent circular diameter. Is the purpose of this step. Therefore, according to the method of the present invention, the first physical after the nucleation step to obtain a number of dislocation lines of less than 5, more preferably less than 3 (ie equal to the number of one or two of said dislocation lines) The crystal dislocations are introduced in a time that does not take longer than the time required to perform the aging step. In that case, it is most important that the dislocation lines are on one and the same crystal plane in order to perform two-dimensional growth and avoid thickness growth.

According to the method of the present invention, the nuclei formed in the nucleation step during the physical ripening step following the introduction of the dislocation lines and the first growth step immediately following the physical ripening step have a growth of 2 to 10 Minutes, more preferably within a time interval of 5 to 10 minutes. The introduction of the crystal dislocation has little effect on the crystal thickness as long as a small amount of iodide is added, for example. On the other hand, when the addition amount is high, many dislocation lines which are not on one and the same crystal plane are introduced into the growth of the formed nucleus, thereby causing three-dimensional (thickness) growth.

Introducing crystal dislocations and generating dislocation lines to be located on one and the same crystal plane is the desired equivalent circular diameter (ECD) of the silver chloride-rich {100} tabular crystals described above.
Give the solution to get.

The nucleation is 0.25 μm as described in the present invention.
m or less, the thickness of the tabular {100} silver halide grains is mainly determined.
Increase the "Ostwald ripening pressure" between "ocated" and "dislocated" particles to simulate Ostwald (physical) ripening during the physical ripening time between the first and second growth steps And “non-dislocation”
Needed to annihilate particles.

During the second physical ripening step, the Ostwald ripening further destroys the fine crystals, thereby increasing the homogeneity of the equivalent circular crystal diameter at the end of the production.

The introduction of a further physical ripening step and / or a growing step is not excluded. At the end of the precipitation, it is also possible to introduce further halide ions or complex anions which form silver salts which are less soluble than silver salts present on the surface of the formed {100} tabular grains rich in silver chloride. In this method, a preferable amount of, for example, 0.05 to enhance the spectral sensitizing property and / or to reduce the pressure sensitivity is used.
Fine silver iodide mylate having a crystal diameter of 0 μm or less
(micrate) Surface conversion by iodide in the form of emulsion grains or iodide ions is highly appreciated.

The total amount of stable binder used in the dispersion medium of the reaction vessel before and during, before or during the formation of silver halide nuclei rich in silver chloride, preferably pure silver chloride. About 0.05% by weight or more, more preferably about 1% by weight or more, even more preferably 5 to 10% by weight
It is common practice to establish concentrations of colloidally stable binders in amounts up to 0% by weight. If gelatin is a colloidally stable binder, 10
Even 0% by weight gelatin is preferred.

According to the method of the present invention, said colloidally stable binder is a compound selected from the group consisting of gelatin, hydrophilic amphoteric block copolymers, colloidal silica or combinations thereof. The use of colloidal silica in the production of {100} tabular grains is described in EP-A 0767.
The use of hydrophilic amphoteric block copolymers is described in U.S. Pat. No. 5,147,771 and 514,777.
2,5147773 and 5385819.

According to the invention, preferred colloidally stable binders used in the nucleation step are the so-called "oxidized"
(oxidized) "gelatin, up to 4000 ppm
Methionine content. In a more preferred embodiment, the gelatin is oxidized to such an extent that it has a methionine content of up to 1500 ppm. In a further preferred embodiment according to the invention, said gelatin is substantially free of calcium ions and is referred to as "deionized" gelatin.

[0037] Additional gelatin may be added at a later stage of the emulsion preparation, for example after washing, to establish optimal coating conditions and / or to establish the required thickness of the coated emulsion layer. The gelatin can be a conventional calcium-containing, non-oxidized gelatin having a high amount of methionine, but calcium-free and / or oxidized gelatin is not excluded. Preferably, a weight ratio of gelatin to silver halide (silver halide is expressed as equivalent of silver nitrate) in the range of 0.2 to 1.0 is then obtained.

"Oxidized gelatin" is US-A 47133.
Defined as gelatin having a methionine content of less than 30 μmol / g according to Maskasky in 23,
That corresponds to an amount of about 4400 ppm or less. Gelatin can be oxidized, for example, by hydrogen peroxide. Publications for the determination of methionine and its oxides in gelatin can be found, for example, in J. Phot. Sci. , Vol. 41, (199).
3), pages 172-175, by S. Tani and T. Tani.

If used in a process for producing so-called "oxidized gelatin", characterized by the presence in the gelatin of an amount of methionine of less than 30 μmol / g of gelatin, as claimed in US Pat. No. 4,713,320, Numerous bromide-rich tabular grains are obtained in the grain population. In contrast, the same author discloses a method of making high chloride tabular grain emulsions using high methionine gelatin peptizers in the presence of certain pyrimidine grain growth modifiers. Many flat plates {100}
The grains have penetrated into a suitable silver chloroiodide emulsion prepared by the method described in US-A 5,413,904.
In US-A 5,413,904 the presence of oxidized gelatin in the reaction vessel seems to be an essential feature from the examples (although not specifically claimed), but for example EP-A
No mention is made of a second, preferably co-existing, gelatin which is essentially free of calcium ions as an essential feature, as described in 0843207.

EP-A 0 796 618 describes a process for preparing tabular grain emulsions in which a gelatin derivative having a chemically modified NH ₂ group is used in the grain growth step and the gelatin has a specific methionine content. ing. The methionine content of the gelatin dispersion medium was changed by the oxidizing agent to be added to the reaction vessel immediately before nucleation,
A 5372975, according to which seed particles are further added. Seed particles formed in the presence of an oxidizing agent are described in JP-A 05-210187, JP-A
06-003758 and JP-A 06-00375
9. Treatment of gelatin solutions with H ₂ O ₂ is described, for example, in JP-A 05-341415. In addition to hydrogen peroxide, other oxidizing agents such as, for example, ozone, peroxyacid salts, halogens, thiosulphonates, quinones and organic peroxides are disclosed in U.S. Pat.
4 used. In order to provide tabular grains having small twin plane separation in tabular grains rich in silver bromide, a production method using oxidized gelatin is disclosed in US-A 52.
19720. Oxidation of methionine reduces the complexing ability of gelatin. Modification of complexing ability is JP
-A can be carried out in various steps during precipitation, such as precipitation of silver halide tabular grains as described in 07-31428, whereby hydrogen peroxide is produced after nucleation and during the subsequent physical ripening step. Is added to

A process for the production of gelatin having a controlled methionine content is disclosed in US Pat. No. 5,412,075. To determine the methionine content of gelatin in a quantitative manner, see, for example, J. Phot. Sc., Vol.
80), pp. 111-118, many references are available from which the macromolecular methionine residue is the Au (III)-as the most obvious reducing substance in gelatin.
Measured by reaction with ions. The so-called “gold number (go
ld number) "is where 1 mmol of Au is 1.
It allows the determination of the amount of methionine in gelatin according to the rule corresponding to 6 mmol. J. Phot. Sc., Vol. 33
(1989), pp. 10-17, the methionine content was determined by Apostolatos and Hoff (Anal. Biochem. Vol. 11).
8 (1981), p. 126).
Measured using gas chromatography applied to gelatin by Kaplan. In this document the thermometry is used in a quantitative method for measuring methionine (constant for the first pH range examined, 3.0-8.0). J. Phot. Sc., Vol. 40 (199
2), pages 149-151, the amounts of methionine, methionine sulfoxide and methionine sulfone were determined by chromatographic techniques on amino acids (Hi
tachi amino acid analyzer), while J. Phot. Sc., Vol.
1 (1993), pp. 172-175, these compounds have been determined by HPLC techniques. J. Pho
t. Sc., Vol. 39 (1995), pp. 367-372, a gas chromatographic technique (4th IAG Conference,
Fribourg 1985, Amman-Brass & Pouradier) and Scatcha
rd technology (J. Phot. Sc., Vol. 42 (1994), 11)
Rose and Kaplan (described on pages 7-119).
It has been established that a good correlation can be found between the methionine contents measured by the method described above. In the above technique, the interaction of Ag ⁺ with gelatin at pH = 3.0 is measured by potentiometry of free Ag ⁺ ions.

It is most important to use said "oxidized" gelatin during nucleation, in a preferred embodiment 2500 pp
Less than m methionine is present in the gelatin, and in a more preferred example the methionine content is less than 1500 ppm. In a preferred embodiment according to the method of the present invention, said "oxidized" gelatin does not contain calcium. The calcium content of the most industrially high quality inert gelatin is about 0.4% or about 100 mmol / kg, measured at the end of the process for producing inert gelatin. The base for high quality gelatin is preferably formed by pure defatted hard bovine bone. In a first manufacturing step, the bone is treated with an acid to remove magnesium and calcium phosphate.
After this step, an alkaline hydrolysis step using calcium hydroxide is performed. At the low pH used to remove phosphate, calcium ions bound to specific amino acids of the polypeptide are exchanged for protons from the acid used. During alkaline hydrolysis with calcium hydroxide, the polypeptide is again saturated with calcium ions. After diafiltration, the non-removable calcium concentration in the gelatin is about 0.5% or 125 mmol /
kg. When slightly acidic during washing, the calcium content is about 0.4% (40 ppm) or 100 mm.
ol / kg. These and other data are from the scientific publication “Influence of Calcium on the
Physical properties of Gelatin Solutions and on Sy
mplex Formation with Macromolecular Polyanious ”,
BH Tavernier, J. Phot. Sci. , Vol . 40, (19
92) at pages 168-173. The authors concluded that complexed calcium ions strongly reduced the potential carried by gelatin. It has been found that there is no effect of calcium ions on physical properties such as viscosity.

The preferred so-called "calcium-free gelatin" is obtained by cation exchange with an ion exchange resin (preferably a so-called mixed bed resin). Substantially "calcium-free gelatin" is defined as gelatin having a calcium content level of 40 ppm or less, which corresponds to the analytical detection limit.

The patent literature on calcium-free or calcium-poor gelatin is quite rare. JP-A 05-173278 describes a color negative material containing gelatin low in calcium and hardened with a vinylsulfonyl hardener type. JP-A
04-321026 discloses a black-and-white multi-contrast material using special calcium-poor gelatin. 100p for JP-A 02-300745
Specific AgX materials have been described, including gelatin having a calcium content of less than pm. The literature specifically describes sensitometric improvements. Further effects on chemical ripening properties, especially with fogging, are described in JP-A
62-006251. Improvements regarding coating properties are disclosed in US-A 5,188,931 and 5,496,691.
And JP-A 03-174142. The effect on viscosity of further using small amounts of viscosity enhancers is described in JP-B 92-062064. The prevention of pressure marks by the use of gelatin containing low calcium is described in JP-A 01-179141, while the adhesive properties and curl of materials containing a defined calcium ion content are described in US Pat.
1. The effect on surface glare is JP
-B 91-080292. For rapid processing applications of materials having a well-defined amount of calcium in a gelatin binder, the drying characteristics of the material are JP-A 0
1-0733337, 03-253839 and 07-14
0576, and US-A 5,318,881 and 5302
505.

EP-A 0843207 discloses a process for producing a photographic silver halide emulsion comprising precipitation in one or more precipitation steps in a reaction vessel followed by desalting by flocculation and washing or by ultrafiltration, The emulsion comprises {100} tabular silver halide grains containing gelatin as binder and at least 50 mol% chloride, at least 40% of the total number of grains being provided by the tabular grains; The gelatin binder present in the reaction vessel during the precipitation step, wherein the particulate particles have an average aspect ratio of at least 2, an average thickness of at most 0.5 μm, and an average equivalent circular crystal diameter of at least 0.3 μm. Contains substantially no calcium ions,
A process is disclosed which is characterized in that it has been oxidized to have a methionine content of up to 4000 ppm.

After completion of the precipitation step, followed by further conversion and / or physical ripening steps, washing techniques are applied to remove excess soluble salts. Any conventional washing technique can be used, washing with some water portions after flocculation with a polymeric flocculant such as, for example, polystyrene sulfonic acid or with an inorganic salt. Emulsion washing is, for example, Research Dis
closure No. 38957 (1996), Chapter III. In a preferred example, ultrafiltration is used as a washing technique. Such a method is, for example, Research Disclosur
e Vol. 102, October, 1972, Item 1020
8; Research Disclosure Vol. 131, March, Item 1
3122 and Mignot US-A 4334012.

Emulsions prepared according to the method of the present invention comprise at least 50 mol% of silver chloride, more preferably at least 70 mol%, even more preferably at least 9 mol%.
Contains {100} tabular silver halide grains containing 0 mol% silver chloride.

In said emulsion at least 60%, more preferably at least 75%, even more preferably at least 90% of the total number of grains is provided by said tabular grains, said tabular grains being at least 2, more preferably An average aspect ratio of from 3 to 50, even more preferably from 5 to 25, with a coefficient of variation up to 0.2 with a coefficient of variation of up to 0.20.
0.3 μm or more, preferably 0.8 μm with an average thickness of 25 μm, preferably 0.05 to 0.20 μm, and a coefficient of variation of 0.30 or less, more preferably 0.25 or less.
m, even more preferably 1.2 to 10 μm, even more preferably 5 μm or less.

Chloride-rich tabular grains having a {100} crystal habit as in the present invention do not require the use of a crystal habit modifier during emulsion production as during the production of {111} tabular grains. This is particularly preferred for reproducibility.

In a preferred embodiment, the emulsion prepared according to the method of the present invention is an emulsion containing {100} tabular silver chloroiodide grains. In particular, the iodide ions used therein are located on the surface of the {100} grains as a result of the iodide conversion step at the end of the production, thereby increasing the silver iodide concentration near the crystal surface and having the highest Reach the concentration.

It is specifically believed that up to 3 mol% of iodide ions are incorporated into the silver chloroiodide grains by the method described above. This may be accomplished by the triple jet technique, in some instances by separate addition of an aqueous iodide-containing solution, or in one or more halide solutions below the desired mol% concentration required for each manufacturing step. (For example, potassium iodide). For comparison to about ^106-fold less soluble silver iodide ion and silver chloride, the iodide ion can replace the chloride ions from the particles by such conventional techniques transform. Iodide ions are incorporated into the silver halide crystal lattice in another example by the addition of a pre-made silver iodide mylate emulsion composed of either pure silver iodide or a mixed halide. In the example, the iodide is provided by an iodide releasing agent. Patent applications mentioning how iodide-releasing agents are used are described, for example, in EP-A 0 563 701, 0 563 708, 056.
1415 and 0651284. If bromide ions, even bromide releasing agents, are incorporated into the chloride-rich {100} tabular grains produced according to the method of the present invention,
It is not excluded in the precipitation step according to the method of the invention.

Two or more types of tabular silver halide emulsions prepared separately can be mixed to form a photographic emulsion for use in accordance with the present invention.

The size distribution of the chloride-rich {100} tabular silver halide grains prepared according to the method of the present invention is monodisperse in thickness and crystal diameter, up to 0.25 and 0.30, respectively, Preferably a coefficient of variation of at most 0.20 and 0.25 is measured.

Tabular silver halide emulsions containing tabular {100} grains rich in chloride prepared by the method of the present invention are described, for example, in "Chimie et Physique Photographique",
Glafkides, "Photographic Emulsion Chemistry",
GF Duffin, Making and Coating Photographic
Emulsion ", VL Zelikman et al., And" Die Grundlag
en der Photographischen Prozesse mit Silberhalogen
iden ”, edited by H. Frieser and Akademische Verlagsgesells
It can be chemically sensitized as described in chaft (1968). Chemical sensitization, as described in the literature, involves compounds containing small amounts of sulfur, such as thiosulfate, thiocyanate, thiourea, their selenium or tellurium analogues, sulfites, mercapto compounds,
And ripening in the presence of rhodamine. The emulsion is prepared by a gold-sulfur ripening agent, or a gold-selenium ripening agent, or a gold-sulfur-selenium ripening agent (in which case, a tellurium compound may be added instead of or in addition to the selenium ripening agent). Or a reducer,
For example, sensitization can also be carried out with tin compounds, amines, hydrazine derivatives, formamidine-sulfinic acid, toluenethiosulfonic acid and silane compounds as described in GB 789823. A general overview of chemical sensitization can be found in Research Disclos, published September 1, 1996.
ure No. 38957, Chapter IV. Particularly useful selenium sensitizers are, for example, EP-A 047
6345, 0831363 and 0862088.

The silver halide emulsion under consideration is described by John Wiley
& Sons, 1964, FM Hamer, “The Cyan
The compounds can be spectrally sensitized with methine dyes such as those described in "Iine Dyes and Related Compounds". Dyes that can be used for the purpose of spectral sensitization include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanines. Dyes, hemicyanine dyes, styryl dyes, and hemioxonol dyes, and particularly valuable dyes are those belonging to cyanine dyes, merocyanine dyes and complex merocyanine dyes. A particularly useful example in the context of tabular grains is described in Research Disclosure No. 38, supra.
957, given to Chapter Va.

Oxacarbocyanine is, for example, US-P
5,340,042. Particularly preferred green sensitizers in connection with the present invention are anhydro-5,5'-dichloro-
3,3'-bis (n.sulfobutyl) -9-ethyl-oxacarbocyanine hydroxide and anhydro-5
5'-Dichloro-3,3'-bis (n.sulfo-propyl) -9-ethyl-oxacarbocyanine hydroxide.

Research Disclosure No. 37312 (1
Imidacarbocyanines, such as those described in EP-A 0590593, are preferred from the standpoint of sensitivity and from the standpoint of decontamination and decolorization properties in the processing of materials containing spectrally sensitized tabular grains. And imidacarbocyanine. Suitable mixtures of oxacarbocyanine and imidacarbocyanine spectral sensitizers which are advantageously applied to decolorizing properties and sensitometry are, for example, anhydro-5,
Anhydro-5,5'-dichloro- along with 5'-dicyano-1,1'-diethyl-3,3'-di (2-acetoxyethyl) ethylimidacarbocyanine bromide
3,3'-bis (n-sulfobutyl) -9-ethyl-oxacarbocyanine hydroxide or anhydro-5
5'-Dichloro-3,3'-bis (n-sulfopropyl) -9-ethyl-oxacarbocyanine hydroxide.

In conventional emulsion production, spectral sensitization is traditionally performed after completion of chemical sensitization. However, in the context of tabular grains, it is specifically contemplated that spectral sensitization can be performed simultaneously with, or even completely prior to, the chemical sensitization step. In preferred embodiments where the tabular {100} emulsion is a chloroiodide emulsion, the spectral sensitizer may be added even before aging the ultrafiltered emulsion or redispersing the flocculated and washed emulsion. Preferred: It is believed that chemical sensitization after spectral sensitization occurs at one or more regular discrete sites on the tabular grains. In practice, the chemical sensitization is carried out, for example, by means of one or more phenidone and derivatives, dihydroxybenzenes such as hydroquinone, resorcinol, catechol and / or derivatives thereof (for example EP-
A 0718682), one or more stabilizers or antifoggants,
The reaction may be performed in the presence of the above-described spectral sensitizer or a combination of the above components. Particularly 1-p-carboxyphenyl,
4,4'Dimethyl-pyrazolidin-3-one was converted to US-A
It may be added as a suitable adjuvant as disclosed in US Pat.

The silver chloride-rich gelatin emulsion prepared according to the method of the present invention is further coated in a hydrophilic layer. The hydrophilic layer, like the non-photosensitive layer of the photographic material according to the invention, may contain compounds which stabilize photographic properties or prevent fogging during the manufacture or storage of the photographic material or during its photographic processing.

Many known compounds can be added as fog inhibitors or stabilizers to the silver halide emulsion layers or to other coating layers in water-permeable relationship therewith, such as undercoats or protective layers (3- Pyrazolidone compounds can be added as described in EP-A 528 480 where they are used). Suitable examples are heterocyclic nitrogen-containing compounds, such as benzothiazolium salts, nitroimidazole, nitrobenzimidazole, chlorobenzimidazole, bromobenzimidazole, mercaptothiazole, mercaptobenzothiazole, mercaptobenzimidazole, mercaptothiadiazole, aminotriazole , Benzotriazole (preferably 5-
Methyl-benzotriazole), nitrobenzotriazole, mercaptotriazole, mercaptotetrazole, especially 1-phenyl-5-mercapto-tetrazole and acetamido-1-phenyl-5-mercaptotetrazole, mercaptopyrimidine, mercaptotriazine, mercapto-imidazole, mercapto Thiadiazole, mercapto-oxadiazole, benzothiazoline-2-thione, oxazoline-thione, triazaindene, tetraazaindene and pentaazaindene, especially by Birr, Z. Wiss. Phot. 47 (1952), 2
-Described by page 58, GB Patent 120
3775 and 1209146, JP-A 753953
7, and triazolopyrimidines such as those described in GB Patent No. 1500278, and US-A 47270
7-hydroxy-s-triazolo- as described in 17
[1,5-a] -pyrimidine and other compounds such as benzenethiosulfonic acid, benzenethiosulfinic acid and benzenethiosulfonic acid amide, and US-A 549
1055 and 5631126 are sulfodihydroxyaryl compounds.

Other compounds which can be used as the fogging inhibiting compound are described in Research Disclosure No. 17643 (197)
8), Chapter VI and RD No. 38957 (199)
6), Chapter VII. Many of these antifogging compounds are rich in silver chloride as described above.
0 ° Already added during chemical ripening of tabular silver halide crystals.

To establish the optimum coating conditions and / or to establish the required thickness of the coated emulsion layer, additional gelatin may be added at a later stage in the emulsion preparation, for example after washing. It is clear. Preferably 0.2 to
A ratio of gelatin to silver halide in the range of 1.0 is then obtained, in which case the extra gelatin added is not required to have a particular composition as in the preparation of the grains by the method of the present invention. 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 gelatin binder of the photographic material having at least one gelatin emulsion according to the present invention may be any suitable hardener, for example of the epoxide type, of the ethyleneimine type, of the vinylsulfone type (for example 1,3-vinyl Sulphonyl-2-propanol, bis-vinyl-sulphonyl-methane or ethane), substituted with hydroxyl groups to give good solubility in aqueous media, chromium salts (for example chromium acetate and alum), aldehydes (for example Formaldehyde, glyoxal, and glutaraldehyde), N-methylol compounds (eg, dimethylolurea and methyloldimethylhydantoin), dioxane derivatives (eg, 2,3-dihydroxy-dioxane), active vinyl compounds (eg, 1,3,5)
-Triacryloyl-hexahydro-s-triazine), an active halogen compound (eg, 2,4-dichloro-
6-hydroxy-s-triazine), and mucohalic acids (e.g., mucochloric acid and mucophenoxychloric acid). These compounds can be used alone or in combination. The binder is US-A4
A fast-reacting curing agent such as a carbamoylpyridinium salt as disclosed in EP-A04
Curing with an onium compound as disclosed in 08143 is also possible.

A review of hardeners useful for hardening the hydrophilic layer of a material containing one or more {100} tabular silver halide grains rich in silver chloride prepared according to the present invention is, for example, RD38957, Chapter IIb Can be found in

In a preferred embodiment, the hydrophilic layer package of a silver halide photographic material comprising one or more {111} tabular emulsions enriched in silver bromide crystals prepared in accordance with the method of the present invention in one or more photosensitive layers comprises: It has a swelling degree of 200% or less. The degree of swelling is measured by the following procedure: a sample of the coated material is incubated at 57 ° C. and 34% RH for 3 days, after which the thickness (a) of the layer assembly is measured. Thereafter, the sample is immersed in distilled water at 21 ° C. for 3 minutes, and the thickness (b) of the swollen layer is measured. The degree of swelling is Δ (ba) /
It is calculated as a｝ 100 (%).

The gelatin emulsions containing {100} tabular grains rich in silver chloride of the present invention can be used in various types of photographic materials, such as black-and-white silver halide photographic materials such as those used for X-ray diagnostic purposes, Or it can be used for color sensitive materials.

In a preferred embodiment, the photographic material is a photographic material comprising a support and at least one light-sensitive silver halide emulsion layer on at least one side of said support, said emulsion layer being prepared according to the method of the present invention. And one or more emulsions containing {100} tabular silver halide emulsion grains.
In a further preferred embodiment, said photographic material is a single-sided or double-sided X-ray material.

The single-sided coated X-ray material may comprise a single emulsion layer (which applies for many applications), or it may be made by two or more emulsion layers. In radiography, a material having a single or double coated emulsion layer coated on one or both sides of the support contains at least one gelatin silver halide emulsion according to the invention.

By using double coated emulsions differing in photographic speed by at least 0.15 log E, an increase in crossover exposure in the double coated material can be obtained. In the case of color photography, the material contains blue, green and red sensitive layers (each of which can be single coated as the most common color positive materials), but may have a double or multiple color like color negative or color intermediate applications. It can also consist of triple layers.

In a preferred embodiment according to the present invention, said photographic material comprises at least two layers having a negative-image silver halide emulsion adjacent to each other, the emulsion layers closer to said support being prepared according to the method described above. At least one emulsion having tabular emulsion crystals selected from the group consisting of silver chloride, silver chlorobromide, silver chloroiodide and silver chlorobromoiodide having a habit of 100 °, further away from the support. The adjacent layer comprises at least one emulsion having an essentially cubic emulsion selected from the group consisting of silver chloride, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide, silver bromide and silver bromoiodide. Including. This layer arrangement is particularly advantageous for pressure insensitivity, but is also useful for improving image tones. Other means for improving image tones are described in EP-A 0789
266, which describes leuco dyes that form dyes by reaction with oxidized developer near the developed particles. Leuco dye is US-A
No. 4,865,958 has already been described for this purpose.

In addition to the light-sensitive emulsion layers, the photographic material may contain several light-insensitive layers, such as a protective layer, one or more backing layers, one or more subbing layers, one or more interlayers, such as a filter layer, and a hardening layer, for example. It may include an after layer containing an agent, an antistatic agent, and a filter dye for safety light purposes. The photographic material of the present invention is described in RD No. 38957 (1996), Chap.
Various additives that modify the coating physical properties, such as those described in ter IX (in which coating aids, plasticizers, lubricants, antistatic agents and matting agents are described) may also be included. Development acceleration is achieved by various compounds, preferably, for example, US-A 30388.
05, 4038075, 4292400 and 55695
76, and a polyalkylene derivative having a molecular weight of at least 400, such as those described in EP-A 0 634 688, in the emulsion layer or adjacent layers.

The photographic material of the present invention may further comprise various other additives such as compounds which improve the dimensional stability of the photographic material, UV absorbers and spacing agents.

Additives suitable for improving the dimensional stability of photographic materials are, for example, water-soluble or poorly water-soluble synthetic polymers such as alkyl (meth) acrylates, alkoxy (meth) acrylates, glycidyl (meth) acrylates, ( (Meth) acrylamide, vinyl ester, acrylonitrile, olefin, and styrene polymers, or the above and acrylic acid, methacrylic acid, α-β-
Dispersions of unsaturated dicarboxylic acids, hydroxyalkyl (meth) acrylates, sulfoalkyl (meth) acrylates, and styrene sulfonic acids).

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 2784/71, cinnamic acid ester compounds as described in U.S. Pat. Nos. 3,705,805 and 3,707,375, U.S. Pat.
229, and US-A
A benzoxazole compound as described in No. 3700455 and a suitable optical brightener are also described in RD No.
38957 (1996), Chapter VI. UV absorbers are particularly useful in color materials,
They prevent light-induced regression of the color image formed after processing.

The spacing agent generally has an average particle size of 0.2.
Those that are between 10 and 10 μm can be present. 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.

The photographic material may comprise several light-insensitive layers, such as a stress-resistant topcoat layer, one or more backing layers, and one or more filters that absorb scattered light and thus enhance image sharpness or contain antihalation dyes. Of an intermediate layer. Suitable light-absorbing dyes for use in these intermediate layers are described, for example, in U.S. Pat.
SA 4311787, DE-A 2453217,
And GB Patent 7907440.

Due to the location of such an intermediate layer between the emulsion layer and the support, decolorization of the filter dye layer in rapid processing conditions forms a problem, as well as a small negligible loss in sensitivity. Therefore, it is recommended to reduce the thickness of the entire coating layer packet and shorten the drying time after cleaning in the processing cycle. Alternatively, the use of an interlayer between the emulsion layer and the support, which reflects the fluorescence emitted by the screen, may provide a solution. Since the light emitted from the screen by the incorporated phosphor is a very important source of light scattering, the addition of an appropriate filter dye to the screen is recommended. For example, in a screen of a green light emitting phosphor, MAKROLEX ORAN
Certain dyes may be used, such as GE G or GG, a trademark product of BAYER AG.

One or more backing layers can be provided on the non-light sensitive side of the support of a material having only one side of the support coated with at least one emulsion layer. These layers, which can act as anti-curl layers, include matting agents such as silica particles,
Conventional ingredients such as lubricants, antistatic agents, light absorbing dyes, opacifiers (eg, titanium oxide) and hardeners and wetting agents can be included.

The support of the photographic material can be opaque or transparent, for example a paper support or a resin support. When a paper support is used, preference is given to those coated on one or both sides with an α-olefin polymer, for example a polyethylene layer containing, if desired, an antihalation dye or pigment. Further, an organic resin support such as a cellulose nitrate film, a cellulose acetate film, a poly (vinyl acetal) film, a polystyrene film, a poly (ethylene terephthalate) film or a poly (ethylene naphthalate) film, a polycarbonate film, a polyvinyl chloride film, or a poly (ethylene chloride) film -Α-olefin films (for example, polyethylene or polypropylene films) can also be used. The thickness of such an organic resin film is preferably 0.07 to 0.35 mm. These organic resin supports are preferably coated with a subbing layer that can contain water-insoluble particles such as silica or titanium dioxide. A further overview of useful supports is R
D38957, Chapter 15.

$ 10 produced according to the method of the present invention
Photographic materials containing 0 ° tabular grains can be image-wise exposed by any convenient radiation source according to the particular use.

Of course, the processing conditions and the composition of the processing solution are determined by the particular type of photographic material to which the chloride-rich {100} tabular grains prepared according to the present invention are applied. For example, in a preferred example of a material for X-ray diagnostic purposes, the material may be adapted to rapid processing conditions in a developer containing or not containing hydroquinone as the main developing agent. Ascorbic acid (preferably 1-ascorbic acid or isoascorbic acid), reductic acid or their derivatives as more ecological developing agents can be partially or completely replaced by hydroquinone. Preferably, an automated processor is used provided with a system for automatic regeneration of the processing solution.

The pre-cured material may be processed using one-part or three-part package chemicals depending on the processing application that determines the degree of cure required for the processing cycle. Applications within the generally known processing time of 30 seconds or less to 90 seconds are possible.
From an ecological point of view, for example, sodium thiosulfate can be used instead of ammonium thiosulfate.

The present invention will be described with reference to the following examples, but the present invention is not limited thereto.

[0084]

EXAMPLES Preparation of Emulsion A (Emulsion of the Invention) 156 g of gelatin, 800 ppm of methionine and 4
1160 m containing less than 0 ppm calcium ions
1 dispersing medium (C) was fed into the stirring reaction vessel.
The pCl was adjusted to a value of 2.0 with sodium chloride; pH
Was adjusted to a value of 5.7 and the reaction vessel was kept at a constant temperature of 35 ° C.

While stirring this solution vigorously, 76 ml of 2.94 mol silver nitrate solution and 76 ml of 2.94 mol
1 sodium chloride solution by double jet precipitation
Added simultaneously at a rate of 80 ml per minute.

1250 containing 456 mg of potassium iodide and 600 mg of sodium chloride in the reaction vessel.
pour the solution to 50 ° C over the next 5 minutes.
Was raised. ( 1 )

While maintaining the pCl value at 2.2 and the temperature at 50 ° C., 58 ml of a 2.94 mol silver nitrate solution and 5 ml
8 ml of a 2.94 mol sodium chloride solution were simultaneously added at a rate of 8 ml per minute each.

While reducing the pCl value from 2.2 to 1.8 and increasing the temperature from 50 ° C. to 65 ° C.,
Both 19 ml of the 2.94 mol silver nitrate solution and 119 ml of the 2.94 mol sodium chloride solution were added simultaneously at an addition rate of linearly increasing from 8 ml to 12 ml per minute.

The temperature of the mixture in the reaction vessel was further increased to 65 ° C.
Was held for 20 minutes.

While maintaining the pCl value at 1.8 at 65 ° C., an additional 477 ml of the 2.94 mol silver nitrate solution and 477 ml of the 2.94 mol sodium chloride solution were both increased from 8.8 ml per minute to 28 ml per minute. At the same rate.

The temperature of the mixture in the reaction vessel was further raised to 65 ° C.
Was held for 30 minutes.

80 ml of a solution containing 2 g of potassium iodide were poured into the mixture obtained in the reaction vessel. ( 2 )

While maintaining the pCl value at 1.8 and the temperature at 65 ° C., 70 ml of 2.10 by double jet precipitation.
A 94 mol silver nitrate solution and 70 ml of a 2.94 mol sodium chloride solution were added simultaneously at a rate of 8 ml per minute.

P. S. The above steps ( 1 ) and ( 2 ) are both so-called "iodide conversion steps".

Preparation of Emulsion B (Comparative emulsion without iodide addition after nucleation ) Emulsion A except for iodide addition step (1) (that is, no dislocation is formed on the formed nucleus) A tabular silver chloride emulsion was produced by performing the same production method as described above.

Preparation of emulsion C ( two separate precipitation steps)
Comparative emulsion with only 156 g gelatin, 800 ppm methionine and 4
1160 m containing less than 0 ppm calcium ions
1 dispersing medium (C) was fed into the stirring reaction vessel.
The pCl was adjusted to a value of 2.0 with sodium chloride; pH
Was adjusted to a value of 5.7 and the reaction vessel was kept at a constant temperature of 35 ° C.

While stirring this solution vigorously, 76 ml of 2.94 mol silver nitrate solution and 76 ml of 2.94 mol
sodium chloride solution by double jet precipitation.
Added simultaneously at a rate of 80 ml per minute.

1250 containing 456 mg of potassium iodide and 600 mg of sodium chloride in the reaction vessel.
pour the solution and allow the temperature of the mixture to rise to 65 over the next 25 minutes.
° C.

While maintaining the pCl value at 1.98 and the temperature at 65 ° C., 724 ml of a 2.94 mol silver nitrate solution and 724 ml of a 2.94 mol sodium chloride solution were simultaneously added at a rate of 4 ml per minute.

Table 1 below summarizes the following parameters and the values measured in connection therewith:% tabs: thickness of up to 0.25 μm in the emulsion, counted from pictures taken from electron microscopy investigations $ 10 with
0% procentual amount of tabular grains; -t: average thickness of {100} tabular grains calculated from shaded grains on photographs from electron microscopy images;-var. Coeff .: ECD: diameter of a circle having the same area as the projected area of the measured {100} tabular grains, the standard deviation for the average thickness and the coefficient of variation for the thickness formed from the ratio of the thickness of the individual grains; Mean circle equivalent diameter calculated from electron microscope images, defined as

[0101]

[Table 1]

As can be concluded from Table 1, the {100} tabular grain emulsions rich in silver chloride prepared according to the method of the present invention have an ECD of 0.3 μm or more for the purposes of the present invention.
Gives significantly improved homogeneity of crystal habit (see% tabs) and thickness (t) (see coefficient of variation denoted as "var.coeff." In Table 1) for particles having

Processes without the introduction of dislocations on the nuclei formed (Comparative Emulsion B) or with only two separate precipitation steps (Comparative Emulsion C) do not clearly lead to the above-mentioned desired objectives.

Having described preferred embodiments of the invention in detail, it will be apparent that those skilled in the art can make numerous modifications without departing from the scope of the invention as defined in the appended claims. Would.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G03C 1/09 G03C 1/09 (72) Inventor Jean Cuipel Septorate, Mozère, Belgium 27 Agfa Gévelt Namloze Bennauert In the chap

Claims (8)

[Claims] 1. A process for preparing a light-sensitive silver halide photographic emulsion, comprising performing at least three separate precipitation steps in an aqueous medium into a reaction vessel and then desalting by flocculation and washing or by ultrafiltration. Wherein said emulsion is a colloidally stabilized binder and at least 5
Including {100} tabular silver halide grains containing 0 mol% silver chloride, at least 60% of the total number of grains
Is provided by the tabular grains, wherein the tabular grains have an average aspect ratio of at least 2, an average thickness of at most 0.25 μm with a coefficient of variation of at most 0.25, and a coefficient of variation of at most 0.20. The three separate precipitation steps are a nucleation step and two growth steps, wherein the method is formed in the nucleation step after the end of the nucleation step. Further introducing one or more crystal dislocations on the nucleus, and giving anisotropic growth of the nucleus into {100} tabular grains,
The introduction of said crystal dislocations is carried out in a time no longer than the time required to carry out the first physical ripening step after the nucleation step in order to obtain a number of dislocation lines of less than 5 on one and the same crystal plane. A method for producing a photosensitive silver halide photographic emulsion, wherein the physical ripening step between the growth of the dislocation-containing nucleus and the introduction of the dislocation in the first growth step is performed within a time interval of 2 to 10 minutes. 2. The method of claim 1, wherein said binder is a compound selected from the group consisting of gelatin, a hydrophilic amphoteric block copolymer and colloidal silica or a combination thereof. 3. The nucleation step provides between 1% and 20% of the total silver nitrate used, and silver and halide ions form silver chloride-rich cubic nuclei having a crystal edge of at most 0.25 μm. 3. The method of claim 2, wherein the method is introduced at a flow rate to obtain. 4. An ion selected from the group consisting of an iodide ion, a bromide ion, a complex anion, and a complex metal ion satisfying the formula (I), wherein crystal dislocations are introduced on nuclei formed in the nucleation step. according to claim 2 of the method is carried out by introducing into the reaction vessel at least one compound give: [M L _6] ^n-(I) wherein, M is an element from group VIII of the periodic table of the elements, Preferably, Ru ²⁺ , Os ²⁺ , Rh ³⁺ , Ir ³⁺ or Pt
Represents a metal ion that is ²⁺ , and L ₆ represents _six independently selected coordination complex ligands (provided that at least three of said ligands are more electronegativity than any halide ligand) And at least four of the ligands are anionic ligands, where n = 1, 2, 3, or 4.) 5. The method according to claim 4, wherein the iodide ions and / or the bromide ions are provided by an organic iodide or bromide releasing agent. 6. The introduction of said crystal dislocations does not take longer than the time required to carry out the first physical ripening step after the nucleation step to obtain a number of dislocation lines of less than 3 on one and the same crystal plane. The method according to any of claims 2 to 5, which is performed in time. 7. {100} containing a colloidally stabilizing binder and at least 50 mol% of silver chloride.
A photographic emulsion comprising tabular silver halide grains, wherein at least 60% of the total number of grains is provided by said tabular grains, said tabular grains having an average aspect ratio of at least 2 and a variation of at most 0.25. Up to 0.2 with coefficients
A photographic emulsion prepared according to the method of any of claims 1 to 6, having an average thickness of 5 µm and an average equivalent circular crystal diameter of 0.3 µm or more with a coefficient of variation of at most 0.20. 8. A photographic material comprising a support and at least one photosensitive silver halide emulsion layer on at least one side of said support, said emulsion layer comprising one or more photographic emulsions according to claim 7. Including photographic materials.