JP2000056419A - Photosensitive emulsion with silver chloride-rich {100} flat platy grain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photosensitive emulsion with silver chloride-rich flat platy photosensitive silver halide grains by introducing a specified polyoxyalkylene block copolymer into a reactor after a 1st growth step. SOLUTION: At least three separate precipitation steps are carried out in an aq. medium in a reactor and desalting is carried out by washing after flocculation or by ultrafiltration. The separate precipitation steps are one nucleus forming step and subsequent 1st and 2nd growth steps. A polyoxyalkylene block copolymer of the formula is introduced into the reactor after the 1st growth step. The block copolymer contains at least three terminal hydrophilic polyoxyethylene groups and at most one terminal hydrophobic polyoxypropylene block unit besides ethylenediamine units as tetravalent bonding units.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a silver chloride rich # 10
0 Photosensitivity with tabular silver halide grains {100}
The invention relates to emulsions, their preparation and the use of said emulsions in photographic materials.

[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 1.5. 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; WO-Application 94/220.
51 and 94/22054 and EP-A 056997.
1: 0584815; 0584644; 060287
8; 0616255; 0617317; 061732
0; 06173321; 0617325; 061849
2: 0618493; 0653659 and 065366
9.

[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. In addition, improved reproducibility of sensitometric properties can be expected when compared to equivalent {111} tabular silver halide 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.

[0013] Tabular grains having a higher aspect ratio and reduced thickness are coated halogens required to obtain the same power, speed and gradation within a short processing time when compared to thick crystals of lower aspect ratio. Thin crystals having such a high aspect ratio are appreciated because they are more preferred with respect to the amount of silver halide.

Furthermore, in addition to the desired {100} tabular grains, for example, cubic grains (having an aspect ratio of less than 1.5) or substantially cubic grains (for a short edge length l of 10 or more cylindrical shapes) Needles having a ratio of long edge length L) and single twins (<111>, <311> or <4
11> The reduction in the presence of grains having a habit deviating from the desired one, such as a cubic {100} crystal having one single twin plane along the plane, is similar in terms of crystal habit homogeneity. Is desired.

The present invention (having a ratio of the long edge length L to the short edge length l of the rectangle of 10 or less, more preferably 5 or less)
Teachings about tabular emulsion grains (or crystals) rich in silver chloride with {100} crystal habit, especially average aspect ratios of 5 or more, average equivalent grains or crystal diameters of at least 0.3 μm and thicknesses of less than 0.25 μm To the teachings of particles having

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an emulsion having photosensitive silver halide tabular grains rich in silver chloride and {100} major faces, an average aspect ratio of 5 or more and an average equivalent of at least 0.3 μm. To provide a process for the preparation of those grains having a circular grain diameter, wherein the number of {100} tabular grains having a thickness of less than 0.25 μm to {100} tabular grains of greater than 0.25 μm in the emulsion. Are significantly increased.

A further object is to reduce the percentage number of grains other than {100} tabular grains.

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

[0019]

SUMMARY OF THE INVENTION It is an object of the present invention to provide {100} tabular silver halide grains containing at least 50 mol% silver chloride and a colloidally stabilizing binder, wherein the total number of grains is reduced. Are provided by the tabular grains, exhibit an average aspect ratio of at least 5 and an average equivalent circular grain diameter of at least 0.3 μm, wherein the tabular grains are at least 7% of the total tabular grains.
It is realized by a photosensitive silver halide photographic emulsion having an average thickness of less than 0.25 μm for 5%.

There is provided a process for preparing said emulsion, comprising performing at least three separate precipitation steps in an aqueous medium in a reaction vessel, followed by washing after aggregation or desalting by ultrafiltration. Wherein said three separate precipitation steps comprise a nucleation step, followed by a first and a second growth step, wherein said method comprises adding said reaction vessel to said reaction vessel after said first growth step (preferably before said second growth step). It is characterized by introducing a block copolymer according to formula (I) as described below.

The claimed emulsion also comprises a block copolymer according to formula (I), wherein the block copolymer has at least three numbers of hydrophilic polyoxyethylene units and at most one number of hydrophobic polymers. It comprises a functional polyoxypropylene block unit and ethylenediamine as a tetravalent binding unit.

Embedded image

[0022]

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
halide salt (preferably pure silver chloride salt) having 1%, even more preferably substantially free of iodide
And about equimolar addition of silver salt. 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 between 0.05 μm and 0.25 μm, more preferably between 0.05 μm and 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 growth 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 by a linearly increasing flow rate. Typically, the flow rate at the end of this second growth step is up to about 10 times, more preferably 1 to 5 times, and even more preferably 1 to 3 times, at the start of the growth step.

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.

According to the invention, a method in which there are three separate precipitation steps is to introduce the block copolymer according to formula (I) into the reaction vessel after the first growth step (more preferably before the second growth step). The block copolymers contain at least three terminal hydrophilic polyoxyethylene groups and at most one terminal hydrophobic polyoxypropylene block unit in addition to ethylenediamine units as tetravalent linking units.

A representative block copolymer according to formula (I) is the commercially available copolymer TETRONIC 1508® from BASF, Ludwigshafen, Germany.

In a preferred embodiment of the method according to the invention, the introduction of the block copolymer into the reaction vessel takes place after the first growth step and before the second growth step.

In the reaction vessel, the pH is 2.0 to 10.
It is preferably set to a value of 0, more preferably 3.0 to 9.0. At least 70 of the number of particles formed
%, More preferably at least 80%, and even more preferably at least 90%, to provide homogeneity such that they are {100} tabular crystals. is important.

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 are at least 75% of the total number of tabular grains.
%, Indicating an average thickness of less than 0.25 μm and an average aspect ratio of at least 5 and an average equivalent circular particle diameter of at least 0.3 μm) between the nucleation step and the first growth step. It is an essential feature to have a crystal dislocation step in which the above dislocations are introduced onto nuclei formed in the nucleation step.

EP filed on October 24, 1997
This process, described in Application No. 97203311, comprises iodide ions, bromide ions, CN ⁻ , SCN ⁻ , SeC
N ^- carried out by introducing at least one compound providing complex anions and the following equation ions selected from the group consisting of complex metal ions satisfying (II), such as in the reaction vessel. During [M _{L 6]} ^n-(II) formula, M represents an element from group VIII of the Periodic Table of the Elements (table Mendelejew), preferably ^{Ru 2+, Os 2+,} Rh
³⁺ , Ir ³⁺ or Pt ²⁺ , and L ₆ represents six independently selected coordination complex ligands (provided that at least three of said ligands are more electrically charged than any halide ligand) The degree of negativity is high, and at least four of the ligands are anionic ligands such as CN ⁻ , SCN ⁻ , and SeCN ⁻ and 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, 07-159913 and 08-171159.

Suitable Group VIII metal ions used to introduce crystal dislocations on the nuclei formed are, for example, R
u ²⁺ , Os ²⁺ , Rh ³⁺ , Ir ³⁺ or Pt ²⁺ . Particularly preferred are ruthenium complex ion compounds, and more preferred are hexacyano-ruthenium salts.

Group VIII metal ions useful in the process of the present invention (the addition of which is not particularly limited during nucleation in silver halide crystals) are described in US Pat.
u, Fe, Rh, Os), 5024931 (Ru, R
h, Os, Ir, Pd, Pt), 5252456 (P
t, Ir) and 5360712 and EP-A 0336.
426 (Ru, Os), 0336427 (Ru, Os)
s), 0415481 (Rh, Ir, Os, Ru, F
e, Co) and 0762192 (Ir) and Research
Disclosure No. 38957, chapter I, D (3) (1
Issued September 1, 996).

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.

When iodide and / or bromide ions are used, these ions may be provided by an organic iodide or bromide releasing agent. Such release agents are described, for example, in US-A 5,389,508, 5,482,826, 549.
8516, 5524660 and 5527664 and EP
-A 0651284. However, other techniques for making dislocations are not excluded.

The crystal dislocations in the nuclei performed by the method of the present invention are introduced to provide anisotropic growth of said nuclei into {100} tabular grains. To obtain the desired crystal diameter of at least 0.3 μm, less than 5, more preferably 3
The time required to perform the first physical ripening step after the nucleation step to obtain a number of dislocation lines less than (i.e., equal to the number of one or two of said dislocation lines) It is important to introduce crystal dislocations. 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. The growth of nuclei formed in the nucleation step during the first growth step immediately following the physical ripening step and the physical ripening step following the introduction of the dislocation lines is 2 to 30 minutes, more preferably 2 to 30 minutes.
Within a 10 minute time interval.

The introduction of the crystal dislocation has little effect on the crystal thickness as long as, for example, a small amount of iodide is added. 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 thereby generating dislocation lines located on one and the same crystal face, is a process which is part of three separate precipitation steps according to the method of the present invention. It is important to provide the desired equivalent circular diameter (ECD) of the silver chloride-rich {100} tabular crystals as a function of the amount of silver nitrate added to them and to not provide any thickness growth.

Nucleation primarily determines the thickness of tabular {100} silver halide grains that are 0.25 μm or less for at least 75% of the total tabular grains as described in the present invention. The growth process is called “non-dislocated”
"Ostwald ripening pressure" between "" and "dislocated" particles,
It is required to simulate Ostwald (physical) ripening during the physical ripening time between the first and second growth steps and to eliminate "non-dislocation" particles.

Thickness having a homogeneous crystal distribution as a result of the presence of a low amount of particles having an equivalent volume diameter of less than 0.03 μm in the presence of the block copolymer according to formula (I) in the reaction vessel before the onset of nucleation We can expect growth.

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

It is not excluded that a physical ripening step and / or a growing step are further introduced. 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 (also called "Lipmann emulsion") 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.

According to the method of the present invention, the binder used is a compound selected from the group consisting of gelatin, a block copolymer corresponding to formula (I) and colloidal silica or a combination thereof. Gelatin is almost always present except when the colloidal silica is present as a single colloid other than, for example, a block copolymer corresponding to formula (I). In that case, the presence of an onium compound, more preferably a phosphonium compound, is described, for example, in EP-A 06
Very preferred as disclosed in 77773.
The use of colloidal silica in the production of {100} tabular grains is described in EP-A 0 767 400.

According to the method of the present invention, up to 4 when gelatin is present as a colloidally stable binder.
Gelatin having a methionine content of 000 ppm (so-called "oxidized" gelatin) is preferred, and gelatin having a calcium content of less than 40 ppm (so-called "calcium-free" gelatin) is more preferably used. The "oxidized" gelatin has a methionine content of up to 4000 ppm, but in a more preferred embodiment the gelatin is oxidized to such an extent that it has a methionine content of up to 1500 ppm. Gelatin substantially free of calcium ions is also referred to as "deionized" gelatin. Additional information on these special types of gelatin is dealt with in EP-A 0843207.

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.

The emulsion prepared according to the method of the present invention comprises 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.

Additional gelatin, colloidal silica and / or a block copolymer according to formula (I) may be added after emulsion preparation to establish optimal coating conditions and / or to establish the required thickness of the coated emulsion layer. In the step, for example, it may be added after washing. The gelatin can be a conventional (calcium-containing and thus non-deionized) non-oxidized gelatin having a high amount of methionine, but calcium-free and / or oxidized gelatin is not excluded. . Preferably 0.2 to
A weight ratio of gelatin to silver halide (silver halide expressed as equivalents of silver nitrate) in the range of 1.0 is then obtained.

In said emulsion, at least 70%, more preferably at least 75%, even more preferably at least 90% of the total number of grains is at least 0.3 μm.
m, for example, 0.3 μm to 10 μm, preferably 0.7 μm
provided by said tabular grains having an average equivalent circular grain diameter of m to 5 μm, more preferably 0.7 μm to 2.5 μm, said tabular grains being at least 5, more preferably 5 to 50, even more preferably 5 to 5 μm. Average aspect ratio of ２５25, at least 75 of the total number of tabular grains present
% Of less than 0.25 μm, preferably 0.05 to
Shows an average thickness of 0.20 μm.

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 methods 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. The iodide ions are, in another example, formed by the addition of a pre-made silver iodide mylate emulsion (also referred to as a Lippmann emulsion) composed of either pure silver iodide or mixed halides. Although incorporated in the preferred embodiment, the iodide is provided by an iodide releasing agent. Patent applications mentioning how iodide-releasing agents are used include, for example, EP-A 0563
701, 0563708, 0561415 and 0651
284. Even in the case of bromide releasing agents, the bromide ions are rich in chloride produced according to the method of the present invention.
If incorporated into 0 ° tabular grains, they are not excluded in the precipitation step according to the method of the present invention.

Tabular silver halide emulsions containing tabular {100} grains rich in silver chloride prepared by the process of the present invention are described, for example, in "Chimie et Physique Photographique",
P. Glafkides, “Photographic Emulsion Chemistry
”, GF Duffin,“ Making and Coating Photogra
phic Emulsion ”, VL Zelikman et al., and“ Die Gru
ndlagen der Photographischen Prozesse mit Silberha
logeniden ”, edited by H. Frieser and Akademische Verlagsge
It can be chemically sensitized as described in sellschaft (1968). Chemical sensitization, as described in the above references, ages in the presence of small amounts of sulfur containing compounds such as thiosulfate, thiocyanate, thiourea, its selenium or its tellurium analog, sulfite, mercapto compounds, and rhodamine. Can be performed. 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, such as a tin compound, an amine, a hydrazine derivative, formamidine- as described in GB 789,823.
Sensitization can also be achieved with sulfinic acid, toluenethiosulfonic acid and silane compounds. A general overview of chemical sensitization can be found in Research Di, published September 1, 1996.
It can be found in sclosure No. 38957, Chapter IV. Particularly useful selenium sensitizers are, for example, EP-A04
76345 and EP Application No. 96202612 (199)
(Filed September 18, 2006) and 97200590 (1997)
(Filed March 1, 2012). Selenium and / or tellurium sensitizers are described in US-A 5,654,134.

The silver halide emulsion under consideration is described by John Wiley
& Sons, 1964, FM Hamer, “The Cyan
Species 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 merocyanine 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. 389, supra.
57, given to Chapter Va. Oxacarbocyanines are described, for example, in US-P 5,340,442. 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 Disclosu
Imidacarbocyanines, such as those described in Re No. 37312 (1995), are like EP-A 0590593 from the standpoint of sensitivity and from the standpoint of decontamination and decolorization properties in the processing of materials containing spectrally sensitized tabular grains. It is useful with a combination of various oxacarbocyanines and imidacarbocyanines. Description of the combination of oxacarbocyanine and imidacarbocyanine dyes is given in US-P 33
97060, 3814609, 3865598, 386
4134, 5597687, 5296345, 5338
655 and 5541047, and DE-A 27343
35, EP-A 0608955 and EP Application No. 98
200601 (filed January 13, 1998).

Suitable mixtures of oxacarbocyanine and imidacarbocyanine spectral sensitizers which are advantageously applied to decolorizing properties and sensitometry are, for example, anhydro-5,5'-dicyano-1,1'-diethyl- 3,3 '
Anhydro-5,5'-dichloro-3,3'-bis (n-sulfobutyl) -9-ethyl-oxacarbocyanine hydroxide or anhydro- with di- (2-acetoxyethyl) ethyl imidacarbocyanine bromide
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 effected, for example, by means of one or more phenidone and derivatives, dihydroxybenzenes such as hydroquinone, resorcinol, catechol and / or derivatives thereof (eg EP-
A 0718682), one or more stabilizers or fogging inhibitors,
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 layer or to other coating layers which have a 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 Birr, Z. Wiss. Phot. 47 (1952), 2-5.
What is described by page 8, GB Patent 12037
57 and 1209146, JP-A 7539537,
And triazolopyrimidines such as those described in GB Patent No. 1500278, and US Pat. No. 4,727,017.
7-hydroxy-s-triazolo- as described in
[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. Another compound that can be used as a fogging inhibitor is Research Disclosure No. 1.
7643 (1978), Chapter VI and RD No. 38
957 (1996), Chapter VII.
Another overview, especially for {100} tabular grains, is EP-A
0617320.

Many of these antifogging compounds have already been added during the chemical ripening of the {100} tabular silver halide crystals rich in silver chloride as described above.

In order to establish optimal 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 process of preparing the grains according to 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 (eg of 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 the onium compounds disclosed in 08143 is also possible.

A summary of useful hardeners 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, a hydrophilic layer of a silver halide photographic material comprising one or more {100} tabular silver halide emulsions rich in silver chloride crystals prepared according to the method of the present invention in one or more photosensitive layers. The package has a degree of swelling of less than 200%. The degree of swelling is measured by the following procedure:
A sample of the coated material is incubated at 57 ° C., 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 {(ba) / a} × 100
Calculated as (%). Another expression that says the same is that no more than 2 g of distilled or deionized water at 21 ° C. per gram of coated gelatin is absorbed within 3 minutes.

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.

Two or more types of tabular silver halide emulsions which are similarly prepared, but which may be prepared separately, are used to form photographic emulsions for use in photographic materials according to the present invention. Can be mixed.

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 example, said photographic material is a single-sided or double-sided coated X-ray material.

The single-coated X-ray material may comprise a single emulsion layer (which applies for many applications), or it may be made up of 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 double coated materials 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-type silver halide emulsion adjacent to each other, the emulsion layers closer to said support being prepared according to the method as 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 the image tone that may be used are given, for example, in EP-A 0 789 266, in which dyes are formed by reaction with an oxidized developer close to the developed particles. Leuco dyes have been described. Leuco dyes have already been described for this purpose in US-A 4,865,958.

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, for example, a hardening layer. 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 include, 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 as used in radiographic applications, 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 green light emitting phosphor screen, MAKRO
LEX ORANGEG or GG, (BAYER AG
Certain dyes (e.g. trademark products) may be used.

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. Organic resin supports, for example, cellulose nitrate film, cellulose acetate film, poly (vinyl acetal) film, polystyrene film, poly (ethylene terephthalate) or poly (ethylene naphthalate) film, polycarbonate film, polyvinyl chloride film, or poly-vinyl chloride Alpha-olefin films (eg, 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 review of useful supports is RD3895
7, 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, reductic acid or derivatives thereof can be partially or completely replaced by hydroquinone as a more ecological developing agent. Preferably, an automated processor is used provided with a system for automatic replenishment of the processing solution.

For X-ray applied materials, the hydrophilic layer may be pre-cured, for example, with a curing agent as described above, and may be one part depending on the processing application that determines the degree of curing required for the processing cycle. It may be processed using a packaged drug or a three-part packaged drug.
Applications within a generally known total processing time of 30 seconds 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 (comparative emulsion) 1450 ml of dispersion medium (C) containing 97.5 g of gelatin essentially free of calcium ions were fed into a stirred reaction vessel. The pCl was adjusted to a value of 2.0 with sodium chloride; the 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, 2.94 m
ol silver nitrate solution and 2.94 mol sodium chloride solution by double jet precipitation within 1 second of 57 seconds.
A simultaneous addition in a volume of 00 ml thus formed the nucleation step .

The above reaction vessel contains 1560 mg of potassium iodide and 450 mg of sodium chloride.
of the mixture and the temperature of the mixture is raised to 65 over the next 20 minutes.
° C.

After 5 minutes, the first growth step was started: for the next 7 minutes and 14 seconds, the silver nitrate solution was 10 ml with the silver chloride solution.
/ Min at a constant rate and the silver chloride solution was added at a variable addition rate to maintain a constant UAg of +178 mV against a silver / silver chloride reference electrode. During the next 11 minutes 53 seconds (at the end of which a temperature of 65 ° C. was reached), a further double-jet precipitation was carried out, but the addition rate of silver nitrate was reduced from 10 ml / min from 10 ml / min while maintaining the UAg at a constant potential of +184 mV . 1 at the end of one growth process
The primary increase was 5 ml / min.

After a physical ripening time of 20 minutes, a second growth step was started: the sodium nitrate solution was maintained at a constant potential of +159 mV while maintaining the UAg from 11 ml / min to 35 ml.
/ Min at a rate increasing linearly to 29 minutes and 45 seconds.

Preparation of Emulsion B (Comparative Emulsion) 1.175 g of copolymer TETRONIC 15 from the start of precipitation
Comparative Emulsion B was prepared according to the same manufacturing procedure as Comparative Emulsion A described above, except that 08.RTM.

Preparation of Emulsion C (Emulsion of the Invention) 1.175 g of copolymer TETRONIC after the first growth step
Emulsion C of the present invention was prepared according to the same manufacturing steps as Comparative Emulsion A described above, except that 1508 (registered trademark) was added.

The following emulsion crystal properties were determined from electron micrographs (replicas):% TAB: the percentage amount of the number of tabular grains (grains having an aspect ratio AR> 5) in the total grain population (= 100%). % _{Tt <0.25 μm} : percentage amount of the number of tabular grains having a thickness of less than _0.25 μm (total tabular grains = 10
% _{Tt> 0.25 μm} : Percentage amount of the number of tabular grains having a thickness of _0.25 μm or more (total tabular grains = 10
0%);-% VAR: Percentage variation in mean particle size measured based on electrochemical reduction at maximum sensitivity (trigger value 10 ^-7 ), taking into account smaller nuclei;-% NUCL: Percentage amount of reduced particles having an equivalent volume diameter of less than 0.03 μm (as measured by electrochemical reduction of said particles); for each tabular grain having a thickness of less than 0.25 μm Average aspect ratio A, defined as the average obtained after calculating the ratio between the equivalent circular diameter ECD and the thickness t
AR;-ECD: equivalent circular diameter calculated as the diameter of a circle having the same area as the projected surface area of the relevant tabular grain (Table 1)
% Is the average calculated from all tabular {100} grains );% CUB: the percentage of the number of cubic crystals present;% N (eedles): the number of needles present % S (ingle) T (wins): Percentage of the number of crystals having a single twin.

[0092]

[Table 1]

As can be calculated from the data summarized in Table 1, the silver chloride-rich # 10 having a thickness of less than 0.25 μm when the emulsion is prepared by the method of the present invention.
A clearly increased percentage amount of 0 ° tabular silver halide grains is present in the emulsion: the addition of the trademark product copolymer TETRONIC 1508 early in the process resulted in renucleation (as shown for Comparative Emulsion B). % NUCL and% VAR), which leads to the loss of tabular crystals at the point where many needles and single twins appear. Otherwise, the addition after the first growth step reduces the percentage of {100} tabular grains having a thickness greater than 0.25 μm by about 1/3 (33%) from about 34% to about 23%, 0.25μm
The ratio between thinner tabular grains and tabular grains having a thickness of 0.25 μm or more is changed from a value of less than 2: 1 to a value of 3: 1 or more. Please). However, the percentage amount of {100} tabular grains, cubic grains, single twins and needles present in the entire grain population of the emulsion remains unchanged (79%: 1).
5%: 5%: 1%).

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

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ann Vervik, Septograt 27, Mortzeal, Belgium Inside Agfa Gevaert Namloze Bennacht Chap (72) Inventor Frank Loue, Motzel, Septograt 27, Belgium Within Gevert Namrö Ze Bennot Chap

Claims (6)

[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 in a reaction vessel followed by desalting by flocculation and washing or by ultrafiltration. Wherein the emulsion contains at least 50 mol% of silver chloride {100}
Comprising tabular silver halide grains and a colloidally stabilizing binder, wherein at least 70% of the total number of grains is provided by said tabular grains, having an average aspect ratio of at least 5 and an average equivalent of at least 0.3 μm. Exhibiting a circular grain diameter, wherein said tabular grains have an average thickness of less than 0.25 μm for at least 75% of the total tabular grains, wherein said three separate precipitation steps comprise a nucleation step, a first and a second step. Two growing steps, wherein the method further comprises introducing a polyoxyalkylene block copolymer according to formula (I) into the reaction vessel after the first growing step, wherein the block copolymer is at least in addition to ethylenediamine units as tetravalent linking units. Contain three terminally hydrophilic polyoxyethylene groups and at most one terminally hydrophobic polyoxypropylene block unit. And a production method characterized by the following: 2. The method according to claim 1, wherein introducing the block copolymer into the reaction vessel is performed before the second growth step. 3. The method according to claim 1, wherein said binder is a compound selected from the group consisting of gelatin, a block copolymer corresponding to formula (I) and colloidal silica or a combination thereof. 4. A photosensitive silver halide photographic emulsion comprising {100} tabular silver halide grains containing at least 50 mol% silver chloride and a colloidally stabilizing binder, wherein the total number of grains is Is provided by tabular grains, exhibiting an average aspect ratio of at least 5 and an average equivalent circular grain diameter of at least 0.3 μm, wherein said tabular grains are at least 7% of the total tabular grain number.
4. A light-sensitive silver halide photographic emulsion having an average thickness of less than 0.25 [mu] m for 5%, wherein said emulsion is prepared according to the method of any of claims 1-3. 5. A photosensitive silver halide photographic emulsion comprising {100} tabular silver halide grains containing at least 50 mol% silver chloride and a colloidally stabilizing binder, wherein the total number of grains is Is provided by tabular grains, exhibiting an average aspect ratio of at least 5 and an average equivalent circular grain diameter of at least 0.3 μm, wherein said tabular grains are at least 7% of the total tabular grain number.
Having an average thickness of less than 0.25 μm for 5%, wherein the colloidally stabilizing binder comprises a polyoxyalkylene block copolymer according to formula (I), wherein the block copolymer is a tetravalent linking unit Photosensitive silver halide photographic emulsion containing at least three terminally hydrophilic polyoxyethylene groups and at most one terminally hydrophobic polyoxypropylene block unit in addition to ethylenediamine units: 6. A photographic material comprising a support and at least one light-sensitive silver halide emulsion layer on at least one side of said support, wherein said emulsion layer is one or more of claims 4 or 5. A photographic material containing a photosensitive silver halide photographic emulsion.