JPH08171163A - Radiation-sensitive emulsion and photographic element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a photographic development speed and reduce high illuminance reciprocity through introduction of dopant. SOLUTION: This emulsion contains a dispersion medium, silver halide grains containing the prescribed plate type grains and a spectral sensitization pigment. Furthermore, silver halide projected parts forming an epitaxial joint with the plate type grains are arranged so as to occupy a maximum of 50% of the surface area of the grains, and contain at least one type of ligand showing higher overall solubility than at least part of the grains forming an epitaxial joint with the projected parts, forming a face centered cubic lattice and having a higher electron attractive function than fluoride ions, as well as the 8th group of a bivalent dopant selected from Fe<+2> , Ru<+2> and Os<+2> .

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to silver halide photography. More particularly, this invention relates to improved spectrally sensitized silver halide emulsions and multilayer photographic elements containing one or more of these emulsions.

[0002]

The term "ECD" shall refer to the diameter of a circle having an area equal to the projected area of a silver halide grain. When showing silver halide grains and emulsions containing two or more kinds of halides, those halides shall be listed in the order of increasing concentration. The term "dopant" is meant to refer to all but the silver and halide ions contained within the silver halide grain crystal lattice structure.

In the present specification, the term "high illuminance reciprocity law failure"
(Sometimes referred to as HIRF), the exposure dose received is the same, but the response to short-time exposure is low when emulsion samples are compared by changing the exposure time in the range of 10 ^-5 to 10 ^-2 seconds. Point When the photographic reciprocity law is satisfied (that is, when there is no reciprocity law failure), the speed of the photographic emulsion is equal to the product I × ti of I and ti even if the values are different. In that case, they all have the same speed. Here, I is the exposure intensity and ti is the exposure time. By comparing the characteristic curves obtained by changing the exposure intensity and the exposure amount, the influence of HIRF on both speed and contrast can be observed.

The periodic table of the elements referred to in this specification is A
The format adopted by the Merchanic Chemical Society (Chemical
from and Engineering News 198
Issued on February 4, 5). Research
Disclosure is Kenneth Maso
nPublications (Dudley Hou
se, 12 NorthSt. , Emsworth
h, Hampshire P010 7DQ, UK)
Issued by.

US Pat. No. 4,439,520 (Kofron et al.) Ushered in the current high performance silver halide photography era. Kofron et al. Show chemical sensitization in which tabular grains having a diameter of at least 0.6 μm and a thickness of less than 0.3 μm exhibit an average aspect ratio higher than 8 and account for more than 50% of the total grain projected area; Disclosed and demonstrated remarkable photographic advantages for spectrally sensitized tabular grain emulsions. Of the numerous emulsions shown, one or more of these numerical parameters often far exceeded the above requirements. Kofron et al.
It has been recognized that the chemically and spectrally sensitized emulsions disclosed in one or more of the various embodiments will be useful in color photography and black and white photography (including indirect radiography). Not only orthochromatic and panchromatic spectral sensitizations for black and white imaging applications were attempted, but also spectral sensitizations in all parts of the visible spectrum and at longer wavelengths. Kofron
Et al. Used a combination of one or more spectral sensitizing dyes with middle chalcogen (eg, sulfur) and / or noble metal (eg, gold) chemical sensitization. However, Kof
Ron et al. also disclose other conventional sensitization methods such as reduction sensitization.

An early cross-reference modification to the teachings of Kofron et al. Was described in US Pat. No. 4,435,501 (Maskasky) (hereinafter "Maskasky-
I "). Maskasky-
I is a site director such as iodide ion, aminoazaindene, or a selected spectral sensitizing dye adsorbed on the surface of host tabular grains,
It has been recognized that silver halide epitaxy can be directed to selected sites on the host grain, typically edges and / or corners. A marked increase in speed was observed depending on the composition and site of silver salt epitaxy.
The modifying compounds are taught to be optionally incorporated into either the host tabular grains or halide salt epitaxy.

In 1982, the first indirect radiographic and color photographic films incorporating the teachings of Kofron et al. Were introduced commercially. Twelve years later it is clearly understood that different tabular grain emulsions are preferred depending on the type of product considered. Indirect radiography has been found to be unattractive because ultrathin tabular grain emulsions produce a silver image with an unfavorable warm (ie, brownish black) image tone. In camera speed color photographic films, ultrathin tabular grain emulsions are usually attractive, especially when spectrally sensitized to wavelength regions where the intrinsic grain sensitivity is low, eg wavelengths above about 430 nm. It turned out to be It is theoretically possible for ultrathin tabular grains containing one or more spectral sensitizing dyes having an absorption peak below 430 nm to exhibit comparable performance. However, it is common in the art to increase sensitivity by relying on the intrinsic blue sensitivity of camera speed emulsions, which slows the transition to ultrathin tabular grain emulsions for blue exposure recording. It was The reduction in grain volume caused by reducing the thickness of tabular grains is inconsistent with the use of intrinsic blue sensitivity, which gives a significantly greater increase in blue sensitivity than achieved by using blue absorption spectral sensitizing dyes. . Therefore, the selection of thicker tabular or non-tabular grains is common for camera speed film blue recording emulsion layers.

Recently, US Pat. No. 5,250,403 (Antoniades et al.), In many respects, prior to the present invention, color photographic elements, particularly the minus blue (red and / or green) portion of the spectrum. Disclosed are tabular grain emulsions representative of the best available emulsions for recording exposures at. Antoniades, etc.
1} Tabular grains having a major surface account for 97% of the total grain projected area
Tabular grain emulsions having a proportion of more than 100% are disclosed. These tabular grains have an average equivalent circular diameter (ECD) of at least 0.7 μm and an average thickness of less than 0.07 μm. Tabular grain emulsions having an average thickness of less than 0.07 µm are referred to below as "ultrathin" tabular grain emulsions. Ultrathin tabular grain emulsions have been found to have efficient silver utilization, attractive sensitivity-granularity relationships, and high image sharpness levels in both the emulsion and lower emulsion layers. Suitable for use in color photographic elements, especially minus blue recording emulsion layers.

Research by Buhr et al.
Disclosure, Volume 253, Item 2533
0, 0.18, as taught in May 1985.
The features that distinguish ultrathin tabular grain emulsions from other tabular grain emulsions, as recognized as tabular grain characteristics having thicknesses in the range of .about.0.08 .mu.m, are within the visible spectrum. It does not show maximum reflection. Research
h Disclosure is P0, Hampshire, UK
10 7DQ Emsworth 12 North Street
Kenneth Maso in Dudley Annex
Published by n Publications, Inc. Multilayer photographic elements have an average tabular grain thickness of 0.18
The upper emulsion layer, which is in the range of .about.0.08 .mu.m, has different reflection characteristics in the visible spectrum, and thus needs to be selected carefully. The choice of ultrathin tabular grain emulsions for the construction of multilayer photographic elements eliminates the need to choose different average grain thicknesses depending on the spectral reflectance in the various emulsion layers overlying the other emulsion layers. Therefore, the use of ultrathin tabular grain emulsions not only improves photographic performance, but also has the advantage of simplifying the construction of multilayer photographic elements. As another method, Antoniades et al. Considered introducing an ionic dopant into ultrathin tabular grains. About this, Research Disclosure (3rd
08, December 1989, Item 308119, Section I, paragraph D).

Kuno US Pat. No. 5,051,344
The specification describes 0.1 to 4 mol% iodide and 5 × 10 ⁻⁹ to 1 × 10 ⁻⁶ as a grain dopant per mol of silver.
Disclosed are silver iodobromide emulsions containing moles of iridium compounds and 5 × 10 ⁻⁹ to 1 × 10 ⁻⁶ moles of iron compounds. The grains have a core-shell structure in which the iodide content of the core is higher than that of the shell (at least 3 mol%). Kuno particularly favors the presence of both iridium and iron in the shell.
The purpose is high contrast by high-intensity short-time exposure,
To achieve rapid processing and good safe light operation.
This last requirement, good safe light operation, is a requirement to increase low light reciprocity failure. That is, the emulsion should be responsive to high intensity short exposures but relatively unresponsive to low brightness levels due to safe light. Kuno admits that iridium reduces both high and low intensity reciprocity failure. The purpose of adding Kuno's iron is to eliminate the effect of iridium which reduces low-light reciprocity failure.

[0011]

SUMMARY OF THE INVENTION Many of the advantages of common tabular grain emulsions and certain improvements with ultrathin tabular grain emulsions and color photographic elements, including the improvements disclosed by Antoniades et al. Nevertheless,
For the construction of photographic elements containing these emulsions as well as performance enhancements in ultrathin tabular grain emulsions heretofore unavailable in the art and for the highest performance emulsions and photographic elements achievable for color photography. There remains an unmet need for alternatives.

Further, there is a need in the art for ultra-thin tabular grain emulsions that are "robust". The term "robust" is used herein to indicate that the emulsion remains close to its intended (ie, as expected) photographic properties in spite of unintended manufacturing variations. Photographic emulsions that appear to be attractive in terms of photographic properties when manufactured under laboratory conditions can result in large amounts of emulsions that deviate from their desired properties to the extent that market requirements are not met by unintentional small variations in the manufacturing procedure. Not rare. There is a need in the art for high performance tabular grain emulsions that exhibit a high level of robustness or desired inertia and that vary substantially from the desired photographic properties from one manufacturing run to the next.

In an attempt to modify the performance of ultrathin tabular grain emulsions by introducing dopants to improve photographic speed and reduce high intensity reciprocity law failure (HIRF), dopants that provide shallower electron capture sites are selected. It has been found that the HIRF reduction due to the inclusion of iridium as a dopant is largely, if not completely, lost when introduced to enhance photographic speed. Therefore, as a new problem to be solved, it is necessary to achieve both high speed and low HIRF in an ultrathin tabular grain emulsion.

[0014]

According to one aspect, the present invention provides (1) a dispersion medium, (2) (a) a {111} major surface, and (b) a bromide to silver. Content of more than 70 mol%, (c) account for more than 90% of the total grain projected area, (d) the average equivalent circular diameter is at least 0.7 μm, and (e) the average thickness is 0. Less than 07 μm,
(F) contains an iridium dopant capable of reducing reciprocity law failure over an exposure range of 1 × 10 ^-2 to 1 × 10 ^-5 seconds, and (g) has a latent image-forming chemically sensitized site on the surface. A silver halide grain containing a tabular grain having
(3) An improved radiation-sensitive emulsion containing a spectral sensitizing dye adsorbed on the surface of the tabular grain, wherein the surface chemical sensitized site forms an epitaxial junction with the tabular grain. Including a silver halide protrusion, wherein the protrusion is
(A) is arranged so as to occupy at most 50% of the surface area of the tabular grain, and (b) exhibits a higher overall solubility than a portion of the tabular grain forming an epitaxial junction with at least the protrusion, (C) at least one ligand forming a face-centered cubic crystal lattice, and (d) having a higher electron-withdrawing property than fluoride ion, and Fe ⁺² , Ru ⁺² and O
A radiation-sensitive emulsion is provided which comprises a divalent Group 8 dopant selected from s ⁺² .

According to another aspect, the invention comprises: (i) a support, (ii) coated on said support, 500-700.
for exposing a first silver halide emulsion layer sensitized so as to produce photographic recording when exposed to specular light in the minus blue visible wavelength region of (nm), and (iii) for exposing the first silver halide emulsion layer. A second silver halide emulsion layer capable of producing a second photographic record coated on the first silver halide emulsion layer, which receives specular minus blue light, the first halogenated in the form of specular light. A second photographic element comprising a second silver halide emulsion layer capable of acting as a transmission medium for delivery of at least a portion of negative blue light for exposing a silver emulsion. It relates to a photographic element characterized in that the emulsion layer comprises an improved emulsion according to the invention.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The improved ultrathin tabular grain emulsions of the present invention utilize a combination of iridium dopant in ultrathin tabular grains and dopant-modified silver halide epitaxy in chemical sensitization to produce ultrathin tabular grains. It is the first to provide the benefits that can be realized with a grain-shaped emulsion and to increase photographic speed and reduce the high intensity reciprocity failure exhibited by such emulsions. The present invention (1) overcomes the stigma in the art for applying silver halide epitaxial sensitization to ultrathin tabular grain emulsions, and (2) only sensitized with conventional sulfur and gold. Recognition of improved performance over ultrathin tabular grain emulsions,
(3) An unexpectedly greater improvement in sensitivity was observed for similar sensitization of thicker tabular grains, and (4) locating the dopant in silver halide epitaxy rather than in tabular grains. It was realized by avoiding the thickening of ultra-thin particles.

The teaching of Antoniades et al. Does not explain or suggest the suitability of the disclosed ultrathin tabular grain emulsions for silver halide epitaxial sensitization. An
Toniades et al., of course, was aware of the teachings of Maskasky-I, but it is correct that Maskasky-I did not provide a clear teaching or example of applying silver halide epitaxial sensitization to ultrathin tabular grain emulsions. I recognized. Antomiade because there is no original consideration to rely on and no clear teaching of applying silver halide sensitization to ultrathin tabular grain emulsions.
S. et al. did not like to estimate the possibility of applying such sensitization to ultrathin tabular grain emulsions.
The surface: volume ratio of ultrathin tabular grains is Maskasky-I.
Much larger than that used by itself was sufficient to raise great doubt as to whether the ultrathin structure of the tabular grains could be maintained during silver halide epitaxial deposition. Furthermore, it seemed intuitively that adding silver halide epitaxy to the ultrathin tabular grain emulsions would not improve image sharpness in the emulsion layers themselves or in the lower emulsion layers.

Antoniades et al. Avoided silver halide epitaxial sensitization, but Antoniade
S. et al. taught doping ultrathin tabular grains according to conventional practice. Antoniades et al. Did not recognize that dopants can cause thickening of tabular grains. Furthermore, we clearly avoid any teachings about silver halide epitaxial sensitization.
Toniades et al. do not admit at all about other doping methods other than locating the dopant in the ultrathin tabular grains.

Not only was chemical sensitization involving silver halide epitaxy compatible with ultrathin host tabular grains, it was found that the resulting emulsions showed quite unexpected improvements in degree and type. The increase in sensitivity imparted to ultrathin tabular grain emulsions by silver halide epitaxy is
Maskasky-using thicker tabular host grains
It was found to be larger than expected based on I's consideration. Furthermore, by properly placing the dopants within the ultrathin tabular grains and silver halide epitaxy,
It was found that both the improvement of photographic speed and the reduction of reciprocity law failure in high illuminance can be realized.

At the same time, the expected unacceptable reduction in image sharpness investigated with respect to specularity measurements is straightforward, even when the amount of silver salt epitaxy is increased well above the preferred maximum level taught by Maskasky-I. It didn't happen.

Yet another advantage resides in reduced unwanted wavelength absorption as compared to similarly sensitized relatively thick tabular grain emulsions. A higher percentage of the total light absorption was confined to the spectral region where the spectral sensitizing dye (s) had an absorption maximum. For the minus blue sensitized ultrathin tabular grain emulsion, the intrinsic blue absorption was also reduced. Finally, the emulsions investigated showed unexpected robustness. When the level of the spectral sensitizing dye is changed so that it can occur during the manufacturing process, the silver salt epitaxially sensitized ultrathin tabular grain emulsion of the present invention produces a comparable ultrathin film using only sulfur sensitization or gold sensitization. It was shown to have less variation in sensitivity than tabular grain emulsions.

The present invention relates to improvements in spectrally sensitized photographic emulsions. This emulsion is specifically intended for incorporation into camera speed color photographic film. The emulsion of the present invention is
The tabular grains have (a) {111} major faces, (b) contain more than 70 mol% of bromide with respect to silver, and (c) account for more than 90% of the total grain projected area, (D) exhibits an average ECD of at least 0.7 μm, and (e)
It can also be accomplished by chemically and spectrally sensitizing any conventional ultrathin tabular grain emulsion exhibiting an average thickness of less than 0.07 μm.

Criteria (a)-(e) are too strict to be satisfied by the majority of known tabular grain emulsions, but a few published precipitation methods produce emulsions meeting these criteria. be able to. Antonia mentioned above
des et al. show preferred silver iodobromide emulsions that meet these criteria. European Patent Application Publication No. 0
362699A3 (Zola and Bryan
t) also discloses silver iodobromide emulsions satisfying these criteria. When describing grains and emulsions containing multiple halides, the halides are listed in order of increasing concentration.

For camera speed films, the tabular grains should contain at least 0.25 mol% iodide, based on silver.
It is generally preferred to include (preferably at least 1.0 mol%). Iodide saturation levels in the silver bromide crystal lattice are generally described as about 40 mole%, a limit commonly stated for iodide formulations.
For photographic applications, iodide concentrations rarely exceed 20 mole percent and are typically in the range of about 1-12 mole percent. As is generally well understood in the art, Antoniodias et al. And Zola and Bryan produce silver iodobromide tabular grain emulsions.
It is possible to produce silver bromide tabular grain emulsions of equivalent or thinner average grain thickness by modifying precipitation methods, including those described in t., by simply omitting the addition of iodide. This is specifically disclosed by Kofron et al.

It is possible to include small amounts of chloride ions in the ultrathin tabular grains. US Pat. No. 5,372,927
0.4-20 mol% chloride and 10 iodide, based on total silver, as disclosed in Delton.
Ultrathin tabular grain emulsions containing up to mol% and the balance of the halide being bromide are described in US Pat. No. 5,061,60
No. 9 and No. 5,061,616 (Pig
Gin et al.) curves A and B corresponding to the grain growth which accounts for 5 to 90% of the total silver within the pAg-temperature (° C) boundary of curve A (preferably within the boundary of curve B) as shown by Delton. It can be prepared by carrying out. Under these precipitation conditions, the presence of chloride ions actually serves to reduce the thickness of the tabular grains. Although chloride ions (when present) are preferred to use precipitation conditions that can help reduce tabular grain thickness, chloride ions are compatible with retention of tabular grain average thickness of less than 0.07 μm. It will be appreciated that to the extent it can be added during conventional ultrathin tabular grain precipitation.

For reasons explained below in connection with silver halide epitaxy, at least 9 of the total grain projected area is
Ultrathin tabular grains accounting for 0% contain at least 70 mol% bromide with respect to silver. These ultrathin tabular grains include silver bromide salt, silver iodobromide, silver chlorobromide, silver iodochlorobromide and silver chloroiodobromide grains. When the ultrathin tabular grains contain iodide, the iodide is evenly distributed within the tabular grains. To further improve the speed-granularity relationship, it is preferred that the iodide distribution satisfy the teachings of US Pat. No. 4,433,048 (Solberg et al.). In this specification, the description is incorporated by reference. Applying the iodide profile of Solberg et al. To ultrathin tabular grain emulsions is a particular subject of Daubendiek et al.-II, cited above. All references to ultrathin tabular grain compositions exclude silver salt epitaxy.

Antoniades et al., Zola and Br
The ultrathin tabular grains produced by the teachings of yant and Delton all have {111} major faces. Such tabular grains typically have triangular or hexagonal main faces. The tabular structure of these grains is due to the inclusion of parallel twin planes.

The tabular grains of the emulsion of the present invention account for more than 90% of the total grain projected area. Ultrathin tabular grain emulsions, in which tabular grains account for greater than 97% of total grain projected area, are preferred and can be prepared by the preparation method taught by Antoniades et al. Antoniade
S. et al. report an emulsion in which substantially all (eg, up to 99.8%) of the total grain projected area is accounted for by tabular grains. Similarly, Delton is "substantially all" of the grains that precipitate when forming ultrathin tabular grain emulsions.
Was reported to be flat. It is important to provide emulsions in which tabular grains account for a high percentage of total grain projected area, especially to achieve the maximum achievable image sharpness level in multilayer color photographic films. It is also important to utilize silver efficiently and achieve the most desirable speed-granularity relationship.

Tabular grains accounting for greater than 90% of total grain projected area have an average ECD of at least 0.7 μm.
Indicates. The benefits realized by keeping the average ECD at least 0.7 μm are shown in Tables III and IV of Antoniades et al. Emulsions with very large average grain ECD's are sometimes prepared for scientific grain studies, but for photographic applications the ECD's are typically 10μ.
m, and in most cases less than 5 μm. The optimum ECD range for medium to high image quality is 1 to 4
It is in the range of μm.

In the ultrathin tabular grain emulsion of the present invention, tabular grains accounting for more than 90% of the total grain projected area have an average thickness of less than 0.07 μm. At an average grain thickness of 0.07 μm, there is almost no reflectance variation between the green and red regions of the spectrum. Further, the difference between the minus blue reflectance and the blue reflectance is not significant compared to tabular grain emulsions having average grain thicknesses in the 0.08 to 0.20 μm range. The film composition is that the green and red recording emulsions (and to a lesser extent blue recording emulsions) can be constructed using the same or similar tabular grain emulsions by decoupling the magnitude of the reflectance from the exposure wavelength in the visible region. It is simplified. If the average thickness of the tabular grains is further reduced below 0.07 μm, the average reflectance observed in the visible spectrum is also reduced. Therefore, it is preferred to maintain the average grain thickness below 0.05 μm. In general, the minimum average tabular grain thickness conveniently achieved by the precipitation method employed is preferred. Thus, the average tabular grain thickness is about 0.03 to 0.05 μm.
Ultrathin tabular grain emulsions in the m range are readily realized. U.S. Pat. No. 4,672,027 (Daub
etc.) is 0.017 μm in average tabular grain thickness.
reporting m. Utilizing the grain growth method taught by Antoniades et al., These emulsions have an average ECD of at least 0. It can grow up to 7 μm. The minimum tabular grain thickness is limited by the spacing of the first two parallel twin planes formed in the grain during precipitation. 0.002 μm (ie 2 nm
Alternatively, a small minimum twin plane spacing of 20 angstroms) was observed in the emulsion of Antoniades et al., But Kofron et al.
It suggests 01 μm.

When the average tabular grain thickness of the tabular grain emulsion is less than 0.04 μm, the ratio of photographic speed (speed) to background radiation is increased.
This relationship has been found to be superior to that achieved when tabular grains are thicker than 0.04 μm. The relatively low sensitivity of these tabular grain emulsions to background radiation is that photographic elements with longer shelf life compared to photographic elements of the same speed using tabular grain emulsions containing thicker tabular grains. I will provide a.

The preferred ultrathin tabular grain emulsions are those in which the differences between the grains are maintained at low levels. Antoni
ades et al. reported ultrathin tabular grain emulsions in which more than 90% of the tabular grains had hexagonal major faces. Antoniades also reported ultrathin tabular grain emulsions with a coefficient of variation (COV) for ECD of less than 25%, and even less than 20%.

Both the photographic speed and the granularity are the average grain E.
It is recognized that it increases with increasing CD. From a comparison of sensitivity and granularity of optimally sensitized emulsions with different grain ECDs, it is known in the art that the speed is doubled (ie 0.3 log E in speed, where E is the exposure dose (lux-sec). The same speed for each increase-
It has been demonstrated that the granularity of emulsions exhibiting a granularity relationship increases by 7 granularity units. It was observed that the presence of even smaller proportions of the larger ECD grains in the ultrathin tabular grain emulsions of this invention significantly increased the granularity of the emulsion.
Antoniades et al. Have a low C because the tabular grains ECD that exist are always close to the average value when COV is limited.
The OV emulsion was preferred.

In accordance with the present invention, COV is not the best technique for determining emulsion granularity. The need for low emulsion COV values limits both grain populations larger and smaller than the average grain ECD, whereas only the former grain population provides high levels of granularity. Total C
The OV measurements depend on the assumption that the particle size-frequency distribution is a normal error function distribution that is intrinsic to the precipitation method and is not easily controllable, regardless of whether the variance is wide or narrow. That is. Modified the ultrathin tabular grain precipitation method taught by Antoniades et al.
It is specifically contemplated to selectively reduce the size-frequency distribution of ultrathin tabular grains exhibiting an ECD greater than D. Since the size-frequency distribution of particles with ECD less than the mean value does not decrease correspondingly, the total COV value does not appreciably decrease. However, the benefits of reducing emulsion granularity were clearly demonstrated.

The reduction of the disproportionated size range in the particle size-frequency distribution of ultrathin tabular grains (hereinafter referred to as "> average ECD grains") larger than the average ECD can be achieved by the following method. It has been found that this can be achieved by modifying the precipitation method of: that is, nucleation of ultrathin tabular grains is carried out with gelatinous peptizers which have not been treated to reduce the natural methionine content, while the gelatine present. Grain growth is carried out after substantially removing the methionine component of the peptizer and the gelatino peptizer introduced later. A convenient way to achieve this is to interrupt the precipitation after nucleation and before the growth progresses sufficiently to introduce the methionine oxidant.

Any of the conventional techniques for oxidizing the gelatino-peptizer methionine can be used.
U.S. Pat. No. 4,713,320 (Maskasky)
(Hereinafter, referred to as "Maskasky-II"), the amount of methionine obtained by oxidation is 30 per gram of gelatin.
It teaches to reduce to less than 12 μmol, preferably less than 12 μmol by using strong oxidizing agents.
In fact, the oxidant treatment used by Maskasky-II reduces methionine to below the detection limit. Agents used to oxidize methionine in gelatinous peptizers include, for example, NaOCl, chloramine, potassium monopersulfate, hydrogen peroxide and peroxide releasing compounds, and ozone. U.S. Pat. No. 4,942,12
No. 0 (King et al.) Teaches the oxidation of the methionine component of gelatinous peptizers with alkylating agents. European Patent Application No. 0434012 (Takada et al.) Discloses the precipitation in the presence of a thiosulfonate represented by one of the following _{formulas: (I) R-SO 2} S-M ( II) in ^{_{R-SO 2 S-R 1}} (III) R-SO 2 S-Lm-SSO 2 -R 2 ( wherein, R, R ¹ and R ² are identical or different, aliphatic group, aromatic group or A heterocyclic group, M is a cation, L is a divalent linking group, and m is 0 or 1, provided that R, R ¹ , R ² and L are joined to form a ring. To). Gelatinous peptizers include gelatin,
For example, alkali-treated gelatin (livestock, bone or hide gelatin) or acid-treated gelatin (pigskin gelatin) and gelatin derivatives such as acetylated or phthalated gelatin.

The tabular grains of the emulsions of this invention include iridium dopants which can reduce high intensity reciprocity law failure (HIRF). Specific examples of iridium dopants used to reduce high intensity reciprocity failure include US Pat. No. 3,901,711 to Iwaosa et al. And US Pat. No. 4,8 to Grzeskowiak et al.
28,962, Kuno, U.S. Pat. No. 5,05.
1,344 and Yoshida et al., U.S. Pat. No. 5,229,263. A more general investigation of iridium dopants used to reduce reciprocity failure and other objectives are described in B. H. C
Iridium Sensitization of Arroll: Review of Literature "Photo
graphical Science and Engi
“Neering” (Vol. 24, No. 6, 1980 11)
/ Dec, p. 265-267). A more general investigation on dopants, including iridium dopants to reduce reciprocity failure, is described in Rese.
arch Disclosure (Volume 365, 199)
September 4th, Item 36544, Section I. Emulsion grains and their preparation, D.I. Particle denaturing conditions and control are described in subparagraphs (3) and (4). Any conventional iridium dopant known to reduce high intensity reciprocity failure can be used in any amount known to be useful for this purpose in the practice of the invention. .

In a particularly preferred embodiment, the iridium dopant is incorporated into the crystal lattice structure of the particles in the form of a hexacoordination complex which satisfies the formula: (IV) [Ir ⁺³ X ₅ L '] ^{m wherein} X is a halide ligand, L'is a bridging ligand, and m is -2 or -3.

When iridium is added during the precipitation process, the hexacoordination complex is accompanied by a suitable counterion such as ammonium or alkali metal, but within the crystal lattice structure of formula I
Only the anion portion of V is actually introduced. In addition, the iridium at the time of introduction can be in a +4 valent state, as exemplified by Leubner et al., US Pat. No. 4,902,611. However,
When +4 valent iridium is incorporated, it returns to the +3 valent state. Chloride and bromide are the preferred halide ligands. The bridging ligand L'can also be a halide ligand, but as an alternative, McDugle et al., U.S. Pat. Nos. 4,933,272, 4,981,7.
81 and 5,037,732, Marc.
US Pat. No. 4,937,180 to Hetti et al., US Pat. No. 5,037,732 to Keevert et al.
No. 5,360,71 to Olm et al.
It can take any convenient conventional form, including the various individual ligand forms described in No. 2.

The iridium dopant is at least 20% (most preferably 60%) of the silver forming the tabular grains.
Is preferably introduced after 90% (most preferably 80%) of the silver forming the tabular grains has been precipitated. If the iridium addition time in the precipitation step is earlier than the above, it should be avoided because it complicates the nucleation of ultrathin tabular grains, and to ensure that iridium is completely incorporated inside the ultrathin tabular grains. The delay of iridium addition in the precipitation process should be avoided.

The preferred concentration of iridium dopant is
Up to about 300 (most preferably 250) mol parts / 1
It can range up to, 000,000,000,000 parts (mppb). 1. Minimum effective concentration of iridium
8 mppb has been reported, but usually about 15 mppb
It is convenient to use the above concentration.

The chemical sensitization and spectral sensitization of the present invention are performed by Mas
It improves the best chemical sensitization and spectral sensitization described in kasky-I. In practicing the present invention, the ultrathin tabular grains undergo epitaxial sensitized silver halide during chemical sensitization which form protrusions at specific sites on the surface of the ultrathin tabular grains. This protrusion has a higher overall solubility than silver halide forming at least a portion of the ultrathin tabular grain that functions as an epitaxial attachment host site, that is, a portion that forms an epitaxial junction with the attached silver halide. Show. By "higher overall solubility" is meant that the mole fraction weighted average solubility of the silver halide forming the protrusions must be higher than the average solubility of the silver halide forming the host portion of the tabular grains. means. Ag in the temperature range 0 to 100 ° C
The solubility products of Cl, AgBr and AgI in water are Mee.
s "The Theory of the Photo"
”Graphic Process” (3rd edition, Mac
6th of Millan, New York (1966))
Page, Table 1.4. For example, at a general emulsion preparation temperature of 40 ° C., the solubility product of AgCl is 6.
22 * 10 < ^-10 >, AgBr is 2.44 * 10 < ^-12 > and AgI is 6.95 * 10 < ^-16 >. Due to the large difference in solubility of silver halide, it is important that the epitaxially deposited silver halide, in the vast majority of cases, exhibit a lower iodide concentration than the host tabular grain undergoing epitaxial deposition. It's obvious. The requirement that the epitaxially deposited protrusions have a higher overall solubility than at least the portion of the ultrathin tabular grain to which the protrusion attaches reduces the displacement of halide ions from the ultrathin tabular grains. Therefore, collapse of the ultrathin shape of tabular grains is avoided.

It was observed that Maskasky-I had the highest photographic sensitivity when a double jet injection of silver ions and chloride ions was carried out at the time of epitaxially adhering to a specific site of tabular grains of silver iodobromide. In any practice of the invention, the silver halide protrusions are in any case 10% or more, preferably 15% or more, most preferably 2% of the host ultrathin tabular grains.
Precipitation may be considered so as to show a chloride concentration higher than 0%. More precisely, it should be the chloride concentration in the silver halide protrusions relative to the chloride ion concentration in the portion forming the epitaxial junction of the ultrathin tabular grains. Concentration is substantially uniform (ie at average level)
Or, it is not always necessary because it is considered to be slightly lowered due to the replacement of iodide in the epitaxial junction region.

In contrast to the Maskasky-I teachings, the addition of iodide ions along with silver and chloride ions to ultrathin tabular grain emulsions at the same time as epitaxial deposition improves photographic speed and contrast. It was recognized that This exceeds the low level (substantially less than 1 mol%) of iodide transferred from the silver iodobromide host tabular grains during the silver and chloride ion addition step, and the iodide concentration in the epitaxial protrusions is increased. Will be raised. Increasing the iodide concentration in the face-centered cubic lattice structure of the epitaxial protrusions improves photographic performance, but the iodide concentration in the silver halide protrusions is at least 1.0 mol% relative to silver, preferably at least 1. It is preferred to increase to 5 mol%. The addition of bromide ions together with chloride and iodide ions increases the amount of iodide that can be contained in silver halide epitaxy, while at the same time, surprisingly, increasing the amount of bromide increases the content of iodide. Does not subtract the increase in photographic speed and contrast. The generally accepted solubilities of silver iodide in silver bromide and silver chloride are 40 mol% and 13 mol%, respectively, with respect to the total amount of silver, and the mixture of silver bromide and silver chloride is Br: C.
It contains an intermediate amount of silver iodide, depending on the molar ratio of l. It is preferred to keep the silver iodide in epitaxy below 10 mol% relative to the total amount of silver in epitaxy. Furthermore, it is preferable to maintain the overall solubility of silver halide epitaxy higher than the overall solubility of the portion that serves as the attachment site for the epitaxial attachment of the ultrathin tabular grains. The total solubility of mixed silver halides is the molar fraction weighted average of the solubilities of the individual silver halides.

The silver halide epitaxy includes (1) a large difference in chloride concentration between the host ultrathin tabular grains and the epitaxially deposited protrusions, and (2) a face-centered cubic crystal lattice of the protrusions. It is believed that the highest levels of photographic performance are achieved when the iodide content of the structure is high.

By subjecting the composition modifications specifically described above, the preferred techniques of chemical and spectral sensitization can be the same as those described above in Maskasky-I. Maskasky-I reports an improvement in sensitization by epitaxially depositing silver halide at specific sites on the surface of host tabular grains. Maskasky-I attributed the observed speed increase to limiting epitaxy deposition of silver halide to a region of small host tabular grain surface area. Ma
As taught by skasky-I, it is believed that silver halide epitaxy is preferably further limited to less than 50% of the ultrathin tabular grain surface area. Above all, M
askasky-I is a silver halide epitaxy of less than 25%, preferably less than 10% of the host grain surface area,
It teaches optimally limiting to less than 5%. So
As taught by Lberg et al., silver halide epitaxy is typically employed when the ultrathin tabular grains comprise a central region of low iodide concentration and regions flanked by high iodide concentrations. Is preferably limited to the portion of the ultrathin tabular grains formed by the regions arranged on the sides including the edges and corners of the tabular grains.

When the iodide concentration varies depending on the portion of the tabular grains, the average of the host ultrathin tabular grains as a whole is within the range in which the iodide concentration in the epitaxial protrusions does not damage the ultrathin tabular grain structure. It may be higher than the concentration, provided that the iodide concentration in the portion of the tabular grain providing the attachment site for the epitaxial protrusion is higher than the iodide concentration in the epitaxial protrusion.

As in Maskasky-I, the practice of the invention is to use a nominal amount of silver halide epitaxy [0.
About 05 mol%] is effective. By increasing the coverage of the surface portion of the host tabular grain by silver halide epitaxy and decreasing the amount of silver in the ultrathin tabular grain described above, the proportion of total silver present in silver halide epitaxy can be further increased. . However, it is preferred to limit silver halide epitaxy to 50% of total silver unless there is a definite advantage obtained by increasing the proportion of silver halide epitaxy. Generally, 0.3-25
A silver halide epitaxy concentration of mol% is preferred and a concentration of about 0.5 to 15 mol% is generally optimal for sensitization.

Maskasky-I teaches a variety of techniques for limiting the surface coverage of host tabular grains by silver halide epitaxy that can be applied in forming the emulsions of this invention. Maskasky-I teaches the use of spectral sensitizing dyes in aggregated form adsorbed onto tabular grain surfaces which can direct silver halide epitaxy towards the edges or corners of the tabular grains. J
Cyanine dyes that are adsorbed to the surface of host ultrathin tabular grains in aggregated form constitute a particularly preferred type of site director. Maskasky-I also teaches using non-dye adsorption site directors such as aminoazaindenes (eg, adenine) to direct epitaxy to the edges or corners of tabular grains. In yet another embodiment, Maskasky-I directs epitaxy to the edges or corners of the tabular grains with a total iodide content in the host tabular grains of at least 8 mole percent.
In yet another aspect, Maskasky-I adsorbs small amounts of iodide to the surface of host tabular grains to direct epitaxy to the edges and / or corners of the grains.
The site-directed techniques described above are mutually compatible and are used in combination in a particularly preferred embodiment of the invention. For example, iodide in the host grains, even if alone does not reach the level of 8 mol% that can direct the epitaxy to the edges or corners of the host tabular grains, in adsorbed surface site director (in the position of epitaxy ( It can work effectively with one or more (eg, spectral sensitizing dyes and / or adsorbed iodides).

Selective site attachment of silver halide epitaxy to host tabular grains reduces sensitized site competition for conduction band electrons released by photon absorption in imagewise exposure, thus improving sensitivity. Generally accepted. That is, epitaxy to a limited portion of the major surface of the ultrathin tabular grain is more efficient than epitaxy covering all or most of the major surface, and more preferably the edge of the host ultrathin tabular grain. Substantially limited to,
And it is an epitaxy in which the amount of coating on the main surface is limited,
Even more efficient is epitaxy limited to or near the corners of the tabular grains or to discrete sites. The spacing of the corners of the principal plane of the host ultrathin tabular grains themselves reduces photoelectron competition sufficiently to achieve near maximum sensitivity. Maskasky-I can reduce the number of epitaxial attachment sites on host tabular grains by slowing the epitaxial attachment rate. US Pat. No. 5,011,767 (Yama
(Shita et al.) further advances this and suggests conditions for forming one epitaxy junction per host particle with a specific spectral sensitizing dye. As taught by Solberg et al., When the host ultrathin tabular grains contain a higher concentration of iodide in the region located on the side, the silver halide protrusions are placed on the side of higher iodide concentration. An improvement in photographic performance is observed by confining it to the area located in the area.

A special recognition of the present invention is that an improvement in photographic performance, consistent with the advantages described above, can be realized by incorporating in the silver halide epitaxy a dopant capable of providing a shallow electron trapping site. is there. This means that divalent Group 8 metals (ie Fe ⁺² , Ru ⁺² or Os ⁺² ) can be deposited within the specified concentration levels and tabular grain positioning with respect to the tabular grain surface and iridium dopant. A speed-increasing Group 8 dopant including
It is preferably achieved by using at least one ligand which is more electron withdrawing than the fluoride ion. The speed-enhancing Group 8 dopant can be introduced as a hexacoordination complex that satisfies the formula: (V) [ML ₆ ] ^{n where} M is a divalent Group 8 cation (ie, Fe ⁺² ,
Ru ⁺² or Os ⁺² ) and L ₆ represents ₆ independently selectable coordination ligands, provided that at least 4 of the ligands are anionic ligands. And at least one of the ligands is more electronegative than any of the halide ligands (ie, more electron withdrawing than the most electronegative halide ion, fluoride ion). , And n is a negative integer whose absolute value is less than 5.

At least 4 ligands should be present to facilitate incorporation of the dopant into the crystal lattice structure of the tabular grains.
The individual must be anionic. The remaining two ligands may likewise be anionic and may be in any convenient conventional neutral form, for example a carbonyl, aquo or amine ligand.

Only one ligand is required to be more electronegative than the halide ion, but some ligands, including all ligands, are more electronegative than the halide ion. May be high. One common method for evaluating electron-withdrawing properties is Inorgani.
c Chemistry: Principles of
Structure and Reactivit
y, James E. Huhey, 1972, Ha
rper and Row, New York and Absorp
Tion Spectra and Chemical
Bonding in Complexes, C.I. K.
Jorgensen, 1962, Pergamon
Reference is made to the spectrochemical series of ligands obtained from the absorption spectra of metal ion complexes in solution referred to in Press, London. As is clear from these references, the order of ligands in the spectrochemical series is as ^{follows: I - <Br - <S} - 2 <S CN - <Cl - <NO 3 - <F - <O H _{^{<ox - 2 <H 2 O}} <N CS - <CH 3 C N - <N H 3 <en <dipy <phen <N O 2 - <phosph << C N - <C O.

The abbreviations used are as follows: ox =
Oxalate, dipy = dipyridine, phen = o-
Phenatroline, and phosph = 4-methyl-2,
6,7-Trioxa-1-phosphabicyclo [2.2.
2] Octane. In the spectrochemical series, the ligands are in the order of electron withdrawing, with the first (I ⁻ ) ligand having the lowest electron withdrawing and the last (CO) ligand having the highest electron withdrawing in the series. . The underline indicates the binding site of the ligand to the polyvalent metal ion. The efficiency of the ligand in providing the electron withdrawing properties required for increased speed is determined by the fact that the ligand atom binding to the metal is changed from Cl to S,
It increases as the order of O, N, C changes. Therefore, the ligands C N ⁻ and C O are particularly preferred. Other preferred ligands are thiocyanate (N CS ^-), selenocyanate (N cse ^-), cyanate (N C
O ⁻ ), tellurocyanate ( N CTe ⁻ ) and azide (N ₃ ⁻ ).

When the metal M in the hexacoordination complex is Fe ⁺² , it is preferable that at least five of the ligands L have higher electron withdrawing properties than halide ions. When the metal M in the hexacoordination complex is Os ⁺² , a sufficient increase in speed is observed if only one ligand is more electron-withdrawing than the halide ion, but two such ligands are observed. It is preferable to have the above. Ru ⁺²
For the complex, it is preferred that at least three of the ligands are more electronegative than the halide ion.

When introduced, the Group 8 coordination complex can be combined with a counter ion for charge balancing similar to the above-mentioned iridium complex. According to the above requirements,
Ligand L can be any of the same conventional ligands as L ′ above (ie, McDuggle et al., US Pat.
No. 3,272, No. 4,981,781 and No. 5,
037,732, Marchetti et al., U.S. Pat. No. 4,937,180, Keevert et al., U.S. Pat. No. 5,037,732, and Olm.
Can be selected from among the various individual ligand forms described in U.S. Pat. No. 5,360,712.

[0057] Specific examples of Group 8 coordination complex dopant capable of enhancing the speed when used in combination with iridium dopants below: SET-1 [Fe (CN) _6] ^{- 4} SET-2 [Ru (CN ) _6] ^{- 4} SET-3 [Os (CN) _6] ^{- 4} SET-4 [Fe (pyrazine) (CN) _5] ^{- 4} SET-5 [RuCl (CN) _5] ^{- 4} SET-6 [OSBR ( CN) _5] ^{- 4} SET-7 [FeCO (CN) _5] ^{- 3} SET-8 [RuF ₂ (CN) _4] ^{- 4} SET-9 [OsCl ₂ (CN) _4] ^{- 4} SET-10 [Ru ( CN) ₅ (OCN)] ^{- 4} SET-11 _{[Ru (CN) 5 (N 3} ) ] ^{- 4} SET-12 [Os (CN) ₅ (SCN)] ^{- 4} SET-13 [Fe (CN) ₃ Cl ₃ ] ^-3 SET-14 [Ru (CO) ₂ (CN) ₄ ] ^-1 SET- 15 [Os (CN) Cl _5] ^{- 4}

The Group 8 dopant is effective at conventional concentrations relative to total silver, including both silver in tabular grains and silver in protrusions. Generally, the shallow electron trap forming dopant is at least 1 mole per silver mole.
From x10 ^-6 mol (1 mppm) up to its solubility limit, typically about 5 x 10 ^-4 mol (50 per mol silver).
It is conceivable to incorporate it at a concentration up to 0 mppm). The preferred concentration is about 10 ^-5 to 10 ^-4 per mole of silver.
It is in the range of mol (10 to 100 mppm).

The advantage of placing Group 8 dopants on the silver halide protrusions is that this arrangement does not (1) interfere with the favorable HIRF effect imparted by iridium, and (2) thickens the ultrathin tabular grains. By eliminating the risk of the dopant contributing to, and (3) arranging the Group 8 dopant on the protrusion, it is generally at or near the joint of the protrusion with the ultrathin tabular grains. It is arranged near a certain latent image forming part. Placing the dopant near the latent image formation site increases the efficiency of the dopant.

Silver halide epitaxy itself is
Photographic speed is increased to levels comparable to those obtained by substantially optimal chemical sensitization with sulfur and / or gold. Further chemical sensitization of tabular grains on which silver halide has been epitaxially deposited with a normal middle chalcogen (that is, sulfur, selenium or tellurium) sensitizer or a noble metal (for example, gold) sensitizer further increases the photographic speed. To do. These conventional chemical sensitization methods applicable to silver halide epitaxial sensitization are described by Resea
rch Disclosure, December 1989, Item 308119, Section III "Chemical Sensitization". Kofron et al. Describe applying these sensitizations to tabular grain emulsions.

In a particularly preferred approach to silver halide epitaxial sensitization, sulfur-containing ripening agents are used in combination with middle chalcogen (typically sulfur) and noble metal (typically gold) chemical sensitizers. Intended sulfur-containing ripening agents include U.S. Pat. No. 3,271,157 (M
cBride), U.S. Pat. No. 3,574,628 (Jones) and U.S. Pat. No. 3,737,313 (Rosenrants et al.), including thioethers. A preferred sulfur-containing ripening agent is US Pat. No. 2,222,2
64 (Nietz), U.S. Pat. No. 2,448,
534 (Lowe et al.) And US Pat. No. 3,32.
Thiocyanates described in No. 0,069 (Illingsworth). A preferred class of middle chalcogen sensitizers is described in US Pat. No. 4,749,6
46 and 4,810,626 (He
rz et al.) and tetra-substituted middle chalcogen ureas. Preferred compounds include those of the formula:

[0062]

Embedded image

Wherein X is sulfur, selenium or tellurium; each of R ₁ , R ₂ , R ₃ and R ₄ independently represents an alkylene, cycloalkylene, alkarylene, aralkylene or heterocyclic arylene group. R ₁ and R ₂ or R ₃ and R ₄ , together with the nitrogen atom to which they are attached, can complete a 5 to 7 membered heterocycle; and A ₁ , A ₂ , A ₃ and A ₄ Each independently represents a group containing hydrogen or an acid group, provided that A ₁ R _{1 to} A _1
At least one of ₄ R ₄ contains an acid group bonded to urea nitrogen through a carbon chain having 1 to 6 carbon atoms).

X is preferably sulfur and A ₁ R ₁
~ A ₄ R ₄ is preferably methyl or carboxymethyl (provided that the carboxy group may be in an acid form or a salt form). Particularly preferred tetra-substituted thiourea sensitizers are 1,
It is 3-dicarboxymethyl-1,3-dimethylthiourea. A preferred gold sensitizer is US Pat. No. 5,049,4.
No. 85 (Deaton) is a gold (I) compound. These compounds include those represented by the formula: (VII) AuL ₂ ⁺ X ⁻ or AuL (L
¹ ) ⁺ X ⁻ , where L is a mesoionic compound; X is an anion; and L ¹ is a Lewis acid donor.

Kofron et al. Introduce a spectral sensitizing dye into the emulsion prior to the heating step (finishing) which results in chemical sensitization.
The advantages of "dye in finish sensitization" are disclosed. Dyes in finish sensitization are particularly advantageous in the practice of this invention in which the spectral sensitizing dyes adsorb to the tabular grain surfaces and act as site directors for silver halide epitaxial deposition. Maskasky-I teaches the use of J-aggregating spectral sensitizing dyes, especially green and red absorbing cyanine dyes as site directors. These dyes are present in the emulsion before the chemical sensitizing finishing step. A much wider range of spectral sensitizing dyes is available if the spectral sensitizing dye present in the finish is not utilized as the site director for silver halide epitaxy. Kofron
Spectral sensitizing dyes disclosed by et al., Especially blue spectral sensitizing dyes represented by structures showing absorption maximums in the green and red parts of the spectrum and longer methine chain analogues,
Particularly preferred for inclusion in the ultrathin tabular grain emulsion of the present invention. It is specifically contemplated to select a J-aggregating blue absorption spectral sensitizing dye for use as a site director. Useful spectral sensitizing dyes are Research Dis
Closure, December 1989, Item 3081
19, section IV. Spectral sensitization and desensitization, A. Spectral sensitizing dyes are generally summarized in.

In a particularly preferred embodiment of the invention, the spectral sensitizing dye can also act as a site director and / or be present in the finish, although it must be fulfilled by the emulsion of the invention. Its only function is to increase the sensitivity of the emulsion to at least one region of the spectrum. Thus, if desired, the spectral sensitizing dyes can be added to the ultrathin tabular grains according to the invention after chemical sensitization is complete.

Ultrathin tabular grain emulsions have a significantly lower average grain volume than thicker tabular grains of the same average ECD and, therefore, have lower intrinsic silver halide sensitivity in the blue region of the spectrum of ultrathin tabular grains. . Therefore, the blue spectral sensitizing dye significantly improves photographic speed even when the iodide concentration of the ultrathin tabular grains is relatively high. At exposure wavelengths bathochromically shifted with respect to intrinsic silver halide absorption, ultrathin tabular grains rely almost exclusively on spectral sensitizing dyes for photon capture. Therefore, the one in which a spectral sensitizing dye having a light absorption maximum (including a longer wavelength blue, green, red and / or infrared absorption maximum) at a wavelength longer than 430 nm is adsorbed on the particle surface of the present invention is extremely large. Speed increases. This is partly because the average particle volume is relatively small,
This is also due in part to the relatively large average particle surface area available for adsorption of the spectral sensitizing dye.

In addition to the characteristics of the spectrally sensitized silver salt epitaxially sensitized ultrathin tabular grain emulsions described above, the emulsions and emulsions of this invention can be in any convenient conventional form. For example, according to conventional practice, a new emulsion satisfying the requirements of the invention can be prepared and then this emulsion can be blended with one or more other novel emulsions according to the invention or any other conventional emulsion. The usual emulsion formulation is Res
search Disclosure, Vol. 308, 19
December 1989, Item 308119, Section I,
Paragraph I describes.

The emulsion, once formed, can be further prepared for photographic use by any convenient conventional method. Further usual features are the Research Disclosure, item 3 above.
08119, Section II, Emulsion Washing; Section V
I, antifoggants and stabilizers; Section VII, color materials; Section VIII, absorbing and scattering agents; Section IX, vehicle and vehicle extenders; Section X,
Hardeners; Section XI, coating aids; and Section X
II, plasticizers and lubricants. VII to XI
The I features can optionally be provided in other photographic element layers.

The novel epitaxy silver halide sensitized ultrathin tabular grain emulsions of this invention can be used in any other conventional photographic element. The emulsion can be included in, for example, a photographic element having one or more silver halide emulsion layers. In one embodiment, the novel emulsions of this invention can be in a single emulsion layer of a photographic element intended to produce a silver or dye photographic image for viewing or scanning.

In one important aspect, the invention comprises at least two overlaid radiation-sensitive silver halide emulsion layers coated on a conventional photographic support of any conventional type. Directed to photographic elements. Typical photographic supports are Research Disclo above.
Sure, Item 308119, Section XVII
It is summarized in. Emulsion layers coated closer to the support side are spectrally sensitized to produce a photographic record when the photographic element is exposed to specular light in the minus blue region of the visible spectrum. The term "minus blue" is used in the art to mean the green and red parts of the visible spectrum (ie, 500-700 nm). The term "specular light" is used in the art to denote a spatially oriented type of light provided by the camera lens to the focal plane of the film surface, ie light that is not scattered for practical purposes. .

The second of the two silver halide emulsion layers is coated on the first silver halide emulsion layer. In this arrangement,
The second emulsion layer is required to perform two distinct photographic effects. The first of these effects is to absorb at least part of the wavelength of light to be recorded. The second emulsion layer comprises near-ultraviolet (≧ 300 nm) to near-infrared (≦ 15 nm)
It is possible to record light in any spectral region in the range of (00 nm). In most applications, the first and second emulsion layers record images in the visible spectrum. The second emulsion layer, in most applications, records blue or minus blue light and usually, but not necessarily, shorter wavelength light than the first emulsion layer. The ability of the second emulsion layer to strike a good balance between photographic speed and image composition (i.e., granularity and sharpness), independent of the intended recording wavelength, is important to satisfying the first effect.

The second different action that the second emulsion layer needs to perform is to transmit the minus blue light intended for recording in the first emulsion layer. The presence of silver halide grains in the second emulsion layer is essential for the first action, but the presence of the grains is sufficient for the transmission action of the second emulsion layer, unless selected as required by this invention. The ability to fulfill is greatly reduced. The emulsion layer provided above (eg, the second emulsion layer) may cause the image sharpness of the emulsion layer provided below (eg, the first emulsion layer) to decrease, so the second emulsion layer Is hereinafter also referred to as "optical causer layer", and the first emulsion layer is also referred to as "optical receiving layer".

As to how the (second) emulsion layer provided above causes a reduction in sharpness in the (first) emulsion layer provided below, Antoniades et al. (See herein) Incorporated) and does not need to be repeated. The preferred combination of photographic speed and image composition (eg granularity and sharpness) is at least a second overcoating using a silver halide epitaxially sensitized ultrathin tabular grain emulsion satisfying the requirements of the invention. It was found to be realized when the emulsion layer was formed. It is surprising that the presence of silver halide epitaxy on the ultrathin tabular grains of the overlying emulsion layer is consistent with the ability to see a sharp image in the first overlying emulsion layer. . Obtaining a sharp image in the underlying emulsion layer depends on the ultrathin tabular grains in the underlying emulsion layer accounting for a high percentage of the total grain projected area; however, ECD of 0.2.
If there are particles that are less than μm, they are relatively optically transparent and can be excluded from the calculation of total particle projected area. Excluding grains having an ECD of less than 0.2 μm from the total grain projected area calculation, the emulsion layer provided above containing the silver halide epitaxially sensitized ultrathin tabular grain emulsion of the present invention is a silver halide grain. It is preferable to occupy more than 97%, preferably more than 99% of the total projected area of

The second emulsion layer consists essentially of ultrathin tabular grains, except that grains having an ECD of less than 0.2 μm (hereinafter referred to as “optically transparent grains”) may be incorporated. It consists of The optical transparency of minus-blue light of particles having an ECD of less than 0.2 μm is
It is well reported in the art. For example, Li with a typical ECD of less than 0.05 to more than 0.1 μm.
It is well known that ppmann emulsions are optically transparent. Particles with an ECD of 0.2 μm are 400
nm light is significantly scattered, but minus blue light is limited in scattering. In a specifically preferred embodiment of the invention, E
Exceeding only 97% of the total projected area of the grains excluding only grains having a CD of less than 0.1 (optimally 0.05) μm, optimally 9
A tabular grain projected area of more than 9% is satisfied. Thus, in the photographic elements of this invention, the second emulsion layer consists essentially of the tabular grains provided by the ultrathin tabular grain emulsion layers of this invention or those tabular grains and optically transparent grains. Has been done. If optically clear grains are present, they are limited to less than 10%, optimally less than 5% of the total silver in the second emulsion layer.

The advantageous properties of the photographic elements of this invention depend on the choice of grains in the emulsion layer overlying the minus blue recording emulsion layer to provide a particular combination of grain properties. First, the tabular grains contain iodide at photographically significant levels. The iodide content confers art-recognized advantages over comparable silver bromide emulsions in terms of speed and, in multicolor photography, interimage effects. Second, the tabular grains occupy a very high percentage of the total grain population as described above, which, in combination with an average ECD of at least 0.7 μm and an average grain thickness of less than 0.07, gives a negative blue light emission. Scattering is greatly reduced. Average ECD of at least 0.
7 μm is, of course, advantageous apart from increasing the specularity of light transmission which allows the higher levels of speed achieved in the second emulsion layer. Third, silver is better utilized and lower levels of granularity are achieved by using ultrathin tabular grains. Finally, the presence of silver halide epitaxy can increase photographic sensitivity more than expected.

In a simple embodiment, the photographic element can be a black and white (eg silver image forming) photographic element in which the underlying (first) emulsion layer is orthochromatic or panchromatic sensitized. In another embodiment, the photographic element is a multicolor photographic element containing blue recording (yellow dye image forming), green recording (magenta dye image forming) and red (cyan dye image forming) layer units in either coating order. be able to. A wide variety of coating arrangements can be found in the above-mentioned Kofron et al.
It is disclosed in columns 56-58.

[0078]

EXAMPLES By reference to the following examples of emulsion preparations, emulsions and photographic elements satisfying the requirements of the invention,
The invention can be better understood. For the photographic sensitivity, the speed difference of 30 log units is 0.3 log E (however, E
Represents a relative log speed equal to the unit: exposure in lux second). Contrast is measured as midscale contrast. The halide ion concentration is represented by mol% (M%) with respect to silver.

Ultrathin tabular grain A 3.75 in lime-processed bone gelatin in a container equipped with a stirrer.
g, 4.12 g NaBr, antifoam, and pH at 39 ° C
Was charged with 6 liters of water containing sufficient sulfuric acid to adjust to 1.8. AgNO ₃ solution and halide (NaBr and KI are 98.5M% and 1.5M, respectively)
%) Solution and silver iodobromide 0.0133
During the nucleation achieved by adding in balance enough to produce 5 moles and simultaneously adding pBr and p
H was kept approximately at the value initially set for the solution in the reactor. Following nucleation, Oxone ™ (2KHS
O ₅ · KHSO ₄ · K ₂ SO ₄ Aldrich) 12
The gelatin in the reactor was rapidly oxidized by adding a solution of 8 mg dissolved in 20 cc of water, and the temperature was adjusted to 5 in 9 minutes.
Raised to 4 ° C. The reactor and its contents were held at this temperature for 9 minutes and then a solution of 100 g of methionine oxidised lime bone gelatin in 1.5 liter of water was added.
Add to reactor at ° C. The pH was then raised to 5.90 and 1M NaBr122.5cc was added to the reactor. 24.5 minutes after nucleation, the growth phase started, during which 2.5M AgNO ₃ , 2.8M NaBr and A
0.18M suspension of gI (Lippmann)
(A) uniformly maintaining the iodide level in the growing silver halide crystals at 4.125 M%, and (b) adjusting the pBr in the reactor until 0.848 mol of silver iodobromide was produced. , Na before the start of nucleation and growth
Br was added in proportion to maintain the value obtained by the addition of Br (53.33 minutes, constant flow rate), at this time,
1M NaBr105cc was added to increase excess Br ^- concentration; in-reactor pBr was maintained at the obtained value to balance growth. Then restart the flow of the reactants,
The flow rate was accelerated so that the final flow rate at the end of this segment was approximately 12.6 times the start; a total of 9 moles of silver iodobromide (4.125 M% I) was produced. AgNO ₃ , AgI
When the addition of NaBr and NaBr is complete, the resulting emulsion layer is coagulated and washed to preserve pH and pBr of 6 and 2.5, respectively.
Adjusted to.

The obtained emulsion was subjected to scanning electron microscopy (SE
M). Over 99.5% of total grain projected area was accounted for by tabular grains. The average ECD of the emulsion grains was 1.89 μm and their COV was 34. Since tabular grains account for nearly all of the grains present, average grain thickness was measured using the dye adsorption method: 1,1'-diethyl-2,2 required for saturation coverage. '-Cyanine dye level was measured and the solution absorption coefficient of this dye was 77,300 liters / mole-c
m, and the site area per mole is 0.566 nm ²
The equation for surface area was solved, assuming that This technique gave a mean grain thickness value of 0.053 μm.

Thin Emulsion B This emulsion was precipitated in exactly the same way as Emulsion A until 9 moles of silver iodobromide had been formed, then 6 moles of silver iodobromide emulsion was removed from the reactor. Further growth was carried out on 3 moles held in the reactor in order to act as seed crystals for further thickness growth. Prior to the start of this further growth, a solution of 17 g of methionine oxidised lime-processed bone gelatin in 500 cc of water was added at 54 ° C. and AgNO ₃ was slowly added alone until pBr was about 2.2. The pBr of the emulsion was reduced to about 3.3 and the Ag
Continued disproportionate inflow of NO ₃ and NaBr. While maintaining this high pBr value and temperature of 54 ° C., AgNO ₃ and mixed halide salt solutions (95.875 M% NaBr and 4.125 M% KI) were further added by 4.4 g of silver iodobromide.
Seed crystals were grown by adding 9 moles (4.125 M% I) to form; during this growth, the flow rate was doubled from start to finish. The obtained emulsion was coagulated and washed, and stored in the same manner as Emulsion A.

The resulting emulsion was investigated in the same manner as Emulsion A. The tabular grains accounted for more than 99.5% of the total grain projected area. The average ECD of this emulsion is 1.76.
μm and their COV was 44. The average thickness of the emulsion grains, determined from the dye adsorption measurement as described for Emulsion A, was 0.130 μm.

Sensitization The emulsion samples were then sensitized with and without the presence of silver halide epitaxy. 0.5 mol of the epitaxially sensitized emulsion sample was melted at 40 ° C., and pBr was adjusted to about 4 by simultaneously adding an AgNO ₃ solution and a KI solution. At this time, the AgNO ₃ solution and the KI solution were added in such a ratio that a small amount of silver halide precipitated during this preparation was 12% I. Then, after addition of 2M% NaCl (based on the initial amount of silver iodobromide host) spectral sensitizing dye 1 [anhydro-9-ethyl-5 ', 6'-dimethyoxy-5-phenyl-3'. -(3-Sulfopropyl)
-3- (3-Sulfobutyl) oxathia-carbocyanine hydroxide] and dye 2 [anhydro-5,5'-di-
Was added chloro-9-ethyl-3,3'-bis (3-sulfopropyl) thiacarbocyanine hydroxide, sodium salt], then, 6M by double jet addition of a balance of AgNO ₃ and NaCl solutions % AgCl
Epitaxy was formed. By this operation, epitaxy growth occurred mainly at the corners and edges of the host tabular grains.

The epitaxially sensitized emulsion was divided into small portions to determine the optimum level of the sensitizing component to be added subsequently, and the effect of level fluctuation was examined. The post-epitaxy component contains a further portion of Dyes 1 and 2, 60m
GNaSCN / mol _{Ag, Na 2 S 2 O 3} · 5H 2 O
(Sulfur), KAuCl ₄ (gold) and 11.44 mg 1
-(3-Acetamidophenyl) -5-mercaptotetrazole (APMT) / mol Ag was included. After all the ingredients were added, the mixture was heated to 60 ° C. to complete the sensitization and after cooling another 114.4 mg APMT was added. The resulting sensitized emulsion was coated on a cellulose acetate film support coated with a gray silver antihalation layer, and this emulsion layer was coated with a surfactant and a bis (vinylzulphonyl) methane hardener (1% based on total gelatin weight). 0.75% by weight) and was overcoated with a 4.3 g / m ² gelatin layer. The emulsion laydown was 0.646 g Ag / m ² , and in this layer coupler 1 and coupler 2 were 0.323 g / m ² and 0.019 g / m ² , 4-hydroxy-6-methyl-1,3, respectively. , 3a, 7, -Tetraazaindene (Na ⁺ salt) 10.5 mg / m ^{2 and} 2-
(2-Octadecyl) -5-sulfohydroquinone (Na
⁺ Salt) 14.4 mg / m ² , surfactant and gelatin total amount 1.08 g / m ² . The emulsion thus coated was passed through a proof neutral step tablet to
atten23A ™ filtration (wavelength> 560 nm transmission) daylight balance light exposure for 0.01 sec and color negative Kodak Flexicolor ™ C4
Developed using one process. Speed was measured at a density of 0.15 above the minimum density.

[0085]

Embedded image

Non-Epitaxial Sensitization Except for this sensitization omitting the epitaxial deposition step,
The epitaxial sensitization was performed in the same manner as described above. That is, after adjusting the initial pBr to about 4, dye 1 and dye 2
Is added in an appropriate amount, and then NaSCN, sulfur, gold and A are added.
PMT was added as above, followed by heat cycling at 60 ° C. The initial levels of optimized spectral sensitizing dyes, sulfur and gold sensitizers are:
It was at a level known to be almost optimum from the conventional experience based on the average grain ECD and the thickness. Then the dye,
Sensitization tests were conducted with systematic changes in sulfur and gold levels. Tables 1 and 2 below show the maximum speeds observed when sensitizing thin and ultrathin tabular grain emulsions A and B, respectively. Table 3 shows the contrast for the epitaxially sensitized thin and ultrathin tabular grain emulsions A and B shown in Tables 1 and 2.

Table 1 Speed increase by epitaxy to thin host tabular grains Type of host emulsion sensitization Dmin Relative logarithmic speed Emulsion B Non-epitaxy 0.11 100 Emulsion B Epitaxy 0.15 130

Table 2 Speed increase by epitaxy to ultrathin host tabular grains Type of host emulsion sensitization Dmin Relative logarithmic speed Emulsion A Non-epitaxy 0.14 100 Emulsion A Epitaxy 0.15 150

Table 3 Comparison of contrast between epitaxially sensitized thin and ultrathin tabular grain emulsions Host emulsion Emulsion type Sensitized contrast Emulsion B Thin epitaxy 0.68 Emulsion A Ultrathin epitaxy 0.89 From Table 1 and Table 2, It is clear that the speed increase obtained from epitaxial sensitization of ultrathin tabular grain emulsions is significantly greater than the speed increase obtained from comparable epitaxial sensitization of thin tabular grain emulsions. Furthermore, it is clear from Table 3 that the epitaxially sensitized ultrathin tabular grain emulsions have a higher contrast than the similarly sensitized thin tabular grain emulsions.

Comparison of Specularity The method of measuring the normalized specular transmission of light through a coating of emulsion as outlined in Example 6 of Antoniades et al. Was used. Table 4 shows the spectral sensitization described above.
Data on normalized specular transmission (NST%) of epitaxially sensitized thin and ultrathin tabular emulsions are summarized. Here, the normalized specular transmittance is a ratio of transmitted specular light to total transmitted light. The transmittance at 450 nm or 550 nm and the normalized specular transmittance were plotted against the silver coating amount. From these plots the silver coverage corresponding to 70% total transmission was determined and used to obtain specular transmission at both 450 nm and 550 nm.

Table 4 Comparison of specularity Host Spectral enhancement AgCl epi NST% Emulsion dye Taxi M% 450nm 550nm Thin emulsion B 1 & 2 6 20.7 18.6 Ultrathin emulsion A 1 & 2 6 70.7 71.6

It is clear from Table 4 that the epitaxially sensitized ultrathin tabular grain emulsions show a significant and surprising increase in the ratio of specular transmission to total transmission as compared to thin tabular grain emulsions. is there.

The same coatings as shown in Table 4, which gave a total transmission of 70% at 550 nm spectral absorption transfer , were further tested to show the absorption by dye 1 and dye 2 at the peak absorption wavelength (647 nm). , Absorption at shorter wavelengths was measured. 60 for 647 nm absorption
A comparison with 0 nm absorption is shown in Table 5, where the absorption at all off-peak wavelengths is lower for the epitaxially sensitized ultrathin tabular grain emulsion than for the similarly sensitized thin tabular grain emulsion.

Table 5 Relative Off- Peak Absorption Epitaxy Relative Absorption Host Emulsion Dye Mol% A600 / A647 Thin Emulsion B 1 & 2 6 0.476 Ultrathin Emulsion A 1 & 2 6 0.370

It is clear from Table 5 that the spectrally sensitized / epitaxially sensitized ultrathin tabular grain emulsions have significantly less off-peak absorption than the similarly sensitized comparative thin tabular grain emulsions. Emulsion C This emulsion was prepared in a manner similar to that described for Emulsion A, except that the precipitation procedure was modified to achieve a higher uniform iodide concentration (AgBr _0.88 I _0.12 ) during growth.
The particle size was made smaller.

Grain parameters were measured in the same manner as for Emulsion A.
As a result, all tabular grains were projected in Emulsion C.
Occupies 99.4% of the area, average particle ECD is 0.95μ
m (COV = 61) and the average particle thickness is 0.049
It was found to be μm. Relationship between specularity and epitaxy level AgCl epitaxy on host ultrathin tabular grains of emulsion C
The formation of sea is typically greater than 6 mol% / min epitaxy.
The flow rate that creates a sea
Then, it was carried out according to the general operation described above. Sulfur
Gold sensitization has a great influence on specularity.
Emulsion samples were not subjected to these sensitizations.
Was. In addition to spectral sensitizing dye 2, the following alternative spectral sensitizing dyes
Was used: Dye 3: Anhydro-6,6'-dichloro-1,1'-
Diethyl-3,3'-bis (3-sulfopropyl)-
5,5'-bis (trifluoromethyl) benzimidazo
Carbocyanine hydroxide, sodium salt; Dye 4: Anhydro-5-chloro-9-ethyl-5'-
Phenyl-3 '-(3-sulfobutyl) -3- (3-su
Rufopropyl) oxacarbocyanine hydroxide, Trier
Tylammonium salt; Dye 5: Anhydro-5,5'-dichloro-3,3'-
Bis (3-sulfopropyl) thiacyanine hydroxide,
Liethylammonium salt.

Epitaxial deposition produces sodium nitrate as a reaction byproduct in stoichiometrically related amounts, and if this byproduct remains in the emulsion when coated, an optical measurement is made. These epitaxied emulsions were all cohesively washed prior to coating to remove such salts, as they can cause interfering haze.

Table 6 Effect of Different Levels of Epitaxy on Specularity of Ultrathin Tabular Grain Emulsions Epitaxy NST (%) Dye Mol% 450 nm 550 nm 650 nm 2 0 71.4 68.4 − − 2 12 65.7 67. 0−−2 24 65.7 61.4−− 2 36 64.0 64.3−− 2 100 50.7 52.9−− 3 & 40 0 −−−− 59.3 3 & 4 12 −−−− 57. 1 5 0 −− 62.9 60.9 5 12 −− 57.6 57.7

From the data in Table 6, the specularity observed for host emulsions without epitaxy decreases only slightly after epitaxial deposition. Even more surprising is the high specularity observed with high levels of epitaxy. 450nm and 550n
Specularity at m is 0 epitaxy level
Note that increasing from 1 to 100% remains high. Although Antoniades et al. Did not use epitaxial sensitization, the normalized specular transmission is comparable to that reported by Antoniades et al. In Table 4. Furthermore, the epitaxy level is Maskas
higher than preferred in kyI,
Note that an acceptable level of specular transmission has been achieved, even though Maskasky I is alternatively taught to be useful.

Robustness Comparison To measure the robustness of emulsions of the present invention, sensitization was optimized so that the effect of slightly increasing or decreasing the amount of spectral sensitizing dye could be determined. Emulsion A was subjected to epitaxial sensitization with or without epitaxial sensitization in the same manner as the emulsions shown in Table 2 except that the operation for changing was carried out. The preferred levels of spectral sensitizing dyes and sulfur and gold sensitizers were determined by the following method: The initial levels were chosen based on conventional experience with these and similar emulsions so that the observations were near optimal. It started with sensitization. Spectral sensitizing dye levels were varied from this selection condition to the optimum workable spectral sensitizing dye level, and then sulfur and gold sensitizing levels were optimized for this dye level. The resulting sulfur (Na ₂ S ₂ O ₃
The optimal levels of 5H ₂ O) and gold (KAuCl ₄ ) were 5 and 1.39 mg / Ag mol, respectively.

Spectral sensitizing dye levels were varied with optimized sulfur and gold sensitization to determine the extent to which dye level differences affect emulsion sensitivity. The results are summarized in Table 7.

[0102] Table 7 Robustness Test: optimum sulfur and gold sensitization without epitaxy ultrathin tabular grain emulsions Dye 1 Dye 2 relative Δ type mM / AgM mM / AgM Suhi ° over preparative Bu Dmin sensitivity levels dye 0.444 1.731 100 0.14 Control High Level Dye 0.469 1.827 117 0.14 +17 Low level dye 0.419 1.629 84 0.15 −16

Every time the dye density is changed by 1%, 2.7
A change of 3 log sensitivity units occurred. When the change in speed was examined a second time, changing the concentration of the spectral sensitizing dye by 1% changed the speed by 4.36 log sensitivity units.
The variability of results between trials only played a role in strengthening the lack of robustness of emulsions lacking epitaxy.

Emulsion A was grown epitaxially in Table 2.
Other than epitaxial sensitization similar to emulsion
Repeated the above experiment. Sulfur (Na₂ S₂ O₃ ・
5H ₂ O) and gold (KAuCl_Four ) Is the optimum level
They were 2.83 and 0.99 mg / Ag mol, respectively. Conclusion
The results are summarized in Table 8 below:

[0105] Table 8 robustness tests: up optimum sulfur and gold using epitaxy sensitized ultrathin tabular grain emulsions Dye 1 Dye 2 relative Δ type mM / AgM mM / AgM Suhi ° over preparative Bu Dmin sensitivity levels dye 0.444 1.73 100 0.14 Control High Level dye 0.469 1.83 107 0.15 + 7 Low level dye 0.419 1.63 91 0.13 − 9

For each 1% change in dye density, the speed changed only 1.31 log speed units. This indicates that the robustness of the epitaxially sensitized ultrathin tabular grain emulsion was unexpectedly increased. Iodide Profile This series of comparisons is made to demonstrate the speed-granularity relationship enhancement made by providing an iodide profile in epitaxially sensitized ultrathin tabular grains satisfying the requirements of the invention.

[0107]Emulsion D (uniform 1.5M% iodide) In a container equipped with a stirrer, treat with an oxidant and add methionine.
2. Lime-treated bone gelatin that did not reduce the amount 3.
75g, 4.12g NaBr, antifoam and p at 39 ° C
Water containing sufficient sulfuric acid to adjust H to 1.8 6
I added liters. AgNO₃ Solution and halide (N
aBr and KI are 98.5 mol% and 1.5 mol, respectively.
%) Solution (both at 2.5M silver iodobromide 0.0133
A sufficient amount to produce 5 moles)
PB during nucleation achieved by simultaneous addition for 4 seconds
r and pH are almost equal to the values initially set for the solution in the reactor.
Maintained. Following nucleation, Oxone (2KHSO
_Five ・ KHSO_Four ・ K₂ SO _Four ) 128 mg of water 20 cc
Gelatin in the reactor by adding the solution dissolved in
Rapidly oxidizes and raises the temperature to 54 ° C in 9 minutes
Was. Hold reactor and its contents at this temperature for 9 minutes
Then, add 100 g of methionine oxide-lime-treated bone gelatin to water.
Add the solution dissolved in 1.5 liter to the reactor at 54 ° C.
Added Then the pH was raised to 5.90 and 1M Na
Br122.5cc was added to the reactor. 2 from nucleation
After 4.5 minutes, the growth phase started, during which 2.5 M A
gNO₃ 0.052 of 2.8M NaBr and AgI
4M suspension was added to the iodine in the growing silver halide crystals.
Keep the chloride level at 1.5M% evenly, and the reactor
Addition of NaBr as described above before nucleation and growth of internal pBr
Was maintained at the value obtained by. This pBr is iodobrominated
Proportionate to maintain until 0.825 mol silver is produced
(40 minutes, constant flow rate), at this time, 1M
 Excess Br by adding NaBr105cc^-Increase concentration
Then occurs to balance the growth of pBr in the reactor
Maintained at the value. The reactant introduction flow rate is set to the remaining 64 of the particle growth.
It accelerated about 12 times in a minute. 9 moles of silver iodobromide
(1.5 M% I) was produced. AgNO₃, AgI and
When the addition of NaBr is complete, aggregate the resulting emulsion layer
Wash and adjust pH and pBr to storage values of 6 and 2.5 respectively.
Arranged

The resulting emulsion was examined by SEM.
The tabular grains accounted for more than 99% of the total projected area of the grains, and the average ECD of the emulsion grains was 1.98 μm (coefficient of variation = 34). When the average grain thickness was measured by the same measurement method as for Emulsion A, it was 0.055 μm. Emulsion E (uniform 12M% iodide) This emulsion was precipitated in the same manner as Emulsion D. However,
The AgI: AgNO ₃ flow rate ratio was increased to obtain a uniform 12 M% silver iodide silver iodobromide grain composition, and the flow rate of AgNO ₃ and NaBr during growth was increased by about 1.93 times the growth time. To reduce re-nucleation during the growth of this lower solubility, higher iodide concentration emulsion.

When Emulsion E was analyzed by the same analysis method as used for Emulsion D, 98% by number was composed of tabular grains, and tabular grains accounted for over 99% of the total grain projected area. Was there. The average ECD of emulsion grains is 1.60 μm
(COV = 42) and the average thickness was 0.086 μm. It was especially noted that the introduction of 12 mol% iodide throughout the precipitation had the effect of increasing the thickness of the silver iodobromide tabular grains and no longer satisfied the requirements for ultrathin tabular grain emulsions. . Emulsion F (homogeneous 4.125 M% iodide) This emulsion was precipitated in the same manner as Emulsion D. However,
The AgI: AgNO ₃ flow rate ratio was increased to obtain a uniform 4.125 M% silver iodide silver iodobromide grain composition, and the flow rate of AgNO ₃ and NaBr during growth was increased by about 1.20 times the growth time. It was reduced to a longer time to prevent re-nucleation during growth of this lower solubility, higher iodide concentration emulsion.

When Emulsion E was analyzed by the same analysis method as that used for Emulsion D, 97.8% by number was composed of tabular grains, and tabular grains accounted for more than 99% of the total grain projected area. Was occupied. The average ECD of emulsion grains is 1.89.
μm (COV = 34) and average thickness is 0.053μ
It was m.

Emulsion G (Profiled Iodide) This emulsion was precipitated in the same manner as Emulsion D. However,
After the formation of 6.75 moles of an emulsion containing 1.5 M% I silver iodobromide grains (equal to 75% of total silver), AgI: A
By increasing the gNO ₃ addition ratio, the remaining portion of the 9 mol batch was 1
It was made to be 2 M% I. During this higher concentration iodide band formation, the flow rate based on the total Ag velocity fed to the reactor was about 25% of the flow rate used to form Emulsion D (total growth time 1.19 times). Long), to prevent re-nucleation during growth of this emulsion with lower solubility and higher iodide concentration.

When Emulsion E was analyzed by the same analysis method as used for Emulsion D, 97% by number was composed of tabular grains, and tabular grains accounted for more than 99% of the total grain projected area. Was there. The average ECD of emulsion grains is 1.67 μm
(COV = 39), and the average thickness was 0.057 μm. The composition and grain size data for Emulsions DG are summarized in Table 9 below.

Table 9 Emulsion grain size and halide data ECD thickness in AgIBr grains Emulsion iodide (μm ) (μm) Aspect ratio D 1.5M% I 1.98 0.055 36.0 (uniform) E 12.0M% I 1.60 0.086 18.6 (Uniform) F 4.125M% I 1.89 0.053 35.7 (uniform) G 1.5M% I 1.67 0.056 29.8 (first 75% Ag) 12M% I (final 25% Ag)

The data in Table 9 show that an emulsion satisfying the requirements of the invention (Emulsion G) was sized to grains of Emulsions D and F containing uniformly distributed 1.5 or 4.125 M% iodide concentrations, respectively. It was found that the particles contained the particles that were comparable to each other. However, Emulsion E, in which 12.0 M% iodide was evenly distributed within the grains, showed a decrease in average ECD, an increase in average grain thickness and a decrease in average aspect ratio of the grains.

[0115]Sensitization The emulsion samples were then similarly sensitized to give emulsions D, E, F and
Silver salt epitaxy is selectively applied to the corners of the tabular grain of G.
Formed. In each case, 0.5 mol test of host emulsion
Melts at 40 ° C, AgNO ₃ Solution and KI solution
The pBr was adjusted to about 4 by adding it at this time. This and
12M% of silver halide precipitated during this adjustment
It was I. Next, 2 M% NaCl (ultra-thin tabular grain milk
Dye 1 and Dye 2 after adding (based on the amount of silver in the agent)
And then AgNO₃ Solution and NaCl solution
6M% AgCl by adding double jet
Epitaxy was formed. Epitaxial deposition on flat plate
Confined to the corners of the particle.

The epitaxially sensitized emulsion was divided into small pieces.
Then, the optimum level of the sensitizing component to be added subsequently is calculated.
Both tested the effect of varying levels. Post epita
In addition to dyes 1 and 2, 60 mg Na
SCN / mol Ag, Na₂ S ₂ O₃ ・ 5H₂ O (Io
C), KAuCl_Four (Friday) and 11.44 mg APMT
/ Mol Ag was included. After adding all ingredients, mix
The material is heated to 60 ° C to complete the sensitization and cooled to 40 ° C.
After rejection, 114.4 mg of APMT was further added.

The sensitized emulsion obtained was coated on a cellulose acetate film support coated with a gray silver antihalation layer and the emulsion layer was overcoated with a 4.3 g / m ² gelatin layer. The emulsion coating amount was 0.646 g Ag / m ² ,
In this layer, coupler 1 and coupler 2 each have a thickness of 0.
323 g / m ² and 0.019 g / m ² , 4-hydroxy-6-methyl-1,3,3A, 7-tetraazaindene (Na ⁺ salt) 10.5 mg / m ² and 2- (2-octadecyl) -5-sulfohydroquinone (Na ⁺ salt) 1
4.4 mg / m ^{2 and} total gelatin amount 1.08 g / m ²
Was also included. 1. Based on surfactant and gelatin total weight.
This emulsion layer was overcoated with a 4.3 g / m ² gelatin layer containing 75% by weight of a bis (vinylsulfonyl) methane hardener.

The emulsion thus coated was exposed to Wratten 23A (trademark) filtered daylight balanced light for 0.01 seconds through a 21-step granularity step tablet (0 to 3 density range), and then Kodak Flexic.
Developed using the color ™ C41 color negative process. Speed was measured at a density of 0.30 above the minimum density.

Granularity readings for the same treated specimens were taken from SPSE Handbook of Photog.
radical Science and Engine
ering W. It was carried out according to the method described in Thomas, pp. 934-939. The granularity reading at each step was divided by the contrast at the same step and the minimum contrast normalized granularity reading was recorded.
The contrast-normalized granularity is expressed in particle units (gu).
(Where each gu represents a 5% change); a positive change and a negative change correspond to an image with greater grain roughness and an image with less grain roughness, respectively ( That is, a negative change is desirable). The contrast-normalized granularity was selected for comparison to remove the granularity difference due to the contrast difference. The granularity random dot model is
The granularity is inversely proportional to the square root of the number of image forming centers (M.
A. Kriss, The Theory of the
Photographic Process, 4th edition,
T. H. Edited by James, Macmill, New York
An, 1977; p. 625) and in emulsions the granularity is constant A because it generally suggests that grain size must be increased to increase sensitivity.
Approximately 7 g / g for every 30 log speed unit increase in coating amount and light efficiency. u. It is generally accepted that it will increase at a rate of Optimal sensitization of each of the emulsions was completed as described for Emulsions A and B. Table 10 shows the relative logarithmic speed and minimum contrast-normalized granularity for optimized sensitization.

Table 10 Sensitivity and Contrast Normalized Granularity Response Emulsion Δ Speed Relative Granularity Contrast D Control Control 0.85 E +9 +4.5 0.55 F +11 −3.0 0.91 G +21 −7.60 .94

The data in Table 10 show that the higher iodide lateral region grain structures provided when all of the corner epitaxial sensitization provided the three comparative emulsions (homogeneous iodide ultrathin tabular grains). ) Is clearly shown. An emulsion satisfying the requirements of the invention (Emulsion G) exhibits both maximum photographic speed and contrast as well as minimum image granularity, and therefore a comparative emulsion of similar structure (but lacking the required iodide profile). ) Was clearly photographically superior to.

Side placement region epitaxy and central region epi
Comparative Emulsion H with Taxi (Profiled Iodide, AgBr Central Region) This emulsion differs from Emulsions D through G except that it has a significant difference in reducing iodide concentration in the central region of the ultrathin tabular grains. It was similarly precipitated. The absence of iodide in the central region is of fundamental importance because the major surface portion of the ultrathin tabular grains formed by the central region accepts silver salt epitaxy in the absence of adsorption site directors. It was Therefore, by selecting this structure, it is possible to form one or more adsorption site-directing bodies with or without the presence or absence of the adsorption site-directing members, respectively, in the central region and the side arrangement region (specifically, the corner portion) of the epitaxial sensitization. I made a comparison. In addition to the above changes in halide composition, other changes to the precipitation procedure described above for Emulsions DG include the use of NaOCl rather than Oxone ™ for in situ oxidation of nucleated gelatin, batch size Increase (12 mol instead of 9 mol)
And a parabolic increase in flow rate at the beginning of growth.

The first 75% of silver was precipitated in the absence of iodide, while the remaining 25% of silver was precipitated in the presence of 6M% I. Emulsion H was analyzed by using the above-mentioned analysis method to find that tabular grains were 98% (9% of total grain projected area).
It accounts for more than 9%). The emulsion has an average ECD of 2.19 μm (COV =
54), and the average thickness was 0.056 μm.

Emulsion H / CR (Central Region)
Area epitaxial sensitization) The procedure used to form epitaxy on the major surface portion of the ultrathin tabular grains of emulsion H formed by the central region is
The procedure was similar to that described above for corner epitaxial sensitization of Emulsions DG except for the following: 1) The initial pBr adjustment prior to epitaxy formation was AgN.
AgNO ₃ alone was used instead of simultaneous addition of O ₃ and KI. 2) pBr was adjusted to about 3.5 instead of 4. 3) No dye addition prior to epitaxy formation.
(These differences were made to eliminate the angular orientation of epitaxy). 4) The AgCl epitaxy level based on Emulsion G before epitaxial deposition was 12 M% instead of 6 M%.

Scanning electron microscopy studies revealed that epitaxy was predominantly deposited on the major surfaces of the ultrathin tabular grains. For emulsions having optimal photographic performance obtained surface in an effort to obtain the (facial) epitaxy was varied the level of spectral sensitizing dye _{Na 2 S 2 O 3 · 5H} 2 O and KAuCl _4. Within the design range tested, optimum performance was determined at these levels (unit: mg / mol Ag), ie 2
50 dye 1, 1025 dye 2, 60 NaSCN, 3.1
3Na ₂ S ₂ O ₃ .5H ₂ O, 1.10KAuCl ₄ ,
Obtained at 11.44 mg APMT. After the addition of these compounds, the resulting mixture is heated to facilitate sensitization and then 1
14.4 mg APMT was added as stabilizer. Coating format, exposure and processing were as described above for Emulsions DG. The sensitivity-granularity relationship is summarized in Table 11 for comparison.

[0126]Emulsion H / LDR (Laterally Displaced Re
gion) (Epitaxial sensitization of side placement area) A common procedure for the formation of corner epitaxy is emulsion
It was the same as described above for D to G. However
However, like Emulsion H / CR, 12 mol instead of 6 mol%
% AgCl epitaxy, and
Dyes, sulfur and gold can be used as a means to obtain suitable photographic performance.
I changed the bell. Within the test design range, the following water
Optimal response was observed in the quasi (unit: mg / mol Ag)
That is, 250 dye 1 and
1025 dye 2, and each after epitaxy formation
25 mg and 102.5 mg, 3.13 mg Na₂ S
₂ O ₃ ・ 5H₂ O and 0.9 mg KAuCl_Four .

The obtained corner epitaxial sensitized emulsion was
Emulsion H / CR was coated, exposed and processed in the same manner. The sensitivity-granularity relationship is summarized in Table 11 for comparison.

Table 11 Sensitivity and Contrast Normalized Granularity Response Epitaxy Emulsion Position Δ Speed Relative Granularity H / CR Main Surface Control Control H / LDR Corner +51 +3

The data in Table 11 demonstrate that corner epitaxial sensitization has substantial advantages over epitaxial sensitization which includes epitaxy distributed on the major faces of the tabular grains. Emulsion H / LDR was 3 g. u.
Only disadvantageous, it was 51 speed units faster than Emulsion H / CR. This is a very favorable speed / granularity relationship: From the above description, the random dot model assumes 0.5 for a constant Ag coverage, assuming constant light efficiency.
About 11.9 g as a penalty with an increase in 1 log E speed. u. It is clear that we are predicting an increase in Therefore, the corner epitaxial sensitization of the profiled iodide ultrathin tabular grain emulsion of the present invention is the same profiled iodide ultrathin tabular grain emulsion but silver salt epitaxy is distributed on the major surface of the grain. However, it has a great advantage in terms of speed-granularity (light efficiency). Therefore, the improved photoefficiency of the emulsions of the present invention is not only due to the action of the iodide profile selected,
It is also a function of silver salt epitaxy and its configuration.

[0130]Increased iodide in epitaxy Various iodide sensitizations of Emulsion C Silver and halogenio introduced during epitaxial sensitization
With the iodide level of the silver halide protrusions formed with
A series of sensitizations were performed to clarify the relationship. Each place
In addition, 0.25 mol of Emulsion C was added to 1715 mg / mol
After coloring with Ag dye 2, AgNO₃ And KI are formed
A small amount of silver halide is the first composition AgI_0.12Br
_0.88At a relative rate corresponding to
Was adjusted to 4.0. Next, the host tabular grains contain
Silver halide epitaxy reaching 12 mol% of silver
Was precipitated. Chloride the halide and silver salt solutions
To maintain AgCl excess of 2 mol% to ensure precipitation of AgCl
While adding sequentially. The addition of silver and halide,
The following is based on the mol% of silver in the host tabular grains. A
gNO ₃ By adjusting the addition rate of 6 mol of epitaxy
Precipitated at a rate of% / min.

Sensitization C-1: 14 M% NaC for nominal (input) epitaxy composition of 12 M% AgCl
After the addition of 1 liter, 12M% AgNO ₃ was added. Sensitized C-2: 12.08 M% N for nominal (input) epitaxy composition of 12 M% AgI _0.16 Cl _0.84
After adding aCl, 1.92 M% AgI (Lippman
n) was added, followed by 10.08 M% AgNO ₃ . Sensitization C-3: 12 M% AgI _0.16 Br _0.42 Cl _0.42 nominal composition of 7.04 M% NaCl after addition 5.
04M% NaBr was added, followed by 1.92M% AgI.
(Lippmann), then 10.08 M% A
gNO ₃ was added.

Following the epitaxial deposition, the separately sensitized samples were subjected to chemically sensitized finishing conditions, with sulfur and gold sensitization to avoid complicating halide analysis of epitaxy protrusions. Didn't do it. Finishing with 60 mg NaSCN and APMT1 per mole silver
1.4 mg was added. After these additions, the mixture is mixed with 50
Heat to ° C and then add APMT 114.4 mg / mol Ag. Next, using the electron microscopy (AEM) method,
The actual composition of the silver halide epitaxy protrusions was measured rather than the nominal (input) composition. The general operation of AEM is described in J. I. Goldstein and D.M. B. Wil
liams, "X-ray Analysis in
the TEM / STEM ", Scanning El
electron Microscopy / 1977; first
Volume, IIT Research Institute,
March 1977, p. 651.

The composition of individual epitaxy protrusions was measured by focusing the electron beam sufficiently small and irradiating only the protrusions to be tested. By selectively arranging epitaxy protrusions at the corners of host tabular grains, addressing only epitaxy protrusions became easy. 25
Each corner epitaxy protrusion for each of the grains was examined for each sensitization. The results are summarized in Table 12.

Table 12 Halide detection in epitaxy Halide sample addition Halide Cl Br I C-1 C1 100% 72.6% 26.8% 0.6% I 16% C-2 C1 84% 69.4% 28.7% 1.9% I 16% C -3 Br / Cl 42% 28.4% 64.5% 7.2%

The minimum AEM detection limit was a halide concentration of 0.5 M%. As is clear from Table 12, C-
With respect to 1, even if chloride was the only silver halide added to the silver iodobromide ultrathin tabular grain emulsion during precipitation of epitaxy protrusions, transfer of iodide ions from the host emulsion to epitaxy was observed. However, the content of bromide ions is high. This is A of AgBr
This is probably because the solubility in gCl is higher than the solubility of AgI in AgCl. For C-2, iodide concentration increased above 1.5 M% when iodide was added along with chloride during epitaxial deposition, but the inclusion of bromide in epitaxy remained relatively constant. It was

Regarding C-3, when half of the chloride added in C-2 was replaced with bromide, even if the same amount of iodide was added at each sensitization, the iodide concentration was C-2. Compared to the large increase. Comparison of Nominal AgCl and Nominal AgICl Epitaxy Emulsion I A silver iodobromide emulsion was prepared containing 4.125 M% I based on total silver. The central region of the grains, which account for 75% of the total silver, contains 1.5 M% I, while the remaining 25% of the total silver.
The lateral placement region, which occupies%, contained 12 M% I.

A container equipped with a stirrer was treated with phthalic anhydride.
Gelatin 30.0 g (10% by weight), NaBr 3.60
g, defoamer and pH at 2.0 at 60 ° C.
Add 9.375 liters of water containing a sufficient amount of sulfuric acid
Was. AgNO₃ And halides (AgNO₃ 0.09
0 mole, NaBr 0.1095 mole, and KI 0.00
(81 mol) solution at the same time for 30 seconds without balancing
PBr in the reactor during nucleation achieved by adding
Decreased due to excess NaBr added during nucleation, p
H is almost equal to the value initially set in the reactor solution.
It remained constant. Following nucleation, the Oxone (quote
Standard) (2KHSO_Five ・ KHSO_Four ・ K₂ SO _Four ) 102
By adding a solution of 1 mg dissolved in 50 cc of water
The gelatin in the reactor was rapidly oxidized. Reactor and its
After holding the contents at this temperature for 7 minutes, methionine oxidation
1.5 liters containing 100g of lime-processed bone gelatin
Water was added to the reactor at 54 ° C. Then adjust the pH
Increase to 5.90, 12 minutes after completion of nucleation, 1M
NaBr196.0cc was added to the reactor. Nucleation complete
14 minutes after completion, the growth stage started, during which 2.30M
AgNO₃ Solution, 2.40M NaBr solution and AgI
(Lippmann) of 0.04624M suspension
The iodide level in the growing silver halide crystals was 1.
Proportional addition was made to maintain a uniform 5M%. Anti
PBr in the reactor grows before and during nucleation and nucleation.
Derived from the previous addition of NaBr. This pBr is
C. Maintained until 2.775 mol of silver bromide is formed (flow rate
Over the 26.2 minutes of the start of this segment 1.8
(Accelerated 7 times), at which time the inflow of the AgI suspension
Stop and concentrate the AgI suspension (0.4140
M) was started and the 12M% iodide portion was added.
AgNO starts growing₃ Addition rate of about 56%
Reduced to. Final growth stage (last 12.5 minutes)
Medium, AgNO₃ Flow acceleration (final flow is in this segment
Was 1.52 times that at the beginning of
Liquid and AgI suspension are adjusted to adjust the pBr in the reactor.
Addition of NaBr before and during nucleation and before the start of growth
Maintained as set by AgI₀. ₁₂Br_0.88
The composition achieved. A total of 3.7 mol of silver iodobromide was produced.
Was. AgNO₃, AgI and NaBr addition is complete
At this time, the obtained emulsion was coagulated and washed, and the pH and pBr were adjusted.
The storage values were adjusted to 6 and 3.0, respectively.

The resulting emulsion was examined by SEM.
Over 99% of the total grain projected area was accounted for by tabular grains. The average ECD of emulsion grains is 0.57
μm (COV) = 54. Since this emulsion is almost entirely tabular, the average grain thickness was measured by the dye adsorption method. 1,1'-diethyl-required for saturation coverage
The amount of 2,2′-cyanine dye was measured, and the solution extinction coefficient of this dye was 77,300 liter / mol-cm,
The equation for surface area was solved assuming that the site area per mole was 0.566 nm ² . This technique gave a mean grain thickness value of 0.043 μm.

Sensitization I-1 Nominal AgCl The following methods were used to evaluate epitaxy formation and sensitization and photographic response. In each case a 0.5 molar sample of Emulsion I was melted at 40 ° C and its p
Br was adjusted to about 4 by simultaneous addition of AgNO ₃ solution and KI solution. At this time, AgNO ₃ solution and K
Solution I was co-added in a ratio such that the small amount of silver halide that precipitated during this preparation was 12 M% I. Next, 2M
% NaCl (based on the initial amount of Emulsion I) was added, followed by 1696 mg of Dye 4 and 152.7 mg of Dye 6 [anhydro-3,9-diethyl-3 '-(N-sulfomethylcarbamoyl) per mol Ag. Methyl) oxathiacarbocyanine hydroxide] and then 6
M% AgCl epitaxy, AgNO ₃ solution and NaC
Formed by balanced double jet addition of solution (addition time: 1 minute). The component after epitaxy (the indicated level unit is per mol of total silver) is 0.1.
4 mg bis (2-amino-5-iodopyridine-dihydroiodide) mercuric iodide, 137 mg dye 4, 12.4 mg dye 6, 60 mg NaSCN,
6.4 mg of sensitizer 1 (sulfur), 3 mg of sensitizer 2
(Gold) and 11.4 mg APMT.

[0140]

Embedded image

After adding all the ingredients, the mixture is stirred at 50 ° C.
Heat for 5 minutes to complete sensitization, cool to 40 ° C, and then
An additional 114.35 mg of PMT was added. Coating support
The Remjet Anti-Halation Backing and Zera
Chin undercoat layer (4.89 g / m² ) And acetic acid cell with
It is a loin film support (thickness: 132 μm).
1.75 of the emulsion layer based on surfactant and total gelatin.
Contains wt% bis (vinylsulfonyl) methane hardener
4.3g / m² The gelatin layer was overcoated.
Emulsion coating amount is 0.538 g Ag / m² And this layer
Is 0.398g each for coupler 3 and coupler 4.
/ M² And 0.022 g / m² , 4-hydroxy-6-
Methyl-1,3,3a, 7-tetraazaindene (Na
⁺Salt) 8.72 mg / m² And 2- (2-octadeci
) -5-Sulfohydroquinone (Na ⁺Salt) 11.96
mg / m² , Surfactant and gelatin total 1.08 g
/ M²Also contained.

[0142]

[Chemical 4]

The emulsion thus coated was subjected to Wratten 9 filtration (wavelength> 460 nm) daylight balanced light exposure for 0.01 seconds through a 21-step granularity step tablet (0-3 density range), and then Kodak. Fl
Developed using the exicolor C41 color negative process. Speed was measured at a density of 0.15 above the minimum density. Granularity readings were taken as described for Emulsions DG on similarly treated specimens.

Sensitizer I-2 Nominal AgICl sensitization, coating and evaluation were performed as for Sensitivity D-1. However, the halide salt solution used for forming the double jet of the epitaxy was 92M% Cl added as NaCl.
And 8 M% I added as KI. Sensitization I-1
Table 13 shows the performance comparison between I and I-2.

Table 13 Performance Comparison of Various Iodides in Epitaxy Nominal Contrast Epitaxy Normalized Halide Dmin Speed Contrast Granularity * C1 0.10 198 1.15 Control C1 0.92 I 0.08 0.08 196 1.39 -3.1gu * 4 Exposures Near Minimum Granularity Average readings over volume steps

Emulsion J A silver iodobromide emulsion containing 4.125 M% I based on total silver was prepared. The central region of the grains, which accounts for 75% of the total silver, is 1.
5M% I, while the remaining 25 of the total precipitated silver
The lateral placement region, which occupies%, contained 12 M% I.
In a container equipped with a stirrer, 3.75 lime-processed bone gelatin
g, NaBr 4.12 g, defoamer and water 6 containing sufficient sulfuric acid to adjust the pH to 1.86 at 39 ° C.
I added liters. AgNO ₃ and halide (Na
Br and KI are 98.5M% and 1.5M% respectively) and balanced and added simultaneously for 4 seconds in sufficient amounts to produce 0.01335 moles of silver iodobromide at 2.5M. During the nucleation achieved, pBr and pH remained approximately at the values originally set for the solution in the reactor. Following nucleation, Oxone (2KHSO ₅ · KH
The _{SO 4 · K 2 SO 4)} 128mg rapidly oxidized methionine in the reactor gelatin by adding a solution prepared by dissolving in water 50 cc, was raised to 54 ° C at the temperature for 9 minutes. After holding the reactor and its contents for 9 minutes at this temperature, a solution of 100 g of methionine lime oxide-treated bone gelatin in 0.5 liter of water was added to the reactor at 54 ° C. Then the pH was raised to 5.87 and 1M Na
Br107.0cc was added to the reactor. Twenty-two minutes after the start of nucleation, the growth stage was started, during which 1.6 M A
gNO ₃ solution, 1.75M NaBr solution and AgI
(Lippmann) 0.0222M suspension at 1.5 iodide levels in growing silver halide crystals.
It was kept homogeneous at M% and the reactor pBr was added proportionately to maintain the value obtained from the addition of NaBr before nucleation and initiation of growth. This pBr was maintained until 0.825 mol of silver iodobromide was formed (constant flow rate for 40 minutes), at which time 1.75M NaBr75cc was added to increase the excess Br ^- concentration and the pBr in the reactor was The values obtained from balanced growth were maintained.
The AgNO ₃ flow rate was accelerated to about 8.0 times its starting value during the next growth of 41.3 minutes. After 4.50 moles of emulsion formed (1.5 M% I), the AgI: AgNO ₃ flow ratio was changed so that the remainder of the 6 mole batch was 12 M% I. At the beginning of the formation of this high iodide band,
During the formation of this solubility-decreased and iodide-enriched band, the rate of total silver fed to the reactor was reduced to about 25% of the value at the end of the previous segment first. Re-nucleation was avoided, but the flow rate was doubled between the start and end of this section. Ag
When the addition of NO ₃ , AgI and NaBr was complete, the resulting emulsion layers were cohesively washed and the pH and pBr were adjusted to storage values of 6 and 2.5, respectively.

Grain size and thickness were measured by the method described for Emulsion H. Average particle ECD is 1.30μ
m (COV = 47) and the thickness was 0.052 μm. Tabular grains accounted for greater than 99% of total grain projected area.

Sensitization J-1 A 0.5 molar sample of Nominal AgCl Emulsion J is melted at 40 ° C. and its pBr is such that the small amount of silver halide precipitated during this preparation is 12 M% I. By ratio, AgNO ₃ solution and KI
The solution was adjusted to about 4 by simultaneous addition. Next, 2M% NaCl (based on silver in Emulsion J) was added, followed by 1170 mg Dye 4, 117.9 mg Dye 6 and 119 mg Dye 7 per mole Ag.
[Anhydro-9-ethyl-5,6-dimethoxy-5 '
- addition of phenyl-3,3'-bis (sulfopropyl) oxacarbocyanine hydroxide, sodium salt], then, AgNO ₃ solution and a double jet addition was balanced with NaCl solution (addition time: 1 minute ) By 6
M% AgCl epitaxy was formed. After the formation of epitaxy, the resulting emulsion was chilled and then 0.
A 04 molar portion was taken and used for the remaining steps of sensitization.
This allowed varying levels of sensitizer to determine optimal treatment combinations. The components after epitaxy (the unit of the stated level is per mol of silver) is
Dye 4, Dye 6 and Dye 7, NaSCN 60 mg / mol Ag, Sensitizer I (Sulfur), Sensitizer 2 (Gold), and N-
It contained 8.0 mg of methylbenzothiazolium iodide. After all the ingredients have been added, the mixture is heated at 50 ° C for 5 minutes to complete the sensitization and after cooling to 40 ° C, APMT
Was further added in 114.35 mg.

Coating, exposure, processing and evaluation were carried out by the methods described above for sensitizing Emulsion H. Within the survey design range, the optimum speed / Dmin (Dmin = 0.1
A response of <0) was observed for these post-sensitized additions (level: mg / mol Ag). 243 mg
Dye 4, 12.15 mg dye 6, 12.2 mg dye 7, 2.68 mg sensitizer 1 and 1.35 mg sensitizer 2.

Sensitization J-2 The same operation as the nominal AgICl sensitization J-1 was repeated. However, the halide salt solution used to form the epitaxy is 84
M% NaCl and 16M% KI. That is, the optimum photographic response was observed at the same sensitizer level as for the sensitized E-2 nominal AgCl epitaxial sensitization. Table 14 shows a performance comparison between the sensitized J-1 and J-2.

Table 14 Performance Comparison of Different Iodides in Epitaxy Nominal Contrast Epitaxy Normalized Halide Dmin Speed Contrast Granularity * C1 0.10 240 1.42 Control C1 0.84 I 0.16 0.08 241 1.58 -2.8gu * 4 Exposures Near Minimum Granularity Average readings for steps over amount

From a comparison of Tables 13 and 14, increasing iodide in silver halide epitaxy increases contrast and decreases granularity, and Table 1 compares with Table 13.
A further increase in iodide in 4 further increased the contrast. Emulsion K A silver iodobromide emulsion containing 4.125 M% I based on total silver was prepared. The central region of the grains, which accounted for 74% of the total silver, contained 1.5 M% I, while the laterally located regions, which accounted for the remaining 26% of the total precipitated silver, contained 12 M% I.

In a container equipped with a stirrer, 3.75 g of lime-processed bone gelatin, 4.12 g of NaBr, an antifoaming agent and 39 °
6 liters of water containing sufficient sulfuric acid to adjust the pH to 5.41 with C were added. AgNO ₃ and halides (NaBr and KI 98.5 M% and 1.
5M%) solution, silver iodobromide 0.013 at both 2.5M
During the nucleation achieved by simultaneous simultaneous addition of 4 seconds in an amount sufficient to produce 35 mol, pBr
And the pH remained at the value originally set for the solution in the reactor. Following nucleation, the methionine in the reactor gelatin was rapidly oxidized by adding 0.656 cc of a solution of 4.74 M% NaOCl, and the temperature was raised to 54 ° C in 9 minutes. After holding the reactor and its contents at this temperature for 9 minutes, 100 g of methionine lime oxide-treated bone gelatin was dissolved in 1.5 liters of water.
° C solution and 1M NaBr122.5cc were added (pH after addition was about 5.74). 2 from nucleation
After 4.5 minutes, the growth phase started, during which 2.50M
AgNO ₃ solution, 2.80M NaBr solution and AgI
(397 ppm) of (Lippmann) at a iodide level of 1.5 in the growing silver halide crystals.
It was kept uniform at M% and the pBr in the reactor was added proportionately to maintain the value obtained from the addition of NaBr above before nucleation and growth initiation. This pBr is maintained until the formation of 0.825 mol of silver iodobromide (constant flow rate for 40 minutes), at which time 1M NaBr105cc is added to increase the excess Br ⁻ concentration and to grow the pBr in the reactor in a balanced manner The value obtained from the above was maintained. AgNO
The flow rate of ₃ was accelerated to about 10 times the starting value in this segment during the next 52.5 minutes of growth. Emulsion 6.6
After 9 moles had formed (1.5 M% I), AgI: AgN
The O ₃ flow rate ratio was set to 12 M%
Was changed to. At the beginning of the formation of this high iodide band, the growth reactant flow rate, based on the amount of total silver fed to the reactor, was initially set at about 2 times the value at the end of the previous segment.
Reducing to 5% to avoid re-nucleation during the formation of this reduced solubility and higher iodide concentration band, the flow rate was accelerated during the formation of this part of the emulsion (final flow rate). Is 1.6 times the start of this segment).
When the addition of AgNO ₃ , AgI and NaBr was complete, the resulting emulsion was coagulated and washed, and the pH and pBr were adjusted to storage values of 6 and 2.5, respectively.

Grain size and thickness were measured by the method described for Emulsion H. Average particle ECD is 1.50μ
m (COV = 53) and the thickness was 0.060 μm. Tabular grains accounted for greater than 99% of total grain projected area. Sensitized K-1 A 0.5 molar sample of nominal AgCl Emulsion K was melted at 40 ° C and its pB
r is a small amount of silver halide which precipitates during this preparation.
Adjusted to about 4 by co-adding AgNO ₃ solution and KI solution in a ratio such that it was M% I. Next, 2M%
NaCl (based on initial silver content of Emulsion F sample) was added, followed by Dye 4 and Dye 6 (1173 and 106 mg / mol Ag respectively), after which a 6 mol% epitaxy was formed as follows. did. Single-jet addition of 6M% NaCl based on the initial amount of host emulsion followed by 6M% AgNO ₃ single-jet addition. AgNO ₃ was added for 1 minute. The additive component after epitaxy was 60 mg NaSCN / mol Ag,
_{Na 2 S 2 O 3 · 5H} 2 O ( sulfur sensitizing agent) and KAu
Cl ₄ (gold sensitizer) and 3.99 mg 3-methyl 1,
It was 3-benzothiazolium iodide / mol Ag.
The sulfur and gold sensitizer levels used were the best levels obtained from several trial sensitizations. After all the ingredients were added, the mixture was heated at 60 ° C for 8 minutes to complete the sensitization. 40 ° C
After cooling to 114.35 mg APMT / mol Ag was added. The optimum sensitization is 2.9 mg / M Ag Na ₂ S _2.
O ₃ · 5H ₂ O and 1.10mg / M Ag KAuC
It was l ₄ .

Instead of coupler 3, coupler 5 (0.3
23 g / m ² ) and the coating amount of coupler 2 is 0.0
Coating, exposure, processing and evaluation were carried out by the methods described above for sensitizing Emulsion H, except at 16 g / m ² .

[0156]

Embedded image

Sensitization K-2 The same procedure as for nominal AgIBrCl Sensitization K-1 was repeated. However, 6M% Na
Instead of sequential single jet additions of Cl and 6M% AgNO ₃ , the following materials were added sequentially: 2.52M
% NaCl, 2.52M% NaBr, 0.96M% Ag
I (Lippmann) and 5.04M% AgNO _3.
The above percentages are based on the silver supplied by Emulsion K. Optimal sensitization is 2.3 mg / M Ag Na ₂ S
₂ O ₃ .5H ₂ O and 0.80 mg / M Ag KAu
It was Cl ₄ . A comparison of the performance of sensitized K-1 and K-2 is summarized in Table 15.

Table 15 Performance Comparison of Different Iodides in Epitaxy Nominal Contrast Epitaxy Normalized Halide Dmin Speed Contrast Granularity * C1 0.09 100 0.51 Control C1 0.42 Br 0.42 I 0.16 0.08 106 0.56 -3.5gu * Near minimum granularity Average of readings of steps exceeding 4 exposures

From Table 15 it is clear that the increase in bromide and iodide in silver halide epitaxy increased contrast and reduced granularity. Examination of Dopants The following examples show that incorporation of a shallow electron trap (SET) dopant in silver halide epitaxial sensitization of ultrathin tabular grain emulsions increases photographic speed.
This is illustrated by the SET-doped epitaxial sensitization and the undoped epitaxial sensitization of Emulsion L and Emulsion M. Emulsion N (undoped) and emulsion O (doped) exemplify that the presence of iridium in the host ultrathin tabular grains can significantly reduce reciprocity law failure. Emulsions N to Z are SETs in the host tabular grain portion of the epitaxially sensitized ultrathin tabular grain emulsion.
6 illustrates that dopants increase photographic speed.

Emulsions AA and BB were added to the host tabular grain portion of the epitaxially sensitized ultrathin tabular grain emulsion.
It illustrates that the addition of both ET and iridium dopants significantly, if not completely, diminishes the ability of the iridium dopant to reduce high intensity reciprocity law failure (HIRF). Emulsion CC illustrates that by moving the SET dopant to epitaxy while leaving the iridium dopant in the ultrathin tabular grains, higher speeds are obtained while retaining the effect of reducing the HIRF of the iridium dopant. is there.

By SET dopant in epitaxy
Speed Improvement In a reaction vessel equipped with an emulsion L (host tabular grain in which iodide is graded) stirrer, 3.75 g of lime-processed bone gelatin, 4.12 g of NaBr, an antifoaming agent and 3
Charged 6 L of water with sufficient sulfuric acid to adjust pH to 5.42 at 9 ° C. 2.5M AgNO ₃ solution and 2.5M halide solution (98.5M% Br and 1.
Nucleation was carried out by adding 5 M% I as NaBr and KI respectively) in an amount sufficient to form 0.01335 mol of silver iodobromide simultaneously for 4 seconds in a balanced manner. Both pBr and pH were maintained at or near the values originally set in the reaction vessel.

After the nucleation, the methionine portion of gelatin in the reaction vessel was replaced with a 0.062 wt% NaOCl solution 50c.
It was oxidized by introducing c and the temperature in the reaction vessel was raised to 54 ° C. over 9 minutes. After holding at this temperature for 9 minutes, 1.5 L at 54 ° C was added to the reaction vessel.
100 g of methionine-oxidized lime-treated bone gelatin dissolved in H ₂ O was added. 24.5 minutes after nucleation, the growth stage was started, during which 2.5M AgN
O ₃ , 2.8M NaBr and 0.0394M AgI
The (Lippmann) suspension was added in small portions so as to keep the amount of iodide in the growing silver iodobromide grains uniform at 1.5 M% and the pBr in the reaction vessel almost constant. The pBr was maintained using a constant flow rate for 40 minutes until 0.826 moles of silver iodobromide was formed,
At that point, 105 cc of 1 M NaBr was added to increase the stoichiometric excess of Br ⁻ concentration. The reaction vessel was maintained at the pBr value obtained for balancing particle growth. During the next 52.5 minutes, accelerate the AgNO ₃ flow rate so that the final flow rate is about 10 times higher than the original flow rate,
6.75 mol of AgBr _0.985 I _0.015 was formed.
In the final growth segment, AgNO ₃ , AgI and Na
The flow rate of Br was continued, but the concentration of AgI suspension was high (0.341M), and the initial flow rate of 2.5M AgNO ₃ was decreased (about 0.25 times as much as that at the end of growth of 1.5M% I). Let During this growth segment, the AgNO ₃ flow rate was accelerated so that its final flow rate was 1.6 times the original. The relative flow rates of AgNO ₃ , AgI and NaBr were adjusted to maintain the pBr of the previous growth segment and ultimately deposit 2.25 moles of silver so that the iodide concentration was 12 M% with respect to silver. I chose

After completion of the final growth segment,
Cooled to ° C and coagulated and washed. Then pH and pB
r was adjusted to conserved values of 6 and 2.5 respectively. The resulting tabular grain silver iodobromide emulsion exhibited an iodide concentration of 1.5 M% for the first 75% of the precipitated grains and 12 M% for the last 25% of the precipitated grains. The grain properties were measured as reported for Emulsion A. Over 99% of the total grain projected area was accounted for by tabular grains. The average ECD of the particles is 1.50 μm (COV = 5
It was 2). The average thickness of the tabular grains is 0.060 μm
Met. In a reaction vessel equipped with an emulsion M (host tabular grain in which iodide was graded) stirrer, 4.21 g of lime-processed bone gelatin, 4.63 g of NaBr, an antifoaming agent and 3
6.75 L of water containing sufficient sulfuric acid to adjust the pH to 1.77 at 9 ° C was charged. 2.4M AgNO ₃ solution and 2.4M halide solution (98.5M% Br and 1.5M% I added as NaBr and KI respectively) sufficient to form 0.0150 moles of silver iodobromide. At the same time, the nucleation was carried out by adding them while balancing for 4 seconds. Both pBr and pH were maintained at or near the values originally set in the reaction vessel.

After nucleation, the methionine portion of gelatin in the reaction vessel was replaced with 50 cc of a 0.07 wt% NaOCl solution.
Was introduced and the temperature in the reaction vessel was raised to 54 ° C. over 9 minutes. 6 at this temperature
After holding for 1 minute, 1 ml of methionine-oxidized lime-processed bone gelatin dissolved in 1.5 L of H ₂ O (additionally containing 0.165 mol of NaOH) at 54 ° C was added to the reaction vessel.
After adding 00 g, the pH was adjusted to 5.85. 24.4 minutes after nucleation, the reaction vessel was charged with 1M halide solution (33M% NaBr and 67M% NaCl) 333.6.
cc was added. 1 minute later, the growth stage started,
Meanwhile, 3.0M AgNO ₃ , 3.33M NaBr
And 0.181 M AgI (Lippmann) suspension at 4.125 times the iodide content in the growing silver iodobromide grains.
It was added in small portions to keep it uniform at M% and to keep the pBr in the reaction vessel almost constant. This pBr
Maintain until 0.635 moles of silver iodobromide is formed,
At that point, 147.4 cc of 1.5 M NaBr was added to increase the stoichiometric excess of Br ⁻ concentration. The reaction vessel was maintained at the pBr value obtained for balancing particle growth. AgNO ₃ , AgI and NaBr
Of the flow rate, in a reaction vessel 6.81 mole of AgI _{0. 04125}
Continued until the formation of Br _0.95875 (105.6 minutes,
Acceleration of the flow rate so that the final flow rate of AgNO ₃ is 9.6 times the initial flow rate).

In the final growth segment, AgNO ₃ , A
The flow rates of gI and NaBr were continued, but the concentration of AgI suspension was high (0.527M) and 3.0M AgNO.
The initial flow velocity of ₃ was decreased (about 0.49 times that at the end of growth of 4.125 M% I). During this growth segment, A
The flow rate of gNO ₃ is kept constant, and AgNO ₃ , AgNO ₃
The relative flow rates of I and NaBr were controlled so that the iodide concentration was 12 M% with respect to silver while maintaining the pBr of the previous growth segment and finally depositing 2.25 mol silver.

After the final growth segment was completed, the emulsion was washed with 40
Cooled to ° C and coagulated and washed. Then pH and pB
r was adjusted to conserved values of 6 and 2.5 respectively. The resulting tabular grain silver iodobromide emulsion exhibited an iodide concentration of 4.125 M% for the first 75% of the precipitated grains and 12 M% for the last 25% of the precipitated grains. The grain properties were measured as reported for Emulsion A. Over 99% of the total grain projected area was accounted for by tabular grains. The average ECD of the particles was 1.79 μm. The tabular grains had an average thickness of 0.056 μm.

[0167]Epitaxial sensitization Next, samples of Emulsion L and Emulsion M were sampled in the presence of a dopant.
It is sensitized by epitaxial deposition with and without
Was. A 0.5 molar sample of the emulsion was melted at 40 ° C and the p
Br was adjusted to about 4 and a small amount of ha was precipitated during this adjustment.
AgNO at a ratio such that silver rogenide is 12% I ₃Melting
Solution and KI solution were added simultaneously. Then, (silver iodobromide
Add 2M% NaCl (based on the initial amount of host)
After adding the spectral sensitizing dye,
6 M% of silver iodobromochloride epitaxy was formed: C
aCl₂2.52 M% Cl added as^-, NaBr
2.52M% Br added as^-, AgI (Lipma
0.96 M% I added as suspension^-And 5.0
4M% AgNO₃. K, a shallow electron-trapping dopant_FourR
u (CN)₆(SET-2) introduced for sensitized epitaxy
In these samples, the dopant is NaB
AgNO after r₃Was added before.

For red sensitization, Dye 1 and anhydro-5,
5'-dichloro-9-ethyl-3,3'-bis (2-hydroxy-3-sulfopropyl) thiacarbocyanine hydroxide, triethylammonium salt, dye 8, and for green sensitization, dye 3 and dye. 4 was used. Epitaxially sensitized emulsion samples were divided into small amounts and the optimum amount of sensitizing component added later was determined. The post-epitaxy component was 0.75 mg of 4,4'-phenyl disulfide diacetanilide, an additional portion of the same sensitizing dye used previously, 60 mg of NaSCN / Ag moles, sensitizer 1 (sulfur sensitizer), Sensitizer 2 (gold sensitizer), 5.72 mg AP
MT / Ag mol (red sensitized emulsion only) and 3.99 mg of 3-methyl-1,3-benzothiazolium iodide / A
g mol (only green sensitized emulsion). After all of the post-epitaxy sensitizing components were added, the mixture was heated to 50 ° C for 5 minutes to complete the sensitization. After cooling to 40 ° C. a further 114.35 mg of AMPT / Ag mol was added.

The red sensitized emulsion was coated on a gray silver antihalation layer on a cellulose acetate film support. The green sensitized emulsion was coated on a similar support, which had a 4.89 g gelatin / m ² subbing layer and also had a REM jet antihalation layer on the back side instead of the gray silver antihalation layer. I had.

The emulsion coating amounts of the red sensitized emulsion and the green sensitized emulsion were 0.646 and 0.538 g Ag / m ² , respectively. Each emulsion layer contained a surfactant, 1.75 g / Ag mole of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene (Na ⁺ salt) and 2.40 g / Ag mole of 2-. (2-octadecyl) -5-sulfohydroquinone (Na ⁺ salt), dye-forming coupler, and a total of 1.
It contained 08 g / m ² of gelatin. Coupler 1 and Coupler 2 were used in the red sensitized emulsion samples at 0.323 and 0.019 g / m ² , respectively. Coupler 4 and coupler 5 were added to the green sensitized emulsion samples at 0.016 and 0.3, respectively.
23 g / m ^{2 was} used. Each emulsion layer was overcoated with a 4.3 g / m ² gelatin layer containing a bis (vinylsulfonyl) methane hardener at 1.75% by weight based on the total gelatin coating amount and a surfactant.

These emulsions were subjected to 0.01 second exposure-balanced daylight exposure. The red sensitized coating was exposed through a Ratten ™ 23A (> 560 nm transmission) filter and the green sensitized coating was exposed through a Ratten ™ 9 (> 460 nm transmission) filter. The exposure is performed through a 21-step granularity step tablet (density range 0 to 3), and then Kodak.
Developed by the Flexicolor ™ C41 color negative process. The speed is 0.1 from the lowest density
It was measured at 5 high concentrations. Granularity readings for the same treated strips were made as described for Emulsions DG.

A sample of Emulsion L was chosen as representative of emulsions according to the invention which were optimally sensitized to the red region of the spectrum. Each sample contained 223 mg of dye 1, 961 mg of dye 8, 2.25 mg of sulfur sensitizer and 0.79 mg of gold sensitizer per mol of Ag. 30 mppm K ₄ per mole of host emulsion during epitaxial deposition
Samples that differ only in the presence or absence of Ru (CN) ₆ are compared in Table 16 below. The addition of this dopant had no effect on tabular grain thickness or granularity.

Table 16 Effect of shallow electron traps included in epitaxy of green sensitized ultrathin tabular grain emulsion SET-2mppm Relative Log speed Dmin 0 100 0.15 30 111 0.18

By introducing a shallow electron trap-imparting dopant at a concentration of only 30 mole parts per million Ag of host emulsion, a significant speed increase of 0.11 log E was realized. There were no performance-detracting drawbacks, except for a slight (0.03) increase in minimum density. No increase in ultrathin tabular grain thickness or increase in granularity was observed. Furthermore, the speed increment provided by the shallow electron trapping dopant is comparable to the speed increment obtained by increasing the amount of iodide contained in the graded iodide profile and epitaxy of the host ultrathin tabular grains illustrated above. Was added to.

A sample of Emulsion M was chosen as representative of emulsions according to the invention which were optimally sensitized to the green region of the spectrum. Each sample contained 336 mg of Dye 3, 973 mg of Dye 4, 2.30 mg of sulfur sensitizer and 0.84 mg of gold sensitizer per mole of Ag. Samples that differ only in the presence or absence of 30 mppm K ₄ Ru (CN) ₆ per mole Ag host emulsion during epitaxial deposition are compared in Table 17 below. The addition of this dopant had no effect on tabular grain thickness or granularity.

Table 17 Effect of shallow electron trap included in epitaxy of red-sensitized ultrathin tabular grain emulsion SET-2mppm Relative Log speed Dmin 0 100 0.06 30 109 109 0.06

By introducing a shallow electron trap-providing dopant at a concentration of only 30 mole parts per million Ag of host emulsion, a significant speed increase of 0.09 log E was realized. There were no downsides in performance. No increase in ultrathin tabular grain thickness, increase in minimum concentration, or increase in granularity was observed. Furthermore, the speed increment provided by the shallow electron trapping dopant is comparable to the speed increment obtained by increasing the amount of iodide contained in the graded iodide profile and epitaxy of the host ultrathin tabular grains illustrated above. Was added to.

Reciprocity Law Failure Reduction Emulsion N ( Zonate Iodide, No Dopant) 3.84 g / L Methionine Oxide Treated Bone Gelatin, Defoamer, Sufficient to Adjust Solution pH to 2.0 6.56L of 0.0048M containing an amount of H ₂ SO ₄
To the NaBr solution, a 2.38M AgNO ₃ aqueous solution and a 2.38M Na (Br _0.95 I _0.05 ) aqueous solution were added at 50 ° C.
At 105.6 mL / min for 0.25 minutes. After nucleation and holding for 14 minutes, methionine-oxidized gelatin (70 g) was added as a basic aqueous solution, and the pH after addition was 6.0 (at 50 ° C).
Raised to. Then, 19 minutes after the nucleation, 1.
A solution of 0M NaBr was added in an amount sufficient to reduce the pBr to 1.95. Ag as an iodide source with 2.38M AgNO ₃ and 2.38M NaBr reagents
I (Lippmann) flow is used to reduce the iodide concentration in the internal region, which accounts for 75% of the total silver amount, and then the iodide concentration introduced is increased to 12 M% to account for the last 25% of the total silver amount. It was grown at 50 ° C. for 87 minutes so as to form a peripheral region, and the total average iodide content was about 4.5 M%.
During the first 20.33 minutes of precipitation, pBr was between 1.95 and 1.
It was carried out with a gradient of 7. After that, pBr was kept constant. During the first 59.83 minutes of precipitation (accounting for 75% of the total silver amount), the AgNO ₃ flow rate was 11.0 to 76.8 mL.
/ Min. The last two of silver introduction
Between 5%, the silver nitrate flow rate was 1 over 27.23 minutes.
Increased to 6.3-47.3 mL / min, and the Lippmann addition rate was 12 M% nominal silver iodide concentration to silver.
It was adjusted so that The emulsion is subsequently washed by ultrafiltration, and the pH and pBr are each kept at the stored values of 6.
Adjusted to 0 and 3.4.

From SEM analysis, the average ECD was 1.29 μm.
(COV = 60%), average particle thickness of 0.053 μm was obtained. The tabular grains account for> 95% of total grain projected area.
Was estimated to occupy.

Emulsion O ( Band iodide, Ir-doped) Emulsion N was prepared repeatedly, except that after the introduction of 70% of the total silver amount, the emulsion was formed without interrupting the addition of silver and halide. Of K ₂ IrCl ₆ was introduced as an aqueous solution in an amount of 0.05 mg per mol of total silver. SEM analysis showed that the physical dimensions of the emulsion grains remained essentially unchanged. Average particle ECD is 1.24 μm,
The average particle thickness was 0.055 μm. There was also no change in tabular grain projected area, estimated as a percent of total grain projected area.

Sensitization and Evaluation Emulsion N and Emulsion O were equally sensitized as follows. One mole of emulsion sample was heated to 40 ° C. and AgNO ₃ and KI
(Molar ratio 1: 0.12) was added at the same time to adjust pBr to about 4
Adjusted to. Then, 2 M% NaCl was added to the silver present before the pBr adjustment. Then, the red spectral sensitizing dye, Dye 1 and Dye 8 were added at a total molar concentration of 1.9 mmol / M Ag (molar ratio Dye 1: Dye 8 = 1: 4). Next, 6 mol% based on silver forming tabular grains
Of silver salt epitaxy was deposited. This is CaC
l _2, NaBr, AgI Lippmann was performed by sequentially introducing and AgNO ₃ (Cl:: Br molar ratio 42:42:16 in I). Each solution was introduced within 3 minutes. The observed epitaxy of the sample was mostly located at the corners of the tabular grains.

The epitaxially sensitized emulsion was then divided into small portions to establish the optimum level of chemical sensitization. 60 mg / Ag mol of NaSCN for each sample, sensitizer 1 as sulfur sensitizer, sensitizer 2, 8 as gold sensitizer
mg / Ag mol of APMT and 2.25 mg / Ag mol of bis (p-acetamidophenyl) disulfide were added. The emulsion containing the sensitizer was heated to 55 ° C for 25 minutes. After cooling to 40 ° C., 114.4 mg APMT was added. The optimum sensitization was identified from various amounts of sensitizer 1 and sensitizer 2 and used as the basis for the following examination.

The resulting sensitized emulsion was coated on a gray silver antihalation layer on a cellulose acetate film support and the emulsion was charged with 1.75% by weight of surfactant and total gelatin weight. A 1.076 g / m ² gelatin layer containing a bis (vinylsulfonyl) methane hardener was overcoated. The amount of emulsion coating is 0.646 gA
g / m ² and then, also the emulsion layer Couplers couplers 1 and 0.21 g / m ² of 0.646g / m ² 2,5.65m
g / m ² of 5-bromo-4-hydroxy-6-methyl-
It further contained 1,3,3a, 7-tetraazaindene triethylammonium salt and a surfactant. The total amount of gelatin was 2.15 g / m ² .

Emulsion N and Emulsion O were exposed in the same manner as Emulsion A,
However, depending on the sample, exposure was performed in the range of 10 ⁻⁵ to 1 second so that the reciprocity law failure could be inspected. In Table 18, the difference in speed observed between the exposure of 10 ^-5 seconds and the exposure of 10 ^-1 seconds is 0.15, 0.35, 0.
55, 0.75, 0.95 and 1.15 higher concentrations are reported. A negative value indicates that the shorter the exposure time is, the lower the speed is, that is, the high illumination reciprocity failure. Ideally, according to the reciprocity law, the exposure value (I ×
t, where I is the exposure intensity and t is the exposure time)
If they are equal, the same speed can be obtained regardless of the values of I and t. Therefore, the speed change amount (ΔlogE)
A value of zero means that the photograph is ideal (there is no reciprocity law failure).

Table 18 Effect of Iridium Doping on Reciprocity Law K ₂ IrCl ₆ mg / mol Ag D _min Delta Speed Emulsion Host D _min 0.15 0.35 0.55 0.75 0.95 1.15 N 0 0.19 -0.08 -0.12 -0.15- 0.18 -0.22 -0.29 O 0.05 0.19 -0.05 -0.04 -0.03 -0.02 -0.02 -0.05

What is clear from the above data is that not only is the reciprocity response of the Ir-doped emulsion O improved overall (as shown by the difference in speed being near the preferred zero), Above all, the contrast reciprocity law is improved. The Δ speed emulsion N becomes progressively larger with increasing concentration is 0 than D _min.
15 This shows that the contrast reciprocity law failure is more severe than the threshold speed reciprocity failure failure at a high speed point.

Shallow electron traps in ultrathin tabular grains
Dopant Emulsion P (No Dopant) Silver iodobromide (2.6M) was prepared according to the same procedure that Antoniades et al. Adopted for the precipitation of emulsions TE-4 to TE-11.
% I, uniform distribution) An emulsion was precipitated. Over 99% of the total grain projected area was accounted for by tabular grains.
The average ECD of the particles is 2.45 μm and the average thickness is 0.05.
It was 1 μm. The average aspect ratio of the particles was 48. No dopant was introduced during the precipitation of this emulsion.

Emulsions Q through Z A series of emulsions was prepared similar to Emulsion P except that ultrathin tabular grains were nucleated over long intervals of grain growth to minimize tabular grain thickening. The dopant was introduced after generation. Attempting to introduce the dopant into the reaction vessel prior to nucleation results in ultrathin tabular grain thickening, and at higher dopant concentrations the thickness is 0.07.
Tabular grains thicker than μm are obtained. All emulsions except Emulsion S showed the same iodide content and profile as Emulsion P. In emulsion S, iodide was not introduced in the interval of 0.2 to 55% of silver addition, and 2.
Precipitation was achieved by introducing a 6M% concentration of iodide.

The results are summarized in Table 19. Dopant concentrations are reported as moles of dopant (mppm) added per million moles of Ag.
The profile% refers to the interval of dopant introduction and is shown as a percentage of the total amount of silver present in the reaction vessel at the beginning and end of dopant introduction.

Table 19 Total Doubt Local Doubt Doubt Grain Thickness Emulsion mppm Concentration mppm Profil% μm Average Aspect Ratio Q 50 63 0.2- 80 0.050 48 R 110 138 0.2- 80 0.051 48 S 110 275 0.2- 40 0.049 44 T 110 275 0.2 -40 0.050 46 U 110 275 40- 80 0.051 48 V 110 275 60-100 0.049 51 W 110 550 60- 80 0.049 49 X 220 275 0.2- 80 0.050 45 Y 220 1100 60- 80 0.050 50 Z 440 550 0.2- 80 0.052 45

Sensitization and Evaluation Emulsions P to Z were similarly chemically and spectrally sensitized as follows. 150 mg / Ag mol of NaSCN, 2.1 mmol / Ag mol of Dye 2, 20 μmol / Ag mol of Sensitizer 1 and 6.7 μmol of Sensitizer 2 were added to the emulsion. The emulsion was then heat digested at 65 ° C. for 15 minutes before the addition of 0.45 M% KI and AgNO ₃ .

A sample of the sensitized emulsion was then coated as follows. 0.538 g Ag / m ² , 2.152 g / m ²
Gelatin (half from the first emulsion, half added), 0.9
68 g / m ² of coupler 1 and 1 g / Ag mol of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene (Na ⁺ salt). The emulsion layer was overcoated with 1.62 g / m ² of gelatin and 1.75% by weight of bis (vinylsulfonyl) methane, based on the total amount of gelatin in the emulsion layer and overcoat layer.

These emulsion coatings were filtered 5 through a Ratten ™ 23A filter (> 560 nm transmission).
Expose daylight of 500 ° K for 1/100 second, and Ko
Dak Flexicolor ™ C41 negative process was processed for 3 minutes and 15 seconds. The speed was measured at a density 0.15 higher than the minimum density. The sensitometric performance is summarized in Table 20.

Table 20 Dopant Speed Enhancement Emulsions Dopant (mppm) Profile% Relative log speed P None --- 210 V 110 60-100 223 W 110 60-80 222 X 220 0.2-80 228 Y 220 60-80 229 Z 440 0.2-80 233

It is clear from Table 20 that the shallow electron-trapping dopant has a speed of 0.13 log E to 0.23.
That is, the log E was increased. Antagonistic to increase speed and decrease HIRF
Compatible Emulsion Combination Emulsion AA 2.54 g / L Oxidized and Lime Treated Bone Gelatin,
Defoamer and enough H to adjust solution pH to 2.0
2.5M in a stirred reaction vessel containing 6.00L of 0.0056M NaBr solution containing ₂ SO _4.
AgNO ₃ aqueous solution and 2.5 M Na (Br _0.95 I
_0.05 ) aqueous solution was introduced by double jet injection method at 101.2 mL / min for 15 seconds at 50 ° C. After holding for 14 minutes following the nucleation, further oxidized gelatin (95.36 g) was added and the pH was adjusted to 6.0.
It was added in basic aqueous solution as it rose (at 50 ° C.). Next, at 19 minutes after the nucleation, 1.0M
A solution of NaBr was added in an amount sufficient to reduce the pBr to 1.95. Immediately after this, 100 mL of an aqueous 2.0 M NaCl solution was added. 2.38M AgNO ₃
And 2.38M NaBr reagent with AgI as I source
Using a (Lippmann) flow and growing at 50 ° C. for 87 minutes,
After a low concentration of iodide in the inner region of the tabular grains accounting for 75% of the total silver in the fully formed tabular grains, a nominal 12M% iodide zone was continued to give an average overall iodide content. Was about 4.5 M%.

The first 20.33 min portion of the internal region growth was performed with a pBr gradient from 1.95 to 1.7. After that, pBr was kept constant. 70% of total silver
Of 0.01 mg / Ag mol (0.2 mpp
m) K ₂ IrCl ₆ was added within 10 seconds in dilute aqueous solution and after 30 seconds 24.8 mg / Ag mol (57 m
(ppm) K ₄ Ru (CN) ₆ (SET-2) was added within 10 seconds in a dilute aqueous solution. Both dopant concentrations are based on the total silver forming tabular grains.
The introduction of other reactants was not interrupted during the addition of these dopants. 59.83 with 75% growth inside this
The whole flow rate of AgNO ₃ is 11.0 to 76.8 mL / min.
It went linearly to the minute. Last 25% of precipitation
For (based on Ag), set the silver nitrate flow rate to 1
Increased from 6.3 to 47.3 mL / min over 27.23 minutes, and the AgI flow rate was adjusted to maintain a nominal 12 M% iodide. The emulsion was subsequently washed by ultrafiltration and the pH and pBr were adjusted to storage values of 6.0 and 3.4, respectively. A total of 8 moles of silver halide was deposited.

The resulting silver iodobromide emulsion contained 4.5 M% iodide and tabular grains accounting for greater than 90% of total grain projected area. The average ECD of emulsion grains is 1.
The average thickness of the tabular grains is 0.048μ.
It was m.

Emulsion BB This emulsion was prepared the same as Emulsion AA, except that the concentration of SET-2 was increased to 82.7 mg / Ag mole based on the tabular grain emulsion silver. The grains were similar to Emulsion AA, except that the average ECD was 1.42 μm.
Met.

Emulsion CC This emulsion was prepared similarly to Emulsion AA, except that SET-2 was omitted from the precipitation. This grain is an emulsion AA
Except that the average ECD was 1.49 μm and the average grain thickness was 0.051 μm.

Epitaxially sensitized Emulsion AA, Emulsion BB and Emulsion CC were each epitaxially sensitized in the same manner, except that in the sensitization of Emulsion CC, 24.8 mg / Ag mol (57
Mppm) in the amount of the dopant K ₄ Ru (CN) ₆ (S
ET-2) was added to the epitaxy.

Each 1 mol sample was melted at 40 ° C. and its pBr adjusted to about 4 and the AgNO ₃ and KI solutions were precipitated with a small amount of 12% I silver halide. Were added at the same time. Then 2
After addition of M% NaCl, the spectral sensitizer dye 1 (0.
38 mg / Ag mol) and Dye 8 (1.5 mg / Ag mol) were added, after which the nominal (based on added amount) halide composition was 42 M% Cl, 42 M% Br and 16
M% I silver halide was added. Precipitation of silver halide epitaxy was performed by sequentially adding NaCl, NaBr, AgI (Lippmann) and AgNO ₃ . By this procedure, epitaxial growth was obtained mainly on the corners and edges of the host tabular grains. The amount of epitaxy was 6 M% of silver in the starting tabular grain emulsion.

In order to determine the optimum amount of the sensitizing component to be added after the sensitization and evaluation , the epitaxially sensitized emulsion was divided into small amounts. In addition to these ingredients, a further portion of Dye 1 and Dye 2, 60 m
g NaSCN / mol Ag, sulfur sensitizer 1, gold sensitizer 2, 8 mg APMT / mol Ag, 2.25 mg / Ag
Mole 4,4'-phenyl disulfide diacetamide and 1.97 g / Ag mol 3,5-disulfocatechol were added. After adding all ingredients, mix
15 minutes, 25 minutes or 3 at ℃, 55 ℃ and 58 ℃ respectively
The sensitization was completed by heating for 5 minutes. After cooling, 114.
4 mg APMT was added.

All samples were coated, exposed, processed and evaluated as described below. However, the following statements apply only to nearly optimally sensitized samples of each emulsion. The optimally sensitized emulsion was coated on a gray silver antihalation layer on a cellulose acetate film support, and the emulsion layer was coated with 1.75% by weight of surfactant and total gelatin weight of bis. Gelatin layer containing (vinylsulfonyl) methane hardener 1.076 g / m ²
Was overcoated. Emulsion coating amount is 0.646g A
and g / m ^2, and this layer is a coupler of the coupler 1,0.021g / m ² of 0.646g / m ² 2,5.65m
g / m ² of 5-bromo-4-hydroxy-6-methyl-
1,3,3a, 7-Tetraazaindenetriethylammonium (TEA) salt, surfactant and 2.15 total
It contained g / m ² of gelatin.

The emulsion thus coated was coated with Ratten ™.
Daylight-balanced exposure filtered through a 23A filter (> 560 nm wavelength transmission) was given through a calibrated neutral step tablet, and Kodak Flexicolo
Developed by r (R) C41 negative process.

To compare the overall speed of emulsion AA, emulsion BB and emulsion CC, development time 1.75 minutes, 2.5
Min vs. 3.25 min and 6 min obtained concentration vs. lo
The characteristic curve of the g exposure (log E, where E represents the exposure in lux-sec) was plotted. A set of three characteristic curves representative of each emulsion was selected on the basis that the lowest densities were the best in harmony. The selected characteristic curve,
The best fit (for maximum achievable overlap) was overlaid and the lateral displacement that occurred on the logE scale was taken as the speed difference.

To evaluate the reciprocity properties of the emulsions, another sample of each emulsion was exposed at 10 ^-5 seconds and 10 ^-2 seconds and 3.25.
Processed in minutes of development. The high intensity reciprocity law failure (HIRF) reported below is 0.15, 0.35,
Differences on the logE scale between the curves compared at points corresponding to 0.55, 0.75, 0.95 and 1.15 higher concentrations. Negative values indicate that the shorter the exposure time, the higher the exposure required to achieve the standard density. The results are summarized in Tables 21 and 22 below.

Table 21 Effect of SET Dopant on Ir-Doped Tabular Grains Ru (CN) ₆ (mppm) Relative Log Emulsion Host Epitaxy Speed _Dmin AA 57 0 100 0.19 BB 190 0 105 0.14 CC 0 57 108 0 .23

[0208] Table 22 Ir doped tabular HIRF the reference density on _effects, D _min SET dopants in particles (unit log speed) Emulsion 0.15 0.35 0.55 0.75 0.95 1.15 AA -4 -4 -3 -3 -8 -18 BB - 3 -4 -5 -8 -18 -19 CC -1 -1 0 -1 -1 -4

HIRF of Emulsion AA and Emulsion BB of Table 22
A large negative value indicates that the contrast in high-illuminance exposure is low. Emulsion CC shows that the combination of iridium dopant contained in the host tabular grains and SET dopant contained in the epitaxy gave the best overall speed and highest contrast. Furthermore, the amount of contrast shift as a function of the increase in exposure intensity with emulsion CC was the lowest of the three emulsions compared.

The embodiments of the present invention will be described below item by item. [1] (1) Dispersion medium, (2) (a) {111} major surface, (b) Bromide in an amount of more than 70 mol% based on silver, (c) Total grain projected area More than 90%, (d) the average equivalent circular diameter is at least 0.7 μm, (e) the average thickness is less than 0.07 μm, and (f) 1 × 10 ^-2 to 1 × 10.
Silver halide grains containing tabular grains containing an iridium dopant capable of reducing reciprocity law failure over an exposure range of ^-5 seconds and (g) having latent image-forming chemically sensitized sites on the surface; (3) An improved radiation-sensitive emulsion containing a spectral sensitizing dye adsorbed on the surface of the tabular grain, wherein the surface chemically sensitized site forms an epitaxial junction with the tabular grain. Including a silver halide protrusion, wherein the protrusion is
(A) is arranged so as to occupy at most 50% of the surface area of the tabular grain, and (b) exhibits a higher overall solubility than a portion of the tabular grain forming an epitaxial junction with at least the protrusion, (C) at least one ligand forming a face-centered cubic crystal lattice, and (d) having a higher electron-withdrawing property than fluoride ion, and Fe ⁺² , Ru ⁺² and O
A radiation-sensitive emulsion comprising a divalent Group 8 dopant selected from s ⁺² .

[2] The emulsion according to the item [1], wherein the protrusion has a chloride concentration higher than that of the tabular grains by 10 mol% or more. [3] The emulsion according to item [2], wherein the protrusions have a chloride concentration higher than that of the tabular grains by 20 mol% or more. [4] The emulsion according to any one of [1] to [3], wherein the epitaxially deposited silver halide protrusions are arranged in less than 25% of the tabular grain surface.

[5] The emulsion according to the item [4], wherein the silver halide protrusions epitaxially deposited are arranged mainly in the vicinity of at least one of the edge and the corner of the tabular grain. [6] The coordination complex dopant contains Os ⁺² and at least one cyano ligand, [1] to
The emulsion according to any one of [5]. [7] The coordinating complex dopant contains Ru ⁺² or Os ⁺² and at least three cyano ligands, [1] to any one of [5], emulsion. [8] The coordination complex dopant is Fe ⁺² , Ru ⁺² or O
The emulsion according to any one of items [1] to [5], which contains s ⁺² and at least 5 cyano ligands.

[0213]

[9] The iridium dopant is present in the area of tabular grains formed after the first 20% of the silver forming the tabular grains has been deposited and before the last 10% of the silver has been deposited. The emulsion according to any one of [1] to [8]. [10] The average thickness of the tabular grains is 0.04 μm.
Further characterized by the following, [1]-

The emulsion according to any one of the items [9]. [11] A support, and coating on the support to give 500 to 7
Minus blue of 00 nm Specular minus blue for the purpose of exposing the first silver halide emulsion layer and the first silver halide emulsion layer sensitized so as to produce photographic recording when exposed to specular light in the visible wavelength range A second silver halide emulsion layer capable of producing a second photographic record coated on a first light-sensitive silver halide emulsion layer for the purpose of exposing the first silver halide emulsion in the form of specular light. And a second silver halide emulsion layer capable of functioning as a transmission medium for delivering at least a portion of the minus blue light, wherein the second silver halide emulsion layer is [1] to [10]. ] A photographic element further characterized in that it comprises an improved emulsion according to any one of paragraphs.

 ─────────────────────────────────────────────────── --Continued from the front page (31) Priority claim number 359251 (32) Priority date December 19, 1994 (33) Priority claim country United States (US) (31) Priority claim number 441489 (32) Priority date May 15, 1995 (33) Priority claim United States (US) (72) Inventor Joseph Charles Deaton United States, New York 14617, Rochester, Nob Hill 37 (72) Inventor Timothy Richard Jersey United States, New York 14609, Rochester, Alford Street 53 (72) Inventor Joseph George Lighthouse USA, New York 14626, Rochester, Countryshire Drive 133 (72) Inventor Miratoforon Orm United States, New York York 14580, Webster, Wycliffe Drive 181 (72) Inventor Shin Wen United States, New York 14618, Rochester, Tillstone Place 70 (72) Inventor Robert Don Wilson United States, New York 14612, Rochester, Seafarers Lane 133

Claims (2)

[Claims] 1. A dispersion medium, (2) (a) having a {111} major surface, (b) containing bromide in an amount of more than 70 mol% based on silver, and (c) all particles. Occupies more than 90% of the projected area, (d) the average equivalent circular diameter is at least 0.7 μm, (e) the average thickness is less than 0.07 μm, and (f) 1 × 10 ^-2 to 1 × 10
Silver halide grains containing tabular grains containing an iridium dopant capable of reducing reciprocity law failure over an exposure range of ^-5 seconds and (g) having latent image-forming chemically sensitized sites on the surface; (3) An improved radiation-sensitive emulsion containing a spectral sensitizing dye adsorbed on the surface of the tabular grains, wherein the surface chemically sensitized site forms an epitaxial junction with the tabular grains. Including a silver halide protrusion, wherein the protrusion has a surface area of the tabular grain of at most 5
Is arranged so as to occupy 0%, and (b) shows a higher overall solubility than at least a portion of the tabular grain forming an epitaxial junction with the protrusion, and (c) forms a face-centered cubic crystal lattice, And (d) at least one ligand having a higher electron-withdrawing property than fluoride ion and Fe ⁺² ,
A radiation-sensitive emulsion comprising a divalent Group 8 dopant selected from Ru ⁺² and Os ⁺² . 2. A support and a first silver halide emulsion coated on the support and sensitized to produce a photographic record when exposed to specular light in the minus blue visible wavelength range of 500 to 700 nm. Layer and a second silver halide emulsion layer capable of producing a second photographic record coated on the first silver halide emulsion layer which receives specular minus blue light for the purpose of exposing the first silver halide emulsion layer. And a second silver halide emulsion layer capable of functioning as a transmission medium for delivery of at least part of minus blue light for the purpose of exposing the first silver halide emulsion in the form of specular light. A photographic element, further comprising, wherein said second silver halide emulsion layer comprises the improved emulsion of claim 1.