JPH07168295A - Silver halide photosensitive material - Google Patents

Abstract

PURPOSE:To produce the subject material high in sensitivity and excellent in pressure resistance. CONSTITUTION:(1) The subject material is incorporated with silver halide particles having >=1.5mol% average content of silver iodide in a vicinity of the outmost surface of the silver halide particles, two sheets of parallel twin crystal face and an average aspect ratio of less than 2. (2) The subject material is incorporated with the silver halide particles having <=2.0mol% average content of silver iodide and a silver halide phase having >=5mol% silver iodide content at the inside of the particles.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a silver halide emulsion having improved sensitivity and pressure resistance and a silver halide photographic light-sensitive material using the same.

[0002]

2. Description of the Related Art In recent years, with silver halide photographic light-sensitive materials, rapid processing by an automatic processor has become widespread, and as a result, there are many opportunities to apply mechanical pressure to the film.

Mechanical pressure is generated, for example, by the film transport roller in the developing machine. Further, in a sheet-like film for direct radiography, since a person directly handles it by hand, it is often bent or bent. Thus, when various pressures are applied to the light-sensitive material, pressure is applied to the silver halide grains using gelatin or a support as a medium. It is known that a stress is applied to the silver halide grains to cause a change in photographic performance. For example, streaky or dot-like fog appears on the film after development.

In a light-sensitive material for medical use, such a phenomenon is not only a hindrance in image diagnosis but also a risk of inducing a misdiagnosis, which is a very serious problem.

Many proposals have hitherto been made as a method for improving the pressure resistance of a light-sensitive material. For example, a method of increasing the amount of binder to silver in the light-sensitive material, a method of using polymer latex, etc. are well known. ing.

However, when the amount of binder such as gelatin is increased, the developability is remarkably deteriorated, and it is impossible to obtain high sensitivity by rapid processing. Further, the use of polymer latex has a drawback that the films are easily stuck to each other, which causes a problem that two or more films are stuck and conveyed during automatic conveyance.

It is also well known that an inorganic substance system such as colloidal silica is added to the light-sensitive material constituting layer to improve pressure resistance and sticking. However, there is a problem that unfixed residual silver is generated in the film when the development processing is performed. Especially in medical light-sensitive materials for which it is necessary to know the diagnosis as quickly as possible, the generation of residual silver is increasing more and more because of the ultra-rapid processing.
Upon storage, the color changes to a yellowish silver image. Therefore, there are drawbacks such as impeding accurate diagnosis of the image observer and causing discomfort.

On the other hand, in the background of a demand for higher sensitivity and higher sharpness for silver halide photographic light-sensitive materials, in recent years, a silver halide grain having a large aspect ratio (diameter / thickness ratio) has a tabular shape. The particles are, for example, U.S. Pat.
No. 1-14636, No. 61-112142, etc.

However, tabular grains having a large aspect ratio are remarkably weak against external force due to their shape, as compared with ordinary silver halide grains such as hexahedron, octahedron, or potato type, and are conventionally known. It was difficult to obtain a satisfactory pressure resistance by the above method alone. Therefore, development of a silver halide photographic light-sensitive material having high sensitivity, high sharpness and excellent pressure resistance has been strongly desired.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a silver halide photographic light-sensitive material having high sensitivity and excellent pressure resistance.

[0011]

The above problems have been solved by the present invention described below.

(1) Silver halide grains having an average silver iodide content in the vicinity of the outermost surface of the silver halide grains of 1.5 mol% or more and having two parallel twin planes and an average aspect ratio of less than 2. A silver halide photographic light-sensitive material comprising:

(2) Halogen in which the average silver iodide content of silver halide grains is 2.0 mol% or less and a silver halide phase having a silver iodide content of 5 mol% or more is present inside the grains. The silver halide photographic light-sensitive material according to item (1), which contains silver halide grains.

The present invention will be described in detail below.

The silver halide grains used in the silver halide emulsion of the present invention are twinned silver halide grains having an average aspect ratio of less than 2 having two twin planes in which 50% or more of the total projected area are parallel. is there.

A twin is a silver halide crystal having one or more twin planes in one grain, and the morphology of twins is classified by Klein and Moiser in a report by Photographie Schér.
Correspondents (Photographisches Korrespondenz) 99
Volume 99 pages, Volume 100 pages 57.

The twin plane can be observed with a transmission electron microscope. Specifically, a sample is prepared by coating a silver halide emulsion on a support so that the principal planes of tabular silver halide grains are oriented substantially parallel to the support. This is cut with a diamond cutter to obtain a thin section with a thickness of about 1.1 μm. The presence of twin planes can be confirmed by observing this section with a transmission electron microscope.

The average grain size of the tabular silver halide grains in the present invention is preferably 0.1 μm or more and 5.0 μm or less, more preferably 0.2 μm to 3.0 μm. Most preferably 0.3 μm
~ 2.0 μm.

In the present invention, the average particle diameter is defined as the particle diameter ri when the frequency ni and ri ³ of the particles having the particle diameter ri becomes ni × ri ³ maximum. (Three significant digits and the least significant digit are rounded off.) The number of measured particles is indiscriminately 1.000 or more.

In the case of tabular silver halide grains, the grain size ri mentioned here is the diameter of a projected image when viewed from a direction perpendicular to the principal plane and converted into a circular image of the same area. For grains other than tabular silver halide grains, it is the diameter when a projected image of the silver halide grains is converted into a circular image having the same area.

The particle size ri is 10,000 to 7 as measured by an electron microscope.
It can be obtained by taking a magnified image of 10,000 times and measuring the particle diameter on the print or the area at the time of projection.

The tabular silver halide grains according to the present invention are
Although it may be polydisperse having a wide grain size distribution or monodisperse having a narrow grain distribution, it is preferably a monodisperse emulsion. The monodisperse emulsion has a distribution of 20% or less, preferably 15% or less.

The average silver iodide content of the silver halide emulsion according to the present invention is preferably 2 mol% or less. The average silver iodide content can be determined by a fluorescent X-ray analysis method.

The silver halide grains of the present invention preferably have a silver halide phase having a silver iodide content of 5 mol% or more and a solid solution limit or less inside the grain. In the present invention, the inside of the grain is inside the grain corresponding to 90% by volume of silver halide, preferably inside 80%, more preferably inside 70%.

In the silver halide emulsion of the present invention, as the silver halide, silver halide grains such as silver iodobromide, silver iodochloride, silver chloroiodobromide and silver chloride can be optionally used. It is preferably silver bromide or silver chloroiodobromide.

The silver halide grains contained in the silver halide emulsion of the present invention may be so-called core / shell type grains in which silver iodide is concentrated. The core / shell type particle is a particle composed of a core that serves as a core and a shell that covers the core, and the shell is formed by one layer or more layers. It is preferable that the core and the shell have different silver iodide contents. The silver iodide content of the core is preferably 5 mol% or more and not more than the solid solution limit, and the silver iodide content of the shell is preferably less than 5 mol%, more preferably 2 mol% or less. The ratio of the core is preferably 2 to 60% of the total volume of the particles, more preferably 5 to 50%.

In the present invention, the above solid solution limit is the maximum mol% of iodide which can exist as a solid solution in silver halide.
Indicated by. Specifically, “The Theory of t” by TH James
he Photographic process ”4th edition, published by Macmillan (1977
Year) page 4 and in the case of silver iodobromide, it can be calculated as follows.

Imax (mol%) = 34.5 + 0.165 (t-25)
(T is degrees Celsius) In the present invention, the presence of a silver halide phase having a silver iodide content of 5 mol% or more and a solid solubility limit or less can be confirmed by the method described below. .

That is, silver halide grains are dispersed in a methacrylic resin and solidified in the same manner as in the method shown in the abstracts of Inoue et al. Focus on the sliced sample with the maximum cross-sectional area or a cross-sectional area of 90% or more, and draw from the center of the circle to the outer circumference when drawing the minimum circumscribed circle for that cross-section. The silver iodide content structure can be determined by measuring the silver iodide content and position on the straight line by the XMA method.

In the XMA method (X-ray Micro Analysis), silver halide grains are dispersed in an observation grid in which an energy dispersive X-ray analyzer is loaded in an electron microscope, and I particles are cooled by liquid nitrogen to display a CRT field of view. The magnification is set so as to enter, and the intensities of AgLα and ILα rays are integrated for a certain period of time. I
The intensity ratio of Lα / AgLα can be prepared in advance and the silver iodide content can be calculated using a calibration curve.

The average silver iodide content in the vicinity of the outermost surface of the silver halide grain in the present invention is 1.5 mol% or more. The vicinity of the outermost surface as used herein means the halogenation present in the region where X-rays penetrate from the surface of the silver halide grain and reach when the average silver iodide content on the surface of the silver halide grain is measured by the XPS method. It means a silver phase, and usually corresponds to a region of about 50Å including the grain surface in the outermost layer constituting the silver halide grain.

The average silver iodide content in the vicinity of the outermost surface of the silver halide grains in the present invention is XPS when a sample prepared from the silver halide grains is cooled to -110 ° C or lower.
It is the value measured using the method.

Conventionally, the XPS method known in the art is usually measured at room temperature. However, according to the study by the present inventors, the average iodide in the vicinity of the outermost surface of silver halide grains was measured by the XPS method at room temperature. When the silver content was measured, the silver halide sample was largely destroyed by X-ray irradiation, and the obtained data cannot be said to accurately indicate the average silver iodide content near the outermost surface of the silver halide grain. There was found.

In particular, a high silver iodide-containing phase and a low silver iodide-containing phase are localized in the outermost surface of silver halide grains having different silver halide compositions between the surface and inside of the grain such as core / shell type grains. It has been revealed that the measured values of the silver halide grains are different from the true composition due to decomposition of the silver halide by X-ray irradiation and diffusion of halide (particularly iodine). According to a further study by the present inventors, in order to avoid such destruction of the sample and obtain the average silver iodide content in the vicinity of the outermost surface of the silver halide grain accurately and with good reproducibility, the sample should be destroyed. It has been found that the sample may be cooled to a temperature at which it rarely occurs, specifically, the sample may be cooled to −110 ° C. or lower.

The XPS method used here is as follows.

A 0.05% by weight aqueous solution of pronase (proteolytic enzyme) is added to the emulsion, and gelatin is decomposed while stirring at 45 ° C. for 30 minutes. Next, the emulsion particles are settled by centrifugation and the supernatant liquid is removed. Then, distilled water is added to disperse the emulsion particles in distilled water, and the mixture is centrifuged to remove the supernatant liquid. The emulsion particles are then redispersed in distilled water. This is thinly applied on a mirror-polished silicon wafer to obtain a measurement sample.

Using the sample thus prepared, XP
The average silver iodide content in the vicinity of the outermost surface of silver halide grains was measured by the S method. In order to prevent the sample from being destroyed by the above-mentioned X-ray irradiation, the sample was cooled to −110 ° C. to −120 ° C. using liquid nitrogen or liquid helium in the XPS measurement chamber. As the probe X-ray, Mg-Kα ray was irradiated at an X-ray source voltage of 13 KV and an X-ray source current of 40 mA.

Ag3d, Br3d, and I3d 3 were used to determine the surface halide composition near the outermost surface of the silver halide grain.
/ 2 electrons were detected. The composition ratio was calculated by correcting the integrated intensity of each measured peak with a sensitivity factor (Sensitivity Factor), and calculating the average silver iodide content near the outermost surface of the silver halide grain from these intensity ratios.

The emulsion used in the silver halide photographic light-sensitive material of the present invention can be prepared by various methods well known in the art. That is, the single jet method, the double jet method, the triple jet method and the like can be used in any combination. It is also possible to use a method of controlling pH and pAg in the liquid phase in which silver halide is produced in accordance with the growth rate of silver halide. In the production of the silver halide emulsion according to the present invention, the halide ion and the silver ion may be mixed at the same time, or the other may be mixed while the one is present. Also, considering the critical growth rate of silver halide crystals,
Further, halide ions and silver ions can be added sequentially or simultaneously by controlling the pH and pAg in the mixing vessel. A conversion method may be used in the step of forming silver halide grains to change the silver halide composition of the grains.

In the process for producing the silver halide emulsion of the present invention, a known silver halide solvent such as ammonia, thioether, thiourea or the like can be present.

In the process for producing the silver halide emulsion of the present invention, the halogenation contained in the silver halide emulsion is supplied by supplying fine silver halide grains having an average silver iodide content of 2 mol% or more before desalting. It can be prepared by forming at least a part of the outermost silver halide phase of the silver grain and the outermost shell layer. The above-mentioned production steps include the steps from nucleation to growth of the silver halide grains, and from seed grains when a seed grain is used, to a desalting step, a silver halide grain dispersion step, and chemical sensitization. And the spectral sensitization step are not included, and the coating liquid preparation step and the manufacturing steps after the coating step are not included.

The above silver halide fine particles may be prepared in advance prior to the preparation of the silver halide grains according to the present invention, or may be prepared in parallel. When prepared in parallel, as described in JP-A 1-183417, 2-24335, etc., the silver halide fine particles are mixed separately provided outside the reaction vessel in which the silver halide grains are formed. Although it is possible to use a method of preparation using a vessel, it is desirable to provide an adjusting container after forming the fine particles, and to supply the fine particle emulsion to the reaction container while adjusting it according to the growth environment in the reaction container.

As a method of producing the silver halide fine grains, a method of forming grains in an acidic or neutral environment (pH≤7) is desirable. In the method for producing fine silver halide grains, a water-soluble silver salt containing silver ions and a water-soluble alkali halide containing halide ions may be mixed while appropriately controlling the supersaturation factor. Regarding the control of supersaturation factors, JP-A-63-92942, 63-92942 and 63-3
The method described in No. 11244 can be referred to.

The pAg forming the silver halide fine grains is preferably 3.0 or more, more preferably 5.0 or more, and further preferably 8.0 or more in order to suppress the generation of reduced silver nuclei in the silver halide fine grains themselves. Is. The temperature for forming the fine silver halide grains is preferably 50 ° C. or lower, preferably 40 ° C. or lower, and more preferably 35 ° C. or lower. Ordinary high molecular gelatin can be used as a protective colloid for forming fine silver halide grains.

When the silver halide fine grains are formed at a low temperature, the progress of Ostwald ripening after the formation of the silver halide fine grains can be further suppressed, but gelatin is likely to coagulate at a low temperature. Kaihei 2-1664
It is preferable to use the low molecular weight gelatin described in No. 42, a synthetic polymer compound having a protective colloid action on silver halide fine particles, or a natural polymer compound other than gelatin. The concentration of the protective colloid is preferably 1% by weight or more, more preferably 2% by weight or more, further preferably 3% by weight or more.

The silver halide fine grains supplied to the aqueous solution containing the protective colloid for forming the silver halide grains according to the present invention grows the silver halide grains by the Ostwald ripening effect. Since the fine silver halide grains have a fine grain size, they are easily dissolved and become silver ions and halide ions again to cause uniform growth.

The grain size of the silver halide fine grains used in the present invention is preferably 0.1 μm or less, more preferably 0.05 μm or less.

In the present invention, in order to form at least a part of the outermost silver halide phase and the outermost shell layer of silver halide grains by using fine silver halide grains, the silver halide grains are protected after desalting. A method of dispersing in an aqueous solution containing a colloid and adding the silver halide fine particles is preferably used.

The fine silver halide grains may be added by funnel addition or function addition using a pump or the like.
It may be added dividedly more than once, and after the addition of silver halide fine grains, ripening may be carried out if necessary.

In the present invention, the aqueous solution containing protective colloid means that the protective colloid is formed in the aqueous solution by gelatin or other substance capable of forming hydrophilic colloid, and preferably the aqueous solution containing colloidal protective gelatin. Say

When forming the outermost silver halide phase of the silver halide grains and at least a part of the outermost shell layer in the present invention, the temperature of the aqueous solution containing the protective colloid in which the silver halide grains are dispersed is 40 C. to 80.degree. C. is preferable, and 50.degree. C. to 70.degree. C. is more preferable. The pH is 2-10, more preferably 4-8. pBr is 0.2 to 3.5, more preferably 0.5 to 2.5. It is preferable not to add a silver halide solvent.

An aqueous solution containing a water-soluble silver salt, a water-soluble halide or a protective colloid can be added before, during or after the addition of the fine silver halide grains, but the addition and ripening of the silver halide grains can be carried out. It is preferable not to add an aqueous solution of silver salt or a water-soluble halide during the heating.

In the present invention, the outermost silver halide phase of a silver halide grain refers to a portion of the silver halide phase from the surface of the silver halide grain to the depth of 50Å from the surface toward the center of the grain.

In the present invention, at least a part of the outermost silver halide phase of the silver halide grains and the outermost shell layer is formed by supplying the above-mentioned silver halide fine grains, Can be confirmed by observing the particle size of the silver halide grains with an electron microscope before the supply of the silver halide grains or after the growth of the silver halide grains by supplying the silver halide fine grains.

The outermost shell layer in the present invention is a silver halide region that occupies 20% of the volume of the silver halide grain from the surface of the silver halide grain toward the center of the grain, and is the outermost halogen described above. Including silver halide phase.

In the production of the silver halide emulsion according to the present invention, conditions other than those mentioned above are described in, for example, JP-A-61-6643.
No. 61, No. 61-14630, No. 61-112142, No. 62-157024,
62-18556, 63-92942, 63-151618, 63-1634
The optimum conditions can be selected with reference to No. 51, No. 63-220238 and No. 63-311244.

The emulsion used in the silver halide photographic light-sensitive material of the present invention can use various photographic additives in the steps before and after physical ripening or chemical ripening.

Examples of the compound used in such a process include Research Disclosure (RD) No.176.
Various compounds described in No. 43, No. 18716 and No. 308119 (December 1989) can be used. These 3
The types and locations of the compounds listed in item (RD) are listed below.

Additive RD-17643 RD-18716 RD-308119 Page Classification Page Page Classification Chemical sensitizer 23 III 648 Upper right 996 III Sensitizing dye 23 IV 648-649 996-8 IVA Desensitizing dye 23 IV 998 IVB Dye 25 ~ 26 VIII 649 ~ 650 1003 VIII Development accelerator 29 XXI 648 Upper right fog inhibitor / stabilizer 24 IV 649 Upper right 1006-7 VI Whitening agent 24 V 998 V Hardener 26 X 651 Left 1004-5 X Surfactant 26-27 XI 650 Right 1005-6 XI Plasticizer 27 XII 650 Right 1006 XII Sliding Agent 27 XII Matting Agent 28 XVI 650 Right 1008-9 XVI Binder 26 XXII 1003-4 IX Support 28 XVII 1009 XVII Halogenation of the Invention Examples of the support used for the silver photographic light-sensitive material include those described in RD above,
A suitable support is polyethylene terephthalate or the like, and the surface of the support may be provided with an undercoat layer to improve the adhesiveness of the coating layer, or may be subjected to corona discharge or ultraviolet irradiation.

In the photographic processing of the light-sensitive material of the present invention, it is preferable that all steps from development, fixing, washing (or stabilization) and drying be completed within 90 seconds.

[0061]

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

Example 1 <Preparation of Twin Crystal Emulsion T-1> By the following method.
A seed emulsion T-1 having two parallel twin planes was prepared.

[0063] A ossein gelatin 80.0 g HO- [CH ₂ CH ₂ O] _m - [CH (CH ₃₎ -CH ₂ O] ₁₇ - [CH ₂ CH ₂ O] _{n -OH (m + n ≒ 5.7} ) MW1700 (10% methanol solution) 0.48ml KBr 47.4g Pure water 8000ml B Silver nitrate 1200g Pure water 1600ml C Ocein gelatin 32.2g KBr 823.5g KI 23.45g Pure water 1600ml D Ammonia water 470ml A stirred vigorously at 40 ℃ A Liquid B and liquid C were added to the liquid by the double jet method over 7.7 minutes to generate nuclei. During this period, pBr was kept at 1.60. Then heat it to 23 for 30 minutes.
Lowered to ℃. Further, add D solution in 1 minute, and continue to 5
Aged for a minute. KBr concentration during aging is 0.03 mol /
The liter and the ammonia concentration were 0.66 mol / liter.

After the ripening, the pH was adjusted to 6.00, and desalting was carried out using an aqueous solution of Demol N (manufactured by Kao Atlas) and an aqueous solution of magnesium sulfate.

When the seed emulsion grains were observed with an electron microscope, they were grains having two twin planes parallel to each other. The average particle diameter of the grains was 0.236 μm, and the ratio of the parallel twin planes of the two grains was 75% in terms of the number of all grains.

<Preparation of Emulsion Em-1 of the Present Invention> A monodisperse emulsion Em-1 having two parallel twin planes was prepared using the following seven kinds of solutions.

[0067] A1 ossein gelatin 61.0 g HO- [CH ₂ CH ₂ O] _m - [CH (CH ₃₎ -CH ₂ O] ₁₇ - [CH ₂ CH ₂ O] _{n -OH (m + n ≒ 5.7} ) MW1700 (10% methanol solution) 2.5 ml Pure water 1963.0 ml Seed emulsion (T-1) 0.343 mol 28 wt% ammonia solution 308.0 ml 56 wt% acetic acid solution 358.0 ml Make pure water 3500.0 ml B1 3.5N ammoniacal silver nitrate solution (However, adjust the pH to 0.9 with ammonium nitrate) 4877.0 ml C1 3.5N KBr aqueous solution 4877.0 ml D1 Fine grain emulsion consisting of 3 wt% gelatin and silver iodide grains (average grain size 0.05 μm) 0.247 mol Preparation of fine grain emulsion The method is shown below.

6.0% by weight containing 0.06 mol of potassium iodide
2000 ml of an aqueous solution containing 7.06 mol of silver nitrate and 7.06 mol of potassium iodide were added to 5000 ml of the gelatin solution of (2) over 10 minutes. The pH during fine particle formation was controlled to 2.0 using nitric acid, and the temperature was controlled to 40 ° C. After forming the grains, the pH was adjusted to 6.0 using an aqueous sodium carbonate solution to give a fine grain emulsion.

E1 A fine grain emulsion consisting of silver iodobromide grains (average grain size 0.04 μm) containing 2 mol% of silver iodide prepared in the same manner as the silver iodide fine grain emulsion layer of solution D3. The temperature inside was controlled at 30 ° C.

F1 1.75N KBr aqueous solution G1 56% by weight acetic acid aqueous solution Solution A1 kept at 70 ° C. in the reaction vessel was added to solutions B1 and C1.
And D1 were added by the simultaneous mixing method over 128 minutes, and then the solution E1 was independently added at a constant rate over 7 minutes to grow a seed crystal to 0.88 μm.

Here, the addition rates of the solutions B1 and C1 are
The amount was changed functionally with respect to the time so as to be commensurate with the critical growth rate, and was added at an appropriate addition rate so as not to cause polydispersion due to generation of small particles other than growing seed crystals and Ostwald ripening. The solution D1 solution, that is, the silver iodide fine grain emulsion is supplied by changing the rate ratio (molar ratio) with the ammoniacal silver nitrate aqueous solution (B1 solution) with respect to the particle size (addition time). A shell type silver halide emulsion was prepared.

By using solutions F1 and G1, pAg and pH during crystal growth were controlled to 7.8 and 9.0, respectively. Incidentally, pAg and pH were measured by using a silver sulfide electrode and a glass electrode according to a conventional method.

After grain formation, desalting was carried out in the same manner as in the above seed emulsion, and then gelatin was added to redisperse the mixture at 40 ° C.
Was adjusted to 5.8 and pAg was adjusted to 8.55. Observation of the obtained emulsion grains by a scanning electron microscope revealed that they were twinned hexahedral grains with an average grain size of 0.878 μm and a distribution width of 12.0%.
95% was 2.0% or less, and the number average of individual aspect ratios (hereinafter, referred to as average aspect ratio) was 1.6.

<Preparation of Comparative Emulsion Em-2> Emulsion Em-1
A hexahedral twin monodisperse emulsion Em-2 having two parallel twin planes was prepared using the solution shown below according to the preparation method of 1.

[0075] A2 ossein gelatin 42.7 g HO- [CH ₂ CH ₂ O] _m - [CH (CH ₃₎ -CH ₂ O] ₁₇ - [CH ₂ CH ₂ O] _{n -OH (m + n ≒ 5.7} ) MW1700 (10% methanol solution) 3.0 ml Seed emulsion (T-1) 0.293 mol 28% by weight aqueous ammonia solution 369.6 ml 56% by weight aqueous acetic acid solution 90.0 ml Make pure water 3600.0 ml B2 3.5N ammoniacal silver nitrate aqueous solution 5903.0 ml C2 0.5 4.25N KBr aqueous solution containing 4% by weight of gelatin 4861.3 ml D2 Fine grain emulsion consisting of 3% by weight of gelatin and silver iodide grains (average grain size of 0.05 μm) 0.215 mol E2 3.5N KBr aqueous solution F2 56% by weight of silver potential control below Aqueous acetic acid solution At the following pH controlled amount of 45 ° C, solution A2 was added to solution B2, solution C2 and solution D.
Seed crystals were grown to 1.0 μm by the addition of 2 by the double-mix method over a period of 235 minutes.

Here, the addition rates of the B2, C2, and D2 solutions were changed functionally with respect to time so as to correspond to the critical growth rate, and the generation of small particles other than the growing seed crystal and the aging of Ostwald ripening caused a large amount. It was added at an appropriate addition rate so as not to disperse. D2 liquid, that is, the supply of silver iodide fine particles,
A core / shell type silver halide emulsion having a multiple structure was prepared by changing the rate ratio (molar ratio) with the B2 solution, that is, the aqueous solution of ammoniacal silver nitrate with respect to the grain size (addition time) as shown in Table 1. did.

Further, by using E2 solution and F2 solution, pAg and pH during crystal growth were controlled as shown in Table 1 below.

[0078]

[Table 1]

Further, desalting treatment was carried out in the same manner as in the seed emulsion. When observed with an electron microscope, the grains were twinned hexahedral grains having an average grain size of 1.0 μm and an average aspect ratio of 1.1. This emulsion was designated as Em-2.

<Preparation of Emulsion Em-3 of the Present Invention> Emulsion Em-
In the preparation method of No.2, 0.254
All except for the addition of moles over a period of 30 seconds
In the same manner as in Example 2, a hexahedral twin emulsion Em-3 having an average grain size of 1.01 μm and an average aspect ratio of 1.1 and having two parallel twin planes was prepared.

<Preparation of Comparative Emulsion Em-4> Emulsion Em-2
The same procedure as in Em-1 except that the seed emulsion is a normal crystal tetradecahedral monodisperse emulsion having an average grain size of 0.230 μm and containing 2.0 mol% of silver iodide. A normal crystal hexahedral emulsion Em-4 having a grain size of 0.96 μm was prepared.

<Preparation of Comparative Emulsion Em-5> Emulsion Em-3
In the same manner as the above, the seed emulsion was a normal tetradecahedral monodisperse emulsion containing 2.0 mol% of silver iodide and having an average grain size of 0.230 μm.
A normal crystal hexahedral emulsion Em-5 having an average grain size of 0.97 μm was prepared.

<Preparation of Twin Crystal Emulsion T-2> A seed emulsion made of silver iodobromide was prepared using the following solution.

[A ₁ ] Hydrogen peroxide treated ossein gelatin 40 g Potassium bromide 75.1 g Water added 4000 ml [B ₁ ] Silver nitrate 600 g Water added 803 ml [C ₁ ] Hydrogen peroxide treated ossein gelatin 16.1 g Potassium bromide 393.7 g Potassium iodide 35.1 g Water added 803 ml [D ₁ ] Ammonia water (28%) 235 ml Using the apparatus disclosed in Japanese Patent Laid-Open No. 62-160128, to the lower part of the stirring impeller for mixing. The supply nozzle for the solution [B ₁ ]
For the solution [C ₁ ], 6 pieces were installed each.

The solution [B ₁ ] and the solution [C ₁ ] were added to the solution [A ₁ ] stirred at a temperature of 40 ° C. and a rotation speed of 430 rpm at a high speed by a controlled double jet method at a flow rate of 62.8 ml / min. did. The flow rate was gradually increased from 4 minutes and 46 seconds after the start of the addition so that the final flow rate was 105 ml / min. The total addition time was 10 minutes 45 seconds. The pBr during addition was kept at 1.3 with potassium bromide solution (3.5N).

After the addition was completed, the temperature of the mixed solution was changed to 20 ° C. for 10 minutes.
And the stirring speed was 460 rpm, and the solution [D
₁ ] was added for 20 seconds, and Ostwald ripening was performed for 5 minutes. During aging, the bromine ion concentration was 0.025 mol / l, the ammonia concentration was 0.63 mol / l, and the pH was 11.7.

Immediately thereafter, acetic acid was added until the pH became 5.6 to neutralize the mixture to stop ripening, and in order to remove excess salts, desalting was performed using an aqueous solution of Demol N (manufactured by Kao Atlas) and an aqueous solution of magnesium sulfate. Seed emulsion T-2 after washing with water
Got

Observation of T-2 with an electron microscope revealed that the particles were spherical particles having an average particle size of 0.28 μm and a particle size variation coefficient of 21%.

<Preparation of Comparative Emulsion Em-6> The obtained seed emulsion T-2 was used in an amount of 0.027 per mol of silver halide in the growing emulsion.
A molar equivalent thereof was taken and dissolved and dispersed in a gelatin aqueous solution at 62 ° C. containing a copolymer of polypropylene oxide (PO) and polyethylene oxide (EO) (EO / PO = 0.33, molecular weight = 1400) as an antifoaming agent. Subsequently, 3.5N silver nitrate aqueous solution and 3.4N potassium bromide aqueous solution were controlled.
The addition was performed by the double jet method over 85 minutes so that the addition rate at the end of addition was 2.5 times that at the start of addition. still,
The temperature was kept at 70 ° C., pH = 5.8, and pHAg = 8.5 all the time. Further, desalting treatment was carried out in the same manner as in the seed emulsion. The resulting emulsion has an average grain size of 1.15 μm, an average thickness of 0.32 μm, and an average aspect ratio of 3.
It was a tabular silver halide emulsion of No. 6. Em this emulsion
It was set to -6.

<Preparation of Emulsion Em-7> After grain growth of Em-6, E1 used in Em-1 was added over 30 seconds to obtain Em-7. The characteristics of Em-1 to Em-7 are shown in Table 2 below.

[0091]

[Table 2]

(Chemical Sensitization of Emulsion) Obtained Em-1 to E
While maintaining m-7 with stirring at 52 ° C., as a chemical sensitizer, 60 mg of ammonium thiocyanate per mol of silver and chloroauric acid were used.
1.45 mg and sodium thiosulfate 13.8 mg were added, respectively. After a certain period of time 4-hydroxy-6-methyl-1,3,3
Stabilization was performed by adding a, 7-tetrazaindene and 1-phenyl-5-mercaptotetrazole, and each was chemically sensitized optimally. The obtained emulsions were named Em-A to Em-G.

The resulting chemically ripened emulsion Em-A-
Em-G was added to the additives described below to prepare an emulsion layer coating solution.
At the same time, a protective layer coating solution described below was also prepared. The coating amount was 2.5 g / m ^{2 on} one side and 1.85 with gelatin.
Two slide hopper type coaters were used at a speed of 80 m / min so that both sides were simultaneously coated on the support at a speed of g / m ² and dried in 2 minutes and 20 seconds.
Got 7. Glycidyl methacrylate 50 as a support
The concentration of the copolymer composed of three kinds of monomers of 10% by weight, 10% by weight of methyl acrylate and 40% by weight of butyl methacrylate is 10% by weight.
A polyethylene terephthalate film base colored blue with a concentration of 0.15 for an X-ray film of 175 μm was used as an undercoating solution of the copolymer aqueous dispersion obtained by diluting the resulting copolymer to a concentration of 0.1%.

The additives used in the emulsion are as follows.
The addition amount is indicated by the amount per mol of silver halide.

1,1-Dimethylol-1-bromo-1-nitromethane 70 mg t-butyl-catechol 82 mg Polyvinylpyrrolidone (molecular weight 10,000) 1.0 g Styrene-maleic anhydride copolymer 25 g Nitrophenyl-triphenylphosphonium chloride 50 mg 1, Ammonium 3-dihydroxybenzene-4-sulfonate 2.0 g 2-Mercaptobenzimidazole-5-sulfonate sodium 1.5 mg

[0096]

[Chemical 1]

C ₄ H ₉ OCH ₂ CH (OH) CH ₂ N (CH ₂ COOH) ₂ 1 g 1-phenyl-5-mercaptotetrazole 15 mg diethylene glycol 7 g dextran (average molecular weight 60,000) 600 mg sodium polyacrylate (average molecular weight 3.6 2.5 g Next, the following was prepared as a protective layer coating liquid. The additive is shown in the amount per liter of coating liquid.

Lime-treated inert gelatin 68 g Acid-treated gelatin 2 g Sodium-i-amyl-n-decylsulfosuccinate 0.3 g Polymethylmethacrylate (matting agent having an area average particle size of 3.5 μm) 1.1 g Silicon dioxide particles (area average particle size) Matte agent of 1.2 μm) 0.5 g Ludox AM (made by DuPont) (colloidal silica) 30 g (CH ₂ = CHSO ₂ CH ₂ ) ₂ O (hardener) 200 mg Glyoxal 40% aqueous solution (hardener) 2.0 ml

[0099]

[Chemical 2]

Sensitometry (evaluation of photographic performance) In sensitometry, a sample was sandwiched between two intensifying screens (NR-160 Konica Corporation), and a tube voltage of 80 was applied through an aluminum wedge.
Irradiation with X-ray for 0.05 seconds at kvp, tube current 50 mA. Next, using a roller-conveying type automatic developing machine, development and fixing were performed with the developing solution and fixing solution shown below.

The processing time was dry to dry for 90 seconds to obtain the sensitivity. The temperature during processing is 32 ° C for development and 33 for fixing.
C., washed with water at 20.degree. C., and dried at 50.degree. Sensitivity is fog +
It was expressed by the reciprocal of the exposure amount giving a density of 0.5, and indicated by the relative sensitivity with the sensitivity of Sample No. 4 as 100.

The compositions of the developing solution and fixing solution used in the present invention are shown below.

Developer Formulation Part-A (for 12 liter finish) Potassium hydroxide 450 g Potassium sulfite (50% solution) 2280 g Diethylenetetraamine pentaacetic acid 120 g Sodium bicarbonate 132 g 5-Methylbenzotriazole 1.2 g 1-phenyl-5- Mercaptotetrazole 0.2g Hydroquinone 340g Add water to make 5000ml.

Part-B (for 12 l finishing) Glacial acetic acid 170 g Triethylene glycol 185 g 1-Phenyl-3-pyrazolidone 22 g 5-Nitroindazole 0.4 g N-Acetyl-DL-penicillamine 1.2 g Starter glacial acetic acid 120 g Potassium bromide 225 g Water Add to make 1.0 liter.

Fixer Formulation Part-A (for 18-liter finish) Ammonium thiosulfate (70wt / vol%) 6000g Sodium sulfite 110g Sodium acetate trihydrate 450g Sodium citrate 50g Gluconic acid 70g 1- (N, N-dimethylamino) -Ethyl-5-mercaptotetrazole 18g Part-B Aluminum sulfate 800g To prepare the developer, add Part A and Part B to approximately 5 liters of water at the same time, add water while stirring and dissolve, and add 12 liters with glacial acetic acid.
The H was adjusted to 10.40. This is used as a developing solution.

20 ml / l of the above-mentioned starter was added to 1 liter of this developing solution to adjust the pH to 10.26 to prepare a working solution.

The fixing solution was prepared by adding Part A and Part B to approximately 5 liters of water.
Was added at the same time, water was added while dissolving with stirring to make 18 l, and the pH was adjusted to 4.6 using sulfuric acid and NaOH. This was used as a fixing solution.

Evaluation of Pressure Sensitivity The sample was conditioned in a dark room at a temperature of 23 ° C. and 40% RH for 1 hour, and then, when the sample was folded in two under the same conditions, a plate with a 4 mm gap was provided between the ends of the sample. It was fixed and bent 180 degrees. The bending speed was 180 degrees in 0.5 seconds, and the original state was restored in the next 0.5 seconds. 10 after bending
The treatment was carried out with no exposure after a minute.

After that, the difference between the density of the blackened portion in the band shape by bending and the density of the fog + base of the sample was measured. The smaller the density difference ΔD, the better the pressure resistance. The results obtained are shown in Table 3.

[0110]

[Table 3]

As is apparent from the table, the sample according to the present invention has high sensitivity and excellent pressure resistance.

[0112]

According to the present invention, a silver halide photographic light-sensitive material having high sensitivity and excellent pressure resistance can be obtained.

Claims (2)

[Claims] 1. A silver halide grain having an average silver iodide content in the vicinity of the outermost surface of the silver halide grain of 1.5 mol% or more and having an average aspect ratio of less than 2 having two parallel twin planes. A silver halide photographic light-sensitive material characterized by containing. 2. The average silver iodide content of silver halide grains is
The silver halide grain according to claim 1, which contains silver halide grains having a silver iodide content of 2.0 mol% or less and a silver iodide content of 5 mol% or more inside the grain. Silver photographic light-sensitive material.