JP2001083642A - Photographic silver halide emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain monodisperse high silver chloride grains, particularly monodisperse high silver chloride grains of small size by carrying out at least one grain forming step using a low viscosity dispersion medium and incorporating a specified mol percentage or more of silver chloride. SOLUTION: The photographic silver halide emulsion is formed through at least one grain forming step using a low viscosity dispersion medium and contains >=50 mol% silver chloride. Gelatin is contained as protective colloid in the dispersion medium and the molecular weight of the protective colloid is monodisperse. The protective colloid is prepared by chemical synthesis or genetic engineering technique. Flat platy grains having an aspect ratio of >=2 occupy >=80% of the total projected area of all silver halide grains in the emulsion. The average equivalent circular diameter of the flat platy grains is <=0.8 μm and the average equivalent spherical diameter of all the grains is <=0.2 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic silver halide photographic material, and more particularly to the formation of high silver chloride grains.

[0002]

2. Description of the Related Art For the purpose of simple and rapid development processing, so-called high silver chloride grains having a high silver chloride content (silver chloride content of 5%).
Various techniques have been proposed for utilizing grains of 0 mol% or more (hereinafter referred to as high silver chloride grains). By using high silver chloride particles, advantages such as an increase in development speed and an increase in reusability of the processing solution can be obtained. For this reason, the type of photosensitive material for printing such as color photographic paper, which uses high silver chloride particles, has become the mainstream. In order to further increase the processing speed, it is effective to reduce the size of silver halide grains, and small-sized high-silver chloride grains have been desired. As a method of forming silver halide grains having a small size, it is effective to reduce the forming temperature. In particular, lowering the temperature during nucleation is particularly effective. However, when nucleation is performed at a low temperature, normal crystal grains, parallel twin grains (tabular grains), and non-parallel twin grains are mixed, and Is impaired in monodispersity. As a result, it is difficult to control photographic properties. The following can be considered as causes for the loss of the monodispersibility of the particles. In other words, gelatin is usually used as a protective colloid for silver halide grains in the production process of silver halide grain emulsions, but the solubility of the gelatin decreases (gelation) and the protective colloid ability is lost. Can be Therefore, there has been a demand for a dispersion medium having excellent protective colloid ability even at a low temperature.

In recent years, chemically modified gelatin has been actively used as a technique for preparing silver halide tabular grain emulsions having a high aspect ratio. Tokuhei 5-1269
No. 6 discloses a technique for preparing thin tabular grains by using, as a protective colloid, gelatin in which a sulfide group in gelatin has been invalidated with hydrogen peroxide or the like. JP-A-8-82883 discloses a technique for adjusting thin tabular grains by invalidating amino groups and sulfide groups. Japanese Patent Application No. 8-308123 discloses a technique for preparing thin and monodisperse tabular grains by introducing two or more carboxyl groups when chemically modifying an amino group in gelatin. further,
U.S. Pat.No. 5,807,712 and European Patent No.926543A1 teach that gelatin used as a protective colloid is designed at the molecular level, and the flattening rate is increased by using a gelatin derivative produced using a chemically synthesized or genetic engineering technique. Techniques for improving are disclosed.

However, in the production process of a silver halide grain emulsion, gelatin used as a protective colloid is intentionally modified by chemical modification or molecular design to form a dispersion medium represented by viscosity. There is no known technique for adjusting the intended silver halide grains by optimizing macroscopic physical properties. For example, in consideration of the temperature dependence of the solubility of silver halide, gelatin that does not gel at lower temperatures can be used.

[0005] On the other hand, gelatin currently manufactured industrially is generally simply derived from collagen contained in bones and skins of animals. One of the drawbacks of gelatin derived from animal collagen is that the molecular weight is polydisperse. It is obvious that the fact that the molecular weight is polydisperse is disadvantageous in controlling the physical properties of the dispersion medium containing gelatin. In addition, if gelatin has a monodispersed molecular weight, the effect of monodispersing the grain shape may be expected in the formation of silver halide grains.

[0006] The technology for producing a gelatin derivative using a chemical synthesis or genetic engineering technique described in US Pat. No. 5,580,712 and European Patent No. 926543A1 is as follows.
It also provides a gelatin derivative having a theoretically monodispersed molecular weight (experimentally, even if the molecular weight distribution is measured by gel permeation chromatography or the like, it is substantially monodispersed). However, there is no intention to optimize the physical properties of the dispersion medium used in the production process of the silver halide grain emulsion by monodispersing the molecular weight of gelatin.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide monodisperse high silver chloride grains, especially small monodisperse high silver chloride grains.

[0008]

The object of the present invention has been attained by the following method. 1. A silver halide emulsion formed by at least one step of forming grains using a low-viscosity dispersion medium and containing at least 50 mol% of silver chloride. 2. The silver halide emulsion according to 2.1, wherein gelatin is contained as a protective colloid in the dispersion medium. 3. The silver halide emulsion according to 1 or 2, wherein the molecular weight of the protective colloid in the dispersion medium is monodisperse. 4. A silver halide emulsion as described in any one of items 1 to 3, wherein the protective colloid in the dispersion medium is produced by a chemical synthesis or genetic engineering technique. 5. 5. The silver halide emulsion according to items 1 to 4, wherein 80% or more of the total projected area is tabular grains having an aspect ratio of 2 or more. 6. 80% or more of the total projected area is tabular grains having an aspect ratio of 2 or more, and the tabular grains have an average equivalent circle diameter of 0.
5. The silver halide emulsion as described in any one of items 1 to 4, which has a thickness of 8 μm or less. 7. 5. The silver halide emulsion as described in any one of items 1 to 4, wherein the average equivalent spherical diameter of all grains is 0.2 μm or less. 8. 2. The silver halide grain according to claim 1, comprising 0.05 to 0.6 mol% of iodine with respect to silver.
8. The silver halide emulsion according to any one of items 1 to 7. 9. Silver halide grains in an amount of 0.1 mol% to 4
9. The silver halide emulsion according to any one of claims 1 to 8, which contains mol% of bromo.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the dispersion medium of the present invention and the protective colloid in the dispersion medium will be described. The viscosity of the dispersion medium is greatly affected by the protective colloid species and the concentration thereof in the dispersion medium, the temperature of the system, the ionic strength, and the pH. Furthermore, depending on the type of protective colloid, the viscosity of the dispersion medium may change over time.

[0010] The viscosity of the dispersion medium is measured using a rotational viscometer. In the present invention, the viscosity of the dispersion medium was measured after the protective colloid used was allowed to stand for 1 hour after dissolution.

The low viscosity in the present invention is an area smaller than the viscosity η of the dispersion medium given by the equation (1). Equation 1 η = (2.8159−0.0743T) exp {(0.1479−0.0017T) C} where η is the viscosity of the dispersion medium (cp), T is the temperature of the dispersion medium (° C.), and C is the protection in the dispersion medium. Colloid concentration (% by weight).

The ionic strength of the dispersion medium is preferably 2 or less,
1.5 or less is more preferable, and 1 or less is further preferable.
The pH of the dispersion medium is preferably 2 to 11, more preferably 3
-10, more preferably 4-9.

In the present invention, the low temperature is preferably 30
C. or lower, more preferably 20.degree. C. or lower, still more preferably 10.degree. C. or lower.

In the present invention, gelatin can be used as a protective colloid in the dispersion medium. The molecular weight of the gelatin is at least 2500, more preferably 10,000 or more. Kinds of gelatin include alkali-treated gelatin derived from animal collagen, oxidized gelatin obtained by oxidizing a methionine group in the gelatin molecule with hydrogen peroxide or the like (methionine content of 40 μmol / g or less), and amino group-modified gelatin (for example, phthalate). Gelatin, trimellitated gelatin, succinated gelatin, maleated gelatin, esterified gelatin) and low molecular weight gelatin (molecular weight: 2500)
~ 40000 is used.

In order to realize the low-viscosity dispersion medium of the present invention, it is effective that the protective colloid has a monodisperse molecular weight.
Monodisperse means that the molecular weight distribution curve measured by gel permeation chromatography has a substantially symmetric single peak according to the PAGI method, and the distribution width of the molecular weight is centered on the average molecular weight. And preferably ± 150%
Or less, more preferably ± 100% or less, still more preferably ± 80% or less.

The gelatin used in the emulsion of the present invention is derived from animal collagen and can have amino acids equivalent to those naturally occurring. Equivalent here means that the amino acid identity is at least 80%, preferably 90%, with the naturally occurring one.

The emulsion of the present invention can have gelatin derived from animal collagen having an amino acid sequence substantially the same as that of a naturally occurring one. Here, “substantial” means
It means that the amino acid mutation is less than 5, preferably less than 3. Suitable types of collagen are I, II and III. Preferably, the sequence is close to the native sequence to ensure activity and avoid expression problems. DNA encoding the amino acid sequence of gelatin may be natural or synthetic. Colorgen type according to the present invention
III The amino acid sequence suitably has or is the sequence of FIG. 3 described in Japanese Patent Application No. 10-378430. The collagen type I amino acid sequence according to the present invention is disclosed in Japanese Patent Application No. 10-378.
No. 430 has or is the sequence of FIG. 8, 10 or 12. Collagen type III is Biochim Biopy
s. Has the amino acid defined in Acta (1994) 1271: 41-48. This document is included herein by reference.

An emulsion according to the present invention in which the gelatin is present in a substantially pure form means that the gelatin is substantially free of nucleic acids, polysaccharides and other proteins. Whether the presence of the present sugars and nucleic acids, even in trace amounts, can have some effect on crystal formation, and indeed whether a sufficiently pure recombinant material for specific photographic applications can be made. I had to doubt.

When Pichia pastoris is used as an expression host, it is advantageous to use a nucleic acid sequence encoding an amino acid sequence that does not have the MGPR sequence, even if it is present in the native sequence of collagen I. This is because we have unexpectedly discovered that this sequence is a new recognition site for the protease present in Pichia pastoris that some collagen types receive. The protease is a Kex-2-like protease,
It is expected that a negative host strain for a Kex-2-like protease would be a suitable host cell. Under general conditions when using Pichia pastoris as a host, the corresponding amino acid sequence is [Leu-Ile-VaI-Met].
-Xaa-Yaa-Arg (wherein Xaa and Yaa
Corresponds to Cly and Pro or other amino acids, wherein at least one of the amino acids in parentheses is changed)
It may be advantageous to use a nucleic acid sequence that encodes a collagen free. The host is selected because the open structure of non-helical collagen is susceptible to proteolysis, and / or
Alternatively, the sequence to be expressed should preferably be mutated or selected so that proteolysis is minimized for the particular combination of host and expressed sequence. Based on the common general knowledge and the present disclosure, including the contents of the cited documents, there are numerous options open to the person skilled in the art to accomplish this.

Another method for increasing expression will reside in codon usage optimized for the host cell in which the sequence is introduced for expression. The use of multicopy transformants is also a method by which increased expression can be achieved. It has been suggested in the art of expression of the bovine brain trypsin inhibitor Saccharomyces cerevisiae that the ultimate level of protein secretion is ultimately determined by the protein folding capacity of the endoplasmic reticulum. Exceeding this capacity by utilizing multicopy transformants is thought to result in the accumulation of unfolded proteins in the endoplasmic reticulum and a concomitant enormous decrease in expression levels due to physiological instability. I have. This is 1995 Parekh
(Protein Expr. Purif. 6, 537-545) and 19
1997 Parekh and Wittrup (Biotechnol. Prog. 13, 117
-122). For our recombinant collagen, which is expressed as an unfolded molecule,
This negative feature is counteracted and / or the phenomenon appears to be less relevant in other expression hosts, especially other yeast hosts. In yeast and bacterial hosts, where there is a prolyl hydroxylation mechanism, as such, expression of collagen in those hosts will result in unfolded collagen. If the collagen is not folded, it will not deplete the ER's folding ability. Also, because of the significant solubility, unfolded and unhydroxylated collagen will not aggregate or accumulate in the endoplasmic reticulum. To eliminate the risk of such folding becoming related to the degree of expression, it is desirable that the collagen not be hydroxylated, or at least hydroxylated to the lowest extent possible.

Heterogeneous prolyl-4 in yeast cells such as Saccharomyces cerevisiae and Pichia pastoris.
It has recently been found that hydroxylation can be achieved by co-expression of hydroxylase. This was Vu in 1997
orela et al. (EMBO J. 16, 6702-6712) and 199
Vaughan et al. (DNA cell Biol. 17,511-518)
Is described. Since the gelation temperature of gelatin depends on the degree of hydroxylation, it will now be possible to vary the degree of hydroxylation in a way that results in expression products having different gelling temperatures. This would be of particular interest in methods having specific temperature requirements that previously prohibited the economic use of collagen, ie, requiring temperatures above room temperature to prevent unwanted gelation.

Gelatin is a fragment of fixed length and composition derived from the sequence encoding natural collagen, wherein the diagnostic strip has a GXY portion characteristic of collagen, It need not be identical to the native sequence in that it is at least as long as weighing 2.5 kDa. Suitably, the weight may be between 2.5 and 100 kDa. Fragments of various sizes are suitable. 5-50kDa, even 20
5050 kDa is a suitable embodiment to be applied. The gelatin can be made de novo from synthetic nucleic acid sequences.

A variety of methods are available to ensure the absence of a helical structure. For example, ensuring the absence of hydroxyproline in gelatin and / or the absence of procollagen and telopeptides. Preferably, for photographic applications, the gelatin should be free of cysteine. AgX emulsions according to the invention in which the gelatin has not been deaminated are an interesting further embodiment of the invention, wherein the gelatin is an isoelectric point of 7-10.

Further studies were conducted to see what else could be found to define what other parameters could be used to improve the results. . To do this, we analyzed a number of modified collagens, non-recombinantly produced collagens, using our recombinant collagens for testing and determined the relevant parameters. Next, we have defined various categories of compounds as suitable for making silver halide to the extent required for tabular grain formation.

Further, another embodiment of the above-shown embodiment having a gelatin having a reduced amino acid oxidized to such an extent that it is present at a level equal to 0.1 to 200 micromoles of reduced methionine per gram of the gelatin. Emulsions of the invention in any of these are suitable embodiments. Preferably, methionine per gram of the gelatin is present at less than 160 micromolar, preferably less than 120 micromolar. Since low levels of reducing power are preferred, preferred emulsions according to the present invention comprise reducing amino acids oxidized to such an extent that the reducing amino acids are present at a level equal to 0.1-80 micromoles of reducing power of methionine per gram of gelatin. It is good to contain the gelatin which has. Relatively high levels of reducing amino acids such that reducing amino acids are present at a level equal to 30-80 micromoles of methionine reducing power per gram of the gelatin can also provide satisfactory results. This is quite surprising given the previous teachings on the requirements for tabular grain formation, the requirement for low reducing power, in many prior art publications. The invention also encompasses those modified collagens having less than 80 micromolar Lebenore's methionine, such as modified type I. For example, modifications to type I collagen are not necessarily due to oxidation, but may be the result of mutations in the coding sequence in which reducing amino acids have been replaced to the extent required by non-reducing amino acids. This saves the step of chemical treatment of the collagen in the silver halide emulsion before use, with the attendant time and cost advantages of the production process. Obviously, natural collagen without more than 80 micromolar reduced amino acids, such as modified type III, is also applicable.

In addition, in contrast to the teachings of Eastman Kodak, first shown and published in 1996, in any of the other embodiments shown, the emulsions of the present invention had a 50 mV
A suitable gelatin having a deptizer with a binding force of silver of greater than 10 and capable of functioning fairly well as an emulsion having a high level of tabular grain formation has a binding force to silver of 100 mV or less. In contrast to the teachings of the prior art, gelatin can have a binding power to silver of 50-100 mV, providing emulsions with excellent tabular grain percentages.

In our test, the ripening process is performed without further addition of gelatin or extra silver. Obviously, in the method of the present invention, the maturation step may have such additional additions.
Gelatin can be the same material at both the nucleation and maturation stages. Further addition at the maturation stage
It could be advantageous for increased steric stability at this stage.

Preferred AgX emulsions according to the invention have a pH of from 4 to
8 having gelatin stable to silver halide tabular grain formation. Conventional gelatin from lime bone and hydroxylated gelatin does not show such tabular grain formation results above pH 5.5. Gelatins according to the invention, such as natural recombinant collagen III, do not exhibit such characteristics and obviate the need for strict pH adjustment during emulsion production storage and application. Natural recombinant collagen can also undergo methionine oxidation and exhibit improved behavior. Suitably, methionine levels are less than 80 micromolar per gram. Thus, emulsions according to the present invention can nucleate and grow at pH 4-8 without negatively affecting tabular grain formation. In the emulsion production process, the change in pH is
In further processing the emulsion obtained for photographic production,
It will not have a negative effect on the result.

The emulsion according to the invention offers the advantage that the gelatin has a homodispersity over the conventional gelatin with a silver halide emulsion. For this reason, the crystallization method is also more homogeneous with all the above advantages. At various stages of silver halide nucleation and growth,
The addition of substantially pure, more homogeneous gelatin allows the crystallization properties to be adjusted in a controlled manner in combination with cost-effectiveness and in ways not previously possible with collagenous gelatin. . Since many types of collagen are naturally present, they can also be applied to the photographic halide emulsions according to the invention.

There are 23 collagen genes discovered to date. Many of these have been partially or wholly sequenced. The data bank has various arrangements for that. For example, Genbank has accession number Genbank U0
8020 has a Col I sequence and a Col III sequence
him Biopys. Acta (1994) 1271: 41-48. These natural collagen genes, compared to themselves,
Shows 40-50% homology. Relevant information of the cited references for sequence data is included herein by reference. See, for example, page 5 of WO 95/31473. As noted above, the collagen-like compounds of the present invention, which compounds are subsequently used in silver halide emulsions for photographic applications
These natural sequences, obtained by isolation from natural sources or by chemical synthesis, are used to make the natural amino acid sequence or a sequence that encodes a polypeptide similar to the natural amino acid sequence, It is utilized as long as the peptide falls within the above parameters. The source of silver halide emulsion gelatin was animal bone, of which type I was the most commonly used type of silver halide emulsion because type I collagen is the most predominant collagen type. Currently, other collagen types can also be tested and applied for application in silver halide emulsions. Other collagen types are not applied as such in the prior art in photographic applications, and certainly not in halogenated emulsions per se. Of course, many collagen types are present in animal tissues that have been used to date. Now it is also possible to understand whether these collagen types do or do contribute to more advantageous properties for photographic products that have not been identified previously. Photosensitive emulsions having recombinant collagen-like polypeptides other than type I as collagen-like components are also considered to form suitable embodiments of the present invention, as long as the above specific requirements are satisfied. Specifically, use in silver halide is included. The location of the silver halide emulsion, a 100% homogeneous source of collagen, is expected to provide maximum homogeneity of crystal formation. The homodispersity requirement and its value are addressed in any of the descriptions of the present invention. Gelatin need not have full-length collagen, but may have fragments thereof. Suitably, however, such fragments are at least 2.5 kDa, preferably at least 10 kDa, in length, ensuring sufficient randomness of expression while retaining the collagen characteristics required for gelatin.

Another feature of the present invention is that 0.95 grams /
A method for producing a recombinant collagen-like polypeptide having expression of a nucleic acid sequence encoding a collagen-like polypeptide by a microorganism to a degree exceeding 1 liter. The recombinant collagen has no helical structure. Expression preferably takes place in a microorganism other than E. coli or Saccharomyces cerevisiae to ensure high expression and preferably secretion. The method can be suitably performed using a fungal cell, preferably a yeast cell. Suitably, the host cell is selected from the group consisting of high expression host cells such as Hansenula, Trichoderma, Aspergillus and Pichia. Fungi and especially yeast cells are preferred over bacteria because they receive less poor expression of repeated sequences. Most preferably, the host should not have high levels of proteases that attack the expressed collagen structure. In this regard, Pichia provides an example of a very suitable expression system. Preferably, the microorganism ensures the absence of a helical structure in the expressed product by the absence of an active post-translational processing mechanism that processes the collagen-like sequence into fibrogen. Also, such processes may occur when the microorganism does not have an active post-translational processing mechanism to process the collagen-like sequence into a triple helix, and / or when the nucleic acid sequence to be expressed encodes procollagen and telopeptide. It can happen when you do not have. The host used requires the presence of the gene for expression of prolyl-4-hydroxylase, an enzyme required for the collagen triple helix construct, in contrast to previous suggestions in the art for collagen production. And not. Based on the necessary parameters described herein, a host cell suitable for expressing the recombinant collagen of the present invention is suitable for photographic techniques in combination with the expressed sequence and knowledge of the host cell. Thus, the skilled artisan will be able to select an appropriate host cell from known industrial enzyme-producing fungal host cells, specifically yeast cells.

To ensure the production of non-cleavable sequences, the method of the present invention for making a recombinant collagen-like material involves the use of a recombinant collagen-like material substantially free of protease-active protease cleavage sites in expression host cells. Using a nucleic acid sequence encoding an amino acid sequence. For example, in the case of Pichia pastoris, and possibly also for other host cells, the corresponding amino acid is [Leu-ILe-
Val-Met] -Xaa-Yaa-Arg (where Xa
a and Yaa correspond to Gly and Pro or other amino acids, and at least one of the amino acids in parentheses is changed). A preferred method of the invention comprises using the microorganism Pichia pastoris as an expression host.

The method suitably provides for expression resulting in a peptide yield of greater than 3 grams / liter. The method can be suitably performed on the emulsions of the invention using any of the recombinant collagen-like gelatins defined above. As is evident from the examples in the environment described therein, the multicopy transformants provide more than 14 g of gelatin per liter of lantern broth at a biomass wet weight of 435 g / l. Most suitably,
Isolating the product from the microbial expression until substantially free of other proteins, polysaccharides and nucleic acids;
Purify. As will be apparent from the examples, many methods are available to one skilled in the art to accomplish this. The method according to the present invention can provide an expression product that is at least isolated and purified to a degree that is less than 100 ppm nucleic acid content, less than 5% polysaccharide content, and less than other proteins in commercial products. More preferably, the DNA content is less than 1 ppm, the RNA content is less than 10 ppm, even less than 5 ppm,
And a polysaccharide content of less than 1% can be obtained.

Another feature of the present invention involves a novel recombinant collagen-like peptide. In particular, the invention encompasses a substantially pure collagen-like material prepared by genetic engineering of a nucleic acid encoding collagen, wherein the piperizer has an amino acid sequence that exhibits greater than 40% homology to native collagen. And has more than four different amino acid types. The nucleic acid sequence may be derived from a native sequence or may be a synthetic nucleic acid that has been synthesized de novo. Another suitable embodiment is a pepriser as described in the embodiment of the emulsion according to the invention. Since homology is greater than 50%, preferably on the order of 80%, and more preferably 80-100%, homology as close as possible is desirable. Specifically, it is preferred that there is no block copolymer structure within the GXY subsequence of the product.

In a preferred embodiment of the present invention, the collagen-like material has no cysteine residues. The presence of cysteine in photographic products will hinder the product manufacturing process. Therefore, cysteine is preferably present in as small an amount as possible. This can be achieved by chemical modification of the recombinant product or by mutation of the nucleic acid sequence encoding the product by mutation or deletion of the sequence encoding cysteine to the extent that cysteine is no longer encoded. Suitably, photographic applications use materials having less than 0.1% cysteine.

In particular, for an optimal silver halide emulsion,
The homology of the collagen material is most important. that is,
Molecules of exactly the same composition and length that allow not only the problem of no impurities providing improvement, but also a good control of the very sensitive method of crystallization and also allow for a uniform crystallization length It is possible to provide. For this reason, recombinant collagen-like materials could have value in this part of the photographic process. Furthermore, the absence of fiber prototype formation and triple helix formation, features that have been completely overlooked to date, are required for this particular use in photographic manufacturing processes. Insights in the relevance of the number of reducing groups in photographic materials are also of great importance. This is not the exact low amount suggested in the prior art required for tabular grain formation. Thus, by reducing cysteine, histidine and methianine levels in the applied collagen-like material, a preferred embodiment of the present invention is formed.

The compounds according to the invention have revealed yet another advantage. Known collagen materials, for example, regular, hydrolyzed collagen from animal sources such as bone and skin, result in low tabular grain formation of photographic film emulsions at pH above pH 5.5. A new group of recombinant collagens is not only at pH 5.5, but also at higher pH, e.g.
It has been found that even H7 or higher results in the same and remarkably high degree of tabular grain formation. This offers the possibility of preparing silver halide emulsions with a less stringently prepared pH, since the new compounds have a distinctly lower pH dependence than non-recombinant collagen. Thus, the present invention provides a high tabular granular percentage, i.e., 50%.
It also relates to a recombinant collagen-like compound which can be used in the production of silver halide emulsions at pH 4 to 8 while reaching a percentage of more than 80%, preferably more than 80%. An additional feature of recombinant collagen that may be considered useful is that the isoelectric point is basic, as opposed to the Eastman Kodak recombinant polypeptide described in 1996 with an acidic IEP. It is expected that the recombinant collagen according to the invention will have an amino acid composition in which more than 4 amino acids are present, resulting in increased variability in the coding sequence and thus allowing for a high degree of expression. By using sequences with less than 33% GXY moieties in the total GXY sequence, additional changes are introduced. This good expression is achieved without using a block copolymer amino acid sequence structure in the GXY sequence.

Next, the particle forming method will be described. First, tabular grains will be described. Tabular grains are basically nucleated,
It is formed by three stages of ripening and growth. When forming ultrafine particles, the growth process can be omitted.

<Nucleation> The nucleation of tabular grains depends on the temperature, dispersion medium (gelatin), halogen concentration and the like, so that appropriate conditions must be set. The gelatin concentration is preferably 0.05% to 10%. The use of the low-viscosity dispersion medium according to the present invention in nucleation has a great effect on monodispersion and micronization. The chloride concentration is 0.001 mol / l to 1 mol / l, preferably 0.003 mol / l to 0.1 mol / l. The nucleation temperature may be any temperature from 0 ° C to 60 ° C, but is preferably from 0 ° C to 45 ° C, and particularly preferably from 0 ° C to 30 ° C. The pCl is preferably from 1.2 to 2.3 for plate nucleation, but from 1.2 to 1.p for monodispersion of the thickness.
8 is preferred.

<Aging> Although nuclei of tabular grains are formed at the first nucleation stage, nuclei other than tabular grains are also contained in the reaction vessel immediately after nucleation. Therefore, after nucleation, aging is required to leave only tabular grains and to eliminate others. When ordinary Ostwald ripening is performed, the tabular grain nuclei also dissolve and disappear, so that the tabular grain nuclei decrease and the size of the resulting tabular grains increases. To prevent this, a crystal habit controlling agent is added. The combined use of phthalated gelatin, ambered gelatin, and trimellit gelatin at the ripening stage enhances the effect of the crystal habit controlling agent, can prevent the dissolution of tabular grains, and is effective for monodispersing the thickness. At this time, the ratio between the crystal habit controlling agent and the gelatin is demanded, and it is preferable to use 3 × 10 ⁻⁶ to 6 × 10 ⁻⁶ mol of the crystal habit controlling agent per gram of phthalated, ambered or merit gelatin. When used in combination, the crystal habit controlling agent and the gelatin solution may be added at the same time, or may be added with a delay, but it is preferable to add a solution in which both are mixed in advance. The pAg during ripening is particularly important,
The voltage is preferably from 60 to 130 mV for the silver-silver chloride electrode. It is efficient that the ripening temperature is higher than the nucleation temperature.
In particular, it is preferable to increase the nucleation temperature by at least 15 ° C.

<Growth> Next, the formed nuclei are grown in the presence of a crystal habit controlling agent by physical ripening and addition of a silver salt and a halide. The case will be described. At this time, the chloride concentration is 5 mol / l or less, preferably 0.05 to 1 mol / l.
Mol / l. The temperature during grain growth is 10 ° C to 9
Although it can be selected in the range of 5 ° C, a range of 30 ° C to 75 ° C is preferable. The total amount of the crystal habit controlling agent used is at least 6 × 10 ⁻⁵ mol, especially 3 × 10 ⁵ mol, per mol of silver halide in the finished emulsion.
^-4 mol to 6 × 10 ^-2 mol is preferred. The phase control agent may be added at any time during the nucleation of silver halide grains, physical ripening, and during grain growth. The crystal habit controlling agent may be added to the reaction vessel in advance, but in the case of forming small-sized tabular grains, it is preferable to add the crystal phase controlling agent to the reaction vessel together with the growth of the grains to increase the concentration. The pH at the time of particle formation is arbitrary, but is preferably in a neutral to acidic range.

As to the crystal habit controlling agent used to form high silver chloride tabular grains, as described above, many compounds are disclosed in US Pat. Nos. 4,400,463, 4,713,323 and 4,713.
983508, 5185239, 517899
7, JP-A-64-70741 and JP-A-8-22
No. 7117 and the like.

In the case of tabular grains, 90% or more of the total projected area of the grains in the emulsion are preferably tabular grains having an aspect ratio of 2 or more, particularly preferably 5 or more.
Generally, the form of a tabular grain is a tabular shape having two parallel surfaces, the two parallel surfaces being referred to as a main surface, and a distance between the main surfaces being referred to as a "thickness". Thickness is 0.2 μm or less, 0.02
μm or more, and particularly preferably 0.0
It is 2 μm to 0.1 μm. The uniformity of the grain thickness is important, and the coefficient of variation (standard deviation divided by the average value) of the thickness of the silver halide grains of the present invention is preferably 20% or less, particularly preferably 16% or less. Is preferred. The thickness of the particles can be determined from the length of the shadow of an electron micrograph of a carbon replica method using metal vapor deposition. The average equivalent circle diameter of all particles is 0.2 μm to 10 μm.
Although it can be arbitrarily selected up to μm, the size of the small-sized particles is preferably 0.2 μm to 0.8 μm. Here, the equivalent circle diameter of the silver halide grains means the diameter of a circle having an area equal to the projected area of the grains in an electron micrograph. The ratio of the diameter / thickness is called an aspect ratio.
The equivalent circle diameter is 0.1 for particles used in the rapid processing light-sensitive material.
A small size range of 3 μm to 0.8 μm is preferred. The distribution of the circle equivalent diameter is preferably monodisperse, and the coefficient of variation of the circle equivalent diameter is preferably 22% or less.

Next, a method for forming normal crystal grains will be described. For nucleation of normal crystal grains, gelatin concentration was 0.5
% To 10% is preferred. The chloride concentration is 0.001 mol /
It is preferably from 0.5 to 0.5 mol / l, particularly preferably from 0.1 to 0.5 mol / l.
It is preferably from 003 mol / l to 0.05 mol / l. The nucleation temperature may be any temperature from 0 ° C to 60 ° C, but is preferably from 0 ° C to 45 ° C, and particularly preferably from 0 ° C to 30 ° C. Next, the formed nuclei are grown by physical ripening and addition of silver salts and halides. At this time, the chloride concentration is 1 mol / liter or less, preferably 0.05 to 0.5.
Mol / l. The temperature during grain growth is 0 ° C to 95
Although it can be selected in the range of ° C., the range of 10 ° C. to 50 ° C. is preferable in order to suppress the particle size. Halogen and silver used for growth may be added as silver halide fine particles. The pH at the time of particle formation is arbitrary, but is preferably in a neutral to acidic range.

The high silver chloride grains of the present invention are grains having a silver chloride content of 50 mol% or more. In particular, 90% or more is preferably silver chloride. Although the particles of the present invention may have a uniform structure, a so-called core / shell structure comprising a core portion and a shell portion surrounding the core portion is preferred. It is preferable that 90% or more of the core portion is silver chloride. The core portion may be composed of two or more portions having different halogen compositions. The shell portion preferably accounts for 50% or less of the total particle volume, particularly preferably 20% or less.

The grains of the present invention are prepared by adding silver iodide to the total amount of silver.
Preferably, it is contained in an amount of 0.1 mol% to 0.8 mol%. In particular, it is preferable to contain 0.2 mol% to 0.6 mol%. The iodide is preferably contained in the shell part (outermost layer). The silver iodide content of the shell part is preferably from 1.0 mol% to 13 mol%, particularly preferably from 2 mol% to 10 mol%. The silver bromide content is preferably from 0.1 mol% to 4 mol%. The silver bromide content in the grains is preferably higher in the shell part than in the core part. Further, it is preferable that a layer having a bromide content of 6 mol% or more exists in the particles.

If the crystal habit controlling agent is present on the surface of the grains even after the formation of the grains, it affects the adsorption of the sensitizing dye and the development. Therefore, the crystal habit controlling agent is preferably removed after the formation of the particles. However, when the crystal habit controlling agent is removed, it is difficult for the high silver chloride grains to maintain the {111} plane under ordinary conditions. Therefore, it is preferable to maintain the particle form by substituting with a photographically useful compound such as a sensitizing dye. This method is described in Japanese Patent Application Nos. 7-230906 and 7-289.
146, U.S. Patent Nos. 5,221,602 and 5,28
6,452, 5,298,387, 5,29
Nos. 8,388 and 5,176,992.

Although the crystal habit controlling agent is desorbed from the grains by the above method, it is preferable to remove the desorbed crystal habit controlling agent out of the emulsion by washing with water. The washing can be carried out at a temperature at which gelatin usually used as a protective colloid does not solidify. As the water washing method, various known techniques such as a flocculation method and an ultrafiltration method can be used. When a pyridinium salt is used as a crystal habit-controlling agent, the washing temperature is preferably 40 ° C. or higher, particularly preferably 50 ° C. or higher. In addition, the desorption of the crystal habit controlling agent is promoted from the particles at a low pH. Therefore, the pH in the water washing step is preferably low as long as the particles are not excessively aggregated.

In the silver halide grains of the present invention, the periodic table VI
Group II metals, namely osmium, iridium, rhodium,
Platinum, ruthenium, palladium, cobalt, nickel,
Metal ions selected from iron or complex ions thereof can be used alone or in combination. Further, a plurality of these metals may be used. The metal ion-providing compound is added to a gelatin aqueous solution, a halide aqueous solution, a silver salt number-order solution, or another aqueous solution which serves as a dispersion medium at the time of forming silver halide grains, or contains a metal ion in advance. The silver halide grains of the present invention can be incorporated into the silver halide grains of the present invention by adding them to the silver halide emulsion in the form of fine silver halide grains and dissolving the emulsion. In addition, the metal ions can be contained in the particles before, during, or immediately after the formation of the particles. It can be changed depending on whether or not it is contained.

In the silver halide grains of the present invention, 50 mol% or more, preferably 80 mol% or more, and more preferably 100%, of the metal ion providing compound is 50% of the grain volume from the surface of the silver halide grains. % Is preferably localized in the surface layer up to the amount corresponding to not more than 10%. The volume of this surface layer is preferably 30% or less. Localizing metal ions in the surface layer is advantageous for suppressing an increase in internal sensitivity and obtaining high sensitivity. In order to concentrate the metal ion-providing compound on the surface layer of such silver halide grains, for example, after forming the silver halide grains (core) in other parts along the surface layer, the surface layer is formed. It can be carried out by supplying the metal ion providing compound in accordance with the addition of the water-soluble silver salt solution and the aqueous halide solution.

The silver halide emulsion used in the present invention is:
In addition to the Group VIII metal, various polyvalent metal ion impurities can be introduced during the process of emulsion grain formation or physical ripening. The addition amount of these compounds varies widely depending on the purpose, but is preferably 1 to 1 mol of silver halide.
0 ^-9 to 10 ^-2 mol is preferred. The silver halide emulsion used in the present invention is usually chemically sensitized. As the chemical sensitization method, a gold sensitization method using a so-called gold compound (for example, US Pat. Nos. 2,448,060 and 3,320,069)
Sensitization method using metals such as iridium, platinum, rhodium and palladium (for example, US Pat. No. 2,448,060).
No. 2,566,245, No. 2,566,263
), A sulfur sensitization method using a sulfur-containing compound (for example, US Pat. No. 2,222,264), selenium sensitization using a selenium compound, tellurium sensitization using a tellurium compound, tin salts, thiourea dioxide, polyamine, etc. (For example, US Pat. Nos. 2,487,850 and 2,51)
Nos. 8,698 and 2,521,925). These sensitization methods can be used alone or in combination.

The silver halide emulsion used in the present invention is:
Gold sensitized, known in the industry, is preferred
New By applying gold sensitization, laser light etc.
To further reduce fluctuations in photographic performance during scanning exposure
Because it can be. For gold sensitization, chloroauric acid
Or its salts, gold thiocyanates and gold thiosulfates
Compounds can be used. The amount of these compounds added
Depending on the case, 5 × per mole of silver halide
10^-7~ 5 × 10^-2Mol, preferably 1 × 10 ^-6~ 1 ×
10^-3Is a mole. The timing of addition of these compounds
The sensitization is performed by the end of the chemical sensitization used for lightening. The present invention
In gold sensitization, other sensitization methods such as sensitization,
Selenium sensitization, tellurium sensitization, reduction sensitization or gold compound
It is also preferable to combine with noble metal sensitization using outside.
Is

The silver halide emulsion used in the present invention may contain various compounds or their precursors for the purpose of preventing fogging or stabilizing photographic performance during the production process, storage or photographic processing of the photographic material. Can be added. Specific examples of these compounds are described in JP-A-62-21.
Those described on page 39 to page 72 of No. 5272 are preferably used. The emulsion used in the present invention is preferably a so-called surface latent image type emulsion in which a latent image is mainly formed on the grain surface.

Hereinafter, the present invention will be described in more detail by way of examples. Gelatin used in the examples is as follows. Gelatin-1 Normal alkali-treated ossein gelatin made from bovine bone. The molecular weight distribution curve measured using gel permeation chromatography had multiple peaks, and the molecular weight of the gelatin was polydispersed. In addition, the viscosity of the dispersion medium containing the gelatin at 15 to 35 ° C. was higher than the value derived from Equation 1.

Gelatin-2 Rat COL3A1 produced using the genetic engineering technique described in European Patent No. 926543A1. The molecular weight distribution curve measured using gel permeation chromatography was a single peak, and the molecular weight of the gelatin was substantially monodisperse. Further, the viscosity of the dispersion medium containing the gelatin at 15 to 35 ° C. was lower than the value derived from Equation 1.

Example 1 (Preparation of {111} high silver chloride tabular grains (A); comparison) 2.0 g of sodium chloride and 2.4 g of gelatin-1 were added to 1.2 liters of water and kept at 33 ° C. While stirring into a container, 45 cc of an aqueous silver nitrate solution (18 g of silver nitrate) and 45 cc of an aqueous sodium chloride solution (6.2 kg of sodium chloride) were added.
g) was added in one minute by the double jet method. One minute after completion of the addition, 40 cc of an aqueous solution containing 0.8 mmol of 1-benzyl-4-phenylpyridine was added, and one minute later, 2.0 g of sodium chloride was added. After the temperature of the reaction vessel was raised to 60 ° C. in the next 25 minutes, it was aged for 20 minutes.
After aging, 560 cc of a 10% phthalated gelatin solution was added. 3.0 g of NaCl were added. After the addition, an aqueous silver nitrate solution (silver nitrate 113.1) was added at an accelerated flow rate for 13 minutes.
g), an aqueous solution of NaCl (NaCl, 41.3 g) and an aqueous solution of 1-benzyl-4-phenylpyridine (containing 1.2 mmol of 1-benzyl-4-phenylpyridine) were added. Thereafter, the silver nitrate aqueous solution (silver nitrate 3
4 g) and an aqueous halogen solution (yellow salt 3 mg, KI0.
66 g and 11.8 g of NaCl).
At the end of the addition, 2.8 mmol of KSCN, anhydro-
5-chloro-4,5-naphth-3,3'-bis- (4-
0.3 mmol of triethylamine salt of sulfobutyl) -thiocyanine hydroxide and anhydro-5,5 '
-Dichloro-3,3'-bis- (4-sulfobutyl)-
The triethylamine salt of thiacyanine hydroxide was added to 0.
After adding 5 mmol, the mixture was stirred and maintained at 75 ° C. for 20 minutes.

After the temperature was lowered to 40 ° C., the product was washed with water by a usual flocculation method. After washing with water, gelatin 67g
And phenol (5%) 80cc and distilled water 150c
c was added. PH with caustic soda and silver nitrate solution
It adjusted to 6.2 and pAg7.5. Obtained particles (A)
Was 80% or more of the total projected area was tabular grains, the average equivalent circle diameter was 0.59 μm, and the average thickness was 0.145 μm. The coefficient of variation of the thickness was 25.8%, and the coefficient of variation of the equivalent circle diameter was 29.0%.

Example 2 (High silver chloride tabular grains (B); the present invention) A silver halide emulsion was formed in the same manner as in Example 1 except that gelatin 1 used for nucleation was changed to gelatin-2. In the obtained grain (B), tabular grains accounted for 95% or more of the total projected area, the average equivalent circle diameter was 0.65 μm, and the average thickness was 0.116 μm. The coefficient of variation of the thickness is 18.
The coefficient of variation of the equivalent circle diameter was 22.0%.

Example 3 (High silver chloride tabular grains (C) formed at low temperature; comparison) 2.0 g of sodium chloride and 2.4 g of gelatin-1 were added to 1.2 liters of water, and the vessel was kept at 20 ° C. While stirring, 45 cc of an aqueous silver nitrate solution (18 g of silver nitrate) and 45 cc of an aqueous sodium chloride solution (6.2 g of sodium chloride)
Was added by the double jet method in one minute. One minute after the completion of the addition, 0.8 g of 1-benzyl-4-phenylpyridine was added.
After 40 minutes of an aqueous solution containing 40 mmol of an aqueous solution containing 1 mmol, 2.0 g of sodium chloride was added. After the temperature of the reaction vessel was raised to 50 ° C. in the next 25 minutes, it was aged for 30 minutes. After aging, 560 cc of a 10% phthalated gelatin solution was added. 3.0 g of NaCl were added. After the addition, an aqueous silver nitrate solution (113.1 g of nitric acid) was added at an accelerated flow rate for 13 minutes.
And an aqueous solution of NaCl (NaCl, 41.3 g) and 1-
An aqueous benzyl-4-phenylpyridine solution (containing 1.2 mmol of 1-benzyl-4-phenylpyridine) was added. Thereafter, the silver nitrate aqueous solution (silver nitrate 34
g) and an aqueous halogen solution (3 mg of yellow blood salt, KI 0.6)
6 g and 11.8 g of NaCl). At the end of the addition, 2.8 mmol of KSCN, anhydro-5-
0.3 mmol of the triethylamine salt of chloro-4,5-naphth-3,3'-bis- (4-sulfobutyl) -thiacyanine hydroxide and anhydro-5,5'-chloro-3,3'-bis- ( After 0.5 mmol of triethylamine of 4-sulfobutyl) -thiocyanine hydroxide was added, the mixture was stirred and maintained at 75 ° C. for 20 minutes.

After the temperature was lowered to 40 ° C., the product was washed with water by a usual flocculation method. After washing with water, gelatin 67g
And phenol (5%) 80cc and distilled water 150c
c was added. PH with caustic soda and silver nitrate solution
It adjusted to 6.2 and pAg7.5. Obtained particles (C)
Was 70% or more of the total projected area was tabular grains, the average equivalent circle diameter was 0.45 μm, and the average thickness was 0.148 μm. The coefficient of variation of the thickness was 33.8%, and the coefficient of variation of the equivalent circle diameter was 28.0%.

Example 4 (High silver chloride tabular grains (D) formed at low temperature; the present invention) Grain formation in the same manner as in Example 3 except that gelatin-1 used for nucleation was changed to gelatin-2. Was done. The resulting emulsion was tabular grains having an aspect ratio of 2 or more in 95% or more of the total projected area, and contained tabular grains (D) having an average equivalent circle diameter of 0.58 μm and an average thickness of 0.095 μm. The coefficient of variation of the particle thickness and the equivalent circle diameter is
16.6% and 19.5%.

Example 5 (Tabular grains containing iodine and bromide (E); the present invention) After the completion of grain formation in Example 4, an aqueous silver nitrate solution (1.2 g of silver nitrate) and iridium hexachloride were added to 8 ×.
KBr aqueous solution containing 10 ^-8 mol (KBr 0.84 g)
Was added at a constant flow rate for 5 minutes. Thereafter, water washing was performed in the same manner as in Example 9. The resulting emulsion had a total projected area of 9
5% or more were tabular grains having an aspect ratio of 2 or more, and were emulsions containing tabular grains (E) having an average equivalent circle diameter of 0.58 μm and an average thickness of 0.096 μm. The variation coefficients of the thickness and the equivalent circle diameter of the particles were 17.3% and 20.2%, respectively.
Met.

Example 6 (Regular particles (F); comparison) H ₂ O was added to a reaction vessel described in JP-A-51-83097.
300 cc, 46 g gelatin-1 and 3.2 NaCl.
g was added and the temperature was kept at 25 ° C. Stirring speed 1200rpm
391 cc of silver nitrate aqueous solution (96 g of silver nitrate) and Na
397 cc of a Cl aqueous solution (35.4 g of NaCl) was added for 9 minutes. Thereafter, the temperature was raised to 35 ° C. in 15 minutes.
Next, 391 cc of an aqueous silver nitrate solution (96 g of silver nitrate) and Na
408 cc of an aqueous Cl solution (35.0 g of NaCl) were added over 15 minutes. After completion of the addition, 0.67 g of the nucleic acid was added. The temperature was maintained at 35 ° C., and water was washed by a usual flocculation method. After washing with water, 0.1 g of gelatin per 1 g of emulsion
Gelatin and distilled water were added so that Further, the pH was adjusted to 6.2 and the pAg to 7.5 with sodium hydroxide and NaCl. The obtained emulsion was collected, and an electron microscope photographic image (TEM image) of the particle replica was observed. According to the data, 91 of all the particles are% cubic particles, and the average length of one piece is 0.12.
μm, and the coefficient of variation of the circle equivalent diameter was 20.9%. Twin particles were typical as examples of particles other than cubic particles.

Example 7 (Regular (G); the present invention) Gelatin-1 previously introduced into a reaction vessel was replaced with gelatin-2
Particle formation was performed in the same manner as in Example 6, except that the particle size was changed to. 98% of the obtained particles were cubic particles, the average of the circle equivalent diameter was 0.10 μm, and the coefficient of variation of the circle equivalent diameter was 15.7%. Thus, in the particles of the present invention, particles other than cubic particles were less mixed, and the coefficient of variation in size was also small.

Example 8 (Comparison of photographic properties) Emulsions A to E of Examples 1 to 5 were prepared by adding sodium thiosulfonate, 1- (5-methylureidophenyl) -5-mercaptotetrazole, sodium thiosulfate at 60 ° C. And chloroauric acid for optimal chemical sensitization. Thus, chemically sensitized emulsions A to E were obtained.

Using chemically sensitized emulsions A to E as blue-sensitive emulsions, coating samples were prepared in the same manner as in Example 1 of Japanese Patent Application No. 10-278255 to obtain coating samples A to E. An optical wedge and a tungsten light source were used for these samples.
Seconds of exposure. In the same manner as in Example 1 of Japanese Patent Application No. 10-278255, a dry-to-dry 180-second CP45X manufactured by Fuji Photo Film Co., Ltd. was used. The reflection density of the color sample after the treatment was measured using a TCD type densitometer manufactured by Fuji Photo Film Co., Ltd. The sensitivity was represented by the exposure required to give a color density 1.0 higher than the fog density. The blue-sensitive layer was expressed as a relative value with the sensitivity of the coated sample A being 100. The gradation is 0.05 and 1.05 in density.
The density was expressed by the reciprocal of the difference between the logarithms of the exposure amounts giving the densities. The results are shown in Table 1.

[0067]

[Table 1]

As shown in Examples and Table 1, it was found that the particles prepared using the gelatin of the present invention have high monodispersity and provide a photosensitive material having high photographic characteristics.

[0069]

According to the present invention, a silver halide photographic emulsion comprising monodispersed and high silver chloride grains was obtained.

Continued on the front page (72) Inventor Yoichi Maruyama 210 Nakanuma, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Photo Film Co., Ltd. (72) Inventor Yuzo Toda 1st Odens Tart, Teilburg, the Netherlands Fuji Photo Film B-veh F-reference (reference) 2H023 BA02 BA03 BA04

Claims (9)

[Claims] 1. A method of forming a particle using at least one particle forming step using a low-viscosity dispersion medium, wherein at least 50 mol%
A silver halide emulsion comprising the above silver chloride. 2. A silver halide emulsion according to claim 1, comprising gelatin as a protective colloid in the dispersion medium. 3. A silver halide emulsion according to claim 1, wherein the molecular weight of the protective colloid in the dispersion medium is monodisperse. 4. The silver halide emulsion according to claim 1, wherein the protective colloid in the dispersion medium is produced by a chemical synthesis or genetic engineering technique. 5. The silver halide emulsion according to claim 1, wherein 80% or more of the total projected area is tabular grains having an aspect ratio of 2 or more. 6. A tabular grain having an aspect ratio of 2 or more in at least 80% of the total projected area, wherein the tabular grain has an average equivalent circle diameter of 0.8 μm or less.
5. The silver halide emulsion according to any one of items 1 to 4. 7. The silver halide emulsion according to claim 1, wherein the average equivalent sphere diameter of all grains is 0.2 μm or less. 8. The silver halide grains have a silver content of 0.05%.
The silver halide emulsion according to any one of claims 1 to 7, wherein the emulsion contains iodine in an amount of from 0.6 mol% to 0.6 mol%. 9. The silver halide emulsion according to claim 1, wherein the silver halide grains contain from 0.1 mol% to 4 mol% of bromo based on silver.