FIELD OF THE INVENTION
[0001] The present invention relates to a silver halide photographic emulsion, and more
particularly to a high-sensitivity silver halide photographic emulsion.
BACKGROUND OF THE INVENTION
[0002] There have lately been growing demands for still better photographic characteristics
of silver halide emulsions, such as higher sensitivity, more excellent graininess,
higher resolution, lower fog density and more sufficiently high optical density than
those of conventional ones. Any of these demands, although seemingly different, can
be mostly solved by technology for manufacturing low-fog and high-sensitivity silver
halide emulsions, and it is no exaggeration to say that the most important problem
for those skilled in the art is to develop a low-fog, high-sensitivity silver halide
emulsion.
[0003] The most proper method for achieving the raising of the sensitivity of an emulsion
is to reduce the inefficiency and increase the quantum efficiency of silver halide
crystals in the course of exposure to light. Conventional means to increase the quantum
efficiency is carried out by forming on the surface of or inside a silver halide crystal
a chemical sensitization center composed of silver sulfide or gold sulfide or a mixture
thereof, which functions as a sensitivity center that traps photoelectrons. The above
means is generally known as sulfur sensitization or gold-sulfur sensitisation.
[0004] However, if an attempt is made to form a chemical sensitization center having a good
electron trapping efficiency in accordance with a conventional chemical sensitization
method, it results in the formation of a number of chemical sensitization centers
which compete with one another for trapping photoelectrons in the process of exposure
to light. thus causing the latent image forming efficiency to lower, i.e., bringing
about lowering of the sensitivity.
[0005] As means to improve the above disadvantage of the conventional method there have
been proposed techniques to control the chemical sensitization center formation in
the presence of a chemical sensitization control agent or a chemical sensitization
reforming agent in the chemical sensitisation process as described in Japanese Patent
Publication Open to Public Inspection (hereinafter referred to as JP O.P.I.) Nos.
126526/1983 and 201651/1989, U.S. Patent Nos. 2,131,038, 3,411,914 and 3,554,757,
and Duffin, G.F., Photographic Emulsion Chemistry, Focal Press, London (1966), pp.138-143.
[0006] As other improving measures, JP O.P.I. No. 93447/1986 discloses various methods for
selectively growing the chemical sensitization center at a specific point on a silver
halide crystal.
[0007] However, as a result of our investigation, it has been found that the above improving
measures are not sufficient to meet the recent high-level demand for raising the sensitivity.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a high-sensitivity silver halide
photographic emulsion produced by an improved chemical sensitisation center forming
process.
[0009] It is another object of the invention to provide a method for producing a high-sensitivity
silver halide photographic emulsion.
[0010] The above objects of the present invention are accomplished by a silver halide photographic
emulsion containing silver halide grains having a chemical sensitization center comprised
of silver sulfide or gold sulfide or a mixture thereof formed in the presence of a
nucleus capable of catalytically acting upon and accelerating the silver sulfide forming
reaction (catalytic nucleus) on the surface of the silver halide crystal and also
in the presence of a compound adsorbent to the silver halide crystal.
[0011] The emulsion of the present invention is prepared by forming the catalytic nucleus
on the surface of the silver halide grain and then performing chemical sensitization
in the presence of a compound adsorbent to the silver halide crystal.
DETAILED DESCRIPTION OF THE INVENTION
[0012] The nucleus capable of catalytically acting upon and accelerating the silver sulfide
forming reaction (catalytic nucleus) is different from the foregoing specific site
on a silver halide crystal defined in the previously mentioned JP O.P.I. No. 93447/1986.
The catalytic nucleus in the invention is a specific point comprised of an element
or a combination of elements other than halogen elements constituting silver halide;
i.e., a specific point comprised of a noble metal element such as Ag, Au, Pt, Ir,
Pd, etc. and/or a simple element such as S, Se, Te, etc. or a compound thereof such
as silver sulfide, gold sulfide, silver selenide, gold selenide, or the like, but
are not limited to the mentioned single substances and compounds.
[0013] Judgement of whether the specific point functions as a catalytic nucleus to accelerate
the silver sulfide forming reaction can be made by measuring the rate of the silver
sulfide forming reaction by a sulfur sensitizer. The silver sulfide forming reaction
in the invention proceeds at a rate of at least 1.5 times as fast as the reaction
in which silver halide is formed in the absence of the nucleus. The silver sulfide
forming reaction rate can be measured in accordance with various methods known to
those skilled in the art, such as a method for tracing the reaction by using a sulfur
sensitizer that is labelled with a radioactive element; a method for spectroscopically
measuring the amount of a produced silver sulfide; a method for measuring the changes
in the proton ion concentration released by the reaction of a sulfur sensitizer; and
the like. Reference can be made for these methods to H. Takiguchi, J. Imaging Sci.,
vol.32, p.20 (1988); E. Moisar, Ber. d. Bun- senges. Phys. Chem., vol.72, p.467 (1968);
and D. J. Cash, J. Photogr. Sci., vol.20, p.107 (1972).
[0014] The catalytic nucleus forming process is preferably put prior to the process for
forming silver sulfide sensitization center by a sulfur sensitizer. As the elemental
substance or compound for use in the formation of the catalytic nucleus there may
be utilized an elemental sulfur element or sulfur sensitizers, gold sensitizers and
selenium sensitizers as described later. The proper amount (number of atoms or molecules)
thereof depends on the conditions of factors such as silver halide crystals, the chemical
sensitization process, etc.
[0015] The sulfur sensitizer for producing silver sulfide in the invention may be selected
from among water-soluble sulfides, thiosulfates, thioureas, mercapto compounds and
rhodanines, which are exemplified in U.S. Patent Nos. 1,574,944, 2,410,689, 2,278,947,
3,501,313 and 3,656,955, West German Patent No. 1,422,869, and Japanese Patent Examined
Publication Nos. 20533/1974 and 28568/1983.
[0016] Preferred among these compounds are thiosulfates, thioureas and rhodanines, and the
most preferred are thiosulfates.
[0017] The using amount of a sulfur sensitizer varies according to the type of a silver
halide used, the kind of a compound used and ripening conditions, but is preferably
from 1x10
-4 to 1x10
-7 mole per mole and more preferably 1x10
-5 to 1x10
-7 mole per mole of silver halide. It is preferable that the sulfur sensitizer be slowly
added to have its reaction take place slowly, so that the reaction temperature is
preferably as low as 40 to 60°C. The silver ion concentration of the reaction system
(silver halide emulsion) is preferably as low as possible; pAg (absolute value of
logarithm of reciprocal of silver ion concentration) is preferably 8.0 to 11.0.
[0018] The compound adsorbent to the silver halide crystals used in the invention is a stabilizer,
antifoggant or spectrally sensitizing dye.
[0019] Examples of the stabilizer or antifoggant include azaindenes; azoles such as benzothiazolium
salts, nitroindazoles, nitrobenzimidazoles, chlorobenzimidazoles, bromobenzimidazoles,
mercaptobenzimidazoles, aminotirazoles, benzotriazoles, nitrobenzotriazoles, mercaptotetrazoles
such as 1-phenyl-5-mercaptotetrazole; mercaptopyrimidines, mercaptotriazines, thioketo
compounds such as oxazolinethione compounds, benzenethiosulfinic acids, benzenesulfinic
acids, benzenesulfonic acid amides, hydroquinone derivatives, aminophenol derivatives,
gallic acid derivatives and ascorbic acid derivatives. Preferred among these compounds
are azaindenes.
[0020] The following are typical examples of the azaindenes, but are not limited thereto.
- A-1
- 2,4-Dihydroxy-6-methyl-1,3a,7-triazaindene
- A-2
- 2,5-Dimethyl-7-hydroxy-1,4,7a-triazaindene
- A-3
- 5-Amino-7-Hydroxy-2-methyl-1,4,7a-triazaindene
- A-4
- 4-Hydroxy-6-methyl-1,3,3a,7-tetrazaindene
- A-5
- 4-Hydroxy-1,3,3a,7-tetrazaindene
- A-6
- 4-Hydroxy-6-phenyl-1,3,3a,7-tetrazaindene
- A-7
- 4-Methyl-6-hydroxy-1,3,3a,7-tetrazaindene
- A-8
- 2,6-Dimethyl-4-hydroxy-1,3,3a,7-tetrazaindene
- A-9
- 4-Hydroxy-5-ethyl-6-methyl-1,3,3a,7-tetrazaindene
- A-10
- 2,6-Dimethyl-4-hydroxy-5-ethyl-1,3,3a,7-tetrazaindene
- A-11
- 4-Hydroxy-5,6-dimethyl-1,3,3a,7-tetrazaindene
- A-12
- 2,5,6-Trimethyl-4-hydroxy-1,3,3a,7-tetrazaindene
- A-13
- 2-Methyl-4-hydroxy-6-phenyl-1,3,3a,7-tetrazaindene
- A-14
- 4-Hydroxy-6-methyl-1,2,3a,7-tetrazaindene
- A-15
- 4-Hydroxy-6-ethyl-1,2,3a,7-tetrazaindene
- A-16
- 4-Hydroxy-6-phenyl-1,2,3a,7-tetrazaindene
- A-17
- 4-Hydroxy-1,2,3a,7-tetrazaindene
- A-18
- 4-Methyl-6-hydroxy-1,2,3a,7-tetrazaindene
- A-19
- 7-Hydroxy-5-methyl-1,2,3,4,6-pentazaindene
- A-20
- 5-Hydroxy-7-methyl-1,2,3,4,6-pentazaindene
- A-21
- 5,7-Dihydroxy-1,2,3,4,6-pentazaindene
- A-22
- 7-Hydroxy-5-methyl-2-phenyl-1,2,3,4,6-pentazaindene
- A-23
- 5-Dimethylamino-7-hydroxy-2-phenyl-1,2,3,4,6-pentazaindene
[0021] The sensitizing dyes preferably used for the invention include cyanine dyes, merocyanine
dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine
dyes, styryl dyes and hemioxonole dyes. The most useful dyes are cyanine dyes, merocyanine
dyes and complex merocyanine dyes.
[0022] These dyes may be ones having a basic heterocyclic nucleus, any of those nucleus
usually utilized for cyanine dyes, such as a pyrroline nucleus, oxazoline nucleus,
thiazoline nucleus, pyrrole nucleus, oxazole nucleus, thiazole nucleus, selenazole
nucleus, imidazole nucleus, tetrazole nucleus and pyridine nucleus; nuclei formed
with a alicyclic hydrocarbon ring fused to the above nuclei, such as an indolenine
nucleus, benzindolenine nucleus, indole nucleus, benzoxazole nucleus, naphthooxazole
nucleus, benzothiazole nucleus, naphthothiazole nucleus, benzoselenazole nucleus,
benzimidazole nucleus and quinoline nucleus. These nuclei may be substituted on a
carbon atom.
[0023] The aforementioned merocyanine dyes or complex merocyanine dyes each may have a ketomethylene-structural
nucleus such as a 5- or 6-member heterocyclic nucleus including pyrazoline-5-one nucleus,
thiohydantoin nucleus, 2-thioxazoline-2,4-dione nucleus, thiazolidine-2,4-dione nucleus,
rhodanine nucleus and thiobarbituric acid nucleus.
[0024] Useful sensitizing dyes are described in West German Patent No. 929,080, U.S. Patent
Nos. 2,231,658, 2,493,748, 2,503,776, 2,519,001, 2,912,329, 3,655,394, 3,656,959,
3,672,897 and 3,694,217, British Patent No. 1,242,588, JP O.P.I. No. 54547/1991 and
Japanese Patent Examined Publication No. 14030/1969.
[0025] These sensitizing dyes may be used alone or in combination. Combination of such sensitizing
dyes are often used particularly for the purpose of supersensitization, typical examples
of which are described in U.S. Patent Nos. 268,545, 2,977,229, 3,397,060, 3,522,052,
3,527,641, 3,617,293, 3,628,964, 3,666,480, 3,679,428, 3,703,377, 3,769,301, 3,814,609
and 3,837,862, British Patent No. 1,344,281 and Japanese Patent Examined Publication
No. 4936/1968.
[0027] An emulsion, in addition to the aforementioned dyes, may also contain a dye which
in itself has no spectral sensitization effect or a substance which does substantially
not absorb any visible rays but shows supersensitization effect. For example, the
emulsion may contain the nitrogen-containing heterocyclic group-substituted aminostilben
compound described in U.S. Patent Nos. 2,933,390 and 3,635,721; the aromatic organic
acid-formaldehyde condensate described in U.S. Patent No. 3,743,510; cadmium salts,
azaindene compounds, or the like. The combined use of those as described in U.S. Patent
Nos. 3,615,613, 3,615,641 and 3,635,721 are particularly useful.
[0028] The compound adsorbent to silver halide to be made present as a control agent in
the chemical sensitization center forming process of the invention may be used alone
or in combination of a plurality of kinds thereof. When a silver halide emulsion needs
to be spectrally sensitized, it is preferable that a spectral sensitization dye be
used in combination as a control agent for the chemical sensitization process. In
this instance, good results can often be obtained when a compound such as the foregoing
stabilizer or antifoggant is used in combination to raise the covering rate on the
surface of silver halide crystals.
[0029] The covering rate on the surface of silver halide crystals by the adsorbent compound
is preferably not less than 50%, and more preferably not less than 70%.
[0030] As the gold sensitizer usable in combination in the invention there may be used various
gold compounds having a gold oxidation number of either +1 or +3. Typical examples
of the gold sensitizer include chloroaurates, potassium chloroaurate, auric chloride,
potassium-auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium
aurothiocyanate, pyridyltrichlorogold and gold complexes with organic sulfur compounds.
[0031] The adding amount of the gold sensitizer differs according to various conditions,
but is preferably about 10⁻⁷ to 10⁻¹ mole per mole of silver halide. The gold sensitizer
for forming a chemical sensitization center is preferably added after completion of
the silver sulfide forming process.
[0032] In the invention, other chemical sensitizers additionally usable in combination include
selenium sensitizers such as aliphatic isoselenocyanates such as allyl isoselenocyanate,
selenoureas, selenoketones, selenoamides, selenocarboxylic acids and esters thereof,
selenophosphates, diethyl selenide and diethyl diselenide. Particular examples of
the above sensitizers are described in U.S. Patent Nos. 1,574,944, 1,602,592 and 1,623,499,
and also include the amines and reductive substances such as stannous salts described
in U.S. Patent Nos. 2,487,850, 2,518,698, 2,521,925, 2,521,926, 2,419,973, 2,694,637
and 2,983,619, and the salts of noble metals such as platinum, palladium, iridium
and rhodium described in U.S. Patent Nos. 2,448,060, 2,566,245 and 2,566,263.
[0033] The chemical ripening with the compound of the invention may be performed satisfactorily
in the presence of a solvent for silver halide, such as a thiocyanate, thioether,
tetra-substituted thiourea or the like.
[0034] The silver halide emulsion of the invention may be of an arbitrary silver halide
composition such as silver bromide, silver iodobromide, silver iodochlorobromide,
silver chlorobromide or silver chloride, which can be prepared in accordance with
an appropriate one of the methods described in P. Glafkides, Chimie et Physique Photographique
(Paul Montel, 1967); G. F. Duffin, Photographic Emulsion Chemistry (The Focal Press,
1966); and V. L. Zelikman, Making and Coating Photographic Emulsion (The Focal Press,
1964); i.e., can be prepared in accordance with any one of the acidic, neutral and
ammoniacal methods. The mixing of an aqueous silver salt solution and an aqueous halide
solution for the reaction thereof may be made in any of the single-jet precipitation
process, double-jet process and combination of both processes, and further may also
be made in the process of forming silver halide grains in the presence of excessive
silver ions, the so-called reverse precipitation process. As one form of the double-jet
process there may be used a process for maintaining pAg constant in the liquid phase
in which silver halide is produced, the so-called controlled double-jet process.
[0035] The silver halide grain size distribution of the silver halide emulsion of the invention
may be either wider or narrower.
[0036] The silver halide grains contained in the silver halide emulsion of the invention
may be regular-form grains such as octahedral or tetradecahedral grains, irregular-form
grains such as spherical grains, twin planes-having grains or grains in the complex
form of these grains. The silver halide grain may be of a substantially uniform composition-having
structure, a core/shell type double structure or a multiphase structure. In the case
of a core/shell type silver halide grain, it is preferably of a heterogeneous halide
composition of core and shell phases.
[0037] The invention may apply to the sensitization of a tabular silver halide grain emulsion.
The tabular silver halide grain is one having a diameter/thickness ratio of not less
than 3, wherein the 'diameter' means the diameter of a circle equivalent in the area
to the projection area of a grain, and the 'thickness' is expressed in terms of the
distance between the two parallel surfaces constituting a tabular silver halide grain.
[0038] The composition and structure of the tabular silver halide grain are the same as
those of the previously mentioned silver halide grain.
[0039] The silver halide crystal grain contained in the silver halide emulsion of the invention
may be joined with a different composition-having silver halide by epitaxial junction
to the host silver halide crystal, and may also be joined with a non-silver halide
compound such as silver thiocyanate or lead oxide. In the silver halide grain forming
or ripening process, a chalcogen compound such as of sulfur, selenium and tellurium,
a cadmium salt, a zinc salt, a lead salt, thalium, an iridium salt or complex salt,
a rhodium salt or complex salt, or an iron salt or complex salt may be present together.
[0040] Also, the core phase of the silver halide grain may be subjected to reduction sensitization
as described in Japanese Patent Examined Publication No. 1410/1983 and Moisar et al,
Journal of Photographic Science, vol.25 (1977), pp.19-27.
[0041] The silver halide emulsion of the invention may, for the purpose of raising the sensitivity
and contrast or of development acceleration, contain, e.g., polyalkylene oxide or
the ether, ester or amine derivative thereof, a thioether compound, a thiomorpholine,
a quaternary ammonium salt, a urethane derivative, a urea derivative, an imidazole
derivative or a 3-pyrazolidone derivative; for example, the emulsion may contain those
described in U.S. Patent Nos. 2,400,532, 2,423,549, 2,716,062, 3,617,280, 3,772,021
and 3,808,003.
[0042] The silver halide emulsion of the invention may contain an antifoggant and a stabilizer
even after completion of the chemical sensitization process. Compounds usable as the
antifoggant or stabilizer are described in the section entitled 'Antifoggrants and
Stabilizer' at page 107 of Product Licensing Index, vol.92.
[0043] The silver halide emulsion of the invention may also contain known photographic additives.
[0044] The known photographic additives include the compounds disclosed in Research Disclosure
RD-17643 (Dec. 1978) and RD-18716 (Nov. 1979), which are listed in the following table.

[0045] The emulsion of the light-sensitive material of the invention may contain a dye forming
coupler capable of forming a dye as a result of its coupling reaction with the oxidation
product of an aromatic primary amine developing agent such as a p-phenylenediamine
derivative or an aminophenol derivative.
[0046] The dye forming coupler is usually so selected as to form an appropriate dye that
absorbs a specific spectral light to which a relevant emulsion layer is sensitive;
that is, a yellow dye forming coupler is used for a blue-sensitive emulsion layer,
a magenta dye forming coupler for a green-sensitive emulsion layer and a cyan dye
forming coupler for a red-sensitive emulsion layer.
[0047] However, the silver halide color photographic light-sensitive material may be prepared
to have coupler-emulsion combinations different from the above according to purposes.
[0048] Each dye forming coupler preferably comprises a group having not less than 8 carbon
atoms, the so-called ballasting group, which makes the coupler non-diffusible. The
dye forming coupler may be either a four-equivalent coupler that requires reduction
of 4 silver ions for forming one molecule of a dye or a two-equivalent coupler that
requires reduction of 2 silver ions for forming one molecule of a dye. The dye forming
coupler includes colored couplers having color correction effect and compounds capable
of releasing photographically useful fragments as a result of its coupling reaction
with the oxidation product of a developing agent, said photographically useful fragments
including development inhibitors, development accelerators, bleaching accelerators,
developing agents, silver halide solvents, toning agents, hardeners, fogging agents,
antifoggants, chemical sensitizers, spectral sensitizers and desensitizers. Of these
couplers, the coupler that releases a development inhibitor, while developing is in
progress, to improve the sharpness and graininess of a developed image is called a
DIR coupler.
[0049] The DIR coupler may be replaced by a DIR compound that produces a colorless compound
and at the same time releases a development inhibitor as a result of its coupling
reaction with the oxidation product of a developing agent.
[0050] The DIR coupler and DIR compound used include those in which an inhibitor is linked
directly to the coupling position thereof and those in which an inhibitor is so linked
through a divalent group to the coupling position thereof as to be released by the
intramolecular nucleophilic reaction or intramolecular electron-transfer reaction
inside the group split off as a result of their coupling reaction (called timing DIR
coupler and timing DIR compound). The inhibitor includes one that becomes diffusible
after being released and one that is not so much diffusible; either one of these may
be used alone or both may be used in combination. A colorless coupler (also called
competing coupler) that effects coupling reaction with the oxidation product of an
aromatic primary amine developing agent but forms no dye may be used in combination
with a dye forming coupler.
[0051] As the yellow dye forming coupler there may be suitably used known acetanilide couplers.
Of these couplers, benzoylacetanilie and pivaloylacetanide compounds are advantageous.
[0052] Usable examples of the yellow dye forming coupler are disclosed in U.S. Patent Nos.
2,875,057, 3,265,506, 3,408,194, 3,551,155, 3,582,322, 3,725,072 and 3,891,445, West
German Patent No. 1,547,868, West German OLS Patent Nos. 2,219,917, 2,261,361 and
2,414,006, British Patent No. 1,425,020, Japanese Patent Examined Publication No.
10783/1976, JP O.P.I. Nos. 26133/1972, 73147/1973, 6341/1975, 87650/1975, 123342/1975,
130442/1975, 21827/1976, 102636/1976, 82424/1977, 115219/1977 and 95346/1983.
[0053] As the magenta dye forming coupler there may be used known 5-pyrazolone couplers,
pyrazolobenzimidazole couplers, pyrazolotriazole couplers, open-chain acylacetonitrile
couplers and indazolone couplers.
[0054] Useful examples of the magenta dye fourming coupler are disclosed in U.S. Patent
Nos. 2,600,788, 2,983,608, 3,062,653, 3,127,269, 3,311,476, 3,419,391, 3,519,429,
3,558,319, 3,582,322, 3,615,506, 3,834,908 and 3,891,445, West German Patent No. 1,810,464,
West German OLS Patent Nos. 2,408,665, 2,417,945, 2,418,959 and 2,424,467, Japanese
Patent Examined Publication No. 6031/1965, JP O.P.I. Nos. 74027/1974, 74028/1974,
129538/1974, 60233/1975, 159336/1975, 20826/1976, 26541/1976, 42121/1977, 58922/1977
and 55122/1978, and Japanese Patent Application No. 110943/1980.
[0055] As the cyan dye forming coupler there may be used known phenol or naphthol couplers
which include alkyl group-, acylamino group- or ureido group-substituted phenol couplers,
naphthol couplers formed from 5-aminonaphthol, and two-equivalent-type naphthol couplers
into which an oxygen atom as a split-off group is introduced.
[0056] Useful examples of the cyan dye forming coupler are disclosed in U.S. Patent Nos.
3,779,763, 2,895,826 and 3,488,193, JP O.P.I. Nos. 98731/1983, 37557/1985, 225155/1985,
222853/1985, 185335/1984, 2377448/1985, 52423/1978, 48237/1979, 27147/1981, 3142/1986,
96523/1986, 39045/1986, 50136/1986, 99141/1986 and 105545/1986, and Japanese Patent
Examined Publication Nos. 11572/1974.
[0057] The photographic light-sensitive material containing the silver halide emulsion of
the invention is produced by coating the emulsion layers and other necessary layers
thereof on a support which retains a good flatness and excellent dimensional stability
during its manufacture or processing. Materials usable as the support include nitrocellulose
film, cellulose ester film, polyvinyl acetal film, polystyrene film, polyethylene
terephthalate film, polycarbonate film, glass, paper, metals, polyolefin, and paper
laminated with, e.g., polyethylene or polypropylene. The support may, in order to
improve its adhesiveness to the photographic emulsion layers, be subjected to hydrophilic
surface treatment such as saponification treatment, corona discharge treatment, subbing
treatment and setting treatment.
[0058] The light-sensitive material containing the silver halide emulsion of the invention
may be processed according to the known photographic processing method with use of
the processing solutions described in Research Disclosure RD-17643, pp. 20-30 (Dec.
1978).
[0059] The photographic processing method may be either for black-and-white processing to
provide a silver image or for color photographic processing to obtain a color image.
The processing is carried out usually at a temperature of 18°C to 50°C, but it is
possible to process the light-sensitive material at a temperature of lower than 18°C
or higher than 50°C.
[0060] The photographic light-sensitive material containing the silver halide emulsion of
the invention may be used as various light-sensitive materials for color and black-and-white
photographic use, such as color negative film for camera use, color reversal film
for camera use, color photographic paper, color positive film, color reversal paper;
direct positive, heat-developable and silver dye bleach color light-sensitive materials;
and black-and-white photographic light-sensitive materials used as X-ray film, lithographic
film, microphotographic film, camera film for general use, and black-and-white photographic
paper.
[0061] The invention is suitable particularly for high-sensitivity color light-sensitive
materials. In multilayer color light-sensitive materials, it is preferable to apply
thereto a technique to change the order of the layer arrangement for making both high
sensitivity and high-quality image consistent with each other, a technique to have
an arbitrary color-sensitive emulsion layer composed of three identical color-sensitive
sub-layers for more improving the graininess, and a technique to provide a reflective
layer consisting of fine-grained silver halide underneath a high-sensitivity layer,
particularly a high-speed blue-sensitive layer, for further increasing the sensitivity.
Of these techniques, the technique to change the layer arrangement is described in
U.S. Patent Nos. 4,184,876, 4,129,446, 4,186,016, 4,186,011, 4,267,264, 4,173,479,
4,157,917 and 4,165,236, British Patent No. 1,560,965, 2,138,962 and 2,137,372, and
JP O.P.I. Nos. 177552/1984, 180556/1984 and 204038/1984. And the technique for the
reflective layer is described in JP O.P.I. No. 160135/1984.
EXAMPLES
[0062] The invention is illustrated further in detail below by the following examples, but
the invention is not limited thereto.
EXAMPLE 1
[0063] A monodispersed core/shell-type silver iodobromide emulsion (containing octahedral
regular crystals having a cubic equivalent grain diameter of 1.3µm, a grain diameter
variation coefficient of 18%, an average silver iodide content of 7.6 mol%: inside
high iodide-containing type) was prepared by a double-jet process with use of a device
disclosed in JP O.P.I. No. 160128/1987.
[0064] The above emulsion was divided into four equal parts, to three parts of them were
added the sulfur compounds or a gold compound as shown in Table-1, and each part was
kept at 60°C for one hour to form a catalytic nucleus. After that, 90 mg of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene
were added to each divided emulsion. The remaining part of the above emulsion was
used for comparison, and prepared adding thereto an equal amount of the above azaindene
compound without giving rise to the catalytic nucleus.
[0065] Next, after cooling the emulsion to 50°C, to the emulsion was added 3.0x10⁻⁶ mol
per mol of silver halide of sodium thiosulfate partially labelled with a radioactive
element ³⁵S as a reagent for producing silver sulfide, and the reaction rate thereof
was measured in accordance with a method for tracing the radioactive element.
[0066] Measurement of the reaction rate was made in accordance with the method described
in the previously mentioned publication J. Imaging Sci., vol.32, p.20 (1988).

[0067] The results of measurement of the rate of the silver sulfide producing reaction by
sodium thiosulfate are shown in Table-2.

[0068] As is apparent from Table-2, the silver sulfide producing reaction rates of the emulsions
in which a catalytic nucleus is given before adding sodium thiosulfate are faster
than the rate of the comparative emulsion.
EXAMPLE 2
[0069] To each of the same emulsions (Em-1 to Em-4) as in Example 1 was added spending one
hour the same amount of non-radioactive sodium thiosulfate instead of the radioactive
sodium thiosulfate in Example 1 to thereby effect the chemical ripening of the emulsions.
[0070] After completion of the chemical ripening, to each emulsion were added further appropriate
amounts of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene as a stabilizer, saponin as a
coating aid, and 2,4-dichloro-6-hydroxy-s-triazine as a hardener.
[0071] Each of the obtained emulsions was coated on a subbed polyester support and then
dried, whereby Samples 1 to 4 were prepared.
[0072] Each sample was exposed for 1/50 sec through a usual sensitometry wedge, and developed
for 30 seconds in the following developer solution at 35°C, then fixed, washed and
dried. After that, the photographic characteristics (sensitivity and fog) of each
processed sample were measured.
[0073] The obtained results are shown in Table-3.
[0074] The photographic sensitivity is expressed in terms of the reciprocal of the logarithm
of an exposure amount necessary to obtain an optical density of a fog value plus 0.1,
but in Table-3, the sensitivity of each sample is shown with a relative value to the
sensitivity of Sample 1 set at 100.

[0075] As is apparent from Table-3, Samples 2, 3 and 4, in which the emulsions of the invention
are used, have higher sensitivities than Sample 1.
EXAMPLE 3
[0076] An emulsion containing tabular grains was prepared by a similar double-jet process
as in Example 1. The emulsion grains had an average iodide content of 9.8 mol% (inside
high iodide-containing type), a cubic equivalent grain diameter of 1.2µm, a grain
diameter variattion coefficient of 20%, and diameter/thickness ratio of 4.3.
[0077] Next, the above emulsion was divided into two equal parts. One part was named Em-5
to be used as a comparative emulsion, and to the other was added 2.5x10⁻⁶ mol per
mol of silver halide of 5,5-dimethylrhodanine gold complex salt to thereby endow a
catalytic nucleus comprised of gold in a similar manner as in Example 1, and this
was named Em-6.
[0078] To Em-5 were added per mol of silver halide 170mg (total amount) of spectral sensitizing
dyes D-1, D-2 and D-3, 4x10⁻⁴ mol of ammonium thiocyanate, 3.7x10⁻⁶ mol of sodium
thiosulfate and 1.0x10⁻⁶ mol of chloroauric acid, and thus the emulsion was subjected
to optimum sulfur-gold sensitization at 50°C.
[0079] To Em-6 were added the same spectral sensiting dyes D-1 to D-3 and ammonium thiocyanate
in the same amounts as in above and then added 20mg of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene.
Next, 3.7x10⁻⁶ mol of sodium thiosulfate was added in one hour to thereby subject
the emulsion to optimum sulfur-gold sensitization at 50°C.
[0080] After that, 850mg of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene were further added
as a stabilizer to the emulsion. Spectral sensitizing dyes

[0081] Subsequently, to each of the above emulsions was added a coupler solution prepared
by dissolving per mol of silver halide 80g of a magenta coupler 1-(2,4,6-trichlorophenyl)-3-[3-(2,4-di-t-amylphenoxyacetamido)benzamido]-5-pyrazolone
and 2.5g of a colored magenta coupler 1-(2,4,6-trichlorophenyl)-4-(1-naphthylazo)-3-(2-chloro-5-octadecenylsuccinimidoanilino)-pyrazolone
by heating in a mixture of 120g of tricresyl phosphate and 240mg of ethyl acetate
and then dispersing the solution into 550ml aqueous 7.5% gelatin solution containing
5g of sodium triisopropylnaphthalenesulfonate.
[0082] Next, an appropriate amount of sodium 2-hydroxy-4,6-dichlorotriazine as a hardener
was added to each of the emulsions prepared above, and then the emulsion was so coated
on a subbed triacetate support as to have a coating weight of silver of 2.0g/m² and
then dried to thereby provide Samples 5 and 6.
[0083] Each of Samples 5 and 6 was exposed through an optical wedge in the usual manner,
processed in accordance with the following color processing steps, and then the photographic
characteristics of the processed samples were evaluated. The results are given in
Table 4.
[0084] The sensitivity shown in the table is a value relative to the sensitivity of Comparative
sample 5 set at 100.

[0085] The compositions of the processing solutions used in the above precedure are as follows:

[0086] As is apparent from Table-4, the sensitivity of Sample 6, in which the emulsion of
the invention is used, is higher than that of Comparative sample 5.