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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silver halide photographic emulsion and,
more particularly, to a photographic emulsion providing an extremely
contrasty negative image photographic property. Further, the present
invention relates to a process for forming images and, more particularly,
to a process for forming photographic images with an extremely contrasty
negative image.
2. Description of the Prior Art
U.S. Pat. No. 2,419,975 describes a process for obtaining a contrasty
negative image photographic property by adding a hydrazine compound. The
disclosure in this U.S. patent is that an extremely contrasty photographic
property of a gamma(.gamma.) of more than 10 can be obtained by adding a
hydrazine compound to a silver chlorobromide emulsion and developing the
emulsion with a developer having a pH as high as 12.8. However, a strongly
alkaline developer whose pH is near 13 tends to be oxidized by air and is
so unstable that it cannot be stored or used for a long time.
A super-contrasty photographic property of a gamma of more than 10 is
extremely useful for photographic reproduction of continuous tone images
through dot images which are useful for making printing plates regardless
of whether the image is negative or positive, or useful for reproduction
of line images. For such a purpose, the process comprising using a silver
chlorobromide photographic emulsion containing more than about 50 mol%,
preferably more than 75 mol%, of silver chloride and developing the
emulsion with a hydroquinone developer wherein the effective concentration
of sulfite ion is controlled to an extremely low level (usually not more
than about 0.1 mol/l) has generally been employed. However, this process
has the defect that, since the sulfite ion concentration in the developer
is low, the developer is extremely unstable and cannot be stored for
longer than about 3 days. In addition, a high sensitivity cannot be
obtained with a silver chlorobromide emulsion containing a slight amount
of silver bromide. Therefore, it has strongly been desired to obtain a
super-contrasty photographic property useful for the reproduction of dot
images or line images using a highly sensitive emulsion and a stable
developer.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a silver halide
photographic emulsion with which an extremely contrasty negative image
photographic property can be obtained using a stable developer.
Another object of the present invention is to provide a highly sensitive
silver halide photographic emulsion capable of providing an extremely
contrasty negative image photographic property.
A further object of the present invention is to provide a process for
forming photographic images having an extremely contrasty negative image
photographic property by using a stable developer.
Still a further object of the present invention is to provide a process for
forming photographic images capable of providing, with high sensitivity,
an extremely contrasty negative image photographic property.
Still a further object of the present invention is to provide a process for
forming extremely contrasty negative photographic images with extremely
less fog.
The above-described objects are attained by incorporating, in a silver
halide photographic emulsion which comprises substantially surface latent
image-type silver chlorobromide or silver chlorobromoiodide grains which
have a mean particle size of not more than about 0.7.mu. and in which the
silver chlorobromoiodide grains contain about 7 mol% or less silver iodide
based on the total silver halide amount with the silver halide
photographic emulsion containing a binder in an amount of not more than
about 250 g per mol of silver halide, and at least one compound
represented by the following general formula (I):
r.sup.1 nhnhcho (i)
wherein R.sup.1 represents an aryl group.
The above-described objects are attained in another embodiment by
developing, after image-wise exposure, a photographic light-sensitive
material containing at least one silver halide photographic emulsion layer
which comprises substantially surface latent image-forming type silver
chlorobromide or silver chlorobromoiodide grains which have a mean
particle size of about 0.7.mu. or less and in which the
silverchlorobromide grains contain up to about 7 mol% silver iodide and
which contains a binder in an amount of not more than about 250 g per mol
of silver halide, and containing the compound represented by the general
formula (I) above in the silver halide photographic emulsion layer or in
at least one other hydrophilic colloidal layer, using a developer
containing about 0.15 mol/l or more sulfite ion in the presence of a
benzotriazole compound at a pH of 11.0 to 12.3.
DETAILED DESCRIPTION OF THE INVENTION
In the general formula (I) above, R.sup.1 represents a monocyclic or
bicyclic aryl group. A suitable example of a monocyclic aryl group for
R.sup.1 is a phenyl group and a suitable example of a bicyclic aryl group
for R.sup.1 is a naphthyl group. The aryl group may be substituted with
one or more substituents which are not electron-attracting, such as alkyl
groups having 1 to 20 carbon atoms (which may be straight or branched
chained, e.g., methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl,
n-octyl, n-hexyl, tert-octyl, n-decyl, n-dodecyl, etc.), aralkyl groups
having 1 to 3 carbon atoms in the alkyl moiety thereof (e.g., benzyl,
phenethyl, etc.), alkoxy groups having 1 to 20 carbon atoms (in which the
alkyl moiety may be straight or branched chain, e.g., methoxy, ethoxy,
2-methylpropyloxy, etc.), amino groups which are mono- or disubstituted
with alkyl groups having 1 to 20 carbon atoms, aliphatic acylamino groups
having 2 to 21 carbon atoms or aromatic acylamino groups (e.g.,
acetylamino, octynylamino, benzoylamino, dimethylamino, etc.), etc.
Specific examples of the substituents represented by R.sup.1 include a
phenyl group, an .alpha.-naphthyl group, a .beta.-naphthyl group, a
p-tolyl group, an m-tolyl group, an o-tolyl group, a p-methoxyphenyl
group, an m-methoxyphenyl group, a p-dimethylaminophenyl group, a
p-diethylaminophenyl group, a p-(acetylamino)phenyl group, a
p-(heptylcarbonylamino)phenyl group, a p-(benzoylamino)phenyl group, a
p-benzylphenyl group, etc.
Of the above-described substituents represented by R.sup.1, monocyclic aryl
groups are preferred, with an unsubstituted phenyl group and a tolyl group
being particularly preferred.
The silver halide grains which can be used in the present invention are
substantially surface latent image-type silver halide grains. In other
words, they are not substantially internal latent image-type silver halide
grains. In the present invention, "substantially surface latent
image-type" is defined as the condition where, on developing, after
exposure for about 1 to about 1/100 second, according to Surface
Development (A) and Internal Development (B) to be described hereinafter,
the sensitivity obtained by Surface Development (A) is greater than that
obtained by Internal Development (B). Sensitivity as used herein is
defined as follows:
S=100/Eh
wherein S represents the sensitivity and Eh represents the exposure amount
necessary for obtaining a density just intermediate the maximum density
(D.sub.max) and the minimum density (D.sub.min), i.e., 1/2(D.sub.max
+D.sub.min).
Surface Development (A)
Development is conducted for 10 minutes at 20.degree. C. in a developer of
the following formulation.
______________________________________
N-Methyl-p-aminophenol (hemisulfate)
2.5 g
Ascorbic Acid 10 g
Sodium Metaborate (tetrahydrate)
35 g
Potassium Bromide 1 g
Water to make 1 l
______________________________________
Internal Development (B)
The light-sensitive material is processed for 10 minutes at about
20.degree. C. in a bleaching solution containing 3 g/l of potassium
ferricyanide and 0.0125 g/l of phenosafranine and, after washing for 10
minutes, developed for 10 minutes at 20.degree. C. in a developer of the
following formulation.
______________________________________
N-Methyl-p-aminophenol (hemisulfate)
2.5 g
Ascorbic Acid 10 g
Sodium Metaborate (tetrahydrate)
35 g
Potassium Bromide 1 g
Sodium Thiosulfate 3 g
Water to make 1 l
______________________________________
If the emulsion of the present invention were not of substantially surface
latent image-type, a positive image in addition to a negative image would
be obtained.
The silver halide grains which can be used in the present invention should
not have a mean particle size of greater than about 0.7.mu.. The term
"mean particle size" is a well known and easily understandable technical
term commonly used by those skilled in the art of silver halide
photography. Where the grains are spherical or can be considered to be
approximately spherical, the particle size means the particle diameter.
With cubic grains, the edge length.times..sqroot.4/.pi. is taken as the
particle size. The mean particle size is determined as an algebraic or
geometric mean based on the projected areas of particles. The details of a
method for determining mean particle size are described in C.E.K. Mees and
T.H. James, The Theory of the Photographic Process, 3rd Ed., pp. 36-43,
Macmillan Co., New York (1966).
If the mean particle size of the grains in the emulsion of the present
invention exceeds about 0.7.mu., a sufficient increase in contrast cannot
be obtained. A mean particle size of not more than 0.4.mu. is more
preferred. With the emulsion of the present invention, even though the
mean particle size of the grains is small, a high sensitivity can be
obtained.
Either of silver chlorobromide or silver chlorobromoiodide is used as the
silver halide. The amount of silver chloride is preferably not more than
about 80 mol% and, with silver chlorobromoiodide, the content of silver
iodide is preferably not more than about 7 mol%. The amount of silver
chloride is particularly preferably not more than about 50 mol%, and the
content of silver iodide is particularly preferably not more than about 6
mol%. In general, surface latent image-forming type silver halide
emulsions can be prepared by chemical sensitization such as sulfur
sensitization, reduction sensitization, noble metal sensitization or a
combination thereof.
The emulsion of the present invention must not contain more than about 250
g of a binder per mol of silver halide. A suitable amount of binder can
range from about 20 g to about 250 g per mol of silver halide. If more
than about 250 g of a binder is present in the emulsion, a contrasty
photographic property, in particular an extremely contrasty photographic
property of a gamma exceeding 10 as intended in the present invention,
cannot be obtained. A general tendency is that, the less the amount of the
binder in an emulsion, the greater the contrast. This is the effect based
on the amount of silver halide present in a silver halide emulsion layer
of a unit thickness. The influence of the amount of silver halide in the
present invention is different from that in known cases, and the effects
on gradation greatly change around the above-described amount of binder.
The effects of the present invention can be obtained only by using silver
halide grains having a mean particle size of not more than about 0.7.mu.
and by incorporating a greater amount of silver halide in an emulsion.
Gelatin can be advantageously used as the binder or protective colloid for
the photographic emulsion. However, other hydrophilic colloids can be used
as well. For example, proteins such as gelatin derivatives, graft polymers
between gelatin and other high polymers, albumin, casein, etc.; cellulose
derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose,
cellulose sulfates, etc.; saccharide derivatives such as sodium alginate,
starch derivatives, etc.; and various synthetic hydrophilic high polymers
of homo- or copolymers such as polyvinyl alcohol, partially acetaled
polyvinyl alcohol, poly-N-vinylpyrrolidone, polyacrylic acid,
polymethacrylic acid, polyacrylamide, polyvinylimidazole,
polyvinylpyrazole, etc., can be used as the binder or protective colloid
for the photographic emulsion.
Acid-processed gelatin may be used as well as lime-processed gelatin as the
gelatin. In addition, the hydrolyzed products of gelatin and
enzyme-decomposed products of gelatin are also suitable. Suitable gelatin
derivatives which can be used include those obtained by reacting gelatin
with various compounds such as acid halides, acid anhydrides, isocyanates,
bromoacetic acid, alkanesulfones, vinylsulfonamides, maleinimides,
polyalkylene oxides, epoxy compounds, etc. Specific examples thereof are
described in U.S. Pat. Nos. 2,614,928, 3,132,945, 3,186,846, 3,312,553,
British Patent Nos. 861,414, 1,033,189, 1,005,784, Japanese Patent
Publication No. 26,845/67.
As the above-described gelatin graft polymer, those which are obtained by
grafting homo- or copolymers of vinyl monomers such as acrylic acid,
methacrylic acid, the ester or amide derivatives thereof, acrylonitrile,
styrene, etc., to gelatin can be used. In particular, graft polymers with
a polymer having some compatibility with gelatin, such as polymers of
acrylic acid, methacrylic acid, acrylamide, methacrylamide, hydroxyalkyl
methacrylate, etc., are preferred. Examples thereof are described in U.S.
Pat. Nos. 2,763,625, 2,831,767, 2,956,884, etc. Typical synthetic
hydrophilic materials are described in, e.g., West German Pat. No.
2,312,708, U.S. Pat. Nos. 3,620,751, 3,879,205 and Japanese Patent
Publication No. 7,561/68.
Although the silver halide emulsions used in the present invention need not
necessarily be chemically sensitized, chemically sensitized silver halide
emulsions are preferred. Processes for chemical sensitization of the
silver halide emulsions which can be used include known sulfur
sensitization, reduction sensitization and noble metal sensitization
processes. These processes are described in references such as P.
Grafkides, Chimie et Phisique Photographique, Paul Montel, Paris (1967) or
Zelikmann, Making and Coating Photographic Emulsions, The Focal Press,
London (1964) or H. Frieser, Die Grundlagen der photographischen Prozesse
mit Silberhalogeniden, Akademische Verlagsgesellschaft, (1968) In the
noble metal sensitization processes, a gold sensitization process is a
typical process where gold compounds or mainly gold complexes are used.
However, if the gold sensitizing agents are used in an amount effective to
carry out chemical sensitization, a softening of the tone occurs.
Accordingly, gold sensitization is not as suitable for the present
invention. No difficulties occur using complexes of noble metals other
than gold, such as those of platinum, palladium or iridium, etc. A
reduction sensitization process may be used if the process does not
generate a fog which causes practical difficulties. However, reduction
sensitization is not as preferred because control of the process
conditions is difficult. A preferred chemical sensitization process for
the present invention is the use of a sulfur sennsitization process. In
the present invention, it is preferred for the silver halide emulsions
substantially not to be subjected to gold sensitization and it is
particularly preferred for the silver halide emulsions to be chemically
sensitized using only a sulfur sensitization process.
Examples of sulfur sensitizing agents which can be used include not only
sulfur compounds present in the gelatin per se but also various sulfur
compounds such as thiosulfates, thioureas, thiazoles or rhodanines, etc.
Examples of suitable sulfur compounds are described in U.S. Pat. Nos.
1,574,944, 2,410,689, 2,278,947, 2,728,668 and 3,656,955. Typical examples
of reduction sensitizing agents which can be used include stannous salts,
amines, formamidine sulfinic acid and silane compounds, etc., as described
in U.S. Pat. Nos. 2,487,850, 2,518,698, 2,983,609, 2,983,610 and
2,694,637. Complex salts of Group VIII metals in the Periodic Table, such
as platinum, iridium or palladium, etc., can be used for noble metal
sensitization and examples thereof are described in U.S. Pat. No.
2,448,060 and British Patent No. 618,061, etc.
Specific examples of compounds represented by the general formula (I) above
are illustrated below. However, the present invention is not to be
construed in any way as being limited to these specific examples.
##STR1##
The compounds represented by the general formula (I) can be synthesized by
reacting hydrazines with formic acid or a formic acid ester. Starting
material hydrazines such as
##STR2##
are commercially available and hydrazines of the formula
##STR3##
where R represents an alkyl group can be synthesized by reduction of a
p-nitrophenyl hydrazine. The reaction can be conducted without a solvent
and at a temperature of about 0.degree. C. to about 100.degree. C.,
preferably 0.degree. C. to 70.degree. C. A suitable molar ratio of the
hydrazine to formic acid is about 1:1 or more.
A specific example of the synthesis of the compounds represented by the
general formula (I) is shown below. Unless otherwise indicated herein, all
parts, percents, ratios and the like are by weight.
Synthesis of Compound 2
110 g of formic acid was stirred at 25.degree.-30.degree. C., and 107 g of
p-tolylhydrazine was added thereto incrementally. After completion of the
addition, the mixture was heated at 50.degree. C. for 20 minutes under
stirring. After cooling with ice, the crystals formed were filtered out,
then recrystallized from 550 ml of acetonitrile. Thus, 54.5 g of colorless
needlelike crystals having a melting point of 176.degree.-177.degree. C.
was obtained.
The compound of the general formula (I) is usually incorporated in the
photographic emulsion of the present invention in an amount of about
10.sup.-4 to about 10.sup.-1 mol/mol Ag. An amount of 3.times.10.sup.-3 to
5.times.10.sup.-2 mol/mol Ag is preferred, with the amount of
5.times.10.sup.-3 to 5.times.10.sup.-2 mol/mol Ag being particularly
preferred.
The addition of the compound represented by the general formula (I) can be
carried out using conventional methods of adding additives to photographic
emulsions. For example, the compound can be added to the emulsions as an
aqueous solution having a suitable concentration where the compound is
water-soluble or as a solution in an organic solvent compatible with water
such as alcohols, ethers, glycols, ketones, esters or amides which do not
adversely influence the photographic properties where the compound is
insoluble or poorly soluble in water. Known methods similar to the
addition of water-insoluble couplers (the so-called oil-soluble couplers)
to emulsions as a dispersion can be used too.
The compounds of the general formula (I) to be used in the present
invention are characterized in that, when incorporated in a silver halide
emulsion, the effect of making an emulsion contrasty and the sensitizing
effect are maintained stable with the lapse of time. From this standpoint,
the compounds of the general formula (I) are markedly superior to known
compounds in producing a contrasty emulsion such as unsubstituted
hydrazine salts, alkoxycarbonylhydrazines, etc.
The photographic emulsions of the present invention can be prepared by
processes described in P. Grafkides, Chimie et Physique Photographique,
Paul Montel Co., Paris (1967), G. F. Duffin, Photographic Emulsion
Chemistry, The Focal Press, London (1966) and V. L. Zelikman et al.,
Making and Coating Photographic Emulsions, The Focal Press, London (1964).
Namely, they may be prepared by any of an acid process, a neutral process
or an ammonia process. Further, a single-jet process, a double-jet process
or a combination thereof may be used as a process of reacting soluble
silver salts with soluble halide salts.
A process of forming grains under conditions where an excess of silver ion
(the so-called reverse mixing process is present can also be used. One
type of double-jet mixing process which can be used is a process which
comprises holding the pAg constant in a liquid phase where silver halide
is formed, namely, the so-called controlled double-jet process. According
to this process, silver halide emulsions having a regular crystal form and
a uniform grain size can be obtained.
The silver halide grains in the photographic emulsions of the present
invention may have a comparatively wide grain size distribution. However,
a narrow grain size distribution is preferred. It is particularly
preferred for 90% by weight or number based on the total silver halide
grains to have a grain size in a range of .+-.40% of the average grain
size (generally, such an emulsion is called a monodispersed emulsion).
The silver halide grain in the photographic emulsions of the invention may
have a regular form such as a cubic form or an octahedral form. Further,
they may have an irregular crystal form such as that of a sphere or a
plate, etc., or they may have a complex form of these crystal forms.
The silver halide grains may have a structure in which the inner part and
the outer part are each composed of a different phase or may have a
structure which is uniform throughout.
In forming silver halide grains or during physical ripening, cadmium salts,
zinc salts, lead salts, thalium salts, iridium salts or complexes thereof,
rhodium salts or complexes thereof, or iron salts or complexes thereof,
etc., may also be present.
Two or more silver halide emulsions produced separately may be used by
mixing them, if desired.
The soluble salts are generally removed from the emulsion after formation
of the precipitates or after physical ripening. A well known noodle water
washing process which is carried out after gelling of the gelatin may be
used for this purpose. Further, flocculation processes utilizing inorganic
salts containing a polyvalent anion, such as sodium sulfate, anionic
surface active agents, anionic polymers (such as polystyrene sulfonic
acid) or gelatin derivatives (such as aromatic acylated gelatins,
aliphatic acylated gelatins or aromatic carbamoylated gelatins, etc.) can
be used. The removal of the soluble salts may be omitted, if desired.
Although emulsions which are not chemically sensitized (a so-called
primitive emulsion) may be used as the silver halide emulsions, they are
usually chemically sensitized.
The silver halide emulsions of the present invention may contain
anti-fogging agents. Such emulsions are preferred in order to attain the
objects of the present invention. Examples of preferred anti-fogging
agents which can be used in the emulsions of the present invention include
1,2,3-triazole, compounds, 3-mercapto substituted 1,2,4-triazole
compounds, 2-mercaptobenzimidazole compounds (which should be
unsubstituted with a nitro group), 2-mercaptopyrimidines,
2-mercaptobenzothiazoles, benzothiazolium compounds (for example,
N-alkylbenzothiazolium halide or N-allylbenzothiazolium halide) and
2-mercapto-1,3,4-thiadiazoles, etc.
Particularly advantageous anti-fogging agents for use in the present
invention are benzotriazoles. The benzene ring of the benzotriazoles may
be substituted with one or more substituents selected from an alkyl group
(e.g., a methyl group, a heptyl group, etc.), a halogen atom (e.g., a
chlorine atom, a bromine atom, etc.), an alkoxy group (e.g., a methoxy
group, etc.), an acyl group (e.g., an acetyl group, a benzoyl group,
etc.), an acylamino group (e.g., an acetylamino group, a capryloylamino
group, a benzoylamino group, a benzenesulfonylamino group, etc.), a
carbamoyl group (e.g., a methylcarbamoyl group, a phenylcarbamoyl group,
etc.), a sulfamoyl group (e.g., a methylsulfamoyl group, a phenylsulfamoyl
group, etc.), an aryl group (e.g., a phenyl group, a tolyl group, etc.),
etc. The alkyl moiety in these substituents preferably contains 12 or less
carbon atoms, particularly preferably 3 or less carbon atoms. In addition,
the benzotriazole compounds may be substituted with a halogen atom (e.g.,
a chlorine atom, a bromine atom, etc.) in the 1-position thereof.
Benzotriazoles, which are particularly effective anti-fogging agents for
the present invention, can be represented by the following general formula
(II):
##STR4##
wherein Y represents an alkyl group having 1 to 12 carbon atoms (for
example, a methyl group, a heptyl group or a decyl group), a halogen atom
(for example, a chlorine atom or a bromine atom), an alkoxy group having 1
to 12 carbon atoms (for example, a methoxy group or a lauryloxy group), an
acyl group having 2 to 13 carbon atoms (for example, an acetyl group or a
benzyl group), an acylamino group having 2 to 13 carbon atoms (for
example, an acetylamino group, a caproylamino group, a benzoylamino group
or a benzenesulfonylamino group), a carbamoyl group which may be
substituted with an aliphatic or aromatic group having up to 12 carbon
atoms (for example, a methylcarbamoyl group or a phenylcarbamoyl group), a
sulfamoyl group which may be substituted with an aliphatic or aromatic
group having up to 12 carbon atoms (for example, a methylsulfamoyl group
or a phenylsulfamoyl group) or a monocyclic or bicyclic aryl group (for
example, a phenyl group). Y does not represent a nitro group. n represents
0, 1 or 2. Where n is 2, Y may be the same or different. The alkyl moiety
in the Y group preferably has 1 to 3 carbon atoms. X represents a hydrogen
atom, a halogen atom (for example, a chlorine atom or a bromine atom) or
an acyl group having 1 to 10 carbon atoms (for example, an acetyl group or
a propionyl group).
Examples of suitable compounds represented by the general formula (II)
which can be used in this invention are described below. However, the
present invention is not to be construed as being limited to these
compounds.
##STR5##
The benzotriazole compounds represented by the general formula (II) can be
synthesized by reference to, for example, the disclosure in Organic
Synthesis, Vol. 3, page 106; Journal of the Chemical Society, Vol. 119,
pages 2088-94 (1921); ibid., pages 1143-53 (1931) or ibid., Section C,
pages 1474-78 (1969), etc.
In order to conduct the development in the process of the present invention
in the presence of the benzotriazoles, they may be incorporated in the
light-sensitive material, the light-sensitive material may be treated with
a solution of the benzotriazole compound before development or the
benzotriazole compound may be added to a developer.
In the image-forming process of the present invention, the benzotriazole
compound may be incorporated, suitably, in one or more hydrophilic colloid
layers of the photographic material. The benzotriazole compound may be
incorporated in a light-sensitive emulsion layer or may be incorporated in
a non-light-sensitive hydrophilic colloid layer. Where the benzotriazole
compound is incorporated into a light-sensitive emulsion layer, although
it is preferred for the emulsion layer to which such is added to be a
silver halide emulsion layer essentially of the type used in the present
invention, it may be incorporated into another type of silver halide
emulsion layer. The benzotriazole compound may be incorporated into a
single silver halide emulsion layer or may be incorporated into two or
more silver halide emulsion layers. Where the benzotriazole compound is
incorporated into a non-light-sensitive hydrophilic colloid layer, the
layer may be any of an intermediate layer, a protective layer, a back
layer and a layer between the silver halide emulsion layer and the support
(under layer). The benzotriazole compound, however, is preferably
incorporated into a layer adjacent the silver halide emulsion layer as
used in the present invention.
In the image-forming process of the present invention, the benzotriazole
compound may be added to the developing solution. When the benzotriazole
compound is added to the developing solution, it is added as a solution in
a solvent compatible with water, such as an alcohol (for example, methanol
or ethanol), a ketone (for example, acetone or methyl ethyl ketone) or an
ester (for example, ethyl acetate) or as an aqueous solution during or
after preparation of the developing solution. These solvents may be used,
as desired, in an alkaline state or an acid state.
The photographic materials may be processed using a bath containing a
benzotriazole compound before development and after exposure to light.
A preferred amount of the benzotriazole compound in the photographic
emulsion ranges from about 10.sup.-4 to 10.sup.-1 mol/mol Ag. An amount of
10.sup.-3 to 3.times.10.sup.-2 mol/mol Ag is particularly preferred.
Where the benzotriazole compound is incorporated into a non-light-sensitive
hydrophilic colloid layer, a benzotriazole compound is preferably present
in the above-described amount based on the amount of the silver salt in
the same area.
Where the benzotriazole compound is added to the developing solution, an
amount of about 10.sup.-6 to about 10.sup..sup.-1 mol/liter of the
developing solution is preferred, particularly an amount of
3.times.10.sup.-5 to 3.times.10.sup.-2 mol/liter of the developing
solution is preferred.
Addition of a small amount of an iodide (e.g., potassium iodide, etc.)
after formation of the silver halide grains, before chemical ripening,
after chemical ripening, or before coating serves to enhance further the
effects of the present invention. Such iodide is suitably added in an
amount of about 10.sup.-4 to about 10.sup.-2 mol/mol Ag.
The photographic emulsions of the present invention may be spectrally
sensitized with methine dyes or the like. Examples of suitable dyes which
can be used include cyanine dyes, merocyanine dyes, complex cyanine dyes,
complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl
dyes and hemioxonol dyes. Particularly useful dyes are cyanine dyes,
merocyanine dyes and complex merocyanine dyes. These dyes may contain
nuclei commonly used as basic heterocyclic nuclei in cyanine dyes. Namely,
a pyrroline nucleus, an oxazoline nucleus, a thiazoline, nucleus, a
pyrrole nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole
nucleus, an imidazole nucleus, a tetrazole nucleus or a pyridine nucleus;
nuclei wherein an alicyclic hydrocarbon ring is fused to the
above-described nuclei; and nuclei wherein an aromatic hydrocarbon ring is
fused to the above-described nuclei, such as an indolenine nucleus, a
benzindolenine nucleus, an indole nucleus, a benzoxazole nucleus, a
naphthoxazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus,
a benzoselenazole nucleus, a benzimidazole nucleus or a quinoline nucleus,
etc., can be employed. These nuclei may be substituted with substituents
on the carbon atoms thereof.
The merocyanine dyes or complex merocyanine dyes may contain 5- or
6-membered heterocyclic rings such as a pyrazolin-5-one nucleus, a
thiohydantoin nucleus, a 2-thioxazolidin-2,4-dione nucleus, a
thiazolidin-2,4-dione nucleus, a rhodanine nucleus or a thiobarbituric
acid nucleus, etc.
Useful sensitizing dyes are those described in German Patent No. 929,080,
U.S. Pat. Nos. 2,231,658, 2,493,748, 2,503,776, 2,519,001, 2,912,329,
3,656,959, 3,672,897 and 3,694,217, British Patent No. 1,242,588 and
Japanese Patent Publication No. 14030/69.
These sensitizing dyes may be used individually or as a combination
thereof. Combinations of sensitizing dyes are often used for the purpose
of supersensitization. Typical examples of such combinations are described
in U.S. Pat. Nos. 2,688,545, 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
Publication No. 4936/68.
The emulsions may contain dyes which do not have a spectral sensitization
function themselves or materials which do not substantially absorb visible
light but give rise to a supersensitization together with the sensitizing
dyes. For example, aminostilbene compounds substituted with a
nitrogen-containing heterocyclic group (such as those described in, for
example, U.S. Pat. Nos. 2,933,390 and 3,635,721), aromatic organic
acid-formaldehyde condensation products (for example, those described in
U.S. Pat. No. 3,743,510), cadmium salts and azaindene compounds may be
employed. The combinations described in U.S. Pat. Nos. 3,615,613,
3,615,641, 3,617,295 and 3,635,721 are particularly useful.
The photographic emulsions of the present invention may contain
water-soluble dyes as filter dyes or for the purpose of preventing
irradiation or for other purposes. Examples of such dyes include oxonol
dyes, hemioxonol dyes, styryl dyes, merocyanine dyes, cyanine dyes and azo
dyes. Above all, oxonol dyes, hemioxonol dyes and merocyanine dyes are
particularly preferred. Examples of these dyes which can be used include
those described in British Pat. Nos. 584,609 and 1,177,429, Japanese
Patent Applications (OPI) No. 85130/73, 99620/64 and 114420/64, and U.S.
Pat. Nos. 2,274,782, 2,533,472, 2,956,879, 3,148,187, 3,177,078,
3,247,127, 3,540,887, 3,575,704, 3,653,905 and 3,718,472.
The photographic emulsions of the present invention may contain inorganic
or organic hardening agents. For example, chromium salts (chrome alum or
chromium acetate, etc.), aldehydes (formaldehyde, glyoxal or
glutaraldehyde, etc.), N-methylol compounds (dimethylolurea or
methyloldimethylhydantoin, etc.), dioxane derivatives
(2,3-dihydroxydioxane, etc.), active vinyl compounds
(1,3,5-triacryloylhexahydro-s-triazine or bis(vinylsulfonyl) methyl ether,
etc.), active halogen compounds (2,4-dichloro-6-hydroxy-s-triazine, etc.),
mucohalic acids (mucochloric acid or mucophenoxychloric acid, etc.),
isoxazoles, dialdehyde starch and 2-chloro-6-hydroxytriazinyl gelatin,
etc., which may be used individually or in a combination of two or more
thereof. Examples of suitable hardening agents include those described in
U.S. Pat. Nos. 1,870,354, 2,080,019, 2,726,162, 2,870,013, 2,983,611,
2,992,109, 3,047,394, 3,057,723, 3,103,437, 3,321,313, 3,325,287,
3,362,827, 3,539,644 and 3,543,292, British Patent Nos. 676,628, 825,544
and 1,270,578, German Patent Nos. 872,153 and 1,090,427 and Japanese
Patent Publication Nos. 7133/59 and 1872/71.
The photographic emulsions of the present invention may contain various
known surface active agents for various purposes, e.g., as a coating aid,
for preventing the generation of electrostatic charges, for improving
lubricating properties, for emulsifying or dispersing, for preventing
adhesion and for improving the photographic properties (for example,
acceleration of development, hardening or sensitization), etc.
Examples of suitable surface active agents include nonionic surface active
agents such as saponin (steroid type), alkylene oxide derivatives (for
example, polyethylene glycol, polyethylene glycol-polypropylene glycol
condensation products, polyethylene glycol alkyl or alkylaryl ethers,
polyethylene glycol esters, polyethylene glycol sorbitan esters,
polyalkylene glycol alkylamines or amides or polyethylene oxide addition
products of silicones, etc.), glycidol derivatives (for example,
alkenylsuccinic acid polyglycerides or alkylphenol polyglycerides),
aliphatic acid esters of polyhydric alcohols, alkyl esters of saccharides,
urethanes of saccharides or ethers of saccharides, etc.; anionic surface
active agents containing acid groups such as a carboxyl group, a sulfo
group, a phospho group, a sulfate group or a phosphate group, etc., such
as triterpenoid type saponin, alkylcarboxylic acid salts, alkyl
sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl
sulfates, alkyl phosphates, N-acyl-N-alkyltaurines, sulfosuccinic acid
esters, sulfoalkylpolyoxyethylene alkylphenyl ethers or polyoxyethylene
alkyl phosphoric acid esters, etc.; amphoteric surface active agents such
as amino acids, aminoalkylsulfonic acids, aminoalkyl sulfates or
phosphates, alkylbetaines, amine imides or amine oxides, etc.; and
cationic surface active agents such as alkylamine salts, aliphatic or
aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts
such as pyridinium or imidazolidium salts, etc., or aliphatic or
heterocyclic phosphonium or sulfonium salts, etc.
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