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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming-process and,
particularly, to an image forming process which has a photographic
characteristic of providing a very contrasty negative image and which are
suitable for reproduction of precise line drawings and an image forming
process using the same.
2. Description of the Prior Art
A process which comprises adding hydrazine compounds to silver halide
photographic emulsions to obtain a photographic characteristic of a
contrasty negative image is described in U.S. Pat. No. 2,419,975. This
patent discloses that a very contrasty photographic characteristic of a
gamma (.gamma.) of more than 10 is obtained when hydrazine compounds are
added to silver bromochloride emulsions and the emulsions are developed
using a developing solution having a pH of as high as 12.8. However, a
strongly alkaline developing solution having a pH near 13 is unstable
because it is easily oxidized by air and, consequently, it cannot be
stored or used for a long period of time. Further, silver bromochloride
emulsions generally have a low sensitivity and are unsuitable for uses
where a high sensitivity is required.
The supercontrasty photographic characteristic of a gamma of more than 10,
for either a negative image or a positive image, is very useful for
photographic reproduction of halftone images or reproduction of line
drawing images by means of dot images useful for printing plates. In the
past, for such a purpose, a process which comprises using silver
bromochloride photographic emulsions having a silver chloride content of
more than 50 mol% and preferably more than 75 mol% and developing such
with a hydroquinone developing solution having a very low sulfite ion
concentration (generally, less than about 0.1 mol/liter) has been used.
However, in this process, the developing solution is very unstable because
it has a low sulfite ion concentration and, consequently, the developing
solution cannot be stored for 3 days or more. Further, since silver
bromochloride emulsions having a comparatively high silver chloride
content are used in this process, a high sensitivity cannot be obtained.
Accordingly, the ability to obtain a supercontrasty photographic
characteristic useful for reproduction of dot images or line drawings
using high speed emulsions and stable developing solutions has been very
much desired.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide silver halide
photographic emulsions having a photographic characteristic which is
capable of providing a very contrasty negative image of a .gamma. of more
than about 10 using a stable developing solution.
A second object of the present invention is to provide high speed silver
halide photographic emulsions which have a photographic characteristic
providing a very contrasty negative image of a .gamma. of more than about
10.
A third object of the present invention is to provide a process for forming
photographic images having a photographic characteristic of a very
contrasty negative image using a stable developing solution containing
sulfite ion.
A fourth object of the present invention is to provide a photographic image
forming process in which a photographic characteristic of a very contrasty
negative image in a high sensitivity can be obtained.
A fifth object of the present invention is to provide a process for forming
very contrasty negative photographic images with a low degree of fog.
These and other objects of the present invention in one embodiment are
attained with a silver halide photographic emulsion comprising
substantially surface latent image type monodispersed silver bromide or
silver iodobromide grains having an average particle size of about 0.7
micron or less and in which the amount of silver iodide in the silver
iodobromide grains is about 10 mol% or less of the silver halide and
binder in an amount of about 250 g or less per mol of the silver halide,
and a compound represented by the following general formula (I):
R.sup.1 NHNHCOR.sup.2 (I)
wherein R.sup.1 represents a monocyclic or bicyclic aryl group and R.sup.2
represents a hydrogen atom, a straight or branched chain alkyl group
having 1 to 3 carbon atoms or a phenyl group.
In another embodiment of this invention, this invention provides a
photographic light-sensitive material comprising a support having thereon
at least one silver halide photographic emulsion layer comprising
substantially surface latent image type silver bromide or silver
iodobromide grains containing up to about 10 mol% silver iodide, wherein
the average grain size of the silver halide grain is about 0.7 microns or
less, with the silver halide photographic emulsion containing a binder in
an amount of about 250 g or less per mol of silver halide, with the silver
halide photographic emulsion layer or at least one other hydrophilic
colloid layer on the support containing a compound represented by the
general formula (I) above.
In an additional embodiment of this invention, this invention provides an
image forming process which comprises imagewise exposing to light a
photographic light-sensitive material as described above and developing
the photographic light-sensitive material with a developing solution
containing at least one dihydroxybenzene in an amount of about 0.05
mol/liter to about 0.5 mol/liter and about 0.15 mol/liter or more of
sulfite ion and having a pH of about 11.0 to about 12.3 wherein the amount
of the compound of the formula (I) is 10.sup.-4 to 10.sup.-1 mol/molAg.
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, iso-propyl, n-butyl, iso-butyl,
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-methylpropyoxy, 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.
R.sup.2 represents a hydrogen atom, an alkyl group having 1 to 3 carbon
atoms which may be straight or branched chained (e.g., methyl, ethyl,
n-propyl and iso-propyl) or a phenyl group. It is preferred for the alkyl
group to be unsubstituted. The phenyl group may be substituted with one or
more substituents which preferably are electron attracting groups such as
a halogen atom (chlorine or bromine, etc.), a cyano group, a
trifluoromethyl group, a carboxyl group or a sulfo group, etc.
Examples of suitable 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-(caproylamino)phenyl group, a p-(benzoylamino)phenyl group and a
p-benzylphenyl group, etc.
Examples of suitable substituents represented by R.sup.2 other than a
hydrogen atom include a methyl group, an ethyl group, an n-propyl group,
an isopropyl group, a phenyl group, a 4-chlorophenyl group, a
4-bromophenyl group, a 3-chlorophenyl group, a 4-cyanophenyl group, a
4-carboxyphenyl group, a 4-sulfophenyl group, a 3,5-dichlorophenyl group
and a 2,5-dichlorophenyl group.
Monocyclic aryl groups are preferred for R.sup.1 and an unsubstituted
phenyl group and a tolyl group are particularly preferred for R.sup.1.
A hydrogen atom, a methyl group and phenyl groups which may be substituted
are preferred for R.sup.2. A hydrogen atom is particularly preferred for
R.sup.2.
Preferred compounds represented by the general formula (I) are those
compounds represented by the following general formula (Ia):
R.sup.1 NHNHCOR.sup.12 (Ia)
wherein R.sup.1 has the same meaning as described in the general formula
(I) and R.sup.12 represents a hydrogen atom, a methyl group, an
unsubstituted phenyl group or a phenyl group substituted with one or more
electron attracting groups (e.g., as described above).
Particularly preferred compounds represented by the general formula (Ia)
are those compounds represented by the general formula (Ib):
R.sup.11 NHNHCHO (Ib)
wherein R.sup.11 represents an unsubstituted phenyl group, a p-tolyl group
or an m-tolyl group.
The above-described objects of the present invention concerning the image
forming process are attained by imagewise exposing to light a photographic
material comprising a support having thereon at least one silver halide
photographic emulsion layer composed of substantially surface latent image
type silver halide grains having an average particle size of about 0.7
micron or less in which the amount of silver iodide in the silver
iodobromide grains is about 10 mol% or less and a binder in an amount of
about 250 g or less per mol of silver halide, wherein the silver halide
photographic emulsion layer or at least one of the other hydrophilic
colloid layers present on the support contains a compound represented by
the general formula (I) above, and developing the imagewise exposed
photographic material using a developing solution containing at least one
dihydroxybenzene in an amount of about 0.05 mol/liter to about 0.5
mol/liter and about 0.15 mol/liter or more of sulfite ion at a pH of about
11.0 to about 12.3 wherein the amount of the compound of the formula (I)
is 10.sup.-4 to 10.sup.-1 mol/molAg.
In this embodiment of this invention, preferred compounds of the general
formula (I) are the compounds of the general formula (Ia) described above
and particularly preferred compounds of the general formula (I) are the
compounds of the general formula (Ib) described above.
Further, a preferred dihydroxybenze used in this invention is hydroquinone.
The silver halide grains used in the present invention are substantially
surface latent image type silver halide grains. In other words, the silver
halide grains are not of the substantially internal latent type. The term
"substantially surface latent image type" is used in the description of
the present invention to describe the situation in which the sensitivity
resulting from the following surface development (A) is higher than that
resulting from the following internal development (B) when the emulsion is
subjected to surface development (A) or internal development (B) after
exposure to light for 1 to 0.01 second, wherein the sensitivity is defined
by the following relationship:
S=100/Eh
where S represents the sensitivity and Eh represents the amount of exposure
necessary to obtain an average density:
1/2(D.sub.max +D.sub.min).
Surface Development (A)
The emulsion is developed at 20.degree. C. for 10 minutes in a developing
solution having the following composition.
______________________________________
N-Methyl-p-aminophenol (hemisulfate)
2.5 g
Ascrobic Acid 10 g
Sodium Metaborate (tetrahydrate)
35 g
Potassium Bromide 1 g
Water to make 1 l
______________________________________
Internal Development (B)
The emulsion is processed at about 20.degree. C. for 10 minutes in a
bleaching solution containing 3 g/liter of potassium ferricyanide and
0.0125 g/liter of phenosafranine, washed with water for 10 minutes and
developed at 20.degree. C. for 10 minutes in a developing solution having
the following composition.
______________________________________
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 emulsions of the present invention are not substantially surface
latent image type emulsions, a positive image tends to be obtained as well
as a negative image.
The average grain size of the silver halide grains used in the present
invention should not be larger than about 0.7.mu., preferably 0.4.mu. or
less. The term "average grain size" is well known and is generally used by
persons skilled in the silver halide photographic field. The grain size
means the diameter of the grains in cases of grains which are spherical or
nearly spherical. Where the particle is cubic, the grain size means the
length of the edge.times..sqroot.4/.pi.. The average is calculated by an
algebraic average or a geometric average based on a projected area of the
particle. Details of calculations of the average grain size are described
in C. E. K. Mees and T. H. James, The Theory of the Photographic Process,
3rd Ed., pages 36-43, Macmillan Co., New York (1966).
In the emulsions of the present invention, if the average grain size
exceeds about 0.7 .mu., a high contrast of a .gamma. of more than about 10
cannot be obtained. It is further preferred for the average grain size of
the silver halide grains in the emulsions of the present invention to be
less than 0.4 .mu.. A characteristic of the emulsions of the present
invention is a high sensitivity in spite of a small average grain size.
The silver halide which is used in this invention is silver bromide or
silver iodobromide containing about 10 mol% or less silver iodide. With
the silver iodobromide, it is further preferred for the silver iodide
content to not exceed 6 mol%. The emulsions of the present invention are
advantageous, because a remarkably higher sensitivity than in cases of
silver bromochloride used in prior art lith-type supercontrasty sensitive
materials is obtained by use of such a silver halide.
The emulsions of the present invention should not contain more than about
250 g of binder per mol of silver halide. A suitable amount of the binder
can range from about 20 g to about 250 g per mol of silver halide. If the
emulsions contain a binder in an amount of more than about 250 g per mol
of silver halide, it is not possible to obtain a contrasty tone and,
particularly, to obtain an extremely contrasty photographic characteristic
of a .gamma. of more than about 10 which is an object of the present
invention. Although a general tendency for the photographic emulsions is
that the lower is the amount of the binder in the emulsions, the more
contrasty is the tone obtained, such a tendency is an effect based on the
amount of silver halide included in an emulsion layer per unit thickness
and unit area. The influence of the amount of silver halide in the present
invention is different from that in known cases, and the influence upon
gradation changes greatly in an amount near the above-described limit.
This change is shown in Example 5 below. The effect of the present
invention is only obtained when the average grain size does not exceed
about 0.7.mu. and the amount of silver halide in the emulsion is high.
Although gelatin is generally and advantageously used as the binder or
protective colloid for the photographic emulsions of this invention, other
hydrophilic colloids may also be used in this invention. For example, it
is possible to use proteins such as gelatin derivatives, graft polymers of
gelatin with other high molecular weight materials, albumin or casein,
etc., cellulose derivatives such as hydroxyethylcellulose,
carboxymethylcellulose or cellulose sulfates, etc., saccharide derivatives
such as sodium alginate or starch derivatives, etc., and synthetic
hydrophilic high molecular weight materials such as homo- or copolymers
such as polyvinyl alcohol, partially acetaled polyvinyl alcohol,
poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid,
polyacrylamide, polyvinylimidazole or polyvinylpyrazole, etc.
Not only lime processed gelatin but also acid treated gelatin may be used
as the gelatin. Further, gelatin hydrolysis products or enzymatic gelatin
decomposition products may be used. Those gelatin derivatives which are
produced by reacting gelatin with various compounds such as acid halides,
acid anhydrides, isocyanates, bromoacetic acid, alkanesultones,
vinylsulfonamides, maleinimide compounds, polyalkylene oxides or epoxy
compounds, etc., may be used. Examples of these gelatin derivatives are
described in, for example, U.S. Pat. Nos. 3,614,928, 3,132,945, 3,186,846
and 3,312,553, British Pat. Nos. 861,414, 1,033,189 and 1,005,784 and
Japanese Patent Publication 26845/67.
As the above-described gelatin graft polymers, it is possible to use those
produced by grafting gelatin with homo- or copolymers of vinyl monomers
such as acrylic acid, metahcrylic acid, the esters thereof, the amides
thereof, acrylonitrile or styrene, etc. Graft polymers prepared from
polymers which are compatible with gelatin, such as polymers of acrylic
acid, methacrylic acid, acrylamide, methacrylamide or hydroxyalkyl
methacrylates, etc., are particularly preferred. Examples of graft
polymers are described in U.S. Pat. Nos. 2,763,625, 2,831,767 and
2,956,884, etc. Typical synthetic hydrophilic high molecular weight
materials are those described in German Patent Application (OLS)
2,312,708, U.S. Pat. Nos. 3,620,751 and 3,879,205 and Japanese Patent
Publication 7561/68.
Although the silver halide emulsions used in the present invention need not
necessarily be chemically sensitized, chemically sensitizied 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.
Glafkides, 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. A
reduction sensitization process may be used if the process does not
generate a fog which causes practical difficulties.
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, 2,278,668 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 Pat. No. 618,061, etc.
Examples of specific compounds represented by the general formula (I) which
can be used in this invention are shown below. The present invention,
however, is not to be construed as being limited to these specific
compounds.
##STR1##
The compounds represented by the general formula (I) can be synthesized by
reacting hydrazines with formic acid or by reacting hydrazines with acyl
halides. Starting material hydrazines such as
##STR2##
and
##STR3##
are commercially available and hydrazines of the formula
##STR4##
where R represents an alkyl group can be synthesized by reduction of a
p-nitrophenylhydrazine. Suitable acyl halides which can be used include
aliphatic acyl halides such as acetyl chloride, propionyl chloride,
butyryl chloride, etc., and aromatic acyl halides such as benzoyl
chloride, toluoyl chloride, etc. The reaction can be conducted in a
solvent such as benzene, chloroform, pyridine, triethylamine, etc., 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
the acyl halide in the presence of a base such as pyridine or
triethylamine which acts as a hydrogen halide acceptor for the hydrogen
halide formed as a by-product ranges from about 1:1 to about 1:3,
preferably 1:1.2 to 1:1.5 and in the absence of such a base ranges from
about 1:0.3 to about 1:1, preferably 1:0.45 to 1:0.5. Hydrogen halide
accepting agents such as triethylamine and pyridine can be employed in an
amount of about one mol or more per mol of the acyl halide used.
Examples of synthesis of the compounds represented by the general formula
(I) are described below. Unless otherwise indicated herein, all parts,
percents, ratios and the like are by weight.
SYNTHESIS EXAMPLE 1
Synthesis of Compound 2
107 g of p-tolylhydrazine was added incrementally to 110 g of formic acid
with stirring at 25.degree. to 30.degree. C. After the addition, the
mixture was heated for 20 minutes with stirring at 50.degree. C. After
cooling with ice, the resulting crystals were separated by filtration and
recrystallized from 550 ml of acetonitrile. Thus, 54.5 g of colorless
needle-like crystals having a melting point of 176.degree. C.-177.degree.
C. was obtained.
SYNTHESIS EXAMPLE 2
Synthesis of Compound 5
15 g of p-tolylhydrazine was added to 100 ml of acetonitrile at
25.degree.-30.degree. C. with stirring. 15 g of benzoyl chloride was then
added dropwise at 25.degree.-30.degree. C. After the addition, stirring of
the system was continued at 25.degree.-30.degree. C. for 6 hours. After
cooling with ice, the resulting crystals were separated by filtration and
recrystallized from benzene. Thus, 7 g of colorless needle-like crystals
having a melting point of 146.degree. C. was obtained.
The compounds represented by the general formula (I) are employed in the
photographic emulsions of the present invention in an amount of about
10.sup.-4 to about 10.sup.-1 mol/mol Ag. A preferred amount is 10.sup.-3
to 5.times.10.sup.-2 mol/mol Ag and particularly 5.times.10.sup.-3 to
5.times.10.sup.-2 mol/mol Ag.
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 photographic emulsions of the present invention can be prepared by
processes described in P. Glafkides, 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.
If a small amount of iodide (for example, potassium iodide) is added to the
emulsions after formation of the grains, before chemical ripening, after
chemical ripening or before coating, the effect of the present invention
is further increased. A preferred amount of iodide to be added is about
10.sup.-4 to about 10.sup.-2 mol/mol Ag.
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 preferred anti-fogging agents for use in the present invention
are benzotriazoles. The benzene ring thereof may be substituted with alkyl
groups (for example, a methyl group or a heptyl group) or halogen atoms
(for example, a chlorine atom or a bromine atom). The alkyl moiety of
these substituents preferably has 12 or less carbon atoms and,
particularly, 3 or less carbon atoms. Further, the 1-position of the
benzotriazole may be substituted with a halogen atom (for example, a
chlorine atom or a bromine atom).
In the benzotriazoles used in the present invention, preferred compounds
are those represented by the following general formula (II):
##STR5##
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.
##STR6##
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 the image forming process of the present invention, it is advantageous
for the development to be conducted in the presence of a benzotriazole
compound in order to obtain images of a low degree of fog. The
benzotriazole compound may be incorporated in the photographic material or
may be added to the developing solution. Preferred benzotriazole compounds
which can be used are those represented by the above-described general
formula (II).
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.-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.
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. 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 Pat. 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 Pat. No. 1,242,588 and
Japanese Patent Publication 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 Pat. No. 1,344,281 and Japanese Patent
Publication 4936/68.
The emulsions may contain dyes which do not ha | | |
