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Description  |
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BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to silver halide color photographic materials and
particularly to silver halide color photographic materials which provide a
color image having excellent graininess and color reproduction and which
have excellent characteristics of development processing.
(2) Description of the Prior Art
As is well-known, silver halide multilayer color photographic materials
comprise a support formed of a cellulose ester or a polyester or the like
having coated thereon at least one red-sensitive silver halide emulsion
layer comprising a nondiffusible cyan dye-forming coupler, at least one
green-sensitive silver halide emulsion layer comprising a nondiffusible
magenta dye-forming coupler and at least one blue-sensitive silver halide
emulsion layer comprising a nondiffusible yellow dye-forming coupler,
which layers may further be divided to achieve specific purposes. For
example, British Pat. No. 818,687 discloses a photographic material
wherein at least one emulsion layer comprises two unit emulsion layers,
one of which is a low-speed layer placed near to the support and the other
of which is a high-speed layer placed over the low-speed layer to thereby
improve the sensitivity of the photographic material. British Pat. No.
923,045 discloses that graininess of a color image may be improved by
controlling the maximum color density of a high-speed unit emulsion layer.
Japanese Patent Publication No. 49-15495 discloses a high-speed multilayer
color photographic material which comprises red-sensitive, green-sensitive
and blue-sensitive layers, at least one of which layers comprises three
unit emulsion layers, the uppermost layer of which has the highest-speed
and the lowermost layer of which has the lowest-speed.
It is known to incorporate into these color photographic materials a
compound which reacts with the oxidation products of a color developing
agent to release a development restrainer or a precursor thereof, i.e. the
so-called DIR compound. Japanese Patent Application (OPI) (unexamined
published application) No. 49-42345 discloses incorporation of a DIR
coupler into the low-speed emulsion layer of the aforementioned
photographic material comprising high- and low-speed emulsion layers and
Japanese Patent Application (OPI) No. 53-7230 discloses incorporation of a
DIR compound into the medium-speed emulsion layer of the aforementioned
photographic material comprising high-, medium- and low-speed emulsion
layers.
The incorporation of the DIR compound into the medium-speed emulsion layer
(and the removal of the DIR compound from the high-speed emulsion layer)
increases sensitivity, improves image graininess or sharpness, or the
ratio of sensitivity to graininess and further extends exposure latitude.
Thus, it has been known that a DIR compound improves image graininess or
sharpness and color reproduction. A development restrainer released from
the DIR compound depending on an image density restrains the development
to thereby make the color image particles finer and diffuses in the
direction parallel to the emulsion layer to cause the Eberhard effect,
improving sharpness, and also in the direction perpendicular to the
emulsion layer to cause a development restraining effect on the other
emulsion layers, i.e. an interlayer development restraining effect to
thereby increase saturation of colors, resulting in an improvement in
color reproduction. Japanese Patent Application (OPI) No. 59-131934
discloses that the improvement in image sharpness and color reproduction
may be intensified by suitably increasing the distance between the site
where a development restrainer is split-off and released during
development and the site where the development restrainer works.
In the field of silver halide color photographic materials, particularly
materials for photographing, realization of high-quality color images has
become a major concern with the current tendency toward miniaturization of
cameras.
However, it is known that when a DIR compound is used for improving image
sharpness, graininess or color reproduction, such disadvantages as a
decrease in sensitivity, flattening of gradation and, occasionally, a
retardation in the progress of development occurs due to the development
restraining effect of the DIR compound. Various research toward realizing
high image quality without such disadvantages, including, for example,
investigation into useful DIR compounds, has been conducted but the
problems still remain unsolved. The results of such studies are seen, for
example, in West German Pat. (OLS) No. 2704797 which discloses a layer
structure wherein a layer comprising a DIR compound and a low-speed AgCl
emulsion is interposed between a high-speed emulsion layer of a
red-sensitive silver halide emulsion layer and that of a green-sensitive
silver halide emulsion layer gives a photographic material which is high
in sensitivity and exerts a great interlayer development restraining
effect even in the area of low density. In the layer structure of this
German Patent, a major portion of the development restrainer, which is
released from the DIR compound in the interposed layer when it reacts with
the oxidation products of a developing agent diffused into the interposed
layer from green- or red-sensitive high-speed emulsion layer, is adsorbed
on the low-speed silver chloride emulsion layer and contributes little to
the development restraining effect on the photosensitive emulsion layer.
Further the layer structure has a disadvantage in that the development
restraining effect, if any, will be canceled by the development
accelerating effect caused by the interaction between a silver bromoiodide
emulsion in the photosensitive emulsion layer and the silver chloride
emulsion, i.e. trapping of iodide ion by silver chloride or conversion of
bromide ion by silver chloride. The photographic material disclosed in
Japanese Patent Application (OPI) No. 53-7230 does not have such
disadvantages as flattening of gradation or a retardation in the progress
of development but it is still unsatisfactory because it is low in the
interlayer development restraining effect, whereas it is high in the
graininess-improving effect.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a new silver halide color
photographic material having excellent characteristics of development
processing and providing a color image of excellent quality, more
particularly to provide a silver halide color photographic material
providing a color image of excellent graininess and color reproduction and
having excellent developability. By the term "excellent developability"
used herein is meant that the photographic material concerned can be
quickly processed by a developing agent to provide an optimum density and
the optimum density once produced does not increase further with time.
The above mentioned object of the present invention can be accomplished by
a silver halide color photographic material which comprises a support
having thereon at least two silver halide light-sensitive layers having
essentially the same color sensitivity but different speeds, and a
light-insensitive layer positioned adjacent to the highest-speed layer of
said light-sensitive layers and containing a compound capable of forming a
diffusible development restraining compound or a precursor thereof upon
reaction with oxidation products of a color developing agent.
DETAILED DESCRIPTION OF THE INVENTION
Such compounds that form a diffusible development restraining compound or a
precursor thereof are described in European Pat. No. 101,621 (U.S. Pat.
No. 4,005,364) and Japanese Patent Application (OPI) No. 59-131,934. The
magnitude of diffusibility of a development restrainer or a precursor
thereof is determined according to the following method as described in
European Pat. No. 101,621 and is preferably 0.4 or more, and particularly
0.95 or less in the present invention.
On a transport support, there are coated two layers having the following
composition to make a light-sensitive material (SAMPLE B).
First layer:
A red-sensitive silver halide emulsion layer.
A gelatin coating solution which contains a silver bromoiodide emulsion
(silver iodide: 5 mole %, average grain size: 4 microns) and Sensitizing
Dye I (6.times.10.sup.-5 mole per mole of silver) used in Example 1
described later and added to render the emulsion red-sensitive, and
coupler X (0.0015 mole per mole of silver) is coated on the support in the
amount of 1.8 g silver/m.sup.2 (2 microns in thickness).
##STR1##
Second layer:
A gelatin layer containing a silver bromoiodide emulsion which is the same
as that used in the first layer except that it is not red-sensitized and
polymethylmethacrylate matting particles having a diameter of about 15
microns (the amount of silver coated: 2 g/m.sup.2, 1.5 microns in
thickness).
In addition to the above compositions, each layer contains a gelatin
hardener, a surface active agent, etc.
SAMPLE A has the same construction as that of SAMPLE B except that the
second layer does not contain the silver bromoiodide emulsion.
SAMPLES A and B are exposed to red-light through an optical wedge and
developed in the same process as in Example 1 except that the time for
development is 2 minutes 10 seconds. A development restrainer was added to
the developer until the density of SAMPLE A is reduced to 1/2. The degree
of density reduction of SAMPLE B developed in the developer containing
such amount of the restrainer is a measure of diffusibility of the
development restrainer in a silver halide emulsion layer.
The object of the present invention cannot be accomplished by only the use
of the compound which releases a diffusible development restrainer or a
precursor thereof but it is necessary to incorporate the compound into the
light-insensitive layer adjacent to the highest-speed light-sensitive
layer. It is preferred that the compound accounts for a stoichiometric
amount of at least 50%, preferably at least 70% and more preferably 100%
of all compounds which are incorporated in the light-insensitive layer and
which cause a coupling reaction with the oxidation products of a
developing agent.
The use of a DIR compound in the present invention is clearly distinguished
from the conventional use of the DIR compound in the prior art wherein the
DIR compound is used in a selected ratio, usually in a minor proportion,
in combination with a non-DIR coupler in light-sensitive emulsion layers.
In the present invention solely by the use of the DIR compound it is
possible to obtain a color image of excellent graininess and color
reproduction and a photographic material of excellent characteristics of
development processing.
It is summarized that the characteristic effects by the incorporation of
the above mentioned compound into the light-insensitive layer adjacent to
the highest-speed layer is caused by the following speculated mechanism.
When a DIR compound is contained together with a non-DIR coupler in a
light-sensitive layer, the DIR compound reacts with the oxidation products
of a developing agent depending on the mixing ratio and the relative
coupling speed of the DIR compound to release a development restrainer
which instantly starts restraining the development of silver grains.
If the development restraining effect is exerted quickly and strongly,
grains which would otherwise develop slowly are almost completely
prevented from being developed by the strong development restraining
effect, which results in a decrease in the number of sites from which
starts, to thereby degrade graininess and to decrease apparent
sensitivity. Retardation of development at the initial stage degrades
developability. These adverse effects are intensified when a large amount
of the DIR compound is used for increasing the interlayer development
restraining effect, as explained earlier.
In contrast, the present invention is characterized in that a DIR compound
is incorporated into a light-insensitive layer adjacent to the
highest-speed layer and it couples with the oxidation products of a
developing agent transferred by diffusion from the light-sensitive
emulsion layer to release a development restrainer which diffuses back
into the light-sensitive emulsion layer where the development restrainer
exerts the development restraining effect. As a result, the timing of the
development restraint is delayed as compared with the case where the DIR
compond is incorporated in the light-sensitive emulsion layer, fewer
grains are extremely restrained from being developed, and the decrease in
the number of sites from which development starts and the retardation of
the initial development are reduced. The oxidation products of the
developing agent formed in the light-sensitive emulsion layer by the
reduction of silver halide diffuse into the adjacent light-insensitive
layer where the oxidation products couple with the DIR compound
incorporated therein, and therefore the amount of oxidation products which
diffuse into the light-insensitive layer and react with the DIR compound
is smaller at the initial stage of development when a coupler exists in
the light-sensitive emulsion layer in an amount which is sufficient to
react with the oxidation products but is larger at the latter stage of
development when the coupler in the light-sensitive emulsion layer is
exhausted and consequently the oxidation products of the developing agent
formed in the light-sensitive layer diffuse excessively into adjacent
layers. That is to say, the later the stage of development, the greater
the amount of the DIR compound which reacts with the oxidation products
becomes and the stronger the development is restrained. This prevents dye
clouds from expanding and restrains the progress of development at the
latter stage of development. This is believed to contribute to the
improvement of graininess and developability. Generally, the lower the
coupling speed of a DIR compound, the lower the rate of reaction of the
DIR compound when it is in coexistence with another non-DIR coupler, and
therefore the interlayer development restraining effect decreases,
although developability is not so much degraded. Since the rate of
reaction of the DIR compound is low particularly in the area of low
density, the interlayer development restraining effect is also low in the
area of low density. On the contrary, when the coupling speed of a DIR
compound is high, developability is degraded although the interlayer
development restraining effect remains high. In the present invention,
since a major part of the compounds incorporated in the light-insensitive
layer adjacent to the light-sensitive layer is accounted for by a DIR
compound, the DIR compound reacts with the oxidation products of a
developing agent diffused therein, and therefore a large interlayer
development restraining effect can be exerted even in the area of low
density regardless of the coupling speed and without degrading
developability.
The effect of the present invention depends on the function of the
oxidation products of a developing agent which are produced in a
light-sensitive emulsion layer and diffuse into the adjacent layer and it
is intensified by increasing the amount of the oxidation products diffused
at the latter stage of development. Accordingly, a layer to which a DIR
compound is incorporated is positioned adjacent to a layer having a high
ratio of silver halide to coupler, usually a high-speed layer. This
arrangement makes it easier to exert the interlayer development
restraining effect from the low density area.
It is advantageous to use a compound which releases a diffusible
development restraining agent or a precursor thereof for obtaining an
adequate interlayer development restraining effect. The present invention
makes it possible to use a large amount of a compound which forms a
diffusible development restrainer or a precursor thereof without degrading
developability and graininess to thereby increase the interlayer
development restraining effect and consequently to achieve the significant
improvement of color reproduction.
In the present invention compounds which react with the oxidation products
of a color developing agent to form a diffusible development restraining
compound or a precursor thereof are referred to as diffusible DIR
compounds. Suitable examples of diffusible DIR compounds are diffusible
DIR hydroquinones and preferably diffusible DIR couplers. The term
"diffusible DIR coupler" as used herein means a coupler which reacts with
oxidation products of a color developing agent to form or release a
development restraining compound or a precursor thereof having large
diffusibility during development. Suitable examples of diffusible DIR
coupler include dye-forming DIR couplers, colorless compound-forming DIR
couplers, etc.
Thus, the incorporation of a compound which releases a diffusible
development restrainer or a precursor thereof into a light-insensitive
interlayer adjacent to a high-speed emulsion layer gives a silver halide
color photographic material having an excellent developability and
provides a color image of excellent graininess and color reproduction.
The compound which forms a diffusible development restrainer or a precursor
thereof is incorporated preferably in the range of 0.00001 to 0.002
mol/m.sup.2, and more preferably 0.00002 to 0.001 mol/m.sup.2.
In the present invention, it is preferred that the light-insensitive layer
does not contain light-sensitive silver halide grains, but it may contain
them under particular condition. This is because even if the
light-insensitive layer contains light-sensitive silver halide grains, it
may become substantially light-insensitve, when a compound which forms a
diffusible development restrainer or a precursor thereof contained in the
light-insensitive layer accounts for at least 50% of all the compounds
contained therein which cause a coupling reaction with the oxidation
products and it extremely restrains the development of the layer
comprising the light-sensitive silver halide grains.
It is preferred that the light-insensitive layer of the photographic
material of this invention does not contain any image dye-forming couplers
other than the compound which reacts with the oxidation products of a
color developing agent to form a diffusible development restraining
compound or a precursor thereof, although it may contain them.
It is preferred that the photographic material of this invention further
comprises a light-insensitive layer containing light-insensitive silver
halide grains. The light-insensitive silver halide grains may be
incorporated into the outermost protective layer or a color mixing
preventing layer to prevent a diffusible development restrainer from
flowing into processing liquids or to control the direction in which the
diffusible development restrainer works.
The light-insensitive layer adjacent to the highest-speed layer may be
positioned near to or remote from the support with respect to the
highest-speed layer. The light-insensitive layer may be positioned
adjacent to one or more of the blue-sensitive, the green-sensitive and the
red-sensitive highest-speed layers.
Preferable diffusible DIR couplers which can be used in the present
invention are represented by the formula (I):
A--Y).sub.m (I)
wherein A represents a coupler component, m represents an integer of 1 or 2
and Y represents a coupling-off group which is linked to a coupling
position of the coupler component A and can be eliminated from the coupler
component upon the reaction with the oxidation products of a color
developing agent to release a highly diffusible development restrainer or
a precursor thereof.
In the formula (I), Y is preferably a group represented by the formulas
(IIa) to (V).
##STR2##
In the formulas (IIa), (IIb) and (III), R.sub.1 represents alkyl, alkoxy,
acylamino, halogen, alkoxycarbonyl, thiazolidinylidenamino,
aryloxycarbonyl, acyloxy, carbamoyl, N-alkylcarbamoyl,
N,N-dialkylcarbamoyl, nitro, amino, N-arylcarbamoyloxy, sulfamoyl,
N-alkylcarbamoyloxy, hydroxy, alkoxycarbonylamino, alkylthio, arylthio,
aryl, hetero ring, cyano, alkylsulfonyl or aryloxycarbonylamino group. In
the formulas (IIa), (IIb) and (III), n represents an integer of 1 or 2, if
n represents 2, R.sub.1 may be the same or different and the total number
of carbons contained in n R.sub.1 is 0 to 10.
In the formula (IV), R.sub.2 represents alkyl or aryl group or hetero ring.
In the formula (V), R.sub.3 represents hydrogen, alkyl or aryl group or
hetero ring, R.sub.4 represents hydrogen, alkyl or aryl group, halogen,
acylamino, alkoxycarbonylamino, aryloxycarbonylamino, hetero ring,
alkylthio or amino group. If R.sub.1, R.sub.2, R.sub.3 or R.sub.4
represents alkyl group, it may be substituted or unsubstituted and chain
or cyclic. The substituent can be halogen, nitro, cyano, aryl, alkoxy,
aryloxy, alkoxycarbonyl, aryloxycarbonyl, sulfamoyl, carbamoyl, hydroxy,
alkanesulfonyl, arylsulfonyl, alkylthio or arylthio group.
If R.sub.1, R.sub.2, R.sub.3 or R.sub.4 represents aryl group, it may be
substituted. The substituent can be alkyl, alkenyl, alkoxy,
alkoxycarbonyl, halogen, nitro, amino, sulfamoyl, hydroxy, carbamoyl,
aryloxycarbonylamino, alkoxycarbonylamino, acylamino, cyano or ureido
group.
If R.sub.1, R.sub.2, R.sub.3 or R.sub.4 represents hetero ring, it
represents a 5- or 6-membered monocyclic or condensed ring containing
nitrogen, oxygen or sulfur as a hetero atom, e.g. pyridyl, quinolyl,
furyl, benzothiazolyl, oxazolyl, imidazolyl, thiazolyl, triazolyl,
benzotriazolyl, imido or oxazine. The ring may further be substituted by
the substituent described above as a substituent for the aryl group.
In the formula (IV), the number of carbon atoms contained in R.sub.2 is
preferably 1 to 15, and more preferably 1 to 5 when R.sub.2 represents an
unsubstituted alkyl.
In the formula (V), the total number of carbon atoms contained in R.sub.3
and R.sub.4 is 1 to 15.
In the formula (I), Y may be represented by the following formula (VI)
--TIME--INHIBIT (VI)
wherein TIME is a group which is linked to a coupling position of a coupler
and is cleaved upon the reaction with the oxidation products of a color
developer to control properly the release of INHIBIT group after the
cleavage.
The INHIBIT group is a residue of a development restrainer.
Preferred examples of the TIME-INHIBIT group are those of the formulas
(VII) to (XIII) as set forth below and also disclosed in U.S. Pat. No.
4,005,634 (European Pat. No. 101,621).
Of the diffusible DIR compounds, particularly preferable are those having
an INHIBIT group represented by the formula (IIa), (IIb), (III), (IV) or
(V).
Suitable examples of the yellow dye image forming coupler component
represented by the group A in the formula (I) include those of
pivaloylacetanilide, benzoylacetanilide, melonyldiester, molonylamide,
dibenzoylmethane, benzothiazolylacetamide, malonic ester monoamide,
benzothiazolylacetate, benzoxazolylacetamide, benzoxazolylacetate,
benzimidazolylacetamide and benzimidazolylacetate types; those derived
from hetero-ring substituted acetamides or hetero-ring substituted
acetates as described in U.S. Pat. No. 3,841,880; those derived from
acylacetamides as described in U.S. Pat. No. 3,770,446, British Pat. No.
1,459,171, West German Patent Application (OLS) No. 2,503,099, Japanese
Patent Application (OPI) 50-139,738 or Research Disclosure No. 15737 (May,
1977); and hetero-ring type couplers as described in U.S. Pat. No.
4,046,574.
Preferable examples of a magenta dye image forming coupler component
represented by the group A in the formula (I) include those of
5-oxo-2-pyrazoline nuclei, pyrazolo-1,5-a benzimidazole nuclei and
cyanoacetophenone type components.
Preferred examples of a cyan dye image forming coupler component
represented by the group A include those of phenol nuclei and
.alpha.-naphthol nuclei.
Preferred examples of the group A of the formula (I) are those represented
by the formulas (IA), (IIA), (IIIA), (IVA), (VA), (VIA), (VIIA), (VIIIA)
and (IXA) as described in U.S. Pat. No. 4,055,634.
Specific examples of preferred diffusible DIR couplers are illustrated as
follows:
##STR3##
Particularly preferred diffusible DIR compounds which can be used in the
present invention are those which form a diffusible development restrainer
which loses the development restraining property after it diffuses into a
developing solution.
The diffusible DIR compounds which can be used in the present invention can
easily be prepared by the methods described in U.S. Pat. Nos. 3,227,554,
3,617,291, 3,933,500, 3,958,993, 4,149,886 and 4,234,678; Japanese Patent
Application (OPI) Nos. 51-13239 and 57-56837; British Pat. Nos. 2,070,266
and 2,072,363; and Research Disclosure No. 21228 (December, 1981).
In the present invention, any known methods as described in U.S. Pat. No.
2,322,027 can be used to incorporate the diffusible DIR compounds and
other couplers explained later into a silver halide emulsion layer or a
light-insensitive layer. For example, they are dissolved in a solvent such
as phthalic acid alkyl esters (e.g. dibutyl phthalate, dioctyl phthalate,
etc.), phosphates (e.g. diphenyl phosphate, triphenyl phosphate, tricresyl
phosphate, dioctyl butyl phosphate, etc.), citrates (e.g. tributyl
acetylcitrate, etc.), benzoates (e.g. octyl benzoate), alkylamides (e.g.
diethyllaurylamide), aliphatic acid esters (e.g. dibutoxyethyl succinate,
diethyl azelate, dioctyl azelate, etc.), trimesic acid esters (e.g.
trimesic acid tributyl ester), etc., or organic solvents having a boiling
point of about 30.degree. C. to about 150.degree. C., such as lower alkyl
acetates (e.g. ethyl acetate, butyl acetate), ethyl propionate, sec-butyl
alcohol, methyl isobutyl ketone, beta-ethoxyethyl acetate,
methylcellosolve acetate, etc. and then dispersed into a hydrophilic
colloid. A mixture of these high and low boiling point solvents may also
be used.
The dispersing method using the polymer as described in Japanese Patent
Publication No. 51-39853 and Japanese Patent Application (OPI) No.
51-59943 may also be used.
Couplers having an acid group such as carboxyl or sulfonic may be
introduced to a hydrophilic colloid in the form of an aqueous alkaline
solution.
Gelatin is most suitable as a binder or protective colloid used in emulsion
layers or interlayers of the photographic material of this invention,
although other hydrophilic colloids may be used alone or together with
gelatin.
Examples of such hydrophilic colloids include proteins such as gelatin
derivatives, graftpolymers of gelatin and other polymers, albumin, casein,
etc.; saccharides such as cellulose derivatives such as hydroxyethyl
cellulose, carboxymethyl cellulose, cellulose sulfate, etc., sodium
alginate, starch derivatives, etc.; and various synthetic hydrophilic high
molecular weight substances such as homopolymers or copolymers, for
example, polyvinyl alcohol, polyvinyl alcohol semiacetal,
poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid,
polyacrylamide, polyvinyl imidazole, polyvinyl pyrazole, etc.
In the present invention, lime-processed gelatin, acid-processed gelatin,
enzyme-processed gelatin as described in Bull. Soc. Sci. Photo. Japan No.
16, page 30 (1966), gelatin hydrolysates or enzyme treated gelatin may be
used. Examples of gelatin derivatives include those obtained by the
reaction between gelatin and various compounds such as acid chlorides,
acid anhydrides, isocyanates, bromoacetic acid, alkanesultones,
vinylsulfonamides, maleicimides, polyalkyleneoxides, epoxy compounds, etc.
In the emulsion layers of this invention, there may be used any of silver
bromide, silver bromoiodide, silver bromochloroiodide, silver
chlorobromide and silver chloride. A preferred silver halide is silver
bromoiodide containing 15 mole % or less of silver iodide. A particularly
preferred one is silver bromoiodide containing 2 to 12 mole % of silver
iodide.
The average size of the silver halide grains of the photographic emulsion
is not particularly limited but it is preferably 3 microns or less,
wherein the average grain size means the average diameter for spherical or
nearly spherical grains and the average edge length for cubic grains and
these average values are calculated from projected surface area.
The grain size distribution may be narrow or broad.
Silver halide grains in the photographic emulsion may be of regular forms
such as cubic or octahedral grains, of irregular forms such as spherical
or tabular grains, of complex forms thereof, or mixtures thereof.
There may also be used an emulsion wherein tabular grains having a
diameter-thickness ratio of at least five constitute 50% or more of the
total projected area of silver halide grains.
Silver halide grains may be of a layer structure wherein the inner layer
and the outer layer are different in phase of joining structure or of
uniform phase structure. Silver halide grains may be those in which a
latent image is formed mainly on the surface thereof, or those in which a
latent image is formed mainly in the interior thereof.
The photographic emulsion used in this invention can be prepared in any
manner, e.g., by the methods as 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 et al.,
Making and Coating Photographic Emulsion, The Focal Press (1964). That is,
any of an acid process, a neutral process, an ammonia process, etc., can
be employed.
Soluble silver salts and soluble halogen salts can be reacted by techniques
such as a single jet process, a double jet process, or a combination
thereof. In addition, there can be used a method in which silver halide
grains are formed in the presence of an excess of silver ions (so-called
reversal mixing process).
As one system of the double jet process, a so-called controlled double jet
process in which the pAg in a liquid phase where silver halide is formed
is maintained at a predetermined level can be employed. This process can
produce a silver halide emulsion in which the crystal form is regular and
the grain size is nearly uniform.
Two or more kinds of silver halide emulsions which are prepared separately
may be used as a mixture.
The formation or physical ripening of silver halide grains may be carried
out in the presence of cadmium salts, zinc salts, lead salts, thallium
salts, iridium salts or complex salts, rhodium salts or complex salts,
iron salts or complex salts, and the like.
For removal of soluble salts from the emulsion after precipitate formation
or physical ripening, a well known noodle washing process in which gelatin
is gelated may be used. In addition, a flocculation process utilizing
inorganic salts having a polyvalent anion (e.g., sodium sulfate), anionic
surface active agents, anionic polymers (e.g., polystyrenesulfonic acid),
or gelatin derivatives (e.g., aliphatic acylated gelatin, aromatic
acylated gelatin and aromatic carbamoylated gelatin) may be used.
Silver halide emulsions are usually chemically sensitized. For this
chemical sensitization, for example, the methods as described in H.
Frieser ed., Die Grundlagen Der Photographischen Prozesse mit
Silberhalogeniden, Akademische Verlagsgesellshaft, pages 675 to 734 (1968)
can be used. Namely, a sulfur sensitization process using active gelatin
or sulfur containing-compounds (e.g., thiosulfates, thioureas, mercapto
compounds and rhodanines) capable of reacting with
sulfoalkylpolyoxyethylene alkylphenyl ethers, and polyoxyethylene
alkylphosphoric acid esters; amphoteric surface active agents, such as
amino acids, aminoalkylsulfonic acids, aminoalkylsulfuric acid or
aminoalkylphosphoric acid esters, alkylbetaines, and amine oxides; and
cationic surface active agents, e.g., alkylamine salts, aliphatic or
aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts
(e.g., pyridinium and imidazolium), and aliphatic or heterocyclic
phosphonium or sulfonium salts.
The photographic emulsion layer of the photographic material of the present
invention may contain compounds such as polyalkylene oxide or its ether,
ester, amine or like derivatives, thioether compounds, thiomorpholines,
quaternary ammonium salt compounds, urethane derivatives, urea
derivatives, imidazole derivatives, and 3-pyrazolidones for the purpose of
increasing sensitivity or contrast, or of accelerating development.
In the photographic emulsion layer or other hydrophilic colloid layers of
the photographic material of the present invention can be incorporated
water-insoluble or sparingly soluble synthetic polymer dispersions for the
purpose of improving dimensional stability, etc. Synthetic polymers which
can be used include homo- or copolymers of alkyl acrylates or
methacrylates, alkoxyalkyl acrylates or methacrylates, glycidyl acrylates
or methacrylates, acrylamides or methacrylamides, vinyl esters (e.g.,
vinyl acetate), acrylonitrile, olefins, styrene, etc. and copolymers.
The photographic emulsion layers or other hydrophilic colloid layers of the
photographic material of this invention may include various surface active
agents as coating aids or for other various purposes, e.g., prevention of
charging, improvement of slipping properties, acceleration of
emulsification and dispersion, prevention of adhesion, and improvement of
photographic characteristics (for example, development acceleration, high
contrast, and sensitization), etc.
Surface active agents which can be used are nonionic surface active agents,
e.g., saponin (steroid-based), alkylene oxide derivatives (e.g.,
polyethylene glycol, a polyethylene glycol/polypropylene glycol
condensate, polyethylene glycol alkyl ethers or polyethylene glycol
alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan
esters, polyalkylene glycol alkylamines or polyalkylene glycol alkylamide,
and silicone/polyethylene oxide adducts, etc.), glycidol derivatives
(e.g., alkenylsuccinic acid polyglyceride and alkylphenol polyglyceride,
etc.), fatty acid esters of polyhydric alcohols, and alkyl esters of
sugar, etc.; anionic surface active agents containing an acidic group,
such as a carboxy group, a sulfo group, a phospho group, a sulfuric acid
ester group, and a phosphoric acid ester group, for example,
alkylcarboxylic acid salts, alkylsulfonic acid salts, alkylbenzenesulfonic
acid salts, alkylnaphthalenesulfonic acid salts, alkylsulfuric acid
esters, alkylphosphoric acid esters, N-acyl-N-alkyltaurines, sulfosuccinic
acid esters, sulfoalkylpolyoxyethylene alkylphenyl ethers, and
polyoxyethylene alkylphosphoric acid esters; amphoteric surface active
agents, such as amino acids, aminoalkylsulfonic acids, aminoalkylsulfuric
acid or aminoalkylphosphoric acid esters, alkylbetaines, and amine oxides;
and cationic surface active agents, e.g., alkylamine salts, aliphatic or
aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts
(e.g., pyridinium and imidaz | | |
