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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a silver halide photographic light-sensitive
material which forms a direct positive photographic image, and more
particularly, to a photographic light-sensitive material in which a novel
compound is contained as a fogging agent in a photographic emulsion layer
or another hydrophilic colloid layer(s).
2. Description of the Prior Art
In the field of silver halide photography, photographic processes which can
produce photographic images without the formaton of a negative image or
without the intermediate treatment for obtaining a negative image are
called direct positive photographic processes, and photographic
light-sensitive materials and photographic emulsions used in such
photographic processes are called direct positive light-sensitive
materials and direct positive photographic emulsions, respectively.
Various types of direct positive photographic processes are known, but a
process in which previously fogged silver halide grains are exposed to
light in the presence of a desensitizer and then developed, and a process
in which a silver halide emulsion having sensitivity specks mainly in the
interior of the silver halide grains is exposed to light and then
developed in the presence of a fogging agent are the most useful. This
invention is concerned with the latter process. Silver halide emulsions
having sensitivity specks mainly in the interior of silver halide grains
and forming a latent image mainly in the interior of the grains are called
silver halide emulsions of the internal latent image type.
A method of directly forming a positive image by subjecting a silver halide
photographic emulsion of the internal latent image type to surface
development in the presence of a fogging agent, and photographic emulsions
and light-sensitive materials used in such a method are well known and are
described in U.S. Pat. Nos. 2,456,953, 2,497,875, 2,497,876, 2,588,982,
2,592,250, 2,675,318 and 3,227,552, British Pat. Nos. 1,011,062 and
1,151,363, and Japanese Patent Publication 29,405/68.
In the above method of directly forming a positive image, the fogging agent
may be added to a developer, but better reversal characteristics can be
obtained when the fogging agent is added to a photographic emulsion layer
or other layers of the light-sensitive material to adsorb the agent on the
surface of the silver halide grains.
Fogging agents which are added to a silver halide emulsion or other layers
of a light-sensitive material include the hydrazine compounds described in
U.S. Pat. Nos. 2,563,785 and 2,588,982. However, these hydrazine
compounds, when added to an emulsion layer, must be used at a quite high
concentration (e.g., about 2g per 1 mol of silver). Moreover, since the
fogging agent is transferred from the emulsion layer to a developer during
development, the concentration of the fogging agent in the emulsion
changes, resulting in a variation in maximum density (in the unexposed
portions). Further, in multilayer color light-sensitive materials, an
unequal fogging effect among the emulsion layers is produced.
Known fogging agents which are free from the above defects include those
heterocyclic quaternary salt compounds described in U.S. Pat. Nos.
3,615,615, 3,719,494, 3,734,738 and 3,759,901. However, silver halide
emulsions, in many cases, contain a sensitizing dye for spectral
sensitization. In particular, for color light-sensitive materials, a layer
sensitive to blue light and also layers respectively sensitive to green
light and red light are indispensable, and the emulsions of the
green-sensitive layer and red-sensitive layer necessarily contain
sensitizing dyes.
When a fogging agent together with a sensitizing dye for green light or red
light are incorporated into a direct positive emulsion, competitive
adsorption on the silver halide occurs between the sensitizing dye and the
quaternary salt fogging agent. Therefore, when the fogging agent is
employed in an amount necessary for forming the desired nuclei, spectral
sensitization is inhibited, and on the other hand, when the spectrally
sensitizing dye is used in a concentration sufficient to obtain the
desired spectral sensitization, the formation of fog nuclei is inhibited.
The use of a sensitizing dye containing, in the dye molecule, a substituent
having a fogging (nucleating) effect as described in U.S. Pat. No.
3,718,470 is known as a method of overcoming the above defect.
However, this method of making a single molecule have a fogging effect and
a spectral sensitizing effect is disadvantageous, e.g., in that the use of
an amount adequate for spectral sensitization results in an unsatisfactory
fogging effect, and on the other hand, the use of a sufficient amount to
produce a fogging effect is unsuitable for spectral sensitization.
To solve the above problems, fogging agents which are more readily adsorbed
on silver halide and perform the desired formation of nuclei by their use
in such an amount which does not inhibit spectral sensitization are
required.
SUMMARY OF THE INVENTION
A first object of this invention is to provide a direct positive
light-sensitive material which can produce a uniform maximum density.
A second object of this invention is to provide a direct positive
light-sensitive material containing a fogging agent which exhibits the
desired fogging effect without inhibiting spectral sensitization.
Another object of this invention is to provide a direct positive
photographic light-sensitive material which can be spectrally sensitized
sufficiently and with which a direct positive image having a uniform and
high maximum density can be formed.
A further object of this invention is to provide a direct positive
photographic light-sensitive material which does not contaminate a
developer on development.
The above objects of this invention are attained by incorporating into at
least one hydrophilic colloid layer of a silver halide light-sensitive
material containing at least one silver halide photographic emulsion layer
of the internal latent image type, preferably into a silver halide
photographic emulsion layer of the internal latent image type or a
hydrophilic colloid layer adjacent thereto, a heterocyclic quaternary salt
compound represented by the following general formula (I)
##STR2##
wherein Z represents an atomic group necessary for forming a 5- or
6-membered heterocyclic nucleus, R.sub.1 represents an aliphatic group,
R.sub.2 represents a hydrogen atom or an aliphatic group, R.sub.3 and
R.sub.4, which may be the same or different, each represents a hydrogen
atom, a halogen atom, an aliphatic group, an alkoxy group, a hydroxy group
or an aromatic group, at least one of R.sub.1, R.sub.2, R.sub.3 and
R.sub.4 being a propargyl group, a butynyl group or a substituent
containing a propargyl or butynyl group, X.crclbar. represents an anion, n
is 1 or 2, with n being 1 when the compound forms an inner salt; in an
amount sufficient to exert a fogging effect on the silver halide
photograhic emulsion of the internal latent image type.
DETAILED DESCRIPTION OF THE INVENTION
Examples of heterocyclic nuclei which are completed by Z include, for
example, a thiazoline nucleus, a thiazole nucleus, a benzothiazole
nucleus, a naphthothiazole nucleus, a selenazole nucleus, a
benzoselenazole nucleus, a naphthoselenazole nucleus, an oxazoline
nucleus, an oxazole nucleus, a benzoxazole nucleus, a naphthoxazole
nucleus, a benzimidazole nucleus, a pyridine nucleus, a quinoline nucleus,
a tetrazole nucleus, an indolenine nucleus, etc.
specific examples of the above nuclei are thiazolines such as
2-methyl-2-thiazoline, 2-p-hydroxyphenyl-5-methyl-2-thiazoline,
2-phenyl-2-thiazoline, 2-ethyl-2-thiazoline, 2-propyl-2-thiazoline and
2-thiazoline; thiazoles such as thiazole, 4 -methylthiazole,
4-phenylthiazole, 4-(p-hydroxyphenyl)thiazole, 5-methylthiazole,
5-phenylthiazole, 4,5-dimethylthiazole and 4,5-diphenylthiazole;
benzothiazoles such as benzothiazole, 5-hydroxybenzothiazole,
5-fluorobenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole,
5-methylbenzothiazole, 6-methylbenzothiazole, 5,6-dimethylbenzothiazole,
5-bromobenzothiazole, 5-phenylbenzothiazole, 6-phenylbenzothiazole,
5-methoxybenzothiazole, 6-methoxybenzothiazole, 5-iodobenzothiazole,
5-ethoxybenzothiazole, tetrahydrobenzothiazole,
5,6-dimethoxybenzothiazole, 5-hydroxybenzothiazole and
6-hydroxybenzothiazole; naphthothiazoles such as .alpha.-naphthothiazole,
.beta.-naphthothiazole, .beta.,.beta.-naphthothiazole,
5-methoxy-.beta.-naphthothiazole, 5-ethoxy-.beta.-naphthothiazole,
7-methoxy-.alpha.-naphthothiazole, 5-hydroxy-.beta.-naphthothiazole,
7-hydroxy-.alpha.-naphthothiazole and 5-ethyl-.beta.-naphthothiazole;
selenazoles such as selenazole, 4-methylselenazole and 4-phenylselenazole;
benzoselenazoles such as benzselenazole, 5-chlorobenzoselenazole,
5-methoxybenzoselenazole, 5-hydroxybenzoselenazole and
tetrahydrobenzoselenazole; naphthoselenazoles such as
.alpha.-naphthoselenazole, .beta.,.beta.-naphthoselenazole and
.beta.-naphthoselenazole; oxazolines such as 2-oxazoline,
2-phenyl-5-methyl-2-oxazoline, 2-methyl-2-oxazoline,
2-phenyl-5-carboethoxy-2-oxazoline and
2-phenyl-4-hydroxymethyl-2-oxazoline; oxazoles such as oxazole,
4-methyloxazole, 5-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole,
4-ethyloxazole, 4,5-dimethyloxazole and 5-phenyloxazole; benzoxazoles such
as benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole,
5-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole,
5-methoxybenzoxazole, 5-ethoxybenzoxazole, 5-trifluoromethylbenzoxazole,
5-hydroxybenzoxazole and 6-hydroxybenzoxazole; naphthoxazoles such as
.alpha.-naphthoxazole, .beta.,.beta.-naphthoxazole, .beta.-naphthoxazole
and 7-hydroxy-.beta.-naphthoxazole; benzimidazoles such as benzimidazole,
1-ethylbenzimidazole, 1-ethyl-5-chlorobenzimidazole,
1-ethyl-5,6-dichlorobenzimidazole and 1-phenyl-5,6-dichlorobenzimidazole;
tetrazoles such as tetrazole, 1-phenyltetrazole, 2-phenyltetrazole,
5-bromotetrazole, 1,5-dimethyltetrazole, pentamethylenetetrazole,
1-carboethoxytetrazole and 1-methyl-5-phenyltetrazole; pyridines such as
pyridine, 3-ethylpyridine, 4-decylpyridine, 4-benzylpyridine,
4-phenylpyridine, 4-chloropyridine, 4-bromopyridine, 4,6-dichloropyridine,
6-bromopyridine, 4-methoxypyridine, 4-ethoxypyridine and
6-methoxypyridine; quinolines such as quinoline, 3-methylquinoline,
6-methylquinoline, 8-methylquinoline, 6-chloroquinoline,
8-chloroquinoline, 8-fluoroquinoline, 6-metoxyquinoline,
6-ethoxyquinoline, 6-hydroxyquinoline and 8-hydroxyquinoline; and
indolenines such as indolenine, 3,3-dimethylindolenine,
5-hydroxy-3,3-dimethylindolenine, 3,3-dimethyl-6-chloroindolenine and
3,3,5-trimethylindolenine.
Aliphatic groups represented by R.sub.1 include unsubstituted alkyl groups
having 1 to 18 carbon atoms (e.g., methyl, ethyl, isopropyl, n-butyl,
t-butyl, heptadecyl, etc.) and substituted alkyl groups having 1 to 4
carbon atoms in the alkyl moiety with the total number of carbon atoms
being 1 to 18 such as sulfoalkyl groups (e.g., 2-sulfoethyl,
3-sulfopropyl, 3-sulfobutyl, 2-hydroxy-3-sulfopropyl, .delta.-sulfobutyl,
etc.), carboxyalkyl groups (e.g., 2-carboxyethyl, 4-carboxybutyl,
carboxymethyl, etc.), hydroxyalkyl groups (e.g., 2-hydroxyethyl,
3-hydroxypropyl, etc.), alkoxyalkyl groups including substituted
alkoxyalkyl groups (e.g., 2-methoxyethyl, 3-methoxypropyl,
2-(2-sulfoethoxy)ethyl, 2-[2-(3-sulfopropoxy)ethoxy]-ethyl,
hydroxymethoxymethyl, 2-hydroxyethoxymethyl, 2-(2-hydroxyethoxy)ethyl,
2-(2-acetoxyethoxy)ethyl, acetoxymethoxymethyl, etc.), acyloxyalkyl groups
(e.g., 2-acetoxyethyl, 4-propionyloxybutyl, etc.), dialkylaminoalkyl
groups (e.g., dimethylaminoethyl, diethylaminopropyl, etc.), sulfatoalkyl
groups (e.g., .beta.-sulfatoethyl, 4-sulfatobutyl, etc.), aralkyl groups
(e.g., benzyl, phenethyl, p-sulfobenzyl, etc.), alkenyl groups (e.g.,
vinylmethyl) and alkynyl groups (e.g., propargyl, 3-butynyl, etc.).
Aliphatic groups represented by R.sub.2 include unsubstituted alkyl groups
having 1 to 18 carbon atoms (e.g., methyl, ethyl, isopropyl, n-butyl,
t-butyl, etc.) and substituted alkyl groups having 1 to 4 carbon atoms in
the alkyl moiety with the total number of carbon atoms being 1 to 18 such
as sulfoalkyl groups (e.g., 2-sulfoethyl, 3-sulfopropyl, 3-sulfobutyl,
4-sulfobutyl, 2-hydroxy-3-sulfopropyl, etc.), carboxyalkyl groups (e.g.,
2-carboxyethyl, 4-carboxybutyl, carboxymethyl, etc.), hydroxyalkyl groups
(e.g., 2-hydroxyethyl, 3-hydroxypropyl, etc.), alkoxyalkyl groups
including substituted alkoxyalkyl groups (e.g., .beta.-methoxyethyl,
.gamma.-methoxypropyl, 2(2-sulfoethoxy)ethyl,
2[2-(3-sulfopropoxy)ethoxy]ethyl, hydroxymethoxymethyl,
2-hydroxyethoxymethyl, 2-(2-hydroxyethoxy)ethyl, 2(2-acetoxyethoxy)ethyl,
acetoxymethoxymethyl, propargyloxymethyl, etc.), acyloxyalkyl groups
(e.g., 2-acetoxyethyl, 4-propionyloxybutyl, etc.), dialkylaminoalkyl
groups (e.g., dimethylaminoethyl, diethylaminopropyl, etc.), sulfatoalkyl
groups (e.g., 2-sulfatoethyl, 4-sulfatobutyl, etc.), aralkyl groups (e.g,,
benzyl, phenethyl, p-sulfobenzyl, etc.), alkenyl groups (e.g.,
vinylmethyl), alkynyl groups (e.g., propargyl, 3-butynyl, etc.) and alkyl
grops substituted with a heterocyclic ring (e.g.,
4-(3'propargylbenzothiazol-2-yl)butyl, etc.).
Examples of halogen atoms represented by R.sub.3 and R.sub.4 include, for
example, a chlorine atom, a bromine atom, an iodine atom, etc.
The aliphatic groups respectively represented by R.sub.3 and R.sub.4
include unsubstituted alkyl groups having 1 to 18 carbon atoms (e.g.,
methyl, ethyl, i-propyl, n-butyl, t-butyl, heptadecyl, etc.) and
substituted alkyl groups having 1 to 4 carbon atoms in the alkyl moiety
with the total number of carbon atoms being 1 to 18 such as sulfoalkyl
groups (e.g., 2-sulfoethyl, 3-sulfopropyl, 3-sulfobutyl, 4-sulfobutyl,
2-hydroxy-3-sulfopropyl, etc.), carboxyalkyl groups (e.g., 2-carboxyethyl,
4-carboxybutyl, carboxymethyl, etc.), hydroxyalkyl groups (e.g.,
.beta.-hydroxyethyl, .gamma.-hydroxypropyl, etc.), alkoxyalkyl groups
including substituted alkoxyalkyl groups (e.g., .beta.-methoxyethyl,
.gamma.-methoxypropyl, propargyloxymethyl, 2-propargyloxyethyl,
2-(2-sulfoethoxy)ethyl, 2-[2-(3-sulfopropoxy)ethoxy]ethyl,
hydroxymethoxymethyl, 2-hydroxyethoxymethyl, 2-(2-hydroxyethoxy)ethyl,
2-(2-acetoxyethoxy)ethyl, acetoxymethoxymethy, etc.). acyloxyalkyl groups
(e.g., 2-acetoxyethyl, 4-propionyloxybutyl, etc.), dialkylaminoalkyl
groups (e.g., dimethylaminoethyl, diethylaminopropyl, etc.), haloalkyl
groups (e.g., trifluoromethyl), sulfatoalkyl groups (e.g.,
.beta.-sulfatoethyl, .omega.-sulfatobutyl, etc.), aralkyl groups (e.g,
benzyl, phenethyl, p-sulfobenzyl, etc.), alkenyl groups (e.g.,
vinylmethyl) and alkynyl groups (e.g., propargyl, 3-butynyl, etc.).
The aromatic groups represented by R.sub.3 and R.sub.4 include monocyclic
or bicyclic aryl groups, preferably monocyclic aryl groups, e.g.,
unsubstituted aryl groups with the number of carbon atoms being up to 18
(e.g., phenyl, naphthyl, etc.) and substituted aryl groups (e.g., phenyl
groups containing one or more substituents such as an alkyl group having 1
to 4 carbon atoms (e.g., methyl), an alkoxy group having 1 to 4 carbon
atoms (e.g., methoxy, ethoxy, etc.), a hydroxy group, a halogen atom
(e.g., chlorine atom) or sulfo grop), the total number of carbon atoms of
the substituted aryl groups ranging up to 18. Specific examples of these
groups are a p-tolyl group, a p-methoxyphenyl group, a p-hydroxyphenyl
group, a 2,4-dimethoxyphenyl group, a p-chlorophenyl group and a
p-sulfophenyl group.
R.sub.3 and R.sub.4 can also represent an alkoxy group having 1 to 18
carbon atoms, i.e., an unsubstituted alkoxy group (such as methoxy, ethoxy
or propargyloxy) or a substituted alkoxy group (such as benzyloxy or
.alpha.-naphthylmethyloxy), or a hydroxy group.
Specific examples of X.crclbar. are a chloride ion, a bromide ion, an
iodide ion, a p-toluenesulfonate ion, an ethylsulfonate ion, a perchlorate
ion and a thiocyanate ion.
n is 1 when the compound represented by the general formula (I) forms an
inner salt, and in other cases, n is 2.
Specific examples of the useful compounds in this invention are given
below.
1. 3-Propargylbenzothiazolium bromide
2. 5,6-Dimethyl-3-propargylbenzothiazolium bromide
3. 5-Methoxy-6-methyl-3-propargylbenzothiazolium bromide
4. 2-Methyl-3-propargylbenzothiazolium bromide
5. 5-Chloro-2-methyl-3-propargylbenzothiazolium bromide
6. 2-Methyl-6-methoxy-3-propargylbenzothiazolium bromide
7. 2-Methyl-3-propargylnaphtho[1,2-d]thiazolium bromide
8. 2-Methylthio-3-propargylbenzothiazolium bromide
9. 2-Methyl-3-propargyl-5-propargyloxybenzothiazolium bromide
10. 1,4-bis(3-Propargylbenzothiazolium-2(butane dibromide
11. 2-Ethyl-3-propargylbenzothiazolium bromide
12. 3-Methyl-2-propargyloxymethylbenzothiazolium iodide
13. 3-Propyl-2-propargyloxymethylbenzothiazolium chloride
14. 2,3-Dimethyl-5-propargyloxybenzothiazolium iodide
15. Anhydro-2-methyl-5-propargyloxy-3-sulfopropylbenzothiazolium bromide
16. 2-Methyl-5-propargyloxy-3-propylbenzothiazolium chloride
17. 2-Methyl-6-.alpha.-naphthylmethoxy-1-propargylquinolinium bromide
18. 2,6-Dimethyl-3-propargylbenzothiazolium bromide
19. 5,6-Dichloro-1-ethyl-2-methyl-3-propargylbenzimidazolium bromide
20. 2-Propyl-3-propargylbenzothiazolium bromide
21. 3-(3-Butynyl)benzothiazolium thiocyanate
22. 2,4-Dimethyl-3-propargylthiazolium bromide
23. 2-Methoxy-4-methyl-3-propargylthiazolium bromide
24. 2-Methyl-3-propargylthiazolinium iodide
25. 2,4-Dimethyl-3-propargyloxazolium iodide
26. 2,5-Methyl-4-carbomethoxy-3-propargyloxazolium iodide
27. 2-Methyl-4-phenyl-3-propargyloxazolium iodide
28. 2-Methyl-4,5-diphenyl-3-propargyloxazolium iodide
29. 2-Methyl-5-phenyl-3-propargylbenzoazolium bromide
30. 2-Methyl-5-trifluoromethyl-3-propargylbenzoxazolium bromide
31. 2-Methyl-5-chloro-3-propargylbenzoxazolium bromide
32. 2,3,3-Trimethyl-1-propargylindoleninium chloride
33. 2-Methyl-1-propargylpyridinium chloride
34. 2-Methyl-3-propargylbenzoselenazolium bromide
35. 2-Propargyloxymethyl-3-methylbenzoselenazolium bromide
36. 2-Methyl-3-propargyl-5-propargyloxybenzoselenazolium bromide
37. 5-Methyl-1-propargyltetrazolium bromide
The heterocyclic quaternary salts of this invention can easily be prepared
by reacting a corresponding heterocyclic compound wth a corresponding
alkylating reagent. Typical alkylating reagents include, for example,
methyl iodide, ethyl bromide, propyl chloride, propargyl bromide,
propanesultone, methyl p-toluenesulfonate, etc.
This reaction requires no catalyst and proceeds by heating at about
50.degree. to about 140.degree. C for about 30 minutes to several hours.
Solvents such as alcohols (e.g., methyl alcohol, ethyl alcohol, etc.),
acetone, methyl ethyl ketone, benzene or toluene are useful, but the
reaction can also be carried out without any solvent. Since the reaction
product precipitates, a pure compound can be obtained simply by washing
with a solvent, e.g., as described above.
Examples of the synthesis of the heterocyclic quaternary salts of this
invention are set forth below.
Unless otherwise indicated in the Examples, all parts, percents, ratios and
the like are by weight.
SYNTHESIS EXAMPLE 1
3-Propargylbenzothiazolium Bromide
13.5 g of benzothiazole was mixed with 13.1 g of propargyl bromide. The
mixture was heated at 80.degree. to 100.degree. C for one hour on a hot
water bath to solidify it. After cooling to room temperature (about
20.degree.- 30.degree. C), the solid was washed with acetone to give 21 g
of 3-propargylbenzothiazolium bromide, m.p. 209.degree.- 210.degree. C.
SYNTHESIS EXAMPLE 2
2-Methyl-3-propargylbenzothiazolium Bromide
14.9 g of 2-methylbenzothiazole and 12.5 g of propargyl bromide were heated
at 80 to 100.degree. C on a hot water bath for 3 hours. The precipitated
crystals were washed with acetone to obtain 18.5 g of
2-methyl-3-propargylbenzothiazolium bromide, m.p. 214.degree.- 215.degree.
C.
SYNTHESIS EXAMPLE 3
2-Methyl-3-propargyl-5-propargyloxybenzothiazolium Bromide
20.4 g of 2-methyl-5-propargyloxybenzothiazole and 12.5 g of propargyl
bromide were heated on a hot water bath at 80.degree. to 100.degree. C for
3 hours. The precipitated crystals were washed with acetone to give 17.5 g
of 2-methyl-3-propargyl-5-propargyloxybenzothiazolium bromide, m.p.
244.degree. C.
Fogging agents, in general, are reducing compounds like a developing agent
used for the development of a silver halide emulsion. One known means of
determining the strength of their reducibility is the measurement of the
polarographic have-wave potential.
Of the fogging agents used in this invention, fogging agents which exhibit
a cathodic half-wave potential more negative than -250 mV (VS.SCE) under
normal development conditions, i.e., at a pH of 11.5, are more effective.
However, this is subject to considerable exceptions, and the degree of the
effect can not, therefore, be judged only by the polarographic half-wave
potential.
The heterocyclic quaternary salt compound represented by the general
formula (I) is incorporated preferably into a silver halide emulsion of
the internal latent image type in the direct positive light-sensitive
material of this invention, but the compound can also be incorporated into
a hydrophilic colloid layer adjacent the silver halide emulsion layer of
the internal image type. Such an adjacent layer may be layers having any
function, e.g., a light-sensitive layer, an intermediate layer, a filter
layer, a protective layer, an antihalation layer, etc.
The desirable amount of the quaternary salt compound present in the layer
is that amount which will provide a sufficient maximum density (e.g., 2.0
or more) when the emulsion of the internal latent image type is developed
in a surface developer. In practice, the amount can widely vary depending
on the characteristics of the silver halide emulsion used, the type of the
fogging agent utilized and the development conditions employed, but an
amount ranging from about 5 mg to about 1000 mg per mol of silver in the
silver halide emulsion of the internal latent image type is useful, and an
amount of about 15 mg to about 700 mg per mol of silver is preferred. In
incorporating the heterocyclic quaternary salt compound of this invention
into a hydrophilic colloid layer adjacent the emulsion layer, the same
amount as above can be employed based on the amount of silver contained in
an equal area of the emulsion of the internal latent image type.
The emulsions of the internal latent image type which can be used in this
invention include silver halide emulsions which form a latent image mainly
in the interior of the silver halide grains, and are distinguished from
silver halide grains which form a latent image mainly on the surface of
the grains. Such an internal latent image is already disclosed in U.S.
Pat. No. 2,592,250 and also in the literature. The silver halide emulsion
of the internal latent image type can be clearly defined as one which when
developd in an "internal" developer, gives a maximum density higher than
that attained when developed in a "surface" developer. Surface developers
and internal developers are described in detail in G. Kornfeld, "The
Distribution of the Latent Image in the Silver Bromide Grain" J. Opt.
Soc., 31, 598 (1941), W. F. Berg, A. Marrige and G. W. W. Stevens, "Latent
Image Distribution" Phot. J., 81 413 (1941), G. W. W. Stevens, "The Depth
of Internal Latent Image" J. Photographic Sci., 1 122 (1953), R. V. Dyba
and T. D. Smith, "Effect of Developers and of pH in the Latent Image
Distribution Studies" Phot. Sci. Eng., 7 98 (1956) and E. Moisar and S.
Wagner, "Untersuchungen uber die Topographie des latenten Innen- and
Aussenbildes" Ber. der Bunsengesselschaft physk. Chem. 67 356 (1963).
Regarding the emulsions of the internal latent image type suitable for this
invention, a maximum density obtained when the silver halide emulsion is
coated on a transparent support, exposed to light for a fixed time ranging
from 0.01 to 1 sec and then developed at 20.degree. C for 3 minutes in the
following Developer A (internal developer) is at least 5 times higher than
that obtained when the silver halide emulsion exposed to light in the same
manner as above is developed at 20.degree. C for 4 minutes in the
following Developer B (surface developer), as measured according to the
usual measurement of photographic density.
______________________________________
Developer A
______________________________________
Hydroquinone 15 g
Monomethyl-p-aminophenol Sesquisulfate
15 g
Sodium Sulfite 50 g
Potassium Bromide 10 g
Sodium Hydroxide 25 g
Sodium Thiosulfate 20 g
Water to make 1 liter
______________________________________
______________________________________
Developer B
______________________________________
p-Oxyphenylglycine
10 g
Sodium Carbonate 100 g
Water to make 1 liter
______________________________________
The emulsions described in U.S. Pat. No. 2,592,250 described above, and the
emulsions described in British Pat. No. 1,027,146 and U.S. Pats. Nos.
3,206,313, 3,511,662, 3,447,927, 3,737,313 and 3,271,157 can be used as
the emulsion of the internal latent image type suitable for the objects of
this invention. However, the invention is not restricted to these.
More specifically, an emulsion of the internal latent image type for use in
this invention can be prepared as follows:
(1) Halide conversion emulsion
First, a silver chloride emulsion is precipitated, and then a halide
exchange is effected by introducing bromide and optionally some iodide
salts.
Increased speed can be obtained by adding noble metal salts before the
completion of the conversion step (e.g., as described in U.S. Pat.
3,703,584). Some additional improvement can be attained by sulfur- and
gold-sensitizing the silver chloride emulsion, converting with bromide or
iodo-bromide and then lightly sulfur- and gold-sensitizing the surface.
(2) Double-jet precipitation of silver bromide or silver iodo-bromide. The
formation of internal sensitivity specks is promoted by the rapid
introduction of thiocyanate after about 20 - 35% of the emulsion has been
precipitated.
(3) Silver halide grains having foreign ion dopants occluded therein, with
the grains having been chemically sensitized on the surface to a level
less than that which will produce a substantial density in a surface
developer after a normal imagewise exposure to light.
The dopant is a foreign metal ion or a metal or inorganic nonmetal
compound. The term "foreign metal ion" is used to describe an ion other
than a silver ion. Examples of dopants are metallic silver, iridium, gold,
platinum, etc.
Precipitation in the presence of the metal ion or preferably despositing
the metal (i.e., chemically sensitizing) on a core of silver halide is
conducted and then formation of the grain to build a shell or outer region
over the metallic deposit is continued.
In the direct positive photographic material of this invention, various
colloids can be used as a binder.
Examples of colloids used for this purpose include any hydrophilic colloid
generally used in photographic art, for example, gelatin, colloidal
albumin, polysaccharides, cellulose derivatives, synthetic resins such as
polyvinyl compounds including polyvinyl alcohol derivatives or acrylamide
polymers, etc. The vehicle or binder can contain, in addition to the
hydrophilic colloid, a hydrophobic colloid such as dispersed vinyl
compound polymers, particularly, those which can increase dimensional
stability of the photographic material. Suitable compounds of this type
include water-soluble polymers such as alkyl acrylate, alkyl methacrylate,
acrylic acid, sulfoalkyl acrylate or sulfoalkyl methacrylate.
Various supports can be used in the light-sensitive material of this
invention. The silver halide emulsion can be coated on one side or both
sides of the support. Typical examples of supports are cellulose nitrate
film, cellulose aliphatic acid ester film, polyvinyl acetal film,
polystyrene film, polyethylene terephthalate film and other polyesters,
glass, papers, metals and ceramics. Satisfactory results can also be
obtained with supports such as papers coated with an .alpha.-olefin
polymer, particularly, a polymer of an .alpha.-olefin containing 2 or more
carbon atoms, such as polyethylene, polypropylene or an ethylene butene
copolymer.
The photographic silver halide emulsion layer and other hydrophilic colloid
layers of the light-sensitive material of this invention can be hardened
with any suitable hardener. Examples of suitable hardeners are aldehyde
hardeners such as formaldehyde or mucohalic acids, hardeners containing an
active halogen, dioxane derivaties and oxypolysaccharides such as
oxy-starch.
Other additives, particularly those which are known to be useful in a
photographic emulsion, such as a lubricant, a stabilizer, a sensitizer, a
light-absorbing dye and a plasticizer can be added to the photographic
silver halide emulsion layer.
Moreover, in this invention, a compound which releases iodide ions (such as
potassium iodide) can be incorporated in the silver halide emulsion, or a
developer containing iodide ions can be used to obtain the desired image.
The light-sensitive material of this invention can contain a surface active
agent for various purposes. Any nonionic, ionic and amphoteric surface
active agents can be used depending upon the purpose, and examples of them
are polyoxyalkylene derivatives and amphoteric amino acids (including
sulfobetaines). Such surface active agents are described in U.S. Pats.
Nos. 2,600,831, 2,171,622, 2,271,623, 2,275,727, 2,787,604, 2,816,920 and
2,739,891, and Belgian Pat. No. 652,862.
The photographic emulsion of the light-sensitive material of this invention
can be spectrally sensitized as to blue light of a comparatively longer
wavelength, green light, red light or infrared light by using sensitizing
dyes. Cyanine dyes, merocyanine dyes, complex cyanine dyes, complex
merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes,
oxonol dyes, hemioxonol dyes, and the like can be used as sensitizing
dyes. Cyanine type dyes can have, as a basic nucleus, any of
nitrogen-containing heterocyclic rings such as pyrroline, oxazoline,
thiazoline, pyrrole, oxazole, thiazole, selenazole, imidazole, pyridine or
tetrazole. The nitrogen atom in these nuclei can have, as substituents, an
aliphatic group such as an alkyl group, an alkenyl group, an alkylene
group, a hydroxyalkyl group, a carboxylalkyl group, a sulfoalkyl group, an
aminoalkyl group, an alkoxyalkyl group, a sulfo-hydroxy-alkyl group or a
sulfoalkoxyalkyl group. Moreover, these nuclei can be condensed with an
aromatic ring (e.g., a benzene ring, a naphthalene ring, etc.)
unsubstituted or substituted with a halogen atom, an alkyl group, an
alkoxy group, a hydroxy group, a cyano group, a carboxy group, an
alkoxycarbonyl group, an alkylamino group, a dialkylamino group, an
acylamino group, an acyl group, a phenyl group or a fluoroalkyl group, an
alicyclic hydrocarbon ring (e.g., cyclohexene ring) unsubstituted or
substituted with the above atoms or groups or heterocyclic ring (e.g., a
quinoxaline ring, a quinoline ring, a pyridine ring, etc.) unsubstituted
or substituted with the above atoms or groups. The cyanine dyes may be
symmetric or asymmetric, and the methine or polymethine chain thereof can
be substituted with an alkyl group, a phenyl group, a substituted phenyl
group such as a carboxyphenyl group or a heterocyclic nucleus such as a
furyl group or a thienyl group. In addition, a part of the methine chain
can form a 5- or 6-membered ring in conjunction with other atoms.
Merocyanine dyes | | |
