[0001] The present invention relates to a silver halide photographic light-sensitive material
having a high sensitivity/fog ratio and improved storage stability during storage
after exposure.
[0002] The subject recently assigned to reseachers specialized in silver-halide color photographic
light-sensitive materials is to develop a light-sensitive material having a very high
sensitivity, such as an ISO 1,600 photographic light-sensitive material, and also
a light-sensitive material which can be used in photography by means of a small-formatted
camera such a a 110-size system or a disk-size system, either exihibitying good graininess,
high sharpness and high color-reproducibility.
[0003] A technique of increasing the sensitivity of a silver halide emulsion is important
since it can provide a silver halide photographic material which has a sufficient
light-sensitivity even though the silver halide grains it contains are relative large.
[0004] Examples of a conventional method known as a chemical sensitization method of increasing
the sensitivity of a silver halide photographic emulsion are sulfur sensitization,
selenium sensitization, noble metal sensitization, reduction sensitization, and hydrogen
sensitization. These sensitization methods are used singly or in a combination of
two or more thereof. The sensitization methods are described in T.H. James, "The Theory
of the Photographic Process", 4th ed., Macmillan Co., 1977, pp. 149 to 160 and pp.
164 and 165.
[0005] In addition to the above sensitization methods, various types of emulsion manufacturing
methods using a silver halide solvent or a so-called stabilizer have been proposed
as the technique of increasing sensitivity.
[0006] In addition to the sensitization methods described above, the grain size of an emulsion
is increased as the sensitivity of a photographic light-sensitive material is increased.
In particular, in order to increase the sensitivity of a light-sensitive material
having ISO sensitivity of 1,600 or more, the grain size of an emulsion must be increased
(to be 1.4 µm or more).
[0007] Although the sensitivity of an emulsion can be increased by the above means, when
light sensitivity is to be increased by improving a sensitization method or by increasing
the grain size of an emulsion to increase the number of photons to be absorbed by
one grain, the following two problems arise:
1) Fog is increased.
2) Sensitivity is increased during storage after exposure (this phenomenon will be
referred to as "latent image sensitization" hereinafter).
[0008] As a conventional method of preventing fog, the use of compounds represented by the
following formulas [I] to [III] and polymers having as a repearting unit a divalent-group
derived from the compounds of formulas [I], [II] or [III] is proposed in U.S. Patent
3,047,393 for a silver iodobromide emulsion and JP-A-63-30425 (hereinafter "JP-A-"
means unexamined published Japanese patent application) for a high-temperature silver
emulsion.
[I]
R-SO₂S-M
[II]
R-SO₂S-R¹
[III]
R-SO₂S-Lm-SSO₂-R²
where R, R¹, and R² may be the same or different and independently represent an aliphatic
group, an aromatic group, or a heterocyclic group, M represents a cation, L represents
a divalent linking group, and m represents 0 or 1.
[0009] These proposals, however, do not describe a detailed use timing (addition timing)
of compounds represented by formulas [I] to [III] during an emulsion manufacturing
process nor mention the problem of item 2) above at all. In a color photograph, the
problem of item 2) causes a variation in color balance or gradation balance between
blue-, green-, and red-sensitive layers because storage stability after exposure is
poor. This means deterioration and a variation in photographic properties.
[0010] It is an object of the present invention to provide a silver halide emulsion exhibiting
high sensitivity, producing low fog, and having improved storage stability during
storage after exposure.
[0011] It is another object of the present invention to provide a silver halide photographic
light-sensitive material using the above emulsion and having high sensitivity, low
fog, and improved storage stability after exposure.
[0012] The above objects can be achieved according to the present invention by a silver
halide emulsion comprising light-sensitive silver halide grains in a binder, wherein
at least one oxidizing agent for silver is added after 5O% of water-soluble silver
salt used in grain formation of the silver halide emulsion are added and before chemical
sensitization is performed.
[0013] In a preffered embodiment, the oxidizing agent for silver is at least one selected
from the group consisting of compounds represented by formulas (I), (II), and (III),
and polymers having as a repeating unit a divalent group derived from the compounds
of formulas (I), (II) or (III):
(I)
R-SO₂S-M
(II)
R-SO₂-R¹
(III)
R-SO₂S-Lm-SSO₂-R²
where R, R¹, and R² may be the same or different and independently represent an aliphatic
group, an aromatic group, or an heterocyclic group, M represents a cation, L represents
a divalent linking group, and m represents 0 or 1, wherein R, R¹, R² and L may combine together, forming ring.
[0014] The present invention also provides a silver halide photographic light-sensitive
material comprising a support, and at least one silver halide emulsion layer formed
on the support, including at least one layer of the silver halide emulsion of the
invention described.
[0015] The present invention will be described in detail below.
[0016] In the present invention, an oxidizing agent for silver is a compound having an effect
of converting metal silver into silver ions. In particular, a compound capable of
converting vary small silver, which is by-produced during a silver halide grain formation
process, into silver ions is effective. The produced silver ions may form a silver
salt which is hardly dissolved in water such as a silver halide, silver sulfide, or
silver selenide, or may form a silver salt which is readily dissolved in water such
as silver nitrate.
[0017] The oxidizing agent for silver may be either an inorganic or organic substance. Examples
of an inorganic oxidizing agent are ozone, hydrogen peroxide and its adducts (e.g.,
NaBO₂·H₂O₂·3H₂O, 2NaCO₃·3H₂O₂, Na₄P₂O₇·2H₂O₂, and 2Na₂SO₄·H₂O₂·2H₂O), a salt of oxyacid
such as peroxate (e.g., K₂S₂O₈, K₂C₂O₆, and K₂P₂O₈), a peroxy complex compound (e.g.,
K₂[Ti(O₂)C₂O₄]·3H₂O, 4K₂SO₄·Ti(O₂), OH·SO₄·2H₂O, and Na₃[VO(O₂)(C₂O₄)₂]·6H₂O), permanganate
(e.g., KMnO₄), and chromate (e.g., K₂Cr₂O₇), a halogen element such as iodine and
bromine, perhalogenate (e.g., potassium periodate), a salt of a high-valence metal
(e.g., potassium hexacyanoferrate), and thiosulfonate.
[0018] Examples of an organic oxidizing agent are a quinone such as p-quinone, an organic
peroxide such as peracetic acid or perbenzoic acid, and a compound releasing an active
halogen (e.g., N-bromosuccinimide, chloramine T, and chloramine B).
[0019] In the present invention, preferred inorganic oxidizing agents include ozone, hydrogen
peroxide and its adducts, a halogen element, and thiosulfonate, and preferred organic
oxidizing agents include quinones.
[0020] A more preferable oxidizing agent for silver is a thiosulfonate selected from the
group consisting of compounds represented by formulas (I) to (III). Of these compounds,
a most preferable compound is a compound represented by formula (I) which converts
silver into silver sulfide.
(I)
R-SO₂S-M
(II)
R-SO₂S-R¹
(III)
R-SO₂S-Lm-SSO₂-R²
wherein R, R¹, and R² may be the same or different and independently represent an
aliphatic group, an aromatic group, or a heterocyclic group, M represents a cation,
L represents a divalent linking group, and m represents 0 or 1.
[0021] It should be noted that polymers having as a repeating unit a divalent group derived
from the compounds of formulas (I), (II) or (III) can be used instead of the compounds
of formula (I), (II) or (III). It is also possible to use, as an oxidizing agent,
the compound of formula (I), (II) or (III) in which R, R¹, R² and L are combined together
to form a ring.
[0022] Thiosulfonic acid compounds represented by formulas (I) to (III) will be described
in more detail below. When each of R, R¹, and R², represent an aliphatic group, it
is a saturated or unsaturated, straight-chain, branched, or cyclic aliphatic hydrocarbon
group and is preferably an alkyl group having 1 to 22 carbon atoms or an alkenyl or
alkinyl group having 2 to 22 carbon atoms. These groups may have substituents. Examples
of the alkyl group are methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, 2-ethylhexyl,
decyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, isopropyl, and t-butyl. Examples
of the alkenyl group are allyl and butenyl. Examples of the alkinyl group are propargyl
and butynyl.
[0023] When R, R¹, and R² each represent an aromatic group, it is an aromatic group of a
monocyclic or condensation-ring, preferably having 6 to 20 carbon atoms. Examples
of such an aromatic group are phenyl and naphthyl. These groups may be substituted.
[0024] When R, R¹, and R² each represent a heterocyclic group, it is a 3- to 15-membered
ring, preferably, a 3-to 6-membered ring having at least one element selected from
nitrogen, oxygen, sulfur, selenium, and tellurium and at least one carbon. Examples
of the heterocyclic group are a pyrrolidine ring, a piperidine ring, a pyridine ring,
a tetrahydrofurane ring, a thiophene ring, an oxazole ring, a thiazole ring, an imidazole
ring, a benzothiazole ring, a benzoxazole ring, a benzimidazole ring, a selenazole
ring, a benzoselenazole ring, a tellurazole ring, a triazole ring, a benzotriazole
ring, a tetrazole ring, an oxadiazole ring, and a thiadiazole ring.
[0025] Examples of the substituent on R, R1, and R2 are an alkyl group (e.g., methyl, ethyl,
and hexyl), an alkoxy group (e.g., methoxy, ethoxy, and octyloxy), an aryl group (e.g.,
phenyl, naphthyl, and tolyl), a hydroxy group, a halogen atom (e.g., fluorine, chlorine,
bromine, and iodine), an aryloxy group (e.g., phenoxy), an alkylthio group (e.g.,
methylthio and butylthio), an arylthio group (e.g., phenylthio), an acyl group (acetyl,
propionyl, butyryl, and valeryl), a sulfonyl group (e.g., methylsulfonyl and phenylsulfonyl),
an acylamino group (e.g., acetylamino and benzoylamino), a sulfonylamino group (e.
g., methanesulfonylamino and benzenesulfonylamino), an acyloxy group (e.g., acetoxy
and benzoxy), carboxyl, cyano, sulfo, amino, -SO₂SM (wherein M represents a monovalent
cation), and -SO₂R¹.
[0026] The divalent linking group represented by L is an atom or an atomic group containing
at least one element selected from C, N, S, and O. Examples of L are an alkylene group,
an alkenylene group, an alkynylene group, an arylene group, -O-, -S-, -NH-, -CO-,
and -SO₂-. These groups can be used singly or in a combination of two or more thereof.
[0027] L is preferably a divalent aliphatic group or a divalent aromatic group. Examples
of the divalent aliphatic group of L are (̵CH₂)̵
n (n = 1 to 12),
-CH₂-CH=CH-CH₂-, -CH₂C≡CCH₂-,

, and a xylylene group. Examples of the divalent aromatic group of L are a phenylene
group and a naphthylene group.
[0028] These substituting groups may be further substituted by the above-mentioned substituting
groups.
[0029] M is preferably a metal ion or an organic cation. Examples of the metal ion are a
lithium ion, a sodium ion, and a potassium ion. Examples of the organic cation are
an ammonium ion (e.g., ammonium, tetramethylammonium, and tetrabutylammonium), a phosphonium
ion (tetraphenylphosphonium), and a guanidil group.
[0030] When the oxidizing agent used in the present invention is one of polymers having
as a repeating unit a divalent group derived from the compound of formula (I), (II)
or (III), the examples of the repeating unit are as follows:

[0031] Each of the polymers mentioned above can be a homopolymer or a copolymer with another
copolymerizable monomer.
[0032] Examples of the compounds represented by formulas (I) to (III) and polymers having
as a repeating unit a divalent group derived from the formula (I), (II) or (III) are
listed in Table A below. However, the compounds are not limited to those shown in
Table A. The compounds of formulas (I) to (III) can easily be synthesized by the methods
described in JP-A-54-1019, British Patent 972,211, and Journal of Organic Chemistry,
Vol. 53, p. 396, 1988.
[0033] An addition amount of the oxidizing agent for silver per mol of silver salt of the
present invention is preferably 10⁻⁷ to 10⁻¹ mol, more preferably, 10⁻⁶ to 10⁻² mol,
and most preferably, 10⁻⁵ to 10⁻³ mol.
[0034] An addition timing of the oxidizing agent of the present invention will be described
below.
[0035] A method of manufacturing a silver halide emulsion mainly comprises grain formation,
desalting, chemical sensitization, and coating. The grain formation includes nucleation,
ripening, and growth. These steps may be performed not in the order mentioned. Some
of these steps may be performed in a reverse order further one or more steps may be
performed repeatedly.
[0036] An effect of the present invention cannot be obtained unless the oxidizing agent
is added after 50% of water-soluble silver salt used in grain formation of an emulsion
are added and before chemical sensitization is performed. When the oxidizing agent
is to be added during grain formation, it is preferably added after 80% of a water-soluble
silver salt used in grain formation are added. More preferably, thiosulfonate is added
after grain formation is ended and before chemical sensitization is started. When
the oxidizing agent is to be added during the desalting step, it can be added at any
time during the step. When the oxidizing agent is to be added before chemical sensitization
is performed, it is added before a sensitizer such as a gold, sulfur, or selenium
sensitizer is added. If a sensitizing dye is added prior to chemical sensitization,
the oxidizing agent is preferably added before addition of the sensitizing dye.
[0037] In order to add oxidizing agents represented by formulas (I) to (III), any conventional
method normally used to add additives to a photographic emulsion can be applied. For
example, the water-soluble compound can be added in the form of an aqueous solution
having any appropriate concentration, and the compound which is insoluble or hardly
dissolved in water can be dissolved in a proper organic solvent, e.g., alcohol, glycol,
ketone, ester, or amide which is miscible with water and has no influence on photographic
properties and added as a solution.
[0038] An average silver halide composition of the entire silver halide grains of the present
invention is silver iodobromide or silver iodochlorobromide, containing 1 to 30 mol%
of silver iodide. Preferably, this composition contains 7 to 20 mol% of silver iodide,
and may contain 10 mol% or less of silver chloride.
[0039] A silver halide grain to be used in the present invention can be selected from a
regular crystal not including a twinned crystal face and those described in Japan
Photographic Society ed., "Silver Salt Photographs, Basis of Photographic Industries",
(Corona Co., p. 163) such as a single twinned crystal including one twinned crystal
face, a parallel multiple twinned crystal including two or more parallel twinned crystal
faces, and a non-parallel multiple twinned crystal including two or more non-parallel
twinned crystal faces in accordance with its applications. In the case of a regular
crystal, a cubic grain consisting of (100) faces, an octahedral grain consisting of
(111) faces, and a dodecahedral grain consisting of (110) faces disclosed in JP-B-55-42737
("JP-B-" means examined published Japanese patent application) and JP-A-60-222842
can be used. In addition, a grain consisting of (hll) faces, e.g., (211) faces, a
grain consisting of (hhl), e.g., (331) faces, a grain consisting of (hk0), e.g., (210)
faces, and a grain consisting of (hkl), e.g., (321) faces as reported in "Journal
of Imaging Science", Vol. 30, p. 247, 1986 can be selectively used in accordance with
an application although a preparation method must be improved. A grain including two
or more types of faces, e.g., a tetradecahedral grain consisting of both (100) and
(111) faces, a grain consisting of both (100) and (110) faces, and a grain consisting
of both (111) and (110) faces can be selectively used in accordance with an application.
[0040] The silver halide grain of the present invention may be a fine grain having a grain
size of 0.1 microns or less or a large grain having a projected surface area diameter
of 10 microns.
[0041] Although the effect of the present invention can be achieved by either a monodisperse
or polydisperse emulsion, a monodisperse emulsion is more preferable. In this case,
"monodisperse" is defined such that at least a variation coefficient of a circle-equivalent
diameter of a projected area of a grain or a variation coefficient of a sphere-equivalent
diameter of a grain volume is 20% or less, and more preferably, 15% or less.
[0042] The photographic emulsion for use in the present invention can be prepared by using
methods described in, for example, P. Glafkides, "Chimie et Physique Photographique",
Paul Montel, 1967; Duffin, "Photographic Emulsion Chemistry", Focal Press, 1966; and
V.L. Zelikman et al., "Making and Coating Photographic Emulsion", Focal Press, 1964.
That is, the photographic emulsion can be prepared by, e.g., an acid method, a neutralization
method, and an ammonia method. Also, as a system for reacting a soluble silver salt
and a soluble halide, the single-jet method, the double-jet method, or a combination
thereof can be used. Also, a so-called reverse mixing method of forming silver halide
grains in the presence of excessive silver ions can be used. As one system of the
double-jet method, a so-called controlled double-jet method wherein the pAg in the
liquid phase generated by the silver halide is kept at a constant value can be used.
According to this method, a silver halide emulsion having a regular crystal form and
almost uniform grain sizes is obtained.
[0043] The silver halide emulsion containing the above-described regular silver halide grains
can be obtained by controlling the pAg and pH during grain formation. More specifically,
such a method is described in "Photographic Science and Engineering" Vol. 6, 159-165
(1962); "Journal of Photographic Science", Vol. 12, 242-251 (1964); U.S. Patent 3,655,394,
and British Patent 1,413,748.
[0044] A tabular grain having an aspect ratio of 3 or more can also be preferably used in
the present invention. The tabular grain can be easily prepared by methods described
in, for example, Cleve, "Photography Theory and Practice", (1930), p. 131; Gutoff,
"Photographic Science and Engineering", Vol. 14, pp. 248 to 257, (1970); and U.S.
Patents 4,434,226, 4,414,310, 4,433,048, and 4,439,520, and British Patent 2,112,157.
When the tabular grain is used, covering power and a color sensitizing efficiency
of a sensitizing dye can be advantageously improved as described in detail in U.S.
Patent 4,434,226.
[0045] The tabular grains are preferably used in the emulsion of the present invention.
In particular, tabular grains in which grains having aspect ratios of 3 or more account
for 60% or more of a total projected area are preferable. Tabular grains in which
grains having aspect ratios of 3 to 10 account for 60% or more of a total projected
area are most preferable. Also in the case of tabular grains, a grain size distribution
is preferably monodisperse. A variation coefficient of a circle-equivalent diameter
of a projected area or a sphere-equivalent diameter of a volume is preferably 25%
or less, more preferably, 20% or less, and most preferably, 15% or less.
[0046] In the silver halide emulsion used in the present invention, a crystal structure
of the silver halide grain may be uniform, may have different halogen compositions
inside and outside a crystal, or may be a layered structure. These emulsion grains
are disclosed in, e.g., British Patent 1,027,146, U.S. Patents 3,505,068 and 4,444,877,
and Japanese Patent Application No. 58-248469. In addition, silver halides having
different compositions may be bonded by an epitaxial junction, or a compound other
than silver halides such as silver rhodanate or zinc oxide may be bonded.
[0047] If the silver halide emulsion of the present invention is a silver iodobromide emulsion
and has a uniform halogen composition, the emulsion preferably comprises silver iodobromide
containing 20 mol% or less of silver iodide. A preferable silver iodide content changes
in accordance with an application. For example, if an emulsion is required to have
a high developing rate, the content of silver iodide is preferably 10 mol% or less,
and more preferably, 5 mol% or less. If an emulsion is required to have a soft tone,
the emulsion is sometimes designed to have a comparatively high silver iodide content.
In this case, the silver iodide content is preferably 5 mol% or more.
[0048] The silver halide emulsion of the present invention preferably can have a distribution
or structure of a halogen composition in its grain. A typical example is a core-shell
type or double structured grain having different halogen compositions in the interior
and surface layer of the grain as disclosed in, e.g., JP-B-43-13162 (Hereinafter "JP-B-"
means Examined Published Japanese Patent Application), JP-A-61-215540, JP-A-60-22284,
and JP-A-61-75337. In such a grain, the shape of a core portion is sometimes identical
to or sometimes different from that of the entire grain with a shell. More specifically,
while the core portion is cubic, the grain with a shell is sometimes cubic or sometimes
octahedral. On the contrary, while the core portion is octahedral, the grain with
a shell is sometimes cubic or sometimes octahedral. In addition, while the core portion
is a clear regular grain, the grain with a shell is sometimes slightly deformed or
sometimes does not have any definite shape. Furthermore, not a simple double structure
but a triple structure as disclosed in JP-A-60-222844 or a multilayered structure
of more layers can be formed, or a silver halide having a different halogen composition
can be thinly formed on the surface of a core-shell double structure grain.
[0049] In order to give the structure inside the grain, a grain having not only the above
surrounding structure but a so-called junction structure can be made. Examples of
such a grain are disclosed in, e.g., JP-A-59-133540, JP-A-58-108526, EP 199290A2,
JP-B-5824772, and JP-A-59-16254. A crystal to be bonded can be produced to have a
composition different from that of a host crystal and in contact with an edge, corner,
or face portion of the host crystal. Such a junction crystal can be formed regardless
of whether the host crystal has a homogeneous halogen composition or a core-shell
structure.
[0050] The junction structure can be naturally made by a combination of silver halides.
In addition, the junction structure can be made by combining a silver salt compound
not having a rock salt structure, e.g., silver rhodanate or silver carbonate with
a silver halide. A non-silver salt compound such as PbO can also be used as long as
the junction structure can be made.
[0051] In a silver iodobromide grain having the above structure, e.g., in a core-shell type
grain, the silver iodide content may be high at a core portion and low at a shell
portion or vice versa.
[0052] Also in a grain having a structure in the silver iodide content, a preferable silver
iodide content on the grain surface changes in accordance with an application. For
example, if an emulsion is required to have a high developing rate, the silver iodide
content on the grain surface is preferably 10 mol% or less, and more preferably, 5
mol% or less. If an emulsion is required to have a soft tone, the emulsion is sometimes
designed to have a comparatively high silver iodide content on the grain surface.
In this case, the silver iodide content is preferably 5 mol% or more.
[0053] In order to obtain a desired silver iodide content on the grain surface, a silver
iodide content in a shell portion may be set to be a desired content, or a thin silver
halide having a desired composition may be adhered on the surface of a grain.
[0054] Similarly, in a grain having the junction structure, the silver iodide content may
be high in a host crystal and relatively low in a junction crystal or vice versa.
[0055] In a grain having the above structure, a boundary between portions having different
halogen compositions may be clear or unclear due to a crystal mixture formed by a
composition difference. Alternatively, a continuous structure change may be positively
made in the boundary portions.
[0056] The silver halide emulsion for use in the present invention can be subjected to a
treatment for rounding a grain as disclosed in, e.g., EP-0096727B1 and EP-0064412B1
or a treatment of modifying the surface of a grain as disclosed in DE-2306447C2 and
JP-A-60-221320.
[0057] The silver halide emulsion for use in the present invention is preferably of a surface
latent image type. An interlal latent image type emulsion, however, can be used by
selecting a developing solution or development conditions as disclosed in JP-A-59-133542.
In addition, a shallow internal latent image type emulsion covered with a thin shell
can be used in accordance with an application.
[0058] A silver halide solvent can be effectively used to promote ripening for grains. For
example, in a known conventional method, an excessive amount of halogen ions are supplied
in a reactor vessel in order to promote ripening. Therefore, it is apparent that ripening
can be promoted by only supplying a silver halide solution into a reactor vessel.
In addition, another ripening agent can be used. In this case, a total amount of these
ripening agents can be mixed in a dispersion medium in the reactor vessel before a
silver salt and a halide are added therein, or they can be added in the reactor vessel
together with one or more halides, a silver salt or a deflocculant. Alternatively,
the ripening agents can be added independently, in steps of adding a halide and a
silver salt.
[0059] Examples of the ripening agent other than the halogen ion are ammonia, an amine compound
and a thiocyanate such as an alkali metal thiocyanate, especially sodium or potassium
thiocyanate and ammonium thiocyanate.
[0060] The silver halide grains of the present invention are subjected to at least one of
sulfur sensitization, gold sensitization, and noble metal sensitization in an arbitrary
step of silver halide emulsion manufacturing steps, and typically, a grain formation
step. Although these methods of chemical sensitization charge in accordance with the
composition, structure, and shape of emulsion grains or an application of the emulsion,
a chemical sensitization nucleus is embedded inside a grain, embedded in a shallow
portion from the grain surface, or formed on the grain surface. Although the present
invention is effective in any case, the chemical sensitization nucleus is most preferably
formed in a portion near the surface. That is, the present invention is more effective
in the surface latent image type emulsion than in the internal latent image type emulsion.
[0061] As chemical sensitization which can be preferably performed in the present invention
(to be referred to as simply chemical sensitization hereinafter), gold sensitization,
sulfur sensitization, and noble metal sensitization can be performed singly or in
a combination of two or more thereof. Chemical sensitization can be performed by using
active gelatin as described in T.H. James, "The Theory of the Photographic Process",
4th ed., Macmillan, 1977, pp. 67 to 76. Alternatively, chemical sensitization can
be performed at a pAg of 5 to 10, a pH of 5 to 8 and a temperature of 30°C to 80°C
by using sulfur, selenium, tellurium, gold, platinum, palladium or irridium, or a
combination of a plurality of these sensitizers as described in Research Disclosure
(to be referred to as simply "RD" hereinafter) Vol. 120, No. 12,008 (April, 1974)
and vol. 34, No. 13,452 (June, 1975), U.S. Patents 2,642,361, 3,297,446, 3,772,031,
3,857,711, 3,901,714, 4,266,018, and 3,904,415, and British Patent 1,315,755. Chemical
sensitization is optimally performed in the presence of a gold compound and a thiocyanate
compound, a sulfur-containing compound described in U.S. Patents 3,857,711, 4,266,018,
and 4,054,457 or a sulfur-containing compound such as a hypo, thiourea compound and
a rhodanine compound.
[0062] Chemical sensitization can also be performed in the presence of a chemical sensitization
assistant. An effective example of the chemical sensitization assistant is a compound
known to suppress fog and increase sensitivity in the chemical sensitization process
such as azaindene, azapyridazine, and azapyrimidine. Examples of a chemical sensitization
assistant modifier are described in U.S. Patents 2,131,038, 3,411,914, 3,554,757,
JP-A-58-126526 and G.F. Duffin, "Photographic Emulsion Chemistry", pp. 138 to 143.
[0063] The emulsion of the present invention exhibits a preferable effect by using gold
sensitization. A preferable amount of the gold sensitizer is 1 × 10⁻⁴ to 1 × 10⁻⁷
mol, and more preferably, 1 × 10⁻⁵ to 5 × 10⁻⁷ mol per mol of a silver halide.
[0064] A preferable amount of the sulfur sensitizer used with respect to silver halide grains
of the present invention is 1 × 10⁻⁴ to 10⁻⁷, and more preferably, 1 × 10⁻⁵ to 5 ×
10⁻⁷ mol per mol of a silver halide.
[0065] Both the above conditions are preferably used in gold·sulfur sensitization.
[0066] The silver halide grains of the present invention are preferably reduction-sensitized
during grain formation, after grain formation and before chemical sensitization, during
chemical sensitization, or after chemical sensitization.
[0067] As a method of reduction sensitization, a method of adding a reduction sensitizer
to a silver halide emulsion, a method called silver ripening in which growth or ripening
is performed in a low-pAg atmosphere having a pAg of 1 to 7, and a method called high
pH ripening in which growth or ripening is performed in a high-pH atmosphere having
pH of 8 to 11 can be selectively used. Alternatively, these methods can be used in
a combination of two or more thereof.
[0068] The method of adding a reduction sensitizer is preferable since the level of reduction
sensitization can be finely adjusted.
[0069] Known examples of a reduction sensitizer are stannous chloride, ascorbic acid and
its derivatives, amine and polyamine, a hydrazine derivative, formamidinesulfinic
acid, a silane compound, and a borane compound. In the reduction sensitization of
the present invention, these known reduction sensitizers can be used selectively or
in a combination of two or more thereof. Preferable compounds as a reduction sensitizer
are stannous chloride, thiourea dioxide, dimethylamineborane, and ascorbic acid and
its derivatives. Although an addition amount of the reduction sensitizer must be selected
in accordance with the emulsion manufacturing conditions, it is preferably 10⁻⁷ to
10⁻³ mol per mol of a silver halide.
[0070] The reduction sensitizer is dissolved in water or a solvent such as alcohol, glycol,
ketone, ester, or amide and added during grain formation. Although the reduction sensitizer
may be added in a reactor vessel before again growth, it is more preferably added
at an arbitrary timing during grain growth. The reduction sensitizer may be previously
added to an aqueous solution of water-soluble silver salt or water-soluble alkali
halide, and the solution may be used to precipitate silver halide grains. Alternatively,
a solution of the reduction sensitizer may be preferably added several times or continuously
over a long time period as grain growth progresses.
[0071] The photographic emulsion of the present invention can contain various compounds
in order to prevent fog during manufacture, storage, or a photographic treatment of
the light-sensitive material or to stabilize photographic properties. Examples of
the compound known as an antifoggant or stabilizer are azoles, e.g., benzothiazolium
salt, nitroimidazole, nitrobenzimidazole, chlorobenzimidazole, bromobenzimidazole,
mercaptothiazole, mercaptobenzothiazole, mercaptobenzimidazole, mercaptothiadiazole,
aminotriazole, benzotriazole, nitrobenzotriazole, and mercaptotetrazole (especially,
1-phenyl-5-mercaptotetrazole); mercaptopyrimidine; mercaptotriadine; a thioketo compound
such as oxadrinthione; azaindene, e.g., triazaindene, tetraazaindene (especially,
4-hydroxy-substituted (1,3,3a,7)tetraazaindene), and pentaazaindene. Examples are
described in U.S. Patents 3,954,474 and 3,982,947 and JP-B-52-28660.
[0072] The photographic emulsion of the present invention can be spectrally sensitized with,
e.g., a methine dye. Examples of the dye are a cyanine dye, a merocyanine dye, a composite
cyanine dye, a composite merocyanine dye, a holopolar cyanine dye, a hemicyanine dye,
a styryl dye, and hemioxonol dye. Most effective dyes are those belonging to a cyanine
dye, a merocyanine dye, and a composite merocyanine dye. In these dyes, any nucleus
normally used as a basic heterocyclic nucleus in cyanide dyes can be used. Examples
of the nucleus are pyrroline nucleus, an oxazoline nucleus, a thiozoline nucleus,
a pyrrole nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus, an
imidazole nucleus, a tetrazole nucleus, and a pyridine nucleus; a nucleus obtained
by fusing an alicyclic hydrocarbon ring to each of the above nuclei; and a nucleus
obtained by fusing an aromatic hydrocarbon ring to each of the above nuclei, e.g.,
an indolenine nucleus, a benzindolenine nucleus, an indole nucleus, a benzoxadole
nucleus, a naphthooxazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus,
a benzoselenazole nucleus, a benzimidazole nucleus, and a quinoline nucleus. These
nuclei may be substituted on a carbon atom.
[0073] As a merocyanine dye or a composite merocyanine dye, a 5- or 6-membered heterocyclic
nucleus, e.g., a pyrazoline-5-one nucleus, a thiohydantoin nucleus, a 2-thioxazolidine-2,4-dione
nucleus, a thiazolidine-2,4-dione nucleus, a rhodanine nucleus, and a thiobarbituric
acid nucleus can be used as a nucleus having a ketomethylene structure.
[0074] These sensitizing dyes can be used singly or in a combination of two or more thereof.
A combination of the sensitizing dyes is often used especially in order to perform
supersensitization. Typical examples of the combination are described in U.S. Patents
2,688,545, 2,977,229, 3,397,060, 3,522,052, 3,527,641, 3,617,293, 3,628,964, 3,666,480,
3,672,898, 3,679,428, 3,703,377, 3,769,301, 3,814,609, 3,837,862, 4,026,707, British
Patents 1,344,281 and 1,507,803, JP-B-43-4936 and JP-B-53-12375, and JP-A-52-110618
and JP-A-52-109925.
[0075] The emulsion may contain, in addition to the sensitizing dye, a dye not having a
spectral sensitizing effect or a substance substantially not absorbing visible light
and having supersensitization.
[0076] The dye can be added in the emulsion at any timing conventionally known to be effective
in emulsion preparation. Most ordinarily, the dye is added after completion of chemical
sensitization and before coating. However, the dye can be added at the same time as
a chemical sensitizer to simultaneously perform spectral sensitization and chemical
sensitization as described in U.S. Patents 3,628,969 and 4,225,666, added before chemical
sensitization as described in JP-B-58-113928, or added before completion of silver
halide grain precipitation to start spectral sensitization. In addition, as described
in U.S. Patent 4,225,666, the above compound can be separately added such that a portion
of the compound is added before chemical sensitization and the remaining portion is
added thereafter. That is, as described in U.S. Patent 4,183,756, the compound can
be added at any timing during silver halide grain formation.
[0077] Although the dye can be preferably added at any of the above addition timings in
the-present invention, it is more preferably added prior to chemical sensitization
or before precipitation of silver halide grains is completed. Most preferably, the
dye is added prior to chemical sensitization.
[0078] An addition amount of the dye may be 4 × 10⁻⁶ to 8 × 10⁻³ mol per mol of a silver
halide. In the case of a prefarable silver halide grain size is 0.1 to 1.2 µm, an
addition amount of about 5 × 10⁻⁵ to 2 × 10⁻³ mol per mol of a silver halide is more
effective.
[0079] The above various additives are used in the light-sensitive material of the present
invention. In addition to the above additives, however, various additives can be used
in accordance with applications.
[0080] These additives are described in RD., Item 17643 (Dec. 1978) and Item 18716 (Nov.
1979) and they are summarized in the following table.
[0081] A spectral sensitizing dye used in the present invention can be used together with
a nitrogen-containing heterocyclic compound represented by the following formula described
in JP-A062089952: Formula

wherein R⁹ represents an aliphatic, aromatic, or heterocyclic group substituted by
at least one -COOM¹ or -SO₃M¹ and M¹ represents a hydrogen atom, an alkali metal atom,
a quaternary ammonium, or quaternary phosphonium.
[0082] An addition amount of the above compound is 1 × 10⁻⁵ to 1 × 10⁻² mol, and preferably,
1 × 10⁻⁴ to 1 × 10⁻³ mol per mol of a silver halide.

[0083] In this invention, various color couplers can be used in the light-sensitive material.
Specific examples of these couplers are described in above-described RD., No. 17643,
VII-C to VII-G as patent references.
[0084] Preferred examples of a yellow coupler are described in, e.g., U.S. Patents 3,933,501,
4,022,620, 4,326,024, and 4,401,752, JP-B-58-10739, and British Patents 1,425,020
and 1,476,760.
[0085] Examples of a magenta coupler are preferably 5-pyrazolone and pyrazoloazole compounds,
and more preferably, compounds described in, e.g., U.S. Patents 4,310,619 and 4,351,897,
EP 73,636, U.S. Patents 3,061,432 and 3,725,067, RD. No. 24220 (June 1984), JP-A-60-33552,
RD. No. 24230 (June 1984), JP-A-60-43659, and U.S. Patents 4,500,630 and 4,540,654.
[0086] Examples of a cyan coupler are phenol and naphthol couplers, and preferably, those
described in, e.g., U.S. Patents 4,052,212, 4,146,396, 4,228,233, 4,296,200, 2,369,929,
2,801,171, 2,772,162, 2,895,826, 3,772,002, 3,758,308, 4,334,011, and 4,327,173, West
German Patent Application (OLS) No. 3,329,729, EP 121,365A, U.S. Patents 3,446,622,
4,333,999, 4,451,559, and 4,427,767, and EP 161,626A.
[0087] Preferable examples of a colored coupler for correcting additional, undesirable absorption
of a colored dye are those described in RD. No. 17643, VII-G, U.S. Patent 4,163,670,
JP-B-57-39413, U.S. Patents 4,004,929 and 4,138,258, and British Patent 1,146,368.
[0088] Preferable examples of a coupler capable of forming colored dyes having proper diffusibility
are those described in U.S. Patent 4,366,237, British Patent 2,125,570, EP 96,570,
and West German Patent Application (OLS) No. 3,234,533.
[0089] Typical examples of a polymerized dye-forming coupler are described in U.S. Patents
3,451,820, 4,080,211, and 4,367,282, and British Patent 2,102,173.
[0090] Couplers releasing a photographically useful residue upon coupling are preferably
used in the present invention. Preferable examples of a DIR coupler releasing a development
inhibitor are described in the patents cited in the above-described RD. No. 17643,
VII-F, JP-A-57-151944, JP-A-57-154234, JP-A-60-184248, and U.S. Patent 4,248,962.
[0091] Preferable examples of a coupler imagewise releasing a nucleating agent or a development
accelerator upon development are those described in British Patent 2,097,140, 2,131,188,
and JP-A-157638 and JP-A-59-170840.
[0092] Examples of a coupler which can be used in the light-sensitive material of the present
invention are competing couplers described in, e.g., U.S. Patent 4,130,427; poly-equivalent
couplers described in, e.g., U.S. Patents 4,283,472, 4,338,393, and 4,310,618; DIR
redox compound, a DIR coupler, a DIR coupler releasing coupler, and a DIR coupler
releasing redox compound described in, e.g., JP-A-60-185950 and JP-A-62-24252; couplers
releasing a dye which turns to a colored form after being split off described in EP
173,302A; bleaching accelerator releasing couplers described in, e.g., RD. Nos. 11449
and 24241 and JP-A-61-201247; and a legand releasing coupler described in, e.g., U.S.
Patent 4,553,477.
[0093] The couplers for use in this invention can be introduced in the light-sensitive material
by various known dispersion methods.
[0094] Examples of a high-boiling solvent used in an oil-in-water dispersion method are
described in, e.g., U.S. Patent 2,322,027.
[0095] Examples of a high-boiling organic solvent to be used in the oil-in-water dispersion
method and having a boiling point of 175°C or more at normal pressure are phthalic
ester (e.g., dibutylphthalate, dicyclohexylphthalate, di-2-ethylhexylphthalate, decylphthalate,
bis(2,4-di-t-amylphenyl)phthalate, bis(2,4-di-t-amylphenyl)isophthalate, and bis(1,1-diethylpropyl)phthalate),
phosphate or phosphonate (e.g., triphenylphosphate, tricresylphosphate, 2-ethylhexyldiphenylphosphate,
tricyclohexylphosphate, tri-2-ethylhexylphosphate, tridodecylphosphate, tributoxyethylphosphate,
trichloropropylphosphate, and di-2-ethylhexylphenylphosphonate), benzoate (e.g., 2-ethylhexylbenzoate,
dodecylbenzoate, and 2-ethylhexyl-p-hydroxybenzoate), amide (e.g., N,N-diethyldodecaneamide,
N,N-diethyllaurylamide, and N-tetradecylpyrrolidone), alcohol or phenol (e.g., isostearylalcohol
and 2,4-di-tert-amylphenol), aliphatic carboxylate (e.g., bis(2-ethylhexyl)sebacate,
dioctylazelate, glyceroltributylate, isostearyllactate, and trioctylcitrate), an aniline
derivative (e.g., N,N-dibutyl-2-butoxy-5-tert-octylaniline), and a hydrocarbon (e.g.,
paraffin, dodecylbenzene, diisopropylnaphthalene). An organic solvent having a boiling
point of about 30°C or more, and preferably, 50°C to about 160°C can be used as a
co-solvent. Typical examples of the co-solvent are ethyl acetate, butyl acetate, ethyl
propionate, methylethylketone, cyclohexane, 2-ethoxyethylacetate, and dimethylformamide.
[0096] Steps and effects of a latex dispersion method and examples of an impregnating latex
are described in, e.g., U.S. Patent 4,199,363 and West German Patent Application (OLS)
Nos. 2,541,274 and 2,541,230.
[0097] The present invention can be applied to various color light-sensitive materials.
Examples of the material are a color negative film for a general purpose or a movie,
a color reversal film for a slide or a television, color paper, a color positive film,
and color reversal paper.
[0098] When the present invention is used as a color photographic material, the present
invention can be applied to light-sensitive materials having various structures and
to light-sensitive materials having combinations of layer structures and special color
materials.
[0099] Typical examples are: light-sensitive materials in which a coupling speed of a color
coupler or diffusibility is combined with a layer structure, as disclosed in, e.g.,
JP-B-47-49031, JP-B-49-3843, JP-B-50-21248, JP-A-59-58147, JP-A-59-60437, JP-A-60-227256,
JP-A-61-4043, JP-A-61-43743, and JP-A-61-42657; light-sensitive materials in which
a single color-sensitive layer is divided into two or more layers, as disclosed in
JP-B-49-15495 and U.S. Patent 3,843,469; and light-sensitive materials in which an
arrangement of high- and low-sensitivity layers or layers having different color sensitivities
is defined, as disclosed in JP-B-53-37017, JP-B-53-37018, JP-A-51-49027, JP-A-52-143016,
JP-A-53-97424, JP-A-53-97831, JP-A-62-200350, and JP-A-59-177551.
[0100] Examples of a support suitable for use in this invention are described in the above-mentioned
RD. No. 17643, page 28 and ibid., No. 18716, page 647, right column to page 648, left
column.
[0101] The color photographic light-sensitive materials of this invention can be developed
by the conventional methods as described in, e.g., the above-described Research Disclosure,
No. 17643, pages 28 to 29 and ibid., No. 18716, page 651, left to right columns.
[0102] A color developer used in developing of the light-sensitive material of the present
invention is, preferably, an aqueous alkaline solution containing, as a main component,
an aromatic primary amine-based color developing agent. As the color developing agent,
although an aminophenol-based compound is effective, a p-phenylenediamine-based compound
is preferably used. Typical examples of the p-phenylenediamine-based compound are
3-methyl-4-amino-N,N-diethylaniline, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline,
3-methyl-4-amino-N-ethyl-N-β-methanesulfonamidoethylaniline, ³-methyl-4-amino-N-ethyl-N-β-methoxyethylaniline,
and sulfates, hydrochlorides, and p-toluenesulfonates thereof. These compounds can
be used in a combination of two or more thereof in accordance with applications.
[0103] In general, the color developer contains a pH buffering agent such as a carbonate,
a borate or a phosphate of an alkali metal, and a development restrainer or antifoggant
such as a bromide, an iodide, a benzimidazole, a benzothiazole or a mercapto compound.
If necessary, the color developer may also contain a preservative such as hydroxylamine,
diethylhydroxylamine, sulfite, a hydrozine, a phenylsemicarbazide, triethanolamine,
a catechol sulfonic acid or a triethylenediamine(1,4-diazabicyclo[2,2,2]octane); an
organic solvent such as ethyleneglycol or diethyleneglycol; a development accelerator
such as benzylalcohol, polyethyleneglycol, a quaternary ammonium salt or an amine;
a dye forming coupler; a competing coupler; a fogging agent such as sodium boron hydride;
an auxiliary developing agent such as 1-phenyl-3-pyrazolidone; a viscosity imparting
agent; and a chelating agent such as an aminopolycarboxylic acid, an aminopolyphosphonic
acid, and alkylphosphonic acid or a phosphonocarboxylic acid. Examples of the chelating
agent are ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic
acid, cyclohexanediaminetetraacetic acid, hydroxyethyliminodiacetic acid, 1-hydroxyethylidene-1,1-diphosphonic
acid, nitrilo-N,N,N-trimethylenephosphonic acid, ethylenediamine-N,N,N',N'-tetramethylenephosphonic
acid and ethylenediamine-di(o-hydroxyphenylacetic acid), and salts thereof.
[0104] In order to perform reversal development, black-and-white development is performed
and then color development is performed. As a black-and-white developer, well-known
black-and-white developing agents, e.g., a dihydroxybenzene such as hydroquinone,
a 3-pyrazolidone such as 1-phenyl-3-pyrazolidone, and an aminophenol such as N-methyl-p-aminophenol
can be used singly or in a combination of two or more thereof.
[0105] The pH of the color and black-and-white developers is generally 9 to 12. Although
a replenishment amount of the developer depends on a color photographic light-sensitive
material to be processed, it is generally 3 liters or less per m² of the light-sensitive
material. The replenishment amount can be decreased to be 500 mℓ or less by decreasing
a bromide ion concentration in a replenishing solution. In order to decrease the replenishment
amount, a contact area of a processing tank with air is preferably decreased to prevent
evaporation and oxidation of the solution upon contact with air. The replenishment
amount can be decreased by using a means capable of suppressing an accumulation amount
of bromide ions in the developer.
[0106] A color development time is normally set between 2 to 5 minutes. The processing time,
however, can be shortened by setting a high temperature and a high pH and using the
color developing agent at a high concentration.
[0107] The photographic emulsion layer is generally subjected to bleaching after color development.
The bleaching may be performed either simultaneously with fixing (bleach-fixing) or
independently thereof. In addition, in order to increase a processing speed, bleach-fixing
may be performed after bleaching. Also, processing may be performed in a bleach-fixing
bath having two continuous tanks, fixing may be performed before bleach-fixing, or
bleaching may be performed after bleach-fixing, in accordance with applications. Examples
of the bleaching agent are a compound of a multivalent metal such as iron (III), cobalt
(III), chromium (VI) and copper (II); a peroxide; a quinone; and a nitro compound.
Typical examples of the bleaching agent are a ferricyanide; a dichromate; an organic
complex salt of iron (III) or cobalt (III), e.g., a complex salt of iron (III) or
cobalt (III) with an aminopolycarboxylic acid such as ethylenediaminetetraacetic acid,
diethylenetriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, methyliminodiacetic
acid, 1,3-diaminopropanetetraacetic acid, and glycoletherdiaminetetraacetic acid,
or a complex salt of iron (III) or cobalt (III) with citric acid, tartaric acid or
malic acid; a persulfate; a bromate; a permanganate; and a nitrobenzene. Of these
compounds, an iron (III) complex salt of aminopolycarboxylic acid such as an iron
(III) complex salt of ethylenediaminetetraacetic acid, and a persulfate are preferred
because they can increase a processing speed and prevent an environmental contamination.
The iron (III) complex salt of aminopolycarboxylic acid is effective in both the bleaching
and bleach-fixing solutions. The pH of the bleaching or bleach-fixing solution using
the iron (III) complex salt of aminopolycarboxylic acid is normally 5.5 to 8. In order
to increase the processing speed, however, processing can be performed at a lower
pH.
[0108] A bleaching accelerator can be used in the bleaching solution, the bleach-fixing
solution and their pre-bath, if necessary. Effective examples of the bleaching accelerator
are compounds having a mercapto group or a disulfide group described in, e.g., U.S.
Patent 3,893,858, West German Patents 1,290,812 and 2,059,988, JP-A-53-32736, JP-A-53-57831,
JP-A-53-37418, JP-A-53-72623, JP-A-53-95630, JP-A-53-95631, JP-A-53-104232, JP-A-53-124424,
JP-A-53-141623, JP-A-53-28426, and RD. No. 17,129 (July, 1978); a thiazolidine derivative
described in JP-A-50-140129; thiourea derivatives described in JP-B-45-8506, JP-A-52-20832,
JP-A-53-32735, and U.S. Patent 3,706,561; an iodide described in West German Patent
1,127,715; polyoxyethylene compounds described in West German Patents 966,410 and
2,748,430; a polyamine compound described in JP-B-45-8836; compounds described in
JP-A-49-42434, JP-A-49-59644, JP-A-53-94927, JP-A-54-35727, JP-A-55-26506, and JP-A-58-163940;
and a bromine ion. Of these compounds, compounds having a mercapto group or a disulfide
group are preferable since they have a great accelerating effect. In particular, compounds
described in U.S. Patent 3,893,858, West German Patent 1,290,812, and JP-A-53-95630
are preferable. A compound described in U.S. Patent 4,552,834 is also preferable.
These bleaching accelerators may be added in the light-sensitive material. These bleaching
accelerators are effective especially in bleach-fixing of a photographic color light-sensitive
material.
[0109] Examples of the fixing agent are a thiosulfate, a thiocyanate, a thioether-based
compound, a thiourea and a large amount of an iodide. Of these compounds, a thiosulfate,
especially, ammonium thiosulfate can be used in a widest range of applications. As
a preservative of the bleach-fixing solution, a sulfite, a bisulfite or a carbonyl
bisulfite adduct is preferred.
[0110] The photographic light-sensitive material of the present invention is normally subjected
to washing and/or stabilizing steps after desilvering. An amount of water used in
the washing step can be arbitrarily determined over a broad range in accordance with
the properties (e.g., a property determined by used substance such as a coupler) of
the light-sensitive material, the application of the material, the temperature of
the water, the number of water tanks (the number of stages), a replenishing scheme
representing a counter or forward current, and other conditions. The relationship
between the amount of water and the number of water tanks in a multi-stage counter-current
scheme can be obtained by a method described in "Journal of the Society of Motion
Picture and Television Engineers", Vol. 64, pp. 248 - 253 (May, 1955).
[0111] According to the above-described multi-stage counter-current scheme, the amount of
water used for washing can be greatly decreased. Since washing water stays in the
tanks for a long period of time, however, bacteria multiply and floating substances
may be undesirably attached to the light-sensitive material. In order to solve this
problem in the process of the color photographic light-sensitive material of the present
invention, a method of decreasing calcium and magnesium ions can be effectively utilized,
as described in Japanese Patent Application No. 61-131632. In addition, a germicide
such as an isothiazolone compound and cyabendazole described in JP-A-57-8542, a germicide
of chlorine-series such as chlorinated sodium isocyanurate, and germicides such as
benzotriazole described in Hiroshi Horiguchi, "Chemistry of Antibacterial and Antifungal
Agents", Eiseigijutsu-kai ed., "Sterilization, Antibacterial, and Antifungal Techniques
for Microorganisms", and Nippon Bokin Bokabi Gakkai ed., "Cyclopedia of Antibacterial
and Antifungal Agents".
[0112] The pH of the water for washing the photographic light-sensitive material of the
present invention is 4 to 9, and preferably 5 to 8. The water temperature and the
washing time can vary in accordance with the properties and applications of the light-sensitive
material. Normally, the washing time is 20 seconds to 10 minutes at a temperature
of 15°C to 45°C, and preferably, 30 seconds to 5 minutes at 25°C to 40°C. The light-sensitive
material of the present invention can be processed directly by a stabilizing agent
in place of washing. All known methods described in JP-A-57-8543, JP-A-58-14834, and
JP-A-60-220345 can be used in such stabilizing processing.
[0113] Stabilizing is sometimes performed subsequently to washing. An example is a stabilizing
bath containing formalin and a surfactant to be used as a final bath of the photographic
color light-sensitive material. Various chelating agents or antifungal agents can
be added in the stabilizing bath.
[0114] An overflow solution produced upon replenishment of the washing and/or stablizing
solution can be reused in another step such as a desilvering step.
[0115] The silver halide color light-sensitive material of the present invention may contain
a color developing agent in order to simplify processing and increase a processing
speed. For this purpose, various types of precursors of a color developing agent can
be preferably used. Examples of the precursor are a compound of indoaniline-series
described in U.S. Patent 3,342,597, a Shciff base type compound described in U.S.
Patent 3,342,599 and RD. Nos. 14,850 and 15,159, an aldol compound described in RD.
No. 13,924, a metal complex salt described in U.S. Patent 3,719,492, and a compound
of urethane series described in JP-A-53-135,628.
[0116] The silver halide color light-sensitive material present invention may contain various
1-phenyl-3-pyrazolidones in order to accelerate color development, if necessary. Typical
examples of the compound are described in JP-A-56-64339, JP-A-57-144547, and JP-A-58-115438.
[0117] Each processing solution in the present invention is used at a temperature of 10°C
to 50°C. Although a normal processing temperature is 33°C to 38°C, processing may
be accelerated at a high temperature to shorten a processing time, or image quality
or stability of a processing solution may be improved at a lower temperature. In order
to save silver for the light-sensitive material, processing using cobalt intensification
or hydrogen peroxide intensification described in West German Patent No. 2,226,770
or U.S. Patent 3,674,499 may be performed.
[0118] The silver halide light-sensitive material of the present invention can also be applied
to heat development light-sensitive materials described in, e.g., U.S. Patent 4,500,626,
JP-A-60-133449, JP-A-59-218443, JP-A-61-238056, and EP 210,660A2.
[0119] When the light-sensitive material of the present invention is to be used in the form
of a roll, it is preferably housed in a cartridge. A most general example of the cartridge
is a currently used 135-format patrone. In addition, cartridges proposed in the following
patents can be used.
[0120] The patents are unexamined Published Japanese Utility Model Application Nos. 58-67329,
and 58-195236, JP-A-58-181035, JP-A-58-182634, JP-A-1-231045, JP-A-2-170156, JP-A-2-124564,
Japanese Patent Application Nos. 1-21862, 1-25362, 1-30246, 1-20222, 1-21863, 1-37181,
1-33108, 1-85198, 1-172594, and 1-172595, and U.S. Patents 4,846,418, 4,848,693, 4,221,479,
and 4,832,275.
[0121] Although the present invention will be described in more detail below by way of its
examples, the present invention is not limited to these examples.
Example 1
[0122] In Example 1, emulsions using tabular grains will be described.
Preparation of emulsion A
[0123] 21 g of inert gelatin and 7.0 g of potassium bromide were dissolved in 1.4 ℓ of distilled
water, and 70 cc of an aqueous solution containing 12.0 g of silver nitrate and 70
cc of an aqueous solution containing 8.0 g of potassium bromide and 0.5 g of potassium
iodide were simultaneously added by the double-jet method at predetermined flow rates
over 45 seconds to the above solution under stirring at 50°C (1st addition). 220 g
of a 10% aqueous solution of inert gelatin were added to the resultant solution, and
the solution was heated up to 65°C. 30 minutes after the temperature reached 65°C,
434 cc of an aqueous solution containing 130 g of silver nitrate were added to the
resultant solution over 35 minutes, while 700 cc of an aqueous solution containing
200 g of potassium bromide and 4.3 g of potassium iodide were added to maintain a
pBr at 2.3 (2nd addition).
[0124] After the 2nd addition, 45 cc of a 1 N solution of potassium thiocyanate were added
to the resultant solution. Two minutes after the addition, 317 cc of an aqueous solution
containing 95 g of silver nitrate were added to the solution, while 700 cc of an aqueous
solution containing 200 g of potassium bromide and 4.3 g of potassium iodide were
added to maintain the pBr at 2.3 (3rd addition).
[0125] 10 minutes after the addition, a desalting step was started. After the desalting
step was finished, the resultant solution was redispersed and optimally gold·sulfur-sensitized
at 60°C. After the chemical sensitization was finished, a dye A (to be described at
the end of this Example) was added at a temperature of 40°C in an amount of 6 × 10⁻⁴
mol per mol of silver nitrate.
Preparation of emulsion B
[0126] An emulsion B was prepared following the same procedures as for the emulsion A except
that a thiosulfonic acid compound (1-5) listed in Table A below was added in an amount
of 1 × 10⁻⁴ mol per mol of silver nitrate at the time when 10 minutes had passed since
the beginning of the 2nd addition in the emulsion A.
Preparation of emulsion C
[0127] An emulsion C was prepared following the same procedures as for the emulsion B except
that the thiosulfonic acid compound was added at the time when 22 minutes had passed
since the beginning of the 2nd addition in the emulsion B.
Preparation of emulsion D
[0128] An emulsion D was prepared following the same procedures as for the emulsion B except
that the thiosulfonic acid compound was added at the same time that the 3rd addition
was started in the emulsion B.
Preparation of emulsion E
[0129] An emulsion E was prepared following the same procedures as for the emulsion B except
that the thiosulfonic acid compound was added at the time when 15 minutes had passed
since the beginning of the 3rd addition in the emulsion B.
Preparation of emulsion F
[0130] An emulsion F was prepared following the same procedures as for the emulsion B except
that the thiosulfonic acid compound was added at the time when 10 seconds had passed
since the completion of the 3rd addition in the emulsion B.
Preparation of emulsion G
[0131] An emulsion G was prepared following the same procedures as for the emulsion B except
that the same number of mols of hydrogen peroxide was added in place of the thiosulfonic
acid compound in the emulsion B.
Preparation of emulsion H
[0132] An emulsion H was prepared following the same procedures as for the emulsion E except
that the same number of mols of hydrogen peroxide was added in place of the thiosulfonic
acid compound in the emulsion E.
Preparation of emulsion B-2
[0133] An emulsion B-2 was prepared by performing the following chemical sensitization after
the desalting step was finished in the emulsion B. That is, the dye A was added in
an amount of 6 × 10⁻⁴ mol per mol of silver nitrate at 60°C, and gold·sulfur sensitization
was optimally performed at 60°C, 20 minutes after the addition.
Preparation of emulsion F-2
[0134] An emulsion F-2 was prepared by performing the following chemical sensitization after
the desalting step was finished in the emulsion F. That is, the dye A was added in
an amount of 6 × 10⁻⁴ mol per mol of silver nitrate at 60°C, and gold·sulfur sensitization
was optimally performed at 60°C, 20 minutes after the addition.
[0135] Each of the above emulsions A to H, B-2, and F-2 comprised tabular grains having
an average circle-equivalent diameter of 0.6 µm, an average aspect ratio of 5.5, and
a variation coefficient of a circle-equivalent diameter of 19%.
[0136] Samples 101 to 108 coated with the emulsions A to H and samples 109 and 110 coated
with the emulsions B-2 and F-2 were formed as follows.
Formation of sample 101
[0137] The following emulsion and protective layers were formed on a triacetylcellulose
film support having an undercoating layer.

Formation of samples 102 to 110 Instead of the emulsion A used in the sample 101, samples 102 to 108 were formed
by using the emulsions B to H, respectively, and samples 109 and 110 were formed by
using the emulsions B-2 and F-2, respectively.
[0138] The samples 101 to 110 were subjected to sensitometry exposure (1/100") and the following
color development.
[0139] The developed samples were subjected by density measurement by using a green filter.
The obtained results of photographic properties are summarized in Table 1.
[0140] In addition, two sets of the samples, each set consisting of samples 101 to 110,
were prepared and subjected to sensitometry exposure (1/100"). One set of the samples
was left to stand at a temperature of 30°C and a relative humidity of 60% for one
month, and the other set was left to stand at a temperature of 40°C and a relative
humidity of 60% for two weeks. Thereafter, these samples were subjected to the following
color development and density measurement by using a green filter. The results are
summarized in Table 1.
[0141] Of the above results of photographic properties, the sensitivity is represented by
relative sensitivity assuming that the sensitivity (fog + optical density of 0.2)
of the sample 101 is 100. (Color Development Process Method)
[0142] The color development process was performed at 38°C in accordance with the following
process steps.

[0144] As is apparent from Table 1, each emulsion of the present invention had a high fog/sensitivity
ratio (i.e., produced low fog) by an effect of the oxidizing agent for silver and
did not increase the sensitivity but was stable during storage in which heat and humidity
were applied after exposure.

Example 2
[0145] Silver iodobromide seed crystals A having a homogeneous halogen distribution structure
and containing 6 mol% of silver iodide were prepared. The seed crystals A were octahedral
regular grains having a sphere-equivalent diameter of 0.50 µm and had a variation
coefficient indicating a size distribution of about 14%.
[0146] Silver iodiobromide containing 6 mol% of silver iodide was grown starting from the
seed crystals A to obtain grains having a sphere-equivalent diameter of 1.4 µm, by
means of controlled double jet method of flow rate-accelerated type, thereby preparing
emulsion I.
[0147] This emulsion I was redispersed at 40°C after a normal desalting step.
[0148] Subsequently, the emulsion I was optimally gold·sulfur-sensitized. After this chemical
sensitization, the dye A described in Example 1 was added to the emulsion I at 40°C
in an amount of 2 x 10⁻⁴ mol per mol of silver nitrate.
[0149] Emulsions J to P were formed following the same procedures as for the emulsion I
except that the oxidizing agent for silver was added at timings as shown in the following
Table 2 during grain formation.
* Represented by a percentage of water-soluble silver salt (silver nitrate) for use
in formation of grains including seed crystals added when an oxidizing agent for silver
is added.
[0150] In addition, an emulsion J-2 was prepared by changing the chemical sensitization
of the emulsion J as follows. That is, after the redispersion, the dye A was added
at 60°C in an amount of 2 × 10⁻⁴ mol per mol of silver nitrate, and gold·sulfur sensitization
was optimally performed at 60°C from the time when 20 minutes had passed since the
addition.
[0151] An emulsion N-2 was prepared by changing the chemical sensitization of the emulsion
N as described above.
[0152] Samples 201 to 208 coated with the emulsions I to p, respectively, and samples 209
and 210 coated with the emulsions J-2 and N-2, respectively, were formed as follows.
Formation of sample 201
[0153] The following emulsion and protective layers were formed on a triacetylcellulose
film support having an undercoating layer.

Formation of samples 202 to 210
[0154] Instead of the emulsion used in the sample 201, samples 202 to 208 were formed by
using the emulsions J to P, respectively, and samples 209 and 210 were formed by using
the emulsions J-2 and N-2, respectively.
[0155] The samples 201 to 210 were subjected to sensitometry exposure (1/100") and color
development following the same procedures as in Example 1.
[0156] The developed samples were subjected to density measurement by using a green filter.
The obtained results of photographic properties are summarized in Table 3.
[0157] In addition, another set of the samples 201 to 210 was subjected to sensitometry
exposure (1/100") and left to stand at a temperature of 40°C and a relative humidity
of 60% for one month. Thereafter, these samples were subjected to color development
following the same procedures as in Example 1, and the developed samples were subjected
to density measurement by using a green filter. The results are summarized in Table
3.
[0158] Of the results of photographic properties summarized in Table 3, the sensitivity
is represented by relative sensitivity assuming that the sensitivity (fog + optical
density of 0.2) of the sample 101 is 100.
[0159] As is apparent from Table 3, each emulsion comprising octahedral grains of the present
invention had a high fog/sensitivity ratio (i.e., produced low fog) by an effect of
the oxidizing agent for silver and did not increase the sensitivity but was stable
during storage in which heat and humidity were applied after exposure.

Example 3
[0160] Silver iodide seed crystals B having a homogeneous halogen distribution structure
and containing 6 mol% of silver iodide were prepared. The seed crystals B were parallel
double twinned crystal tabular grains having a sphere-equivalent diameter of 0.60
µm and had a variation coefficient of a sphere-equivalent diameter of 23% and an average
aspect ratio of all grains of 9.5.
[0161] Silver iodobromide containing 23 mol% of silver iodide was grown starting from the
seed crystals B to obtain grains having a sphere-equivalent diameter of 1.15 µm, by
means of controlled double jet method of flow rate-accelerated type, thereby preparing
emulsion Q. In the emulsion Q, a variation coefficient of a sphere-equivalent diameter
was 18%, and an average aspect ratio of all grains was 7.0.
[0162] This emulsion Q was subjected to a normal desalting step and then redispersed at
40°C.
[0163] Subsequently, the emulsion Q was optimally gold°sulfur-sensitized at 60°C. After
this chemical sensitization, spectral sensitizing dyes V, VI, and VII listed in Table
B below were mixed in amounts of 3.5 × 10⁻⁵ mol, 8 × 10⁻⁵ mol, and 3 × 10⁻⁴ mol, respectively,
per mol of silver nitrate and added at 40°C.
[0164] Emulsions R to X were prepared following the same procedures as for the emulsion
Q except that the oxidizing agent for silver was added at addition timings as shown
in Table 4 during grain formation.
* Represented by a percentage of water-soluble silver salt for use in formation of
grains including seed crystals added when an oxidizing agent for silver is added.
[0165] In addition, an emulsion R-2 was prepared by changing the chemical sensitization
of the emulsion R as follows. That is, after the redispersion, the spectral sensitizing
dyes V, VI, and VII were mixed in amounts of 3.5 × 10⁻⁵ mol, 8 × 10⁻⁵ mol, and 3 ×
10⁻⁴ mol, respectively, per mol of silver nitrate and added at 60°C. At the time when
20 minutes had passed since the addition, gold·sulfur sensitization was optimally
performed at 60°C.
[0166] Emulsions U-2 and V-2 were prepared by changing the chemical sensitization of the
emulsions U and V, respectively, as described above.
[0167] Samples 301 to 308 coated with the emulsions Q to X, respectively, and samples 309
to 311 coated with the emulsions R-2, U-2, and V-2, respectively, were formed to have
the same compositions as those of the coated samples described in Example 2.
[0168] The samples 301 to 311 were subjected to sensitometry exposure (1/100") and color
development following the same procedures as in Example 1.
[0169] The developed samples were subjected to density measurement by using a green filter.
The obtained results of photographic properties are summarized in Table 5.
[0170] In addition, another set of the samples 301 to 308 was subjected to sensitometry
exposure (1/100") and left to stand at a temperature of 40°C and a relative humidity
of 60% for one month. Thereafter, these samples were subjected to color development
following the same procedures as in Example 1, and the developed samples were subjected
to density measurement by using a green filter. The results are summarized in Table
5.
[0171] Of the results of photographic properties summalized in Table 5, the sensitivity
is represented by a relative sensitivity assuming that the sensitivity (fog + optical
density of 0.2) of the sample 101 is 100.
[0172] As is apparent from Table 5, each emulsion of the present invention produced low
fog by an effect of the oxidizing agent for silver and did not increase the sensitivity
but was stable during storage in which heat and humidity were applied after exposure.

Example 4
[0173] The following dye groups 1 to 3 were added at 40°C to the emulsions Q to X prepared
in Example 3 which were chemically sensitized but not added with the spectral sensitizing
dyes, thereby preparing red-, green-, and blue-sensitive emulsions.
[0174] Sensitizing dyes II to VII in the following dye groups 1 to 3 are listed in Table
B below.

[0175] The emulsions R-2, U-2, and V-2 prepared in Example 3 were obtained by adding the
dye group 2 to the emulsions R, U, and V, respectively, prior to gold·sulfur sensitization.
[0176] The dyes to be added following the same procedures as in the chemical sensitization
for the emulsions R-2, U-2, and V-2 were changed to those of the dye group 1, thereby
preparing emulsions R-3, U-3, and V-3, respectively.
[0177] In addition, the dyes to be added following the same procedures as in the chemical
sensitization for the emulsions R-2, U-2, and V-2 were changed to that of the dye
group 3, thereby preparing emulsions R-4, U-4, and V-4, respectively.
[0178] Using these emulsions, layers having the following compositions were coated on an
undercoated cellulose triacetate film support, thereby manufacturing a multilayered
color light-sensitive material.
(Compositions of light-sensitive layers)
[0179] The coating amounts of a silver halide and colloidal silver are represented in units
of g/m² of silver, those of a coupler, an additive, and gelatin are represented in
units of g/m², and that of a sensitizing dye is represented by the number of mols
per mol of the silver halide in the same layer.
[0180] The structural formulas of the compounds identified below by using symbols are listed
in Table C below.
Layer 1: Antihalation layer
[0181] Black colloidal silver

Layer 2: Interlayer
[0182] Fine silver iodobromide grain (AgI = 1.0 mol%, sphere-equivalent diameter = 0.07
µm)

Layer 3: 1st red-sensitive emulsion layer
[0183] Silver iodobromide emulsion (AgI = 5.0 mol%, surface high AgI type, sphere-equivalent
diameter = 0.9 µm, variation coefficient of sphere-equivalent diameter = 21%, tabular
grain, diameter/thickness ratio = 7.5)

[0184] Silver iodobromide emulsion (AgI = 4.0 mol%, internally high AgI type, sphere-equivalent
diameter = 0.4 µm, variation coefficient of sphere-equivalent diameter = 18%, tetradecahedral
grain)

Layer 4: 2nd red-sensitive emulsion layer
[0185] Silver iodobromide emulsion (AgI = 8.5 mol%, internally high AgI type, sphere-equivalent
diameter = 1.0 µm, variation coefficient of sphere-equivalent diameter = 25%, tabular
grain, diameter/thickness ratio = 3.0)

Layer 5: 3rd red-sensitive emulsion layer
[0186] Silver iodobromide emulsion I

Layer 6: Interlayer
[0187]

Layer 7: 1st green-sensitive emulsion layer
[0188] Silver iodobromide emulsion (AgI = 5.0 mol%, surface high AgI type, sphere-equivalent
diameter = 0.9 µm, variation coefficient of sphere-equivalent diameter = 21%, tabular
grain, diameter/thickness ratio = 7.0)

[0189] Silver iodobromide emulsion (AgI = 4.0 mol%, internally high AgI type, sphere-equivalent
diameter = 0.4 µm, tetradecahedral grain, variation coefficient of sphere-equivalent
diameter = 18%)

Layer 8: 2nd green-sensitive emulsion layer
[0190] Silver iodobromide emulsion (AgI = 8.5 mol%, internally high iodide type, sphere-equivalent
diameter = 1.0 µm, variation coefficient of sphere-equivalent diameter = 25%, tabular
grain, diameter/thickness ratio = 3.0)

Layer 9: Interlayer
[0191]

Layer 10: 3rd green-sensitive emulsion layer
[0192] Silver iodobromide emulsion II

Layer 11: Yellow filter layer
[0193]

Layer 12: Interlayer
[0194]

Layer 13: 1st blue-sensitive emulsion layer
[0195] Silver iodobromide emulsion (AgI = 2 mol%, homogeneous iodide type, sphere-equivalent
diameter = 0.55 µm, variation coefficient of sphere-equivalent diameter = 25%, tabular
grain, diameter/thickness ratio = 7.0)

Layer 14: 2nd blue-sensitive emulsion layer
[0196] Silver iodobromide emulsion (AgI = 19.0 mol%, internally high AgI type, sphere-equivalent
diameter of 1.0 µm variation coefficient of sphere-equivalent diameter = 16%, octahedral
grain)

Layer 15: Interlayer
[0197] Fine silver iodobromide grain (AgI = 2 mol%, homogeneous iodide type, sphere-equivalent
diameter = 0.13 µm)

Layer 16: 3rd blue-sensitive emulsion layer
[0198] Silver iodobromide emulsion III

Layer 17: 1st protective layer
[0199]

Layer 18: 2nd protective layer
[0200] Fine silver chloride grain (sphere-equivalent diameter = 0.07 µm)

[0201] In addition to the above additives, B-1 (0.20 g/m² in total), 1,2-benzisothiazoline-3-one
(about 200 ppm on the average with respect to gelatin), n-butyl, p-hydroxybenzoate
(about 1,000 ppm on the average with respect to gelatin), and 2-phenoxyethanol (about
10,000 ppm on the average with respect to gelatin) were added to the layers.
[0202] The silver iodobromide emulsions I, II, and III of the layers 5, 10 and 16 were prepared
by adding any one of the dye groups 1 to 3 into any one of the emulsions Q to X prepared
in Example 3, which emulsions Q to X were gold·sulfur sensitized but not mixed with
spectral sensitizing dye. Samples 401 to 408 of multilayered color photographic light-sensitive
materials listed in the following Table 6 were formed, by incorporating the emulsions
I, II and III into the layers 5, 10 and 16 respectively. The table 6 shows combinations
of the dye groups 1 to 3 and the emulsions Q to X, which are employed respectively
in the emulsion I (layer 5), emulsion II (layer 10) and the emulsion III (layer 16)
of the samples 401 to 408.

[0203] In addition, multilayered color photographic light-sensitive materials 409 to 411
were formed by incorporating the emulsions R-2, R-3, and R-4, U-2, U-3, and U-4, and
V-2, V-3, and V-4, respectively, added with the dye groups 1 to 3 prior to gold·sulfur
sensitization. Combinations of the dye groups 1 to 3 and the emulsions Q to X in that
layers 5, 10 and 16 of samples 409 to 411 are summarized in the following Table 7.

[0204] These samples 401 to 411 were subjected to sensitometry exposure (1/100) and the
following color development.
[0205] The developed samples were subjected to density measurement by using red, green,
and blue filters.
[0206] In addition, another set of the samples 401 to 411 was subjected to sensitometry
exposure (1/100") and left to stand at a temperature of 40°C and a relative humidity
of 60% for one month. Thereafter, these samples were also subjected to the following
color development.
[0207] The developed samples were subjected to density measurement by using red, green,
and blue filters. Processing method
[0208] The color development process was performed at 38°C in accordance with the following
process steps.

[0209] The processing solution compositions used in the respective steps were as follows.

[0210] The obtained results corresponded to the results obtained in Example 3, i.e., a light-sensitive
material which produced low fog and did not increase the sensitivity but was stable
during storage in which heat and humidity were applied after exposure was obtained
in the multilayered color light-sensitive material using the emulsions T, U, V, and
X of the present invention. In particular, the results obtained by the emulsion in
which the spectral sensitizing dyes were present prior to gold·sulfur sensitization
upon chemical sensitization corresponded to the results obtained in Example 3, and
in that case particularly preferable results were obtained.
Example 5
[0211] The samples 401 to 408 of the present invention and the comparative examples were
used to conduct the experiment following entirely the same procedures as in Example
4 except for the processing method to be presented below. Color development was performed
by using an automatic developing machine in accordance with the following method.

[0212] The processing solution compositions will be described below.

(Washing solution)
[0213] Tap water was supplied to a mixed-bed column filled with an H type strongly acidic
cation exchange resin (Amberlite IR-120B: available from Rohm & House Co.) and an
OH type strongly basic anion exchange resin (Amberlite IR-400) to set the concentrations
of calcium and magnesium to be 3 mg/ℓ or less. Subsequently, 20 mg/ℓ of dichlorinated
sodium isocyanurate and 1.5 g/ℓ of sodium sulfate were added. The pH of the solution
fell within the range of 6.5 to 7.5.

[0214] By the effect of the present invention, preferable results were obtained in also
the above processing as in Example 4.
Example 6
[0215] The samples 401 to 408 of the present invention and the comparative examples were
subjected to the experiments following the same procedures as in Example 4 and processed
by using an automatic developing machine in accordance with the following method.

[0216] The processing solution compositions will be described below.

(Washing solution)
[0217] Tap water was supplied to a mixed-bed column filled with an H type strongly acidic
cation exchange resin (Amberlite IR-120B: available from Rohm & House Co.) and an
OH type strongly basic anion exchange resin (Amberlite IR-400) to set the concentrations
of calcium and magnesium to be 3 mg/ℓ or less. Subsequently, 20 mg/ℓ of dichlorinated
sodium iocyamurate and 1.5 g/ℓ of sodium sulfate were added. The pH of the solution
fell within the range of 6.5 to 7.5.
