Silver halide emulsions comprising grains with (100) surfaces having conjugated (110) surface crystals thereon and method for the preparation thereof

The present invention provides a novel silver chlorobromide emulsion which is substantially free from silver iodide and which contains silver halide crystal particles comprising cubic, rectangular parallelepiped or tetradecanedral first silver halide crystals having six (100) surfaces which may further comprise additional (110) surfaces, at least one of the six (100) surfaces being conjugated with second silver halide crystals having a halogen composition different from that of the (100) surfaces of the first silver halide crystals and mainly comprising (110) surfaces, the second silver halide crystals being conjugated over the one or more surfaces of the first silver halide crystals in the form of one or more projections. The present invention further provides a method for the preparation of this conjugated silver chlorobromide particle-containing emulsion which is substantially free from silver iodide which comprises forming cubic, rectangular parallelepiped or tetradecahedral first silver halide crystals having six (100) surfaces which may further comprise additional (110) surfaces and then adding thereto an aqueous halide solution and an aqueous silver salt solution in the presence of a crystal habit regulator wherein at least one of the six (100) surfaces of the first silver halide crystals is conjugated with second silver halide crystals mainly comprising (110) crystal surfaces and having a halogen composition different from that of the (100) surfaces of the first silver halide crystals, the second silver halide crystals being conjugated over one or more surfaces of the first silver halide crystals in the form of one or more projections.

FIELD OF THE INVENTION 
The present invention relates to silver halide emulsions and a method for 
the preparation thereof, more precisely, to novel silver halide 
photographic emulsions which contain silver halide crystal particles 
having specific shapes and a method for the preparation thereof. 
BACKGROUND OF THE INVENTION 
Known silver halides include silver iodide, silver bromide, silver 
chloride, silver iodochloride, silver chlorobromide, silver 
iodochlorobromide, etc. A variety of shapes of the silver halide crystals 
particles (grains) are also known. So-called regularly shaped crystal 
forms include cubic, octahedral, tetradecahedral, rhombic dodecahedral or 
the like. Spherical, tabular, amorphous or the like are examples of 
irregularly shaped crystalline particles. Further, multiphase structural 
crystal particles having layered structures or conjugate (joined) 
structures in the particles are also in common use. The halogen 
composition, shape and structure of these crystal particles are known to 
influence the characteristics and properties of the silver halide 
particles, as noted, for example, by T. H. James in The Theory of the 
Photographic Process (4th Ed., Macmillan Co., Ltd., New York) 
(particularly, the description in the first and third chapters of the 
properties of silver halides, and the description in the third chapter of 
the shapes of silver halides, etc.). 
Silver halide emulsions may exhibit various characteristics, depending upon 
the halogen composition of the particles used therein. For example, a 
silver chloride emulsion has a low sensitivity but has a high solubility 
and, therefore, is suitable for rapid processing as such an emulsion is 
capable of undergoing high speed development and fixation. However, fog 
often occurs in silver chloride emulsions. On the other hand, when a 
silver bromide emulsion is used, development processing is somewhat 
slower, but fog hardly occurs, and, further, the light sensitivity of this 
type of emulsion is high. Silver iodide emulsions are extremely difficult 
to develop, and, therefore, are rarely used alone in photographic 
materials. However, mixed silver halide crystals comprising silver iodide 
and silver bromide exhibit an excellent light sensitivity and, therefore, 
silver halide emulsions containing such a mixture of crystal particles are 
extremely important in photographic light-sensitive materials used as 
camera films. 
A variety of techniques have heretofore been known, utilizing the 
characteristics of various kinds of these silver halides, and there is a 
substantial amount of literature publications concerning core-shell 
layered structures of silver halide particles. Typically, the entire 
surface of the core is coated with one or more shells having a silver 
halide composition which is different from that of the core. Japanese 
Patent Publication No. 18939/81 teaches that a silver halide emulsion 
comprising silver bromide (core) and silver chloride (shell) particles 
combines the high light sensitivity of the silver bromide and the rapid 
developability of the silver chloride, but these properties of the two 
types of silver halide become somewhat suppressed in a mixed crystal type 
silver chlorobromide emulsion. In addition, German Patent Application 
(OLS) No. 3,229,999 illustrates that core-shell silver halide particles 
formed from a silver halide layer having at least 25 mol% silver chloride 
content and a silver halide layer having a smaller silver chloride content 
(mol%) than the former, the latter being adjacent to the former, are 
characterized in that the amount of fog formation is small and the 
pressure property is good. 
U.S. Pat. No. 4,094,684 illustrates an emulsion containing silver halide 
particles formed by epitaxial growth of silver chloride over polyhedral 
silver iodide crystal particles. Further, U.S. Pat. No. 4,463,087 
illustrates an emulsion containing silver salt particles formed by 
epitaxial growth of (111) surface-surrounded and silver iodide-containing 
host silver halide particles and a method for the preparation thereof; and 
U.S. Pat. No. 4,471,050 illustrates an emulsion comprising silver halide 
host particles having a face-centered cubic type crystalline structure and 
non-isomorphous silver salts as projecting only from the edges or corners 
of the host particles. Furthermore, Japanese Patent Publication No. 
24772/83 (corresponding to U.S. Pat. No. 4,496,652) describes cubic silver 
halide crystals where the corner parts have a different halogen 
composition from that of the center body part of the crystal, illustrating 
that it is possible for such crystals to have a selectivity to the 
introduction of impurities thereinto and to control the crystal defects 
thereof. 
The silver halide particles having this type of structure (as described in 
Japanese Patent Publication No. 24772/83) are also described by C. Hasse, 
H. Frieser and E. Klein in Die Grundlagen der Photographischen Prozesse 
mit Silberhalogeniden, Vol. 2 (Akademische Verlagsgesellschaft, Frankfurt 
an Main, 1968), in which it is stated that the deposition of silver 
chloride on octahedral silver bromide crystals resulted in the formation 
of many (100) surface-containing small silver chloride particles on the 
eight (111) surfaces of the octahedral crystals and that these small 
particles were attached to the octahedral crystals after the successive 
deposition of the silver chloride over the crystals to finally form 
crystalline surfaces of cubic crystals. 
According to C.R. Berry and D.C. Skillman in Journal of Applied Physics, 
35, 7, 2165 (1964), the deposition of silver chloride on octahedral silver 
bromide particles also causes the epitaxial formation of silver 
chlorobromide mixed crystals over the (111) surface of the particles, 
while the deposition of silver chloride on cubic silver bromide particles 
causes epitaxial growth or projections only at the corners or edges of the 
cubic crystals. 
In the same manner, C.R. Berry mentions in Photographic Science and 
Engineering, 19, 3, 29 (1975) that the deposition of silver chloride on 
dodecahedral particles having both (111) and (100) surfaces preferentially 
occurs on the (111) surface most often, whereas deposition on the (110) 
surface occurs next most often, while deposition on the (100) surface 
hardly occurs. Further, this publication describes that the deposition of 
silver chloride occurs more readily on the six tetrasymmetric corners than 
on the other eight tri-symmetric corners among the two kinds of corners 
present on dodecahedral particles. 
In all of these above-described known techniques and publications 
concerning silver chlorobromide particles, epitaxial growth selectively 
occurs on the edges or corners of each crystal, or growth occurs on the 
(111) surface and (110) surface of the crystal. In the aforesaid 
core-shell type particles, uniform growth causes the covering (the shell) 
of all the surfaces of the core particles. Under these circumstances, 
epitaxial conjugate (joined) particles having a silver halide part 
selectively conjugated and formed on the (100) surface of the core silver 
halide particles are not known to exist. 
On the other hand, with respect to (110) surface-surrounded rhombic 
dodecahedral particles, German Pat. No. 2,222,297 (corresponding to U.S. 
Pat. No. 3,817,756) describes silver chloride and silver chlorobromide 
particles and Japanese Patent Application (OPI) No. 222842/85 describes 
silver bromide and silver iodobromide particles (the term "OPI" as used 
herein refers to a "published unexamined Japanese patent application"). 
However, the particles obtained by these known methods are rhombic 
dodecahedral particles themselves having twelve (110) surfaces or 
polyhedral particles which further have six (100) surfaces or eight (111) 
surfaces introduced into the dodecahedral particles. Such particles are 
also described in the above-mentioned Photographic Science and 
Engineering, 19, 3, 29 (1975). However, the shapes of the particles 
described therein are not defined with particularity, and further, such 
particles are difficult to obtain by the method described therein. 
Japanese Patent Application (OPI) No. 83531/86 illustrates silver bromide 
and silver iodobromide particles which have a groove in the center of the 
(110) surface. These particles, however, are not conjugate (joined) type 
particles. 
In any event, these known particles described above are rhombic 
dodecahedral shaped or similarly shaped crystalline particles, and, 
therefore, the specifically shaped conjugate type particles composed 
mainly of (110) crystalline surfaces of the present invention are novel. 
Development of silver halide particles having a higher sensitivity with 
less fog formation is a keenly desired goal in the photographic technical 
field. However, silver halide particles which satisfactorily achieve this 
goal had not yet been discovered until the present invention described in 
detail hereinbelow. 
SUMMARY OF THE INVENTION 
Accordingly, one object of the present invention is to provide silver 
chlorobromide particles having excellent photographic characteristics and 
novel crystalline shapes. 
A further object of the present invention is to provide a method for the 
preparation of such silver chlorobromide emulsions. 
Still another object of the present invention is to provide silver 
chlorobromide photographic materials which contain silver chlorobromide 
particles having excellent developability characteristics and which 
exhibit higher sensitivity with less fog formation. 
The present invention provides novel silver chlorobromide emulsions which 
are substantially free from silver iodide and which are characterized by 
containing silver halide crystal particles comprising cubic, rectangular 
parallelpiped or tetradecahedral silver halide crystals having six (100) 
surfaces which may further comprise additional (110) surfaces (first 
silver halide crystals), wherein at least one of the six (100) surfaces of 
the first silver halide crystals is conjugated (joined) with silver halide 
crystals (second silver halide crystals) which have a halogen composition 
different from that of the (100) surfaces of the first silver halide 
crystals and which mainly comprise (110) crystal surfaces, wherein the 
second silver halide crystals are conjugated over one or more surfaces of 
the first silver halide crystals in the form of one or more projections. 
The present invention further provides a method for the preparation of 
these conjugate (joined) silver chlorobromide emulsions which are 
substantially free from silver iodide which comprises forming cubic, 
rectangular parallelpiped or tetradecahedral silver halide crystals which 
may further comprise additional (110) surfaces (first silver halide 
crystals) and then adding thereto an aqueous halide solution and an 
aqueous silver salt solution in the presence of a crystal habit regulator 
(growth modifier) wherein at least one of the six (100) surfaces of the 
first silver halide crystals is conjugated with silver halide crystals 
(second silver halide crystals) mainly comprising (110) surfaces and 
having a halogen composition which is different from that of the (100) 
surfaces of the first silver halide crystals, wherein the second silver 
halide crystals are conjugated over one or more surfaces of the silver 
halide crystals in the form of one or more projections. 
The surfaces of the silver halide crystal particles of the present 
invention, as well as other crystal particles described above, are 
described with reference to standard Miller index notations, i.e., (100) 
cubic surfaces, (110) dodecahedral surfaces, and (111) octahedral surfaces 
.

DETAILED DESCRIPTION OF THE INVENTION 
The conjugate (joined) type silver halide particles of the present 
invention and the method for the preparation thereof are explained in 
detail below. 
The most typical particles within the scope of the present invention 
comprise cubic, rectangular parallelpiped or tetradecahedral silver halide 
crystals having six (100) surfaces which may further comprise an 
additional twelve (110) surfaces (first silver halide crystals), the six 
(100) surfaces of which are conjugated thereover with the second silver 
halide crystals described above which have a halogen composition different 
from that of the first silver halide crystals (the host particles), mostly 
in the form of projections. The resulting conjugate silver halide 
particles have a rhombic dodecahedral crystal structure, the outer surface 
of which is surrounded with (110) surfaces containing the projections. The 
conjugated second crystals are not limited to conventional (110) 
surface-containing rhombic dodecahedral crystals, but the corners thereof 
may be rounded or the crystals may additionally contain (111) surfaces or 
(100) surfaces. In particular, the (100) surface is most likely to be 
present on the conjugate crystal surface in the boundary between the host 
crystal and the conjugate crystal. In any event, the conjugated crystals 
of the present invention will perform their intended function as long as 
the surface of the conjugate or second crystal, which is not adjacent to 
the host crystal, is surrounded mainly with (110) surfaces. 
Further, the conjugated second crystals which are not formed and grown on 
the same (100) surface of the host crystal are adjacent and bound to each 
other, and may also cover portions of edges and corners of the first 
silver halide crystals (referred to as "host crystals" hereinafter). 
Alternatively, the second or conjugate crystals do not necessarily have to 
be formed on all six of the (100) surfaces of the host crystals; for 
example, the second crystals may be conjugated on four or five of the 
(100) surfaces. Conjugated particles where the second crystals are only 
formed on one of the (100) surfaces are also included in the scope of the 
present invention. 
More specifically, the second silver halide crystals which have a different 
halogen composition from that of the host crystals are to be conjugated 
and grown on at least one (100) surface of the host crystals, preferably 
two or more (100) surfaces thereof, and most preferably all six (100) 
surfaces thereof, in order to satisfy the objects of the present 
invention. The second silver halide crystals thus conjugated may cover all 
the respective (100) surfaces of the host crystals, or alternatively, may 
cover only parts thereof. Further, the second crystals which are 
conjugated on different crystal surfaces may be attached or bound to each 
other, as mentioned above. 
The host crystals are most preferably silver halides of cubic crystals, 
rectangular parallelpiped crystals, tetradecahedral crystals which may 
further comprise an additional twelve (110) surfaces. The edges and 
corners of these host crystals may be rounded, and the overall shape of 
these cubic crystals, rectangular parallelpiped crystals or 
tetradecahedral crystals need not necessarily be definite, and those host 
crystals containing additional (110) surfaces need not necessarily be 
definite, as long as the host crystals have (100) surfaces onto which the 
second silver halide crystals can be conjugated as described above. All of 
these types of host silver halide crystals can be used in the formation of 
the conjugated particles of the present invention. 
The ratio of the silver halide constituting the host crystal particle to 
the silver halide constituting the second crystal particle which is to be 
conjugated and grown on the host particle is not necessarily limited. 
However, if the ratio of the latter to the former is too small, a definite 
conjugate structure can not be observed or the (110) surfaces are 
difficult to discern; on the other hand, if the ratio is too large, all of 
the second silver halide crystals cannot be completely conjugated on the 
host crystals so as to result in the formation of differnt, new crystal 
particles, or the second crystals will entirely cover all the surfaces of 
the host crystals and will be linked together thereon, resulting in 
two-layered structural crystal particles wherein the conjugated structure 
of the particles of the present invention cannot be discerned. 
Accordingly, the ratio of the silver halide constituting the host crystals 
and the second crystals, respectively, is preferably about 0.1 mol/mol to 
about 6 mols/mol. 
In order to obtain uniform formation and growth of the conjugate crystals 
over the host crystals, uniformity of the shape of the host crystals as 
well as high monodispersivity of the particle size distribution of the 
host particles are desired. If, on the other hand, the host crystals have 
a broad particle size distribution, silver halide emulsions can be 
obtained containing various conjugated particles having differing silver 
amount ratios between the conjugate crystals and host crystals, by 
appropriately regulating the addition speed of the water-soluble silver 
salt and the water-soluble halide during the formation of the second 
silver halide crystals to be conjugated over the host crystals. 
A variation coefficient (which is determined as the value obtained by 
dividing the standard deviation of the particle size distribution (s) by 
the mean particle size (.gamma.): (s/.gamma.) of the monodispersed 
emulsion according to the present invention is not more than 0.20, 
preferably not more than 0.15. 
The conjugated particles comprising the silver halide emulsions of the 
present invention are present in a ratio of particles where the second 
crystals are formed on all six (100) surfaces of the host crystals to the 
total conjugated crystals (i.e., including those wherein the second 
crystals are conjugated on less than all six (100) surfaces of the host 
crystals). This ratio is desirably about 40% or more (calculated on the 
basis of the total number of crystals in the emulsion or based on the 
weight thereof). Further, the emulsion contains preferably about 90% or 
more of the conjugated particles where the second silver halide crystals 
are conjugated to at least one of six (100) surfaces of said first silver 
halide crystals as calculated on the basis of the total number or weight 
of particles in the emulsion; the emulsion contains about 85% or more of 
the conjugated particles where the second silver halide crystals are 
conjugated to at least three of six (100) surfaces of said first silver 
halide crystals as calculated on the basis of the total number or weight 
of particles in the emulsion; and the emulsion contains about 60% or more 
of the conjugated particles where the second silver halide crystals are 
conjugated to at least four of six (100) surfaces of said first silver 
halide crystals as calculated on the basis of the total number of weight 
of particles in the emulsion. 
The ratio of the conjugated crystal particles where the second crystals 
formed on different (100) surfaces of the same host crystal are bound 
together (i.e., linking together over the edge portions of the (110) 
surfaces of the host crystal, or where the second crystals are bound 
together in such a way that they cover the corner portions of the host 
crystal or the (111) surfaces of the tetradecahedral host crystal) to the 
total conjugated crystals desirably does not exceed about 80% of the total 
number or weight of the crystal particles in the emulsion. In this regard, 
conjugated crystals wherein six or more edges portions from among the 
twelve edge portions of the host crystal are not bound together by the 
second crystal are acceptable for purposes of the present invention. 
Further, conjugated crystals wherein eight corner portions of the host 
crystal or four or more surfaces from among the (111) surfaces thereof 
have remained uncovered are also acceptable. 
The wording "the second conjugate silver halide crystals are conjugated 
over one or more surfaces of the first host silver halide crystals in the 
form of one or more projections" as used herein means that the surfaces of 
the host crystals have either remained uncovered by the second crystals 
after the conjugation of the second crystals on the host crystals, or the 
second crystals do not entirely cover all of the surfaces of the host 
crystals in the resulting conjugated crystal particles. 
The halogen composition of the host crystals may be silver bromide, silver 
chlorobromide, silver chloride, etc. The silver chlorobromide crystals may 
comprise any silver halide composition, i.e., where the content of the 
silver chloride varies from 0 mol% to 100 mol%, with 100 mol% being 
exclusive of silver bromide. The wording "substantially free from silver 
iodide" means that the proportion of the content of silver iodide is about 
2 mol% or less, preferably 1 mol% or less, and most preferably, the silver 
iodide content is zero. 
The halogen composition of the second silver halide crystals to be 
conjugated on the host crystals may be silver bromide, silver 
chlorobromide or silver chloride; in particular, silver chlorobromide and 
silver chloride are especially preferred as the second silver halide 
conjugate crystals. If the second crystals contain silver iodide, the 
content thereof is desirably about 2 mol% or less. The halogen 
compositions of the conjugate crystals and the host crystals are desirably 
differentiated from each other by at least 1 mol% or more silver chloride. 
The formation of the conjugated particles of the present invention begins 
with the preparation of the host crystals. The cubic particles, 
rectangular parallelepiped particles and tetradecahedral particles are 
prepared, for example, by blending a soluble silver salt aqueous solution 
and a soluble halide aqueous solution under the condition of a constant 
silver ion concentration. If silver chloride is present in the reaction 
system, the silver ion concentration is not necessarily required to be 
kept constant during the formation of the host crystals. The formation of 
these crystal particles is well-documented in pertinent literature and 
publications, for example, in the above-mentioned Die Grundlagen der 
Photographischen Prozesse mit Silberhalogeniden, etc. Further, these 
crystal particles can be formed by the method as reported in E. Moiser and 
E. Klein, Physicochemistry, Bunsen Association Report, Vol. 67 (1963). The 
formation of the cubic, rectangular parallelepiped or tetradecahedral 
crystal particles comprising additional (110) surfaces will be described 
hereinafter. 
The host crystal particles may be of a so-called two-layered structure 
wherein the internal portion or the core portion of the particle has a 
different halogen composition from that of the outer portion thereof or 
may have any other structure, so long as the surface or the shell portion 
of the crystal particle has a different halogen composition from the 
second silver halide crystals. 
The formation of the second or conjugate crystals over the host silver 
halide crystals follows the formation of the host crystals, and can be 
effected by adding a soluble halide aqueous solution which has a different 
halogen composition from that of the host crystals and a soluble silver 
salt aqueous solution to the previously formed host crystals in the 
presence of a crystal habit regulator ("growth modifier" described 
hereinafter), and precipitated thereover. During the formation of the 
conjugated crystal in this manner, the silver ion concentration is more 
preferably kept constant. Where the host crystals and second crystals 
comprise silver chlorobromide, conjugated crystals with a uniform 
conjugation between the host and conjugate particles can often be formed 
even through the silver ion concentration is not kept constant during the 
formation of the conjugate crystals. In particular, if the content of 
silver chloride of the host crystals and second crystals is high, the 
aqueous halide solution can first be added to the suspension of host 
silver halide crystals and then the silver salt aqueous solution can be 
added thereto, or as the case may be, the silver salt aqueous solution can 
be added thereto later, whereby the desired conjugated particles can be 
obtained. 
The soluble halide aqueous solution and silver salt aqueous solution used 
to form the conjugate crystals are added to the host silver halide 
crystals at a maximum addition speed falling within the range such that 
the addition of these solutions does not cause the formation of any new 
nuclei, the conjugate crystals then are precipitated over the host 
crystals, so that the resulting conjugated silver halide crystals may have 
a composition which is close to the stoichiometrical composition of the 
aqueous halide solution initially added and the composition of the host 
silver halide crystals remains almost the same as the initial composition. 
However, if these formation conditions for the resulting conjugated 
particles are not used, or if the particles are physically ripened after 
the formation thereof using the above-described formation conditions, the 
soluble halide aqueous solution added or the second silver halide crystals 
formed and the host silver halide particles will recrystallize or will 
undergo halogen conversion whereby the composition of the conjugated 
silver halide crystals formed will be different from the stoichiometrical 
composition of the soluble halide aqueous solution added to the host 
crystals and, therefore, the composition of the host silver halide 
crystals themselves, after being conjugated, will often be different from 
that of the initial host crystals. In the formation of particles of the 
present invention, however, such compositional variation does not occur in 
most cases because of the presence of the crystal habit regulator; on the 
other hand, such variations can easily be made to occur, if desired. The 
variations in the halogen compositions of the host silver halide crystals 
and the conjugate silver halide crystals, which will result from the 
above-noted recrystallization or the like, or variations in the molar 
ratio of the halogen compositions constituting the host crystals and the 
conjugated crystals, are noted to be more remarkable where there is a 
larger difference between the halogen compositions of the host crystals 
and the conjugate crystals, or the silver halides as used have a higher 
solubility. Even though such variations may have occurred, silver halide 
emulsions containing the conjugated particles with the shapes as defined 
in the present invention can be obtained. 
Where the halide used to form the second silver halide crystals is of the 
same halogen composition as that of the host silver halide crystals, 
formation of the conjugated particles of the present invention is 
impossible, since the particles will grow to form multilayered structural 
or core-shell structural particles. The differentiation of the halogen 
compositions between the host silver halide crystals and the second silver 
halide crystals is considered to be essential in the formation of the 
conjugated crystal particles of the present invention. Since the 
conjugated particles of the present invention have different halogen 
compositions beteen the host crystal part and the conjugate crystal part, 
recrystallization sometimes occurs during the formation of the particles 
which causes the fusion of the conjugate crystals or the incorporation of 
the conjugate crystals into the host crystals themselves. The result of 
such interaction is that the particles formed sometimes could not have a 
conjugated structure. Such particles with no conjugated structure are 
outside the scope of the present invention. 
In order to inhibit the formation of such non-conjugated particles falling 
outside the scope of the present invention, for example, the conjugated 
crystal-forming speed during the formation of the second silver halide 
crystals should be higher than the speed at which non-conjugated crystals 
are formed due to recrystallization or Ostwald's ripening. To achieve this 
aim, the speed of the addition of the silver salt aqueous solution and/or 
the soluble halide aqueous solution for the formation of the second silver 
halide crystals should be established near to the critical speed necessary 
for the growth of the conjugated crystals. Specifically, this addition 
speed is to be determined so that if the soluble halide and silver salt 
solutions are added at a higher speed than the determined speed, the 
solutions would not be deposited on the already formed host crystal 
particles to form the second conjugate crystals thereon, but would form 
different, new crystal nuclei. If the addition speed is higher than the 
critical growth speed, the formation of new crystal nuclei occurs, and as 
mentioned above, does not always inhibit the formation of the conjugated 
crystals. Further, if the addition speed is lower than the critical growth 
speed, crystallization of the conjugated crystals being formed occurs, but 
depends upon a larger difference between the addition speed and the 
critical growth speed, whereby the conjugated crystals will be difficult 
to form. 
The critical growth speed as referred to herein varies depending upon the 
conditions for the formation of the crystals. For example, such conditions 
include the temperature, the silver ion concentration in the reaction 
system, the stirring speed or other blending conditions, and after the 
determination of the conditions for the actual formation of the particles, 
the critical growth speed can be experimentally determined by observing 
the existence of any newly formed crystals by an electron microscope. 
Further, the critcal growth speed also varies depending upon the specific 
crystal habit regulator employed. 
In the present invention, it is fairly difficult to indiscriminately and 
uniformly define the range of the conditions used in the formation of the 
conjugated crystals in view of the above-mentioned variables and concerns. 
In general, however, the addition speed of the silver ion and/or the 
halide ion desirably falls within the range of from about 0.1 to about 5 
times the critical growth speed of the particles. In particular, this 
range is more preferably from 0.15 to 3 times. 
If the above-mentioned crystal habit regulator is not used in the process 
of the present invention, the conjugated particles of the present 
invention having projecting conjugate crystals comprising mainly (110) 
surfaces could not be formed. Even if the conjugated particles could be 
formed, the second crystals would not mainly comprise (110) surfaces, or 
even worse, no conjugated particles would be formed. 
The "crystal habit regulator" as referred to herein includes compounds that 
can accelerate the development of the (110) crystal surfaces when the 
second silver halide particles are formed in an aqueous medium in the 
presence of a hydrophilic protective colloid, for example, those as 
illustrated in Japanese Patent Application (OPI) No. 222842/85 
(corresponding to European Pat. No. 159,045 A2). Further, some of the 
compounds described in German Pat. No. 2,222,297 (corresponding to U.S. 
Pat. No. 3,817,756) and their analogous compounds can also be used. 
However, all of the compounds described in these publications are not 
always effective as the crystal habit regulator of the present invention. 
Moreover, if the amount of the regulator present during the formation of 
the conjugated particles is not appropriate, the conjugated particles of 
the present invention could not be obtained. Specifically, if the amount 
of regulator is too small, the resulting conjugated crystals which are 
surrounded mainly by (110) surfaces could not be formed or, as the case 
may be, no conjugated particles themselves could be formed, as mentioned 
above. If, on the contrary, the amount of regulator is too large, the 
conjugation would be interrupted. 
The chemical structures of the crystal habit regulators which are effective 
in the present invention are difficult to precisely define. However, 
preferred compounds include mercaptotetrazole type compounds, 
mercaptotriazole type compounds, mercaptothiadiazole type compounds, 
hydroxyazaindenes, merocyanine dyes having a rhodanine nucleus or a 
thiohydantoin nucleus, as well as certain kinds of cyanine dyes such as 
benzothiadicarbocyanine, etc. 
Other silver halide adsorptive compounds present during the formation of 
the conjugated particles will sometimes inhibit the formation of the 
conjugated particles of the present invention. Many of the cyanine dyes 
will inhibit the formation of the conjugated particles, if present during 
the formation of the second silver halide crystals, whereby the resulting 
shapes of the silver halide particles formed will often be cubic or 
rectangular parallelepiped. However, such compounds having this type of 
inhibitory activity are sometimes effective for stabilizing the shapes of 
the already formed conjugated particles, and, therefore, these compounds 
can be used in the process of the present invention within amounts that 
will not inhibit the formation of the conjugated particles. The shapes of 
the conjugated particles of the present invention can be easily varied 
depending upon the temperature or pAg of the emulsion or the kind and the 
amount of the crystal habit regulator, and the conjugated particles do not 
always have the required (110) surfaces selectivity. In such a case, some 
silver halide adsorptive compounds can be added during the formation of 
the particles in order to impart (110) surface selectivity to the 
resulting conjugated particles. 
The co-use of a compound which accelerates the formation of the conjugated 
particles of the present invention and a compound which does not 
accelerate such formation makes it possible to vary the conjugated shapes 
of the conjugated particles or the halogen distribution in the particles. 
Further, additional third and fourth silver halides can be conjugated over 
the second conjugate silver halide crystals of the conjugated crystals of 
the present invention, if desired. 
The crystal habit regulator as used in the present invention is added to 
the reaction system prior to the completion of the formulation of the 
conjugated crystals, preferably prior to the formation of about 70 mol% of 
the conjugated crystals, more preferably prior to the formation of 40 mol% 
of the conjugated crystals, and most preferably prior to the beginning of 
the formation of the conjugated crystals. 
The crystal habit regulator can also be added to the reaction system prior 
to the formation of the host crystals or during the formation thereof. In 
this case, the presence of the regulator will sometimes cause the 
variation of the cubic, rectangular parallelepiped or tetradecahedral 
shapes of the host crystals to different shapes having an additional 
twelve (110) surfaces. This depends upon the kind or the amount of the 
crystal habit regulator used or the time of the addition thereof. Even in 
such a case, the host crystals can still be used in the present invention 
so long as they still comprise the necessary (110) surfaces on which the 
second conjugate crystals can be formed and grown to form the desired 
conjugated particles of the present invention. 
The crystal habit regulator is not always necessarily added at one time. 
The addition amount may be divided into several parts, and each part may 
then appropriately be added in each stage of the growth of the particles. 
Alternatively, the regulator may gradually be added at a constant speed or 
an accelerated speed, as with the addition of the silver salt aqueous 
solution or the soluble halide aqueous solution described above. Any 
combination of these addition methods can also be used in the present 
invention. 
The amount of the mercaptotetrazole type compound to be added, one type of 
crystal habit regulator which may be used herein, is preferably from about 
2.times.10.sup.-5 to about 2.times.10.sup.-2 mol, more preferably 
5.times.10.sup.-5 to 1.times.10.sup.-2 mol, and most preferably 
1.times.10.sup.-4 to 5.times.10.sup.-3 mol, per mol of the Ag ion used for 
the formation of the conjugated crystals. 
Suitable amounts of the mercaptothiadiazole type compound to be added is 
the same as that just described for the mercaptotetrazole type compound. 
The amount of the hydroxyazaindene type crystal habit regulator is, in the 
same manner, preferably about 2.times.10.sup.-4 to about 2.times.10.sup.-1 
mol, more preferably 5.times.10.sup.-4 to 1.times.10.sup.-1 mol, per mol 
of the Ag ion used for the formation of the conjugated crystal. The amount 
of the cyanine dye and that of the merocyanine dye which may be added each 
is, also in the same manner, preferably about 2.times.10.sup.-5 to about 
2.times.10.sup.-2 mol, more preferably 5.times.10.sup.-5 to 
1.times.10.sup.-2 mol, per mol of the Ag ion used for the formation of the 
conjugated crystals. 
The mercaptotetrazole type compounds which are preferably used in the 
present invention can be selected from those represented by the following 
general formula (I): 
##STR1## 
wherein R represents an alkyl group, an alkenyl group or an aryl group, 
and X represents a hydrogen atom, an alkali metal atom, an ammonium group 
or a precursor. The alkali metal atom includes, for example, a sodium 
atom, a potassium atom, etc.; the ammonium group includes, for example, a 
trimethylammonium chloride group, a dimethylbenzylammonium chloride group, 
etc. The precursor is a group which may be a hydrogen atom or an alkali 
metal under an alkaline condition, for example, including an acetyl group, 
a cyanoethyl group, a methanesulfonylethyl group, etc. 
The alkyl group and the alkenyl group representative of R in general 
formula (I) include unsubstituted groups and substituted groups, and 
additionally, alicyclic groups. Examples of the substituents in the 
substituted alkyl groups are a halogen atom, an alkoxy group, an aryl 
group, an acylamino group, an alkoxycarbonylamino group, a ureido group, a 
hydroxyl group, an amino group, a heterocyclic group, an acyl group, a 
sulfamoyl group, a sulfonamido group, a thioureido group, a carbamoyl 
group, and additionally, a carboxylic acid group, a sulfonic acid group 
and a salt thereof, etc. 
The ureido group, thioureido group, sulfamoyl group, carbamoyl group and 
amino group mentioned as substituents for the alkyl groups may be 
unsubstituted or may be N-alkyl-substituted or N-aryl-substituted. 
Examples of the aryl group for R are a phenyl group and substituted phenyl 
groups; the substituents on the substituted phenyl groups include an alkyl 
group and the substituents suitable for substituted alkyl groups in the 
above description. 
The mercaptothiadiazole type compounds which are preferably used in the 
present invention can be selected from those represented by the following 
general formula (II): 
##STR2## 
wherein L represents a divalent linking group; R' represents a hydrogen 
atom, an alkyl group, an alkenyl group or an aryl group; and n represents 
0 or 1. The alkyl group and alkenyl group for R' as well as X have the 
same meanings as described above in general formula (I). 
Examples of the divalent linking group represented by L include 
##STR3## 
etc., wherein R.sup.0, R.sup.1 and R.sup.2, which may be the same or 
different, each represents a hydrogen atom, an alkyl group or an aralkyl 
group. 
The hydroxyazaindenes which are preferably used in the present invention 
can be selected from those represented by the following general formula 
(III): 
##STR4## 
wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 may be the same or different 
and each represents a hydroxyl group, an alkyl group, an alkenyl group, an 
aryl group, a cyano group, a ureido group, an amino group, a halogen atom 
or a hydrogen atom, with the proviso that the number of hydroxyl groups in 
the formula is to be 1 or 2. 
The above-mentioned alkyl group, alkenyl group, aryl group, ureido group 
and amino group may be substituted in the same manner as described above 
for these same groups in the above-mentioned general formula (I). 
Especially preferred substituents for the alkyl group are an aryl group, 
an alkoxycarbonyl group, a carbamoyl group, a cyano group, an amino group 
and a sulfonamido group. 
Further, R.sub.3 and R.sub.4 may be linked together to form a 5- or 
6-membered, saturated or unsaturated carbon ring. 
Typical examples of the crystal habit regulators which can be used in the 
formation of the conjugated particles of the present invention include the 
following compounds: 
##STR5## 
The silver halide emulsions of the present invention may be chemically 
sensitized. For instance, various known methods may be used for the 
chemical sensitization, including a sulfur sensitization method in which a 
sulfur-containing compound capable of reacting with an active gelatin and 
silver (such as a thiosulfate, a thiourea, a mercapto compound, or a 
rhodanine compound) is used; a reduction sensitization method in which a 
reducing substance (such as stannous salt, an amine compound, a hydrazine 
derivative, a formamidinesulfinic acid, or a silane compound) is used; and 
a noble metal sensitization method in which a noble metal compound (such 
as a gold complex or a Pt-, Ir-, Pd- or other Periodic Table VIII group 
metal-complex) is used. These sensitization methods may be used alone or 
in combination. 
The photographic emulsions of the present invention can contain a variety 
of compounds for the purpose of the prevention of the occurrence of fog 
during the manufacture and preservation of the photographic 
light-sensitive materials and for the stabilization of the photographic 
characteristics of the materials. For instance, a variety of compounds 
which are known as fog inhibitors or stabilizers can be added to the 
materials for these purposes, including azoles such as benzothiazolium 
salts, nitroindazoles, triazoles, benzotriazoles, and benzimidazoles 
(especially nitro- or halogen-substituted forms); heterocyclic mercapto 
compounds such as mercaptothiazoles, mercaptobenzothiazoles, 
mercaptobenzimidazoles, mercaptothiadiazoles, mercaptotetrazoles 
(especially 1-phenyl-5-mercaptotetrazole and substituted derivatives 
thereof), and mercaptopyrimidines; the above-mentioned heterocyclic 
compounds which further contain a water-soluble group such as a carboxyl 
group or a sulfone group; thioketo compounds such as oxazolinethiones; 
azaindenes such as tetraazaindenes (especially 4-hydroxy-substituted 
(1,3,3a,7)tetraazaindenes); benzenethiosulfonic acids; benzenesulfinic 
acids, etc. 
The photographic emulsions of the present invention can contain further 
additives for the purpose of increasing sensitivity, increasing the 
contrast or the acceleration of developability. Examples of such additives 
include polyalkylene oxides or ethers, esters, amines or similar 
derivatives thereof, thioether compounds, thiomorpholines, quaternary 
ammonium salt compounds, urethane derivatives, urea derivatives, imidazole 
derivatives and 3-pyrazolidones. 
Any known water-soluble dyes can be incorporated in the silver halide 
photographic emulsions of the present invention (for example, oxonol dyes, 
hemioxonol dyes or merocyanine dyes) as a filter dye or for the purpose of 
irradiation prevention or for any other various purposes. In addition, any 
other known cyanine dyes, merocyanine dyes, hemicyanine dyes or the like 
can also be incorporated in the emulsions before, during or after the 
chemical sensitization thereof as a spectral sensitizer or for the purpose 
of controlling the crystal shape or the size of the silver halide 
particles. 
The silver halide photographic emulsions of the present invention can 
contain color couplers such as cyan couplers, magenta couplers or yellow 
couplers or compounds containing a dispersion of these couplers. The 
couplers to be incorporated are preferably non-diffusible because of the 
presence of a ballast group therein or their having been polymerized. 
Suitable color couplers include 2-equivalent color couplers where the 
coupling active position is substituted by a releasing group are preferred 
over 4-equivalent color couplers where the coupling active position is 
occupied by a hydrogen atom, since the amount of the silver in the 
emulsion to be coated can be reduced when using 2-equivalent couplers. In 
addition, couplers that can form colored dyes with a pertinent 
diffusibility, non-coloring couplers, DIR couplers which can release a 
development inhibitor upon undergoing a coupling reaction or couplers 
which can release a development accelerator upon undergoing a coupling 
reaction, can also be used. 
Typical examples of the yellow couplers which can be used in the present 
invention are oil-protect type acylacetamide couplers. Specific examples 
thereof are described in, e.g., U.S. Pat. Nos. 2,407,210, 2,875,057 and 
3,265,506. In particular, 2-equivalent yellow couplers are preferably used 
in the present invention, and typical examples thereof are oxygen 
atom-releasing type yellow couplers as described in, e.g., U.S. Pat. Nos. 
3,408,194, 3,447,928, 3,933,501 and 4,022,620; and nitrogen atom-releasing 
type yellow couplers as described in, e.g., Japanese Patent Publication 
No. 10739/83, U.S. Pat. Nos. 4,401,752 and 4,326,024, Research Disclosure, 
No. 18053 (April, 1979), British Pat. No. 1,425,020, and German Patent 
Application (OLS) Nos. 2,219,917, 2,261,361, 2,329,587 and 2,433,812. In 
particular, .alpha.-pivaloylacetanilide type couplers are excellent in 
fastness, especially light fastness, of the colored dyes; on the other 
hand, .alpha.-benzoylacetanilide type couplers can form colored dyes with 
high color density. 
The magenta couplers which can be used in the present invention include, 
for example, oil-protect type indazolone or cyanoacetyl couplers, 
preferably 5-pyrazolone or pyrazoloazole couplers such as 
pyrazolotriazoles. The 5-pyrazolone type couplers where the 3-position is 
substituted by an arylamino group or an acylamino group are preferred in 
view of the hue and color density of the colored dyes; typical examples 
thereof are described in, e.g., U.S. Pat. Nos. 2,311,082, 2,343,703, 
2,600,788, 2,908,573, 3,062,653, 3,152,896 and 3,936,015. Releasing groups 
in the 2-equivalent 5-pyrazolone type couplers include nitrogen-releasing 
groups as described in U.S. Pat. No. 4,310,619 and arylthio groups as 
described in U.S. Pat. No. 4,351,897. In addition, ballast 
group-containing 5-pyrazolone type couplers as described in European Pat. 
No. 73,636 are preferred, due to their ability to form colored dyes with 
high color density. 
The pyrazoloazole type couplers which can be used in the present invention 
include, for example, pyrazolobenzimidazoles as described in U.S. Pat. No. 
3,369,879, preferably pyrazolo[5,1-c][1,2,4]triazoles; pyrazolotetrazoles 
as described in Research Disclosure, No. 24220 (June, 1984); and 
pyrazolopyrazoles as described in Research Disclosure, No. 24230 (June, 
1984). In particular, imidazo[1,2-b]pyrazoles as described in European 
Pat. No. 119,741 are preferred due to their small amount of yellow side 
absorption and high light fastness; and pyrazolo[1,5-b][1,24]triazoles as 
described in European Pat. No. 119,860 are especially preferred. 
The cyan couplers which can be used in the present invention include, for 
example, oil-protect type naphthol or phenol couplers; typical examples 
thereof are naphthol type couplers as described in U.S. Pat. No. 
2,474,293, preferably oxygen atom-releasing type 2-equivalent naphthol 
couplers as described in U.S. Pat. Nos. 4,052,212, 4,146,396, 4,228,233 
and 4,296,200. In addition, specific examples of phenol type couplers are 
described in, e.g., U.S. Pat. Nos. 2,369,929, 2,801,171, 2,772,162 and 
2,895,826. In particular, cyan couplers that are fast to moisture and 
temperature are preferably used in the present invention; typical examples 
thereof are phenol type cyan couplers which have an ethyl or higher alkyl 
group in the m-position of the phenol nucleus, as described in U.S. Pat. 
No. 3,772,002; 2,5-diacylamino-substituted phenol type couplers as 
described in U.S. Pat. Nos. 2,772,162, 3,758,308, 4,126,396, 4,334,011 and 
4,327,173, German Patent Application (OLS) No. 3,329,729 and Japanese 
Patent Application (OPI) No. 166956/84; and phenol type couplers having a 
phenylureido group in the 2-position and an acylamino group in the 
5-position, as described in U.S. Pat. Nos. 3,446,622, 4,333,999, 4,451,559 
and 4,427,767. 
The graininess can be improved by the incorporation of a coupler capable of 
forming a colored dye with suitable diffusibility. Such dye-diffusible 
couplers include the magenta couplers as described in U.S. Pat. No. 
4,366,237 and British Pat. No. 2,125,570, and the yellow, magenta or cyan 
couplers as described in European Pat. No. 96,570 and German Patent 
Application (OLS) No. 3,234,533. 
The dye-forming couplers and the above-mentioned special couplers may be in 
the form of a dimer or higher polymer. Typical examples of these 
polymerized dye-forming couplers are described in U.S. Pat. Nos. 3,451,820 
and 4,080,211. Specific examples of the polymerized magenta couplers are 
described in British Pat. No. 2,102,173 and U.S. Pat. No. 4,367,282. 
Two or more kinds of these couplers can be incorporated in the same 
light-sensitive layer, or the same coupler can be incorporated in two or 
more different layers in order that the photographic materials employing 
the emulsions of the present invention can have the necessary 
characteristics. 
The standard amount of the color coupler to be used is within about 0.001 
to about 1 mol per mol of the light-sensitive silver halide, and 
preferably the amount of the yellow coupler is from about 0.01 to about 
0.5 mol, that of the magenta coupler is from about 0.003 to about 0.3 mol 
and that of the cyan coupler is from about 0.002 to about 0.3 mol, each 
per mol of the silver halide. 
The photographic light-sensitive materials to be formed in accordance with 
the present invention can contain hydroquinone derivatives, aminophenol 
derivatives, amines, gallic acid derivatives, catechol derivatives, 
ascorbic acid derivatives, non-coloring couplers, sulfonamidophenol 
derivatives, etc., as color fog inhibitors or color stain inhibitors. 
The photographic light-sensitive material of the present invention can 
further contain a known discoloration inhibitor. Typical examples of 
suitable organic discoloration inhibitors are hindered phenols such as 
hydroquinones, 6-hydroxychromans, 5-hydroxycoumarans, spirochromans, 
p-alkoxyphenols and bisphenols, and gallic acid derivatives, 
methylenedioxybenzenes, aminophenols, hindered amines, as well as ether 
and ester derivatives thereof where the phenolic hydroxyl group in the 
compound is silylated or alkylated. In addition, metal complexes such as 
(bissalicylaldoximato)nickel complexes and 
(bis-N,N-dialkyldithiocarbamato)nickel complexes can also be used. 
Compounds having both partial structures of a hindered amine and a hindered 
phenol in 1 molecule, as described in U.S. Pat. No. 4,268,539, are 
effective for the prevention of the deterioration of the yellow colored 
images under conditions of heat, moisture and light. Spiroindanes as 
described in Japanese Patent Application (OPI) No. 159644/81 and 
hydroquinone-diether- or -monoether-substituted chromans as described in 
Japanese Patent Application (OPI) No. 89835/80 are effective for the 
prevention of the deterioration of the magenta colored images, especially 
under light. 
Benzotriazole type ultraviolet absorbents are preferably used for improving 
the preservation stability, especially light fastness, of the cyan images. 
The ultraviolet absorbent can be co-emulsified together with the cyan 
coupler. 
The amount of the ultraviolet absorbent to be coated is enough to be 
satisfactory for imparting light stability to the cyan colored images. If, 
however, the amount is too large, the non-exposed part (white background 
part) of the color photographic material will be tinted yellow, and, 
therefore, the amount, in general, preferably should fall within the range 
of about 1.times.10.sup.-4 mol/m.sup.2 to about 2.times.10.sup.-3 
mol/m.sup.2, especially 5.times.10.sup.-4 mol/m.sup.2 to 
1.5.times.10.sup.-3 mol/m.sup.2. 
In the constitution of the light-sensitive layers of generally used color 
papers, the ultraviolet absorbent is incorporated into one or preferably 
both of the layers adjacent to both sides of the cyan coupler-containing 
red-sensitive emulsion layer. When the ultraviolet absorbent is added to 
the intermediate layer between the green-sensitive emulsion layer and the 
red-sensitive emulsion layer, it may be co-emulsified together with the 
color stain inhibitor. If the ultraviolet absorbent is added to the 
protective layer, another protective layer can be provided thereon as an 
outermost layer. The protective layer can contain a matting agent or the 
like, having any desired grain size. 
The photographic light-sensitive materials of the present invention can 
also contain the ultraviolet absorbent in the hydrophilic colloid layer. 
The photographic light-sensitive materials of the present invention can 
contain a whitening agent such as stilbene type, triazine type, oxazole 
type, coumarin type or the like compounds, in the photographic emulsion 
layers or in other hydrophilic colloid layers. The whitening agents to be 
used may be water-soluble, or, as the case may be, water-insoluble 
whitening agents can also be used in the form of a dispersion thereof. 
As mentioned above, the emulsion of the present invention can be adopted to 
multilayer and multicolor photographic materials having at least two 
layers of different spectral sensitivities on a support. Multilayer 
natural color photographic materials have, in general, at least one 
red-sensitive emulsion layer, at least one green-sensitive emulsion layer 
and at least one blue-sensitive emulsion layer on a support. The order of 
these layers to be provided on the support can be selected freely 
depending on the desired results. Each of the emulsion layers may comprise 
two or more layers having different degrees of sensitivity, or a 
light-insensitive layer may be provided between two or more layers having 
the same color sensitivity. 
The photographic light-sensitive materials of the present invention 
preferably have auxiliary layers such as a protective layer, an 
intermediate layer, a filter layer, an antihalation layer and a backing 
layer, in addition to the silver halide emulsion layers, as desired. 
Gelatin is advantageously used as the binder or protective colloid to be 
incorporated into the emulsion layer or intermediate layer of the 
photographic light-sensitive materials of the present invention; other 
known hydrophilic colloids can, of course, also be used, for instance, 
proteins such as gelatin derivatives, graft polymers of gelatin and other 
high molecular weight substances, albumin, or casein; cellulose 
derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose, or 
cellulose sulfates; saccharide derivatives such as sodium alginate or 
starch derivatives; homo- or copolymers comprising various synthetic 
hydrophilic high molecular weight substances such as polyvinyl alcohol, 
partially acetalized polyvinyl alcohol, poly-N-pyrrolidone, polyacrylic 
acid, polymethacrylic acid, polyacrylamide, polyvinyl imidazole, polyvinyl 
pyrazole, etc. 
Gelatins which can be used in the present invention include lime-treated 
gelatin, acid-treated gelatin and enzyme-treated gelatin as described in 
Bull. Soc. Sci. Phot. Japan, No. 16, page 30 (1966); in addition, 
hydrolyzed or enzyme-decomposed products of gelatins can also be used. 
The finished emulsions are coated on a suitable support, for example, a 
baryta paper, a resin-coated paper, a synthetic paper, a triacetate film, 
a polyethylene terephthalate film or a similar plastic base, or a glass 
plate. 
The silver halide photographic materials containing the novel emulsions of 
the present invention can be utilized, for example, in color positive 
films, color papers, color negative films, color reversal films 
(containing or not containing couplers), photographic light-sensitive 
materials for photomechanical processes (such as lith films, lith-dupe 
films), light-sensitive materials for cathode ray tube display, 
light-sensitive materials for X-ray recording, light sensitive materials 
for silver salt diffusion transfer processes, light-sensitive materials 
for color diffusion transfer processes, light-sensitive materials for 
imbibition transfer processes, emulsions to be used in silver dye 
bleaching processes, light-sensitive materials for recording printout 
images, light-sensitive materials for direct print images, light-sensitive 
materials for heat development, light-senstive materials for physical 
development, etc. 
The exposure for obtaining the photographic images can be carried out in a 
conventional manner. For instance, any one of various known light sources 
can be used for the exposure, including, for example, natural light 
(daylight), a tungsten lamp, a fluorescent lamp, a mercury lamp, a xenon 
arc lamp, a carbon arc lamp, a xenon flash lamp, a cathode ray tube flying 
spot, etc. The exposure time may be from about 1/1,000 second to about 1 
second, which is a common exposure time for most cameras. Further, a 
shorter exposure time than 1/1,000 second, for example, from 1/10.sup.4 to 
1/10.sup.6 second by the use of a xenon flash lamp or a cathode ray tube, 
may also be used. On the other hand, a longer exposure time than 1 second 
can also be used. If necessary, the spectral composition of the light to 
be used for the exposure can be regulated by using a color filter. A laser 
ray can also be utilized for the exposure. In addition, the materials can 
be exposed with a light as emitted from a fluorescent material excited by 
an electron ray, X-ray, .gamma.-ray, .alpha.-ray, etc. 
Any known methods and known processing solutions, as described, e.g., in 
Research Disclosure, No. 17643, pp. 28-30 (November, 1978), can be 
utilized in the photographic treatment of the light-sensitive materials of 
the present invention. The photographic treatment may be either a 
photographic treatment for the formation of silver images (black-and-white 
photographic treatment) or a photographic treatment for the formation of 
color images (color photographic treatment), in accordance with the 
objects and usage of the materials. The processing temperature is 
generally selected from about 18.degree. C. to about 50.degree. C. 
However, the temperature may be lower than 18.degree. C. or higher than 
50.degree. C., if desired. 
The color developers which can be used in the development of the materials 
of the present invention are preferably alkaline aqueous solutions 
containing an aromatic primary amine type color developing agent as a main 
component. Suitable color developing agents preferably used are 
p-phenylenediamine type compounds; typical examples thereof are 
3-methyl-4-amino-N,N-diethylaniline, 
3-methyl-4-amino-N-ethyl-N-.beta.-hydroxyethylaniline, 
3-methyl-4-amino-N-ethyl-N-.beta.-methanesulfonamidoethylaniline, 
3-methyl-4-amino-N-ethyl-N-.beta.-methoxyethylaniline and sulfates, 
hydrochlorides, phosphates and p-toluene-sulfonates thereof, as well as 
tetraphenylborates and p-(t-octyl)benzenesulfonates thereof. 
Aminophenol type derivatives can also be used, including, for example, 
o-aminophenol, p-aminophenol, 4-amino-2-methylphenol, 
2-amino-3-methylphenol, 2-oxy-3-amino-1,4-dimethylbenzene, etc. 
In addition, compounds as described in L.F.A. Mason, Photographic 
Processing Chemistry, pp. 226-229, (Focal Press, 1979), U.S. Pat. Nos. 
2,193,015 and 2,592,364 and Japanese Patent Application (OPI) No. 64933/73 
can also be used. If necessary, two or more kinds of color developing 
agents can be used in combination. 
The processing temperature of the color developer is preferably about 30 to 
about 50.degree. C., more preferably 33 to 45.degree. C. 
Development accelerators may be used in the developer, but benzyl alcohol 
is preferably not used in view of the prevention of pollution. Instead of 
the use of benzyl alcohol, various other kinds of compounds can be used. 
For instance, various kinds of pyrimidium compounds and other cationic 
compounds, phenosafranines and similar cationic dyes, and natural salts 
such as thallium nitrate and potassium nitrate, as typically described in, 
e.g., U.S. Pat. No. 2,648,604, Japanese Patent Publication No. 9503/69 and 
U.S. Pat. No. 3,171,247 can be used, as well as polyethylene glycol and 
derivatives thereof, and polythioethers and similar nonionic compounds, as 
described in Japanese Patent Publication No. 9304/69, U.S. Pat. Nos. 
2,533,990, 2,531,832, 2,950,970 and 2,577,127, thioether type compounds as 
described in U.S. Pat. No. 3,201,242, and the compounds described in 
Japanese Patent Application (OIP) Nos. 156934/83 and 220344/85. 
In a rapid development treatment to be completed in a short period of time, 
both the means for accelerating development and the techniques for 
preventing the formation of fog during development are important. 
Preferred fog inhibitors are alkali metal halides such as potassium 
bromide, sodium bromide and potassium iodide, as well as organic fog 
inhibitors. The organic fog inhibitors which can be used herein include 
nitrogen-containing heterocyclic compounds such as benzotriazole, 
6-nitrobenzimidazole, 5-nitroisoidazole, 5-methylbenzotriazole, 
5-nitrobenzotriazole, 5-chlorobenzotriazole, 2-thiazolylbenzimidazole, 
2-thiazolylmethylbenzimidazole and hydroxyazaindolizine; 
mercapto-substituted heterocyclic compounds such as 
1-phenyl-5-mercaptotetrazole, 2-mercaptobenzimidazole and 
2-mercaptobenzothiazole; as well as mercapto-substituted aromatic 
compounds such as thiosalicylic acid. In particular, halides are 
especially preferred as the fog inhibitor. The fog inhibitors can also be 
incorporated in the color photographic light-sensitive materials to be 
processed (in addition to be added directly to the developer), whereby the 
fog inhibitor can be dissolved out from the material being processed so as 
to precipitate in the color developer during the processing of the 
materials. 
In addition, the color developer can contain a pH buffer such as alkali 
metal carbonates, borates and phosphates; a preservative such as 
hydroxylamine, triethanolamine, the compounds described in German Patent 
Application (OLS) No. 2,622,950, sulfites and bisulfites; an organic 
solvent such as diethylene glycol; a dye-forming coupler; a competing 
coupler; a nucleating agent such as sodium boronhydride; an auxiliary 
developing agent such as 1-phenyl-3-pyrazolidone; a tackifier; a chelating 
agent such as aminopolycarboxylic acids including 
ethylenediaminetetraacetic acid, nitrilotriacetic acid, 
cyclohexanediaminetetraacetic acid, iminodiacetic acid, 
N-hydroxymethylethylenediaminetriacetic acid, 
diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid 
and the compounds described in Japanese Patent Application (OPI) No. 
195845/83, 1-hydroxyethylidene-1,1'-diphosphonic acid, organic phosphonic 
acids as described in Research Disclosure, No. 18170 (May, 1979), 
aminophosphonic acids including aminotris(methylenephosphonic acid) and 
ethylenediamine-N,N,N',N'-tetramethylenephosphonic acid, the 
phosphonocarboxylic acids described in Japanese Patent Application (OPI) 
Nos. 102726/77, 42730/78, 121127/79, 4024/80, 4025/80, 126241/80, 65955/80 
and 65956/80, and Research Disclosure, No. 18170 (May, 1979), etc. 
The color developer can be divided into two or more developer baths, if 
necessary, whereupon a color developer replenisher can be replenished into 
the first bath or into the last bath in the course of the development so 
that the development time can be reduced and, further, the amount of the 
replenisher can also be reduced. 
The silver halide color photographic materials are, after having been color 
developed, generally bleached. The bleaching step can be carried out 
simultaneously with fixation (bleaching-fixation) or, alternatively, 
separately therefrom. Bleaching agents which can be used are, for example, 
compounds of polyvalent metals such as iron (III), cobalt (III), chromium 
(VI) or copper (II), peracids, quinones and nitroso compounds. For 
instance, ferricyanides, bichromates, organic complexes with iron (III) or 
cobalt (III) such as complexes of ethylenediaminetetraacetic acid, 
diethylenetriaminepentaacetic acid, nitril.triacetic acid, 
1,3-diamino-2-propanoltetraacetic acid or similar aminopolycarboxylic 
acids or with citric acid, tartaric acid, malic acid or similar organic 
acids; persulfates, manganates; and nitrosophenol can be used. In 
particular, potassium ferricyanide, sodium ethylenediaminetetraacetato 
ferrate, ammonium ethylenediaminetetraacetato ferrate, ammonium 
triethylenetetraminepentaacetato ferrate and persulfates are especially 
preferred. Ethylenediaminetetraacetato ferrate complexes are usable both 
in an independent bleaching solution and in a combined bleaching-fixation 
solution. 
The bleaching solution and the bleaching-fixation solution may contain, if 
necessary, various kinds of accelerators. For instance, a bromide ion, an 
iodide ion, as well as thiourea type compounds as described in U.S. Pat. 
No. 3,706,561, Japanese Patent Publication Nos. 8506/70 and 26586/74, and 
Japanese Patent Application (OPI) Nos. 32735/78, 36233/78 and 37016/78; 
thiol type compounds as described in Japanese Patent Application (OPI) 
Nos. 124424/78, 95631/78, 57831/78, 32736/78, 65732/78 and 52534/79 and 
U.S. Pat. No. 3,893,858; heterocyclic compounds as described in Japanese 
Patent Application (OPI) Nos. 59644/74, 140129/75, 28426/78, 141623/78, 
104232/78 and 35727/79; thioether type compounds as described in Japanese 
Patent Application (OPI) Nos. 20832/77, 25064/80 and 26506/80; quaternary 
amines as described in Japanese Patent Application (OPI) No. 84430/73; and 
thiocarbamoyl type compounds as described in Japanese Patent Application 
(OPI) No. 42349/74 can be used. 
Suitable fixing agents include thiosulfates, thiocyanates, thioether type 
compounds, thioureas and iodides. In particular, thiosulfates are 
generally used. As the preservative for the bleaching-fixation solution or 
the fixation solution, sulfites or bisulfites or carbonyl-bisulfite 
adducts are preferred. 
After the bleaching-fixation step or the fixation step, the photographic 
materials are generally washed with water. In the washing step, various 
kinds of known compounds can be used fro the purpose of the prevention of 
precipitation or of the economization of water. For instance, a water 
softener such as inorganic phosphoric acids, aminopolycarboxylic acids or 
organic phosphoric acids; a bactericide or fungicide for the prevention of 
growth of various bacteria, algae or fungi; a hardener such as magnesium 
salts or aluminum salts; a surfactant for the prevention of drying load or 
unevenness, etc., can be added as necessary. As the case may be, the 
compounds described in L.E. West, Photographic Science and Engineering, 
Vol. 9, No. 6 (1965) can be added. In particular, the addition of the 
chelating agent or fungicide is effective. A multistage countercurrent 
flow system (for example, comprising 2 to 5 stages) can be used in the 
washing step for the purpose of the economization of water. 
After the washing step or in place thereof, the photographic material may 
be subjected to multistage countercurrent stabilizing process as described 
in Japanese Patent Application (OPI) No. 8543/82. The stabilization step 
requires a countercurrent bath line comprising 2 to 9 baths. Various kinds 
of compounds are added to the stabilization baths for the stabilization of 
images. For instance, a film pH regulating buffer (such as borates, 
metaborates, borax, phosphates, carbonates, potassium hydroxide, sodium 
hydroxide, aqueous ammonia, monocarboxylic acids, dicarboxylic acids, 
polycarboxylic acids, etc.) and formalin can be added. In addition, a 
water softener (such as inorganic phosphoric acids, aminopolycarboxylic 
acids, organic phosphoric acids, aminopolyphosphonic acids, 
phosphonocarboxylic acids, etc.), a bactericide (such as Proxel 
(benzoisothiazoline), isothiazolone, 4-thiazolylbenzimidazole, halogenated 
phenolbenzotriazoles, etc.), a surfactant, a brightening agent, a 
hardener, etc., can further be added as needed. 
Various kinds of ammonium salts such as ammonium chloride, ammonium 
nitrate, ammonium sulfate, ammonium phosphate, ammonium sulfate or 
ammonium thiosulfate can be added as a film pH regulator for regulating 
the pH value of the film after processing. 
The present invention will be explained in greater detail by reference to 
the following examples, which, however, are not intended to be interpreted 
as limiting the scope of the present invention. Unless otherwise 
indicated, all parts, percents, ratios and the like are by weight. 
EXAMPLE 1 
30 g of lime-treated gelatin was addedto 1,000 cc of distilled water and 
dissolved at 40.degree. C. and, then, the resulting solution was regulated 
to have a pH value of 4.0 with sulfuric acid, and 6.5 g of sodium chloride 
and 0.02 g of N,N'-dimethylethylenethiourea were added thereto and 
dissolved, and the temperature of the resulting solution was elevated up 
to 65.degree. C. A solution of 62.5 g of silver nitrate dissolved in 750 
cc of distilled water and a solution of 30.6 g of potassium bromide and 
6.5 g of sodium chloride dissolved in 500 cc of distilled water were added 
to the previous solution over the course of 40 minutes, while the 
temperature was kept at 65.degree. C., and blended. The silver halide 
particles formed were observed with an electron microscope, indicating the 
formation of cubic crystals with a length of one edge of 0.36 .mu.m. To 
the emulsion containing the host crystals were further added a solution 
containing 62.5 g of silver nitrate dissolved in 500 cc of distilled 
water and a solution containing 13.1 g of potassium bromide and 15.1 g of 
sodium chloride dissolved in 300 cc of distilled water over the course of 
10 minutes, while the temperature was kept at 60.degree. C., and blended. 
The silver halide particles formed were observed with an electron 
microscope, indicating the formation of conjugated crystals, in which the 
(100) surfaces of the cubic crystals were conjugated with rectangular 
parallelepiped conjugate crystals comprising (100) surfces (Emulsion (A)). 
30 g of lime-treated gelatin was added to 1,000 cc of distilled water and 
dissolved at 40.degree. C., and then the resulting solution was regulated 
to have a pH value of 4.0 with sulfuric acid, and 6.5 g of sodium chloride 
and 0.02 g of N,N'-dimethylethylenethiourea were added thereto and 
dissolved, and thereafter the temperature of the resulting solution was 
elevated up to 60.degree. C. A solution containing 6.5 g of silver nitrate 
dissolved in 750 cc of distilled water and a solution containing 21.9 g of 
potassium bromide and 10.8 g of sodium chloride dissolved in 500 cc of 
distilled water were added to the previous solution over the course of 40 
minutes, while the temperature was kept at 60.degree. C., and blended. The 
silver halide particles formed were observed with an electron microscope, 
indicating the formation of cubic crystals with a length of one edge of 
0.36 .mu.m. To the emulsion containing the host crystals were further 
added a solution containing 62.5 g of silver nitrate dissolved in 500 cc 
of distilled water and a solution containing 21.9 g of potassium bromide 
and 10.8 g of sodium chloride dissolved in 300 cc of distilled water over 
the course of 10 minutes, while the temperature was kept at 60.degree. C., 
and blended. The silver halide particles formed were observed with an 
electron microscope, indicating the formation of cubic particles with a 
length of one edge of 0.45 .mu.m (Emulsion (B)). 
30 g of lime-treated gelatin was added to 1,000 cc of distilled water and 
dissolved at 40.degree. C., and then the resulting solution was regulated 
to have a pH value of 4.0 with sulfuric acid, and 6.5 g of sodium chloride 
and 0.02 g of N,N'-dimethylethylenethiourea were added thereto and 
dissolved, and the temperature of the resulting solution was elevated up 
to 55.degree. C. A solution containing 62.5 g of silver nitrate dissolved 
in 750 cc of distilled water and a solution containing 13.1 g of potassium 
bromide and 15.1 g of sodium chloride dissolved in 500 cc of distilled 
water were added to the previous solution over the course of 40 minutes, 
while the temperature was kept at 55.degree. C. The silver halide 
particles formed were observed with an electron microscope, indicating the 
formation of cubic crystals having a length of one edge of 0.36 .mu.m. To 
the emulsion containing the host crystals were further added a solution 
containing 62.5 g of silver nitrate dissolved in 500 cc of distilled water 
and a solution containing 30.6 g of potassium bromide and 6.5 g of sodium 
chloride dissolved in 300 cc of distilled water over the course of 10 
minutes, while the temperature was kept at 65.degree. C., and blended. The 
silver halide particles formed were observed with an electron microscope, 
indicating the formation of cubic particles with an edge of about 0.45 
.mu.m which were somewhat expanded in the corners and had steps in the 
(100) surfaces (Emulsion C)). 
A host crystal-containing emulsion was prepared in the same manner as 
described above for Emulsion (A)). Prior to the formation of the 
conjugated crystals, 0.10 g, 0.16 g or 0.32 g, respectively, of 
1-(m-methylureidophenyl)-5-mercaptotetrazole was added to the emulsion and 
the same silver nitrate solution and halide solution as used in the 
formation of the second silver halide crystals in Emulsion (A) described 
above were added thereto. The emulsions obtained were designated Emulsion 
(D), Emulsion (E) and Emulsion (F), respectively. 
Next, the host crystal-containing emulsion was prepared in the same manner 
as described above for Emulsion (B). Prior to the formation of the second 
or conjugate crystals, 0.10 g, 0.16 g or 0.32 g, respectively, of 
1-(m-methylureidophenyl)-5-mercaptotetrazole was added to the emulsion and 
the same silver nitrate solution and halide solution as used in the 
formation of the second silver halide crystals in Emulsion (B) described 
above were added thereto. The emulsions obtained were designated Emulsion 
(G), Emulsion (H) and Emulsion (I), respectively. 
Further, the host crystal-containing emulsion was prepared in the same 
manner as described above for Emulsion (C). Prior to the formation of the 
second or conjugate crystals, 0.10 g, 0.16 g or 0.32 g, respectively, of 
1-(m-methylureidophenyl)-5-mercaptotetrazole was added to the emulsion and 
the same silver nitrate solution and halide solution as used in the 
formation of the second silver halide crystals in Emulsion (C) described 
above were added thereto. The emulsions obtained were designated Emulsion 
(J), Emulsion (K) and Emulsion (L), respectively. 
The crystal particles were Emulsion (D) were observed with an electron 
microscope, indicating the formation of conjugated crystals, in which the 
(100) surfaces of the host crystals were conjugated with the second 
conjugate crystals which had (100) surfaces surrounded by (110) surfaces 
(FIG. 4). 
The crystal particles of Emulsion (E) were observed with an electron 
microscope, indicating the formation of conjugate crystals, in which the 
(100) surfaces of the host crystals were conjugated with the second 
conjugate crystals surrounded by (110) surfaces (FIG. 5). 
The crystal particles of Emulsion (F) were observed with an electron 
microscope, indicating the formation of conjugated crystals, in which the 
(100) surfaces of the host crystals were conjugated with the second 
conjugate crystals surrounded by four (110) surfaces and the overall 
appearance of each conjugated crystal particle was confirmed to have a 
shape like a rhombic dodecahedron. However, the conjugated crystal 
particles thus-formed were different from general or conventional rhombic 
dodecahedral crystals in that the edge parts (that is, the parts 
corresponding to the (110) surfaces) of the host cubic crystals existing 
in the conjugated particles were confirmed to have formed thin grooves 
(dividing the rhombic surfaces of the rhombic dodecahedral crystals into 
two parts (FIG. 6). 
The crystal particles of Emulsion (G) were observed with an electron 
microscope, indicating the formation of nearly cubic crystals in which the 
edge portions of the cubic crystals were confirmed to be somewhat rounded. 
The crystal particles of Emulsion (H) were observed with an electron 
microscope, indicating the formation of particles in which the edge 
portions of the cubic crystals were confirmed to be rounded to fairly 
reveal the (110) surfaces. 
The crystal particles of Emulsin (I) were observed with an electron 
microscope, indicating the formation of no cubic crystals but the 
formation of complete rhombic dodecahedral particles. 
The crystal particles of Emulsion (J) were observed in the same manner, 
indicating the formation of conjugated crystals, in which the (100) 
surfaces of the cubic host crystals were conjugated with the second 
conjugate crystals which had (100) surfaces surrounded by (110) surfaces 
(FIG. 7). 
The crystal particles of Emulsion (K) were observed in the same manner, 
indicating the formation of conjugated crystals, in which the (100) 
surfaces of the cubic host crystals were conjugated with the second 
conjugate crystals surrounded by (110) surfaces (FIG. 8). 
The crystal particles of Emulsion (L) were observed in the same manner, 
indicating the formation of conjugated crystals, in which the (100) 
surfaces of the cubic host crystals were conjugated with the second 
conjugate crystals surrounded by four (110) surfaces and the overall 
appearance of each conjugated crystal particle was confirmed to have a 
shape of a rhombic dodecahedron. However, these crystal particles were 
also confirmed, like those in Emulsion (F), to have thin grooves dividing 
each of the rhombic surfaces into two parts (FIG. 9). 
Summarizing the above, it is concluded that Emulsions (D), (E), (F), (J), 
(K) and (L) are novel emulsions within the scope of the present invention, 
while Emulsions (A), (B), (C), (G), (H) and (I) fall outside the scope of 
the present invention. 
Table 1 below summarizes the properties of the emulsions formed as 
described above. 
TABLE 1 
__________________________________________________________________________ 
First (host) 
Second (conjugate) 
Crystals* 
Crystals* Shape of Resulting 
Emulsion 
(mol %) 
(mol %) Conjugate Crystal 
Remarks 
__________________________________________________________________________ 
A 70 30 
##STR6## Comparison 
B 50 50 
##STR7## Comparison 
C 30 70 
##STR8## Comparison 
D 70 30 
##STR9## Comparison 
E 70 30 
##STR10## 
Comparison 
F 70 30 
##STR11## 
Comparison 
G 50 50 
##STR12## 
Comparison 
H 50 50 
##STR13## 
Comparison 
I 50 50 
##STR14## 
Comparison 
J 30 70 
##STR15## 
Comparison 
K 30 70 
##STR16## 
Comparison 
L 30 70 
##STR17## 
Comparison 
__________________________________________________________________________ 
*Content of silver bromide in each crystal. 
EXAMPLE 2 
In the same manner as in the preparation of Emulsion (E) in Example 1, with 
the exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was 
replaced by the same molar amount of 1-phenyl-5-mercaptotetrazole, 
Emulsion (M) was prepared. Emulsion (M) was confirmed, by observation with 
an electron microscope, to have the same type of conjugated particles as 
those in Emulsion (D) described above (FIG. 10). 
In the same manner as in the preparation of Emulsion (F) in Example 1, with 
the exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was 
replaced by the same molar amount of 2-amino-5-mercapto-1,3,4-thiadiazole, 
Emulsion (N) was prepared. Emulsion (N) was confirmed, by observation with 
an electron microscope, to have the same type conjugated particles as 
those in Emulsion (D) described above (FIG. 11). 
In the same manner as in the preparation of Emulsion (F) in Example 1, with 
the exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was 
replaced by the same molar amount of 
2-methylthio-5-mercapto-1,3,4-thiadiazole, Emulsion (O) was prepared. 
Emulsion (O) was confirmed, by observation with an electron microscope, to 
have the same type of conjugated particles as those in Emulsion (F) 
described above (FIG. 12). 
In the same manner as in the preparation of Emulsion (E) in Example 1, with 
the exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was 
replaced by 0.6 g of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, Emulsion 
(P) was prepared. Emulsion (P) was confirmed, by observation with an 
electron microscope, to have conjugated particles which were an 
intermediate shape as compared to the particles in Emulsion (D) and those 
in Emulsion (E) described above (FIG. 13). 
In the same manner as in the preparation of Emulsion (E) in Example 1, with 
the exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was 
replaced by 0.4 g of 4-hydroxy-5,6-trimethylene-1,3,3a,7-tetraazaidene, 
Emulsion (Q) was prepared. Emulsion (Q) was confirmed, by observation with 
an electron microscope, to have the same type of conjugated particles as 
those in Emulsion (F) described above (FIG. 14). 
In the same manner as in the preparation of Emulsion (E) in Example 1, with 
the exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was 
replaced by 0.36 g of 
3,3'-diethyl-9,9'-(2,2-dimethyl-1,3-propano)thiadicarbocyanine iodide, 
Emulsion (R) was prepared. Emulsion (R) was confirmed, by observation with 
an electron microscope, to have the same type of conjugated particles as 
those in Emulsion (D) described above (FIG. 15). 
EXAMPLE 3 
30 g of lime-treated gelatin was added to 1,000 cc of distilled water and 
dissolved at 40.degree. C., and then the resulting solution was regulated 
to have a pH value of 4.0 with sulfuric acid, and 6.5 g of sodium chloride 
and 0.02 g of N,N'-dimethylethylenethiourea were added thereto and 
dissolved and the temperature of the resulting solution was elevated up to 
65.degree. C. A solution containing 35 g of silver nitrate dissolved in 
420 cc of distilled water and a solution containing 7.4 g of potassium 
bromide and 8.4 g of sodium chloride dissolved in 280 cc of distilled 
water were added to the previous solution over the course of 22 minutes 
and 30 seconds, while the temperature was kept at 65.degree. C., and 
dissolved. The silver halide particles formed were observed with an 
electron microscope, indicating the formation of cubic crystals with a 
length of one edge of 0.29 .mu.m. To this emulsion containing the host 
crystals were further added a solution containing 23 g of silver nitrate 
dissolved in 160 cc of distilled water and a solution containing 9.8 g of 
potassium bromide and 2.1 g of sodium chloride dissolved in 300 cc of 
distilled water over the course of 3 minutes, while the temperature was 
kept at 67.5.degree. C., and blended. 
Prior to the addition of the silver salt aqueous solution and the soluble 
halide aqueous solution in the second stage, 0.1 g of 
1-(m-methylureidophenyl)-5-mercaptotetrazole was added, to obtain Emulsion 
(S). Emulsion (S) was confirmed, by observation with an electron 
microscope, to have the same type of conjugated particles as those in 
Emulsion (J) described above (FIG. 16). 
In the same manner as in the preparation of Emulsion (S), with the 
exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was replaced 
by the same molar amount of 1-phenyl-5-mercaptotetrazole, Emulsion (T) was 
prepared. Emulsion (T) was confirmed, by observation with an electron 
microscope, to have the same type of conjugated particles as those in 
Emulsion (J) described above (FIG. 17). 
In the same manner as in the preparation of Emulsion (S), with the 
exceptionthat 1-(m-methylureidophenyl)-5-mercaptotetrazole was replaced by 
the same molar amount of 2-amino-5-mercapto-1,3,4-thidiazole, Emulsion (U) 
was prepared. Emulsion (U) was confirmed, by observation with an electron 
microscope, to have the same type of conjugated particles as those in 
Emulsion (J) described above (FIG. 18). 
In the same manner as in the preparation of Emulsion (S), with the 
exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was replaced 
by twice the molar amount of 2-methylthio-5-mercapto-1,3,4-thiadiazole, 
Emulsion (V) was prepared. Emulsion (V) was confirmed, by observation with 
an electron microscope, to have the same type of conjugated particles as 
those in Emulsion (J) described above. 
In the same manner as in the preparation of Emulsion (S), with the 
exception that 1-(me-methylureidophenyl)-5-mercaptotetrazole was replaced 
by 0.45 g of 4-hydroxy-6-methyl-1,3,3a,7-tetraazindene, Emulsion (W) was 
prepared. Emulsion (W) was confirmed, by observation with an electron 
microscope, to have conjugated particles which were of an intermediate 
shape as compared with the particles in Emulsion (J) and those in Emulsion 
(K) described above. 
In the same manner as in the preparation of Emulsion (S), with the 
exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was replaced 
by 0.3 g of 4-hydroxy-5,6-trimethylene-1,3,3a,7-tetraazaindene, Emulsion 
(X) was prepared. Emulsion (X) was confirmed, by observation with an 
electron microscope, to have the same type of conjugated particles as 
those in Emulsion (K) described above (FIG. 19). 
In the same manner as in the preparation of Emulsion (S), with the 
exception that 1-(m-methylureidophenyl)-5-mercaptotetrazole was replaced 
by 0.27 g of 
3,3'-diethyl-9,9'-(2,2-dimethyl-1,3-propano)thiadicarbocyanine iodide, 
Emulsion (Y) was prepared. Emulsion (Y) was confirmed, by observation with 
an electron microscope, to have the same type of conjugated particles as 
those in Emulsion (J) described above. 
EXAMPLE 4 
30 g of lime-treated gelatin was added to 1,000 cc of distilled water and 
dissolved at 40.degree. C. with sulfuric acid, and 6.5 g of sodium 
chloride and 0.02 g of N,N'-dimethylethylenethiourea were added thereto 
and dissolved, and the temperature of the resulting solution was elevated 
up to 65.degree. C. A solution containing 35 g of silver nitrate dissolved 
in 420 cc of distilled water and a solution containing 17.2 g of potassium 
bromide and 3.6 g of sodium chloride dissolved in 280 cc of distilled 
water were added to the previous solution over the course of 22 minutes 
and 30 seconds, while the temperature was kept at 65.degree. C., and 
blended. The silver halide particles formed were observed with an electron 
microscope, indicating the formation of cubic crystals with a length of 
one edge of 0.29 .mu.m. To the emulsion containing these host crystals was 
added 0.16 g of 1-(m-methylureidophenyl)-5-mercaptotetrazole, and then a 
solution containing 58 g of silver nitrate dissolved in 465 cc of 
distilled water and a solution of 12.2 g of potassium bromide and 14.0 g 
of sodium chloride dissolved in 275 cc of distilled water were further 
added thereto over the course of 9 minutes and 20 seconds, while the 
temperature was kept at 60.degree. C., and blended. The emulsion obtained 
was designated Emulsion (Z). Emulsion (Z) was confirmed, by observation 
with an electron microscope, to have conjugated particles which were of 
nearly the same shape as the particles in Emulsion (K) described above 
(FIG. 20). 
EXAMPLE 5 
In the preparation of Emulsion (E) in Example 1, 
1-(m-methylureidophenyl)-5-mercaptotetrazole was added in the stage where 
25%, on the basis of the silver amount, of the host crystals were formed 
to obtain Emulsion (E-1); similarly, the tetrazole compound was added in 
the stage where 60%, on the basis of the silver amount, of the host 
crystals were formed to obtain Emulsion (E-2); again, the tetrazole 
compound was added in the stage where 36% of the silver nitrate used to 
form the second crystals was consumed to obtain Emulsion (E-3); and 
finally the tetrazole compound was added in the stage where 71%, on the 
basis of the silver amount, of the second crystals were formed to obtain 
Emulsion (E-4). Each emulsion thus obtained was observed with an electron 
microscope, which indicated that the host crystals themselves had the same 
crystal shape as that of the crystals of Emulsion (I) described above, 
having no (100) surfaces, and, therefore, no conjugated particles within 
the scope of the present invention were formed in Emulsion (E-1); Emulsion 
(E-2) contained the conjugated particles of the present invention formed 
therein; Emulsion (E-3) also contained the conjugated particles of the 
present invention formed therein; and Emulsion (E-4) contained conjugated 
particles formed therein, but the particles had no definite (110) 
surfaces. 
EXAMPLE 6 
In the preparation of Emulsion (P) in Example 2, 
4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene was not added over the same 
time period, but was added concurrently with the halide solution to form 
the second silver halide crystals over the course of the same period of 
time and at a constant flow rate for the addition, to obtain Emulsion 
(P-1). Emulsion (P-1) was observed to contain particles having nearly the 
same shape as that of the particles in Emulsion (E) described above. 
EXAMPLE 7 
30 g of lime-treated gelatin was added to 1,000 cc of distilled water and 
dissolved at 40.degree. C., and then 6.5 g of sodium chloride was added 
thereto and dissolved, and the temperature of the resulting solution was 
elevated up to 52.5.degree. C. A solution containing 6.25 g of silver 
nitrate dissolved in 750 cc of distilled water and a solution containing 
21.5 g of potassium chloride dissolved in 500 cc of distilled water were 
added to the previous solution over the course of 40 minutes, while the 
temperature was kept at 52.5.degree. C., and blended. To the emulsion 
containing the thus-formed host crystals was added 
4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, and then a solution containing 
62.5 g of silver nitrate dissolved in 500 cc of distilled water and a 
solution containing 43.8 g of potassium bromide dissolved in 300 cc of 
distilled water were further added thereto over the course of 10 minutes, 
while the temperature was kept at 77.5.degree. C., and blended. The 
crystal particles formed in this emulsion, labeled Emulsion (B-1), were 
confirmed, by observation with an electron microscope, to have almost the 
same conjugated crystal shapes as those in Emulsion (P) described above 
(FIG. 21). 
30 g of lime-treated gelatin was added to 1,000 cc of distilled water and 
dissolved at 40.degree. C., and then 6.5 g of sodium chloride and 0.02 g 
of N,N'-dimethylethylenethiourea were added thereto and dissolved. 
Afterwards, the temperature of the resulting solution was elevated up to 
77.5.degree. C. Next, a solution containing 62.5 g of silver nitrate 
dissolved in 750 cc of distilled water and a solution containing 43.8 g of 
potassium bromide dissolved in 500 cc of distilled water were added to the 
previous solution over the course of 40 minutes, while the temperature was 
kept at 77.5.degree. C., and blended. To this emulsion containing the host 
crystals was added 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, and then a 
solution containing 62.5 g of silver nitrate dissolved in 500 cc of 
distilled water and a solution containing 21.5 g of potassium chloride 
dissolved in 300 cc of distilled water were further added thereto over the 
course of 10 minutes, while the temperature was kept at 52.5.degree. C., 
and blended. The crystal particles formed in this emulsion, labeled 
Emulsion (B-2), were confirmed, by observation with an electron 
microscope, to have almost the same conjugated crystal structure as those 
in Emulsion (P) described above (FIG. 22). 
The amount of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene as used in the 
preparation of these two emulsions was 0.6 g in each case. 
EXAMPLE 8 
30 g of lime-treated gelatin was added to 1,000 cc of distilled water and 
dissolved at 40.degree. C., and then the pH value of the resulting 
solution was regulated to 4.0 with sulfuric acid, 6.5 g of sodium chloride 
was added thereto and dissolved, and the temperture of the resulting 
solution was elevated up to 57.5.degree. C. Next, a solution containing 
62.5 g of silver nitrte dissolved in 750 cc of distilled water and a 
solution containing 4.4 g of potassium bromide and 19.4 g of sodium 
chloride dissolved in 500 cc of distilled water were added to the previous 
solution over the course of 40 minutes, while the temperature was kept at 
57.5.degree. C., and blended. To this emulsion containing the host 
crystals was added 0.16 g of 1-(m-methylureidophenyl)-5-mercaptotetrazole, 
and then a solution containing 62.5 g of silver nitrate dissolved in 500 
cc of distilled water and a solution containing 21.5 g of potassium 
chloride dissolved in 300 cc of distilled water were further added thereto 
over the course of 10 minutes, while the temperature was kept at 
52.5.degree. C., and blended. The crystal particles thus formed were 
conjugated particles having almost the same shape as that of the particles 
in Emulsion (D) described above. 
EXAMPLE 9 
30 g of lime-treated gelatin was added to 1,000 cc of distilled water and 
dissolved at 40.degree. C., and then 6.5 g of sodium chloride and 0.02 g 
of N,N'-dimethylethylenethiourea were added thereto and dissolved, and the 
temperature of the resulting solution was elevated up to 72.5.degree. C. 
Next, a solution containing 62.5 g of silver nitrate dissolved in 750 cc 
of distilled water and a solution containing 35.0 g of potassium bromide 
and 4.3 g of sodium chloride dissolved in 500 cc of distilled water were 
added thereto over the course of 40 minutes, while the temperature was 
kept at 72.5.degree. C., and blended. To the emulsion containing these 
host crystals was added 0.16 g of 
1-(m-methylureidophenyl)-5-mercaptotetrazole, and, further, a solution 
containing 62.5 g of silver nitrate dissolved in 500 cc of distilled water 
and a solution containing 26.3 g of potassium bromide and 8.6 g of 
potassium chloride dissolved in 300 cc of distilled water were added 
thereto over the course of 10 minutes, while the temperature was kept at 
67.5.degree. C., and blended. The crystal particles formed were conjugated 
particles having almost the same shape as those of the particles in 
Emulsion (E) described above. 
EXAMPLE 10 
Comparative Emulsion (B) and Emulsions (D) and (P) of the present invention 
were demineralized and washed with water and then chemically sensitized 
with 6 mg of sodium thiosulfate for 40 minutes at 60.degree. C. Each 
emulsion was then coated on a paper support, after gelatin had been added 
thereto, the amount of the coated silver being 0.6 g/m.sup.2, to obtain 
Samples (b), (d), (p), respectively. These samples were exposed to a white 
light of 2,800.degree. K. through a continuous wedge for 1/10 second, and 
then developed with the following black-and-white developer at 20.degree. 
C. for 3 minutes. The photographic density obtained was measured in each 
sample, and the results are in Table 2 below. 
______________________________________ 
Developer: 
______________________________________ 
Ascorbic Acid 10 g 
(p-Methyl)aminophenol 
2.4 g 
Sodium Carbonate 10 g 
Potassium Bromide 1 g 
Water to make 1 liter 
______________________________________ 
TABLE 2 
______________________________________ 
Sample Sensitivity 
Fog Remarks 
______________________________________ 
(b) 100 0.03 Comparison 
(d) 180 0.03 Invention 
(p) 195 0.03 Invention 
______________________________________ 
A relative sensitivity was used for the evaluation of the sensitivity of 
the samples, whereupon the reciprocal of the exposure required for 
obtaining a density value of (fog +0.2) in Sample (b) was 100. Table 2 
demonstrates the high sensitivity of the emulsions of the present 
invention. 
EXAMPLE 11 
The layers shown in Table 3 below were provided on a paper support, both 
surfaces of which had been laminated with polyethylene, to form a 
multilayered color print. The coating solutions were prepared as follows: 
Preparation of the Coating Solution for the First Layer 
27.2 ml of ethyl acetate and 7.9 ml of the solvent (c) were added to 19.1 g 
of the yellow coupler (a) and 4.4 g of teh color image stabilizer (b) and 
dissolved, and the resulting solution was emulsified and dispersed in 185 
ml of a 10% gelatin aqueous solution containing 8 ml of 10% sodium 
dodecylbenzenesulfonate. Additionally, the blue-sensitive sensitizing dye 
shown below was added to the silver chlorobromide emulsion (silver 
bromide: 4.0 mol%, Ag content: 70 g/kg) in an amount of 
5.0.times.10.sup.-4 mol per mol of silver. The emulsified dispersion and 
the silver chlorobromide emulsion were blended and dissolved to obtain the 
coating solution for the first layer, the gelatin concentration being 
adjusted as shown in Table 3 below. 
Preparation of Coating Solutions for the Second to Seventh Layers 
In the same manner as in the preparation of the coating solution for the 
first layer described above, coating solutions for the second to the 
seventh layers were prepared. The gelatin hardener used in each layer was 
sodium 1-oxy-3,5-dichloro-s-triazine. 
The spectral sensitizer used in each emulsion was as follows. 
Blue-Sensitive Emulsion Layer: 
##STR18## 
(added amount: 5.0.times.10.sup.-4 mol per mol of silver halide) 
Green-Sensitive Emulsion Layer: 
##STR19## 
(added amount: 4.0.times.10.sup.-4 mol per mol of silver halide) 
##STR20## 
(added amount: 7.0.times.10.sup.-5 mol per mol of silver halide) 
Red-Sensitive Emulsion Layer: 
##STR21## 
(added amount: 1.0.times.10.sup.-4 mol per mol of silver halide) 
The anti-irradiation dye used in each emulsion layer was as follows: 
Green-Sensitive Emulsion Layer: 
##STR22## 
Red-Sensitive Emulsion Layer: 
##STR23## 
The other compounds (including couplers) used in various layers as shown in 
Table 3 in the amounts shown therein were as follows: 
(a) Yellow Coupler: 
##STR24## 
(b) Color Image Stabilizer: 
##STR25## 
(c) Solvent: 
##STR26## 
(d) Color Stain Inhibitor: 
##STR27## 
(h) Ultraviolet Absorbent: 
Mixture (1:5:3 by molar ratio) of the following compounds (1), (2) and (3), 
respectively: 
##STR28## 
(i) Color Stain Inhibitor: 
##STR29## 
(j) Solvent: 
(iso C.sub.9 H.sub.18 O).sub.3 P=O 
(e) Magenta Coupler: 
##STR30## 
(f) Color Image Stabilizer: 
##STR31## 
(g) Solvent: 
Mixture (2:1 by weight ratio) of the following Compounds (1) and (2): 
##STR32## 
(k) Cyan Coupler: 
##STR33## 
(l) Color Image Stabilizer: 
Mixture (1:3:3 by molar ratio) of the following compounds (1), (2) and (3), 
respectively: 
##STR34## 
TABLE 3 
______________________________________ 
Seventh Layer: Protective Layer 
Gelatin 1.33 g/m.sup.2 
Acryl-modified polyvinyl alcohol 
0.17 g/m.sup.2 
copolymer (modification degree: 17%) 
Sixth Layer: Ultraviolet Absorbent Layer 
Gelatin 0.54 g/m.sup.2 
Ultraviolet absorbent (h) 
0.21 g/m.sup.2 
Solvent (j) 0.09 cc/m.sup.2 
Fifth Layer: Red-Sensitive Layer 
Silver chlorobromide (silver 
0.26 g (Ag)/m.sup.2 
bromide: 3.0 mol %) 
Gelatin 0.98 g/m.sup.2 
Cyan coupler (k) 0.38 g/m.sup.2 
Color image stabilizer (l) 
0.17 g/m.sup.2 
Solvent (c) 0.23 cc/m.sup.2 
Fourth Layer: Ultraviolet Absorbent Layer 
Gelatin 1.60 g/m.sup.2 
Ultraviolet absorbent (h) 
0.62 g/m.sup.2 
Color stain inhibitor (i) 
0.05 g/m.sup.2 
Solvent (j) 0.26 cc/m.sup.2 
Third Layer: Green-Sensitive Layer 
Silver chlorobromide emulsion 
0.16 g (Ag)/m.sup.2 
(chemically sensitized 
Emulsion (B), (D) or (P) in Example 1) 
Gelatin 1.80 g/m.sup.2 
Magenta coupler (e) 0.45 g/m.sup.2 
Color image stabilizer (f) 
0.20 g/m.sup.2 
Solvent (g) 0.45 cc/m.sup.2 
Second Layer: Color Stain Inhibitory Layer 
Gelatin 0.99 g/m.sup.2 
Color stain inhibitor (d) 
0.08 g/m.sup.2 
First Layer: Blue-Sensitive Layer 
Silver chlorobromide emulsion 
0.27 g (Ag)/m.sup.2 
(silver bromide: 4.0 mol %) 
Gelatin 1.86 g/m.sup.2 
Yellow coupler (a) 0.74 g/m.sup.2 
Color image stabilizer (b) 
0.17 g/m.sup.2 
Solvent (c) 0.31 cc/m.sup.2 
Support: 
Polyethylene-laminated paper (containing white 
pigment (TiO.sub.2) and bluish dye (ultramarine) in the 
polyethylene in the same side of the support as the 
first layer 
______________________________________ 
The chemically sensitized Emulsions (B), (D) and (P) were used as the 
silver chlorobromide emulsions in the green-sensitive layer of the 
material described above in Table 3 to obtain Color Print Samples (I), 
(II) and (III), respectively. 
The color print samples thus obtained were exposed by wedge exposure and 
then processed in accordance with the following procedure: 
______________________________________ 
Temperature 
Processing Step 
Time (.degree.C.) 
______________________________________ 
Color Development 45 sec 35 
Bleaching-Fixation 45 sec 35 
Rinsing 1 min 30 sec 30 
(with four-tank cascade) 
Drying 50 sec 80 
______________________________________ 
The composition of the treating solution used in each of the above 
processing steps was as follows: 
______________________________________ 
Color Developer: 
Water 800 ml 
Diethylenetriaminepentaacetic Acid 
1.0 g 
Sodium Sulfite 0.2 g 
Potassium Bromide 0.02 g 
Sodium Chloride 1.5 g 
Potassium Carbonate 30 g 
N--Ethyl-N--(.beta.-methanesulfonamidoethyl)- 
4.5 g 
3-methyl-4-aminoaniline Sulfate 
N,N--Diethylhydroxylamine 4.2 g 
4,4'-Diaminostilbene Type Brightening 
1.0 g 
Agent (Whitex 4, by Sumitomo Chemical 
Co., Ltd.) 
Water to make 1,000 ml 
KOH to adjust pH to 10.25 
Bleaching-Fixation Solution: 
Water 400 ml 
Ammonium Thiosulfate (70%) 
150 ml 
Sodium Sulfite 18 g 
Ammonium Ethylenediaminetetraacetato 
55 g 
Ferrate 
Ethylenediaminetetraacetic Acid 
5 g 
Water to make 1,000 ml 
pH 6.75 
Rinsing Solution: 
1-Hydroxyethylidene-1,1-diphosphonic 
1.5 ml 
Acid (60%) 
Nitrilotriacetic Acid 1.0 g 
Nitrilo-N,N,N--trimethylenephosphonic 
1.0 g 
Acid 
Ethylenediaminetetraacetic Acid 
0.5 g 
Ethylenediamine-N,N,N',N'--tetramethylene- 
1.0 g 
phosphonic Acid 
Bismuth Chloride (40%) 0.5 g 
Magnesium Sulfate 0.2 g 
Zinc Sulfate 0.3 g 
Ammonium Alum 0.5 g 
5-Chloro-2-methyl-4-isothiazolin-3-one 
30 mg 
2-Methyl-4-isothiazolin-3-one 
10 mg 
2-Octyl-4-isothiazolin-3-one 
10 mg 
Ethylene Glycol 1.5 g 
Sulfanylamide 0.1 g 
1,2,3-Benzotriazole 1.0 g 
Ammonium Sulfite (40%) 1.0 g 
Aqueous Ammonia (26%) 2.6 ml 
Polyvinyl Pyrrolidone 1.0 g 
Brightening Agent (4,4'-diamino- 
1.0 g 
stilbene type) 
Water to make 1,000 ml 
KOH to adjust pH to 7.0 
______________________________________ 
The results obtained are shown in Table 4 below: 
TABLE 4 
______________________________________ 
Sample Sensitivity 
Fog Remarks 
______________________________________ 
(I) 100 0.09 Comparison 
(II) 162 0.08 Invention 
(III) 182 0.08 Invention 
______________________________________ 
A relative sensitivity was used for the evaluation of the sensitivity of 
the samples, whereupon the reciprocal of the exposure required for 
obtaining a density value of (fog +0.5) in Sample (I) was 100. Table 4 
above demonstrates high sensitivity and low amount of fog formation in the 
emulsions of the present invention. 
The above examples illustrate that the silver halide photographic emulsions 
of the present invention have high sensitivity with low amount of fog 
formation. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.