JP4081544B2 - Method and apparatus for forming silver halide emulsion grains - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for forming silver halide emulsion grains, and more particularly to a technique for forming silver halide emulsion grains using a static mixing apparatus.
[0002]
[Prior art]
When forming silver halide emulsion grains for use in a silver halide light-sensitive material, there are two main steps. One is a nucleation process for forming seed grains of silver halide emulsion grains, and the other is a grain growth process for growing the seed grains formed in the nucleation process into grains having a size suitable for a photosensitive material. is there.
[0003]
First, in the nucleation process, for example, to prepare tabular grains with uniform shapes, it is necessary to increase the probability of double twins with uniform grain size distribution at the seed grain stage that is the source of tabular grains. It is. In order to grow such tabular grains, in order to regulate the growth direction, seed grains for growth formed by nucleation are added to a system in which host grains for growth exist, and Ostwald ripening is performed. It is effective to make it progress. Such seed particles are required to have a fine size and excellent monodispersibility.
[0004]
In order to form such seed particles, a silver salt aqueous solution (explained in the example of “silver nitrate aqueous solution” below) and a halogen salt aqueous solution are mixed at a very low concentration in a mixing reactor to react both solutions. If so, it is possible to form the desired twin seed particles unless the stirring or mixing conditions are too weak, but it is not industrially profitable at low concentration conditions. Therefore, in order to form seed particles or grow seed particles at an industrially profitable concentration level, a reaction under a high concentration condition is required.
[0005]
In addition, in order to stably form fine silver halide emulsion grains in the nucleation step and grain growth step, it is necessary to devise a device that does not cause nucleation and grain growth at the same time. It is desirable to use a small volume static mixing device that does not generate backflow. Here, the static mixing device refers to a mixing device having no stirring means such as a stirrer in the mixing field.
[0006]
Examples of methods for forming silver halide emulsion grains using such a static mixing device include JP-A-4-292416, JP-A-11-217217, JP-A-2000-187293, and the like. The two jets of high Re (Reynolds number) silver nitrate solution and halogen salt solution collide with each other at the intersection of very narrow pipes such as T-shaped tubes and Y-shaped tubes, and both liquids are mixed and reacted instantaneously. The mixed reaction liquid is discharged in a short time.
[0007]
[Problems to be solved by the invention]
However, in order to increase the mixing efficiency by colliding both liquids, which are high-speed turbulent flow, as in the conventional static mixing device, it is necessary to increase the speed of the jet jet. When it is increased, frictional heat is generated by liquid-liquid friction between both liquids. Since the reaction for forming silver halide emulsion grains is an exothermic reaction, when frictional heat is added to the exothermic reaction, the seed grains formed by the reaction of the silver nitrate aqueous solution and the halogen salt aqueous solution grow by Ostwald ripening. There is a drawback that the silver halide emulsion grains having fine monodispersibility are difficult to be formed due to the progress.
[0008]
In addition, high-speed turbulent jet jets are prone to cavitation, and bubbles due to cavitation tend to collect to form a gas-liquid interface in the static mixing device, resulting in nonuniform mixing and reaction. There is a disadvantage that silver halide emulsion grains having good dispersibility are difficult to form.
[0009]
Against this background, good mixing performance can be obtained even when a halogen salt aqueous solution or silver nitrate aqueous solution is ejected at low speed, and even if the concentration of the halogen salt aqueous solution and the silver nitrate aqueous solution is high, fine particles and monodisperse halogen There has been a need for a static mixing device capable of forming silver halide emulsion grains.
[0010]
The present invention has been made in view of the above circumstances, and can reduce the frictional heat at the time of mixing the silver nitrate aqueous solution and the halogen salt aqueous solution, prevent the occurrence of cavitation, and can efficiently perform the mixing reaction. It is an object of the present invention to provide a silver halide emulsion grain forming method and apparatus capable of forming a silver halide emulsion grain having fine grains and good monodispersibility because the mixing state in the mechanical mixing can be optimized. .
[0011]
In addition, the present invention can obtain a good mixing performance even when a halogen salt aqueous solution or a silver nitrate aqueous solution is ejected at a low speed. An object of the present invention is to provide a silver halide emulsion grain forming method and apparatus capable of forming silver halide emulsion grains.
[0012]
[Means for solving the problems]
In order to achieve the above object, the present invention ejects a silver salt aqueous solution and a halogen salt aqueous solution from each nozzle into a mixing chamber having a diameter larger than the diameter of the nozzle to cause a mixing reaction, and the mixed reaction solution is mixed with the mixing reaction solution. A method of forming silver halide emulsion grains by discharging from a discharge port having a diameter smaller than the chamber diameter, wherein one of the silver salt aqueous solution and the halogen salt aqueous solution is converted into a thin turbulent straight flow The other liquid is applied to the straight flow at a position before the eddy viscosity formed by jetting the straight flow from the small diameter nozzle to the large diameter mixing chamber is maximized. The one liquid and the other liquid are instantaneously mixed and reacted by being ejected as a substantially orthogonal cross flow.
[0013]
In order to achieve the above object, the present invention jets a silver salt aqueous solution and a halogen salt aqueous solution from the respective nozzles into a mixing chamber having a diameter larger than the diameter of the nozzles and causes a mixing reaction, A method of forming silver halide emulsion grains by discharging from a discharge port having a diameter smaller than that of the mixing chamber, wherein one of the silver salt aqueous solution and the halogen salt aqueous solution is moved straight in a thin film turbulent flow. The flow is ejected as a flow into the mixing chamber, and the other liquid is ejected as an orthogonal flow substantially orthogonal to the straight flow at a position before the straight flow is reduced to 1/10 or less of the maximum flow velocity. It is characterized in that the liquid and the other liquid are mixed instantaneously.
[0014]
In order to achieve the above object, the present invention provides a silver halide emulsion grain forming apparatus for forming silver halide emulsion grains by mixing and reacting an aqueous silver salt solution and an aqueous halogen salt solution with a static mixing device. The static mixing device comprises: a mixer in which a cylindrical mixing chamber for mixing and reacting the silver salt aqueous solution and the halogen salt aqueous solution is formed; and one of the silver salt aqueous solution and the halogen salt aqueous solution. A first nozzle for ejecting the liquid as a turbulent straight flow into the mixing chamber; and the other liquid of the silver salt aqueous solution and the halogen salt aqueous solution as an orthogonal flow substantially orthogonal to the straight flow into the mixing chamber. And a second nozzle positioned so as to be ejected from a position before the eddy viscosity generated in the mixing chamber is maximized by the straight flow ejected from the first nozzle, and mixed in the mixing chamber. And a discharge port for discharging the reacted reaction mixture from the mixing chamber, and the cylindrical diameter of the mixing chamber is formed larger than the diameters of the first nozzle, the second nozzle, and the discharge port. In addition, at least the first nozzle of the first nozzle and the second nozzle is formed such that the jet flow shape is a thin film.
[0015]
In order to achieve the above object, the present invention provides a silver halide emulsion grain forming apparatus for forming silver halide emulsion grains by mixing and reacting an aqueous silver salt solution and an aqueous halogen salt solution with a static mixing device. The static mixing device comprises: a mixer in which a cylindrical mixing chamber for mixing and reacting the silver salt aqueous solution and the halogen salt aqueous solution is formed; and one of the silver salt aqueous solution and the halogen salt aqueous solution. A first nozzle for ejecting the liquid as a turbulent straight flow into the mixing chamber; and the other liquid of the silver salt aqueous solution and the halogen salt aqueous solution as an orthogonal flow substantially orthogonal to the straight flow into the mixing chamber. A second nozzle positioned so as to be ejected from a position before the straight flow ejected from the first nozzle decreases to 1/10 or less of the maximum flow velocity at the time of ejection; and the mixing chamber And a discharge port for discharging the mixed reaction liquid that has been combined and reacted from the mixing chamber, and the cylindrical diameter of the mixing chamber is larger than the diameters of the first nozzle, the second nozzle, and the discharge port In addition, at least the first nozzle of the first nozzle and the second nozzle is formed such that the jet flow shape is a thin film.
[0016]
Here, in the present invention, “the other liquid is jetted into the mixing chamber as a cross flow substantially orthogonal to the straight flow” means that the cross flow is orthogonal even if the cross flow is not completely orthogonal to the straight flow. This means that any vector component may be used.
[0017]
In the present invention, the straight flow is basically one, but there may be a plurality of orthogonal flows. For example, a plurality of types of silver salt aqueous solutions having different silver salt concentrations or silver salt types (silver nitrate, silver iodide, etc.) are jetted out as a plurality of orthogonal flows with respect to one straight flow of the halogen salt aqueous solution. May be. In this case, a plurality of cross-flow nozzle positions may be provided to eject a plurality of types of silver salt aqueous solutions, or a plurality of types of silver salt aqueous solutions may be ejected from one nozzle position at the initial reaction stage, the middle reaction stage, and the final reaction stage. You may make it divide and eject in order. Accordingly, the number of first nozzles for straight flow is basically one, but there may be a plurality of second nozzles for cross flow.
[0018]
As in the conventional static mixing device, the present invention makes high-speed turbulent flow of silver salt aqueous solution and high-speed turbulent flow of halogen salt aqueous solution collide at the intersection of very narrow pipes such as T-shaped tubes and Y-shaped tubes. Focusing on the eddy viscosity, which is known as the evaluation of mixing in a turbulent flow field, rather than causing an instantaneous mixing reaction in the collision field, the halogen salt aqueous solution (or silver salt aqueous solution) A straight flow and a silver salt aqueous solution (or halogen salt aqueous solution) are added to the mixing chamber as a cross flow, and the two liquids are mixed and reacted instantaneously by utilizing the eddy viscosity formed by accompanying the straight flow. It is comprised as follows.
[0019]
In particular, according to the present invention, since the straight flow is ejected in a thin film shape, the straight flow can be slowed down. Therefore, generation of frictional heat of liquid-liquid friction due to a straight flow can be suppressed, and growth due to Ostwald ripening of the formed particles can be suppressed. In addition, since the entrained interfacial area is increased by jetting the straight flow into a thin film, good mixing performance can be obtained even when a high-concentration halogen salt aqueous solution and silver nitrate aqueous solution are used at a low jet flow velocity. It is done. When jetting a straight flow in a thin film, the cross flow is jetted so as to be substantially perpendicular to the thin film surface of the straight flow, and it is more preferable that the cross flow is also made into a thin film.
[0020]
That is, in the static mixing device, the first nozzle and the second nozzle having a smaller diameter than the cylinder diameter of the mixing chamber are provided in the mixer in which the cylindrical mixing chamber is formed so that eddy viscosity is generated in the mixing chamber. For example, an orifice in which a slit-like thin film or a fan-like thin film is formed is provided in the first nozzle that ejects a straight flow. Then, eddy viscosity is formed by ejecting liquid from a small diameter nozzle to a larger diameter mixing chamber, and pressure is applied to the mixing chamber by reducing the diameter of the discharge port. This makes it difficult for the gas-liquid interface to be formed by cavitation in the mixing chamber. The jet flow ejected from the first nozzle is ejected to a place wider than the width of the flow, thereby generating a vortex flow due to the turbulent flow, and there is an accompanying flow from the second nozzle accompanied by the vortex flow. As a result, eddy viscosity is generated, and the mixing effect can be remarkably improved. However, such an effect cannot be expected when the tube diameter does not change like the T-shaped tube and the Y-shaped tube described above.
[0021]
In addition, when eddy viscosity is formed by a straight flow in which one of the silver salt aqueous solution and the halogen salt aqueous solution is jetted from the first nozzle, the eddy viscosity is maximized at the position of the jet distance slightly away from the first nozzle. Note that the mixing efficiency of both liquids is maximized at the position of the maximum eddy viscosity, and the other liquid, the cross flow, is injected into the mixing chamber from the position before the vortex viscosity is maximized. The positional relationship between the first nozzle and the second nozzle was defined. The position where the eddy viscosity becomes maximum is obtained by conducting a simulation in advance using R-Flow, a numerical analysis software made by R-Flow, which is already commercially available in Japan as a flow analysis software, and grasping the region where the eddy viscosity appears, The center point is grasped, and a position at which the orthogonal flow as the second nozzle is added to the straight flow jet nozzle side from this point is determined.
[0022]
Further, the position where the eddy viscosity becomes maximum in the mixing chamber substantially corresponds to the position where the maximum velocity of the straight flow from the first nozzle is reduced to 1/10, so the straight flow is reduced to 1/10 or less of the maximum flow velocity. You may position a 2nd nozzle so that a crossflow may be ejected before doing.
[0023]
In order to efficiently mix the cross flow and the straight flow using eddy viscosity, the jet flow velocity at the time of cross flow ejection is equal to or less than the jet flow velocity at the time of straight flow ejection and is accompanied by a high-speed straight flow. It is preferable that a cross flow is involved in the entrained flow.
[0024]
As described above, the present invention can form silver halide emulsion grains excellent in monodispersity even when a high-concentration halogen salt aqueous solution and a silver nitrate aqueous solution are used at a low jet flow velocity.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a method and apparatus for forming silver halide emulsion grains according to the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, an example of one straight flow and one cross flow will be described.
[0026]
FIG. 1 is a diagram conceptually showing a production line 10 for a silver halide light-sensitive material equipped with a silver halide emulsion grain forming apparatus of the present invention.
[0027]
The silver halide photosensitive material production line 10 includes a nucleation step for forming fine grain nuclei of silver halide emulsion grains, and a fine grain nucleus formed in the nucleation process is brought into contact with silver halide emulsion grains for growth. And a nuclear growth process for growing fine particle nuclei. In the nucleation step, a static mixing device 12 which is a silver halide emulsion grain forming device of the present invention is disposed, and in the nucleation step, a growth tank 16 having a heating jacket 14 is disposed.
[0028]
In the static mixing device 12, the silver nitrate aqueous solution X and the halogen salt aqueous solution Y are instantaneously mixed and reacted to form a mixed reaction solution Z containing fine grain nuclei of silver halide emulsion grains and immediately sent to the nucleus growth tank 16. . The fine particle nuclei sent to the growth tank 16 are grown by Ostwald ripening while being stirred by a stirrer 18 in a solution of silver halide emulsion grains for growth. It is preferable to use the same static mixing apparatus as that used in the nucleation step for forming silver halide emulsion grains for growth in this nucleation step.
[0029]
FIG. 2 is a conceptual diagram showing the structure of the static mixing device 12 in the present invention.
[0030]
As shown in FIG. 2, the static mixing device 12 has a halogen salt in an opening on one end side of a mixer 22 in which a cylindrical mixing chamber 20 is formed in which a silver nitrate aqueous solution X and a halogen salt aqueous solution Y are mixed and reacted. A first conduit 24 for introducing the aqueous solution Y into the mixing chamber 20 is connected, and a discharge pipe 26 for the mixed reaction solution mixed and reacted in the mixing chamber 20 is connected to the other end side opening. A second conduit 28 for introducing the aqueous silver nitrate solution X into the mixing chamber 20 is connected to the side of the mixer 22 near the outlet of the first conduit 24. In this embodiment, the halogen salt aqueous solution Y is introduced from the first conduit 24 and the silver nitrate aqueous solution X is introduced from the second conduit 28. However, both solutions may be reversed. Further, if the connection position of the discharge pipe 26 is in the vicinity of the other end side of the mixer 22, the discharge pipe 26 may be connected to the side surface of the mixer 22.
[0031]
A first orifice 30 and a second orifice 32 are formed inside the distal ends of the first conduit 24 and the second conduit 28, respectively, thereby disturbing the first conduit 24 and the second conduit 28. A first nozzle 34 and a second nozzle 36 are formed for ejecting a liquid flow. As a method of drilling the first and second orifices 30 and 32 in the block-shaped orifice material 23, as a processing method of precisely opening an ejection hole of about 100 μm in the orifice material 23 of metal, ceramics, glass or the like. Known micro cutting processing, micro grinding processing, injection processing, micro electric discharge processing, LIGA method, laser processing, SPM processing and the like can be suitably used. The material of the orifice material 23 is preferably a material having good workability and a hardness close to diamond. Therefore, as materials other than diamond, those obtained by hardening various metals and metal alloys such as quenching, nitriding, and sintering can be preferably used. Ceramics can also be suitably used because of its high hardness and superior workability than diamond. In the present embodiment, an example of an orifice will be described as the throttle structure of the first nozzle 34 and the second nozzle 36. However, as long as it has a function of ejecting a turbulent liquid, the present invention is not limited to the orifice. The method can be used.
[0032]
The first conduit 24 and the second conduit 28 are provided with pressurizing means (not shown), and the halogen salt aqueous solution Y and the silver nitrate aqueous solution X are pressurized and supplied to the first and second nozzles 34 and 36. . Various means are known as pressurizing means for applying a high pressure to the liquid, and any means can be used. However, relatively easy and inexpensive means such as a plunger pump and a booster pump are available. It is preferable to use a reciprocating pump. In addition, although a high pressure cannot be generated as much as a reciprocating pump, some rotary pumps can generate a high pressure, and such a pump can be used.
[0033]
The halogen salt aqueous solution Y is jetted from the first nozzle 34 into the mixing chamber 20 as a turbulent straight flow A, and the silver nitrate aqueous solution X is jetted from the second nozzle 36 as a cross flow B substantially orthogonal to the straight flow A. The two solutions are mixed and reacted to form a mixed reaction solution Z containing silver halide emulsion grains. In this case, even if the orthogonal flow B is not completely orthogonal to the straight flow A at an angle of 90, the orthogonal flow B only needs to have an orthogonal velocity vector component as a main component. In FIG. 2, the second nozzle 36 for ejecting the cross flow B is disposed on the upper side of the mixer 22. However, the second nozzle 36 may be disposed on the lower side or on the side side of the mixer 22. May be ejected so that the orthogonal flow B is substantially orthogonal to the straight flow A.
[0034]
Such a mixing reaction involves, as schematically shown in FIG. 3, an orthogonal flow B ejected from a direction substantially orthogonal to the straight flow A in the accompanying flow accompanying the high-speed straight flow A of the turbulent flow. By using the large eddy viscosity generated by mixing the straight flow A and the cross flow B of the turbulent flow, high-performance mixing efficiency is obtained, and the mixing chamber 20 of the static mixing device 12 described above, The first and second nozzles 34 and 36 and the discharge pipe 26 are formed to have the following relationship.
[0035]
That is, it is necessary that eddy viscosity be formed in the mixing chamber 20, and the cylinder diameter D of the mixing chamber 20. ₁ Is the orifice diameter D of the first nozzle 34 ₂ The orifice diameter D of the second nozzle 36 _Three It is formed in a larger diameter than. In particular, the eddy viscosity generated by the straight flow A is important for improving the mixing efficiency, and the orifice diameter D of the first nozzle 34. ₂ Diameter D of the mixing chamber 20 with respect to ₁ Is preferably in the range of 1.1 to 50 times, more preferably in the range of 1.1 to 20 times. Further, in order to facilitate the cross flow B to be caught in the straight flow A, the jet flow velocity of the cross flow B is preferably equal to or less than the jet flow velocity of the straight flow A. Specifically, the jet flow velocity of the straight flow A The flow rate ratio of the jet flow velocity of the cross flow B with respect to is 0.05 to 0.4 times, more preferably 0.1 to 0.3 times.
[0036]
Further, the orthogonal flow B is transferred to the mixing chamber 20 at a position before the eddy viscosity C formed by the straight flow A being ejected from the first nozzle 34 having a small diameter into the mixing chamber 20 having a larger diameter is maximized. It is necessary to eject, and it is necessary to arrange the second nozzle 36 between the first nozzle 34 and the maximum position of the eddy viscosity C. Therefore, it is necessary to know the position where the eddy viscosity C is maximized, but the position of the mixing chamber 20 where the eddy viscosity C is maximized is already marketed in Japan as flow analysis software and is well known as flow analysis software. This can be grasped by performing a simulation in advance using R-Flow, a numerical analysis software manufactured by R-Flow. In this case, as can be seen from FIG. 3, the position where the eddy viscosity C is maximum has a region instead of a pin point. . Therefore, the second nozzle 36 may be positioned before the point P, but more preferably the second nozzle position is positioned so that the cross flow B can be ejected at the initial stage of formation of the eddy viscosity C.
[0037]
Incidentally, when there is no mixing chamber 20 that forms eddy viscosity C or when the positional relationship between the first nozzle 34 and the second nozzle 36 is not appropriate, the straight flow A is mixed with the orthogonal flow B added from the middle. Before mixing, a very long mixing field is required for complete mixing, and the time interval between the first mixed and the last mixed is increased and the silver halide is increased. The grain size distribution of emulsion grains increases.
[0038]
Further, when analyzed with the above numerical analysis software, the central point P of the region where the eddy viscosity C appears is related to the flow velocity of the straight flow A, and the maximum flow velocity of the straight flow A (usually the flow velocity at the first nozzle position). Is substantially equivalent to a position where 1 is reduced to 1/10. Therefore, if the position where the maximum flow velocity of the straight flow A decreases to 1/10 is calculated and the second nozzle 36 is positioned so that the orthogonal flow B can be ejected before that point, the maximum position of the eddy viscosity C is obtained. There is no need to calculate point P.
[0039]
In addition, it is necessary to secure the length L (see FIG. 2) of the mixing chamber 20 necessary for forming the maximum eddy viscosity C in the mixing chamber 20, but if it is too long, the mixed reaction solution Z is mixed with the mixing chamber 20. This tends to cause stagnation and backflow, which adversely affects the grain size and monodispersity of silver halide grains. Therefore, the length L of the mixing chamber 20 is preferably 2 to 5 times, more preferably 2 to 3 times the distance from the first nozzle 34 to the point P which is the maximum position of the eddy viscosity C.
[0040]
Further, when liquid is ejected from the first and second nozzles 34 and 36 having a small diameter into the mixing chamber 20 having a larger diameter than that at a high speed, cavitation is likely to occur, and this cavitation causes a gas-liquid interface in the mixing chamber 20. Formed to reduce mixing efficiency. Therefore, in order to increase the mixing efficiency using the eddy viscosity C, it is necessary to prevent the gas-liquid interface from being formed in the mixing chamber 20. Therefore, as shown in FIG. _Four Is squeezed by the third orifice 38 and the cylinder diameter D of the mixing chamber 20 ₁ It is necessary to perform mixing with the pressure of the mixing chamber 20 being increased. Thereby, since cavitation can be eliminated, mixing efficiency is further improved. In addition, in order to shorten the residence time in the part which does not contribute to mixing in the discharge pipe 26 as much as possible, the outlet in the mixing chamber 20 is throttled and at least the cylinder diameter D of the mixing chamber 20 ₁ It is preferable that the discharge pipe 26 having a smaller inner diameter is connected to the growth tank 16 by making it as short as possible.
[0041]
In addition, the shape of the jet flow ejected from the first nozzle 34 and the second nozzle 36 into the mixing chamber 20 is regulated by the first and second orifices 30 and 32 provided in the first and second nozzles 34 and 36, respectively. The jet shape affects the mixing performance. Accordingly, it is preferable to appropriately use an orifice that forms a jet flow shape such as a thread line shape, a conical shape, a slit shape, or a fan shape in accordance with the purpose of the mixing reaction. For example, in the case of a reaction with a very fast reaction speed on the order of milliseconds, it is necessary to eject the straight flow A and the cross flow B so that the eddy viscosity C is instantaneously maximized in the narrowest possible range. An orifice that forms a linear jet shape is preferred. Also, when the reaction rate is relatively slow, it is better to increase the entrained interface area created by the straight flow A by jetting the straight flow A and the cross flow B so that the eddy viscosity C is maximized in the widest possible range. In this case, an orifice that forms a thin jet flow shape is preferable. In the case of an intermediate reaction rate between a very high reaction rate on the order of milliseconds and a relatively low reaction rate, an orifice that forms a conical jet flow shape is preferable.
[0042]
FIGS. 4 to 7 illustrate orifices for forming the shape of each of the thread-line, conical, slit, and fan-like jets, and (a) in each figure is a view as seen from the orifice tip side. (B) is a longitudinal sectional view of the orifice, and (c) is a transverse sectional view of the orifice.
[0043]
FIG. 4 shows a first orifice 30 for ejecting the straight linear flow A into the mixing chamber 20 and is formed in a straight thread line. FIG. 5 shows a first orifice 30 for ejecting the conical straight flow A into the mixing chamber 20 and is formed in a trumpet shape having an open tip. FIG. 6 shows a first orifice 30 for ejecting the straight flow A of the thin film into the mixing chamber 20 and is formed in a rectangular slit shape. FIG. 7 shows a first orifice 30 for ejecting a straight flow A of a fan-shaped thin film into the mixing chamber 20, and the tip portion is formed with a fan-shaped diameter.
[0044]
As for the Reynolds number when the cross section of the pipe is not circular like the slit-shaped first orifice 30 shown in FIG. 6, see “Understanding of Chemical Engineering” (by Haruo Hamada, Asakura Shoten) as follows: Can be handled. That is, when S is “cross-sectional area” and lp is “length around the solid wall in contact with the fluid”, the equivalent diameter De is defined as De = 4 S / lp. Since the slit-like orifice has a closed groove structure, if the short side is a and the long side is b, lp = 2 (a + b) is indicated. Therefore, the equivalent diameter De is expressed by the following formula (1).
[0045]
[Expression 1]
De = 4 (ab) / 2 (a + b) = 2ab / (a + b) (1)
When calculating the turbulent flow expressed by the present invention, De calculated by Equation (1) is used as the equivalent circle diameter.
[0046]
Next, a method for forming silver halide emulsion grains using the static mixing device 12 configured as described above will be described.
[0047]
The halogen salt aqueous solution Y is ejected from the first nozzle 34 into the mixing chamber 20 as a turbulent straight flow A, and the straight traveling flow A is ejected from the small diameter first nozzle 34 to the large diameter mixing chamber 20. The silver nitrate aqueous solution X is approximately orthogonal to the straight flow A from the second nozzle 36 at a position before the eddy viscosity C becomes maximum or before the maximum flow velocity of the straight flow A decreases to 1/10 or less. The two solutions are instantaneously mixed and reacted by being ejected as an orthogonal flow B and entrained in the straight flow A, and the mixed reaction solution Z is discharged from the discharge pipe 26.
[0048]
In the mixing reaction using the eddy viscosity C, there are two methods for improving the mixing reactivity in the mixing chamber 20.
[0049]
The first method is a method in which the straight flow A is injected as a yarn-like high-speed flow so that the eddy viscosity C is instantaneously maximized in the narrowest possible range. For this purpose, as the first orifice 30 of the first nozzle 34 that jets the straight flow A, the first orifice 30 that forms the yarn-like jet flow of FIG. 4 may be used.
[0050]
From the viewpoint of mixing, the straight flow A is preferably a high-speed flow, but in order to control the reaction product to a desired particle size and size distribution, the reaction to the reaction of frictional heat caused by the liquid-liquid friction generated by the high-speed flow. The impact must be taken into account. As such a countermeasure, the temperature of the reaction solution is lowered in advance, or the addition pipe, the orifice part, the mixing chamber part, the discharge part are cooled in a double structure, or both are used. Is effective. Further, since the high-speed flow is determined by the ejection pressure applied according to the flow rate to be ejected and the inner diameter of the first orifice 30, the inner diameter of the first orifice 30 is made as small as possible in order to create a higher-speed flow. However, the pressure applied to the liquid must be increased. Accordingly, the wear of the first orifice 30 becomes a problem as the flow rate becomes higher, but this can be dealt with by using diamond or the like having good durability.
[0051]
The second method is a method in which the straight flow A is made into a thin-film jet flow shape and the interfacial area produced by the straight flow A is increased. For this purpose, as the first orifice 30 of the first nozzle 34 from which the straight flow A is jetted, the first orifice 30 that forms the slit-like or fan-like jet shape shown in FIGS. 6 and 7 is used. Good. In this case, it is necessary to adjust the jet flow velocity of the cross flow B so that the cross flow B does not break the thin film of the straight flow A. More preferably, the second orifice 32 of the second nozzle 36 also has a slit-like or fan-like thin-film jet flow shape like the straight flow A, as shown in FIGS. .
[0052]
Since this second method can secure a larger eddy viscosity region, good mixing performance can be obtained even if the jet flow velocity of the straight flow A is smaller than that of the yarn-like jet flow shape. it can. Accordingly, since the straight flow A can be reduced in speed, it is possible to suppress the generation of frictional heat of liquid-liquid friction due to the straight flow A. As a result, the growth of the formed grains due to Ostwald ripening can be suppressed, and more fine silver halide emulsion grains can be formed. In addition, since the flow velocity of the straight flow is reduced, the wearability of the first and second orifices 30 and 32 is improved. Therefore, it is possible to manufacture the orifices with metals, metal processed products, ceramics, etc. that have good workability. It becomes possible.
[0053]
As described above, the static mixing device 12 according to the present invention is configured based on an unconventional idea, and the following effects can be obtained by using the static mixing device 12.
[0054]
(1) By using a structure that generates eddy viscosity in the static mixing device, an optimal mixing reaction state in static mixing can be obtained, so that fine silver halide grains with good monodispersity can be formed. Can do.
[0055]
(2) Mixing reaction utilizing eddy viscosity makes it possible to obtain good mixing performance even when the jetting flow velocity of the halogen salt aqueous solution Y or the silver nitrate aqueous solution X is slowed, so that the jetting pressure can be lowered. Thereby, the ease of manufacture of an apparatus, stability, and maintainability can be improved. In particular, the material of the first and second orifices 30 and 32 can be changed to a low-priced material with good workability other than diamond.
[0056]
(3) By jetting at least a straight flow in the form of a thin film, a mixed reaction of the halogen salt aqueous solution Y and the silver nitrate aqueous solution X at a high concentration becomes possible. As a result, it is possible to form seed grains of silver halide emulsion grains and grow seed grains at a high concentration level that is industrially profitable. In particular, it is suitable for the formation of silver halide emulsion grains in a grain growth step in which a halogen salt aqueous solution Y and a silver nitrate aqueous solution X are mixed and reacted at a high concentration.
[0057]
{Circle around (4)} Since the jet speed of the halogen salt aqueous solution Y and the silver nitrate aqueous solution X can be slowed by ejecting at least a straight flow in a thin film state, generation of frictional heat due to liquid-liquid friction can be suppressed. In particular, when forming seed grains of fine grains in the nucleation step, Ostwald ripening is less likely to occur, and silver halide emulsion grains having a smaller grain size can be formed.
[0058]
【Example】
Example 1
Example 1 uses the static mixing apparatus shown in FIG. 2 to increase the jet flow velocity of the straight linear flow A to about 233 m / sec and to increase the concentration of the halogen salt aqueous solution and the silver nitrate aqueous solution. Concentration test.
[0059]
That is, the static mixing device 12 introduces a linear linear flow A into one end of a mixer 22 in which a mixing chamber 20 having a cylinder diameter of 3 mm and a length of 20 mm is formed. A first nozzle 34 having an orifice 30 was provided, and a discharge pipe 26 having a third orifice 38 having a diameter of 1.2 mmφ was connected to the other end of the mixer 22. Then, simulation is performed in advance using numerical analysis software, R-Flow, the region where the eddy viscosity C appears is grasped, the center point P (see FIG. 3) is grasped, and the first nozzle 34 side from this point P The 2nd nozzle 36 provided with the 2nd orifice 32 of 0.6 mmphi in the position of 0.5 mm from the jet nozzle of the 1st nozzle 34 was provided. As a turbulent straight flow A from the first nozzle 34, a 2.2 mol / L potassium bromide aqueous solution (containing 1% gelatin as a protective colloid and a liquid viscosity of 10 Cp) in the mixing chamber 20 at room temperature (25 ° C.). As a turbulent cross flow B, a 2.2 mol / L silver nitrate aqueous solution X was ejected from the second nozzle 36 into the mixing chamber 20 at room temperature (25 ° C.). The jet flow velocity of the straight flow A was about 233 m / sec, the jet pressure was about 30 Mpa, the jet flow velocity of the cross flow B was about 25 m / sec, and the jet pressure was about 0.27 Mpa.
[0060]
The formed silver halide emulsion grains were rapidly frozen with liquid nitrogen, and the grain size was measured with an electron microscope. As a result, the average grain size of the silver halide emulsion grains was 10.5 nm.
[0061]
Further, when the liquid temperature of the mixed reaction liquid discharged from the discharge pipe 26 was measured, it was about 7 ° C. higher than the liquid temperature of the halogen salt aqueous solution or silver nitrate aqueous solution before jetting into the mixing chamber 20 due to reaction viscosity and frictional heat. A temperature rise was confirmed.
[0062]
(Example 2)
In the second embodiment, the thin film-like straight flow A is ejected from the first nozzle 34, so that the jet velocity of the straight flow A is reduced to about 1/10 of that in the first embodiment, and the concentrations of the halogen salt aqueous solution and the silver nitrate aqueous solution are reduced. This test was reduced to about 1/2 of Example 1.
[0063]
In order to form the thin-film straight flow A, the first orifice 30 of the first nozzle 34 is formed into the slit shape of FIG. 6, and the slit-shaped orifice has a slit thickness of 0.6 mm and a slit width of 2.0 mm. In addition, the jet flow velocity of the straight flow A was set to a low speed of about 22 m / second, and the cross flow B was set to a low speed of about 15 m / second so as not to break the thin film of the straight flow A. Then, as a turbulent straight flow A from the first nozzle 34, a 1.0 mol / L potassium bromide aqueous solution (containing 1% gelatin as a protective colloid and a liquid viscosity of 10 Cp) is mixed at room temperature (25 ° C.). As a turbulent cross flow B, a 1.0 mol / L silver nitrate aqueous solution was ejected from the second nozzle 36 into the mixing chamber 20 at room temperature (25 ° C.).
[0064]
As a result, when the liquid temperature of the mixed reaction liquid discharged from the discharge pipe 26 was measured, the temperature rose only by about 1 ° C. than the liquid temperature of the halogen salt aqueous solution or silver nitrate aqueous solution before jetting into the mixing chamber 20. . The average grain size of the formed silver halide emulsion grains was 8.5 nm, which was small and very monodispersed even though the straight flow A was slow.
[0065]
(Example 3)
Example 3 is a test in which the concentrations of the halogen salt aqueous solution and the silver nitrate aqueous solution X were set to the same high concentrations as in Example 1 while maintaining the low-speed jet speed of the thin-film straight flow A of Example 2.
[0066]
That is, a 2.2 mol / L potassium bromide aqueous solution (containing 1% gelatin as a protective colloid, liquid viscosity 10 Cp) as a turbulent straight flow A from the first nozzle 34 is mixed at room temperature (25 ° C.). As a turbulent cross flow B, a 2.2 mol / L silver nitrate aqueous solution X was jetted into the mixing chamber 20 at room temperature (25 ° C.). Further, on the premise that the position of the second nozzle 36 of the cross flow B is the same as that of the second embodiment, the dimension of the slit-like orifice of the first nozzle 34 is calculated so that the eddy viscosity C becomes the maximum, and the slit-like shape is calculated. The dimensions of the orifice were such that the slit thickness was 0.58 mm and the slit width was 2.0 mm.
[0067]
As a result, when the liquid temperature of the mixed reaction liquid discharged from the discharge pipe 26 was measured, the temperature rose only by about 2 ° C. than the liquid temperature of the halogen salt aqueous solution or silver nitrate aqueous solution before jetting into the mixing chamber 20. The average grain size of the formed silver halide emulsion grains was 8.6 nm and was small and very monodispersed.
[0068]
As described above, from the results of Examples 1 to 3, silver halide emulsion grains having a sufficiently small grain size can be obtained by making the jet shape of the straight flow A into a thin slit or fan shape even at a low jet velocity. It was found that it can be formed. Further, from the results of Example 3, even when the jet flow velocity of the straight flow A is low and a high-concentration halogen salt aqueous solution and silver nitrate aqueous solution are used, the jet flow shape of the straight flow A is made into a thin slit or fan shape. It was found that sufficiently small silver halide emulsion grains can be formed.
[0069]
【The invention's effect】
As described above, according to the method and apparatus for forming silver halide emulsion grains of the present invention, the reduction of frictional heat and the occurrence of cavitation during mixing of the silver salt aqueous solution and the halogen salt aqueous solution are prevented, and the mixing reaction Can be performed efficiently, and the mixing state in static mixing can be optimized, so that silver halide emulsion grains having a small grain size and excellent monodispersibility can be formed.
[0070]
Furthermore, even if a high-concentration halogen salt aqueous solution and silver nitrate aqueous solution are used, the straight flow flow velocity is low, and the straight flow shape is made into a thin slit or fan shape, resulting in sufficiently small halogenation. Silver emulsion grains can be formed.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a production line for a silver halide light-sensitive material equipped with a silver halide emulsion grain forming apparatus of the present invention.
FIG. 2 is a conceptual diagram of a static mixing device in the silver halide emulsion grain forming device of the present invention.
FIG. 3 is a schematic diagram illustrating eddy viscosity formed in a mixing chamber of a static mixing device.
FIG. 4 is an explanatory diagram for explaining the shape of an orifice forming a yarn-like jet flow shape
FIG. 5 is an explanatory diagram for explaining the shape of an orifice forming a conical jet flow shape.
FIG. 6 is an explanatory diagram for explaining the shape of an orifice forming a slit-like jet flow shape in a thin film form
FIG. 7 is an explanatory diagram for explaining the shape of an orifice forming a fan-like jet flow shape in a thin film shape
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Silver halide photosensitive material production line, 12 ... Static mixing apparatus, 16 ... Growth tank, 20 ... Mixing chamber, 22 ... Mixer, 23 ... Orifice material, 24 ... First conduit, 26 ... Discharge pipe 28 ... second conduit, 30 ... first orifice, 32 ... second orifice, 34 ... first nozzle, 36 ... second nozzle, 38 ... third orifice, A ... straight flow, B ... cross flow , C ... Eddy viscosity, X ... Silver nitrate aqueous solution, Y ... Halogen salt aqueous solution

Claims (6)

A silver salt aqueous solution and a halogen salt aqueous solution are ejected from each nozzle into a mixing chamber having a diameter larger than the diameter of the nozzle to cause a mixing reaction, and the mixed reaction liquid is discharged from a discharge port having a diameter smaller than the diameter of the mixing chamber. A method of forming silver halide emulsion grains,
One of the silver salt aqueous solution and the halogen salt aqueous solution is jetted into the mixing chamber as a straight turbulent flow in the form of a thin film, and the straight flow is jetted from a small diameter nozzle to a large diameter mixing chamber. The one liquid and the other liquid are instantaneously mixed and reacted by ejecting the other liquid as a cross flow substantially orthogonal to the straight flow at a position before the eddy viscosity formed becomes maximum. A method for forming a silver halide emulsion grain characterized by the above. A silver salt aqueous solution and a halogen salt aqueous solution are ejected from each nozzle into a mixing chamber having a diameter larger than the diameter of the nozzle to cause a mixing reaction, and the mixed reaction liquid is discharged from a discharge port having a diameter smaller than the diameter of the mixing chamber. A method of forming silver halide emulsion grains,
One of the silver salt aqueous solution and the halogen salt aqueous solution is jetted into the mixing chamber as a straight turbulent flow in the form of a thin film, at a position before the straight flow is reduced to 1/10 or less of the maximum flow velocity, A method of forming silver halide emulsion grains, wherein the one liquid and the other liquid are instantaneously mixed by ejecting the other liquid as a cross flow substantially orthogonal to the straight flow. 3. The method for forming silver halide emulsion grains according to claim 1 or 2, wherein the straight flow in the form of a thin film has a slit shape or a fan shape. The method for forming silver halide emulsion grains according to any one of claims 1 to 3, wherein the flow velocity at the time of jetting the cross flow is equal to or less than the flow velocity at the time of jetting the straight flow. In a silver halide emulsion grain forming apparatus for forming silver halide emulsion grains by mixing and reacting a silver salt aqueous solution and a halogen salt aqueous solution with a static mixing apparatus,
The static mixing device is:
A mixer in which a cylindrical mixing chamber is formed in which the silver salt aqueous solution and the halogen salt aqueous solution are mixed and reacted;
A first nozzle that ejects one of the silver salt aqueous solution and the halogen salt aqueous solution into the mixing chamber as a turbulent straight flow;
The other liquid of the silver salt aqueous solution and the halogen salt aqueous solution is jetted into the mixing chamber as a cross flow that is substantially orthogonal to the straight flow, and into the mixing chamber by the straight flow jetted from the first nozzle. A second nozzle positioned to be ejected from a position before the generated eddy viscosity is maximized;
A discharge port for discharging the mixed reaction solution mixed and reacted in the mixing chamber from the mixing chamber;
The cylinder diameter of the mixing chamber is formed larger than the diameters of the first nozzle, the second nozzle, and the discharge port, and at least the first nozzle of the first nozzle and the second nozzle is a jet flow. An apparatus for forming silver halide emulsion grains, characterized in that the silver halide emulsion grains are formed in a thin film shape. In a silver halide emulsion grain forming apparatus for forming silver halide emulsion grains by mixing and reacting a silver salt aqueous solution and a halogen salt aqueous solution with a static mixing apparatus,
The static mixing device is:
A mixer in which a cylindrical mixing chamber is formed in which the silver salt aqueous solution and the halogen salt aqueous solution are mixed and reacted;
A first nozzle that ejects one of the silver salt aqueous solution and the halogen salt aqueous solution into the mixing chamber as a turbulent straight flow;
The other liquid of the silver salt aqueous solution and the halogen salt aqueous solution is jetted into the mixing chamber as a cross flow substantially orthogonal to the straight flow, and the straight flow jetted from the first nozzle is the maximum at the time of jetting. A second nozzle positioned to be ejected from a previous position that decreases to 1/10 or less of the flow velocity;
A discharge port for discharging the mixed reaction solution mixed and reacted in the mixing chamber from the mixing chamber;
The cylinder diameter of the mixing chamber is formed larger than the diameters of the first nozzle, the second nozzle, and the discharge port, and at least the first nozzle of the first nozzle and the second nozzle is a jet flow. An apparatus for forming silver halide emulsion grains, characterized in that the silver halide emulsion grains are formed in a thin film shape.

Images