JP2624589B2 - Equipment for manufacturing silver halide photographic emulsions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a silver halide photographic emulsion. More specifically, the present invention relates to a silver halide photographic emulsion manufacturing apparatus capable of manufacturing silver halide grains having a narrow grain size distribution and uniform grain crystallization even in mass production.

[0002]

2. Description of the Related Art Generally, silver halide grains are produced by reacting an aqueous silver salt solution and an aqueous halide solution in a colloid aqueous solution in a reaction vessel. In a reaction solution, a protective colloid such as gelatin and an aqueous solution of a halogen salt are put, and an aqueous solution of a silver salt is added thereto for a certain time. A double-jet method in which addition is performed for a certain time is known. Comparing the two, the double jet method is advantageous in that silver halide grains having a narrow grain size distribution can be obtained, and further, as the grains grow, the halide composition can be freely changed. US Pat. No. 3,415,65 discloses an apparatus for producing a silver halide photographic emulsion by the double jet method.
0, British Patent 1,323,464,
U.S. Pat. No. 3,692,283, Japanese Patent Publication No. 55-55
A technique disclosed in Japanese Patent No. 10545 is known.

[0003] These apparatuses have been devised in order to create uniform reaction conditions between an aqueous silver salt solution and an aqueous halide salt solution and to simplify the production process of a silver halide photographic emulsion. The shape, the method of supplying the aqueous solution of the halogen salt and the aqueous solution of the silver salt and the like are improved. However, with these techniques, it is difficult to produce silver halide grains having a sufficiently narrow grain size distribution and a uniform grain habit due to defects such as lack of uniformity of the circulating flow of the liquid in the entire reaction vessel. . On the other hand, Japanese Patent Application Laid-Open No. 57-925
No. 24 discloses an apparatus for producing a silver halide emulsion in which the uniformity of the circulating flow of the liquid in the entire reaction vessel is improved by converting the discharge flow from the stirring blade into a flow mainly composed of vertical flow by a liquid flow regulating plate. Have been. However, even with this technique, the circulation of the liquid is not yet sufficient, and silver halide grains having a sufficiently narrow grain size distribution cannot be produced.

[0004] Japanese Utility Model Publication No. 3-20829 discloses an apparatus capable of producing a silver halide grain having an improved liquid circulation property, a narrow grain size distribution, and a uniform grain habit. Tokuho 2 as a device that can be manufactured
Although the objectives have been attained by the silver halide photographic emulsion manufacturing apparatus disclosed in Japanese Patent Application Laid-Open No. -60166, when a larger amount of silver halide photographic emulsion is manufactured (for example, a reaction vessel of 1000 liters or more). For example, when the aqueous solution of the halogen salt and the aqueous solution of the silver salt are supplied to the mixing vessel at a flow rate of 4000 cc / min or more), the apparatus described in Japanese Patent Publication No. 2-60166 may be used. Since the size and the rotation speed of the stirring blade greatly deviate from appropriate ranges and are difficult to manufacture mechanically, a sufficient circulating flow was not obtained, and desired silver halide grains could not be obtained.

[Problems to be solved by the invention]

An object of the present invention is to provide an apparatus capable of producing a large amount of silver halide grains having a narrow grain size distribution and a uniform grain habit.

[0006]

The object of the present invention is to provide an apparatus for producing silver halide grains by a double jet method, wherein a stirring blade which generates a liquid flow in a reaction vessel in a centrifugal direction or obliquely downward is provided in a reaction vessel. A fixed cylinder having a diameter of 1.1 to 1.5 times the diameter of the stirring blade, and a liquid cylinder disposed at a position apart from the upper end of the cylinder to restrict the liquid flow in the downward direction of the rotation axis of the stirring blade, and A liquid flow regulating plate having a diameter substantially the same as that of the cylinder for suppressing air mixing, and an injection nozzle which is located below the stirring blade and discharges a halogen salt aqueous solution and a silver salt aqueous solution upward. This is a silver halide photographic emulsion manufacturing device. The diameter of the stirring blade is 20% of the diameter of the reaction vessel.
To 30% with a silver halide photographic emulsion manufacturing apparatus.

[0007]

FIG. 1 is a schematic diagram showing one embodiment of the present invention. For convenience, a perspective view is shown around the stirring blade. Reference numeral 1 denotes a reaction vessel which is previously filled with a protective colloid aqueous solution, and the liquid level of the aqueous solution is filled at least above the stirring blade 3, more preferably above the liquid flow regulating plate 5. In the present invention, a stirring blade 3 is used, such as a pitched turbine type or a pitched paddle type, which generates a liquid flow which is discharged in a centrifugal direction or obliquely downward with respect to the blade by rotating.
Focusing on the liquid supply side to the stirring blade 3, a sharp downward flow from above to the stirring blade 3 along the rotation axis can be observed. If the liquid flow regulating plate 5 shown in FIG. 1 does not exist, the above-mentioned rapid downward flow makes the liquid surface near the rotation axis concave, causing a large amount of air to be mixed into the liquid and causing a lot of foaming.
Bubbling significantly impairs the formation or growth of uniform silver halide grains in the production of silver halide photographic emulsions, and is undesirable from the viewpoint of emulsion yield.
By disposing the liquid flow regulating plate 5 as in the present invention, it is possible to prevent the liquid surface near the rotating shaft from being dented and to suppress foaming. As a result, a liquid flow from the radial direction to the rotation axis is formed on the lower surface side of the liquid flow regulating plate 5. This means that, as in the present invention, the silver halide aqueous solution and the halogen salt aqueous solution are continuously injected, and the resulting mixture is stirred and mixed. Then, during the growth process of the recycle type silver halide grains, in which the silver salt aqueous solution and the halogen salt aqueous solution are again subjected to stirring and mixing by the liquid circulation in the reaction vessel, the recycling cycle is shortened and the inter-particle recycling is performed. The effect of reducing the difference in period and uniformly promoting particle growth is obtained.

On the other hand, an upward flow accompanied by rotation along the rotation axis from the bottom of the reaction vessel is also observed near the rotation axis immediately below the stirring blade. Reference numerals 2 and 2 'denote injection nozzles for continuously injecting the silver salt aqueous solution and the halogen salt aqueous solution, which are opened in the direction facing the stirring blade 3, so that when injected, the flow velocity toward the stirring blade 3 It is provided to have components. The flow velocity component and the upward flow with rotation along the rotation axis from the bottom of the reaction vessel are synergized, and the silver salt aqueous solution and the halogen salt aqueous solution injected from the nozzles 2 and 2 ′ are formed by the protective colloid aqueous solution. Simultaneously with the dilution, the mixture is instantaneously mixed and reacted by the upward flow with rotation to produce silver halide grains. After the silver halide grains reach the stirring blades, they are discharged in a horizontal centrifugal direction or obliquely downward with respect to the blades, and reach the above-described recycling movement.

In the case of using a round-bottomed mixing vessel having a symmetrical shape with respect to the vertical plane as shown in this embodiment, when the liquid is rotated and stirred, a phenomenon in which the liquids rotate only monotonously and are difficult to mix with each other. As a method of avoiding this, it is known to use a baffle plate 7 as shown in FIG. 1 and this is also used in the present invention, but the upstream liquid surface of the liquid flow rotating around the baffle plate becomes convex. Since the downstream liquid surface is concave, foaming is forced. When a rotation speed sufficient to form uniform silver halide grains is given, the above-mentioned concave state of the downstream liquid surface causes a remarkable aeration phenomenon and promotes foaming. In the present invention, foaming could be suppressed by installing the cylinder 4 shown in FIG. 1 around the stirring blade. That is, most of the liquid discharged from the stirring blade (which fluctuates depending on the inclination of the stirring blade used) first flows around the inside of the cylinder 4 and then is discharged from the lower side and the upper side of the cylinder 4, so that the baffle plate Is not so high as to cause the above-described air mixing phenomenon.

In the production of silver halide photographic emulsions, the setting of the discharge amount of the stirring blade is an important factor. In the present invention, as a result of repeating many experiments, a general pitched turbine blade or a pitched paddle type stirring blade was obtained. When a blade is used, the diameter of the stirring blade is set to 20% to 30% of the mixing vessel, and
0 rpm or more and 600 rpm or less, preferably 500 rpm
When the diameter of the cylinder was 1.1 to 1.5 times the diameter of the stirring blade by applying a rotation of not more than m, desired silver halide grains were obtained and foaming could be suppressed. When the present invention is applied to the so-called double jet method and the controlled double jet method, the reaction between the aqueous silver salt solution and the aqueous silver salt solution can be performed quickly and completely. By keeping the amount of addition substantially equal, it is possible to relatively easily maintain the silver ion concentration in the dispersion (the protective colloid solution containing suspended silver halide particles) at a preset value. It has a very great advantage in the production of silver halide photographic emulsions. In the present invention, in addition to fine adjustment of the relative positions of the cylinder and the liquid flow regulating plate with respect to the stirring blade by raising and lowering the support rod 6 by an elevating device (not shown) installed above the reaction vessel, cleaning is also possible. It is clear that it works effectively and can be easily realized by well-known techniques.

[0011]

EXPERIMENTAL EXAMPLES The effects of the present invention will be illustrated by specific experimental examples.

The following three types of solutions were prepared. Solution [A] Gelatin 14.0 Kg NaCl 250 g Add water to finish to 240.0 Kg Solution [B] NaCl 27.0 Kg Add water to finish to 255.0 Kg Solution [C] AgNO3 70.0 kg Water In addition, FIG. 1 shows a manufacturing apparatus for finishing to 255.0 kg. The solution [A] is dissolved in a dissolution equipment (not shown) and then dissolved in a reaction vessel (round bottom cylindrical type: diameter 110).
0 mm), and while maintaining the temperature at 40 ° C., the solutions [B] and [C], which were kept at 40 ° C. in separate containers, were separately supplied at a constant flow rate (5000 g / mi) from the nozzle.
Injection was continued for 90 minutes in n). The position of the nozzle was symmetric with respect to the center axis of the reaction vessel, the distance between the nozzles at the nozzle opening was 80 mm, and the distance from the bottom of the reaction vessel to the nozzle opening was 100 mm. The inner diameter of each nozzle was 14 mm. The stirring blade is 45mm in diameter 300mm
Stirring was performed at 400 rpm using a pitched turbine blade having a blade size of 75 mm * 60 mm having an inclination of ゜. The stirring blade was disposed at a position where the distance between the lower end and the bottom surface of the reaction vessel was 180 mm. The cylinder had an inner diameter of 370 mm and a depth of 150 mm, and was placed at a position concentric with the stirring blade and at a distance of 150 mm between the lower end of the cylinder and the bottom surface of the reaction vessel. The liquid flow regulating plate is a circular plate having a diameter of 400 mm and is 50 m from the upper end of the cylinder.
m. A plate having a width of 110 mm and a length from the upper end of the reaction vessel to the vicinity of the bottom was uniformly disposed at four places on the circumference of the reaction vessel as a baffle plate.
On the other hand, as a comparative experiment-1, an experiment in which the cylinder and the liquid flow regulating plate were removed under the conditions of the above-mentioned experimental example was performed, and the apparatus shown in the above-mentioned JP-B-2-60166 was used on the same scale as a comparative experiment-2. Each experiment was performed.

The silver halide grains thus obtained were measured for the average grain size, the standard deviation, and the number of irregularly shaped grains by an electron micrograph. Table 1 shows the results.

[Table 1]

The irregular shaped particles in the comparative experiment were mainly coarse particles. Regarding the state of foaming, in the case of the present invention, 9
Immediately after the completion of the mixing time of 0 minutes, approximately 80 mm from the liquid level
Although the subsequent washing and desalting process could be carried out without any trouble to the extent that foaming was observed, in Comparative Experiment 1, foaming of 500 mm or more from the liquid surface was recognized, and significant foaming into the liquid was observed. Contamination was confirmed, and the subsequent washing and desalting step could not be carried out completely. In Comparative Experiment-2, 300
mm or more was observed, and the mixing of bubbles into the liquid was more remarkable than in Comparative Experiment 1, and the subsequent washing and desalting step could not be carried out completely.

【The invention's effect】

As apparent from the above description, the following effects can be obtained by the present invention. (1) Even in a large scale of 1000 liters or more, which is on the order of one order of magnitude higher, conventional silver halide grains having a uniform crystal habit can be produced by preventing the occurrence of irregularly shaped silver halide grains without foaming problems. The cost can be reduced, and a large amount of emulsions having the same photographic characteristics can be obtained at the same time. (2) Since silver halide having a narrow particle size distribution can be produced, photographic characteristics can be improved, and in particular, silver can be saved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Nozzle 2 'nozzle 3 Stirrer blade 4 Cylinder 5 Liquid flow regulating plate 6 Support rod 7 Baffle plate

Claims (2)

(57) [Claims] In an apparatus for producing silver halide grains by a double jet method, a stirring blade for producing a liquid flow in a reaction vessel in a centrifugal direction or obliquely downward of a blade, and a diameter of the stirring blade fixed around the stirring blade. A cylinder having a diameter of 1.1 to 1.5 times, and the cylinder arranged at a position apart from the upper end of the cylinder to regulate a liquid flow in a downward direction of a rotating shaft of the stirring blade and to suppress air mixing from a liquid surface. An apparatus for producing a silver halide photographic emulsion, comprising: a liquid flow regulating plate having a diameter substantially the same as that of a stirring blade; and an injection nozzle which is located below the stirring blade and discharges an aqueous solution of a halogen salt and an aqueous solution of a silver salt upward. 2. The apparatus according to claim 1, wherein the diameter of the stirring blade is 20% to 30% of the diameter of the reaction vessel.