JPS5967534A - Method and apparatus for manufacturing photographic silver halide emulsion - Google Patents

Abstract

PURPOSE:To carry out rapid coagulation and precipitation without breaking a reaction product by uniformly adding a coagulant to a silver halide emulsion while stirring the emulsion, and carrying out rapid stirring when the coagulant is added and slow stirring during the coagulation of particles. CONSTITUTION:A coagulant is mixed with emulsion particles by stirring the emulsion in vessel by uniform force all over the inside of the vessel. For example, using hollow blades 17 rapid stirring is carried out when the coagulant is added, and slow stirring is carried out during the coagulation of particles after finishing the reaction. The coagulant is added to the silver halide emulsion in the mixing vessel so that it is uniformly distributed, the emulsion is stirred by uniform force all over the inside of the vessel, and the stirring is made rapid when the coagulant is added and slow during the reaction, so the uniform reaction of emulsion particles with the coagulant can be allowed to proceed even at a high reaction rate. Since a reaction product is not broken, particles are rapidly coagulated and precipitated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing a silver halide photographic emulsion, and is particularly characterized by the addition of a flocculant in the desalting step, the stirring means, and the stirring operation.

In producing silver halide photographic emulsions, after producing silver halide emulsion grains by reacting silver waves and alkali halide liquid in the presence of gelatin, an important step is to remove excess salt produced by the reaction. There is a process. A flocculation method is generally adopted for this desalting step. In this flocculation method, a suitable flocculant is added to a silver halogenide emulsion, the silver halogenide emulsion grains are coagulated and precipitated together with gelatin, and the resulting grains are separated from a supernatant liquid containing salt. For desalting, conventionally, the flocculant was added from the surface of the emulsion through a supply pipe 2 provided at the top of the mixing tank 1, as shown in Figure 1.

However, since the reaction between emulsion grains and flocculant is fast, and emulsion grains have many reactive groups with flocculant, most of these reactions end near the surface of the emulsion, and further reactions occur. In order to proceed, a large amount of flocculant had to be added. However, since most flocculants exhibit undesirable side effects in terms of photographic performance, it has not been desirable to increase the amount of flocculants.

However, if the addition to the liquid surface of the emulsion is carried out by dispersion, the flocculant will be dispersed and reactions will occur throughout the liquid surface, but in systems with large density differences, as long as it is surface addition, mixing will be insufficient. However, even in such a case, when uniform mixing is desired, addition using a stick mixer or pipeline addition is effective. However, in the case of these addition methods, it is difficult to repeat the operation two or more times in one unit, and it cannot be said that it is suitable as a manufacturing system.

Furthermore, in the past, the emulsion and the flocculant added thereto were mixed using a single stirrer 3 installed in the mixing tank 1, and the blades of the fingers/push plate 3 had a blade diameter/tank diameter. It was small, less than 0.3, and it was necessary to rotate the stirring rod 3 at high speed in order to improve the fluidity of the emulsion in the tank.

Therefore, there is a problem in that most of the force applied to the emulsion in the tank is concentrated near the stirrer 3, and the reaction products with weak binding strength are destroyed in the vicinity of the stirrer. moreover,
In the conventional case, stirring was always carried out at the same stirring speed despite the differences in the processes of reaction and aggregation.
The reaction products are not destroyed even during aggregation due to mutual collision, which causes a significant reduction in coagulation and precipitation of emulsion grains.

This invention is intended to solve the various problems mentioned above.
While stirring the silver halide emulsion with uniform force throughout the tank, the flocculant is added so as to be uniformly distributed in the emulsion. Rapid stirring is performed when adding the flocculant, and slow stirring is performed when grains are agglomerated. Disclosed is a method for producing a silver halide photographic emulsion in which coagulation and precipitation can be rapidly carried out without increasing the amount of coagulant and without destroying reaction products, and an apparatus for carrying out the method. is intended to provide.

Next, the present invention will be explained with reference to the drawings from FIG. 2 onwards.

When desalting a silver halide emulsion, first, a flocculant is added to the emulsion in the mixing tank 10 so as to be evenly distributed. This flocculant is added to the deep layer of the emulsion.

This is carried out using a dispersion/addition device 11 having a plurality of discharge ports in the middle layer portion and the surface layer portion (including the liquid surface). The dispersion addition device Mll is provided with two or more supply pipes 12a, 12b as shown in the second diagram, and the supply pipes 12a, 1
Even if the discharge ports 12a' and 12h' at the lower end of the supply pipe 2b are designed to allow the addition of a flocculant into the emulsion, two or more discharge ports may be provided on the side of one supply pipe 12a as shown in the third figure. 12a' and 12b' may be provided so that the flocculant can be added in a dispersed manner, or other types may be used.

When the flocculant is added, finger mixing is performed to promote the reaction between the flocculant and the emulsion particles, and also after the addition is completed to promote aggregation due to mutual collision of the reaction products. This stirring and mixing requires stirring the emulsion with uniform force throughout the tank.

This invention comprises the flocculant dispersion and addition device 11 shown in FIGS. 2 and 3 above, the agitation 113a shown in FIGS. 4 and 5,
13b, 13c, and 14 may be simply used in combination in the same mixing tank 1 (the embodiment in this case is not shown), but it is most desirable to use the combination shown in FIGS. 6 and 7. As shown, the stirring mode also serves as a dispersion addition device (hereinafter simply referred to as the stirring addition device).

1 shown in Figure 6. The stirring/adding device 15 includes a hollow tube 16 provided with a hollow blade body 17, and a flocculant discharge port 18 provided at the outer end of the blade body 17, which is distributed at a plurality of locations in the tank 10. (corresponds to the combination of Figures 2 and 4)
. The finger press addition device 15' shown in FIG.
A hollow wing body 17' in the shape of a letter is provided, and a plurality of flocculant discharge ports 18' are provided at the outer edge of the wing body 17' (corresponding to the combination of FIG. 3 and FIG. 5). ). These Figure 6.

The finger addition devices 15 and 15' shown in FIG. 7 stir the emulsion with uniform force throughout the tank by rotating the blades 17 and 17', and feed the emulsion through the hollow tubes 16 and 16/. A discharge port 18 provided with a flocculant in the blade body 17, 17',
18' is designed so that it can be evenly distributed in the emulsion layer.

Therefore, the stirrer and the shield/stirring addition device 15°15'
Wing body 17,1? 'When adding a flocculant, rapid stirring is performed to quickly mix the emulsion particles and flocculant to make the reaction uniform, while slow stirring is performed when the particles are agglomerated after the reaction is completed to reduce the bonding strength. By frequently destroying weak reaction products, the probability of collision between the reaction products is increased, and large flocs can be formed to quickly precipitate.

Embodiment Now, the method of this invention is shown in FIG. 6, 1. When the coagulation and sedimentation rate of particles was measured using the apparatus shown in FIG. 7 and when using the conventional method, the results shown in the following table were obtained.

For reference, the following table shows the conventional stirring method using finger pressure.
When operating as in the present invention, a comparison is made including the case where the stirring method used in the present invention is used but no liquid separation is added (FIGS. 4 and 5).

(d/D - Stirring blade diameter/tank diameter) As described above, the present invention is capable of adding a flocculant to the silver halogenide emulsion in the mixing tank so as to uniformly distribute it, and adding it uniformly throughout the tank. Stirring is done by force with fingers, and the stirring is done quickly when adding the flocculant and slowly when reacting, so even if the reaction between the emulsion particles and the flocculant is rapid, a uniform reaction can occur. . Therefore, there is no need to increase the amount of flocculant as in the past, and the force during stirring is not locally concentrated and does not destroy the reaction product, so particles coagulate and precipitate as shown in the table above. This has the excellent effect of being carried out quickly.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a device for carrying out the conventional method, Figures 2 and 3 are
The figure is a sectional view showing the dispersion addition device, FIGS. 4 and 5 are sectional views showing the stirring mode, and FIGS. FIG. 7 is a cross-sectional view of a preferred apparatus for practicing the invention. 10... Mixing tank, 11... Dispersion addition device. 13a, 13b, 13c, 14... Umaki Tsuki. 15, 15'...Agitating and dispersing device. Patent applicant Konishiroku Photo Industry Co., Ltd. Figure 1 2 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (6)

[Claims] (1) While stirring the silver halogenide emulsion with uniform force throughout the tank, add the emulsion so as to distribute it uniformly,
A method for producing a silver halide photographic emulsion, characterized in that rapid stirring is carried out when the aggregating agent is added, and slow stirring is carried out when grains are agglomerated. (2) @Note: The method for producing a silver halide photographic emulsion according to claim 1, which is carried out by stirring dispersedly at a plurality of locations in a tank. (3) The method for producing a silver halide photographic emulsion according to claim 1, wherein the stirring is performed using fingers with a blade diameter/tank diameter of 0.3 to 0.9 mm. (4) The addition of the flocculant into the emulsion liquid is carried out by a fractional addition device having a plurality of discharge ports.
A method for producing a silver halogenide photographic emulsion according to items 1 to 3. (5) The method for producing a silver halide photographic emulsion according to any one of claims 2 to 4, wherein the stirrer also serves as a dispersion adding device. (6) Equipped with a stirrer that can uniformly apply force to the fluid throughout the tank and a dispersion and addition device that can evenly distribute the additive to the fluid in the tank, and the stirring rod rapidly stirs when adding the additive. An apparatus for producing a silver halide photographic emulsion, which is capable of performing the following steps and performing slow stirring during agglomeration of grains.