JPH0715560B2 - Dispersion control method for photographic emulsion - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for controlling the dispersity of a photographic emulsion, and more specifically, it relates to a washing water for coagulation-precipitating emulsion when adjusting the desalting degree of the emulsion.
The present invention relates to a method for controlling the degree of dispersion of a photographic emulsion in which the degree of desalination of a desalinated emulsion is kept constant by controlling the degree of dispersion in a solvent.

In the desalting step of a photographic emulsion such as a silver halide gelatin emulsion, the desalting degree is controlled by the electric conductivity. Then, in the desalting step of the photographic emulsion by continuous centrifugation, there is a technique of controlling the flow rate of the solution so that the mixture of the emulsion and the washing water maintains a predetermined electric conductivity. Is disclosed in. (Hereinafter, the technique described in the patent publication is referred to as prior art.) According to the patent publication describing the prior art, the emulsion and the washing water are supplied to the emulsion without the need for a supply device having a strict quantitative property. Although it is said that the desalination accuracy can be improved, studies by the present inventors have revealed that the prior art has the following drawbacks. That is, in the coagulation-precipitation emulsion, gelatin, which is a hydrophilic binder, undergoes a cross-linking reaction with the coagulant to form a so-called sticky form, and the dispersibility in washing water is extremely poor. The electric conductivity is different depending on whether the waxy aggregate emulsion is sufficiently dispersed in the washing water or the gelatin solvent for storing the set and the case where the degree of dispersion is low. In addition, even if the liquid transfer amount is regulated so as to keep the electric conductivity of the liquid in the tank constant without judging whether or not the dispersion degree of the liquid in the tank is sufficient, this is merely an apparent electric It cannot be said that the objective electrical conductivity is constant, only the conductivity is constant. Further, desalting of the emulsion itself is insufficient, and there are cases in which an emulsion of constant quality cannot be obtained.

[Object of the Invention] The present invention was made based on the above findings of the present invention, and provides a means for confirming whether or not an aggregate-precipitated emulsion is sufficiently dispersed. At the same time, the concentration and the liquid amount of the finished emulsion are determined. It is an object of the present invention to clarify a method for controlling the degree of dispersion of a photographic emulsion, which can be controlled so that it can be kept constant, and which can provide an emulsion of constant quality.

SUMMARY OF THE INVENTION According to the present invention for achieving the above object, in a desalting step of a photographic emulsion by batch-type coagulation precipitation, the emulsion is coagulated-precipitated in a reaction tank, the supernatant is discharged, and then the emulsion is re-prepared. When the washing water for washing or a solvent for storing the emulsion as a set is added, the silver potential decreases as the precipitated emulsion is dispersed and it converges to the theoretical value obtained from the Nernst equation below. Utilizing the correlation between dispersed emulsion and silver potential,
It is characterized by confirming that the silver potential converges to the theoretical value to confirm that the whole amount is dispersed to form a homogeneous system.

Nernst equation EAg = EAg ° -Eref + klog [Ag ⁺ ] where EAg is the silver potential EAg ° is the silver standard electrode Eref is the reference electrode Ag ⁺ is the silver activity k is a constant determined by the temperature An example of the method of the present invention will be described with reference to the drawings.

The desalting step of the present invention is based on the so-called batch coagulation precipitation method.
That is, first, the aggregating agent 3 is added to the silver halide emulsion stretched in the reaction tank 2 equipped with the stirrer 1 and stirred (see FIG. 1 (A)). Next, the stirrer 1 is stopped and the emulsion 4 is allowed to stand until it precipitates and separates (see FIG. 1 (B)), and the supernatant 5 is discharged (see FIG. 1 (C)). Next, a certain amount of desalination cleaning water 6 is supplied and the stirrer 1
Then, the flocculation-precipitated emulsion is dispersed with the washing water 6 (see FIG. 3D). In the case where the emulsion in the above step (C) is set-preserved (being set-preserved for a long time at a low temperature of about 10 ° C. or less from preparation of the silver halide emulsion to coating on the base) As a set gel (solvent) 7, a certain amount of gelatin for dispersion is supplied and agitated by the stirrer 1 to disperse the coagulation-precipitated emulsion in the set gel (solvent) 7 (see (D) 'in the same figure). .

In the present invention, the means for managing the degree of dispersion in the above step (D) or (D) 'is as follows.

The dispersion degree control method of the present invention is based on the following experiment. That is,
The present inventors have found that there is a correlation between the undispersed emulsion and the silver potential value EAg, and as the precipitated emulsion is dispersed, the EAg value decreases and converges to the theoretical amount.

Here, the theoretical value is the Nernst'se formula (Nernst'se
q.), that is, the value (k: constant term determined by temperature) obtained from EAg = EAg ° -Eref + klog [Ag ⁺ ]. The present inventors investigated the relationship between the amount of undispersed emulsion and the silver potential. The result was as shown in FIG. From this result, it was found that the EAg value can be confirmed when the whole amount was dispersed and a homogeneous system was obtained.

In FIG. 2, in the undispersed emulsion amount ratio m / m ₀ , m ₀ represents the amount of the residual precipitation emulsion in the stirrer 1 after draining in the above (D) or (D) ′, and m is the amount of the dispersed emulsion = m _0- amount of undispersed emulsion.

This experimental result shows that the EAg value can control the dispersity of the precipitated emulsion. The present invention is based on the findings obtained by this experiment. The EAg value for controlling the degree of dispersion in this way can be detected by the EAg value detection unit 8 provided in the reaction tank 2.

If it is judged by the dispersion management method of the present invention that the amount of undispersed emulsion is not present, the liquid in the reaction vessel 2 can be treated as a homogeneous system, and thereafter, the same method as the above-mentioned prior art can be used. The concentration and volume of the emulsion can be adjusted. That is, EAg is continuously detected by the detection unit 8, and the supply amount of the wash water 6 or the set gel (solvent) 7 is regulated by the flow rate control valve 10 regulated by the controller 9 so that the desired desalination degree is obtained. It may be adjusted (see (E) in the figure). In this adjusting method, if the desired desalination degree cannot be obtained even with a full amount of the washing water 6 in the reaction tank 2, the steps from (A) may be repeated. In other words, if the desired degree of desalination is obtained in (E), the process proceeds to the coating step which is the next step, while the desired degree of desalination is supplied even when the reaction tank 2 is supplied with the washing water 6 that is full. If is not obtained, it may be transferred to the step (A). Thus, in the case of the present invention, it is possible to obtain a desired degree of desalination by the batch method. When the step (D) 'is completed, the process is moved to the set storing process. Also,
When the desired degree of desalting is obtained in the step (E), the step is moved to the sensitizing step which is the next step.

According to the present invention, in the desalting step of a photographic emulsion by palindromic coagulation precipitation, the emulsion is coagulated and precipitated in the reaction tank, the supernatant liquid is discharged, and the washing water for washing the emulsion again is used. When the solvent is added to store the emulsion as a set, the degree of dispersion of the precipitated emulsion in the washing water and the solvent is controlled by the silver potential or the electric conductivity, so that the quality variation in the case of the prior art is large. It can be suppressed to the width, especially the emulsion density (EAg
Value) can be suppressed to ± 0 mV, and the amount of emulsion liquid can be suppressed to within ± 0.5%.

[Brief description of drawings]

FIG. 1 is a process chart showing an example of the present invention, and FIG. 2 is a graph showing the relationship between the amount of undispersed emulsion and the EAg value. 1 is a stirrer, 2 is a reaction tank, 3 is a coagulant, 4 is an emulsion, 5 is a supernatant, 6 is washing water, 7 is a set gel (solvent), 8 is a detection part, 9 is a controller, 10 is Control valves are shown respectively.

Claims (1)

[Claims] 1. In a desalting step of a photographic emulsion by batch-type coagulation precipitation, the emulsion is coagulated and precipitated in a reaction tank, the supernatant liquid is discharged, and washing water or an emulsion for washing the emulsion is again used. When adding a solvent for set storage, use the correlation between the undispersed emulsion and the silver potential that the silver potential decreases as the precipitate emulsion is dispersed and converges to the theoretical value obtained from the Nernst equation below. Then, it is confirmed by confirming that the silver potential converges to the theoretical value that the whole amount is dispersed to form a homogeneous system. Nernst equation EAg = EAg ° -Eref + klog [Ag ⁺ ] where EAg is the silver potential EAg ° is the silver standard electrode Eref is the reference electrode Ag ⁺ is the silver activity k is a constant determined by temperature