JPH08136499A - Silver or halogen ion concentration measuring method and apparatus - Google Patents

Abstract

PURPOSE: To provide a silver or halogen ion concentration measuring method and apparatus in which temperature alteration of a reference electrode is prevented, an indication electrode is thus measured precisely, the silver of halogen ion concentration in a silver halide photographic emulsion is consequently measured instantly with high reproducibility, and in which the reaction situation at the time of silver halide crystal formation is traced precisely. CONSTITUTION: A silver or halogen ion concentration measuring apparatus is a sensor system to detect electrode potential relating to the degree of silver or halogen ion activity in an aqueous gelatin solution 1 containing a silver halide crysta. A reference electrode 2 to become a potential measuring standard is not put directly in the object solution 1 for measurement but in a temperature keeping bath whose temperature is controlled to be constant at high accuracy within ±0.5 deg.C by a temperature constant bath and which is made of vinyl chloride resin or acrylic resin or coated with an insulating coating of such as a Teflon coating. The potential is measured by electrically communicating the object solution 1 for measurement and the reference electrode 2 through a salt bridge 4, immersing only one end part of an indicating electrode 5 in the object solution 1 for measurement through a ceramic having fine pores, and connecting the reference electrode and the other end part of the indicating electrode 5 in a potentiometer 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the concentration of silver or halogen ions in a silver halide photographic emulsion during or after its formation.

[0002]

BACKGROUND OF THE INVENTION Controlling the silver or halogen ion concentration during or after the formation of conventional silver halide photographic emulsions has been
It is essential to obtain the desired photographic properties, and the reference and indicator electrodes for the above purposes are used by direct insertion into a precipitation vessel containing an aqueous gelatin solution in which an aqueous solution of a halogen salt and an aqueous solution of silver nitrate react. Has been widely practiced. The relationship between silver or halogen ion concentration and electrode potential is described in "The Theory of the Photographic Process.
edition or Fourth edition. (Macmillan Publishi
ng Co. Inc) ”. The silver or halogen ion concentration is represented by pAg and pX, respectively, and defined by the equations (1) and (2). ^{pAg = -log [Ag +] ···} (1) pX = -log [X -] ···· (2) where [Ag ^+] silver ion activity. [X ⁻ ] represents the activity of a halogen ion (Br ⁻ or Cl ⁻ or I ⁻ ). The electrode potentials E _Ag and E _X related to the silver or halogen ion activity in the silver halide crystal are expressed as follows.

[0003]

[Equation 1]

In practical silver halide emulsions, the halide salt is often excessive, and the silver supporting electrode is covered with a silver halide layer and saturated with the silver halide salt. Therefore, the activity of silver and halogen ions on the surface of the electrode is related by the equation (4). [Ag ⁺ ] [X ⁻ ] = Ksp (4) Here, Ksp represents the solubility product of silver halide. That is, the silver / silver silver halide electrode is essentially equivalent to a silver electrode in which the silver ion activity is dominated by the halogen ion activity in the solution. Therefore, Ex is represented by the formula (5), but the indicator electrode in the silver halide emulsion shows the same potential because the emulsion solution is in equilibrium with the silver halide crystals.

[0005]

[Equation 2]

[0006] Measurement of the electrode potential E can be performed by detecting a potential difference set the potential E _R and the battery system of the comparative electrodes for generating a reference potential, pAg or pX
The relationship between and can be expressed by the following equation.

[0007]

(Equation 3)

Therefore, by measuring the indicator electrode potential E, the states of pAg and pX in the silver halide photographic emulsion can be grasped. However, if a reference electrode for measuring the potential is placed in the liquid to be measured, it takes time to obtain a constant potential due to the temperature change of the liquid to be measured, and as a result, the instantaneous change in ion concentration can be made continuous. In addition, gelatin or silver halide grains adhered to the liquid junction of the reference electrode to cause clogging, and an asymmetric potential was generated to make it difficult to obtain a constant potential as a reference. (Photographic Emulsion Ch
emistry 1966 by GFDuffin (FOCAL PRESS LIMITED p14
Also, in the measurement of silver ion activity in a system such as an aqueous gelatin solution containing silver halide crystals using a conventional silver metal rod as an indicator electrode, the reproducibility of the measured potential in repeated measurement must be satisfied. However, the size distribution, shape, photographic properties, etc. of the silver halide crystals obtained thereby varied. In Japanese Patent Laid-Open No. 60-2313858, as a stabilizing measure as a conventional silver ion concentration detecting electrode for obtaining the stability of the indicator electrode, one or more of silver and silver having a higher redox potential than silver is used. Is disclosed, or a method of using an alloy electrode made of two or more metals having a redox potential higher than that of silver.

[0009]

However, the method described in Japanese Examined Patent Publication No. 60-2313858 is an indicator electrode. An object to be measured permeated and adhered to a small gap between metallic silver and its alloy and its holding cover, and an accurate value could not be obtained when measuring different kinds of solutions to be measured.

The object of the present invention is to eliminate the temperature change of the reference electrode to secure a constant reference potential, and to make it possible to always carry out an accurate measurement by re-installing the indicator electrode. Another object of the present invention is to provide a method and an apparatus for measuring the concentration of silver or halogen ions, by which the concentration of silver or halogen ions can be instantaneously measured with good reproducibility and the reaction state at the time of silver halide crystal formation can be accurately traced.

[0011]

The above object of the present invention is to provide a reference electrode as a reference for potential measurement in a sensor system for detecting the concentration of silver or halogen in a gelatin aqueous solution containing silver halide crystals as a potential. Instead of directly putting it in the solution to be measured, it is placed in a precisely controlled temperature-maintaining bath that is in an electrically insulated state, and is electrically connected using a salt bridge between the solution to be measured and the reference electrode. Conductive, and one end of the indicator electrode is immersed in the solution to be measured, and the other end of the reference electrode and the indicator electrode is connected to a potentiometer to measure the potential difference. Ion concentration measurement method. A reference electrode, which is placed in a heat-retaining bath that is electrically insulated at a constant temperature, has one end electrically connected to a gelatin aqueous solution containing silver halide crystals by a silver bridge with a silver wire, and the silver halide crystals. Silver or halogen ion concentration, characterized in that it comprises an indicator electrode in which only one end is immersed in a gelatin aqueous solution containing, and a potentiometer in which the reference electrode and the other end of the indicator electrode are electrically connected. measuring device. In the contact portion of the salt bridge with the aqueous gelatin solution containing the silver halide crystals, a ceramic having fine pores is used, and a potassium nitrate solution is used as an internal solution of the salt bridge, or Halogen ion concentration measuring device. A silver metal rod having a purity of 99.9% or more is used as the indicator electrode, platinum is plated or an insulator is coated on the contact portion between the indicator electrode and the holding holder portion, and contact is made with the gelatin aqueous solution containing the silver halide. The silver or halogen ion concentration measuring device as described above or above, wherein the surface of the part is plated with AgBr or Ag ₂ S to a thickness of 0.1 μm or less. Achieved by

The salt bridge between the aqueous gelatin solution containing silver halide crystals (hereinafter referred to as the solution to be measured) and the reference electrode in the present invention is made of soft plastic, and the KNO ₃ solution is used as the internal solution in the hose. And its concentration is 0.0
1-5 mol / l, preferably 0.8-1.2 mol / l
1 is used. Immersing only one end of the indicator electrode in the liquid to be measured in the present invention means that only the tip of the one end of the indicator electrode is immersed and the body of the silver rod is not immersed in the liquid to be measured. Measuring the potential means measuring the potential difference between the reference electrode and the indicator electrode using a potentiometer. In the present invention, the heat insulation bath in a constant temperature and electrically insulated state,
The insulation bath is made of vinyl chloride or acrylic resin, or is insulated, and the internal liquid of the container with insulation of 100 MΩ or more (same as the salt bridge internal liquid) is kept within ± 0.5 ° C by a thermostat, etc. It means maintaining the stability of the potential. In the present invention, using a ceramic having fine pores in the contact portion of the salt bridge with the aqueous gelatin solution containing the silver halide crystals means that the porosity is 2 to 40%, preferably 5 to 1
The end of the salt bridge is plugged with a porous ceramic of 5%, and the outflow rate of the potassium nitrate solution of the internal solution is 0.01 at a head pressure of 9.8 KPa through the ceramic plug.
-10 cc / min, preferably 0.1-1 cc / mi
It means that the potassium nitrate solution of n is allowed to flow out from the warm bath into the gelatin aqueous solution containing the silver halide. Purity 99.9% as an indicator electrode in the present invention
The above silver metal rod is used, and the contact portion of the silver metal rod with the holding holder portion is coated with platinum or an insulating material, and Teflon or ceramic is used as this insulating material. The attachment to the part is supported by the O-ring. The surface of one end, which is the contact portion with the gelatin aqueous solution containing silver halide crystals, is AgBr.
Alternatively, one plated with Ag ₂ S to a thickness of 0.1 μm or less is used. By doing so, the accuracy of the potential of the indicator electrode is maintained. Alternatively, if a glass electrode is used as the indicator electrode, it is possible to provide a sensor system that can measure pH stably and with good reproducibility.

[0013]

【Example】

(Embodiment 1) An embodiment of the present invention will be described with reference to FIG. In a sensor system that detects the concentration of silver or halogen ions in an aqueous gelatin solution 1 containing silver halide crystals as a potential, a reference electrode 2 that serves as a reference for potential measurement is not placed directly in the liquid to be measured 1 0.5
It is placed in a heat insulation bath 3 made of vinyl chloride, acrylic resin, or Teflon coating, etc., whose temperature is precisely controlled within ℃, and salt between the measured liquid 1 and the reference electrode 2 is added. Silver which is electrically conducted using the bridge 4 and has only one end of one indicator electrode 5 immersed in the liquid to be measured 1 and the other ends of the reference electrode 2 and the indicator electrode 5 electrically shielded. A silver and halogen ion concentration measuring method and apparatus for connecting a potentiometer 6 with a line 7 to measure a potential difference. A saturated calomel electrode was used as the reference electrode 2, and a ceramic 8 having fine pores having a porosity of 5 to 15% was used. A ceramic 8 having pores is used at a contact portion of the salt bridge 4 with the aqueous solution of gelatin 1 containing silver halide, and 0.5 to 1.
A 2 mol / l potassium nitrate solution is used. Further, a silver metal rod 9 having a purity of 99.9% or more is used as the indicator electrode 5, and the contact electrode 11 with the holder 10 portion of the indicator electrode 5 has a P
t-plated or insulated Teflon coat or ceramic coat, and the following two O-rings 14 between the holder 10 and
Supported by. The surface of the contact portion 12 with the aqueous gelatin solution 1 containing silver halide is plated with AgBr or Ag ₂ S to a thickness of 0.1 μm or less.

Example 2 In the above example, the silver and halogen concentration measuring method and apparatus of the present invention used in the silver halide emulsion precipitation vessel 12 were described. In addition, a gelatin aqueous solution containing silver halide was sampled. FIG. 2 shows one example of the measuring device. Reference electrode 2
Is immersed in a heat-retaining bath 3 of a potassium nitrate solution, and both ends of a salt bridge 4 are electrically connected to a solution to be measured 1 which is a gelatin aqueous solution containing silver halide through a ceramic 8 having fine pores. The indicator electrode 5 electrically insulates the body of the silver metal rod, and the end of the liquid to be contacted is AgBr or Ag ₂ S.
It is plated with and is immersed in the liquid to be measured 1.
The other ends of the reference electrode 2 and the indicator electrode 5 are electrically connected to the potentiometer 6 by a shielded silver wire 7. The temperature of the liquid to be measured is kept constant by a constant temperature bath.

(Example-3) In Example-1, the reference electrode 2 and the indicator electrode 5 were separated from one holding holder, and the n indicator electrodes 5 were separated into silver halide emulsion precipitation vessels 13.
It is possible to measure the concentration distribution of silver or halogen ions in the precipitation container by installing the indicator electrode and the potentiometer 6 by switching the connection between the indicator electrode and the potentiometer 6 by the connection connection switching device 15.

[0016]

EFFECTS OF THE INVENTION With the silver or halogen ion concentration measuring method and apparatus of the present invention, a constant reference potential can be obtained by eliminating the temperature change of the reference electrode and the generation of asymmetric potential in the liquid junction of the reference electrode. By eliminating the influence of foreign substances adhering to the contact area with the solution to be measured and enabling accurate measurement, the electrode potential related to silver or halogen ion activity in various silver halide emulsions can be instantaneously measured. That is, it becomes possible to measure within 1 second (it took about 5 to 50 minutes to show a constant potential when placed in another solution to be measured in the past), and during the formation of silver halide crystals. Conventionally, the silver potential of the precipitation container of the prior art could be deviated by about 50 mV or more in the fluctuation range, but it can now be detected with good accuracy with an accuracy of ± 1 mV.
As a result, a silver halide photographic emulsion can be produced with good reproducibility. Others: The life of the reference electrode was extended, and when the high temperature automatic cleaning of the inside of the tank was performed, the sensor part could be cleaned at the same time, and it was possible to completely automate the preparation of the next product type. .

[Brief description of drawings]

FIG. 1 is a layout view of one embodiment of a silver or halogen ion concentration measuring device of the present invention.

FIG. 2 is a layout view of another embodiment of the silver or halogen ion concentration measuring device of the present invention.

FIG. 3 is a layout view of another embodiment of the silver or halogen ion concentration measuring device of the present invention.

[Explanation of symbols]

1 Gelatin aqueous solution containing silver halide crystals (solution to be measured) 2 Reference electrode 3 Insulating bath 4 Soft plastic hose salt bridge 5 Indicator electrode 6 Potentiometer 7 Shielded silver wire 8 Ceramic with fine holes 9 Silver metal rod 10 Holder 11 Body part of silver metal rod (platinum plating layer or Teflon coating layer or ceramic coating layer) 12 Contact part with measured liquid (plating layer of AgBr, Ag ₂ S) 13 Precipitation container 14 O-ring 15 Connection switching device

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[Procedure amendment]

[Submission date] August 11, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Therefore, by measuring the indicator electrode potential E, the states of pAg and pX in the silver halide photographic emulsion can be grasped. However, if a reference electrode for measuring the potential is placed in the liquid to be measured, it takes time to obtain a constant potential due to the temperature change of the liquid to be measured, and as a result, the instantaneous change in ion concentration can be made continuous. not be measured, further the liquid junction of the reference electrode adhere gelatin and silver halide grains clogging occurred raw Ji asymmetric potential that, it is difficult to obtain a constant potential as a reference. (Photographic Emulsion Ch
emistry 1966 by GFDuffin (FOCAL PRESS LIMITED p14
Also, in the measurement of silver ion activity in a system such as an aqueous gelatin solution containing silver halide crystals using a conventional silver metal rod as an indicator electrode, the reproducibility of the measured potential in repeated measurement must be satisfied. However, the size distribution, shape, photographic properties, etc. of the silver halide crystals obtained thereby varied. In Japanese Patent Laid-Open No. 60-2313858, as a stabilizing measure as a conventional silver ion concentration detecting electrode for obtaining the stability of the indicator electrode, one or more of silver and silver having a higher redox potential than silver is used. Is disclosed, or a method of using an alloy electrode made of two or more metals having a redox potential higher than that of silver.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

The above object of the present invention is to provide a reference electrode which serves as a reference for potential measurement in a sensor system which detects the concentration of silver or halogen ions in an aqueous gelatin solution containing silver halide crystals as a potential. Instead of putting it directly in the solution to be measured, put it in a temperature-controlled bath that has a precisely controlled temperature and is in an electrically insulated state, and use a salt bridge to electrically connect the solution to be measured and the reference electrode. And one end of the indicator electrode is immersed in the solution to be measured, and the other end of the reference electrode and the indicator electrode is connected to a potentiometer to measure the potential difference. Method for measuring halogen ion concentration. A reference electrode, which is placed in a heat-retaining bath that is electrically insulated at a constant temperature, has one end electrically connected to a gelatin aqueous solution containing silver halide crystals by a silver bridge with a silver wire, and the silver halide crystals. Silver or halogen ion concentration, characterized in that it comprises an indicator electrode in which only one end is immersed in a gelatin aqueous solution containing, and a potentiometer in which the reference electrode and the other end of the indicator electrode are electrically connected. measuring device. In the contact portion of the salt bridge with the aqueous gelatin solution containing the silver halide crystals, a ceramic having fine pores is used, and a potassium nitrate solution is used as an internal solution of the salt bridge, or Halogen ion concentration measuring device. A silver metal rod having a purity of 99.9% or more is used as the indicator electrode, platinum is plated or an insulator is coated on the contact portion between the indicator electrode and the holding holder portion, and contact is made with the gelatin aqueous solution containing the silver halide. The silver or halogen ion concentration measuring device as described above or above, wherein the surface of the part is plated with AgBr or Ag ₂ S to a thickness of 0.1 μm or less. Achieved by

Claims (4)

[Claims] 1. In a sensor system for detecting the concentration of silver or halogen-on in an aqueous gelatin solution containing silver halide crystals as a potential, a reference electrode for potential measurement is accurately placed without directly inserting it into a solution to be measured. It is placed in a temperature-controlled bath that has a constant controlled temperature and is electrically insulated, and electrically conducts between the measured solution and the reference electrode using a salt bridge,
On the other hand, the concentration of silver or halogen ions is measured by immersing only one end of the indicator electrode in the solution to be measured, and connecting the other end of the reference electrode and the indicator electrode to a potentiometer to measure the potential. Method. 2. A reference electrode, which is disposed in a heat-retaining bath that is electrically insulated at a constant temperature, and has one end electrically connected to a gelatin aqueous solution containing silver halide crystals by a salt bridge, and the halogen. It is characterized by comprising an indicator electrode having only one end immersed in a gelatin aqueous solution containing silver halide, and a potentiometer in which the other end of the reference electrode and the indicator electrode are electrically connected by a silver wire. Silver or halogen ion concentration measuring device. 3. A ceramic having fine pores is used at a contact portion of the salt bridge with an aqueous gelatin solution containing the silver halide crystals, and a potassium nitrate solution is used as an internal solution of the salt bridge. The silver or halogen ion concentration measuring device according to claim 2. 4. A silver metal rod having a purity of 99.9% or more is used as the indicator electrode, and a contact portion between the indicator electrode and a holding holder portion is coated with platinum or an insulator to form the silver halide crystal. The silver or halogen ion concentration measuring device according to claim 2 or 3, wherein the surface of the contact portion with the aqueous gelatin solution containing Ag is plated with AgBr or Ag ₂ S to a thickness of 0.1 µm or less.