JP3308735B2 - Silver or halogen ion concentration measurement method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, controlling silver or halide ion concentration during or after formation of a silver halide photographic emulsion involves the following steps.
Indispensable for obtaining desired photographic characteristics, the reference electrode and the indicator electrode for the above purpose are used by directly inserting them into a precipitation container containing an aqueous gelatin solution in which an aqueous halide solution and an aqueous silver nitrate solution react. That has been widely done. The relationship between silver or halide ion concentration and electrode potential is described in “The Theory of the Photographic Process. Third.
edition or Fourth edition. (Macmillan Publishi
ng Co. Inc). The silver or halogen ion concentration is represented by pAg and pX, respectively, and is defined by equations (1) and (2). ^{pAg = -log [Ag +] ···} (1) pX = -log [X -] ···· (2) where [Ag ^+] silver ion activity. [X ^-] is a halogen ion shows the activity of (Br ^- or Cl ^{- -} or I). Silver in the silver halide crystal or electrode potential E _Ag and E _X of related to halide ion activity can be expressed as follows.

[0003]

(Equation 1)

In a practical silver halide emulsion, the halide salt is often excessive, and the silver supporting electrode is covered with a silver halide layer and is saturated with the silver halide salt. Therefore, the activities of silver and halogen ions on the electrode surface are in the relationship of the formula (4). [Ag ⁺ ] [X ⁻ ] = Ksp (4) Here, Ksp represents the solubility product of silver halide. That is, a silver / silver halide electrode is essentially equivalent to a silver electrode where the silver ion activity is dominated by the halide ion activity in the solution. Thus, Ex is given by equation (5), but the indicator electrode in the silver halide emulsion shows the same potential since 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
Can be shown by the following equation.

[0007]

(Equation 3)

Therefore, by measuring the indicator electrode potential E, the state of pAg and pX in the silver halide photographic emulsion can be ascertained. However, if a reference electrode for potential measurement is placed in the liquid to be measured, it takes time to obtain a constant potential due to a change in the temperature of the liquid to be measured. 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 is necessarily satisfactory. However, the silver halide crystals obtained therefrom varied in size distribution, shape, photographic properties, and the like. Japanese Patent Application Laid-Open No. Sho 60-213858 discloses, as a measure for stabilizing a conventional electrode for detecting silver ion concentration in order to obtain the stability of the indicator electrode, at least one of silver and silver whose oxidation-reduction potential is more noble than silver. Discloses a method using an alloy electrode composed of two or more metals whose oxidation-reduction potential is more noble than silver.

[0009]

However, the method described in Japanese Patent Publication No. 60-213858 is an indicator electrode. An object to be measured permeated and adhered to a slight gap between the metallic silver and its alloy and the holding cover thereof, so that accurate values could not be obtained when measuring different kinds of liquids to be measured.

An object of the present invention is to eliminate the temperature change of the reference electrode, to secure a constant reference potential, and to make the mounting method of the indicator electrode always accurate again. It is an object of the present invention to provide a method and an apparatus for measuring the concentration of silver or halide ions, by which the concentration of silver or halide ions can be instantaneously measured with good reproducibility and the reaction state at the time of silver halide crystal formation can be accurately tracked.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to provide a sensor system for detecting the concentration of silver or halide ions in an aqueous gelatin solution containing silver halide crystals as a potential. Instead of putting it directly into the solution to be measured, place it in a precisely controlled, constant temperature, electrically insulated bath, and use a salt bridge between the solution to be measured and the reference electrode. And a holding holder using a silver metal rod having a purity of 99.9% or more.
Platinum plating or insulating material is applied to the contact area with the
Only one end of the indicator electrode is immersed in the liquid to be measured.
A method for measuring the concentration of silver or halide ions, wherein the other ends of the comparison electrode and the indicator electrode are connected to a potentiometer to measure a potential. It is placed in a heat insulating bath that is electrically insulated at a constant temperature, and only one end is electrically connected to an aqueous gelatin solution containing silver halide crystals by a salt bridge.
Against the connection comparer electrodes, purity of 99.9% or more silver metal rod
Platinum plating or in contact with the holding holder using
And indicator electrode immersed only one end to a gelatin aqueous solution containing the silver halide crystals by coating an insulating material, and electrically connected to the conductive position in silver wire and the other end of the reference electrode and the indicator electrode silver or halogen ion concentration measuring device, characterized in that it consists of a difference meter. The silver or silver salt according to the above, wherein a ceramic having micropores is used in a contact portion of the salt bridge with the aqueous gelatin solution containing the silver halide crystal, and a potassium nitrate solution is used as an internal solution of the salt bridge. Halogen ion concentration measurement device. As the indicator electrode, of the or wherein the use of the surface of the contact portion with the aqueous gelatin solution containing a pre-Symbol silver halide crystals that plating below the thickness 0.1μm by AgBr or Ag ₂ S Silver or halogen ion concentration measurement device. Achieved by

In the present invention, the salt bridge between the gelatin aqueous solution containing silver halide crystals (hereinafter referred to as the liquid to be measured) and the reference electrode is formed by using a soft plastic and using a KNO ₃ solution as an internal liquid in the hose. And the concentration is 0.0
1 to 5 mol / l, preferably 0.8 to 1.2 mol / l
Use l. To immerse only one end of the indicator electrode in the liquid to be measured in the present invention means that only the tip of one end of the indicator electrode is immersed and the body of the silver bar is not immersed in the liquid to be measured. Measuring a potential means measuring a potential difference between a reference electrode and an indicator electrode using a potentiometer. In the present invention, the insulated bath that is in an electrically insulated state at a constant temperature is
Insulation bath is made of vinyl chloride or acrylic resin or insulated. Keep the inner solution (same as the salt bridge inner solution) in a container with an insulation of 100 MΩ or more within ± 0.5 ° C in a thermostat, etc. Maintaining the stability of the potential. In the present invention, the use of a ceramic having fine pores at 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 5% porous ceramic. The flow rate of the internal solution of potassium nitrate through the ceramic plug is set to 0.01 at a head pressure of 9.8 KPa.
10 to 10 cc / min, preferably 0.1 to 1 cc / mi
n means that the potassium nitrate solution flows out of the heat-retention bath into the aqueous gelatin solution containing the silver halide. Purity 99.9% as indicator electrode in the present invention
Using the silver metal rod described above, the contact portion of the silver metal rod with the holding holder portion is coated with platinum plating or an insulator, and Teflon or ceramic is used as the insulating material. The insertion into the part is supported by an O-ring. The surface at one end, which is the contact portion with the aqueous gelatin solution containing silver halide crystals, is AgBr.
Alternatively, a material 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, a sensor system capable of stably and reproducibly measuring pH can be provided.

[0013]

【Example】

(Embodiment 1) An embodiment of the present invention will be described with reference to FIG. In a sensor system for detecting the concentration of silver or halide ions in an aqueous gelatin solution 1 containing silver halide crystals as a potential, a reference electrode 2 serving as a reference for potential measurement is not directly placed in the liquid 1 to be measured, but is controlled by a thermostat. 0.5
It is placed in an insulated bath 3 made of vinyl chloride, acrylic resin, or Teflon coated at a constant temperature precisely controlled within ℃, and a salt is applied between the liquid 1 to be measured and the reference electrode 2. The bridge 4 is electrically connected, and only one end of one indicator electrode 5 is immersed in the liquid 1 to be measured, and the other ends of the reference electrode 2 and the indicator electrode 5 are electrically shielded. A silver or halogen ion concentration measuring method and apparatus for measuring a potential difference by connecting to a potentiometer 6 by a wire 7. As the comparative electrode 2, a saturated calomel electrode was used, and as the ceramic 8 having fine pores, one having a porosity of 5 to 15% was used. At the contact portion of the salt bridge 4 with the aqueous solution 1 of gelatin containing silver halide, a ceramic 8 having pores is used.
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 a contact portion 11 of the indicator electrode 5 with the holder 10 is used.
t-plated or insulated Teflon coat or ceramic coat, and the following two O-rings 14
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.

(Embodiment 2) In the above embodiment, the method and apparatus for measuring the silver or halogen concentration of the present invention used in the silver halide emulsion precipitation vessel 12 have been described. In addition, an aqueous gelatin solution containing silver halide was sampled. FIG. 2 shows one embodiment of all the measuring devices. Reference electrode 2
Is immersed in a warm bath 3 of a potassium nitrate solution, and both ends of the salt bridge 4 are electrically connected to a test solution 1 which is a gelatin aqueous solution containing silver halide through ceramics 8 having fine pores. The indicator electrode 5 electrically insulates the body of the silver metal rod, and its liquid contact end is made of AgBr or Ag ₂ S.
Is immersed in the liquid 1 to be measured.
The other ends of the comparison electrode 2 and the indicator electrode 5 are electrically connected to a potentiometer 6 by a shielded silver wire 7. The temperature of the liquid to be measured is maintained at a constant temperature by a thermostat.

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 replaced with the silver halide emulsion precipitation vessel 13.
By changing the connection between the indicator electrode and the potentiometer 6 by the connection connection switching device 15, the silver or halide ion concentration distribution in the precipitation container can be measured.

[0016]

According to the method and apparatus for measuring silver or halide ion concentration 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 at the liquid junction of the reference electrode. Eliminating the effects of foreign matter adherence at the contact area with the liquid to be measured, and enabling accurate measurement, instantaneous electrode potentials related to silver or halide ion activity in various silver halide emulsions That is, the measurement can be performed within one second (in the past, it took about 5 to 50 minutes to show a constant potential when put in another liquid to be measured). In the past, the silver potential of the precipitation vessel could be shifted by about 50 mV or more with a fluctuation range, whereas it could be detected with good reproducibility with an accuracy of ± 1 mV.
As a result, a silver halide photographic emulsion can be produced with good reproducibility. Others The service life of the reference electrode is extended, and when the tank is automatically cleaned at high temperature, the sensor section can be cleaned at the same time, which has the effect of being able to completely automate the preparation of the next product type. .

[Brief description of the drawings]

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

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

FIG. 3 is a layout diagram of another embodiment of the silver or halide ion concentration measuring apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Gelatin aqueous solution containing a silver halide crystal (measurement liquid) 2 Reference electrode 3 Insulation bath 4 Soft plastic hose salt bridge 5 Indicator electrode 6 Potentiometer 7 Shielded silver wire 8 Ceramic having fine holes 9 Silver metal rod 10 Holder 11 body portion of the silver metal rod contacting portion (the platinum plated layer or Teflon coating layer or ceramic coating layer) 12 test liquid (AgBr, plating layer of Ag ₂ S) 13 precipitates container 14 O-ring 15 hardwired switching device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-213858 (JP, A) JP-A-61-30853 (JP, U) JP-A-60-3464 (JP, U) 505237 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/416 G01N 27/30 G01N 27/401

Claims (4)

(57) [Claims] 1. A sensor system for detecting a silver or halogen ion-concentration aqueous gelatin solution containing silver halide crystals as a potential, not placed in the reference electrode directly under side fixed liquid as a reference for potential measurement, It is placed in a precisely controlled, constant temperature, electrically insulated insulated bath, and electrically conducts between the liquid to be measured and the reference electrode using a salt bridge, while having a purity of 99.9%. Using a silver metal bar
Apply platinum plating or an insulator to the contact
Immersing only one end of the indicator electrode in the liquid to be measured, connecting the other end of the reference electrode and the other end of the indicator electrode to a potentiometer, and measuring the potential. Measuring method. Wherein arranged in the temperature constant insulation bath which electrically is insulated, and the reference electrode which is electrically connected to only one end portion in an aqueous gelatin solution containing silver halide crystals by salt bridges, 99 0.9% or more silver metal bar
Apply platinum plating or an insulator to the contact
And indicator electrode immersed only one end to a gelatin aqueous solution containing the silver halide crystals by coating, and electrically conductive and connected by a silver wire <br/> the other end of the reference electrode and the indicator electrode silver or halogen ion concentration measuring device, characterized in that it consists of a position difference meter. 3. The method according to claim 1, wherein a ceramic having fine pores is used at a contact portion of the salt bridge with the aqueous gelatin solution containing the silver halide crystal, 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. As claimed in claim 4, wherein said indicator electrode, the surface of the contact portion with the aqueous gelatin solution containing a pre-Symbol silver halide crystals AgBr
Or Ag ₂ S silver or halogen ion concentration measuring device according to claim 2 or 3, wherein the use of what plated below the thickness 0.1μm by.