JPS63311346A - Production of silver halide photographic emulsion - Google Patents

Abstract

PURPOSE:To stably produce the titled emulsion composed mainly of silver bromide which has a narrow particle size distribution and is lessened the deflection width of a controllable EAg value, by incorporating 2-10mol.% a chloride based on a bromide in the titled emulsion. CONSTITUTION:The titled emulsion which contains mainly silver bromide, holding a silver potential (EAg) value of the silver halide emulsion to a constant value is produced by using the producing apparatus of the titled emulsion. In the process for producing said emulsion, the chloride is incorporated in the bromide in an amount of 2-10mol.% based on the used bromide. Namely, the EAg value of the silver bromide is stably controlled, and especially, the EAg value of 80-220mV is effective. Thus, the titled emulsion composed mainly of the silver bromide which is lessened the deflection width of the EAg value and has the narrow particle size distribution, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a silver halide photographic emulsion using a controlled double jet method.

(Prior art) The conventional double jet method, in which a silver salt aqueous solution and a silver halide aqueous solution are mixed while controlling the silver potential (EAg) value in a silver halide emulsion to a constant value, It has been widely used as an effective method for producing photographic emulsions in which the grain size, grain size distribution, crystal habit, etc. of silver halide grains can be controlled by controlling the values.

The most important feature of this method is to control the EAg value, but the EAg value during mixing of silver halide is significantly affected by stirring conditions, concentration of silver salt and halide aqueous solution, injection speed, injection amount, etc. , strictly constant EAg
It is difficult to control the value, and the current situation is that it is controlled within a certain range of fluctuations. In particular, silver bromide has a low solubility, so the EAg value tends to fluctuate.

In the controlled double jet method, fluctuations in the EAg value have a large effect on the grain size, grain size distribution, crystal habit, etc. of silver halide grains, but when trying to obtain a silver halide emulsion with a particularly narrow grain size distribution, the fluctuation in BAg value It is essential to make it small.

JP-A No. 60-203934 discloses an apparatus for producing a silver halide photographic emulsion using a double-jet method, which has a mixer in a reaction vessel consisting of a stirring blade and a casing fixed around the stirring blade. It has an opening for introducing a halogen salt aqueous solution, a silver salt aqueous solution and a protective colloid aqueous solution into the mixer, and has an opening at an upper end for discharging silver halide particles produced in the mixer; The aperture has a sufficient length in the direction of the stirring blade rotation axis so that the discharged liquid flow becomes a vertical flow in the direction of the stirring blade rotation axis, and has a plurality of conductive passages that open in the stirring blade rotation axis direction. An apparatus for producing a silver oxide photographic emulsion, comprising a flow control plate for horizontally diverting a liquid flow discharged as a vertical flow through the conductive path into the protective colloid aqueous solution above the mixer. An apparatus for producing a silver halide photographic emulsion is described.

The purpose of this device is to uniformly agitate the tank and narrow the particle size distribution of silver halide grains, but in the case of an emulsion containing mainly silver bromide, it is difficult to narrow the particle size distribution sufficiently. There was a drawback that it couldn't be done.

(Objective of the Invention) An object of the present invention is to provide a method for stably producing a photographic emulsion mainly containing silver bromide by reducing the fluctuation of the controlled EAg value in the controlled double jet method. be. Still another object is to provide a method for producing a photographic emulsion mainly containing silver bromide having a narrow particle size distribution.

(Structure of the Invention) The object of the present invention is to provide an apparatus for producing a silver halide photographic emulsion using a controlled double jet method, in which a reaction vessel is provided with
It has a mixer consisting of a stirring blade and a casing fixed around it, and the casing has a halogen salt aqueous solution at the lower end,
It has an opening for introducing the silver salt aqueous solution and the protective colloid aqueous solution into the mixer, and has an opening at the upper end for discharging the silver halide particles produced in the mixer, and the upper end opening is A silver halide photographic emulsion having a sufficient length in the direction of the rotational axis of the stirring blade so that the discharged liquid flow becomes a vertical flow in the direction of the rotational axis of the stirring blade, and a plurality of conductive paths opening in the direction of the rotational axis of the stirring blade. This is a manufacturing device for manufacturing equipment, in which a protective colloid above the mixer □
Using a silver halide photographic emulsion production apparatus having a flow control plate that horizontally diverts a liquid flow discharged as a vertical flow through the conductive path into an aqueous solution, the silver in the silver halide emulsion is A method for producing a photographic emulsion mainly composed of silver bromide while keeping the electric potential (BAg) value at a constant value, characterized by adding 2 to 10 mol of chloride to the bromide used. This is achieved by a method for producing a silver halide photographic emulsion.

The gist of the present invention is to stably control the pBAg value using the apparatus shown in JP-A No. 60-203934 and the addition of chloride, and to produce a photographic emulsion mainly composed of silver bromide with a narrow particle size distribution. However, especially when the EAg value is 80 mV~
The method of the invention is effective between 220 mV. Also E
When the Ag value is 80 mV or less, the fluctuation of the EAg value is relatively small even without adding chloride, but by using the method of the present invention, the fluctuation can be further reduced.

In the present invention, the EAg value refers to silver potential, and is a value measured using a metal silver electrode and a double junction type saturated Ag/A gct reference electrode.

In the normal control double jet method, the EAg value is -10
It is carried out in the range of 0 mV to 240 mV.

In the present invention, a photographic emulsion mainly composed of silver bromide is one in which the silver bromide composition of silver halide is 90 mole or more;
These include silver chlorobromide, silver iodobromide, silver chlorobromide iodide, etc.

In the present invention, bromides include potassium bromide, sodium bromide, and the like.

In the present invention, chloride refers to common salt, potassium chloride, etc., which has the effect of sufficiently reducing the fluctuation of EAg value at 2 to 10 molar relative to bromide, and if it is less than 10 molar, it affects the crystal form. It does not impair its properties as silver bromide.

The chloride of the present invention may be added by dissolving it in the aqueous bromide solution, or may be injected simultaneously with the aqueous bromide solution from a separate container.

In carrying out the present invention, the concentrations of the aqueous silver nitrate solution and aqueous halide solution used can range from 0.5 mol/l to 4 mol μ.

In carrying out the present invention, water-soluble polymers such as gelatin, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, etc. are used as the hydrophilic colloid. As the gelatin, acid-treated gelatin, alkali-treated gelatin, decalcified gelatin (Ca content: 11,000 PP or less), or chemically modified gelatin can be used.

The pH at which the present invention is practiced can range from 2 to 10.

For preparing the silver halide emulsion of the present invention, an ammonia method,
The effects of the present invention are not impaired regardless of whether a neutral method or an acidic method is used.

Examples Silver bromide emulsions (EM-1 to EM-4) were prepared in the following manner.

EM-1,2 (Liquid A) Ossein gelatin 4.6Kg water
6.6Kg 2N silver nitrate solution and 2N potassium bromide solution were simultaneously injected at 60°C while controlling the EAg value to solution A to which potassium bromide had been added in advance to give the EAg value as shown in Table 1. The mixture was mixed until the average particle diameter was 0.2μ.

As a mixing device, a double jet device shown in the specification of JP-A-60-203934 was used. The EAg value was measured using a metal silver electrode and a double junction type saturated Ag/Agct comparison electrode.

EM-3,4 Add 3 mol of salt to potassium bromide in 2N potassium bromide solution,
6 molti was added and the rest was manufactured in the same manner as EM-1 and EM-2.

Table 1 The emulsions produced in EM-1 to EM-4 were observed using an electronic microscope to measure average grains and particle size distribution, and to examine monodispersity. Monodispersity was expressed as a coefficient of variation expressed by (standard deviation of particle size)/(average particle size) x 100.

The results are shown in Table 2 below.

Comparing BM-1 and BM-3, the amplitude of the EAg value is clearly E
M-3 is smaller, has a lower coefficient of variation, and has a narrower particle size distribution. A similar effect appears in BM-4 as well. E
In M-1 and M-2, many microparticles of 0.15μ or less were observed.

The crystal forms of EM-1 to EM-4 are all cubic, but EM
There was no significant difference between -1, 2, 3, and 4.

Claims (1)

[Claims] A mixer consisting of a stirring blade and a casing fixed around the stirring blade is provided in the reaction vessel, and the casing has an opening at the lower end for introducing the halogen salt aqueous solution, the silver salt aqueous solution, and the protective colloid aqueous solution into the mixer. and has an opening at the upper end for discharging the silver halide particles generated in the mixer, and the upper end opening is arranged so that the discharged liquid flow becomes a vertical flow in the direction of the rotation axis of the stirring blade. The stirring blade has sufficient length in the rotation axis direction,
A silver halide photographic emulsion production apparatus comprising a plurality of conductive passages that open in the direction of the rotating axis of the stirring blade, in which a liquid stream is discharged as a vertical flow through the conductive passages into a protective colloid aqueous solution above the mixer. Using a silver halide photographic emulsion production apparatus having a flow control plate for horizontally diverting the flow,
In a method for producing a photographic emulsion mainly composed of silver bromide while keeping the silver potential (EAg) value in the silver halide emulsion at a constant value, 2 to 10 mol% of bromide is used.
1. A method for producing a silver halide photographic emulsion, which comprises adding chloride.