JPS63214743A - Production of silver halide emulsion having improved suitability to desalting and washing - Google Patents

Abstract

PURPOSE:To prevent the clogging of a filter and to shorten the time necessary for a desalting and washing stage by removing part of the supernatant liq. of a silver halide (AgX) emulsion in a desalting and washing stage so as to regulate the total volume of flocks and the remaining supernatant liq. to a specified value basing on the amt. of AgX. CONSTITUTION:In a stage for desalting and washing an AgX emulsion, an org. gelatin flocculant is added to the emulsion to be desalted and washed and uniformly mixed. Consequently, liq. on flocculated and settled flocks is removed so as to regulate the total volume of the remaining supernatant and the flocks to 190-300ml per 1mol. AgX. The resulting emulsion does not cause the clogging of a filter due to flocks when the emulsion to be coated is filtered during desalting and washing by flocculation and settling. The time necessary for flocculation and settling can be shortened and the desalting efficiency is increased. Thus, the time necessary for the desalting and washing stage is shortened and an emulsion having satisfactory photographic performance can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a silver halide photographic emulsion, and more particularly to an improvement in the desalting and water washing steps using a coagulation sedimentation method.

[Background of prior art and invention]

Generally, during the manufacturing process of photographic silver halide emulsions, excess halides, by-produced nitrates, ammonium salts, etc. are removed from the emulsion after physical ripening, and desorption is performed to further concentrate the silver halide emulsion. Includes salt and water washing process.

The method for desalting and washing with water is described in ``Basics of Photographic Engineering.''

Various methods are known, as described in "Silver Halide Photography Edition" (edited by the Photographic Society of Japan, Corona Publishing). Let it precipitate, discard the supernatant, and decant for 2 to 30 minutes.
A method of desalting by washing three times with water (coagulation sedimentation method) is widely used.

In the coagulation-sedimentation method, conditions such as the amount of flocculant, stirring speed, and gelatin concentration are usually selected to create aggregate particles of appropriate size and precipitate them, but the desalting efficiency and emulsion concentration rate are limited. In order to increase the
In addition, a technique aimed at reducing the volume of aggregates as much as possible during sedimentation is disclosed in JP-A-60-220337.

However, if the aggregates are coarse, the sedimentation rate is high (and the work efficiency is good), but they tend to form lumps, and these aggregates have the disadvantage of clogging the filter in the process of filtering the emulsion before the coating process, causing failure. On the other hand, if the fruit is fine, the sedimentation rate will be slow and the time required for sedimentation will be longer.

[Purpose of the invention]

Therefore, the first object of the present invention is to provide a desalting/washing method that improves clogging of a filter when filtering a coated emulsion caused by aggregates during desalting/washing. Second, it is an object of the present invention to provide a desalting/rinsing method that can shorten the time required for the desalting/rinsing process.

[Structure of the invention]

An object of the present invention is to desalt a silver halide emulsion by a coagulation sedimentation method and wash it with water, in which at least one part of the supernatant liquid is desalted and washed with water.
This is achieved by a method for producing a silver halide emulsion, which is characterized in that the total volume of the aggregates and remaining supernatant liquid after removing part of the silver halide is 190 eef or more and 300 m1 or less per mole of silver halide.

In the present invention, an organic gelatin flocculant is used as a flocculant for desalting and washing with water by a coagulation sedimentation method of a silver halide emulsion. As an organic gelatin concentration agent, a water-soluble polymer compound having a sulfonic acid group or a carboxylic acid group or a surfactant with a relatively large molecular weight is used.
Many are described in No. 322. In particular, the following polymers can be cited as typical examples.

No, I No, 2a:b=G9
-9:1 (molar ratio) No, 3 No, 4c:d=
1:1 (molar ratio) ・, -a/ , No, 6 where 鵠 is the degree of polymerization and a"d is the composition ratio. These organic gelatin flocculants have molecules in the range of J11,000 to ioo, ooo. .

Commercially available products include Versa TL (Kanebo NNC Co., Ltd.), ScripL (Monsanto Company, USA), and EMA (Monsanto Company, USA).

The organic gelatin solid weight used in the present invention may be used in combination with other flocculants such as sulfates (magnesium sulfate, sodium sulfate, etc.), and the effects of the present invention will not be impaired even if they are used in combination.

The amount of the organic gelatin flocculant used in the present invention is 10 to 150% based on the solid weight of gelatin in the silver halide emulsion.
It is used in weight%, but considering resolubility, it is 10 to 80%.
% by weight is preferred. The pH for coagulation is preferably 7 or less, preferably 3 to 6.5.

The silver halide emulsions to which the present invention is applied include gelatin-based silver halide emulsions such as black and white emulsions, fogged direct blemish emulsions, color emulsions, silver chloride emulsions, silver bromide emulsions, silver chlorobromide emulsions, Silver iodobromide emulsions, single jet emulsions, double jet emulsions, etc. are not limited to the type of emulsion or the size of silver halide grains, and there are also particular restrictions on the ratio of silver to gelatin and the amount of excess halogen in the silver halide emulsion. Not sure (
, the ratio of silver to gelatin, and the amount of excess halogen do not impair the effects of the present invention.

The gelatin used in the present invention may be any gelatin normally used in silver halide emulsions (for example, alkaline gelatin, acidic gelatin, desalted gelatin, low calcium gelatin, etc.) (in short, gelatin coagulated with an organic gelatin flocculant). There is no particular limitation as long as it is gelatin.

A gelatin concentration of 0.3 to 3% by weight during coagulation of the silver halide emulsion used in the present invention gives good results, but even if the concentration is higher than that, the organic gelatin flocculant, pH, etc. The effects of the present invention can be obtained through adjustment.

The silver halide emulsion to which the present invention is applied is a silver halide emulsion mainly composed of gelatin, but other water-soluble polymer compounds (e.g., hydroxymethylcellulose, carboxymethylcellulose, polyacrylamide acrylate, polyvinyl alcohol, etc.) are also used. ) can be used in combination with gelatin to the extent that it does not interfere with coagulation with an organic gelatin flocculant.

In the present invention, an organic gelatin flocculant is added to the silver halide emulsion to be desalted and washed with water, and the organic gelatin flocculant is mixed uniformly, and at least iW of the supernatant liquid on the top of the flocculates that has coagulated and precipitated.
When S is removed, the total volume of the remaining supernatant liquid and aggregates is 190 ml or more per mole of silver halide and 300 m
Discard the supernatant liquid so that the concentration is below N. Therefore, in the present invention, the aggregation conditions (amount of flocculant, temperature and pH of the emulsion, etc.) should be appropriately selected so that the volume (bulk) of the agglomerates is 300 m1 or less per mole of silver halide. is necessary.

If the above-mentioned "remaining volume" is less than 190 mN, the filtration filter is likely to be clogged during emulsion coating,
If it exceeds 0-1, the desalination efficiency decreases, and the efficiency of the desalination and water washing process decreases. In addition, the higher the volume (bulk) ratio of the aggregates in the above-mentioned "remaining volume", the better; specifically, 8
It is preferably 0% or more.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A 2.5% gelatin aqueous solution 8.41 was kept at 40°C, and a silver iodobromide emulsion (monodisperse cubic emulsion) containing 1.5 mol% of silver iodide with an average grain size of 0.3 μ- was prepared in this aqueous solution. ) was used as a seed crystal emulsion and an amount equivalent to 2% of the silver amount after growth was dissolved, and 1.3
A specified amount of ammonia water was added. Add ammoniacal silver ions to bring the pAg to 11%, and add acetic acid to make the pAg 8.0.
H to 9.7, 1iiL, 366m equivalent to 1/10 of 3.2N ammoniacal silver ion solution 13660g+1
1' was added at a rate of 6 ml per minute. At the same time, 368 tsl of a halide solution containing 0.96 N of potassium iodide and 2 N of potassium bromide was added, and the pH and pAg were constant with acetic acid and potassium bromide solution to remove a localized portion of 30 mol% silver iodide. Formed. Furthermore, acetic acid and potassium bromide solution were added to adjust the pH to 9.0 and the pAg to 9.0.
．． 2N ammoniacal silver ion solution 3294+N and 3
．． Add the same amount of 2N potassium bromide solution, keep the pAg constant, add acetic acid in proportion to the am added, and adjust the pH.
The silver iodide content was 3 mol%, the average particle size was 1.21μ - the coefficient of variation of the particle size distribution was 15%, the gelatin concentration was 1.1% by weight, and the weight ratio between gelatin and silver was 115. A silver iodobromide emulsion was obtained.

This emulsion was divided into 5 parts, and a 5% by weight aqueous solution of exemplified compound No. 6, an organic gelatin flocculant, was added to each portion of the solid gelatin while stirring so that the amount of the flocculant became 20% by weight. ℃, the silver halide emulsion is coagulated, and the total volume of aggregates or aggregates and supernatant liquid settles to below the value shown in the "Capacity (A)" column of Table 1 (
The standing time is listed in Table 1), and the remaining after removing the supernatant <a
Discard the supernatant liquid until the total amount of fruits or aggregates and supernatant liquid reaches the amount shown in the "Capacity (A)" column of Table 1. Next, add 4.91 g of pure water at 40 ° C. , After stirring for 10 minutes, magnesium sulfate (20% by weight water soluble?l)
120 mN was added to coagulate the silver halide emulsion again, and after the aggregates had settled to 1 or less as shown in Table 1 [volume ff1 (A month) (the standing time is listed in Table 1), the 7 m collection fruit supernatant After discarding the supernatant liquid until the total volume of the liquid reached "capacity (A)", 4.9 liters of pure water at 40°C was added and stirred for 10 minutes, and then washed with water in the same manner as above (lf2f After desalting, gelatin solution (10% by weight)
After adding 500 mN of aqueous solution and diluting with pure water, pA
An emulsion with a weight of 8.5 g and a volume of 2000 sol was obtained.

Table 1 shows the amount of the five emulsions thus obtained that passed through a 1500 mesh filter at 35°C.

The desalination efficiency in Table 1 is a relative value of the ratio of the salt concentration before desalination to the salt concentration after desalination, and the larger the value, the better the desalination efficiency.

“As shown in Table 1, the emulsion according to the present invention does not clog the filter.Furthermore, according to the present invention, the standing time (time required for coagulation and sedimentation) is short, and the desalination process time is short. It is also possible to shorten the desalting efficiency.In addition, the desalting efficiency in the method of Emulsion 5 is 172 or less than that in the method of the present invention, and unnecessary salts cannot be removed by washing with water up to two times, so the number of washings with water must be further increased. Furthermore, although the desalting efficiency is good in the methods for Emulsions 1 and 2, the filters become clogged.

Example 2 Emulsions having various grain sizes shown in Table 2 were obtained in the same manner as in Example 1, except for changing the amount of the seed crystal emulsion. These were passed through a filter in the same manner as in Example 1, and as shown in Table 2, regardless of the particle size of the silver halide,
The emulsion according to the invention does not cause filter clogging.

Example 3 In the same manner as in Example 1, the gelatin concentration before adding the seed crystal emulsion was changed to obtain an emulsion having a grain size of 1.21 μm as shown in Table 3. The transit time of these emulsions when passed through a filter was measured in the same manner as in Example 1, and the results are shown in Table 3.

As shown in Margin Table 3 below, the emulsion to which the present invention is applied does not cause fill letter clogging, regardless of the gelatin concentration during silver halide growth.

Example 4 Ammonium thiocyanate, chloroauric acid, and hypo were added to the emulsions (1 to 5) obtained in Example 1 and chemically ripened (
4-
Hydroxy-6-methyl-1゜3.3a,? - A conventional coating aid and hardening agent were added to the emulsion containing tetrazaindene, and the mixture was coated on both sides of a polyethylene terephthalate support together with a gelatin protective film to prepare a light-sensitive material sample.

The amount of coated silver is 5.5g per 1m, and the amount of gelatin coated is l.
Next, these samples were
Placed at a distance of 2- from the MW and powered at 90kV p50mA,
X-ray exposure was performed for 08 seconds. At this time, the intensifying screen is polar light LT-f
f and an aluminum wedge. The image was developed using an automatic developer VX-400 manufactured by Konishiroku Photo Industry Co., Ltd.
and processed with XD-90 developer at 35° C. for 90 seconds.

In addition, in order to know the X-ray comfort, the blackening density of the developed sample was measured using a Konishi Roku Photo Industry Co., Ltd. [PDA-35 densitometer. The relative sensitivity of Emulsion 2 and Emulsion 3 was determined as 100.

In addition, in order to examine the heat resistance performance of each of emulsions 1 to 5,
After being left in an atmosphere of 55° C. 20% and f150° C. 80% for 3 days, capri, sensitivity and maximum density were determined by the above method. The results are shown in Table 4.

As is clear from Table 4, the emulsion produced by the method of the present invention has a small increase in capri when left at 55°C at 20% for 3 days, and a decrease in sensitivity Dma when left at 50°C at 80% for 3 days. There is little decrease in (maximum concentration).

〔Effect of the invention〕

According to the present invention, when silver halide emulsions are desalted and washed with water by the coagulation sedimentation method, the clogging of the filtration filter when filtering the coated emulsion caused by aggregates is improved, and the time required for coagulation sedimentation is improved. Since it is possible to improve the overall efficiency of both the desalination and water washing processes, it is possible to shorten the time required for the desalination and water washing processes.

Further, the emulsion produced according to the present invention also has good photographic performance.

Applicant: Konishiroku Photo Industry Co., Ltd. Procedural amendment March 10, 1986

Claims (1)

[Claims] In the process of desalting and washing a silver halide emulsion with water by a coagulation sedimentation method, the total volume of aggregates and remaining supernatant liquid after removing at least a part of the supernatant liquid is 190 ml or more and 300 ml or less per mole of silver halide. A method for producing a silver halide emulsion, characterized in that: