SU554522A1 - Method for producing halogen-silver photographic emulsions - Google Patents

Description

one

The invention relates to a method for producing halogen-silver photographic emulsions used to make photographic materials, including black-and-white negative, direct positive, color and materials used in diffusion processes. The method is particularly suitable for obtaining fine-grained and "grain-free Lippmann emulsions that have found application in holography, microelectronics, and nuclear physics.

It is known that the sensitivity of halogen-silver emulsions substantially depends on the concentration of silver ions. At the same time, for a number of emulsions (infrachromatic, fine-grained, Lippmann), as pAg decreases from the commonly used value of 9-7.5 to 7-5, photographic sensitivity increases.

At the same time, in the pAg range from 4.5 to 7.5, the colloidal stability of the emulsions sharply decreases. This is because the isoelectric point, for example, silver bromide lies in the region of 5 (depending on the size of microcrystals), and therefore because of the small electric charge of its particles in the region of 5-6.5, the probability of flocculation 1 .

Aggregation leads to loss of colloidal stability of the emulsion and, as a result, to

deterioration of a number of photographic characteristics of photographic materials based on these emulsions. The problem of colloidal stability of halide-silver emulsions in the case of fine-grained and Lippmann emulsions with a large excess surface energy is especially acute. In the range of 5–7.5, due to the coarsening of the grain, a rapid turbidity of the emulsions is observed upon standing. This makes it difficult to carry out all the manufacturing operations of the emulsions associated with its standing in the molten state and especially chemical and spectral sensitization.

An equally important problem for particularly fine-grained emulsions is the elimination (or inhibition) of recrystallization at high values of pAg (8.5-9.5), since recrystallization leads to the growth of microcrystals during emulsion processing, which impairs the resolution of photographic materials and makes it difficult chemical and spectral sensitization.

A known method for producing halogen-silver emulsions using the emulsification stages, the first and second maturation, as well as the introduction of additives into the emulsion, in which special fine-grained emulsions are used to increase colloidal stability and inhibit grain growth, or enter gelatins in the emulsion. t organic additives adsorbing on silver halide microcrystals. Such additives include, for example, sulfur-containing aromatic or heterocyclic compounds 2.

The disadvantage of the known method of stabilization of fine-grained emulsions is its inefficiency at pAg4 values of 5-7.5, especially at elevated temperatures and vigorous stirring, since the additives do not impart an electrical charge to the silver halide microcrystals, but only protect against flocculation by. In addition, due to the introduction of significant amounts (0.1-1 g / g-mol silver bromide) the organic substances strongly adsorbing and thereby blocking the surface of silver bromide, organic substances decrease the efficiency of ontic sensitization for a number of dyes and especially for infrachromatic sensitizers, the adsorption energy which is relatively ivelic.

The aim of the invention is to increase the colloidal stability of the emulsion and inhibit the growth of microcrystals, as well as to increase the sensitivity of the spectrally sensitized emulsion.

The essence of the invention is that in a known method, a salt or an acid containing a fourfold charge anion is added as an additive at any stage, for example, a salt or acid with a shifted cyanide complex anion.

As an acid or salt with a mixed cyanide complex anion, an acid with anion Fe (CN) Fe (CxN), NO, (CN) Fe {CN), Fe (CN), Fe (CN), AsO, -4; Co (CN) R, (CN) OS (CN) (CN) I. (CN) its salt.

Due to the specific adsorption of multi-charge anions on silver halide (due to their high polarizability), such ions become potential and microcrystals of silver halide retain a negative charge in the critical area for colloidal stability, 5-6.5. Thus, the aggregative stability of silver halide salts is achieved. Some of the anions (for example, Fe (SM) b) block the surface areas of the emulsion grains that are prone to dissolution, especially at high pAg values and thus inhibit recrystallization processes.

Chloride, bromide, iodide, chloride bromide, silver bromide iodide, etc. can be used as halides. Halide-silver emulsions can be obtained either by the method of two-jet emulsification or by single-jet method. Both ammonium and ammonia-free emulsions can be used. Gelatin or other hydrophilic film-forming polymers can be used as a binder. Emulsions can be subjected to sulfur or reductive sensitization, as well as to be sensitized by salts of metals of Group VIII of the Periodic Table of Elements with an atomic weight of 100 or gold salts. Emulsions can be spectrally sensitized with organic dyes. Tanning agents, stabilizers, anti-smoking agents and other additives can be added to the emulsion. Substances that stabilize them over time, including inhibitors of their oxidation by air oxygen, can be introduced into solutions of salts or acids containing multiply charged anions.

Solutions of salts or acids with multi-charge anions can be added to the emulsion at any stage after the end of emulsification, either alone or in conjunction with alkali metal halide solutions. Halogen-silver emulsions can be initially subjected to physical maturation or flocculation to bring the size of microcrystals to a certain size and then stabilized by the introduction of a salt solution with a multi-charge anion that inhibits the growth of silver halide microcrystals.

Example 1. Particularly fine-grained bromide-silver emulsion (0.7 mol.% Iodine) is synthesized by the method of double-flow (three-solution) controlled emulsification at 6 At 40 ° C. The silver content in the emulsion after washing 15 g per 1 l of the emulsion, the concentration of gelatin 3.0 weight. %, the average size of microcrystals is 0.03-0.04 microns.

Control emulsions are adjusted to a certain pAg with a solution of potassium bromide. The emulsions tested for the effect of colloidal stabilization are adjusted to the required pAg value with an aqueous solution of potassium ferro-syngas. The stability of the emulsions is assessed using a FEC-L photocolorimeter based on the light scattering of samples diluted with water in the ratio of 1:50 (behind a blue light filter).

The results of tests of emulsions for colloidal stability depending on pAg, temperature and speed of movement are given in Table. one.

From the data given in table. 1, it follows that the colloidal stability of the emulsion at, 7-6.7 is small and decreases even more with increasing temperature and movement. The introduction of potassium ferrocyanide ferrite provides the colloidal stability of emulsions.

Table 1

Example 2 An emulsion was prepared analogously to example 1. A control emulsion was made up using potassium bromide solution. In the tested emulsion, the concentration of silver ions is reduced to 6 ° C. Thus, potassium ferrocyanide inhibits the growth of silver bromide iodide microcrystals as a result of recrystallization at a high pAg value.

Example 3. An emulsion was prepared as in Example 1. The concentration of silver ions was adjusted with a solution of potassium bromide to pAg 6.4. The emulsion was set at 50 ° C for 1 hour, then divided into two parts. To one part, a solution of potassium ferromagnetisate to 0 is added, and the standing of both parts of the emulsion is continued for 1 hour. The optical density of the initial emulsion is 0.35. After 1 h, the standing D is 0.90. After the addition of ferro-synergistic potassium after 1 h of standing, the density is 1.00. The density of the original emulsion during this time increases to, 0. Thus, the introduction of potassium ferrocyanide at some stage inhibits

addition of potassium bromide solution and prior to the introduction of potassium ferrocyanide. Both emulsions stand at 40 ° C and with stirring (n 400 rpm). The test results are shown in Table. 2

table 2

Optical density D emulsion depending on the time of maturation, .min

silver bromide iodide microcrystal growth.

Example 4. An emulsion was prepared as in Example 1. A single portion of the emulsion was adjusted.

to, 7 using potassium bromide solution. The second batch is adjusted to 7 with a solution of potassium ferrocyanide. Then an alcoholic solution of AQ 1605 3,3-diethyl-9,11 cyanine dye (| 3, j3 - dimethyltrimethylene) of tiatetracarbocyanionic iodide in an amount of 10 g-mol / g mol of silver bromide-iodide of silver is introduced in both portions. The emulsions are allowed to stand for 20 minutes, then they are watered on glass and exposed on an FSR-14 sensitometer behind SZS-22 and KS-14 light filters. The plates are developed in a D-19 developer for 5 minutes. In parallel, experiments were conducted to determine the colloidal stability of emulsions at 40 ° C.

The results of definitions are given in table. 3

Claims (2)

Table 3 From the data given in table. 3, it follows that the introduction of potassium iron synergate into the emulsion significantly exceeds the effective sensitivity behind the KS-14 light filter. In addition, ferrocyanide potassium retains its stabilizing effect on colloidal stability and in the presence of a dye. Example 5. An emulsion was prepared as in Example 1. The control portion of the emulsion was adjusted to 6 with potassium bromide solution. The second portion of emlsia is adjusted to 6 using a solution (SMB). The emulsions are allowed to stand without mixing. The initial optical density of the emulsions is 0.35. After 1 h of standing, the optical density of the control emulsion increases to 1.50, while for an emulsion with a cobalt compound, only to 0.45. Thus, adding a cobalt compound helps stabilize the emulsion. Example 6. An emulsion was prepared in the same manner as in Example 1. The control emulsion was adjusted to 6 with potassium bromide solution. The second portion of emulsin is adjusted to pAg with 5.6 solution (CA) b. The emulsions are allowed to stand at 40 ° C without mixing. The initial optical density of the emulsion is 0.32. After 1 h, the optical density of the control emulsion increases to 1.40, while for emulsion C (C) only to 0.40. Thus, the addition of acid with multi-dose aio. nome provides colloidal emulsion stabilization. EXAMPLE 7. Highly fine-grained bromide-silver emulsion is synthesized by the method of double-flow (three-solution) controlled emulsification at 6, 6 at. The silver content in the emulsion (after washing) reaches 23 g per 1 liter of the emulsion, the concentration of gelatin is 3.0 weight. % The average size of microcrystals is 0.07-0.09 microns. The control portion of the emulsion is adjusted to pAg 5.5 solutions of potassium bromide. The second portion of the emulsion is adjusted to pAg 5.5 with a solution (CM) of 55Oz. The emulsin is allowed to stand at 55 ° C without stirring. The initial optical density of the control emulsion (behind a red light filter, a dilution of 1: 350) is equal to 0.125. After 1.5 hours, the optical density increases to 0.175. For an emulsion with (CN) 5S03, the initial density is 0.095. After 1.5 hours, the optical density did not change (0.094). Thus, the addition of (CN) 5SOs provides colloidal emulsion stabilization. Claim 1. Method of obtaining silver halide photographic emulsions by emulsification, first and second maturation, addition of additives, characterized in that, in order to increase colloidal stability and sensitivity of a spectrally sensitized emulsion, as well as inhibiting the growth of microcrystals, into an emulsion at any stage as additives are added to the salt or acid containing a four to five charge anion, for example, an acid or salt with a mixed cyanide complex anion. 2. A method according to claim 1, characterized in that an acid with anion Fe (CN) Fe (CN), NO, J-4 is used as an acid or salt with a mixed cyanide complex anion; Re, (CN), NOS | - "; Re (CN) 5SCN | - Re (SM), Re (CN), AsO, - “; Co (CN) R (CN) OS (CN) Mo (CN), I. (CN) or its salt. Sources of information taken into account in the examination 1.K. Miz, T. James. Theory of the photographic process. Ed. Chemistry, L., 1973, p. 23. 2. The UK patent number 1204623, cl. G OZS 1/02, publ. 09.09.70.