DE10101773A1 - Production of a silver bromide iodide or bromide chloride iodide emulsion used in color silver halide photographic materials - Google Patents

Abstract

Production of a silver bromide iodide or bromide chloride iodide emulsion of Br content at least 80 mol.% and iodine content 1.5-15 mol.%, a projection surface of at least 50% crystals of aspect ration at least 4-25:1 and comprising a core, an inner region containing at least 5 mol.% I and of higher I content than the core and an outer region, comprises precipitating a core forming 0.2-3 mol.% of the crystals in a precipitation medium of pH 1.2-2.5, pAg value 8.5-100. The emulsion has a ratio of particle volume distribution DV to numerical distribution DN of 1-0.65, where DV is at least 25%smaller.

Description

Process for the preparation of a tabular photographic silver bromide iodide or silver bromide chloride iodide emulsion with a bromide content of at least 80 mol% and an iodide content of 1.5 to 15 mol%, based on the Projection area of at least 50% of crystals with an aspect ratio of at least 4: 1 and at most 25: 1 and a structured core structure, inner area and outer area, the inner area at least one contains iodide-rich crystal zone with an iodide content of at least 5 mol%, which based on the silver 10 to 70 mol% of the crystals and a higher Has iodide content as the core and the outer region, according to this method prepared silver halide emulsions and photographic materials, such Contain silver halide emulsions.

It is known from Research Disclosure 37 725, p. 606 (1995), silver bromide iodide emulsions with structured ultra-thin crystals with aspect ratio Produce ratios between 34: 1 and 57: 1 by the precipitation of the iodide poor crystal nucleus in the precipitation medium has a pH of 1.8 and a pAg of 9.1 set and then several zones under special conditions to be noticed.

With the emulsions according to the prior art, however, it does not succeed at the same time to achieve a very high sensitivity and good latent image stability as they today for photographic materials, especially for highly sensitive color films, be required.

The invention is therefore based on the object of a new silver halide emulsion to provide, which is characterized by a very high sensitivity and at the same time by good latent image stability.  

It has now surprisingly been found that this succeeds if a structured structured silver bromide iodide or silver bromide iodide chloride emulsion is precipitated in such a way that when the crystal nucleus is precipitated, pH values between 1.2 and 2.5 and pAg values between 8.5 and 10, 0 are observed and the subsequent crystal growth is controlled so that crystals with an aspect ratio between 4: 1 and 25: 1 and a ratio of particle volume distribution width D _V to numerical distribution width D _N (D _V / D _N ) from 1.0 to 0 , 65 can be obtained in which D _{V is} less than 25%.

The invention therefore relates to a process for producing a tabular photographic silver bromide iodide or silver bromide chloride iodide emulsion with a bromide content of at least 80 mol% and an iodide content of 1.5 to 15 mol%, which, based on the projection area, consists of at least 50% Kris tallen with an aspect ratio of at least 4: 1 and at most 25: 1 and a structured structure of core, inner region and outer region, the inner region contains at least one iodide-rich crystal zone with an iodide content of at least 5 mol%, which is related makes up 10 to 70 mol% of the crystals on the silver and has a higher iodide content than the core and the outer region, characterized in that when the core is precipitated, the 0.2 to 3.0 mol% based on the silver which constitutes crystals, pH values of 1.2 to 2.5 and pAg values of 8.5 to 10.0 are maintained in the precipitation medium and the emulsion has a ratio from particle volume distribution width D _V to numerical distribution width D _N (D _V / D _N ) from 1.0 to 0.65, where D _{V is} less than 25%.

The crystal growth after nucleation can be optimized by a person skilled in the field of emulsion production by known methods in order to produce the emulsions according to the invention with aspect ratios between 4: 1 and 25: 1, ratios D _V / D _N between 1.0 and 0.65 Obtain D _V values less than 25%.

The relative distribution width D _{V of} the volume-weighted mean particle diameter of a grain size distribution (d _V ) is defined as

and the relative distribution width D _{N of} the numerical mean of a grain size distribution (d _N )

where the grain size of a crystal is the diameter of the same volume sphere is defined.

It is preferred, after precipitation of the crystal nucleus and before precipitation of the iodide-rich ones Crystal zone at least one silver halide zone with a lower iodide content than in the iodide-rich crystal zone, especially a silver bromide zone precipitate, the pAg value in the precipitation medium being less than 9.5.

In a preferred embodiment, the iodide-rich crystal zone contains one Iodide content of at least 10 mol% and at most 40 mol%, it being particularly is preferred if the iodide-rich crystal zone 10 to 40 mol% of the total silver of all the crystals.

It is particularly advantageous if the aspect ratio is at least 8: 1, in particular especially between 10: 1 and 22: 1.

Particularly good latent image stabilities can be achieved if the ratio D _V / D _{N has} values from 0.85 to 0.70 and D _{V is} less than 20%.

Methods which form emulsions onto the project are particularly preferred tion area related crystal share of at least 80%.

The invention furthermore relates to a photographic silver halide emulsion, characterized in that it uses a method according to the invention and a photographic silver halide material with a support, especially a color photographic material with a transparent support, because characterized in that it contains such a silver halide emulsion.

Further preferred embodiments of the invention are set out in the subclaims remove.

Examples of color photographic materials are color negative films, color reversal films, Color positive films, color photographic paper, color reversal photographic paper, color sensitive materials for the color diffusion transfer process or silver dye bleaching process. An overview can be found in Research Disclosure 37 038 (1995) and Research Disclosure 38957 (1996).

The photographic materials consist of a support on which at least one photosensitive silver halide emulsion layer is applied. Own as carrier especially thin films and foils. An overview of carrier material lien and auxiliary layers applied to the front and back are in Research Disclosure 37 254, Part 1 (1995), p. 285 and in Research Disclosure 38 957, Part XV (1996), p. 627.

The color photographic materials usually contain at least one red sensitive, green-sensitive and blue-sensitive silver halide emulsions layer and, if necessary, intermediate layers and protective layers.  

Depending on the type of photographic material, these layers can be arranged differently. This is shown for the most important products:
Color photographic films such as color negative films and color reversal films have 2 or 3 red-sensitive, cyan-coupling silver halide emulsion layers, 2 or 3 green-sensitive, purple-coupling silver halide emulsion layers and 2 or 3 blue-sensitive, yellow-coupling silver halide emulsion layers on the support in the order given below. The layers of the same spectral sensitivity differ in their photographic sensitivity, with the less sensitive sub-layers generally being closer to the support than the more sensitive sub-layers.

Between the green sensitive and blue sensitive layers is common a yellow filter layer is applied, which prevents blue light from lying in the below layers.

The possibilities of different layer arrangements and their effects The photographic properties are described in J. Inf. Rec. Mats., 1994, Vol. 22, Pages 183-193 and in Research Disclosure 38 957 Part XI (1996), p. 624 be wrote.

Color photographic paper, which is usually much less sensitive to light as a color photographic film, points in the order given below usually a blue-sensitive, yellow-coupling silver halide on the carrier nidemulsion layer, a green-sensitive, purple-coupling silver halide emulsion sion layer and a red-sensitive, cyan-coupling silver halide emul ion layer on; the yellow filter layer can be omitted.

Deviations in the number and arrangement of the photosensitive layers can occur to achieve certain results. For example, you can all highly sensitive layers in one layer package and all low-sensitive layers  Layers together to form another layer package in a photographic film be quantified to increase sensitivity (DE-25 30 645).

Essential components of the photographic emulsion layers are binders, Silver halide grains and color couplers.

Information on suitable binders can be found in Research Disclosure 37 254, Part 2 (1995), p. 286 and in Research Disclosure 38 957, Part II.A (1996), p. 598.

Information about suitable silver halide emulsions, their preparation, maturation, Stabilization and spectral sensitization including suitable spectral sensi Bilisators can be found in Research Disclosure 37 254, Part 3 (1995), p. 286, in Research Disclosure 37 038, Part XV (1995), p. 89 and in Research Disclosure 38 957, part V. A (1996), p. 603.

Photographic materials with camera sensitivity usually contain Sil berbromide iodide emulsions, which may also contain small amounts of silver chloride can contain. Photographic copying materials contain either silver chloride bromide emulsions with up to 80 mol% AgBr or silver chloride bromide emulsions with over 95 mol% AgCl.

Information on the color couplers can be found in Research Disclosure 37 254, Part 4 (1995), p. 288, in Research Disclosure 37038, Part II (1995), p. 80 and in Research Disclosure 38 957, Part X. B (1996), p. 616. The maximum absorption of the dyes formed from the couplers and the color developer oxidation product is preferably in the following ranges: yellow coupler 430 to 460 nm, purple couplers 540 to 560 nm, cyan couplers 630 to 700 nm.

In color photographic films, to improve sensitivity, grainy speed, sharpness and color separation are often used in the compounds involved in the reaction  with the developer oxidation product release compounds that are photographic are effective, e.g. B. DIR couplers that release a development inhibitor.

Information on such compounds, in particular couplers, can be found in Research Disclosure 37 254, Part 5 (1995), p. 290, in Research Disclosure 37 038, Part XIV (1995), p. 86 and in Research Disclosure 38 957, Part X. C (1996), p. 618.

The mostly hydrophobic color coupler, but also other hydrophobic components of the Layers are usually ge in high-boiling organic solvents dissolves or disperses. These solutions or dispersions are then in one emulsified aqueous binder solution (usually gelatin solution) and lie after drying the layers as fine droplets (0.05 to 0.8 µm through knife) in the layers.

Suitable high-boiling organic solvents, methods for incorporation into the Layers of photographic material and other methods, chemical ver Finding bonds in photographic layers can be found in Research Disclosure 37 254, Part 6 (1995), p. 292.

The usually indicated between layers of different spectral sensitivity ordered non-photosensitive interlayers may contain agents that an undesirable diffusion of developer oxidation products from a light sensitive to another light-sensitive layer with different spectra Prevent central sensitization.

Suitable connections (white coupler, scavenger or EOP catcher) can be found in Research Disclosure 37 254, Part 7 (1995), p. 292, in Research Disclosure 37 038, Part III (1995), p. 84 and in Research Disclosure 38 957, part X.D (1996), p. 621 ff.

The photographic material can also UV-absorbing compounds, whiteners, spacers, filter dyes, formalin scavengers, light stabilizers, antioxidants, D _Min dyes, plasticizers (latices), biocides and additives to improve the coupler and dye stability, to reduce the color fog and to reduce yellowing and other included. Suitable compounds can be found in Research Disclosure 37 254, Part 8 (1995), p. 292, in Research Disclosure 37 038, Parts IV, V, VI, VII, X, XI and XIII (1995), p. 84 ff and in Research Disclosure 38 957, Parts VI, VIII, IX and X (1996), pp. 607 and 610 ff.

The layers of color photographic materials are typically hardened, i.e. that is Binder used, preferably gelatin, is replaced by suitable chemical Process networked.

Suitable hardener substances can be found in Research Disclosure 37 254, Part 9 (1995), p. 294, in Research Disclosure 37 038, Part XII (1995), page 86 and in Research Disclosure 38 957, Part II.B (1996), p. 599.

After photographic exposure, color photographic materials become their character processed according to different processes. Details on ver procedures and the chemicals required for this are in Research Disclosure 37 254, Part 10 (1995), p. 294, in Research Disclosure 37 038, parts XVI to XXIII (1995), P. 95 ff and in Research Disclosure 38 957, parts XVIII, XIX and XX (1996), P. 630 ff published together with exemplary materials.

Examples Emulsions used Em-1 (comparison)

3 l of a 0.2% by weight inert gelatin solution, the 3.2 g KBr were added, stirred at 40 ° C and a pH of 5.8. To this Solution are in a double inlet 20 ml of a 0.5 molar silver nitrate and a 0.5 molar potassium bromide solution was metered in in 30 seconds, Precipitation medium has a constant pAg of 9.5 by regulating the potassium bromide dosage was maintained. The AgBr- Crystals are referred to as seed precipitation of the emulsion and are based on the total silver 0.3%.

The temperature of the reaction vessel is then raised to 60 ° C. and one Add a solution of 20 g of low-viscosity inert gelatin in 200 ml of water. The pH is still 5.8 and a pAg of 9.4 is with a 0.5 molar Potassium bromide solution set. Now 1.1 l of a 3 molar silver nitrate solution metered in, the metering rate continuously from an initial value of 5 ml / min is linearly increased to a final value of 50 ml / min and at the same time a 3 molar potassium bromide solution dosed so that a pAg value in the precipitation medium of 9.4 is held during the precipitation. The one generated in this precipitation section AgBr crystal area makes up a proportion of total silver 99.7% and is called the crystal shell.

After the precipitation has ended, the emulsion is desalted to a conductivity of less than 2 mS, chemically ripened optimally with sodium thiosulfate and tetrachloroauric acid and then spectrally sensitized with 450 μmol BS-1 per mol silver halide and by adding 4 mmol 4-hydroxy-6- methyl-1,3,3a, 7-tetraazaindene per mole of Ag stabilized. Further information on Em-1 can be found in Table 1.

Em-2 (comparison)

Germ precipitation of Em-2 is carried out in exactly the same way as for Em-1 described. It accounts for 0.3% of the total silver.

Then the temperature of the reaction kettle is also increased to 60 ° C and a solution of 20 g of low-viscosity inert gelatin in 200 ml of water given. The pH continues to be 5.8 and a pAg of 9.4 is included a 0.5 molar potassium bromide solution. Now 0.1 l of a 3 molar Silver nitrate solution metered in, the metering rate being continuous from an initial value of 5 ml / min is increased linearly to a final value of 15 ml / min while doing so at the same time a 3 molar potassium bromide solution is metered in so that in the precipitation medium a pAg of 9.4 is maintained during the precipitation. The one in this Crystalline region produced from AgBr makes one on the whole silver-related share of 7.7% and is called the inner silver bromide zone designated.

This is followed by a double enema of a 3 molar silver nitrate solution and a 3 molar potassium bromide iodide solution (with 90 mol% potassium bromide and 10 mol% potassium iodide) at a pAg of 9.4 regulated with a 0.5 molar potassium bromide solution at a dosing rate of 12 , 5 ml / min over 14 minutes. The AgBr _0.9 I _0.1 crystal region generated in this precipitation section accounts for 13.5% of the total silver and is referred to as the iodide-rich crystal zone.

Then 1.02 l of a 3 molar silver nitrate solution are metered in, the metering rate continuously from an initial value of 15 ml / min to a final value is increased by 50 ml / min and at the same time a 3 molar potassium bromide dosed in such a way that a pAg of 9.4 in the precipitation medium during the Precipitation is held. The crystal region generated in this precipitation section AgBr accounts for 78.5% of total silver and will referred to as the crystal shell. Further information on Em-2 can be found in Table 1.

After the precipitation has ended, the emulsion is reduced to a conductivity of less than 2 mS desalted, optimally chemically with sodium thiosulfate and tetrachloroauric acid matured, then spectrally sensitive with 450 µmol BS-1 per mol silver halide lized and by adding 4 mmol of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazainden each Mol Ag stabilized. Further information on Em-2 can be found in Table 1.

Em-3 (invention)

In a reaction kettle, 3 l of a 0.2% by weight inert gelatin solution, to which 2.5 g of KBr have been added, are stirred at 40 ° C. and a pH range adjusted to 1.5 with 2N HNO ₃ solution. 20 ml of a 0.5 molar silver nitrate and a 0.5 molar potassium bromide solution are metered into this solution in a double inlet in 30 seconds, a constant pAg of 9.4 being maintained in the precipitation medium by regulating the potassium bromide metering. The AgBr crystals produced up to this point in time are referred to as seed precipitation of the emulsion and make up 0.3% of the total silver.

Then the pH is adjusted to 5.8 with 2N KOH solution and the pAg value of 9.25 with 0.5 m KBr solution and the inner silver bromide zone (with a based on the total silver content of 7.7%) as described for Em-2 noticed with a pAg regulated to 9.25.  

This is followed by a double enema of a 3 molar silver nitrate solution and a 3 molar potassium bromide iodide solution (with 80 mol% potassium bromide and 20 mol% potassium iodide) at a pAb value of 9.4 regulated with a 0.5 molar potassium bromide solution at a dosing rate of 12. 5 ml / min over 14 minutes. The AgBr _0.8 I _0.2 crystal region generated in this precipitation section accounts for 13.5% of the total silver and is referred to as the iodide-rich crystal zone.

The precipitation of the AgBr crystal shell with a based on the total silver Proportion of 78.5%, desalination, chemical ripening, spectral sensitization and stabilization are as described for Em-2. Further information on Em-3 are shown in Table 1.

Em-4 (invention)

Em-4 is made like Em-3, however, during the precipitation of the inner Silver bromide zone kept a pAg of 8.85 constant and during the precipitation the crystal shell kept a pAg of 9.1 constant. Further information on Em-4 are shown in Table 1.

Em-5 (comparison)

Em-5 is precipitated as described in RD 37725, p. 606 (1995) for "Emulsion A" and desalted, chemically matured, spectrally sensitized and as described for Em-1 stabilized.  

example 1

Test materials for color negative color development were prepared by applying the following layers in the order given to a transparent cellulose triacetate support. The quantities given relate to 1 m ² . The corresponding amounts of AgNO ₃ are given for the silver halide application.

1st layer (emulsion layer)

1.7 g AgNO ₃

the test emulsion
3.3 g gelatin
1.62 g colorless coupler Y
1.62 g tricresyl phosphate

2nd layer (intermediate layer)

2.0 g gelatin

3rd layer (protective and hardening layer)

0.25 g gelatin
0.60 g of curing agent H

The emulsions used are listed in Table 1 below.

A sample of each material was left behind after exposure of a gray wedge a blue filter based on "The British Journal of Photography", 1974, pages 597 and 598 developed and determined the relative sensitivity in DIN.

The sensitivities obtained are listed in Table 1 as relative values, where the sensitivity specification for material 1 is arbitrarily set to 100 is.

To determine the latent image stability, a sample as described above was used wrote exposed and together with an unexposed comparative sample of the same material stored for 2 weeks at 40 ° C and 50% relative humidity. To Exposure of the comparative sample was carried out jointly according to "The British Journal of Photography ", 1974, pages 597 and 598. This exam is a good rapid test for the latent image stability of photographic materials. In Table 1 the sensitivities determined in this way are delta E latent values equal to rel.  

Sensitivity in DIN of the exposed sample minus rel. Sensitivity in DIN specified in the comparison sample.

Table 1

From Table 1 it can be clearly seen that the emulsions according to the invention are characterized by a very high sensitivity and good latent image stability.

Claims (10)

1. A process for producing a tabular photographic silver bromide iodide or silver bromide chloride iodide emulsion with a bromide content of at least 80 mol% and an iodide content of 1.5 to 15 mol%, which is based on the projection area to at least 50% of crystals with an aspect ratio of at least 4: 1 and at most 25: 1 and a structured structure consisting of core, inner region and outer region, the inner region contains at least one iodide-rich crystal zone with an iodide content of at least 5 mol%, which is 10 to 70 mol based on the silver -% of the crystals and has a higher iodide content than the core and the outer area, characterized in that during the precipitation of the core, which is 0.2 to 3.0 mol% of the crystals based on the silver, pH in the precipitation medium Values from 1.2 to 2.5 and pAg values from 8.5 to 100 are observed and the emulsion has a ratio of particle volume distribution width D _{V has a} numerical distribution width D _N (D _V / D _N ) from 1.0 to 0.65, where D _{V is} less than 25%. 2. The method according to claim 1, characterized in that after the precipitation of the Crystal nucleus and before precipitation of the iodide-rich crystal zone at least one Silver halide zone with a lower iodide content than in the iodide-rich Crystal zone is noticed, the pAg value in the precipitation medium smaller than 9.5. 3. The method according to claim 2, characterized in that the one pAg of less than 9.5 precipitated silver halide zone from silver bromide consists. 4. The method according to claim 1, characterized in that the iodide-rich Crystal zone has an iodide content of at least 10 mol% and a maximum of 40 mol% contains.   5. The method according to claim 1, characterized in that the aspect ver ratio is at least 8. 6. The method according to claim 1, characterized in that the ratio D _V / D _{N has} values from 0.85 to 0.70 and D _{V is} less than 20%. 7. The method according to claim 1, characterized in that the crystal portion accounts for at least 80% of the projection area. 8. The method according to claim 1, characterized in that the iodide-rich Crystal zone accounts for 10 to 40 mol% of the total silver of all crystals. 9. Photographic silver halide emulsion, characterized in that it was prepared by the method of claim 1. 10. Color photographic silver halide material with a support, thereby characterized in that it is a silver halide emulsion according to claim 9 contains.