EP0046247A1 - Process for making dispersions and photographic materials - Google Patents

Abstract

Process for the preparation of photographic emulsions, consisting of dispersions of water-immiscible or water-insoluble particles in an aqueous solution of a binder, characterized in that the entire non-aqueous phase is initially introduced at a temperature above the liquefaction temperatures of the aqueous and non-aqueous phases, then a smaller volume emulsified continuously or in portions in the aqueous phase into the non-aqueous phase using methods known per se and finally, while continuing to emulsify, continue to add as much aqueous phase until the viscosity of the emulsion exceeds a maximum (which indicates the phase reversal to an emulsion of non-aqueous particles in an aqueous dispersion medium 1 shows a stirred tank (2) in which a solution of the color coupler and oil former is produced at 100 to 140 ° C. This stirred tank (2) also serves as a receiver tank and is equipped with a Kotthoff mixing siren (3) r The boiler (1) is equipped with a stirrer (4). In the kettle (1), gelatin, water and emulsifier can be added via the feed lines (5, 6 and 7). Oil formers and couplers can be added to the boiler (2) via the feed lines (8 and 9). The inflow and outflow can be regulated via the valves (10).

Description

The invention relates to a process for the production of dispersions and photographic materials which contain dispersions according to the invention. In particular, the invention relates to the production of dispersions of organic, hydrophobic substances in an aqueous phase.

In the following, dispersions are understood to mean apparently homogeneous systems which contain at least 2 phases in finely divided form and in which the particles of the phases are larger than 1 nm. Examples of dispersions are e.g. Emulsions and suspensions. The term "emulsified" is also common in the photographic field.

To prepare such dispersions, it is known to mix organic substances, in particular color couplers, in solid or liquid form with high-boiling solvents referred to as oil formers, optionally to add a low-boiling auxiliary solvent, and this mixture with the aid of an emuls gators with an aqueous solution, generally a gelatin solution. Such processes are described in US Pat. No. 2,322,027 and GB-A 791 353; from DE-PS 1 143 707 it is also known to emulsify color components with a melting point below 75 ° C. in a gelatin solution heated to 90 ° C. with the aid of an emulsifier. From GB-PS 1 151 590 it is known to use color couplers with a melting point below 100 ° C., the color couplers being melted together with a dispersant. From GDR patent specification 139 040 it is known to use color couplers with a melting point above 75 ° C. by mixing these couplers with a high-boiling solvent and then emulsifying them in water which contains a wetting agent. It can then be mixed with a gelatin solution at low temperature.

For the production of adhesive mixtures it is known from the patent specification GB-A 636 102 that such dispersions can be obtained by reversing the phase from a water-in-oil to an oil-in-water emulsion at temperatures below 100 ° C. With these dispersions, however, the criterion of particle fineness does not seem to play the decisive role as with color coupler dispersions for photographic use. Furthermore, the stability of these dispersions is not sufficient and can only be achieved by additional additives.

From DE-OS 3 011 927 it is also known that from a resolution of a color coupler in a low boiling solvent can be prepared by adding water, a water-in-oil emulsion, which can be converted into an oil-in-water emulsion by adding more water by phase reversal. This oil-in-water emulsion must be stabilized by adding a binder.

A disadvantage of the known processes is that it is very difficult to produce highly concentrated Disgate in a binder in a fine phase distribution without the use of low-boiling solvents in one operation.

The object of the invention is to find a dispersion process which avoids the disadvantages of the known processes. In particular, the invention is based on the object of specifying a dispersion process which, at a high concentration and without the use of low-boiling solvents, ensures a fine distribution of the dispersed compounds in a binder.

A process has now been found for producing dispersions from at least one liquid organic phase which contains a hydrophobic, photographically active compound and at least one aqueous phase; in which both phases are combined with dispersion. According to the invention, the organic phase is initially introduced and the aqueous phase is added to it with dispersion until an oil-in-water emulsion is formed from the water-in-oil emulsion initially formed by reversing the phase. When the phase is reversed, the viscosity exceeds a maximum.

The organic phase preferably contains a substance which is essentially immiscible with water at pH 7, in particular a photographically active substance. In addition, a preferably high-boiling oil former can be contained in a preferred embodiment.

This inversion method or phase inversion method is e.g. in the literature in Ullmann, Encyclopedia of Industrial Chemistry, Vol. 10, page 454 or in Stache, Tensid-Taschenbuch, Hanser-Verlag 1979, page 180 ff. However, the use of the phase reversal method for the preparation of dispersions with photographically active substances from oil-soluble photographic additives or the melted oil-soluble additive or its pure melt in an aqueous binder solution with active substances is not obvious to the person skilled in the art, because this phase reversal method requires that both phases are longer Time under high shear must be at temperatures that exceed the higher of the condensing temperatures of both phases. Therefore, on the basis of the generally recognized teaching opinion, the person skilled in the art must assume that the structure of the binders is destroyed under these circumstances by the combined thermal and mechanical stress until the binders become ineffective.

The process according to the invention is outstandingly suitable for producing dispersions in an aqueous medium from organic hydrophobic substances which are photographically active. Examples of Such substances include, for example, hydrophobic couplers of various types (4-equivalent couplers, 2-equivalent couplers, DIR couplers, mask couplers, white couplers, competitive couplers), dyes or other coloring compounds, for example for the color diffusion transfer process, UV absorbers, stabilizers and other photographic substances Additions.

The aqueous phase preferably contains, to improve the stability of the dispersions, hydrophilic colloidal binders, e.g. Gelatin. The gelatin can also be replaced in whole or in part by other natural, synthetic or semi-synthetic binders, e.g. by derivatives of alginic acid or cellulose, by polyvinyl alcohol, polyacrylates, partially saponified polyvinyl acetate or polyvinyl pyrrolidone.

Although the gelatin acts as a dispersing aid, it is not absolutely necessary. This means that a fine-particle stock dispersion can be produced without gelatin, e.g. a particle size of 320 nm. With the same concentration of organic phase, the gelatin causes a finer particle size distribution in the aqueous phase. The concentration of organic phase required for phase reversal with gelatin can also be reduced without an increase in the particle size being observed. Furthermore, the gelatin concentration can be used to control the particle size, since a higher gelatin concentration leads to a smaller particle size.

The dispersion temperature has little or no influence on the fine distribution. At lower temperatures and thus a higher viscosity of the organic phase, somewhat finer particle size distributions result. The preferred temperature range for the organic phase is 50 to 90 ° C, at dissolving temperatures of 100 to 140 ° C. The aqueous phase is advantageously kept at 50 to 90 ° C.

The dispersion takes place at normal pressure, but could also be carried out under pressure if higher temperatures (e.g. for products with higher liquefaction temperatures) require this.

The average particle size in the dispersions obtained is a function of the residence time, mixing power and dispersion temperature. In general, the influence of the residence time decreases with higher mixing performance. In general, finer dispersions can be obtained at higher temperatures than at lower temperatures. In principle, any particle sizes can be obtained, particle sizes from 200 to 800 nm, in particular from 300 to 350 nm, are particularly preferred.

According to the invention, relatively temperature-sensitive substances can also be dispersed in the dispersing device at high temperatures.

An important technical advance of the process according to the invention is that such highly concentrated (up to 70%) dispersions of high fineness are produced have been set, while according to the conventional method, according to the same experience with the different systems, the finer the dispersion, the lower the concentration of disperse phase. Conventionally produced emulsions for the photographic areas therefore hardly have a 2.0% disperse phase.

Another surprising technical advantage is that to achieve the required fineness (usually in the range between 100 to 500 nm), substantially simpler dispersing devices with a substantially lower energy input are sufficient.

The use of an oil former (high-boiling solvent such as tricresyl phosphate, dibutyl phthalate) is not absolutely necessary. If not specified for other reasons, it is advantageous to use only as much oil-forming agent as is required to prepare a pumpable solution, at the preferred dispersion temperature of 50 to 90.degree.

The ratio of organic matter (color coupler, UV absorber, etc.) to oil former is not a critical parameter for the success of the process. The oil former (high-boiling solvent) is not absolutely necessary, but it is advantageous not to exceed the viscosity of 1000 mPas at the preferred dispersion temperature. A corresponding setting is possible by adding oil formers.

The oil formers are substances which generally boil above 180 ° C. and have good dissolving power for the hydrophobic substance to be dispersed. Among these, the esters of glutaric acid, adipic acid, phthalic acid, sebacic acid, succinic acid, maleic acid, fumaric acid, isophthalic acid, terephthalic acid and phosphoric acid or the esters of glycerol, as well as paraffin and fluorinated paraffin are preferably used because these compounds are chemically stable and very easily accessible, very much can be handled easily and have no adverse effect on the light-sensitive materials when the dispersions are used for photographic purposes. The following are particularly preferably used as oil formers according to the invention: tricresyl phosphate, triphenyl phosphate, dibutyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, glycerol tributyrate, glycerol tripropionate, dioctyl sebacate. Paraffin and fluorinated paraffin. Examples of the preferred oil formers are given below.

The binder containing dispersion can be further processed by conventional methods, e.g. it can be gelled on cooling belts and transferred through a perforated grid into a pasta shape and stored in cold cellars. Of course, even in these process steps, the high concentration of the photographically active disperse phase requires a corresponding increase in the space / time yield and a reduction in the storage volume and the cooling costs.

However, the highly concentrated dispersate obtained can also be diluted with an aqueous binder-containing solution and / or a silver halide-containing photographic emulsion while maintaining the particle size. Furthermore, it has surprisingly been found that these dispersions are in dry emulsions with good storage stability and good solubility and redispersibility, e.g. following the usual drying processes for gelatin with a belt drying process, e.g. according to a method as described in US Pat. No. 2,801,171, especially when the concentration of the hydrophilic binder, based on an aqueous phase, is between 10 and 25%. The economic advantage of drying such highly concentrated and therefore low-water Emulgate is obvious.

The apparatus for performing the process are stirred tanks, as are common in chemical companies. Fig. 1 shows a useful device with a stirred tank 1, in which a solution of gelatin, water and emulsifier is produced. A solution of color coupler and oil former is produced at 100 to 140 ° C. in a stirred tank 2. This stirred tank 2 also serves as a storage tank and is equipped with a Kotthoff mixing siren 3. The boiler 1 is equipped with a stirrer 4. In the vessel 1, gelatin, water and emulsifier can be added via the feed lines 5, 6 and 7. In the boiler 2 8 and 9 oil formers and couplers can be added via the feed lines. The inflow and outflow can be regulated via the valves 10. After adding the gelatin solution and carrying out the phase reversal, the emulsate can, under certain circumstances, advantageously be discharged for use via a subsequent high-pressure homogenizing machine; however, this is not always necessary.

Particularly fine dispersions are obtained if the phase reversal is moved to the shear zone. This can be done according to FIG. 2. The aqueous phase of water 5, gelatin 6 and emulsifier 7 is prepared in a stirred tank 1 which is equipped with a stirrer 4. In a stirred tank 2, which is equipped with a stirrer 4, the organic phase from oil former 8 and color coupler 9 is placed. A water-in-oil emulsion is produced by adding the solution from 1 to 2. This water-in-oil emulsion is converted into an oil-in-water emulsion by a dispersing machine 11 by using appropriate shear forces, which is available in a boiler 12 for further use.

The dispersions prepared according to the invention are outstandingly suitable for the preparation of light-sensitive photographic materials which contain silver halide. The dispersions can be introduced into such materials in a manner known per se. The dispersions can be introduced both in layers containing silver halide and in layers free of silver halide.

The usual silver halide emulsions can be used, which can be prepared by the usual known methods. Gelatin can be used as a binder for the photographic layers, but can be replaced in whole or in part by other binders. Stabilizers such as e.g. Triazole derivatives, thiocarbonic acid derivatives of thiodiazole or azaindenes can be added. The silver halide emulsions can also be sensitized with the usual chemical sensitizers; for optical sensitization, the usual sensitizers, as described for example in the work of S.M. Hamer "The Cyanine Dyes and Related Compounds" (1964), Intersience Publishers John Wiley & Sons.

The photographic layers are hardened under conditions which do not adversely affect the image tone, but which allow the layers to be processed quickly even at higher temperatures. Suitable curing agents are, for example, formalin, dialdehydes, divinyl sulfone, triazine derivatives, optionally in counter were tertiary amines, as well as instant hardeners such as carbamoylpyridinium compounds or carbodiimides. The usual layer supports can be used, for example polyolefin-laminated underlays, for example polyethylene-coated paper, suitable polyolefins and paper, and also polyester underlays and triacetate-based films.

example 1

520 kg of 10% gelatin solution are placed in a kettle 1 FIG. 1. An additional 22.5 kg of triisopropyl naphthalene sulfonate are dissolved in this solution at a temperature of 60 ° C. (aqueous phase, W).

150 kg Kuppler der Formel

und 400 kg Trikresylphosphat bei 140°C gelöst und anschließend auf 80°C abgekühlt (Ölphase, 0).In a second boiler (2), 350 kg of couplers of the formula

150 kg coupler of the formula

and 400 kg of tricresyl phosphate dissolved at 140 ° C and then cooled to 80 ° C (oil phase, 0).

With constant mixing by a Kotthoff mixing siren 3 type turbine stirrer operated in the 2nd boiler, the contents of the 1st boiler are discharged into the 2nd boiler. This creates a water-in-oil (W / O) dispersion which, until the end of the addition of the aqueous phase, changes into an 8 l in water (0 / W) dispersion by phase reversal.

The average droplet size of the dispersion is 350 nm. A 35% dispersion is obtained.

Example 1a

From the color coupler dispersion prepared according to Example 1, 67 kg are added to 1000 kg of a molten photographic silver halide emulsion which is heated to 40 ° C. and is provided in the usual way with an optical sensitizer for the red spectral range and with other additives which influence the durability. This emulsion is cast into a photographic layer after the addition of hardening substances and the wetting agents customary for watering.

Example 1b

The concentrated color coupler dispersion prepared according to Example 1 is blended at 40 ° C. with 520 kg of 25% gelatin solution. The emulsifier formed is dried using methods known per se according to US Pat. No. 2,801,171.

Example 1c

The concentrated color coupler dispersion prepared according to Example 1 is at 40 ° C with 1200 kg of a Lö solution of 120 kg of gelatin and 4.8 kg of phenol in 1075.2 kg of water and then converted into a gel form by cooling to 4 ° C. After storage, the gel is dissolved in 2680 kg of a solution _/ of 78 kg of gelatin and 10.8 kg of phenol in 2591.2 kg of water at 40 ° C. in use.

Example 1d

The concentrated color coupler dispersion prepared according to Example 1 is mixed at 40 ° C. with 3879.5 kg of a solution of 198 kg of gelatin and 12.5 kg of phenol in 3669 kg of water. The solution can be directly processed further by adding to a photographic silver halide emulsion or by cooling in the gel form and stored until use.

Example 2

In a release kettle 1, Fig. ' 1 268.1 kg of 10% gelatin solution are prepared by a known procedure, placed at 60 ° C. and 9.3254 kg of emulsifier (75%) of the type of a straight-chain alkylbenzenesulfonate are introduced (aqueous phase).

In a second tank (2) 105 kg of dibutyl phthalate, 35 kg of compound of the formula

auf 140°C angeheizt und 70 kg Kuppler der Formel

eingerührt. Nachdem eine klare Lösung entstanden ist, wird auf 80°C abgekühlt und der Inhalt von Kessel 1 zum Inhalt von Kessel 2 gegeben (organische Phase).

heated to 140 ° C and 70 kg coupler of the formula

stirred in. After a clear solution has formed, the mixture is cooled to 80 ° C. and the contents of boiler 1 are added to the contents of boiler 2 (organic phase).

The initial water / oil dispersion produces an oil / water dispersion which is recirculated at 3000 1 / h at 200 bar for 30 minutes using a Knollenberg high-pressure homogenizer.

The average particle size is 310 nm. A 14% dispersion is obtained.

Example 2a

The concentrated color coupler dispersion prepared according to Example 2 is mixed with the appropriate amount of a silver halide emulsion to form the ready-to-pour photographic emulsion and poured in after the usual additives have been added.

Example 2b

The concentrated color prepared according to Example 2 coupler dispersion is blended at 40 ° C with 324 kg of 25% gelatin solution. The resulting emulsifier is dried using methods known per se.

Example 2c

In parallel to the emulsification process, a solution of 809.9 kg of 10% gelatin solution, 541.8 kg of water and 2.8 kg of 50% phenol solution is placed in the boiler 1 at 40 ° C. The concentrated stock emulsion produced in the final fineness is pressed into the boiler 1 by means of a rotary piston pump and a high-pressure homogenizer, where it is diluted to the final concentration and drained off again via the boiler 2 and the homogenization circuit, which is simultaneously pre-cleaned.

The batch is converted into a gel form by cooling to 4 ° C. and stored at 10 ° C. until used.

Example 3a

A color coupler melt is made from 350 g of couplers of the formula in a stirrable and heatable boiler

150 g Kuppler der Formel

und 400 g Trikresylphosphat bei 140°C hergestellt und anschließend auf 60°C abgekühlt.

150 g coupler of the formula

and 400 g of tricresyl phosphate at 140 ° C and then cooled to 60 ° C.

A solution of 300 g of water and 22.5 g of triisopropylnaphthalene sulfonate at 60 ° C. is added to this solution within 2 minutes. First a water-in-oil dispersion is created, then an oil-in-water dispersion after phase reversal. The emulsion is homogenized for 15 minutes with a high pressure homogenizer of the gan pump type at 150 to 200 bar. A 74% dispersion with a particle size of 310 nm is obtained.

Example 3b

An organic phase is produced as in example 3a.

In this solution, a 60 ° C warm solution of 250 g of 10% gelatin solution with 22.5 g of triisopropylnaphthalenesulfonate is added within 2 minutes. First a water-in-oil dispersion is created, then an oil-in-water dispersion after phase reversal. The emulsion is homogenized for 15 minutes with a high pressure homogenizer of the gan pump type at 150-200 bar. A dispersion with a particle size of 270 nm is obtained.

Example 4

und 0.,.25 kg Verbindung der Formel

bei 120°C gelöst und vorgelegt. Als Rührorgan wird ein Scheibenrührer mit einem Druchmesser von 60 mm bei einer Drehfrequenz von 1000 min^-1 verwendet. In diesem Kessel wird aus einer beheizten und gerührten offenen Vorlage mittels Zahnraddosierpumpe eine 95°C heiße Mischung aus 2,0 kg Gelatinelösung 10 %ig und 0,07 kg Triisopropylnaphthalinsulfonat mit einem Stoffstrom von 20 kg/h eindosiert.In a heatable and stirrable 10 1 pressure vessel Color coupler melt made of 0.75 kg dibutyl phthalate; 0.5 kg coupler of the formula

and 0.,. 25 kg compound of the formula

dissolved at 120 ° C and submitted. A disc stirrer with a diameter of 60 mm and a rotation frequency of 1000 min ^{-1 is} used as the stirrer. A 95 ° C hot mixture of 2.0 kg gelatin solution 10% and 0.07 kg triisopropylnaphthalene sulfonate with a material flow of 20 kg / h is metered into a heated and stirred open receiver in this kettle by means of a gear metering pump.

At a temperature of 120 ° C and an overpressure of 1 bar, an initial W / O dispersion results in an O / W dispersion, which is then stirred for a further 20 minutes under these conditions. The mixture is then cooled to 60 ° C., decompressed and drained into storage vessels or sent straight to further processing.

A finely divided dispersion with an average particle size of 550 nm and a concentration of 14% is formed.

Example 5

900 g of 10% gelatin with 66 g of straight-chain alkylbenzenesulfonate 75% at 60 ° C. are placed in a dissolving kettle 1, FIG. 1.

In a second kettle 300 g tricresyl phosphate are heated to 140 ° C. and 300 g 1- (2 ', 4', 6'-trichlorophenyl) -3- (3 "- 8- [2" ', 4 "' -di -tert.-amylphenoxy] -butyramido) -benzamido.-5-pyrazolone; 300 g 1- (2 ', 4', 6'-trichlorophenyl) -3- [2 "-chloro-5" -cetyloxicarbonylamido) -anilino] -5-pyrazolone stirred in and dissolved.

After a clear solution has formed, the mixture is cooled to 80 ° C. and the contents of kettle 1 are added to the contents of kettle 2 with stirring and recirculated for 12 minutes using a Manton Gaulin high-pressure homogenizer 3 at 200 to 250 bar. A dispersion with an average particle size of 350 nm and a concentration of 38% is obtained.

• 3600 g Gelatinelösung 10 %ig;
• 1350 g H₂0 und
• 112,5 g Phenollösung 20 %ig
• vorgelegt ist.

The finely divided, concentrated dispersion produced in this way is then discharged into a further temperature-controlled and stirred kettle in which a mixture is formed at 40.degree

• 3600 g gelatin solution 10%;
• 1350 g H ₂ 0 and
• 112.5 g phenol solution 20%
• is presented.

The emulsified product is then gelled on a cooling belt and stored at + 10 ° C until further processing.

The dispersant obtained is added to a silver halide emulsion containing 60 g / l silver halide in a manner known per se. The dispersion thus obtained is provided with hardening and wetting agents and cast onto a base in a known manner. The material obtained is exposed imagewise and developed in a conventional color developer.

• Die oben angegebenen Mengen an Kuppler und Trikreylphosphat werden in 1200 g Essigester gelöst. Durch Einfließenlassen in 4500 g 10 %-ige Gelatinelösung, die mit der oben angegebenen Menge Netzmittel versetzt wurde, wird unter Rühren eine Mischung hergestellt. Diese Mischung wird mehrfach durch eine Mischsirene geschickt und dabei dispergiert. Anschließend wird das Lösungsmittel im Vakuum abgedampft. Das erhaltene Emulgat wird der Silberhalogenidemulsion zugesetzt.

For comparison, a corresponding photographic material is produced from the same silver halide emulsion with the same dispersed compounds, but the dispersion was not carried out according to the invention but as follows:

• The amounts of coupler and tricreyl phosphate given above are dissolved in 1200 g of ethyl acetate. A mixture is prepared by stirring in 4500 g of 10% gelatin solution to which the above-mentioned amount of wetting agent has been added. This mixture is passed through a mixing siren several times and dispersed in the process. The solvent is then evaporated off in vacuo. The emulsify obtained is added to the silver halide emulsion.

The comparison material was processed in the same way as that of the invention.

The sensitometric data listed in the table below show that, according to the invention, a higher sensitivity, gradation and maximum density is obtained.

An increase in sensitivity by 0.3010 units corresponds to a doubling of the sensitivity.

Example 6a

15 kg of compounds according to DE-OS 2 036 719 and 15 kg of compounds according to DE-OS 1 772 192 are produced in a dissolving kettle by heating to 80 ° C.

40 kg of 12% gelatin solution and 0.628 kg of emulsifier of the type of a straight-chain alkylbenzenesulfonate (10%) are added to this organic phase. The addition is carried out with stirring using a mixer at a peripheral speed of 5 m / s. The process of producing a water-in-oil emulsion takes place. The dispersion has a particle size of 572 nm.

Example 6b

An organic phase is prepared as in Example 6 a. However, 1.884 kg of emulsifier are used with the 12% gelatin solution. The resulting dispersion has a particle size of 475 nm.

Example 6c

An organic phase is prepared as in Example 6 a. However, a 20% gelatin solution and 1.884 kg emulsifier are used. The resulting dispersion has a particle size of 404 nm.

Example 6d

An organic phase is prepared as in Example 6a. A 20% gelatin solution is used and 1.884 kg emulsifier. However, the phase reversal takes place at circumferential speeds of 23 m / s. The resulting dispersion has a particle size of 385 nm.

Claims (10)

1) Process for the preparation of dispersions from at least one liquid organic phase which contains a hydrophobic, photographically active substance and at least one liquid aqueous phase by combining the phases with dispersion in a dispersing device, characterized in that the organic phase is initially charged and to this the aqueous phase is added with dispersion until after a maximum of the viscosity has been exceeded a phase reversal to a dispersion of the organic phase in the aqueous phase is obtained. 2) Method according to claim 1, characterized in that the organic phase is the pure melt of a photographically active substance and that the dispersion takes place above the liquefaction temperature of this photographically active substance. 3) Method according to claim 1, characterized in that the organic phase is the solution of a photographically active substance in an oil former (high-boiling solvent) and that the dispersion takes place above the liquefaction temperature of this solution. 4) Method according to claim 1, characterized in that the aqueous phase contains dissolved binder and that the dispersion above the liquefy temperature of this binder solution. 5) Method according to claim 1, characterized in that the aqueous phase is a gelatin solution. 6) Method according to claim 1 to 5, characterized in that the dispersion of the organic phase and the aqueous phase in which binders are dissolved takes place at a temperature above the liquefaction temperatures of both phases. 7) Method according to claim 1, characterized in that the photographically active substance is a color coupler. 8) Method according to claim 1, characterized in that the photographically active substance is a UV absorber. 9) Method according to claim 1, characterized in that the photographically active substance is a stabilizing agent. 10) Photographic material from a layer support, at least one silver halide emulsion layer and optionally further layers, characterized in that a dispersion prepared according to claim 1 is contained in at least one layer.

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