JPH09146221A - Method for producing dispersion of photographically useful compound ready for use in coating solution for hydrophilic layer of photographic material - Google Patents

Abstract

(57) Abstract: A concentrated dispersion of a photographically useful compound having an ionizable acid site on a molecule, which is ready for use in a coating solution for a hydrophilic layer of a photographic material. A method for preparing a dispersion of a photographically useful compound, said compound having at least one ionizable acid site on its molecule, said method comprising: -comprising said compound in an alkaline medium. Deprotonation and solubilization, microprecipitation of said compound, -microfine precipitation of the compound, -of the photographically useful compound in the non-photosensitive and / or photosensitive hydrophilic layers of the silver halide photographic material A manufacturing method comprising a step of coating the dispersion, wherein fine pulverization is carried out during and / or after the microprecipitation step.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a process for preparing a dispersion of a photographically useful compound which can be used immediately in a coating solution for a hydrophilic layer of a photographic material. ionisable acid site).

[0002] Photographically active components for use in one or more hydrophilic layers of silver halide photographic materials are well known, whether photosensitive or not. Particularly well-known components are filter dyes, accutance dyes or antihalation dyes, stabilizers, color or non-color couplers, color coupler precursors, developing agents, developing activators and deactivators, hardeners, sensitizers. A dye that can be used as an agent or a desensitizer.

[0003] One of the objects is therefore always to bring the components in a suitable dispersed form in the layer.

[0004] One of the possibilities for achieving that object is, for example, EP-A 0 384 633 and 0 351 593, and also the approved EP-A 0 233 729, 02747.
23,0276566 and U.S. Pat.
904565, 4949654, 4940654, 49
48717, 4988611 and 4803150 in the preparation of solid particle dispersions of water-insoluble compounds as widely described for dyes.

[0005] One of the objects is therefore always to provide the dye in a suitable dispersed form in said layer.

[0006] Usually, the storage dispersion of the solid particle dispersion is
Formed in aqueous gelatinous media by ball mill, sand mill, roll mill and other techniques. The method 6
There is no interest in economics since the milling time is ２４24 hours and even 72 hours. The mechanical load therein is so severe that an increase in temperature can lead to a partial decomposition of the dye. Especially when making gelatinous dispersions from mixtures of dyes necessary to obtain the desired absorption wavelength spectrum, the milling method interferes with the mechanical process because of the dramatic increase in viscosity. Longer production times make the production method "directly incorporation directly into the coating solution" impossible. The dispersion must be stored and desintegration of the dispersed colloid and / or agglomeration of the particles may occur. Attempts have been made to provide a dispersion of the dye by the so-called "microprecipitation method" in order to avoid the mechanical load during the preparation of the dispersion as described above. The microprecipitation method is, for example, DE-PS9323.
43, EP-A0015601, 0019299, 03
23729, 0549486 and 0549489, JP
-A61-185568, GB112253 and 13
05441 and US-A 4,970,139,507520
5,5077184,5089380,510478
6,51555015 and 5182189.

[0007] EP-A 0 549 486 discloses microprecipitated dispersions containing methine oxonol filter dyes. In the above EP-A, US-A 48552
24, in which re-precipitation of the dye is considered to be an inadequate technique for preparing filter dye dispersions.

[0008] EP-A 0 549 489 discloses a microprecipitation method using acidic protons of a filter dye, which is used during the acidification step of a dispersing aid, wherein the dispersing aid is used in a filter dye composition prior to acidification. Preferably, the milling technique is excluded there.

The dispersing aid is a stabilizer, a dispersant, a surfactant, a polymer colloid or a mixture thereof.

[0010] Dispersions of dyes having ionizable acid sites on the molecules and other photographically useful compounds prepared according to the microprecipitation method usually involve large agglomerated particles, especially when starting from concentrated slurries in aqueous media. And the microprecipitation is carried out at a high concentration. As a result, such dispersions are not preferred as components for coating solutions of hydrophilic layers in photographic materials containing photographically useful compounds having ionizable acid sites on the molecule.

[0011]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a concentrated dispersion of a photographically useful compound having an ionizable acid site on the molecule, which can be used immediately in a coating solution for a hydrophilic layer of a photographic material. Is to get

It is a further object of the present invention to obtain a dispersion having particles having a sufficiently small average particle size, having a small amount of aggregated particles.

[0013] Other objects will become apparent from the following detailed description and examples.

[0014]

According to the present invention, there is provided a process for preparing a concentrated dispersion of a photographically useful compound which can be used immediately in a coating solution for a hydrophilic colloid layer of a silver halide photographic material. The compound has at least one ionizable acid site on its molecule, the method comprising:-deprotonating and solubilizing the compound in an alkaline medium, microprecipitating the compound;
-Milling the microprecipitated compound;-coating the dispersion of the photographically useful compound in a non-photosensitive and / or photosensitive hydrophilic layer of a silver halide photographic material; A manufacturing method is provided in which milling is performed during and / or after the microprecipitation step.

[0015]

DETAILED DESCRIPTION OF THE INVENTION As used herein, the term "dispersion of a photographically active or photographically useful compound or component" for use in one or more hydrophilic layers of a silver halide photographic material. Are used as filter dyes, acutance dyes or antihalation dyes, stabilizers, color or non-color (colorless) couplers, color coupler precursors, developing agents, development activators or quenchers, curing agents, sensitizers or desensitizers Involved. Especially when the photographically useful compound is a dye, the term "dispersion of at least one dye" means that if more than one dye is present in said dispersion, they are separately microprecipitated "microprecipitation dispersions". As a result of a mixture of "body" s, or both mixtures originating from a mixture of at least one "co-microprecipitated dispersion", which is comminuted by the process of the invention during and / or after the microprecipitation step. Must be interpreted as a thing. In particular, according to the method of the present invention, the dispersion is prepared from, but not limited to, merostyryl dye, oxonol dye, developing agent, activator or quencher.

The "microprecipitate" is used to acidify an aqueous alkaline solution of a photographically useful compound having ionizable acid sites on the molecule, which is deprotonated and consequently solubilized in an alkaline medium. Obtained by:
During microprecipitation, it is preferable to provide an energy input such that when the alkaline solution is contacted with the acidic solution, strong mixing of the alkaline and acidic solutions of the photographically useful compound occurs. Preferably said mixing is "low shear mixing",
Provided by "high shear mixing" or "axial flow blade mixing".

An example of a "high shear mixer" is "Ultra Turrax
"(Janke & Kunkel) and" Misch Sirene "(
Kotthoff). A type of "axial flow blade" well known from the literature is described, for example, in Chem. Eng. Sc., Vol.
992), pages 1401-1410.
Turbine, anchor blade, blade
e) or paddle blades. The blades are variable speed motors (Zeromax, Model K, Zeromax Inc.,
Driven in it by Toronto). The effect of the blade is described in, for example, Chem. Eng. Progress, February 1994, 45-
It is described on page 48. Ultrasonic transducers are "Branson Liquid Processor" and "Branson So
nifier 250 ", whose schematic diagram is the
ltrasound Dispersing ”, University of Leuven
1987/1988, B. Horsten, pages 83 and 84, respectively.

In another example, the ultrasonic device is optionally associated with at least a portion of the device, in which microprecipitates are formed or collected after precipitation.

[0019] Combinations of different energy sources can be applied that provide energy input during and / or after microprecipitation. The energy can be varied by changing the parameters, by changing the input energy of one device, whether or not combined with another device, for example by changing the stirring speed of the stirrer, (Diameter, height, distance ...), flow rate, etc. can be varied. Perr
For example, "Kenics static mixer" (Chemi Eng.
neer, Inc.) and “Sulzer static mixer” (Koch
Engineering Co., Inc.).

Furthermore, the application of energy input according to the method of the invention can be carried out batchwise or continuously.

The microprecipitation step which forms part of the process used in the present invention may be carried out in a small "nucleation" vessel, in which case a small amount of acid solution is dissolved in the photographically useful compound At a controlled rate, which flows at a predetermined rate through the "nucleation vessel" into a larger vessel to collect microprecipitated compounds. Suitable components such as, for example, dispersants, solvents, binders or combinations thereof may be present in such larger containers, but especially before the microprecipitated dispersion is coated on a film support. When stored for a certain period of time,
It should be present there at a much lower concentration than before the milling process, or it should be avoided at the nucleation stage. In a continuous production process, the sonication step can be applied to the "nucleation vessel", to the main pipe connected to said "nucleation vessel" and "collection vessel", or to the "collection vessel".

Otherwise, the dispersion can be formed batchwise in one vessel by microprecipitation. This discontinuous method can be interrupted at any stage of the microprecipitation process, for example, to change the mixer, to initiate sonication for a well-defined time. The sonication step during and / or after the microprecipitation step is in many cases highly preferred.

Thus, a combination of energy inputs is possible to obtain a predictable average particle size and particle size distribution for the particles of the dispersion of the photographically useful compound.

The aqueous solution of the photographically useful compound used in the process according to the invention is made alkaline with a base such as, for example, sodium hydroxide or potassium hydroxide. In the neutralization step, an organic acid such as acetic acid or propionic acid is used, or a diluted inorganic acid such as sulfuric acid or phosphoric acid is used.

In the microprecipitation step of the dispersion preparation, in which the microprecipitates formed are pulverized during and / or after the microprecipitation step according to the method of the invention, said microprecipitation step comprises at least one dispersant, at least one hydrophilic It is carried out in the presence of a sex colloid or a mixture thereof.

When the microprecipitation step is performed in the absence of a dispersing agent and / or a dispersing aid such as a hydrophilic colloid, the drug and / or colloid is added during the pulverization step, and then the microprecipitation step is performed. Added inside.

[0027] Suitable hydrophilic colloids are, for example, gelatin, colloidal silica sols and synthetic, semi-synthetic or other natural polymers. Compounds that replace gelatin are, for example, polyvinyl alcohol, poly-N-vinylpyrrolidone, polyvinylimidazole, polyvinylpyrazole,
Polyacrylamide, polyacrylic acid and their derivatives, especially copolymers. Natural alternatives to gelatin are other proteins such as zein, albumin and casein, cellulose, saccharides, starch and alginic acid. In general, semi-synthetic alternatives to gelatin are gelatin derivatives obtained, for example, by conversion of gelatin with alkylating or acrylate agents or by grafting polymerizable monomers to gelatin, and hydroxyalkylcellulose, carboxymethylcellulose, phthaloylcellulose, And cellulose derivatives such as cellulose sulfate. The hydrophilic colloid should treat a large number of acceptable functional groups, which can provide a sufficient resistant layer after coating by reaction with a suitable hardener. Such functional groups include, in particular, amino groups, but also carboxyl groups, hydroxy groups and active methylene groups.

As the solvent, for example, methyl alcohol,
Ethyl alcohol, isopropyl alcohol, tetrahydrofuran, dimethylformamide, dioxane, N-
Methyl-pyrrolidone, acetonitrile, ethylene glycol, ethyl acetate, tetrahydrofuran and the like can be used. However, the solution contains an aqueous solution of a surfactant containing a polymer, which is ionizable by a base.

Suitable dispersants used in the microprecipitation step of the dispersion production process according to the invention are ionizable polymers and / or amphoteric and / or surfactants. Surfactants having a hydrophobic portion (eg, a long chain aliphatic group or an aliphatic-aromatic group) and a hydrophilic portion (eg, an anionic or cationic group, an amphoteric group or a nonionic group such as an ethylene oxide group) It is suitable. They include interfacial anionics containing acidic groups such as carboxy, sulfo, phospho, sulfric or phosphoric ester groups; amino acids, aminoalkyl sulfonic acids, aminoalkyl sulfates or phosphates, alkyl betaines, amine-N-oxides such as Amphoteric agents include cationic agents such as alkylamine salts, aliphatic, aromatic or heterocyclic quaternary ammonium salts, aliphatic or heterocyclic ring containing phosphonium or sulfonium salts. The drug has the function of facilitating the dispersion and emulsification of the components in the silicic acid during the manufacturing procedure. These surfactant compounds may or may not be added to the reaction vessel, with or without the organic solvent of the photographically useful compound to be dispersed, added to the aqueous alkali solution, or divided into two. Good. Particularly preferred is 2-
It is an amphoteric compound such as N, N, N-trialkylaminoacetic acid. The dispersant, if present, is preferably present in an amount of 0.1 to 20% by weight, based on the amount of dye.

If the microprecipitation step, which forms part of the process used in the present invention, is carried out in a milling vessel, a small amount of acidic solution flows through said vessel at a predetermined rate to a collector. Such a controlled rate is continuously injected into the alkaline solution while simultaneously collecting microprecipitated and finely divided photographically useful compounds. Suitable components may be present in the collector, such as, for example, dispersants, solvents, hydrophilic colloids or combinations thereof, which are avoided during the “microprecipitation and milling process” for any reason. Or a much lower concentration therein. The method according to the invention is characterized by "during microprecipitation and / or
Alternatively, to further reduce the formation of agglomerates in the microprecipitation and milling process, a sonication process is recommended, for example, when a small amount of hydrophilic colloid is used for viscosity reasons. It is performed during and / or after the precipitation step and / or the pulverization step, for example, after the above-mentioned "during and / or after the microprecipitation step, the microprecipitation and pulverization step", an ultrasonic treatment step can be performed in the collector.

The milling step may be a microprecipitation method and / or a later well-known mechanical milling technique (eg ball milling,
Roll milling, pearl milling, basket milling or microfluidization), said steps being so-called "ball mill", "sand mill", "pearl mill",
It is carried out in a corresponding "pulverizing device" such as, but not limited to, a "basket-mill" or "roll mill" device. The photographically useful compounds are preferably microprecipitated and milled separately or together during and / or after microprecipitation in the presence of gelatin. The presence of a hydrophilic colloid different from gelatin is not thereby excluded. Suitable hydrophilic colloids are the same as those described above.

The process according to the invention for producing dispersions of photographically useful compounds leads to dispersion particle sizes of less than 500 nm. To achieve a particle size below 500 nm by applying only the acidification step of an alkaline solution (a coating solution or another solution containing at least one photographically useful group), a well-defined pH is used. Microprecipitation under the conditions is required. Thus, a pH fixation device can be used to control these conditions, but the rate at which the acidic solution is added is also important. Both conditions determine not only the ultimate particle size of the microprecipitated particles, but also the photographic activity, for example, as in the case of dye particles. In that case, they determine the absorption for a particular wavelength range, for example, 370-700 nm, depending on their chemical structure. Thus, according to the present invention, the application of a milling step during and / or after microprecipitation to further reduce particle size is required.

As a result, a particle size of 0.05 to 0.50 μm, more preferably 0.10 to 0.45 μm, can be achieved in an economically justified manner without the presence of undesirable agglomerations. Undesirable flocculation requires a filtration step before addition of the dispersion to the coating solution and results in coating fading.
failures). In contrast, in the case of dyes prepared according to the process of the invention, for example in the form of a dispersion, a marked increase in their absorption efficiency is observed, the transparency of the hydrophilic layer of the photographic material over which they are coated. And reduce scattering of incident light, thus improving sharpness.

[0034] In the case of the example dyes, the amount commonly used in the hydrophilic layer of the photographic material is 10 to 500 mg / m ^2, more preferably from 100 to 300 mg / m ^2.

For example, in the case of a dye dispersion, for example, 37
The preferred absorption concentration in the well-defined wavelength range of 0-700 nm is at least 0.3, more preferably at least 0.6. Obviously, finely dispersed dye particles require a small coverage of the dye to achieve a suitable absorption concentration. Further, during processing of a silver halide photographic material containing a dye prepared according to the method of the present invention, in an alkali developer, the finer the alkali-soluble dye particles, the faster the bleaching will occur, and It is clear that it is more easily removed. It is clear that this is preferred, for example, for rapid processing applications of photographic materials coated with dye dispersions prepared according to the process of the invention.

In order to remove the salts formed during the microprecipitation, it is particularly recommended to reduce the coating fade due to the presence of said salts by a desalination step after the microprecipitation step. Its presence can lead, for example, to tack development. The desalting step is preferably performed by, for example, dialysis, ultrafiltration, or the like, but is not limited thereto.

According to the process of the present invention, high concentrations of photographically active compounds in dispersed form can be obtained. Suitable concentrations are 0.5 to 15% by weight, more preferably 1 to 10% by weight and even more preferably 2 to 10% by weight. Application of the above desalting method is recommended to increase the concentration.

The advantages resulting from the use of a dispersion of the photographically useful compound prepared by the process of the present invention are not only economical, such as, for example, concentration enhancement and storage functions, but also allow the use of small amounts of hydrophilic colloids. There is also that. Since the said amount of hydrophilic colloid is introduced together with the dispersion into the coated hydrophilic layer, the reduction of said amount is necessary, for example, in applications where an extremely thin layer substantially free of gelatin used as a binder is required. Is very preferred. Accordingly, it is preferred in that case that the dispersing aid is not present if possible.

When, for example, a dye dispersion is prepared according to the invention, said dispersion comprises one or more dyes to be incorporated in at least one hydrophilic layer of a silver halide photographic material, a separate dispersion. It can be included whether it results from mixing, or co-precipitation and milling. In particular, at least one oxonol dye is present in the dispersion prepared according to the method of the present invention. In a preferred example, at least one oxonol dye corresponding to the following formula (I) can be present, and at least one melostyryl dye corresponding to the formula (II) can be present.

Suitable oxonol dyes for use in dispersed form wherein the dispersion is prepared according to the process of the present invention are represented by general formula (I):

Embedded image Wherein m = 0, 1 or 2; each of R ¹ and R ² is independently hydrogen, (substituted or unsubstituted) alkyl, (substituted or unsubstituted) aryl, COOR ³ , NHCOR ⁴ or N
HSO ₂ R ⁵ , R ³ represents hydrogen or alkyl, each of R ⁴ and R ⁵ independently represents alkyl or aryl, and at least one of R ¹ and R in formula (I)
² has an ionizable group.

In a preferred example of the oxonol dye in the general formula (I), m = 2, R ¹ = p-carboxyphenyl, and R ² = CH ₃ .

The oxonol dye is, for example, US-P4
092168 and 4288534.

Suitable merostyryl dyes, optionally present, are represented by the following general formula (II):

Embedded image Wherein n represents 0 or 1; each of p and q independently represents 0, 1 or 2; Q represents the atoms necessary to form an acidic nucleus; each of R ¹ and R ² Are each independently hydrogen, a (substituted or unsubstituted) alkyl group, a (substituted or unsubstituted) aryl group, COOR ³ , NHCOR
⁴ or NHSO ₂ R ⁵ , R ³ represents hydrogen or a (substituted or unsubstituted) alkyl group, and R ⁴ and R ⁵ each independently represent a (substituted or unsubstituted) alkyl group, or (substituted or unsubstituted). It represents a non-substituted) aryl group; X represents oR ^6, SR ⁶ or NR ⁷ R ^8, R ⁶
Represents H, a (substituted or unsubstituted) alkyl group, or a (substituted or unsubstituted) aryl group; R ⁷ and R ⁸ may be the same or different; represents a (substituted or unsubstituted) aryl group, or atoms necessary to form a ring together with the C atom of the phenylene ring in ortho position with respect to the N atom and the N atom to which they are attached or R ⁷ And R
⁸ together can represent the atoms necessary to form a ring with the N atom to which they are attached; L ₁ , L ₂ , L ₃
Represents (substituted or unsubstituted) methine (provided that when it is substituted, at least one of L ₁ , L ₂ or L ₃ is —CONR ⁹ R ¹⁰ , —CON (R ¹¹ ) —,
—COOR ⁹ , which must be substituted by CN), R ⁹ and R ¹⁰ may be the same or different and represent hydrogen, a (substituted or unsubstituted) alkyl group or a (substituted or unsubstituted) aryl group. R ¹¹ represents an atom necessary for forming a ring with the aforementioned Q atom;
At least one of the ¹ to R ¹¹ contains an ionizable group. Preferably the ionizable group is located in R ^2.

In the above formula (II) of the merostyril dye, the acidic nucleus is pyrazoline, barbituric acid, thiobarbituric acid,
Preference is given to rhodanine, hydantoin, oxazolidinedione, thio-oxazolidinedione or isoxazolinone.

In a more preferred example of the above-mentioned merostyril dye in the formula (II), the necessary atom represented by L ₁ -L ₃ is mono- or trimethine.

The dye according to the general formula (II) is, for example, EP-A
0586748, 0587230, US-P53447
49 and EP-A 0 656 401.

According to the present invention, for example, a dispersion of the dye prepared according to the method of the present invention is incorporated into at least one hydrophilic colloid layer of a silver halide photographic material having an absorption spectrum in the range of 370 to 700 nm. It is especially conceivable that the merostyril dye may be present in the dispersion mixture, especially in the "microprecipitated-milled" form. The amount of per 1m ² of the oxonol dye is about 0.1g
(That is, 0.09 to 0.11 g).
If more deep-color absorbing dyes are required to cover a wider range of absorption spectra, at least one merostyryl dye is required in the dispersion, in which case the merostyril dye corresponding to formula (II) The amount per 1 m ² is 0.1 to 0.3 g. In that case, the weight ratio of at least one melostyryl dye corresponding to the formula (II) and at least one oxonol dye corresponding to the formula (I) is at least one hydrophilic colloid layer of the silver halide photographic material. The ratio is preferably from 3: 1 to 1: 1.

Suitable hydrophilic layers in which photographically useful compounds are used, such as, for example, dye dispersions prepared according to the process of the invention, are non-light-sensitive and light-sensitive layers in the case of dyes, for example An antihalation subbing layer coated between the support and a silver halide emulsion layer closer to the support; one or more silver halide emulsion layers; one or more intermediate layers between the silver halide emulsion layers in a multilayer arrangement. Layer: a protective layer which may be composed of a filter layer or one or more layers between the emulsion layer and the protective layer farthest from the support. Any combination is possible depending on the special conditions of each material. The components used in the dye-containing layer and other layers of the silver halide photographic material are Research Disclosures RD17
643, 23-28; RD 18716, 648-65
1 page; RD308119, 996-1009 and RD
36544, 501-541, which are incorporated herein by reference. Those having an ionizable acid site on an ionic molecule from these components are preferably produced by the method of the present invention.

Suitable silver halide photographic materials coated from layers capable of using the dispersions of photographically useful compounds prepared according to the process of the invention are coated on one or both sides of a support, for example EP -Application No. 95201822
(A radiographic material, a microscopic material, a double-sided coating material, a material for use in graphic applications, a color material, etc.) having a multilayer arrangement as described in (filed on Jul. 4, 1995).

In a particularly preferred embodiment of the invention, apart from the dispersion of the photographically useful compound, a dye dispersion is incorporated into the non-photosensitive hydrophilic colloid layers of the radiographic material, said layers being on both sides of the support. Is provided with a silver halide emulsion layer and a stress-resistant layer as a protective stress-resistant layer coated thereon. The radiographic material is preferably separated on two sides of the film support into two distinct emulsion layers having different average grain size silver halide crystals, one being a high speed emulsion layer and the other being a low speed emulsion layer. It has a silver halide emulsion and the high-speed emulsion layer is provided at a greater distance from the support than the low-speed emulsion layer. In this way, the sensitivity measurement curve can be fine-tuned, giving the complete profile required for a particular use. The layer arrangement can also be reversed in order to obtain higher contrast. Even without the use of additional anti-crossover layers, this layer arrangement reduces crossover, especially in critical low concentration regions. In the presence of an antihalation undercoat layer to prevent crossover, the layer containing the dispersion, particularly the dye dispersion, prepared according to the method of the present invention, when processed, is a reference for the material, especially at high throughput. Immediate processing with a processing time of less than 60 seconds, preferably 45, 38 or 30 seconds, improves the crossover reduction without leaving color contamination.

One or more backing layers may be present in the one-sided coating material, one or more of which may contain at least one photographically useful group of dispersions prepared according to the method of the present invention. .

Further, in order to prevent the dye from migrating successively into the layers, the coating pH is less than 6.5, preferably 5.5 to 5.5.
It is particularly desirable to have a value of 6.5.

The combination of a film symmetrically double-coated with a symmetric or asymmetric set of intensifying screens, or a combination of a film double-coated with an asymmetric emulsion layer with or without a double coating is an intensifying screen. In combination with a symmetric or asymmetric set of Said material comprises at least one dispersion of at least one photographically useful compound produced by the method according to the invention.

In another example, the dye dispersion produced by the method of the present invention is incorporated into a coated optical photoconductive layer from a non-aqueous coating solution.

Suitable supports used for the material are the RD36544 and for example EP-A061951.
4 can be found. Particularly preferred supports are polyethylene terephthalate and polyethylene naphthalate.

[0056]

EXAMPLES The present invention will be described with reference to the following examples, but the effects obtained by the present invention are not limited to these examples.

Example 1 Preparation of dispersion of fully protonated dye I-1:

Embedded image

1. Microprecipitation step: about 5.2% by weight of the aqueous solution of the dye I-1 was stirred for about 45 wt.
Prepared by dispersing 30 g of fully protonated dye in 0 g of distilled water. About 99 ml of 2N
Aqueous aOH was added at a rate of about 9 ml / min to give a final pH of about 9. The solution was filtered to remove undissolved contaminants, leaving about 24 hours without chemical degradation of Dye I-1.
Time could be stored.

Microprecipitation was performed by pouring 54 ml of a 6N aqueous sulfuric acid solution into the raw material solution. The raw solution was stirred with a high shear mixer while pouring into the aqueous acid, and the two solutions were mixed very efficiently. After this microprecipitation step, the suspension was heated to 40 ° C. while stirring with an axial flow
Was added to give a pH value of about 5.2. This suspension was mixed with a 20% by weight aqueous gelatin solution and then pulverized with a ball mill to form a stable dispersion. 0.6-0.8 μm zirconium oxide pearl was used as the milling material.

Comparative Dispersion 1: A comparative dispersion was prepared as described above except for the milling step: to obtain a stable dispersion, after mixing a suspension of dye I-1 with a 20% by weight aqueous gelatin solution. No pulverization was performed at all with a ball mill.

Comparative Dispersion 2: A comparative dispersion was prepared by bead milling fully protonated dye I-1. Water (38 ml), about 2 g of gelatin and about 10 ml of dispersion "Hostapon" (Hoec
hst, trademark product from Frankfurt, Germany) 10% by weight
The solution was placed in the reaction vessel. About 5 g of fully protonated dye I-1 was added with stirring in a high shear mixer. This suspension was then comminuted in a bead mill. The milling time of this comparative dispersion was 4 times longer than in the example with the microprecipitated protonated dye I-1. The resulting suspension was then mixed with a 20% by weight solution of gelatin to give a more stable dispersion.

Evaluation of dispersion: The results are shown in Table 1.

[Table 1]

It is generally known that dispersions of antihalation dyes of smaller particle size produce better properties in the coated film.

It is generally known that dispersions of antihalation dyes containing a large number of particles having a particle size of 5 μm or more give rise to a number of problems with the low transparency of the film in coated films.

If these large particles were filtered before forming the coated film, the process for producing Dye I-1 would be less efficient.

Example 2 Preparation of a dispersion of a fully protonated dye II-1

Embedded image

Microprecipitation: 50 ml distilled water and 60 ml
Of a 2N NaOH aqueous solution to about 20 g of fully protonated dye II-1 produced a stock solution of about 15% by weight of dye II-1. About 4
The mixture was stirred with an axial flow blade while heating to 5 ° C. Final pH was about 12.0. The solution was filtered to remove insoluble products.

Microprecipitation was performed by pouring 25 ml of sulfuric acid 6N into the raw material solution. While pouring into the aqueous acid, the raw solution was vigorously stirred with a high shear mixer to achieve very efficient mixing of the aqueous acid and the raw solution. After this fine precipitation, the high shear mixer was washed using about 100 ml of distilled water to obtain a low viscosity suspension.

This suspension was mixed with about 9.8% by weight of an aqueous gelatin solution and 25 ml of a dispersant “Aerosol OT” (America).
n Cyanamid (trademark product) was added to a solution consisting of a dispersant (1% by weight) and about 25 ml of 2N aqueous NaOH. While the suspension was being added to the solution, mixing was performed with axial flow blades and heating at a temperature of about 45 ° C. The resulting suspension was then finely pulverized with a bead mill to form a stable dispersion.

Comparative Dispersion 3: A comparative dispersion was prepared by bead milling fully protonated dye II-1. About 57 ml of water and about 100 ml of dispersant "Ae
rosol OT "(trademark product from American Cyanamid)
A mixture of the above solutions (1% by weight) was prepared. To this solution was added about 20 g of fully protonated dye II-1 while stirring with a high shear mixer. This suspension was then comminuted in a bead mill. The milling time of this comparative dispersion was eight times longer than in the example with the microprecipitated protonated dye II-1. The resulting suspension was then mixed with a solution of gelatin (7.2% by weight) to obtain a more stable dispersion.

Evaluation of the dispersion: Table 2 shows the results obtained for the particle size of the filter dye.

[Table 2]

It is generally known that dispersions of filter dyes having smaller particle sizes have much higher dye yields. As a result, low amounts of dispersed dye are required to obtain sufficient absorption with said amount of filter dye coated in at least one hydrophilic layer of the photographic material. Furthermore, the processing time of the photographic material can be reduced, since the residual amount of the dye dispersed according to the method of the invention is removed more quickly.

Example 3 Preparation of fully protonated dye III-1 and fully protonated dye IV-1

Embedded image

[Chemical 6]

Microprecipitation: by dispersing 40 g of fully protonated dye III-1 in about 824 g of distilled water while stirring with an axial flow blade about 4% by weight of an aqueous starting solution of dye III-1. Manufactured. About 176ml of 2N
An aqueous solution of NaOH is added at a rate of about 15 ml / min.
A final pH value of 5 was obtained. The solution was filtered to remove undissolved residue and could be stored for about 10 days without chemical degradation of dye III-1.

About 6.4% by weight of the aqueous raw material solution of Dye IV-1 was added to about 930 g of distilled water while stirring with an axial flow blade.
Prepared by dispersing 0 g of fully protonated dye. About 230 ml of 2N aqueous NaOH was added at a rate of about 15 ml / min, giving a final pH value of about 9.1. The solution was filtered to remove undissolved residue. The aqueous raw material solutions of Dye IV-1 and Dye III-1 were poured together at a volume ratio of 1.25: 1.00 and mixed for a while. Microprecipitation was performed by pouring 114 ml of 6N aqueous sulfuric acid into the mixture of raw material solutions. During the pouring step, the raw solution mixture was agitated with a high shear mixer, resulting in extremely efficient mixing of the solution. After this micro-coprecipitation step, the suspension was heated to 43 ° C. while stirring with a high shear mixer and about 40 ml of 2N aqueous NaOH was added to give a final pH of about 5.1. This suspension was mixed with a 24% by weight aqueous solution of gelatin, and then pulverized with a bead mill. A stable dispersion was obtained.

Comparative Dispersion 4: A comparative dispersion was prepared in the same manner as described above without the milling step in a bead mill. A stable dispersion was obtained.

Evaluation of dispersion: The results are shown in Table 3.

[Table 3]

It is generally known that dispersions of filter dyes having smaller particle sizes have much higher dye yields. The same results as described above in Example 2 can be derived from Example 3.

Embodiment 4 4.1. Preparation of dispersion of fully protonated dye V-1:

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Microprecipitation: 5 l ethanol and approx. 25 l
Of distilled water of 5 kg of fully protonated dye I-1
About 12% by weight of dye I-1 in aqueous stock solution are prepared by adding to 6.4 l of N 4
Add an aqueous solution of aOH 2N at a rate of about 3 l / min to give about 1
A final pH value of 0.3 was given. The solution was filtered to remove undissolved residue and could be stored for at least 60 minutes without chemical degradation of dye V-1.

490 ml of the solution of dye V-1 in a mill
The microprecipitation was carried out on a bead mill by simultaneously sending a 6N aqueous solution of sulfuric acid at a rate of 60 ml / min from an adjacent site near the solution of Dye V-1 into the mill device at a rate of 60 ml / min. Meanwhile, the bead mill was stirred at a normal operation speed. 0.6-0.8 μm zirconium oxide pearl was used as the milling material.

After the "microprecipitation-milling" method, a 12.8% by weight gelatin solution was added to coagulate the resulting dispersion.

4.2. Operate with the same dye V-1, but
"Microprecipitation-milling" in the presence of gelatin solution. 3
By adding 30 ml of distilled water to 50 g of fully protonated dye V-1, about 11% by weight of dye V
-1 of the raw material aqueous solution, and with stirring, about 7
2 ml of a 2N aqueous NaOH solution was added at a rate of about 15 ml / min to give a final pH of about 10.8. The solution was filtered to remove undissolved residue. Thereafter, the solution was heated to 45 ° C. and 510 ml of an aqueous gelatin solution (9.7% by weight) was mixed into the solution by means of an axial blade. 22.5 ml of H ₂ SO ₄ at a rate of about 60 ml / min
Microprecipitation was carried out on a bead mill under normal operating conditions while circulating a mixture of gelatin solution and dye V-1 solution at a rate of 2.5 l / min by sending a 6N aqueous solution into the mill. 0.6-0.8 μm zirconium oxide pearl was used as the milling material. After a while, the suspension was collected and cooled to obtain a solidified dispersion.

4.3. Comparative Dispersion 5 Example 4.2. Aqueous solution of gelatin and dye V
A comparative dispersion was made by making the same mixture of the -1 solutions.

About 22.5 ml of sulfuric acid 6 was added to the above mixture.
Microprecipitation was performed by pouring an aqueous solution of N. The mixture was stirred with a shear mixer while pouring the aqueous acid solution, resulting in extremely efficient mixing of the solution. After this microprecipitation step, Example 4.2. The suspension was subsequently pulverized in a bead mill under the same operating conditions as described in (1). Therefore, no microprecipitation occurred in the mill equipment. After cooling, a coagulated dispersion was obtained.

Evaluation of dispersion: The results are shown in Table 4.

[Table 4]

It can be concluded from Table 4 that it is possible to obtain a dispersion having particles of sufficiently small average particle size.

It can also be concluded that the microprecipitation performed in the mill results in a much smaller average particle size compared to the microprecipitation by pulverization of the separately microdispersed dispersion in a subsequent step.

According to the invention, the microprecipitations carried out in the mill have a much smaller number of agglomerated particles, as can be seen from Table 4. Further, the number of aggregates obtained is determined by the chemical structure of a photographically useful compound such as Dye V-1 used in this example.

Embodiment 5 5.1. Preparation of a dispersion of fully protonated dye V-1 in the absence of a dispersing aid. Microprecipitation: Examples 4, 4.1. Did the same as

5.2. Operate with the same dye V-1, but
"Microprecipitation-milling" in the presence of pre-added gelatin solution. Microprecipitation: Examples 4, 4.2. Did the same as

5.3. Operate with the same dye V-1, but
"Pulverize after microprecipitation" in the presence of a dispersing aid different from the gelatin added before microprecipitation. An aqueous starting solution of about 11% by weight of dye V-1 is prepared by adding 333 ml of distilled water to 50 ml of fully protonated dye V-1 and, with stirring, about 67 ml of N 2
An aqueous solution of aOH 2N was added at a rate of about 15 ml / min to give a final pH value of about 10.1. The solution was filtered to remove undissolved residue and could be stored for at least about 60 minutes without chemical degradation of Dye V-1. 2
5 ml of the dispersing aid "Alkanol XC (trademark product of Du Pont)" was added to the solution before microprecipitation. The microprecipitation was performed by pouring about 22.5 ml of 6N aqueous sulfuric acid into the above mixture. While pouring into the aqueous acid, the mixture was stirred with a shear mixer to provide a very efficient mixing of the solution. After this precipitation step, the suspension is heated to about 43 ° C. while stirring with an axial flow blade, and about 50 ml of 9.7 are obtained.
A weight-% gelatin solution was mixed to obtain a coagulated dispersion.

Evaluation of Dispersion The results are shown in Table 5.

In Table 5, the volume ratios relate to the reference volume set equal to 1.0 for Example 5.1 before microprecipitation. The volumes obtained for the other examples before and after microprecipitation are relevant.

[0095]

[Table 5]

As can be seen from Table 5, dispersions having substantially the same particle size, that is, having the same photographic characteristics can be obtained.

Dispersing aids (especially 6.2.
It is also evident that achieving microprecipitation in the absence of dispersing aids is of greatest interest from an economic point of view, since the volume ratio before and after precipitation is always high when (see).

Embodiment 6 6.1. Preparation of a fully protonated dispersion of dye II-1. Microprecipitation: 50 ml of distilled water and 60 ml of NaOH
About 2Og of a fully protonated dye in 2N aqueous solution
By adding to II-1, a 15% by weight aqueous starting solution of dye II-1 was prepared. The solution was stirred with an axial flow blade while heating to about 47 ° C. Final pH was about 12.0. The solution was filtered to remove undissolved product.

Microprecipitation was performed by pouring 25 ml of a 6N aqueous solution of sulfuric acid into the raw material solution. While pouring the aqueous acid solution, the raw material solution was stirred with the axial flow blade, and the aqueous acid solution and the raw material solution were extremely efficiently mixed. After the fine precipitation, the axial flow blade was washed using about 100 ml of distilled water to obtain a low-viscosity suspension.

The suspension was mixed with about 9.8% by weight of gelatin water and about 25 ml of “Aerosol OT” (American Cyana).
trademark product from mid) solution dispersant and about 25 ml of N
Added to a solution consisting of aOH 2N aqueous solution. Mixing was performed with an axial flow blade while adding the suspension to the solution, and the mixture was heated to a temperature of about 47 ° C. The resulting suspension was then pulverized with a bead mill to form a stable dispersion.
0.6-0.8 μm zirconium oxide pearl was used as the milling material.

6.2. Example 6.1. Except for using a high shear mixer during microprecipitation. Comparative dispersions were prepared in the same manner as described above.

6.3. Example 6.1. During microprecipitation, except that an ultrasonic device was used to create a micromixed flow. Comparative dispersions were prepared in the same manner as described above.

Evaluation of the dispersion: The results for the particle size of the filter dye particles in dispersed form are given in Table 6.

[Table 6]

This example shows that the average particle size of the fine precipitate can be monitored as a function of the mixing device. Table 6
It can be seen that the energy per volume input to the microprecipitation vessel increases from the axial flow blade toward the ultrasonic mixing device by selecting a mixing device as described in. As a result, when more samples are made (five samples made by each mixing technique), the average particle size decreases as well as its standard deviation.

The amount of dispersion required to obtain sufficient absorption by the filter dye is small, as the finely dispersed particles yield the dye in much higher yields. Furthermore, in actual coatings the processing time of the exposed silver halide photographic film is reduced without residual dye staining.

Front Page Continuation (72) Inventor Jean Gière, Septerrato, Mortzel, Belgium 27 Agfa Gewert Namrose Rose Bennault Chap

Claims (10)

[Claims] 1. A method of preparing a dispersion of photographically useful compounds, said compound having at least one ionizable acid site on its molecule, said method comprising: Deprotonating and solubilizing with, microprecipitating the compound, -milling the microprecipitated compound, -a photographically useful compound in the non-photosensitive and / or photosensitive hydrophilic layer of the silver halide photographic material. Of the above dispersion, wherein fine pulverization is carried out during and / or after the microprecipitation step. 2. The method according to claim 1, wherein the microprecipitation step is carried out in the presence of at least one dispersant and / or at least one hydrophilic colloid. 3. A sonication step is performed during and / or after the microprecipitation step and / or the pulverization step.
Or the method of 2. 4. A method according to any of claims 1 to 3, wherein during microprecipitation the energy input is provided by low shear mixing, high shear mixing or axial flow vane mixing. 5. The method according to claim 1, wherein a desalting step is performed after the microprecipitation step. 6. The method according to claim 5, wherein the desalting step is performed by dialysis or ultrafiltration. 7. The method according to claim 1, wherein the finely pulverizing step is performed by a ball mill, a sand mill, a pearl mill, a basket mill or a roll mill device. 8. The method according to claim 1, wherein the particle size of the photographically useful compound in dispersed form is 0.10 to 0.45 μm. 9. The method according to claim 1, wherein the concentration of the photographically useful compound in the dispersion is 0.5 to 15% by weight. 10. The coating pH of the hydrophilic layer is 5.5 to 5.
The method according to any one of claims 1 to 9, which is 6.5.