JPH08292509A - Method for emulsifying and dispersing hydrophobic photographic useful compound - Google Patents

Abstract

PURPOSE: To prevent occurrence of grain growth and the like in storage with the lapse of time without changing fine particle characteristics by specifying the viscosity of a water-insoluble phase, in dispersing the water-insoluble phase containing the photographic useful compound into water or the like. CONSTITUTION: The water-insoluble phase containing the water-insoluble photographic useful compound is dispersed into water or a hydrophilic colloid composition by controlling the viscosity of the water-insoluble phase to 100-1,000,000Poise in a shering speed of 10sec<-1> at a storing temperature of the dispersed phase and, for this purpose, by adding a high-molecular substance such as synthetic polymer as a thicker to the water-insoluble phase comprising the photographic useful compound, a high-boiling solvent, and a low-boiling organic solvent to enhance the apparent viscosity, thus permitting the obtained dispersed composition not to cause grain growth or occurrence of coarse grains or precipitation of crystal without changing fine particle characteristics.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for dispersing a photographically useful compound used in a silver halide photographic light-sensitive material.
More specifically, it relates to a method for stably emulsifying a hydrophobic photographically useful compound in water or in a hydrophilic colloid composition.

[0002]

2. Description of the Related Art A photographic light-sensitive material has a hydrophilic colloid layer containing a hydrophobic photographic useful compound on a support.
The useful compounds for hydrophobic photographic use are, for example, image forming couplers, colored couplers, development inhibitor releasing couplers, anti-fading agents, anti-foggants, ultraviolet absorbers, photographic dyes or anti-color mixing agents. Generally, hydrophobic photographic useful compounds are incorporated into photographic light-sensitive materials by the method of dissolving these compounds in a high boiling organic solvent called an oil protect method or by emulsifying and dispersing them, or by solidifying without using an organic solvent. Direct dispersion in the state, or British Patent 1,19
3,349, RD-16,468, U.S. Pat. No. 2,87.
0,012, European Patents 361,322, 347,
As shown in each specification such as No. 837, a method has been adopted in which a hydrophobic photographic useful compound is dissolved in a water-miscible organic solvent or a basic aqueous solution and then precipitated and dispersed as fine particles in water.

[0003]

In any of the methods, in order to effectively use expensive photographic compounds,
In order to increase the surface area per unit weight of dispersoid, it is necessary to disperse the particles into particles of less than 1 μm, and it is the fate of general colloidal dispersion that the stability of the dispersion deteriorates with the increase of the number of particles and the interfacial area. In addition to the quality of photographic performance, the coating quality was deteriorated not only by the quality of photographic performance but also by the generation of coarse particles and lumps caused by crystallization of the hydrophobic compound. These problems particularly occur during the storage of the above dispersion, and in the case of containing gelatin, both during storage of the gelatin aqueous solution below the gelling temperature and storage above the melting point of the gel. Therefore, there has been an uneconomical situation in which the aging period for management is limited, and in some cases the dispersion prepared with great care must be discarded.

In order to solve the above-mentioned conventional problems, the present invention aims to provide a dispersion which maintains the performance of fine particles at the time of dispersion and does not cause particle growth or generation of coarse particles or precipitated crystals during storage over time. It is to provide an emulsification method that can be obtained.

[0005]

As a result of intensive studies, the present inventors have found that the above-mentioned object of the present invention can be achieved by the following. (1) In a method of dispersing a water-insoluble phase containing a hydrophobic photographic useful compound in water or a hydrophilic colloid composition, the viscosity of the water-insoluble phase at the storage temperature of the prepared dispersion is 10 sec ^-1. A method for emulsifying and dispersing a hydrophobic photographically useful compound, which comprises preparing and using a water-insoluble phase so that the shear rate is 100 Poise or more and less than 1,000,000 Poise. (2) In the method of dispersing a water-insoluble phase containing a hydrophobic photographically useful compound in water or a hydrophilic colloid composition, the viscosity of the water-insoluble phase at the storage temperature of the prepared dispersion is 10 sec ^-1. Emulsifying and dispersing a useful compound for photographic photography, characterized in that a water-insoluble phase is prepared and used by adding a thickening agent to the water-insoluble phase so that the shear rate is 100 Poise or more and less than 1,000,000 Poise. Method. (3) In a method of dispersing a water-insoluble phase containing a hydrophobic photographic useful compound and a low boiling point organic solvent in water or a hydrophilic colloid composition, the viscosity of the water-insoluble phase at the storage temperature of the prepared dispersion Is prepared and used by removing the low boiling point organic solvent during or after dispersion in water or the hydrophilic colloid composition so that it becomes 100 Poise or more and less than 1,000,000 Poise at a shear rate of 10 sec ^-1. A method for emulsifying and dispersing a useful compound for hydrophobic photography, which is characterized by: Achieved by

The details of the present invention will be described below. INDUSTRIAL APPLICABILITY The present invention is effective when a hydrophobic photograph useful compound (hereinafter sometimes referred to as a hydrophobic compound or a photograph compound) is finely dispersed in a fine particle. Specifically, the effect is remarkable when performing dispersion with an average particle size of less than 1 μm and a volume fraction of dispersoid of 10% or more. In the emulsified dispersion of the present invention, generally, a high-boiling point organic solvent having a boiling point of about 175 ° C. or higher or a low-boiling point organic solvent having a boiling point of about 30 ° C. to about 150 ° C. is used singly or as a mixture of both at an arbitrary ratio. Thus, the hydrophobic compound is dissolved, and then dispersed in water or in the hydrophilic colloid composition. However, in the process of preparing such an emulsified dispersion, and the process of storing the finished emulsified dispersion,
It was often experienced that hydrophobic compounds crystallize from the water-insoluble phase to grow into coarse particles. The reason for this is that the hydrophobic photographic useful compound such as an image forming coupler generally has a large molecular weight of 500 or more, and the molecular structure is extremely complicated, so that it is difficult to be stably dissolved in an organic solvent. Furthermore, in order to achieve image quality such as sharpness and graininess required for photographic materials in recent years, it is necessary to incorporate a photographic compound in a light-sensitive material film at a high density, and for that purpose, particles in an emulsion dispersion are used. This is because it is not uncommon for the concentration of the photographic compound inside to be set above the saturation solubility. When the emulsified dispersion under such conditions is stored, crystallization of the photographic compound proceeds in each dispersed particle, and finally the entire dispersion is in a precipitated state. Needless to say, when a photographic emulsion containing this emulsified dispersion is applied, defects such as spots frequently occur and the value as a product is impaired.

As a result of analyzing the details of the precipitation mechanism of an emulsion in which a water-insoluble phase having a composition that easily crystallizes is dispersed, we have found that the viscosity of the water-insoluble phase has a great influence. That is,
Even in a situation where the degree of supersaturation is high and crystal nuclei are easily generated, if the viscosity of the water-insoluble phase is sufficiently high, the movement of solute molecules is restricted, and the crystal growth rate becomes slow. If the viscosity of the water-insoluble phase is sufficiently high, it is possible to avoid any substantial deterioration of the coating quality, since no significant crystal growth occurs during the normal storage period of the emulsified dispersion. In order to maintain a storage period of about 3 months for various photographic compounds and organic solvent compositions, the viscosity of the water-insoluble phase is set to a shear rate of 10 se.
It was demonstrated that at c ^-1 , it must be at least 100 Poise or more.

There are three ways to achieve this viscosity range of the water-insoluble phase. The first is a method of increasing the apparent viscosity by adding a polymer such as a synthetic polymer as a thickener in addition to a useful photographic compound, a high-boiling organic solvent, and a low-boiling organic solvent which usually constitute a water-insoluble phase. . Secondly, the initial water-insoluble phase contains a large amount of low-boiling point organic solvent and therefore has a low viscosity, but the low-boiling point solvent is removed during or immediately after the dispersion to increase the solute concentration and increase the viscosity. How to increase. Third, the melting point of the photographic compound is 1
When the temperature is lower than 00 ° C, the viscosity of the water-insoluble phase is increased by emulsifying and dispersing at a temperature near its melting point and then cooling to a normal storage temperature of 5 ° C to 60 ° C, preferably 5 ° C to 40 ° C. There is a method of making it. According to our research results, a shear rate of 10 se is obtained using either of the above methods.
The viscosity of the water-insoluble phase at storage temperature at c ^-1 is 100 Po.
If ise or more, no formation of deposits that would deteriorate the coating quality was observed during the storage period of 3 months. However, it can be said that the means for emulsifying and dispersing at a temperature near the third melting point is not a general-purpose method as compared with the other two methods because the melting point is determined by the photographic compound itself.

The viscosity of the water-insoluble phase in the present invention can be measured by any method such as a capillary type or a double cylinder type, as long as the shear rate can be regulated, and a cone-plate type E type is particularly preferable. Viscometer has a shear rate of 10
In sec ^-1 , it is preferable in that the viscosity of 1 to 100,000 Poise can be evaluated easily and accurately. In addition, since this viscosity is not measurable because the water-insoluble phase is divided into fine particles after the emulsification and dispersion, it is measured before the emulsification and dispersion, and the formulation is designed so that the viscosity of the present invention is obtained. There is a need to.

The higher the viscosity of the water-insoluble phase at a shear rate of 10 sec ^-1 , the slower the molecular motion of the photographic compound, and the higher the effect of preventing crystallization, but the extremely high viscosity results. When approaching the solid state, various obstacles occur practically. For example, in the method of adding the first thickener in the present invention, if the viscosity of the water-insoluble phase becomes too high, the emulsification dispersibility deteriorates and fine particles cannot be obtained. Further, regarding the second method for removing the low boiling point organic solvent in the present invention, in the case where the photographic compound acts like a coupler for image formation or an antifoggant in a photographic light-sensitive material with a chemical reaction, However, there arises a problem that the photographic activity decreases as the viscosity of the water-insoluble phase increases. From the above viewpoint, there is an upper limit to the viscosity of the water-insoluble phase at a shear rate of 10 sec ^-1 , and the viscosity in the present invention is 10
The range is 0 Poise or more and less than 1,000,000 Poise, preferably 100 Poise or more and less than 100,000 Poise, more preferably 1,000 Poise or more 100,0.
It should be less than 00 Poise.

The water-insoluble phase thickener used in the present invention may be any polymer as long as it comprises at least one repeating unit and is water-insoluble and soluble in an organic solvent.
Examples of the types of repeating units forming these include acrylic acid esters, methacrylic acid esters, vinyl esters, acrylamides, methacrylamides, olefins, vinyl ethers and the like. Also,
The polymer in the present invention may be a homopolymer having a single type of repeating unit, or a copolymer or block copolymer composed of two or more types of repeating units. The higher the molecular weight and the degree of polymerization of the polymer, the more the thickening action is enhanced, and the desired viscosity can be obtained even when the amount added to the water-insoluble is small, but on the other hand, the solubility is lowered, so that the polymer It must be set to an appropriate value depending on the type. It is important that the glass transition temperature of the polymer is equal to or higher than the storage temperature of the emulsified dispersion from the viewpoint of keeping the viscosity in the water-insoluble phase as a thickener constant, preferably 40 ° C. or higher, more preferably 60 ° C. The above is desired.

Some specific examples of the thickener used in the present invention will be described below, but the present invention is not limited thereto. (P-1) Poly (2-tert-butylphenyl acrylate) (P-2) Poly (4-tert-butylphenyl acrylate) (P-3) Polymethyl methacrylate (P-4) Polyethyl methacrylate (P-5 ) Polymethylchloroacrylate (P-6) Poly (N-sec-butylacrylamide) (P-7) Poly (N-tert-butylacrylamide) (P-8) Poly (N-tert-butylmethacrylamide) (P -9) Poly (4-biphenyl acrylate) (P-10) Poly (2-chlorophenyl acrylate) (P-11) Poly (4-cyanobenzyl acrylate) (P-12) Poly (3-methoxycarbonylphenyl acrylate) ( P-13) Polyvinyl-tert-butyrate (P-14) Poly (ethylfluoromethacrylate) ( P-15) Methyl methacrylate-vinyl chloride copolymer (70:30) (P-16) Methyl methacrylate-styrene copolymer (90:10) (P-17) Vinyl chloride-vinyl acetate copolymer (6
5:35) (P-18) methyl methacrylate-phenyl vinyl ketone copolymer (70:30) (P-19) methyl methacrylate-acrylic acid copolymer (95: 5) (P-20) methyl methacrylate-acrylic Nitrile Copolymer (70:30) (P-21) Methyl Methacrylate-Styrene-Vinyl Sphonamide Copolymer (70:20:10) (P-22) n-Butyl Methacrylate-Methyl Methacrylate-Benzyl Methacrylate-Acrylic Acid Copolymer (35: 35: 25: 5) (P-23) n-butylmethacrylate-methylmethacrylate-acrylamide copolymer (35: 35: 3)
0) (P-24) n-butyl methacrylate-methyl methacrylate-vinyl chloride copolymer (37:36:27)

The low boiling point organic solvent can be removed by a known method. For example, US Pat. No. 2,322,027,
Emulsification using an aqueous hydrophilic colloid solution having a gelling temperature, such as gelatin, as shown in each specification of No. 2,801,171, No. 2,949,360, No. 3,396,027. In the case of the dispersion, the low boiling point organic solvent is removed by extruding the dispersion in a Nudder shape at a temperature not higher than the gelation temperature and washing with water. Alternatively, JP-A-60-158
No. 437, U.S. Pat. Nos. 5,024,929 and 5,108,
The method using the dialysis membrane shown in each specification of No. 611 is mentioned. Further, as in Japanese Patent Publication No. 61-56010, a method of evaporating and removing the low boiling point organic solvent by a depressurizing operation or a heating operation is also possible.

Among these, in the method of combining the depressurizing operation and the heating operation, various molecular distillation and evaporation devices described in "Chemical Engineering Handbook" (Maruzen Co., Ltd.) edited by the Chemical Engineering Society should be used alone or in combination. However, in either case, the evaporation rate is determined by the temperature and the degree of reduced pressure of the heated emulsified dispersion, and the removal rate of the low boiling point organic solvent changes depending on the operation time. At this time, if the temperature of the emulsified dispersion is too high or the operation time is long,
Care must be taken because the dispersion undergoes thermal deterioration to grow into coarse particles and the photographic compound decomposes. Therefore, the temperature of the emulsified dispersion is less than 60 ° C, preferably 50 ° C.
It is desired to be kept below. The operating time under this temperature condition is less than 60 minutes, more preferably less than 30 minutes. In order to realize the high viscosity range of the water-insoluble phase, which is the object of the present invention, within this temperature and operating time range, it varies depending on the composition of the water-insoluble phase, but the low boiling point at the temperature of the heated emulsion dispersion. It is necessary to set the decompression condition to at least less than 80% of the vapor pressure of the organic solvent, preferably less than 50% of the vapor pressure, and more preferably less than 30% of the vapor pressure.

The hydrophobic photographically useful compound that can be used in the present invention means any organic compound and inorganic compound useful for photographic use. The concentration of the hydrophobic photographically useful compound added to the water-insoluble phase is 10% by weight.
To 90, preferably 50 to 80. In the present invention, it is preferable to use an oil-soluble organic photographic substance. Here, oil-soluble means that it is soluble in an organic solvent in an amount of 3% by weight or more at room temperature (20 ° C.). The organic solvent means an organic solvent described in "Solvent Handbook", and examples thereof include methanol, ethanol, isopropanol, butanol, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, tetrahydrofuran, cyclohexanone, benzene. , Toluene, dioxane, acetonitrile, dichloromethane, chloroform and the like.

Hydrophobic photographically useful compounds which can be used in the dispersion of the present invention include dye image-forming couplers, dye image-donating redox compounds, anti-stain agents, anti-foggants, ultraviolet absorbers, anti-fading agents and anti-color mixing agents. Agents, nucleating agents, dye image stabilizers, silver halide solvents, bleaching accelerators, filter dyes and their precursors, dyes, pigments, sensitizers, hardeners, brighteners, desensitizers, Developers, antistatic agents, antioxidants, developer scavengers, mordants, and dispersing oils and dispersing polymers used as a medium for dispersing these, and the like, as the description of these compounds,
Research Disclosure No. 17643, N
o. 18716, No. No. 307105 and the like.

Examples of the disperser used for carrying out the present invention include a high-speed stirring disperser having a large shearing force and a disperser giving high-strength ultrasonic energy. Specifically, there are a colloid mill, a homogenizer, a capillary type emulsifying device, a liquid siren, an electromagnetic distortion type ultrasonic generator, and an emulsifying device having a Paulman whistle. High-speed stirring type dispersers preferred for use in the present invention include dissolvers, polytrons, homomixers, homoblenders, keddy mills,
A main part such as a jet agitator that disperses and rotates at a high speed in the liquid (500 to 15,000 rpm, preferably 2.0).
This is a disperser of the type of (00 to 4,000 rpm).
The high speed stirring type disperser used in the present invention is also called a dissolver or a high speed impeller disperser.
As described in Japanese Patent No. 129136, a preferred example is one in which an impeller in which saw-toothed plates are alternately bent in the vertical direction is attached to a shaft that rotates at high speed.

In preparing the emulsified dispersion containing the hydrophobic compound according to the present invention, various processes can be followed. When the hydrophobic compound is dissolved in an organic solvent, one or two or more kinds selected from high boiling point organic substances described later, water-immiscible low boiling point organic solvent or water-miscible organic solvent is arbitrarily selected. It is dissolved in a multi-component admixture and then dispersed in water or in an aqueous hydrophilic colloid solution in the presence of a surface-active compound. The method for mixing the water-insoluble phase containing the hydrophobic compound and the aqueous phase may be a so-called forward mixing method in which the water-insoluble phase is added to the aqueous phase with stirring, or the reverse mixing method thereof, but especially the reverse mixing method. The phase inversion method, which is one of the above, is preferable in that it gives a finer aqueous dispersion.

In the present invention, the hydrophobic compound can be dispersed either in water or in the hydrophilic colloid composition, but it is preferably dispersed in the hydrophilic colloid composition. As the hydrophilic colloid used in the present invention, a binder or protective colloid usually used in silver halide photographic light-sensitive materials is used. For these, it is useful to use gelatin, but other hydrophilic colloids can also be used. For example, gelatin derivatives, graft polymers of gelatin and other polymers, albumin,
Proteins such as casein; cellulose derivatives such as hydroxycellulose, carboxymethylcellulose, cellulose phosphates; sugar derivatives such as sodium alginate and starch derivatives; polyvinyl alcohol, polyvinyl alcohol partial acetal, poly-N-vinylpyrrolidone, polyacrylic A wide variety of synthetic hydrophilic polymeric substances such as single or copolymers of acids, polymethacrylic acid, polyacrylamide, polyvinylimidazole, polyvinylpyrazole and the like can be used. Examples of high boiling point solvents used in the oil-in-water dispersion method are described in US Pat. No. 2,322,0.
No. 27, International Publication No. WO91 / 17480, and the like. Phthalic acid esters, phosphoric acid or phosphonic acid esters, benzoic acid esters, amides, alcohols or phenols, and aliphatic carvone. Examples thereof include acid esters, aniline derivatives and hydrocarbons.

[0020]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. (Example-1) I-1 and II-1 to II-8 below
Using the liquid, emulsions A-1 to A-8 were prepared by the following method. Solution I-1: Lime-treated gelatin solution (10%) 1000 g Solution II-1: Coupler (Y-1) 100 g Tricresyl phosphate 50 g Ethyl acetate 50 g Sodium dodecylbenzenesulfonate 10 g II-2 Solution: Coupler (Y-1) ) 100 g tricresyl phosphate 50 g ethyl acetate 50 g sodium dodecylbenzene sulfonate 10 g P-1 (MW = 70,000) 5 g II-3 solution: the following coupler (Y-1) 100 g tricresyl phosphate 50 g ethyl acetate 50 g sodium dodecylbenzene sulfonate 10 g P -1 (MW = 70,000) 10 g II-4 solution: the following coupler (Y-1) 100 g tricresyl phosphate 50 g ethyl acetate 50 g sodium dodecylbenzenesulfonate 10 g P-1 (MW = 70,000) 25 g II-5 solution: coupler( Y-1) 100 g Tricresyl phosphate 50 g Ethyl acetate 50 g Sodium dodecylbenze sulfonate 10 g P-1 (MW = 70,000) 40 g II-6 solution: Coupler (Y-1) 100 g Tridecyl phosphate 50 g Ethyl acetate 50 g Dodecylbenzene sulfonic acid Sodium 10g P-7 (MW = 100,000) 30g II-7 liquid: The following coupler (Y-1) 100g Tricresyl phosphate 50g Ethyl acetate 50g Sodium dodecylbenzene sulfonate 10g P-16 (MW = 60,000) 30g II-8 Liquid: The following coupler (Y-1) 100 g Tricresyl phosphate 50 g Ethyl acetate 50 g Sodium dodecylbenzenesulfonate 10 g P-21 (MW = 70,000) 30 g

[0021]

Embedded image

The emulsification method was carried out by mixing and dissolving the liquid I and the liquid II at 60 ° C., and using a dissolver blade having a diameter of 5 cm in a 2-liter container at a rotation speed of 5000 rpm so that the average particle diameter was about 0.15 μm. Stir for ~ 30 minutes.
A NICOMP Model 370 manufactured by Nozaki Sangyo Co., Ltd. using a dynamic light scattering method was used for measuring the average particle diameter. More than 8
The seed emulsion was cooled and gelled, and the degree of crystallization of the coupler was examined when the emulsion was stored at 5 ° C. for a long time. To measure the viscosity of the liquid II, use an E-type viscometer manufactured by Tokyo Keiki Co., Ltd. at 5 ° C.
It was carried out in a temperature-controlled room. To crystallize the coupler, 100 g of an emulsion dissolved at 40 ° C. was sampled, suction filtration was performed using an Epocell filter manufactured by Pall Co., which has a nominal pore diameter of 3 μm, and the weight of the filtration residue accumulated on the filter was determined for comparison. did. The results are shown in Table 1. A-1 of Comparative Example in which no polymer was added and A-2 in which the amount of the polymer added was small and the viscosity was less than 100 Poise.
In A and A-3, remarkable crystallization of the coupler is observed, whereas in the emulsions A-4 to A-8 according to the present invention, only slight crystallization occurs over a long period of time. This demonstrates the excellent emulsion stability according to the invention.

[0023]

[Table 1]

(Example-2) Emulsion A-9 was prepared by the following method using the above-mentioned solutions II and II-9.
Was prepared. Liquid II-9: Coupler (Y-1) 100 g, tricresyl phosphate 100 g, sodium dodecylbenzenesulfonate 10 g

The emulsification method is as follows.
Mix and dissolve at 0 ° C and 80 ° C, and in a 2 liter container kept warm by a hot water jacket at 70 ° C, a dissolver blade with a diameter of 5 cm was rotated at 6000 rpm for 40 minutes so that the average particle diameter was about 0.15 μm. It was stirred. The average particle diameter and the viscosity of the liquid II were measured, and the crystallization of the coupler was evaluated in the same manner as in Example-1. The results of comparison with the emulsion A-1 of Example-1 are shown in Table 2. Coupler Y
The melting point of -1 is about 90 ° C, but in the presence of tricresyl phosphate which is a high boiling point solvent, a stable solution state is obtained even at 70 ° C 47. Even when the stirring rotation speed was increased as compared with the emulsion of Example-1, it took an extra 10 minutes or more to reach the target average particle diameter. It is presumed that the dispersion action was lowered because the II-9 liquid was extremely viscous. 1 Po at 70 ° C
Viscosity is less than ise, but increases 5 times or more at 5 ℃. Therefore, Table 2 clearly shows that the crystallization of the coupler is extremely stable because the viscosity at 5 ° C. is far above 100 Poise.

[0026]

[Table 2]

(Example-3) The following liquids I-2 and II
An emulsion was prepared by the following method using Solution-10. Solution I-2: Lime-treated gelatin solution (12%) 6000 g Solution II-10: Coupler (C-1) below 600 g Tricresyl phosphate 300 g Ethyl acetate 300 g Sodium dodecylbenzenesulfonate 60 g

[0028]

Embedded image

The emulsification method was carried out by mixing and dissolving the liquid I and the liquid II at 60 ° C., and using a dissolver blade having a diameter of 7 cm in a container of 10 liters at a rotation speed of 4000 rpm so that the average particle diameter was about 0.2 μm. Stir for ~ 30 minutes.
After that, collect 1000 g of the finished emulsion,
50 ~ 400tor using rotary evaporator
The mixture was heated to 50 ° C. under reduced pressure of r to remove ethyl acetate, and finally emulsions B-2 to B-6 were obtained. The vapor pressure of ethyl acetate at 50 ° C. is about 300 torr.
Decompression degree set to 400 torr and 300 torr, respectively B
-2 and B-3 could not remove the solvent sufficiently, but the pressure was reduced to less than one third of the vapor pressure of ethyl acetate.
For 5 and B-6, a residual solvent ratio of 10% or less was obtained. The average particle diameter and the viscosity of the liquid II were measured, and the crystallization of the coupler was evaluated in the same manner as in Example-1. The concentration of ethyl acetate was determined by a gas chromatograph calibrated with an aqueous solution sample. The results are shown in Table 3 and are shown in Tables B-1 to B-
As the removal rate of 6 and the solvent increases, the viscosity of the liquid II increases. At the same time, the degree of crystallization of the coupler decreases,
From B-5 having a viscosity of more than 100 Poise, no spots causing coating failure were observed even after long-term refrigeration for 90 days. This demonstrates that the use of the second method of the present invention for removing the low boiling organic solvent in the emulsion and increasing the viscosity of the water-insoluble phase imparts excellent stability over time.

[0030]

[Table 3]

[0031]

INDUSTRIAL APPLICABILITY As described in detail in the above examples, according to the present invention, it is possible to stably obtain dispersion particles of a hydrophobic photographic useful compound, and to provide long-term storage stability. Excellent in manufacturing suitability. Furthermore, the present invention provides a method for universally preventing crystallization of useful compounds for hydrophobic photography, so that the degree of freedom in molecular design of these compounds is increased, and photographic performance and cost merit are improved. can get.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Fujiwara 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Fuji Photo Film Co., Ltd.

Claims (3)

[Claims] 1. A method of dispersing a water-insoluble phase containing a hydrophobic photographic useful compound in water or a hydrophilic colloid composition, wherein the viscosity of the prepared water-insoluble phase at the storage temperature is 10 sec. 100Po at a shear rate of ^-1
A method for emulsifying and dispersing a useful compound for hydrophobic photography, which comprises preparing and using a water-insoluble phase such that the water is not less than ise and less than 1,000,000 Poise. 2. A method for dispersing a water-insoluble phase containing a useful compound for hydrophobic photography in water or in a hydrophilic colloid composition, wherein the viscosity of the water-insoluble phase at the storage temperature of the prepared dispersion is 10 sec. 100Po at a shear rate of ^-1
A method for emulsifying and dispersing a useful compound for hydrophobic photography, which comprises preparing and using a water-insoluble phase by adding a thickening agent to the water-insoluble phase so that it is equal to or more than ise and less than 1,000,000 Poise. 3. A method of dispersing a water-insoluble phase containing a hydrophobic photographically useful compound and a low boiling point organic solvent in water or a hydrophilic colloid composition, wherein the water-insoluble phase at the storage temperature of the prepared dispersion is used. Has a viscosity of 100 Poise or more at a shear rate of 10 Sec ^{-1 and} has a viscosity of 1,000,000.
A method for emulsifying and dispersing a useful compound for a hydrophobic photograph, characterized by being prepared and used by removing a low boiling point organic solvent during or after dispersion in water or a hydrophilic colloid composition so as to be less than Poise.