JPS61293537A - Production of emulsified material - Google Patents

Abstract

PURPOSE:To finely pulverize an emulsified grain and to make the grain size fine by emulsifying and dispersing an aq. phase and an oily phase with an apparatus which is provided with both members of a member rotating along an inside wall and/or a bottom of an emulsification dispersion apparatus and a high-velocity stirring member rotating in high velocity. CONSTITUTION:An aq. phase and an oily phase are respectively dissolved and prepared by using the preparation kettles 1, 2 (or a close-type emulsification dispersion apparatus 3 is used instead of one hand thereof.) of the aq. phase and the oily phase provided with the propeller type stirrers. Both the prepared phase are transferred into the apparatus 3, emulsified and dispersed for a speci fied time by rotating the high-velocity stirrers 8, 9 so as to reach >=2500cm/ second circumferential velocity. Furthermore in this time, the inside of the apparatus 3 may be made to a decompression state with a vacuum pump 7 in order to remove a low b.p. solvent or to suppress the bubbles. In this time, the temp. of the inside of the apparatus 3 is always held at about 50-70 deg.C with a hot water jacket 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing an emulsified dispersion, more specifically a method for producing an oil-in-water emulsion, and more specifically an oil-in-water emulsion used for producing photographic materials. This invention relates to a method for preparing an emulsion.

(Background of the Invention) In the case of photographic materials, for example, in the case of couplers, the conventional method for producing oil-in-water emulsions is to prepare the coupler in a first tank with a propeller-type stirrer, which has a relatively simple structure.
While making the oil phase solution, the second one with a propeller-type stirrer
An "aqueous phase solution" containing a hydrophilic colloid, such as gelatin as a water-soluble binder, is prepared in a tank, and then the "oil solution" prepared in the first tank is added to the "aqueous phase solution" in a second tank. First, a coarsely dispersed emulsion is obtained by adding and mixing the "oil phase solution" and "aqueous phase solution" or simultaneously injecting and mixing the "oil phase solution" and "aqueous phase solution" into a third tank equipped with a propeller-type stirrer. Then, this coarsely dispersed emulsion is further finely dispersed by passing through an emulsifier such as a colloid mill, an ultrasonic emulsifier, or a high-pressure homogenizer to form particles of oil-soluble coupler droplets as a dispersed phase. The aim was to adjust the diameter to a desired level and complete the emulsification process.

Further, JP-A No. 57-59620 discloses a dispersion method that has a good effect of emulsifying fine particles by using a stirring member having a disc-shaped or cross-shaped stirring piece with folded blades.

When using the above-mentioned emulsifying and dispersing machines, such as colloid mills, ultrasonic emulsifiers, and high-pressure homogenizers, it is not possible to obtain sufficiently finely divided emulsions, and the quality of the emulsions deteriorates due to heat generation, especially in colloidal milk tubes. Sometimes it was damaged. In order to improve these drawbacks, high-pressure homogenizers connected in multiple stages have been disclosed in Japanese Patent Publication No. 52-151676, Japanese Patent Publication No. 52-151676, etc.
In order to set and change the conditions to obtain the optimal operating conditions, it takes time to replace and set the nozzle part, and the pressure to be applied to the liquid is as high as 100 to 500 9/criG. However, in order to obtain a large amount of emulsion, a large amount of power is required, and there are practical problems such as significant wear of the members constituting the nozzle part.

On the other hand, so-called high-speed rotary emulsifying and dispersing machines, such as homogenizers, homomixers, etc., with blades of various shapes, are usually operated at several thousand rpm at least several hundred rpm.
The method of emulsifying and dispersing by rotating at pm or higher is also widely used, and is practical because it is a simple device, it is easy to set conditions, and it is highly durable and easy to maintain. There were no satisfactory results in terms of obtaining a sufficiently finely divided average particle diameter or the presence or absence of coarse particles.

Furthermore, in emulsification, it is said that the larger the proportion of the dispersed phase, that is, the oil phase, the greater the atomization effect in the case of mass sales, which causes phase inversion in the case of oil-in-water emulsions.

However, with high-pressure homogenizers, when the volume percentage of the oil phase to the gold phase exceeds 30%, a creaming phenomenon occurs and dispersion becomes impossible, which limits the content of the oil phase during dispersion. have.

Furthermore, the dispersion device described in JP-A No. 57-59620 has a large atomization effect, and only a small amount of coarse particles are generated in the dispersion near the stirring piece. However, the flow near the pot wall is very poor, and very coarse particles are likely to be generated in this area. This is particularly noticeable when the volume ratio of the oil phase is high or the viscosity is high.

For this reason, this method alone is inadequate for the purpose of obtaining an emulsion with a uniform and small particle size.

Oil-in-water emulsions prepared by the method described above are widely used in cosmetics, foods, paints, medicines, etc., as well as in photographic materials, pressure-sensitive papers, etc. The oil-soluble substances involved are useful ingredients in these products. In particular, in photographic materials, hydrophobic substances are used in color image forming compounds (hereinafter referred to as "couplers"), compounds for diffusion transfer, color antifogging agents, antifading agents, color mixing inhibitors, ultraviolet absorbers, whitening agents, etc. However, to prepare oil-in-water emulsions of these oil-soluble substances, generally, if the oil-soluble substance is liquid, it is first dissolved as is, or if necessary, with an organic solvent or in an emulsifying aid or an organic solvent. An oil phase solution (hereinafter referred to simply as ``oil phase'') is prepared by heating or dissolving the oil-soluble substance in an organic solvent together with an emulsifying agent, or by heating or dissolving the oil-soluble substance in an organic solvent together with an emulsifying agent. A water-compatible solution containing a water-soluble binder with an emulsifying agent added as necessary (hereinafter simply referred to as "solution")
aqueous phase solution. '' and emulsified and dispersed to prepare an oil-in-water emulsion with an average particle size of approximately 0.1 to 1.0 μm.

The particle size and variation in particle size of the oil-in-water emulsion of the coupler are directly related to the sharpness of color photographs, and are always a problem from the perspective of improving image quality. No satisfactory emulsification method has been obtained in which particles are fine and uniform in particle size.

(Objective of the Invention) The object of the present invention is to eliminate the drawbacks of the conventional emulsification methods described above, and to produce a stable oil-in-water emulsion with fine emulsified particles and sufficiently uniform particle sizes using simple equipment and operations. The purpose of this invention is to provide a method for manufacturing the same.

(Structure and Effects of the Invention) An object of the present invention is to produce an oil-in-water emulsion in which an oil phase containing at least one type of oil-soluble substance is emulsified and dispersed in an aqueous phase containing a water-soluble substance. In this process, an emulsifying device is equipped with both a member that rotates along the inner wall and/or bottom of the emulsifying dispersion device (hereinafter referred to as a film scraper) and a high-speed stirring member that rotates at high speed (hereinafter referred to as a high-speed stirrer). This is achieved by a method for producing an emulsion characterized by emulsification and dispersion using a dispersion device.

In an embodiment of the present invention, it is preferable that the high-speed stirrer of the emulsifying and dispersing device comprises two high-speed stirrers having stirring blades that rotate in opposite directions.

The method of the present invention is significantly effective in the oil-in-water emulsion composition in which the volume percentage of the oil phase exceeds 25%, and the method of the present invention is particularly effective when the volume percentage of the oil phase exceeds 25%. The effect becomes significant when the circumferential speed is 2500 cm/s or more.

A batch type emulsifying and dispersing apparatus is convenient for controlling the particle size and distribution of the desired emulsion.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a diagram showing an outline of an apparatus related to the present invention.

In FIG. 1(A), numerals 1 and 2 are aqueous phase and oil phase mixing vessels each equipped with a conventional propeller type stirrer. 3 is a closed type emulsifying and dispersing device, 4 is a high-speed stirrer, 5 is a membrane scraper, 6 is a jacket for circulating hot water, and 7 is a vacuum pump. The shape of the rotary blade of the high-speed stirrer (4) may be any of a disilver type, a seed type, a propeller type, and a homomixer type. However, since a membrane scraper is installed in the same pot, the size should be selected so that it does not interfere with its installation. The film scraper 5 only needs to have the function of scraping the bottom of the pot and the vicinity of the pot wall. Specifically, it is preferable that the film scraper 5 maintains a clearance with the bottom and/or the pot wall using Teflon. A method is used in which the diameter is narrowed to 1 crn or less, rotated at low speed, and scraped indirectly, but this method is limited and requires less than one step. In addition, in order to install the film scraping 1% i5, if two high-speed stirrers that rotate in opposite directions are used as shown in Figure 1 (B), a space will be created in the center of the pot. Therefore, it is advantageous for installing a film scraper. Furthermore, the installation of these two high-speed stirrers that rotate left and right in the opposite direction not only improves the shearing force on the liquid and increases the flow of the liquid, but also suppresses the generation of bubbles. It has the advantage of being possible.

Note that the mixing pots 1 and 2 can also be used as the emulsifying and dispersing device 3, and two of them are not necessarily required. Also, the vacuum pump 7 may be used as needed, and is not necessarily necessary.

In FIG. 1(B), numerals 8 and 9 are two high-speed agitators whose rotary blades rotate in opposite directions.

Next, the emulsification and dispersion procedure performed using this apparatus will be described.

The aqueous phase and oil phase are dissolved and adjusted by 1 or 2 (or by substituting 3 for one of them). Transfer both of the blended materials into an emulsifying dispersion device gLS, and use a high-speed stirrer or 8.9 at a circumferential speed of 2500 tM/
s or more, and the membrane scraper 5 is also rotated to emulsify and disperse for a certain period of time.

Further, at this time, the vacuum pump 7 may be used to reduce the pressure inside the emulsification dispersion device [3] in order to remove the low boiling point solvent or suppress bubbles.

At this time, the temperature inside the emulsifying and dispersing device jt, 3 is always maintained at 50'C to 70C by the wet jacket 6.

In addition, the circumferential speed of the tip of the high-speed rotating blade of the high-speed stirrer is
If it is less than 2500 crn/s, a tendency to agglomerate occurs due to the balance between agglomeration and atomization, and emulsification and dispersion to an average particle size of 1 μm or less becomes insufficient.

Figure 2 shows the relationship between the tip circumferential speed of a high-speed rotating blade and the average grain size. The average particle diameter after dispersion for a certain period of time is at a circumferential speed of 250
It was found that the particle size rapidly decreases as the circumferential speed increases up to 0 m/s, and reaches almost saturation at 2500 crn/s or more, making it possible to emulsify and disperse particles up to a particle size of at least 0.2 μm. However, in this case, if there is no membrane scraper, the flow near the rotary blade is good, but the flow near the pot wall and bottom is poor. FIG. 3 shows the particle size distribution of the emulsified dispersion near the pot wall and near the blade after stirring for a certain period of time without a boundary MS separation machine.

This shows that there are many coarse particles near the pot wall. It can be seen that the liquid stagnates in areas with poor flow, which causes coarse particles, and that high-speed stirring alone cannot prevent the generation of coarse particles due to poor flow of the liquid itself.

On the other hand, in the present invention, the atomization effect due to high-speed stirring is achieved by rotating the blades at high speed, and stagnation due to poor flow is prevented by using a film scraper. ” and “Prevention of generation of coarse particles”
Two things are achieved.

It has been found that the atomization effect is greater when the ratio of the rough oil phase to the gold phase is increased within a range that does not cause the creaming phenomenon. FIG. 4 shows the relationship between the volume percentage of the oil phase to the gold phase and the average particle size. From Figure 4, the higher the concentration of the oil phase is near the phase inversion point, the better the atomization effect is.Especially, at an oil phase concentration of 25% or more, there is a tendency for the atomization to be saturated, and above this point, the atomization tends to be saturated. Less than the phase point (approximately 75%) is desirable.

In addition, if it is necessary to dilute the emulsified dispersion to a desired concentration after emulsifying and dispersing in the method of the present invention, use warm water at approximately the same temperature as the dispersion and use a propeller-type stirrer installed inside the emulsifying and dispersing device or separately. It can be easily diluted by

The emulsion thus obtained had a sufficiently small average particle size and a narrow particle size distribution, that is, it was a good emulsion with almost no coarse particles of uniform particle size.

When emulsifying and dispersing the oil phase with a high volume concentration using an emulsifying and dispersing device using only a high-speed stirrer, the circumferential speed should be increased to achieve atomization, and the cover wall should be In order to prevent flow stagnation, countermeasures are generally taken such as increasing the diameter of the rotating blade and narrowing the distance between the lid wall and the tip of the blade, but if the depth of the liquid is sufficiently shallow. Due to the above-mentioned measures, the overall liquid flow condition is good. However, if the liquid is deep, even if the flow on the lid wall near the stirring blade is good, the flow in the bottom where the stirring force does not reach or in the part away from the stirring blade is poor, leading to the generation of coarse particles.

In addition, in the present invention, if it is necessary to remove the low boiling point solvent in the oil phase in order to prevent re-agglomeration of the emulsion, the pressure inside the tank is reduced to remove it based on the known vacuum distillation procedure. You may. Furthermore, in order to remove the material more efficiently at this time, a high-speed stirrer and/or film scraper may be applied while reducing the pressure. Further, the removal of this low boiling point solvent is not necessarily carried out only within the apparatus of the present invention, but if necessary, the emulsion may be removed using a separate organic solvent removal method such as a vertical long tube type, evaporator, centrifugal thin film type evaporator, etc. It is also possible to arrange a device and perform the removal within the device of the present invention in parallel or alone.

As described above, the emulsification and dispersion method of the present invention achieves two main effects: "atomization effect" and "prevention of coarse particle generation." This effect is due to the fact that the higher the volume concentration of the oil phase to be dispersed, the greater the surface area of the interface between it and the aqueous phase, which is the dispersion medium, which increases the resistance and increases the viscosity, making it difficult to stir. This is thought to be because the force efficiently contributes to dispersion. However, when the volume concentration of the dispersed oil phase is increased, the viscosity increases, resulting in poor flow, and although particles with fine diameters are formed locally, coarse particles are generated near the lid wall. Similarly, when using a high-pressure homogenizer as an emulsifying and dispersing device, it may not be possible to use it if the viscosity is high, or creaming may occur if a long time is not spent on pre-mixing. There was also a limit to the increase in the volume concentration of the oil phase. However, these problems were solved by using a high-speed stirrer and a membrane scraper together as in this device. Furthermore, in addition to the above-mentioned two effects, the following effects can also be achieved. In other words, the device is simple, the operating conditions can be easily set and changed, cleaning is easy, the entire device is compact and inexpensive, loss of emulsion is reduced, and maintenance of the device is easy.

Furthermore, since the flow of the dispersion during emulsification is improved, the dispersion time becomes very short. This is thought to be because, when the Ray film scraper is not provided, the probability that the dispersion liquid flows into the field where the shear force of the high-speed rotating blades acts is very small.

When the method for producing an emulsion of the present invention is applied to the production of photographic materials, the coupler as an oil-soluble substance is an oxidation product of a color developing agent, such as an aromatic amine (usually a primary amine). It is a color image-forming compound that reacts with the coupler to form a dye, and generally has a hydrophobic group called a ballast group in the coupler molecule and is preferably non-diffusible, and has a 4-equivalent or 2-equivalent property with respect to silver ions. It may be either. The couplers include colored couplers that have a color correction effect, and so-called DIR couplers that release a development inhibitor during development. Among the above couplers, a known closed ketomethylene thread coupler can be used as the yellow coloring coupler. Among these, benzoylaceto-7dilide and pivaloylacetanilide compounds are advantageous.

Further, as the magenta coloring coupler, pyrazolone compounds, indacylon compounds, cyanoacetyl compounds, etc. can be used, and pyrazolone compounds are particularly advantageous.

Further, as the cyan color-forming coupler, phenolic compounds, naphthol thread compounds, etc. can be used.

On the other hand, as a lard coupler, for example, JP-A-52-
42121 can be used.

In addition, as a DIR coupler, for example, JP-A-52-
Those described in No. 69624 can be used. moreover,
In addition to the above-mentioned DIR coupler, the photographic material may contain a compound that releases a development inhibitor upon development, and for example, those described in JP-A-53-9116 can be used.

The diffusion transfer compounds include a dye developer, a diffusible dye-releasing coupler (DIR), a diffusible dye-releasing reducing agent (
DRR compounds].

The color anti-capri agent is, for example, a hydroquinone derivative,
Those containing aminophenol derivatives, gallic acid derivatives, and ascorbic acid derivatives are used.

The anti-fading agents include, for example, dihydroxybenzene tS conductors, dihydroxynaphthalene derivatives, minonaphthol derivatives, sulfonamide phenol derivatives, sulfone midonaphthol derivatives, and the like.

The ultraviolet absorber is, for example, a benzotriazole compound substituted with an aryl group, a 4-thiazolidone compound,
A benzophenone compound, a cinnamic acid ester compound, a butadiene compound, a benzoxyzole compound can be used, and an ultraviolet absorbing coupler, an ultraviolet absorbing polymer, etc. may also be used.

The brightening agent is, for example, a stilbenzene-based, toridine-based, oxazole-based, or coumarin-based compound.

For example, in photographic materials, the organic solvent may be one having a boiling point of about 30 to 160, such as a 7-tar alkyl ester, a phosphoric acid ester, a citric acid ester, a benzoic acid ester, an alkylamide, or a fatty acid ester.
Examples of organic solvents having a relatively low boiling point at °C include lower alkyl acetate, ethyl propionate, secondary butyl alcohol, methyl in butyl ketone, cyclohexanone, β-nitoxyethyl acetate, and methyl cellosolve acetate.

In photographic materials, the water-soluble binders include, for example, gelatin, gelatin derivatives, graft polymers of gelatin and other polymers, and proteins such as albumin and casein.
Cellulose derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose, cellulose sulfates, etc.; sugar derivatives such as sodium alkinate, starch conductors; polyvinyl alcohol, polyvinyl alcohol partial acetal, Billy N-vinyl pyrrolidone, polyacrylic acid, polymethacrylic acid, A wide variety of synthetic hydrophilic polymeric materials can be used, such as single or copolymers of polyacrylamide, polyvinylimidazole, golibinylvirazole, and the like.

In photographic materials, the emulsifying aids include, for example, saponin (steroid thread), alkylene oxide derivatives (such as polyethylene glycol, polyethylene glycol/
Polypropylene glycol condensates, polyethylene glycol alkyl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyethylene glycol sorbyl amines or sorbitols, polyethylene oxide adducts of silicones, glycidol derivatives ( For example, alkenylsuccinic acid polyglycerides, alkylphenol polyglycerides, fatty acid esters of polyhydric alcohols, alkyl esters of sugars, nonionic surfactants such as urethanes or ethers, nitriterpenoid saponins, alkyl carboxylates, Alkyl sulfonates, alkylbenzene sulfones [salts, alkylnaphthalene sulfonates, alkyl sulfates, alkyl phosphates, N-acyl-N-furkyltaurines, sulfo;/S phosphates, sulfoalkyl poly Anionic surfactants containing acidic groups such as carboxy groups, sulfo groups, phospho groups, sulfate ester groups, phosphoric ester groups, etc., such as oxyethylene alkylphenyl ethers, polyoxyethylene alkyl phosphates, etc. Minoalkyl sulfonic acids, aminoalkyl sulfuric acid or phosphoric acid varnish f/11)lλ7/l
/ Kill 6 tines - amphoteric surfactants such as amine imides and amine oxides dialkyl amine salts, aliphatic or aromatic quaternary ammonium salts, pyridinium,
Heterocyclic quaternary ammonium salts such as imidazolium,
and cationic surfactants such as phosphonium or sulfonium salts containing aliphatic or heterocycles.

Specific examples of the oil-soluble substances, organic solvents for dissolving oil-soluble substances, water-soluble binders, and surfactants as emulsification aids include, in addition to those mentioned above,
All those described in No. 36045 can be used.

(Examples) Hereinafter, in order to further clarify the effects of the present invention, examples will be given and explained.

Example 1 When obtaining an emulsion of magenta coupler in a photographic material, magenta coupler, 1-(2,4,6-)lichlorophenyl J-3-(
2-chloro-5-tetradecanamitono-7-2-
4 og of pyrazolone, 30 oo of organic solvent dioctyl (7 sauce) for dissolving oil-soluble substances, 70 oo of ethyl acetate,
30 g of gelatin as a water-soluble binder to form the aqueous phase
, dodecylbenzenesulfonic acid as surfactant 0.7
An oil phase and an aqueous phase bath liquid were prepared using 250 co of pure water.

Each solution was transferred to the emulsifying and dispersing device shown in Figure 1 (B), the tip of the blade rotating at high speed was rotated at a circumferential speed of z5oom/s, and the membrane scraper was rotated at 100 rpm for 5 minutes. Emulsified and dispersed. The particle size distribution at this time is shown by the curve (&) in FIG. Further, the relationship between the emulsification dispersion time and the average particle diameter at this time is shown in curve (b) in FIG.

Comparative Example 1 Emulsification and dispersion was carried out in the same manner as in Example 1 except that the film scraper was not used. The results are shown in curve (0) in Figure 5 and curve (d) in Figure 6.

As is clear from the above results, when a film scraper is installed, the average particle size becomes smaller, the emulsification and dispersion time is shortened, and the particle size distribution becomes sharper, and coarse particles No occurrence was observed.

Comparative Example 2 The liquid compositions of the oil phase and aqueous phase solutions were the same as in Example 1, and a high-pressure jHR homogenizer was used for emulsification and dispersion without using a high-speed rotation stirring device. In advance, use a propeller type stirrer for 30 minutes.
Orpm, and then passed through a high-pressure homogenizer twice at a pressure of 420 kliJ/cd for emulsification treatment to form a pre-in-water emulsion.

As a result, due to the high viscosity of the dispersion, the nozzle of the high-pressure homogenizer was clogged, making dispersion impossible. That is,
In a high-pressure homogenizer, the volume concentration of the oil phase must be at a relatively low concentration, and emulsification and dispersion could not be achieved with the volume concentration of the oil phase of this formulation.

(Effects of the Invention) According to the present invention, refinement of oil droplets and improvement of monodispersity with a narrow particle size distribution width of an oil-in-water emulsion are achieved, and creaming and foaming are achieved until the oil phase concentration approaches the phase inversion point. A good emulsion with high emulsification processing efficiency can be obtained without causing any problems.

Moreover, the device is simple, compact, and inexpensive, and its maintenance and inspection are easy. In addition, there is little loss of emulsion, which greatly contributes to production technology.

[Brief explanation of drawings]

FIGS. 1A and 1B are schematic diagrams of an apparatus related to the method of the present invention. Figure 2 is a graph showing the relationship between the circumferential speed of the high-speed stirrer and the average particle diameter, Figure 3 is a graph showing the particle distribution near the rotating blades and near the strip wall, and Figure 4 is the volume percentage of the oil phase. 5 and 6 are graphs showing the relationship between the particle size distribution and the average particle size, and the relationship between the emulsification dispersion time and the average particle size. 1; Water phase preparation pot; 2 and 8, 9; Oil phase preparation pot 3; Emulsifying and dispersing device; 4: High speed stirrer; 5: Film scraper. Applicant Konishiroku Photo Industry Co., Ltd. Figure 2' 10oo 2000 3ooo 4o
oo 5000 circumferential speed cliff (C1/s) Figure 3 0. f O, 20, 30, 4-0, 50, 6 diameter (PTn) Fig. 4 5 White wood grain body 11 sweat spit (%) Fig. 5 Q, 1 0.2 0.3 0.4 0 ．．
5 0.6 particle size Cμm) Emulsification dispersion time (medium)

Claims (2)

[Claims] (1) When producing an oil-in-water emulsion in which an oil phase containing at least one type of oil-soluble substance is emulsified and dispersed in an aqueous phase containing a water-soluble substance, the inner wall of the emulsification dispersion device and/or
Alternatively, a method for producing an emulsion, characterized in that emulsification and dispersion is carried out using an emulsification and dispersion device equipped with both a member that rotates along the bottom and a high-speed stirring member that rotates at high speed. (2) The method for producing an emulsion according to claim 1, wherein the high-speed stirring member of the emulsifying and dispersing device comprises two high-speed stirring members having stirring blades that rotate in opposite directions.