JPS61291036A - Preparation of emulsion - Google Patents

Abstract

PURPOSE:To impart uniform fine particles and to enhance emulsifying and dispersing stability, by emulsifying and dispersing an oil phase in such a state that the concn. of the oil phase is high and preliminarily reducing a low b.p. solvent from the obtained emulsified dispersion before diluting said dispersion. CONSTITUTION:An aqueous phase solution and an oil phase solution are pre pared by dissolving vessels 1, 2 for an aqueous phase and an oil phase each equipped with a usual propeller type stirrer. Next, both solutions are emulsified and dispersed in a hermetically closed type emulsifying/dispersing apparatus 3 and a low b.p. solvent is subsequently removed from thus obtained dispersion in a low b.p. solvent removing apparatus. Further, the dispersion is transferred to a dilution vessel 9 where the aqueous phase solution is added from an aque ous phase solution adding line 8 at the time of dilution to dilute the same to obtain an emulsified dispersion. The dissolving vessel 1, 2 can be also used as the emulsifying apparatus 3 and it is not necessary to require two vessels. The low b.p. solvent is pref. removed until reduced to 20% or less of the total volume of the oil phase.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing an emulsified dispersion, more specifically to a method for producing an oil-in-water emulsion, and more specifically to a method for producing an oil-in-water emulsion used for producing photographic materials. This invention relates to a method for producing an oil emulsion.

[Background of the invention]

In 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 preparing an "oil phase solution", an "aqueous phase solution" containing a hydrophilic colloid, such as gelatin as a water-soluble binder, is prepared in a second tank having a propeller-type stirrer, and then an "aqueous phase solution" in the second tank is prepared. ”, the “oil phase solution” prepared in the first tank is added and mixed, or the “oil phase solution” and “
Aqueous phase solution is simultaneously injected and mixed to obtain a coarsely dispersed emulsion, and then this coarsely dispersed emulsion is further processed using a quaternary mill, an ultrasonic emulsifier, a high-pressure homogenizer, etc. It was an attempt to complete the emulsification process by finely dispersing the oil-soluble coupler as a dispersed phase by passing it through an emulsifier and dispersing machine, and aligning the particle size of the liquid surface of the oil-soluble coupler as a dispersed phase to a desired level. describes that dispersion with an excellent atomization effect can be obtained by using a disc-shaped stirring device that rotates at high circumferential speed.

When emulsifying and dispersing in such an apparatus, it is desirable to perform dispersion at a high oil phase concentration because the higher the dispersoid concentration, that is, the oil phase concentration, the better the dispersion efficiency. However, it may be necessary to further dilute the emulsified dispersion by adding an aqueous phase solution to the emulsified dispersion due to liquid transportation of the emulsion obtained after emulsification dispersion, addition to another aqueous phase, or performance required for the emulsion. . In this case, a desired aqueous phase solution was added after emulsification and dispersion, and the mixture was diluted and stirred at low speed. If the oil phase solution contains a low boiling point solvent and it must be removed from the final product, dilute it to improve the fluidity of the dispersion and improve the removal efficiency, and then remove the low boiling point solvent again. The low boiling point solvent was removed by passing it through a device.

In addition, when dilution is not performed, dispersion is carried out in advance according to the final composition formulation with a low oil phase concentration, but in this case it is inevitable that the dispersion efficiency will be lowered.

Once the oil phase has been emulsified and dispersed in a high concentration state, the aqueous phase solution is continued until the desired composition is obtained without removing the low boiling point solvent at all (for example, the extent of natural evaporation is ignored). When added and diluted, particles agglomerate immediately and the average particle size increases.

Further, as a device for this emulsification and dispersion, any of a colloid mill, an ultrasonic emulsifier, a high-pressure homogenizer, etc. can be used as described above. However, when using colloid mills, ultrasonic decomposition devices, high-pressure homogenizers, etc. as emulsifying and dispersing devices, it is difficult to obtain sufficiently finely divided emulsions. Quality was sometimes compromised. In order to improve these drawbacks, a high-pressure homogenizer that connects in multiple stages is disclosed in Japanese Patent Publication No. 52-11221 and Japanese Patent Application Laid-open No. 52-1516.
No. 76 etc. have been disclosed and proposed, but it takes time to replace and set the nozzle part to set and change the conditions to obtain the optimal operating conditions, and the pressure to be applied to the liquid is high. Since the pressure is as high as 100 to 500 Kg/crl G, a large amount of power is required to obtain a large amount of emulsion, and there are practical problems such as significant wear of the nozzle member. Furthermore, high-pressure homogenizers have a narrow tolerance range for the viscosity of the emulsified dispersion, and creaming occurs when the oil phase concentration is high. Therefore, the oil phase concentration can only be increased to a certain extent, and the dispersion efficiency is limited. On the other hand, with a high-speed stirrer, the oil phase concentration is near the phase inversion point (approximately 75%).
If the circumferential speed of high-speed stirring is made sufficiently high, the atomization effect will be greater than when using a high-pressure homogenizer. Therefore, it is more advantageous to use a high-speed stirring device with a sufficiently high circumferential speed than to use a high-pressure homogenizer, if it is possible to prevent particle agglomeration when diluting with an aqueous solution to a desired oil phase concentration later. be.

The oil-in-water emulsion prepared as described above can be used in cosmetics,
It is widely used in foods, paints, medicines, etc., as well as in photographic materials, pressure-sensitive papers, etc., and the oil-soluble substances contained in the oil phase are useful ingredients in these products. Particularly in photographic materials, color image-forming compounds (hereinafter "couplers")
Oil-soluble substances are used in diffusion transfer compounds, color fog preventive agents, color fading preventive agents, color mixing preventive agents, ultraviolet absorbers, whitening agents, and the like. In general, to prepare oil-in-water emulsions of these oil-soluble substances, first, if the oil-soluble substances are liquid, they may be used as is, or if necessary, together with an organic solvent or an emulsifying agent, or an emulsifying agent dissolved in an organic solvent. An oil phase solution (hereinafter simply referred to as "oil phase solution") prepared by heating or dissolving the oil-soluble substance in an organic solvent, or by dissolving it in an organic solvent together with an emulsifying agent if the oil-soluble substance is solid. ) is added to an aqueous phase solution (hereinafter simply referred to as "aqueous phase solution") containing a water-soluble binder to which an emulsification aid is added as needed, and emulsified and dispersed to obtain a concentration of approximately 0.
It was prepared as an oil-in-water emulsion with an average particle size of 1 to 1.0 pm.

The particle size and agglomeration state of the oil-in-water emulsion of the coupler immediately affect the sharpness of color photographs, and the stability of the emulsion dispersion is always a problem along with the particle size from the viewpoint of productivity, and it is still difficult to understand. However, a satisfactory method for preparing an oil-in-water emulsion with high dispersion stability has not been obtained.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the emulsification method for oil-in-water emulsions containing a low boiling point solvent in the oil phase, and to practically provide uniform fine particles and emulsify and disperse them using simple equipment and operations. An object of the present invention is to provide a highly stable oil-in-water emulsification method.

[Structure and effects of the invention]

As a result of intensive research, the present inventors found that when producing an oil-in-water emulsion in which an oil phase containing a low-boiling point solvent and an oil-soluble substance is emulsified and dispersed in an aqueous phase containing a water-soluble substance, Emulsifying and dispersing in a state where the dispersoid concentration, that is, the oil phase concentration is high,
When adding an aqueous phase to this and diluting it to the desired oil phase concentration,
It has been clarified that the above object can be achieved by reducing the low boiling point solvent from the emulsified dispersion during or after emulsifying dispersion by performing a reduction operation in advance, and then diluting it with an aqueous phase solution.

In the present invention, it is preferable to reduce the amount of the low boiling point solvent to 20% or less of the total oil phase volume.

Further, in the present invention, the aqueous phase solution includes an aqueous solution containing water, a water-soluble surfactant, a hydrophilic colloid, and the like.

An embodiment of the present invention will be described below based on the attached drawings.

FIG. 1 is a schematic diagram showing an apparatus for carrying out the invention. 1 and 2 are dissolution vessels for the aqueous phase and the oil phase, respectively, each equipped with a conventional propeller-type stirrer.

3 is a closed type emulsifying and dispersing device, 4 is a high-speed rotating blade,
The shaded area 5 is a jacket for circulating hot water, 6
7 is a vacuum pump, 7 is a low boiling point solvent removal device, 8 is an aqueous solution addition line during dilution, and 9 is a dilution vessel equipped with a conventional propeller type stirrer. Note that the shape of the high-speed rotating blade 4 may be any one such as a disilver type, a seed type, a propeller type, a homomixer type, or any other type including two shafts that rotate left and right in opposite directions.

Further, the low boiling point solvent removal device 7 may be any device as long as it is capable of removing the low boiling point solvent. Further, the melting vessels 1 and 2 can also be used as the emulsifying and dispersing device 3, and two of them are not necessarily required. Further, the vacuum pump 6 may be used as needed, and is not necessarily necessary.

Next, each of the dispersion procedures shown in FIGS. 1 to 4 will be described. Note that the same symbols have the same meaning throughout each figure.

In Figure 1, water phase and oil phase solutions are prepared in steps 1 and 2, emulsified and dispersed in step 3, and then the low boiling point solvent is removed in the low boiling point solvent removal device in step 7. This is transferred to the dilution pot in step 9. An emulsified dispersion is obtained by adding more aqueous phase solution and diluting it.

In FIG. 2, the low boiling point solvent is removed at the same time as the emulsification and dispersion in step 3, and this is transferred to the dilution pot in step 9 and diluted.

In FIG. 3, all of emulsification and dispersion, removal of low boiling point solvent, and dilution are performed in step 3.

In FIG. 4, after emulsification and dispersion in step 3, the low-boiling point solvent is removed in step 7, and the mixture is again transferred to the emulsification and dispersion device in step 3 using a liquid feed pump 0 for dilution.

Further, the emulsifying and dispersing device 3 does not necessarily have to be a high-speed stirring type, and may be other devices such as a high-pressure homogenizer or a colloid mill.

FIG. 5 shows the removal rate of the pre-reduced low boiling point solvent and the average particle size of the oil phase (oil droplets) in the final oil-in-water emulsion when emulsified and dispersed with the same composition and diluted. As is clear from Figure G, if the particles are diluted with an aqueous solution before removing the low-boiling point solvent, the particles will aggregate and the average particle size will increase, whereas in the present invention, the low-boiling point solvent is removed in advance. It was found that as the removal rate increased, aggregation was suppressed and the average particle size before dilution could be maintained.

Furthermore, as shown in Fig. 5, when the removal rate of the low boiling point solvent exceeds 60%, the reduction in the average particle size becomes almost saturated, and at least 60%.
% or more is preferable.

At this time, when the concentration of the low boiling point solvent is converted into the concentration of the low boiling point solvent in the total oil phase volume, the concentration is 20% or less.

In general, low boiling point solvents contained in emulsified dispersions are essential to play the role of solubilizing agent, dispersing agent, etc. at the initial stage of dispersion, but once dispersion has progressed to a certain extent, they can actually promote particle aggregation. It often works. Furthermore, when the emulsified dispersion containing a low boiling point solvent is transferred to a coating process or the like, fire and sanitary safety problems also arise. For this reason, conventionally, after obtaining a desired emulsified dispersion, the low boiling point solvent was removed before finally moving on to the next step. That is, once an emulsified dispersion is obtained by a phase inversion method etc. in a state where the concentration of the dispersoid (oil phase) is higher, an aqueous phase is added and diluted to obtain the desired composition, and then a low boiling point The solvent was removed. For this reason, particle aggregation occurs during the initial dilution stage, and even if the dispersoid (oil phase) is efficiently dispersed into fine particles at a high concentration, the average particle size increases with dilution. .

On the other hand, the method of the present invention, that is, diluting to the desired concentration after removing the low-boiling point solubilizer, suppresses the above-mentioned agglomeration, and allows the particles to be efficiently dispersed and atomized at a high concentration of dispersoids (oil phase). can be diluted to a desired concentration while maintaining its particle size.

When the present invention is applied to various photographic materials, the coupler is an oil-soluble substance that forms a color image by reacting with an oxidation product of a color developing agent such as an aromatic amine (usually a primary amine) to form a dye. The compound is preferably a non-diffusible compound that generally has a hydrophobic group called a ballast group in the coupler molecule, and may be either 4-equivalent or 2-equivalent to silver ions. In addition, the coupler includes:
Also included are 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 open-chain ketomethylene coupler can be used as the yellow coloring coupler. Among these, benzoylacetanilide 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, phenol compounds, naphthol compounds, etc. can be used.

On the other hand, as a colored coupler, for example,
-42121 can be used.

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

The compounds for diffusion transfer include colorants (developer diffusible dye-releasing couplers (DDR couplers), diffusible dye-releasing reducing agents (DRR compounds), etc.).

The color antifogging agent used includes, for example, a hydroquinone derivative, an aminophenol derivative, a gallic acid derivative, or an ascorbic acid derivative.

Examples of the antifading agent include dihydroxybenzene derivatives, dihydroxynaphthalene derivatives, aminonaphthol derivatives, sulfonamide phenol derivatives, sulfonamide naphtho-)V 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 brightener is, for example, a stilbenzene-based, triazine-based, oxazole-based, or coumarin-based compound.

The organic solvent used in photographic materials is, for example, one with a high boiling point, such as phthalic acid alkyl ester, phosphoric acid ester, citric acid ester, benzoic acid ester, alkylamid, fatty acid ester, etc., with a boiling point of about 30 to 160°.
Examples of organic solvents having relatively low points for C include lower alkyl acetate, ethyl propionate, secondary butyl alcohol, methyl isobutyl ketone, cyclohexanone, β-ethoxyethyl acetate, and methyl cellosolve acetate.

The latter is referred to as a low boiling point solvent in the present invention.

In photographic materials, the water-soluble binders include gelatin, gelatin derivatives, graft polymers of seratin and other polymers, albumin, casein, etc. [1; hydroxyethyl cellulose, carboxymethyl cellulose, cellulose sulfate esters, etc. Sugar derivatives such as cellulose transconductors, sodium alkinate, and starch derivatives:
Various synthetic hydrophilic polymeric substances such as single or copolymers of polyvinyl alcohol, polyvinyl alcohol partial acetal, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole, polyvinylpyrazole, etc. Can be used.

In photographic materials, the emulsification aids include, for example, saponins (steroids), alkylene oxide derivatives (e.g. polyethylene glycol, polyethylene glycol/polypropylene glycol condensates, polyethylene glycol alkyl or alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan). esters, polyalkylene glycol alkylamines or amides, silicone polyethylene oxide adducts), glycidol derivatives (e.g. alkenylsuccinic acid polyglycerides, alkylphenol polyglycerides), fatty acid esters of polyhydric alcohols, alkyl esters of sugars, Similarly, nonionic surfactants such as urethanes or ethers; triterpenoid saponins, alkyl carboxylates, alkyl sulfones W1. salt, alkylbenzene sulfonate,
Alkylnaphthalene sulfonates, alkyl sulfates, alkyl phosphates, N-acyl-N-
Acidic groups such as carboxy groups, sulfo groups, phospho groups, sulfate ester groups, phosphate ester groups, etc. such as alkyl taurines, sulfosuccinates, sulfoalkyl polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl phosphates, etc. Anionic surfactants containing groups; amino acids, aminoalkylsulfonic acids,
Ampholytic surfactants such as aminoalkyl sulfates or phosphates, alkyl betaines, amine imides, and amine oxides; heterocyclic quaternary surfactants such as alkyl amine salts, aliphatic or aromatic quaternary ammonium salts, pyridinium, imidazolium, etc. Cationic surfactants such as ammonium salts and phosphonium or sulfonium salts containing aliphatic or heterocycles can be used.

〔Example〕

Next, 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)-3-(2
-Chloro-5-tetradecanamido)anilino-5-pyrazolone 4og, mlfj organic solvent for dissolving chemical substances (dioctyl phthalate) 30 cc, ethyl acetate 60
CC, 30 g of gelatin as a water-soluble binder to form an aqueous phase, 800 CC of pure water, and dodecylbenzenesulfonic acid as a surfactant) 1. An oil phase and an aqueous phase solution were prepared using Og. Each solution was transferred to the emulsifying and dispersing apparatus shown in FIG. 1 and emulsifying and dispersing for 5 minutes. At this time, the average particle size of the oil droplets of the obtained emulsified dispersion was 0.23 μm. Further, 99% or more of the initial amount of ethyl acetate contained in this emulsified dispersion was removed using a vertical long tube evaporator, and then 300 cc of pure water was added to dilute the emulsified dispersion. The average particle size of oil droplets of the emulsified dispersion obtained after dilution was 0.25 μm.
Met.

Comparative Example 1 The same composition and method as in Example 1 were used to reduce the average particle size to 0.23μ.
An emulsified dispersion of m was obtained. Pure water 3 is added to this emulsified dispersion.
After adding 00 cc and diluting the emulsified dispersion, more than 99% of the initial amount of ethyl acetate contained in the emulsified dispersion was removed using a vertical long tube evaporator. The average particle size of the oil droplets was 0.62 μm.

When the emulsified dispersion requires dilution as described in Example 1 and Comparative Example 1, the average particle size can be adjusted by removing the low boiling point solvent, ie, ethyl acetate, before dilution, and then adding and diluting the required aqueous phase solution. A small emulsified dispersion is obtained.

Comparative Example 2 Magenta coupler 1 was used as an oil-soluble substance forming an oil phase.
-(2,4,6-dolichlorophenyl)-3-(2-di60-5-tetradecanamido)anilino-5-pyrazolone 409, organic solvent dioctyl phthalate for dissolving oil-soluble substances) 30 cc.

60 cc of ethyl acetate, 30 g of gelatin as a water-soluble binder to form an aqueous phase, 500 cc of pure water, and 1. sodium dodecylbenzenesulfonate as a surfactant.
An oil phase solution and an aqueous phase solution were prepared at 0 g. Each solution was transferred to the emulsifying and dispersing apparatus shown in FIG. 1 and emulsifying and dispersing for 5 minutes. The average particle size of the emulsified dispersion obtained at this time was 0.65 μm.

As described in Example 1 and Comparative Example 2, if the composition of the final emulsion is emulsified and dispersed from the beginning without dilution, the atomization effect is small, and once the dispersoid is dispersed at a high concentration, An emulsified dispersion with a smaller average particle size was obtained by dilution.

Example 2 Magenta coupler, 1- as a composition substance forming an oil phase
(2,4,6-dolichlorophenyl)-3-(2-chloro-5-tetradecanamido)anilino-5-pyrazolone 40 g, organic solvent for dissolving oil-soluble substances (tilphthalate) 30 cc, ethyl acetate An oil phase and an aqueous phase solution were prepared using 200 cc of pure water to form an aqueous phase and 1.0 g of sodium dodecylbenzenesulfonate as a surfactant. Each solution was transferred to the emulsifying and dispersing apparatus shown in FIG. 1 and emulsifying and dispersing for 5 minutes. The average particle size of the emulsified dispersion obtained at this time was 0.15 pm. Furthermore, after removing 99% or more of the initial ethyl acetate/l/total of ethyl acetate contained in this emulsified dispersion using a vertical long-tube evaporator, 300 cc of pure water and a gelatin solution consisting of gelatin 309 were added. Diluted. The average particle size of the emulsified dispersion obtained after dilution was 0.18 ρm.

As shown in Example 2, the water-soluble binder used in the aqueous phase may be contained in the initial emulsification and dispersion, or may be contained only in the aqueous phase during dilution.

〔Effect of the invention〕

The present invention achieves the atomization of oil droplets of an oil-in-water emulsion by simple operation without making any changes to the conventional emulsification dispersion device, and maintains the emulsion dispersion stability, which is extremely significant in terms of productivity. .

[Brief explanation of the drawing]

1 to 4 are schematic diagrams of an apparatus for preparing a pre-in-water emulsion. FIG. 5 is a graph showing the relationship between the removal rate of the low boiling point solvent and the zero particle size of the oil droplets of the emulsion. 1... Water phase dissolution pot 2... Oil phase dissolution pot 3... Emulsifying and dispersing device 7... Low boiling point solvent removal device 9...・Dilution pot applicant Konishi Roku Photo Industry Co., Ltd. Fig. 1 1° Water I @ Yumae 2 Karesa 59 醇釜 3 Tarurika Bunei 1 7 Irareru, refusal, spinning; Se Makumo Ei ri” 1t9.4 turn tank M! i Q B Figure 2 A La 3 Reli Figure 4

Claims (1)

[Claims] When producing an oil-in-water emulsion in which an oil phase containing a low boiling point solvent and an oil-soluble substance is emulsified and dispersed in an aqueous phase containing a water-soluble substance, the oil phase is emulsified and dispersed in a high concentration state in advance,
Production of an emulsion, characterized in that during and/or after the emulsification dispersion step, the low boiling point solvent is previously reduced from the emulsion dispersion by a reduction operation, and then the emulsion dispersion is diluted. Method.