Method for producing oil-in-water emulsions

Abstract

To provide a method that can produce an oil-in-water emulsion, regardless of its viscosity, by using a device of a simple structure.SOLUTION: A method for producing an oil-in-water emulsion includes adding a jet of an oil-in-water preliminary emulsion L1, which has an oil phase dispersed in a first aqueous phase, to a second aqueous phase L2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a method for producing an oil-in-water emulsion. [Background technology]

[0002] A method for producing an emulsion as a final product is known, which involves mixing a pre-prepared raw material emulsion with an aqueous or oil phase. For example, Patent Document 1 discloses a method for producing a secondary emulsion in which the diameter of the droplets of phase A is smaller than that of the primary emulsion, by using a primary emulsion in which droplets of phase A are dispersed in phase B as the starting material, and applying shear stress to the primary emulsion by placing it in a container made of a coaxial cylinder. Patent Document 2 discloses a method for producing an emulsion in which a part of the aqueous phase and all of the oil phase, all of the aqueous phase and part of the oil phase, or a part of the aqueous phase and part of the oil phase are continuously supplied to an emulsifier to generate a preliminary emulsion, and the preliminary emulsion and the remaining aqueous and / or oil phase are supplied to another emulsifier for stirring and mixing.

[0003] Furthermore, a mixing method is known in which one of two liquids is discharged into the other in a jet state. For example, Patent Document 3 discloses a method for producing a fatty acid neutralized product in which a fatty acid mixture is discharged into a basic aqueous solution in a jet state. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 11-509473 [Patent Document 2] Japanese Patent Application Publication No. 5-154367 [Patent Document 3] International Publication No. 2020 / 129723 [Overview of the project] [Problems that the invention aims to solve]

[0005] When producing low-viscosity emulsions, high-shear mixing of the oil and aqueous phases is not required, so a relatively simple mixer can be used. Such mixers have low installation and maintenance costs, are easy to clean, and are suitable for mass production.

[0006] On the other hand, producing high-viscosity emulsions requires high-shear mixing of the oil and aqueous phases, necessitating the use of complex mixers. Such mixers have problems such as high installation and maintenance costs, poor cleanability, and unsuitability for mass production.

[0007] The object of the present invention is to provide a method for producing oil-in-water emulsions using a simple apparatus, regardless of their viscosity. [Means for solving the problem]

[0008] The present invention is a method for producing an oil-in-water emulsion, in which an oil phase is dispersed in a first aqueous phase, and this preliminary emulsion is added to a second aqueous phase by jet. [Effects of the Invention]

[0009] According to the present invention, by using a simple apparatus and adding an oil-in-water pre-emulsifier in which the oil phase is dispersed in the first aqueous phase to the second aqueous phase via a jet, an oil-in-water emulsion with a small average particle size of the oil phase can be produced regardless of its viscosity. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram shows the configuration of the oil-in-water emulsion manufacturing apparatus used in the example. [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below.

[0012] The method for producing an oil-in-water emulsion according to this embodiment involves jet-adding an oil-in-water preliminary emulsion, in which the oil phase is dispersed in a first aqueous phase, into a second aqueous phase. In this application, "jet state" refers to a state in which the oil-in-water preliminary emulsion is ejected from holes placed in the second aqueous phase into a wide area filled with the second aqueous phase, and it can be visually confirmed that droplets smaller than the diameter of the holes are formed and diffuse from the holes. In this application, "jet addition" refers to adding the oil-in-water preliminary emulsion in a "jet state" from holes placed in the second aqueous phase into a wide area filled with the second aqueous phase. According to the method for producing an oil-in-water emulsion according to this embodiment, by using a simple apparatus equipped with a mixing tank having a jet discharge part such as a jet nozzle, and jet-adding the preliminary emulsion from the jet discharge part into the second aqueous phase stored in the mixing tank, an oil-in-water emulsion with small average particles of oil phase can be produced regardless of its viscosity. This is presumed to be because, when the preliminary emulsion is added in a jet to the second aqueous phase, an oil-water interface has already been formed at the time of the jet. As a result, shear stress is efficiently applied to the interface of the oil phase, thereby promoting the refinement of the oil phase.

[0013] Therefore, the costs of introducing and maintaining such equipment can be kept low. Furthermore, because the equipment has excellent cleanability, the oil-in-water emulsion being manufactured can be switched over in a short time, resulting in high productivity. In addition, large-scale production of oil-in-water emulsions in single batches is possible.

[0014] In the method for producing an oil-in-water emulsion according to this embodiment, first, an oil phase and a first aqueous phase are mixed to prepare an oil-in-water preliminary emulsion.

[0015] The method for preparing the preliminary emulsion is not particularly limited and includes, for example, general high-pressure emulsification, phase inversion emulsification, membrane emulsification, and D-phase emulsification.

[0016] Examples of the oil phase include fragrances, oils, antioxidants, cooling agents, dyes, pigments, silicones, solvents, oil-soluble polymers, etc. The oil phase may contain one or more of these. From the viewpoints of producing an oil-in-water emulsion with a small average particle size of the oil phase and improving the stability of the oil-in-water emulsion, it is preferable that the oil phase contains an oil agent and / or a silicone, and it is more preferable that the oil phase contains a silicone.

[0017] The oil agent is preferably an organic compound having a solubility of less than 1 g in 100 g of water. The solubility of this oil agent in 100 g of water is the solubility at 25°C (1013.25 hPa). The solubility of the oil agent in 100 g of water is preferably 0.5 g or less, more preferably 0.1 g or less, and may be 0 g. For the measurement of solubility, reference can be made to, for example, Journal of the Chemical Society of Japan, 1985, No. 11, p2116 - 2119, the same journal, 1982, No. 11, p1830 - 1834, etc.

[0018] Examples of the oil agent include liquid oils that are liquid at 20°C and solid fats that are solid at 20°C. The oil agent may contain only liquid oils, only solid fats, or both of them.

[0019] Examples of the oil agent include alcohols, ester oils, hydrocarbon oils, dialkyl ether compounds, amine compounds, amide compounds, fats and oils, higher fatty acids, etc. The oil agent preferably contains one or more of these. Note that the oil agent may contain those used as fragrances, antioxidants, cooling agents, moisturizing agents, dyes, pigments, etc.

[0020] Examples of silicones include dimethylpolysiloxane, methylpolysiloxane, methylphenylpolysiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, methylhydrogenpolysiloxane, silicone resins, amino-modified silicones, alkyl-modified silicones, polyether-modified silicones, glyceryl-modified silicones, and silicone waxes. From the viewpoint of obtaining a dispersion of fine particles, it is preferable that the silicone contains one or more of these, and more preferably dimethylpolysiloxane. The silicone may also contain those used as texture enhancers or moisturizing ingredients.

[0021] The first aqueous phase may be water alone, or it may be an aqueous solution in which a water-soluble substance is dissolved in water. Examples of water-soluble substances include thickeners and emulsifying stabilizers. From the viewpoint of improving the stability of the oil-in-water emulsion, the thickener is preferably one or more polysaccharides, more preferably one or more selected from the group consisting of sodium alginate, carboxymethylcellulose and its salts, carrageenan, xanthan gum, sodium polyacrylate, hydroxyethylcellulose, hydroxypropylcellulose, pectin, tragacanth gum, gum arabic, guar gum, karaya gum, locust bean gum, gellan gum, tamarind gum, and psyllium seed gum, and even more preferably locust bean gum. From the viewpoint of improving the stability of the oil-in-water emulsion, the emulsifying stabilizer is preferably one or more compounds having polar groups, more preferably one or more neutral compounds, even more preferably one or more neutral polymers, and even more preferably polyvinyl alcohol. The first aqueous phase may also be a dispersion in which dispersed particles are dispersed in water.

[0022] The mass ratio of the oil phase content to the first aqueous phase content in the preliminary emulsion (oil phase / first aqueous phase) is preferably 0.01 or higher, more preferably 0.05 or higher, even more preferably 0.1 or higher, and even more preferably 0.3 or higher, from the viewpoint of improving the freedom of formulation, and preferably 4 or lower, more preferably 3.5 or lower, even more preferably 3 or lower, and even more preferably 2 or lower, from the viewpoint of obtaining a stable oil-in-water preliminary emulsion.

[0023] The average particle size of the oil phase in the preliminary emulsion is preferably 2000 μm or less, more preferably 1000 μm or less, even more preferably 500 μm or less, even more preferably 100 μm or less, even more preferably 70 μm or less, preferably 1 μm or more, and more preferably 10 μm or more, from the viewpoint of producing an oil-in-water emulsion with a small average particle size of the oil phase. Here, the average particle size of the oil phase in this application is the area-based average particle size measured by the laser diffraction scattering method using a laser diffraction / scattering particle size distribution analyzer.

[0024] In the method for producing an oil-in-water emulsion according to this embodiment, after preparing a preliminary emulsion, the preliminary emulsion is added to the second aqueous phase by jet to obtain the final oil-in-water emulsion.

[0025] The second aqueous phase may consist of water alone, but like the first aqueous phase, it may also be an aqueous solution in which a water-soluble substance is dissolved in water, or a dispersion in which dispersed particles are dispersed in water. Preferably, the second aqueous phase has the same components as the first aqueous phase of the preliminary emulsion. The second aqueous phase may have the same composition as the first aqueous phase, or a different composition.

[0026] The addition of the preliminary emulsion to the second aqueous phase by jet is preferably carried out using a nozzle. In this case, it is preferable that the tip of the nozzle is submerged in the second aqueous phase. From the viewpoint of productivity, the inner diameter of the nozzle is preferably 0.01 mm or more, more preferably 0.05 mm or more, and even more preferably 0.1 mm or more, and from the viewpoint of jetting the preliminary emulsion, it is preferably 20 mm or less, more preferably 10 mm or less, and even more preferably 1 mm or less. If the opening shape of the nozzle is not a perfect circle, the inner diameter of the nozzle is the hydraulic diameter of the opening shape.

[0027] The viscosity at the temperature when the preliminary emulsion is jet-added to the second aqueous phase is preferably 1 mPa·s or more, more preferably 10 mPa·s or more, and even more preferably 100 mPa·s or more, from the viewpoint of suppressing creaming of the preliminary emulsion, and preferably 15,000 mPa·s or less, more preferably 10,000 mPa·s or less, and even more preferably 6,000 mPa·s or less, from the viewpoint of reducing nozzle pressure loss.

[0028] The viscosity of the second aqueous phase at the temperature during jet-addition of the preliminary emulsion is preferably 0.1 mPa·s or higher, more preferably 0.5 mPa·s or higher, and most preferably 1.0 mPa·s or higher, from the viewpoint of suppressing creaming of the oil-in-water emulsion produced, and from the viewpoint of miscibility, preferably 20,000 mPa·s or lower, more preferably 10,000 mPa·s or lower, more preferably 6,000 mPa·s or lower, more preferably 1,000 mPa·s or lower, even more preferably 500 mPa·s or lower, and most preferably 10 mPa·s or lower. The viscosity of this second aqueous phase is preferably lower than the viscosity of the preliminary emulsion from the viewpoint of producing an oil-in-water emulsion with a small average particle size in the oil phase.

[0029] The linear velocity when the preliminary emulsion is jet-added to the second aqueous phase is preferably 5 m / s or more, more preferably 10 m / s or more, even more preferably 20 m / s or more, and even more preferably 30 m / s or more, from the viewpoint of producing an oil-in-water emulsion with a small average particle size of the oil phase, and preferably 100 m / s or less, more preferably 50 m / s or less, and even more preferably 40 m / s or less, from the viewpoint of reducing the load on the equipment. Here, "linear velocity of the preliminary emulsion" in this application refers to the velocity of the liquid in the direction of discharge of the preliminary emulsion. The absolute value of this linear velocity of the preliminary emulsion is calculated by dividing the mass flow rate of the preliminary emulsion by the density of the preliminary emulsion, further dividing that by the area of ​​the discharge hole, and converting it to per second.

[0030] The shear rate when the preliminary emulsion is added to the second aqueous phase by jet is preferably 0.25 million s, from the viewpoint of efficiently applying shear to the oil-water interface between the preliminary emulsion and the second aqueous phase to refine the oil phase. -1 The above is a comfortable 0.5s -1 More preferably 10,000 s -1 More preferably 20,000 s -1 More preferably 30,000 s -1 Therefore, from the viewpoint of reducing the load on the device, 500,000 s is preferred. -1 More preferably 400,000 s -1 More preferably, 300,000 s -1 The following is the result. When the pre-emulsified material is added to the second aqueous phase by a jet using a nozzle, this shear rate is calculated by dividing the linear velocity of the pre-emulsified material by the inner diameter of the nozzle (linear velocity of pre-emulsified material / inner diameter of nozzle).

[0031] The average particle size of the oil phase in the oil-in-water emulsion produced is preferably 35 μm or less, more preferably 30 μm or less, even more preferably 20 μm or less, and even more preferably 1 μm or more.

[0032] The ratio of the average particle size of the oil phase in the oil-in-water emulsion to the average particle size of the oil phase in the preliminary emulsion (average particle size of the oil phase in the oil-in-water emulsion / average particle size of the oil phase in the preliminary emulsion) is preferably 0.001 or higher, more preferably 0.01 or higher, and even more preferably 0.1 or higher, from the viewpoint of producing emulsions in an energy-saving manner, and is preferably 0.9 or lower, more preferably 0.7 or lower, and even more preferably 0.6 or lower, from the viewpoint of producing fine emulsions.

[0033] With regard to the embodiments described above, the present invention further discloses the following embodiments.

[0034] [1] A method for producing an oil-in-water emulsion, comprising adding an oil-in-water preliminary emulsion, in which the oil phase is dispersed in a first aqueous phase, to a second aqueous phase by jet.

[0035] [2] A method for producing an oil-in-water emulsion according to [1], wherein the viscosity at the temperature when the preliminary emulsion is added to the second aqueous phase in a jet is 0.1 mPa·s or more and 20,000 mPa·s or less.

[0036] [3] A method for producing an oil-in-water emulsion according to [1] or [2], wherein the viscosity at the temperature when the preliminary emulsion is added to the second aqueous phase in a jet is 0.1 mPa·s or more and 10,000 mPa·s or less.

[0037] [4] A method for producing an oil-in-water emulsion according to any one of [1] to [3], wherein the viscosity at the temperature when the preliminary emulsion of the second aqueous phase is added in a jet is 1 mPa·s or more and 10,000 mPa·s or less.

[0038] [5] A method for producing an oil-in-water emulsion according to any one of [1] to [4], wherein the viscosity at the temperature when the preliminary emulsion is added to the second aqueous phase in a jet is 1 mPa·s or more and 6000 mPa·s or less.

[0039] [6] A method for producing an oil-in-water emulsion according to any one of [1] to [5], comprising using a mixing tank having a jet discharge section and jet-adding the preliminary emulsion from the jet discharge section into the second aqueous phase stored in the stirring mixing tank.

[0040] [7] A method for producing an oil-in-water emulsion according to any one of [1] to [6], wherein the mass ratio of the oil phase content in the preliminary emulsion to the first aqueous phase content is 0.01 or more and 4 or less.

[0041] [8] A method for producing an oil-in-water emulsion according to any one of [1] to [7], wherein the mass ratio of the oil phase content in the pre-emulsified emulsion to the first aqueous phase content is 0.01 or more and 3 or less.

[0042] [9] A method for producing an oil-in-water emulsion according to any one of [1] to [8], wherein the mass ratio of the oil phase content in the preliminary emulsion to the first aqueous phase content is 0.05 or more and 3 or less.

[0043]

[10] A method for producing an oil-in-water emulsion according to any one of [1] to [9], wherein the mass ratio of the oil phase content in the preliminary emulsion to the first aqueous phase content is 0.1 or more and 3 or less.

[0044]

[11] A method for producing an oil-in-water emulsion according to any one of [1] to

[10] , wherein the mass ratio of the content of the oil phase in the pre-emulsified emulsion to the content of the first aqueous phase is 0.1 or more and 2 or less.

[0045]

[12] A method for producing an oil-in-water emulsion according to any one of [1] to

[11] , wherein the average particle size of the oil phase in the pre-emulsified emulsion is 2000 μm or less.

[0046]

[13] A method for producing an oil-in-water emulsion according to any one of [1] to

[12] , wherein the average particle size of the oil phase in the pre-emulsified emulsion is 1000 μm or less.

[0047]

[14] A method for producing an oil-in-water emulsion according to any one of [1] to

[13] , wherein the average particle size of the oil phase in the pre-emulsified emulsion is 1 μm or more and 500 μm or less.

[0048]

[15] A method for producing an oil-in-water emulsion according to any one of [1] to

[14] , wherein the average particle size of the oil phase in the pre-emulsified emulsion is 10 μm or more and 100 μm or less.

[0049]

[16] A method for producing an oil-in-water emulsion according to any one of [1] to

[15] , wherein the viscosity of the preliminary emulsion at the temperature when it is added to the second aqueous phase by jet is 1 mPa·s or more and 15,000 mPa·s or less.

[0050]

[17] A method for producing an oil-in-water emulsion according to any one of [1] to

[16] , wherein the viscosity of the preliminary emulsion at the temperature when it is added to the second aqueous phase by jet is 1 mPa·s or more and 10,000 mPa·s or less.

[0051]

[18] A method for producing an oil-in-water emulsion according to any one of [1] to

[17] , wherein the viscosity of the preliminary emulsion at the temperature when it is added to the second aqueous phase by jet is 1 mPa·s or more and 6000 mPa·s or less.

[0052]

[19] A method for producing an oil-in-water emulsion according to any one of [1] to

[18] , wherein the viscosity of the preliminary emulsion at the temperature when it is added to the second aqueous phase by jet is 10 mPa·s or more and 6000 mPa·s or less.

[0053]

[20] A method for producing an oil-in-water emulsion according to any one of [1] to

[19] , wherein the viscosity of the second aqueous phase (temperature at which the preliminary emulsion is added in a jet) is lower than the viscosity of the preliminary emulsion (temperature at which it is added in a jet to the second aqueous phase).

[0054]

[21] A method for producing an oil-in-water emulsion according to any one of [1] to

[20] , wherein the second aqueous phase has the same constituent components as the first aqueous phase of the pre-emulsified emulsion.

[0055]

[22] A method for producing an oil-in-water emulsion according to any one of [1] to

[21] , wherein the average particle size of the oil phase in the oil-in-water emulsion produced is 35 μm or less.

[0056]

[23] A method for producing an oil-in-water emulsion according to any one of [1] to

[22] , wherein the average particle size of the oil phase in the oil-in-water emulsion produced is 30 μm or less.

[0057]

[24] A method for producing an oil-in-water emulsion according to any one of [1] to

[23] , wherein the average particle size of the oil phase in the oil-in-water emulsion produced is 1 μm or more and 20 μm or less.

[0058]

[25] A method for producing an oil-in-water emulsion according to any one of [1] to

[24] , wherein the linear velocity of the pre-emulsified material when it is added to the second aqueous phase by jet is 5 m / s or more.

[0059]

[26] A method for producing an oil-in-water emulsion according to any one of [1] to

[25] , wherein the linear velocity when the preliminary emulsion is added to the second aqueous phase by jet is 5 m / s or more and 100 m / s or less.

[0060]

[27] A method for producing an oil-in-water emulsion according to any one of [1] to

[26] , wherein the linear velocity when the preliminary emulsion is added to the second aqueous phase by jet is 10 m / s or more and 100 m / s or less.

[0061]

[28] A method for producing an oil-in-water emulsion according to any one of [1] to

[27] , wherein the oil phase comprises an oil and / or silicone.

[0062]

[29] A method for producing an oil-in-water emulsion according to

[28] , wherein the oil contains one or more of the following: alcohol, ester oil, hydrocarbon oil, dialkyl ether compound, amine compound, amide compound, oil and fat, and higher fatty acid.

[0063]

[30] A method for producing an oil-in-water emulsion according to any one of [1] to

[29] , wherein the oil phase contains silicone.

[0064]

[31] A method for producing an oil-in-water emulsion according to any one of [1] to

[30] , wherein the preliminary emulsion is added to the second aqueous phase by jet using a nozzle.

[0065]

[32] The method for producing an oil-in-water type emulsion according to

[31] , wherein the inner diameter of the nozzle is 0.01 mm or more and 20 mm or less.

[0066]

[33] The method for producing an oil-in-water type emulsion according to

[31] , wherein the inner diameter of the nozzle is 0.05 mm or more and 10 mm or less.

[0067]

[34] The method for producing an oil-in-water type emulsion according to

[31] , wherein the inner diameter of the nozzle is 0.1 mm or more and 1 mm or less.

[0068]

[35] The shear rate during the jet addition of the preliminary emulsion to the second aqueous phase is 0.25 × 10^4 s -1 or more and 50 × 10^4 s -1 or less. The method for producing an oil-in-water type emulsion according to any one of [1] to

[34] .

[0069]

[36] The shear rate during the jet addition of the preliminary emulsion to the second aqueous phase is 0.5 × 10^4 s -1 or more and 40 × 10^4 s -1 or less. The method for producing an oil-in-water type emulsion according to any one of [1] to

[34] .

[0070]

[37] The shear rate during the jet addition of the preliminary emulsion to the second aqueous phase is 1 × 10^4 s -1 or more and 30 × 10^4 s -1 or less. The method for producing an oil-in-water type emulsion according to any one of [1] to

[34] .

Example

[0071] (Oil-in-water type emulsion production device) FIG. 1 shows the configuration of an oil-in-water type emulsion production device 10 used in this example.

[0072] The oil-in-water type emulsion production device 10 includes a preliminary tank 11 and a compounding tank 12. A liquid supply pipe 13 extends from the bottom of the preliminary tank 11 and is connected to a circular jet nozzle 14 provided on the bottom side surface of the compounding tank 12. A pump 15 for liquid feeding is provided in the liquid supply pipe 13.

[0073] (Manufacturing of oil-in-water emulsions) <Example 1 and Comparative Example 1> In Example 1, an oil-in-water pre-emulsification L1 was prepared, in which the oil phase with the composition shown in Table 1 was dispersed in the first aqueous phase, with a mass ratio of oil phase to first aqueous phase of 0.5. This pre-emulsification L1 was then placed in the pre-tank 11. A second liquid phase L2 with the composition shown in Table 1 was prepared, and this second liquid phase L2 was placed in the blending tank 12. The commercially available materials used to prepare the oil phase and first aqueous phase of the pre-emulsification L1, as well as the second aqueous phase L2, are as follows.

[0074] Silicone: Methylcyclopentasiloxane (TSF405A, manufactured by Momentive) Oil: Ethylhexyl methoxycinnamate (Ubinal MC80, manufactured by BASF Japan) Thickener: Locust bean gum (Soarlocust A120, manufactured by Mitsubishi Chemical Foods Co., Ltd.) Emulsifying stabilizer: Polyvinyl alcohol (Gosenol EG-05, manufactured by Mitsubishi Chemical Corporation)

[0075] Then, by operating pump 15 (diaphragm pump), the preliminary emulsion L1 from the preliminary tank 11 was supplied to the second liquid phase L2 in the mixing tank 12 via the liquid supply pipe 13 under the conditions described in Table 1. At this time, the preliminary emulsion L1 was discharged into the second liquid phase L2 from a jet nozzle 14 with an inner diameter of 0.35 mm to produce an oil-in-water emulsion. At this time, the ejection and diffusion of the preliminary emulsion L1 from the jet nozzle 14 could be visually confirmed through the transparent wall of the mixing tank 12.

[0076] In Comparative Example 1, the same procedure as in Example 1 was followed, except that a water-in-oil pre-emulsifier and a second liquid phase were used, with an oil phase / first aqueous phase mass ratio of 5.0, prepared so that the composition of the final oil-in-water emulsion was the same as in Example 1.

[0077] <Examples 2 to 10 and Comparative Example 2> The same procedure as in Example 1 was performed, except that the conditions described in Tables 1 to 5 were changed.

[0078] <Examples 11 and 12> In Example 11, an oil-in-water pre-emulsification L1 was prepared, in which the oil phase with the composition shown in Table 6 was dispersed in the first aqueous phase, with a mass ratio of oil phase to first aqueous phase of 0.5. This pre-emulsification L1 was then placed in the pre-tank 11. A second liquid phase L2 with the composition shown in Table 6 was prepared, and this second liquid phase L2 was placed in the blending tank 12. The commercially available materials used to prepare the oil phase and first aqueous phase of the pre-emulsification L1, as well as the second aqueous phase L2, are as described above.

[0079] Then, by operating the pump 15 (rotary pump), the preliminary emulsion L1 from the preliminary tank 11 was supplied to the second liquid phase L2 in the mixing tank 12 via the liquid supply pipe 13 under the conditions described in Table 6. At this time, the preliminary emulsion L1 was discharged into the second liquid phase L2 from the jet nozzle 14 with an inner diameter of 5 mm to produce an oil-in-water emulsion. At this time, it was possible to visually confirm from above the mixing tank 12 that the preliminary emulsion L1 was being ejected from the jet nozzle 14 and diffusing.

[0080] In Example 12, the same procedure as in Example 11 was performed, except that the conditions listed in Table 6 were changed.

[0081] [Table 1]

[0082] [Table 2]

[0083] [Table 3]

[0084] [Table 4]

[0085] [Table 5]

[0086] [Table 6]

[0087] (Measurement of average particle size of the oil phase) For each of the preliminary emulsions L1 obtained in Examples 1 to 12 and Comparative Example 2, the average particle size (22°C) of the oil phase was measured as an area-based average particle size using the laser diffraction / scattering method with a laser diffraction / scattering particle size distribution analyzer (LA-960S, Horiba, Ltd.). Similarly, for each of the oil-in-water emulsions obtained in Examples 1 to 12 and Comparative Examples 1 and 2, the average particle size (22°C) of the oil phase was measured. The average particle size of the oil phase in the oil-in-water emulsions obtained in Examples 1 to 12 was smaller than the inner diameter of the circular jet nozzle 14 used in each example. In Examples 1 to 12, it was visually confirmed that the preliminary emulsion L1 was ejected from the jet nozzle 14 and diffused. Therefore, in Examples 1 to 12, the state of the fluid discharged from the jet nozzle 14 was determined to be a jet state. The results are shown in Tables 1 to 6. In Comparative Example 1, measurement could not be performed because the emulsified state of the preliminary emulsion could not be maintained.

[0088] (Viscosity measurement) The viscosity (at 22°C) of the preliminary emulsion L1 and second aqueous phase L2 obtained in each of Examples 1 to 12 and Comparative Example 2 was measured using a Type B viscometer (BL, manufactured by Toki Sangyo Co., Ltd.) under the following conditions. Similarly, the viscosity of the oil-in-water emulsion obtained in each of Examples 1 to 12 and Comparative Examples 1 to 2 was measured. The results are shown in Tables 1 to 6. The measurement temperature was room temperature (22°C), the same as when the preliminary emulsion L1 was added to the second liquid phase L2.

[0089] For viscosity of 50 mPa·m or less: Rotor No. 1, rotation speed 60 rpm, measurement time 1 minute. For viscosity exceeding 50 mPa·m but less than 20,000 Pa·m: Rotor No. 2, rotation speed 6 rpm, measurement time 1 minute. For viscosity levels of 20,000 mPa·m or higher: Rotor No. 4, rotation speed 6 rpm, measurement time 1 minute. [Industrial applicability]

[0090] This invention is useful in the technical field of methods for producing oil-in-water emulsions. [Explanation of Symbols]

[0091] 10 Oil-in-water emulsion production equipment 11 Reserve tank 12 Blending tank 13 Liquid supply pipe 14. Jet nozzle (jet discharge section) 15 pumps L1 Pre-emulsified L2 2nd liquid phase

Claims

1. A method for producing an oil-in-water emulsion, comprising adding an oil-in-water preliminary emulsion, in which the oil phase is dispersed in a first aqueous phase, to a second aqueous phase by jet, A method for producing an oil-in-water emulsion, wherein the linear velocity when the pre-emulsified material is added to the second aqueous phase by jet is 10 m / s or more and 100 m / s or less.

2. A method for producing an oil-in-water emulsion, comprising adding an oil-in-water preliminary emulsion, in which the oil phase is dispersed in a first aqueous phase, to a second aqueous phase by jet, A method for producing an oil-in-water emulsion, wherein the shear rate when the pre-emulsified material is added to the second aqueous phase by jet is 0.25 million s⁻¹ or more and 500,000 s⁻¹ or less.

3. A method for producing an oil-in-water emulsion according to claim 1 or 2, wherein the viscosity at the temperature when the preliminary emulsion is added to the second aqueous phase in a jet is 0.1 mPa·s or more and 20,000 mPa·s or less.

4. A method for producing an oil-in-water emulsion according to any one of claims 1 to 3, wherein the viscosity at the temperature when the preliminary emulsion is added to the second aqueous phase in a jet is 1 mPa·s or more and 10,000 mPa·s or less.

5. A method for producing an oil-in-water emulsion according to any one of claims 1 to 4, comprising using a mixing tank having a jet discharge section, and jet-adding the pre-emulsified material from the jet discharge section into the second aqueous phase stored in the mixing tank.

6. A method for producing an oil-in-water emulsion according to any one of claims 1 to 5, wherein the mass ratio of the oil phase content in the preliminary emulsion to the first aqueous phase content is 0.01 or more and 4 or less.

7. A method for producing an oil-in-water emulsion according to any one of claims 1 to 6, wherein the average particle size of the oil phase in the pre-emulsified emulsion is 2000 μm or less.

8. A method for producing an oil-in-water emulsion according to any one of claims 1 to 7, wherein the average particle size of the oil phase in the pre-emulsified emulsion is 1 μm or more and 500 μm or less.

9. A method for producing an oil-in-water emulsion according to any one of claims 1 to 8, wherein the viscosity of the pre-emulsified material at the temperature when it is jet-added to the second aqueous phase is 1 mPa·s or more and 15,000 mPa·s or less.

10. A method for producing an oil-in-water emulsion according to any one of claims 1 to 9, wherein the viscosity of the second aqueous phase (at the temperature when the preliminary emulsion is added in a jet) is lower than the viscosity of the preliminary emulsion (at the temperature when it is added in a jet to the second aqueous phase).

11. A method for producing an oil-in-water emulsion according to any one of claims 1 to 10, wherein the second aqueous phase has the same constituent components as the first aqueous phase of the preliminary emulsion.

12. A method for producing an oil-in-water emulsion according to any one of claims 1 to 11, wherein the oil phase contains an oil agent and / or silicone.

13. A method for producing an oil-in-water emulsion according to any one of claims 1 to 12, wherein the average particle size of the oil phase in the oil-in-water emulsion is 35 μm or less.

14. A method for producing an oil-in-water emulsion according to any one of claims 1 to 13, wherein the pre-emulsified material is added to the second aqueous phase by jet using a nozzle.

15. A method for producing an oil-in-water emulsion according to any one of claims 1 to 14, wherein the linear velocity when the pre-emulsified material is added to the second aqueous phase by jet is 5 m / s or more.

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