Droplet or bubble generating device, droplet or bubble generation method, or method for producing droplet or bubble dispersion composition

Abstract

This droplet or bubble generating device for generating droplets or bubbles in a liquid continuous phase comprises a cylindrical body having a plurality of pores in a wall surface thereof, and a helical partitioning structure fixedly disposed inside the cylindrical body, wherein: the helical partitioning structure includes a core rod that is concentric with the cylindrical body, and a helical partition that is joined to the core rod and is formed in a helical shape in the axial direction of the core rod; and an internal space formed inside the cylindrical body by the cylindrical body and the helical partition structure has a cross-sectional area, in a cross section perpendicular to the axial direction of the cylindrical body, that is smaller on an inflow side, which is one opening side of the cylindrical body, than on an outflow side, which is the other opening side of the cylindrical body.

Description

Droplet or bubble generator, method for generating a droplet or a bubble, or method for producing a droplet or bubble dispersion composition

[0001] The present disclosure relates to a droplet or bubble generator, a method for generating a droplet or a bubble, or a method for producing a droplet or bubble dispersion composition.

[0002] There is a monodisperse droplet mass production technology for bio and industrial functional materials. In the direct membrane emulsification method used there, droplets are generated by the shear force of the liquid flowing in the pipe against the pipe wall. Usually, the linear velocity of the liquid is slower near the pipe wall. Therefore, the shear force weakens as it approaches the wall from the center of the pipe, and it is difficult to produce droplets with a small particle size with respect to the pore diameter with good productivity. Further, in the longitudinal direction of the pipe-shaped porous membrane, there is a problem that the shear force applied to the emulsification site of the porous membrane is non-uniform, so that the size distribution of the generated droplets becomes wide.

[0003] In order to solve these problems, a method is known in which a swirling flow of a preliminary composition in which a dispersed-phase fluid is dispersed in a continuous-phase liquid is generated along the outer circumference of a cylindrical body composed of a porous membrane, and the preliminary composition is permeated through the porous membrane (Patent Document 1). Also known is a crossflow device including a tubular membrane adapted to be located inside a tubular sleeve and an insert adapted to be located inside the tubular membrane (Patent Document 2).

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-223526 Patent Document 2: Japanese Patent Application Laid-Open No. 2021-502249

[0005] In the method of generating a swirling flow, the shear force in the longitudinal direction is not maintained, and a large amount of continuous phase may be required for droplet production, and there is room for improvement in terms of droplet productivity. Also, in the method using an insert, the shear force in the longitudinal direction becomes excessive, and the generated droplets may coalesce, and there is room for improvement in terms of the size distribution of the droplets. Thus, a method for producing droplets with a uniform size with good productivity has not been known.

[0006] This disclosure has been made in view of the above circumstances. One embodiment of this disclosure aims to solve the problem of producing droplets or bubbles with a narrow size distribution and with high productivity, and to provide a droplet or bubble generating apparatus, a method for generating droplets or bubbles, or a method for producing a droplet or bubble dispersion composition.

[0007] The following embodiments are included as specific means to solve the above problems.

[0008] <1> A droplet or bubble generating device for generating droplets or bubbles in a continuous liquid phase, comprising a cylindrical body having a plurality of pores on its wall surface, and a helical partition structure fixedly positioned inside the cylindrical body, wherein the helical partition structure has a core rod concentric with the cylindrical body and a helical partition connected to the core rod and formed helically in the axial direction of the core rod, and the internal space formed inside the cylindrical body by the cylindrical body and the helical partition structure has a cross-sectional area perpendicular to the axial direction of the cylindrical body, where the outflow side, which is the other opening side of the cylindrical body, is larger than the inflow side, which is the other opening side of the cylindrical body. <2> The droplet or bubble generating device according to <1>, wherein the cross-sectional area gradually increases from the inflow side to the outflow side in the axial direction of the cylindrical body. <3> A droplet or bubble generating device according to <1> or <2>, wherein the spiral partition structure has at least one of the following structures: the diameter of the core rod decreases from the inlet side to the outlet side in the axial direction of the core rod, and the spiral pitch in the spiral partition increases from the inlet side to the outlet side in the axial direction of the core rod. <4> A droplet or bubble generating device according to any one of <1> to <3>, wherein the volume of the internal space is 10% or more and 80% or less of the volume inside the cylindrical body. <5> A droplet or bubble generating device according to any one of <1> to <4>, wherein the thickness of the spiral partition structure at the radial end of the spiral partition is 10% or more and 80% or less based on the thickness at the joint between the core rod and the spiral partition. <6> The droplet or bubble generating device according to any one of <1> to <5>, wherein the thickness of the spiral partition structure is greater than 0.5 mm at the joint between the core rod and the spiral partition, and 0.5 mm or less at the radial end of the spiral. <7> The droplet or bubble generating device according to any one of <1> to <6>, wherein the outermost diameter of the spiral partition structure is 80% or more and 99% or less based on the inner diameter of the cylindrical body. <8> The droplet or bubble generating device according to any one of <1> to <7>, wherein the difference between the outermost diameter of the spiral partition structure and the inner diameter of the cylindrical body is 0.5 mm or less. <9> The droplet or bubble generating device according to any one of <1> to <8>, wherein the material of the spiral partition structure is metal or resin. <10> The droplet or bubble generating device according to any one of <1> to <9>, wherein the cylindrical body is a porous glass body.<11> The droplet or bubble generating apparatus according to any one of <1> to <10>, wherein the cylindrical body is a porous body obtained by processing a metal pipe with pores of 0.1 μm to 200 μm in diameter. <12> A method for generating droplets or bubbles using the droplet or bubble generating apparatus according to any one of <1> to <11>, comprising the steps of: supplying a continuous phase into the interior of the cylindrical body from one opening of the cylindrical body; supplying a raw material for droplets or bubbles into the interior of the cylindrical body; and recovering a composition containing droplets or bubbles and a continuous phase from the other opening of the cylindrical body. <13> A method for producing a droplet or bubble dispersion composition using a droplet or bubble generating apparatus described in any one of <1> to <11>, comprising the steps of: supplying a continuous phase into the interior of a cylindrical body from one opening of the cylindrical body; supplying a droplet raw material or bubble raw material into the interior of the cylindrical body; and recovering a composition containing droplets or bubbles and the continuous phase from the other opening of the cylindrical body.

[0009] According to one embodiment of the present disclosure, it is possible to provide a droplet or bubble generating apparatus, a method for generating droplets or bubbles, or a method for producing a droplet or bubble dispersion composition that can generate droplets or bubbles with a narrow size distribution and with high productivity.

[0010] Figure 1 is a schematic cross-sectional view illustrating a droplet or bubble generating device. Figure 2A is an explanatory diagram illustrating a screw body included in the droplet or bubble generating device. Figure 2B is a schematic cross-sectional view illustrating the fixing of the screw body in the droplet or bubble generating device. Figure 3 is an explanatory diagram illustrating a screw body with an adjusted core diameter. Figure 4 is an explanatory diagram illustrating a screw body with adjusted core diameter and helical partition pitch. Figure 5 is a schematic cross-sectional view illustrating the sealing of a porous body. Figure 6 is a schematic cross-sectional view illustrating the sealing of a porous body at the inlet. Figure 7 is a schematic cross-sectional view illustrating the sealing of a porous body at the outlet. Figure 8 is a schematic cross-sectional view illustrating the sealing of a porous body at the inlet. Figure 9 is a schematic cross-sectional view illustrating the sealing of a porous body at the outlet. Figure 10 is a schematic side view illustrating a unit comprising multiple droplet or bubble generating devices. Figure 11 is a schematic side view illustrating a unit comprising multiple droplet or bubble generating devices. Figure 12 is an explanatory diagram illustrating a droplet or bubble generating system including a droplet or bubble generating device. Figure 13 is a graph of droplet size distribution obtained in Example 3, with the horizontal axis representing droplet diameter [μm] and the vertical axis representing frequency [%]. Figure 14 is a graph of droplet size distribution obtained in Comparative Example 1, with the horizontal axis representing droplet diameter [μm] and the vertical axis representing frequency [%]. Figure 15 is an optical microscope image of the droplet obtained in Example 3. Figure 16 is an optical microscope image of the droplet obtained in Comparative Example 1.

[0011] The following describes in detail a droplet or bubble generating apparatus, a method for generating droplets or bubbles, or a method for manufacturing a droplet or bubble dispersion composition. The following descriptions of components may be based on typical embodiments of this disclosure, but this disclosure is not limited to such embodiments.

[0012] In this disclosure, numerical ranges indicated using "~" mean ranges that include the numerical values ​​before and after "~" as the lower and upper limits, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. Furthermore, in each drawing, identical or corresponding parts are denoted by the same or similar reference numerals, and redundant explanations are omitted. Also, in each drawing, to avoid complexity, only one of several identical parts may be denoted by a reference numeral. In this specification, the term "process" is included not only in the sense of an independent process, but also in the sense of a process that achieves its intended function, even if it cannot be clearly distinguished from other processes. In this disclosure, when describing droplets or bubbles, if one is described as an example, the same applies to the other. Therefore, the description of droplets also applies to bubbles.

[0013] [Droplet or Bubble Generating Apparatus] A droplet or bubble generating apparatus in one embodiment of the present disclosure is a droplet or bubble generating apparatus that generates droplets or bubbles in a continuous phase which is a liquid, and comprises a cylindrical body having a plurality of pores on its wall surface and a helical partition structure fixedly arranged inside the cylindrical body. The helical partition structure has a core rod concentric with the cylindrical body and a helical partition coupled to the core rod and formed helically in the axial direction of the core rod. The internal space formed inside the cylindrical body by the cylindrical body and the helical partition structure has a cross-sectional area perpendicular to the axial direction of the cylindrical body, where the outflow side, which is the other opening side of the cylindrical body, is larger than the inflow side, which is the other opening side of the cylindrical body.

[0014] The process leading to one embodiment of this disclosure will be explained. We found that a device in which a screw-shaped helical partition structure is inserted into a cylindrical body is suitable as a droplet or bubble generating device that can produce droplets or bubbles as monodisperse droplets or monodisperse bubbles with a narrow size distribution in a high productivity manner. By using this device, it is possible to improve the shear force by narrowing the clearance between the helical partition structure and the cylindrical body while preventing the coalescence of the generated droplets, and by maintaining a swirling flow in the longitudinal direction (i.e., the axial direction of the cylindrical body) inside the cylindrical body, so that monodisperse droplets can be produced in a high productivity manner.

[0015] Furthermore, in order to increase productivity by increasing the amount of monodisperse droplets produced per unit time through an increase in the supply of raw materials, the shape of the helical partition structure was investigated. As a result, it was found that in the internal space formed inside the cylindrical body by the cylindrical body and the helical partition structure, by making the cross-sectional area of ​​the section perpendicular to the axial direction of the cylindrical body larger on the outflow side (the other opening side of the cylindrical body) than on the inflow side (the other opening side of the cylindrical body), droplets or bubbles can be produced more productively in a monodisperse state, that is, with a narrow size distribution.

[0016] The mechanism by which the above effects are achieved is not clear, but it is speculated as follows: In a cylindrical droplet or bubble-making apparatus, when droplets merge downstream of the apparatus, the shear rate of the fluid flowing in the internal space increases due to the merging of droplets. Furthermore, regarding viscosity, which is a factor in shear force, if, for example, droplets of high-viscosity oil merge, the viscosity of the fluid containing the droplets increases. In other words, the shear rate and viscosity increase continuously due to the merging of droplets, resulting in non-uniform shear force downstream of the apparatus.

[0017] In one embodiment of this disclosure, the cylindrical body and the helical partition structure are presumed to provide an appropriate balance between the reduction in shear rate, the increase in viscosity of the fluid containing the droplets, and the pseudoplasticity (decrease in viscosity when shear is applied) of the droplet dispersion composition when droplets merge inside the cylindrical body, particularly downstream of the cylindrical body. Specifically, it is presumed that the helical outer diameter of the helical partition structure maintains a swirling flow, and the helical partition suppresses the coalescence of droplet formation, while the core of the helical partition structure and the pitch of the helical partitions control the shear rate, viscosity, and pseudoplasticity of the fluid flowing through the internal space of the cylindrical body.

[0018] As shown in Figure 1, a droplet or bubble generating device 10 in one embodiment of the present disclosure comprises a porous body 11 having a plurality of pores on its walls, which is a cylindrical body, and a screw body 12, which is a helical partition structure, disposed inside the porous body 11. The housing 13 is an outer cylinder that surrounds the entire porous body 11. The screw body 12 is fixedly disposed inside the porous body 11. The porous body 11 is surrounded by the housing 13 at a predetermined distance from the outer surface of the porous body 11 and the inner surface of the housing 13, such that a space 14 is formed between the outer surface of the porous body 11 and the inner surface of the housing 13. A liquid or gas, which is the dispersed phase D, is introduced into the space 14. Therefore, the housing 13 has a dispersed phase inlet 15 at least at one location on its outer surface for introducing the liquid or gas into the space 14. Furthermore, the housing 13 has a continuous phase inlet 16 for introducing a liquid that becomes the continuous phase C. The continuous phase inlet 16 is configured to communicate with the internal space 18, which is the interior of the porous body 11 surrounded by the housing 13. The internal space 18 is a space formed inside the porous body 11 by the porous body 11 and the screw body 12. In this way, the continuous phase C introduced from the continuous phase inlet 16 flows through the internal space 18 in the longitudinal direction from the inlet side to the outlet side of the porous body 11 (i.e., in the x direction), and at the outlet side, it is discharged as an emulsion M containing the continuous phase C and generated droplets or bubbles from the outlet 17 formed in the housing 13, which communicates with the internal space 18. In the cylindrical porous body 11 having one opening and the other opening, the inlet side is the opening side of the housing 13 on the continuous phase inlet 16 side, and the outlet side is the opening side of the housing 13 on the outlet 17 side. The air vent 21 is an air vent when the continuous phase C is filled, and air V is discharged from the air vent 21.

[0019] In the droplet or bubble generating apparatus 10, the internal space 18 has a larger cross-sectional area on the outlet side 17 than on the continuous phase inlet side 16, based on the cross-sectional area perpendicular to the axial direction of the porous body 11. When using a cylindrical body and a helical partition structure, by satisfying the above requirements regarding the cross-sectional area of ​​the internal space, as described above, the shear rate, viscosity, and pseudoplasticity are all controlled, and monodisperse droplets with a narrow size distribution can be produced with high productivity. High productivity means producing more monodisperse droplets per unit time.

[0020] To ensure that the cross-sectional area perpendicular to the axial direction of the cylindrical body is larger on the outflow side than on the inflow side within the internal space, any method that adjusts the cross-sectional area as described above can be employed. For example, the cross-sectional area can be adjusted by adjusting the inner diameter of the cylindrical body or by adjusting the shape of the helical partition structure. Among these, adjusting the shape of the helical partition structure is preferable because it allows for a simpler way to satisfy the above-mentioned cross-sectional area requirement. The shape of such a helical partition structure will be described later.

[0021] The cross-sectional area of ​​the internal space preferably increases gradually from the inlet side to the outlet side in the axial direction of the cylindrical body. This is because the shear rate, viscosity, and pseudoplasticity of the fluid flowing through the internal space are all more favorably controlled. The increase may be stepwise or continuous, but from the viewpoint of favorably controlling the shear rate, viscosity, and pseudoplasticity of the fluid flowing through the internal space, continuous is preferred.

[0022] [Cylindrical Body] A cylindrical body is a hollow member having multiple pores on its walls for liquid or gas to pass from the outside to the inside and form droplets or bubbles. For example, a cylindrical body may be a porous body made by laser-processing a metal pipe such as SUS with pores ranging in diameter from 0.1 μm to 200 μm. Alternatively, a cylindrical body may be a porous glass body. An example of a porous glass body is an SPG (Shirasu Porous Glass) film. SPG films can be purchased, for example, from SPG Techno Co., Ltd. Alternatively, a cylindrical body may be any other porous film. Thus, a cylindrical body may be any porous body having a large number of minute through-holes for liquid or gas to pass from the outside to the inside. For example, a cylindrical body is cylindrical in shape, and liquid or gas passes from the outside of the cylinder to the inside of the cylinder through the through-holes.

[0023] As the material for the cylindrical body, known materials such as glass, ceramic, SUS (Steel Use Stainless), and nickel can be used. The diameter of the pores in the cylindrical body can be appropriately selected according to the particle size of the desired dispersed phase. For example, when generating droplets or bubbles on the order of microns, the pore diameter can be appropriately selected from the range of 0.1 μm to 200 μm. The pore diameter may also be selected from a range other than 0.1 μm to 200 μm. The number of pores is not particularly limited. The dimensions of the porous body 11 as a cylindrical body (inner diameter, longitudinal length, surface area, etc.) can be appropriately selected.

[0024] The shape of the cylindrical body is not particularly limited, but it is preferable that its inner diameter is constant in the longitudinal direction. Therefore, it is preferable that the cylindrical body be cylindrical. The longitudinal length of the cylindrical body is also not particularly limited, as long as it can be manufactured and function as a cylindrical body. Typically, it is in the range of 10 mm to 500 mm. Other dimensions may be, for example, an inner diameter of 5 mm to 15 mm, or a thickness of 0.1 mm to 1 mm. Alternatively, the inner diameter of the cylindrical body does not have to be constant, and may be configured to increase or decrease in the longitudinal direction, for example.

[0025] [Spiral Partition Structure] A spiral partition structure is a component placed inside a cylindrical body that forms a spiral flow path. The spiral partition structure has a core rod concentric with the cylindrical body and spiral partitions connected to the core rod and formed spirally in the axial direction of the core rod. Here, the "spiral outer diameter" of the spiral partition structure is the maximum distance between the two ends of the spiral partition passing through the center of the core rod. The "spiral pitch" is the distance between a spiral partition located on a line parallel to the core rod and an adjacent spiral partition. The "spiral thickness" is the thickness of the spiral partition itself.

[0026] As shown in Figure 2A, the screw body 12, which is a helical partition structure, comprises a core rod 121 that is concentric with the cylindrical porous body 11, and screw blades 122, which are helical partitions formed to be wound around the core rod 121 in the longitudinal direction.

[0027] The core rod may be solid or hollow, but it is preferable that it be solid. In this way, the helical partition is fixed and positioned so that it does not move inside the cylindrical body (i.e., it maintains non-rotation without rotating). As shown in Figure 2B, the screw body 12 may be fixed in place within the porous body 11 by pressing a packing 19 made of rubber or the like against it in the direction of the arrow during device assembly. The packing 19 allows for tolerance of the length accuracy of the porous body 11. Note that the device refers to an apparatus configured in a double-cylindrical shape by arranging a cylindrical porous body 11 inside an outer cylinder which is a housing 13.

[0028] The winding direction of the helical partition is not particularly limited. It may be right-handed or left-handed. The term "concentric" above is not limited to cases where the central axis of the cylindrical body and the central axis of the core rod of the helical partition structure coincide, but also includes cases where the central axis of the cylindrical body and the central axis of the core rod of the helical partition structure are misaligned, as long as the helical partition structure achieves the effects of this disclosure.

[0029] The material of the helical partition structure is not particularly limited. For example, it may be made of resin or stainless steel. If the material is stainless steel, it may be, for example, SUS304, SUS630, or SUS316L. From the viewpoint of realizing a desirable fluid flow state, it is preferable that the material of the helical partition structure is metal or resin. Using these materials, the helical partition structure may be manufactured by 3D printing, machining, casting, or a combination thereof. The length of the helical partition structure is not particularly limited as long as the effect of inserting the helical partition structure is sufficiently obtained. It may be changed as appropriate to match the cylindrical body. Typically, if the inner diameter of the cylindrical body is 10 mm, the maximum length is 500 mm.

[0030] By arranging a helical partition structure inside a cylindrical body, a helical flow path is formed in the longitudinal direction within the cylinder. Therefore, the continuous phase introduced into the cylinder flows through this helical flow path, swirling as it goes. As the continuous phase flows through the helical flow path from the inlet side to the outlet side of the cylinder, the shear force near the cylinder wall is improved. Because the continuous phase flows through the helical flow path, the longitudinal flow velocity within the cylinder is made uniform, the swirl is not attenuated, and the non-uniformity of shear force at longitudinal positions within the cylinder can be eliminated. Furthermore, because of the screw-shaped structure, clearance can be secured between the cylinder wall and the helical partition structure. In other words, because a swirling flow is generated by the helical flow path, the spatial volume can be expanded while maintaining a high shear force on the surface of the cylinder, compared to inserting a solid cylinder. Therefore, the coalescence of generated droplets or bubbles can be suppressed. The "shear force" mentioned above refers to the force caused by the inertial force of a continuous-phase fluid that occurs at the pore exits on the surface of the cylindrical body, in a direction parallel to the surface of the cylindrical body.

[0031] The helical flow path formed by the helical partition structure preferably rotates two or more times within the cylindrical body. More preferably, it rotates three or more times, and particularly preferably four or more times. Therefore, the helical partition is formed on the core rod such that it rotates at least two times, preferably at least three times, and more preferably at least four times around the core rod. With this configuration, the continuous phase flows through the cylindrical body while repeatedly rotating along the wall surface, so that the shear force due to the continuous phase can be made higher near the wall surface of the porous body.

[0032] Preferably, the helical partition structure has at least one of the following structures: a structure in which the diameter of the core rod decreases from the inlet side to the outlet side of the cylindrical body in the axial direction of the core rod, and a structure in which the helical pitch in the helical partition increases from the inlet side to the outlet side of the cylindrical body in the axial direction of the core rod. By having any of the following structures in the helical partition structure, the cross-sectional area of ​​the internal space can be preferably adjusted, and preferably, in the internal space, the cross-sectional area of ​​the section perpendicular to the axial direction of the cylindrical body is larger on the outlet side of the cylindrical body than on the inlet side of the cylindrical body.

[0033] In a structure in which the diameter of the core rod decreases in the axial direction of the core rod from the inlet side to the outlet side of the cylindrical body, the manner of the decrease can be appropriately determined by the type of continuous phase, the type of dispersed phase, the flow velocity, etc. The manner of the decrease may be stepwise or continuous, but from the viewpoint of favorably controlling the shear rate, viscosity, and pseudoplasticity of the fluid flowing in the internal space, it is preferable that it be continuous.

[0034] In a structure in which the diameter of the core rod decreases in the axial direction of the core rod from the inlet side to the outlet side of the cylindrical body, it is preferable that the diameter of the core rod gradually decreases from the inlet side to the outlet side of the cylindrical body. The manner of gradual decrease may be stepwise or continuous, and the rate of gradual decrease may be constant or variable. From the viewpoint of realizing a desirable fluid flow state, it is preferable that the diameter of the core rod be gradually decreased continuously and at a constant rate.

[0035] As shown in Figure 3, the screw body 22, which is a helical partition structure, has a structure in which the diameter d of the core rod 121 decreases in the axial direction from the inlet side to the outlet side of the porous body 11, which is a cylindrical body. The diameter d of the core rod 121 gradually decreases at a similar rate throughout the entire core rod 121 from the inlet side to the outlet side of the porous body 11, and the core rod diameter din on the inlet side is larger than the core rod diameter dout on the outlet side. In the screw body 22, the helical pitch p of the screw blades 122, which are helical partitions, is the same for each of the multiple helical pitches p provided throughout the screw body 22. The screw body 22 makes it possible to make the cross-sectional area of ​​the porous body 11 perpendicular to the axial direction in the internal space 18 larger on the outlet side of the porous body 11 than on the inlet side.

[0036] In a structure where the helical pitch of a helical partition increases from the inlet side to the outlet side of a cylindrical body in the axial direction of the core rod, the manner of increase can be appropriately determined depending on the type of continuous phase, the type of dispersed phase, the flow velocity, etc. The manner of increase may be stepwise or continuous, but from the viewpoint of favorably controlling the shear rate, viscosity, and pseudoplasticity of the fluid flowing in the internal space, it is preferable that it be continuous.

[0037] In a structure where the helical pitch of a helical partition increases from the inlet side to the outlet side of a cylindrical body in the axial direction of the core rod, it is preferable that the helical pitch of the helical partition gradually increases from the inlet side to the outlet side of the cylindrical body. The mode of gradual increase may be stepwise or continuous, and the rate of gradual increase may be constant or variable. From the viewpoint of realizing a desirable fluid flow state, it is preferable that the helical pitch of the helical partition be increased continuously and at a constant rate. With such a helical partition, in the internal space, the cross-sectional area of ​​the section perpendicular to the axial direction of the cylindrical body can be made larger on the outlet side of the cylindrical body than on the inlet side of the cylindrical body.

[0038] In a structure in which the diameter of the core rod decreases from the inlet side to the outlet side of the cylindrical body in the axial direction of the core rod, and the helical pitch in the helical partition increases from the inlet side to the outlet side of the cylindrical body in the axial direction of the core rod, the manner of decrease and increase are the same as described above. Furthermore, it is preferable that the diameter of the core rod gradually decreases from the inlet side to the outlet side of the cylindrical body, and that the helical pitch in the helical partition gradually increases from the inlet side to the outlet side of the cylindrical body, as described above.

[0039] As shown in Figure 4, the screw body 12, which is a helical partition structure, has a structure in which the diameter d of the core rod 121 decreases from the inlet side to the outlet side of the porous body 11, which is a cylindrical body, in the axial direction of the core rod 121, and the helical pitch p of the screw blades 122, which are helical partitions, increases from the inlet side to the outlet side of the porous body 11 in the axial direction of the core rod 121. The diameter d of the core rod 121 decreases at a similar rate throughout the entire core rod 121 from the inlet side to the outlet side of the porous body 11 in the axial direction of the core rod 121, and the core rod diameter din on the inlet side is larger than the core rod diameter dout on the outlet side. Also, the helical pitch p of the screw blades 122 increases at a similar rate throughout the entire core rod 121 from the inlet side to the outlet side of the porous body 11 in the axial direction of the core rod 121, and the helical pitch pin on the inlet side of the screw blades 122 is smaller than the helical pitch pout on the outlet side of the screw blades 122. Such a helical partition structure allows for a more favorable arrangement within the internal space, where the cross-sectional area of ​​the section perpendicular to the axial direction of the cylindrical body is larger on the outlet side of the cylindrical body than on the inlet side.

[0040] In a helical partition structure, the thickness of the helical partition may be the same in the axial direction of the core rod. For example, not only in the case where the diameter of the core rod decreases from the inlet side to the outlet side of the cylindrical body in the axial direction of the core rod, but also in the case where the helical pitch of the helical partition increases from the inlet side to the outlet side of the cylindrical body in the axial direction of the core rod, the greater the helical pitch of the helical partition, the more the helical partition becomes flatter along the core rod, and thus the cross-sectional area of ​​the internal space can be made larger on the outlet side than on the inlet side of the cylindrical body.

[0041] In a helical partition structure, the thickness of the helical partition may be varied along the axial direction of the core rod. When the thickness is varied, it may be stepped or continuous. By varying the thickness of the helical partition, the cross-sectional area of ​​the internal space can be adjusted. For example, the thickness on the outlet side of the cylindrical body may be smaller than the thickness on the inlet side of the cylindrical body. In this case, the diameter of the core rod may be the same or vary along the axial direction of the core rod. Also, the helical pitch of the helical partition may be the same or vary along the axial direction of the cylindrical body. By making the thickness of the helical partition smaller on the outlet side of the cylindrical body than the thickness on the inlet side of the cylindrical body, the area occupied by the helical partition in the internal space becomes smaller on the outlet side, so the cross-sectional area of ​​the internal space can be made larger on the outlet side than on the inlet side of the cylindrical body.

[0042] In a helical partition structure, the helical thickness may be the same or varied at the joint portion between the core rod and the helical partition and at the helical radial end. If it is varied, in a helical partition structure, the thickness at the helical radial end of the helical partition is preferably 10% to 80% of the thickness at the joint portion between the core rod and the helical partition, from the viewpoint of realizing a favorable fluid flow state.

[0043] The specific dimensions of the helical partition structure can be appropriately selected depending on the inner diameter of the cylindrical body and the particle size of the droplets or bubbles to be generated. For example, if the inner diameter of the cylindrical body is 8 mm and particles with a diameter of 200 μm are to be obtained, the outer diameter of the helix of the helical partition structure may be 7 mm to 8 mm, and the core rod diameter may be 5 mm to 6 mm. Thus, it is preferable to design the structure according to the dimensions of the cylindrical body used and the particle size of the droplets or bubbles to be generated.

[0044] The helical partition structure may more precisely adjust the diameter of the droplets or bubbles to be generated by adjusting its design parameters. For example, when the helical pitch of the helical partition structure is narrowed, the flow rate of the continuous phase increases, and the shear force of the continuous phase can be increased. Conversely, when the helical pitch is widened, the flow rate of the continuous phase decreases, and the shear force of the continuous phase can be decreased. The range of the helical pitch is preferably 1 mm to 20 mm, and more preferably 2 mm to 10 mm. Also, when the core rod diameter of the helical partition structure is made thinner, the clearance between the cylindrical body and the helical partition structure becomes wider, and as a result, the flow rate of the continuous phase decreases, and the shear force of the continuous phase can be decreased. When the core rod diameter of the helical partition structure is made thicker, the clearance between the cylindrical body and the helical partition structure becomes narrower, and as a result, the flow rate of the continuous phase increases, and the shear force of the continuous phase can be increased.

[0045] The range of the helix thickness is preferably 0.1 mm to 5 mm, and more preferably 0.3 mm to 2 mm. Thus, the diameter of the droplets or bubbles can be adjusted more finely by the design of the helical partition structure. Note that the decrease in shear force generates larger diameter particles. Conversely, the increase in shear force generates smaller diameter particles.

[0046] For the helical partition structure, it is preferable that the helix thickness is greater than 0.5 mm at the joint portion between the core rod and the helical partition, and 0.5 mm or less at the end portion in the helical diameter direction, and more preferably greater than 0.5 mm at the joint portion between the core rod and the helical partition, and 0.3 mm or less at the end portion in the helical diameter direction. It is preferable in terms of realizing a preferable flow state of the fluid by making the helix thickness different at the joint portion of the core rod and the helical partition and at the end portion in the helical diameter direction.

[0047] By adjusting the outermost diameter of the helical partition structure (i.e., the helical outer diameter), the clearance between the cylindrical body and the helical partition structure may be adjusted. The outermost diameter of the helical partition structure means the largest diameter in the helical partition structure including the helical partition. That is, the outermost diameter of the helical partition structure is the outer diameter of the helical partition structure in a direction perpendicular to the longitudinal direction of the cylindrical body. From the viewpoint of preferably adjusting the shear force of the continuous phase, the outermost diameter of the helical partition structure is preferably 80% or more and 99% or less based on the inner diameter of the cylindrical body, and more preferably 90% or more and 99% or less.

[0048] It is preferable that the clearance (or gap) between the outermost diameter of the helical partition of the helical partition structure and the inner diameter of the cylindrical body is 0.5 mm or less. More preferably, it is 0.4 mm or less, and still more preferably, it is 0.3 mm or less. When the clearance is 0.5 mm or less, the shear force applied to the wall surface of the continuous phase flowing through the helical flow path can be sufficiently obtained.

[0049] The volume of the helical partition structure in the space volume inside the cylindrical body varies due to the helical partition structure. When the volume of the helical partition structure is determined, the space volume of the helical flow path formed inside the cylindrical body is determined. The space volume obtained by removing the volume of the helical partition structure from the space volume inside the cylindrical body is preferably 10% or more and 80% or less of the total space volume inside the cylindrical body. Preferably, it is 10% or more and 60% or less. When the space volume is 10% or more, a clearance for the generated droplets or bubbles can be secured, and it is possible to suppress the droplets or bubbles from colliding and merging with each other. When it is 80% or less, the space inside the cylindrical body is restricted, and the shear force of the continuous phase flowing through the helical flow path can be sufficiently obtained. Note that the space volume obtained by removing the volume of the helical partition structure from the space volume inside the cylindrical body is equal to or substantially equal to the space volume of the helical flow path.

[0050] [Housing] The housing, as a structural element, is a member that surrounds the cylindrical body and forms a space together with the outer surface of the cylindrical body. The space 14 is formed by the housing 13 and the outer surface of the porous body 11, which is the cylindrical body (see Figure 1). The configuration and shape of the housing are not particularly limited, and it is sufficient if it is a structure that can maintain liquid or gas, which will become droplets or bubbles, on the outside of the cylindrical body, or supply liquid or gas to the pores of the cylindrical body. Preferably, it is a structure that ensures uniform inflow pressure of the dispersed phase onto the cylindrical body. For example, the housing may be coaxially symmetrical with respect to the cylindrical body. As an example, the housing may be configured such that the portion surrounding the cylindrical body is a coaxial double cylinder with respect to the cylindrical body. Alternatively, the housing may be configured such that at least the inner surface of the portion surrounding the cylindrical body is a coaxial double cylinder with respect to the cylindrical body. Furthermore, it is preferable that the distance (or gap) between the outer surface of the cylindrical body and the inner surface (i.e., the side) of the housing is at least 1 mm. The housing has a dispersed phase inlet on its outer surface for introducing liquid or gas into the space. The dispersed phase inlet may be one, two, or even more than one. Furthermore, the housing has a continuous phase inlet for introducing a liquid that will become the continuous phase and an outlet for discharging the continuous phase.

[0051] The material of the enclosure is not particularly limited. However, it is preferable that it be resistant to acids, alkalis, or organic solvents. SUS (stainless steel) is one example of such a material.

[0052] [Inlet or Outlet] The structure of the inlet, which is the inlet side of the cylindrical body in a droplet or bubble generating device, or the structure of the outlet, which is the outlet side, will be described. In a droplet or bubble generating device, droplets or bubbles can be generated with high productivity by introducing more continuous phase and dispersed phase at a faster rate. For this reason, it is preferable that the structure of the inlet or outlet in a droplet or bubble generating device be as follows.

[0053] It is preferable that the cylindrical body be more securely sealed and fixed, at least on the inlet side. For example, when the cylindrical body is a porous membrane, the longitudinal dimensions of the cylindrical body may not be the same on the inlet and outlet sides of the device due to intersections. In a droplet or bubble generating device, it is preferable to provide multiple means for fixing the cylindrical body at least on the inlet side. Specifically, it is preferable to provide two means for fixing the cylindrical body at least on the inlet side. Alternatively, two means for fixing the cylindrical body may be provided on both the inlet and outlet sides. The means for fixing multiple cylindrical bodies may be the same or different. For example, the means for fixing the cylindrical body may be fixing means using O-rings.

[0054] By providing multiple means for fixing the cylindrical body at least on the inlet side, sealing can be achieved more reliably even when the longitudinal dimensions of the cylindrical bodies are not the same. In particular, sealing of the cylindrical body is more reliable when introducing a larger amount of continuous phase and dispersed phase, or at a faster rate.

[0055] As shown in Figure 5, the droplet or bubble generating device 10 is provided with two sealing means, sealing means S1 and sealing means S2, which use O-rings to seal the cylindrical porous body 11. This makes it possible to maintain a more reliable sealing state, especially when there are some tolerances in the longitudinal dimensions of the cylindrical porous body 11, or when a large force is applied by introducing more of the continuous phase C and dispersed phase D at a faster rate.

[0056] Furthermore, sealing of the outer diameter of the cylindrical body may affect droplet or bubble formation. On the other hand, cylindrical bodies may have tolerances not only in their longitudinal dimensions but also in their outer diameter. For example, when the cylindrical body is a commercially available porous membrane, the tolerance of the outer diameter of the porous membrane may be as large as ±5%. Therefore, multiple sealing means may be provided in the diameter within a plane perpendicular to the axial direction of the cylindrical body. For example, when using O-rings as sealing means, multiple O-rings of different diameters may be provided. By providing multiple sealing means in the diameter within a plane perpendicular to the axial direction of the cylindrical body, the cylindrical body can be sealed more reliably, even when there are tolerances in the outer diameter or when the flow rate increases.

[0057] As shown in Figure 6, at the inlet 10a of the droplet or bubble generating device 10, the cylindrical porous body 11 is sealed on the axial inlet side of the porous body 11 by a sealing means S1 which is an O-ring. Furthermore, at the axial outlet side of the porous body 11, it is sealed by a sealing means S2b which is an O-ring with a small diameter and a sealing means S2s which is an O-ring with a large diameter. Note that the sealing means S1 may be composed of multiple O-rings of different diameters. As shown in Figure 7, at the outlet 10b of the droplet or bubble generating device 10, the cylindrical porous body 11 is sealed on the axial inlet side of the porous body 11 by a sealing means S1b which is an O-ring with a small diameter and a sealing means S1s which is an O-ring with a large diameter.

[0058] Furthermore, if the diameter of the core rod of the helical partition structure decreases on the outflow side, the diameter on the outflow side becomes smaller when fixing the helical partition structure on both the inflow and outflow sides of the droplet or bubble generation device. As a result, excessive shear force may be applied to the droplets generated when the liquid is delivered at a high flow rate. To address this, the helical partition structure may be fixed only on the inflow side and left as a free end on the outflow side. This ensures a wider diameter of the flow path on the outflow side, and even if excessive shear force is applied when the liquid is delivered at a high flow rate, the destruction of the generated droplets is suppressed. Note that the wider diameter corresponds to the inner diameter of the cylindrical body.

[0059] As shown in Figure 8, at the inlet 10a of the droplet or bubble generating device 10, the screw 12, which is a helical partition structure, can be fixed on the inlet side such that its fixed portion 12a is sandwiched between the members. On the other hand, as shown in Figure 9, at the outlet 10b of the droplet or bubble generating device 10, the screw 12 is not fixed but has a free end, and a wide-diameter flow path is provided near the outlet. Alternatively, a gap may be provided near the outlet in the axial direction of the flow path.

[0060] [Droplet or bubble generating device unit] A single droplet or bubble generating device may be used, or multiple devices may be connected in series to form a unit. As shown in Figure 10 or Figure 11, a droplet or bubble generating device unit 101, which consists of multiple droplet or bubble generating devices connected in series, comprises an inlet side lid 71a, a main body 71b, and an outlet side lid 71c as the unit housing 71. Ten droplet or bubble generating devices 10 are connected in series within the main body 71b. The continuous phase C flows in from the continuous phase inlet 16 installed in the inlet side lid 71a. The dispersed phase D is introduced from the dispersed phase inlet 15 located in the main body 71b. The emulsion M is discharged from the outlet 17 installed in the outlet side lid 71c. Multiple air vents 21 may be provided. An outlet 23 for discharging waste liquid W is also provided. Each of these inlets and outlets is fitted with a valve, which can be operated to remove air during liquid filling and to drain liquid from inside the housing and piping.

[0061] The inlet-side cover 71a has an internal buffer section 72a, and the outlet-side cover 71c has an internal buffer section 72b. The buffer sections 72a and 72b are each in communication with the droplet or bubble generating device 10. The continuous phase C flows through the inlet-side buffer section 72a, and after filling the buffer section 72a, the continuous phase C branches off to the respective droplet or bubble generating devices 10. The emulsion M flows through the outlet-side buffer section 72b, and after filling the buffer section 72b, the emulsion M proceeds to the outlet 17. The buffer section 72a has the function of reducing pump pulsation, flow dynamic pressure, etc. The buffer section 72b has the function of reducing concerns such as the destruction of generated droplets or bubbles. From the viewpoint of the above functions, it is preferable that the buffer sections 72a and 72b each have a large volume. It is preferable that the volumes of the buffer sections 72a and 72b be changed, for example, according to the flow rate. Furthermore, if the volume of the buffer section 72b is changed according to the flow rate, it is preferable to also change the diameter of the outlet 17 according to the flow rate. This helps to suppress droplet breakage.

[0062] Furthermore, the droplet or bubble generating device unit 101 can have a side inlet relative to the unit housing, thereby reducing the dynamic pressure of the continuous phase or dispersed phase flow in the droplet or bubble generating device. By arranging multiple droplet or bubble generating devices in series, suitable droplets or bubbles can be produced with greater productivity. In the droplet or bubble generating device unit 101, the position and arrangement of the porous body 11 can be freely changed as long as the dispersed phase D flows precisely into the porous body 11. In the droplet or bubble generating device unit 101, droplets or bubbles can be suitably generated whether the droplet or bubble generating devices 10 are arranged vertically or horizontally.

[0063] [Dispersed Phase / Continuous Phase] The liquid or gas that forms the dispersed phase is not particularly limited. The liquid that forms the continuous phase is also not particularly limited. For example, when producing an oil-in-water emulsion, the oil phase may be the dispersed phase and the aqueous phase the continuous phase. When producing an emulsion of water in oil, the oil phase may be the continuous phase and the aqueous phase the dispersed phase. Depending on the application, the oil phase may contain two or more types of oil, or may contain components other than oil. Depending on the application, the aqueous phase may contain components other than water. For example, surfactants and viscosity modifiers can be used. Depending on the selection of materials, capsules can also be formed by forming a solid or gel at the interface between the dispersed phase and the continuous phase. The particle size of the dispersed phase may be, for example, 10 μm to 500 μm, or 50 μm to 300 μm. However, it is not limited to these ranges. The particle size may be appropriately selected according to the chosen material.

[0064] To generate bubbles, compressed air (or compressed air), hydrogen, oxygen, nitrogen, noble gases, carbon dioxide, and ozone are introduced as gases. By introducing gases, minute bubbles can be obtained in the continuous phase. For example, fine bubbles (e.g., with a diameter of 100 μm or less) can be obtained. Furthermore, surfactants or the like may be added to the continuous phase to maintain the generated bubbles for a longer period.

[0065] [Method for generating droplets or bubbles] One embodiment of the method for generating droplets or bubbles (hereinafter also referred to as the droplet or bubble generation method) of the present disclosure is a method for generating droplets or bubbles using a droplet or bubble generation apparatus, comprising a step of supplying a continuous phase into the interior of a cylindrical body from one opening of the cylindrical body (hereinafter referred to as the continuous phase supply step) and a step of supplying a raw material for droplets or a raw material for bubbles into the interior of the cylindrical body (hereinafter referred to as the dispersed phase supply step). The droplet or bubble generation method enables the production of droplets or bubbles with a narrow size distribution and high productivity.

[0066] Furthermore, one embodiment of the present disclosure, a method for producing droplet or bubble dispersion compositions (hereinafter also referred to as the method for producing droplet or bubble dispersion compositions), is a method for producing droplet or bubble dispersion compositions using a droplet or bubble generating device, comprising: a step of supplying a continuous phase into the interior of a cylindrical body from one opening of the cylindrical body (hereinafter referred to as the continuous phase supply step); a step of supplying droplet raw materials or bubble raw materials into the interior of the cylindrical body (hereinafter referred to as the dispersion phase supply step); and a step of recovering a composition containing droplets or bubbles and the continuous phase from the other opening of the cylindrical body (hereinafter referred to as the recovery step). The method for producing droplet or bubble dispersion compositions enables the production of droplet or bubble dispersion compositions with a narrow size distribution of generated droplets or bubbles and with high productivity.

[0067] Referring to Figure 12 and, as appropriate, Figure 1, an example of a method for generating droplets or bubbles using a droplet or bubble generation system with a droplet or bubble generation device 10 (hereinafter referred to as generation device 10) will be described. Note that the following description will focus on the generation of droplets, but the method is the same for generating bubbles.

[0068] First, the dispersed phase tank 20, which stores the liquid that will become the dispersed phase, contains the liquid for forming droplets. When pressurized gas is introduced into the dispersed phase tank 20, the stored liquid is injected into the generator 10. The method of injecting the liquid is not particularly limited and can be done using a generally used method. The liquid is sent to the space 14 inside the generator 10 by injection, and then passes through the pores of the porous body 11 and enters the interior of the porous body 11 (dispersed phase supply process). On the other hand, the liquid that will become the continuous phase, stored in the continuous phase container 40, is sent into the porous body 11 inside the generator 10 by the circulation pump 50 (continuous phase supply process). It is preferable to continuously supply the dispersed phase in the dispersed phase supply process. It is also preferable to continuously supply the continuous phase in the continuous phase supply process. The liquid sent into the porous body 11 flows through the helical channel formed by the screw body 12 and moves along the wall surface of the porous body 11 while swirling. At this time, the liquid that has passed through the pores of the porous body 11 and entered the porous body 11 forms particles that are torn off by the shear force of the swirling continuous phase, and these particles float in the continuous phase as a dispersed phase, and are discharged to the outside of the porous body 11 and the generating device 10 together with the continuous phase. The droplet or bubble dispersion composition containing the dispersed phase floating in the discharged continuous phase is recovered (recovery step).

[0069] By using this method for generating droplets or bubbles, or for manufacturing droplet or bubble dispersion compositions, it is possible to mass-produce particles having a uniform particle size on the order of microns. Figure 10 shows an embodiment in which the generated droplets are sent to a continuous phase container 40 and circulated again with the continuous phase. However, the embodiment of the droplet or bubble generating device 10 is not limited to this. For example, there may be an embodiment in which there is no circulation line 41 in Figure 10, and the generated droplets are collected without being circulated.

[0070] A digital pressure gauge 30 may be installed in the flow path of the pressurized gas introduced into the dispersed phase tank 20 to control the pressure of the pressurized gas. Furthermore, air, or an inert gas such as nitrogen or a rare gas can be used as the pressurized gas.

[0071] As described above, in the droplet or bubble generating device according to this disclosure, by arranging a screw body as a helical partition structure inside the cylindrical body to form a helical flow path, the shear force applied to the porous wall surface that generates droplets or bubbles can be increased even at the same flow rate. As a result, it becomes possible to reduce the size of droplets, achieve monodispersion, and concentrate them (i.e., increase the proportion of the dispersed phase in the overall liquid).

[0072] Furthermore, in the droplet or bubble generating apparatus according to this disclosure, the internal space formed inside the cylindrical body by the cylindrical body and the helical partition structure is configured such that the cross-sectional area of ​​the cross section perpendicular to the axial direction of the cylindrical body is larger on the outflow side, which is the other opening of the cylindrical body, than on the inflow side, which is the other opening of the cylindrical body. This allows for appropriate balance between the decrease in shear rate, the increase in viscosity of the fluid containing the droplets, and the pseudoplasticity (decrease in viscosity when shear is applied) of the droplet dispersion composition when droplets merge on the outflow side of the cylindrical body. Therefore, even when the overall flow rate is increased, in addition to reducing the size and concentration of droplets (i.e., increasing the proportion of the dispersed phase in the overall liquid), the size distribution of droplets can be narrowed, and more such droplets can be generated per unit time.

[0073] Furthermore, while a helical channel can be formed by inserting a helical partition structure into the inside of a cylinder, the size, monodispersity, and concentration of droplets or bubbles can also be adjusted by changing the design parameters of this helical partition structure. These design parameters include the clearance between the outermost diameter of the helical partition structure and the inner diameter of the cylinder, the helical pitch, and the core rod diameter. Adjusting these parameters allows for adjustment of the shear force acting on the inner wall of the cylinder and the spatial volume for the helical channel, thereby enabling adjustment of the physical properties of the droplets or bubbles. For example, the shear force changes depending on the helical pitch. A narrower helical pitch results in a greater shear force, allowing for stronger shear force even at the same flow rate. Additionally, the presence of a core rod allows for narrowing the channel and increasing the flow velocity. Thus, a thicker core rod results in a greater shear force.

[0074] Furthermore, as you move downstream, the flow rate of the dispersed phase increases (i.e., the dispersed phase flows in from the outside of the cylindrical body), so the overall flow rate also increases as you move downstream. In this disclosure, by changing the design parameters of the helical partition structure from upstream to downstream as described above, it is possible to control the decrease in shear rate, the balance between the increase in viscosity of the fluid containing droplets and the pseudoplasticity of the droplet dispersion composition, and to more precisely equalize the shear force acting on the inner wall of the porous body from upstream to downstream.

[0075] Furthermore, since the spiral partition structure is simply inserted and fixed, there is no need to significantly increase manufacturing costs. Also, it can be disassembled and cleaned after use. Therefore, there are few concerns regarding hygiene and quality. The spiral partition structure can also be fixed to the cylindrical body by shrink fitting or other methods. When the spiral partition structure is integrated by shrink fitting or other methods, sufficient shear force can be obtained, similar to the case where the clearance is narrow, and it has advantages such as no hassle in attaching and detaching and high reproducibility of installation.

[0076] Currently, there is a growing need for the mass production of uniform droplets, capsules, particles, etc., for industrial use. The droplet or bubble generating apparatus described herein can provide droplets or bubbles at low cost, with high quality and high productivity, to meet diverse needs.

[0077] The present disclosure will be further explained with reference to the following examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples may be modified as appropriate, as long as they do not deviate from the spirit of this disclosure. Therefore, the scope of this disclosure is not limited to the following examples.

[0078] <Examples 1 to 6 and Comparative Examples 1 and 2> In the droplet or bubble generating apparatus 10 shown in Figure 1, droplets were generated using the following screw body. A porous body 11 was used as the cylindrical body (porous cylindrical body). The porous cylindrical body 11 was an SPG (Shirasu Porous Glass) film, with a longitudinal length of 125 mm, an inner diameter of 8.4 mm, an outer diameter of 10 mm, and a pore diameter of 50 μm. A hydrophilic type porous cylindrical body of the above dimensions was used (manufactured by SPG Techno Co., Ltd.). For the screw body (helical partition structure) inserted into the porous cylindrical body, those made of SUS304 material were manufactured by machining. For those made of SUS630 material, those manufactured by 3D printing were used. In both cases, the insertion length of the screw body was 125 mm.

[0079] The screw bodies, which are helical partition structures, are those shown in Table 2. In the column for screw bodies, the outer diameter indicates the outermost diameter. The thickness indicates the thickness of the helical partition; when indicated by a number and an arrow, the first number indicates the thickness at the connection point with the core rod 121, and the number after the arrow indicates the thickness at the tip of the helical partition. The core rod indicates the diameter of the core rod 121 of the helical partition structure; when indicated by a number and an arrow, the first number indicates the diameter at the inlet, and the number after the arrow indicates the diameter at the tip of the outlet (see Figure 3). The pitch indicates the pitch p of the helical partition (see Figure 4); when indicated by a number and an arrow, the first number indicates the pitch at the inlet, and the number after the arrow indicates the pitch at the outlet. In Examples 1 and 2, the screw body 22 shown in Figure 3 was used, and in Examples 3 and 4, the screw body 12 shown in Figure 4 was used. In Examples 3, 4, and 6, the pitch of the screw body was specifically 5 mm at the inlet, and was continuously increased by 1 mm increments, from 5 mm to 6 mm, then 7 mm, then 8 mm, and finally to a pitch of 16.0 mm. However, the final pitch of 16.0 mm was not a complete pitch and ended prematurely. In Example 6, a screw body in which the diameter of the core rod did not change was used, while in Comparative Examples 1 and 2, a screw body in which both the diameter of the core rod and the pitch of the helical partition did not change was used.

[0080] In the "Multiple Units" column of Table 2, the numbers indicate the number of droplet or bubble generating devices 10 used. In Example 5, a unit consisting of 10 droplet or bubble generating devices 10 in series was used (see Figure 10 or Figure 11).

[0081] When inserting the screw body 12 into the porous cylindrical body, the screw body 12 was fixed to the device (MD10L125, manufactured by SPG Techno) via a rubber packing to prevent it from being driven by the flow of the liquid. The device was constructed in a double-cylinder shape by placing the porous cylindrical body 11 inside the outer cylinder housing 13. An oil phase was introduced from the outside of the porous cylindrical body as the dispersed phase, and an aqueous phase was introduced from the inside as the continuous phase, each pumped at different flow rates. Oil phase: coconut oil (manufactured by Fujifilm Wako Pure Chemical Industries) Aqueous phase: pure water with 0.5 mass% of Ryoto sugar ester M1695 (manufactured by Mitsubishi Chemical Corporation) dissolved in it. Oil phase pump: 2NL08F manufactured by Hyoshin Equipment Co., Ltd. Aqueous phase pump: HYSA-16P manufactured by Fuji Techno Industries Co., Ltd.

[0082] In Examples 1 to 5 and Comparative Examples 1 to 2, droplets were produced. In droplet production, the flow rates of the aqueous phase and the oil phase were kept constant, with the ratio of the flow rate of the aqueous phase per unit time to the flow rate of the oil phase per unit time being the ratios shown in Table 2.

[0083] (Cross-sectional area of ​​the internal space) For the screw bodies shown in Table 2, the screw body 12 was inserted into a porous cylindrical body, and the cross-sectional area of ​​the internal space perpendicular to the axial direction of the cylindrical body was measured. The cross-sectional area was measured every 20 mm in the x direction from the starting point of the inner wall of the porous body on the inflow side. The measurement results of the cross-sectional area for the screw body used in Example 6, the screw body 22 used in Examples 1 and 2, the screw body 12 used in Examples 3 and 4, and the screw bodies used in Comparative Examples 1 and 2 are shown in Table 1.

[0084]

[0085] <Evaluation> (Evaluation of droplets) For the generated droplets (granular bodies), the average particle size and average dispersion (CV value) of the particle size were calculated and recorded in Table 2. The CV value of the particle size was calculated using the following formula: CV value of particle size (%) = (Standard deviation of the equivalent circle diameter of the granular bodies / Average particle size of the granular bodies) × 100 Here, the average particle size of the granular bodies is the value measured by the following method. The standard deviation of the equivalent circle diameter of the granular bodies is the standard deviation of the equivalent circle diameter of 5,000 to 10,000 granular bodies calculated in the measurement of the average particle size of the granular bodies. A CV value of 33% or less was considered acceptable.

[0086] -Measurement Method- The droplet diameter (particle size) was measured as follows. Because the obtained emulsion M was highly concentrated, three samples were prepared by dissolving approximately 1% by mass of the obtained emulsion M in a 110 mL vial containing 100 mL of continuous phase C. For each sample, the droplet diameter was measured using a dispersion particle size analyzer (xpt-c, manufactured by PS Prozestechnik). For each sample, the diameters of 5,000 to 10,000 droplets were measured as equivalent circular diameters, and the average value was defined as the "average particle size of the granules." In addition, the "standard deviation of the equivalent circular diameter of the granules" was calculated from the equivalent circular diameters of the measured droplet diameters. The above "equivalent circular diameter" is the area equivalent diameter calculated from the projected area. For each of the three samples, the "average particle size of the granules" and the "CV value of the particle size" were calculated. The three obtained values ​​were averaged and listed in Table 1 as "average particle size" and "average CV value." The "average particle size" or "CV value of particle size" for the three samples were approximately the same.

[0087]

[0088] Figure 13 shows the droplet size distribution graph obtained in Example 3, and Figure 14 shows the droplet size distribution graph obtained in Comparative Example 1. In the droplet size distribution graphs, the horizontal axis represents droplet size [μm], and the vertical axis represents frequency [%]. Figure 15 shows an optical microscope image of the droplet obtained in Example 3, and Figure 16 shows an optical microscope image of the droplet obtained in Comparative Example 1.

[0089] As shown in Table 2, in Examples 1 to 5, which use a droplet or bubble production apparatus according to one embodiment of the present disclosure, in which the cross-sectional area of ​​the cylindrical body perpendicular to the axial direction is larger on the outflow side, which is the other opening side of the cylindrical body than on the inflow side, which is the other opening side of the cylindrical body, it was demonstrated that droplets with a smaller CV value and a narrower size distribution can be obtained compared to Comparative Examples 1 and 2, in which the cross-sectional area of ​​the cylindrical body perpendicular to the axial direction is the same in the axial direction of the cylindrical body.

[0090] The disclosure of Japanese Patent Application No. 2024-169549, filed on 27 September 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A droplet or bubble generating device for generating droplets or bubbles in a continuous liquid phase, comprising: a cylindrical body having a plurality of pores on its wall surface; and a helical partition structure fixedly positioned inside the cylindrical body, wherein the helical partition structure has a core rod concentric with the cylindrical body and a helical partition connected to the core rod and formed helically in the axial direction of the core rod, and the internal space formed inside the cylindrical body by the cylindrical body and the helical partition structure has a cross-sectional area perpendicular to the axial direction of the cylindrical body, where the outflow side (the other opening side) is larger than the inflow side (the other opening side) of the cylindrical body.

2. The droplet or bubble generating apparatus according to claim 1, wherein the cross-sectional area gradually increases in the axial direction of the cylindrical body from the inlet side to the outlet side.

3. The droplet or bubble generating apparatus according to claim 1, wherein the helical partition structure has at least one of the following structures: a structure in which the diameter of the core rod decreases from the inlet side to the outlet side in the axial direction of the core rod, and a structure in which the helical pitch in the helical partition increases from the inlet side to the outlet side in the axial direction of the core rod.

4. The droplet or bubble generating apparatus according to claim 1, wherein the volume of the internal space is 10% or more and 80% or less of the volume inside the cylindrical body.

5. The droplet or bubble generating apparatus according to claim 1, wherein the thickness of the spiral partition structure at the spiral radial end of the spiral partition is 10% or more and 80% or less based on the thickness at the joint portion between the core rod and the spiral partition.

6. The droplet or bubble generating apparatus according to claim 1, wherein the thickness of the helical partition structure is greater than 0.5 mm at the joint between the core rod and the helical partition, and less than or equal to 0.5 mm at the radial end of the helical.

7. The droplet or bubble generating apparatus according to claim 1, wherein the outermost diameter of the helical partition structure is 80% or more and 99% or less based on the inner diameter of the cylindrical body.

8. The droplet or bubble generating apparatus according to claim 1, wherein the difference between the outermost diameter of the helical partition structure and the inner diameter of the cylindrical body is 0.5 mm or less.

9. The droplet or bubble generating apparatus according to claim 1, wherein the helical partition structure is made of metal or resin.

10. The droplet or bubble generating apparatus according to claim 1, wherein the cylindrical body is a porous glass body.

11. The droplet or bubble generating apparatus according to claim 1, wherein the cylindrical body is a porous body obtained by processing a metal pipe with pores having a diameter of 0.1 μm to 200 μm.

12. A method for generating droplets or bubbles using a droplet or bubble generating apparatus according to any one of claims 1 to 11, comprising: a step of supplying the continuous phase into the interior of the cylindrical body from one opening of the cylindrical body; a step of supplying the raw material for the droplets or the raw material for the bubbles into the interior of the cylindrical body; and a step of recovering the composition containing the droplets or bubbles and the continuous phase from the other opening of the cylindrical body.

13. A method for producing a droplet or bubble dispersion composition using a droplet or bubble generating apparatus according to any one of claims 1 to 11, comprising: a step of supplying the continuous phase into the interior of the cylindrical body from one opening of the cylindrical body; a step of supplying the droplet raw material or the bubble raw material into the interior of the cylindrical body; and a step of recovering the composition containing the droplet or bubble and the continuous phase from the other opening of the cylindrical body.

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