Method for manufacturing seamless capsule

Abstract

To stably manufacture a high-quality seamless capsule.SOLUTION: A method for manufacturing a seamless capsule 50 includes a forming step for dripping liquid droplets from a tip 1a of a nozzle 1 to cooling liquid 49 in a flow passage of a forming pipe 10 so as to form a seamless wet capsule 50w from the liquid droplets. The nozzle 1 is provided with an inclined part 25 inclined to the inside of the nozzle 1 from the middle toward the tip 1a. A distance Z between an apex 27 of a space surrounded by a virtual surface 26 formed by extending the outer surface 25a of the inclined part 25 toward below the tip 1a and the upper end 10a of the forming pipe 10 is in a range of -10 mm≤Z≤6 mm. If Z<0, the apex 27 is positioned below the upper end 10a of the forming pipe 10. If Z>0, the apex 27 is positioned above the upper end 10a of the forming pipe 10.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for producing a seamless capsule. [Background technology]

[0002] Patent Document 1 discloses a method for producing spherical seamless capsules by causing droplets to flow downward from the tip of a nozzle into a cooling liquid (hardening liquid) in a flow path of a forming tube, and coating the filling material with a coating material. The nozzle tapers midway. The tip of the nozzle is provided with a tip surface having an opening through which the droplets flow. The tip surface is perpendicular to the central axis of the nozzle and faces horizontally. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-136576 A Summary of the Invention [Problem to be solved by the invention]

[0004] This manufacturing method employs a so-called air nozzle method in which the tip face of the nozzle is positioned above the liquid surface of the cooling liquid. When the outer diameter of the seamless capsule to be manufactured is d, the distance between the tip face of the nozzle and the liquid surface is set within a range of 0.5d to 3d. However, there is still room for improvement in the manufacturing method of seamless capsules with respect to the stable manufacture of high-quality seamless capsules, such as capsules with no cracks in the shell.

[0005] An object of the present invention is to stably produce high-quality seamless capsules. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems, and have come up with the following idea. That is, when the nozzle is tapered (i.e., the nozzle has an inclined portion that inclines inward from the middle of the nozzle toward the tip) and the tip surface of the nozzle is below the liquid level of the cooling liquid, the cooling liquid flows downward along the outer surface of the nozzle and flows into the forming tube through the opening at the upper end of the forming tube. In the process, the cooling liquid flows toward the apex of a space surrounded by a virtual surface that is an extension of the outer surface of the inclined portion toward the bottom of the tip, and a vortex may form near the apex. When such a vortex occurs, the shape of the composite jet flowing out of the nozzle becomes unstable, causing cracks in the shell of the seamless capsule and increasing the variation in the outer diameter of the seamless capsule. Therefore, the inventors came up with the idea that by adjusting the position of this virtual apex rather than the tip surface of the nozzle, the flow of the cooling liquid flowing into the forming tube can be controlled, and therefore high-quality seamless capsules can be stably manufactured. The present inventors have embodied this idea and completed the present invention.

[0007] One aspect of the present invention provides a method for producing seamless capsules, comprising a forming step of dropping droplets from a tip of a nozzle into a cooling liquid in a flow path of a forming tube, and forming seamless wet capsules from the droplets, wherein the nozzle has an inclined portion that inclines inwardly from the middle of the nozzle toward the tip, and a distance Z between an apex of a space enclosed by an imaginary plane formed by extending an outer surface of the inclined portion downward from the tip and an upper end of the forming tube is within a range of -10 mm≦Z≦6 mm, and when Z<0, the apex is located below the upper end of the forming tube, and when Z>0, the apex is located above the upper end of the forming tube.

[0008] In a vertical cross section of the nozzle passing through a central axis of the nozzle, an angle between a pair of straight lines connecting an upper end and a lower end of the outer surface of the inclined portion may be within a range of 20° to 70°.

[0009] In a horizontal cross section of the nozzle perpendicular to a central axis of the nozzle, the outline of the inclined portion may be circular, elliptical or polygonal.

[0010] The coefficient of variation of the particle size of the wet capsules may be 0.1 or less.

[0011] The forming step may include a step of positioning a tip of the nozzle below a liquid level of the cooling liquid.

[0012] The method may further include a drying step of drying the wet capsule to obtain a dry capsule.

[0013] The coefficient of variation of particle size of the dry capsules may be 0.1 or less. Effect of the Invention

[0014] According to the present invention, high-quality seamless capsules can be stably produced. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of a manufacturing apparatus for carrying out a manufacturing method for a seamless capsule according to an embodiment. [Diagram 2] FIG. 2 is an enlarged view of a nozzle and a forming pipe of the manufacturing apparatus of FIG. 1. [Diagram 3] FIG. 3 is a horizontal cross-sectional view of the nozzle taken along line III-III in FIG. 2 . [Figure 4] 13 is a diagram for explaining the distance between a virtual vertex set on the nozzle and the upper end of the forming tube. FIG. [Diagram 5] FIG. 13 is an enlarged view of a nozzle and a forming pipe according to a first modified example. [Figure 6A] FIG. 11 is a horizontal cross-sectional view of a nozzle according to a second modified example. [Figure 6B] FIG. 11 is a horizontal cross-sectional view of a nozzle according to a third modified example. [Figure 7] FIG. 13 is a front view of a nozzle according to a fourth modified example. [Figure 8A] FIG. 13 is a front view of a nozzle according to a fifth modified example. [Figure 8B]FIG. 13 is a front view of a nozzle according to a sixth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment will be described with reference to the drawings. Note that the same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed description thereof will be omitted.

[0017] 1 manufactures a seamless capsule 50 using the manufacturing method according to this embodiment. The manufacturing apparatus includes a nozzle 1, a content liquid tank 2, a content liquid supply pipe 2a, a coating liquid tank 3, a coating liquid supply pipe 3a, a cooling liquid reservoir 6, a cooling liquid tank 7, a cooling liquid supply pipe 8, a cooling device 9, a forming pipe 10, pumps 11 to 13, a screen 14, and a dryer 15.

[0018] The nozzle 1 is connected to the content liquid tank 2 via a content liquid supply pipe 2a, and is connected to the coating liquid tank 3 via a coating liquid supply pipe 3a. The content liquid tank 2 stores the content liquid 41. The content liquid 41 is pressure-fed from the content liquid tank 2 to the nozzle 1 via the content liquid supply pipe 2a by the pump 11. The content liquid 41 is also called a filling liquid, and when filled inside the seamless capsule 50, it becomes a content 51 described below. The coating liquid tank 3 stores the coating liquid 42. The coating liquid 42 is pressure-fed from the coating liquid tank 3 to the nozzle 1 via the coating liquid supply pipe 3a by the pump 12.

[0019] 1 and 2, the coolant reservoir 6 is connected to the coolant tank 7 via a coolant supply pipe 8. The coolant tank 7 stores a coolant 49. The coolant 49 is also called a solidified liquid or a solidified liquid. The coolant 49 is pumped from the coolant tank 7 to the coolant reservoir 6 via the coolant supply pipe 8 by the pump 13, and is cooled by a cooling device 9 during the process. The coolant 49 is received in the internal space of the coolant reservoir 6. The coolant reservoir 6 has a bottom wall 6a, an upper wall 6b, and a peripheral wall 6c, and the inner surfaces of these walls define the internal space. The bottom wall 6a and the upper wall 6b are approximately horizontal and are separated from each other in the vertical direction. The peripheral wall 6c is erected upward from the peripheral portion of the bottom wall 6a. The peripheral portion of the upper wall 6b is located above the peripheral wall 6c, and a spacer 6e is provided between the peripheral portion of the upper wall 6b and the upper end of the peripheral wall 6c. The spacer 6e is a member that determines the distance between the upper wall 6b and the peripheral wall 6c, and is replaceable. The coolant reservoir 6 is provided with a coolant inlet port 6d that allows the coolant 49 to flow into the internal space. The downstream end of the coolant supply pipe 8 is connected to the coolant inlet port 6d. The upper wall 6b is configured to be able to open the space above the liquid level 49L of the coolant 49 to the atmosphere. The coolant 49 is returned from the coolant reservoir 6 to the coolant tank 7 through the forming pipe 10. The forming pipe 10 is open at both ends and forms a flow path through which the coolant 49 flows. In the example of FIG. 1 and FIG. 2, the coolant 49 flows through the flow path of the forming pipe 10 by the head pressure. In a modification of this embodiment, the discharge force of the pump 13 can also be used to make the coolant 49 flow through the flow path of the forming pipe 10. In such a modification, a coolant reservoir 6 with a sealed internal space may be used.

[0020] The spacer 6e only needs to separate the upper wall 6b and the peripheral wall 6c, and the material and shape of the spacer 6e can be selected as desired depending on the purpose of manufacturing. Examples of the material of the spacer 6e include resin, metal, natural rubber, and synthetic rubber. The shape of the spacer 6e, when viewed from above and below, can be a shape that covers the entire part of the periphery of the upper wall 6b that faces the peripheral wall 6c, or a shape in which a part of the part that faces the peripheral wall 6c is interrupted.

[0021] The upper end 10a (one end, upstream end) of the forming tube 10 opens in the internal space of the cooling liquid reservoir 6. The central axis of the forming tube 10 is oriented vertically at the upper end of the forming tube 10, and the upper end 10a of the forming tube 10 is oriented horizontally. The cross section of the forming tube 10 is typically circular. The forming tube 10 extends downward from the upper end 10a, penetrates the bottom wall 6a of the cooling liquid reservoir 6, turns upward once, turns downward again, and terminates. In addition, the distance H between the upper end 10a and the inner surface of the bottom wall 6a can be changed, and a seal 6f is provided between the forming tube 10 and the bottom wall 6a to prevent the cooling liquid 49 from flowing out. The opening of the other end (downstream end) of the forming tube 10 is located above the cooling liquid tank 7 and faces downward. The cooling liquid 49 is discharged from the opening of the other end of the forming tube 10 and received in the cooling liquid tank 7.

[0022] The material of the sealing 6f can be selected arbitrarily depending on the purpose of manufacture as long as it can prevent the outflow of the cooling liquid 49. Examples of the material of the sealing 6f include resin, metal, natural rubber, and synthetic rubber.

[0023] Referring to FIG. 2, the nozzle 1 is cylindrical as a whole. The central axis A of the nozzle 1 is oriented vertically. A plate-shaped flange portion 1b protruding in the radial direction is provided at an axially intermediate portion of the nozzle 1. The flange portion 1b is supported on the outer surface (upper surface) of the upper wall 6b of the coolant reservoir 6. The nozzle 1 protrudes upward from the upper wall 6b at a portion closer to the axial base end than the flange portion 1b. At this base end portion, a content liquid inflow port 1c for allowing the content liquid 41 to flow into the nozzle 1 and a coating liquid inflow port 1d for allowing the coating liquid 42 to flow into the nozzle 1 are provided. The nozzle 1 passes through the upper wall 6b at a portion closer to the axial tip end than the flange portion 1b and enters the internal space of the coolant reservoir 6 from above.

[0024] The flange portion 1b is a member fixed to the nozzle 1 and is replaceable. A fixing tool such as a screw can be used to fix the flange portion 1b to the nozzle 1. Since the flange portion 1b is supported on the upper surface of the upper wall 6b as described above, the position of the nozzle 1 can be adjusted by the thickness of the flange portion 1b in the vertical direction. The material of the flange portion 1b can be selected arbitrarily depending on the purpose of manufacture. Examples of the material of the flange portion 1b include resin, metal, natural rubber, and synthetic rubber. In addition, the shape of the flange portion 1b is not particularly limited as long as the nozzle 1 can be installed on the upper wall 6b via the flange portion 1b, but may be, for example, a circle, an ellipse, or a polygon in a plan view in the vertical direction.

[0025] In the internal space of the coolant reservoir 6, a liquid level 49L of the coolant 49 is located between the upper end 10a of the forming tube 10 and the inner surface (lower surface) of the upper wall 6b. The position of the liquid level 49L can be controlled in this manner by adjusting the flow rate of the pump 13. The tip 1a of the nozzle 1 is located below the liquid level 49L. In other words, the tip of the nozzle 1 is immersed in the coolant 49 received in the coolant reservoir 6.

[0026] 2 and 3, the nozzle 1 has a central nozzle 21 and an outermost nozzle 22. Both the central nozzle 21 and the outermost nozzle 22 extend in the axial direction inside the nozzle 1. The central nozzle 21 has a circular cross section centered on the central axis A. The outermost nozzle 22 is concentric with the central nozzle 21, surrounds the central nozzle 21, and has an annular cross section centered on the central axis A. One end (upper end, upstream end) of the central nozzle 21 is connected to the content liquid inlet port 1c. One end (upper end, upstream end) of the outermost nozzle 22 is connected to the coating liquid inlet port 1d. The other end (lower end, downstream end) of the central nozzle 21 and the other end (lower end, downstream end) of the outermost nozzle 22 open at the tip 1a of the nozzle 1. The tip 1a of the nozzle 1 forms a flat tip surface perpendicular to the central axis A. The central nozzle 21 and the outermost nozzle 22 open at this tip surface.

[0027] The nozzle 1 has an inclined portion 25 that inclines from the middle of the nozzle 1 toward the tip 1a toward the inside of the nozzle 1. The inclined portion 25 is provided at a location closer to the tip side in the axial direction than the flange portion 1b.

[0028] As can be seen from FIG. 2 and FIG. 4, in a vertical cross section of the nozzle 1 passing through the central axis A of the nozzle 1, the outer surface 25a of the inclined portion 25 is represented as a pair of straight lines 25b. The pair of straight lines 25b connect the upper end 25c and the lower end 25d of the outer surface 25a of the inclined portion 25. The pair of straight lines 25b are inclined so as to approach each other toward the tip 1a. The pair of straight lines 25b are line-symmetrical with respect to the central axis A. The lower ends of the pair of straight lines 25b are each connected to a tip surface represented as a horizontal line perpendicular to the central axis A. As can be seen from FIG. 3, in this embodiment, in a horizontal cross section of the nozzle 1 passing through the central axis A of the nozzle 1, the outer surface of the inclined portion 25 is circular.

[0029] Thus, in this embodiment, the inclined portion 25 has a truncated cone shape. The pair of straight lines 25b are the generating lines of the truncated cone.

[0030] 4, a virtual surface 26 is assumed to be formed by extending the outer surface 25a of the inclined portion 25 downward from the tip 1a of the nozzle 1. The virtual surface 26 is expressed as a downward extension of a pair of straight lines 25b in a vertical cross section passing through the central axis A of the nozzle 1. The virtual surface 26 becomes a point on the central axis A. That is, the downward extensions of the pair of straight lines 25b intersect on the central axis A. This intersection is the apex 27 of the space surrounded by the virtual surface 26. In this embodiment in which the cross section of the outer surface 25a of the inclined portion 25 is circular, this virtual space is conical with the tip surface of the nozzle 1 where the central nozzle 21 and the outermost nozzle 22 open as its base.

[0031] The distance Z between the apex 27 and the upper end 10a of the forming tube 10 is within the range of -10mm≦Z≦6mm. The distance Z is the distance between the apex 27 and the upper end 10a in the vertical direction, and the vertical direction corresponds to the axial direction of the nozzle 1, the normal direction of the tip surface of the nozzle 1, the axial direction of the forming tube 10, and the perpendicular direction of the opening of the upper end 10a of the forming tube 10. When the apex 27 coincides with the upper end 10a of the forming tube 10, Z=0. When Z<0, the apex 27 is located below the upper end 10a of the forming tube 10, that is, within the flow path of the forming tube 10. When Z>0, the apex 27 is located above the upper end 10a of the forming tube 10, that is, outside the forming tube 10. Note that FIG. 4 illustrates the case of Z<0, and more specifically, illustrates the case where the tip 1a of the nozzle 1 itself is located above the upper end 10a of the forming tube 10 even though Z<0. However, this is just one example.

[0032] In setting the distance Z between the apex 27 and the upper end 10a of the forming tube 10, the thickness of the spacer 6e, the thickness of the flange portion 1b, and the distance H between the upper end 10a and the inner surface of the bottom wall 6a can be changed in this embodiment, but changing these three is not essential. That is, it is preferable to change at least one of the thickness of the spacer 6e, the thickness of the flange portion 1b, and the distance H between the upper end 10a and the inner surface of the bottom wall 6a.

[0033] In addition, in a vertical cross section of nozzle 1 passing through central axis A of nozzle 1, angle θ between a pair of straight lines 25b connecting upper end 25c and lower end 25d of outer surface 25a of inclined portion 25 is within the range of 20° to 70°.

[0034] 1 and 2, the method for manufacturing the seamless capsule 50 by such a manufacturing apparatus includes a forming step of dropping liquid droplets from the tip 1a of the nozzle 1 into the liquid coolant 49 in the flow path of the forming tube 10, and forming a seamless wet capsule 50w from the liquid droplets. In this forming step, the tip 1a of the nozzle 1 is located below the liquid level 49L of the liquid coolant 49. That is, the so-called dripping method is applied to the manufacturing apparatus and method according to this embodiment.

[0035] The droplets dropped from the nozzle 1 include the content liquid 41 supplied from the content liquid tank 2 to the nozzle 1 and discharged from the central nozzle 21, and the coating liquid 42 supplied from the coating liquid tank 3 to the nozzle 1 and discharged from the outermost nozzle 22. The content liquid 41 is discharged downward from the center of the tip face. The coating liquid 42 is discharged downward from the peripheral part of the tip face, covering the content liquid 41 from the outer periphery. In this way, the nozzle 1 discharges a composite jet 59 containing the content liquid 41 and the coating liquid 42 downward from its tip face into the cooling liquid 49. The composite jet 59 extends downward from the tip face in the cooling liquid 49. The composite jet 59 breaks into droplets from its lower end due to surface tension. When the droplets become grains of a predetermined size and the coating liquid 42 covers the entire content liquid 41, the coating liquid 42 solidifies. In this way, a seamless capsule 50 is produced.

[0036] The seamless capsule 50 has a spherical shape as a whole, and includes a content 51 and a shell layer 52 that encapsulates the content 51. The shell layer 52 is formed by solidification of the shell liquid 42, and has no seams. The content 51 is composed of the content liquid 41, and the state of the content 51 may be liquid, semi-solid such as gel, or solid.

[0037] The composite jet 59 is ejected into the flow path of the forming tube 10, and seamless capsules 50 are formed in the flow path of the forming tube 10. The formed seamless capsules 50 ride on the flow of the cooling liquid 49 in the forming tube 10 and are transported along the forming tube 10. The upper opening of the cooling liquid tank 7 is covered with a screen 14. The screen 14 allows the cooling liquid 49, which is among the material discharged from the opening at the other end of the forming tube 10, to pass through, while blocking the seamless capsules 50 from flowing into the cooling liquid tank 7. The seamless capsules 50 blocked by the screen 14 are collected as wet capsules 50w.

[0038] The collected wet capsule 50w may be a final product. The manufacturing device may have a dryer 15 for drying the wet capsule 50w. A drying step of drying the wet capsule 50w with the dryer 15 can be performed to obtain a dry capsule 50d. In this way, the wet capsule 50w may be an intermediate product of the dry capsule 50d, and the dry capsule 50d may be a final product.

[0039] The content liquid 41 is not particularly limited, and examples thereof include a lipophilic or hydrophilic liquid, a suspension of such a liquid and an insoluble powder therein, or a mixture of such liquids. The content liquid 41 may be appropriately mixed with compounding agents such as an excipient, a stabilizer, a surfactant, an adjuvant, or a foaming agent.

[0040] The coating liquid 42 contains a natural polymer and water. The natural polymer is a component that solidifies the coating liquid 42, and is often water-soluble. The natural polymer is, for example, at least one selected from the group consisting of gelatin, casein, zein, pectin or a derivative thereof, alginic acid or a salt thereof, agar, gellan gum, carrageenan, furcellaran, chitosan, curdlan, starch, modified starch, pullulan, and mannan. The natural polymer is not limited to the above, and any component can be used as long as it is capable of forming the coating layer 52.

[0041] The coating liquid 42 may further contain a plasticizer. The plasticizer is a component that imparts flexibility to the coating layer 52. The plasticizer can maintain sufficient flexibility and make the dried product of the coating layer 52 less likely to crack, particularly in the dried capsule 50d. Examples of the plasticizer include glycerin and sorbitol. The plasticizer is not limited to the above and can be any component that can impart flexibility to the coating layer 52.

[0042] The coating liquid 42 may further contain additives such as colorants, flavoring ingredients, preservatives, or fragrances depending on the purpose of the seamless capsule 50.

[0043] The viscosity of the shell liquid 42 is preferably 30 to 350 mPa·s, more preferably 50 to 300 mPa·s, and even more preferably 50 to 250 mPa·s at 60° C. When the viscosity of the shell liquid 42 is within the above range, the seamless capsules can be well prepared by the dropping method.

[0044] The cooling liquid 49 is typically at or below 20° C., and preferably at 1 to 18° C. The temperature of each liquid discharged from the nozzle 1 is not particularly limited, and is typically 15 to 70° C., and preferably 20 to 65° C.

[0045] The coolant 49 may include oil-based components such as medium chain triglycerides (MCT), vegetable oils (such as palm oil, sunflower oil, safflower oil, sesame oil, rapeseed oil, grape seed oil, and mixtures thereof), liquid paraffin, and mixtures thereof.

[0046] 2, the cooling liquid 49 flows from the liquid surface 49L in the cooling liquid reservoir 6 toward the opening of the upper end 10a of the forming tube 10. The inclined portion 25 of the nozzle 1 is disposed near this opening, and the cooling liquid 49 flows along the outer surface of the inclined portion 25 toward the opening of the forming tube 10. The flow along the outer surface moves radially inward of the nozzle 1 as it moves from the tip 1a of the nozzle 1 toward the inside of the forming tube 10 further downward. In other words, the cooling liquid 49 flows along the imaginary surface 26 formed by extending the outer surface of the inclined portion 25 downward, and moves toward the apex 27 of the space surrounded by the imaginary surface 26. A vortex of the cooling liquid 49 may be formed near this apex 27.

[0047] If the apex 27 is too far above the upper end 10a, there is a risk that disturbances in the flow of the cooling liquid 49 may occur near the opening of the forming tube 10 in addition to the apex 27. The composite jet 59 is affected by this disturbance, which hinders stable formation of the coating layer 52, and the particle size variation of the wet capsules 50w is likely to increase. If the apex 27 enters too far into the forming tube 10, the cooling liquid 49 passes through a narrow space surrounded by the forming tube 10 and the nozzle 1, making it difficult to control the flow rate of the cooling liquid 49. Therefore, when the cooling liquid 49 flows through the flow path of the forming tube 10, the shear force generated by the flow of the cooling liquid 49 becomes unstable, and the particle size variation of the wet capsules 50w is likely to increase. In contrast, in this embodiment, the distance Z between the apex 27 and the upper end 10a of the forming tube 10 is within the range of -10 mm≦Z≦6 mm. The flow of the cooling liquid 49 flowing into the forming tube 10 can be easily controlled by the inclined portion 25, the shell layer 52 is stably formed, and the variation in particle size of the wet capsules 50w can be reduced. Therefore, high-quality seamless capsules 50 with reduced shell cracks can be manufactured.

[0048] When the angle θ between a pair of straight lines 25b connecting the upper end 25c and the lower end 25d of the outer surface 25a of the inclined portion 25 is small, the position of the apex 27 is away from the tip surface downward. Then, the flow of the cooling liquid 49 is easily disturbed near the lower end of the composite jet 59, and the particle size variation of the seamless capsules 50 produced is likely to increase. On the other hand, when the angle θ is large, the position of the apex 27 is closer to the tip surface. Then, the composite jet 59 is easily affected by the vortex of the cooling liquid 49 immediately after being discharged. The shape of the composite jet 59 becomes unstable, and the particle size of the seamless capsules 50 produced is not stable. In this embodiment, the angle θ is within a range of 20° to 70°. This stabilizes the particle size of the seamless capsules 50, and the particle size variation can be suppressed. The lower limit of the angle θ is preferably 30° or more. Also, the upper limit of the angle θ is preferably 60° or less.

[0049] As a result, the coefficient of variation of the particle size of the wet capsule 50w is 0.1 or less. When the dry capsule 50d is obtained from such a wet capsule 50w, the coefficient of variation of the particle size of the dry capsule 50d is 0.1 or less. In this way, it becomes possible to stably manufacture high-quality seamless capsules 50. The coefficient of variation is a dimensionless statistical value obtained by dividing the standard deviation of a certain index value of a plurality of samples by its average value.

[0050] Although the embodiment has been described above, the above configuration is merely an example and can be modified as appropriate within the scope of the present invention.

[0051] FIG. 5 shows a first modified example. As shown in FIG. 5, a seamless capsule 50 having a three-layer structure may be produced. In this case, the nozzle 1 further includes an intermediate nozzle 23 formed between the central nozzle 21 and the outermost nozzle 22 in the radial direction. The intermediate nozzle 23 is concentric with the central nozzle 21 and the outermost nozzle 22, has an annular cross section, and extends in the axial direction. The upper end of the intermediate nozzle 23 is connected to an intermediate liquid inflow port 1e into which the intermediate liquid 43 supplied from an intermediate liquid tank (not shown) flows. The lower end of the intermediate nozzle 23 opens at the tip surface. The composite jet 59 contains not only the content liquid 41 and the coating liquid 42, but also the intermediate liquid 43 interposed therebetween. The seamless capsule 50 containing the content 51, the intermediate layer 53, and the coating layer 52 is produced in the forming tube 10 by dropletization of the composite jet 59.

[0052] FIG. 6A shows a second modified example, and FIG. 6B shows a third modified example. The horizontal cross section of the outer surface of the inclined portion 25 of the nozzle 1 is not limited to a circular shape. As shown in FIG. 6A, the horizontal cross section may be an ellipse. As shown in FIG. 6B, the horizontal cross section may be a polygon. In FIG. 6B, the polygon is a square just as an example, but the polygon may be a quadrangle other than a square. In addition, the number of corners or sides of the polygon is not limited to four.

[0053] 7 shows a fourth modified example. The nozzle 1 may be composed of a cylindrical nozzle body 31 and a cap 32 that covers the tip of the nozzle body 31 (see the dashed line). The cap 32 forms an inclined portion 25 and a tip 1a, and is detachably attached to the nozzle body 31. A plurality of caps 32 with different angles θ may be prepared for one nozzle body 31, and one cap 32 selected from the plurality of caps 32 may be attached to the nozzle body 31. This makes it possible to select a cap 32 with appropriate specifications depending on the content liquid and coating liquid.

[0054] FIG. 8A shows a fifth modified example, and FIG. 8B shows a sixth modified example. In the vertical cross section of the nozzle 1 passing through the central axis A of the nozzle 1, in the examples shown in FIG. 2 and FIG. 7, the outline of the outer surface 25b of the inclined portion 25 is a single straight line, but the outline is not limited to a single straight line. In the fifth modified example of FIG. 8A, the outline of the outer surface 25b may be a wavy line or a line similar thereto. When the outline of the outer surface 25b is a wavy line or the like, the intersection point where the downward extensions of the pair of straight lines 25b intersect on the central axis A may not coincide with the vertex 27 of the space surrounded by the imaginary surface 26.

[0055] 8B, the outline of outer surface 25b may be a bent line or a curved line. When outer surface 25b has a curved line or the like, the portion of inclined portion 25 that is largely involved in controlling the flow of the coolant is defined as the main body of inclined portion 25, the straight line connecting the upper end and the lower end of the outer surface of the main body is defined as straight line 25b, and the imaginary surface formed by extending the outer surface of inclined portion 25 downward is defined as imaginary surface 26.

[0056] Although detailed illustration is omitted, the second or third modified example may be applied to the first modified example, and the fourth modified example may be applied to the first modified example. The second or third modified example and the fourth modified example may be applied simultaneously to the above embodiment or the first modified example. The second or third modified example and the fifth or sixth modified example may be applied simultaneously to the above embodiment or the first modified example.

[0057] The present invention will be described in more detail below with reference to Examples and Comparative Examples (Experiment Classifications 1 to 28), but the present invention is not limited thereto. In the following description, "parts" and "%" are by mass unless otherwise specified.

[0058] (Experiment Classification 1) A content solution of 80 parts of MCT (Kao) was prepared. A coating solution of 16 parts of gelatin (PB Leiner Argentina), 4 parts of sorbitol (Roquette China Co. Ltd.), and 300 parts of purified water was prepared. The bloom value of the gelatin was 240, and the viscosity of the coating solution was 50 mPa·s at 60°C. A cooling solution of 100% MCT (Kao) was prepared. The preparation of these solutions was the same for the other experimental categories 2 to 28.

[0059] Using a seamless capsule manufacturing machine (manufactured by Morishita Jintan) having a structure as exemplified in FIG. 1, the content liquid was discharged from the center nozzle and the shell liquid was discharged from the outermost nozzle into the cooling liquid at the same time to produce a seamless capsule with a two-layer structure. Next, the produced seamless capsule was aerated and dried to evaporate the water contained in the shell layer, thereby obtaining a dry capsule. The mass of the shell layer was 30% of the total mass of the dry capsule. The manufacturing method of the dry capsule and the mass ratio of the shell layer described here are the same for the other experimental classes 2 to 28.

[0060] As shown in Table 1, a first nozzle (1-60) with an inclined portion was used as a nozzle having a central nozzle and an outermost nozzle. The first nozzle (1-60) was formed to a size expected to produce a dried capsule with a particle size of about 1 mm, and the angle between the outer line of the inclined portion (hereinafter simply referred to as "angle θ") was 60°. In order to obtain the required particle size, the values ​​obtained by dividing the flow rate of the content liquid, the flow rate of the coating liquid, and the flow rate of the cooling liquid by the flow path cross-sectional area of ​​the forming tube were adjusted as shown in Table 1.

[0061] The position of the nozzle relative to the forming tube was adjusted so that the distance between the apex of the space enclosed by a virtual plane formed by extending the outer surface of the inclined portion and the upper end of the forming tube (hereinafter simply referred to as "distance Z") was -10.1 mm. The tip of the nozzle was positioned below the liquid surface of the cooling liquid, and the composite jet was discharged into the cooling liquid.

[0062] (Experimental Classifications 2-4) As shown in Table 1, in the experimental groups 2 to 4, seamless capsules were produced using the first nozzle in the same manner as in the experimental group 1, except that the distance Z was changed from that in the experimental group 1.

[0063] In experimental category 2, the distance Z was adjusted to -1.8 mm. In experimental category 3, the distance Z was adjusted to 3.2 mm. In experimental category 4, the distance Z was adjusted to 13.2 mm.

[0064] (Experimental Classification 5~8) As shown in Table 1, in the experimental groups 5 to 8, a second nozzle (1-30) having an inclined portion was used as a nozzle having a central nozzle and an outermost nozzle. The second nozzle (1-30) was formed to an expected size such that the particle size of the dried capsules to be produced was about 1 mm in the same manner as the first nozzle (1-60), while the angle θ was 30°. The flow rates of the content liquid, the coating liquid, and the cooling liquid, divided by the flow path cross-sectional area of ​​the forming tube, were adjusted as shown in Table 1.

[0065] In experimental category 5, distance Z was adjusted to -14.9 mm. In experimental category 6, distance Z was adjusted to -4.5 mm. In experimental category 7, distance Z was adjusted to 0.5 mm. In experimental category 8, distance Z was adjusted to 10.6 mm.

[0066] (Experimental Classification 9~12) As shown in Table 2, in the experimental groups 9 to 12, a third nozzle (5-60) having an inclined portion was used as a nozzle having a central nozzle and an outermost nozzle. The third nozzle (5-60) was formed to a size expected to produce a dried capsule with a particle size of about 5 mm, and the angle θ was 60°. The flow rates of the content liquid, the coating liquid, and the cooling liquid divided by the flow path cross-sectional area of ​​the forming tube were adjusted as shown in Table 2.

[0067] In experimental category 9, distance Z was adjusted to -19 mm. In experimental category 10, distance Z was adjusted to -5.7 mm. In experimental category 11, distance Z was adjusted to -0.7 mm. In experimental category 12, distance Z was adjusted to 9.3 mm.

[0068] (Experimental Classification 13~16) As shown in Table 2, in the experimental groups 13 to 16, a fourth nozzle (5-40) having an inclined portion was used as a nozzle having a central nozzle and an outermost nozzle. The fourth nozzle (5-40) was formed to a size expected to produce a particle size of about 5 mm in the same manner as the third nozzle (5-60), while the angle θ was 40°. The flow rates of the content liquid, the coating liquid, and the cooling liquid divided by the flow path cross-sectional area of ​​the forming tube were adjusted as shown in Table 2.

[0069] In experimental category 13, distance Z was adjusted to -30 mm. In experimental category 14, distance Z was adjusted to -5.8 mm. In experimental category 15, distance Z was adjusted to -0.8 mm. In experimental category 16, distance Z was adjusted to 9.2 mm.

[0070] (Experimental Classification 17~20) As shown in Table 2, in the experimental groups 17 to 20, a fifth nozzle (5-30) having an inclined portion was used as a nozzle having a central nozzle and an outermost nozzle. The fifth nozzle (5-30) was formed to a size expected to produce a dried capsule having a particle size of about 5 mm in the same manner as the third nozzle (5-60), while the angle θ was 30°. The flow rates of the content liquid, the coating liquid, and the cooling liquid divided by the flow path cross-sectional area of ​​the forming tube were adjusted as shown in Table 2.

[0071] In experimental category 17, distance Z was adjusted to -36.2 mm. In experimental category 18, distance Z was adjusted to -6 mm. In experimental category 19, distance Z was adjusted to -1 mm. In experimental category 20, distance Z was adjusted to 9 mm.

[0072] (Experimental Classification 21~24) As shown in Table 3, in the experimental groups 21 to 24, a sixth nozzle (8-60) having an inclined portion was used as a nozzle having a central nozzle and an outermost nozzle. The sixth nozzle (8-60) was formed to a size expected to produce a dried capsule with a particle size of about 8 mm, and the angle θ was 60°. The flow rates of the content liquid, the coating liquid, and the cooling liquid divided by the flow path cross-sectional area of ​​the forming tube were adjusted as shown in Table 3.

[0073] In experimental category 21, distance Z was adjusted to -26 mm. In experimental category 22, distance Z was adjusted to -9.5 mm. In experimental category 23, distance Z was adjusted to -4.5 mm. In experimental category 24, distance Z was adjusted to 6.1 mm.

[0074] (Experimental Classification 25~28) As shown in Table 3, in the experimental groups 25 to 28, a seventh nozzle (8-30) having an inclined portion was used as a nozzle having a central nozzle and an outermost nozzle. The seventh nozzle (8-30) was formed to a size expected to produce a dried capsule having a particle size of about 8 mm in the same manner as the sixth nozzle (8-60), while the angle θ was 30°. The flow rates of the content liquid, the coating liquid, and the cooling liquid divided by the flow path cross-sectional area of ​​the forming tube were adjusted as shown in Table 3.

[0075] In experimental category 25, distance Z was adjusted to -51 mm. In experimental category 26, distance Z was adjusted to -9.7 mm. In experimental category 27, distance Z was adjusted to -4.7 mm. In experimental category 28, distance Z was adjusted to 5.3 mm.

[0076] (Examples / Comparative Examples) Experimental classes 2, 3, 6, 7, 10, 11, 14, 15, 18, 19, 22, 23, 26, and 27 are examples in which the distance Z is within the range of -10.0 mm≦Z≦6.0 mm. The other experimental classes 1, 4, 5, 8, 9, 12, 13, 16, 17, 20, 21, 24, 25, and 28 are comparative examples in which the distance Z is outside the range.

[0077] (evaluation) Using the seamless capsules obtained in each experimental classification, the following evaluations were carried out.

[0078] <Average particle size and coefficient of variation> In each of the experimental categories 1 to 28, 20 capsules were randomly selected from the obtained wet capsules, and the particle size (outer diameter) of each wet capsule was measured with a vernier caliper. Based on the particle size data of the 20 capsules, the average particle size and standard deviation of the wet capsules were calculated. Furthermore, the obtained standard deviation was divided by the average particle size to calculate the coefficient of variation of the wet capsule particle size. The average particle size, standard deviation, and coefficient of variation of the dry capsules were calculated in the same manner for the dry capsules.

[0079] In the examples, the average particle size of the dry capsules was equal to or close to the expected particle size. In addition, in the examples, the coefficient of variation was 0.1 or less for both the wet capsules and the dry capsules, and the variation in particle size was suppressed.

[0080] <Wet capsule yield rate> In each of the experimental groups 1 to 28, 100 objects (approximately the same size as the wet capsule) formed from the composite jet discharged from the nozzle and flowing down the forming tube were visually confirmed, and the number of debris whose coating was broken and not spherical was counted. The number of objects and the number of debris were then applied to the following formula (1) to calculate the yield rate. Yield rate (%) = 1 - (number of debris) / (number of objects) × 100 Equation (1)

[0081] In the examples, a minimum yield rate of 97% was achieved, whereas in the comparative examples, the maximum yield rate was 82%, which is the experimental class 24, and it was not possible to achieve a high yield rate like that of the examples.

[0082] [Table 1]

[0083] [Table 2]

[0084] [Table 3]

[0085] The present disclosure may include the following aspects. (Aspect 1) A method for producing a seamless capsule, comprising the steps of: A forming step includes dropping droplets from a tip of a nozzle into a cooling liquid in a flow passage of a forming tube, and forming a seamless wet capsule from the droplets; The nozzle includes an inclined portion that is inclined toward the inside of the nozzle from the middle toward the tip, The distance Z between the apex of the space surrounded by a virtual surface formed by extending the outer surface of the inclined portion downward from the tip and the upper end of the forming tube is within the range of -10 mm ≦ Z ≦ 6 mm, and when Z < 0, the apex is located below the upper end of the forming tube, and when Z > 0, the apex is located above the upper end of the forming tube. A method for producing seamless capsules. (Aspect 2) In a vertical cross section of the nozzle passing through the central axis of the nozzle, an angle between a pair of straight lines connecting the upper end and the lower end of the outer surface of the inclined portion is within a range of 20° to 70°. A method for producing the seamless capsule according to embodiment 1. (Aspect 3) In a horizontal cross section of the nozzle perpendicular to the central axis of the nozzle, the damage surface of the inclined portion is circular, elliptical or polygonal. A method for producing the seamless capsule according to aspect 1 or 2. (Aspect 4) The coefficient of variation of the particle size of the wet capsule is 0.1 or less; A method for producing the seamless capsule according to any one of aspects 1 to 3. (Aspect 5) the forming step includes a step of positioning a tip of the nozzle below a liquid level of the cooling liquid; A method for producing the seamless capsule according to any one of aspects 1 to 4. (Aspect 6) The method further comprises a drying step of drying the wet capsule to obtain a dry capsule. A method for producing the seamless capsule according to any one of aspects 1 to 5. (Aspect 7) The coefficient of variation of the particle size of the dry capsule is 0.1 or less. A method for producing the seamless capsule according to embodiment 6. [Explanation of symbols]

[0086] 1 nozzle 1a Tip 1b Flange part 1c Content inlet port 1d Membrane fluid inlet port 1e Intermediate liquid inlet port 2 Contents tank 2a Contents liquid supply pipe 3. Coating liquid tank 3a Coating liquid supply pipe 6 Coolant Reservoir 6a Bottom wall 6b Upper wall 6c Peripheral wall 6d Coolant inlet port 6e Spacer 6f Ceiling 7 Coolant Tank 8 Coolant supply pipe 9 Cooling device 10 Formation tube 10a top end 11~13 Pump 14 Screens 15 Dryer 21 Center nozzle 22 Outermost nozzle 23 Intermediate nozzle 25 Slope 25a outer surface 25b straight line 25c top end 25d bottom end 26 Virtual Surface 27 Vertex 31 Nozzle body 32 Cap 41 Content liquid 42 Film Fluid 43 Intermediate Liquid 49 Coolant 49L liquid level 50 seamless capsules 50w Wet Capsule 50d dry capsule 51 Contents 52 Coating layer 53 Middle Class 59 Composite Jet A center axis Z distance H distance θ angle

Claims

1. A method for producing a seamless capsule, comprising the steps of: A forming step includes dropping droplets from a tip of a nozzle into a cooling liquid in a flow passage of a forming tube, and forming a seamless wet capsule from the droplets; The nozzle includes an inclined portion that is inclined toward the inside of the nozzle from the middle toward the tip, The distance Z between the apex of the space surrounded by a virtual surface formed by extending the outer surface of the inclined portion downward from the tip and the upper end of the forming tube is within the range of -10 mm ≦ Z ≦ 6 mm, and when Z < 0, the apex is located below the upper end of the forming tube, and when Z > 0, the apex is located above the upper end of the forming tube. A method for producing seamless capsules.

2. In a vertical cross section of the nozzle passing through the central axis of the nozzle, an angle between a pair of straight lines connecting the upper end and the lower end of the outer surface of the inclined portion is within a range of 20° to 70°. The method for producing the seamless capsule according to claim 1.

3. In a horizontal cross section of the nozzle perpendicular to the central axis of the nozzle, the outline of the inclined portion is a circle, an ellipse, or a polygon. The method for producing the seamless capsule according to claim 1.

4. The coefficient of variation of the particle size of the wet capsule is 0.1 or less. The method for producing the seamless capsule according to claim 1.

5. the forming step includes a step of positioning a tip of the nozzle below a liquid level of the cooling liquid; The method for producing the seamless capsule according to any one of claims 1 to 4.

6. The method further comprises a drying step of drying the wet capsule to obtain a dry capsule. The method for producing the seamless capsule according to any one of claims 1 to 4.

7. The coefficient of variation of the particle size of the dry capsule is 0.1 or less. The method for producing the seamless capsule according to claim 6.

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