JP7579665B2 - Vacuum spray freezing nozzle, freeze-drying device, and granulation method - Google Patents

Description

The present invention relates to a vacuum spray freezing nozzle, a freeze-drying device, and a granulation method.

In a spray-type freeze-drying device, the raw material liquid is sprayed downward from a vacuum spray freezing nozzle in a vacuum chamber. The sprayed raw material liquid contains raw materials for, for example, medicines, foods, cosmetics, etc., in a solvent or dispersant. The sprayed raw material liquid changes from a liquid column to particles below the vacuum spray freezing nozzle. The raw materials contained in the particles self-freeze as the solvent or dispersant absorbs the latent heat of vaporization (see, for example, Patent Document 1).

Patent No. 5230033

Technology that enables the smooth flow of raw material liquid in a vacuum spray freezing nozzle is highly desired in order to expand freeze-drying technology to various fields of use. A smooth flow of raw material liquid in a vacuum spray freezing nozzle means that the sprayed raw material liquid is less likely to scatter around the nozzle as it grows into a liquid column, or that the raw material liquid flows smoothly toward the nozzle at the start and end of the flow of raw material liquid toward the nozzle.

The vacuum spray freezing nozzle for solving the above problem is a vacuum spray freezing nozzle that sprays the raw material liquid into a vacuum space where the droplets of the raw material liquid self-freeze, and includes an inflow surface that separates the inflow port of the raw material liquid, an injection surface that separates the injection port of the raw material liquid, and an inner hole surface that separates an injection hole that communicates with the inflow port and the injection port. At least one of the inflow surface and the injection surface is a target surface, and the surface formed by the target surface and the inner hole surface includes a region where the contact angle decreases in the direction from the target surface toward the inner hole surface.

According to the above configuration, the liquid located at the boundary between the surface with the high contact angle and the surface with the low contact angle exerts a driving force to flow from the surface with the high contact angle to the surface with the low contact angle. According to the above nozzle for vacuum spray freezing, the driving force based on the difference in the contact angles is exerted in a direction from the target surface to the inner surface of the hole. As a result, when the target surface is the injection surface, the raw material liquid exerts a driving force to return the raw material liquid in a direction from the injection surface to the inner surface of the hole, thereby suppressing splashing toward the periphery of the injection port. When the target surface is the inflow surface, the raw material liquid exerts a driving force to push the raw material liquid in a direction from the inflow surface to the inner surface of the hole, thereby allowing the raw material liquid to flow smoothly into the inside of the injection hole at the start or end of injection of the raw material liquid. In other words, a smooth flow of the raw material liquid is realized.

In the above-mentioned vacuum spray freezing nozzle, the target surface may include the injection surface, and the surface formed by the inlet surface and the injection surface may have a region at the boundary between the injection surface and the inner surface of the hole where the contact angle decreases in the direction from the injection surface to the inner surface of the hole.

In conventional vacuum spray freezing nozzles, the raw material liquid located at the boundary between the injection surface and the inner surface of the hole is prone to scattering toward the periphery of the injection port before it grows into a liquid column. In this regard, with the above-mentioned vacuum spray freezing nozzle, a driving force is generated that pushes the raw material liquid located at the boundary between the injection surface and the inner surface of the hole back toward the inside of the injection port, so scattering toward the periphery of the injection port is more effectively suppressed.

In the above-mentioned vacuum spray freezing nozzle, the inner surface of the hole may have a region where a contact angle decreases in a direction from the target surface into the inner surface of the hole.
According to the above configuration, the raw material liquid located inside the injection hole flows smoothly along the inner surface of the hole, so that the raw material liquid can be smoothly pushed away inside the injection hole. Also, the raw material liquid is pushed toward the injection hole so that the flow of the raw material liquid when it leaves the injection hole is unlikely to be directed toward the outside of the injection hole. This makes it possible to prevent the raw material liquid from scattering around the injection hole.

In the above-mentioned vacuum spray freezing nozzle, the inner surface of the hole may be provided with a groove extending from the inlet to the nozzle so that the contact angle decreases in the direction from the target surface to the inner surface of the hole.

With the above configuration, the raw material liquid located inside the injection hole flows smoothly along the grooves on the inner surface of the hole, making it possible to smoothly push the raw material liquid into the injection hole. In addition, it is possible to smoothly form a liquid column by injecting the raw material liquid from the injection hole, and thus to suppress splashing toward the periphery of the injection hole.

In the above-mentioned vacuum spray freezing nozzle, the target surface and the hole inner surface may be provided with regions in which the contact angle decreases stepwise in a direction from the target surface to the hole inner surface.
According to the above configuration, since the contact angle decreases stepwise, it is possible to form a region having the above contact angle depending on the presence or absence of surface treatment, such as the presence or absence of a liquid-repellent surface layer, the presence or absence of a liquid-repellent surface structure, etc. This makes it possible to suppress an increase in the manufacturing load of the vacuum spray freezing nozzle, compared to manufacturing a vacuum spray freezing nozzle in which the degree of surface treatment is gradually changed.

In the above-mentioned vacuum spray freezing nozzle, the injection hole may be a circular hole having a constant diameter extending from the inlet toward the injection hole.
According to the above-mentioned vacuum spray freezing nozzle, in a configuration including an injection hole having a constant diameter extending from the inlet to the injection port, a smooth flow of the raw material liquid is realized.

In the above-mentioned vacuum spray freezing nozzle, the inner surface of the hole has a first frustum cylindrical surface with the inlet at its bottom, a second frustum cylindrical surface with the outlet at its bottom, and a cylindrical surface connecting the first frustum cylindrical surface and the second frustum cylindrical surface, and at least one of the first frustum cylindrical surface and the second frustum cylindrical surface is a target cylindrical surface, and the contact angle of the cylindrical surface may be smaller than the contact angle of the target cylindrical surface.

With the above-mentioned vacuum spray freezing nozzle, the inner surface of the hole has a change in contact angle that drops from the target surface toward the inside of the injection hole, so that not only the raw material liquid located at the boundary between the target surface and the inner surface of the hole, but also the raw material liquid located inside the injection hole can easily follow the driving force due to the difference in contact angle. As a result, the effectiveness of the effect of realizing a smooth flow of the raw material liquid is increased.

In the above-mentioned vacuum spray freezing nozzle, the target cylindrical surface may include the second truncated cylindrical surface, and the angle of the second truncated cylindrical surface with respect to the cylindrical surface may be greater than the difference between the contact angle of the cylindrical surface and the contact angle of the second truncated cylindrical surface.

With the above-mentioned vacuum spray freezing nozzle, the angle formed by the cylindrical surface and the second frustum cylindrical surface is greater than the difference between the contact angle of the cylindrical surface and the contact angle of the second frustum cylindrical surface. This means that in addition to guiding the raw material liquid by the contact angle, the angle formed by the cylindrical surface and the second frustum cylindrical surface also makes it possible to prevent the liquid from splashing around the nozzle.

The above-mentioned vacuum spray freezing nozzle may have a difference in surface roughness within the surface composed of the target surface and the inner surface of the hole such that the contact angle decreases in the direction from the target surface to the inner surface of the hole.

With the above-mentioned vacuum spray freezing nozzle, the area where the contact angle decreases in the direction from the target surface to the inner surface of the hole is realized by the difference in surface roughness, so the above-mentioned effect can be obtained by a general-purpose method such as applying surface treatment to the target material.

The freeze-drying apparatus for solving the above problem includes a vacuum chamber, a vacuum spray freezing nozzle that sprays raw material liquid into the vacuum chamber, and a supply unit that supplies the raw material liquid to the vacuum spray freezing nozzle, and the vacuum spray freezing nozzle is the above-mentioned vacuum spray freezing nozzle.

The granulation method for solving the above problem includes supplying a raw material liquid to a vacuum spray freezing nozzle, and spraying the raw material liquid from the vacuum spray freezing nozzle into a vacuum chamber to allow granules made of the raw material liquid to self-dry in the vacuum chamber, and the vacuum spray freezing nozzle is the above-mentioned vacuum spray freezing nozzle.

The vacuum spray freezing nozzle, freeze-drying device, and granulation method of the present invention enable smooth flow of the raw material liquid.

FIG. 1 is a diagram showing a configuration of a freeze-drying apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a cross-sectional structure of a vacuum spray freezing nozzle. FIG. 4 is a cross-sectional view showing another example of a cross-sectional structure of a vacuum spray freezing nozzle. FIG. 4 is a cross-sectional view showing another example of a cross-sectional structure of a vacuum spray freezing nozzle. FIG. 4 is a cross-sectional view showing another example of a cross-sectional structure of a vacuum spray freezing nozzle.

The freeze-drying device, the vacuum spray freezing nozzle, and the granulation method according to an embodiment will be described below with reference to Figures 1 and 4. In freeze-drying, the raw material liquid is sprayed from the vacuum spray freezing nozzle into a vacuum where the pressure is equal to or lower than the triple point in the phase diagram of water, and the latent heat of vaporization is removed from the liquid and solid contained in the raw material liquid, causing the raw material liquid to self-freeze.

As shown in FIG. 1, the freeze-drying apparatus 10 includes a supply unit 11, a vacuum chamber 21, a vacuum pump 31, and an injector 41. The supply unit 11 supplies the raw material liquid to the injector 41. The vacuum chamber 21 evacuates the inside of the vacuum chamber 21 by driving the vacuum pump 31. The injector 41 injects the raw material liquid supplied from the supply unit 11 into the inside of the vacuum chamber 21.

The raw material liquid supplied by the supply unit 11 includes raw materials such as pharmaceuticals, foods, and cosmetics, and is a liquid in which the raw material powder is dissolved in a solvent, a liquid body in which the raw material powder is dissolved in a solvent, or a liquid or liquid body in which the raw material powder is dispersed in a dispersion medium. A liquid body is a fluid with a higher viscosity than a liquid that is positioned between a solid and a liquid. Examples of raw material liquids are an albumin aqueous solution containing albumin, and a mannitol aqueous solution containing mannitol.

The water content of the aqueous solution is, for example, 70% by weight or more. A water content of 70% by weight or more in the aqueous solution is preferable from the viewpoint of easily removing the latent heat of vaporization from the water. For example, if the water content of the aqueous solution is 70% by weight or more, even if the surface layer of the raw material liquid sprayed from the injector 41 changes to a solid phase before reaching the tray 21T, the latent heat of vaporization can be removed through the surface layer that has changed from a liquid phase other than the surface layer to a solid phase.

The supply unit 11 may include a container in which the raw material liquid is stored, and an adjustment unit that adjusts the flow rate of the raw material liquid stored in the container. The adjustment unit included in the supply unit 11 may adjust the volumetric flow rate of the raw material liquid, or may adjust the mass flow rate of the raw material liquid. The adjustment unit included in the supply unit 11 may also supply an inert gas into the container, on the premise that the flow rate injected by the injector 41 is proportional to the pressure of the container, thereby adjusting the pressure difference between the internal pressure of the container and the internal pressure of the vacuum chamber 21. The internal pressure of the container is, for example, 0 MPa or more and 0.5 MPa or less.

The vacuum chamber 21 may have a cylindrical shape having a top surface and a bottom surface. The vacuum chamber 21 separates the vacuum space 21S, which is the internal space of the vacuum chamber. The pressure of the vacuum space 21S is a value below the triple point in the phase diagram of water. The pressure of the vacuum space 21S may be adjusted to any value between 0.1 Pa and 500 Pa by driving the vacuum pump 31. Note that it is preferable that the value between 0.1 Pa and 500 Pa is the water pressure in the vacuum space 21S, not the total pressure of the vacuum space 21S.

The injector 41 may be disposed on the top surface of the vacuum chamber 21, on the side surface of the vacuum chamber 21, or on the bottom surface of the vacuum chamber 21. The injector 41 is connected to the supply unit 11. The injector 41 includes a vacuum spray freezing nozzle 43. The vacuum spray freezing nozzle 43 injects the raw material liquid supplied from the supply unit 11 into the inside of the vacuum space 21S. The raw material liquid after injection does not become mist inside the vacuum space 21S, but generates a liquid column L1 described later, so that the injection of the raw material liquid can be said to be ejected as the raw material liquid. The vacuum chamber 21 may include a cold trap around the injector 41. The cold trap does not adsorb the raw material contained in the raw material liquid, but adsorbs and exhausts the water vapor introduced from the injector 41 under reduced pressure and evaporated.

The raw material liquid sprayed into the vacuum space 21S forms a liquid column L1 from the vacuum spray freezing nozzle 43. The length of the liquid column L1 is determined by the viscosity of the raw material liquid, the inner diameter of the injection hole 51 of the vacuum spray freezing nozzle 43, the pressure at which the raw material liquid is sprayed from the injection hole 51, the pressure of the vacuum space 21S, etc. When the raw material liquid is an aqueous mannitol solution, an example of the inner diameter of the injection hole 51 is 150 μm, an example of the pressure at which the raw material liquid is sprayed is 0.5 MPa, and an example of the pressure of the vacuum space 21S is 50 Pa. In this example, the length of the liquid column L1 is approximately 400 mm.

As time passes from the time of ejection, the liquid column L1 is transformed from an unstable column shape to a stable granular shape due to the action of the surface tension of the raw material liquid, and is finally broken into droplets L2, which are particles of the raw material liquid. The liquid components contained in the liquid column L1 and the droplets L2 evaporate in the vacuum space 21S by taking the latent heat of evaporation from the raw material, etc. The droplets L2 from which the latent heat of evaporation has been taken begin to self-freeze and turn into frozen particles L3. Here, the frozen particles L3 are particles in which at least the surface layer of the droplets L2 has changed from the liquid phase to the solid phase as a result of self-freezing. Note that immediately after the droplets L2 are transformed into the frozen particles L3, the surface layer of the frozen particles L3 may be in a two-phase state in which both the liquid phase and the solid phase are expressed. However, the amount of injection of the device is adjusted so that the formation of the solid phase progresses on the surface layer of the frozen particles L3 to the extent that the frozen particles L3 cannot be joined to each other just before they are deposited on the tray 21T. The solid phase (solidified portion) of the liquid components contained in the frozen particles L3 also evaporates by absorbing the latent heat of sublimation from the raw material. As a result, the raw material particles self-freeze, and frozen particles L3, which are the freeze-dried product of the raw material, are deposited on the tray 21T. When the phase changes from the liquid or solid phase to the gas phase, and heat is predominantly removed from the droplets L2, the entire surface layer of the raw material liquid particles changes to the solid phase. This freezing phenomenon is called self-freezing. The conditions for self-freezing to occur are that the size of the droplets L2 is sufficiently small, and that the water pressure of the environment in which the droplets L2 are placed is below the triple point.

The tray 21T may be transported from the vacuum chamber 21 to a drying chamber or the like connected to the vacuum chamber 21 by driving a transport mechanism or the like. The drying chamber is equipped with a heating device such as an infrared heater for drying the frozen particles L3, and dries the frozen particles L3 transported into the drying chamber.

2, the injector 41 includes an inlet pipe 42, a vacuum spray freezing nozzle 43, and a fixing ring 44. The inlet pipe 42 is fixed to the upper surface of the vacuum chamber 21. The inside 42S of the inlet pipe 42 receives the raw material liquid from the supply unit 11. The inlet pipe 42 introduces the raw material liquid received from the supply unit 11 into the vacuum spray freezing nozzle 43. The inlet pipe 42 may have a cylindrical shape or a polygonal tubular shape. The tip of the inlet pipe 42 may be equipped with a support ring 42A for supporting the vacuum spray freezing nozzle 43.

The vacuum spray freezing nozzle 43 sprays the raw material liquid introduced from the introduction pipe 42 into the vacuum space 21S. The vacuum spray freezing nozzle 43 has an injection hole 51 that penetrates between the inside of the introduction pipe 42 and the vacuum space 21S. The number of injection holes 51 may be one for each introduction pipe 42, or two or more for each introduction pipe 42. The vacuum spray freezing nozzle 43 may be plate-shaped or may be cylindrical with a bottom that has the injection hole 51.

The vacuum spray freezing nozzle 43 may be sandwiched between the support ring 42A and the fixed ring 44 so that the injection hole 51 opens toward the vacuum space 21S, or may be supported only by the introduction pipe 42, or may be configured integrally with the introduction pipe 42. When the vacuum spray freezing nozzle 43 is sandwiched between the support ring 42A and the fixed ring 44, the support ring 42A and the fixed ring 44 may be fixed by a fastening member 45. When the vacuum spray freezing nozzle 43 is connected to the support ring 42A, a sealing member such as an O-ring may be interposed between the support ring 42A and the vacuum spray freezing nozzle 43.

As shown in FIG. 3, the vacuum spray freezing nozzle 43 has an inlet surface S1 and an outlet surface S2.
The inlet surface S1 is a surface where the injection hole 51 opens, and is a surface of the vacuum spray freezing nozzle 43 that faces the inside of the introduction pipe 42. The inlet surface S1 may be a flat surface such as a horizontal surface, or may be a curved surface. The inlet surface S1 may be a convex surface that protrudes toward the inside of the introduction pipe 42, or may be a convex surface that protrudes toward the injection surface S2.

The injection surface S2 is the surface where the injection hole 51 opens, and is the surface exposed to the vacuum space 21S within the vacuum spray freezing nozzle 43. The injection surface S2 may be the surface facing the tray 21T, or it may be a surface facing a member other than the tray 21T within the vacuum space 21S. The injection surface S2 may be a flat surface such as a horizontal surface, or it may be a curved surface. The injection surface S2 may be a convex surface that protrudes toward the vacuum space 21S, or it may be a convex surface that protrudes toward the inflow surface S1.

The injection hole 51 penetrates between the inflow surface S1 and the injection surface S2. The injection hole 51 may be a circular hole having a constant diameter extending from the inflow surface S1 toward the injection surface S2. The inner hole surface 51S of the injection hole 51 is a surface that separates the inflow surface S1, the injection surface S2, and the bulk of the vacuum spray freezing nozzle 43 from the injection hole 51. When the injection hole 51 is a circular hole, the inner hole surface 51S of the injection hole 51 is a cylindrical surface extending from the inflow surface S1 toward the injection surface S2. The inner diameter 51R of the injection hole 51 may be 0.05 mm or more and 0.5 mm or less. The inner diameter of the injection hole 51 determines the thickness of the liquid column L1 and thus the size of the liquid droplets L2. The inner diameter 51R of the injection hole 51 is appropriately selected according to the size of the frozen particles L3. In addition, the length of the injection hole 51, which is the distance between the inflow surface S1 and the injection surface S2, acts as a resistance to the fluid and determines the thickness of the liquid column L1, and thus the size and particle size distribution of the droplets L2. From the viewpoint of stabilizing the shape of the liquid column L1, it is generally preferable for the resistance to the fluid to be low, and the length of the injection hole 51 is set to a few mm.

As shown in FIG. 4, the injection hole 51 may be composed of a truncated cone hole extending from the inlet surface S1 to the injection surface S2, a truncated cone hole extending from the injection surface S2 to the inlet surface S1, and a circular hole connecting the truncated cone holes. In this case, the hole inner surface 51S of the injection hole 51 may be composed of a first truncated cone cylindrical surface 511S, a second truncated cone cylindrical surface 512S, and a cylindrical surface 513S. The first truncated cone cylindrical surface 511S extends from the inlet surface S1 to the injection surface S2 with the inlet H1 as its bottom. The second truncated cone cylindrical surface 512S extends from the injection surface S2 to the inlet surface S1 with the injection port H2 as its bottom. One cylindrical surface 513S has a constant diameter and connects the top of the truncated cone cylindrical surface 511S to the top of the truncated cone cylindrical surface 512S.

The injection hole 51 may also be composed of a truncated cone hole extending from the inflow surface S1 toward the injection surface S2 and a circular hole connecting the truncated cone hole and the injection surface S2. In this case, the hole inner surface 51S of the injection hole 51 may be composed of a first truncated cone cylindrical surface 511S and a single cylindrical surface extending from the first truncated cone cylindrical surface 511S to the injection surface S2. Alternatively, the injection hole 51 may be composed of a circular hole extending from the inflow surface S1 toward the injection surface S2 and a truncated cone hole extending from the circular hole toward the injection surface S2. In this case, the hole inner surface 51S of the injection hole 51 may be composed of a single cylindrical surface extending from the inflow surface S1 toward the injection surface S2 and a second truncated cone cylindrical surface 512S from the cylindrical surface to the injection surface S2.

As shown in FIG. 5, the injection hole 51 may be a truncated cone hole extending from the inlet surface S1 toward the injection surface S2. Alternatively, the injection hole 51 may be a truncated cone hole extending from the injection surface S2 toward the inlet surface S1. In this case, the hole inner surface 51S of the injection hole 51 may be a truncated cone cylindrical surface tapering from the inlet surface S1 toward the injection surface S2, or may be a truncated cone cylindrical surface tapering from the injection surface S2 toward the inlet surface S1.

The boundary between the hole inner surface 51S and the inlet surface S1 is the inflow port H1, which is one opening in the injection hole 51. The boundary between the hole inner surface 51S and the injection surface S2 is the injection port H2, which is the other opening in the injection hole 51. The inflow port H1 is the opening through which the raw material liquid is introduced into the injection hole 51. The injection port H2 is the opening through which the raw material liquid is discharged into the vacuum space 21S.

At least one of the inlet surface S1 and the ejection surface S2 is a target surface. The surface formed by the target surface and the hole inner surface 51S has a region where the contact angle decreases in the direction from the target surface toward the hole inner surface 51S. The region where the contact angle decreases in the direction from the target surface toward the hole inner surface 51S may be a region where the contact angle increases in a direction perpendicular to that direction.

Areas where the contact angle decreases in the direction from the target surface to the inner hole surface 51S guide the flow of the raw material liquid toward the area with the lower contact angle.Areas where the contact angle increases in the direction perpendicular to the direction from the target surface to the inner hole surface 51S also guide the flow of the raw material liquid in the direction from the target surface to the inner hole surface 51S.

The region where the contact angle decreases in the direction from the target surface to the hole inner surface 51S may be a region where the contact angle decreases in one step, a region where the contact angle decreases in multiple steps, or a region where the contact angle decreases continuously. When the contact angle decreases in steps, the position that is the boundary of the contact angle may be inside the target surface, may be the boundary between the target surface and the hole inner surface 51S, or may be inside the hole inner surface 51S.

When the inlet surface S1 is the target surface, the direction from the target surface to the hole inner surface 51S may be (i) a first guide direction DS1 that is a direction along the inlet surface S1 within the inlet surface S1 and has as a component a direction from the outside of the inlet H1 in the inlet surface S1 toward the inlet H1. The first guide direction DS1 may be the radial direction of the injection hole 51, or may be a swirling direction having the radial direction as a component.

When the inflow surface S1 is the target surface, the direction from the target surface to the hole inner surface 51S may be (ii) a direction from the inflow surface S1 into the hole inner surface 51S. The direction from the inflow surface S1 into the hole inner surface 51S is the inflow direction DH1. The inflow direction DH1 is applied to the range from the inflow opening H1 in the hole inner surface 51S to the center position 51C in the extension direction of the hole inner surface 51S. The inflow direction DH1 is a direction along the hole inner surface 51S, and has as a component the direction from the inflow opening H1 toward the injection port H2. The inflow direction DH1 may be the extension direction of the injection port 51, or it may be a spiral direction having the extension direction as a component.

When the inflow surface S1 is the target surface, the direction from the target surface to the hole inner surface 51S may have a first guide direction DS1 at the inflow surface S1 and an inflow direction DH1 at the hole inner surface 51S.

When the injection surface S2 is the target surface, the direction from the target surface to the hole inner surface 51S may be (iii) a second guide direction DS2 that is a direction along the injection surface S2 within the injection surface S2 and has as a component a direction from the outside of the injection port H2 on the injection surface S2 toward the injection port H2. The second guide direction DS2 may be the radial direction of the injection port 51, or a swirling direction having the radial direction as a component.

When the injection surface S2 is the target surface, the direction from the target surface to the hole inner surface 51S may be (iv) a direction from the injection surface S2 into the hole inner surface 51S. The direction from the injection surface S2 into the hole inner surface 51S is the counter-inflow direction DH2. The counter-inflow direction DH2 is applied to the range from the injection port H2 in the hole inner surface 51S to the center position 51C in the extension direction of the hole inner surface 51S. The counter-inflow direction DH2 is a direction along the hole inner surface 51S, and has as a component the direction from the injection port H2 toward the inlet H1. The counter-inflow direction DH2 may be the extension direction of the injection port 51, or may be a spiral direction having the extension direction as a component.

When the ejection surface S2 is the target surface, the direction from the target surface to the hole inner surface 51S may have a second guide direction DS2 on the ejection surface S2 and a counter-flow direction DH2 on the hole inner surface 51S.

For example, the vacuum spray freezing nozzle 43 shown in Figures 3, 4, and 5 may have a region in at least a part of the inlet H1, which is the boundary between the inlet surface S1 and the hole inner surface 51S, where the contact angle decreases in the direction from the inlet surface S1 to the hole inner surface 51S. The vacuum spray freezing nozzle 43 may also have a region in the inlet surface S1, outside the injection hole 51 more than the inlet H1, where the contact angle decreases in the first guide direction DS1 from the inlet surface S1 to the hole inner surface 51S. The vacuum spray freezing nozzle 43 may also have a region in the hole inner surface 51S, in the range from the inlet H1 to the center position 51C, where the contact angle decreases in the inlet direction DH1.

For example, the first frustum cylindrical surface 511S of the vacuum spray freezing nozzle 43 shown in FIG. 4 may have a region where the contact angle decreases in the inflow direction DH1. The vacuum spray freezing nozzle 43 may also have a region where the contact angle decreases in the inflow direction DH1 in the range from the boundary between the first frustum cylindrical surface 511S and the cylindrical surface 513S to the center position 51C.

The nozzle 43 for vacuum spray freezing may also have a region where the contact angle decreases in the inflow direction DH1 at the boundary between the first truncated cylindrical surface 511S and the cylindrical surface 513S. In this case, in a cross section of the nozzle 43 for vacuum spray freezing including the central axis of the injection hole 51, the angle of the first truncated cylindrical surface 511S with respect to the cylindrical surface 513S may be greater than the difference between the contact angle of the first truncated cylindrical surface 511S and the contact angle at the cylindrical surface 513S, or may be less than or equal to the difference. From the viewpoint of making the flow of the raw material liquid smoother, it is preferable that the angle of the first truncated cylindrical surface 511S with respect to the cylindrical surface 513S, that is, the angle formed by the extension surface of the cylindrical surface 513S and the first truncated cylindrical surface 511S, is greater than the difference between the contact angle of the first truncated cylindrical surface 511S and the contact angle at the cylindrical surface 513S.

For example, the vacuum spray freezing nozzle 43 shown in Figures 3, 4, and 5 may have an area in at least a part of the nozzle hole H2, which is the boundary between the injection surface S2 and the hole inner surface 51S, where the contact angle decreases in the direction from the injection surface S2 to the hole inner surface 51S. The vacuum spray freezing nozzle 43 may also have an area in the injection surface S2, outside the injection hole 51 beyond the injection hole H2, where the contact angle decreases in the second guide direction DS2 from the injection surface S2 to the hole inner surface 51S. The vacuum spray freezing nozzle 43 may also have an area in the hole inner surface 51S, in the range from the injection hole H2 to the center position 51C, where the contact angle decreases in the anti-inflow direction DH2.

For example, the second frustum cylindrical surface 512S of the vacuum spray freezing nozzle 43 shown in FIG. 4 may have a region where the contact angle decreases in the anti-inflow direction DH2. The vacuum spray freezing nozzle 43 may also have a region where the contact angle decreases in the anti-inflow direction DH2 in the range from the boundary between the second frustum cylindrical surface 512S and the cylindrical surface 513S to the center position 51C.

The nozzle 43 for vacuum spray freezing may also have a region at the boundary between the second truncated cone cylindrical surface 512S and the cylindrical surface 513S where the contact angle decreases in the anti-inflow direction DH2. In this case, in a cross section of the nozzle 43 for vacuum spray freezing including the central axis of the injection hole 51, the angle of the second truncated cone cylindrical surface 512S with respect to the cylindrical surface 513S may be greater than the difference between the contact angle at the cylindrical surface 513S and the contact angle of the second truncated cone cylindrical surface 512S, or may be less than or equal to the difference. From the viewpoint of making the flow of the raw material liquid smoother, it is preferable that the angle of the second truncated cone cylindrical surface 512S with respect to the cylindrical surface 513S, i.e., the angle formed by the extension surface of the cylindrical surface 513S and the second truncated cone cylindrical surface 512S, is greater than the difference between the contact angle at the cylindrical surface 513S and the contact angle of the second truncated cone cylindrical surface 512S.

The contact angle is the advancing contact angle of water measured by the sessile drop method in accordance with JIS R 3257:1999. The regions where the contact angle decreases in the direction from the target surface toward the hole inner surface 51S are the regions where the contact angle decreases in the first guide direction DS1, the second guide direction DS2, the inflow direction DH1, and the counter-inflow direction DH2.

The region where the contact angle is reduced in each direction DS1, DS2, DH1, DH2 may be realized by the presence or absence of a surface liquid-repellent layer on the surface of the vacuum spray freezing nozzle 43, or by the difference in liquid-repellent performance of the surface liquid-repellent layer. Also, the region where the contact angle is reduced in each direction DS1, DS2, DH1, DH2 may be realized by the presence or absence of a surface unevenness structure on the surface of the vacuum spray freezing nozzle 43, or by the difference in flow performance of the surface unevenness structure. Also, the region where the contact angle is reduced in each direction DS1, DS2, DH1, DH2 may be realized by the magnitude of surface roughness on the surface of the vacuum spray freezing nozzle 43. Alternatively, the region where the contact angle is reduced in each direction DS1, DS2, DH1, DH2 may be realized by the presence or absence of a surface unevenness structure on the surface liquid-repellent layer, or by the difference in flow performance of the surface unevenness structure on the surface liquid-repellent layer, or by the magnitude of surface roughness on the surface liquid-repellent layer.

The surface liquid-repellent layer repels the raw material liquid on the surface of the vacuum spray freezing nozzle 43 more than a vacuum spray freezing nozzle 43 that does not have a surface liquid-repellent layer. The material constituting the surface liquid-repellent layer is, for example, at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and perfluoroethylenepropene copolymer (FEP). The material constituting the surface liquid-repellent layer is, for example, a plating film co-deposited with a water-repellent resin, or a zinc-nickel-silica composite plating film that has been treated with a water-repellent silane coupling. From the viewpoint of obtaining high liquid repellency, the material constituting the surface liquid-repellent layer preferably contains a fluororesin. In addition, from the viewpoint of obtaining mechanical durability of the surface liquid-repellent layer, the surface liquid-repellent layer is preferably a plating film co-deposited with a fluororesin. If the plating film is co-deposited with a fluororesin, the fluororesin is easily distributed uniformly in the surface liquid-repellent layer, and the liquid repellency due to the fluororesin and the durability due to the plating film are easily obtained uniformly throughout the surface liquid-repellent layer.

The surface liquid-repellent layer is, for example, a nickel plating film co-deposited with PTFE. The nickel plating film is, for example, an electroless nickel plating film containing 30% PTFE. With an electroless nickel plating film, PTFE, which is an example of a fluororesin, is easily distributed uniformly in the nickel plating film, making it easier to obtain liquid repellency to liquid components uniformly over almost the entire surface liquid-repellent layer. Furthermore, with a nickel plating film, even if the raw material liquid contains powder, the surface liquid-repellent layer can obtain abrasion resistance against powder.

The surface unevenness structure is a stripe-like unevenness along each direction DS1, DS2, DH1, DH2 finely machined on the surface of the vacuum spray freezing nozzle 43. The surface unevenness structure on the inlet surface S1, the injection surface S2, or the hole inner surface 51S may be vertical stripes formed by cutting such as laser processing or water jet cutting. The surface unevenness structure on the inlet surface S1, the injection surface S2, or the hole inner surface 51S may be vertical stripes formed by cutting such as broaching, shaping, or slotting, or grinding. The surface unevenness structure on the hole inner surface 51S may be vertical stripes formed by electric discharge processing such as wire electric discharge processing or electrode electric discharge processing. Furthermore, the surface unevenness structure on the inlet surface S1, the injection surface S2, or the hole inner surface 51S may be stripes formed on the inlet surface S1, the injection surface S2, or the hole inner surface 51S through collision between the particles and the surface due to repeated preliminary injection using the particles contained in the raw material liquid.

Surface roughness is the magnitude of unevenness in each direction DS1, DS2, DH1, and DH2 machined on the surface of the vacuum spray freezing nozzle 43. The surface roughness may be the arithmetic mean height, the maximum height, or the maximum valley depth. The uneven structure that determines the surface roughness is formed using the processing method described in the uneven surface structure.

The size of the unevenness of the surface unevenness structure, and the relationship between the size of the unevenness that determines the surface roughness and the contact angle, differ depending on whether the chemical properties of the surface with respect to the raw material liquid are liquid-repellent or liquid-philic.

For example, if the chemical properties of the target surface or hole inner surface 51S are lyophilic, when the entire interior of the unevenness that constitutes the surface unevenness structure or the unevenness that determines the surface roughness comes into contact with the raw material liquid, the surface area for the raw material liquid increases by the amount of the unevenness, emphasizing the wettability of the surface. In other words, when the surface is composed of unevenness large enough that the entire surface comes into contact with water, the target surface or hole inner surface 51S emphasizes the wettability. The surface unevenness structure that extends in each direction DS1, DS2, DH1, and DH2 emphasizes the lyophilicity that has affinity for the raw material liquid, and induces the flow of the raw material liquid in the direction in which the unevenness extends.

For example, if the chemical properties of the target surface or the hole inner surface 51S are liquid repellent, when only the tips of the projections and recesses that make up the surface unevenness structure are in contact with the raw material liquid, the surface area with respect to the raw material liquid is reduced by the amount of the projections and recesses, emphasizing the liquid repellency of the surface. In other words, when the surface is made up of projections and recesses that are so small that only the tips of the projections come into contact with water, the suppression of wettability is emphasized on the target surface or the hole inner surface 51S. The surface unevenness structure that extends in each of the directions DS1, DS2, DH1, and DH2 strengthens the suppression of wettability in the direction perpendicular to the direction, and further strongly induces the flow of the raw material liquid in the direction in which the projections and recesses extend.

[Action]
The granulation method using the above-mentioned vacuum spray freezing nozzle includes supplying a raw material liquid to the vacuum spray freezing nozzle 43, and spraying the raw material liquid from the vacuum spray freezing nozzle 43 into the inside of the vacuum chamber 21 to cause granules made of the raw material liquid to self-dry inside the vacuum chamber 21.

The raw material liquid supplied to the injector 41 passes through the inlet surface S1 from the introduction pipe 42 and enters the inside of the hole inner surface 51S from the inlet H1. The raw material liquid that has entered the inside of the hole inner surface 51S is injected from the injection port H2 into the vacuum space 21S. The raw material liquid injected from the injection port H2 forms a liquid column L1 extending from the injection port H2. The liquid components contained in the liquid column L1 evaporate in the vacuum space 21S by absorbing latent heat of evaporation from the raw material liquid and the like. The liquid droplets L2 that have been deprived of the latent heat of evaporation begin to self-freeze and turn into frozen particles L3. The solid phase (solidified portion) of the liquid components contained in the frozen particles L3 also evaporates by absorbing latent heat of sublimation from the raw material and the like. As a result, the raw material particles self-freeze, and the frozen particles L3, which are the freeze-dried product of the raw material, are deposited on the tray 21T.

The liquid column L1 and the droplets L2 undergo precession near the injection port H2, which causes the frozen particles L3 in FIG. 1 to be distributed in a conical shape, that is, radially in cross section. In other words, the precession of the liquid column L1 and the droplets L2 changes the position of the liquid column L1, which is connected in a straight line, and the position of the droplets L2, which are scattered on the straight line, in accordance with the change in the extension direction of the straight line over the period during which the raw material liquid is injected. In FIG. 1, the above-mentioned precession and the flow of gas converted to a gas phase are combined to show that the landing position of the frozen particles L3 on the tray 21T spreads over a certain range. Incidentally, as a result of observing the generation process of the frozen particles L3 using a high-speed camera, the change from the droplets L2 to the frozen particles L3 is only a phase change from liquid to solid. It was also confirmed that the direction of movement of frozen particle L3 followed the direction of movement of droplet L2, tracing a trajectory that roughly followed the law of inertia, and landing toward tray 21T.

Here, if the raw material liquid stagnates at the inlet surface S1 or the flow of the raw material liquid stagnates at the inlet H1 prior to the start of the injection of the raw material liquid, air bubbles will be present in the raw material liquid flowing out of the injection port H2, or pulsation will occur in the raw material liquid flowing out of the injection port 51. In addition, gas dissolved in the raw material liquid may be present as an indirect cause, and a phenomenon suspected to be cavitation will occur. Since the presence of air bubbles or pulsation will cause the liquid column L1 to become unstable, it is necessary to preliminarily flow more raw material liquid before the start of the injection of the raw material liquid until a steady flow of the raw material liquid is formed. Similarly, just before the end of the injection of the raw material liquid, if the raw material liquid stagnates at the inlet surface S1 or the flow of the raw material liquid stagnates at the inlet H1, air bubbles will be present in the raw material liquid flowing out of the injection port H2, or pulsation will occur in the raw material liquid flowing out of the injection port 51. And when the injection of the raw material liquid ends, in order to ensure a steady flow of the raw material liquid, it is necessary to leave as much raw material liquid in the supply system to complete the process.

In this regard, the region where the contact angle decreases in the direction from the inlet surface S1 toward the hole inner surface 51S exerts a driving force that pushes the raw material liquid located at the boundary between the inlet surface S1 and the hole inner surface 51S from the inlet surface S1 toward the hole inner surface 51S. Also, as in the configuration (i) above, the region where the contact angle decreases in the direction from the inlet surface S1 toward the hole inner surface 51S exerts a driving force that pushes the raw material liquid located around the inlet H1 toward the inlet H1. Also, as in the configuration (ii) above, the region where the contact angle decreases in the direction from the inlet surface S1 toward the hole inner surface 51S exerts a driving force that smooths the flow of raw material liquid inside the injection hole 51 and directs the flow of raw material liquid from the inlet H1 to the injection hole H2.

Therefore, the area where the contact angle decreases in the direction from the inlet surface S1 toward the hole inner surface 51S smooths the flow of the raw material liquid at the start and end of spraying, suppressing the inclusion of air bubbles and flow pulsation. As a result, the amount of raw material liquid discharged prior to the start of spraying of the raw material liquid is suppressed, and the amount of raw material liquid remaining in preparation for the end of spraying of the raw material liquid is suppressed. Note that a smooth flow of raw material liquid near the inlet H1 is understood to be a flow in which the fluid resistance at the contact interface between the vacuum spray freezing nozzle 43 and the raw material liquid is reduced compared to the upstream area in that vicinity.

While the raw material liquid is being sprayed, some of the raw material liquid sprayed from the nozzle H2 does not form the liquid column L1, or is separated (split) from the liquid column L1 and scatters as microdroplets toward the periphery of the nozzle H2. A particularly large number of microdroplets can be formed in a highly viscous raw material liquid compared to a low-viscosity raw material liquid such as water. Many of the scattered microdroplets reach the periphery of the nozzle H2 and self-freeze and dry on the spray surface S2. The raw material liquid that self-freezes on the spray surface S2 does not undergo a phase transition upon contact with other raw material liquids, but continues to exist as a solid phase, changing the spray direction of the raw material liquid and the direction in which the liquid column L1 grows.

In this regard, the region where the contact angle decreases in the direction from the ejection surface S2 toward the hole inner surface 51S exerts a driving force that pushes back the raw material liquid located at the boundary between the ejection surface S2 and the hole inner surface 51S from the ejection surface S2 toward the hole inner surface 51S. Also, as in the configuration (iii) above, the region where the contact angle decreases in the direction from the ejection surface S2 toward the hole inner surface 51S exerts a driving force that pushes back the raw material liquid that overflows from the ejection port H2 to its periphery toward the ejection port H2. Also, as in the configuration (iv) above, the region where the contact angle decreases in the direction from the ejection surface S2 toward the hole inner surface 51S realizes an increase in the contact angle near the ejection port H2 so that the flow of the raw material liquid that reaches the ejection port H2 is unlikely to be directed outside the ejection port H2. This makes it possible to prevent the raw material liquid pushed out of the ejection port 51 from scattering toward the periphery of the ejection port H2, and to smoothly form the liquid column L1.

In particular, when the angle of the second truncated cone cylindrical surface 512S relative to the cylindrical surface 513S is greater than the difference between the contact angle on the cylindrical surface 513S and the contact angle on the second truncated cone cylindrical surface 512S, the suppression of splashing due to the structure of the injection hole 51 and the suppression of splashing due to the contact angle of the hole inner surface 51S combine to form the liquid column L1 more smoothly. The suppression of splashing due to the structure of the injection hole 51 switches the flow path of the raw material liquid from the cylindrical surface 513S to the second truncated cone cylindrical surface 512S, thereby gradually suppressing contact between the raw material liquid and the hole inner surface 51S at the front stage of the injection hole H2.

In this way, the area where the contact angle decreases in the direction from the ejection surface S2 toward the hole inner surface 51S smoothes the flow of the raw material liquid not only at the start and end of ejection but also during ejection, preventing the raw material liquid from scattering as microdroplets and preventing the scattered microdroplets from solidifying around the ejection port H2. As a result, a smooth flow of the raw material liquid is achieved, and variation in the particle size of the product produced by freeze-drying is suppressed.

The smooth flow of raw material liquid near the nozzle H2 can also be interpreted as a phenomenon in which the surface of the liquid column L1 of a fixed shape is continuously renewed without splitting in response to the raw material liquid being pushed out. Even if split pieces of raw material liquid exist, the driving force toward the nozzle H2 causes each surface to quickly merge into the surface of the liquid column L1, forming a dynamically stable flow. This can be defined as smooth.

As described above, according to the above embodiment, the following effects can be obtained.
(1) When the target surface is the ejection surface S2, the raw material liquid exerts a driving force that returns the raw material liquid in a direction from the ejection surface S2 toward the hole inner surface 51S, thereby suppressing the scattering of the raw material liquid toward the periphery of the ejection port H2.

(2) When the target surface is the inflow surface S1, the raw material liquid exerts a driving force that pushes the raw material liquid in a direction from the inflow surface S1 toward the hole inner surface 51S, and when the raw material liquid starts to be sprayed or when the raw material liquid is stopped to be sprayed, the raw material liquid flows smoothly into the inside of the spray hole 51. In other words, a smooth flow of the raw material liquid is achieved.

(3) When the contact angle decreases in the direction from the ejection surface S2 toward the hole inner surface 51S and also at the ejection port H2, the raw material liquid located at the boundary between the ejection surface S2 and the hole inner surface 51S exerts a driving force that pushes the raw material liquid back toward the inside of the ejection port 51. This more effectively prevents the raw material liquid from splashing toward the periphery of the ejection port H2.

(4) As in (ii) above, when the hole inner surface 51S has a region where the contact angle decreases in the inflow direction DH1, it is possible to smoothly push the raw material liquid located inside the injection hole 51 along the hole inner surface 51S.

(5) As in (iv) above, when the hole inner surface 51S has a region where the contact angle decreases in the counter-flow direction DH2, the raw material liquid is pushed toward the nozzle H2 so that the flow of the raw material liquid when it reaches the nozzle H2 is unlikely to be directed outward from the nozzle H2. This prevents the raw material liquid pushed out of the nozzle 51 from scattering toward the periphery of the nozzle H2, making it possible to smoothly form the liquid column L1.

(6) When the contact angle decreases stepwise, effects similar to those of (1) to (5) above can be obtained depending on the presence or absence of surface treatment, such as the presence or absence of a liquid-repellent surface layer or the presence or absence of a liquid-repellent surface structure. This makes it possible to suppress the increase in the manufacturing load of the vacuum spray freezing nozzle compared to the manufacture of a vacuum spray freezing nozzle in which the degree of surface treatment is gradually changed.

(7) When the injection hole 51 is a circular hole with a constant diameter, it is possible to easily process the hole from the inlet H1 to the injection hole H2 and to easily ensure the accuracy of the hole dimensions.

(8) When the angle formed by the cylindrical surface 513S and the second frustum cylindrical surface 512S is greater than the difference between the contact angle of the cylindrical surface 513S and the contact angle of the second frustum cylindrical surface 512S, in addition to guiding the raw material liquid by the contact angle, the structure of the injection hole 51 also makes it possible to suppress splashing toward the periphery of the injection hole H2.

(9) If the area in which the contact angle decreases in the direction from the target surface toward the inner surface of the hole 51S is due to differences in the surface unevenness or surface roughness, the effects equivalent to those of (1) to (8) above can be obtained by a general-purpose method such as applying surface treatment to the vacuum spray freezing nozzle 43.

The above embodiment can be modified as follows.
A cover such as the fixing ring 44 may have a hole that expands from the injection hole 51 toward the vacuum space 21S. That is, the hole of the cover may have a frustum cylindrical surface shape that tapers toward the injection hole 51. Also, the hole of the cover may have a cylindrical surface shape with a diameter sufficiently larger than that of the injection hole 51.

The surface of the cover may also have liquid repellency to repel the liquid components of the raw material liquid. This configuration can further prevent the freeze-dried material from accumulating around the injection hole 51. The liquid repellency of the cover surface may be provided by the cover itself being made of a material having liquid repellency, or the cover surface may be made of a liquid repellent layer.

The liquid repellent layer may be a water repellent silane coupling agent applied to the surface of the vacuum spray freezing nozzle 43 .
The material constituting the vacuum spray freezing nozzle 43 may be, for example, a water-repellent resin such as PTFE, PFA, or FEP. In this case, the liquid-repellent layer may be omitted, and the outer surface of the vacuum spray freezing nozzle 43 may be the outer surface of the vacuum spray freezing nozzle that has liquid-repellent properties. In other words, the liquid-repellent properties of the outer surface of the vacuum spray freezing nozzle may be borne by the liquid-repellent properties of the vacuum spray freezing nozzle 43.

- The region where the contact angle is continuously decreased may be configured with regions with two different contact angles arranged in a comb-like shape. When viewed from a viewpoint facing the inflow surface S1, the region where the contact angle is continuously decreased on the inflow surface S1 may be configured with each tooth of the comb-like shape as the hypotenuse of an isosceles triangle, and the area of the region with one contact angle may be continuously changed from 0% to 100% in the direction from the base to the apex of the isosceles triangle. Similarly, when viewed from a viewpoint facing the ejection surface S2, the region where the contact angle is continuously decreased on the ejection surface S2 may be configured with each tooth of the comb-like shape as the hypotenuse of an isosceles triangle, and the area of the region with one contact angle may be continuously changed from 0% to 100% in the direction from the base to the apex of the isosceles triangle.

In other words, the region where the contact angle is continuously decreased may be configured such that, for each area in the region having two different types of contact angles, one side is continuously increased and the other side is continuously decreased. With such a configuration, in the region having two types of contact angles, the contact angle per unit area acts on the liquid as a value obtained by unifying the contributions due to the area ratio of the regions having each contact angle, that is, a contact angle unified by the area ratio of each contact angle. Note that if the pitch width of the teeth in the comb shape is, for example, 1/2 or less of the expected droplet diameter of the split raw material liquid, it is possible to exert a sufficient driving force on the split droplets.

The liquid-repellent layer and the uneven surface structure may be omitted from the injection hole 51 and positioned only on the injection surface of the vacuum spray freezing nozzle. The liquid-repellent layer and the uneven surface structure may be positioned only on the part of the injection surface of the vacuum spray freezing nozzle that surrounds the injection hole 51.

The direction from the target surface to the hole inner surface 51S may be at least one of the above (i) to (iv).
The vacuum chamber 21 may be equipped with a heating mechanism for heating the freeze-dried material. If the vacuum chamber 21 is configured to be equipped with a heating mechanism, it is possible to promote drying of the freeze-dried material by heating.

L1: liquid column L2: droplet L3: frozen particle 10: freeze-drying apparatus 11: supply section 21: vacuum chamber 21S: vacuum space 21T: tray 31: vacuum pump 41: injector 42: introduction pipe 42A: support ring 43: nozzle for vacuum spray freezing 44: fixing ring 45: clamping member 51: injection hole 511S: first frustum cylindrical surface 512S: second frustum cylindrical surface 513S: cylindrical surface

Claims (6)

A nozzle for vacuum spray freezing that sprays a raw material liquid into a vacuum space where droplets of the raw material liquid self-freeze,
an inflow surface defining the inflow port of the raw material liquid;
an injection surface that divides an injection port of the raw material liquid;
a hole inner surface that divides an injection hole that communicates with the inlet and the injection port ,
the hole inner surface includes a first truncated cylindrical surface having the inlet as a bottom portion, a second truncated cylindrical surface having the ejection port as a bottom portion, and a cylindrical surface connecting the first truncated cylindrical surface and the second truncated cylindrical surface,
At least one of the first frustum cylindrical surface and the second frustum cylindrical surface is a symmetric cylindrical surface,
The contact angle of the cylindrical surface is smaller than the contact angle of the target cylindrical surface.
Nozzle for vacuum spray freezing. the target cylindrical surface includes the second frustum cylindrical surface,
The nozzle for vacuum spray freezing according to claim 1 , wherein an angle of the second frustum cylindrical surface with respect to the cylindrical surface is greater than a difference value between a contact angle of the cylindrical surface and a contact angle of the second frustum cylindrical surface. A nozzle for vacuum spray freezing that sprays a raw material liquid as a liquid column into a vacuum space where droplets of the raw material liquid self-freeze,
an inflow surface defining the inflow port of the raw material liquid;
an injection surface that divides an injection port of the raw material liquid;
a hole inner surface that divides an injection hole that communicates with the inlet and the injection port ,
The contact angle of the inlet is smaller than the contact angle of the outside of the inlet on the inlet surface.
Nozzle for vacuum spray freezing. A nozzle for vacuum spray freezing that sprays a raw material liquid as a liquid column into a vacuum space where droplets of the raw material liquid self-freeze,
an inflow surface defining the inflow port of the raw material liquid;
an injection surface that divides an injection port of the raw material liquid;
a hole inner surface that divides an injection hole that communicates with the inlet and the injection port ,
The contact angle at the center position of the inner surface of the hole in the extending direction is smaller than the contact angle at the inlet on the inner surface of the hole.
Nozzle for vacuum spray freezing. A vacuum chamber;
a vacuum spray freezing nozzle for spraying the raw material liquid into the vacuum chamber;
A supply unit that supplies the raw material liquid to the vacuum spray freezing nozzle,
The freeze-drying apparatus according to claim 1 , wherein the vacuum spray freezing nozzle is the vacuum spray freezing nozzle according to claim 1 . Supplying a raw material liquid to a nozzle for vacuum spray freezing; and
A granulation method comprising spraying a raw material liquid into a vacuum chamber from the vacuum spray freezing nozzle and allowing granules made of the raw material liquid to self-dry in the vacuum chamber,
The vacuum spray freezing nozzle according to claim 1 ,