JP3467220B2 - Droplet generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet generating apparatus used for obtaining, for example, polymer beads having a uniform particle size. 2. Description of the Related Art A container for storing a liquid in a continuous phase, a porous member having an ejection hole disposed inside the container,
A means for supplying the liquid to be dropletized to the porous member; and a means for vibrating the liquid to be dropletized ejected from the ejection hole, wherein the ejected liquid to be dropletized is changed in accordance with the frequency. 2. Description of the Related Art A droplet generation apparatus that disperses and forms droplets has been conventionally proposed (see Japanese Patent Publication No. 1-28761). [0003] The above-described droplet generating apparatus is used, for example, to polymerize droplets of a monomer to obtain polymer beads having a uniform particle size. It is necessary to increase the number of orifices to be formed. Therefore, as shown in FIG. 5, a porous member 102 in which a large number of ejection holes 101 are uniformly arranged has been used. However, if a large number of ejection holes 101 are evenly arranged, it becomes difficult to generate droplets having a uniform particle diameter.
That is, as shown in FIG.
A porous member 102 in which a large number of ejection holes 101 are evenly arranged is disposed inside a container 104 for storing
When the liquid to be dropletized is supplied to 02 and ejected from the ejection hole 101, and the ejected liquid is vibrated to generate a droplet 105, the droplet 105 rises along with the liquid 103 in a continuous phase state. I do. Therefore, the liquid 103 in the continuous phase state
Flows toward the center of the upward flow of the droplet 105 as shown by the arrow in the figure, and a contraction portion 105 ′ is generated in the upward flow of the droplet 105. The droplets 105 collide with each other at the contraction portion 105 ′ so as to be united or split, so that the size of the droplets 105 becomes uneven. In order to solve such a problem, by arranging a large number of ejection holes formed in a porous member in an annular region, the contraction of the upward flow of the droplet is reduced, and the size of the droplet is made uniform. It has been proposed to achieve this (see Japanese Patent Application Laid-Open No. 3-249931). [0006] By arranging the ejection holes formed in the porous member in an annular region, the liquid in the continuous phase exists at the center of the upward flow of the droplet, and the continuous liquid is present. The flow of the liquid in the phase state toward the center of the upward flow is weakened, and the size of the droplets can be made uniform to some extent. However, in the above-mentioned prior art, the ejection holes are arranged over the entire annular region. Therefore, when the arrangement pitch of the ejection holes is reduced, the circumferential direction is reduced by the contraction of the upward flow of the droplets. The droplets adjacent to each other collide with each other, and the size of the droplets becomes non-uniform. An object of the present invention is to provide a droplet generating apparatus which can solve the above-mentioned problems of the prior art. A feature of the present invention is that a container for storing a liquid in a continuous phase, a porous member having a large number of ejection holes arranged inside the container, Means for supplying the liquid to be dropletized to the porous member, and means for vibrating the liquid to be dropletized ejected from the ejection holes, the droplets having a large number of ejection holes arranged in an annular region In the generator, a plurality of voids in which the orifices are not arranged at intervals in the circumferential direction are provided in the annular region of the porous member in which the orifices are arranged, and the circumferential width of the void is the same as that of the jet.
The point is that it is made larger than the arrangement pitch of the outlet holes . According to the structure of the present invention, a plurality of cavities are provided at intervals in the circumferential direction in the annular region of the porous member in which the ejection holes are arranged, so that the central portion of the upward flow of the droplets is provided. In the circumferential direction, a region where no droplet exists is generated. Since the liquid in the continuous phase forms a passage toward the center of the upward flow in the region where the droplet does not exist, the contraction of the upward flow of the droplet can be reduced. An embodiment of the present invention will be described below with reference to the drawings. A droplet generating apparatus 1 shown in FIG. 3 includes a container 3 for storing a liquid 2 in a continuous phase, and a plate-shaped porous member 4 disposed inside the container 3. As shown in FIG. 1, a large number of ejection holes 5 are provided in the annular region of the porous member 4.
Are arranged. In the annular region of the porous member 4 in which the ejection holes 5 are arranged, a plurality of air spaces 6 in which the ejection holes 5 are not arranged are provided at intervals in the circumferential direction. A housing 7 is provided below the porous member 4, and a tank 8 for storing the liquid to be dropletized is provided in the housing 7 with a pipe 9.
And a pump 10. Thus, the liquid to be dropletized supplied to the porous member 4 is ejected from the ejection holes 5 into the liquid 2 in a continuous phase state. A piezoelectric vibrator 11 for vibrating the ejected liquid is provided inside the housing 7. In order to disperse the liquid to be formed into droplets ejected from the ejection hole 5 in accordance with the frequency of the vibrator 11 to produce a uniform droplet group, the droplet diameter to be produced, the continuous phase According to the physical properties of the liquid 2 in the state or the physical properties of the liquid to be dropletized,
It is necessary to determine the diameter and arrangement pitch of the ejection holes 5 and the ejection speed and frequency of the liquid to be dropletized by trial and error. [0014] The diameter of the ejection hole 5 is determined by the liquid 2 in a continuous phase.
Although it is affected by various factors including physical properties of the liquid to be formed into droplets and conditions of vibration, it is mainly determined by the size of the droplet to be formed. Generally, the size of the droplet to be formed is 20 to 10000 μm, and the diameter of the ejection hole 5 is 1 μm.
It is 0 to 5000 μm. The flow of the liquid to be formed into droplets ejected from the ejection holes 5 needs to be laminar in order to obtain a uniform droplet group. Therefore, when the density of the liquid to be dropletized is ρ, the ejection speed is u, the diameter of the orifice hole is D, and the viscosity of the liquid to be dropletized is μ, Re = D · u · ρ / μ. The Reynolds number is 10 to 2000, preferably 15 to 10
00, particularly preferably 20 to 300. If the Reynolds number is less than 10, the flow rate is small and the production efficiency is low, and if it exceeds 2,000, a turbulent region is formed, so that a uniform droplet group is not generated. The means for vibrating the liquid to be formed into droplets ejected from the ejection holes 5 may be any means having a vibration characteristic capable of dispersing the ejected flow into a uniform group of droplets. 10 to 50,000 Hz is preferred. As a specific vibration means, a mechanical vibrator, an electroacoustic vibrator, a hydroacoustic vibrator, an electromagnetic vibrator, a magnetoresistive transducer, etc. can be used, and these vibrators are connected to a porous member. Then, the porous member may be vibrated, or the liquid to be dropletized may be vibrated as shown in FIG. The arrangement pitch P of the ejection holes 5 is preferably at least 15 times the hole diameter, and the circumferential width s of the air space 6 is set to be larger than the pitch P. The number of the airspaces 6 is preferably 2 to 30, and more preferably 3 to 15. The total of the circumferential width s of the airspace 6 is 0.1 to 0.8 times, preferably 0.2 to 0.7 times, the circumferential length of the annular region. When the radius from the center to the outer diameter of the annular region in which the ejection holes 5 are arranged is r, the inner diameter is preferably 0.3 r or more, preferably 0.5 r or more, and more preferably 0.7 r or more. Above. Further, although the respective ejection holes 5 are arranged on each side of the polygon in FIG. 1, they may be arranged on the circumference, and the specific arrangement is not limited as long as they are arranged in an annular region. In the above-described droplet generating apparatus 1, a 1 wt% PVA solution is stored in the container 3 as the liquid 2 in the continuous phase state, and a monomer solution is supplied to the porous member 4 as a liquid to be dropletized, and is discharged from the ejection hole 5 It is ejected at a flow rate of 1.2 g / min per hole, and the ejected flow is applied to the
A sinusoidal vibration of z was applied. As the monomer solution, a solution of lauroyl acrylate / vinyl acetate / divinylbenzene / lauroyl peroxide = 80/10/9/1 was used. In addition, the diameter of the ejection hole 5 is 80 μm, the arrangement pitch P is 1.5 mm, and as shown in FIG. An airspace 6 not arranged was provided. The sum of the circumferential widths of the six airspaces was 0.18 times the circumferential length of the annular area. The radius of the circumscribed circle of the annular region was 13.5 mm. As a result, a very uniform monodispersed droplet 12 was produced as shown in FIG. That is, the droplet 1
The ascending flow of 2 rises with the surrounding PVA solution 2,
Droplets 12 are located both between the center of the upward flow of the droplet and the circumferential direction.
There is a region where there is no. Since the area where the droplets do not exist becomes a passage for the PVA solution 2 toward the center of the upward flow, the contraction of the upward flow of the droplets 12 is reduced, and the collision of the droplets 12 is prevented. The resulting droplets were polymerized by a conventional method, and as a result, polymer beads having a uniform diameter of about 265 μm were obtained. According to the droplet generating apparatus of the present invention, a plurality of cavities in which the ejection holes are not arranged at intervals in the circumferential direction are formed in the annular region of the porous member in which a large number of ejection holes are arranged. The droplets can be made uniform with a simple configuration of providing the droplets.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a porous member of a droplet generation device according to an embodiment of the present invention. FIG. 2 is an operation explanatory diagram of a droplet generation device according to an embodiment of the present invention. FIG. 4 is an explanatory diagram of a configuration of a droplet generating device according to an embodiment of the present invention. FIG. 4 is an explanatory diagram of an operation of a droplet generating device according to a conventional example. FIG. [Description of Signs] 1 Droplet generating device 2 Liquid in continuous phase 3 Container 4 Porous member 5 Spouting hole 6 Airspace 10 Pump 11 Piezoelectric vibrator

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seiji Tamaki 1334 Minato, Wakayama, Wakayama Pref. References JP-A-3-249931 (JP, A) JP-A-2-305802 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 2/00-2/60 B01J 2 / 06

Claims (1)

(57) [Claim 1] A container for storing a liquid in a continuous phase state, a porous member having a large number of ejection holes disposed inside the container, and droplets formed on the porous member. Means for supplying a target liquid;
Means for vibrating the liquid to be dropletized to be ejected from the ejection holes, wherein the plurality of ejection holes are arranged in an annular region, wherein the porous member in which the ejection holes are arranged In the annular region, a plurality of air spaces in which the ejection holes are not arranged at intervals in the circumferential direction are provided , and a circumferential width of the air space is provided.
The droplet generation device according to claim 1, wherein the arrangement pitch is larger than the arrangement pitch of the ejection holes .