JP3525792B2 - Droplet ejection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to liquid droplets which are preferably used in a powder production apparatus for obtaining, for example, ceramic powder having a uniform particle size distribution by making liquid into fine liquid droplets.
Discharge device The term "ceramic powder" as used in the present invention means a generic term including powders of metal compounds.

[0002]

2. Description of the Related Art Wet or dry mills or spray dryers are known for industrially mass-producing ceramic powders. The crusher is for finely crushing a lumpy raw material into powder, and the spray drying device is for drying the sprayed liquid to form a solid material having a size corresponding to the size of the droplet. is there.

[0003]

Since the powder produced by using a pulverizer has a large variation in particle size distribution, in order to obtain a uniform particle size within a desired range, it is necessary to screen the powder after production. I won't. Even in the spray dryer,
It is difficult to make the droplets uniform with the atomizer. Therefore, it can be considered to make the particle size distribution uniform by using a droplet discharge device that always discharges a constant droplet. When a droplet discharge device is used, a plurality of droplet means are used in order to enhance the discharge capability of a proper amount of liquid, but the number is limited due to the mounting space. Also, since the droplet discharge device has a structure in which the size of the droplets is fixed, it must be operated at a high speed in order to increase the number of discharges. Alternatively, liquid droplets that are continuously discharged may be discharged as large liquid droplets without being separated from each other, and thus there is a limit to the increase in operating speed. or,
In particular, when it is necessary to obtain a small particle size of several tens of μm or less, the ejection amount per droplet becomes small, and the ejection performance is significantly reduced.

[0004]

SUMMARY OF THE INVENTION The present invention is a powder manufacturing apparatus.
A droplet discharge device that can be suitably used for, for the purpose of increasing the discharge ability without impairing the uniformity of the droplet size to be discharged, especially the fine particle size, and its configuration is as follows.
Inlet for introducing liquid and extrusion for ejecting liquid
The pressurizing chamber with the discharge port with the opening chamber and the pressurizing chamber
To introduce liquid and to discharge liquid in the pressure chamber
Pressure applying means for applying intermittent pressure to the
At the outlet, multiple nozzles are set for one pressurizing chamber.
All nozzles are
Of the radius of the bottom surface in the extrusion chamber communicating with the pressure chamber
Connected in the area of concentric circles with a radius of 1/2
Especially .

The droplet discharge device has a cross section of a nozzle opening.
The sum of products is 1.5 to 0.67 with respect to the opening area of the inlet.
Set to double the range, and set the inlet and outlet to the liquid
Tapered shape whose cross-sectional area gradually decreases in the flow direction
Is desirable.

[0006] The pressure chamber is in the form an elongated cavity, the inlet to the central portion with respect to the longitudinal direction, or as having a discharge port comprising a plurality of nozzles on both ends, as well
The pressurizing chamber is composed of a long cavity, and may have a discharge port having a plurality of nozzles at the center in the longitudinal direction and an introduction port at both ends.

[0007]

DETAILED DESCRIPTION OF THE INVENTION A droplet discharge device according to the present invention will be described with reference to the drawings. FIG. 1 shows the droplet discharge device of the present invention .
It shows the powder production equipment that can be used appropriately ,
Reference numeral 1 denotes a quartz heating furnace equipped with external heating heaters 1a, 1a. The heating furnace 1 is connected to the air inlet 2 at the upper side and to the air outlet 3 at the lower side.
A powder recovery box 4 is provided between the air outlet 3 and the air outlet 3, and droplets are introduced into the heating furnace 1 near the connection with the air inlet 2 via the electromagnetic shutters 5 and 5. Equipped with droplet discharge devices 6 and 6 for intermittent discharge.

The droplet discharge device 6 is formed by laminating green sheets made of zirconia ceramics in three steps and integrally firing them. As illustrated in FIG. 2, a window portion cut out is formed in an intermediate sheet. A pressurizing chamber 7 is formed, an inlet 8 and an outlet 9 are provided on the lower surface of the pressurizing chamber 7, and a voltage / electrostrictive element 10 is mounted on the upper surface of the piezoelectric / electrostrictive element. A micropump is constructed which causes a pressure change in the pressurizing chamber 7 by utilizing the strain of 10, and the liquid introduced into the pressurizing chamber 7 from the inlet 8 can be discharged from the outlet 9 by the pressure change. ing.

The pressurizing chamber 7 has an elongated cavity shape, the introduction port 8 is one end portion in the longitudinal direction of the elongated cavity shape, and the discharge port 9 is elongated. The discharge port 9 is located at the other end of the cavity shape in the longitudinal direction, and is composed of two nozzles 9a and 9a. In addition, the discharge port 9 is connected to the pressurizing chamber 7
An extrusion chamber 11 is provided, and the bottom of the extrusion chamber 11 is
In contrast, the center of each nozzle 9a, 9a is pushed out to the bottom of the chamber 11.
In the area of concentric circles equal to half the radius of the plane
The structure is connected to (see Fig. 3). in this way
Since the pressure chamber has a structure with an extrusion chamber, the extrusion chamber 1
The central part within 1 is less affected by viscous resistance.
The passed liquid is sent to the nozzles 9a, 9a,
It is discharged smoothly.

Next, an example of forming a powder of zirconia ceramics by using the powder manufacturing apparatus formed as described above will be described. The inlet 8 of the droplet discharge device 6 was connected to a tank (not shown) of an ethyl alcohol solution of zirconium chloride, which is a precursor of zirconia ceramics,
A voltage is intermittently applied to the voltage / electrostrictive element 10, and a deformation of the voltage / electrostrictive element 10 causes a pressure change in the pressurizing chamber 7, and the pressure change causes the ethyl alcohol of zirconium chloride in the tank. The solution is introduced into the pressurizing chamber 7, the introduced ethyl alcohol solution of zirconium chloride is ejected as minute droplets from the nozzles 9a, 9a, and the ejected droplets are intermittently passed through the electromagnetic shutter 5. It is sent into the heating furnace 1. The liquid droplets sent into the heating furnace 1 are instantaneously evaporated in the heating furnace 1 and remain as zirconia ceramic powder. Therefore, the zirconia ceramic powder is placed on the air flow to collect the powder. Collect within 4.

Since a myriad of minute liquid droplets are discharged through the two nozzles 9a, 9a in this manner, zirconia ceramic powder, which is a ceramic powder of minute and uniform particle size, can be efficiently and quickly produced. You can get a lot. Incidentally, the powder obtained by using this device in which the liquid ejecting means is composed of a micro pump has a particle size of 10 to 180 μm.
In m, it was confirmed that the particle size distribution was within ± 10% of the average particle size.

In the droplet discharge device, green sheets made of zirconia ceramics are laminated in three stages and integrally formed, so that the pressure chamber and the nozzle are also made of zirconia ceramics, and chemical resistance, It has excellent heat resistance and toughness, and can be applied even when using an acetone-based or hydrochloric acid-based liquid. In addition, the pressurizing chamber has an elongated cavity shape, and has an inlet port at one end and an outlet port composed of a plurality of nozzles at the other end in the longitudinal direction of the elongated cavity shape. Since the inlet, pressurizing chamber, and outlet are made of zirconia ceramics, which has good wettability with liquid, the liquid can be smoothly passed from the inlet to the outlet. ,
It is possible to avoid the occurrence of defective ejection due to the adhesion of bubbles or the like in the middle.

In the above-mentioned droplet discharge device, the discharge port is composed of two nozzles, but as shown in FIG. 4, the discharge port 9 is composed of three nozzles 9a, 9a, 9a or more nozzles. Alternatively, as shown in FIG. 5 , the introduction port 8 may be formed of a plurality of through holes 8a, 8a, 8a. When the number of nozzles is increased, the ejection amount is increased, and when the introduction port is composed of a plurality of through holes, the introduction amount is increased and the ejection efficiency is also improved.

Further, the introduction port and the discharge port are not only separately arranged at both ends with respect to the longitudinal direction in the elongated cavity shape, but also as shown in FIG.
A discharge port 9 having a plurality of nozzles 9a, 9a ...
, The inlets 8 are provided at both ends, or the opposite
In addition, although not shown in the figure, it is introduced in the central part in the longitudinal direction.
The mouth can also be provided with a discharge port equipped with nozzles at both ends.
It Then, as shown in FIG.
When a discharge port consisting of
Means that the pressure change in the pressurizing chamber can be efficiently used for discharge.
In addition, there is an advantage, and the inlet is at the center and the outlets at both ends.
If you place, increase the distance between each nozzle.
As the droplets are ejected, it is necessary to prevent the ejected droplets from interfering with each other.
Avoidance and smooth introduction of liquid into the pressure chamber
It has advantages such as that.

By the way, if there is no shut-off mechanism such as a valve for both the discharge port and the introduction port, the liquid tries to be discharged from both the discharge port and the introduction port due to the pressure change of the pressurizing chamber.
It is necessary to discharge efficiently from the discharge port at the time of discharge, and at the time of introduction, the liquid must be introduced only from the introduction port. Therefore, the introduction port and the ejection port are defined as the sum of the cross-sectional areas of the nozzle openings, depending on the arrangement of the introduction port and the ejection port, the number of through holes that configure the introduction port, and the number of nozzles that configure the ejection port. 1.5 to 0.6 for the area of the opening
It is desirable that the discharge efficiency be optimized by setting the range to be 7 times. Also as illustrated in Figure 7, an inlet 8, constituting the discharge port 9 to which a nozzle 9a, and 9a,
If the tapered shape is such that the cross-sectional area gradually decreases with respect to the flow direction, the fluid resistance in the liquid flow direction decreases and increases in the opposite direction. Not only can efficiency be improved, but a backflow prevention effect can also be expected.

The above-mentioned powder producing apparatus produces a ceramic powder by heat-treating the discharged liquid as it is.
It is also possible to subject the discharged droplets to a reaction treatment once in the reaction tank and heat-treat them. Next, an example will be described.
FIG. 8 shows a part of another powder manufacturing apparatus,
Reference numeral 12 is a reaction tank, and 13 and 14 are droplet discharge devices. The reaction tank 12 has a reaction solution injection port 15 in the upper part and an ejection port 16 in the lower part. An ethyl alcohol solution of sodium hydroxide is stored in the reaction tank 12. The droplet ejecting device 13 ejects aluminum ethoxide ethyl alcohol solution, and the droplet ejecting device 14 ejects zirconium chloride ethyl alcohol solution. Each of the discharged droplets is reacted with an ethyl alcohol solution of sodium hydroxide in the reaction tank 12, and the product obtained by the reaction is taken out from the take-out port 16 and thermally decomposed, whereby zirconia particles and alumina particles are obtained. It is possible to obtain a mixed powder of Also in this example, it was confirmed that the powders of zirconia and alumina were all uniform in particle size.

The liquid ejecting means used in the liquid droplet ejecting apparatus of the present invention is not limited to the micropump system, and even in the micropump system, an electric typified by a voltage / electrostrictive element is used. In addition to mechanical conversion method, charge control method,
An electrothermal conversion method, an electrostatic suction method, etc. can be adopted. or,
The form of the pressurizing chamber, the positions of the introduction port and the discharge port, etc. may be appropriately changed without departing from the spirit of the present invention. Further, the liquid used is appropriately selected according to the type of ceramic powder to be manufactured.

[0018]

According to the droplet discharge device of the present invention, extrusion is performed.
Central part that is not easily affected by viscous resistance in the room
Since the liquid that has passed through is sent to multiple nozzles,
If the droplets are smoothly discharged and used in a powder manufacturing apparatus, it is possible to efficiently obtain a ceramic powder having a uniform particle size. Then, the pressurizing chamber has a long cavity shape, or the inlet and the discharge port are separately arranged at both ends with respect to the long cavity shape, or the discharge port is composed of a plurality of nozzles, The ejection efficiency can be further improved by forming the introduction port with a plurality of holes, tapering each nozzle, or limiting the opening area ratio of the introduction port and the ejection port.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a powder manufacturing apparatus that can suitably use a droplet discharge device according to the present invention.

FIG. 2 shows an embodiment of a droplet discharge device according to the present invention,
(A) is sectional explanatory drawing, (b) is explanatory drawing which showed the positional relationship of an inlet and an outlet.

FIG. 3 is an explanatory diagram showing a connection relationship of nozzles with respect to an extrusion chamber.

FIG. 4 is an explanatory diagram showing an example of changing the positions of the inlet and the outlet with respect to the pressurizing chamber.

FIG. 5 is an explanatory diagram showing an example of changing the positions of the inlet and the outlet with respect to the pressurizing chamber.

FIG. 6 is an explanatory diagram showing an example of changing the positions of the inlet and the outlet with respect to the pressurizing chamber.

FIG. 7 is an explanatory diagram exemplifying a modification of the introduction port and the nozzle.

FIG. 8 is an explanatory view showing a modified embodiment of the powder manufacturing apparatus.

[Explanation of symbols]

1 ... Heating furnace, 1a ... External heater for heating, 2 ... Air inlet, 3 ... Air outlet, 4 ... Powder recovery box,
5 ... Electromagnetic shutter, 6 ... Droplet discharge device, 7 ... Pressurization chamber, 8 ... Inlet port, 8a ... Through hole, 9 ... Discharge port, 9a
..Nozzle, 10 ... Piezoelectric / electrostrictive element, 11 ... Extrusion chamber, 12 ... Reaction tank, 13, 14 ...
15 ... Reactant inlet, 16 ... Outlet.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-40226 (JP, A) JP-A-6-277486 (JP, A) JP-A-6-40030 (JP, A) JP-A-10- 246964 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 2/04 B01J 19/00 B05B 1/00

Claims (4)

(57) [Claims] 1. An inlet for introducing a liquid, and a liquid
A pressure chamber having a discharge port with a discharge chamber for discharging,
The liquid is introduced into the pressurizing chamber and the liquid in the pressurizing chamber is removed.
Pressurizing means for applying intermittent pressure to discharge
The discharge port has a plurality of pressure chambers.
Nozzles are set and all nozzles
In the extrusion chamber where the center of the
Within a concentric area equal to half the radius of the bottom surface
Droplet ejection device connected . 2. The sum of the cross-sectional areas of the nozzle openings is set to be in the range of 1.5 to 0.67 times the opening area of the introduction port, and the introduction port and the discharge port are provided with a liquid flow. The droplet discharge device according to claim 1, wherein the droplet discharge device has a tapered shape in which the cross-sectional area gradually decreases in the direction. 3. The pressurizing chamber has an elongated cavity, and an inlet is provided at the center with respect to the longitudinal direction, and an outlet composed of a plurality of nozzles is provided at both ends. Droplet
Discharge device . 4. The pressurizing chamber comprises an elongated cavity,
The droplet discharge device according to claim 1 or 2, wherein a discharge port having a plurality of nozzles is provided at a central portion with respect to the longitudinal direction, and an introduction port is provided at both end portions.