JP7079058B2 - Dropping device and method - Google Patents

Description

The present invention relates to a liquid dropping device and a method thereof.

There are many industrial examples of the process of dropping a liquid in the form of droplets. For example, a step of dropping a liquid crystal onto a liquid crystal panel, a step of dropping and drying a liquid containing a chemical to form granules, a step of dropping a high-viscosity coating agent dissolved in a solvent on a semiconductor wafer and applying it with a spinner, a silicic acid. There is a step of dropping an alkaline aqueous solution into an acidic solution to obtain precipitated silica.

In these steps, the dropping device is required to be able to quantitatively control the dropping amount and to prevent dripping and stringing when the liquid is stopped. Further, from the viewpoint of cost, it is desired to simplify the mechanism, such as enabling dropping from a plurality of nozzles with one liquid supply mechanism. For example, the method of dropping from a tube using a tube pump is highly quantitative, but is not suitable for industrial use because it requires one liquid supply mechanism for each tube.

In Patent Document 1, a sealed tank is filled with a highly viscous coating agent, which is turned upside down, and the opening / closing control is performed by a solenoid valve to perform dripping by gravity to prevent residual liquid from remaining in the piping. A dropping device capable of is described. Patent Document 2 describes a dropping device capable of preventing thread pulling from a nozzle by attaching a high-pressure air injection device inside the nozzle. Patent Document 3 describes a dropping device capable of highly quantitative dropping only by gravity without the need for a liquid feeding mechanism, so that the liquid level in the tank is always kept at a constant height by devising a structure. Have been described.

Japanese Unexamined Patent Publication No. 05-138101 Japanese Unexamined Patent Publication No. 54-058360 Japanese Unexamined Patent Publication No. 11-15617

In all of Patent Documents 1 to 3, a relatively simple mechanism enables highly quantitative dropping, and does not leave residual liquid in the pipe. On the other hand, when used industrially, there are the following problems. Since the dropping device described in Patent Document 1 needs to control the opening and closing of each nozzle by a solenoid valve, it is economically disadvantageous when it is desired to drop from a large number of nozzles at the same time. Although the dropping device described in Patent Document 2 is difficult to drip, it has a complicated mechanism in a thin nozzle portion, and maintenance is difficult when a highly viscous liquid solidifies in the nozzle. The dropping device described in Patent Document 3 has difficulty in quantification because the dropping speed depends on the mechanical structure of the device, and it is difficult to evenly drop from a plurality of nozzles.

In addition, as a method capable of dropping from a plurality of nozzles, there is a method of supplying a liquid under pressure and branching it to each nozzle. In order to drip in the form of droplets by this method, it is necessary to operate with the degree of pressurization suppressed to a low level so that the liquid does not become a jet state, or to operate with a small nozzle diameter. However, when operating under a slight pressurization, it is difficult to control the pressure so as to keep the dropping amount constant, and when the nozzle diameter is reduced, it is very difficult to remove the clogging when the liquid solidifies in the nozzle.

The present invention has been made in view of such circumstances, and is a dropping device that can easily perform quantitative and uniform dropping from a plurality of nozzles without requiring a complicated mechanism, and is easy to maintain. And to provide a method for it.

(1) In order to achieve the above object, the dropping device of the present invention is a dropping device that drops a liquid from a plurality of nozzles, and is arranged on a storage tank for storing the liquid and a bottom surface of the storage tank. The storage tank comprises a plurality of the nozzles, a liquid supply unit for supplying the liquid to the storage tank, and an air vent valve arranged on a facing surface of a bottom surface on which the nozzles are arranged. It is characterized in that it is sealed by closing the nozzle, the liquid supply unit, and the air vent valve.

In this way, by making the storage tank a dripping device that is sealed by closing a plurality of nozzles, a liquid supply unit, and an air bleeding valve, the dripping speed can be controlled by the balance of the force due to the vacuum, and each nozzle. Quantitative and uniform dropping can be done. In addition, it can be a dropping device having a simple structure, which facilitates maintenance.

(2) Further, in the dropping device of the present invention, the plurality of nozzles are characterized in that the diameter of the narrowest portion is 1.2 mm or more and 4.0 mm or less. This makes maintenance easier because the nozzle diameter is large enough.

(3) Further, in the dropping device of the present invention, the plurality of nozzles are characterized in that the length is 50 mm or less. This makes maintenance easier because the nozzle length is not too long.

(4) Further, the method of the present invention is a liquid dropping method applied to a dropping device in which a storage tank is closed by closing a plurality of nozzles, a liquid supply unit, and an air bleeding valve, and is in a closed state. A step of supplying the liquid having a viscosity of 1 cp or more and 1000 cp or less from the liquid supply unit, discharging the air from the air bleeding valve, and storing the liquid in the storage tank in which the plurality of nozzles are closed, and the air bleeding. A step of closing the valve, a step of opening the plurality of nozzles and waiting until the discharge of the liquid from the plurality of nozzles naturally stops, and a step of waiting from the liquid supply unit to the storage tank. It is characterized by including a step of adjusting and supplying the liquid according to the number of nozzles and the amount of the liquid dripping from each of the nozzles. As a result, the dropping speed can be controlled by the balance of the force due to the vacuum, and quantitative and uniform dropping can be performed from each nozzle.

The dropping device and its method of the present invention can drop highly quantitatively from a plurality of nozzles without requiring a complicated mechanism, and may also drop a highly viscous liquid or a liquid that easily solidifies. However, the nozzle is less likely to be blocked and maintenance can be easily performed.

It is a conceptual diagram which shows the schematic structure of the dropping device which concerns on this embodiment. It is a graph which showed the relationship between the dropping amount and time of each group when the liquid supply amount of the dropping device of an Example was made constant, and the nozzles were divided into groups. It is a graph which showed the relationship between the dropping amount and time for each liquid supply amount when the liquid supply amount of the dropping device of an Example is changed.

As a result of diligent research, the present inventors have made the storage tank of the dropping device a closed state by closing a plurality of nozzles, a liquid supply unit, and an air vent valve, and the dropping speed is balanced by the force of vacuum. By controlling the above, it was found that quantitative and uniform dropping can be performed from each nozzle, a dropping device having a simple structure can be obtained, and maintenance can be facilitated, and the present invention has been completed. Hereinafter, embodiments of the present invention will be described.

[Structure of dropping device]
FIG. 1 is a conceptual diagram showing a schematic configuration of a dropping device according to the present embodiment. The dropping device 1 according to the present embodiment includes a storage tank 3, a nozzle 5, a liquid supply unit 7, and an air bleeding valve 9.

The storage tank 3 stores the liquid to be dropped. The storage tank 3 is sealed by closing the nozzle 5, the liquid supply unit 7, and the air vent valve 9. In this way, by forming the storage tank 3 in a structure that is sealed by closing the nozzle 5, the liquid supply unit 7, and the air vent valve 9, it is possible to control the dropping speed by balancing the force due to the vacuum. It becomes. The principle will be described later. Since the storage tank 3 is subjected to pressure due to atmospheric pressure, it is preferable that the storage tank 3 is made of a material that does not easily deform. For example, it can be made of copper, iron, stainless steel, ceramics, or the like.

The nozzle 5 is provided in the storage tank 3, and droplets of the liquid stored in the storage tank 3 are discharged. A plurality of nozzles 5 are provided. The plurality of nozzles 5 are provided at positions where the distances from the liquid level of the liquid stored in the storage tank 3 when generating the droplets are substantially the same in order to perform quantitative and uniform dropping from each nozzle 5. It is preferable to be. For example, when the storage tank 3 has a bottom surface parallel to the liquid surface, it is convenient to provide the plurality of nozzles 5 on the bottom surface. Further, it can be provided at a position on the side surface of the storage tank 3 having substantially the same distance from the liquid level.

It is preferable that the diameter (nozzle diameter) of the narrowest portion of the nozzle 5 is 1.2 mm or more and 4.0 mm or less. The shape of the hole of the nozzle 5 may be an ellipse, a regular polygon, or the like in addition to the circular shape, but the circular shape is preferable in consideration of maintainability. The nozzle diameter is the inner diameter of the nozzle 5, and is the diameter when the shape of the hole of the nozzle 5 is circular, the major diameter when it is an ellipse, and the maximum length passing through the center when it is a regular polygon. Further, the nozzle 5 preferably has a length of 50 mm or less. If the nozzle diameter is smaller than 1.2 mm or the nozzle length is longer than 50 mm, maintainability may deteriorate. Further, if the nozzle diameter is larger than 4.0 mm, air tends to enter the storage tank 3 through the nozzle 5, and the vacuum state may easily collapse. Further, it is preferable that the plurality of nozzles 5 have the same nozzle diameter, nozzle length, and nozzle shape in order to perform quantitative and uniform dropping from each nozzle 5.

The nozzle diameter, nozzle length, and nozzle shape may be adjustable according to the viscosity of the stored liquid and the size of the generated droplets. As the shape of the nozzle, for example, one having a cylindrical tip or one having a tapered tip can be used. Further, for example, by mounting an auxiliary nozzle made of resin or the like on a convex nozzle 5 having a hole in the center formed in the storage tank 3, the nozzle diameter and the length of the nozzle are increased for each auxiliary nozzle to be mounted. And the shape of the nozzle may be adjusted.

The number of nozzles 5 has an upper limit depending on the size of the storage tank 3 and the nozzles 5, but from the viewpoint of improving the efficiency of droplet generation, and due to the solidification of some nozzles 5 during the generation of droplets, etc. A large number is preferable from the viewpoint of making it difficult to affect the quantitativeness of the droplets generated from the other nozzles 5 when the nozzles are closed. For example, when one of the n nozzles is blocked and the amount of liquid supplied from the liquid supply unit 7 to the storage tank 3 is not changed, the droplets generated from the remaining n-1 nozzles 5 are generated. The amount is n / (n-1) times higher than that before occlusion. Therefore, the larger n is, the smaller the influence is.

The liquid supply unit 7 is provided in the storage tank 3 and supplies the liquid to the storage tank 3. It is preferable that the liquid supply unit 7 has a structure capable of supplying a liquid having excellent quantification and preventing air or the like other than the liquid supplied at the time of liquid supply from being mixed. For example, a tube pump, a diaphragm pump, or the like can be used. By adjusting and supplying the liquid from the liquid supply unit 7 according to the number of the plurality of nozzles 5 and the amount of the liquid to be dropped from each nozzle 5, quantitative and uniform dropping can be performed from each nozzle 5.

The air bleeding valve 9 is opened when the liquid is supplied to the storage tank 3 to bleed the air in the storage tank 3. Further, the air vent valve 9 is closed during the generation of droplets. Further, the air bleeding valve 9 can be opened after the generation of the droplets is completed, so that the liquid remaining in the storage tank 3 can be discharged from the nozzle 5. A valve for draining liquid may be separately provided in the storage tank 3 and discharged through the valve.

[Dripping method and principle using a dropping device]
Next, the dropping method using the dropping device and its principle will be described. Here, the method using the dropping device of FIG. 1 will be described, but the scope of the invention is not limited to this.

(1) Preparation for operation First, the air bleeding valve 9 is opened, the liquid to be the material of the droplet is supplied from the liquid supply unit 7 with the caps on each of the nozzles 5, and the storage tank 3 is filled with the liquid.

After that, the air vent valve 9 is closed, and all the caps of the nozzle 5 are removed. Then, the liquid is discharged from each nozzle 5, and the liquid level of the stored liquid 11 is lowered. The liquid discharged here is not used as droplets.

As the liquid level of the stored liquid 11 decreases, the volume of the space 13 in the tank increases. Since the liquid drops from the state of being filled with the liquid (the state where there is almost no space 13) and the space 13 expands without changing the amount of gas, the space 13 is in a low vacuum state.

As the liquid is discharged, an upward force due to a low vacuum and a downward force due to the weight of the liquid are applied to the liquid, and both are balanced to stop the discharge of the liquid.

(2) Operation The liquid is supplied from the liquid supply unit 7 at the speed (total of all nozzles) to be dropped. Then, the weight of the liquid increases, and the liquid is dropped from the nozzle 5 as droplets 15 by the amount supplied.

(3) Stop When the air bleeding valve 9 is opened, the entire amount of the liquid is discharged through the nozzle 5. The liquid discharged here is not used as droplets, but is received by other containers. Alternatively, a valve for draining liquid may be provided at the bottom of the device and drained through the valve.

(Supplement to the principle)
In this dropping device, the dropping speed is controlled by balancing the upward force due to the vacuum and the downward force due to the weight of the liquid itself. If it is open to the atmosphere, the dropping speed is controlled by the weight of the liquid and the friction between the liquid and the nozzle. In this case, the height of the liquid with respect to the nozzle changes with a slight tilt, so the downward force applied to the liquid. Is not uniform, and it is extremely difficult to drip evenly from all nozzles. This phenomenon can be alleviated to some extent by increasing the friction between the liquid and the nozzle by making the nozzle elongated, but making the nozzle elongated leads to difficulty in maintenance.

Further, when the storage tank is pressurized, the problem that the amount of liquid varies from nozzle to nozzle can be alleviated, but it becomes necessary to further increase the friction between the liquid and the nozzle, which also deteriorates maintainability.

In the dropping device of the present invention, the balance of the force due to the vacuum is utilized for adjusting the flow rate instead of the friction between the liquid and the nozzle. As a result, the nozzle diameter can be increased to several mm, and the structure has excellent maintainability. However, it can be dropped with good quantitativeness. In addition, since the liquid level is high, the allowable range for the inclination of the device is much wider than that in the case of opening to the atmosphere.

In addition, since the dropping device of the present invention adjusts the flow rate by adjusting the force by vacuum, the dropping flow rate can be controlled by the amount of liquid supplied into the device regardless of the viscosity. It can be applied to a wide range of liquids up to 1000 cp. Further, since this feature is advantageous in dropping a high-viscosity solution, the viscosity of the liquid dropped by the apparatus of the present invention is particularly suitable for dropping a relatively high-viscosity liquid of about 50 to 750 cp. For a liquid having a viscosity higher than this, the contribution of friction between the nozzle and the liquid in the balance of forces becomes relatively large, and the dropping becomes unstable.

Further, in the dropping device of the present invention, it is easy to obtain a large amount of droplets having little variation in mass, volume, shape, etc. from a plurality of nozzles, so that the droplet itself becomes a product or a material of the product, and a large amount thereof is used. It is suitably used in the process of dropping in the production of what needs to be produced. For example, it is suitably used in a drug manufacturing step of dropping and drying a liquid containing a drug to form granules, a silica manufacturing step of dropping an alkaline silicate aqueous solution into an acidic solution to obtain precipitated silica, and the like. By using it in such a manufacturing process, it is possible to obtain a granular or powdery product or a material for the product in a short time and at low cost.

[Example]
Examples of applying the present invention will be described below, but the present invention is not limited to the dropping device of the embodiment and its use. 36 nozzles with a diameter of 2 mm and a length of 15 mm (arranged in a 6 x 6 grid with a gap of 30 mm from each other) at the bottom of a rectangular parallelepiped storage tank with a bottom surface of 200 x 200 mm and a height of 100 mm, and a liquid injection port at the top. A dropping device equipped with a (liquid supply unit) and an air vent valve was manufactured. The material was stainless steel. Using this dropping device, the following experiments were performed in a room at room temperature of 25 ° C. and humidity of 60%.

First, the nozzle of this device was capped, the air vent valve was opened, and then soda No. 3 silicate (viscosity 370 cp) was injected from the liquid injection port until the water was full. After that, the air vent valve was closed, the cap was removed, and the liquid was waited until the discharge stopped.

(Test 1)
This device was fixed so that the bottom surface was horizontal, and four saucers (called A to D) were installed under the dropping device so that droplets from nine nozzles could be received.

When the tube pump was operated and the No. 3 sodium silicate was introduced into the dropping device, the No. 3 sodium silicate was dropped from all the nozzles.

The flow rate of the tube pump was set to 150 mL / min, and the operation was performed for 1 minute, 5 minutes, and 10 minutes, and the weight of the saucer before and after the operation was measured to measure the amount of the dropped liquid. FIG. 2 is a graph showing the result. The horizontal axis plots the operating time, and the vertical axis plots the amount of liquid in each saucer.

The amount of dropping increased in proportion to the dropping time, and the dropping amount was uniformly dropped on each saucer. From this, it was found that dropping was uniformly performed from each nozzle regardless of the operating time.

(Test 2)
In addition, the flow rate of the tube pump was changed to 30 mL / min, 60 mL / min, 150 mL / min, and 300 mL / min, and the operation was performed for 1 minute, 5 minutes, and 10 minutes, and the weight of the saucer A before and after the operation was measured and dropped. The amount of liquid that was added was measured. FIG. 3 is a graph showing the result.

It was found that the dropping amount was proportional to the dropping time in any of the dropping amounts, and that quantitative dropping was possible in a wide dropping amount range.

(Test 3)
After use, a 10% caustic soda solution (viscosity 3.2 cp) was added dropwise at a rate of 150 mL / min for 15 minutes in the same manner, followed by tap water at a rate of 150 mL / min for 15 minutes. The dropping device was washed. After 24 hours, the dropping experiment of No. 3 sodium silicate was performed again, but the same result was obtained, and no residue or solidification of No. 3 sodium silicate inside the dropping device was observed. Therefore, it was found that maintenance was easy.

In addition, the same test as in Test 1 was separately performed on the 10% caustic soda solution and clean water. In each case, the dropping amount increased in proportion to the dropping time, and the dropping amount was uniformly dropped on each saucer. From this, it was found that the dropping device of the present invention can uniformly drop from each nozzle regardless of the viscosity of the liquid.

From the above results, the dropping device of the present invention is a dropping device having excellent maintainability because it can uniformly drop from a plurality of nozzles with a simple mechanism and has a large nozzle diameter and is easy to clean.

1 Drop device 3 Storage tank 5 Nozzle 7 Liquid supply unit 9 Air bleeding valve 11 Stored liquid 13 Space in the tank 15 Dropped liquid (droplet)
17 Liquid to be supplied

Claims (4)

A dripping device that drips liquid from multiple nozzles.
A storage tank for storing the liquid and
A plurality of the nozzles arranged on the bottom surface of the storage tank,
A liquid supply unit that supplies the liquid to the storage tank,
A valve for bleeding air, which is arranged on the facing surface of the bottom surface on which the nozzle is arranged, is provided.
The storage tank is sealed by closing the plurality of nozzles, the liquid supply unit, and the air vent valve .
The liquid supply unit is in a low vacuum state in which the liquid is stored in the storage tank, the liquid supply unit and the air vent valve are closed, and the liquid is not naturally discharged in a state where the plurality of nozzles are released downward. The dropping device is characterized in that the liquid can be supplied to the storage tank at a supply amount of a predetermined speed, and droplets corresponding to the supply amount are dropped from the plurality of nozzles . The dropping device according to claim 1, wherein the plurality of nozzles have a diameter of the narrowest portion of 1.2 mm or more and 4.0 mm or less. The dropping device according to claim 1 or 2, wherein the plurality of nozzles have a length of 50 mm or less. A method of dripping liquid applied to a dripping device in which a storage tank is sealed by closing a plurality of nozzles, a liquid supply unit, and an air bleeding valve.
A step of supplying the liquid having a viscosity of 1 cp or more and 1000 cp or less from the liquid supply unit, discharging the air from the air vent valve, and storing the liquid in the storage tank in which the plurality of nozzles are closed.
The process of closing the air vent valve and
A step of opening the plurality of nozzles and waiting until the discharge of the liquid from the plurality of nozzles naturally stops.
A method comprising a step of adjusting and supplying the liquid from the liquid supply unit to the storage tank according to the number of the plurality of nozzles and the amount of the liquid dripping from each nozzle.

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