JP2002181689A - Particle diameter distribution measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle diameter distribution measuring apparatus capable of eliminating bubbles in a flow cell and increasing measuring accuracy irrespective of the diameter of a line forming a flow passage. SOLUTION: The particle diameter distribution measuring apparatus includes a pump 2 for causing circulation of a liquid and the flow cell 5a, both of which are provided within the flow passage 1 through which the liquid circulates; an irradiating portion for irradiating the flow cell 5a with laser beams; and a detector for detecting the beams emitted from the irradiating portion and scattered by particles in the liquid contained in the flow cell 5a. Prior to the measurement of a distribution of particle diameters by the irradiation of the flow cell 5a with the laser beams emitted from the irradiating portion, the flow of the liquid in the flow cell 5a is reversed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a particle size distribution measuring device.

[0002]

2. Description of the Related Art As a conventional particle size distribution measuring device for irradiating a laser beam to particles dispersed in a liquid and obtaining a particle size distribution from light scattered by the particles, the device is provided in a flow path in which the liquid circulates. A pump for circulating the liquid, a supply unit for supplying the liquid to the flow path, an outlet for discharging the liquid in the flow path, and a particle size distribution for particles in the liquid. A measurement unit for obtaining, the measurement unit, a flow cell that can flow the liquid,
Some of these have an irradiation unit for irradiating the flow cell with laser light, and a detector for detecting light scattered by particles in the liquid flowing through the flow cell.

In the above-mentioned conventional particle size distribution measuring apparatus, bubbles attached to the surface of the flow cell cause an error in the measurement of the particle size distribution. The bubble is pushed out from the inside of the flow cell by increasing the flow rate of the liquid as compared with the normal circulation.

[0004]

However, in the conventional particle size distribution measuring apparatus having the above configuration, when the diameter of the pipe forming the flow path is relatively small, the flow rate of the liquid in the pipe is restricted. As a result, the flow rate of the liquid could not be increased sufficiently, so that bubbles in the flow cell were not sufficiently removed, and the measurement accuracy was reduced.

The present invention has been made in consideration of the above-mentioned problems, and has as its object to increase the measurement accuracy regardless of the diameter of a pipe forming a flow path. It is to provide.

[0006]

To achieve the above object, a particle size distribution measuring apparatus according to the present invention is provided with a pump for circulating a liquid and a flow cell in a flow path in which the liquid circulates. An irradiation unit for irradiating the flow cell with laser light; and a detector for detecting light from the irradiation unit scattered by particles in the liquid contained in the flow cell. Before measuring the particle size distribution performed by irradiating the flow cell with a laser beam from the irradiation unit,
The flow of the liquid flowing in the flow cell is configured to be reversed (claim 1).

[0007] With the above configuration, it is possible to provide a particle size distribution measuring apparatus capable of removing bubbles in the flow cell and increasing the measurement accuracy regardless of the diameter of the pipe forming the flow path. Becomes

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a perspective view and an explanatory view schematically showing a configuration of a particle size distribution measuring device D according to a first embodiment of the present invention. The particle size distribution measuring device D
A pump 2 for circulating a liquid (not shown) containing sample particles in a flow path 1 for circulating the liquid,
A supply unit 3 for supplying the liquid to the flow path 1, a discharge unit 4 for discharging the liquid in the flow path 1, and a measurement for obtaining a particle size distribution of sample particles in the liquid A part 5 and an injection part 6 for injecting a diluting liquid (for example, water) for diluting the liquid in the flow path 1 and a cleaning liquid used for cleaning the inside of the flow path 1 into the flow path 1. Have.

The particle size distribution measuring device D irradiates a sample particle dispersed in a liquid with a laser beam and obtains a particle size distribution from a frequency intensity distribution of light scattered by the sample particle. It is a dynamic light scattering type particle size distribution measuring device constructed based on the light scattering theory. In addition,
The particle size distribution measuring device D of the present invention is not limited to a dynamic light scattering type particle size distribution measuring device.

The liquid containing the sample particles includes:
For example, organic pigments, ceramics, abrasives for semiconductor wafers and hard disks, inks for ink jet printers, and the like, each diluted with an appropriate dispersion medium (water, alcohols such as ethanol, etc.) can be used.

In the flow path 1, the supply section 3, the injection section 6, the pump 2, the measurement section 5 and the discharge section 4 are provided in this order. Note that the arrangement of the supply unit 3, the injection unit 6, the pump 2, the measurement unit 5, and the discharge unit 4 in the flow path 1 is not limited to the above, and can be appropriately set.

The pump 2 is in a normal rotation state, a stopped state,
It is configured to take three states of reverse rotation.
When the pump 2 is in the normal rotation state, the circulation of the liquid in the flow path 1 is performed again after the liquid passes through the supply unit 3, the injection unit 6, the pump 2, the measurement unit 5, and the discharge unit 4 in this order. When the pump 2 is in the reverse rotation state, the circulation of the liquid in the flow path 1 is performed by the supply section 3, the discharge section 4, the measurement section 5, and the pump 2. , Through the injecting section 6, a reverse circulation toward the supply section 3 again. In addition, by stopping the pump 2, the circulation of the liquid in the flow path 1 can be stopped.

The supply section 3 comprises, for example, a dispersion bus having an inlet (not shown) for introducing the liquid into the supply section. A dispersing unit for dispersing (stirring) the sample particles in the liquid stored in the supply unit 3 may be provided. Such a dispersing unit may be, for example, a sample in the liquid in the supply unit 3. An ultrasonic bath capable of performing an ultrasonic dispersion process for dispersing particles by ultrasonic waves may be employed as the supply unit 3 or provided by providing a device capable of applying an appropriate impact to the supply unit 3. it can.

The discharge section 4 is connected to a three-way solenoid valve 4a and a flow path 1 via the three-way solenoid valve 4a. A discharge path 4b for discharging the liquid in the flow path 1 to the outside of the flow path 1 is provided. Consists of In the discharge section 4 having such a configuration, the liquid flowing in the flow path 1 can be discharged from the discharge path 4b by switching the three-way solenoid valve 4a. The configuration of the discharge unit 4 is not limited to the above-described one. For example, instead of the three-way solenoid valve 4a, two two-way solenoid valves (not shown) may be used. The two-way solenoid valve may be provided in the discharge path 4b, and the other two-way solenoid valve may be provided in the flow path 1.

The measuring section 5 has a flow cell 5a through which the liquid can flow, an irradiation section (not shown) for irradiating the flow cell 5a with a laser beam, and is housed in the flow cell 5a. A detector (not shown) for detecting light scattered by the sample particles in the liquid.

FIG. 2 is an explanatory view schematically showing the structure of the flow cell 5a. The flow cell 5a includes a cell main body 7 and a cell lid 8 which is detachably provided on the upper part of the cell main body 7.
It is configured such that the thermometer 9 can be inserted therein.
Note that the flow cell 5a is made of a material (for example, glass or the like) through which the laser light from the irradiation unit passes.

The cell body 7 has two ports 7a and 7b at its upper part, which serve as entrances and exits of the liquid into the cell body 7, and each of the ports 7a and 7b has a The space provided toward the bottom communicates near the bottom of the cell body 7. Further, the cell body 7 has a partition 7c protruding downward from between the two mouths 7a and 7b. This partitioning body 7c is formed so as to become thinner from its center to its lower end.
The partition body 7c forms a flow path / space having a substantially U-shaped or substantially V-shaped vertical section in the cell body 7.

The cell lid 8 is provided with the two mouths 7a, 7
b, and an insertion hole 8c for holding the thermometer 9 inserted in the cell main body 7.

The thermometer 9 measures the temperature while immersed in the liquid in the cell body 7, and is arranged at a position where the optical path of the laser beam irradiated toward the cell body 7 is not obstructed. You.

The flow cell 5a having the above configuration is set in the flow path 1 while being held by a cell holder (not shown). When measuring the particle size distribution, the laser beam from the irradiating section is irradiated to an appropriate portion 7d of the cell body 7, and the detector detects the scattered light from the sample particles generated thereby, whereby the particle size is measured. The distribution is measured.

The injection section 6 is connected to the three-way solenoid valve 6a and the flow path 1 through the three-way solenoid valve 6a, and is used to selectively inject the cleaning liquid and the diluting liquid into the flow path 1. And an injection path 6b. An upstream portion of the injection path 6b is provided with a three-way solenoid valve 6c. The three-way solenoid valve 6c includes a cleaning liquid supply path 6d for supplying the cleaning liquid,
A diluent supply path 6e for supplying the diluent is connected.

In the injection section 6 having the above structure,
By appropriately switching the three-way solenoid valves 6a and 6c, the cleaning liquid and the diluting liquid can be selectively injected into the flow path 1. The configuration of the injection unit 6 is not limited to the above-described one. For example, two two-way solenoid valves (not shown) may be used instead of the three-way solenoid valve 6a. The two-way solenoid valve is connected to the injection path 6b.
And the other two-way solenoid valve may be provided in the flow path 1.
Further, two two-way solenoid valves (not shown) may be used in place of the three-way solenoid valve 6c. In this case, one two-way solenoid valve is provided in the cleaning liquid supply path 6d and the other is provided. A two-way solenoid valve may be provided in the diluent supply passage 6e.

Next, the operation of the particle size distribution measuring device D having the above configuration will be described. The particle size distribution measuring device D
In order to perform measurement using a liquid, first, a liquid to be measured is supplied from the supply unit 3 into the flow path 1, and the liquid is normally circulated in the flow path 1 by rotating the pump 2 in a forward rotation state. Let it. When it is necessary to dilute the liquid circulating in the flow path 1, an appropriate amount of the diluent may be injected from the injection section 6.

After the liquid is circulated forward for a predetermined time, the pump 2 is stopped, and then the pump 2 is rotated in the reverse direction. As a result, the liquid circulates backward in the flow path 1. After the liquid is circulated in the reverse direction for a predetermined time, the pump 2 is stopped to stop the circulating liquid in the flow cell 5a of the measuring unit 5. Subsequently, the measuring unit 5 Is measured by the method described above.

At this time, if air bubbles adhere to the inner wall of the cell body 7, the air bubbles scatter the laser light from the irradiating section in the same manner as the sample particles. In other words, in the particle size distribution measuring device D of the present invention, as described above, the flow of the liquid flowing in the flow cell 5a is reversed before the measurement, so that the liquid Make a reciprocating motion, and the bubbles attached to the inner wall of the cell body 7 are stimulated to shake the bubbles, thereby removing the bubbles. Therefore, when laser light is irradiated from the irradiation unit,
The bubbles adhering to the inner wall of the cell body 7 do not scatter the laser light, and only the light scattered from the sample particles floating on the inner wall surface of the cell body 7 is detected by the detector.

In order to enhance the effect of removing air bubbles, the pump 2 is stopped from a normal rotation state, and then stopped after a reverse rotation state.
A series of reversing operations for changing the liquid circulating normally in the flow path 1 to reverse circulation may be repeated not only once but also several times to several tens of times. In this case, the liquid in the flow path 1 also repeats the normal circulation and the reverse circulation, whereby it is possible to remove the air bubbles firmly attached to the flow cell 5a.

In the above series of reversing operations, the time during which the pump 2 is kept in the normal rotation state, the stopped state, and the reverse rotation state can be appropriately adjusted according to conditions such as the viscosity of the liquid. is there. For example, when the liquid is ethylene glycol whose viscosity is nearly 20 times higher than that of water, the flow rate of the liquid in the pipe forming the flow path 1 becomes small. If the time for the reverse rotation state is set to be long, and the normal circulation and the reverse circulation of the liquid in the flow path 1 are surely performed, the effect of removing the bubbles in the flow cell 5a is sufficiently achieved. Can be obtained.

It should be noted that the time during which the pump 2 is stopped before the pump 2 is reversed from the normal rotation state to the reverse rotation state and before the pump 2 is reversed from the reverse rotation state to the normal rotation state should be as short as possible. Preferably, the pump 2
It is desirable that the switching between the normal rotation state and the stop state and the switching between the reverse rotation state and the stop state be performed suddenly and instantaneously. By performing the operation as described above, the shaking of the bubbles in the flow cell 5a becomes more effective, and the efficiency of removing the bubbles increases.

When the predetermined measurement in the measuring section 5 is completed and the liquid in the flow path 1 becomes unnecessary, the liquid in the flow path 1 may be discharged from the discharge section 4. Then, if it is necessary to clean the inside of the flow path 1,
Subsequently, the cleaning liquid may be injected into the flow path 1 from the injection section 6, the cleaning liquid may be circulated in the flow path 1 by the pump 2, and finally the used cleaning liquid may be discharged from the discharge section 4.

When the washing is performed by circulating the washing liquid in the flow path 1, the washing effect can be improved by performing a series of reversing operations performed before the measurement in the same manner.

The particle size distribution measuring device D having the above-mentioned configuration
Removes air bubbles in the flow cell 5a of the measuring unit 5,
Unlike the conventional particle size distribution measuring device, the flow rate of the liquid flowing in the flow path 1 is not increased but the circulation of the liquid flowing in the flow path 1 is reversed. The air bubbles in the flow cell 5a can be reliably removed without limiting the diameter of the pipe forming the pipe 1, and the measurement accuracy can be increased.

Further, in the particle size distribution measuring apparatus D having the above-described configuration, it is necessary to confirm whether or not air bubbles are adhered to the inner wall of the flow cell 5a at the time of measurement by reliably removing the air bubbles in the flow cell 5a. Since there is no such a process, it is very important to enable the automatic (unmanned) operation to perform the steps from the supply of the liquid to the flow path 1 to the cleaning of the flow path 1 through the measurement as described above and the repetition of this step. Are suitable.

[0033]

As described above, according to the present invention having the above-described structure, air bubbles in the flow cell are removed and measurement accuracy is increased regardless of the diameter of the pipe forming the flow path. It is possible to provide a particle size distribution measuring device that can perform the measurement.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a configuration of a particle size distribution measuring apparatus according to one embodiment of the present invention.

FIG. 2 is an explanatory view schematically showing a configuration of a flow cell in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flow path, 2 ... Pump, 5a ... Flow cell, D ... Particle size distribution measuring device.

Claims (1)

[Claims] A pump for circulating the liquid and a flow cell provided in a flow path in which the liquid circulates, an irradiation unit for irradiating the flow cell with laser light, and the flow cell A particle size distribution measuring device having a detector for detecting light from the irradiation unit scattered by particles in the liquid contained in the liquid cell, wherein the flow cell emits laser light from the irradiation unit. A particle size distribution measuring device configured to reverse the flow of the liquid flowing in the flow cell before measuring the particle size distribution performed by irradiating the particle size distribution.