JP2001083074A - Grain diameter distribution measuring device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grain diameter distribution measuring device and method, capable of switching between, when directly and accurately measuring temperature data at measurement and when substituting indirectly measured temperature, such as the temperature of a holder for simplicity of measurements and using the temperature data for computing a grain diameter distribution. SOLUTION: In this grain diameter distribution measuring device 1, a scattering light generated by irradiating samples to be measured 3 and 4 with a laser beam 6 is converted into electrical detecting signals, and grain diameter distribution F(D) of grains 4 contained in the samples to be measured 3 and 4 are computed by performing the inverse computations on the detection signals. The measuring device 1 comprises an external temperature sensor 15b, mounted to a holder 2b to hold the samples 3 and 4 to be measured for measuring the temperatures T of the samples to be measured 3 and 4 for measuring the their temperatures indirectly, an internal temperature sensor 15a to measure directly the temperatures of the samples to be measured 3 and 4, is capable of selecting the temperature sensor to be used according to the samples to be measured 3 and 4, and comprises a computation processing part 17 to perform the inverse computation for the grain diameter distributions F(D) by substituting the temperature T of the samples to be measured 3 and 4 measured by the selected temperature sensor into the Stokes-Einstein equation and obtaining the response function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle size distribution measuring apparatus and a particle size distribution measuring method utilizing dynamic light scattering.

[0002]

2. Description of the Related Art Recently, a particle size distribution measuring device for measuring the particle size distribution of particles dispersed in a dispersion medium of a sample to be measured has been proposed. That is, the particle size distribution measuring device irradiates a laser beam of a specific wavelength to the sample to be measured, and makes the scattered light scattered on the particles incident on the detector. At this time, the interference light of the scattered light generated by the Doppler shift of the laser light applied to the particles performing the Brownian motion is detected, and the detection signal of the diffused light is subjected to the Fourier transform to analyze the frequency, thereby obtaining the frequency of the measured light intensity. Characteristics can be determined. Then, it has been proposed to measure the particle size distribution from the frequency characteristics of the light intensity.

[0003]

However, in order to obtain the particle size distribution from the frequency characteristics, it is necessary to perform complicated arithmetic processing, which requires a high-performance computer. In addition, the calculation result may diverge, and the particle size distribution may not be obtained. Therefore, in order to obtain the particle size distribution from the frequency characteristics, it is conceivable to convert the frequency characteristics into the form of convolution integral and deconvolve it, or to obtain the particle size distribution using a shift variant response function. However, this method inevitably reduces the analytical accuracy.

Accordingly, the present applicant has filed a statement on October 30, 1998.
As of the date, “Particle size distribution analysis method” (Japanese Patent Application No. 10-31)
0063). By using this particle size distribution analysis method, a simple repetitive calculation can be performed, and the particle size distribution can be obtained by inversely calculating the particle size distribution from the Fredholm integral equation of the first kind. Further, by adjusting the response function used in the process of the inverse operation to various conditions at the time of measurement, a more accurate particle size distribution can be measured.

Here, in order to make the particle size distribution obtained by the inverse calculation more accurate, various conditions such as the temperature and the viscosity coefficient of the sample at the time of the measurement are set as accurate parameters by the user before the measurement. It is important to input, but there is also a problem that this input operation is troublesome. The viscosity coefficient changes with a predetermined relationship with temperature depending on the type of the dispersion medium (solvent) of the sample to be measured. To measure the particle size distribution accurately, the temperature must be measured accurately. That was important.

As a method of measuring the temperature of a sample to be measured, generally, the temperature is indirectly measured by attaching the sample to a metal or immersion bath type holder (cell holder) which holds a cell containing the sample to be measured. That was being done. However, in this method, a difference often occurs between the temperature of the cell holder and the liquid temperature of the sample to be measured, and this may cause a measurement error. In particular, when the measurement is started immediately after a high-temperature or low-temperature sample to be measured is placed in the cell, the difference becomes large and a large error may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to directly and accurately measure temperature data at the time of measurement, which is indispensable for calculating the particle size distribution. A particle size distribution measuring device and a particle size measurement method that can switch between the case and the case where an indirectly measured temperature such as the temperature of a holder is substituted for simplicity of measurement, and use the temperature data for calculating the particle size distribution. An object of the present invention is to provide a method for measuring a diameter distribution.

[0008]

In order to achieve the above object, a particle size distribution measuring apparatus according to a first aspect of the present invention irradiates a sample to be measured with laser light and converts scattered light generated into an electrical detection signal. Then, in the particle size distribution measuring device for calculating the particle size distribution of the particles contained in the sample by performing an inverse operation of the detection signal, attached to a holder holding the sample to be measured in order to measure the temperature of the sample to be measured. An external temperature sensor that indirectly measures the temperature, and an internal temperature sensor that directly measures the temperature of the sample to be measured, allowing the temperature sensor to be used according to the sample to be measured to be selectable and selected It is characterized by having an arithmetic processing unit for performing the inverse calculation of the particle size distribution by substituting the temperature of the sample to be measured measured by the temperature sensor into the Stokes-Einstein equation to obtain a response function.

Therefore, according to the first aspect, the user can switch between performing the temperature measurement directly and indirectly in consideration of the required accuracy and the like according to the sample to be measured. That is, when accuracy is required, the use of an internal temperature sensor that directly measures the liquid temperature of the sample to be measured can prevent a temperature error from occurring, and can provide a highly accurate particle size distribution. In addition, the measurement can be simplified by using an external temperature sensor for a measurement target sample that is less affected by temperature and a measurement target sample that does not require much accuracy. In other words, it is possible to have both a function of obtaining a particle size distribution as accurate as possible, preventing a distribution failure due to a calculation error and an error, and a function of performing a simpler measurement.

[0010] The applicant of the present invention filed on October 30, 1998, "Method of analyzing particle size distribution" (Japanese Patent Application No. 10-3099).
No. 78: hereinafter referred to as the invention of the prior application), and by inputting calculation parameters in accordance with various conditions at the time of measurement,
We propose a new analysis method to analyze the particle size distribution using the theoretical formula. That is, since the temperature data measured by the present invention is accurately input as the calculation parameter, the analysis of the particle size distribution proposed in the invention of the prior application can be performed with higher accuracy.

A particle size distribution measuring apparatus according to a second aspect of the present invention irradiates a sample to be measured with laser light, converts scattered light generated into an electrical detection signal, and inversely operates the detection signal to obtain a sample. In a particle size distribution measuring device for calculating a particle size distribution of contained particles, an optical fiber for guiding and irradiating the laser light to a sample to be measured and guiding light scattered by the particles to a detector, and a laser light emitting end of the optical fiber Having a temperature sensor attached to the side to directly measure the temperature of the sample to be measured, and substituting the temperature of the sample to be measured measured by the temperature sensor into the Stokes-Einstein equation to obtain a response function And an arithmetic processing unit for performing an inverse calculation of the particle size distribution.

Therefore, according to the second aspect of the present invention, the particle size distribution can be measured without removing the sample to be measured from the container only by immersing the tip of the optical fiber in the sample to be measured stored in an arbitrary container. Easy to handle. Further, since the temperature sensor is attached to the laser light emitting end side of the optical fiber, it is possible to measure the actually measured temperature of a portion closer to the measurement point, and to calculate the particle size distribution more accurately.

Further, in the particle size distribution measuring method of the present invention, a sample to be measured is irradiated with laser light, the generated scattered light is converted into an electrical detection signal, and the detection signal is inversely calculated and included in the sample. In the particle size distribution measuring method for calculating the particle size distribution of particles to be measured, whether to use an internal temperature sensor for directly measuring the temperature or an external temperature sensor for indirectly measuring the temperature according to the sample to be measured After selecting, the temperature of the sample to be measured is measured by the selected temperature sensor at the time of measurement, and the measured temperature is substituted into the Stokes-Einstein equation to obtain a response function, thereby performing an inverse calculation of the particle size distribution. It is characterized by:

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram schematically showing a configuration of a dynamic light diffusion type particle size distribution measuring device which is a particle size distribution measuring device of the present invention. In FIG. 1, reference numeral 1 denotes a measuring unit, which is configured as follows, for example. That is, 2 is a cell containing a solvent 3 and particles (sample) 4 to be measured, and 5 is a particle 4
Is a light source for irradiating the laser beam 6 to the cell 2, and 7 is a
It is a lens that focuses light inside.

Reference numeral 8 denotes a beam splitter (or a laser beam 6) that reflects interference light 9 generated by light scattered by the particles 4.
, A reflecting mirror provided with a transmission hole), a lens 10 for condensing the interference light 9, and a detector 11 for converting the interference light 9 into an electric detection signal. Reference numeral 12 denotes an amplifier for amplifying the detection signal, reference numeral 13 denotes a filter, and reference numeral 14 denotes an AD converter for converting the detection signal into a digital signal.

In addition, reference numeral 15 denotes a temperature measuring unit for measuring the temperature of the samples 3 and 4 stored in the cell 2;
An internal temperature sensor 15a for directly measuring the temperature of the sample, an external temperature sensor 15b for indirectly measuring the temperatures of the samples 3 and 4, and a thermometer circuit connected to these temperature sensors 15a and 15b to output the temperature data T The temperature data from the temperature sensor 15 is also converted into a digital signal by the AD converter 14.

FIG. 2 is a horizontal sectional view for clarifying the arrangement of the temperature measuring section 15. As shown in FIGS. 1 and 2, the internal temperature sensor 15 a in this example is attached to the lid 2 a of the cell 2, and measures the temperature in a state where the internal temperature sensor 15 a is immersed in the samples 3 and 4 in the cell 2. The internal temperature sensor 15a is disposed at a corner of the cell 2 so as not to obstruct the optical path of the laser beam 6 passing through the cell 2. However, the present invention is not limited to the arrangement position and mounting of the internal temperature sensor 15a. It does not limit the method.

In this embodiment, the internal temperature sensor 15a is a contact-type temperature sensor such as a thermocouple, thereby enabling more accurate temperature measurement. However, the present invention is not limited to this. is not. That is, the internal temperature sensor 15b may be formed by a non-contact radiation thermometer that measures the temperature by radiating infrared rays. in this case,
Since it is not necessary to clean the internal temperature sensor 15a every time the measurement is performed, the particle size distribution can be measured more easily.

Further, by providing a radiation thermometer separately from the contact-type temperature sensor 15a, the temperature of the samples 3 and 4 measured by the radiation thermometer can be used to determine the temperature measured by the external temperature sensor 15b and the temperature of the samples 3 and 4. It may be possible to detect that a difference has occurred in the actual temperature of the data. That is, various modifications can be considered, such as using the measurement of the temperature of the samples 3 and 4 by the radiation thermometer as a criterion for determining whether or not the internal temperature sensor 15a needs to be used.

The external temperature sensor 15b is buried and attached to the outside of the cell 2 in a metal cell holder 2b for holding the cell, and indirectly measures the temperatures of the samples 3 and 4 based on the temperature of the cell holder 2b. I do. However, the present invention does not limit the shape of the cell holder 2b, and may adjust the temperature of the samples 3 and 4 via the liquid while the cell 2 is immersed in the liquid. In this case, the external temperature sensor 15b can be attached to the cell holder 2b so as to be immersed in the liquid together with the cell 2.

In this embodiment, the cell holder 2b adjusts the temperature of the samples 3 and 4 in the cell 2, and includes a heater and an electronic cooler (not shown). That is, the external temperature sensor 15b constantly measures the temperature of the holder 2b, and the temperature is adjusted so that the temperature measured by the external temperature sensor 15b is constant. Then, the cell 2 is inserted into the holder 2b whose temperature has been adjusted.

In such a case, the external temperature sensor 1 is temporarily set according to the temperatures of the samples 3 and 4 to be measured in the cell 2.
It is conceivable that the detected temperature data T by 5b fluctuates. Therefore, when this temperature fluctuation is severe, the cell 2
This indicates that there is a difference between the temperature of the measurement target samples 3 and 4 and the temperature of the holder 2b, so that the particle size distribution measurement device 1 uses the internal temperature sensor 15a for the user. You may be prompted. Alternatively, the user may be prompted to wait for the measurement of the interference light 9 until the temperature change has calmed down.

Reference numeral 16 denotes a measurement control unit which controls the entire apparatus including the measurement unit 1 and performs various calculations.
For example, it consists of a personal computer. The personal computer 16 has a storage section such as a memory 18 and a hard disk 19 and an input / output section such as a display section 20 and a keyboard 21 in addition to a CPU 17 (calculation processing section) for performing calculation processing.

The memory 18 and the hard disk 1
Reference numeral 9 stores an analysis program for obtaining a particle size distribution from the detection signal and data on a viscosity coefficient and a refractive index corresponding to the type of the solvent. Note that the method of analyzing the particle size distribution by this analysis program uses the method shown in the invention of the prior application, and thus the details are omitted.

In the dynamic light scattering type particle size distribution measuring apparatus having the above configuration, the laser beam 6 emitted from the light source 5 passes through the beam splitter 8 and the lens 7 and is condensed in the cell 2. At this time, the laser light 6 hits the particles 3 which are dispersed in the solvent 3 and which undergoes Brownian motion, and scatters light which has been Doppler shifted by the Brownian motion of the particles 3. The interference light 9 is generated by the Doppler-shifted scattered light, and the interference light 9 is detected by the detector 11. The interference light 9
May be caused by interference between scattered lights or by scattered light and non-scattered light.

During the measurement of the interference light 9, the temperature data T is also taken in by the temperature measuring section 15. Then, the detection signal of the interference light 9 detected by the detector 11 and the samples 3 and 4 measured by the temperature measurement unit 15
Is converted into a digital signal by the AD converter 14 and input to the personal computer 16. Then, the personal computer 16 converts the detection signal of the interference light 9 into a power spectrum, and calculates the average value of the power spectrum from the detection signal of the interference light 9 measured during a certain measurement time to thereby reduce the influence of noise. Perform analysis with less

The average value Ta, the maximum value Tmx, and the minimum value Tmn of the temperature data T captured during the measurement time are obtained. The personal computer 16 uses the average temperature Ta (average temperature) to store information such as the average temperature Ta of the samples 3 and 4 at the time of measurement and the type of the solvent 3 in the memory 18.
And the data stored in the hard disk 19 to calculate various parameters η and T such as the viscosity coefficient and the temperature of the solvent 3 at the time of measurement.

That is, the personal computer 16 determines the viscosity coefficient with respect to the temperature of each solvent 3 according to the type of the solvent 3.
The viscosity approximation formula Fx is stored in the memory 18 and the hard disk 19 as data, and the personal computer 16 can obtain the viscosity coefficient η at the time of measurement from the average temperature Ta of the samples 3 and 4 measured by the temperature sensor 15.

Then, the personal computer 16 substitutes the obtained viscosity coefficient η and the measured temperature Ta into a Stokes-Einstein relational expression shown in the following equation (1) to obtain a response function from the Lorentz function. Then, a particle size distribution F (D) is calculated from the obtained response function and the power spectrum obtained from the detection signal of the interference light 9. Here, η is the viscosity coefficient, and T is the average value of the measured temperatures Ta, Dp
Is the particle diameter, and the unit is [mPaSe
c], [K] and [m].

As described above, since accurate conditions such as the temperature T and the viscosity coefficient η of the samples 3 and 4 at the time of measurement are reflected in the preparation of the response function, a more accurate measurement of the particle size distribution F (D) is performed. Becomes possible. In particular, in the present invention, since the temperature sensors 15a and 15b used at the time of measurement can be appropriately selected, it is possible to measure the particle size distribution with an accuracy suitable for the samples 3 and 4 to be measured.

That is, when it is desired to perform a measurement with as high a precision as possible, the internal temperature sensor 15a is selected,
Since the temperature T of the samples 3 and 4 can be directly measured, the measurement error of the particle size distribution due to the temperature measurement error can be minimized. On the other hand, when not much measurement accuracy is required, by selecting the external temperature sensor 15b, there is no need to use the internal temperature sensor 15a.
There is no need to clean 5a, and the measurement can be performed easily.

FIG. 3 is a diagram disclosing another example of the present invention. In FIG. 3, reference numeral 22 denotes a liquid tank containing the solvent 3 and the particles 4 to be measured. Reference numeral 23 denotes one end 23a of which is inserted into the liquid tank 22 and the other end 23b is a condensing point of the lens 7. The optical fiber is arranged in the optical fiber. The above-mentioned contact-type temperature sensor 15a is arranged along one end 23a of the optical fiber 23.

According to the above configuration, the laser beam 6 incident on the lens 7 passes through the optical fiber 23 from the other end 23b of the optical fiber 23 and the one end 23a (laser light emitting end).
And scattered light hitting the particles 4 to generate interference light 9. Then, the interference light 9 enters the one end 23a and exits from the other end 23b, and is detected by the detector 11 as shown in FIG.

At the same time, in this example, the temperature sensor 15a for measuring the liquid temperature is attached to one end 23a of the optical fiber 23, so that the temperature at the portion for detecting the light for measuring the particle size distribution can be accurately measured. And the accuracy of the measurement result of the particle size distribution can be improved accordingly. The other points are the same as those described with reference to FIGS. 1 and 2, and a detailed description thereof will be omitted.

Further, by configuring as in this example,
The particle size distribution can be measured in a state where the measurement target samples 3 and 4 are stored in an arbitrary container 22. Therefore, even if the measurement target samples 3 and 4 are stored in a place where they cannot be taken out, the optical fiber 2 can be used without any means for measuring the temperature of the contents in the container storing the samples 3 and 4.
As long as there is an opening into which one end 23a of the sample 3 can be inserted, the particle size distribution of the samples 3 and 4 can be measured.

[0036]

As described above, according to the present invention,
By using the temperature sensor that measures the liquid temperature of the sample to be measured, the user can calculate the particle size distribution using the temperature at the time of more accurate measurement and the viscosity coefficient according to this temperature condition as the calculation parameter. . Therefore, a particle size distribution as accurate as possible can be obtained as the final purpose. If an external temperature sensor that indirectly measures the temperature of the sample to be measured is also installed, this external temperature sensor can be selected and used to simplify the measurement of the particle size distribution of samples that do not require high accuracy. Can be done.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a particle size distribution measuring device of the present invention.

FIG. 2 is a diagram showing a method of selecting a solvent by the particle size distribution measuring device.

FIG. 3 is a diagram showing a processing flow of the particle size distribution measuring method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Particle size distribution measuring device, 2b ... Holder, 3, 4 ... Sample to be measured, 6 ... Laser light, 9 ... Scattered light, 15 ... Temperature measuring unit, 15a ... Internal temperature sensor, 15b ... External temperature sensor, 17 ... Arithmetic processing unit, F (D): particle size distribution.

Claims (3)

[Claims] 1. A particle for irradiating a sample to be measured with a laser beam, converting generated scattered light into an electrical detection signal, and calculating the particle size distribution of particles contained in the sample by performing an inverse operation on the detection signal. In the diameter distribution measuring device, an external temperature sensor attached to a holder that holds the sample to be measured to measure the temperature of the sample to be measured and indirectly measures the temperature, and directly measures the temperature of the sample to be measured Internal temperature sensor that can select the temperature sensor to be used in accordance with the sample to be measured, and substitutes the temperature of the sample to be measured measured by the selected temperature sensor into the Stokes Einstein equation for a response function. A particle size distribution measuring device, comprising: an arithmetic processing unit for performing an inverse calculation of the particle size distribution by obtaining the following. 2. A particle for irradiating a sample to be measured with laser light, converting scattered light generated into an electrical detection signal, and calculating the particle size distribution of particles contained in the sample by inversely calculating the detection signal. In the diameter distribution measuring device, the laser light is guided to the sample to be measured and irradiated, and the optical fiber that guides the scattered light by the particles to the detector, and the temperature of the sample to be measured attached to the laser light emitting end side of the optical fiber is adjusted. A temperature sensor for directly measuring the temperature of the sample to be measured, and substituting the temperature of the sample to be measured into the Stokes-Einstein equation to obtain a response function, thereby performing an inverse calculation of the particle size distribution. A particle size distribution measuring device having a portion. 3. A particle for irradiating a sample to be measured with laser light, converting generated scattered light into an electrical detection signal, and calculating the particle size distribution of particles contained in the sample by inversely calculating the detection signal. In the diameter distribution measurement method, after selecting whether to use an internal temperature sensor for directly measuring the temperature or an external temperature sensor for indirectly measuring the temperature according to the sample to be measured, the sample to be measured at the time of measurement is selected. A particle size distribution measuring method characterized in that the temperature of the sample is measured by a selected temperature sensor, and the measured temperature is substituted into the Stokes-Einstein equation to obtain a response function, thereby performing inverse calculation of the particle size distribution. .