JPS6276431A - Centrifugal sedimentation particle size distribution measurement method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention provides a method for determining particle size distribution using a sedimentation method.

In the prior art sedimentation type particle size distribution measurement method, normally, test sample 4 particles are dispersed in a liquid and placed in a cell, and centrifugal force is applied.The larger the particle size, the shorter the time. It utilizes the phenomenon of sedimentation, and particles 5 suspended in a solution
The temporal change in H is detected from the light 1d that passes through the cell.

By the way, the degree of light shielding by particles is generally proportional to the particle size, so the particles near the end of the measurement.

In other words, there was a problem in that it was impossible to measure the particle size distribution of particles with a small relative particle size.

C. Objectives In view of the above-mentioned problems, it is an object of the present invention to propose a sedimentation type particle size distribution measuring method that can classify even areas with small relative particle sizes with high resolution.

20. The structure of the present invention, that is, the feature of the present invention is that samples of respective concentrations are suspended in a plurality of cells, and the particle size distribution region is divided and measured.

E. Embodiments The details of the present invention will be explained below based on illustrated embodiments.

FIG. 1 shows an example of a device used in the present invention, and reference numeral 1 in the figure indicates a cell holter driven by an electric motor 2, and a plurality of cells are placed at the same distance L (Fig. f52) from the center of one rotation. It is constructed by fixing 3.3° cells and forming a light-transmitting window at a position facing the optical path of a detector 4, which will be described later. Reference numeral 4 denotes the aforementioned detector, which consists of a light emitting element 4a and a light receiving element 4b arranged with a cell holder l in between. The light-receiving element 4b is configured to irradiate the sample inside the sample and detect the absorbance by the sample. 5 is a microcomputer 5a, ROM5b, RAM
A calculation circuit consisting of 5c inputs the light transmittance signal from the detector 4 and the centrifugal force action time signal from the timer 8, calculates the Fourier rate and outputs it to the display 11 and printer 12, and also outputs it to the display 11 and printer 12. When the light transmittance of the cell on the side becomes outside the measurement range of the detector 4, the detection timing is shifted and the input switch 7 is driven to select the cell on the high concentration side as the measurement target. In addition, the reference numeral 6 in the figure indicates the cell position detection sensor that detects the position of the cell.
denote a logarithmic converter, an A/D converter, and a preamplifier, respectively, which process the optical transmission signal from the detector 4.

In this example, two beakers containing the same medium are prepared, and a sample is prepared by suspending particles of different I,) in each beaker.

These two types of samples having different concentrations of particles are filled into separate cells 3.3° and set in the sample holder 1.

When the apparatus is operated after the preparation is completed in this way, the powder P,, P in the sample accommodated in the cell 3.3' is
2. P3. P4 is a particle with a large particle size that is subjected to centrifugal force.
Sedimentation begins gradually from 1 (Tl in Figure 2). At the beginning of the measurement, since the amount of sedimentation is small, the transmitted light from the cell 3 containing the high concentration sample is extremely small, and the detector 4
Since it is outside the measurement area, the measurement is performed targeting cell 3, which has a lower powder concentration.

In this way, the measurement by cell 3 on the low concentration side takes place at time T2.
Particles of a certain size, in this example particles P,
, Pl has finished settling (T3), the number of particles suspended in the lower cell 3, which is now the target of X1ll constant, decreases. For this reason, the amount of transmitted light becomes so small that it exceeds the measurement range of the detector 4, making measurement impossible.

At this point, the measurement target is switched to the second cell 3' side containing the sample powder at a high concentration. Needless to say, since the same centrifugal force was acting on the two cells 3.3°, the medium in the second cell 3° maintained the same relative particle size distribution as cell 3, which was the subject of measurement last time. On the other hand, small particles P3. which could not be measured. P4 is suspended at high concentrations. Therefore, the light from the light emitting element 4a is absorbed by the particles P3 and P4 suspended in large numbers in the medium and falls within the X1ll fixed range. As a result, Al1 becomes constant again, and particles P, . . . P4 having smaller particle diameters are measured.

Hereafter, by continuing the total Jllll of the sample of cell 3° in this way, we will calculate the Fruier rate of
A11l can be determined.

FIG. 3 shows an example of the measurement terminology according to the present invention, and when it becomes impossible to determine the Fruier ratio of the low concentration cell at a particle size of 3 m (FIG. 3A), By switching the measurement target to the cell on the high concentration side, particle diameters of 0 and 2
It was possible to expand Fruier rate measurement to gm (mouth)
.

In the above embodiment, the cell whose absorbance is to be measured is selectively switched, but the light transmittance of the two cells is alternately measured and the envelope of the peak value is used to create a particle size distribution characteristic diagram. Needless to say, you can do as you like.

In addition, in the above-mentioned embodiment, two sample cells are used to measure the two areas, high and low, but by using three or more cells and changing the sample concentration, a more precise particle size distribution can be measured. Needless to say, it can be done.

As explained above, according to the present invention, the same centrifugal force field is applied to 2g of samples prepared with different concentrations of powder to be measured on the sample holder, and samples with higher concentrations are Since the light transmittance is detected sequentially, the distribution of suspended particles can be determined by a series of measurement operations at a concentration suitable for absorbance measurement.
In particular, the distribution of microparticles can be measured with high resolution.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an example of an apparatus used in the present invention, FIG. 2 is an explanatory diagram showing the operation of the same apparatus, and FIG. 3 is a particle size measurement diagram showing an example of measurement results by the above apparatus.

Claims (1)

[Claims] Centrifugal sedimentation characterized by suspending particles to be measured in a medium at different concentrations in each of a plurality of measurement cells, and measuring absorbance while applying centrifugal force to the measurement cells under the same conditions. formula particle size distribution measurement method.