JP2010101705A - Instrument for measuring physical properties of particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an instrument for measuring physical properties of particles, equipped with an electrode sensor where air bubbles do not remain in a through-hole functioning as a liquid sump part, at the measurement of zeta potential. <P>SOLUTION: The instrument for measuring physical properties of particles is equipped with the electrode sensor, having a body to which not only the through-hole in a lateral direction, but also the air-venting passage passing through the through-hole to extend in a longitudinal direction are formed and a pair of the mutually facing electrodes that are embedded in the body and exposed from the inner wall surface of the through-hole. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a particle property measuring apparatus for measuring particle property values including a zeta potential.

  Colloidal particles, which are macromolecules and aggregates thereof, are charged by adsorption of dissociating groups and ions in an aqueous solution. The electric potential formed by this charging is called a zeta (ζ) electric potential, and the zeta electric potential is calculated by applying an electric field to particles and measuring the moving speed (electrophoretic speed).

  In order to measure the zeta potential using an electrophoretic velocity measuring device, an electrode is inserted into a measurement cell containing a liquid sample in which particles are dispersed, a DC voltage is applied to the electrode, and the liquid sample is measured. The laser beam is irradiated while applying an electric field to the particles inside, the scattered light scattered at a predetermined angle is received, and the difference in frequency between the scattered light and the reference light branched from a part of the laser light (interference phenomenon) ) Is measured, the moving speed of the particles in the liquid sample is calculated. Then, the zeta potential is calculated by performing predetermined arithmetic processing on the obtained moving speed.

Conventionally, as an electrode, as shown in FIG. 9, an electrode sensor is provided with a through hole 71 that functions as a liquid reservoir (measuring unit), and a pair of electrodes 9 are exposed from the inner wall surface of the through hole 71. 6 'is used (Patent Document 1). In order to ensure the flow of the liquid sample, such an electrode sensor 6' has a body 7 smaller than the measurement cell 2 and accommodates the liquid sample. When inserted into the measured cell 2, the liquid sample flows into the through-hole 71 through the gap between the inner peripheral surface of the measurement cell 2 and the side peripheral surface of the main body 7. However, in this case, since it is difficult to control the flow of the liquid sample, air bubbles often remain in the through-hole 71, resulting in inconvenience in particle movement and light scattering. For this reason, when the electrode sensor 6 ′ is inserted into the measurement cell 2, the electrode sensor 6 ′ is inserted obliquely so that no bubbles remain in the through hole 71.
JP 2004-317123 A

  Therefore, the present invention is intended to provide a particle physical property measuring apparatus including an electrode sensor in which bubbles do not remain in a through hole that functions as a liquid reservoir when measuring a zeta potential.

  That is, the particle physical property measuring apparatus according to the present invention measures a physical property value of particles dispersed in a liquid sample, and has a horizontal through-hole formed therein and the vertical direction through the through-hole. And an electrode sensor having a pair of opposed electrodes that are embedded in the main body and exposed from the inner wall surface of the through hole. It is characterized by.

  If it is such, since it has an electrode sensor in which an air vent extending in the vertical direction is formed through the through hole functioning as a liquid reservoir, the size of the main body and the size of the measurement cell are provided. When the electrode sensor is inserted into the measurement cell containing the liquid sample, the liquid sample first flows into the air vent path below the through hole. Then, the liquid sample that has flowed into the air vent passage flows into the through hole. Next, the air pushed out by the inflowing liquid sample and flowing out from the through hole flows into the air vent path above the through hole and is discharged out of the measurement cell. For this reason, according to the present invention, it is possible to control the flow of the liquid sample and the air in the measurement cell by the air vent passage, so that it is difficult for bubbles to remain in the through hole. Therefore, when measuring the zeta potential, the movement of particles in the liquid sample in the through hole and light scattering are not hindered by the bubbles, and the measurement accuracy of the zeta potential can be kept high.

  Conventionally, the physical properties of nanoparticles have been measured by scanning electron microscope (SEM) for shape property values such as aspect ratio (aspect ratio) and agglomeration degree, the particle diameter is determined by dynamic light scattering, and the dispersity is zeta potential. Are measured using separate analyzers. For this reason, a particle physical property measuring apparatus capable of efficiently measuring various physical property values with one unit is desired.

  However, it is necessary to detect scattered light from multiple angles in order to accurately measure shape physical properties such as aspect ratio and degree of aggregation, particle diameter, and molecular weight. It is necessary to insert an electrode into the inside. For this reason, the electrode is obstructed and only scattered light in one direction can be detected. In addition, if an electrode is inserted into a measurement cell after measuring a physical property value other than the zeta potential, the liquid sample may be agitated to disturb the particle state. Furthermore, when a zeta potential is measured and then a physical property value other than the zeta potential is measured, a particle deformed by voltage application may be measured.

  For this reason, the particle physical property measuring apparatus according to the present invention measures the zeta potential and other various physical property values efficiently and with high accuracy without disturbing the state of the particles while the electrode sensor is inserted into the measurement cell. So that the body of the electrode sensor has a cylindrical shape and is a measurement cell that can be fitted to the electrode sensor, and when the electrode sensor is inserted into the measurement cell, It is preferable to include a measurement cell that is hooked at a position and that forms a gap between the bottom surface of the electrode sensor and the inner bottom surface of the measurement cell.

  If this is the case, the zeta potential is measured by applying a voltage to the liquid sample in the through-hole formed in the electrode sensor, and formed between the inner bottom surface of the measurement cell and the bottom surface of the electrode sensor. By irradiating the liquid sample in the formed gap from multiple angles and detecting the scattered light, shape property values such as aspect ratio and cohesion, particle diameter and molecular weight can be measured. It is possible to measure the zeta potential and other various physical property values efficiently and with high accuracy while being inserted into the measurement cell.

  In order for the electrode sensor to be hooked at a predetermined position in the measurement cell to form a gap between the inner bottom surface of the measurement cell and the bottom surface of the electrode sensor, for example, as the electrode sensor, the main body What is provided with the cover part which was provided in the upper end of this and protruded in the horizontal direction from the said main body is used.

  If bubbles adhere to the bottom surface of the electrode sensor, measurement of shape property values such as aspect ratio and aggregation degree, particle diameter, and molecular weight may be hindered. In this case, if the measurement cell is composed of a cylindrical part and a bottom part that are separate from each other, the measurement cell in which the electrode sensor is inserted is turned upside down so that the bottom part is up. It is preferable because the bottom can be removed to remove bubbles.

  Thus, according to the present invention, it is possible to fill the liquid sample without leaving air in the through hole functioning as the liquid reservoir. In addition, by forming a gap between the inner bottom surface of the measurement cell and the bottom surface of the electrode sensor, the zeta potential, the shape property value such as the aspect ratio and the degree of aggregation, etc., with the electrode sensor inserted in the measurement cell, Since the particle diameter and molecular weight can be measured, various physical property values can be measured efficiently and with high accuracy without disturbing the state of the particles.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an outline of the configuration of a particle property measuring apparatus 1 according to this embodiment. The particle property measuring apparatus 1 according to this embodiment includes a shape property value measuring mechanism, a particle size measuring mechanism, a molecular weight measuring mechanism, and a zeta potential measuring mechanism, and is transparent as shown in FIG. A measurement cell 2 containing a liquid sample made of quartz glass or the like and having a particle group dispersed in a dispersion medium such as water, and an electrode sensor 6 inserted into the measurement cell 2 (not shown in FIG. 1) .), A laser 3 for irradiating the liquid sample with laser light L, and scattered light S emitted from a group of particles in the liquid sample irradiated with the laser light L, and a pulse signal corresponding to the number of photons or Light receiving units 41 and 42 that are photomultiplier tubes that output an electrical signal corresponding to fluctuations in light intensity, a half mirror 51 that branches a part of the laser light L emitted from the laser 3, mirrors 52 and 53, and Reference light R and scattering from mirror 53 A reference optical system 5 consisting of a half mirror 54 for mixing the light S, and a.

The configuration of each measurement mechanism will be described below.
As shown in FIG. 2, the shape property value measuring mechanism for measuring the aspect ratio, the degree of aggregation, and the like includes a laser 3, polarizers 11 and 14, quarter-wave plates 12 and 13, and a light receiving unit 41. Composed. The polarizer 11 is used to fix the polarization direction of the laser light L emitted from the laser 3, but the quarter wavelength plates 12 and 13 are rotatable around the optical axis, and the quarter wavelength plate. The linearly polarized light is converted into elliptically polarized light at 12, and the elliptically polarized light is converted back to linearly polarized light by the quarter wavelength plate 13 and the polarizer 14.

  In order to measure the physical property value of the shape, first, the transmittance of the laser beam L of the liquid sample in the measurement cell 2 is measured using the method described in US Pat. No. 6,721,051. Next, the laser light L is emitted while rotating the quarter-wave plates 12 and 13 and the polarizer 14 around the optical axis, and the position (angle) of the light receiving unit 41 is changed in a plurality of modes of polarization patterns. Then, the intensity of the scattered light S at a predetermined scattering angle is measured. Then, predetermined aspect processing is performed on the obtained transmittance and scattered light intensity ratio to calculate the aspect ratio and / or the degree of aggregation.

  As shown in FIG. 3, the particle size measuring mechanism includes a laser 3, a light receiving unit 41, and a correlator 15. In order to measure the particle size (particle size distribution), the dynamic light scattering method is used, and the liquid sample in the measurement cell 2 is irradiated with the laser light L, and the scattered light S emitted from the particle group in the liquid sample is used. The correlator 15 that receives light from the light receiving unit 41 and receives a pulse signal corresponding to the number of photons from the light receiving unit 41 generates autocorrelation data from the time-series data of the number of pulses, and generates a predetermined value based on the autocorrelation data. The particle size distribution of the particle group is calculated by performing arithmetic processing. In the present embodiment, the method of calculating from the pulse signal corresponding to the number of photons has been described in detail, but it is also possible to calculate from the electric signal corresponding to the fluctuation of the light intensity.

  In the embodiment shown in FIG. 3, the light receiving unit 41 receives the scattered light S in the optical path orthogonal to the laser light L, but a suitable position of the light receiving unit 41 when measuring the particle size (particle size distribution) ( The angle varies depending on the concentration of the liquid sample, and is orthogonal to the laser beam L when the transmittance is high (the concentration of the liquid sample is low) according to the laser beam transmittance of the liquid sample measured when measuring the shape property value. The scattered light S of the optical path (scattering angle 90 °) is received, and when the transmittance is low (the concentration of the liquid sample is high), the scattered light S of the optical path matching the laser light L (scattering angle 180 °) is received. As described above, the position (angle) of the light receiving unit 41 is adjusted.

  As shown in FIG. 4, the molecular weight measurement mechanism includes a laser 3 and a light receiving unit 41. In order to measure the molecular weight, laser light is applied to the liquid sample in the measuring cell 2 while changing the position (angle) of the light receiving unit 41 using a plurality of types of liquid samples with different concentrations using the static light scattering method. L is irradiated, and the angular distribution of the light intensity of the scattered light S emitted from the particle group in the liquid sample is measured. Then, from the change in the amount of scattered light due to the concentration of the liquid sample and the change in the scattering angle, a Zimm plot is performed to calculate the molecular weight of the particles.

  As shown in FIG. 5, the zeta potential measuring mechanism includes a laser 3, an electrode sensor 6 including a pair of electrodes 9 made of platinum or the like, a reference optical system 5, and a light receiving unit 42. In order to measure the zeta potential, an electrophoretic method is used, a direct current or an alternating voltage is applied to the electrode sensor 6 inserted in the measurement cell 2, and a laser beam L is irradiated while applying an electric field to particles in the liquid sample. The scattered light S scattered at a predetermined angle is received, and the difference in frequency (interference phenomenon) between the scattered light S and the reference light R is measured to calculate the moving speed of the particles in the liquid sample. Further, the zeta potential is calculated by performing predetermined arithmetic processing on the obtained moving speed.

  As shown in FIGS. 6 and 7, the electrode sensor 6 includes a main body 7 in which a through hole 71 and an air vent path 72 are formed, a lid portion 8 provided at the upper end of the main body 7, and the main body 7 and the lid portion 8. A pair of electrodes 9 embedded therein.

  The main body 7 has a cylindrical shape, and has a horizontal through hole 71 formed in the lower portion thereof, and an air vent path 72 extending in the vertical direction through the through hole 71. Two air vent paths 72 are formed on the side peripheral surface of the main body 7 so as to pass through the open ends of the through holes 71, respectively, and the lower air vent path 721 formed below the through holes 71, It is divided into an upper air vent path 722 formed on the upper side.

  The lid portion 8 has a disk shape, is provided at the upper end of the main body 7, protrudes in the horizontal direction from the main body 7, and has a vertical through-hole 81 connected to the air vent path 72.

  The main body 7 and the lid 8 are made of, for example, polyvinyl fluoride (poly (vinyl fluoride), PVF), polyvinylidene fluoride (poly (vinylidene fluoride), PVDF), polytetrafluoroethylene (PTFE), tetra Fluoroethylene / hexafluoropropylene copolymer (tetrafluoroethylene / hexafluoropropylene copolymer, FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (tetrafluoroethylene / perfluoroalkylene copolymer, etc.) It is integrally formed in a state of enclosing the.

  The electrode 9 is a pair of long plate-like bodies made of platinum or the like facing each other, embedded in the main body 7 and the lid portion 8, and the lower portion thereof is exposed from the inner wall surface of the through hole 71. . The upper end of the electrode 9 protrudes from the upper end surface of the lid 8 and is connected to a voltage application circuit or the like (not shown).

  The electrode sensor 6 is used by being inserted into the measurement cell 2, and the measurement cell 2 is fitted with the electrode sensor 6, and is composed of a cylindrical portion 21 and a bottom portion 22 that are separate from each other. 22 and the cylinder part 21 are detachable.

  When the electrode sensor 6 is inserted into the measurement cell 2, the lid portion 8 comes into contact with the upper end of the measurement cell 2 and is latched at a predetermined position, and a gap 23 is formed between the inner bottom surface of the measurement cell 2 and the bottom surface of the electrode sensor 6. Is formed.

  In this embodiment, various physical property values of particles can be measured while the electrode sensor 6 is inserted into the measurement cell 2. When the electrode sensor 6 is inserted into the measurement cell 2 containing the liquid sample, first, the air in the measurement cell 2 flows out through the air vent path 72. Next, when the main body 7 is immersed in the liquid sample stored in the measurement cell 2, the liquid sample flows into the lower air vent path 721. When the electrode sensor 6 is further inserted deeply into the measurement cell 2, the liquid sample flowing into the lower air vent 721 flows into the through hole 71, and the air in the through hole 71 is pushed out by the liquid sample that has flowed into the upper air vent. Flow into 722. Further, when the electrode sensor 6 is inserted deeply into the measurement cell 2 and a liquid sample flows into the upper air vent path 722, the air in the upper air vent path 722 is discharged to the outside from the through hole 81 of the lid portion 8. Is done.

  When measuring the zeta potential, the liquid sample in the through-hole 71 is irradiated with the laser beam L. On the other hand, when measuring the physical properties such as the aspect ratio and the degree of aggregation, the particle diameter, and the molecular weight, the gap 23 The liquid sample inside is irradiated with laser light L. In order to quickly measure various physical property values of these particles, the laser beam L may be simultaneously irradiated to the liquid sample in the through hole 71 and the liquid sample in the gap 23 by using the laser beam L as a double beam.

  In the present embodiment, the through-hole 71 functioning as a liquid reservoir is surrounded by a wall surface. However, if a voltage is applied to the electrode 9 if the lower part of the liquid reservoir is open, In addition, the flow of the liquid sample in the liquid reservoir is disturbed, making it difficult to accurately measure the moving speed of the particles when measuring the zeta potential.

  Therefore, according to the particle physical property measuring apparatus 1 configured as described above, the air vent path 72 extending in the vertical direction through the through hole 71 functioning as a liquid reservoir is formed on the side peripheral surface of the main body 7 of the electrode sensor 6. Therefore, when the electrode sensor 6 is inserted into the measurement cell 2 containing the liquid sample, first, the liquid sample flows into the lower air vent path 721, and the liquid sample that flows into the lower air vent path 721 flows into the through hole 71. Flow into. Next, the air pushed out by the inflowing liquid sample and flowing out from the through hole 71 flows into the upper air vent path 722 and is discharged out of the measurement cell 2 from the through hole 81. For this reason, according to the present embodiment, since the flow of the liquid sample and the air in the measurement cell 2 can be controlled by the air vent path 72, it is possible to prevent bubbles from remaining in the through hole 71. Accordingly, movement of particles in the liquid sample in the through hole 71 and light scattering are not hindered by bubbles during zeta potential measurement, and the measurement accuracy of the zeta potential can be kept high.

  Further, when the electrode sensor 6 is inserted into the measurement cell 2, the lid portion 8 comes into contact with the upper end of the measurement cell 2 and is latched at a predetermined position, and between the inner bottom surface of the measurement cell 2 and the bottom surface of the electrode sensor 6. Since the gap 23 is generated, the zeta potential can be measured by applying a voltage to the liquid sample in the through hole 71 formed in the electrode sensor 6, and the liquid sample in the gap 23 is irradiated with light from multiple angles. Then, by detecting the scattered light, it is possible to measure the shape physical property value such as aspect ratio and aggregation degree, particle diameter and molecular weight, so that the state of the particles can be maintained with the electrode sensor 6 inserted in the measurement cell 2. Various physical property values can be measured efficiently and with high accuracy without disturbing.

  Furthermore, in this embodiment, since the main body 7 and the lid portion 8 of the electrode sensor 6 are made of a fluorine resin having high chemical resistance, the electrode sensor 6 can be used regardless of the dispersion medium of the liquid sample.

  Further, since the measurement cell 2 is composed of a cylindrical portion 71 and a bottom portion 72 which are separate from each other, when bubbles adhere to the bottom surface of the electrode sensor 6 or the like, the aspect ratio, the degree of aggregation, etc. are reduced by the bubbles. In order to prevent the measurement of the shape physical property value, the particle diameter and the molecular weight, the measurement cell 2 in which the electrode sensor 6 is inserted is turned upside down so that the bottom 72 is up, and then the bottom 72 is removed to remove bubbles. Can be excluded.

  The present invention is not limited to the above embodiment.

  For example, when the particle property measuring apparatus 1 measures only the zeta potential, the shape of the main body 7 of the electrode sensor 6 and the shape of the measurement cell 2 are not limited to a cylindrical shape. Good. In this case, the gap 23 may not be formed between the inner bottom surface of the measurement cell 2 and the bottom surface of the electrode sensor 6.

  Further, as shown in FIG. 8, the electrode sensor 6 does not have the lid portion 8, the inner space of the measurement cell 2 is narrower on the bottom side, and the electrode sensor 6 is hooked at the stepped portion 73 where the inner space becomes narrower. Then, the gap 23 may be formed between the inner bottom surface of the measurement cell 2 and the bottom surface of the electrode sensor 6. Further, instead of forming a gap between the inner bottom surface of the measurement cell 2 and the bottom surface of the electrode sensor 6, a separate space is provided above or below the zeta potential measurement through hole 71 of the electrode sensor 6. Particle physical properties other than the potential may be measured.

  Furthermore, the air vent path 72 may not be formed on the side peripheral surface of the main body 7, and may penetrate through the inside of the main body 7, for example. Further, the air vent path 72 is not limited to two, and may be one or three or more. Further, the measurement cell 2 may be one in which the cylindrical portion 21 and the bottom portion 22 are integrally molded.

  It goes without saying that the present invention may appropriately combine some or all of the above-described embodiments and modified embodiments, and various modifications can be made without departing from the spirit of the present invention.

1 is a schematic overall view showing an outline of a particle physical property measuring apparatus according to an embodiment of the present invention. The typical block diagram which shows the shape physical-property value measurement mechanism in the embodiment. The typical block diagram which shows the particle size measurement mechanism in the embodiment. The typical block diagram which shows the molecular weight measurement mechanism in the embodiment. The typical block diagram which shows the zeta potential measurement mechanism in the embodiment. The perspective view which shows the electrode sensor and measurement cell in the embodiment. The longitudinal cross-sectional view which shows the electrode sensor and measurement cell in the embodiment. The longitudinal cross-sectional view which shows the electrode sensor and measurement cell in other embodiment. The perspective view which shows the conventional electrode sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Particle physical property measuring apparatus 2 ... Measurement cell 6 ... Electrode sensor 7 ... Main body 71 ... Through-hole 72 ... Air vent path 8 ... Cover part 9 ... Electrode

Claims (4)

Measuring physical properties of particles dispersed in a liquid sample,
A main body in which a through hole in the horizontal direction is formed and an air vent path extending in the vertical direction through the through hole is formed, and the main body embedded in the main body and exposed from the inner wall surface of the through hole An apparatus for measuring particle physical properties, comprising an electrode sensor having a pair of opposed electrodes. The electrode sensor body is cylindrical, and
A measurement cell that can be fitted with the electrode sensor, and when the electrode sensor is inserted into the measurement cell, the electrode cell is hooked at a predetermined position, and the bottom surface of the electrode sensor and the inner bottom surface of the measurement cell The particle physical property measuring apparatus according to claim 1, further comprising a measurement cell in which a gap is formed.   The particle physical property measuring apparatus according to claim 2, wherein the electrode sensor includes a lid portion provided at an upper end of the main body and protruding laterally from the main body.   4. The particle physical property measuring apparatus according to claim 2, wherein the measurement cell includes a cylindrical portion and a bottom portion that are separate from each other.