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EP-4361594-B1 - PARTICLE MEASUREMENT DEVICE AND PARTICLE MEASUREMENT METHOD

EP4361594B1EP 4361594 B1EP4361594 B1EP 4361594B1EP-4361594-B1

Inventors

  • NAKAMURA, SOHICHIRO
  • HAMADA, KENICHI

Dates

Publication Date
20260506
Application Date
20220525

Claims (18)

  1. A particle measurement device (10, 60) of a dispersion liquid including a single type of particles, the particle measurement device comprising: a light source unit (20, 22, 62) that irradiates the dispersion liquid with measurement light; a parameter setting unit (13) that sets at least one of a scattering angle or a measurement wavelength as a measurement parameter; a scattered light measurement unit (14) that obtains a plurality of pieces of scattering intensity data by measuring a scattering intensity of scattered light emitted from the dispersion liquid by the measurement light a plurality of times while changing a value of the measurement parameter set by the parameter setting unit a plurality of times; and a calculation unit (18) that calculates a complex refractive index and a particle diameter distribution of the single type of particles by calculating scattering intensity time variation characteristic data and scattering intensity parameter-dependent data from the plurality of pieces of scattering intensity data obtained by the scattered light measurement unit and fitting the calculated scattering intensity time variation characteristic data and the calculated scattering intensity parameter-dependent data and transmittance data of the dispersion liquid using a theoretical formula or a simulation based on a theory of electromagnetic wave behavior that defines a relationship of the complex refractive index, a particle diameter, and the scattering intensity and a theoretical formula or a simulation based on a theory of electromagnetic wave behavior that defines a relationship of the complex refractive index, the particle diameter, and transmittance.
  2. The particle measurement device according to claim 1, further comprising: a transmittance measurement unit that measures the transmittance of the dispersion liquid.
  3. The particle measurement device according to claim 1 or 2, wherein the measurement parameter is the scattering angle, and the scattered light measurement unit obtains the plurality of pieces of scattering intensity data by measuring the scattering intensity of the scattered light of the dispersion liquid for each of a plurality of scattering angles while changing a value of the scattering angle by two angles or more.
  4. The particle measurement device according to claim 1 or 2, wherein the measurement parameter is the measurement wavelength, and the scattered light measurement unit obtains the plurality of pieces of scattering intensity data by measuring the scattering intensity of the scattered light of the dispersion liquid for each of a plurality of measurement wavelengths using the measurement wavelength of two wavelengths or more.
  5. The particle measurement device according to any one of claims 1 to 4, wherein the scattered light measurement unit measures a light intensity of a polarized component of the scattered light of the dispersion liquid obtained by irradiating the dispersion liquid with the measurement light having specific polarization, as the scattering intensity.
  6. The particle measurement device according to any one of claims 1 to 5, wherein the scattered light measurement unit measures at least one of scattering intensity parameter-dependent data obtained by successively irradiating the dispersion liquid with the measurement light having a plurality of polarization states or scattering intensity parameter-dependent data obtained by extracting a polarized component of the scattered light emitted from the dispersion liquid a plurality of times.
  7. The particle measurement device according to any one of claims 1 to 6, wherein the calculated scattering intensity time variation characteristic data of the measurement parameter is calculated based on a Stokes-Einstein's theoretical formula, and the scattering intensity parameter-dependent data of the measurement parameter is calculated based on at least one of a Mie scattering theoretical formula, a discrete dipole approximation method, or a finite-difference time-domain method.
  8. The particle measurement device according to any one of claims 3 to 7, wherein the calculation unit compares the calculated refractive index of the single type of particles with a refractive index for a known material in 100% concentration and calculates a volume concentration of a constituent material of the single type of particles using dependency of the refractive index with respect to a particle volume concentration.
  9. The particle measurement device according to claim 1, wherein the calculation unit calculates the complex refractive index of the single type of particles and a particle diameter distribution of a number concentration by fitting using the scattering intensity time variation characteristic data, the scattering intensity parameter-dependent data, the transmittance data, and volume concentration data of the dispersion liquid.
  10. A particle measurement method of a dispersion liquid including a single type of particles, wherein at least one of a scattering angle or a measurement wavelength is set as a measurement parameter, and the particle measurement method comprises: a measurement step of measuring a scattering intensity of scattered light emitted from the dispersion liquid by measurement light a plurality of times while changing a value of the set measurement parameter a plurality of times; a calculation step of calculating scattering intensity time variation characteristic data and scattering intensity parameter-dependent data from a plurality of pieces of scattering intensity data obtained by the measurement step; and a step of calculating a complex refractive index and a particle diameter distribution of the single type of particles by fitting transmittance data of the dispersion liquid, and the scattering intensity time variation characteristic data and the scattering intensity parameter-dependent data, which are obtained by the calculation step, using a theoretical formula or a simulation based on a theory of electromagnetic wave behavior that defines a relationship of the complex refractive index, a particle diameter, and the scattering intensity and a theoretical formula or a simulation based on a theory of electromagnetic wave behavior that defines a relationship of the complex refractive index, the particle diameter, and transmittance.
  11. The particle measurement method according to claim 10, further comprising: a step of measuring the transmittance of the dispersion liquid and obtaining the transmittance data.
  12. The particle measurement method according to 10 or 11, wherein the measurement parameter is the scattering angle, and in the measurement step, the scattering intensity of the scattered light of the dispersion liquid is measured for each of a plurality of scattering angles while changing a value of the scattering angle by two angles or more.
  13. The particle measurement method according to 10 or 11, wherein the measurement parameter is the measurement wavelength, and in the measurement step, the scattering intensity of the scattered light of the dispersion liquid is measured for each of a plurality of measurement wavelengths using the measurement wavelength of two wavelengths or more.
  14. The particle measurement method according to any one of claims 10 to 13, wherein, in the measurement step, a light intensity of a polarized component of the scattered light of the dispersion liquid obtained by irradiating the dispersion liquid with the measurement light having specific polarization is measured as the scattering intensity.
  15. The particle measurement method according to any one of claims 10 to 14, wherein, in the measurement step, at least one of scattering intensity parameter-dependent data obtained by successively irradiating the dispersion liquid with the measurement light having a plurality of polarization states or scattering intensity parameter-dependent data obtained by extracting a polarized component of the scattered light emitted from the dispersion liquid a plurality of times is measured.
  16. The particle measurement method according to any one of claims 10 to 15, wherein the calculated scattering intensity time variation characteristic data of the measurement parameter is calculated based on a Stokes-Einstein's theoretical formula, and the scattering intensity parameter-dependent data of the measurement parameter is calculated based on at least one of a Mie scattering theoretical formula, a discrete dipole approximation method, or a finite-difference time-domain method.
  17. The particle measurement method according to any one of claims 12 to 16, further comprising: a step of comparing the calculated refractive index of the single type of particles with a refractive index for a known material in 100% concentration and calculating a volume concentration of a constituent material of the single type of particles using dependency of the refractive index with respect to a particle volume concentration.
  18. The particle measurement method according to claim 10, wherein the complex refractive index of the single type of particles and a particle diameter distribution of a number concentration are calculated by fitting using the scattering intensity time variation characteristic data, the scattering intensity parameter-dependent data, the transmittance data, and volume concentration data of the dispersion liquid.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle measurement device and a particle measurement method that measure a complex refractive index of a single type of particle included in a dispersion liquid. 2. Description of the Related Art There is known a dynamic light scattering measurement method that checks dynamic characteristics of scatterers by applying light to a medium, such as a colloidal solution or a particle dispersion liquid, and detecting a time variation of a scattered light intensity scattered from the scatterers in the medium using an autocorrelation function or a power spectrum. The dynamic light scattering measurement method has been widely used in various kinds of measurement, such as particle diameter measurement and gel structure analysis. For example, JP1990-63181B (JP-H02-63181B) describes a particle diameter measurement device comprising a laser device that irradiates a particle group to be measured with laser beam, a measurement system that measures an intensity per scattering angle of scattered light emitted from the laser device and scattered by the particle group to be measured, as a scattered light intensity distribution, a relative particle diameter distribution calculation unit that calculates a relative particle size distribution from measured values of the scattered light intensity distribution obtained by the measurement system, a conversion table that stores conversion coefficients obtained by calculating, for each scattering angle, ratios between measured values and theoretical values of a scattered light intensity distribution obtained by irradiating a reference particle group with known particle diameter and particle diameter density with laser beam, a conversion unit that converts the measured values of the scattered light intensity distribution obtained by irradiating the particle group to be measured with laser beam, based on the conversion table and obtains an incident scattered light intensity distribution in an incidence portion of the measurement system, and an absolute particle diameter distribution calculation unit that calculates an absolute particle diameter distribution from the incident scattering intensity distribution obtained by the conversion unit and the relative particle diameter distribution of the particle group to be measured obtained by the relative particle diameter distribution calculation unit. US 2014/152986 A1 discloses a method and apparatus for improving measurements of scattered light from particles by controlling multiple scattering and coincidence count levels. SUMMARY OF THE INVENTION As described above, JP1990-63181B (JP-H02-63181B) describes that the absolute particle diameter distribution is calculated using the scattered light intensity distribution that is the intensity per scattering angle of scattered light scattered by the particle group to be measured. Note that, in JP1990-63181B (JP-H02-63181B), the particle size distribution can be measured, but a refractive index of a particle cannot be measured. While there is a need to obtain information regarding a refractive index for a measurement target particle, information regarding the refractive index cannot be obtained at present. An object of the present invention is to provide a particle measurement device and a particle measurement method capable of measuring a complex refractive index and a particle size distribution of a single type of particles included in a dispersion liquid. To attain the above-described object, the invention provides a particle measurement device according to claim 1 and a particle measurement method according to claim 10. Advantageous aspects are set out in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a first example of a particle measurement device of an embodiment of the present invention.Fig. 2 is a flowchart illustrating a first example of a particle measurement method not forming part of the present invention.Fig. 3 is a graph showing an example of a relationship between a scattering intensity and a scattering angle of an aqueous dispersion liquid of polystyrene particles.Fig. 4 is a graph showing an example of a secondary autocorrelation function of each scattering angle.Fig. 5 is a graph showing calculated values of a scattering angle and a scattering intensity of each refractive index of particles having the same particle size.Fig. 6 is a graph showing an example of a relationship between a scattering intensity and a measurement wavelength.Fig. 7 is a graph showing another example of a relationship between a scattering intensity and a measurement wavelength.Fig. 8 is a graph showing a relationship between a scattering intensity and a scattering angle of each particle shape.Fig. 9 is a schematic view showing a second example of a particle measurement device of the embodiment of the present invention.Fig. 10 is a schematic view showing a third example of