Dynamic light scattering measurement method and dynamic light scattering measurement apparatus

Abstract

Provided are a dynamic light scattering measurement method and a dynamic light scattering measurement device with which it is possible to ascertain the particle size distribution for each type of particle included in a dispersion that includes particles. This dynamic light scattering measurement method for a dispersion including a plurality of types of particles includes: a measurement step in which scattering intensity in a dispersion is measured a plurality of times, while changing one value of at least scattering angle and measurement wavelength from among measurement parameters, so as to obtain a plurality of scattering intensity data points; a calculation step in which a plurality of scattering intensity temporal variation data points and a plurality of scattering intensity parameter-dependent data points are calculated using the plurality of scattering intensity data points obtained in the measurement step; and a step in which the plurality of scattering intensity temporal variation data points and the plurality of scattering intensity parameter-dependent data points obtained in the calculation step are fitted to a formula establishing the relationship between particle size and the scattering intensity so as to determine the particle size distribution of each of the plurality of types of particles.

Description

Technical Field

[0001] The present invention relates to a method for measuring dynamic light scattering of a dispersion liquid containing particles and a dynamic light scattering measuring apparatus.

Background Art

[0002] There is a dynamic light scattering measurement method for examining the dynamic characteristics of a scatterer by applying light to a medium such as a colloidal solution or a particle dispersion liquid and detecting the time variation of the scattered light intensity from the scatterer in the medium using a time correlation function or a power spectrum. The dynamic light scattering measurement method is widely used for various measurements such as particle size measurement.

[0003] Patent Document 1 discloses a method for evaluating the characteristics of particles in a sample, including irradiating the sample in a sample cell with a light beam so as to generate scattered light by the interaction between the light beam and the sample, acquiring a time series of measurement values of the scattered light from a single detector, and determining which of the measurement values obtained when large-diameter particles contribute to the scattered light by judging which of the measurement values obtained when large-diameter particles contribute to the scattered light, which includes dividing the time series into a plurality of short sub-ranges, performing correlation on each sub-range, and then judging which of the sub-ranges contains measurement values having a scattering contribution from large-diameter particles, and determining the particle size distribution from the time series of measurement values, including correction of the light scattered by large-diameter particles, which correction includes excluding the sub-range obtained when large-diameter particles contribute to the scattered light or analyzing it individually. Here, a sub-range refers to a part of the execution data extracted from the time series data measured multiple times or for a long time.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-535429 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent Document 1 evaluates small-diameter particles while removing the influence of large-diameter particles when determining the particle size distribution. However, Patent Document 1 cannot obtain the particle size distribution for each particle type contained in a dispersion containing particles.

[0006] The object of the present invention is to provide a dynamic light scattering measurement method and a dynamic light scattering measurement apparatus that can obtain the particle size distribution for each type of particle contained in a dispersion containing particles. [Means for solving the problem]

[0007] To achieve the above objective, one aspect of the present invention provides a method for measuring the dynamic light scattering of a dispersion containing multiple types of particles, comprising: a measurement step of obtaining multiple scattering intensity data by measuring the scattering intensity of the dispersion multiple times while changing the value of at least one of the measurement parameters, the scattering angle and the measurement wavelength; a calculation step of calculating multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data from the multiple scattering intensity data obtained in the measurement step; and a step of determining the particle size distribution for each of the multiple types of particles by fitting the multiple scattering intensity time variation characteristic data and the multiple scattering intensity parameter-dependent data obtained in the calculation step to a theoretical formula that defines the relationship between particle size and scattering intensity.

[0008] One aspect of the present invention provides a method for measuring the dynamic light scattering of a dispersion containing particles, comprising: a measurement step of obtaining multiple scattering intensity data by measuring the scattering intensity of the dispersion multiple times while changing the value of at least one of the measurement parameters, the scattering angle and the measurement wavelength; a calculation step of calculating multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data from the multiple scattering intensity data obtained in the measurement step; a determination step of determining the type of particles contained in the dispersion by fitting the multiple scattering intensity time variation characteristic data and the multiple scattering intensity parameter-dependent data obtained in the calculation step to a theoretical formula defining the relationship between particle size and scattering intensity; and a step of determining the particle size distribution for each type of particle in the dispersion determined in the determination step.

[0009] It is preferable that the measurement parameter be the scattering angle. Furthermore, it is preferable that the measurement parameter be the measurement wavelength. Furthermore, it is preferable that the measurement parameters are the scattering angle and the measurement wavelength. The measurement process preferably involves irradiating the dispersion with incident light of a specific polarization and measuring the light intensity of the polarization component of the scattered light of the dispersion as the scattering intensity. Furthermore, the measurement process preferably involves measuring at least one of the following: scattering intensity parameter-dependent data obtained by sequentially irradiating the dispersion with incident light in multiple polarization states, and scattering intensity parameter-dependent data obtained by extracting multiple polarization components of scattered light emitted from the dispersion. It is preferable that the scattering intensity profiles obtained by changing the values ​​of the measurement parameters differ for each of the multiple types of particle species. It is preferable that the calculated scattering intensity time variation characteristic data and the scattering intensity parameter dependence data of the measured parameters are calculated based on at least one of the following: the Mie scattering theory formula, the discrete dipole approximation method, and the Stokes-Einstein theory formula.

[0010] One aspect of the present invention provides a dynamic light scattering measuring device for a dispersion containing multiple types of particles, comprising: a parameter setting unit that changes the value of at least one of the measurement parameters, the scattering angle and the measurement wavelength; a scattering light measurement unit that measures the scattering intensity of the dispersion multiple times while changing the value of at least one of the measurement parameters, the scattering angle and the measurement wavelength, by the parameter setting unit to obtain multiple scattering intensity data; and a calculation unit that calculates multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data from the multiple scattering intensity data obtained by the scattering light measurement unit, and then fits the calculated multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data to a theoretical formula defining the relationship between particle size and scattering intensity to determine the particle size distribution for each of the multiple types of particles.

[0011] One aspect of the present invention provides a dynamic light scattering measuring device for a dispersion containing particles, comprising: a parameter setting unit that changes the value of at least one of the scattering angle and measurement wavelength as a measurement parameter; a scattering light measurement unit that measures the scattering intensity of the dispersion multiple times while changing the value of at least one of the scattering angle and measurement wavelength among the measurement parameters by the parameter setting unit to obtain multiple scattering intensity data; and a calculation unit that calculates multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data from the multiple scattering intensity data obtained by the scattering light measurement unit, determines the type of particles in the dispersion by fitting the calculated multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data to a theoretical formula that defines the relationship between particle size and scattering intensity, and, if the type of particles in the dispersion can be determined, calculates the particle size distribution of each particle in the dispersion.

[0012] It is preferable that the measurement parameter be the scattering angle. Furthermore, it is preferable that the measurement parameter be the measurement wavelength. Furthermore, it is preferable that the measurement parameters are the scattering angle and the measurement wavelength. The scattered light measurement unit preferably measures the light intensity of the polarization component of the scattered light of a dispersion obtained by irradiating the dispersion with incident light of a specific polarization as the scattering intensity. Furthermore, it is preferable that the scattered light measurement unit measures at least one of the following: scattering intensity parameter-dependent data obtained by sequentially irradiating the dispersion with incident light in multiple polarization states, and scattering intensity parameter-dependent data obtained by extracting multiple polarization components of scattered light emitted from the dispersion. It is preferable that the scattering intensity profiles obtained by changing the values ​​of the measurement parameters differ for each of the multiple types of particle species. It is preferable that the calculated scattering intensity time variation characteristic data and the scattering intensity parameter dependence data of the measured parameters are calculated based on at least one of the following: the Mie scattering theory formula, the discrete dipole approximation method, and the Stokes-Einstein theory formula. [Effects of the Invention]

[0013] According to the present invention, a dynamic light scattering measurement method and a dynamic light scattering measurement apparatus can be provided that can obtain the particle size distribution for each type of particle contained in a dispersion containing particles. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram showing an example of a dynamic light scattering measurement device according to an embodiment of the present invention. [Figure 2] This graph shows the relationship between scattering intensity and scattering angle. [Figure 3] This is a schematic diagram showing a single particle. [Figure 4] This is a schematic diagram showing aggregates formed by cross-linking particles. [Figure 5] This is a flowchart showing a dynamic light scattering measurement method according to an embodiment of the present invention. [Figure 6] This is a histogram of a single particle. [Figure 7] This is a histogram of aggregates formed by cross-linking particles. [Figure 8]This graph shows an example of the relationship between scattering intensity and measurement wavelength. [Figure 9] This graph shows another example of the relationship between scattering intensity and measured wavelength. [Figure 10] This is the histogram of particle A. [Figure 11] This is the histogram of particle B. [Figure 12] This graph shows the relationship between scattering intensity and scattering angle for each particle shape obtained by the DDA method. [Figure 13] This is a schematic perspective view showing spherical particles. [Figure 14] This is a schematic perspective view showing disc-shaped particles. [Figure 15] This graph shows an example of data dependent on the scattering intensity parameter. [Figure 16] This graph shows another example of data dependent on the scattering intensity parameter. [Figure 17] This graph shows the measurement results for Sample 1 using the dynamic light scattering measurement method of the present invention. [Figure 18] This graph shows the measurement results for Sample 2 using the dynamic light scattering measurement method of the present invention. [Figure 19] This graph shows the measurement results for Sample 3 using the dynamic light scattering measurement method of the present invention. [Figure 20] This graph shows the measurement results for Sample 4 using the dynamic light scattering measurement method of the present invention. [Figure 21] This graph shows the measurement results for Sample 1 using a conventional dynamic light scattering measurement method. [Figure 22] This graph shows the measurement results for Sample 2 using a conventional dynamic light scattering measurement method. [Figure 23] This graph shows the measurement results for Sample 3 using a conventional dynamic light scattering measurement method. [Figure 24] This graph shows the measurement results for Sample 4 using a conventional dynamic light scattering measurement method. [Figure 25] This graph shows the measurement results for sample 10 using the dynamic light scattering measurement method of the present invention. [Figure 26] This graph shows the measurement results for sample 11 using the dynamic light scattering measurement method of the present invention. [Figure 27] This graph shows the measurement results for sample 12 using the dynamic light scattering measurement method of the present invention. [Figure 28] This graph shows the measurement results for sample 10 using a conventional dynamic light scattering measurement method. [Figure 29] This graph shows the measurement results for sample 11 using a conventional dynamic light scattering measurement method. [Figure 30] This graph shows the measurement results for sample 12 using a conventional dynamic light scattering measurement method. [Modes for carrying out the invention]

[0015] The dynamic light scattering measurement method and dynamic light scattering measurement apparatus of the present invention will be described in detail below based on preferred embodiments shown in the attached drawings. The figures described below are illustrative examples for illustrating the present invention, and the present invention is not limited to the figures shown below. In the following, the "~" symbol indicating a numerical range includes the numbers written on both sides. For example, when ε is given as α ~ β, the range of ε is the range that includes both α and β, which can be expressed in mathematical notation as α ≤ ε ≤ β. Unless otherwise specified, angles expressed as "specific numerical values" and angles such as "perpendicular" include the generally acceptable margin of error in the relevant technical field.

[0016] (Dynamic light scattering measurement device) Figure 1 is a schematic diagram showing an example of a dynamic light scattering measurement device according to an embodiment of the present invention. The dynamic light scattering measurement device 10 shown in Figure 1 includes an incident setting unit 12 that irradiates a sample cell 16 containing a dispersion liquid Lq containing particles with laser light as measurement light, a scattered light measurement unit 14 that measures the scattering intensity of scattered light produced when the laser light is scattered by the dispersion liquid Lq, and a calculation unit 18 that determines the particle size distribution for each type of particle contained in the dispersion liquid.

[0017] The incident setting unit 12 includes a first light source unit 20 that emits laser light as input light to the dispersion Lq, a second light source unit 22 that emits laser light as input light to the dispersion Lq, a half mirror 24, a focusing lens 26 that focuses the laser light transmitted or reflected by the half mirror 24 onto the sample cell 16, and a polarizing element 28 that transmits only a certain polarization component of the laser light.

[0018] The half-mirror 24 transmits the laser light emitted from the first light source unit 20 and reflects the laser light emitted from the second light source unit 22 at, for example, 90° with respect to the incident direction, and along the same optical path as the laser light emitted from the first light source unit 20. The laser light transmitted through the half-mirror 24 and the laser light reflected by the half-mirror 24 pass along the same optical axis C1. A focusing lens 26 and a polarizing element 28 are arranged on the optical axis C1. A sample cell 16 is arranged on the optical axis C1. Furthermore, a shutter (not shown) that temporarily blocks the optical path of the laser beam and an ND (Neutral Density) filter (not shown) that attenuates the laser beam may be provided on the optical axis C1 of the laser beam. ND filters are used to adjust the intensity of laser light, and any known type can be used as appropriate.

[0019] The polarizing element 28 can be any polarizing element appropriate to the polarization of light irradiated onto the sample cell 16, such as circularly polarized, linearly polarized, or elliptically polarized light. Note that if it is not necessary to irradiate the sample cell 16 with polarized light, the polarizing element 28 is not necessarily required.

[0020] The first light source unit 20 irradiates the dispersion liquid Lq with laser light as input light, and is, for example, an Ar laser that emits laser light with a wavelength of 488 nm. The wavelength of the laser light is not particularly limited. The second light source unit 22 irradiates the dispersion liquid Lq with laser light as input light, and is, for example, a He-Ne laser that emits laser light with a wavelength of 633 nm. The wavelength of the laser light is not particularly limited.

[0021] The first light source unit 20 and the second light source unit 22 emit laser light at different wavelengths. Note that in the dynamic light scattering measurement device 10, the appropriate wavelength varies depending on the target particle being measured. Therefore, it is desirable to select a combination of wavelengths such that the refractive index difference between multiple particles differs significantly between wavelengths. Furthermore, the incident setting unit 12 changes the value of the measurement wavelength, which is one of the measurement parameters, along with the scattering angle. The scattering angle is changed by the rotation unit 36, described later, rotating the scattered light measurement unit 14. The incident setting unit 12 and the rotation unit 36, described later, constitute the parameter setting unit 13. The parameter setting unit 13 changes the value of at least one of the measurement parameters, either the scattering angle or the measurement wavelength. The measurement wavelength is changed by switching between the first light source unit 20 and the second light source unit 22. Therefore, the configuration has light source units corresponding to the number of measurement wavelengths, and is not limited to the first light source unit 20 and the second light source unit 22. If the measurement wavelength is not changed, one of the first light source unit 20 and the second light source unit 22 is sufficient. Furthermore, the number of light source units can be increased to increase the number of measurement wavelengths.

[0022] The sample cell 16 is, for example, a rectangular or cylindrical container made of optical glass or optical plastic. The sample cell 16 contains a dispersion Lq containing particles to be measured. Laser light is irradiated onto the dispersion Lq as input light to the dispersion Lq. The sample cell 16 may be placed inside an immersion bath (not shown). The immersion bath is used to eliminate refractive index differences and to equalize the temperature.

[0023] As described above, the scattered light measurement unit 14 measures the scattering intensity of the scattered light generated when the laser light is scattered in the dispersion liquid Lq. The incident setting unit 12 changes the value of the measurement wavelength among at least the scattering angle and measurement wavelength as measurement parameters, and the scattered light measurement unit 14 measures the scattering intensity of the dispersion Lq multiple times. The scattered light measurement unit 14 includes a polarizing element 30 that transmits only a certain polarization component of the scattered light from the sample cell 16, a focusing lens 32 that images the scattered light onto the photodetector 34, and a photodetector 34 that detects the scattered light. Furthermore, a first pinhole (not shown) and a second pinhole (not shown) may be provided to appropriately set the scattering volume of the sample.

[0024] The polarizing element 30 can be appropriately selected to detect the polarization, such as circular polarization, linear polarization, or elliptic polarization. Alternatively, the polarizing element 30 may be configured with a polarizing element for detecting circular polarization and a polarizing element for detecting linear polarization side by side, and the light intensity of each polarization component of the scattered light may be detected by the photodetector 34 by switching between them according to the polarization to be detected. Furthermore, if it is not necessary to measure the light intensity of the polarization component of scattered light, the polarizing element 30 is not necessarily required.

[0025] The light detection unit 34 is not particularly limited as long as it can detect the intensity of scattered light, and for example, a photomultiplier tube, a photodiode, an avalanche photodiode, and a time correlation meter can be used. Furthermore, the device has a rotating part 36 that rotates the scattered light measuring unit 14 to change the angle of the scattered light. The angle of the scattering angle θ can be changed by the rotating part 36. The angle of the scattering angle θ is the scattering angle. In Figure 1, the scattering angle is 90°. That is, the scattering angle is 90°. If the scattering angle θ is not to be changed, the rotating part 36 is not necessarily required. For example, a goniometer can be used as the rotating part 36. For example, the scattered light measuring unit 14 is placed on a goniometer which is the rotating part 36, and the scattering angle θ is adjusted by the goniometer.

[0026] As described above, the dynamic light scattering measurement device 10 has a first light source unit 20 and a second light source unit 22 that emit different laser light, enabling dynamic light scattering measurements at different wavelengths. Furthermore, as described above, the dynamic light scattering measurement device 10 has a rotating unit 36 ​​that rotates the scattered light measurement unit 14, enabling dynamic light scattering measurements to be performed by changing the angle of the scattering angle θ, i.e., the scattering angle. The calculation unit 18 determines the particle size distribution for each of the multiple types of particles in a dispersion Lq containing multiple types of particles, based on the intensity of the scattered light detected by the photodetector 34.

[0027] The calculation unit 18 calculates multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data of the measurement parameters from multiple scattering intensity data obtained by the scattered light measurement unit 14. By fitting the calculated multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data of the measurement parameters to a theoretical formula that defines the relationship between particle size and scattering intensity, the calculation unit 18 determines the particle size distribution for each of several types of particle species. In addition to theoretical formulas defining the relationship between particle size and scattering intensity, time-varying data of the scattering intensity of measurement parameters calculated by simulation and parameter-dependent data of the calculated scattering intensity of measurement parameters may also be used.

[0028] Furthermore, the calculation unit 18 calculates multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data of the measurement parameters obtained by the scattered light measurement unit 14. By fitting the calculated multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data of the measurement parameters to a theoretical formula defining the relationship between particle size and scattering intensity, the calculation unit 18 determines the type of particles in the dispersion. If the type of particles in the dispersion can be determined, the calculation unit 18 determines the particle size distribution of each particle in the dispersion. The determination of the type of particles in the dispersion will be described later. The fitting will be described later. The calculation unit 18 calculates the above-mentioned scattering intensity parameter-dependent data based on at least one of the following: the Mie scattering theory formula, the discrete dipole approximation method (DDA method), and the Stokes-Einstein theory formula.

[0029] The calculation unit 18 determines the particle size distribution as described above by executing a program (computer software) stored in ROM (Read Only Memory) or the like on the calculation unit 18. The calculation unit 18 may be composed of a computer in which each part functions when the program is executed as described above, or it may be a dedicated device in which each part is composed of a dedicated circuit, or it may be composed of a server that runs on the cloud.

[0030] When measuring the scattering intensity of a dispersion, the measurement parameters include the scattering angle and the measurement wavelength. If the measurement parameter is the scattering angle, the scattering intensity of the dispersion is measured by changing the scattering angle. If the measurement parameter is the measurement wavelength, change the measurement wavelength and measure the scattering intensity of the dispersion. Furthermore, while the scattering intensity can be measured using a single measuring device in conjunction with the dynamic light scattering measurement method or apparatus as described above, it may also be used in combination with measurement data from two different devices: a dynamic light scattering apparatus and a light scattering goniophotometer. For measurement wavelengths, a spectrometer may also be used. As described above, the apparatus configuration is not limited to, for example, the dynamic light scattering measurement apparatus 10 shown in Figure 1.

[0031] Figure 2 is a graph showing the relationship between scattering intensity and scattering angle, Figure 3 is a schematic diagram of a single particle, and Figure 4 is a schematic diagram of an aggregate formed by cross-linking particles. As shown in Figure 2, the scattering intensity differs depending on the scattering angle between a single particle and an aggregate of particles formed by cross-linking. Figure 2 shows the time-averaged scattering intensity against the scattering angle. Profile 50, which shows the scattering intensity of a single particle as shown in Figure 2, exhibits fluctuations in scattering intensity depending on the scattering angle. Profile 52, which shows the scattering intensity of an aggregate formed by cross-linked particle aggregation, shows a constant value with no fluctuations in scattering intensity depending on the scattering angle.

[0032] As shown in Figure 3, a single particle 51 is composed of one particle, for example, with a diameter of 1000 nm. As shown in Figure 4, an aggregate 53 formed by cross-linking particles is composed of multiple particles 54. The particles 54 constituting the aggregate 53 have a diameter of, for example, 50 nm, but the overall diameter of the aggregate 53 is, for example, 1000 nm. The aggregate 53 shown in Figure 4 is also called a cross-linked aggregate. The aggregate 53 is composed of, for example, particles 54 of a predetermined size and a solvated polymer present between the particles. The polymer is often a polymer having a functional group (for example, a polar group) that causes the particles 54 to aggregate. When comparing a single particle and an aggregate of similar size, a 1000 nm single particle exhibits strong forward scattering and anisotropic scattering, while scattered waves from a 1000 nm bridging aggregate (composed of particles with a diameter of 50 nm) are a superposition of isotropic scattered waves from the constituent particles, resulting in isotropic scattering. Consequently, even if the hydrodynamic diameter obtained by dynamic light scattering is the same 1000 nm, differences in scattering intensity arise depending on the scattering angle.

[0033] As shown in Figure 2, by utilizing the difference in scattering intensity between a single particle and an aggregate with respect to the scattering angle, it is possible to determine the particle size distribution for each of multiple particle types in a dispersion containing particles, even if multiple types of particles are present. Furthermore, the type of particle in the dispersion can be determined by utilizing the difference in scattering intensity with respect to the scattering angle, as shown in Figure 2. The particle size distribution of the determined particles can also be determined. Therefore, the type of particle in the dispersion can be known or unknown.

[0034] The determination of the type of particles in the dispersion based on the difference in scattering intensity with respect to the scattering angle, as described above, is performed by the calculation unit 18. The calculation unit 18 detects, for example, the difference from the theoretical formula for scattering intensity assuming one type of particle, and if there is a difference, it determines that there are multiple types of particles in the dispersion. Assuming that there are multiple types of particles in the dispersion, a theoretical formula is established that defines the relationship between particle size and scattering intensity, and the particle size distribution for each of the multiple particle types is determined. In this way, the particle size distribution for each particle type contained in the dispersion is determined. In addition, the calculation unit 18 may set up a theoretical formula assuming that there are multiple types of particles in the dispersion. In this case, even if there is only one type of particle in the dispersion, the particle size distribution can be determined.

[0035] Here, Figure 5 is a flowchart showing a dynamic light scattering measurement method according to an embodiment of the present invention. As shown in Figure 5, the dynamic light scattering measurement method includes, for example, a measurement step (step S10), a step of obtaining experimental data (step S12), a step of obtaining pre-calculated values ​​(step S14), and an optimization step (step S16). The optimization step (step S16) yields analysis results, i.e., particle size distributions for each of several types of particles (step S18). The measurement step (step S10) measures, for example, the time fluctuation of the scattering intensity, and the scattering angle dependence or wavelength dependence of the time-averaged scattering intensity. The step of obtaining experimental data (step S12) involves obtaining, for example, the time correlation of the scattering intensity with respect to time fluctuations, based on the measurements taken in the measurement step (step S10). It also involves obtaining the time-averaged scattering intensity dependent on the scattering angle, or the time-averaged scattering intensity dependent on the wavelength. This allows, for example, the scattering intensity for each scattering angle shown in Figure 2 to be obtained.

[0036] The step of obtaining pre-calculated values ​​(step S14) involves, for example, obtaining calculated values ​​of scattering intensity using a theoretical formula or simulation that defines the relationship between particle size and scattering intensity. Furthermore, it involves obtaining scattering intensity time variation characteristic data and scattering intensity parameter dependence data of the calculated measurement parameters calculated using a theoretical formula that defines the relationship between particle size and scattering intensity. Alternatively, it involves obtaining scattering intensity time variation characteristic data and scattering intensity parameter dependence data of the calculated measurement parameters calculated by simulation. In step S14, the scattering intensity parameter-dependent data is calculated based on at least one of the following: the Mie scattering theory formula, the discrete dipole approximation method (DDA method), and the Stokes-Einstein theory formula. Alternatively, numerical values ​​of the scattering intensity and scattering intensity parameter-dependent data may be obtained using the FDTD (Finite-difference time-domain) method, which is a known numerical calculation method. In step S14, measured values ​​of the scattering intensity using known particles such as standard particles may also be obtained. The pre-calculated values ​​obtained in step S14 are used to identify the particles or particle species. Furthermore, the particle aggregation state or particle species can be determined by comparing the measured values ​​obtained in step S10 with the particle scattering characteristics in step S14, for example.

[0037] In the optimization step (step S16), for example, the autocorrelation function and the theoretical formula for scattering intensity are fitted to the time correlation of the time fluctuations of scattering intensity and the time-averaged value of the scattering intensity obtained in step S12. In step S16, initial values ​​are set for the number of particles for all particle sizes, and then the evaluation values ​​are updated to minimize them to obtain the final number of particles. The following provides a more detailed explanation of the dynamic light scattering measurement method, including the fitting process.

[0038] (First example of a dynamic light scattering measurement method) In dynamic light scattering measurement methods, the scattering intensity of a dispersion is measured using scattering angle and wavelength as measurement parameters. In the first example of a dynamic light scattering measurement method, the measurement parameter is the scattering angle, and the scattering intensity of the dispersion is measured by changing the scattering angle.

[0039] First, a laser beam with a wavelength of, for example, 633 nm is irradiated onto the dispersion liquid Lq from the second light source unit 22 shown in Figure 1. The scattered light is detected by the photodetector unit 34 at a predetermined scattering angle for a predetermined time. This allows the scattering intensity of the dispersion liquid Lq at the scattering angle to be obtained. Next, the rotating unit 36 ​​rotates the scattered light measuring unit 14 to change the scattering angle θ and obtain the scattering intensity of the dispersion Lq. The scattering angle is changed and the scattering intensity of the dispersion Lq is measured repeatedly, and the scattering intensity of the dispersion Lq is measured multiple times. The scattering angle is changed, for example, in increments of 10° and the scattering intensity is measured. The above steps constitute the measurement process and correspond to step S10 described above.

[0040] Next, the calculation unit 18 calculates scattering intensity time variation characteristic data from the time dependence of the scattering intensity of the dispersion Lq obtained in the measurement step. The scattering intensity time variation characteristic data is either an autocorrelation function or a power spectrum. The autocorrelation function is calculated from the scattering intensity of the dispersion using a known method. The power spectrum is also calculated from the scattering intensity of the dispersion using a known method. In this way, time variation characteristic data of scattering intensity can be obtained for each scattering angle. In other words, there are multiple time variation data. Next, the calculation unit 18 calculates scattering intensity parameter-dependent data from the scattering intensity of the dispersion obtained in the measurement process. Parameter-dependent data for the scattering intensity of the dispersion can be obtained, for example, by calculating the time-averaged scattering intensity of the dispersion for each scattering angle. This yields scattering intensity data for each scattering angle, as shown in Figure 2. The calculation step involves calculating the scattering intensity time variation characteristic data of the dispersion and the scattering intensity parameter-dependent data of the dispersion, and corresponds to step S12 described above.

[0041] Next, the calculation unit 18 fits the time variation characteristic data of scattering intensity for multiple scattering angles and the scattering intensity parameter-dependent data for multiple scattering angles to a theoretical formula that defines the relationship between particle size and scattering intensity. The particle size distribution for each of the multiple types of particles is determined by the above fitting. This corresponds to steps S16 and S18 described above. Specifically, let's explain using the example of a dispersion containing two types of particles. The first-order autocorrelation function is g (1) (τ) = exp(-Dq)2 It is represented by τ). The relationship between the diffusion coefficient obtained from the autocorrelation function and the particle size is applied with the Stokes-Einstein formula used in the normal dynamic light scattering method.

[0042] When there are two types of particle species in the dispersion liquid, the first-order autocorrelation function is represented by the following formula (1). Also, the scattering intensity is represented by the following formula (2). The following formulas (1) and (2) are theoretical formulas, and the I in formulas (1) and (2) total are both calculated values. Also, I d single and I d floc are theoretical values, and the pre-calculated values obtained in the above step S14 can be used. In the following formulas (1) and (2), g (1) represents the first-order autocorrelation function. I total represents the total scattering intensity. d represents the particle size. The subscripts 0 to M of d indicate the bin ordinal numbers of the histograms shown in FIGS. 6 and 7. N represents the number of particles. The subscript d of N represents dependence on the particle size d. Note that the bin of the histogram is the data interval of the histogram and is shown as a bar in the histogram. The superscript single of the number of particles N represents the number of single particles in FIG. 3, and the superscript floc represents the number of particles in the aggregate in FIG. 4. Also, D represents the diffusion coefficient. The subscript d of the diffusion coefficient D represents dependence on the particle size d. q represents the scattering vector. τ represents the time lag of the first-order autocorrelation function. θ represents the scattering angle. I represents the scattering intensity. The subscript d of the scattering intensity I represents dependence on the particle size d. The superscript single of the scattering intensity I represents the scattering intensity based on the single-particle model in FIG. 3, and the superscript floc represents the scattering intensity based on the aggregate model in FIG. 4.

[0043]

Equation

[0044] In equation (1) above, the following term corresponds to a single particle and corresponds to the histogram of a single particle shown in Figure 6. In the following term, exp(-Dq 2 τ) is the first-order autocorrelation function corresponding to the particle size d, and the other N d single I d single / I total The part represents the ratio of the scattering intensity by all single particles belonging to the bottle of particle size d to the total scattering intensity. In other words, it is the weighting of single particles. Note that I in equation (1) total This is a theoretical value determined by the particle size.

[0045]

number

[0046] In equation (1) above, the following term corresponds to aggregates formed by cross-linking of particles, and corresponds to the histogram of aggregates shown in Figure 7. In the following term, exp(-Dq 2 τ) is the first-order autocorrelation function, and other N d floc I d floc / I total The part indicated by the symbol represents the ratio of the scattering intensity due to all aggregates belonging to the bottle with particle size d to the total scattering intensity. In other words, it is the weighting of the aggregates.

[0047]

number

[0048]

number

[0049] In equation (2) above, N d single I d single This corresponds to the scattering intensity of all single particles belonging to the bottle with particle size d, and N d floc Id floc This corresponds to the scattering intensity of the total aggregate formed by cross-linked particle aggregation, belonging to the bottle with particle size d.

[0050] <First example of fitting> The following describes the fitting process for determining the particle size distribution for multiple types of particles. In the fitting process, the number of particles for each particle size is used as a variable, and the final number of particles for each particle size is determined. Second-order autocorrelation function g (2) (τ) has been measured for each scattering angle, and there are multiple values ​​for it. In the fitting process, for each scattering angle, the number of particles is used as a variable in equation (1) to set the initial number of particles. The calculated value of the first-order autocorrelation function in equation (1) is obtained based on the set initial number of particles. From the calculated value of the first-order autocorrelation function, the second-order autocorrelation function g is obtained. (2) (τ) = 1 + β·|g (1) (τ)| 2 Calculate the value of β. Note that β is the device constant. For each scattering angle, the difference between the measured value of the second-order autocorrelation function and the calculated value of the second-order autocorrelation function is determined. This difference between the measured value and the calculated value of the second-order autocorrelation function is called the difference in the second-order autocorrelation function. The difference in the second-order autocorrelation function is obtained for each scattering angle. The calculated value of the second-order autocorrelation function for each scattering angle corresponds to the scattering intensity time variation characteristic data of the measurement parameters calculated using the theoretical formula.

[0051] Total scattering intensity I total This has been measured for each scattering angle. In equation (2), the total scattering intensity I of equation (2) is based on the set initial number of particles. total Find the value of this. For each scattering angle, the measured total scattering intensity I is as shown in Figure 2. total The value of and the total scattering intensity I in equation (2) total The difference between this value and the calculated value is calculated. Note that the measured total scattering intensity I at any scattering angle is calculated. total The value of and the total scattering intensity I in equation (2) total The difference from the calculated value is the total scattering intensity I at the scattering angle.total This is called the difference in total scattering intensity I total Regarding the total scattering intensity I at the scattering angle, total The difference is obtained. Total scattering intensity I in equation (2) total The calculated value corresponds to the scattering intensity parameter-dependent data of the measurement parameter calculated by the theoretical formula.

[0052] In the fitting process, the difference between the second-order autocorrelation functions obtained for each scattering angle and the difference in total scattering intensity at each scattering angle are used to determine the final particle number. For example, an evaluation value is obtained by summing the square of the difference between the second-order autocorrelation functions obtained for each scattering angle and the square of the difference in total scattering intensity at each scattering angle for all scattering angles. The particle number that minimizes this evaluation value is taken as the final particle number. Therefore, in the fitting process, the number of particles is repeatedly updated in equations (1) and (2) to minimize the evaluation value, and the final number of particles is obtained. This corresponds to step S16 described above. After setting initial values ​​for the number of particles for all particle sizes, the evaluation value is updated to minimize it. For example, a histogram of a single particle shown in Figure 6 and a histogram of an aggregate formed by cross-linking particles shown in Figure 7 can be obtained. That is, N d single , N d floc For all d=d0~d M By determining this, the particle size distribution can be obtained. This corresponds to step S18 described above. The particle size distribution is the distribution of the number of particles against the particle size, and for example, the unit is expressed in percent. The above steps describe the process for determining the particle size distribution for each of several types of particle species. Note that the evaluation values ​​used for fitting are not limited to those described above.

[0053] As described above, the two theoretical equations, equations (1) and (2), are used in relation to the experimentally measured second-order autocorrelation function and the experimentally measured total scattering intensity I totalThe final number of particles is determined by fitting the model to the model. However, the optimization method for the fitting is not limited to the one described above; for example, Bayesian optimization can be used for the fitting. As mentioned above, a second-order autocorrelation function was used to determine the number of particles, but this is not the only method; a power spectrum can also be used instead. Furthermore, if a first-order autocorrelation function is measured using heterodyne detection, that function may also be used. As described above, by fitting the autocorrelation function or power spectrum of the scattering intensity to a theoretical formula for each scattering angle, the number of particles and particle size distribution for single particles and aggregates can be obtained. Furthermore, if the dispersion contains impurity components, the impurity components and the particle size distribution for each particle type can be obtained, thus separating the influence of the impurity components. In addition to theoretical formulas, the scattering intensity time variation characteristic data of the measurement parameters calculated by simulation and the scattering intensity parameter dependence data of the calculated measurement parameters can also be used for fitting.

[0054] (Second example of a dynamic light scattering measurement method) In dynamic light scattering measurement methods, if the measurement parameter is the measurement wavelength, the measurement wavelength is changed and the scattering intensity of the dispersion is measured. The second example of the dynamic light scattering measurement method differs from the first example of the dynamic light scattering measurement method described above in that the measurement parameter is the measurement wavelength, the scattering angle θ (see Figure 1) is fixed, and there is only one scattering angle. Here, Figures 8 and 9 show the relationship between scattering intensity and measurement wavelength. Figure 8 shows the scattering intensity of two types of particles calculated at a measurement wavelength of 488 nm. As shown in Figure 8, the scattering intensity profile 56 of particle A and the scattering intensity profile 57 of particle B are different. Figure 9 shows the scattering intensities of two types of particles calculated at a measurement wavelength of 632.8 nm. As shown in Figure 9, the scattering intensity profile 58 of particle A and the scattering intensity profile 59 of particle B are different. As shown in Figures 8 and 9, the scattering intensity with respect to the measurement wavelength differs depending on the type of particle. This can be used to determine the number of particles. Particle A is a PY74 (CI Pigment Yellow 74) particle, and particle B is a polystyrene particle.

[0055] A second example of a dynamic light scattering measurement method involves changing the measurement wavelength as the measurement parameter to measure the scattering intensity of the dispersion. First, a laser beam with a wavelength of, for example, 488 nm is irradiated onto the dispersion liquid Lq from the first light source unit 20 shown in Figure 1. The scattered light is detected by the photodetector unit 34 for a predetermined time at a scattering angle of, for example, 90°. This allows the scattering intensity of the dispersion liquid Lq based on the laser beam from the first light source unit 20 to be obtained. Next, the second light source unit 22 irradiates the dispersion liquid Lq with laser light, for example, with a wavelength of 633 nm. The scattered light is detected by the photodetector unit 34 for a predetermined time at a scattering angle of, for example, 90°. This allows the scattering intensity of the dispersion liquid based on the laser light from the second light source unit 22 to be obtained. The above steps constitute the measurement process. For example, the laser light from the first light source unit 20 has a wavelength of 488 nm, and the laser light from the second light source unit 22 has a wavelength of 633 nm, so the measurement wavelengths are different.

[0056] Next, the scattering intensity time variation characteristic data is calculated from the time dependence of the scattering intensity of the dispersion obtained in the measurement process. The scattering intensity time variation characteristic data is either an autocorrelation function or a power spectrum. In this way, scattering intensity time variation characteristic data for each wavelength is obtained. Next, the scattering intensity parameter-dependent data is calculated from the scattering intensity of the dispersion obtained in the measurement process. The scattering intensity parameter-dependent data for the dispersion can be obtained, for example, by calculating the time-averaged scattering intensity of the dispersion for each laser light wavelength. This allows for obtaining scattering intensity data for each measurement wavelength. The calculation step involves calculating the scattering intensity time variation characteristic data of the dispersion and the scattering intensity parameter-dependent data of the dispersion, and corresponds to step S12 described above.

[0057] Next, the time variation characteristic data of scattering intensity at multiple scattering angles and the scattering intensity parameter-dependent data at multiple scattering angles are fitted using theoretical formulas. The particle size distribution for each of the multiple types of particles is determined by the above fitting. This corresponds to steps S16 and S18 described above. When there are two types of particles, particle A and particle B, in a dispersion, the first-order autocorrelation function is given by equation (3) below. The scattering intensity is given by equation (4) below. Equations (3) and (4) below are theoretical formulas, and the I of equations (3) and (4) total These are all calculated values. Also, I d A and I d B This is a theoretical value, and the pre-calculated value obtained in step S14 described above can be used. Equation (3) below is basically the same as equation (1) in the first example of the dynamic light scattering measurement method, and equation (4) below is basically the same as equation (2) in the first example of the dynamic light scattering measurement method. In equations (3) and (4) below, the superscripts A and B indicate that the scattering intensity wavelength dependence corresponds to particle A and particle B.

[0058]

number

[0059] In equation (3) above, the following term corresponds to particle A, and corresponds to the histogram of particle A shown in Figure 10. In the following term, exp(-Dq 2 τ) is the first-order autocorrelation function, and other N d A I d A / I totalThe part in parentheses represents the ratio of the scattering intensity by all particles A belonging to the bottle with particle size d to the total scattering intensity. In other words, it is the weighting of particle A. Note that in equation (3), I total This is a theoretical value determined by the particle size. The Mie scattering theory formula can be used as the theoretical value.

[0060]

number

[0061] In equation (3) above, the following term corresponds to particle B, and corresponds to the histogram of particle B shown in Figure 11. In the following term, exp(-Dq 2 τ) is the first-order autocorrelation function, and other N d B I d B / I total The part indicated by the symbol represents the ratio of the scattering intensity due to all particles B belonging to the bottle with particle size d to the total scattering intensity. In other words, it is the weighting of particle B.

[0062]

number

[0063]

number

[0064] In equation (4) above, N d A I d A This corresponds to the scattering intensity of all particles A belonging to the bottle with particle size d, and N d B I d B This corresponds to the scattering intensity of all particles B belonging to the bottle with particle size d.

[0065] <Second example of fitting> The fitting for obtaining the particle size distribution for each of a plurality of types of particle species will be described below. In the fitting, the number of particles is used as a variable, and finally the number of particles for each particle diameter is obtained. The second-order autocorrelation function g (2) (τ) has been actually measured for each measurement wavelength, and there are a plurality of them. In the fitting, for the first-order autocorrelation function for each measurement wavelength, in Equation (3), with the number of particles as a variable, an initial number of particles is set. The calculated value of the first-order autocorrelation function in Equation (3) based on the set initial number of particles is obtained. From the calculated value of the first-order autocorrelation function, the second-order autocorrelation function g (2) (τ)=1+β·|g (1) (τ)| 2 of the calculated value is obtained. Here, β is an apparatus constant. For each measurement wavelength, the difference between the actually measured value of the second-order autocorrelation function and the calculated value of the second-order autocorrelation function is obtained. Note that the difference between the actually measured value of this second-order autocorrelation function and the calculated value of the second-order autocorrelation function is referred to as the difference of the second-order autocorrelation function. The difference of the second-order autocorrelation function is obtained for each measurement wavelength. The calculated value of the second-order autocorrelation function for each measurement wavelength corresponds to the scattered intensity time-variation characteristic data of the measurement parameters calculated by the theoretical formula.

[0066] The total scattered intensity I total has been actually measured for each measurement wavelength. In Equation (4), the value of the total scattered intensity I total in Equation (4) based on the set initial number of particles is obtained. For each measurement wavelength, the difference between the actually measured value of the total scattered intensity I total and the calculated value of the total scattered intensity I total in Equation (4) is obtained. Note that, for an arbitrary measurement wavelength, the difference between the actually measured value of the total scattered intensity I total and the calculated value of the total scattered intensity I total in Equation (4) is referred to as the difference of the total scattered intensity I total at the measurement wavelength. For the total scattered intensity I total , the difference of the total scattered intensity I total at the measurement wavelength is obtained. The calculated value of the total scattered intensity I total in Equation (4) corresponds to the scattered intensity parameter-dependent data of the measurement parameters calculated by the theoretical formula.

[0067] Similar to the first example of the dynamic light scattering measurement method, the fitting process uses the difference in the second-order autocorrelation function obtained for each measurement wavelength and the difference in the total scattering intensity at the measurement wavelength to determine the final number of particles. For example, the evaluation value obtained by summing the square of the difference in the second-order autocorrelation function obtained for each measurement wavelength and the square of the difference in the total scattering intensity at the measurement wavelength for all measurement wavelengths is used. The number of particles that minimizes this evaluation value is taken as the final number of particles. Therefore, in the fitting process, the number of particles is repeatedly updated in equations (3) and (4) to minimize the evaluation value, and the final number of particles is obtained. This corresponds to step S16 described above.

[0068] After setting initial values ​​for the number of particles for all particle sizes, the evaluation value is updated to minimize it. For example, the histogram of particle A shown in Figure 10 and the histogram of particle B shown in Figure 11 can be obtained. That is, N d A , N d B For all d=d0~d M By determining this, the particle size distribution can be obtained. This corresponds to step S18 described above. The above steps describe the process for determining the particle size distribution for each of several types of particle species. Note that the evaluation values ​​used for fitting are not limited to those described above. Furthermore, the calculation unit 18 can determine the type of particles in the dispersion by utilizing the difference in scattering intensity with respect to the measurement wavelength, as shown in Figure 8 or Figure 9. The particle size distribution of the determined particles can also be calculated. For this reason, the type of particles in the dispersion may be known or unknown.

[0069] Similar to the first example of the dynamic light scattering measurement method, the two theoretical equations, equations (3) and (4), as described above, are used with respect to the measured second-order autocorrelation function and the measured total scattering intensity I totalThe final number of particles is determined by fitting the model to the model. However, the optimization method for the fitting is not limited to the one described above; for example, Bayesian optimization can be used for the fitting. As mentioned above, a second-order autocorrelation function was used to determine the number of particles, but this is not the only method; a power spectrum can be used instead of a first-order autocorrelation function. Furthermore, if a first-order autocorrelation function is measured using heterodyne detection, that function may also be used. Furthermore, as described above, by fitting the autocorrelation function or power spectrum of the scattering intensity to the theoretical formula for each measurement wavelength, the number of particles and the particle size distribution for each particle type, such as particle A and particle B, can be obtained. In addition, if the dispersion contains impurity components, the impurity components and the particle size distribution for each particle type can be obtained, thus separating the effect of the impurity components. Note that, in addition to theoretical formulas, the scattering intensity time variation characteristic data of the measurement parameters calculated by simulation and the scattering intensity parameter dependence data of the calculated measurement parameters can also be used for fitting. Although I have explained two examples of measurement wavelengths, the measurement wavelengths are not limited to two; if there are multiple wavelengths, there could be three, four, or any other.

[0070] (Third example of a dynamic light scattering measurement method) The measurement process may involve irradiating the dispersion with incident light of a specific polarization and measuring the light intensity of the polarization component of the scattered light of the dispersion as the scattering intensity. This measurement process is performed by the scattered light measurement unit 14. For example, circularly polarized laser light is irradiated onto the dispersion Lq of sample cell 16 as incident light, and the polarization component of the scattered light of the dispersion Lq is measured. For example, the light intensity of the polarization component of the scattered light is measured as the difference between the light intensity of vertically linearly polarized light and the light intensity of horizontally linearly polarized light. In this case, as in the first example of the dynamic light scattering measurement method described above, by changing the scattering angle during measurement, a graph showing the relationship between scattering intensity and scattering angle, as shown in Figure 12, can be obtained. Furthermore, perpendicular linear polarization refers to the direction of linear polarization being perpendicular when the scattering surface is considered horizontal. Horizontal linear polarization refers to the direction of linear polarization being horizontal when the scattering surface is considered horizontal.

[0071] Figure 12 is a graph showing the relationship between scattering intensity and scattering angle for each particle shape obtained by the DDA method. Figure 12 shows the relationship between scattering intensity and scattering angle for spherical particles shown in Figure 13 and disc-shaped particles shown in Figure 14. As shown in Figure 12, the scattering intensity profile 60 for spherical particles and the scattering intensity profile 61 for disc-shaped particles are different. Thus, the change in scattering intensity with respect to the scattering angle differs depending on the particle shape. In other words, for each of the multiple types of particles, the scattering intensity profile obtained by changing the scattering angle, for example, will be different as a value of the measurement parameter. By measuring the polarization component of the scattered light using a laser beam polarized as incident light, the differences in particle shapes can be determined from the differences in the scattering intensity profiles.

[0072] Furthermore, a third example of the dynamic light scattering measurement method uses a laser beam polarized as the incident light, measures the polarization component of the scattered light, and, in the same manner as the first example of the dynamic light scattering measurement method described above, can determine the particle size distribution for each of the multiple types of particles in a dispersion containing multiple types of particles. Furthermore, if the types of particles in the dispersion can be determined, the particle size distribution of each particle in the dispersion can be calculated. Furthermore, as described above, by incidenting polarized light as incident light into the dispersion, detecting the light intensity of the polarization component of the scattered light as the scattering intensity, and combining this with at least one of the scattering angle and measurement wavelength described above, it is possible to determine the particle size distribution for multiple types of particles, even for particles with different shapes. In addition, if the dispersion contains impurity components, the effect of the impurity components can be separated, and the particle size distribution for multiple types of particles can be determined. For fitting, in addition to theoretical formulas, scattering intensity time variation characteristic data of measurement parameters calculated by simulation and scattering intensity parameter dependence data of calculated measurement parameters can also be used. Furthermore, by using polarization and utilizing the difference in scattering intensity with respect to scattering angle as shown in Figure 12, the calculation unit 18 can determine the type of particles in the dispersion, for example, their shape. The particle size distribution of the determined particles can also be calculated. Therefore, the shape of the particles in the dispersion may be known or unknown.

[0073] As described above, when polarization is used, for example, when the scattering angle is used as the measurement parameter, equations (1) and (2) above can be used. Furthermore, when polarization is used as described above, for example, when the measurement wavelength is used as the measurement parameter, equations (3) and (4) above can be used. Furthermore, the first example of the dynamic light scattering measurement method described above and the second example of the dynamic light scattering measurement method may be combined. That is, the particle size distribution for each of several types of particles can be determined using the scattering angle and measurement wavelength described above as measurement parameters. In this case as well, if the dispersion contains impurity components, the impurity components and the particle size distribution for each particle type can be obtained, thus separating the effect of the impurity components.

[0074] Furthermore, the measurement process may involve measuring at least one of the following: scattering intensity parameter-dependent data obtained by sequentially irradiating the dispersion with incident light in multiple polarization states, and scattering intensity measurement parameter-dependent data obtained by extracting multiple polarization components of scattered light emitted from the dispersion. This measurement process is performed by the scattered light measurement unit 14 and the polarizing element 28. The scattering intensity parameter-dependent data obtained by sequentially irradiating a dispersion with incident light in multiple polarization states assumes the incident light is in a polarized state. Furthermore, the scattering intensity parameter-dependent data obtained by extracting multiple polarization components of scattered light emitted from the dispersion does not assume the incident light is in a polarized state, but rather detects the polarization components of the scattered light. The above-mentioned scattering intensity parameter-dependent data also includes cases where the incident light is in a polarized state and the polarization components of the scattered light are detected. For example, if the measurement parameter is the scattering angle, the polarization state of the incident light is circularly polarized, and the polarization component of the scattered light is the difference between the vertical polarization intensity and the horizontal polarization intensity, then the scattering intensity parameter-dependent data shown in Figure 15 can be obtained. Profile 62 in Figure 15 represents the spherical particles in Figure 13, and profile 63 represents the disc-shaped particles in Figure 14. Furthermore, for example, if the measurement parameter is the scattering angle, the polarization state of the incident light is set to 45° linear polarization, and the polarization component of the scattered light is the sum of the vertical polarization intensity and the horizontal polarization intensity, the scattering intensity parameter-dependent data shown in Figure 16 can be obtained. Profile 64 in Figure 16 represents the spherical particles in Figure 13, and profile 65 represents the disc-shaped particles in Figure 14.

[0075] The scattering intensity parameter-dependent data shown in Figure 15 may be used for the fitting described above. Alternatively, the scattering intensity parameter-dependent data shown in Figure 16 may be used for the fitting described above. Furthermore, both the scattering intensity parameter-dependent data shown in Figure 15 and the scattering intensity parameter-dependent data shown in Figure 16 may be used for the fitting described above. In this way, the scattering intensities for multiple incident polarization states and multiple outgoing polarization states may be combined and fitted. As shown in Figures 15 and 16, the scattering intensity parameter-dependent data obtained depending on the polarization state shows different trends. By utilizing the differences in scattering intensity parameter-dependent data depending on the polarization state and performing fitting, it is possible to determine the type of particles in the dispersion, such as their shape, with higher accuracy, and to determine the particle size distribution of the determined particles. Note that while the scattering intensity parameter-dependent data shown in Figures 15 and 16 above use the scattering angle as the measurement parameter, the measurement parameter is not limited to the scattering angle; it may also be the measurement wavelength.

[0076] In any of the first, second, and third examples of the dynamic light scattering measurement method described above, if it is not known that a dispersion containing particles contains multiple types of particles, a determination step may be included to determine the types of particles in the dispersion. If the determination step can determine the types of particles in the dispersion, a step may be performed to determine the particle size distribution of each type of particle in the dispersion. The determination step is performed by the calculation unit 18. The determination process involves using the theoretical formula described above to perform fitting. When the measurement parameter is the scattering angle, for example, it detects the difference between the theoretical formula for scattering intensity assuming one type of particle and the theoretical formula for scattering intensity. If a difference is found, it is determined that there are multiple types of particles in the dispersion. For particle type determination, for example, theoretical formulas for the scattering intensity of particle A, particle B, and particle C are stored in a library (not shown) of the calculation unit 18 (see Figure 1). When determining particle type, the calculation unit 18 calls up the above-mentioned theoretical formulas for scattering intensity, attempts fitting, and calculates the minimum value of the evaluation value through optimization. The particle type with the smallest minimum evaluation value is determined to be the actual correct particle type. Furthermore, if the measurement parameter is the measurement wavelength, the determination process can detect differences in scattering intensity depending on the measurement wavelength, and if there is a difference, it can be determined that there are multiple types of particles in the dispersion. Furthermore, the determination process uses polarization to detect differences in scattering intensity based on the scattering angle. If a difference is found, it can be determined that there are multiple types of particles with different shapes in the dispersion.

[0077] In addition, the term "multiple types of particles" refers to various aspects such as the aggregate structure, particle material, and particle shape. These multiple types of particles include the single particles, aggregates formed by cross-linking particles, polystyrene particles, spherical particles, disc-shaped particles, etc.

[0078] The present invention is basically configured as described above. Although the dynamic light scattering measurement method and dynamic light scattering measurement apparatus of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various improvements or modifications may be made without departing from the spirit of the present invention. [Examples]

[0079] The features of the present invention will be further described in detail below with reference to examples. The materials, reagents, amounts and proportions of substances, and procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following examples. In the first embodiment, dynamic light scattering measurements of a dispersion containing particles were performed using the scattering angle as the measurement parameter. This was designated as Example 1. Samples 1 to 4 below were used as the dispersion. Sample 1 is a dispersion using pure water as the solvent and silica as the particles. Sample 2 is a dispersion prepared using pure water as the solvent, silica as the particles, and 0.3 mg / ml of PVP (polyvinylpyrrolidone, molecular weight Mw=1,300,000) added. Sample 3 is a dispersion prepared using pure water as the solvent, silica as the particles, and with the addition of 1 mg / ml of PVP. Sample 4 is a dispersion prepared using pure water as the solvent, silica as the particles, and with the addition of 10 mg / ml of PVP. The particle concentrations in samples 1-4 were all 1.3% by volume. Adding PVP causes silica particles to aggregate, and the degree of aggregation increases with the amount of PVP added. Samples 2-4 have PVP added, so the silica particles are aggregated. In Example 1, the results for Sample 1 are shown in Figure 17, the results for Sample 2 are shown in Figure 18, the results for Sample 3 are shown in Figure 19, and the results for Sample 4 are shown in Figure 20. In Figures 17 to 20, □ represents a single silica particle, and ◆ represents a crosslinked aggregate.

[0080] As Comparative Example 1, a conventional dynamic light scattering measurement was performed. In the conventional dynamic light scattering measurement, the scattering angles were set to 50°, 90°, and 150°. The scattered light intensity was measured at scattering angles of 50°, 90°, and 150°, and the autocorrelation function was determined. The number of particles was then determined by fitting a theoretical formula to the autocorrelation function. In Comparative Example 1, the results for Sample 1 are shown in Figure 21, the results for Sample 2 are shown in Figure 22, the results for Sample 3 are shown in Figure 23, and the results for Sample 4 are shown in Figure 24. Note that the particle numbers shown in Figures 21 to 24 represent the number of particles with hydrodynamic diameters determined solely from dynamic light scattering.

[0081] Sample 1 does not show aggregated silica particles. In Example 1, as shown in Figure 17, the result obtained was that Sample 1 was a single particle. On the other hand, in Comparative Example 1, as shown in Figure 21, it is not possible to determine whether it is a single particle or a cross-linked aggregate, so only the hydrodynamic diameter is indicated. Samples 2-4 show aggregated silica particles. In Example 1, as shown in Figures 18-20, there are two distributions with different diameters; one corresponds to a single silica particle, and the other corresponds to a cross-linked aggregate. On the other hand, in Comparative Example 1, as shown in Figures 22-24, there is only one distribution, and although the generation of large-diameter particles is captured, it is not possible to distinguish whether they are single particles or cross-linked aggregates, so only the hydrodynamic diameter is shown. [Examples]

[0082] In the second example, as Example 10, dynamic light scattering measurements of a dispersion containing particles were performed using the measurement wavelength as the measurement parameter. The measurement wavelengths were 488 nm and 632.8 nm. The dispersions used were samples 10 to 12 listed below. Sample 10 is a dispersion using pure water as the solvent and PY74 (CI Pigment Yellow 74) as the particles. Only one type of particle was used. The particle concentration in Sample 10 was 0.00272% by mass. Sample 11 is a dispersion using pure water as the solvent and polystyrene (PS) as the particles. Only one type of particle is used. The particle concentration in Sample 11 was 0.0013% by mass. Sample 12 is a dispersion using pure water as the solvent and PY74 and PS as particles. There are two types of particles. The particle concentrations in Sample 12 were 0.000068 mass% for PY74 and 0.0013 mass% for PS. In Example 10, the results for Sample 10 are shown in Figure 25, the results for Sample 11 are shown in Figure 26, and the results for Sample 12 are shown in Figure 27.

[0083] As Comparative Example 10, a conventional dynamic light scattering measurement was performed. In the conventional dynamic light scattering measurement, the measurement wavelengths were 488 nm and 632.8 nm. The scattered light intensity was measured at each measurement wavelength, the autocorrelation function was determined, and the number of particles was determined by fitting a theoretical formula to the autocorrelation function. Samples 10 to 12 were used as the dispersion. In Comparative Example 10, the results for Sample 10 are shown in Figure 28, the results for Sample 11 are shown in Figure 29, and the results for Sample 12 are shown in Figure 30. The particle numbers shown in Figures 28 to 30 represent the number of particles with hydrodynamic diameters determined solely from dynamic light scattering. In Figures 25 to 30, □ represents PY74 particles, and ◆ represents PS particles.

[0084] In Example 10, as shown in Figures 25 and 26, the particle size distribution was obtained by treating samples 10 and 11, which consist of one type of particle, as one type of particle. Also, as shown in Figure 27, the particle size distribution was obtained by treating sample 12, which consists of two types of particle, as two types of particle. On the other hand, in Comparative Example 10, as shown in Figures 28 and 29, the particle type cannot be determined in the first place, so only the hydrodynamic diameter is indicated. Also, as shown in Figure 30, the particle type cannot be determined in the first place, so only the hydrodynamic diameter is indicated. [Explanation of Symbols]

[0085] 10 Dynamic light scattering measurement device 12 Incidence setting section 13 Parameter setting section 14 Scattered light measurement section 16 sample cells 18 Arithmetic section 20 1st light source section 22 Second light source section 24 Half Mirror 26, 32 Focusing lenses 28, 30 Polarizing elements 34 Light detection unit 36 Rotating part Profiles 50, 52, 56, 57, 58, 59, 60, 61 51 Single Particle 53 Aggregates 54 particles C1 optical axis θ scattering angle

Claims

1. A method for measuring the dynamic light scattering of a dispersion containing multiple types of particles, A measurement step to obtain multiple scattering intensity data by measuring the scattering intensity of the dispersion multiple times while changing the value of at least one of the measurement parameters, the scattering angle and the measurement wavelength, A calculation step is performed to calculate a plurality of scattering intensity time variation characteristic data and a plurality of scattering intensity parameter-dependent data from the plurality of scattering intensity data obtained by the measurement step. The process includes a step of determining the particle size distribution for each of the multiple types of particles by fitting the multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data obtained in the calculation step to a theoretical formula that defines the relationship between particle size and scattering intensity. A dynamic light scattering measurement method in which the scattering intensity profile obtained by changing the value of the measurement parameter differs for each of several types of particle species.

2. A method for measuring the dynamic light scattering of a dispersion containing particles, A measurement step to obtain multiple scattering intensity data by measuring the scattering intensity of the dispersion multiple times while changing the value of at least one of the measurement parameters, the scattering angle and the measurement wavelength, A calculation step is performed to calculate a plurality of scattering intensity time variation characteristic data and a plurality of scattering intensity parameter-dependent data from the plurality of scattering intensity data obtained by the measurement step. A determination step is performed to determine the type of particles contained in the dispersion by fitting the plurality of scattering intensity time variation characteristic data and plurality of scattering intensity parameter-dependent data obtained in the calculation step to a theoretical formula that defines the relationship between particle size and scattering intensity. The process includes determining the particle size distribution for each type of particle in the dispersion determined by the determination step, A dynamic light scattering measurement method in which the scattering intensity profile obtained by changing the value of the measurement parameter differs for each of several types of particle species.

3. The dynamic light scattering measurement method according to claim 1 or 2, wherein the measurement parameter is the scattering angle.

4. The dynamic light scattering measurement method according to claim 1 or 2, wherein the measurement parameter is the measurement wavelength.

5. The dynamic light scattering measurement method according to claim 1 or 2, wherein the measurement parameters are the scattering angle and the measurement wavelength.

6. The method for measuring dynamic light scattering according to any one of claims 1 to 5, wherein the measurement step involves irradiating the dispersion with incident light of a specific polarization and measuring the light intensity of the polarization component of the scattered light of the dispersion as the scattering intensity.

7. The method for measuring dynamic light scattering according to any one of claims 1 to 5, wherein the measurement step involves measuring at least one of the scattering intensity parameter-dependent data obtained by sequentially irradiating the dispersion with incident light in multiple polarization states, and the scattering intensity parameter-dependent data obtained by extracting multiple polarization components of scattered light emitted from the dispersion.

8. The dynamic light scattering measurement method according to any one of claims 1 to 7, wherein the calculated scattering intensity time variation characteristic data of the measurement parameter and the scattering intensity parameter dependence data of the measurement parameter are calculated based on at least one of the Mie scattering theory formula, the discrete dipole approximation method, and the Stokes-Einstein theory formula.

9. A dynamic light scattering measurement device for a dispersion containing multiple types of particles, The measurement parameters include a parameter setting unit that changes at least one of the following values: scattering angle and measurement wavelength. The parameter setting unit measures the scattering intensity of the dispersion multiple times while changing the value of at least one of the measurement parameters, the scattering angle and the measurement wavelength, to obtain multiple scattering intensity data, and the scattered light measurement unit The system includes a calculation unit which calculates multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data from the multiple scattering intensity data obtained by the scattering light measurement unit, and then fits the calculated multiple scattering intensity time variation characteristic data and the multiple scattering intensity parameter-dependent data to a theoretical formula defining the relationship between particle size and scattering intensity to determine the particle size distribution for each of the multiple types of particles, A dynamic light scattering measurement device in which the scattering intensity profile obtained by changing the value of the measurement parameter differs for each of several types of particle species.

10. A dynamic light scattering measurement device for a dispersion containing particles, The measurement parameters include a parameter setting unit that changes at least one of the following values: scattering angle and measurement wavelength. The parameter setting unit measures the scattering intensity of the dispersion multiple times while changing the value of at least one of the measurement parameters, the scattering angle and the measurement wavelength, to obtain multiple scattering intensity data, and the scattered light measurement unit The system includes a calculation unit which calculates multiple scattering intensity time variation characteristic data and multiple scattering intensity parameter-dependent data from the multiple scattering intensity data obtained by the scattered light measurement unit, and determines the type of particles in the dispersion by fitting the calculated multiple scattering intensity time variation characteristic data and the multiple scattering intensity parameter-dependent data to a theoretical formula that defines the relationship between particle size and scattering intensity, and if the type of particles in the dispersion can be determined, calculates the particle size distribution of each particle in the dispersion. A dynamic light scattering measurement device in which the scattering intensity profile obtained by changing the value of the measurement parameter differs for each of several types of particle species.

11. The dynamic light scattering measuring device according to claim 9 or 10, wherein the measurement parameter is the scattering angle.

12. The dynamic light scattering measuring apparatus according to claim 9 or 10, wherein the measurement parameter is the measurement wavelength.

13. The dynamic light scattering measuring apparatus according to claim 9 or 10, wherein the measurement parameters are the scattering angle and the measurement wavelength.

14. The dynamic light scattering measuring device according to any one of claims 9 to 13, wherein the scattered light measuring unit measures the light intensity of the polarization component of the scattered light of the dispersion obtained by irradiating the dispersion with incident light of a specific polarization as the scattering intensity.

15. The dynamic light scattering measuring apparatus according to any one of claims 9 to 13, wherein the scattered light measuring unit measures at least one of the scattering intensity parameter-dependent data obtained by sequentially irradiating the dispersion with incident light in multiple polarization states, and the scattering intensity parameter-dependent data obtained by extracting multiple polarization components of scattered light emitted from the dispersion.

16. The dynamic light scattering measurement apparatus according to any one of claims 9 to 15, wherein the calculated scattering intensity time variation characteristic data of the measurement parameter and the scattering intensity parameter dependence data of the measurement parameter are calculated based on at least one of the Mie scattering theory formula, the discrete dipole approximation method, and the Stokes-Einstein theory formula.

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