Method and apparatus for evaluating the orientation of non-spherical particles

Abstract

By detecting the optical properties of the coating surface, the orientation of non-spherical particles can be quantitatively evaluated simply and over a wide range of applications. [Solution] A method for evaluating the orientation of non-spherical particles in a coating film, comprising: step S1 of irradiating a predetermined area on the surface of the coating film with light; step S2 of receiving reflected light reflected by the coating film and obtaining the polarization axis azimuth angle of the non-spherical particles from the polarization component parameters of the reflected light; and step S4 of evaluating the orientation using an angular index of the non-spherical particles obtained using the polarization axis azimuth angle as an evaluation index.

Description

Technical Field

[0001] The present disclosure relates to a method for evaluating the orientation of non-spherical particles and an orientation evaluation apparatus.

Background Art

[0002] In order to impart design properties such as metallic luster to a coating film, for example, non-spherical particles such as metal flakes may be added. In a coating film containing non-spherical particles, the orientation of the non-spherical particles in the coating film affects the properties and appearance of the coating film. Conventionally, visual inspection by human eyes has been performed as a method for evaluating the appearance of such a coating film. For example, Patent Document 1 discloses a technique for distinguishing between scratches and those due to the orientation of coating flakes by an observer wearing polarizing goggles and observing the coating surface.

[0003] In addition, there are a method of observing a cross-section of a coating film with a scanning electron microscope (SEM) and performing image analysis, and a method of irradiating a coating film with light and measuring the reflected light intensity at a position corresponding to the orientation angle of the scaly material in the coating film and quantifying the orientation state of the scaly material by calculating the frequency of the orientation angle, as disclosed in Patent Document 2, and a method of irradiating a coating layer with light and measuring the reflected light and performing a quantitative evaluation of the appearance by digitizing the position distribution of the brightening material, as disclosed in Patent Document 3.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in ADAS (Advanced Driver-Assistance Systems) and autonomous driving technologies in automobiles, sensor units that use electromagnetic waves to sense distance, speed, and obstacles are installed on the vehicle's bumper and other parts. Multiple paint films are layered on the surface of an automobile body to form a surface coating, which protects the body and improves its design. However, non-spherical particles contained in the paint film hinder the transmission of electromagnetic waves. Therefore, it is necessary to control the structure of non-spherical particles in the paint film on the vehicle body surface to achieve both design and electromagnetic wave transmission.

[0006] Therefore, with the aim of controlling the structure of non-spherical particles in paint films, efforts are being made to predict the behavior of non-spherical particles in paint during drying. In order to confirm the accuracy of the construction model used for this prediction and to verify the control, it is necessary to quantitatively evaluate the relationship between structural features such as the orientation of non-spherical particles in the paint film after drying and the appearance (aesthetics) of the paint film. Quantitative evaluation is difficult with the visual inspection described above, and evaluation by cross-sectional observation using SEM etc. has problems such as being time-consuming and having a localized imaging range.

[0007] Therefore, this disclosure aims to provide a method and apparatus for evaluating the orientation of non-spherical particles in a coating film, which can quantitatively evaluate the orientation of non-spherical particles in a simple and wide range of applications by detecting optical properties on the surface of the coating film. [Means for solving the problem]

[0008] To solve the above problems, the first invention, as one aspect of the method for evaluating the orientation of non-spherical particles according to this disclosure, A method for evaluating the orientation of non-spherical particles in a coating film, The steps include irradiating a predetermined area of ​​the coating surface with light, The steps include receiving the reflected light reflected by the coating film and obtaining the polarization axis orientation angle of the non-spherical particles from the parameters of the polarization component of the reflected light, The method is characterized by including the step of evaluating orientation using an angular index of the non-spherical particles, which is determined using the polarization axis orientation angle, as an evaluation index.

[0009] As a result of diligent research, the inventors of this invention have discovered that by receiving reflected light from the surface of a coating film and using the polarization axis orientation angle of the non-spherical particles, it is possible to quantitatively evaluate the structural characteristics of non-spherical particles in a simple and wide-ranging manner. With the above configuration, there is no need to cut the coating film and observe the cross-section, and evaluation can be performed non-destructively by detecting the polarization axis orientation angle on the surface of the coating film. Therefore, the time and effort required for evaluation are reduced compared to conventional methods, and quantitative evaluation is possible.

[0010] In the first invention, it is preferable that the angle index is at least one of the following in the predetermined region: the average polarization axis orientation angle, the peak position of the polarization axis orientation angle distribution, the absolute value of the average polarization axis orientation angle of -90°, and the absolute value of the peak position of the polarization axis orientation angle distribution of -90°.

[0011] According to the above configuration, evaluation results that correlate strongly with conventional evaluation methods using cross-sectional observation can be obtained.

[0012] The second invention, as one aspect of the method for evaluating the orientation of non-spherical particles according to this disclosure, A method for evaluating the orientation of non-spherical particles in a coating film, The steps include irradiating a predetermined area of ​​the coating surface with light, The steps include receiving the reflected light reflected by the coating film and obtaining the polarization axis orientation angle of the non-spherical particles from the parameters of the polarization component of the reflected light, The method is characterized by including a step of evaluating orientation using an evaluation index obtained by the integration or division of an angular index of the non-spherical particles, which is determined using the polarization axis azimuth angle, and a variability index of the non-spherical particles, which is determined using the polarization axis azimuth angle.

[0013] With the above configuration, it is not necessary to observe the cross-section of the coating film, and evaluation can be performed by detecting the polarization axis orientation angle on the surface of the coating film. This reduces the time and effort required for evaluation compared to conventional methods, and enables quantitative evaluation. Furthermore, by using angle indices and variability indices for non-spherical particles and deriving evaluation indices by integrating or dividing them, it is possible to quantitatively evaluate the relationship between structural features such as the orientation of non-spherical particles and the appearance (design) of the coating film.

[0014] In the second invention, The angle index is at least one of the following in the predetermined region: the average polarization axis orientation angle, the peak position of the polarization axis orientation angle distribution, the absolute value of the average polarization axis orientation angle of -90°, and the absolute value of the peak position of the polarization axis orientation angle distribution of -90°. Preferably, the variability index is at least one of the standard deviation of the polarization axis orientation angle, the variance of the polarization axis orientation angle, and the full width at half maximum of the axis orientation angle distribution in the predetermined region.

[0015] More preferably, the angle index is the absolute value of the average polarization axis orientation angle of -90°, or the absolute value of the peak position of the polarization axis orientation angle distribution of -90°.

[0016] More preferably, the evaluation index is the sum of the absolute value of the mean polarization axis orientation angle of -90°, or the absolute value of the peak position of the polarization axis orientation angle distribution of -90°, and the standard deviation of the polarization axis orientation angle, the variance of the polarization axis orientation angle, or the half-width of the polarization axis orientation angle distribution, or It is calculated by dividing the standard deviation of the polarization axis orientation angle by the mean of the polarization axis orientation angle.

[0017] More preferably, the evaluation index is obtained by multiplying the absolute value of the average polarization axis orientation angle of -90°, or the peak position of the polarization axis orientation angle distribution of -90°, by the standard deviation of the polarization axis orientation angle, the variance of the polarization axis orientation angle, or the full width at half maximum of the polarization axis orientation angle distribution.

[0018] According to the above configuration, evaluation results that correlate strongly with conventional evaluation methods using cross-sectional observation can be obtained.

[0019] One aspect of the non-spherical particle orientation evaluation apparatus according to the present disclosure is a non-spherical particle orientation evaluation apparatus in a coating film, comprising lighting means for irradiating light onto a predetermined region of the coating film surface, light receiving means for receiving the reflected light reflected by the coating film, calculation means for obtaining the polarization axis azimuth angle of the non-spherical particles from the parameters of the polarization component of the reflected light and calculating an angular index of the non-spherical particles using the polarization axis azimuth angle, and characterized by including the above.

Advantages of the Invention

[0020] As described above, according to the present disclosure, by detecting the polarization axis azimuth angle on the coating film surface, it becomes possible to quantitatively evaluate the orientation of non-spherical particles simply and over a wide range.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic diagram showing a configuration example of a non-spherical particle orientation evaluation apparatus according to the present disclosure. [Figure 2] It is an example of a flowchart of a non-spherical particle orientation prediction method according to the present disclosure. [Figure 3] It is a diagram for explaining the polarization axis azimuth angle Ψ of non-spherical particles when the coating film surface is irradiated with light. [Figure 4] It is a schematic diagram for explaining the imaging field of view of a polarization camera and the distribution of the polarization axis azimuth angle. [Figure 5] It is a diagram showing the distribution of the polarization axis azimuth angle and the angular index. [Figure 6] It is a graph showing the correlation with the evaluation result by the conventional method. [Figure 7] It is a graph showing the correlation with the evaluation result by the conventional method.

Embodiments for Carrying Out the Invention

[0022] Embodiments of the present disclosure will be described in detail below with reference to the drawings. The following description of preferred embodiments is illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses in any way.

[0023] <coating film> The coating film, which is the subject of orientation evaluation of non-spherical particles according to this embodiment, will be described in outline. The coating film is formed by applying a paint containing non-spherical particles, a solvent, and a resin to the surface of a substrate and drying it.

[0024] The type, shape, and particle size of the non-spherical particles can be appropriately selected depending on the application of the coating film. Non-spherical refers to a shape that is not a perfect sphere, for example, with an aspect ratio greater than 1. The aspect ratio is the ratio of the length of the major axis to the length of the minor axis of a particle. Examples of non-spherical particle shapes include disc-shaped, elliptical, flake-shaped, rod-shaped, columnar, plate-shaped, needle-shaped, and fibrous shapes, among which disc-shaped, elliptical, flake-shaped, disc-shaped, and plate-shaped particles are preferred.

[0025] The application of the paint is not particularly limited, but for example, when a metallic sheen is desired in the paint film, such as in the surface coating of an automobile, it is preferable to use a glossy material such as aluminum flakes as non-spherical particles. When using aluminum flakes, it is preferable to use those with an average particle size of 0.3 μm or more, preferably 1 μm to 100 μm, and an average thickness of 10 nm or more, preferably 10 nm to 2 μm. When using aluminum flakes, the aspect ratio (average particle size / average thickness) is preferably 30 to 300. The average particle size can be obtained, for example, by determining the D50, which is the 50th percentile value of the particle size distribution measured by a laser diffraction particle size distribution analyzer. The average particle size is preferably the number average particle size. The average thickness can be obtained, for example, by observing with a scanning electron microscope, measuring the thickness of multiple (e.g., 50) particulate components, and calculating the average value.

[0026] The resin is not particularly limited as long as it can form a coating film. However, for example, when considering automotive surface coatings as a substrate, acrylic resins, polyester resins, urethane resins, melamine resins, isocyanate resins, etc., can be used individually or in combination of several types.

[0027] Various organic solvents capable of dissolving the resin can be used as solvents. One solvent may be used alone, or two or more may be used in mixture form. Examples of solvents include hydrocarbon solvents such as xylene, toluene, hexane, and heptane; ester solvents such as ethyl acetate, butyl acetate, and ethylene glycol monomethyl ether acetate; ether solvents such as ethylene glycol monomethyl ether and ethylene glycol diethyl ether; alcohol solvents such as butanol, propanol, octanol, cyclohexanol, and diethylene glycol; and ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone.

[0028] The paint may contain additives such as pigments, UV shielding agents, viscosity enhancers, thickeners, pigment dispersants, and surface modifiers, as needed.

[0029] The coating is formed by first applying the paint to the substrate to create a wet coating, and then drying and curing the paint at room temperature and by heating while evaporating the solvent. The application method is not particularly limited; it may be applied using a brush or spatula, or it may be sprayed and applied from above using a spray gun.

[0030] <Apparatus for evaluating the orientation of non-spherical particles> Figure 1 shows an example of the configuration of the non-spherical particle orientation evaluation device 100 (hereinafter also referred to as "evaluation device 100") of this embodiment. The evaluation device 100 is a device for evaluating the orientation of non-spherical particles in a coating film, and comprises a computer 10 and a measuring device 20.

[0031] The computer 110 comprises a processor 11 as a means of calculation, a storage unit 12 that stores information such as calculation programs and various analysis data, a display unit 13 consisting of a display or the like, and an input unit 14 consisting of a keyboard or the like. The processor 11 performs various calculations based on the information stored in the storage unit 12, the information input via the input unit 14, and the information acquired from the measuring device 20. The processor 11 acquires the parameters of the polarization component of reflected light (Stokes parameters) based on the electrical signals transmitted from the measuring device 20, and acquires the polarization axis azimuth angle of non-spherical particles from the polarization component parameters. Then, it calculates the angular index and the variability index of the non-spherical particles using the polarization axis azimuth angle, and evaluates the orientation of the non-spherical particles in the coating film based on these indices.

[0032] The measuring device 20 includes an LED light source 21 as an illumination means, a polarizing camera 22 as a light receiving means, a microscope lens 23, and a light intensity adjustment device 24. The LED light source 21 irradiates a predetermined area of ​​the surface of the coating film X to be evaluated with light. The polarizing camera 22 has a polarizing filter and a two-dimensional light receiving element such as a CMOS, and receives the reflected light reflected by the coating film X. As will be described in detail later, the polarizing camera 22 separates the light into light intensity, horizontal polarization component, and vertical polarization component, and converts the optical signal into an electrical signal. The polarizing camera 22 transmits this electrical signal to the processor 11.

[0033] <Method for evaluating the orientation of non-spherical particles> Figure 2 is an example of a flowchart of the orientation prediction method for non-spherical particles according to this disclosure (hereinafter also referred to as the "prediction method"). As shown in Figure 2, this prediction method includes, for example, a light irradiation step S1, a polarization axis azimuthal angle acquisition step S2, an angle index and variability index calculation step S3, and an orientation evaluation step S4.

[0034] First, in the light irradiation step S1, the LED light source 21 irradiates a predetermined area on the surface of the coating X to be evaluated, and the polarizing camera 22 receives the reflected light reflected by the coating X. The polarizing camera 22 can acquire the light as Stokes parameters. The Stokes parameters are expressed as S0 = light intensity, S1 = horizontal linear polarization component (when it is 1 it is horizontal polarization [P polarization], and when it is -1 it is vertical polarization [S polarization]), S2 = 45° linear polarization component, and S3 = right circular polarization component, and the polarizing camera can acquire S0, S1 and S2. The polarizing camera 22 transmits the acquired Stokes parameters as electrical signals to the processor 11.

[0035] In the polarization axis azimuth angle acquisition step S2, the processor 11 acquires the parameters of the polarization component of the reflected light (Stokes parameters) from the electrical signal transmitted from the measuring device 20. The processor 11 further acquires the polarization axis azimuth angle of the non-spherical particles from the parameters of the polarization component.

[0036] In step S3, which calculates the angle index and variability index, the processor 11 calculates the angle index and variability index of non-spherical particles using the acquired polarization axis azimuthal angle.

[0037] Then, in the orientation evaluation step S4, the processor 11 evaluates the orientation of the non-spherical particles using the angle index as an evaluation index, or using a value obtained from the integration or division of the angle index and the variation index as an evaluation index.

[0038] <Polarization axis azimuth> Figure 3 illustrates the polarization axis azimuth angle Ψ of non-spherical particles when light is irradiated onto a coating surface. It is assumed that light emitted from the LED light source 21 is reflected at point P on the xy-plane of the non-spherical particle Y. A common method for obtaining angular information of non-spherical particles is to use a normal vector n, which is expressed from the zenith angle θ and azimuth angle Ψ of the incident light. As will be described in detail later, in this embodiment, instead of using the normal vector n, the polarization axis azimuth angle Ψ is used to obtain angular information of non-spherical particles. In this embodiment, a polarization camera is used as the light receiving means. The polarization camera acquires three Stokes parameters: S0, S1, and S2. The polarization axis azimuth angle Ψ is expressed using the linear polarization components S1 and S2 as follows: Polarization axis azimuth Ψ=arctan(S2 / S1) It is possible to obtain it by doing so.

[0039] Figure 4 is a schematic diagram illustrating the imaging field of view of a polarization camera and the distribution of polarization axis azimuth angles. By receiving reflected light, the polarization camera enables the processor to obtain the polarization axis azimuth angle Ψ of non-spherical particles as described above. As shown in Figure 4, the processor can determine the distribution of polarization axis azimuth angles Ψ for each pixel, for example, within a predetermined range within the imaging field of view of the polarization camera (polarization axis azimuth angle distribution).

[0040] <Angular index and variability index> In the evaluation method described herein, an angular index relating to the angle of the non-spherical particles and a variability index relating to the variability of the angle of the non-spherical particles are used as structural features of the non-spherical particles to evaluate the orientation of the non-spherical particles. Both the angular index and the variability index are determined using the polarization axis azimuthal angle.

[0041] Figure 5 shows the distribution of polarization axis azimuth angles and an angular index. The processor can obtain a polarization axis azimuth angle distribution, as shown in Figure 5, from the polarization axis azimuth angle distribution information obtained as shown in Figure 4, with the horizontal axis representing the polarization axis azimuth angle and the vertical axis representing its frequency. The processor can then calculate the average polarization axis azimuth angle and the peak position of the polarization axis azimuth angle distribution from this distribution. The average optical axis azimuth angle and the peak position of the polarization axis azimuth angle distribution can be used as angular indices for evaluating the orientation of non-spherical particles. Furthermore, the processor can obtain the full width at half maximum (FWHM), variance, and standard deviation of the polarization axis azimuth angle from the polarization axis azimuth angle distribution. The FWHM, variance, and standard deviation of the polarization axis azimuth angle can be used as variability indices for evaluating the orientation of non-spherical particles.

[0042] As described above, in the evaluation method of this disclosure, the orientation state can be evaluated by obtaining the polarization axis azimuth angle Ψ using a polarization camera, thereby obtaining an angle index and a variability index. However, as mentioned above, in order to evaluate the orientation of non-spherical particles, there is a method to determine the normal vector n represented by the zenith angle θ and azimuth angle Ψ of the reflected light. With a polarization camera, the azimuth angle Ψ can be determined, but the zenith angle θ cannot. When the zenith angle θ cannot be determined, as shown in Figure 3, there are two types of candidate normal vectors n, and there are also two types of candidate polarization axis azimuth angles Ψ, Ψ and Ψ+180°, so it is not possible to determine one of them. However, in the evaluation method of this disclosure, it is sufficient to determine the orientation state, such as whether the non-spherical particles are upright or lying down, within the coating film, and it is considered that the evaluation accuracy will not be affected even if one of the two types of normal vectors n is not determined. Therefore, in the evaluation method disclosed herein, the orientation of non-spherical particles can be evaluated by the absolute value of the polarization axis azimuth angle Ψ-90° (|polarization axis azimuth angle Ψ-90°|).

[0043] In other words, the angle index is at least one of the following: the average polarization axis azimuthal angle, the peak position of the polarization axis azimuthal angle distribution, the absolute value of the average polarization axis azimuthal angle of -90°, and the absolute value of the peak position of the polarization axis azimuthal angle distribution of -90°, but it is preferable that the index is the absolute value of the average polarization axis azimuthal angle of -90° and the absolute value of the peak position of the polarization axis azimuthal angle distribution of -90°.

[0044] While it is possible to evaluate the orientation of non-spherical particles using only an angle index, it is preferable to evaluate them using an evaluation index obtained by the integration or division of the angle index and the variability index. The evaluation index is preferably obtained, for example, by the integration of the absolute value of the mean polarization axis orientation angle -90°, or the absolute value of the peak position -90° of the polarization axis orientation angle distribution, with the standard deviation of the polarization axis orientation angle, the variance of the polarization axis orientation angle, or the full width at half maximum of the polarization axis orientation angle distribution, or by the division of the standard deviation of the polarization axis orientation angle with the mean polarization axis orientation angle. Specifically, for example, (Absolute value of the mean polarization axis orientation angle -90°) × Standard deviation of the polarization axis orientation angle, (Absolute value of the average polarization axis orientation angle -90°) × Variance of the polarization axis orientation angle, (Absolute value of the average polarization axis orientation angle of -90°) × Full width at half maximum of the polarization axis orientation angle distribution, (Absolute value of the peak position of the polarization axis orientation angle distribution at -90°) × Standard deviation of the polarization axis orientation angle, (Absolute value of the peak position of the polarization axis orientation angle distribution at -90°) × Variance of the polarization axis orientation angle, (Absolute value of the peak position of the polarization axis azimuth angle distribution at -90°) × Full width at half maximum of the polarization axis azimuth angle distribution, and standard deviation of the polarization axis azimuth angle / mean of the polarization axis azimuth angle It is more preferable to use this as an evaluation metric. [Examples]

[0045] The following describes the confirmation of the correlation between the evaluation indicators obtained using the evaluation method disclosed herein and the evaluation indicators obtained using conventional evaluation methods. Three test pieces, Sample No. 1 to No. 3, were prepared as the subjects of evaluation. Each test piece was prepared by coating a 120 mm × 150 mm × 2.85 mm PP board, which was the substrate material, with paint having the same composition. The composition of the paint used in common for the preparation of Sample No. 1 to No. 3 is shown below, and the characteristics of the glossy material, paint viscosity, and coating film preparation method are shown in Table 1.

[0046] Resin: Acrylic resin 29.2 wt%, Blocked isocyanate 7.9 wt% Additives: Viscosity agent 3.3 wt% Solvent: 59.6 wt% The solvents include ethylbenzene, xylene, toluene, ethyl acetate, methyl isobutyl ketone, isobutyl alcohol, n-butyl acetate, isopentyl alcohol, 1-butanol, and ethyl alcohol. The content of glossing agents as non-spherical particles in the paint solids (paint film components) is 2.8%.

[0047] [Table 1]

[0048] <Conventional method: Evaluation by cross-sectional observation> For Samples No. 1 to No. 3, created as described above, the angular distribution and standard deviation of non-spherical particles were determined by cross-sectional observation of the coating film using conventional methods. Specifically, the coating film and substrate were cut and embedded in resin, the cross-sections of the coating film and substrate (which served as the observation surfaces) were polished, and then observed with a laser microscope. The angular distribution and its standard deviation were measured based on the brightness of the image. The evaluation took approximately two days. The equipment and measurement conditions used are shown below. (Equipment used) Lasertec Corporation OPTELICS HYBRID L7-GA300 (Measurement conditions) Mode: Surface Geometry, Magnification: 50x, Measurement Algorithm: First Peak, Resolution: 0.05μm, Exposure Time: Standard, Light Intensity: 100%, Gain: 500~600 After imaging with the laser microscope described above, the angular distribution based on image brightness and its standard deviation were measured using the Directionality tool in the image processing software ImageJ (manufactured by National Institutes of Health).

[0049] <Conventional method: Evaluation based on optical properties> Furthermore, for Samples No. 1 to No. 3 created as described above, the particle density σ was determined from the distribution of luminance values ​​on the coating surface using a conventional method. The particle density σ is calculated by multiplying the standard deviation of the luminance values ​​by the reciprocal of the mean of the luminance values. The equipment and measurement conditions used are shown below. (Equipment used) Microplane photometer (MMP) manufactured by Nippon Denshoku Industries Co., Ltd. (Measurement conditions) Measurement items: Luminous reflectance Y, Incident angle: 40°, Receiving angle: 5°, Spot diameter: 0.2mm, Measurement distance: 30mm, Measurement interval: 0.1mm.

[0050] <Method for evaluating this disclosure> Furthermore, for Samples No. 1 to No. 3 created as described above, each evaluation indicator was determined using the evaluation method disclosed herein. The evaluation took approximately 2 hours. The equipment and measurement conditions used are shown below. (Equipment used) Polarization imaging camera PI-300, manufactured by Photonic Lattice Co., Ltd. Operating wavelength: 520nm, Resolution: 2464×2056 pixels, Maximum operating speed: 20fps, Zoom lens magnification: 0.87~10.5, Field of view: Approx. 9.9×8.3mm~0.8×0.7mm (Measurement conditions) Light intensity: 250 (0-255), Magnification: 10.5 (0.87-10.5), Gain: 10 (0-25), Exposure time: 30,000 μsec (0-1,000,000 μsec), Total number of frames: 50 (1-1,000), Resolution: 0.3 μm / pixel.

[0051] Figures 6 and 7 are examples of graphs showing the correlation with evaluation results using conventional methods. In Figures 6 and 7, the vertical axis represents the evaluation index in the evaluation method of this disclosure, showing the product of the average of the polarization axis orientation angle (absolute value of -90°) and the standard deviation of the polarization axis orientation angle. The horizontal axis in Figure 6 represents the evaluation index using conventional methods, which is the product of the angle average and its standard deviation obtained from the luminance obtained by cross-sectional observation. The horizontal axis in Figure 7 represents the evaluation index using conventional methods, which is the value of the particle sensitivity σ obtained from the luminance obtained by a micro-surface photometer. Figures 6 and 7 are scatter plots showing the evaluation index in the evaluation method of this disclosure and the evaluation index using conventional methods, along with their correlation lines.

[0052] Table 2 shows the results of the correlation analysis between the evaluation indicators obtained by the evaluation method disclosed herein and the evaluation indicators obtained by conventional evaluation methods. In Table 2, the coefficient of determination (R) of the correlation line shown in Figures 6 and 7 is shown. 2 If the value is 0.8 or higher, it was determined that the evaluation index by the evaluation method of this disclosure shows a strong correlation with the evaluation results by the conventional method. Furthermore, in Table 2, if the evaluation index by the evaluation method of this disclosure shows a strong correlation with both the cross-sectional evaluation results and the optical property evaluation by the conventional method, the correlation evaluation is set to A; if the evaluation index by the evaluation method of this disclosure shows a strong correlation with either the cross-sectional evaluation results or the optical property evaluation by the conventional method, the correlation evaluation is set to B; and if the evaluation index by the disclosed evaluation method does not show a strong correlation with either the cross-sectional evaluation results or the optical property evaluation by the conventional method, the correlation evaluation is set to C.

[0053] [Table 2]

[0054] When using only angular indices—the average polarization axis orientation angle, the peak position of the polarization axis orientation angle distribution, the absolute value of the average polarization axis orientation angle of -90°, and the absolute value of the peak position of the polarization axis orientation angle distribution of -90°—as evaluation indicators, the correlation with conventional methods was A. Therefore, it is possible to use the evaluation method disclosed in this disclosure as an alternative to conventional methods, using only angular indices as evaluation indicators, and quantitative evaluation of orientation can be performed more simply and broadly than before.

[0055] Furthermore, the correlation with conventional methods was also A when using the following evaluation indicators: the product of the angle index and the variability index, namely (absolute value of the average polarization axis orientation angle -90°) × standard deviation of the polarization axis orientation angle, (absolute value of the average polarization axis orientation angle -90°) × variance of the polarization axis orientation angle, (absolute value of the average polarization axis orientation angle -90°) × full width at half maximum of the polarization axis orientation angle distribution, (absolute value of the peak position of the polarization axis orientation angle distribution at -90°) × standard deviation of the polarization axis orientation angle, (absolute value of the peak position of the polarization axis orientation angle distribution at -90°) × variance of the polarization axis orientation angle, (absolute value of the peak position of the polarization axis orientation angle distribution at -90°) × full width at half maximum of the polarization axis orientation angle distribution, and the division of the angle index and the variability index, namely standard deviation of the polarization axis orientation angle / average polarization axis orientation angle.

[0056] Incidentally, when determining particle sensitivity σ from the distribution of luminance values, as in conventional evaluation methods based on optical properties, particle sensitivity σ is obtained by multiplying the standard deviation of luminance values ​​by the reciprocal of the mean of luminance values. Considering this, in the evaluation method disclosed herein, it is thought that obtaining the evaluation index by multiplying or dividing the angle index by a variability index such as the standard deviation or dispersion value of the polarization axis orientation angle, rather than using only the angle index, will yield more reliable results in quantitatively evaluating the relationship between structural features such as the orientation of non-spherical particles and the appearance (design) of the coating film.

[0057] As described above, the evaluation method and apparatus of this disclosure make it possible to quantitatively evaluate structural characteristics such as the orientation of non-spherical particles in a simple and wide-ranging manner. With the evaluation method and apparatus of this disclosure, it is not necessary to cut the coating film and observe the cross-section, and evaluation can be performed non-destructively by detecting the polarization axis orientation angle on the surface of the coating film. Therefore, the time and man-hours required for evaluation are reduced compared to conventional methods, and quantitative evaluation is possible.

[0058] According to the evaluation method and apparatus of this disclosure, since evaluation is possible by detecting the polarization axis orientation angle on the surface of the coating film, it is possible not only to evaluate the state of non-spherical particles in a dry coating film after drying by evaporating the solvent, but also to acquire time-series data of a wet coating film containing a solvent before drying as it dries and hardens over time, and use this to predict the behavior of non-spherical particles in the drying process. [Industrial applicability]

[0059] This disclosure provides a method and apparatus for evaluating the orientation of non-spherical particles, which is extremely useful because, when evaluating the orientation of non-spherical particles in a coating film, the orientation can be quantitatively evaluated simply and over a wide range by detecting the optical properties of the coating film surface. [Explanation of Symbols]

[0060] 10 Computers 11. Processor (arithmetic means) 20 Measuring devices 21 LED light source (illumination means) 22 Polarizing camera (light receiving means) 100 Orientation evaluation device

Claims

1. A method for evaluating the orientation of non-spherical particles in a coating film, The steps include irradiating a predetermined area of ​​the coating surface with light, The steps include receiving the reflected light reflected by the coating film and obtaining the polarization axis orientation angle of the non-spherical particles from the parameters of the polarization component of the reflected light, A method for evaluating the orientation of non-spherical particles, comprising the step of evaluating the orientation using an angular index of the non-spherical particles obtained using the polarization axis azimuthal angle as an evaluation index.

2. In claim 1, A method for evaluating the orientation of non-spherical particles, wherein the angle index is at least one of the following in a predetermined region: the average polarization axis orientation angle, the peak position of the polarization axis orientation angle distribution, the absolute value of the average polarization axis orientation angle of -90°, and the absolute value of the peak position of the polarization axis orientation angle distribution of -90°.

3. A method for evaluating the orientation of non-spherical particles in a coating film, The steps include irradiating a predetermined area of ​​the coating surface with light, The steps include receiving the reflected light reflected by the coating film and obtaining the polarization axis orientation angle of the non-spherical particles from the parameters of the polarization component of the reflected light, A method for evaluating the orientation of non-spherical particles, comprising the step of evaluating the orientation using an evaluation index obtained by the integration or division of an angular index of the non-spherical particles obtained using the polarization axis azimuthal angle and a variability index of the non-spherical particles obtained using the polarization axis azimuthal angle.

4. In claim 3, The angle index is at least one of the following in the predetermined region: the average polarization axis orientation angle, the peak position of the polarization axis orientation angle distribution, the absolute value of the average polarization axis orientation angle of -90°, and the absolute value of the peak position of the polarization axis orientation angle distribution of -90°. A method for evaluating the orientation of non-spherical particles, wherein the variability index is at least one of the standard deviation of the polarization axis orientation angle, the variance of the polarization axis orientation angle, and the full width at half maximum of the axial orientation angle distribution in the predetermined region.

5. In claim 4, A method for evaluating the orientation of non-spherical particles, wherein the angle index is the absolute value of the average polarization axis orientation angle of -90°, or the absolute value of the peak position of the polarization axis orientation angle distribution of -90°.

6. In claim 4, The aforementioned evaluation index is calculated by multiplying the absolute value of the average polarization axis azimuth angle of -90°, or the absolute value of the peak position of the polarization axis azimuth angle distribution of -90°, by the standard deviation of the polarization axis azimuth angle, the variance of the polarization axis azimuth angle, or the half-width of the polarization axis azimuth angle distribution, or A method for evaluating the orientation of non-spherical particles, obtained by dividing the standard deviation of the polarization axis orientation angle by the mean of the polarization axis orientation angle.

7. In claim 6, The aforementioned evaluation index is a method for evaluating the orientation of non-spherical particles, obtained by multiplying the absolute value of the average polarization axis orientation angle of -90°, or the peak position of the polarization axis orientation angle distribution of -90°, by the standard deviation of the polarization axis orientation angle, the variance of the polarization axis orientation angle, or the full width at half maximum of the polarization axis orientation angle distribution.

8. An apparatus for evaluating the orientation of non-spherical particles in a coating film, An illumination means for irradiating a predetermined area on the surface of the coating film with light, A light receiving means for receiving reflected light reflected by the coating film, A calculation means that obtains the polarization axis azimuth angle of the non-spherical particle from the polarization component parameters of the reflected light and calculates an angular index of the non-spherical particle using the polarization axis azimuth angle, An apparatus for evaluating the orientation of non-spherical particles, including those containing this material.

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