Analytical methods

Abstract

To provide an analysis method capable of accurately estimating the type, content, and mixing ratio of a filler present in an elastomer composition, such as to determine whether or not a sample contains two or more types of fillers.SOLUTION: The present invention relates to an analysis method for estimating a type, content, and mixing ratio of a filler in an elastomer composition containing an elastomer component and the filler, the analysis method performing estimation based on properties, particle size, and a particle size distribution of the filler.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an analysis method.

Background Art

[0002] Regarding fillers dispersed in an elastomer composition containing an elastomer, a filler, etc., a method for measuring the average particle diameter and particle size distribution is used, but it is desired to precisely analyze whether or not it contains a plurality of types of fillers, the type, content, and mixing ratio of the fillers.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to provide an analysis method that solves the above problems and can accurately estimate the type, content, and mixing ratio of fillers present in an elastomer composition, such as whether it is a sample containing two or more types of fillers.

Means for Solving the Problems

[0004] The present disclosure is an analysis method for estimating the type, content, and mixing ratio of the fillers in an elastomer composition containing an elastomer component and a filler, relating to an analysis method for estimating based on the properties, particle diameter, and particle size distribution of the fillers.

Effects of the Invention

[0005] According to the present invention, since it is an analysis method for estimating the type, content, and mixing ratio of the fillers in an elastomer composition containing an elastomer component and a filler, and is an analysis method for estimating based on the properties, particle diameter, and particle size distribution of the fillers, it is possible to accurately estimate the type, content, and mixing ratio of the fillers present in the elastomer composition, such as whether it is a sample containing two or more types of fillers.

Brief Description of the Drawings

[0006] [Figure 1]An example of the particle size distribution of carbon black (the filler to be analyzed) present in the sample of formulation 2. [Figure 2] An example of the particle size distribution of carbon black (the filler to be analyzed) present in the sample of formulation 3. [Figure 3] An example of a diagram showing the average value, 3σ value, lower limit control line (LCL), and upper limit control line (UCL) derived from the average value and 3σ value of the particle size distribution of standard fillers (carbon black SAF, ISAF, HAF, FEF, GPF). [Figure 4] An example of a figure showing the results of comparing and analyzing the particle size distribution of filler (carbon black) in a sample of formulation 2 with the particle size distribution of standard fillers (SAF, ISAF, HAF, FEF, GPF). [Figure 5] An example of a figure showing the results of comparing and analyzing the particle size distribution of filler (carbon black) in a sample of formulation 3 with the particle size distribution of standard fillers (SAF, ISAF, HAF, FEF, GPF). [Figure 6] An example of the particle size distribution of carbon black (the filler to be analyzed) present in a sample of formulation 1. [Figure 7] An example of the particle size distribution of carbon black (the filler to be analyzed) present in the sample of formulation 4. [Figure 8] An example of the particle size distribution of carbon black (the filler to be analyzed) present in a sample of formulation 5. [Figure 9] An example of the particle size distribution of carbon black (the filler to be analyzed) present in a sample of formulation 6. [Figure 10] An example of the particle size distribution of carbon black (the filler to be analyzed) present in a sample of formulation 7. [Modes for carrying out the invention]

[0007] The present invention relates to an analytical method for estimating the type, content, and mixing ratio of a filler in an elastomer composition containing a filler and an elastomer, wherein the analytical method estimates the filler based on its properties, particle size, and particle size distribution.

[0008] The method disclosed herein involves measuring the properties, particle size, and particle size distribution of fillers dispersed within an elastomer composition, and then analyzing the results. This method allows for the determination of which commercially available product (standard product) the primary particle size of the fillers in the composition corresponds to. Furthermore, since this method measures the particle size and particle size distribution of fillers within a composition, for example, by comparing the obtained particle size and particle size distribution with the particle size and particle size distribution of a commercially available product (standard product), it is possible to determine whether a sample contains two or more fillers, the content of each filler, and the mixing ratio, not only for samples containing one type of filler, but also for samples containing two or more types of fillers (two or more types of carbon black, two or more types of silica, one or more types of carbon black and one or more types of silica, etc.). Therefore, this disclosure makes it possible to estimate the type (grade, etc.) of fillers in the elastomer composition, the presence or absence of two or more types of fillers, the filler content, and the mixing ratio of each filler.

[0009] In the analytical method of the present invention, an elastomer composition (sample) containing elastomer components and fillers is analyzed. However, the usable elastomer components are not particularly limited, and for example, diene rubbers can be used. Examples of diene rubbers include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). Butyl rubbers and fluororubbers can also be used. These may be used individually or in combination of two or more.

[0010] The usable fillers are not particularly limited, and materials known in the rubber field can be used, such as inorganic fillers like carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica; and poorly dispersible fillers. Among these, carbon black and silica are particularly suitable.

[0011] The carbon black used is not particularly limited and includes SAF, ISAF, HAF, FF, FEF, GPF, etc. Commercially available products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., Columbia Carbon, etc. can be used. These may be used individually or in combination of two or more types. In particular, the analytical method disclosed herein can estimate the type (grade), content, and content ratio of each carbon black contained in a sample, not only for samples containing only one type of carbon black, but also for samples containing two or more types of carbon black.

[0012] In the elastomer composition (sample), the carbon black content is not particularly limited. For example, it is 1 to 150 parts by mass, preferably 3 to 100 parts by mass, and more preferably 5 to 80 parts by mass, per 100 parts by mass of the elastomer component. Within this range, it tends to be possible to accurately estimate the type (grade), content, and proportion of each type of carbon black contained in the sample.

[0013] Examples of silica include dry-process silica (anhydrous silicic acid) and wet-process silica (hydrated silicic acid), but wet-process silica is preferred because it contains a large number of silanol groups. The raw material for silica may be water glass (sodium silicate) or biomass material such as rice husks. Commercial products from companies such as Evonik Degussa, Tosoh Silica Co., Ltd., Solvay Japan Ltd., and Tokuyama Corporation can be used. These may be used individually or in combination of two or more types. In particular, the analytical method disclosed herein can estimate the type (grade), content, and content ratio of each type of silica contained in a sample, not only for samples containing only one type of silica, but also for samples containing two or more types of silica.

[0014] In the elastomer composition (sample), the silica content is not particularly limited. For example, it is 1 to 150 parts by mass, preferably 3 to 100 parts by mass, and more preferably 5 to 80 parts by mass based on 100 parts by mass of the elastomer component. When within the above range, there is a tendency to accurately estimate the type, content, and content ratio of each silica contained in the sample.

[0015] The analysis method of the present disclosure is a method for estimating the type, content, and mixing ratio of the filler present in the elastomer composition (sample) based on the properties, particle size, and particle size distribution of the filler present therein. Examples of the properties of the filler include the shape, surface activity, size of the structure, and aggregate state distribution of the filler.

[0016] Among the properties of the filler, from the viewpoint of accurately estimating the type, content, and content ratio of each filler, it is desirable that the filler be in the form of a shape. The shape of the filler is not particularly limited and includes spherical, needle-like, rod-like, amorphous, and the like.

[0017] The present disclosure is an analysis method for estimating the type, content, and mixing ratio of the filler (such as carbon black, silica, etc.) in the elastomer composition (sample) based on the properties, particle size, and particle size distribution of the filler. From the viewpoint of accurate estimation, it is desirable to subject the sample to high-temperature treatment under a nitrogen atmosphere or an air atmosphere and analyze the filler (the filler in the sample) collected after the treatment.

[0018] For example, such high-temperature treatment and collection of the filler can be carried out by applying the following method to the sample (elastomer composition). The sample is heated to 650°C under a nitrogen atmosphere by thermogravimetric analysis (TGA), and the remaining components (such as carbon black, silica, etc.) are extracted. The remaining components (the filler to be analyzed) are sufficiently dispersed in a solvent (ethanol) by ultrasonic waves and then dropped onto a mesh for transmission electron microscope observation (TEM observation).

[0019] In the above method, 650°C is used as the processing temperature for high-temperature treatment. However, a suitable temperature can be selected to ensure that no elastomer components remain in the sample while retaining the target fillers such as carbon black and silica. For example, it can be performed at 500-800°C. By subjecting the sample (elastomer composition) to high-temperature treatment in this way, it becomes possible to retain and collect the target fillers.

[0020] The above method involves dispersing the remaining components (carbon black, silica, etc.) in a solvent by sonication, but any method that can disperse the target filler (carbon black, silica, etc.) can be appropriately selected. Suitable solvents include ethanol, methanol, tetrahydrofuran, acetone, and other organic solvents, as well as water. In addition to sonication, it is also possible to disperse the filler in the solvent using a high-speed homogenizer, colloid mill, blender mill, etc.

[0021] By using the methods described above, after dropping the filler to be analyzed (carbon black, silica, etc.) onto a mesh for transmission electron microscopy (TEM observation), the properties, particle size, and particle size distribution of the filler present in the sample can be analyzed by applying, for example, the following methods to the filler. TEM observation is performed on the dropped filler material (carbon black, silica, etc.) to be analyzed, and an image is acquired at a magnification sufficient to confirm the primary particle size. Acquire images until the number of particles reaches approximately 300. The particle size is calculated from the acquired image, and the particle size distribution is checked.

[0022] As exemplified by the method described above, which involves TEM observation of the filler to be analyzed (carbon black, silica, etc.), it is preferable to use electron microscopy observation from the viewpoint of being able to accurately estimate the properties, particle size, and particle size distribution of the filler present in the sample (elastomer composition), and scanning electron microscopy (SEM) can also be used.

[0023] The above method, as an example, involves TEM observation and acquiring images until the number of particles reaches approximately 300 at a magnification sufficient to confirm the primary particle size. However, in electron microscopy observation, the magnification and number of particles can be appropriately selected. Furthermore, the particle size of the filler to be analyzed can be determined by observing it with an electron microscope, measuring the particle size of a predetermined number of fillers observed within the field of view, and averaging the results. Here, an example with approximately 300 particles is given, but this is not particularly limited, and the number of particles can be appropriately selected considering factors such as precise measurement accuracy.

[0024] Then, particle size can be obtained from the acquired image, and further, the particle size distribution can be calculated from that particle size. The particle size can be defined as, for example, the diameter of the sphere if the filler is spherical, the shortest diameter if it is needle-shaped or rod-shaped, or the average diameter from the center if it is irregularly shaped.

[0025] This disclosure describes an analytical method for estimating the type, content, and mixing ratio of a filler based on the properties, particle size, and particle size distribution of the filler to be analyzed obtained by the above-mentioned method, but from the viewpoint of being able to estimate accurately, it is desirable that the estimation method be performed by comparing the shape, particle size, and particle size distribution of the filler present in the sample (elastomer composition) with the shape, particle size, and particle size distribution of a standard filler obtained separately.

[0026] An example of such estimation method is described below, but the analytical methods described in this disclosure are not limited to the following methods.

[0027] Samples of formulation 2 (a sample prepared by kneading 66 parts by mass of ISAF, 33 parts by mass of GPF, and 100 parts by mass of diene rubber) and formulation 3 (a sample prepared by kneading 50 parts by mass of ISAF, 50 parts by mass of GPF, and 100 parts by mass of diene rubber) described in the examples below are prepared, and for example, the samples are subjected to high-temperature treatment, collection of the filler (carbon black) to be analyzed, electron microscope observation, image acquisition, and calculation of particle size and particle size distribution using the method described above.

[0028] Regarding the obtained particle size and particle size distribution, Figure 1 shows the particle size distribution of carbon black (the filler to be analyzed) present in two formulation samples, and Figure 2 shows the particle size distribution of carbon black (the filler to be analyzed) present in three formulation samples.

[0029] Figure 3 shows the average particle size distribution, 3σ value, and lower limit control line (LCL) and upper limit control line (UCL) derived from the average and 3σ values ​​of the standard fillers (SAF, ISAF, HAF, FEF, GPF), as well as the characteristics of the standard filler (GPF). Figures 1 and 2 also show graphs related to these standard fillers, showing the average particle size distribution, LCL, and UCL for each standard filler. The average particle size and particle size distribution of the standard fillers can be measured using conventionally known methods. Although five types of carbon black are shown as examples of standard fillers, they are not particularly limited, and any commercially available fillers (other carbon blacks, silica, etc.) can be used.

[0030] Regarding standard fillers, for example, a particle size distribution can be obtained from approximately 300 particles in one image (or field of view). By further processing this distribution across multiple images (or fields of view), the average value of the particle size distribution can be calculated, the distribution can be divided into intervals, the probability of particle existence in each interval can be determined, and the 3σ value can be calculated from the variability across multiple images (or fields of view).

[0031] For example, by comparing and analyzing the particle size distribution of the sample for formulation 2 in Figure 1 or the sample for formulation 3 in Figure 2 with the particle size distribution of standard fillers (SAF, ISAF, HAF, FEF, GPF), it is possible to determine the type of carbon black contained in the sample for formulation 2 and the sample for formulation 3 (whether SAF, ISAF, HAF, FEF, or GPF are included), the amount of carbon black present, and the proportion of two or more types of carbon black present if they are included.

[0032] In particular, from the standpoint of accurate estimation, it is desirable to compare the shape, particle size, and particle size distribution of fillers present in the sample with the shape, particle size, and particle size distribution of a separately obtained standard filler, for example, based on the agreement rate between the particle size distribution of the filler and the particle size distribution of the standard filler.

[0033] Figure 4 shows the results of a comparison and analysis of the particle size distribution of the filler (carbon black) in the sample of formulation 2 with the particle size distribution of GPF as an example from among the standard fillers (SAF, ISAF, HAF, FEF, GPF). Similarly, Figure 5 shows the results of a comparison and analysis of the particle size distribution of the filler (carbon black) in the sample of formulation 3 with the particle size distribution of GPF as an example from among the standard fillers (SAF, ISAF, HAF, FEF, GPF).

[0034] Here, if the percentage of carbon black particles within a specified range (in 5nm increments in Figures 4 and 5) in the sample is within the LCL to UCL range of the standard filler, it is indicated with ○ (match), and if it is outside the range, it is indicated with × (mismatch).

[0035] First, regarding the sample of formulation 2 in Figure 4, the content of carbon black with a particle size between 35 nm and 40 nm (interval 40) in the sample is 9.5%, whereas the GPF in Figure 3 has a particle size between 35 nm and 40 nm (interval 40) within the range of LCL (6.8%) to UCL (16.9%), so it is marked as OK. Furthermore, while the content of carbon black with a particle size between 40 nm and 45 nm (interval 45) in the sample of formulation 2 in Figure 4 is 2.9%, it falls outside the range of LCL (5.9%) to UCL (16.7%) for the particle size between 40 nm and 45 nm (interval 45) in the GPF in Figure 3, and is therefore marked as ×.

[0036] Next, an appropriate particle size range is selected for GPF, and the percentage of ○ within that range is calculated. This calculated value can then be used as an example of the agreement rate with GPF (the agreement rate between the particle size distribution of the filler and the particle size distribution of GPF (standard filler)). For example, in the sample of formulation 2, in the particle size range of over 0 nm and up to 170 nm (interval 5 to 170), the percentage of ○s regarding GPF is (25 (number of ○s) / 34) × 100 = 73.5%, and the agreement rate can be judged as 73.5%.

[0037] The same method can be used to calculate the agreement rate for other standard fillers (SAF, ISAF, HAF, FEF), and the results show a high agreement rate with ISAF.

[0038] Here, for example, the number of peaks in the particle size distribution curve of the sample of formulation 2 can be estimated to represent the number of different types of fillers contained in the sample, and it can also be estimated that the sample contains fillers with a high agreement rate with the standard filler. In the sample of formulation 2 shown in Figure 1, the particle size distribution curve has two peaks, and as mentioned above, the agreement rate with GPF and ISAF is high. Therefore, it can be estimated that the sample of formulation 2 likely contains two types of carbon black: GPF and ISAF.

[0039] Next, regarding the sample of formulation 3 in Figure 5, the content of carbon black with a particle size between 35 nm and 40 nm (interval 40) is 8.9%, whereas in the GPF in Figure 3, the content of LCL (6.8%) to UCL (16.9%) with a particle size between 35 nm and 40 nm (interval 40) is within the range of LCL (6.8%) to UCL (16.9%), so it is marked as ○. Furthermore, while the content of carbon black with a particle size between 40 nm and 45 nm (interval 45) in the sample of formulation 3 in Figure 5 is 4.1%, it falls outside the range of LCL (5.9%) to UCL (16.7%) for the particle size between 40 nm and 45 nm (interval 45) in the GPF in Figure 3, and is therefore marked as ×.

[0040] Next, an appropriate particle size range is selected for GPF, and the percentage of ○ within that range is calculated. This calculated value can then be used as an example of the agreement rate with GPF (the agreement rate between the particle size distribution of the filler and the particle size distribution of GPF (standard filler)). For example, in the sample of formulation 3, in the particle size range of over 0 nm and up to 170 nm (interval 5 to 170), the percentage of ○s regarding GPF is (28 (number of ○s) / 34) × 100 = 82.3%, and the agreement rate can be judged as 82.3%.

[0041] The same method can be used to calculate the agreement rate for other standard fillers (SAF, ISAF, HAF, FEF), and the results show a high agreement rate with ISAF.

[0042] Here, for example, the number of peaks in the particle size distribution curve of the sample of formulation 3 can be estimated to represent the number of different types of fillers contained in the sample, and it can also be estimated that the sample contains fillers with a high agreement rate with the standard filler. In the sample of formulation 3 shown in Figure 2, the particle size distribution curve has two peaks, and as mentioned above, the agreement rate with GPF and ISAF is high. Therefore, it can be estimated that the sample of formulation 3 likely contains two types of carbon black: GPF and ISAF.

[0043] Furthermore, by appropriately scaling up or down the particle size distributions of standard fillers for two or more fillers presumed to be present in the sample, and then synthesizing them to match the particle size distribution of the sample, the proportion of two or more fillers contained in the sample can be calculated. In the sample shown in Figure 1, the proportion of GPF and ISAF can be calculated by scaling up or down the particle size distributions of GPF and ISAF, synthesizing them to match the particle size distribution of the sample.

[0044] Furthermore, the content of each filler can be calculated by comparing the peak height and peak area of ​​the particle size distribution of each of the two or more fillers estimated to be present in the sample with the particle size distribution of the standard filler. In Figure 1, the content of GPF and ISAF in the sample can be calculated by comparing the peak height and peak area of ​​the particle size distribution of GPF in the sample with the particle size distribution of GPF as a standard filler, and by comparing the peak height and peak area of ​​the particle size distribution of ISAF in the sample with the particle size distribution of ISAF as a standard filler.

[0045] Therefore, for example, this method can be used to estimate the type, content, and mixing ratio of two or more fillers contained in a sample (elastomer composition).

[0046] In the examples in Figures 1 and 2, particle size distribution curves are shown with particle size (nm) on the X axis and content percentage (%) on the Y axis. However, distribution curves using other characteristics such as area can also be used.

[0047] Furthermore, while Figures 1-4 above show an example of a method for measuring the agreement rate between the particle size distribution of fillers in a sample and the particle size distribution of a standard filler, any method that can measure the proximity between the particle size distribution of fillers in a sample and the particle size distribution of a standard filler can be used without particular limitations, and the proximity obtained therefrom can also be used as the agreement rate.

[0048] The agreement rate between the particle size distribution of the filler in the sample and that of the standard filler can be measured using known methods. Furthermore, it is possible to automate the process using RPA (Robotic Process Automation), Excel macros, Python, etc., to measure the agreement rate.

[0049] Furthermore, in the method described above, the number of images (or fields of view) is small, so the agreement rate is calculated to estimate what types of fillers are present. However, by increasing the number of data points for each standard filler, reducing the variability within the interval, and simultaneously changing the interval width, for example from 5 nm to 2.5 nm or 1 nm, it is possible to obtain a cleaner particle size distribution curve.

[0050] Similarly, for samples such as formulations 2 and 3, it is possible to obtain a clean particle shape distribution curve by increasing the number of images (or fields of view) and reducing the variability.

[0051] Then, by fitting each particle shape distribution curve, and either using the sample's fitting curve directly or performing waveform separation and comparing it with the standard filler's fitting curve, the types and proportions of fillers contained in the sample can be determined, enabling more accurate analysis.

[0052] Furthermore, AI and machine learning methods can be used for data acquisition and comparison.

[0053] Using the method described above, it is possible to estimate the type, content, and mixing ratio of each filler, not only for samples containing one type of filler, but also for samples containing two or more types of fillers, based on the properties (shape, etc.), particle size, and particle size distribution of the fillers contained in the sample. [Examples]

[0054] The present invention will be specifically described based on the examples provided, but the present invention is not limited to these examples.

[0055] <Sample preparation (example)> First, according to the mixing ratios of the two types of carbon black shown in Table 1 below, diene rubber and the two types of carbon black were added to a 1.7L Banbury mixer and kneaded for 3 minutes under conditions of 150°C to obtain each of the samples (elastomer compositions) of formulations 1 to 7.

[0056] For each sample (elastomer composition), the aforementioned method was used to perform high-temperature treatment of the sample, collect the carbon black to be analyzed, observe with an electron microscope, acquire images, and calculate the particle size and particle size distribution. This yielded the particle size distribution of carbon black present in the samples of Formulation 1 (Figure 6), Formulation 2 (Figure 1), Formulation 3 (Figure 2), Formulation 4 (Figure 7), Formulation 5 (Figure 8), Formulation 6 (Figure 9), and Formulation 7 (Figure 10).

[0057] Furthermore, the average particle size and particle size distribution (average value, LCL, UCL) of standard fillers (SAF, ISAF, HAF, FEF, GPF) were measured using the "Particle Analyzer Luzex" (manufactured by Nireco Corporation), and are shown in Figures 1-2 and 6-10. Furthermore, the mean (average particle size) and standard deviation were calculated from the obtained particle size distribution, and the values ​​are shown in Table 2.

[0058] <Sample preparation (comparative example)> The average particle size and particle size distribution width of each sample (elastomer composition) from formulations 1 to 7 were measured using the "Luzex Particle Analyzer" (manufactured by Nireco Corporation), and the values ​​are shown in Table 1.

[0059] [Table 1]

[0060] [Table 2]

[0061] Then, by applying the same methods as those described in Figures 1-5 to the samples prepared in the examples, and estimating the type, content, and percentage of carbon black contained in formulations 1-7, it was estimated that the samples were highly likely to be those of the carbon black types (ISAF, GPF), content, and percentage listed in Table 1.

[0062] On the other hand, regarding the comparative example, for example, the average particle size of formulation 4 was close to that of FEF, and it could not be estimated that it was a sample containing ISAF and GPF.

[0063] (1) This disclosure provides an analytical method for estimating the type, content, and mixing ratio of fillers in an elastomer composition comprising elastomer components and fillers, This is an analytical method that estimates based on the properties, particle size, and particle size distribution of the filler.

[0064] Disclosure (2) is the analytical method described in Disclosure (1), wherein the properties of the filler are the shape of the filler.

[0065] Disclosure (3) is an analytical method described in Disclosure (2) for estimating the type, content, and mixing ratio of the filler in the elastomer composition based on a comparison of the shape, particle size, and particle size distribution of the filler with the shape, particle size, and particle size distribution of a standard filler obtained separately.

[0066] Disclosure (4) is an analytical method according to any one of Disclosures (1) to (3), which involves treating the elastomer composition at a high temperature under a nitrogen atmosphere or an air atmosphere and analyzing the filler in the collected elastomer composition.

[0067] Disclosure (5) is an analytical method according to any of Disclosures (1) to (4) wherein the properties, particle size, and particle size distribution of the filler are obtained using electron microscopy observation.

[0068] This disclosure (6) is an analytical method described in this disclosure (5) in which the shape, particle size, and particle size distribution of the filler are obtained based on electron microscope images obtained by electron microscope observation.

Claims

1. An analytical method for estimating the type, content, and mixing ratio of fillers in an elastomer composition containing elastomer components and fillers, Based on the properties, particle size, and particle size distribution of the filler, The properties of the filler are the shape of the filler, Based on a comparison of the shape, particle size, and particle size distribution of the filler with the shape, particle size, and particle size distribution of a separately obtained standard filler, the type, content, and mixing ratio of the filler in the elastomer composition are estimated. The comparison is performed based on the agreement rate between the particle size distribution of the filler and the particle size distribution of the standard filler. An analytical method for estimating the number of types of fillers contained in the filler by the number of peaks in the particle size distribution curve of the filler.

2. The analytical method according to claim 1, comprising treating the elastomer composition at a high temperature under a nitrogen atmosphere or an air atmosphere, and analyzing the filler in the collected elastomer composition.

3. The analytical method according to claim 1 or 2, wherein the properties, particle size, and particle size distribution of the filler are obtained by electron microscope observation.

4. The analytical method according to claim 3, wherein the shape, particle size, and particle size distribution of the filler are obtained based on the electron microscope image obtained by the electron microscope observation.

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