Method and apparatus for analyzing resin materials

Abstract

This invention provides a resin material analysis method and a resin material analysis apparatus that can non-destructively evaluate the degree of material degradation accompanied by dehydrochlorination in resin materials containing polymers with chlorine atoms. [Solution] For a resin material containing a polymer containing chlorine atoms, the modification of the resin material accompanied by dehydrochlorination from the polymer is considered a degradation phenomenon. A reference measurement step is performed on multiple reference samples composed of the resin material with different degrees of degradation to obtain multiple reference spectra. A target measurement step is performed on a target sample composed of the resin material with an unknown degree of degradation to obtain a target spectrum. An estimation step is performed on the target spectrum by comparing it with the multiple reference spectra in a wavelength range that includes a region where the absorbance changes due to the degradation phenomenon, in order to estimate the degree of degradation in the target sample.

Description

Technical Field

[0001] The present disclosure relates to a resin material analysis method and a resin material analysis apparatus.

Background Art

[0002] Various resin materials are used as constituent materials for automobile members, aircraft members, electric and electronic devices, etc. When these various devices and members are continuously used over a long period of time, deterioration due to the denaturation of the polymer constituting the resin material may become a problem. In particular, when the polymer contains chlorine atoms such as polyvinyl chloride (PVC), denaturation accompanied by dehydrochlorination may occur in an environment such as high temperature. When dehydrochlorination occurs, changes in the polymer structure such as a decrease in molecular weight, and changes in physical and chemical properties may occur in the resin material.

[0003] In view of the influence of the denaturation of the resin material, methods for determining the presence or absence and degree of denaturation have been proposed so far. For PVC as well, for example, in Non-Patent Document 1, surface deterioration analysis is performed using X-ray photoelectron spectroscopy (XPS). In Non-Patent Document 1, quantitative analysis of the amount of hydrochloric acid and the like is performed.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Several methods are known for evaluating the presence and extent of degradation of resin materials due to polymer modification, including those listed in Non-Patent Document 1. However, these methods are often based on molecular weight measurement, chemical analysis, or physical property measurement, and involve destructive analysis. XPS, used in Non-Patent Document 1, is also an excellent method for identifying and quantifying chemical species, but it requires sample pretreatment and measurement in a measuring device that requires a vacuum. Therefore, it is desirable to be able to analyze the progression of degradation of resin materials constituting various devices and components using non-destructive analysis. If the degree of degradation of resin materials, such as the dehydrochlorination of PVC, can be evaluated using non-destructive analysis, it may be possible to improve convenience in determining whether parts made of a given resin material can be used continuously in a device or component, or in implementing countermeasures if degradation is progressing.

[0006] In view of the above, the objective is to provide a resin material analysis method and a resin material analysis apparatus that can non-destructively evaluate the degree of material degradation accompanied by dehydrochlorination in resin materials containing polymers containing chlorine atoms. [Means for solving the problem]

[0007] The resin material analysis method according to this disclosure includes, for a resin material containing a polymer containing chlorine atoms, a reference measurement step of obtaining multiple reference spectra by performing near-infrared spectroscopy on multiple reference samples composed of the resin material with different degrees of degradation, with the modification of the resin material accompanied by dehydrochlorination from the polymer being considered as a degradation phenomenon; a target measurement step of obtaining a target spectrum by performing near-infrared spectroscopy on a target sample composed of the resin material with an unknown degree of degradation; and an estimation step of estimating the degree of degradation in the target sample by comparing the target spectrum with the multiple reference spectra in a wavelength range that includes a region in which the absorbance changes due to the degradation phenomenon.

[0008] The resin material analysis apparatus described herein is used to perform the resin material analysis method described above. [Effects of the Invention]

[0009] The resin material analysis method and resin material analysis apparatus described herein are capable of non-destructively evaluating the degree of material degradation accompanied by dehydrochlorination in resin materials containing polymers that include chlorine atoms. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows near-infrared spectra of polyvinyl chloride (PVC)-containing resin materials with different degrees of degradation, as examples of reference spectra used in the resin material analysis method of this disclosure. [Figure 2] Figures 2A to 2C show examples of measured physical properties for reference samples obtained at various temperatures and elapsed times. Figure 2A shows the modulus of elasticity, Figure 2B shows the tensile strength, and Figure 2C shows the elongation at break. [Figure 3] Figures 3A to 3C show the relationship between measured physical properties and estimated values ​​obtained from principal component regression analysis. Figure 3A shows the modulus of elasticity, Figure 3B shows the tensile strength, and Figure 3C shows the elongation at break. [Modes for carrying out the invention]

[0011] [Description of Embodiments in this Disclosure] First, embodiments of this disclosure will be listed and described. The resin material analysis method and resin material analysis apparatus according to this disclosure have the following configurations.

[0012] [1] The resin material analysis method according to the present disclosure includes, for a resin material containing a polymer containing chlorine atoms, a reference measurement step of obtaining multiple reference spectra by performing near-infrared spectroscopy measurements on multiple reference samples composed of the resin material with different degrees of degradation, with the modification of the resin material accompanied by dehydrochlorination from the polymer being considered as a degradation phenomenon; a target measurement step of obtaining a target spectrum by performing near-infrared spectroscopy measurements on a target sample composed of the resin material with an unknown degree of degradation; and an estimation step of estimating the degree of degradation in the target sample by comparing the target spectrum with the multiple reference spectra in a wavelength range that includes a region in which the absorbance changes due to the degradation phenomenon.

[0013] The resin material analysis method described herein utilizes near-infrared (NIR) spectroscopy to evaluate the degree of degradation in a resin material accompanied by dehydrochlorination. In NIR spectra, spectral changes corresponding to dehydrochlorination are clearly observed. In other words, as degradation accompanied by dehydrochlorination progresses in a resin material, the NIR spectrum changes. Therefore, by measuring the NIR spectrum of both a reference sample and a target sample, and comparing the multiple reference spectra obtained for the reference sample with the target spectrum obtained for the target sample, the degree of degradation in the target sample can be estimated in comparison with the reference sample. NIR spectra can be obtained by irradiating a sample with NIR light and detecting components including the contribution of NIR absorption by the sample, such as reflected light and transmitted light. Thus, the degree of degradation of a sample can be evaluated non-destructively. NIR spectrum measuring devices are small and highly portable, making them convenient for measuring resin materials that constitute various devices and components.

[0014] [2] In the embodiment of [1] above, the polymer may be polyvinyl chloride (PVC). PVC is widely used as a component material for automotive parts, aircraft parts, electrical and electronic equipment, etc. When resin materials containing PVC are placed in a high-temperature environment, dechlorination tends to progress. However, by applying the resin material analysis method of this disclosure to resin materials containing PVC, the progression of degradation phenomena accompanied by dechlorination can be sensitively detected, and the obtained information can be used for inspection and maintenance of equipment and components.

[0015] [3] In the embodiment of [1] or [2] above, the estimation step may include a wavelength range of 1300 nm to 2100 nm. A clear spectral change corresponding to dehydrochlorination in the resin material appears in the 1300 nm to 2100 nm range. Therefore, by performing the estimation step focusing on a wavelength range including this region, it becomes possible to estimate the degree of progression of the degradation phenomenon accompanied by dehydrochlorination in the target sample sensitively and with high accuracy.

[0016] [4] In any of the embodiments of [1] to [3] above, the comparison of the multiple reference spectra and the target spectrum in the estimation step may be performed using multiple regression analysis. This allows the changes in the NIR spectrum to be accurately and easily correlated with the degree of progression of the degradation phenomenon, and to be reflected in the evaluation of the degree of degradation in the target sample.

[0017] [5] In any of the embodiments described in [1] to [4] above, in the reference measurement step, the physical properties of the resin material are measured for a plurality of reference samples in conjunction with the acquisition of the reference spectrum, and the reference spectrum and the physical properties are associated. In the estimation step, the degree of progression of the degradation phenomenon in the target sample is associated with the change in the physical properties. Degradation of resin materials accompanied by dehydrochlorination tends to lead to changes in the physical properties of the resin material, but by using this method, information on changes in the physical properties of the resin material can be obtained directly based on changes in the NIR spectrum.

[0018] [6] In the above aspect [5], in the estimation step, principal component regression analysis may be used to estimate the physical property value in the target sample from the comparison between the target spectrum and a plurality of the reference spectra. Then, changes in the NIR spectrum can be accurately and simply associated with changes in the physical property value accompanying the progress of the deterioration phenomenon, and reflected in the evaluation of the physical property change accompanying the deterioration phenomenon in the target sample.

[0019] [7] The resin material analyzer according to the present disclosure executes any one of the resin material analysis methods of [1] to [6] above. In the resin material analysis method, as described above, NIR spectra are measured for the reference sample and the target sample, and by comparing the spectra of both, the degree of progress of the deterioration phenomenon accompanied by dehydrochlorination can be evaluated non-destructively for the target sample. The resin material analyzer according to the present disclosure becomes an apparatus that can evaluate the degree of progress of the deterioration phenomenon accompanied by dehydrochlorination in the resin material non-destructively by implementing the analysis method.

[0020] [Details of Embodiments of the Present Disclosure] The resin material analysis method and the resin material analyzer according to the embodiments of the present disclosure will be described below with reference to the drawings.

[0021] <Overview of Resin Material Analysis Method and Resin Material Analyzer> In the resin material analysis method according to the embodiments of the present disclosure, for a resin material containing a polymer containing chlorine atoms, the degree of progress of the deterioration phenomenon is evaluated using near-infrared (NIR) spectroscopy.

[0022] In the resin material analysis method according to the embodiments of the present disclosure, a reference measurement step, a target measurement step, and an estimation step are performed in this order. The reference measurement step and the target measurement step include steps of performing NIR spectroscopic measurement by an NIR spectroscopic measurement device. In the estimation step, analysis of the NIR spectra obtained in the reference measurement step and the target measurement step is performed.

[0023] The resin material analyzer according to the embodiment of this disclosure is configured as an apparatus for performing the resin material analysis method described above. The resin material analyzer can be configured to include both a spectroscopic measuring device for measuring NIR spectra in the reference measurement step and the target measurement step, and an analysis device such as a computer equipped with software for analyzing the obtained NIR spectra and performing an estimation step. Alternatively, it can be configured as an analysis device equipped with software that reads NIR spectra obtained from an independent spectroscopic measuring device to perform the reference measurement step and the target measurement step, and also performs an estimation step on the read spectra.

[0024] <Subject of Analysis> In the resin material analysis method according to embodiments of this disclosure, the resin material to be analyzed is not particularly limited as long as it contains a polymer containing chlorine atoms in its molecular structure. Examples of polymers containing chlorine atoms include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and chlorinated polyolefins.

[0025] In resin materials containing polymers with chlorine atoms, as illustrated above, dehydrochlorination, that is, the detachment of chlorine atoms contained in the polymer from the polymer molecule in the form of hydrochloric acid, is likely to occur. Dehydrochlorination is a factor that causes modification and degradation of the resin material. Therefore, in the resin material analysis method according to this embodiment, the modification of the resin material accompanied by dehydrochlorination from the polymer is considered as a degradation phenomenon of the resin material, and this degradation phenomenon is evaluated using NIR spectroscopy. Below, each step of the resin material analysis method will be explained, mainly using a resin material in which a plasticizer (diisononyl phthalate; DINP) has been added to PVC as an example.

[0026] <Reference measurement process> In the reference measurement step, NIR spectroscopy is performed on multiple reference samples to obtain multiple reference spectra. The reference samples are prepared using the same type of resin material as the target sample whose degradation phenomenon, i.e., the degree of progression of the modification of the resin material accompanied by dehydrochlorination, is to be evaluated. The multiple reference samples are composed of resin materials with different degrees of degradation progression. Different degrees of degradation progression refer to states in which the dehydrochlorination density differs from one another, and also include forms in which no degradation phenomenon occurs. Preferably, one of the multiple reference samples is composed of a sample in which substantially no degradation phenomenon has occurred. In the reference sample, the degradation phenomenon can be advanced by placing the resin material in a high-temperature environment. In order to make the degree of degradation progression differ among the multiple reference samples, it is sufficient to differ at least one of the temperature and elapsed time at which the degradation phenomenon occurs.

[0027] Once the reference samples are prepared, NIR spectroscopy is performed on each reference sample. NIR spectroscopy can be performed using a known NIR spectrometer. For the measurement, NIR light is incident on the reference sample, and the transmitted or reflected light is detected. Then, the absorbance at each wavelength is calculated from the intensity of the incident and detected light, and this is obtained as the NIR spectrum. The conditions for NIR spectroscopy should be kept consistent among multiple reference samples. The range of wavelengths for measurement in NIR spectroscopy is not particularly limited, but it is preferable to set the wavelength range to include at least the region in which absorbance changes due to degradation phenomena, that is, the region in which absorbance changes due to dehydrochlorination. For example, it is preferable to set the wavelength range to include the range from 1300 nm to 2100 nm.

[0028] As a specific example, Figure 1 shows NIR spectra obtained by reflectance measurements for several samples of a resin material containing PVC, each exhibiting a different degree of degradation. In the reference measurement process, it is sufficient to prepare a group of NIR spectra as shown in Figure 1. For each spectrum shown in Figure 1, the resin material was heated in air while varying the temperature and elapsed time, as described in the legend, to allow the degradation phenomenon to progress. Those labeled "Initial" represent the initial state of the sample before heating, where virtually no degradation has occurred.

[0029] In the spectral group shown in Figure 1, changes occur in the spectra with changes in temperature and elapsed time. In particular, in each spectrum, two distinct peaks, indicated by symbols A and B, appear in the region between wavelengths of 1300 nm and 2100 nm. The spectral changes with changes in temperature and elapsed time are particularly pronounced in the region containing these peaks A and B. Peaks A and B are thought to include contributions from CH stretching vibrations at the C=C double bond site. Furthermore, in PVC, when chlorine atoms are removed by dehydrochlorination, a new C=C double bond is formed, and the intensity of peaks A and B is thought to increase.

[0030] Detailed observation of spectral changes in the wavelength range of 1300 nm to 2100 nm with changes in temperature and elapsed time under high-temperature conditions reveals that, generally, when exposed to high temperatures and for extended periods, the peak heights (relative to the background level, specifically the shorter and longer wavelength regions relative to the peaks, respectively) tend to increase for both peaks A and B. This trend is particularly pronounced with increasing temperature.

[0031] The growth of peaks A and B reflects that dehydrochlorination occurred under high-temperature conditions, causing the resin material to denature. In other words, the changes in the spectral group in Figure 1 with increasing temperature and elapsed time indicate that the degradation phenomenon in the resin material is progressing. From this, it can be seen that the degree of progression of the degradation phenomenon in the resin material can be estimated from the state of the NIR spectrum, especially the state in the wavelength region from 1300 nm to 2100 nm. It should be noted that plasticizers are generally added to PVC, and as mentioned above, the resin material measured in Figure 1 also contains plasticizers. When the resin material is placed under high-temperature conditions, the plasticizer in the resin material may decrease due to volatilization and migration to contacting substances, along with the progression of dehydrochlorination. The decrease in plasticizers, along with dehydrochlorination, can also be a factor that causes the degradation of the resin material. The changes in the NIR spectrum in the wavelength region from 1300 nm to 2100 nm may be contributed not only to dehydrochlorination but also to the decrease in plasticizers.

[0032] If you wish to obtain estimated physical properties of the target sample in a later estimation process, then in this reference measurement process, you should measure the physical properties of the resin material for each of the multiple reference samples, in addition to obtaining the reference spectrum described above. There are no particular limitations on the types of physical properties to be measured; you should measure the types of physical properties for which you wish to obtain information about the target sample. For example, the (tensile) modulus, tensile strength, and elongation at break of the resin material can be used as examples.

[0033] As an example, Figures 2A and 2C show the results of physical property measurements performed on resin materials after being exposed to high-temperature environments at various temperatures and elapsed times, including the sample whose NIR spectrum is shown in Figure 1. Figure 2A shows the modulus of elasticity, Figure 2B shows the tensile strength, and Figure 2C shows the elongation at break. For all three physical properties, the values ​​change with changes in temperature and elapsed time. In other words, it is confirmed that the material properties change as the resin material deteriorates. In particular, a systematic change is clearly observed in the modulus of elasticity. At temperatures below 100°C, the measured value decreases with increasing temperature and elapsed time, while at temperatures above 140°C, the measured value increases with increasing temperature and elapsed time. At 120°C, the measured value changes from decreasing to increasing with increasing elapsed time.

[0034] <Target Measurement Process> In the target measurement process, NIR spectroscopy is performed on a sample whose degree of degradation is unknown, that is, a target sample whose degree of degradation is unknown. The NIR spectroscopy should be performed in the same manner as for the reference sample. The conditions for NIR spectroscopy should be the same for the target sample and each reference sample.

[0035] <Estimated process> In the estimation step, the target spectrum obtained in the target measurement step is compared with multiple reference spectra obtained in the reference measurement step. The comparison is performed on the NIR spectrum in a wavelength region in which the absorbance changes due to the degradation phenomenon. Preferably, the comparison is performed in a wavelength region that includes the region between 1300 nm and 2100 nm. Based on the results of the comparison, the degree of progression of the degradation phenomenon in the target sample is estimated.

[0036] In the comparison, the degree of degradation in the target sample is correlated to the degree of degradation in the reference sample based on which of the series of reference spectra shown in Figure 1 the target spectrum is closest to, and / or how close it is to one or more reference spectra, within the set wavelength range. For example, if the state of the target spectrum is sufficiently similar to a certain reference spectrum, it can be estimated that the degradation in the target sample is progressing to the same extent as the degradation in the reference sample that gives that reference spectrum. Alternatively, if the state of the target spectrum is intermediate between two reference spectra, it can be estimated that the degradation in the target sample is intermediate between the degradation in the two reference samples that give those two reference spectra, respectively. As shown in the series of spectra in Figure 1, the progression of degradation is clearly reflected in the increase in intensity of peaks A and B that appear in the region between 1300 nm and 2100 nm. Therefore, if the intensity of these peaks in the target spectrum is similar to that of a certain reference spectrum, it can be estimated that the progression of degradation in the target sample is similar to that of the reference sample that gives that reference spectrum. Furthermore, if the intensity of these peaks in the target spectrum is midway between the intensity of the peaks in two reference spectra, it can be estimated that the progression of degradation in the target sample corresponds to a midpoint between the progression of degradation in the two reference samples that give those two reference spectra, respectively.

[0037] When comparing each reference spectrum with a target spectrum, one method for determining the similarity between the reference spectrum and the target spectrum is to directly determine the similarity of the overall shape of the spectrum in a predetermined wavelength range. Alternatively, one method is to compare representative values ​​extracted from the spectrum, such as absorbance, peak height, peak integral intensity, and peak width at a predetermined wavelength, such as the peak of a certain peak (e.g., peak B). Using multiple regression analysis such as principal component analysis (PCA) is also preferable. Furthermore, machine learning may be used. When using machine learning, a learning model can be created by performing machine learning using the relationship between the group of reference spectra and the degree of degradation progression as training data, and then applying that learning model to the target spectrum.

[0038] When comparing a reference spectrum with a target spectrum using the methods described above, it is preferable to pre-process each NIR spectrum prior to the comparison. Examples of pre-processing include wavelength range extraction, spectrum averaging, standardization, smoothing, and background removal. Of these, smoothing can be performed using methods such as the Savitzky-Golay method.

[0039] Furthermore, when correlating the degree of degradation in the target sample with the degree of degradation in the reference sample based on the comparison results of the reference spectrum, one method of correspondence is to directly associate the degree of degradation experienced by the target sample with the conditions of degradation experienced by the reference sample, such as "corresponding to degradation caused by heating in air at a temperature of X°C for Y hours." Alternatively, the degree of degradation in the reference sample can be ranked in multiple stages, and the degree of degradation in the target sample can be associated with these ranks. In addition, if the degree of degradation in each reference sample, which is a known sample, is quantitatively determined in advance by molecular weight measurement or chemical analysis, in the form of the amount of dechlorination, the degree of degradation in the target sample can also be quantitatively estimated.

[0040] Alternatively, as described above, if the physical properties of each reference sample are measured in the reference measurement step and the reference spectrum is correlated with the physical properties, then in this estimation step, the degree of progression of the degradation phenomenon in the target sample can be correlated with the physical properties. In other words, for the target sample, physical properties such as elastic modulus, tensile strength, and elongation at break can be estimated for the state in which it has undergone modification due to the degradation phenomenon. The estimation of physical properties can be performed, for example, using multiple regression analysis such as principal component regression analysis (PCR), as will be explained later, based on the comparison between the target spectrum and the reference spectrum, and the correspondence between the reference spectrum and the physical properties.

[0041] <Examples of applications of resin material analysis methods> As described above, by performing NIR spectroscopy measurements on multiple reference samples and the target sample, and comparing the obtained NIR spectra, the degree of degradation in the target sample can be estimated. As reference samples, as explained in relation to Figure 1, multiple samples can be prepared in which the degradation phenomenon has progressed under conditions in which parameters such as temperature and elapsed time are controlled, and the degree of degradation varies. On the other hand, as the target sample, materials that actually constitute a part of a device or component, such as automotive parts, aircraft parts, or electrical and electronic equipment, can be suitably applied. Materials that have undergone actual use for a certain period of time can also be applied. In this way, by applying constituent materials of devices and components actually used as target samples and estimating the degree of degradation in those constituent materials and the resulting changes in physical properties, it is possible to determine, for example, whether measures to counteract the progression of degradation and changes in physical properties, such as replacement or maintenance, should be taken for parts containing those constituent materials. Furthermore, information on the progression of degradation can be used as basic information for future consideration and development of constituent materials, as well as for consideration of the usage environment of constituent materials.

[0042] NIR absorption spectroscopy is a method that quantitatively obtains information about the chemical state of an object to be evaluated simply by the incidence and detection of light onto the object. Therefore, in the resin material analysis method according to this embodiment, the degree of progression of degradation phenomena involving dehydrochlorination can be evaluated non-destructively and non-invasively for the object to be evaluated. Furthermore, physical properties that change with the progression of degradation can be estimated without actual measurement. These points are particularly advantageous when the object to be evaluated constitutes an actual device or component in use, as described above. Moreover, in the resin material analysis method according to this embodiment, since the degree of progression of degradation phenomena is evaluated by focusing on changes in the NIR spectrum, the degree of degradation phenomena of the resin material can be detected and evaluated sensitively and with high accuracy through changes in the chemical state of the resin material associated with the degradation phenomenon.

[0043] <Estimation of physical properties using multiple regression analysis> Finally, as an example of a method for performing the estimation process, we will specifically explain how to estimate physical properties using multiple regression analysis. Here, we will describe a form of multiple regression analysis that uses principal component regression analysis (PCR).

[0044] In the estimation process, to estimate the physical properties of the target sample, as explained above, in the reference measurement process, reference spectra are obtained and the physical properties of interest are measured for multiple reference samples, and the reference spectra and physical properties are associated. In the estimation process, first, appropriate preprocessing such as averaging, standardization (normalization), and smoothing using the Savitzky-Golay method is applied to each reference spectrum, and then the optimal number of principal components is verified for the group of reference spectra. The optimal number of principal components can be set, for example, to a level where the contribution rate no longer effectively improves as the number of principal components increases. Next, principal component analysis (PCA) is performed on the group of reference spectra with the set optimal number of principal components. Then, the scores of multiple principal components are extracted. For example, the scores of the first principal component, second principal component, and third principal component can be extracted. Furthermore, regression analysis is performed between the physical properties measured for each reference sample and the scores of each extracted principal component. As a result of the regression analysis, a regression equation containing one or more regression coefficients and intercepts is obtained.

[0045] Next, the target spectrum is preprocessed as appropriate, similar to the reference spectrum, and the loading is determined for each principal component (e.g., the 1st to 3rd principal components). Then, the score for each principal component is calculated from the obtained loading. By applying the scores obtained from the target spectrum to the regression equation obtained above, estimated values ​​of the physical properties can be obtained. The obtained estimated values ​​correspond to the physical properties that the resin material of the target sample is estimated to possess, corresponding to the degree of degradation that the target sample has experienced. In other words, the estimated values ​​of the physical properties indirectly indicate the degree of degradation that the target sample has experienced.

[0046] Figures 3A-3C show the results of verifying the validity of estimating physical properties using the principal component regression analysis described above. In Figures 3A-3C, for the reference sample whose physical property measurement results are shown in Figures 2A-2C, the measured values ​​(values ​​plotted in Figures 2A-2C) are plotted on the horizontal axis, and the estimated values ​​obtained using principal component regression analysis are plotted on the vertical axis. Figure 3A shows the modulus of elasticity, Figure 3B shows the tensile strength, and Figure 3C shows the elongation at break. Each dashed line indicates the state where the measured value and the estimated value are equal. In addition, Table 1 below shows the optimal number of principal components, cumulative contribution rate, and coefficient of determination (R) for each physical property value in the principal component regression analysis. 2 ) indicates.

[0047] [Table 1]

[0048] As shown in Figures 3A-3C, the plotted points for all three material properties are well distributed along the dashed lines, indicating that the estimation of material properties by principal component regression analysis is highly accurate. In Table 1, the cumulative contribution rate is large, exceeding 0.70, and the coefficient of determination is large, exceeding 0.87, which also supports the validity of applying principal component regression analysis. In particular, for the elastic modulus, the plotted points are distributed with high uniformity over a wide range of values, and the coefficient of determination is the largest, indicating that the estimation of the value by principal component regression analysis is especially accurate.

[0049] Although embodiments of the present disclosure have been described in detail above, the present invention is not limited in any way to the above embodiments, and various modifications are possible without departing from the spirit of the present invention.

Claims

1. Regarding resin materials containing polymers that contain chlorine atoms, The modification of the resin material, accompanied by the dehydrochlorination of the polymer, is considered a degradation phenomenon. A reference measurement step involves performing near-infrared spectroscopy measurements on multiple reference samples composed of resin materials with different degrees of degradation to obtain multiple reference spectra, A target measurement step involves performing near-infrared spectroscopy on a target sample composed of the resin material whose degree of degradation is unknown, in order to obtain a target spectrum. A resin material analysis method comprising: an estimation step of estimating the degree of progression of the degradation phenomenon in a target sample by comparing the target spectrum with a plurality of reference spectra in a wavelength range that includes a region in which the absorbance changes due to the degradation phenomenon.

2. The resin material analysis method according to claim 1, wherein the polymer is polyvinyl chloride.

3. The resin material analysis method according to claim 1, wherein in the estimation step, the wavelength range includes a region of 1300 nm to 2100 nm.

4. The resin material analysis method according to claim 1, wherein the comparison of a plurality of reference spectra and the target spectrum in the estimation step is performed using multiple regression analysis.

5. In the aforementioned reference measurement step, for multiple reference samples, the physical properties of the resin material are measured in conjunction with the acquisition of the reference spectrum, and the reference spectrum and the physical properties are associated with each other. The resin material analysis method according to claim 1, wherein in the estimation step, the degree of progression of the degradation phenomenon in the target sample is associated with the change in the physical property value.

6. The resin material analysis method according to claim 5, wherein in the estimation step, principal component regression analysis is used to estimate the physical properties of the target sample from a comparison between the target spectrum and a plurality of reference spectra.

7. A resin material analyzer that performs the resin material analysis method according to any one of claims 1 to 6.

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