Method for inspecting quality of resin material

Abstract

To provide a quality inspection method of a resin material capable of nondestructively evaluating the susceptibility of the resin material containing a base polymer of a fluororesin and a pigment to external damage.SOLUTION: And an evaluation step of evaluating a degree of aggregation of the pigment in the resin material based on a distribution of an intensity of a first peak attributed to molecular vibration or lattice vibration of the pigment obtained by the mapping measurement, in which a base polymer of the resin material is a fluorine-based resin.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for inspecting the quality of a resin material. [Background technology]

[0002] Conventionally, cables have been known that have a sheath made of a material containing a fluororesin as the base polymer and a pigment as a colorant (see Patent Document 1). In the cable described in Patent Document 1, perfluoroalkoxyalkane (referred to as perfluoroalkoxy fluororesin in Patent Document 1: PFA), polytetrafluoroethylene (PTFE), or the like is used as the fluororesin that is the base polymer of the sheath. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-025001 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have confirmed that insulated wires and cables having an insulating coating made of a resin material consisting of a fluorine-based resin containing a pigment, such as the cable described in Patent Document 1, may be prone to external damage (cracks) during processing (assembly) depending on the manufacturing conditions, etc.

[0005] Therefore, if it were possible to non-destructively evaluate the susceptibility of resin materials to external damage, it would be possible to select insulated wires and cables that reduce the occurrence of external damage to resin materials during processing.

[0006] An object of the present invention is to provide a quality inspection method for resin materials that can non-destructively evaluate the susceptibility to external damage of resin materials whose base polymer is a fluorine-based resin and which contain pigments. [Means for solving the problem]

[0007] The present invention provides a quality inspection method for a resin material, comprising: a measurement step of irradiating a resin material containing a pigment with a laser and performing a mapping measurement of the Raman spectrum; and an evaluation step of evaluating the degree of aggregation of the pigment in the resin material based on the distribution of intensities of first peaks attributable to molecular vibrations or lattice vibrations of the pigment obtained by the mapping measurement, wherein the base polymer of the resin material is a fluorine-based resin. [Effects of the Invention]

[0008] According to the present invention, a quality inspection method for resin materials can be provided that can non-destructively evaluate the susceptibility to external damage of resin materials whose base polymer is a fluorine-based resin and which contain pigments. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a radial cross-sectional view of a cable according to an embodiment of the present invention. [Figure 2] Figures 2(a) and (b) show an optical microscope image of the surface of the insulating coating of sample A and an example of a Raman spectrum obtained by Raman scattering measurement of the surface of the insulating coating. [Figure 3] Figures 3(a) and (b) show an optical microscope image of the surface of the insulating coating of sample B and an example of a Raman spectrum obtained by Raman scattering measurement of the surface of the insulating coating. [Figure 4] Figure 4(a) is a mapping image of sample A formed on the optical microscope image of Figure 2(a). Figure 4(b) is a histogram showing the frequency distribution of the pigment concentration contained in each pixel of the mapping image of sample A shown in Figure 4(a). [Figure 5] Figure 5(a) is a mapping image of sample B formed on the optical microscope image of Figure 3(a). Figure 5(b) is a histogram showing the frequency distribution of the pigment concentration contained in each pixel of the mapping image of sample B shown in Figure 5(a). [Figure 6]Figure 6(a) is a mapping image of sample A, and Figure 6(b) is a binarized version of the mapping image of Figure 6(a). Figure 6(c) is a histogram showing the frequency distribution of the number of white pixels for each of the multiple partitioned regions in the binarized mapping image of Figure 6(b). [Figure 7] Figure 7(a) is a mapping image of sample B, and Figure 7(b) is a binarized version of the mapping image of Figure 7(a). Figure 7(c) is a histogram showing the frequency distribution of the number of white pixels for each of the multiple partitioned regions in the binarized mapping image of Figure 7(b). DETAILED DESCRIPTION OF THE INVENTION

[0010] (Quality inspection method for resin materials) According to the quality inspection method for resin materials of the embodiment of the present invention, the degree of pigment aggregation in a resin material containing a pigment can be evaluated using Raman scattering measurement, and the susceptibility of the resin material to external damage such as cracks can be predicted.

[0011] Examples of resin materials include an insulating coating layer (hereinafter referred to as insulating coating) provided on the outermost side of an insulated wire or cable, a sheet, or a structure such as a cylinder. An insulating coating is, for example, an insulator that covers a conductor in an insulated wire or a sheath in a cable. The resin material according to an embodiment of the present invention has a base polymer that is a fluorine-based resin and contains a pigment as a colorant. The resin material is formed by extrusion using an extruder.

[0012] Raman scattering measurement allows for the non-destructive evaluation of the degree of pigment aggregation in resin materials. Furthermore, since the measurement can be performed without contact, contamination of the resin material during measurement can be avoided. Furthermore, Raman scattering measurement does not alter the fluororesin, as does SEM-EDS, which irradiates electron beams, so there is no risk of losing information about the original state of the resin material due to alteration.

[0013] Furthermore, in Raman scattering measurements, the measurement area is the diameter of the laser spot irradiated on the surface of the resin material, making it possible to measure within a very small area with a diameter of 1 μm or less. This makes it possible to measure the distribution of pigment concentration in a very small area of ​​a few tens of μm or less, which is difficult to do with FT-IR, for example. Furthermore, Raman scattering measurements make it possible to measure the spectra of inorganic pigments, which is difficult to do with FT-IR, for example.

[0014] Although it is difficult to evaluate whether the pigment is uniformly distributed using point measurements, the mapping measurement described below makes it possible to accurately evaluate whether the pigment is uniformly distributed, and this also makes it possible to reveal differences in the degree of pigment aggregation in the resin material for each sample.

[0015] The type of fluorine-based resin that is the base polymer of the resin material according to the embodiment of the present invention is not particularly limited, and may be crosslinked or not. For example, PFA (perfluoroalkoxyalkane), PTFE (polytetrafluoroethylene), FEP (perfluoroethylenepropene copolymer), ETFE (ethylenetetrafluoroethylene copolymer), PVDF (polyvinylidene fluoride), PCTFE (polychlorotrifluoroethylene), ECTFE (ethylenechlorotrifluoroethylene copolymer), etc. can be used as the fluorine-based resin that is the base polymer of the resin material.

[0016] The type of pigment contained in the resin material according to the embodiment of the present invention is not particularly limited, and may be either inorganic or organic, and the color is also not limited. As long as the pigment has the property of agglomerating within the resin material, its degree of agglomeration can be evaluated using the quality inspection method for resin material according to the embodiment of the present invention. For example, cobalt titanate green, chrome oxide green, etc. can be used as the pigment. The pigment is contained in the resin material at a concentration that affects the susceptibility of the resin material to external damage when agglomerated. For example, KREMER-PIGMENTE's 44100 Cobalt Green can be used as the cobalt titanate green.

[0017] The present inventors have found that the higher the degree of pigment agglomeration in a resin material, the more likely external damage such as cracks will occur in the insulating coating during processing of an insulated electric wire or cable. It is believed that areas with high pigment agglomeration have large localized strains, which are likely to cause cracks to occur from these areas. The present inventors have established a quality inspection method for a resin material according to an embodiment of the present invention, which predicts the susceptibility of a resin material to external damage by evaluating the degree of pigment agglomeration in the resin material.

[0018] A quality inspection method for a resin material according to an embodiment of the present invention includes a measurement step of irradiating a pigment-containing resin material with a laser and performing Raman spectrum mapping measurement, and an evaluation step of evaluating the degree of aggregation of the pigment in the insulating coating based on the distribution of intensities of peaks (referred to as first peaks) attributed to molecular vibrations or lattice vibrations of the pigment obtained by the mapping measurement. Examples of pigment-containing resin materials include insulating coatings for insulated wires or cables.

[0019] Mapping measurement is a measurement method in which measurements are repeated while scanning a measurement point (a laser irradiation point) within a predetermined measurement area on the surface of a measurement object. The mapping image, which is two-dimensional measurement data obtained by mapping measurement, contains data on the intensity of the first peak contained in the Raman spectrum obtained in one Raman scattering measurement (for example, the intensity of the first peak normalized by the intensity of the second peak described below) for each pixel.

[0020] The intensity of the first peak, which is attributed to the molecular vibration or lattice vibration of the pigment, increases as the pigment concentration in the measurement area increases. Therefore, the pigment concentration distribution can be derived from the distribution of the first peak intensity obtained by Raman spectrum mapping measurement. Furthermore, since the greater the deviation in the pigment concentration distribution, the higher the degree of aggregation, the greater the degree of aggregation can be evaluated from the pigment concentration distribution.

[0021] A specific method for deriving the pigment concentration distribution from the intensity of the first peak includes, for example, binarizing the mapping image obtained by mapping measurement by setting a threshold value for the intensity value of the first peak contained in each pixel of the mapping image, and then counting the number of pixels of at least one color for each of a plurality of regions (referred to as divided regions) of the same area divided in the binarized mapping image. The threshold value can be set appropriately to a value that makes it easy to determine the bias in the pigment concentration distribution from the binarized mapping image, for example.

[0022] For example, if the mapping image is binarized so that pixels whose first peak intensity is equal to or greater than a threshold are colored white and pixels whose first peak intensity is less than the threshold are colored black, the pigment concentration distribution can be derived by measuring the number of white pixels in each of multiple divided regions.

[0023] That is, in the above evaluation process, a threshold value is set for the intensity value of the first peak contained in each pixel of the mapping image obtained by the mapping measurement, and the mapping image is binarized, and the degree of pigment aggregation can be evaluated based on the number of pixels of at least one color for each of the multiple divided areas.

[0024] Furthermore, a specific method for evaluating the degree of pigment aggregation from the pigment concentration distribution is, for example, to calculate the frequency distribution of the number of pixels of at least one color for each of a plurality of divided regions, and evaluate the degree of aggregation as the coefficient of variation obtained by dividing the standard deviation of the frequency distribution by the mean value of the frequency distribution.

[0025] For example, when the mapping image is binarized so that pixels whose first peak intensity is equal to or greater than a threshold are colored white and pixels whose first peak intensity is less than the threshold are colored black, the frequency distribution of the number of white pixels for each of the multiple divided regions is calculated, and the coefficient of variation obtained by dividing the standard deviation of the frequency distribution by the mean value of the frequency distribution can be evaluated as the degree of aggregation.

[0026] The first peak used in the evaluation step is typically the peak with the greatest intensity among the peaks attributed to molecular vibration or lattice vibration of the pigment. For example, when Cobalt titanate green is used as the pigment, A 1g The Raman spectrum shows a lattice vibration at 688 cm -1 That's all, 724cm -1 The peak having the maximum peak height within the following range can be used as the first peak. 1g The 532 cm in the Raman spectrum is attributed to the lattice vibration of the mode -1 Above, 568cm -1 The peak with the maximum peak height within the following range can be used as the first peak. Note that the wavenumber at which each peak in the Raman spectrum has a maximum height may shift depending on factors such as the environmental temperature during measurement, but the magnitude relationship between the wavenumbers at which these peaks have a maximum height remains unchanged, so there is no risk of misidentifying the peaks.

[0027] In order to reduce the influence of measurement conditions, etc., the intensity of the first peak is preferably normalized by the intensity of a peak (referred to as the second peak) attributed to the molecular vibration of the fluororesin, which is the base polymer of the insulating coating. The second peak is typically the peak with the greatest intensity among the peaks attributed to the molecular vibration of the fluororesin.

[0028] For example, when PFA, PTFE, or FEP is used as the fluororesin, the Raman spectrum shows a peak at 724 cm attributable to CF symmetric stretching. -1 More than 760cm -1 The peak having the maximum peak height within the following range can be used as the second peak.

[0029] In addition, when ETFE is used as the fluororesin, a Raman spectrum of 812 cm attributable to CF symmetric stretching is observed. -1 Above, 848cm -1 The peak with the maximum peak height within the following range can be used as the second peak. When PVDF is used as the fluororesin, the peak at 776 cm in the Raman spectrum, which is attributed to the CH rocking deformation vibration, can be used as the second peak. -1 That's all, 812cm -1 The peak with the maximum peak height within the following range can be used as the second peak. When PCTFE is used as the fluorine-based resin, the peak at 649 cm in the Raman spectrum, which is attributed to CC stretching, can be used as the second peak. -1 That's all, 685cm -1 The peak with the maximum peak height within the following range can be used as the second peak. When ECTFE is used as the fluororesin, the peak at 2956 cm in the Raman spectrum, which is attributed to CH symmetric stretching, can be used as the second peak. -1 Above, 2992cm -1 The peak having the maximum peak height within the following range can be used as the second peak.

[0030] The peak height or the integrated intensity of the peak can be used as the intensity of the first peak or the second peak. The peak height can be calculated, for example, as the average value of the peak heights in the range where each of the above peaks is at its maximum. For example, the peak height of the first peak of Cobalt titanate green is 688 cm -1 That's all, 724cm -1 It is calculated as the average value of peak heights within the following range: The integrated intensity of a peak can be calculated, for example, using the Covell method.

[0031] (Cable configuration) 1 is a radial cross-sectional view of a cable 1, which is an example of an insulated wire or cable according to an embodiment of the present invention. The cable 1 is a so-called ultra-fine cable having a diameter of several hundred μm, and includes a conductor 10 and an insulator 11 that covers the conductor 10.

[0032] The conductor 10 is a twisted wire formed by twisting together a plurality of wires made of, for example, copper wires, copper alloy wires, etc. The insulator 11 is made of a resin material whose base polymer is a fluorine-based resin and which contains a pigment as a colorant.

[0033] (Specific examples of quality inspection methods for insulating coating) A specific example of a quality inspection method for resin materials according to an embodiment of the present invention will be described below. In this example, Raman spectrum mapping measurements were performed on a sample (referred to as Sample A) of ultra-thin cables with an insulating coating approximately 20 μm thick, each having a base polymer of PFA and containing Cobalt titanate green as a pigment, in which the insulating coating is prone to damage during processing, and a sample (referred to as Sample B) in which the insulating coating is less prone to damage during processing, to evaluate the degree of pigment aggregation in the insulating coating.

[0034] The insulating coating of sample A was formed without adequately mixing the material during the extrusion coating process, while the insulating coating of sample B was formed with adequately mixing the material during the extrusion coating process. Both samples A and B were extrusion coated at a temperature above the melting point of PFA.

[0035] The measurement conditions for mapping measurement are shown in Table 1. The theoretical value of the laser irradiation diameter, calculated based on Abbe's definition using the laser excitation wavelength (532.06 nm) and objective lens numerical aperture (NA 0.90) in Table 1, is 0.36 μm.

[0036] [Table 1]

[0037] Figures 2(a) and (b) show an optical microscope image of the surface of the insulating coating of sample A and an example of a Raman spectrum obtained by Raman scattering measurement of the surface of the insulating coating. The two Raman spectra shown in Figure 2(b) were measured at measurement positions A1 and A2, indicated by the cross marks in Figure 2(a).

[0038] Figures 3(a) and (b) show an optical microscope image of the surface of the insulating coating of sample B and an example of a Raman spectrum obtained by Raman scattering measurement of the surface of the insulating coating. The two Raman spectra shown in Figure 3(b) were measured at measurement positions B1 and B2, indicated by the cross marks in Figure 3(a).

[0039] In Figures 2(b) and 3(b), the position of the first peak P1 attributed to the molecular vibration or lattice vibration of the pigment and the position of the second peak P2 attributed to the molecular vibration of the fluororesin, which is the base polymer of the insulating coating, are shown by dashed lines.

[0040] Measurement positions A1 and B1 are examples of positions where the intensity of the first peak P1 on the surface of the insulating coating of samples A and B is relatively low, and the pigment concentration is relatively low. On the other hand, measurement positions A2 and B2 are examples of positions where the intensity of the first peak P1 on the surface of the insulating coating of samples A and B is relatively high, and the pigment concentration is relatively high.

[0041] Figure 4(a) is a mapping image of sample A formed on the optical microscope image of Figure 2(a). Figure 5(a) is a mapping image of sample B formed on the optical microscope image of Figure 3(a).

[0042] Each pixel in the mapping images in Figures 4(a) and 5(a) contains pigment concentration data obtained from the Raman spectrum measured at that position, and each pixel has a color corresponding to the magnitude of the pigment concentration.

[0043] Here, the pigment concentration was determined as the intensity of the first peak normalized by the intensity of the second peak, i.e., the value obtained by dividing the intensity of the first peak by the intensity of the second peak (intensity of the first peak / intensity of the second peak). In calculating the pigment concentration contained in each pixel of these mapping images, the peak heights of the first and second peaks were used as the intensities of the first and second peaks.

[0044] Figure 4(b) is a histogram showing the frequency distribution of the pigment concentration contained in each pixel of the mapping image of sample A shown in Figure 4(a). Figure 5(b) is a histogram showing the frequency distribution of the pigment concentration contained in each pixel of the mapping image of sample B shown in Figure 5(a).

[0045] In the histograms shown in Figures 4(b) and 5(b), the range of pigment concentration (the intensity of the first peak normalized by the intensity of the second peak) from minimum to maximum is divided into 256 classes, and the horizontal axis represents the frequency, which is the number of pixels in each class, and the vertical axis represents the frequency.

[0046] The average value of the frequency distribution of the pigment concentration in the insulating coating of sample A calculated from the histogram shown in Figure 4(b) is 0.5445. The average value of the frequency distribution of the pigment concentration in the insulating coating of sample B calculated from the histogram shown in Figure 5(b) is 0.5310. Note that the average value of the frequency distribution of the pigment concentration may also be determined from the frequency distribution table on which the histogram is based, rather than from the histogram.

[0047] As described above, there was no significant difference between the mean value of the frequency distribution of the pigment concentration in the insulating coating of sample A and the mean value of the frequency distribution of the pigment concentration in the insulating coating of sample B. This suggests that the susceptibility of external damage to the insulating coating is not significantly affected by the mean value of the frequency distribution of the pigment concentration in the insulating coating.

[0048] Figure 6(a) is a mapping image of sample A, and Figure 6(b) is a binarized mapping image of Figure 6(a). Figure 7(a) is a mapping image of sample B, and Figure 7(b) is a binarized mapping image of Figure 7(a).

[0049] The mapping images in Figures 6(b) and 7(b) are binarized so that pixels whose pigment concentration (the intensity of the first peak normalized by the intensity of the second peak) is equal to or greater than a threshold are white, and pixels whose pigment concentration is less than the threshold are black.

[0050] Furthermore, in the mapping images of Figures 6(b) and 7(b), a 120 pixel x 120 pixel region is partitioned into 144 square regions (division regions) of equal area (12 vertical x 12 horizontal). Each division region has 10 pixels x 10 pixels, with one pixel being 0.4 μm. Of these multiple division regions, regions with a large number of white pixels can be determined to be regions with a high pigment concentration. Therefore, the pigment concentration distribution can be derived from the binarized mapping image.

[0051] Figure 6(c) is a histogram showing the frequency distribution of the number of white pixels for each of the multiple partitioned regions in the binarized mapping image of Figure 6(b). Figure 7(c) is a histogram showing the frequency distribution of the number of white pixels for each of the multiple partitioned regions in the binarized mapping image of Figure 7(b).

[0052] In the histograms shown in Figures 6(c) and 7(c), the horizontal axis represents the number of white pixels per unit divided area, ranging from 0 to 100 (pixels / divided area). The vertical axis represents the frequency, which is the number of divided areas. There are 144 divided areas per unit mapping image, for a total of 14,400 divided areas (144 (pixels / mapping image) x 100 (images)). Here, the following procedure was performed to evaluate the degree of cohesion. Each of the 144 divided areas was shifted by one pixel, and the number of white pixels in each divided area was measured after each shift. This process was repeated, ultimately shifting the area by 10 pixels x 10 pixels, and the frequency distribution was calculated from the data for 100 images (data on the number of white pixels in each of the 144 divided areas x 100).

[0053] If the coefficient of variation, obtained by dividing the standard deviation of the frequency distribution by the mean value of the frequency distribution, is taken as the degree of pigment agglomeration, the degree of pigment agglomeration obtained from the histogram in Figure 6(c) is 0.7147, and the degree of pigment agglomeration obtained from the histogram in Figure 7(c) is 0.5921. In other words, the degree of pigment agglomeration is high in the insulating coating of sample A, which is prone to external damage to the insulating coating, and low in the insulating coating of sample B, which is less prone to external damage to the insulating coating. Note that the standard deviation and mean value of the frequency distribution of pigment concentration may also be obtained from the frequency distribution table on which the histogram is based, rather than from the histogram.

[0054] As shown above, the susceptibility of insulating coatings to external damage is not significantly affected by the average value of the frequency distribution of pigment concentration, but is affected by the degree of pigment aggregation. Based on these results, it is predicted that the range of pigment aggregation at which insulating coatings are susceptible to external damage is approximately 0.6 or higher.

[0055] The Raman spectroscopic analyzer used for Raman scattering measurement in the resin material quality inspection method according to the embodiment of the present invention may be connected to an agglomeration evaluation device for performing the evaluation step of evaluating the agglomeration degree of the pigment in the resin material. This agglomeration evaluation device is, for example, a personal computer having stored therein a program for performing the evaluation step (e.g., deriving the agglomeration degree from a mapping image). That is, according to the embodiment of the present invention, it is possible to provide an agglomeration evaluation device that can be connected to a Raman spectroscopic analyzer capable of performing the measurement step in the resin material quality inspection method and that can perform the evaluation step in the resin material quality inspection method.

[0056] Furthermore, according to an embodiment of the present invention, the measurement process using the Raman spectroscopic analyzer and the evaluation process using the agglomeration evaluation device can be performed non-destructively and non-contactly on the insulating coating. Therefore, a resin material extrusion molding system capable of in-line evaluation of the pigment agglomeration level in a resin material can be provided, which includes an extruder that extrudes a resin material, and the above-described Raman spectroscopic analyzer and agglomeration evaluation device that perform an inspection of the extruded resin material using the resin material quality inspection method according to an embodiment of the present invention. For example, by accumulating measurement data using this extrusion molding system, it is possible to more accurately determine the range of pigment agglomeration levels that are likely to cause external damage to the resin material. Furthermore, the resin material extrusion molding system capable of in-line evaluation of pigment agglomeration level can also control extrusion conditions to reduce agglomeration levels, thereby improving the yield of the resin material.

[0057] (Effects of the embodiment) According to the quality inspection method for resin materials according to the embodiment of the present invention, the base polymer is a fluorine-based resin, and the degree of pigment aggregation in a resin material containing a pigment can be quantified, making it possible to predict in advance the likelihood of external damage to the resin material during processing.

[0058] Furthermore, according to the quality inspection method for resin materials according to an embodiment of the present invention, it is possible to non-destructively evaluate the susceptibility of resin materials to external damage, and therefore, for example, it is possible to select resin materials that are less likely to be damaged during processing.

[0059] (Summary of the embodiment) Next, the technical concept grasped from the above-described embodiment will be described.

[0060] [1] A quality inspection method for a resin material, comprising: a measurement step of irradiating a resin material containing a pigment with a laser and performing a mapping measurement of the Raman spectrum; and an evaluation step of evaluating the degree of aggregation of the pigment in the resin material based on the distribution of intensities of first peaks attributable to molecular vibrations or lattice vibrations of the pigment obtained by the mapping measurement, wherein the base polymer of the resin material is a fluorine-based resin.

[0061] [2] The quality inspection method for a resin material according to [1] above, wherein in the evaluation step, the mapping image obtained by the mapping measurement is binarized by setting a threshold value for the intensity value of the first peak contained in each pixel of the mapping image, and the degree of aggregation is evaluated based on the number of pixels of at least one color in each of a plurality of regions of the same area partitioned in the binarized mapping image.

[0062] [3] A quality inspection method for a resin material according to the above [2], wherein a frequency distribution of the number of pixels of at least one color for each of the plurality of regions is calculated, and the coefficient of variation obtained by dividing the standard deviation of the frequency distribution by the mean value of the frequency distribution is evaluated as the degree of aggregation.

[0063] [4] A quality inspection method for a resin material according to any one of [1] to [3] above, wherein the intensity of the first peak is normalized by the intensity of a second peak attributed to molecular vibration of the fluororesin.

[0064] [5] The quality inspection method for a resin material according to the above [4], wherein the fluorine-based resin is a perfluoroalkoxyalkane, and the second peak is a peak attributed to CF2 symmetric stretching.

[0065] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications can be made without departing from the spirit of the invention. Furthermore, the above-described embodiments do not limit the scope of the invention according to the claims. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. [Explanation of symbols]

[0066] 1 cable 10 Conductors 11 Insulators

Claims

1. a measuring step of irradiating a resin material containing a pigment with a laser and measuring the Raman spectrum by mapping; an evaluation step of evaluating the degree of aggregation of the pigment in the resin material based on the distribution of intensities of first peaks attributed to molecular vibrations or lattice vibrations of the pigment obtained by the mapping measurement; Including, The base polymer of the resin material is a fluorine-based resin. Quality inspection method for resin materials.

2. In the evaluation step, a threshold value is set for the intensity value of the first peak included in each pixel of the mapping image obtained by the mapping measurement, and the mapping image is binarized, and the degree of aggregation is evaluated based on the number of pixels of at least one color for each of a plurality of regions of the same area partitioned in the binarized mapping image. The method for inspecting the quality of a resin material according to claim 1.

3. a frequency distribution of the number of pixels of the at least one color for each of the plurality of regions is obtained, and a coefficient of variation obtained by dividing a standard deviation value of the frequency distribution by a mean value of the frequency distribution is evaluated as the degree of aggregation; The method for inspecting the quality of a resin material according to claim 2.

4. The intensity of the first peak is normalized by the intensity of a second peak attributed to molecular vibration of the fluororesin. The method for inspecting the quality of a resin material according to any one of claims 1 to 3.

5. the fluorine-based resin is a perfluoroalkoxyalkane, The second peak is CF ２ This is a peak attributed to symmetric stretching. The method for inspecting the quality of a resin material according to claim 4.

Images