Method for inspecting quality of electric wire

Abstract

Provided is a quality inspection method for an electric wire that enables investigation of the properties of an insulating coating layer having polyethylene or polypropylene as a main component using Raman mapping measurement. A quality inspection method for an electric wire (1) that has an insulating coating layer (11) having polyethylene as a main component, the quality inspection method including a measurement step and an evaluation step; in the measurement step, Raman mapping measurement is performed on the surface of the insulating coating layer (11), and a Raman spectrum group is obtained; in the evaluation step, the retraction deformation rate of the insulating coating layer (11) is evaluated based on the intensity of a first peak attributed to C-H bending vibration of the polyethylene in the Raman spectrum group.

Description

Technical Field

[0001] This invention relates to a method for quality inspection of electrical wires. Background Technology

[0002] Previously, methods for determining the properties of polyethylene by Raman scattering were known (see Non-Patent Document 1 and Non-Patent Document 2). Non-Patent Document 1 discloses a method for determining the crystallinity of polyethylene using the intensity of the peak attributable to the CH bending vibration of polyethylene in the Raman spectrum. Non-Patent Document 2 discloses a method for determining the strain of polyethylene using the position of the peak of the CC symmetric stretching vibration of polyethylene in the Raman spectrum.

[0003] Existing technical documents

[0004] Non-patent literature

[0005] Non-patent document 1: APKotula et al., "The rheo-Raman microscope: Simultaneouschemical, conformational, mechanical, and microstructural measures of softmaterials", REVIEW OF SCIENTIFIC INSTRUMENTS 87 105105 (2016).

[0006] Non-patent document 2: PA Tarantili, AG Andreopoulos and C. Galiotis, "Real-TimeMicro-Raman Measurements on Stressed Polyethylene Fibers. 1.Strain RateEffects and Molecular Stress Redistribution", Macromolecules 1998, 31, 20, 6964-6976. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] Raman scattering measurement allows for non-destructive and non-contact measurement of the object being measured. Therefore, if the desired characteristics of an object can be determined through Raman scattering measurement, these characteristics can be measured without damaging or contaminating the object.

[0009] The purpose of this invention is to provide a method for quality inspection of electrical wires, which can use Raman mapping to investigate the characteristics of insulation coatings mainly composed of polyethylene or polypropylene.

[0010] Methods for solving problems

[0011] To address the aforementioned issues, this invention provides a method for quality inspection of electrical wires. The electrical wires have an insulating coating primarily composed of polyethylene or polypropylene. The method includes a measurement step and an evaluation step. In the measurement step, Raman mapping is performed on the surface of the insulating coating to obtain a Raman spectrum. In the evaluation step, the shrinkage deformation rate of the insulating coating is evaluated based on the intensity of the first peak in the Raman spectrum attributed to the CH bending vibration of polyethylene or the CC stretching vibration of polypropylene.

[0012] In addition, in order to solve the above-mentioned problems, the present invention provides a method for quality inspection of electrical wires, wherein the electrical wires have an insulating coating mainly composed of polyethylene, and the method for quality inspection of electrical wires includes a measurement step and an evaluation step; in the measurement step, Raman mapping measurement is performed at two locations on the surface of the insulating coating to obtain two Raman spectra; in the evaluation step, the fracture resistance of the insulating coating is evaluated based on the difference in position of the third peak of the CC-symmetric stretching vibration of the polyethylene in the two Raman spectra.

[0013] In addition, in order to solve the above-mentioned problems, the present invention provides a method for quality inspection of electrical wires, wherein the electrical wires have an insulating coating mainly composed of polyethylene or polypropylene, and the method for quality inspection of electrical wires includes a measurement step and an evaluation step; in the measurement step, Raman mapping measurement is performed at two locations on the surface of the insulating coating to obtain two Raman spectral groups; in the evaluation step, the fracture resistance of the insulating coating is evaluated based on the intensity difference of the first peaks of the CH bending vibration of the polyethylene or the CC stretching vibration of the polypropylene in the two Raman spectral groups.

[0014] Invention Effects

[0015] According to the present invention, a method for quality inspection of electrical wires can be provided, which can use Raman mapping to investigate the characteristics of an insulation coating mainly composed of polyethylene or polypropylene. Attached Figure Description

[0016] Figure 1 This is a radial cross-sectional view of an insulated wire, which is an example of a wire according to the first embodiment of the present invention.

[0017] Figure 2 middle, Figure 2(a) is an optical microscope image of a portion of the surface of the insulating coating of the first sample. Figure 2 (b) indicates that the surface of the insulating coating is... Figure 2 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0018] Figure 3 middle, Figure 3 (a) is the surface of the insulating coating of the first sample with Figure 2 (a) shows optical microscope images of different parts. Figure 3 (b) indicates that the surface of the insulating coating is... Figure 3 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0019] Figure 4 middle, Figure 4 (a) is an optical microscope image of a portion of the surface of the insulating coating of the second sample. Figure 4 (b) indicates that the surface of the insulating coating is... Figure 4 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0020] Figure 5 middle, Figure 5 (a) is the surface of the insulating coating of the second sample with respect to... Figure 4 (a) shows optical microscope images of different parts. Figure 5 (b) indicates that the surface of the insulating coating is... Figure 5 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0021] Figure 6 middle, Figure 6 (a) is in Figure 2 (a) is a mapping image of the first specimen formed on an optical microscope image. Figure 6 (b) means Figure 6 The crystallinity α contained in each pixel of the mapped image of the first sample shown in (a) c Histogram of frequency distribution.

[0022] Figure 7 middle, Figure 7 (a) is in Figure 3 (a) is a mapping image of the first specimen formed on an optical microscope image. Figure 7 (b) means Figure 7 The crystallinity α contained in each pixel of the mapped image of the first sample shown in (a) c Histogram of frequency distribution.

[0023] Figure 8 middle, Figure 8 (a) is in Figure 4 The mapped image of the second sample formed on the optical microscope image of (a), Figure 8 (b) means Figure 8 The crystallinity α contained in each pixel of the mapped image of the second sample shown in (a) c Histogram of frequency distribution.

[0024] Figure 9 middle, Figure 9 (a) is in Figure 5 The mapped image of the second sample formed on the optical microscope image of (a), Figure 9 (b) means Figure 9 The crystallinity α contained in each pixel of the mapped image of the second sample shown in (a) c Histogram of frequency distribution.

[0025] Figure 10 The graph is obtained by visualizing the values ​​in Table 2.

[0026] Figure 11 It is an optical microscope image of a surface with a cracked insulating coating.

[0027] Figure 12 middle, Figure 12 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating of the third sample. Figure 12 (b) represents the cross-section through the radial direction of the insulating coating. Figure 12 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0028] Figure 13 middle, Figure 13 (a) is a radial cross-section of the insulation coating of the third sample, located on the central axis separated by the insulated wire. Figure 12 An optical microscope image of the portion opposite to the portion shown in (a). Figure 13 (b) represents the cross-section through the radial direction of the insulating coating. Figure 13 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0029] Figure 14 middle, Figure 14 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating of the fourth sample. Figure 14 (b) represents the cross-section through the radial direction of the insulating coating. Figure 14 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0030] Figure 15 middle, Figure 15 (a) is a radial cross-section of the insulation coating of the fourth sample, located on the central axis separated by the insulated wire. Figure 14 An optical microscope image of the portion opposite to the portion shown in (a). Figure 15 (b) represents the cross-section through the radial direction of the insulating coating. Figure 15 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0031] Figure 16 middle, Figure 16 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating of the fifth sample. Figure 16 (b) represents the cross-section through the radial direction of the insulating coating. Figure 16 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0032] Figure 17 middle, Figure 17 (a) is a radial cross-section of the insulation coating of the fifth sample, located on the central axis separated by the insulated wire. Figure 16 An optical microscope image of the portion opposite to the portion shown in (a). Figure 17 (b) represents the cross-section through the radial direction of the insulating coating. Figure 17 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0033] Figure 18 middle, Figure 18 (a) is in Figure 12 The mapped image of the third sample formed on the optical microscope image of (a), Figure 18 (b) means Figure 18 The position (cm) of the third peak P3 contained in each pixel of the mapped image of the third sample shown in (a). -1 Histogram of the frequency distribution of ).

[0034] Figure 19 middle, Figure 19 (a) is in Figure 13 The mapped image of the third sample formed on the optical microscope image of (a), Figure 19 (b) means Figure 19 The position (cm) of the third peak P3 contained in each pixel of the mapped image of the third sample shown in (a). -1 Histogram of the frequency distribution of ).

[0035] Figure 20 middle, Figure 20(a) is in Figure 14 The mapped image of the fourth sample formed on the optical microscope image of (a), Figure 20 (b) means Figure 20 The location (cm) of the third peak P3 contained in each pixel of the mapped image of the fourth sample shown in (a). -1 Histogram of the frequency distribution of ).

[0036] Figure 21 middle, Figure 21 (a) is in Figure 15 The mapped image of the fourth sample formed on the optical microscope image of (a), Figure 21 (b) means Figure 21 The location (cm) of the third peak P3 contained in each pixel of the mapped image of the fourth sample shown in (a). -1 Histogram of the frequency distribution of ).

[0037] Figure 22 middle, Figure 22 (a) is in Figure 16 The mapped image of the fifth sample formed on the optical microscope image of (a), Figure 22 (b) means Figure 22 The location (cm) of the third peak P3 contained in each pixel of the mapped image of the fifth sample shown in (a). -1 Histogram of the frequency distribution of ).

[0038] Figure 23 middle, Figure 23 (a) is in Figure 17 The mapped image of the fifth sample formed on the optical microscope image of (a), Figure 23 (b) means Figure 23 The location (cm) of the third peak P3 contained in each pixel of the mapped image of the fifth sample shown in (a). -1 Histogram of the frequency distribution of ).

[0039] Figure 24 The graph is obtained by visualizing the values ​​in Table 4.

[0040] Figure 25 middle, Figure 25 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating of the third sample. Figure 25 (b) represents the cross-section through the radial direction of the insulating coating. Figure 25 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0041] Figure 26 middle, Figure 26(a) is a radial cross-section of the insulation coating of the third sample, located on the central axis separated by the insulated wire. Figure 25 An optical microscope image of the portion opposite to the portion shown in (a). Figure 26 (b) represents the cross-section through the radial direction of the insulating coating. Figure 26 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0042] Figure 27 middle, Figure 27 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating of the fourth sample. Figure 27 (b) represents the cross-section through the radial direction of the insulating coating. Figure 27 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0043] Figure 28 middle, Figure 28 (a) is a radial cross-section of the insulation coating of the fourth sample, located on the central axis separated by the insulated wire. Figure 27 An optical microscope image of the portion opposite to the portion shown in (a). Figure 28 (b) represents the cross-section through the radial direction of the insulating coating. Figure 28 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0044] Figure 29 middle, Figure 29 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating of the fifth sample. Figure 29 (b) represents the cross-section through the radial direction of the insulating coating. Figure 29 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0045] Figure 30 middle, Figure 30 (a) is a radial cross-section of the insulation coating of the fifth sample, located on the central axis separated by the insulated wire. Figure 29 An optical microscope image of the portion opposite to the portion shown in (a). Figure 30 (b) represents the cross-section through the radial direction of the insulating coating. Figure 30 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a).

[0046] Figure 31 middle, Figure 31 (a) is in Figure 25 The mapped image of the third sample formed on the optical microscope image of (a), Figure 31 (b) means Figure 31 The crystallinity α contained in each pixel of the mapped image of the third sample shown in (a) c Histogram of frequency distribution.

[0047] Figure 32 middle, Figure 32 (a) is in Figure 26 The mapped image of the third sample formed on the optical microscope image of (a), Figure 32 (b) means Figure 32 The crystallinity α contained in each pixel of the mapped image of the third sample shown in (a) c Histogram of frequency distribution.

[0048] Figure 33 middle, Figure 33 (a) is in Figure 27 The mapped image of the fourth sample formed on the optical microscope image of (a), Figure 33 (b) means Figure 33 The crystallinity α contained in each pixel of the mapped image of the fourth sample shown in (a) c Histogram of frequency distribution.

[0049] Figure 34 middle, Figure 34 (a) is in Figure 28 The mapped image of the fourth sample formed on the optical microscope image of (a), Figure 34 (b) means Figure 34 The crystallinity α contained in each pixel of the mapped image of the fourth sample shown in (a) c Histogram of frequency distribution.

[0050] Figure 35 middle, Figure 35 (a) is in Figure 29 The mapped image of the fifth sample formed on the optical microscope image of (a), Figure 35 (b) means Figure 35 The crystallinity α contained in each pixel of the mapped image of the fifth sample shown in (a) c Histogram of frequency distribution.

[0051] Figure 36 middle, Figure 36 (a) is in Figure 30 The mapped image of the fifth sample formed on the optical microscope image of (a), Figure 36 (b) means Figure 36 The crystallinity α contained in each pixel of the mapped image of the fifth sample shown in (a) c Histogram of frequency distribution.

[0052] Figure 37The graph is obtained by visualizing the values ​​in Table 5.

[0053] Explanation of reference numerals in the attached figures

[0054] 1: Wire; 10: Conductor; 11: Insulating coating. Detailed Implementation

[0055] [First Implementation Method]

[0056] (Methods for inspecting the quality of electrical wires)

[0057] According to the first embodiment of the present invention, the method for quality inspection of electrical wires uses Raman scattering measurement to evaluate the shrinkage deformation rate of the insulating coating layer of the electrical wire, which is mainly composed of polyethylene (e.g., comprising more than 50% by mass of the total). Here, the insulating coating layer is the outermost layer of the electrical wire, formed, for example, by extrusion using an extruder.

[0058] The "electric wire" of this invention includes not only an electric wire consisting of a single conductor, or stranded wires, covered by an insulating sheath (hereinafter referred to as an insulated wire), but also a so-called cable consisting of multiple insulated wires covered by a sheath. That is, when the electric wire of this invention is a cable, its sheath is equivalent to the insulating sheath of this invention.

[0059] Shrinkage is a phenomenon caused by residual stress in the insulation coating during wire manufacturing, resulting in the shrinkage of the insulation coating as the temperature rises. The shrinkage deformation rate of the insulation coating refers to the shrinkage rate of the insulation coating along the length of the wire due to shrinkage.

[0060] Raman scattering measurements allow for the non-destructive evaluation of the shrinkage rate of the insulation coating on electrical wires. Furthermore, Raman scattering measurements can be performed non-contactly, thus avoiding contamination of the insulation coating during the measurement process.

[0061] Furthermore, in Raman scattering measurements, the diameter of the laser spot irradiating the surface of the resin material becomes the measurement area, thus enabling measurements within tiny areas with diameters of less than 1 μm. Therefore, it is possible to evaluate the shrinkage deformation rate of the insulation coating in fine-diameter wires (e.g., wires with an outer diameter of less than 200 μm) where measurements need to be performed within tiny areas. It should be noted that, for example, FT-IR can be cited as a non-destructive, non-contact measurement method similar to Raman scattering measurements, but FT-IR is difficult to perform measurements within tiny areas of tens of μm.

[0062] Furthermore, while point measurements are difficult to obtain information on localized deterioration of the insulating coating, Raman mapping measurements (described later) can provide information on the deterioration within the measured range, thus enabling high-precision evaluation of the shrinkage rate of the insulating coating. Additionally, this allows for the precise determination of the difference in shrinkage rate of the insulating coating for each sample.

[0063] The inventors conducted in-depth research and discovered a correlation between the intensity of the peak attributable to the CH bending vibration of polyethylene (referred to as the first peak) in the Raman spectrum obtained by Raman mapping of the insulating coating and the shrinkage deformation rate of the insulating coating (the higher the intensity of the first peak in the Raman spectrum, the greater the shrinkage deformation rate). Based on this correlation, the wire quality inspection method of this embodiment can use the intensity of the first peak in the Raman spectrum obtained by Raman mapping of the insulating coating to evaluate the shrinkage deformation rate of the insulating coating.

[0064] That is, the quality inspection method for electrical wires according to this embodiment is a quality inspection method for electrical wires having an insulation coating mainly composed of polyethylene, including a measurement step and an evaluation step; in the measurement step, Raman mapping measurement is performed on the surface of the insulation coating to obtain a Raman spectrum; in the evaluation step, the shrinkage deformation rate of the insulation coating is evaluated based on the intensity of the first peak of the CH bending vibration attributed to the polyethylene in the Raman spectrum. It should be noted that the position of the first peak in the Raman spectrum (the position where the maximum intensity is obtained) is typically at 1240 cm⁻¹. -1 Above and 1360cm -1 Within the following range. It should be noted that the positions of the peaks in the Raman spectrum can be read from the positions of the apexes of the peaks in the fitted curve obtained by fitting and analyzing the Raman spectrum.

[0065] In the evaluation of the shrinkage deformation rate of the insulation coating in the aforementioned evaluation process, the shrinkage deformation rate of the insulation coating can be determined using the correlation between the intensity of the first peak in the Raman spectrum, which is experimentally determined beforehand, and the shrinkage deformation rate of the insulation coating. This correlation can be obtained, for example, from the results of Raman mapping measurements of the insulation coating of the wire and thermal shock tests on the wire.

[0066] In the aforementioned evaluation process, for example, the shrinkage rate of the insulating coating can be evaluated based on the average value of the frequency distribution of the intensity of the first peak in the Raman spectral set. In this case, the shrinkage rate of the insulating coating can be calculated using the correlation between the average value of the frequency distribution of the intensity of the first peak in the Raman spectral set and the shrinkage rate of the insulating coating, which has been experimentally determined in advance (e.g., a mathematical expression representing the shrinkage rate of the insulating coating as a function of the average value of the frequency distribution of the intensity of the first peak in the Raman spectral set).

[0067] Raman mapping measurement is a measurement method that repeatedly measures while scanning measurement points (laser irradiation points) within a predetermined measurement area on the surface of the object being measured. The mapped image, which is the two-dimensional measurement data obtained by Raman mapping measurement, has data for each pixel related to the intensity of the first peak contained in the Raman spectrum obtained by a single Raman scattering measurement (e.g., the intensity of the first peak, the intensity of the first peak normalized to the intensity of the second peak described later). That is, the Raman spectrum set obtained by Raman mapping measurement is a set of Raman spectra with the same number of pixels as the mapped image.

[0068] It should be noted that, in the method of using Raman spectra obtained by Raman mapping measurement, which is based on multi-point measurement (mapping) using a laser with a small spot diameter, for analysis, the influence of fluorescence in the Raman spectrum can be suppressed compared to the method of using a single Raman spectrum obtained by irradiating the surface of the insulating coating with a laser with a large spot diameter (e.g., the same measurement range as the Raman mapping measurement). This is because, compared to Raman light, the increase in reflection intensity associated with the increase in the irradiated area of ​​the laser is particularly large. As a result, the intensity of Raman peaks in the Raman spectrum relative to the background (fluorescence) increases, allowing for accurate determination of the intensity and position of peaks used for analysis, such as the first peak.

[0069] It is known that the higher the crystallinity of polyethylene, the greater the intensity of the first peak of the CH bending vibration attributable to polyethylene (refer to Non-Patent Literature 1 above). Therefore, the intensity of the first peak in the Raman spectrum obtained by Raman mapping of the insulating coating represents the crystallinity of the insulating coating within the measurement range of the Raman mapping measurement. It is believed that in the insulating coating, a higher intensity of the first peak in the Raman spectrum indicates a greater shrinkage deformation rate because higher crystallinity makes it easier to shrink when heated.

[0070] To suppress the influence of measurement conditions, the intensity of the first peak is preferably normalized to the intensity of the peak attributable to the CH torsion vibration of polyethylene (referred to as the second peak), which is almost unaffected by the crystallinity of polyethylene. The position of the second peak in the Raman spectrum (the position where the maximum intensity is obtained) is typically at 1375 cm⁻¹. -1 Above and 1455cm-1 Within the following range.

[0071] In the aforementioned evaluation process, for example, the crystallinity α is determined based on the intensity of the first peak in the Raman spectral set. c The average value of the frequency distribution (called the average crystallinity) can be used to evaluate the shrinkage deformation rate of the insulating coating. Crystallinity α c It is a physical property value that is proportional to the intensity of the first peak, which is normalized to the intensity of the second peak in the Raman spectrum of the insulating coating, and is represented by Equation 1 below.

[0072] [Number 1]

[0073]

[0074] Equation 1 I b It is the intensity of the first peak of the CH bending vibration attributed to polyethylene, I t This is the intensity of the second peak attributable to the CH torsional vibration of polyethylene. Additionally, N in Equation 1... c It is a scaling factor. For example, in high-density polyethylene (HDPE), N... c Take a value of 0.80±0.03.

[0075] The intensity of the first and second peaks can be obtained using either the peak height or the integrated intensity of the peak. The integrated intensity of the peak can be calculated, for example, using the Covell method.

[0076] (The composition of electrical wires)

[0077] Figure 1 This is a radial cross-sectional view of an insulated wire 1, which is an example of a wire according to the first embodiment of the present invention. The insulated wire 1 includes a conductor 10 and an insulating coating 11 covering the periphery of the conductor 10.

[0078] The conductor 10 is a stranded wire made of multiple wires 101, such as copper wire and copper alloy wire, twisted together. The insulating coating layer 11 is a layer with polyethylene as the main component, consisting of an inner layer 111 covering the conductor 10 and an outer layer 112 covering the inner layer 111.

[0079] (An example of a quality inspection method for electrical wires)

[0080] The following describes an embodiment of the wire quality inspection method of this embodiment. In this embodiment, firstly, two insulated wires 1 with different shrinkage deformation rates are used to determine the average crystallinity based on Raman mapping and the shrinkage deformation rate based on thermal shock testing, indicating that there is a correlation between the average crystallinity of the insulation coating and the shrinkage deformation rate.

[0081] Here, the insulated wire 1 with the lower shrinkage deformation rate of the two insulated wires 1 in this embodiment is referred to as the first sample, and the insulated wire 1 with the higher shrinkage deformation rate is referred to as the second sample. The outer diameter of both the first and second samples is approximately 1.4 mm, and the polyethylene concentration of the insulating coating layer 11 is approximately 99% by mass of the whole.

[0082] In this embodiment, the integrated intensities of the first peak P1 and the second peak P2 are respectively set as the intensity I of the first peak P1. b The intensity of the second peak P2 I t Additionally, in this embodiment, it is necessary to use polyethylene composed of the same type (i.e., N in Formula 1). c The average crystallinity of the insulating coating layer 11 of the first sample (with equal values) and the insulating coating layer 11 of the second sample were compared. Therefore, for convenience, N was... c Treat it as 1.

[0083] The measurement conditions for Raman mapping of insulating coating 11 are shown in Table 1 below. It should be noted that the theoretical value of the laser irradiation diameter, calculated based on the Abbe definition using the excitation wavelength (532.06 nm) and numerical aperture (NA 0.80) of the objective lens in Table 1, is 0.41 μm.

[0084] [Table 1]

[0085]

[0086] Figure 2 (a) is an optical microscope image of a portion of the surface of the insulating coating 11 of the first sample. Figure 2 (b) indicates that by means of the surface of the insulating coating 11 Figure 2 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 2 The two Raman spectra shown in (b) are in Figure 2 The measurements were taken at locations A1 and A2, indicated by a cross in (a).

[0087] Figure 3 (a) is the surface of the insulating coating 11 of the first sample, and Figure 2 (a) shows optical microscope images of different parts. Figure 3 (b) indicates that by means of the surface of the insulating coating 11 Figure 3 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 3 The two Raman spectra shown in (b) are in Figure 3 The measurements were taken at locations B1 and B2, indicated by a cross in (a).

[0088] Figure 4 (a) is an optical microscope image of a portion of the surface of the insulating coating 11 of the second sample. Figure 4 (b) indicates that by means of the surface of the insulating coating 11 Figure 4 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 4 The two Raman spectra shown in (b) are in Figure 4 The measurements were taken at the locations C1 and C2, indicated by the cross in (a).

[0089] Figure 5 (a) is the surface of the insulating coating 11 of the second sample, and Figure 4 (a) shows optical microscope images of different parts. Figure 5 (b) indicates that by means of the surface of the insulating coating 11 Figure 5 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 5 The two Raman spectra shown in (b) are in Figure 5 The measurements were taken at the locations D1 and D2, indicated by the cross in (a).

[0090] Figure 2 (b) Figure 3 (b) Figure 4 (b) Figure 5 The Raman spectrum shown in (b) contains a first peak P1 attributable to the CH bending vibration of polyethylene and a second peak P2 attributable to the CH torsional vibration of polyethylene.

[0091] Measurement positions A1, B1, C1, and D1 are examples of locations where the intensity of the first peak P1 on the surface of the insulating coating layer 11 of the first or second sample is relatively high (high crystallinity of polyethylene). On the other hand, measurement positions A2, B2, C2, and D2 are examples of locations where the intensity of the first peak P1 on the surface of the insulating coating layer 11 of the first or second sample is relatively low (low crystallinity of polyethylene).

[0092] Figure 6 of (a) Figure 7 (a) are respectively in Figure 2 of (a) Figure 3 The first sample is mapped onto the optical microscope image of (a). Figure 8 of (a) Figure 9 (a) are respectively in Figure 4 of (a) Figure 5 The mapping image of the second sample formed on the optical microscope image of (a).

[0093] exist Figure 6 of (a) Figure 7 of (a) Figure 8 of (a) Figure 9 Each pixel of the mapped image in (a) contains the crystallinity α obtained from the Raman spectrum measured at its location. c (Intensity I of the first peak P1) b / Intensity of the second peak P2 I t The data shows that each pixel has a crystallinity α. c The corresponding color.

[0094] Figure 6 (b) Figure 7 (b) respectively represent Figure 6 of (a) Figure 7 The crystallinity α contained in each pixel of the mapped image of the first sample shown in (a) c Histogram of frequency distribution. Figure 8 (b) Figure 9 (b) respectively represent Figure 8 of (a) Figure 9 The crystallinity α contained in each pixel of the mapped image of the second sample shown in (a) c Histogram of frequency distribution.

[0095] exist Figure 6 (b) Figure 7 (b) Figure 8 (b) Figure 9 In the histogram shown in (b), the crystallinity α is used to represent... c The range from the minimum to the maximum value is divided into 256 levels as the horizontal axis, and the number of pixels in each level, i.e., the frequency, is the vertical axis.

[0096] according to Figure 6 (b) Figure 7 The average crystallinity of the insulating coating 11 in the first sample, calculated from the histogram shown in (b), is 0.1000 and 0.1110, respectively. Additionally, from... Figure 8 (b) Figure 9 The average crystallinity of the insulating coating layer 11 in the second sample, calculated from the histogram shown in (b), is 0.1286 and 0.1207, respectively. It should be noted that the average crystallinity can also be obtained from the frequency distribution table, which serves as the basis for the histogram, rather than from the histogram.

[0097] Next, an example of a thermal shock test used to determine the shrinkage deformation rate will be described. First, the conductor 10 is pulled out from the first and second specimens, which are insulated wires 1, and the remaining insulation layer 11 is cut with a length L of 100 mm to serve as a test piece for the thermal shock test. That is, the length L of the test piece before the test is 100 mm. Five of these test pieces are cut from the insulation layer 11 of the first and second specimens respectively.

[0098] Next, these test pieces were moved from room temperature to an environment of 150°C, kept there for 15 minutes, and then returned to room temperature to conduct a simple thermal shock test. Then, the length L of the test piece after the test was measured, and the shrinkage deformation rate of the test piece was calculated as (L before the test - L after the test) / (L before the test).

[0099] The average shrinkage deformation rate of the five test pieces cut from the insulating coating layer 11 of the first sample was taken as the average shrinkage deformation rate of the insulating coating layer 11 of the first sample, and the average shrinkage deformation rate of the five test pieces cut from the insulating coating layer 11 of the second sample was taken as the average shrinkage deformation rate of the insulating coating layer 11 of the second sample. The obtained average shrinkage deformation rates of the insulating coating layer 11 of the first sample and the insulating coating layer 11 of the second sample were 5.8% and 7.5%, respectively.

[0100] Table 2 below shows the average crystallinity of the insulating coating 11 in the first and second samples obtained by the above Raman mapping and the average shrinkage deformation rate of the insulating coating 11 in the first and second samples obtained by the above thermal shock test.

[0101] [Table 2]

[0102]

[0103] Figure 10 The graph is obtained by visualizing the values ​​in Table 2. Figure 10 The bar chart represents the average crystallinity value, and the line chart represents the average shrinkage deformation rate value. Table 2 and Figure 10 The study shows a correlation between the average crystallinity and the average shrinkage deformation rate in the insulating coating layer 11 of the insulated wire 1.

[0104] If we obtain the information shown in Table 2 in advance, and Figure 10 The correlation between the intensity (e.g., average crystallinity) of the first peak in the Raman spectrum of the insulation coating of the insulated wire and the shrinkage deformation rate shows that the shrinkage deformation rate of the insulation coating can be evaluated based on the intensity of the first peak in the Raman spectrum obtained by Raman mapping.

[0105] (Effects of the first implementation method)

[0106] According to the wire quality inspection method of the first embodiment, the shrinkage deformation rate of the insulation coating can be evaluated based on the intensity of the first peak in the Raman spectrum obtained by Raman mapping through the surface of the insulation coating. Therefore, the shrinkage deformation rate of the insulation coating, which is mainly composed of polyethylene, can be measured without causing damage or contamination.

[0107] [Second Implementation]

[0108] The second embodiment of the present invention differs in the content of the quality inspection method for the wire and the wire characteristics evaluated. Points identical to those in the first embodiment are omitted or simplified in their description.

[0109] (Methods for inspecting the quality of electrical wires)

[0110] According to the second embodiment of the present invention, the method for quality inspection of wires can use Raman scattering measurement to evaluate the fracture resistance of the insulation coating, which is mainly composed of polyethylene, of the wire.

[0111] The inventors conducted in-depth research and discovered a correlation between the position difference of the peak (referred to as the third peak) of the CC-symmetric stretching vibration of polyethylene in two Raman spectral groups obtained from two locations (e.g., two locations on the surface and two locations on the cross-section) of the insulating coating and the fracture resistance of the insulating coating (the greater the difference in the position of the third peak in the two Raman spectral groups, the lower the fracture resistance of the insulating coating). Based on this correlation, the wire quality inspection method of this embodiment can evaluate the fracture resistance of the insulating coating by using the position of the third peak in the two spectral groups obtained by Raman mapping of the insulating coating.

[0112] The quality inspection method for electrical wires according to this embodiment is a method for inspecting the quality of electrical wires with an insulation coating mainly composed of polyethylene, including a measurement step and an evaluation step. In the measurement step, Raman mapping measurements are performed at two locations on the surface of the insulation coating to obtain two Raman spectral sets. In the evaluation step, the fracture resistance of the insulation coating is evaluated based on the difference in position between the third peaks of the C-S symmetric stretching vibrations of the polyethylene in the two Raman spectral sets. It should be noted that the position of the third peak in the Raman spectrum (the position where the maximum intensity is obtained) is typically at 1115 cm⁻¹. -1 Above and 1150cm -1 Within the following range.

[0113] In the evaluation of the fracture resistance of the insulation coating in the aforementioned evaluation process, the fracture resistance of the insulation coating can be evaluated using the correlation between the position difference of the third peak of two Raman spectral groups, determined experimentally in advance, and the presence or absence of surface cracks in the insulation coating, which is an indicator of the fracture resistance of the insulation coating (e.g., a threshold for the position difference of the third peak of two Raman spectral groups that can effectively suppress the generation of cracks in the insulation coating under specific operating conditions). This correlation can be obtained, for example, from the results of Raman mapping measurements performed on wires with cracks on the surface of the insulation coating and wires without cracks on the surface of the insulation coating.

[0114] In the aforementioned evaluation process, for example, the fracture resistance of the insulating coating can be evaluated based on the difference in the average values ​​of the frequency distributions of the positions of the third peaks in the two Raman spectral groups. In this case, the fracture resistance of the insulating coating can be evaluated using the correlation between the average values ​​of the frequency distributions of the positions of the third peaks in the two Raman spectral groups, which are experimentally determined in advance, and the fracture resistance of the insulating coating.

[0115] The difference in the position of the third peak of two Raman spectral groups obtained by Raman mapping at two locations on the surface of the insulating coating is correlated with the difference in strain at those two locations (see Non-Patent Document 2 above). For example, if the difference in the position (cm) of the third peak of two Raman spectral groups obtained by Raman mapping at two locations on the surface of the insulating coating is... -1 Let ΔP be the difference (%) between the two parts, and let ΔS be the difference between the two parts. Then the relationship shown in Equation 2 holds true.

[0116] [Number 2]

[0117]

[0118] It is believed that the greater the difference in position of the third peak of the two Raman spectral groups in the insulating coating, the lower the fracture resistance of the insulating coating. This is because, when ΔS is large, that is, when the uniformity of strain in the insulating coating is low, the insulating coating is prone to fracture.

[0119] It should be noted that in the above-described measurement process, Raman mapping measurements can also be performed at three or more locations on the surface of the insulating coating to obtain three or more Raman spectral sets. In this case, in the above-described evaluation process, for example, the position difference of the third peak in two of the three or more Raman spectral sets can be calculated several times, and the fracture resistance of the insulating coating can be evaluated based on their average value.

[0120] Figure 11 It is an optical microscope image of the surface of the cracked insulating coating 11 (the surface of the outer layer 112). Figure 11The surface cracks of the insulating coating illustrated are caused by the displacement between atoms and molecules due to the application of external forces, as well as the cutting of molecules and the reduction of intermolecular forces due to the penetration of adhering solvents, etc. It is believed that they are more likely to occur when the uniformity of strain and stress in the insulating coating is low.

[0121] (An example of a quality inspection method for electrical wires)

[0122] The following describes an embodiment of the wire quality inspection method of this embodiment. In this embodiment, firstly, using one insulated wire 1 with cracks on the surface of the insulation coating 11 and two insulated wires 1 without cracks on the surface of the insulation coating 11, the position of the third peak of the insulation coating 11 is determined based on Raman mapping. It is shown that the difference in the average value of the frequency distribution of the position of the third peak of the insulation coating 11 is related to the fracture resistance.

[0123] Here, the insulated wire 1 with cracks on the surface of the insulating coating layer 11 among the three insulated wires 1 in this embodiment is referred to as the third sample, and the two insulated wires 1 without cracks on the surface of the insulating coating layer 11 are referred to as the fourth sample and the fifth sample. The outer diameter of the third sample, the fourth sample and the fifth sample is approximately 2.2 mm, and the polyethylene concentration of the insulating coating layer 11 is approximately 99% by mass of the whole.

[0124] Table 3 below shows the measurement conditions for Raman mapping of the insulating coating 11 in this embodiment. It should be noted that the theoretical value of the laser irradiation diameter, calculated based on the Abbe definition using the excitation wavelength (532.06 nm) and numerical aperture (NA 0.80) of the objective lens in Table 3, is 0.41 μm.

[0125] [Table 3]

[0126]

[0127] Figure 12 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating 11 of the third sample. Figure 12 (b) represents the radial cross-section of the insulating coating 11. Figure 12 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 12 The two Raman spectra shown in (b) are in Figure 12 The measurements were taken at locations E1 and E2, indicated by a cross in (a).

[0128] Figure 13(a) is a radial cross-section of the insulating coating 11 of the third sample, located on the central axis separated by the insulated wire 1. Figure 12 An optical microscope image of the portion opposite to the portion shown in (a). Figure 13 (b) represents the radial cross-section of the insulating coating 11. Figure 13 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 13 The two Raman spectra shown in (b) are in Figure 13 The measurements were taken at the locations F1 and F2, indicated by the cross in (a).

[0129] Figure 14 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating 11 of the fourth sample. Figure 14 (b) represents the radial cross-section of the insulating coating 11. Figure 14 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 14 The two Raman spectra shown in (b) are in Figure 14 The measurements were taken at the locations G1 and G2, indicated by the cross in (a).

[0130] Figure 15 (a) is a radial cross-section of the insulating coating 11 of the fourth sample, located on the central axis separated by the insulated wire 1. Figure 14 An optical microscope image of the portion opposite to the portion shown in (a). Figure 15 (b) represents the radial cross-section of the insulating coating 11. Figure 15 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 15 The two Raman spectra shown in (b) are in Figure 15 The measurements were taken at the locations H1 and H2, indicated by the cross in (a).

[0131] Figure 16 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating 11 of the fifth sample. Figure 16 (b) represents the radial cross-section of the insulating coating 11. Figure 16 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 16 The two Raman spectra shown in (b) are in Figure 16 The measurements were taken at the locations I1 and I2, indicated by the cross in (a).

[0132] Figure 17(a) is a radial cross-section of the insulating coating 11 of the fifth sample, located on the central axis separated by the insulated wire 1. Figure 16 An optical microscope image of the portion opposite to the portion shown in (a). Figure 17 (b) represents the radial cross-section of the insulating coating 11. Figure 17 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 17 The two Raman spectra shown in (b) are in Figure 17 The measurements were taken at the locations J1 and J2, indicated by the cross in (a).

[0133] Figure 12 (b) Figure 13 (b) Figure 14 (b) Figure 15 (b) Figure 16 (b) Figure 17 The Raman spectrum shown in (b) contains a third peak P3 attributable to the CC symmetric stretching vibration of polyethylene.

[0134] Figure 18 of (a) Figure 19 (a) are respectively in Figure 12 of (a) Figure 13 The mapping image of the third sample formed on the optical microscope image of (a). Figure 20 of (a) Figure 21 (a) are respectively in Figure 14 of (a) Figure 15 The mapped image of the fourth sample formed on the optical microscope image of (a). Figure 22 of (a) Figure 23 (a) are respectively in Figure 16 of (a) Figure 17 The mapping image of the fifth sample formed on the optical microscope image of (a).

[0135] exist Figure 18 of (a) Figure 19 of (a) Figure 20 of (a) Figure 21 of (a) Figure 22 of (a) Figure 23 Each pixel of the mapped image (a) contains the position (cm) of the third peak P3 obtained from the Raman spectrum measured at its location. -1 The data shows that each pixel has a color corresponding to the position of the third peak P3.

[0136] Figure 18 (b) Figure 19 (b) respectively represent Figure 18 of (a) Figure 19 The position (cm) of the third peak P3 contained in each pixel of the mapped image of the third sample shown in (a). -1 Histogram of the frequency distribution of ). Figure 20 (b) Figure 21 (b) respectively represent Figure 20 of (a) Figure 21 The location (cm) of the third peak P3 contained in each pixel of the mapped image of the fourth sample shown in (a). -1 Histogram of the frequency distribution of ). Figure 22 (b) Figure 23 (b) respectively represent Figure 22 of (a) Figure 23 The location (cm) of the third peak P3 contained in each pixel of the mapped image of the fifth sample shown in (a). -1 Histogram of the frequency distribution of ).

[0137] exist Figure 18 (b) Figure 19 (b) Figure 20 (b) Figure 21 (b) Figure 22 (b) Figure 23 In the histogram shown in (b), the range from the minimum to the maximum value of the third peak P3 is divided into 256 levels as the horizontal axis, and the number of pixels in each level, i.e., the frequency, is set as the vertical axis.

[0138] Depend on Figure 18 (b) Figure 19 The average frequency distribution of the position of the third peak P3 of the insulating coating 11 of the third sample, calculated from the histogram shown in (b), is 1133.9 cm. -1 1133.1cm -1 In addition, by Figure 20 (b) Figure 21 The average P3 position of the insulating coating 11 in the fourth sample, calculated from the histogram shown in (b), is 1133.8 cm. -1 1133.3cm -1 In addition, by Figure 22 (b) Figure 23 The average P3 position of the insulating coating 11 in the fifth sample, calculated from the histogram shown in (b), is 1133.1 cm. -1 1133.3cm -1 It should be noted that the average position of P3 can also be determined not from the histogram, but from the frequency distribution table that forms the basis of the histogram.

[0139] Table 4 below shows the average P3 position of the insulating coating 11 in the third, fourth and fifth samples obtained by the Raman mapping measurement described above, the difference between the two average P3 positions of each sample, and the difference in strain at two locations of the insulating coating 11 calculated using Equation 2 described above.

[0140] [Table 4]

[0141]

[0142] Figure 24 This is a graph created by visualizing the values ​​in Table 4. Table 4 and Figure 24 The diagram illustrates the correlation between the difference in the average position of P3 at two different locations within the insulation coating 11 of the insulated wire 1 and the presence or absence of surface cracks caused by fracture resistance. It should be noted that in the above embodiment, Raman mapping measurements were performed on the radial cross-section of the insulation coating 11; however, the same results are obtained when Raman mapping measurements are performed on the surface of the insulation coating 11. If the Raman mapping measurement is performed on the surface of the insulation coating 11, it can be carried out non-destructively and non-contactly.

[0143] If we obtain the information shown in Table 4 in advance, Figure 24 The correlation between the position difference of the third peak of two Raman spectral groups in the insulation coating of the insulated wire (e.g., the average position difference of P3 of the two Raman spectral groups, i.e., the average position difference of P3 of the two locations) and the presence or absence of surface cracks allows for the evaluation of the fracture resistance of the insulation coating based on the position difference of the third peak of the two Raman spectral groups obtained by Raman mapping of the two locations.

[0144] (Effects of the second implementation method)

[0145] According to the wire quality inspection method of the second embodiment, the fracture resistance of the insulation coating can be evaluated based on the difference in the positions of the third peaks of two Raman spectral groups obtained by Raman mapping measurements of the surfaces of the insulation coating at two locations. Therefore, the fracture resistance of insulation coatings with polyethylene as the main component can be evaluated without causing damage or contamination.

[0146] [Third Implementation Method]

[0147] The third embodiment of the present invention differs in the content of the quality inspection method for the wire and the wire characteristics evaluated. Points identical to those in the first embodiment are omitted or simplified in their description.

[0148] (Methods for inspecting the quality of electrical wires)

[0149] According to the third embodiment of the present invention, the method for quality inspection of wires can use Raman scattering measurement to evaluate the fracture resistance of the insulation coating of the wire, which is mainly composed of polyethylene.

[0150] The inventors conducted in-depth research and discovered a correlation between the intensity difference of the first peak of the CH bending vibration of polyethylene in two Raman spectral groups obtained from two locations (e.g., two locations on the surface and two locations on the cross-section) of the insulating coating and the fracture resistance of the insulating coating (the greater the intensity difference of the first peak in the two Raman spectral groups, the lower the fracture resistance of the insulating coating). Based on this correlation, the wire quality inspection method of this embodiment can evaluate the fracture resistance of the insulating coating using the intensity of the first peak in the two spectral groups obtained by Raman spectral measurement of the insulating coating.

[0151] The quality inspection method for electrical wires according to this embodiment is a method for inspecting the quality of electrical wires having an insulation coating mainly composed of polyethylene, including a measurement step and an evaluation step. In the measurement step, Raman mapping measurement is performed at two locations on the surface of the insulation coating to obtain two Raman spectral sets. In the evaluation step, the fracture resistance of the insulation coating is evaluated based on the difference in intensity (e.g., the difference in average crystallinity) of the first peak of the CH bending vibration belonging to the polyethylene in the two Raman spectral sets. Furthermore, the first peak in this embodiment is the same as the first peak in the first embodiment.

[0152] In the evaluation of the fracture resistance of the insulation coating in the aforementioned evaluation process, the fracture resistance of the insulation coating can be evaluated using the correlation between the intensity difference of the first peak of two Raman spectral groups (e.g., the difference in average crystallinity of the two Raman spectral groups, i.e., the difference in average crystallinity of the two locations) and the presence or absence of surface cracks in the insulation coating, which is an indicator of the fracture resistance of the insulation coating (e.g., a threshold for the intensity difference of the first peak of two Raman spectral groups that can effectively suppress the generation of cracks in the insulation coating under specific operating conditions). This correlation can be obtained, for example, from the results of Raman mapping measurements performed on wires with cracks on the surface of the insulation coating and wires without cracks on the surface of the insulation coating.

[0153] In the aforementioned evaluation process, for example, the fracture resistance of the insulating coating can be evaluated based on the difference in the average values ​​of the frequency distributions of the intensities of the first peaks of the two Raman spectral groups. In this case, the fracture resistance of the insulating coating can be evaluated using the correlation between the average values ​​of the frequency distributions of the intensities of the first peaks of the two Raman spectral groups, which are experimentally determined in advance, and the fracture resistance of the insulating coating.

[0154] As described in the first embodiment above, the intensity of the first peak in the Raman spectrum obtained by mapping measurement represents the crystallinity of the insulating coating within the measurement range of the Raman mapping measurement. It is believed that the greater the difference in intensity of the first peak of the two Raman spectrum sets in the insulating coating, the lower the fracture resistance of the insulating coating. This is because when the uniformity of crystallinity in the insulating coating is low, the insulating coating is prone to fracture.

[0155] To suppress the influence of measurement conditions, the intensity of the first peak is preferably normalized to the intensity of the second peak, which is attributed to the CH torsion vibration of polyethylene and is almost unaffected by the crystallinity of polyethylene. This second peak is the same as the second peak in the first embodiment.

[0156] In the aforementioned evaluation process, for example, the crystallinity α is determined based on the intensity of the first peak in the Raman spectral set. c The average value of the frequency distribution (average crystallinity) can be used to evaluate the fracture resistance of the insulating coating.

[0157] It should be noted that in the above-described measurement process, Raman mapping measurements can also be performed at three or more locations on the surface of the insulating coating to obtain three or more Raman spectral groups. In this case, in the above-described evaluation process, for example, the intensity difference of the first peak in two of the three or more Raman spectral groups can be calculated several times, and the fracture resistance of the insulating coating can be evaluated based on their average value.

[0158] (An example of a quality inspection method for electrical wires)

[0159] The following describes an embodiment of the wire quality inspection method. In this embodiment, firstly, using a third sample of an insulated wire 1 with cracks on the surface of the insulation coating 11, and a fourth and fifth sample of an insulated wire 1 without cracks on the surface of the insulation coating 11, the average crystallinity based on Raman mapping is measured, showing a correlation between the average crystallinity of the insulation coating and its fracture resistance. These third, fourth, and fifth samples in this embodiment are the same as those in the second embodiment described above.

[0160] In this embodiment, the integrated intensities of the first peak P1 and the second peak P2 are respectively set as the intensity I of the first peak P1. b The intensity of the second peak P2 I t Additionally, in this embodiment, it is necessary to use polyethylene composed of the same type (i.e., N in Formula 1). c The average crystallinity of the insulating coatings 11 of the third, fourth, and fifth samples (which have the same value) is compared. Therefore, for convenience, N is...c Treat it as 1.

[0161] The Raman mapping measurement conditions for the insulating coating layer 11 in this embodiment are the same as those used in the Raman mapping measurement in the embodiment of the second embodiment described above.

[0162] Figure 25 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating 11 of the third sample. Figure 25 (b) represents the radial cross-section of the insulating coating 11. Figure 25 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 25 The two Raman spectra shown in (b) are in Figure 25 The measurements were taken at the locations K1 and K2, indicated by the cross in (a).

[0163] Figure 26 (a) is a radial cross-section of the insulating coating 11 of the third sample, located on the central axis separated by the insulated wire 1. Figure 25 An optical microscope image of the portion opposite to the portion shown in (a). Figure 26 (b) represents the radial cross-section of the insulating coating 11. Figure 26 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 26 The two Raman spectra shown in (b) are in Figure 26 The measurements were taken at the locations L1 and L2, indicated by the cross in (a).

[0164] Figure 27 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating 11 of the fourth sample. Figure 27 (b) represents the radial cross-section of the insulating coating 11. Figure 27 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 27 The two Raman spectra shown in (b) are in Figure 27 The measurements were taken at the locations M1 and M2, indicated by the cross in (a).

[0165] Figure 28 (a) is a radial cross-section of the insulating coating 11 of the fourth sample, located on the central axis separated by the insulated wire 1. Figure 27 An optical microscope image of the portion opposite to the portion shown in (a). Figure 28 (b) represents the radial cross-section of the insulating coating 11. Figure 28 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 28 The two Raman spectra shown in (b) are in Figure 28 The measurements were taken at the locations N1 and N2, indicated by the cross in (a).

[0166] Figure 29 (a) is an optical microscope image of a portion of the radial cross-section of the insulating coating 11 of the fifth sample. Figure 29 (b) represents the radial cross-section of the insulating coating 11. Figure 29 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 29 The two Raman spectra shown in (b) are in Figure 29 The measurements were taken at the locations O1 and O2, indicated by the cross in (a).

[0167] Figure 30 (a) is a radial cross-section of the insulating coating 11 of the fifth sample, located on the central axis separated by the insulated wire 1. Figure 29 An optical microscope image of the portion opposite to the portion shown in (a). Figure 30 (b) represents the radial cross-section of the insulating coating 11. Figure 30 An example of Raman spectra obtained by Raman scattering measurement of the portion shown in (a). Figure 30 The two Raman spectra shown in (b) are in Figure 30 The measurements were taken at the locations P1 and P2, indicated by the cross in (a).

[0168] exist Figure 25 (b) Figure 26 (b) Figure 27 (b) Figure 28 (b) Figure 29 (b) Figure 30 The Raman spectrum shown in (b) contains a first peak P1 attributable to the CH bending vibration of polyethylene and a second peak P2 attributable to the CH torsional vibration of polyethylene.

[0169] The measurement positions K1, L1, M1, N1, O1, and P1 are examples of locations where the intensity of the first peak P1 in the radial cross-section of the insulating coating layer 11 of the third, fourth, or fifth sample is relatively high (indicating higher crystallinity of polyethylene). On the other hand, the measurement positions K2, L2, M2, N2, O2, and P2 are examples of locations where the intensity of the first peak P1 in the radial cross-section of the insulating coating layer 11 of the third, fourth, or fifth sample is relatively low (indicating lower crystallinity of polyethylene).

[0170] Figure 31 of (a) Figure 32 (a) are respectively in Figure 25 of (a) Figure 26 The mapping image of the third sample formed on the optical microscope image of (a). Figure 33 of (a) Figure 34 (a) are respectively in Figure 27 of (a) Figure 28 The mapped image of the fourth sample formed on the optical microscope image of (a). Figure 35 of (a) Figure 36 (a) are respectively in Figure 29 of (a) Figure 30 The mapping image of the fifth sample formed on the optical microscope image of (a).

[0171] exist Figure 31 of (a) Figure 32 of (a) Figure 33 of (a) Figure 34 of (a) Figure 35 of (a) Figure 36 Each pixel of the mapped image in (a) contains the crystallinity α obtained from the Raman spectrum measured at its location. c (Intensity I of the first peak P1) b / Intensity of the second peak P2 I t The data shows that each pixel has a crystallinity α. c The corresponding color.

[0172] Figure 31 (b) Figure 32 (b) respectively represent Figure 31 of (a) Figure 32 Histogram of the frequency distribution of crystallinity αc contained in each pixel of the mapped image of the third sample shown in (a). Figure 33 (b) Figure 34 (b) respectively represent Figure 33 of (a) Figure 34 The crystallinity α contained in each pixel of the mapped image of the fourth sample shown in (a) c Histogram of frequency distribution. Figure 35 (b) Figure 36 (b) respectively represent Figure 35 of (a) Figure 36 The crystallinity α contained in each pixel of the mapped image of the fifth sample shown in (a) c Histogram of frequency distribution.

[0173] exist Figure 31 (b) Figure 32 (b) Figure 33 (b) Figure 34 (b) Figure 35 (b) Figure 36 In the histogram shown in (b), the crystallinity α c The range from the minimum to the maximum value is divided into 256 levels as the horizontal axis, and the number of pixels in each level, i.e., the frequency, is used as the vertical axis.

[0174] according to Figure 31 (b) Figure 32 The average crystallinity of the insulating coating 11 in the third sample, calculated from the histogram shown in (b), is 0.357 and 0.138, respectively. Additionally, from... Figure 33 (b) Figure 34 The average crystallinity of the insulating coating 11 in the fourth sample, calculated from the histogram shown in (b), is 0.054 and 0.126, respectively. Additionally, from... Figure 35 (b) Figure 36 The average crystallinity of the insulating coating 11 in the fifth sample, calculated from the histogram shown in (b), is 0.127 and 0.224, respectively. It should be noted that the average crystallinity can also be obtained from the histogram, which is based on the frequency distribution table.

[0175] Table 5 below shows the average crystallinity of the insulating coating 11 in the third, fourth and fifth samples obtained by the above Raman mapping determination.

[0176] [Table 5]

[0177]

[0178] Figure 37 This is a graph created by visualizing the values ​​in Table 5. Table 5 and Figure 37 The diagram illustrates the correlation between the difference in average crystallinity between two different locations in the insulating coating 11 of the insulated wire 1 and the presence or absence of surface cracks caused by fracture resistance. It should be noted that in the above embodiment, Raman mapping measurements were performed on the radial cross-section of the insulating coating 11; however, the same results are obtained when Raman mapping measurements are performed on the surface of the insulating coating 11. If the Raman mapping measurement is performed on the surface of the insulating coating 11, it can be carried out non-destructively and non-contactly.

[0179] If we obtain the information shown in Table 5 in advance, Figure 37 The correlation between the intensity difference of the first peak of the two Raman spectral groups in the insulation coating of the insulated wire (e.g., the difference in the average crystallinity of the two Raman spectral groups, i.e., the difference in the average crystallinity of the two locations) and the presence or absence of surface cracks allows for the evaluation of the fracture resistance of the insulation coating based on the intensity difference of the first peak of the two Raman spectral groups obtained by Raman mapping measurements at the two locations.

[0180] (Effects of the third implementation method)

[0181] According to the wire quality inspection method of the third embodiment, the fracture resistance of the insulation coating can be evaluated based on the intensity difference of the first peaks of two Raman spectral groups obtained by Raman mapping measurements of the surfaces of the insulation coating at two locations. Therefore, the fracture resistance of insulation coatings mainly composed of polyethylene can be evaluated without causing damage or contamination.

[0182] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention without departing from its spirit. For example, the wire quality inspection method of the first and third embodiments described above is applicable to the quality inspection of wires having an insulation coating with polypropylene as the main component, and can evaluate the shrinkage deformation rate and fracture resistance of the insulation coating. In this case, in the evaluation process, instead of the peak of the CH bending vibration belonging to polyethylene, the peak of the CC stretching vibration belonging to polypropylene is used as the first peak. The peak of the CC stretching vibration belonging to polypropylene is located at 808 cm⁻¹ in the Raman spectrum of the insulation coating. -1 Nearby peaks. Additionally, as a second peak used to normalize the first peak, the peak attributable to the CH plane rocking vibration of polypropylene can be used instead of the peak attributable to the CH torsional vibration of polyethylene. The peak attributable to the CH plane rocking vibration of polypropylene is located at 840 cm⁻¹ in the Raman spectrum of the insulating coating. -1 Nearby peaks. Other specific methods and effects are the same as those described in the first and third embodiments above.

[0183] Furthermore, for example, in the Raman spectroscopic analysis apparatus used for Raman mapping measurement in the wire quality inspection methods of the first to third embodiments described above, an evaluation device for performing evaluation steps to evaluate the shrinkage rate or fracture resistance of the insulation coating may also be connected. This evaluation device is, for example, a personal computer that stores the program for performing the evaluation steps (e.g., deriving the shrinkage rate or fracture resistance from the mapping image) in its memory. That is, according to this embodiment, an evaluation apparatus capable of performing the evaluation steps in the wire quality inspection method can be provided, and this evaluation apparatus can be connected to a Raman spectroscopic analysis apparatus capable of performing the measurement steps in the wire quality inspection method.

[0184] Furthermore, according to the first to third embodiments described above, the measurement process using a Raman spectrophotometer and the evaluation process using the aforementioned evaluation device can be performed on the insulation coating of a wire in a non-destructive and non-contact manner. Therefore, it is possible to provide an extrusion molding system for an insulation coating capable of online evaluation of its shrinkage deformation rate or fracture resistance, comprising an extruder that extrudes insulating material to form an insulation coating around a conductor or the like, and the aforementioned Raman spectrophotometer and evaluation device for inspecting the formed insulation coating using the wire quality inspection method of this embodiment.

[0185] Furthermore, the embodiments described above do not limit the invention covered by the claims. It should also be noted that the combinations of features described in the embodiments are not necessarily all necessary means to solve the problems of the invention.

[0186] (Summary of implementation methods)

[0187] Next, the technical ideas learned from the embodiments described above will be described by reference to the accompanying reference numerals and the like. However, the reference numerals and the like in the following description do not limit the constituent elements in the claims to the components specifically shown in the embodiments.

[0188] [1] A quality inspection method for an electric wire (1) is a quality inspection method for an electric wire (1) having an insulating coating (11) with polyethylene or polypropylene as the main component, including a measurement step and an evaluation step; in the measurement step, Raman mapping measurement is performed on the surface of the insulating coating (11) to obtain a Raman spectrum set; in the evaluation step, the shrinkage deformation rate of the insulating coating (11) is evaluated based on the intensity of the first peak of the first peak of the Raman spectrum set attributable to the CH bending vibration of the polyethylene or the CC stretching vibration of the polypropylene.

[0189] [2] According to the quality inspection method of the wire (1) described above [1], in the evaluation process, the shrinkage deformation rate of the insulation coating (11) is evaluated based on the average value of the frequency distribution of the intensity of the first peak in the Raman spectrum group.

[0190] [3] According to the quality inspection method of the wire (1) described in [1] or [2] above, the intensity of the first peak is standardized by the intensity of the second peak belonging to the CH torsional vibration of the polyethylene or the CH planar rocking vibration of the polypropylene.

[0191] [4] A quality inspection method for an electrical wire (1) is a quality inspection method for an electrical wire (1) having an insulating coating (11) with polyethylene as the main component, including a measurement step and an evaluation step; in the measurement step, Raman mapping measurement is performed at two locations on the surface of the insulating coating (11) to obtain two Raman spectral groups; in the evaluation step, the fracture resistance of the insulating coating (11) is evaluated based on the difference in position of the third peak of the CC symmetric stretching vibration of the polyethylene in the two Raman spectral groups.

[0192] [5] According to the quality inspection method of the wire (1) described above [4], in the above evaluation process, the fracture resistance of the above insulation coating (11) is evaluated based on the difference of the average value of the frequency distribution of the position of the third peak of the above two Raman spectral groups.

[0193] [6] A method for quality inspection of an electrical wire (1) is a method for quality inspection of an electrical wire (1) having an insulating coating (11) with polyethylene or polypropylene as the main component, including a measurement step and an evaluation step; in the measurement step, Raman mapping measurement is performed at two locations on the surface of the insulating coating (11) to obtain two Raman spectral groups; in the evaluation step, the fracture resistance of the insulating coating (11) is evaluated based on the difference in intensity of the first peak of the CH bending vibration of the polyethylene or the CC stretching vibration of the polypropylene in the two Raman spectral groups.

[0194] [7] According to the quality inspection method of the wire (1) described above [6], in the above evaluation process, the fracture resistance of the above insulation coating (11) is evaluated based on the difference in the average value of the frequency distribution of the intensity of the first peak of the above two Raman spectral groups.

[0195] [8] According to the quality inspection method of the wire (1) described in [6] or [7] above, the intensity of the first peak is standardized by the intensity of the second peak belonging to the CH torsional vibration of the polyethylene or the CH planar rocking vibration of the polypropylene.

Claims

1. A method for quality inspection of electrical wires, wherein the wires have an insulation coating primarily composed of polyethylene or polypropylene. The quality inspection methods for the wires include: The measurement process involves performing Raman mapping measurements on the surface of the insulating coating to obtain a Raman spectrum. The evaluation process assesses the shrinkage rate of the insulating coating based on the intensity of the first peak in the Raman spectral set attributed to the CH bending vibration of the polyethylene or the CC stretching vibration of the polypropylene.

2. The method for quality inspection of electrical wires according to claim 1, wherein, In the evaluation process, the shrinkage deformation rate of the insulating coating is evaluated based on the average value of the frequency distribution of the intensity of the first peak in the Raman spectrum.

3. The method for quality inspection of electrical wires according to claim 1 or 2, wherein, The intensity of the first peak is normalized using the intensity of the second peak, which is attributed to the CH torsional vibration of the polyethylene or the CH planar rocking vibration of the polypropylene.

4. A method for quality inspection of electrical wires, wherein the electrical wire has an insulation coating mainly composed of polyethylene. The quality inspection methods for the wires include: In the measurement process, Raman mapping measurements are performed at two locations on the surface of the insulating coating to obtain two sets of Raman spectra. The evaluation process assesses the fracture resistance of the insulating coating based on the difference in position of the third peak of the CC-symmetric stretching vibrations of the polyethylene in the two Raman spectral groups.

5. The method for quality inspection of electrical wires according to claim 4, wherein, In the evaluation process, the fracture resistance of the insulating coating is evaluated based on the difference in the average value of the frequency distribution of the position of the third peak in the two Raman spectral groups.

6. A method for quality inspection of electrical wires, wherein the electrical wires have an insulation coating mainly composed of polyethylene or polypropylene. The quality inspection methods for the wires include: In the measurement process, Raman mapping measurements are performed at two locations on the surface of the insulating coating to obtain two sets of Raman spectra. The evaluation process assesses the fracture resistance of the insulating coating based on the intensity difference of the first peaks attributable to the CH bending vibration of the polyethylene or the CC stretching vibration of the polypropylene in the two Raman spectral groups.

7. The method for quality inspection of electrical wires according to claim 6, wherein, In the evaluation process, the fracture resistance of the insulating coating is evaluated based on the difference in the average value of the frequency distribution of the intensity of the first peak of the two Raman spectral groups.

8. The method for quality inspection of electrical wires according to claim 6 or 7, wherein, The intensity of the first peak is normalized using the intensity of the second peak, which is attributed to the CH torsional vibration of the polyethylene or the CH planar rocking vibration of the polypropylene.

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