Insulated electrical wire and wiring harness

Abstract

Insulated electrical wire, comprising: an electrical wire conductor; and an insulating coating that coats an outer circumferential surface of the electrical wire conductor, wherein the insulating coating is made from a resin composition containing a thermoplastic polyester elastomer as the main component, including the polymer components that make up the resin composition, the thermoplastic polyester elastomer content is 80% by mass or more, where the melting point of the thermoplastic polyester elastomer is 200°C or less, and where a tensile energy upon fracture of the resin composition, obtained by measuring only the insulating coating, obtained by removing the electrical wire conductor from the insulated electrical wire, 200 mJ / mm² 3 or more.

Description

Technical field

[0001] The present invention relates to an insulated electrical wire and a wiring harness, and in particular relates to an insulated electrical wire which can preferably be used for electrical connection in motor vehicles and the like, and a wiring harness with such an insulated electrical wire. Technical background

[0002] Insulated electrical wires often require a high degree of flexibility to ensure proper routing. In particular, insulated electrical wires used for electrical connections in automobiles are increasingly being installed in confined spaces or along complex routes due to the recent increase in functionality and performance of vehicles, thus increasing the demands on flexibility.

[0003] One way to increase the flexibility of an insulated electrical wire is to reduce the thickness of the insulating coating. Reducing the thickness of the insulating coating decreases the diameter of the insulated electrical wire, thus saving space. However, reducing the thickness of the insulating coating makes it difficult to ensure its wear resistance. When using an insulated electrical wire in harsh environments, such as in an automobile where it is frequently subjected to vibration or comes into contact with other elements, it is particularly important that the insulating coating exhibits high wear resistance.

[0004] Another way to increase the flexibility of an insulated electrical wire is to use a highly flexible resin composition that forms an insulating coating. However, when the component compositions of many resin materials are adjusted to increase flexibility, sufficient wear resistance is often not guaranteed.

[0005] Many insulating coating materials for automotive electrical wires typically contain polyvinyl chloride (PVC) as the main component, but PVC is not a material with high wear resistance. For example, patent document 1 attempted to achieve both wear resistance and flexibility in an insulating coating by adding a predetermined amount of plasticizer to PVC as a method for improving the wear resistance of a resin composition containing PVC as the main component. However, it is difficult to significantly improve the wear resistance of an insulating coating by adjusting the plasticizer content.

[0006] Furthermore, patent document 2 attempted to improve wear resistance and similar properties by adding a polyester elastomer or a methyl methacrylate butadiene styrene resin to an electrical wire coating material made of plasticized PVC. However, the effect of improving wear resistance achieved by adding these resin components to a PVC resin is limited, and even if wear resistance can be improved, it is difficult to ensure sufficient flexibility of an insulating coating and to achieve both flexibility and wear resistance.

[0007] Patent document 3 further discloses a resin composition for a conductor sheathing material, an insulated conductor, and a cable harness. The resin composition comprises (A) a polysulfone-based resin; (B) an aromatic polyester resin; (C) a polyester elastomer; and (D) a compound with a reactive functional group that reacts with a carboxyl group and a hydroxyl group, wherein component (D) reacts with component (B) and component (C) to form a bond. List of citations for patent documents Patent document 1: JP 2014 - 043 508 A Patent document 2: JP H06 - 223 630 A Patent document 3: DE 11 2014 002 917 T5 Brief description of the invention: Technical problem

[0008] As described above, a thickness-reducing process is used to increase the flexibility of an insulated electrical wire by reducing the thickness of an insulating coating. While this method is effective in reducing the diameter of the insulated electrical wire, ensuring adequate wear resistance becomes challenging. Therefore, to achieve sufficient wear resistance even with reduced coating thickness, a high wear resistance property of the resin composition forming the insulating coating is essential.

[0009] It is an object of the present invention to provide an insulated electrical wire with an insulating coating made of a resin composition with high wear resistance and a cable harness with such an insulated electrical wire. Solution to the problem

[0010] To solve the problem described above, the present invention relates to an insulated electrical wire comprising: an electrical wire conductor; and an insulating coating that coats an outer circumferential surface of the electrical wire conductor, wherein the insulating coating is made of a resin composition containing a thermoplastic polyester elastomer as the main component, wherein the content of the thermoplastic polyester elastomer among the polymer components forming the resin composition is 80% by mass or more, wherein the melting point of the thermoplastic polyester elastomer is 200°C or less, and wherein the tensile energy upon rupture of the resin composition, obtained by measuring only the insulating coating, obtained by removing the electrical wire conductor from the insulated electrical wire, is 200 mJ / mm². 3 or more.

[0011] It is preferred that the insulating coating thickness is less than 0.7 mm. Furthermore, it is preferred that the tensile energy upon fracture of the resin composition be 400 mJ / mm. 3 or more. It is preferred that the hardness of the thermoplastic polyester elastomer is 60 or less, as defined by the Shore D hardness. It is preferred that the cross-sectional area of ​​the electrical wire conductor is 3 mm². 2 or more and 20 mm 2 or less.

[0012] The present invention is further directed to a cable harness comprising this type of insulated electrical wire. Advantageous effects of the invention

[0013] In the insulated electrical wire according to the present invention, the insulating coating consists of a resin composition containing a thermoplastic polyester elastomer as the main component, wherein the thermoplastic polyester elastomer content among the polymer components forming the resin composition is 80% by mass or more, and the thermoplastic polyester elastomer has a melting point of 200°C or less. Accordingly, the insulating coating exhibits high wear resistance as a material property. Therefore, even if the thickness of an insulating coating is reduced to improve the flexibility of an insulated electrical wire and to reduce its diameter, it is easy to ensure sufficient wear resistance of the insulating coating.A thermoplastic polyester elastomer is a material that excels in terms of flexibility, which also helps to maintain both the wear resistance and flexibility of an insulating coating.

[0014] When the insulating coating thickness is less than 0.7 mm, the insulated electrical wire exhibits high flexibility due to the thinness of the coating. Furthermore, it is easy to reduce the diameter of the insulated electrical wire. Even with this reduction in the insulating coating thickness, sufficient wear resistance and flexibility can be easily achieved, thanks to the thermoplastic polyester elastomer, the main component in the resin composition that forms the insulating coating.

[0015] Since the magnitude of the tensile energy at fracture is a good indicator of the wear resistance of the resin composition, a tensile energy at fracture of 200 mJ / mm² indicates a resin composition 3 or rather, it suggests that the insulating coating likely has high wear resistance.

[0016] If the hardness of the thermoplastic polyester elastomer is 60 or less than the Shore D hardness, it is particularly easy to improve the wear resistance of the insulating coating. Furthermore, it is also easy to improve the flexibility of the insulating coating.

[0017] Since the melting point of the thermoplastic polyester elastomer in the insulated electrical wire according to the present invention is 200°C or less, it is likely that the thermoplastic polyester elastomer has a particularly high wear resistance.

[0018] If the cross-sectional area of ​​the electrical wire conductor is 3 mm² 2 or more and 20 mm 2 or less, if the thickness of the insulating coating is reduced using a high wear resistance resin composition, the reduction in thickness leads both to an increase in the effect of reducing the diameter of an insulated electrical wire and to an increase in the effect of improving flexibility.

[0019] The cable harness according to the present invention incorporates this type of insulated electrical wire, thus making it easy to ensure the wear resistance of the insulating coating even with a reduced thickness of the insulating coating on the insulated electrical wire. If the flexibility of the insulated electrical wire is improved and the diameter is reduced by decreasing the thickness of the insulating coating, the flexibility of the entire cable harness can be improved and space saved. Brief description of the drawings Fig. Figure 1 shows an insulated electrical wire according to an embodiment of the present invention, wherein Fig. 1(a) a perspective view of it is and Fig. 1(b) is a circumferential cross-sectional view. Fig.Figure 2 shows an example of an SS curve when measuring the tensile energy at fracture, obtained by measuring sample B3. Fig. Figure 3 is a diagram that illustrates the relationship between the tensile energy at breakage and the result of the wear resistance assessment of examples. Description of the embodiment

[0020] An insulated electrical wire and a cable harness according to an embodiment of the present invention are described in detail below with reference to the drawings. Outline of the insulated electrical wire

[0021] First, the outline of an insulated electrical wire according to one embodiment of the present invention is described. It should be noted that the physical properties of materials in this description refer to values ​​measured in air at room temperature, unless otherwise specified.

[0022] Fig.Figure 1 shows the outline of an insulated electrical wire according to one embodiment of the present invention. As shown in Fig. As shown in Figure 1, an insulated electrical wire 10 comprises an electrical conductor 12 and an insulating coating 14 that coats the outer circumferential surface of the conductor 12. The insulated electrical wire 10 can be obtained by extrusion to coat the outer circumferential surface of the conductor 12 with a resin composition to form the insulating coating 14.

[0023] As described in detail later, the insulating coating 14 consists of a resin composition containing a thermoplastic polyester elastomer as its main component, wherein the thermoplastic polyester elastomer content among the polymer components forming the resin composition is 80% by mass or more, and the thermoplastic polyester elastomer has a melting point of 200°C or less. The insulating coating 14 exhibits high wear resistance due to its composition. Because the insulating coating 14 is made of a resin composition with high wear resistance, its wear resistance can be maintained even if the thickness of the insulating coating 14 is reduced to improve the flexibility of an insulated electrical wire 10 and, for example, to reduce its diameter.

[0024] The thickness of the insulating coating 14 is preferably less than 0.7 mm. Accordingly, it is easy to improve the flexibility and reduce the diameter of the insulated electrical wire 10. The thickness of the insulating coating 14 is preferably 0.5 mm or less. However, from the perspective of simplifying the assurance of mechanical properties, such as the wear resistance of the insulating coating 14, the thickness of the insulating coating 14 is preferably 0.3 mm or more. If the thickness of the insulating coating 14 is uneven, it is sufficient that the average thickness lies within the range described above.

[0025] The electrical wire conductor 12 is typically made of copper, but can also be made of other metallic materials besides copper, such as aluminum or magnesium. These metallic materials can be alloys. Examples of other metallic materials used to make alloys are iron, nickel, magnesium, silicon, and combinations thereof.

[0026] Of these materials, aluminum and an aluminum alloy have a lower electrical conductivity than copper and a copper alloy, from which the electrical wire conductor is typically made. Therefore, if aluminum or an aluminum alloy is used for the electrical wire conductor 12, the outer diameter of the electrical wire conductor 12 will likely increase to ensure the required conductivity. Thus, reducing the diameter of the entire insulated electrical wire 10 by reducing the thickness of the insulating coating 14 using a material with high wear resistance is of particular importance.

[0027] The electrical wire conductor 12 can consist of a solid wire or a twisted wire formed by twisting together a plurality of element wires 12a. From the perspective of ensuring the flexibility of the insulated electrical wire 10, the electrical wire conductor 12 preferably consists of a twisted wire. If, in this case, the outer diameter of each element wire 12a forming a twisted wire is 0.45 mm or less, it is particularly easy to ensure the flexibility of the twisted wire as a whole.

[0028] There is no particular limitation regarding the cross-sectional area of ​​the electrical wire conductor 12, but it is preferably 3 mm². 2 or more. If the conductor cross-sectional area is less than 3 mm² 2If the thickness of the insulating coating 14 is reduced, the diameter of the entire insulated electrical wire 10 cannot be effectively reduced. On the other hand, if the conductor cross-sectional area is 3 mm² 2 or more, the diameter can be effectively reduced by reducing the thickness of the insulating coating 14. An insulated electrical wire where the conductor cross-sectional area of ​​the electrical wire conductor 12 is 3 mm² 2A wire with a diameter greater than or greater is generally referred to as thick electrical wire, and when an insulating coating is formed using a conventionally available PVC resin, the thickness of the insulating coating is typically 0.8 mm or more to ensure wear resistance. However, if, as described above, the thickness of the insulating coating 14 is reduced to less than 0.7 mm using a resin composition with high wear resistance, the diameter of a thick insulated electrical wire with such a conventionally available PVC resin coating can be reliably reduced. Preferably, the conductor cross-sectional area of ​​the electrical wire conductor 12 is 8 mm². 2 or more.

[0029] Meanwhile, the conductor cross-sectional area of ​​the electrical wire conductor is 12, preferably 20 mm². 2 or less. If the conductor cross-sectional area is more than 20 mm² 2If the cross-sectional area of ​​the conductor is 20 mm², the flexibility of the electrical wire conductor 12 is too low, and even if the flexibility of the insulating coating 14 is increased by reducing its thickness, it is difficult to ensure sufficient flexibility of the insulated electrical wire 10 as a whole. 2 If the cross-sectional area of ​​the electrical wire 12 is 12 or less, it is possible to effectively improve the flexibility of the insulated electrical wire 10 by reducing the thickness of the insulating coating 14. Preferably, the conductor cross-sectional area of ​​the electrical wire 12 is 16 mm². 2or less. Any combination can be selected as the thickness of the insulating coating 14 and the cross-sectional area of ​​the electrical wire 12, and the more the thickness of the insulating coating 14 is reduced and the more the cross-sectional area of ​​the electrical wire 12 is reduced, the more the flexibility of the insulated electrical wire 10 can be increased. However, considering that both the small thickness of the insulating coating 14 and the small cross-sectional area can effectively contribute to improving the flexibility of the insulated electrical wire 10 as a whole, the thickness of the insulating coating 14 is preferably 0.4 mm or less when the cross-sectional area is 8 mm². 2 or less, such as 3 mm 2 If the conductor cross-sectional area is more than 8 mm² 2 , like 20 mm 2, however, the thickness of the insulating coating 14 is preferably less than 0.7 mm.

[0030] There are no particular limitations on the applications of the insulated electrical wire 10 according to this embodiment, but it can be used as various electrical wires for automobiles, appliances, data communication, electrical power, watercraft, aircraft, and the like. Its use as an electrical wire for automobiles is particularly preferred. For an automotive electrical wire, a certain degree of freedom in routing is necessary, both from the perspective of space saving and the like, and a high degree of flexibility is required. Likewise, a reduction in the diameter of the electrical wire is necessary from the perspective of space saving. In particular, a high degree of flexibility is required for an electrical wire with a large conductor cross-sectional area.Furthermore, it is likely that an electrical wire for automobiles will come into contact with a vehicle body or other component during assembly and will experience friction with a vehicle body or other component during use, thus requiring excellent wear resistance. In the insulated electrical wire 10 according to this embodiment, the insulating coating 14 consists of a resin composition with high wear resistance. Therefore, it is possible to achieve both flexibility and wear resistance by reducing the thickness of the insulating coating 14 while maintaining sufficient wear resistance and by reducing the diameter of the insulated electrical wire 10.

[0031] The insulated electrical wire 10 according to this embodiment can be used either in the form of a solid wire or a wiring harness with a plurality of such insulated electrical wires. All insulated electrical wires forming a wiring harness can be the insulated electrical wires 10 according to this embodiment, or only a portion of them can be the insulated electrical wires 10 according to this embodiment. In the insulated electrical wire 10 according to this embodiment, the insulated electrical wire 10 is made flexible and its diameter is reduced by decreasing the thickness of the insulating coating 14 while maintaining wear resistance, which contributes to improved flexibility of a wiring harness, including the insulated electrical wire 10 as a whole, and to space savings. Resin composition that forms the insulating coating.

[0032] Next, the resin composition that forms the insulating coating 14 of the insulated electrical wire 10 will be described in more detail.

[0033] As described above, the resin composition forming the insulating coating 14 contains a thermoplastic polyester elastomer as its main component. "Contains a thermoplastic polyester elastomer as its main component" means a state in which the thermoplastic polyester elastomer is the largest component among the polymer components forming the resin composition. According to the present invention, the amount of thermoplastic polyester elastomer contained in the polymer components is 80% by weight or more. It is particularly preferred that the polymer components consist solely of the thermoplastic polyester elastomer.

[0034] The thermoplastic polyester elastomer has a hard segment and a soft segment in its molecular structure, with the hard segment consisting of a single polyester unit. There are no particular restrictions regarding the type of soft segment; examples include polyether-based and polyester-based structures. The thermoplastic polyester elastomers included in the resin composition can be used individually or in combination with two or more.

[0035] The thermoplastic polyester elastomer is a material with excellent wear resistance. Since the resin composition forming the insulating coating 14 contains a thermoplastic polyester elastomer as its main component, the resin composition exhibits high wear resistance as a material property. Therefore, as described above, even if the thickness of the insulating coating 14 is reduced to improve the flexibility of the insulated electrical wire 10 and reduce its diameter, high wear resistance of the insulating coating 14 can be ensured.Furthermore, the thermoplastic polyester elastomer is excellent not only in terms of wear resistance but also in terms of flexibility, and thus the effect of the material properties together with the effect of reducing the thickness of the insulating coating 14 contributes to an improvement in the flexibility of the insulated electrical wire 10.

[0036] Furthermore, the hardness of the thermoplastic polyester elastomer is preferably 60 or less, as defined by the Shore D hardness. When the thermoplastic polyester elastomer has such a hardness, the insulating coating 14 exhibits particularly good wear resistance. The reason for this appears to be that, with a Shore D hardness of only 60 or less, the material properties of the thermoplastic polyester elastomer contribute significantly to the abrasion of the insulating coating 14. Since the hardness of the thermoplastic polyester elastomer is kept low, it is also easy to improve the flexibility as a material property of the resin composition. Preferably, the hardness of the thermoplastic polyester elastomer is 40 or less, as defined by the Shore D hardness.Not only the thermoplastic polyester elastomer alone, but also the resin composition that forms the insulating coating 14 as a whole, has a hardness of preferably 60 or less and more preferably 40 or less, as defined by the Shore D hardness.

[0037] Furthermore, from the perspective of high wear resistance according to the present invention, the melting point of the thermoplastic polyester elastomer is 200°C or less. The reason for this appears to be that the lower the melting point, the weaker the interaction between the molecules and the greater the energy that is absorbed. Preferably, the melting point is 190°C or less.

[0038] The resin composition forming the insulating coating 14 may optionally contain components other than the thermoplastic polyester elastomer, provided that the wear resistance of the thermoplastic polyester elastomer is not significantly impaired. Examples of components other than the thermoplastic polyester elastomer include other polymer components and additives.

[0039] There are no particular restrictions on other polymer components that may be included in the resin composition, but examples of polymer components expected to improve wear resistance are the following. In all cases, the content is preferably 5 parts by weight or less per 100 parts by weight of the thermoplastic polyester elastomer. - Other thermoplastic elastomers: in particular styrene-based thermoplastic elastomers, such as maleic acid-modified styrene-ethylene-butylene-styrene block copolymer (SEBS) and amine-modified SEBS. - Oxazoline-modified polystyrene (PS)

[0040] Furthermore, there are no specific restrictions on additives that may be included in the resin composition, and additives typically found in resin compositions for coating electrical wires, such as antioxidants and flame retardants, may be included if desired. Examples of additives intended to improve wear resistance are the following. - Compound containing carbodiimide groups (preferably in an amount of 5 parts by mass or less, based on 100 parts by mass of the thermoplastic polyester elastomer) - Inorganic fillers, such as calcium carbonate, talc, clay and silica

[0041] It should be noted that a plasticizer can be added to the resin composition. However, if a plasticizer is added, the wear resistance of the thermoplastic polyester elastomer is likely to be significantly reduced, although its flexibility is partially improved. Therefore, from the point of view of maintaining wear resistance, it is preferable not to add a plasticizer.

[0042] The resin composition forming the insulating coating 14 exhibits a tensile energy at break of 200 mJ / mm 3 or more. As described later, the tensile energy at fracture of the resin composition is a good indicator for assessing wear resistance, and thus a tensile energy at fracture of the resin composition of 200 mJ / mm 3or moreover, high wear resistance is ensured even with reduced thickness of the insulating coating 14. The tensile energy upon fracture of the resin composition is therefore 200 mJ / mm. 3 or more, preferably 400 mJ / mm 3 or more and preferably 500 mJ / mm 3 or more. Furthermore, not only the resin composition as a whole, but also the thermoplastic polyester elastomer contained as the main component in the resin composition alone exhibits a tensile energy at break of 200 mJ / mm. 3 or more, preferably 400 mJ / mm 3 or more and preferably 500 mJ / mm 3 or more. Assessment of wear resistance based on tensile strength at fracture

[0043] The tensile energy upon fracture of the resin composition has a high correlation with the wear resistance, and a resin composition with high tensile energy upon fracture can be considered to have high wear resistance.

[0044] The tensile energy at fracture is directly the amount of energy applied to a material when it is subjected to stress until it breaks. The tensile energy at fracture of a resin composition can be evaluated, for example, by tensile tests according to JIS K 7161. A sample of the resin composition is held at two points along its length by chucks, and a tensile load is applied to the sample between the chucks. At this point, the ratio between the load per unit area (stress, unit: MPa) and the elongation (strain, unit: dimensionless) until fracture of the sample is recorded. Subsequently, as described in Fig.Figure 2 shows an example: a stress-strain curve (SS curve) is plotted, taking the load per unit area as the vertical axis and the elongation as the horizontal axis. The area under the SS curve is then calculated until the specimen fractures (the area of ​​the region defined by the SS curve, the horizontal axis, and a vertical line passing through the fracture point). The resulting value is then used as the tensile energy at fracture of the resin material (unit: mJ / mm²). 3 ) assumed.

[0045] The specimen used for the tensile tests can be obtained, for example, by removing the electrical wire conductor 12 from the insulated electrical wire 10, which has a length of approximately 100 mm. Furthermore, the test conditions can be, for example, as follows: the distance between the chucks is 20 mm and the tensile speed is 200 mm / min. The tensile energy at break, described above as a value for the resin composition containing the thermoplastic polyester elastomer as the main component, is 200 mJ / mm. 3 or more can also be measured under these conditions.

[0046] The tensile energy at fracture directly indicates a material's strength against stress and is generally not used as an indicator of wear resistance. However, as shown in the following examples, there is a positive correlation between the tensile energy at fracture and wear resistance, and the tensile energy at fracture can be used as an indicator of wear resistance. The reason for this appears to be that the tensile energy at fracture correlates with the energy consumed in scraping the resin material off the surface of the insulated electrical wire 10.

[0047] Wear resistance can also be directly assessed through abrasion tests, which apply the degree of abrasion under stimulation, such as friction, to an actual sample. However, instead of or in addition to abrasion tests, the tensile energy at fracture can be measured through tensile tests and used as an indicator of wear resistance, thus allowing for a simpler and more accurate evaluation and estimation of the resin material's wear resistance. It should be noted that the elongation at break (tensile strain at fracture), the applied load (tensile strength at fracture), and the tensile modulus (a slope on an increasing section of the SS curve), parameters obtained through tensile tests, do not correlate with wear resistance in the same way as the tensile energy at fracture. Therefore, it is difficult to use these parameters as indicators for assessing wear resistance.

[0048] There is no restriction on the resin composition, provided it meets the requirements as described above, and it is possible to find a resin composition with high wear resistance that can be used as an insulating coating 14 of the insulated electrical wire 10 by using a correlation between tensile energy at break and wear resistance. That is, if an attempt is made to obtain the insulating coating 14 from a material with high wear resistance, for example, to reduce the thickness of the insulating coating 14 of the insulated electrical wire 10, it is sufficient to set a threshold value for the tensile energy at break at which the required wear resistance is achieved and to use a resin composition with a tensile energy at break that is greater than or equal to the threshold value.As shown in the following examples, a relationship between tensile energy at fracture and wear resistance can be approximated by a single correlation function (a straight or curved line) beyond the type of resin composition (the type of polymer material included as the main component), and thus the use of a resin composition with tensile energy at fracture greater than or equal to a predetermined threshold makes it possible to obtain an insulating coating 14 with the desired high wear resistance, regardless of the details of the component composition of the resin composition.

[0049] A specific threshold value of the tensile energy at breakage can be selected according to the required degree of wear resistance. For example, it is intended that the thickness of the insulating coating 14, while maintaining the overall wear resistance of the insulating coating 14, must be reduced similarly to an insulating coating made of a conventionally available PVC resin in order to improve the flexibility of the insulated electrical wire 10 and reduce its diameter.The wear resistance of the entire insulating coating 14 increases with increasing thickness of the insulating coating 14, and thus, to realize an insulating coating 14 with a lower thickness than that of a conventional insulating coating, together with a wear resistance similar to that of the conventional insulating coating, it is sufficient to set the tensile energy at breakage to a higher wear resistance as a material property (a property of a material itself that is irrelevant to the thickness) than that of the conventional insulating coating. Examples

[0050] Examples of the present invention are described below. It should be noted that the present invention is not limited to these examples. Test A: Properties of the insulating coating with thermoplastic polyester elastomer as the main component. Test procedure (1) Preparation of the sample

[0051] Twisted aluminum wire conductors with a conductor cross-sectional area of ​​3 mm² each were used. 2 (Element wire diameter 0.32 mm, number of element wires 37) and a conductor cross-sectional area of ​​20 mm² 2 (Element wire diameter 0.32 mm, number of element wires 19 / 13). Resin compositions from components shown in Tables 1 and 2 were extruded to a predetermined thickness around each of the outer circumferential surfaces of the twisted wire conductors to produce insulated electrical wires.

[0052] The materials used in the examples and comparison examples are as follows. In the examples, the thermoplastic polyester elastomers were used as in the resin compositions, while in the comparison examples, the components were mixed by kneading to obtain the resin compositions according to Table 2. Table 2 shows the component contents in parts by mass. Thermoplastic polyester elastomer - TPEE1 (Shore D hardness 27; melting point 160°C): “Hytrel 3046”, manufactured by Du Pont-Toray Co., Ltd. - TPEE2 (Shore D hardness 47; melting point 200°C): “Hytrel 4777”, manufactured by Du Pont-Toray Co., Ltd. - TPEE3 (Shore D hardness 53; melting point 208°C): “Hytrel 5577”, manufactured by Du Pont-Toray Co., Ltd. - TPEE4 (Shore D hardness 72; melting point 219°C): “Hytrel 7277”, manufactured by Du Pont-Toray Co., Ltd.

[0053] Other materials - Polyvinyl chloride (PVC): “ZEST1300Z” (polymerization level 1300), manufactured by Shindai-Ichi Vinyl Corporation. - Plasticizer: “Monocizer W-700” (trimellitic acid ester), manufactured by DIC - Non-lead heat stabilizer: “RUO-110” (Ca-Zn-based), manufactured by ADEKA Corporation - Extender: “Super 1700” (calcium carbonate), manufactured by Maruo Calcium Co., Ltd. (2) Assessment of tensile strength at fracture

[0054] Each of the insulated electrical wires, as described in the examples and comparison examples, was cut to a length of 100 mm, and one electrical wire conductor was removed, leaving only the insulating coating. This insulating coating was used as a sample, and its tensile energy at break was estimated through tensile tests. Specifically, the sample was clamped at two points along its longitudinal axis using chucks and subjected to a tensile test at a distance of 20 mm between the chucks and a tensile speed of 200 mm / min. A tensile energy curve was then recorded, and the area below the curve, up to the point of breakage, was used to calculate the tensile energy at break.The tensile energy during breakage is susceptible to errors due to factors such as variations in the manufacturing conditions of insulated electrical wires, and it has been confirmed that similar samples manufactured separately can have errors of around 20%. (3) Assessment of wear resistance

[0055] Wear resistance was assessed using strip abrasion tests according to ISO 6722. This involved pressing a strip of abrasive paper against each of the outer circumferential surfaces of the insulated electrical wires, as shown in the examples and comparison examples, with a load of 1500 g. The distance the strip moved until the electrical wire conductor was exposed was then measured. A greater movement distance indicates higher wear resistance. The samples had a conductor cross-sectional area of ​​3 mm². 2The samples were rated such that a movement distance of 600 mm or more indicates excellent wear resistance “A”, a movement distance of 200 mm or more and less than 600 mm indicates good wear resistance “B”, and a movement distance of less than 200 mm indicates unsatisfactory wear resistance “C”. Furthermore, the samples with a conductor cross-sectional area of ​​20 mm² were also tested. 2 such that a movement distance of 2000 mm or more indicates excellent wear resistance “A”, a movement distance of 1000 mm or more and less than 2000 mm indicates good wear resistance “B”, and a movement distance of less than 1000 mm indicates unsatisfactory wear resistance “C”. (4) Assessment of flexibility

[0056] As described below, the flexibility of the insulated electrical wires was evaluated according to the examples and comparison samples. First, each of the insulated electrical wires, cut to a length of 400 mm, was attached at a bending radius of 90 mm at positions 75 mm from either end. The insulated electrical wire was then bent vertically at a speed of 50 mm / min midway between these attachment points. At this point, the samples had a conductor cross-sectional area of ​​3 mm². 2 with a bending radius of 22.5 mm and the samples with a conductor cross-sectional area of ​​20 mm² 2 The samples were bent at a bending radius of 45 mm. The repulsive force during bending was measured using a load cell. A lower repulsive force indicates greater flexibility. The samples had a conductor cross-sectional area of ​​3 mm². 2The samples were evaluated such that a repulsion force of less than 2 N indicates high flexibility “A” and a repulsion force of 2 N or more indicates low flexibility “B”. The samples had a conductor cross-sectional area of ​​20 mm². 2 were rated such that a repulsion force of less than 10 N indicates high flexibility “A” and a repulsion force of 10 N or more indicates low flexibility “B”. Results

[0057] Tables 1 and 2 show evaluation results of the examples and comparative examples with respect to tensile energy at break, wear resistance, and flexibility, as well as the configurations of their insulated electrical wires. Examples A3, A4, A6, and A8 in Table 1 are non-inventive reference examples. Table 1 Beis games A1 A2 A3 A4 A5 A6 A7 A8 Thermoplastic polyester elastomer TPEE1 TPEE2 TPEE3 TPEE4 TPEE1 TPEE4 TPEE1 TPEE4 Conductor cross-sectional area (mm²) 2 ) 3 3 3 3 20 20 3 20 Coating thickness (mm) 0,4 0,4 0,4 0,4 0,65 0,65 0,75 1,1 Tensile energy at fracture (mJ / mm) 3 ) 492 533 175 218 476 214 501 236 Tensile modulus (MPa) 19 59 115 200 19 200 19 200 Wear resistance Measurement (mm) 650 800 250 500 2400 1500 1650 4200 Evaluation A A B B A B A A flexibility Measured value(N) 1,2 1,1 1,4 1,4 4,2 7,3 4,2 24 Evaluation A A A A A A B B Table 2 Comparative examples A1 A2 A3 A4 Polyvinyl chloride 100 100 100 100 Plasticizers 40 60 40 60 Non-lead heat stabilizer 5 5 5 5 Extender (calcium carbonate) 10 10 10 10 Conductor cross-sectional area (mm²) 2 ) 3 3 20 20 Coating thickness (mm) 0,4 0,4 0,65 0,65 Tensile energy at fracture (mJ / mm) 3 ) 28 48 32 46 Tensile modulus (MPa) 180 30 180 30 Wear resistance Measurement (mm) 100 50 750 450 Evaluation C C C C flexibility Measured value (N) 7,3 1,2 14,2 4,2 Evaluation B A B A

[0058] Firstly, in all comparative examples A1 to A4 of Table 2, the polymer component of the insulating coating is made of polyvinyl chloride, and therefore the wear resistance is insufficient. The tensile energy at breakage, which can reach up to 50 mJ / mm², is insufficient. 3 A value of less than or equal to a certain amount corresponds to low wear resistance. In comparison examples A2 and A4, where the plasticizer content is high, the flexibility is sometimes high, while in comparison examples A1 and A3, where the plasticizer content is low, not only the wear resistance but also the flexibility is low.

[0059] On the other hand, in all examples A1 to A8 of Table 1, the insulating coating is made of thermoplastic polyester elastomer, and thus the wear resistance is good. The high wear resistance corresponds to a tensile energy at break that is greater than that of the comparison examples. Furthermore, a comparison between examples A1 and A4, where the insulating coatings have the same thickness, shows that a higher tensile energy at break corresponds to higher wear resistance. In examples A1 and A2, where the melting point of the thermoplastic polyester elastomer is 200°C or less, particularly high wear resistance is achieved. The tensile modulus of elasticity does not show a clear correlation with wear resistance.

[0060] The flexibility of an insulated electrical wire depends on the thickness of the insulating coating. In examples A1 to A6, where the insulating coating thickness is less than 0.7 mm, the flexibility is high. The flexibility of an insulated electrical wire is not significantly dependent on the conductor's cross-sectional area. Test B: Relationship between tensile energy at break and wear resistance of the insulating coating. Test procedure (1) Sample preparation

[0061] Insulated electrical wires were manufactured as in the preceding test A. In this test, the conductor cross-sectional area was reduced to 3 mm². 2 and the thickness of the insulating coating was set to 0.7 mm.

[0062] The insulating coatings of the samples each consist of the resin materials shown in Table 3. The polyvinyl chloride used in sample B8 is the same resin composition as in comparison samples A2 and A4 of the preceding Test A. Furthermore, the polyester elastomer 1 used in sample B3 is the same as TPEE2 of Test A, and the polyester elastomer 2 used in sample B4 is the same as TPEE4 of Test A. The details of the other samples are as follows. - Polyurethane elastomer (ester-based): “Resamin P-1078”, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd. - Polyurethane elastomer (ether-based): “Resamin P-2283”, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd. - Polyolefin elastomer: “Thermorun QT60MB”, manufactured by Mitsubishi Chemical Corporation - Modified polyphenylene ether (PPE): “Xyron AF700”, manufactured by Asahi Kasei Corporation - Polyacetal (POM): “Tenac EX352”, manufactured by Asahi Kasei Corporation (2) Evaluation of characteristics

[0063] The tensile energy at fracture of each specimen was evaluated by plotting an SS curve as in Test A. Furthermore, the wear resistance was evaluated as in Test A. In the tensile tests to determine the tensile energy at fracture, the tensile modulus was also determined. Fig. Figure 2 shows, as an example, an SS curve obtained for sample B3. Results

[0064] Table 3 shows the evaluation results of the samples with regard to tensile modulus, tensile energy at break, and wear resistance, as well as the resin types of their insulating coatings. Furthermore, in Fig. 3. A relationship between the tensile energy at breakage and the result of the wear resistance assessment is plotted. Table 3 sample resin type Tensile modulus (MPa) Tensile energy at fracture (mJ / mm) 3 ) Wear resistance rating (mm) B1 Polyurethane elastomer (ester base) 30 550 2600 B2 Polyurethane elastomer (ester base) 7 685 3400 B3 Polyester elastomer 1 59 526 2500 B4 Polyester elastomer 2 200 232 1750 B5 Polyolefin elastomer 3 38 200 B6 Modified polyphenylene ether 2500 23 300 B7 Polyacetal 3000 46 300 B8 Polwine chloride 30 47 500

[0065] From Table 3 and Fig.Figure 3 shows that the tensile energy at fracture and the result of the wear resistance assessment are related, with wear resistance increasing with increasing tensile energy at fracture. As indicated by the dashed line in Fig. As shown in Figure 3, their relationship can essentially be approximated as a straight line. The resins from which the samples are made are of different types, and it can be said that such a relationship exists beyond the resin type. This result shows that the tensile energy at fracture of the resin material is an excellent indicator of wear resistance.

[0066] Particularly in samples B1 to B4, where a thermoplastic elastomer was used in the insulating coating, the tensile energy at break was up to 200 mJ / mm. 3 or more. Accordingly, the result of the wear resistance assessment was even over 1500 mm high.

[0067] Table 3 also shows the tensile modulus of elasticity for the individual resin types. It shows that, unlike the tensile energy at break, the tensile modulus of elasticity does not exhibit a clear correlation with wear resistance.

[0068] Although one embodiment of the present invention has been described in detail above, the present invention is in no way limited to the embodiment described above. Reference symbol list 10 Insulated electrical wire 12 Electrical wire conductor 12a Element wire 14 Insulating coating

Claims

[1] Insulated electrical wire, comprising: an electrical wire conductor; and an insulating coating that coats an outer circumferential surface of the electrical wire conductor, wherein the insulating coating is made from a resin composition containing a thermoplastic polyester elastomer as the main component, including the polymer components that make up the resin composition, the thermoplastic polyester elastomer content is 80% by mass or more, where the melting point of the thermoplastic polyester elastomer is 200°C or less, and where a tensile energy upon fracture of the resin composition, obtained by measuring only the insulating coating, obtained by removing the electrical wire conductor from the insulated electrical wire, 200 mJ / mm² 3 or more. [2] Insulated electrical wire according to claim 1, wherein the thickness of the insulating coating is less than 0.7 mm. [3] Insulated electrical wire according to claim 1 or 2, wherein the tensile energy on breakage of the resin composition is 400 mJ / mm 3 or more. [4] Insulated electrical wire according to any one of claims 1 to 3, wherein the hardness of the thermoplastic polyester elastomer is 60 or less, as defined by the Shore D hardness. [5] Insulated electrical wire according to any one of claims 1 to 4, wherein a conductor cross-sectional area of ​​the electrical wire conductor is 3 mm² 2 or more and 20 mm 2 or less. [6] Wiring harness comprising the insulated electrical wire according to any one of claims 1 to 5.

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