Wire Assembly

Abstract

To provide a wire assembly which has good cut-off performance between a resin mold member and a resin coating.SOLUTION: A wire assembly includes a wire having a conductor and a resin coating, a terminal member connected to the conductor at the end of the wire, and a resin mold member covering a region from the terminal member and the resin coating, wherein a value of a bonding work determined from surface free energy of the resin mold member, and surface free energy of the resin coating is equal to or more than 45 mJ / m2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrical wire assembly. [Background technology]

[0002] Patent Document 1 discloses a composite cable in which a first electric wire and a multi-core electric wire are collectively covered with an outer sheath. The multi-core electric wire has a configuration in which a plurality of second electric wires are covered with an inner sheath. The second electric wires include a conductor and an insulating layer. The inner sheath is a resin covering placed on the outermost periphery of the multi-core electric wire. A terminal member and a resin molded member are provided at the end of the multi-core electric wire. The terminal member is a sensor or the like that is electrically connected to the conductor of the second electric wire. The resin molded member covers the area from the terminal member to the outer periphery of the inner sheath. The resin molded member waterproofs the connection point between the conductor and the terminal member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-131054 Summary of the Invention [Problem to be solved by the invention]

[0004] To ensure watertightness at the connection point, the resin molded component and the resin-coated inner sheath must be bonded without any gaps. However, depending on the compatibility between the resins that make up the resin molded component and the resin that makes up the resin coating, sufficient watertightness may not be achieved. This compatibility may vary depending on the grade of the resin, the molecular weight of the resin, or the proportion of additives contained in the resin. For example, there will be a difference in adhesive ability to the resin coating between a resin molded component made of resin A and a resin molded component made of resin A containing additives.

[0005] In view of the above circumstances, one object of the present disclosure is to provide an electric wire assembly having good watertight performance between a resin molded member and a resin coating. [Means for solving the problem]

[0006] The wire assembly of the present disclosure comprises: an electric wire having a conductor and a resin coating; a terminal member connected to the conductor at an end of the wire; a resin molded member that covers an area extending from the terminal member to the resin coating, The value of the work of adhesion calculated from the surface free energy of the resin molded member and the surface free energy of the resin coating is 45 mJ / m 2 That's all. [Effects of the Invention]

[0007] The wire assembly of the present disclosure has excellent watertightness between the resin molded member and the resin coating in the wire assembly. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of the wire assembly described in embodiment 1. [Figure 2] FIG. 2 is a cross-sectional view of the electric wire described in the first embodiment. [Figure 3] FIG. 3 is a schematic diagram of the test device used in Test Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] The present inventors have investigated identifying a physical quantity related to the adhesion between a resin-molded member and a resin coating, and evaluating the watertightness between the resin-molded member and the resin coating based on whether the physical quantity is equal to or greater than a predetermined value. As a result, they have found that a wire assembly in which the value of the work of adhesion satisfies a predetermined value ensures sufficient watertightness between the resin-molded member and the resin coating. Details of the work of adhesion will be described later. The wire assembly of the present disclosure was obtained based on the above-mentioned findings.

[0010] First, the contents of the embodiments of the present disclosure will be listed and described.

[0011] <1> The wire assembly according to the embodiment includes: an electric wire having a conductor and a resin coating; a terminal member connected to the conductor at an end of the wire; a resin molded member that covers an area extending from the terminal member to the resin coating, The value of the work of adhesion calculated from the surface free energy of the resin molded member and the surface free energy of the resin coating is 45 mJ / m 2 That's all.

[0012] Surface free energy refers to the surface tension of a solid. Adhesion work refers to the amount of work required to separate the resin molding member and the resin coating that are bonded at the interface. Methods for calculating surface free energy and adhesion work will be described in detail in the embodiments.

[0013] The adhesive work value is 45mJ / m 2 If the above condition is met, it can be said that the resin-molded member and the resin coating are firmly bonded together, and therefore, the water-stopping property between the resin-molded member and the resin coating is easily maintained.

[0014] <2> In one example of an electric wire assembly according to an embodiment, the difference in strain between the resin molded member and the resin coating is 0.02 or less; The difference in strain is the difference between the strain of the resin molded member and the strain of the resin coating when the temperature changes from 90°C to 20°C.

[0015] The distortion of a member when the temperature changes from 90° C. to 20° C. can be calculated by multiplying the sum of the linear expansion coefficients of the member in 10° C. increments by the temperature difference. A specific method for calculating the distortion will be described in detail in the embodiments.

[0016] If the difference in strain between the resin-molded component and the resin coating is small, stress is less likely to act on the interface between the resin-molded component and the resin coating.If the difference in strain is 0.02 or less, good water-stopping properties are likely to be maintained between the resin-molded component and the resin coating.

[0017] <3> In one example of an electric wire assembly according to an embodiment, The shear bond strength between the resin molded member and the resin coating is 0.2 MPa or more.

[0018] The shear bond strength is calculated by dividing the load required for the bond to break when a tensile test is performed by the contact area. The contact area is the area of ​​the contact portion between the resin molded member and the resin coating. A specific method for determining the shear bond strength will be described in detail in the embodiments.

[0019] A high shear bond strength indicates that the resin-molded member and the resin coating are firmly bonded together. If the shear bond strength is 0.2 MPa or more, good water-stopping properties are likely to be maintained between the resin-molded member and the resin coating.

[0020] <4> In one example of an electric wire assembly according to an embodiment, The difference between the linear expansion coefficient of the resin molded member and the linear expansion coefficient of the resin coating at 20°C is 2.2 × 10 -4 / ℃ or less.

[0021] The linear expansion coefficients of the resin molded member and the resin coating are determined by thermomechanical analysis (TMA).

[0022] If the difference between the linear expansion coefficient of the resin molded member and the linear expansion coefficient of the resin coating is large, there is a risk of peeling occurring at the interface between the resin molded member and the resin coating during the manufacture of the electric wire assembly. In other words, if the difference is small, stress is less likely to act on the interface between the resin molded member and the resin coating. When the difference at 20°C is 2.2 × 10 -4 If the temperature is 100° C. or less, the water-stopping property between the resin molded member and the resin coating is easily maintained.

[0023] <5> In one example of an electric wire assembly according to an embodiment, The elastic modulus of the resin coating at 20°C is 100 MPa or less.

[0024] As will be described in the embodiments below, the elastic modulus of the resin coating at 20°C affects the magnitude of stress generated in the resin coating when an electric wire assembly is fabricated. If the elastic modulus of the resin coating at 20°C is 100 MPa or less, good watertightness between the resin molded member and the resin coating is likely to be maintained.

[0025] <6> In one example of an electric wire assembly according to an embodiment, The resin mold member covers the entire terminal member.

[0026] In a wire assembly in which a resin molded member covers the entire terminal member, the interface between the resin molded member and the resin coating is the only route for moisture to penetrate into the connection between the conductor and the terminal member. In the wire assembly of the embodiment, the high water-blocking properties between the resin molded member and the resin coating make it difficult for moisture to adhere to the connection. This prevents corrosion of the conductor or damage to the terminal member.

[0027] <7> In one example of an electric wire assembly according to an embodiment, The terminal member is a sensor.

[0028] If the terminal member is a sensor, it can measure a physical quantity in a device to which the electric wire assembly is mounted. For example, if the electric wire assembly is mounted in a vehicle, the sensor can monitor a physical quantity related to the operation of the vehicle. The type of sensor is not particularly limited.

[0029] [Details of the embodiments of the present disclosure] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate. The same reference numerals in the drawings indicate the same objects. The present invention is not limited to the exemplary embodiments, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0030] <Embodiment 1> The wire assembly 1 of this example shown in Fig. 1 includes an electric wire 2, a resin molded member 3, and a terminal member 4. One of the features of the wire assembly 1 of this example is that the resin coating 23 arranged on the outermost periphery of the electric wire 2 and the resin molded member 3 are firmly bonded together. Each component of the wire assembly 1 will be described below. Next, the physical quantities for determining whether the resin coating 23 and the resin molded member 3 are firmly bonded together will be described.

[0031] ≪Electric wire≫ As shown in the cross-sectional view of FIG. 2, the electric wire 2 of this example is a multi-core electric wire, a so-called twisted pair cable. The electric wire 2 of this example has two core wires 2A and 2B. The core wires 2A and 2B of this example have the same configuration. The number of core wires is not particularly limited. The configurations of the multiple core wires may be different. Unlike this example, the electric wire 2 may be a single core wire.

[0032] The core wires 2A and 2B each include a conductor 20 and an insulating layer 21. The conductor 20 is made of a conductive material such as aluminum, an aluminum alloy, copper, or a copper alloy. The conductor 20 is electrically connected to the terminal member 4 (FIG. 1). The insulating layer 21 is made of an insulating resin such as polyvinyl chloride or polyethylene.

[0033] The two core wires 2A, 2B are disposed inside a tubular resin coating 23. In this example, the resin coating 23 is a so-called sheath. In this example, there is a gap between the core wires 2A, 2B and the resin coating 23. Unlike this example, an inclusion such as a resin may be filled between the core wires 2A, 2B and the resin coating 23. An example of the inclusion is urethane resin. A shielding layer or the like may be provided on the inner periphery of the resin coating 23.

[0034] As shown in FIG. 1, a portion of the resin molded member 3 is disposed on the outer periphery of the resin coating 23. The inner periphery of the resin molded member 3 is bonded to the outer periphery of the resin coating 23. The main component of the resin coating 23 is a resin material. The main component means a component whose content in the resin coating 23 is 50 mass % or more. Examples of the resin material include polyurethane (PU) resin and polyester (PE) resin. The resin coating 23 may also contain additives such as a flame retardant or a filler.

[0035] Even if the resin material constituting resin coating 23 is the same, the adhesive strength between resin coating 23 and resin molded member 3 varies depending on the number of branched chains of the resin material, the molecular weight, the type and amount of additives contained in resin coating 23, etc. Therefore, even if resin coating 23 is made of, for example, PU resin, there are cases where it cannot satisfy the value of the work of adhesion described below.

[0036] Terminal parts The terminal member 4 shown in FIG. 1 is electrically connected to the conductor 20 (FIG. 2) of the electric wire 2. In this example, the terminal member 4 is a wheel speed sensor. The sensor is not limited to a wheel speed sensor. For example, the sensor may be a temperature sensor or an acceleration sensor. Unlike this example, the terminal member 4 may be a terminal or the like.

[0037] <Resin molded parts> The resin molded member 3 covers the area extending from the terminal member 4 to the resin coating 23. In this example, the resin molded member 3 covers the entire terminal member 4.

[0038] The resin molded member 3 overlaps the outer periphery of the resin coating 23 of the electric wire 2. In other words, the inner periphery of the resin molded member 3 is bonded to the outer periphery of the resin coating 23. The resin molded member 3 prevents moisture from adhering to the connection between the conductor 20 (FIG. 2) of the electric wire 2 and the terminal member 4. The longer the overlap length L0 between the resin molded member 3 and the resin coating 23 along the longitudinal direction of the electric wire 2, the better the water-stopping ability of the resin molded member 3. If the length L0 is too long, the resin molded member 3 becomes large, making it difficult to install the electric wire assembly 1 in a device. From the viewpoint of improving water-stopping ability and preventing an increase in size, the length L0 is preferably, for example, 1 mm or more and 100 mm or less. The length L0 may further be 5 mm or more and 50 mm or less.

[0039] Unlike this example, when the electric wire 2 is a single-core wire, the resin molded member 3 covers the outer periphery of the insulating layer 21 that is arranged on the outer periphery of the conductor 20. In other words, in an electric wire assembly including a single-core wire, the insulating layer 21 corresponds to the resin coating of the electric wire 2.

[0040] There is no particular limitation on the outer shape of the resin molded member 3. The outer shape of the resin molded member 3 in this example is a shape that follows the outer shape of the terminal member 4. Unlike this example, the resin molded member 3 may be provided with a flange or the like for fixing the wire assembly 1 to an attachment target.

[0041] The main component of the resin molded member 3 is a resin material. The main component means a component whose content in the resin molded member 3 is 50% by mass or more. Examples of the resin material include polyamide (PA) resin, polyphenylenesulfide (PPS) resin, and polybutyleneterephtalate (PBT) resin. The resin molded member 3 may also contain additives such as a flame retardant or a filler.

[0042] Even if the resin material constituting resin molded member 3 is the same, the adhesive strength between resin coating 23 and resin molded member 3 varies depending on the number of branched chains of the resin material, the molecular weight, the type and amount of additives contained in resin molded member 3, etc. Therefore, even if resin molded member 3 is made of, for example, PA resin, there are cases where it cannot satisfy the value of the work of adhesion described below.

[0043] In the wire assembly 1 of this example, "adhesion work" is defined as an index for evaluating the watertightness between the resin molded member 3 and the resin coating 23. If the adhesion work in the wire assembly 1 is equal to or greater than a predetermined value, it can be said that the watertightness between the resin molded member 3 and the resin coating 23 is high. Other indices for evaluating watertightness include "difference in strain," "shear bond strength," "difference in linear expansion coefficient," and "elastic modulus of the resin coating 23." Each index will be explained in detail below.

[0044] <Adhesion work> The work of adhesion is an index showing the degree of adhesion between the resin molded member 3 and the resin coating 23. In other words, the work of adhesion is an index showing how difficult it is to peel the resin molded member 3 from the resin coating 23, and is also an index for evaluating the water-stopping ability between the resin molded member 3 and the resin coating 23.

[0045] The work of adhesion is calculated from the surface free energy of the resin molded member 3 and the surface free energy of the resin coating 23. The surface free energy corresponds to the surface tension in a solid. To calculate the work of adhesion, the surface free energy of the resin molded member 3 and the surface free energy of the resin coating 23 are first calculated. The surface free energy can be calculated using the Young's equation and the extended Fowkes equation shown below.

[0046] Young's formula gamma S =γ L cosθ+γ SL θ: Contact angle of a droplet resting on a solid surface; unit is (π / 180) rad gamma S...Surface tension of a solid, i.e., surface free energy; unit is mJ / m 2 gamma L ...surface tension of the liquid that makes up the droplet; unit is mJ / m 2 gamma SL ...interfacial tension between a solid and a liquid; unit is mJ / m 2

[0047] Extended Fowkes formula gamma SL =γ S +γ L -2(γ S d gamma L d ) 1 / 2 -2(γ S p gamma L p ) 1 / 2 -2(γ S H gamma L H ) 1 / 2 gamma L d ...Dispersion component in the surface tension of a liquid gamma L P ...polar component in the surface tension of a liquid gamma L H ...Hydrogen bonding component in the surface tension of a liquid gamma S d ...dispersion component of the surface free energy of a solid gamma S P ...polar component in the surface free energy of a solid gamma S H ...Hydrogen bond component in the surface free energy of solids The units of each component of surface tension are mJ / m 2 , the unit of each component of surface free energy is mJ / m 2Although there is an induction component in surface tension, it can be ignored because it is very small.

[0048] γ in the extended Fowkes formula SL Substituting Young's equation into, we obtain the following equation (1).

[0049] ·Formula (1) gamma L (1+cosθ)=2(γ S d gamma L d ) 1 / 2 +2(γ S p gamma L p ) 1 / 2 +2(γ S H gamma L H ) 1 / 2

[0050] The surface free energy of a solid is γ L ,γ L d ,γ L p ,γ L H can be obtained by attaching three known types of liquid to a solid and measuring the contact angle θ. For example, γ S d ,γ S P ,γ S H To find this, the first liquid, the second liquid, and the third liquid, each with a known surface tension, are attached to the resin molded member 3, and three linear equations with three unknowns are obtained. S d ,γ S P ,γ S H The method for determining the surface free energy of the resin coating 23 is the same as the method for determining the surface free energy of the resin molded member 3.

[0051] The work of adhesion can be calculated using Dupre's formula below.

[0052] ·Dupre formula gamma 12 +W=γ1+γ2 W: Adhesion work; unit is mJ / m 2 gamma 12 …interfacial free energy; unit is mJ / m 2 γ1: Surface free energy of resin molded member 3 γ2: Surface free energy of the resin coating 23

[0053] where γ 12 is calculated by the extended Fowkes formula shown below.

[0054] Extended Fowkes formula gamma 12 =γ1+γ2-2(γ1 d γ2 d ) 1 / 2 -2(γ1 p γ2 p ) 1 / 2 -2(γ1 H γ2 H ) 1 / 2 γ1 d ...Dispersion component in the surface free energy of the resin molded member 3 γ1 P ...polar component in the surface free energy of the resin molded member 3 γ1 H ...Hydrogen bond component in the surface free energy of the resin molded member 3 γ2 d ...Dispersion component of surface free energy of resin coating 23 γ2 P ...Polar component in the surface free energy of resin coating 23 γ2 H ...Hydrogen bond component in the surface free energy of resin coating 23

[0055] Substituting the extended Fowkes formula into Dupre's formula, we obtain the following formula (2).

[0056] ·Formula (2) W=2(γ1 d γ2 d ) 1 / 2 +2(γ1 p γ2 p ) 1 / 2 +2(γ1 H γ2 H ) 1 / 2

[0057] Each component of the surface free energy of the resin molded member 3 to be substituted into formula (2) can be determined by formula (1). Similarly, each component of the surface free energy of the resin coating 23 to be substituted into formula (2) can also be determined by formula (1).

[0058] When the work of adhesion W is large, it can be said that the resin molded member 3 and the resin coating 23 are firmly bonded to each other. The work of adhesion W in the electric wire assembly 1 of this example is 45 mJ / m 2 The value of the adhesive work W is 45mJ / m 2 If this is the case, the watertightness between the resin molded member 3 and the resin coating 23 is easily maintained. The work of adhesion W is 65 mJ / m 2 It is preferable that the concentration is 80 mJ / m or more. 2 More preferably, it is equal to or greater than this.

[0059] <Difference in Distortion> The procedure for forming the resin molded member 3 around the outer periphery of the electric wire 2 and the terminal member 4 is as follows: Of the electric wire 2 to which the terminal member 4 is connected, the end of the electric wire 2 including the terminal member 4 is placed in a mold. Then, the material for the resin molded member 3 in a molten state is poured into the mold. The temperature of the mold is about 70°C. When the molten material flows into the mold, the resin coating 23 placed in the mold is heated to about 90°C. When the electric wire assembly 1 is removed from the mold, the electric wire assembly 1 is cooled to room temperature. If the room temperature is 20°C, the temperatures of the resin molded member 3 and the resin coating 23 change from 90°C to 20°C during the manufacture of the electric wire assembly 1. Due to the temperature change, distortion occurs in the resin molded member 3. Similarly, distortion also occurs in the resin coating 23. If there is a difference between the distortion of the resin molded member 3 and the distortion of the resin coating 23, stress acts at the interface between the resin molded member 3 and the resin coating 23. This stress is the force that peels the resin-molded member 3 from the resin coating 23. Therefore, the difference between the strain of the resin-molded member 3 and the strain of the resin coating 23 can be said to be an index for evaluating the water-stopping ability between the resin-molded member 3 and the resin coating 23.

[0060] The strain of each component is calculated based on its linear expansion coefficient. The linear expansion coefficients of the resin molded component 3 and the resin coating 23 are measured by a method conforming to JIS K 7197:2012. Specifically, these linear expansion coefficients are measured using TMA. TMA provides the linear expansion coefficients (1 / °C) for every 10°C. Specifically, the linear expansion coefficients X1 from 20°C to 30°C, X2 from 30°C to 40°C, X3 from 40°C to 50°C, X4 from 50°C to 60°C, X5 from 60°C to 70°C, X6 from 70°C to 80°C, and X7 from 80°C to 90°C are obtained. As shown in the following formula (3), the strain of each component can be calculated by multiplying the sum of the linear expansion coefficients from 90°C to 20°C by the temperature difference.

[0061] ·Formula (3) Distortion=(X1+X2+X3+X4+X5+X6+X7)×70

[0062] The strain difference is the absolute value of the difference between the strain of the resin molded member 3 calculated by formula (3) and the strain of the resin coating 23 calculated by formula (3). A small strain difference means that strong stress is unlikely to act on the interface between the resin molded member 3 and the resin coating 23. Therefore, the strain difference is preferably 0.02 or less. A more preferable strain difference is 0.0129 or less, and an even more preferable strain difference is 0.0011 or less.

[0063] <Shear adhesive strength> The shear bond strength is calculated by dividing the load required to break the bond by the contact area when a tensile test is conducted in which the wire 2 and the resin molded member 3 are pulled apart. Therefore, the shear bond strength can be considered an index for evaluating the watertightness between the resin molded member 3 and the resin coating 23.

[0064] The shear bond strength in this example can be determined as follows. For example, the electric wire assembly 1 is cut at the position shown by the two-dot chain line in Figure 1. The outer periphery of the electric wire 2 and the resin molded member 3 are each chucked, and the electric wire 2 is pulled in the direction away from the resin molded member 3 along the extension direction of the electric wire 2. The pulling speed is 10 mm / min. The load when either the resin molded member 3 or the resin coating 23 breaks is measured. This load is divided by the contact area between the resin molded member 3 and the resin coating 23. The unit of the load is N, and the unit of the contact area is mm 2 The contact area is calculated by multiplying the perimeter of the wire 2, i.e., the perimeter of the resin coating 23, by the length L1. The perimeter is calculated by multiplying the diameter of the wire 2 by π. The length L1 is the distance from the cut surface of the wire assembly 1 to the end of the resin molded member 3 on the wire 2 side.

[0065] A high shear bond strength between the resin molded member 3 and the resin coating 23 indicates that the resin molded member 3 and the resin coating 23 are firmly bonded together. Therefore, the shear bond strength is preferably 0.2 MPa or more. A more preferred shear bond strength is 0.8 MPa or more, and an even more preferred shear bond strength is 1.5 MPa or more.

[0066] <Difference in linear expansion coefficient> The linear expansion coefficient relates to the amount of expansion and contraction of a component due to temperature changes. Therefore, if there is a difference between the linear expansion coefficient of the resin molded component 3 and the linear expansion coefficient of the resin coating 23, stress acts on the interface between the resin molded component 3 and the resin coating 23. Therefore, the difference between the linear expansion coefficient of the resin molded component 3 and the linear expansion coefficient of the resin coating 23 can be said to be an index for evaluating the watertightness between the resin molded component 3 and the resin coating 23. The linear expansion coefficients of the resin molded component 3 and the resin coating 23 can each be determined by TMA.

[0067] If the difference between the linear expansion coefficient of the resin molded member 3 and the linear expansion coefficient of the resin coating 23 is large, peeling may occur at the interface between the resin molded member 3 and the resin coating 23 during the manufacture of the electric wire assembly 1. If the difference in the linear expansion coefficient at 20°C is 2.2 × 10 -4 / °C or less, the watertightness between the resin molded member 3 and the resin coating 23 is easily maintained. -4 / °C or less, more preferably 1.5 × 10 -4 / °C or less is more preferable.

[0068] <Elastic modulus> As described above, during the manufacturing process of the wire assembly 1, the resin coating 23 of the wire 2 is heated in a mold. If the resin coating 23 has a high elastic modulus, significant strain will occur in the resin coating 23 when the wire assembly 1 is removed from the mold and the resin coating 23 is cooled to room temperature. The stress generated in the resin coating 23 due to this strain may cause the resin molded member 3 to peel off from the resin coating 23. The stress is calculated by multiplying the strain generated in the resin coating 23 by the elastic modulus of the resin coating 23. Therefore, selecting a resin coating 23 with a low elastic modulus makes it difficult for the resin molded member 3 to peel off from the resin coating 23. Within the temperature range of the resin coating 23 during the manufacturing process of the wire assembly 1, the elastic modulus of the resin coating 23 is at its maximum at 20°C. Therefore, to evaluate its waterproofing performance, it is necessary to measure the elastic modulus of the resin coating 23 at 20°C. The elastic modulus is determined using a measurement method conforming to JIS K 7244.

[0069] If the elastic modulus of resin coating 23 is 100 MPa or less, it is easy to maintain good watertightness between resin molded member 3 and resin coating 23. The elastic modulus is preferably 60 MPa or less, and more preferably 20 MPa or less.

[0070] <Test Example 1> In this test example, electric wire assemblies 1 were produced for Samples No. 1 to No. 6, in which the material of the resin molded member 3 and the material of the resin coating 23 were different. The resin molded member 3 was either Resin molded member A or Resin molded member B shown in Table 1. Resin molded member A was made of PA6T, a heat-resistant PA resin. The melting point of Resin molded member A was 300°C. Resin molded member B was made of PA612, a type of PA resin. The melting point of Resin molded member B was 220°C.

[0071] [Table 1]

[0072] Resin coating 23 is any one of resin coating C, resin coating D, resin coating E, resin coating F, resin coating G, and resin coating H shown in Table 2. In Table 2, resin coatings with "Yes" in the crosslinked column have crosslinked resins. Resin coatings with "Yes" in the filler column contain fillers. Resin coatings with "Yes" in the flame retardant column contain flame retardants. The flame retardants were metal hydroxides. The filler content in resin coating C was 50% by mass when resin coating C was taken as 100% by mass. The filler content in resin coating F was 40% by mass when resin coating F was taken as 100% by mass.

[0073] [Table 2]

[0074] The electric wire assemblies 1 of Samples No. 1 to No. 6 were subjected to a leak test. An overview of the leak test is shown in Figure 3. As shown in Figure 3, water was filled in a water tank 7, and the resin molded member 3 of the electric wire assembly 1 was placed in the water. Next, air was pumped into the inside of the electric wire 2 from the end opposite the resin molded member 3 using an air pump (not shown). The air pressure was gradually increased, and the value on the pressure meter of the air pump was recorded when air leaked from the gap between the resin molded member 3 and the resin coating 23. The value on the pressure meter when air leakage occurred is called the leak pressure (kPa). If the leak pressure is 30 kPa or higher, it can be determined that the watertightness is good, and if it is 50 kPa or higher, it can be determined that the watertightness is excellent. The leak pressure results are shown in Table 3. Table 3 shows the material of each sample, the work of adhesion (mJ / m 2 ), difference in strain, shear bond strength (MPa), difference in linear expansion coefficient, and elastic modulus of the resin coating (MPa) are also shown. Each physical quantity was measured according to the method shown in the embodiment.

[0075] [Table 3]

[0076] As shown in Table 3, the work of adhesion was 45 mJ / m 2 The leak pressure of the wire assemblies 1 of Samples No. 1 to No. 4 was much higher than 30 kPa. It can be determined that the watertightness of the wire assemblies 1 of Samples No. 1 to No. 4 is good. By comparing Samples No. 1 to No. 4, it was found that the higher the work of adhesion, the higher the leak pressure. In particular, when the work of adhesion was 65 mJ / m 2 The leak pressures of Samples No. 1 and No. 2 were significantly higher than 50 kPa.

[0077] From the results shown in Table 3, the difference in strain was 0.02 or less, the shear bond strength was 0.2 MPa or more, and the difference in linear expansion coefficient was 2.2 × 10 -4 It was found that when the elastic modulus of the resin coating is 100 MPa or less, the leak pressure of the electric wire assembly 1 becomes 30 kPa or more. [Explanation of symbols]

[0078] 1 Wire Assembly 2 electric wire 2A core wire 2B core wire 20 Conductors 21 Insulating layer 23 Resin coating 3. Resin molded parts 4 Terminal members 7. Aquarium L0 length L1 length

Claims

1. an electric wire having a conductor and a resin coating; a terminal member connected to the conductor at an end of the wire; a resin molded member that covers an area extending from the terminal member to the resin coating, The value of the work of adhesion calculated from the surface free energy of the resin molded member and the surface free energy of the resin coating is 45 mJ / m ２ That's all, a difference in strain between the resin molded member and the resin coating is 0.02 or less; The difference in strain is the difference between the strain of the resin molded member and the strain of the resin coating when the temperature changes from 90°C to 20°C. Wire assembly.

2. The electric wire assembly according to claim 1 , wherein the shear bond strength between the resin molded member and the resin coating is 0.2 MPa or more.

3. The difference between the linear expansion coefficient of the resin molded member and the linear expansion coefficient of the resin coating at 20°C is 2.2 × 10 －４ The wire assembly according to claim 1 or claim 2, wherein the temperature is 100°C or less.

4. The electric wire assembly according to claim 1 , wherein the resin coating has a modulus of elasticity of 100 MPa or less at 20° C.

5. The electric wire assembly according to claim 1 , wherein the resin mold member covers the entire terminal member.

6. The wire assembly according to claim 1 , wherein the terminal member is a sensor.

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