Electric wire with terminal

Abstract

The invention provides an electric wire with a terminal, which can improve the waterproof property of a resin coating part for coating an electric connection part between a terminal fitting and an insulated electric wire without using a liquid adhesive. A terminal-equipped electric wire (1) is provided with: an electric wire section (6) obtained by electrically connecting, at an electric connection section (6a), a terminal fitting (5) and an insulated electric wire (2) in which the outer periphery of a conductor (3) is coated with an insulating coating layer (4); a pipe material (7) that covers the outer periphery of the insulating coating layer (4) at a portion thereof in the axial direction of the insulated wire (2); and a resin coating part (8) formed so as to cover a portion of the electric wire part (6) including the electric connection part (6a) and so as to be in contact with at least a part of the outer peripheral surface of the pipe (7), the pipe (7) being configured as a single-layer cylindrical member, the pipe containing: a crosslinked polyolefin resin; and at least one of an acid-modified resin and a thermoplastic elastomer, the acid-modified resin being 5-40 mass% inclusive in the resin component, and the thermoplastic elastomer being 20-40 mass% inclusive in the resin component.

Description

Technical Field

[0001] The present disclosure relates to an electric wire with a terminal. Background Art

[0002] In insulated wires installed in vehicles such as automobiles, terminal fittings are often connected to the conductor at the end. If electrolyte liquids such as water come into contact with the electrical connection formed by the terminal fittings and the wire conductor, electrical problems such as short circuits and corrosion of metal materials may occur. In order to prevent these electrical problems and corrosion, it is required to waterproof the electrical connection.

[0003] It is well known that the electrical connection part is covered with a resin coating such as a molded part in order to waterproof the electrical connection part. The resin coating part is formed in a region from the electrical connection part to a part of the end of the insulated wire. However, if a gap is generated between the resin coating part and the insulated wire, liquids such as water will intrude from the gap, and electrical problems such as short circuits and corrosion of metal materials may occur in the electrical connection part. As a means to suppress the intrusion of such liquids from the gap, a method of placing an adhesive layer between the insulated wire and the resin coating part is sometimes used. For example, Patent Document 1 discloses the following method: an adhesive layer is formed on the surface of the insulating coating layer at the end of the insulated wire, and a waterproof resin part (resin coating part) is formed including a portion where the adhesive layer is formed. In addition, there is also a case where a tube such as a heat shrink tube is used instead of an adhesive. For example, Patent Document 2 discloses the following method: after an adhesive tube covering the end of the insulating material of the insulated wire is provided, a molded part (resin coating part) is formed including an area covering a part of the adhesive tube. The adhesive tube of Patent Document 2 is made of a thermoplastic resin having a cross-linked structure and has heat shrinkability.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-187041

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-091639 Summary of the invention

[0008] Problems to be solved by the invention

[0009] When a liquid adhesive is used to compensate for the waterproofness of the resin coating as disclosed in Patent Document 1, there may be disadvantages such as the film thickness of the liquid adhesive being easily varied and the solvent contained in the liquid adhesive taking a long time to dry. In addition, from the viewpoint of following the thermal expansion difference between the insulating coating layer of the insulated wire and the resin coating, it is required to form a thick layer of the adhesive, but it is difficult to form a thick layer using a liquid adhesive. In contrast, if a tube such as a heat shrink tube is used instead of an adhesive as disclosed in Patent Document 2, a layer having a sufficient thickness and excellent thickness uniformity can be easily arranged at a location between the resin coating and the insulated wire.

[0010] Patent Document 2 lists as the constituent material of the adhesive tube a thermoplastic resin having a cross-linked structure, especially a synthetic resin having a polyolefin resin such as cross-linked polyethylene and cross-linked polypropylene as the main component. It is believed that the intrusion of liquid can be suppressed by bonding the outer peripheral surface of the adhesive tube to the inner peripheral surface of the molded portion. However, in automobiles and the like, there are cases where a particularly high level of waterproofness is required depending on the use of the wire with a terminal and the location where the wire with a terminal is laid. By further studying the constituent material of the adhesive tube based on the constituent material described in Patent Document 2, it is possible to achieve a higher level of waterproofness.

[0011] In view of the above, an object is to provide an electric wire with a terminal capable of improving the waterproofness of a resin coating portion covering an electrical connection portion between a terminal fitting and an insulated electric wire without using a liquid adhesive.

[0012] Means for solving problems

[0013] The terminal-equipped electric wire disclosed in the present invention comprises: an electric wire portion obtained by electrically connecting a terminal fitting and an insulated electric wire formed by covering the outer periphery of a conductor with an insulating coating at an electrical connection portion; a tubing covering the outer periphery of the insulating coating at a portion along the axial direction of the insulated electric wire; and a resin coating portion formed in a manner covering a portion of the electric wire portion including the electrical connection portion and contacting at least a portion of the outer peripheral surface of the tubing, the tubing being configured as a single-layer cylindrical member, the tubing comprising: a cross-linked polyolefin-based resin; and at least one of an acid-modified resin and a thermoplastic elastomer, the acid-modified resin accounting for 5% to 40% by mass in the resin component, and the thermoplastic elastomer accounting for 20% to 40% by mass in the resin component.

[0014] Effects of the Invention

[0015] The electric wire with terminal according to the present disclosure is an electric wire with terminal capable of improving the waterproofness of the resin coating portion covering the electrical connection portion between the terminal fitting and the insulated wire without using a liquid adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a perspective side view showing an electric wire with a terminal according to an embodiment of the present disclosure. Here, the pipe is indicated by a dotted line.

[0017] Figure 2 This is a partial cross-sectional view showing the pipe material and the resin coating portion cut away in the above-mentioned electric wire with a terminal. DETAILED DESCRIPTION

[0018] [Description of Embodiments of the Present Disclosure]

[0019] First, an embodiment of the present disclosure is described.

[0020] (1) The terminal-equipped electric wire disclosed in the present invention comprises: an electric wire portion obtained by electrically connecting a terminal fitting and an insulated electric wire formed by covering the outer periphery of a conductor with an insulating coating at an electrical connection portion; a tubular material covering the outer periphery of the insulating coating at a portion along the axial direction of the insulated electric wire; and a resin coating portion formed in a manner covering a portion of the electric wire portion including the electrical connection portion and contacting at least a portion of the outer peripheral surface of the tubular material, the tubular material being constituted as a single-layer cylindrical member, the tubular material comprising: a cross-linked polyolefin-based resin; and at least one of an acid-modified resin and a thermoplastic elastomer, the acid-modified resin accounting for 5% to 40% by mass in the resin component, and the thermoplastic elastomer accounting for 20% to 40% by mass in the resin component.

[0021] In the above-mentioned electric wire with a terminal, a pipe is provided between the resin coating of the electrical connection portion between the terminal fitting and the insulated wire and the insulated wire. The pipe contains at least one of the acid-modified resin and the thermoplastic elastomer in the above-mentioned prescribed amount in addition to the cross-linked polyolefin resin, thereby exhibiting high adhesion to the insulating coating layer and the resin coating. Therefore, the resin coating is firmly bonded to the insulated wire via the pipe, and it is not easy for liquids such as water to penetrate from the area between the resin coating and the insulated wire. As a result, in the electric wire with a terminal, the waterproofness imparted by the resin coating is effectively improved by the pipe. The pipe is also excellent in manufacturability.

[0022] (2) In the above-mentioned embodiment (1), the pipe preferably contains both the acid-modified resin and the thermoplastic elastomer. In this way, the adhesion between the pipe and the insulating coating layer and the resin coating is particularly improved, and the waterproofing effect is enhanced.

[0023] (3) In the above-mentioned solution (1) or (2), the thermoplastic elastomer and the resin material constituting the resin coating part preferably have the same skeleton. In this way, the adhesion of the pipe material to the resin coating part becomes particularly high, and a high effect is obtained in improving the waterproof property.

[0024] (4) In any of the above-mentioned embodiments (1) to (3), the thermoplastic elastomer preferably includes at least one of a polyester elastomer and a polyamide elastomer. In this way, the tube exhibits high adhesion to the insulating coating layer and the resin coating. Polyester resins and polyamide resins are often used as constituent materials of molded parts provided on electric wires with terminals. In the case where the resin coating is constituted as a molded part composed of these resin materials, if the tube contains the above-mentioned elastomer, the tube exhibits particularly high adhesion to the molded part, and can effectively suppress the intrusion of liquid from the area between the resin coating and the insulated wire.

[0025] (5) In any one of the above (1) to (4), the acid-modified resin preferably includes an acid-modified polyolefin resin. This makes it easy to form a pipe material that exhibits high adhesion to the insulating coating layer and the resin coating together with the cross-linked polyolefin resin.

[0026] (6) In any of the above (1) to (5), the resin coating preferably covers the entire outer peripheral surface of the tube. In this way, the entire area of ​​the tube is disposed between the resin coating and the insulated wire, which can help improve the adhesion between the resin coating and the insulated wire.

[0027] [Details of the embodiments of the present disclosure]

[0028] Hereinafter, the electric wire with a terminal according to one embodiment of the present disclosure will be described in detail with reference to the drawings. Hereinafter, various properties are values ​​measured at room temperature and in the atmosphere unless otherwise specified.

[0029] <Overall structure>

[0030] First, refer to Figure 1 , 2 The overall structure of the electric wire with terminal 1 according to one embodiment of the present disclosure will be described. The electric wire with terminal 1 includes an electric wire portion 6, a pipe material 7, and a resin coating portion 8. Figure 1 In FIG. 1 , the electric wire 1 with the terminal is shown in a perspective side view. Here, the pipe 7 is indicated by a dotted line. Figure 2 In FIG. 1 , the electric wire with a terminal 1 is shown in a partial cross-sectional view in which only the tube 7 and the resin coating portion 8 are cut.

[0031] In the wire portion 6, the insulated wire 2 formed by covering the conductor 3 with the insulating coating 4 and the terminal fitting 5 are electrically connected at the electrical connection portion 6a. The terminal fitting 5 has a terminal connection portion 51, and has a barrel portion formed by a first barrel portion 52 and a second barrel portion 53 and extending integrally at the rear end side of the terminal connection portion 51. The terminal connection portion 51 is configured as a bolt-fastened connection portion, and can be electrically connected to a counterpart conductive member using a bolt inserted into the bolt insertion hole 51a.

[0032] At the electrical connection portion 6a, the insulating coating 4 at the end of the insulated wire 2 is removed to expose the conductor 3. The end of the insulated wire 2 with the conductor 3 exposed is fixed to one side ( ) of the barrel 52, 53 of the terminal fitting 5 by crimping. Figure 1 , 2 The first barrel 52 is formed on the upper surface side of the wire 1 with a terminal, and connects the insulated wire 2 and the terminal fitting 5. Specifically, the first barrel 52 electrically connects the conductor 3 and the terminal fitting 5, and physically fixes the conductor 3 to the terminal fitting 5. On the other hand, the second barrel 53 fixes the insulated wire 2 at a position further back than the first barrel 52, and assists in the physical fixation of the insulated wire 2 to the terminal fitting 5. In this specification, along the axial direction (length direction) of the wire 1 with a terminal, the side where the terminal fitting 5 is arranged is set as the front, and the side where the insulated wire 2 is arranged is set as the rear.

[0033] The pipe 7 is a single-layer cylindrical member made of a predetermined material described later. The pipe 7 covers the outer circumference of the insulating coating 4 at a portion along the axial direction of the insulated wire 2. In the illustrated embodiment, the pipe 7 covers the entire circumference of the region near the end of the insulated wire 2.

[0034] The resin coating 8 is formed as a coating layer made of a resin material such as a molded part, and covers a portion of the wire portion 6 including the electrical connection portion 6a. The resin coating 8 is in contact with at least a portion of the outer peripheral surface of the tube 7. In the illustrated embodiment, the resin coating 8 covers the entire outer peripheral surface of the tube 7. The resin coating 8 is formed along the axial direction of the wire 1 with a terminal in a region from a position forward of the front end 3a of the conductor 3 exposed at the end of the insulated wire 2 to a position backward of the front end of the insulating coating 4 of the insulated wire 2, and covers the entire range of the electrical connection portion 6a and a portion of the region where the insulating coating 4 of the insulated wire 2 remains. The region where the resin coating 8 covers the insulating coating 4 of the insulated wire 2 also includes the region where the tube 7 is provided.

[0035] In this way, the pipe 7 is arranged in a manner to cover the outer periphery of the insulating coating 4 of the insulated wire 2, and further the outer periphery thereof is covered by the resin coating 8. The pipe 7 is composed of a single-layer material, and no other material such as an adhesive is provided between the pipe 7 and the insulating coating 4 and between the pipe 7 and the resin coating 8. The pipe 7 is bonded to the surface of the insulating coating 4 at the inner peripheral surface, and is bonded to the inner peripheral surface of the resin coating 8 at the outer peripheral surface. Here, the bonding of the inner and outer surfaces of the pipe 7 to the insulating coating 4 and the resin coating 8 occurs by welding (fusion). That is, the material constituting the single-layer pipe 7 melts and then solidifies in the inner peripheral surface and the outer peripheral surface and the depth region near them, thereby being bonded to the insulating coating 4 and the resin coating 8 respectively over the entire circumference.

[0036] In the electric wire with terminal 1 according to the present embodiment, the resin coating 8 covers the entire range of the electric connection portion 6a of the electric wire portion 6. Therefore, the electric connection portion 6a is protected by the resin coating 8 and is prevented from contacting with liquids such as water. Moreover, a pipe 7 is provided between the resin coating 8 and the insulated electric wire 2, and the pipe 7 is bonded to both the resin coating 8 and the insulated electric wire 2. Therefore, the resin coating 8 is closely attached to the outer periphery of the insulating coating 4 without a gap through the pipe 7, and the presence of the pipe 7 inhibits the intrusion of liquids such as water from the portion between the resin coating 8 and the insulating coating 4 into the electric connection portion 6a. That is, the pipe 7 plays a role in improving the waterproofness of the electric wire with terminal 1. In particular, the pipe 7 is composed of a predetermined material described later, and has excellent adhesion to the insulating coating 4 and the resin coating 8, and has a high effect on improving the waterproofness. Since the resin coating 8 and the tube 7 prevent electrolytes such as water from entering the electrical connection portion 6 a , electrical problems such as short circuits and corrosion of metal materials are less likely to occur in the electrical connection portion 6 a .

[0037] <Structure of each part>

[0038] Hereinafter, specific structures of the electric wire portion 6 , the resin coating portion 8 , and the tube material 7 constituting the electric wire with terminal 1 will be described in order.

[0039] (Wire Department)

[0040] As described above, the electric wire portion 6 has a structure in which the terminal fitting 5 is connected to the terminal portion of the insulated electric wire 2 via the electrical connection portion 6 a.

[0041] The conductor 3 constituting the insulated wire 2 may be composed of a single metal wire, but is preferably composed of a stranded wire formed by twisting a plurality of wires. In this case, the stranded wire may be composed of one metal wire or two or more metal wires. Examples of the material of the metal wire constituting the conductor 3 include copper, copper alloys, aluminum, aluminum alloys, or materials obtained by applying various platings to these materials.

[0042] As materials constituting the insulating coating layer 4 of the insulated wire 2, for example, polyolefin resins such as rubber, polyethylene (PE), polypropylene (PP), halogen polymers such as polyvinyl chloride (PVC), thermoplastic elastomers, etc. can be cited. They can be used alone or in combination of two or more. The resin material can also be cross-linked. Various additives can also be appropriately added to the constituent materials of the insulating coating layer 4. As additives, flame retardants, fillers, colorants, etc. can be cited.

[0043] As the material (the material of the base material) of the terminal fitting 5, various copper alloys, copper, etc. can be cited in addition to the generally used brass. A part (such as a contact) or the entire surface of the terminal fitting 5 can also be plated with various metals such as tin, nickel, gold, or alloys thereof.

[0044] As described above, the conductor 3 and the terminal fitting 5 may be made of any metal material, but when dissimilar metals come into contact at the electrical connection portion 6a, such as when the terminal fitting 5 is made of a general terminal material obtained by tinning a base material made of copper or a copper alloy and the conductor 3 includes a wire made of aluminum or an aluminum alloy, corrosion is particularly likely to occur at the electrical connection portion 6a due to contact with an electrolyte such as water. However, in the electric wire with a terminal 1 according to the present embodiment, the waterproof structure in which the resin coating 8 covers the electrical connection portion 6a and the pipe 7 is provided between the resin coating 8 and the insulated wire 2 can also suppress such corrosion such as corrosion between dissimilar metals.

[0045] (Resin coating)

[0046] As described above, the resin coating 8 can prevent liquid such as water from intruding into the electrical connection portion 6a from the outside by coating the electrical connection portion 6a between the terminal fitting 5 and the conductor 3. Figure 1 , 2 As shown, the resin coating 8 contacts the surface of the terminal fitting 5 at the front side and contacts the insulating coating 4 and the tube 7 of the insulated wire 2 at the rear side, covering the entire area including the electrical connection portion 6a.

[0047] As long as the resin coating 8 is arranged along the axial direction of the electric wire portion 6 so as to cover the entire range of the electric connection portion 6a and to contact at least a portion of the outer peripheral surface of the pipe 7, the specific range of the arrangement is not specified. That is, the resin coating 8 may cover only the outer peripheral surface of a portion of the front side of the pipe 7 along the front-to-back direction, or may cover the entire range of the outer peripheral surface of the pipe 7. However, it is preferred that the resin coating 8 covers the entire range of the outer peripheral surface of the pipe 7 along the front-to-back direction and along the circumferential direction as shown in the figure. In this way, the pipe 7 contacts and adheres to the resin coating 8 over the entire range of the outer peripheral surface, thereby improving the adhesion between the resin coating 8 and the insulated wire 2, and obtaining a higher effect of suppressing the intrusion of liquid from the portion between them by the pipe 7.

[0048] The constituent material of the resin coating 8 is not particularly limited, and various resin materials can be applied, but polyester resins such as polybutylene terephthalate (PBT) and polyamide resins such as aromatic nylon can be appropriately used. These resins can firmly inhibit the intrusion of liquids such as water and exhibit high mechanical strength. The resin material constituting the resin coating 8 can be only one kind, or it can be mixed with more than two kinds. Various additives can also be appropriately added to the constituent materials of the resin coating 8. As additives, flame retardants, fillers, colorants, etc. can be cited.

[0049] The resin coating 8 composed of a polyester resin or a polyamide resin exhibits high adhesion to the surface of metal materials such as the terminal fitting 5 and the wire conductor 3. Therefore, in the electrical connection portion 6a, the resin coating 8 is directly in close contact with the surface of these metal materials, and the intrusion of liquid from the outside can be firmly suppressed. On the other hand, the resin coating 8 composed of such a resin often does not exhibit high adhesion to the insulating coating 4 composed of polyolefin, PVC, etc. However, in the electric wire 1 with a terminal involved in this embodiment, at the rear part of the resin coating 8, a pipe 7 that exhibits adhesion to both the insulating coating 4 and the resin coating 8 is located between the insulating coating 4 and the resin coating 8, and the insulating coating 4 and the resin coating 8 are bonded to each other via the pipe 7.

[0050] The resin coating 8 can also be arranged at a predetermined position by any method such as coating and molding of molten resin. However, it is preferred that the resin coating 8 is formed as a molded product obtained by molding molten resin. The resin coating 8 containing polyester resin or polyamide resin can be suitably formed as a molded product.

[0051] (Pipe)

[0052] The tube 7 is an insulating resin member that is pre-formed into a cylindrical shape before being arranged on the outer periphery of the insulated wire 2. The tube 7 is a single-layer cylindrical member, and has no layers other than the cylindrical member such as a liquid adhesive layer on the inner and outer peripheral surfaces.

[0053] The constituent material of the tube 7 includes a cross-linked polyolefin resin and further includes at least one of an acid-modified resin and a thermoplastic elastomer. Preferably, the tube 7 includes at least an acid-modified resin in addition to the cross-linked polyolefin resin. More preferably, the tube 7 includes both an acid-modified resin and a thermoplastic elastomer in addition to the cross-linked polyolefin resin. As described above, the tube 7 is formed of a single layer, and each resin is uniformly mixed and formed.

[0054] Crosslinked polyolefin resin is a resin having a crosslinked structure between polymer chains of the polyolefin resin. As the polyolefin resin constituting the crosslinked polyolefin resin, homopolymer polyolefins such as polyethylene (PE) and polypropylene (PP), block polyolefins such as ethylene-propylene copolymers, ethylene copolymers, etc. can be cited. In particular, polyolefins headed by PE are preferably used. As the polyolefin resin, only one kind can be used, or two or more kinds can be mixed and used. The polyolefin resin is different from the acid-modified resin described below and is not acid-modified. The crosslinked polyolefin resin exhibits a certain degree of adhesion relative to the insulating coating layer 4 and the resin coating portion 8 by welding.

[0055] The crosslinking of the polyolefin resin is preferably performed by irradiation with ionizing radiation, particularly electron beams. However, other crosslinking methods other than crosslinking based on ionizing radiation, such as silane crosslinking, may also be used. It should be noted that in the pipe 7, the polyolefin resin as described above and the acid-modified resin and / or the thermoplastic elastomer may also be crosslinked in a mixed state.

[0056] The tube 7 can be configured as a heat-shrinkable tube by including a cross-linked polyolefin resin. That is, the tube 7 can be given heat shrinkability by extruding a resin composition including an olefin resin into a small-diameter tube shape, cross-linking the tube by electron beam irradiation, etc., and then expanding the diameter of the small-diameter tube while heating. If the tube 7 configured as a heat-shrinkable tube is arranged at a predetermined position of the insulated wire 2 and heated to shrink, the tube 7 can be arranged in close contact with the outer peripheral surface of the insulated wire 2. During the heating process, the inner peripheral surface of the tube 7 can be welded to the surface of the insulating coating 4 at the same time.

[0057] The content of the cross-linked polyolefin resin in the pipe 7 is not particularly limited. However, from the viewpoint of ensuring the manufacturability of the pipe 7, the cross-linked polyolefin resin preferably occupies the main component of the resin component constituting the pipe 7. That is, the cross-linked polyolefin resin preferably occupies 50% by mass or more of the resin component of the pipe 7. In particular, the cross-linked polyolefin resin preferably occupies 60% by mass or more and 95% by mass or less of the resin component constituting the pipe 7. In addition, the cross-linked polyolefin resin preferably occupies the remainder of the resin component constituting the pipe 7 excluding the acid-modified resin and the thermoplastic elastomer. It should be noted that in this specification, the content shown in mass % for each component constituting the pipe 7 refers to the amount of the resin component (polymer component) in the constituent material of the pipe 7.

[0058] As described above, the constituent material of the pipe 7 preferably contains an acid-modified resin. The type of resin constituting the acid-modified resin is not particularly limited, but polyolefin resins or other thermoplastic resins can be suitably used. As polyolefin resins, homopolyolefins such as polyethylene (PE) and polypropylene (PP), block polyolefins such as ethylene-propylene copolymers, ethylene copolymers, etc. can be cited. As thermoplastic resins other than polyolefin resins, styrene resins such as styrene-ethylene-butylene-styrene block copolymers (SEBS) can be suitably used. In particular, from the viewpoint of affinity with cross-linked polyolefin resins, polyolefins headed by PP are preferably used. The acid-modified resin can be used alone or two or more can be mixed.

[0059] Since the constituent material of the pipe 7 includes an acid-modified resin in addition to the cross-linked polyolefin resin, the adhesion of the pipe 7 to the insulating coating 4 and the resin coating 8 becomes high. In particular, when the resin coating 8 includes a structure having polarity such as a polyester resin or a polyamide resin, the pipe 7 exhibits high adhesion to the resin coating 8 due to the interaction between these polar structures and the acid-modified part of the acid-modified resin.

[0060] The content of the acid-modified resin in the constituent material of the pipe material 7 is preferably 5% by mass or more from the viewpoint of obtaining a sufficient effect of improving adhesion. Further, it is preferably 10% by mass or more, and further preferably 20% by mass or more. On the other hand, if the content of the acid-modified resin is too high, the constituent material of the pipe material 7 becomes brittle, and damage such as breakage occurs during the manufacturing process such as extrusion molding and diameter expansion, and the manufacturing of the pipe material 7 may become difficult. From the viewpoint of ensuring the manufacturability of the pipe material 7, the content of the acid-modified resin is preferably suppressed to 40% by mass or less, and further preferably 30% by mass or less.

[0061] In addition, the constituent material of the pipe 7 preferably contains a thermoplastic elastomer in addition to or instead of the acid-modified resin. The thermoplastic elastomer is not particularly limited to a specific type as long as it is an elastomer, that is, a polymer type having a hard segment and a soft segment. The adhesion of the pipe 7 to the insulating coating layer 4 and the resin coating 8 is improved by the contribution of the soft segment mainly contained in the thermoplastic elastomer. The thermoplastic elastomer is different from the above-mentioned acid-modified resin and is not acid-modified.

[0062] In particular, the thermoplastic elastomer preferably contains at least one of a polyester elastomer whose hard segment is composed of polyester units and a polyamide elastomer whose hard segment is composed of polyamide units. These thermoplastic elastomers have a high effect on improving the adhesion of the tube 7. In particular, the thermoplastic elastomer preferably has the same skeleton as the resin material constituting the resin coating portion 8. For example, in the case where the resin coating portion 8 contains a polyester resin such as PBT, a polyester elastomer can be used for the tube 7. In addition, in the case where the resin coating portion 8 contains a polyamide resin such as aromatic nylon, a polyamide elastomer can be used for the tube 7. In the case where the thermoplastic elastomer contained in the tube 7 and the resin material constituting the resin coating portion 8 have the same skeleton, the adhesion of the tube 7 to the resin coating portion 8 can be particularly effectively improved.

[0063] The content of the thermoplastic elastomer in the constituent material of the tube 7 is preferably 20% by mass or more from the viewpoint of obtaining a sufficient effect of improving adhesion. Further, it is preferably 30% by mass or more. On the other hand, from the viewpoint of ensuring the manufacturability of the tube 7, the content of the thermoplastic elastomer is preferably suppressed to 40% by mass or less.

[0064] Both the acid-modified resin and the thermoplastic elastomer have the effect of improving the adhesion of the pipe 7 to the insulating coating 4 and the resin coating 8, especially the resin coating 8, and the effect of improving the adhesion is exerted as long as at least one of them is contained in the constituent material of the pipe 7. However, if at least the acid-modified resin is contained, a high effect of improving the adhesion of the pipe 7 is obtained even if it is contained in a relatively small amount, which is preferred. Furthermore, the embodiment in which the pipe 7 contains both the acid-modified resin and the thermoplastic elastomer is most preferred. In this case, a particularly high effect of improving the adhesion of the pipe 7 is obtained by the contribution of both the acid-modified resin and the thermoplastic elastomer. It is particularly preferred that the total content of the acid-modified resin and the thermoplastic resin in the constituent material of the pipe 7 is 30% by mass or more and 45% by mass or less.

[0065] The constituent material of the pipe 7 may contain polymer components other than the above-mentioned cross-linked polyolefin resin, acid-modified resin, and thermoplastic elastomer, but it is preferable to suppress the content to be less than these resins in a manner not to impair the characteristics of these resins. Preferably, the polymer material constituting the pipe 7 does not contain polymer components other than the cross-linked polyolefin resin, acid-modified resin, and thermoplastic elastomer. In addition, the constituent material of the pipe 7 may also contain additives as appropriate in addition to the polymer material. Examples of the additives include flame retardants, fillers, colorants, and the like.

[0066] The wall thickness of the pipe 7 is not particularly limited, but is preferably set to 50 μm or more, and further 100 μm or more, from the viewpoint of improving the effect of improving the waterproof property and sufficiently following the thermal expansion difference between the insulating coating layer 4 and the resin coating 8. On the other hand, from the viewpoint of suppressing excessive enlargement of the waterproof part of the electric wire with terminal 1, the wall thickness of the pipe 7 is preferably suppressed to 2 mm or less, and further 1 mm or less. It should be noted that the wall thickness described here refers to the wall thickness after the pipe is thermally shrunk.

[0067] As described above, in the electric wire with terminal 1 according to the present embodiment, the pipe 7 is arranged between the resin coating 8 covering the region including the electrical connection portion 6a and the insulating coating 4 of the insulated wire 2, and the pipe 7 exhibits adhesiveness to the insulating coating 4 and the resin coating 8. Thus, the resin coating 8 is bonded to the insulated wire 2 via the pipe 7. Since the constituent material of the pipe 7 contains at least one of an acid-modified resin and a thermoplastic elastomer in addition to the cross-linked polyolefin resin, the adhesiveness of the pipe 7 is improved, and particularly, the adhesiveness to the resin coating 8 is high. Since the pipe 7 has high adhesiveness, it is possible to suppress the intrusion of liquids such as water from the region between the resin coating 8 and the insulating coating 4 toward the electrical connection portion 6a. By protecting the electrical connection portion 6a from contact with electrolytes such as water, electrical problems such as short circuits and corrosion of metal materials are suppressed in the electrical connection portion 6a, and good electrical connection is maintained for a long time in the electrical connection portion 6a. Since the tube 7 is a single-layer cylindrical member with high adhesiveness, it is not necessary to use a liquid adhesive for the purpose of improving waterproofness. By using the tube 7, unlike a liquid adhesive, it is possible to easily and uniformly arrange a resin material of sufficient thickness at a predetermined position of the wire 1 with a terminal.

[0068] In addition, in the pipe material 7, as described above, from the viewpoint of ensuring the manufacturability in the manufacturing process involving extrusion molding and diameter expansion, the contents of the acid-modified resin and the thermoplastic elastomer are preferably suppressed to 40% by mass or less. As an index of the manufacturability of the pipe material 7, the elongation at break of the constituent material of the pipe material 7 can be used. Specifically, the constituent material of the pipe material 7 preferably has an elongation at break of 150% or more, and further 300% or more. The elongation at break can be evaluated by a tensile test in accordance with JIS K7161.

[0069] <Method for manufacturing electric wire with terminal>

[0070] Finally, the manufacturing method of the electric wire 1 with a terminal involved in the present embodiment is described. First, the manufacturing method of the pipe 7 is described. When making the pipe 7, first, at least one of a polyolefin resin, an acid-modified resin and a thermoplastic resin (various additives are also added as needed) is mixed to prepare a resin composition. Then, the resin composition is extruded into a cylindrical shape. The obtained cylindrical body is cross-linked by electron beam irradiation, etc., so as to obtain the pipe 7. In the case where the pipe 7 is constituted as a heat shrinkable tube, it is extruded into a small diameter, cross-linked by electron beam irradiation, etc., and then expanded while heating, and then cooled. In this way, the shape before the expansion is memorized, and the pipe 7 obtains heat shrinkability. Regarding the inner diameter of the heat shrinkable tube, it is smaller than the outer diameter of the insulated wire 2 in the state before the expansion, and it can be expanded to be larger than the outer diameter of the insulated wire 2 by the expansion.

[0071] When manufacturing the electric wire 1 with a terminal, first, the electric wire portion 6 is manufactured. That is, the barrel portions 52 and 53 of the terminal fittings 5 ​​are caulked and fixed at the ends of the insulated electric wires 2 from which the insulating coating 4 has been stripped. Thus, a structure in which the electric wire conductor 3 and the terminal fittings 5 ​​are connected at the electrical connection portion 6a is obtained. It should be noted that, depending on the specific structure of the terminal fittings 5, the connection between the electric wire conductor 3 and the terminal fittings 5 ​​may be performed by ultrasonic welding, soldering, etc. instead of caulked fixing. In either case, before or after the terminal fittings 5 ​​are fixed to the insulated electric wire 2, the insulated electric wire 2 is inserted into the hollow portion of the pipe 7 cut to the required length, thereby arranging the pipe 7 on the outer periphery of the insulated electric wire 2.

[0072] Next, the pipe 7 is heated while being positioned at a predetermined position near the end of the insulated wire 2. When the pipe 7 is a heat shrinkable tube, the pipe 7 shrinks by heating and adheres to the outer periphery of the insulated wire 2. At the same time, the constituent material of the inner peripheral surface of the pipe 7 is welded to the insulating coating 4 by heating, so that the pipe 7 is bonded to the insulating coating 4. The heating of the pipe 7 can be performed by ultrasonic welding, vibration welding, high-frequency welding, laser welding, infrared welding, friction welding, hot plate welding, hot air welding, etc.

[0073] Furthermore, the wire portion 6 to which the pipe 7 is installed is coated with a predetermined portion including the electrical connection portion 6a to form a resin coating portion 8. The resin coating portion 8 can be formed by arranging a molten resin material at a predetermined portion and solidifying it. The arrangement of the resin material can be suitably implemented by molding. That is, after a mold having a cavity that matches the shape of the resin coating portion 8 to be formed accommodates an area of ​​the wire portion 6 including the electrical connection portion 6a and a portion to which the pipe 7 is installed, molten resin material is injected into the mold. By solidifying the resin material, a resin coating portion 8 constituting a molded part can be obtained. When forming the resin coating portion 8, the high-temperature molten resin contacts the outer peripheral surface of the pipe 7, and the constituent material of the outer peripheral surface of the pipe 7 is welded to the inner peripheral surface of the resin coating portion 8 by the heat, and the pipe 7 is bonded to the resin coating portion 8.

[0074] Example

[0075] The following are examples. Here, the waterproofness and other properties of the wire with terminal were evaluated while changing the constituent material of the pipe. It should be noted that the present invention is not limited to these examples. In this example, the evaluation of the properties was performed at room temperature and in the atmosphere.

[0076] [Preparation of samples]

[0077] For samples A1 to A27 and B1 to B9, heat-shrinkable tubes containing the components listed in Tables 1 to 3 were prepared respectively. When making the tubes, the resin composition obtained by mixing the components in Table 1 was extruded into a small-diameter cylinder, and after cross-linking based on electron beam irradiation, the diameter was expanded while heating. In the expanded state, the outer diameter of the heat-shrinkable tube was 6.4 mm and the wall thickness was 0.5 mm. It should be noted that for the samples using non-cross-linked PE as the material of group a, the resin composition was directly extruded into the above-mentioned dimensions without electron beam irradiation. In addition, for the samples using silane cross-linked PE, silane cross-linking was also implemented after the resin composition was extruded into the above-mentioned dimensions. Electron beam cross-linked PE1 and electron beam cross-linked PE2 are both electron beam cross-linked polyethylene, but the degree of cross-linking is different from each other, and the degree of cross-linking of electron beam cross-linked PE2 is lower.

[0078] As an insulated wire, an electric wire in which an insulating coating layer composed of a cross-linked polyethylene resin is formed on the outer periphery of a conductor composed of a stranded wire of a copper alloy is prepared. The outer diameter of the insulated wire is 5.3 mm. After removing the insulating coating layer at the end of the insulated wire to expose the wire conductor, a convex crimping terminal fitting composed of tin-plated brass commonly used for automobiles is crimped and fixed to the end of the wire to obtain a wire section. In addition, a pipe with a length of 10 mm is arranged on the outer periphery near the end of the insulated wire constituting the wire section.

[0079] Next, the sample was placed in a thermostatic chamber to heat the pipe. At this time, for the sample with heat shrinkage, the pipe shrank and adhered to the outer circumference of the insulated wire. After heat shrinkage, the wall thickness of the pipe became 0.6 mm.

[0080] Finally, the resin coating is formed by molding. PBT or nylon 6T (PA6T) is used as the constituent material of the resin coating. Figure 1 , 2 As shown, the resin coating portion is formed so as to cover the entire range of the electrical connection portion between the insulated wire and the terminal fitting and to cover the entire range of the outer peripheral surface of the pipe material.

[0081] [Evaluation of characteristics]

[0082] (1) Waterproof

[0083] The waterproofness of the electric wires with terminals made of various pipes described above was evaluated by an air leakage test. That is, the entire portion of the electric wire with terminals provided with a resin coating was immersed in water, and air pressure was applied at a predetermined pressure from the end of the wire on the side not connected to the terminal fitting. Whether air leakage occurred was confirmed by visually confirming the generation of bubbles from the interface between the insulating coating layer and the resin coating of the insulated wire when the air pressure was applied. The test was performed while changing the applied air pressure, and the waterproofness was evaluated using the upper limit of the air pressure at which no air leakage occurred.

[0084] The waterproofness was evaluated based on the following criteria. Very high water resistance (A+): When the upper limit of air pressure is 200 kPa or more High waterproofness (A): When the upper limit of air pressure is 100 kPa or more and less than 200 kPa Low water resistance (B): When the upper limit of air pressure is 50 kPa or more and less than 100 kPa Very low water resistance (B-): When the upper limit of air pressure is less than 50 kPa

[0085] (2) Heat shrinkage of pipes

[0086] Whether a tube disposed on the outer periphery of an insulated wire has heat shrinkage (A) or not (B) is determined based on whether the tube shrinks when the tube is heated in a manufacturing process of a wire with a terminal.

[0087] (3) Manufacturability of pipes

[0088] As an index indicating the manufacturability of the pipe material, the elongation at break of the constituent material of the pipe material was measured. This is because if the constituent material of the pipe material is brittle and has a low elongation at break, damage such as breakage will occur during extrusion molding and diameter expansion, and the manufacturability of the pipe material will decrease. The elongation at break was measured by a tensile test in accordance with JIS K 7161.

[0089] Using the measured elongation at break value, the manufacturability of the pipe material was evaluated as follows. Very high manufacturability (A+): elongation at break is more than 300% High manufacturability (A): Elongation at break is 150% or more and less than 300% Low manufacturability (B): elongation at break less than 150%

[0090] [Evaluation method]

[0091] In the following Tables 1 to 3, the evaluation results of each property are shown together with the component composition of the pipe material and the constituent material of the resin coating portion for samples A1 to A27 and B1 to B9. Regarding the component composition of the pipe material, the content of each component in the resin component is expressed in mass %. Regarding the resin coating portion, a black circle is marked for the one of PBT and PA6T used as the constituent material.

[0092] [Table 1]

[0093] [Table 2]

[0094] [Table 3]

[0095] The pipes of samples A1 to A27 described in Tables 1 and 2 above all contain at least one of an acid-modified resin (group b) and a thermoplastic elastomer (group c) in addition to the cross-linked polyolefin resin (group a), the acid-modified resin (group b) being 5% to 40% by mass in the resin component, and the thermoplastic elastomer (group c) being 20% ​​to 40% by mass in the resin component. Since the pipe contains the cross-linked polyolefin resin, the pipe has heat shrinkage (A) in all the samples. In addition, high waterproofness (A or A+) and high pipe manufacturability (A or A+) are obtained in accordance with the inclusion of at least one of the acid-modified resin and the thermoplastic elastomer in the above-mentioned prescribed amount.

[0096] On the other hand, in the samples B1 to B9 described in Table 3, since the pipe does not have a component composition containing a cross-linked polyolefin resin and at least one of the above-mentioned specified amount of acid-modified resin and thermoplastic elastomer, at least one of the characteristics of waterproofness, heat shrinkage of the pipe, and manufacturability of the pipe is not fully satisfied. In samples B3 and B6, since a non-cross-linked resin is used as the resin of group a, the pipe does not contain a cross-linked resin, so the pipe does not have heat shrinkage (B). In sample B7, a cross-linked silicone resin is used as the cross-linked resin instead of a polyolefin cross-linked resin. Although the pipe exhibits heat shrinkage (A), the evaluation result is that the waterproofness is very low (B-). This is considered to be because the cross-linked silicone resin does not have high adhesion to the insulating coating of the insulated wire.

[0097] In samples B1 to B5, the evaluation result of extremely low water resistance (B-) corresponds to the fact that the pipe material does not contain any of the acid-modified resin and the thermoplastic elastomer. In sample B8, although the pipe material contains the acid-modified resin, the amount thereof is less than 10% by mass, and the water resistance is low (B). In sample B9, the pipe material contains more than 40% by mass of the acid-modified resin, and the manufacturability of the pipe material is low (B).

[0098] Here, samples A1 to A27 are compared with each other. First, regarding the crosslinked polyolefin resin of group a, it can be confirmed from the comparison between sample A3 and sample A4 that the same waterproofness (A) and pipe manufacturability (A+) are obtained regardless of whether the crosslinking is performed by electron beam crosslinking or silane crosslinking. In addition, from the comparison between sample A2 and sample A7, in sample A2 using a resin with a high crosslinking density, namely, electron beam crosslinked PE1, particularly high manufacturability is obtained.

[0099] In samples A1 to A11, the pipe material contains only one of the acid-modified resin and the thermoplastic elastomer, while in samples A12 to A27, both of them are contained. In samples A1 to A11, the water resistance is only rated as high (A), while in most of samples A12 to A27, very high water resistance (A+) is obtained. Therefore, it can be said that the use of the acid-modified resin and the thermoplastic elastomer in the pipe material simultaneously has a high effect on improving the water resistance.

[0100] From the comparison between Sample A1 and Sample A2, it can be confirmed that no matter which of acid-modified SEBS and acid-modified PP is used as the acid-modified resin, an effect on improving water resistance can be obtained. As for the thermoplastic elastomer, from the evaluation results of the water resistance of each sample, it can be confirmed that no matter which of polyester and polyamide is used, an effect on improving water resistance can be obtained. However, in Samples A12 to A15 in which the thermoplastic elastomer contained in the pipe and the resin material constituting the resin coating have a polyester skeleton and Samples A24 to A27 in which they both have a polyamide skeleton, a tendency to obtain higher water resistance can be seen compared with Samples A16 to A23 in which the thermoplastic elastomer contained in the pipe and the resin material constituting the resin coating have different skeletons. Therefore, it can be said that by using a thermoplastic elastomer having the same skeleton as the resin material constituting the resin coating as the thermoplastic elastomer added to the pipe, a high effect on improving water resistance can be obtained.

[0101] As mentioned above, although embodiment of this disclosure was demonstrated in detail, this invention is not limited to the said embodiment at all, Various changes are possible within the range which does not deviate from the summary of this invention.

[0102] Description of symbols

[0103] 1 Wire with terminal

[0104] 2 Wires

[0105] 3 Conductors

[0106] 3a The front end of the conductor

[0107] 4 Insulation coating

[0108] 5 Terminal accessories

[0109] 51 Terminal connection part

[0110] 51a Bolt insertion hole

[0111] 52 First barrel

[0112] 53 Second tube

[0113] 6. Wire Department

[0114] 6a Electrical connection

[0115] 7 Pipe

[0116] 8 Resin coating

Claims

1. An electric wire with a terminal, comprising: An electric wire portion obtained by electrically connecting a terminal fitting and an insulated electric wire formed by covering the outer circumference of a conductor with an insulating coating layer at an electric connection portion; a pipe covering the outer circumference of the insulating coating layer at a portion along the axial direction of the insulated wire; and The resin coating portion is formed so as to cover a portion of the electric wire portion including the electrical connection portion and to be in contact with at least a portion of the outer peripheral surface of the pipe. The pipe is constituted as a single-layer cylindrical member, and the pipe comprises: Cross-linked polyolefin resins; and At least one of an acid-modified resin and a thermoplastic elastomer, wherein the acid-modified resin accounts for 5% to 40% by mass in the resin component, and the thermoplastic elastomer accounts for 20% to 40% by mass in the resin component.

2. The electric wire with a terminal according to claim 1, wherein The pipe comprises both the acid-modified resin and the thermoplastic elastomer.

3. The electric wire with a terminal according to claim 1, wherein The thermoplastic elastomer and the resin material constituting the resin coating portion have the same skeleton.

4. The electric wire with a terminal according to claim 1 or 3, wherein: The thermoplastic elastomer includes at least one of a polyester-based elastomer and a polyamide-based elastomer.

5. The electric wire with a terminal according to claim 1 or 2, wherein: The acid-modified resin includes an acid-modified polyolefin resin.

6. The electric wire with a terminal according to claim 1 or 2, wherein: The resin coating portion covers the entire outer peripheral surface of the pipe.

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