Resin tube, cable, and wire harness

Abstract

The invention provides a resin tube, a cable, and a wire harness. The invention provides a resin tube which is not easy to wear even in contact with other members, and a cable and a wire harness using the resin tube. The resin tube (1) is a hollow tubular resin tube (1) having a hollow portion (1a) along the longitudinal direction, and is configured from a resin composition in which particles comprising a crosslinked fluororesin are dispersed in a base resin.

Description

Technical Field

[0001] The present invention relates to a resin pipe, a cable and a wire harness. Background Art

[0002] Resin tubes used in industrial robots and the like are used, for example, as a part of a multi-core cable wired on a SCARA robot (for example, see Patent Document 1). In addition, in industrial robots used in production lines for welding and assembly of automobiles, resin tubes are used as a part of a wiring harness that bundles a plurality of cables.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-170751 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The outer surface of the resin tube may come into contact with other members due to the movement of the cable or the like, and the contact portion may be worn. Therefore, there is a demand to reduce the wear of the contact portion.

[0008] Therefore, an object of the present invention is to provide a resin tube that is not easily worn even when it comes into contact with other members, and a cable and a wire harness using the resin tube.

[0009] Methods for solving problems

[0010] The present invention aims to solve the above-mentioned problems and provides a resin tube having a hollow cylindrical shape and a hollow portion in the longitudinal direction, and is composed of a resin composition in which particles composed of a cross-linked fluororesin are dispersed in a base resin.

[0011] In order to solve the above-mentioned problems, the present invention provides a cable comprising one or more of the above-mentioned resin tubes, wherein the one or more resin tubes and one or more insulated wires are covered together with a sheath.

[0012] In order to solve the above-mentioned problems, the present invention provides a wire harness including one or more of the above-mentioned resin tubes and formed by bundling the one or more resin tubes and one or more insulated wires.

[0013] Effects of the Invention

[0014] According to the present invention, it is possible to provide a resin tube that is less likely to be worn even when it comes into contact with other members, and a cable and a wire harness using the resin tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a cross-sectional view and a partially enlarged view showing a cross section perpendicular to the longitudinal direction of a resin tube according to an embodiment of the present invention.

[0016] Figure 2 This is a flowchart showing the steps in manufacturing the resin tube.

[0017] Figure 3 This is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a multi-core cable as a cable according to one embodiment of the present invention.

[0018] Figure 4 This is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a flat cable as a cable according to one embodiment of the present invention.

[0019] Figure 5 This is a schematic configuration diagram of a wire harness according to an embodiment of the present invention.

[0020] Figure 6 This is a cross-sectional view showing a cross section perpendicular to the longitudinal direction when a resin tube is used as a protective tube.

[0021] Explanation of symbols

[0022] 1 ... resin tube, 1a ... hollow portion, 2 ... outer surface, 3 ... inner surface, 4 ... insulated wire, 10 ... cable, 13 ... wiring harness. DETAILED DESCRIPTION

[0023] [Implementation Method]

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0025] Figure 1 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of the resin tube 1 of the present embodiment and a partially enlarged view thereof. Figure 1 As shown, the resin tube 1 is a hollow cylindrical resin tube having a hollow portion 1 a along the longitudinal direction.

[0026] The resin tube 1 of the present embodiment is made of a resin composition in which particles made of a cross-linked fluororesin are dispersed in a base resin. The particles made of the cross-linked fluororesin are made of a fluororesin having a cross-linked structure that is cross-linked by irradiation with ionizing radiation.

[0027] Cross-linked fluororesin is a non-melting resin that does not show melt fluidity even when heated to a temperature above its melting point, and has the characteristics of being difficult to agglomerate and having very high dispersibility. Therefore, by using particles composed of a fluororesin having a cross-linked structure, it is easy to evenly disperse the particles in the base resin. Moreover, by evenly dispersing the particles composed of the non-melting cross-linked fluororesin in the base resin, fine and uniform concavities and convexities can be formed on the surface of the resin tube 1 after molding. As a result, the wear of the resin tube 1 when it contacts other components can be suppressed, and a resin tube 1 that is not easy to wear can be realized.

[0028] In the resin tube 1, at least the arithmetic mean roughness Ra of the outer surface 2 (outer peripheral surface) thereof can be 1 μm or more and 10 μm or less. Thus, the outer diameter of the resin tube 1 can be suppressed from changing, and the wear of the resin tube 1 when it contacts other components can be suppressed, and the wear resistance is improved. In addition, water and dirt are difficult to adhere to the outer surface 2 of the resin tube 1, and even if they adhere, they can be easily wiped off.

[0029] In addition, the resin tube 1 may have fine irregularities on its inner surface 3 (inner circumferential surface), and the arithmetic mean roughness Ra of the inner surface 3 may be 1 μm or more and 10 μm or less. Thus, when liquid or the like passes through the hollow portion 1a of the resin tube 1, it is difficult for liquid or the like to adhere to the inner surface 3 of the resin tube 1. In addition, when a cable or the like is passed through the hollow portion 1a of the resin tube 1, wear of the resin tube 1 due to friction with the cable or the like can be suppressed.

[0030] The particles composed of cross-linked fluororesin are formed by irradiating uncross-linked fluororesin formed into a sheet shape with ionizing radiation to cross-link the sheet, and then crushing the sheet into particles having a particle size of 25 μm or less, more preferably 20 μm or less. That is, the particle size of the particles composed of cross-linked fluororesin used in the present embodiment is 25 μm or less, more preferably 20 μm or less. It should be noted that if particles having a particle size greater than 25 μm are included, the outer diameter of the resin tube 1 changes too much, which is not preferred.

[0031] The uncrosslinked fluororesin used for crosslinking the fluororesin is composed of, for example, tetrafluoroethylene polymer (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and tetrafluoroethylene / ethylene copolymer (ETFE). In the present embodiment, PTFE is used as the fluororesin used in the uncrosslinked fluororesin. When the uncrosslinked fluororesin is crosslinked, the crosslinking treatment may be performed by irradiating ionizing radiation at a temperature higher than the melting point of the uncrosslinked fluororesin in an inactive gas atmosphere with an oxygen concentration of 100 torr or less (more preferably 10 torr or less).

[0032] The content of perfluorinated compounds (PFCA) with 8 carbon atoms in the cross-linked fluororesin can be 10 ppb or less. In addition, the content of each PFCA with 9 to 21 carbon atoms in the cross-linked fluororesin can be 25 ppb or less. In the present embodiment, the content of PFCA, which is known as an environmental load substance, is reduced by performing a heat treatment under prescribed conditions after cross-linking. Thus, a resin tube 1 with less load on the environment can be achieved. As a heat treatment, for example, it can be carried out in a temperature range that is higher than the melting point of the cross-linked fluororesin and is 100°C or less than the melting point of the cross-linked fluororesin.

[0033] As the base resin for the resin tube 1, nylon, polyurethane, fluororesin such as PTFE, engineering plastics such as PEEK (polyetheretherketone), polyimide, polyethylene, polypropylene, etc. can be used. For example, when ETFE is used as the base resin, the heat resistance of the resin tube 1 can be improved by including particles composed of a cross-linked fluororesin.

[0034] From the viewpoint of reducing the environmental load, as the base resin for the resin tube 1, a non-fluorine resin such as nylon may be used instead of a fluororesin. As in the present embodiment, by dispersing particles composed of a cross-linked fluororesin in the base resin, sufficient wear resistance and the like can be achieved even without using a fluororesin as the base resin. For example, when nylon is used as the base resin, by including particles composed of a cross-linked fluororesin, wear resistance equivalent to that of ETFE can be achieved. Therefore, as a substitute for ETFE, a resin composition in which particles composed of a cross-linked fluororesin are dispersed in nylon can be used for the resin tube 1, and the amount of fluororesin used can be reduced, further reducing the load on the environment.

[0035] The resin tube 1 may contain particles consisting of a cross-linked fluororesin in an amount of not less than 5% by mass and not more than 20% by mass. That is, the mass ratio of the base resin to the particles consisting of the cross-linked fluororesin (base resin: particles consisting of the cross-linked fluororesin) may be in the range of 95:5 to 80:20. When the particles consisting of the cross-linked fluororesin are less than 5% by mass, the effect of improving the wear resistance cannot be fully obtained. In addition, when the particles consisting of the cross-linked fluororesin are more than 20% by mass, the fluidity decreases and the extrusion molding of the resin tube 1 becomes difficult. By forming resin tubes 1 having different contents of particles consisting of the cross-linked fluororesin, resin tubes 1 having different wear resistance can be manufactured, and grading corresponding to the wear resistance can also be performed.

[0036] The resin tube 1 preferably has a thickness (difference between inner diameter and outer diameter) of (average thickness - 0.01 mm) or more and (average thickness + 0.01 mm) or less in the entire circumference, and a flatness (minimum outer diameter / maximum outer diameter) of 0.9 or more and 1.0 or less. Thus, when the outer surface 2 of the resin tube 1 contacts other components, point contact is easily achieved, so that the wear resistance is further improved.

[0037] (Manufacturing method of resin tube 1)

[0038] Figure 2 1 is a flow chart showing the steps for manufacturing the resin tube 1. Figure 2 As shown, first, in step S1, a cross-linked fluororesin manufacturing process is performed. In the cross-linked fluororesin manufacturing process, a sheet (such as a PTFE sheet) composed of uncross-linked fluororesin is irradiated with ionizing radiation to produce a sheet composed of a cross-linked fluororesin, and the sheet is crushed to form particles. At this time, the crushing can be performed in a manner such that the average particle size is less than 25 μm (preferably less than 20 μm). Thus, particles composed of a cross-linked fluororesin are obtained. Then, the above-mentioned heat treatment can be applied to the obtained particles composed of the cross-linked fluororesin, thereby reducing perfluorinated compounds and reducing the load on the environment.

[0039] Then, in step S2, a molding material manufacturing process is performed. In the molding material manufacturing process, a base resin and particles consisting of a cross-linked fluororesin are put into a mixer such as a twin-shaft mixer, and after heating and mixing them, the mixed resin is extruded from the mixer. Then, the extruded resin composition is molded with a granulator or the like, thereby manufacturing a molding material (a material for manufacturing a molded body) consisting of particles and sheets. It should be noted that in order to make the resin tube 1 having fine concave-convex shapes on the outer surface 2 and the inner surface 3 easy to mold, the molding material is preferably particles. In addition, the cooling of the resin composition can be carried out just after being extruded from the mixer, or just after being formed into particles, etc. The resin temperature during mixing in the molding material manufacturing process can be set to be above the melting point of the base resin used (more preferably above the melting point of the base resin + 10°C) and below the melting point of the base resin + 50°.

[0040] After that, a molding process is performed in step S3. In the molding process, a molding material composed of particles or the like is put into an extruder for extrusion molding, thereby forming a resin tube 1. In the present embodiment, after the resin composition is extruded and molded in a manner that covers the surface of a linear core material (e.g., a single-wire conductor) composed of metal or the like, the core material is pulled out to form a resin tube 1. Thus, a resin tube 1 having a constant thickness (difference between the inner diameter and the outer diameter), a cross-sectional shape close to a circular shape, and a high concentricity is obtained. It should be noted that the resin temperature during extrusion molding is the same as the resin temperature during mixing in the molding material manufacturing process, and can be above the melting point of the base resin used (more preferably above the melting point of the base resin + 10°C) and below the melting point of the base resin + 50°. In addition, extrusion molding can be solid extrusion or tube extrusion. Since fine concave-convex shapes are formed on the inner surface 3 of the resin tube 1 in the present embodiment, the adhesion to the core material can be reduced, and the core material can be easily pulled out. It should be noted that it can also be cut to a desired length (e.g., 1m, 2m, etc.) before pulling out the core material.

[0041] It should be noted that in the present embodiment, the core material is used in the molding process to form the resin tube 1, but the present invention is not limited thereto, and the resin tube 1 may be formed by extruding the resin composition without using a core material. In this case, in order to suppress the uneven thickness caused by the influence of gravity, it is preferred to use a vertical extruder that performs extrusion molding in a downward direction in the vertical direction.

[0042] (cable 10)

[0043] Next, the cable 10 of this embodiment is described. The cable 10 is, for example, a movable part cable used in a movable part of an industrial robot or the like. The cable 10 includes one or more resin tubes 1 of this embodiment, and may be composed of one or more resin tubes 1 and one or more insulated wires 4 (or cables 5 including one or more insulated wires 4) covered with a sheath, and may have various structures.

[0044] For example, the cable 10 may be a multi-core cable 11 . Figure 3 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of the multi-core cable 11. The multi-core cable 11 includes a cable core 11a formed by twisting a plurality of (here, two) cables 5 and two resin tubes 1, a belt member 11b wound in a spiral shape around the cable core 11a, a shielding layer 11c provided so as to cover the belt member 11b, and a sheath 11d provided so as to cover the shielding layer 11c. The resin tube 1 is provided as a member for making the cross section of the cable core 11a substantially circular or as a member for conveying air or water.

[0045] Since the resin tube 1 has fine irregularities on its outer surface 2, even if the multi-core cable 11 is repeatedly subjected to bending, twisting and other actions, wear (wear of the resin tube 1 and wear of the member rubbing against the resin tube 1) caused by friction with the adjacent cable 5 and the belt member 11b can be suppressed. Therefore, the resistance to repeated bending, twisting, U-shaped sliding and other actions can be improved. The cable 5 is formed by twisting 6 insulated wires 4 coated with an insulator 42 around a conductor 41, spirally winding a belt member 51 around it, and covering the belt member 51 with a sheath 52. However, the specific structure of the cable 5 is not limited to this, and the insulated wire 4 can also be used instead of the cable 5.

[0046] The belt member 11b is made of, for example, a resin belt, and is wound in a spiral shape so that a portion of the belt is overlapped in the width direction. The shielding layer 11c is made of a braided shielding member made by braiding a plurality of metal wires, a transversely wound shielding member made by winding a plurality of metal wires in a spiral shape, a plated shielding member made by plating a metal such as copper, or a combination of a plurality of these. It should be noted that the shielding layer 11c can be omitted depending on the application. The sheath 11d is made of, for example, a polyvinyl chloride resin.

[0047] Alternatively, the cable 10 may be a flat cable 12 . Figure 4 : is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of the flat cable 12. The flat cable 12 is formed by arranging a plurality of (here, 4) cables 5 and a plurality of (here, 2) resin tubes 1 in parallel in the width direction, and fusing the sheaths 12a of the adjacent cables 5 to each other. In the flat cable 12, the resin tube 1 is arranged so as to sandwich the four cables 5. In addition, in the flat cable 12, the sheath 12a is covered so as to cover the periphery of the resin tube 1, and the sheath 12a is fused to the sheath 12a of the adjacent cable 5, so that the resin tube 1 is connected to the cable 5 via the sheath 12a. It should be noted that in the example of the figure, only cables 5 of the same structure are used, but cables 5 of different structures may also be included. In addition, in the example of the figure, the case where the sheaths 12a are fused to each other is shown, but it is not limited to this, and the flat cable 12 may be formed by providing a cover so as to cover the periphery of the cables 5 and the resin tube 1 arranged in parallel. In addition, the cables 5 arranged in parallel and the resin tube 1 covered by the sheath 12a may also be bonded.

[0048] (Wire harness 13 and other uses)

[0049] In addition, the resin tube 1 may be assembled into a wiring harness 13 (also referred to as a wiring harness) used for wiring of an industrial robot or the like. Figure 5The wiring harness 13 shown is formed by bundling a plurality of cables 5 and a resin tube 1 with a bundling member 13a. Since the resin tube 1 has fine irregularities on the outer surface 2, it is not easy to be worn even if it rubs against the cable 5 and surrounding members. It should be noted that the cable 5 includes one or more insulated wires 4. Moreover, the insulated wires 4 can also be used instead of the cable 5. That is, the wiring harness 13 can be formed by bundling one or more resin tubes 1 and one or more insulated wires 4 (or cables 5 including the insulated wires 4).

[0050] And, if Figure 6 As shown in FIG. 1 , the resin tube 1 can also be used as a protective tube that covers the periphery of a plurality of cables 5. In this case, the plurality of cables 5 are inserted into the hollow portion 1a of the resin tube 1. Since fine concavo-convex shapes are formed on the inner surface 3 of the resin tube 1, even if the cables 5 inserted into the hollow portion 1a rub against the inner surface 3, the cables 5 are not easily worn. In addition, since fine concavo-convex shapes are also formed on the outer surface 2 of the resin tube 1, liquids such as water and paint and dirt are difficult to adhere to, and even if they adhere, they can be easily wiped off.

[0051] (Functions and Effects of Implementation Methods)

[0052] As described above, the resin tube 1 of the present embodiment is composed of a resin composition in which particles composed of a cross-linked fluororesin are dispersed in a base resin. As a result, the particles composed of the cross-linked fluororesin are non-fusible, have low cohesiveness, and are easily dispersed. Therefore, the particles composed of the cross-linked fluororesin can be uniformly dispersed in the base resin, and fine concavo-convex shapes are uniformly formed on the surface of the resin tube 1, which is not easily worn even when in contact with other components.

[0053] Furthermore, by forming fine irregularities on the outer surface 2 and the inner surface 3 of the resin tube 1, liquids such as water and dirt are less likely to adhere to the outer surface 2 and the inner surface 3 of the resin tube 1. Furthermore, even if dirt or the like adheres to the outer surface 2 of the resin tube 1, the dirt can be easily wiped off.

[0054] Furthermore, according to the present embodiment, even if a non-fluorine resin is used instead of a fluorine resin in the base resin, wear resistance and the like equivalent to that of a case where a fluorine resin is used can be achieved. Therefore, the amount of fluorine resin used in the resin tube 1 can be reduced, further reducing the load on the environment. In addition, by reducing the amount of fluorine resin used in the resin tube 1, costs can also be reduced. Furthermore, for example, when a fluorine resin such as PTFE is used in the base resin, it is hard and weak to impact, but by using a non-fluorine resin such as nylon in the base resin, the flexibility can be improved, and the resistance to impact can also be improved.

[0055] (Variation Example)

[0056] In the above embodiment, the case where the resin tube 1 has a single-layer structure is described, but the resin tube 1 may also have a multi-layer structure. In this case, at least one or more layers of the layers constituting the resin tube 1 may be composed of a resin composition in which particles composed of a cross-linked fluororesin are dispersed in a base resin. In addition, the layer formed of the resin composition in which particles composed of a cross-linked fluororesin are dispersed in a base resin may constitute at least one of the outer surface 2 or the inner surface 3 of the resin tube 1.

[0057] (Summary of Implementation Methods)

[0058] Next, the technical ideas grasped from the above-described embodiments are described by referring to the symbols in the embodiments. However, the symbols in the following description do not limit the constituent elements in the claims to the members specifically shown in the embodiments.

[0059] [1] A resin tube (1) is a hollow cylindrical resin tube (1) having a hollow portion (1a) along the longitudinal direction, and is composed of a resin composition in which particles composed of a cross-linked fluororesin are dispersed in a base resin.

[0060] [2] The resin tube (1) according to [1], comprising 10% by mass or more and 20% by mass or less of the particles composed of the cross-linked fluororesin.

[0061] [3] The resin tube (1) according to [1], wherein at least the outer surface (2) thereof has an arithmetic mean roughness Ra of 1 μm or more and 10 μm or less.

[0062] [4] The resin tube (1) according to [1], wherein the content of the perfluoro compound having 8 carbon atoms in the cross-linked fluororesin is 10 ppb or less, and the content of each perfluoro compound having 9 to 21 carbon atoms is 25 ppb or less.

[0063] [5] The resin tube (1) according to [1], wherein the base resin is composed of a non-fluorine resin.

[0064] [6] A cable (10) comprising one or more resin tubes (1) described in any one of [1] to [5], the cable being formed by covering the one or more resin tubes (1) and one or more insulated wires (4) together with a sheath (11a, 12a).

[0065] [7] A wire harness (13) comprising one or more resin tubes (1) according to any one of [1] to [5], and being formed by bundling the one or more resin tubes (1) and one or more insulated wires (4).

[0066] (Note)

[0067] The embodiments of the present invention are described above, but the embodiments described above do not limit the invention involved in the claims. In addition, it should be noted that all combinations of the features described in the embodiments are not necessary for solving the invention problems. In addition, the present invention can be implemented by appropriate deformation within the scope of its purpose.

Claims

1. A resin tube having a hollow cylindrical shape and having a hollow portion in a longitudinal direction, the resin tube being composed of a resin composition in which particles composed of a cross-linked fluororesin are dispersed in a base resin. 2 . The resin tube according to claim 1 , comprising 10% by mass or more and 20% by mass or less of the particles composed of the cross-linked fluororesin.

3. The resin tube according to claim 1, wherein At least the arithmetic mean roughness Ra of the outer surface is 1 μm or more and 10 μm or less.

4. The resin tube according to claim 1, wherein In the cross-linked fluororesin, the content of the perfluoro compound having 8 carbon atoms is 10 ppb or less, and the content of each perfluoro compound having 9 to 21 carbon atoms is 25 ppb or less.

5. The resin tube according to claim 1, wherein The base resin is composed of a non-fluorine resin. 6 . An electric cable comprising one or more resin tubes according to claim 1 , wherein the one or more resin tubes and one or more insulated wires are covered together with a sheath. 7 . A wire harness comprising one or more resin tubes according to claim 1 , wherein the wire harness is formed by bundling the one or more resin tubes and one or more insulated electric wires.

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