Resin tube, cable and harness

Abstract

To provide a resin tube that is resistant to wear even when it is in contact with other materials, and a cable and a harness using the resin tube.SOLUTION: A resin tube 1 is a hollow cylindrical resin tube 1 having a hollow part 1a along a longitudinal direction, and is made of a resin composition in which particles made of crosslinked fluororesin are dispersed in a base resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a resin tube, a cable, and a harness. [Background technology]

[0002] Resin tubes used in industrial robots and the like are used, for example, as part of a multi-core cable wired to a SCARA robot (see, for example, Patent Document 1). Also, in industrial robots used in manufacturing lines for welding automobiles and assembling parts, resin tubes are used as part of a harness bundling multiple cables together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-170751 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a cable or the like moves, the outer surface of the resin tube comes into contact with other members, and the contact portion is worn. Therefore, there is a demand for reducing the wear of the contact portion.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a resin tube that is resistant to wear even when it comes into contact with other members, and a cable and harness using the same. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides a hollow cylindrical resin tube having a hollow portion along the longitudinal direction, the resin tube being made of a resin composition in which particles made of cross-linked fluororesin are dispersed in a base resin.

[0007] In addition, in order to solve the above-mentioned problems, the present invention provides a cable comprising one or more of the above-mentioned resin tubes, and wherein the one or more resin tubes and one or more insulated electric wires are collectively covered with a sheath.

[0008] In addition, in order to solve the above-mentioned problems, the present invention provides a harness comprising one or more of the above-mentioned resin tubes and configured by bundling the one or more resin tubes and one or more insulated electric wires. Effect of the Invention

[0009] According to the present invention, it is possible to provide a resin tube that is resistant to wear even when it comes into contact with other members, and a cable and harness using the same. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a cross section perpendicular to a longitudinal direction of a resin tube according to an embodiment of the present invention, and an enlarged view of a portion thereof; [Diagram 2] FIG. 4 is a flow chart showing a procedure for manufacturing a resin tube. [Diagram 3] 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a multi-core cable according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a flat cable according to an embodiment of the present invention; [Diagram 5] 1 is a schematic configuration diagram of a harness according to an embodiment of the present invention; [Figure 6] 11 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction when a resin tube is used as a protective tube. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of a resin tube 1 according to the present embodiment, and an enlarged view of a part of the cross-sectional view. As shown in Fig. 1, the resin tube 1 is a hollow cylindrical resin tube having a hollow portion 1a along the longitudinal direction.

[0013] The resin tube 1 according to the present embodiment is made of a resin composition in which particles made of crosslinked fluororesin are dispersed in a base resin. The particles made of crosslinked fluororesin are made of fluororesin having a crosslinked structure that is crosslinked by irradiation with ionizing radiation.

[0014] Cross-linked fluororesin is a non-melt type resin that does not exhibit melt fluidity even when heated above its melting point, and has the characteristic of being difficult to aggregate and highly dispersible. Therefore, by using particles made of fluororesin with a cross-linked structure, it becomes easier to uniformly disperse the particles in the base resin. And by uniformly dispersing particles made of non-melt type cross-linked fluororesin in the base resin, it becomes possible to form fine and uniform irregularities on the surface of the resin tube 1 after molding. As a result, it becomes possible to suppress abrasion when the resin tube 1 comes into contact with other members, and it becomes possible to realize a resin tube 1 that is less prone to abrasion.

[0015] The resin tube 1 preferably has an arithmetic mean roughness Ra of at least its outer surface 2 (outer peripheral surface) of 1 μm or more and 10 μm or less. This can suppress abrasion when the resin tube 1 comes into contact with other members while suppressing the variation in the outer diameter of the resin tube 1, improving the abrasion resistance. In addition, water and dirt are less likely to adhere to the outer surface 2 of the resin tube 1, and even if they do adhere, they can be easily wiped off.

[0016] The resin tube 1 also preferably has fine irregularities on its inner surface 3 (inner circumferential surface), and the arithmetic mean roughness Ra of the inner surface 3 is preferably 1 μm or more and 10 μm or less. This makes it difficult for liquid or the like to adhere to the inner surface 3 of the resin tube 1 when passing the liquid through the hollow portion 1a of the resin tube 1. Furthermore, 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.

[0017] The particles made of crosslinked fluororesin are formed by irradiating uncrosslinked fluororesin formed into a sheet shape with ionizing radiation to crosslink it, and then pulverizing 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 made of crosslinked fluororesin used in this embodiment is 25 μm or less, more preferably 20 μm or less. Note that if particles having a particle size larger than 25 μm are included, the outer diameter fluctuation of the resin tube 1 becomes too large, which is not preferable.

[0018] The uncrosslinked fluororesin used for the crosslinked fluororesin may be, for example, a tetrafluoroethylene polymer (PTFE), a tetrafluoroethylene / hexafluoropropylene copolymer (FEP), or a tetrafluoroethylene / ethylene copolymer (ETFE). In this embodiment, PTFE is used as the fluororesin used for the uncrosslinked crosslinked fluororesin. When the uncrosslinked fluororesin is crosslinked, the crosslinking treatment may be performed by irradiating the fluororesin with ionizing radiation in an inert gas atmosphere with an oxygen concentration of 100 torr or less (more preferably 10 torr or less) at a temperature higher than the melting point of the uncrosslinked fluororesin.

[0019] The crosslinked fluororesin may have a content of 10 ppb or less of perfluoro compounds (PFCA) having 8 carbon atoms. The crosslinked fluororesin may have a content of 25 ppb or less of each of PFCAs having 9 to 21 carbon atoms. In this embodiment, the content of PFCAs, which are known as environmental load substances, is reduced by carrying out a heat treatment under predetermined conditions after crosslinking. This makes it possible to realize a resin tube 1 with an even smaller load on the environment. The heat treatment may be carried out, for example, in a temperature range higher than the melting point of the crosslinked fluororesin and 100° C. or less than the melting point of the crosslinked fluororesin.

[0020] The base resin used for the resin tube 1 may be nylon, urethane, fluororesin such as PTFE, engineering plastic such as PEEK (polyether ether ketone), polyimide, polyethylene, polypropylene, etc. For example, when ETFE is used as the base resin, the heat resistance of the resin tube 1 can be improved by including particles made of cross-linked fluororesin.

[0021] From the viewpoint of reducing the environmental load, it is preferable to use a non-fluororesin such as nylon as the base resin used in the resin tube 1, instead of a fluororesin. By dispersing particles made of crosslinked fluororesin in the base resin as in the present embodiment, it is possible to realize sufficient abrasion resistance and the like without using a fluororesin as the base resin. For example, when nylon is used as the base resin, it is possible to realize abrasion resistance equivalent to that of ETFE by including particles made of crosslinked fluororesin. Therefore, as an alternative to ETFE, a resin composition in which particles made of crosslinked fluororesin are dispersed in nylon can be used for the resin tube 1, and the amount of fluororesin used can be reduced, thereby further reducing the load on the environment.

[0022] The resin tube 1 preferably contains particles made of cross-linked fluororesin in an amount of 5 mass% or more and 20 mass% or less. In other words, the mass ratio of the base resin to the particles made of cross-linked fluororesin (base resin:particles made of cross-linked fluororesin) is preferably within the range of 95:5 to 80:20. If the particles made of cross-linked fluororesin are less than 5 mass%, the effect of improving the abrasion resistance cannot be sufficiently obtained. If the particles made of cross-linked fluororesin are more than 20 mass%, the fluidity decreases, making it difficult to extrude the resin tube 1. By forming the resin tube 1 with a different content of particles made of cross-linked fluororesin, it is possible to manufacture resin tubes 1 with different abrasion resistance, and it is also possible to grade the resin tubes according to their abrasion resistance.

[0023] The resin tube 1 preferably has a thickness (difference between the inner diameter and the outer diameter) of (average thickness -0.01 mm) or more (average thickness +0.01 mm) or less in the circumferential direction, and a flatness (minimum outer diameter / maximum outer diameter) of 0.9 or more and 1.0 or less. This makes it easier for the outer surface 2 of the resin tube 1 to come into point contact with other members, thereby further improving wear resistance.

[0024] (Manufacturing method of resin tube 1) FIG. 2 is a flow diagram showing the procedure for manufacturing the resin tube 1. As shown in FIG. 2, first, in step S1, a crosslinked fluororesin manufacturing process is performed. In the crosslinked fluororesin manufacturing process, a sheet made of a crosslinked fluororesin is produced by irradiating a sheet made of a non-crosslinked fluororesin (for example, a PTFE sheet) with ionizing radiation, and the sheet is pulverized into particles. At this time, it is preferable to perform pulverization so that the average particle size is 25 μm or less (preferably 20 μm or less). As a result, particles made of a crosslinked fluororesin are obtained. Thereafter, the obtained particles made of a crosslinked fluororesin may be subjected to the above-mentioned heat treatment to reduce the perfluoro compound and reduce the burden on the environment.

[0025] Then, in step S2, a molding material production process is performed. In the molding material production process, a base resin and particles made of a crosslinked fluororesin are put into a kneader such as a twin-screw kneader, and after they are heated and kneaded, the kneaded resin is extruded from the kneader. The extruded resin composition is then molded with a pelletizer or the like to produce a molding material (material for producing a molded body) made of pellets or sheets. In addition, in order to easily mold a resin tube 1 having fine irregularities on the outer surface 2 and the inner surface 3, the molding material is preferably pellets. In addition, the resin composition may be cooled immediately after being extruded from the kneader, or immediately after being formed into pellets or the like. The resin temperature during kneading in the molding material production process is preferably the melting point of the base resin used or higher (more preferably, the melting point of the base resin + 10°C or higher) and the melting point of the base resin + 50° or lower.

[0026] Thereafter, in step S3, a molding process is performed. In the molding process, a molding material such as pellets is put into an extruder and extrusion-molded to form the resin tube 1. In this embodiment, the resin composition is extruded so as to cover the surface of a linear core material (e.g., a solid conductor) made of metal or the like, and then the core material is pulled out to form the resin tube 1. This makes it possible to obtain 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. The resin temperature during extrusion molding is preferably set to be equal to or higher than the melting point of the base resin used (more preferably, equal to or higher than the melting point of the base resin + 10°C) and equal to or lower than the melting point of the base resin + 50°C, similar to the resin temperature during kneading in the molding material manufacturing process. The extrusion molding may be solid extrusion or tube extrusion. Since fine irregularities are formed on the inner surface 3 of the resin tube 1 according to this embodiment, the adhesive force to the core material can be reduced, and the core material can be easily pulled out. The resin tube 1 may be cut to a desired length (e.g., 1 m, 2 m, etc.) before pulling out the core material.

[0027] In this embodiment, the resin tube 1 is formed using a core material in the molding process, but the present invention is not limited to this, and the resin tube 1 may be formed by extruding the resin composition into a tube without using a core material. In this case, it is preferable to use a vertical extruder that performs extrusion molding in a vertical downward direction in order to suppress unevenness in thickness due to the influence of gravity.

[0028] (Cable 10) Next, a cable 10 according to the present embodiment will be described. The cable 10 is, for example, a cable for moving parts used in moving parts of industrial robots and the like. The cable 10 may have various structures as long as it includes one or more resin tubes 1 according to the present embodiment and is configured by collectively covering the one or more resin tubes 1 and one or more insulated wires 4 (or a cable 5 including one or more insulated wires 4) with a sheath.

[0029] For example, cable 10 may be a multi-core cable 11. Fig. 3 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of multi-core cable 11. Multi-core cable 11 includes a cable core 11a in which a plurality of (two here) cables 5 and two resin tubes 1 are twisted together, a tape member 11b wound in a spiral shape around cable core 11a, a shield layer 11c provided so as to cover the periphery of tape member 11b, and a sheath 11d provided so as to cover shield layer 11c. Resin tube 1 is provided as a member for making the cross section of cable core 11a approximately circular, or as a member for transporting air or water.

[0030] Since the resin tube 1 has fine irregularities on its outer surface 2, even if the multi-core cable 11 is repeatedly bent, twisted, or the like, it is possible to suppress wear (wear of the resin tube 1 and wear of the member rubbing against the resin tube 1) caused by rubbing against the adjacent cables 5 and tape member 11b. This improves resistance to repeated bending, twisting, U-shaped sliding, and other operations. The cable 5 is configured by twisting six insulated electric wires 4, each having an insulator 42 coated around a conductor 41, and winding a tape member 51 around the conductor 41 in a spiral shape, and coating the tape member 51 with a sheath 52. However, the specific structure of the cable 5 is not limited to this, and the insulated electric wire 4 may be used instead of the cable 5.

[0031] The tape member 11b is made of, for example, a resin tape, and is wound in a spiral shape so that a part of the tape overlaps in the width direction. The shield layer 11c is made of a braided shield made of a plurality of metal wires braided together, a horizontally wound shield made of a plurality of metal wires wound in a spiral shape, a plated shield plated with a metal such as copper, or a combination of a plurality of these. The shield layer 11c can be omitted depending on the application. The sheath 11d is made of, for example, polyvinyl chloride resin.

[0032] The cable 10 may be a flat cable 12. FIG. 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 configured by arranging a plurality of (four here) cables 5 and a plurality of (two here) resin tubes 1 in parallel in the width direction and fusing the sheaths 12a of adjacent cables 5 together. In the flat cable 12, the resin tubes 1 are arranged to sandwich the four cables 5. In the flat cable 12, the sheaths 12a are coated so as to cover the circumference of the resin tubes 1, and the sheaths 12a are fused to the sheaths 12a of adjacent cables 5, so that the resin tubes 1 are connected to the cables 5 via the sheaths 12a. In the illustrated example, only cables 5 having the same structure are used, but cables 5 having different structures may be included. In the illustrated example, the sheaths 12a are fused to each other, but the present invention is not limited to this. The flat cable 12 may be configured by providing a cover to cover the circumference of the parallel-arranged cables 5 and the resin tubes 1. Alternatively, the cable 5 and the resin tube 1 covered with the sheath 12a, which are arranged in parallel, may be bonded together.

[0033] (Harness 13, and other uses) The resin tube 1 may also be incorporated into a harness 13 (also referred to as a set harness) used for wiring an industrial robot or the like. For example, the harness 13 shown in FIG. 5 is configured by bundling a plurality of cables 5 and the resin tubes 1 with a bundling member 13a. The resin tube 1 has fine irregularities on the outer surface 2, so that it is less likely to be worn even when rubbed against the cables 5 or surrounding members. The cable 5 includes one or more insulated electric wires 4. The insulated electric wires 4 may be used instead of the cable 5. In other words, the harness 13 may be configured by bundling one or more resin tubes 1 and one or more insulated electric wires 4 (or cables 5 including the insulated electric wires 4).

[0034] Furthermore, as shown in Fig. 6, the resin tube 1 can also be used as a protective tube that collectively covers the periphery of multiple cables 5. In this case, multiple cables 5 are inserted into the hollow portion 1a of the resin tube 1. Since the inner surface 3 of the resin tube 1 has fine irregularities, the cables 5 are less likely to wear out even if the cables 5 inserted into the hollow portion 1a rub against the inner surface 3. Furthermore, since the outer surface 2 of the resin tube 1 also has fine irregularities, liquids such as water and paint and dirt are less likely to adhere to the tube, and even if they do, they can be easily wiped off.

[0035] (Functions and Effects of the Embodiments) As described above, the resin tube 1 according to the present embodiment is made of a resin composition in which particles made of crosslinked fluororesin are dispersed in a base resin. As a result, the particles made of crosslinked fluororesin are non-meltable and have low coagulation properties, making them easy to disperse. Therefore, by uniformly dispersing the particles made of crosslinked fluororesin in the base resin, it is possible to uniformly form fine irregularities on the surface of the resin tube 1, making it less susceptible to wear even when it comes into contact with other members.

[0036] Furthermore, by forming minute irregularities on the outer surface 2 and 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 inner surface 3 of the resin tube 1. Even if dirt or the like adheres to the outer surface 2 of the resin tube 1, the dirt can be easily wiped off.

[0037] Furthermore, according to this embodiment, even if a non-fluororesin is used as the base resin instead of a fluororesin, it is possible to achieve abrasion resistance and the like equivalent to that achieved when a fluororesin is used. This makes it possible to reduce the amount of fluororesin used in the resin tube 1 and further reduce the burden on the environment. Furthermore, reducing the amount of fluororesin used in the resin tube 1 also makes it possible to reduce costs. Furthermore, for example, when a fluororesin such as PTFE is used as the base resin, the tube is hard and vulnerable to impact, but by using a non-fluororesin such as nylon as the base resin, it is possible to improve flexibility and resistance to impact.

[0038] (Modification) In the above embodiment, the resin tube 1 has been described as having a single layer structure, but the resin tube 1 may have a multi-layer structure. In this case, at least one of the layers constituting the resin tube 1 may be made of a resin composition in which particles made of cross-linked fluororesin are dispersed in a base resin. In addition, the layer made of the resin composition in which particles made of cross-linked fluororesin are dispersed in a base resin may constitute at least one of the outer surface 2 and the inner surface 3 of the resin tube 1.

[0039] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[0040] [1] A hollow cylindrical resin tube (1) having a hollow portion (1a) along the longitudinal direction, the resin tube (1) being made of a resin composition in which particles made of cross-linked fluororesin are dispersed in a base resin.

[0041] [2] The resin tube (1) according to [1], comprising particles made of the crosslinked fluororesin in an amount of 10 mass% or more and 20 mass% or less.

[0042] [3] The resin tube (1) according to [1], wherein at least the outer surface (2) has an arithmetic mean roughness Ra of 1 μm or more and 10 μm or less.

[0043] [4] The resin tube (1) according to [1], wherein the crosslinked fluororesin has a content of perfluoro compounds having a carbon number of 8 of 10 ppb or less, and a content of each of perfluoro compounds having a carbon number of 9 to 21 of 25 ppb or less.

[0044] [5] The resin tube (1) according to [1], wherein the base resin is made of a non-fluorine resin.

[0045] [6] A cable (10) comprising one or more resin tubes (1) according to any one of [1] to [5], the one or more resin tubes (1) and one or more insulated electric wires (4) being collectively covered with a sheath (11a, 12a).

[0046] [7] A harness (13) comprising one or more resin tubes (1) according to any one of [1] to [5], and configured by bundling the one or more resin tubes (1) and one or more insulated electric wires (4).

[0047] (Additional Note) Although the embodiment of the present invention has been described above, the invention according to the claims is not limited to the embodiment described above. It should be noted that not all of the combinations of features described in the embodiment are essential to the means for solving the problems of the invention. The present invention can be modified appropriately without departing from the spirit of the invention. [Explanation of symbols]

[0048] 1...Resin tube 1a...Hollow part 2...External surface 3. Inner surface 4…Insulated wire 10…Cable 13…Harness

Claims

1. A hollow cylindrical resin tube having a hollow portion along a longitudinal direction, The resin composition comprises a base resin and particles of a crosslinked fluororesin dispersed therein. Plastic tube.

2. The particles made of the crosslinked fluororesin are contained in an amount of 10 mass% or more and 20 mass% or less. The resin tube according to claim 1 .

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

4. The crosslinked fluororesin is The content of perfluoro compounds having 8 carbon atoms is 10 ppb or less, The content of each of the perfluoro compounds having a carbon number of 9 to 21 is 25 ppb or less. The resin tube according to claim 1 .

5. The base resin is made of a non-fluorine resin. The resin tube according to claim 1 .

6. The device comprises one or more resin tubes according to any one of claims 1 to 5, The one or more resin tubes and the one or more insulated electric wires are collectively covered with a sheath. cable.

7. The device comprises one or more resin tubes according to any one of claims 1 to 5, The one or more resin tubes and one or more insulated electric wires are bundled together. Harness.

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