Electric wires and cables

Abstract

This invention provides electric wires and cables in which the suppression of changes in the outer diameter of electric wires and cables due to the migration of oily components from the outside is ensured with the minimum thickness of the outermost layer. [Solution] A wire or cable having a coating layer as the outermost layer, which is formed by coating an extruded resin layer disposed around a conductor or an insulated core wire having an insulating layer on a conductor with a thickness of 1 to 100 μm, and the coating film thickness of the coating layer is uniform in a cross section along the outer circumference of the extruded resin layer.

Description

Technical Field

[0001] The present invention relates to electric wires and cables.

Background Art

[0002] Laid electric wires and cables may be continuously exposed to oil components contained in electric wires and cables of different material types or structures existing in the surrounding environment. For example, when a plurality of types of electric wires and cables are bundled and laid in a structure, a plasticizer (oil component) contained on the surface of a certain electric wire and cable continues to contact other electric wires and cables. Also, when an electric wire and cable is laid near a machine, the electric wire and cable may be continuously exposed to the oil component contained in the machine. In the above, depending on the amount of the oil component, contact time, temperature conditions, etc., the oil component penetrates into and swells the extrusion resin layer of the electric wire and cable directly or through a liquid medium such as the laying environment water. When the extrusion resin layer expands, an outer diameter variation of the electric wire and cable occurs. For example, when an outer diameter variation occurs at a penetration part or an edge of a structure at the laying location, the outer diameter variation may cause a factor for an injury to occur on the surface of the electric wire and cable. As a result, the performance of the electric wire and cable may deteriorate.

[0003] In order to suppress an outer diameter change (outer diameter expansion) due to the extrusion resin layer of an electric wire and cable absorbing an oil component from the outside and expanding, there are methods such as laying the electric wire and cable in a protection tube excellent in oil resistance, making it a structure with a metal sheath, or preventing the transfer of the oil component from the outside. Since these methods increase the outer diameter and weight when including the protection tube and the metal sheath, it is difficult to make a small turn during wiring and the workability is poor. As other methods, for example, having an extrusion resin layer excellent in oil resistance as the outermost layer can be mentioned. However, in the case of an extrusion resin, there has conventionally been a need to realize characteristics other than oil resistance such as insulation characteristics, mechanical strength characteristics, flexibility, and flame retardancy required for the extrusion resin layer, and there are cases where it is difficult to achieve both of these and excellent oil resistance. In contrast, for example, Patent Document 1 describes a technology in which the outermost layer is a multilayer structure consisting of an extruded resin inner layer and an extruded resin outer layer, with the two layers sharing the performance. In this technology, by providing the inner layer with insulating and flame-retardant properties, and the outer layer with flame-retardant, oil-resistant, and mechanical properties, the influence of oily components in the surrounding environment can be suppressed. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-97881 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] As mentioned above, if the outermost layer of electric wires and cables is a multi-layer structure consisting of an inner layer and an outer layer of extruded resin, the resin layers need to be several hundred micrometers or thicker to maintain the performance of each layer. In this case, the outer diameter of the electric wires and cables becomes large, making them difficult to maneuver and resulting in poor workability, as mentioned earlier. Based on the above points, the present invention aims to provide electric wires and cables in which the suppression of changes in outer diameter due to the migration of oily components from the outside is ensured with the minimum thickness of the outermost layer. [Means for solving the problem]

[0006] The object of the present invention was achieved by the following means. [1] On an extruded resin layer arranged around a conductor, or an insulated core wire having an insulating layer on a conductor, The outermost layer is a coating layer formed by applying a resin coating with a thickness of 1 to 100 μm, which includes at least one resin selected from the group consisting of epoxy resin, urethane resin, silicone resin, fluororesin, and acrylic resin. The thickness of the coating layer is uniform in a cross-section along the outer circumference of the extruded resin layer. Electric wires and cables. [2] The electric wire / cable described in [1], wherein the uniformity of the coating film thickness of the aforementioned coating layer is such that the ratio of the minimum thickness (tmin) to the average thickness (ta) at each measurement point (tmin / ta), as measured by the following measurement method, is in the range of 0.8 to 1.0. (Method for measuring the uniformity of the coating layer) The extruded resin layer and the outermost layer are peeled off as a single unit from the electric wire / cable. The circumferential cross-section of the electric wire / cable is observed with a microscope, and the average thickness of the coating film at each of the four points obtained by dividing the outer circumference into four sections is defined as ta, and the minimum thickness as tmin. [3] The electric wire or cable according to [1] or [2], wherein the extruded resin layer consists of at least one selected from the group consisting of polyolefin resin, polyolefin elastomer, chloroprene rubber, and vinyl chloride resin. [4] The electric wire or cable according to any one of [1] to [3], wherein the coating layer is made of an acrylic resin paint or a urethane resin paint that does not contain halogens. [5] The electric wires and cables described in any one of [1] to [4], wherein the coefficient of kinetic friction between the electric wires and cables is 0.7 or less. [6] The electric wire or cable described in any one of [1] to [5], wherein the rate of outer diameter expansion due to migration of oily components from the outside is 5% or less. [7] The electric wire / cable according to [6], wherein the oily component is at least one selected from the group consisting of JIS No. 2 oil, light oil, naphthenic oil, trimellitic acid ester oil, and naphthenic ester oil. [Effects of the Invention]

[0007] The electric wires and cables of the present invention ensure that changes in outer diameter due to the migration of oily components from the outside are suppressed with the minimum thickness of the outermost layer. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view along the outer circumference showing one embodiment of the electric wire / cable according to the present invention. [Figure 2] This is a cross-sectional view along the outer circumference showing another embodiment of the electric wire / cable according to the present invention. [Figure 3] This is a cross-sectional view along the outer circumference showing yet another embodiment of the electric wire / cable according to the present invention. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below. The electric wire / cable of the present invention comprises an extruded resin layer around a conductor, or an insulated core wire having an insulating layer on a conductor. An example of the former is a configuration in which an extruded resin layer 2 is arranged around a conductor 1, as shown in Figure 1. The number of conductors 1 in this configuration is not limited to that shown in Figure 1, and may be two or more. An example of the latter is a configuration in which an extruded resin layer 5 is arranged around an insulated core wire 4 having an insulating layer 4B on a conductor 4A, as shown in Figure 2. Another example is a configuration in which an extruded resin layer 8 is arranged around a twisted arrangement of multiple insulated core wires 7, each having an insulating layer 4B on a conductor 7A. The number of insulated core wires 7 is not limited to that shown in Figure 3, and may be six or fewer, or eight or more.

[0010] The material of the conductor can be any conductive material commonly used for electric wires and cables, without any particular limitations. Examples include copper, copper alloys, aluminum, aluminum alloys, and the like.

[0011] The insulating material constituting the insulating layer can be any type of insulating material commonly used in electric wires and cables, without any particular limitations. Examples include cross-linked polyethylene, ethylene propylene rubber, and polyvinyl chloride.

[0012] The extruded resin layer is formed by, for example, extruding a thermoplastic resin using an extruder and extruding and coating it on the outer surface of the aforementioned conductor or an insulated core wire having an insulating layer on the conductor. By extrusion molding, a resin layer with a certain thickness can be formed, and as described above, various properties other than oil resistance can be realized. The extruded resin layer is preferably composed of at least one selected from the group consisting of polyolefin resins, polyolefin elastomers, chloroprene rubber, and vinyl chloride resins.

[0013] The wire and cable of the present invention has a coating film layer formed by applying a resin paint on the extruded resin layer as the outermost layer. Thus, the coating film layer is arranged to cover the outer periphery of the extruded resin layer. For example, the coating film layer 3 shown in FIG. 1, the coating film layer 6 shown in FIG. 2, and the coating film layer 9 shown in FIG. 3 can be mentioned. Unlike the extruded resin layer, the coating film layer is a thin film, and the resin paint is applied with a thickness of 1 to 100 μm. That is, the coating film thickness of the coating film layer is 1 to 100 μm. This is possible because the coating film layer is formed by coating and is more likely to be formed as a thin layer (film) compared to the extruded resin layer formed by extrusion molding. Thereby, an increase in the outer diameter during manufacturing can be suppressed. The resin paint contains at least one selected from the group consisting of epoxy resins, urethane resins, silicone resins, fluorine resins, and acrylic resins. That is, the coating film layer contains at least one selected from the group consisting of epoxy resins, urethane resins, silicone resins, fluorine resins, and acrylic resins.

[0014] The wire and cable of the present invention has the coating film layer on the outside of the extruded resin layer with a specific material and a specific thin coating film thickness. Even if the coating film layer is thin, it is a film of the aforementioned specific material, so it has high oil resistance. Thereby, the wire and cable of the present invention ensures suppression of outer diameter change due to migration of oily components from the outside with a minimum outermost layer thickness.

[0015] As mentioned above, the coating layer is so thin that it cannot be achieved with the extruded resin layer that is formed by extrusion molding. Therefore, the coating layer and the extruded resin layer can be distinguished by observing the cross-section along the outer circumference of the electric wire / cable of the present invention (a cross-section perpendicular to the wire length direction) and measuring the thickness. The ratio (H2 / H1) of the coating film thickness (H2) of the coating film layer to the thickness (H1) of the extruded resin layer is preferably 1 / 20 or less, more preferably 1 / 50 or less, and even more preferably 1 / 100 or less, from the viewpoint of further reducing the outer diameter of the electric wire / cable of the present invention. The ratio (H2 / H1) is preferably 1 / 1000 or more, more preferably 1 / 500 or more, and even more preferably 1 / 200 or more, from the viewpoint of more reliably suppressing changes in outer diameter due to migration of oily components from the outside.

[0016] The thickness (H2) of the coating layer is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 7 μm or more. This prevents the problem of the coating layer being difficult to apply uniformly if the thickness is too thin. The thickness (H2) of the coating layer is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less. This prevents the coating from becoming too thick, making it less likely for the coating layer to crack or peel off. Furthermore, the thickness of the extruded resin layer (H1) can be arbitrarily set depending on the performance of the electric wire or cable.

[0017] From the viewpoint of achieving the aforementioned effects, it is preferable that the coating layer be placed directly on the extruded resin layer. This ensures that the coating layer adheres closely to and covers the surface of the extruded resin layer, more reliably eliminating the possibility of oily components seeping in, and more effectively suppressing changes in the outer diameter of the electric wires and cables of the present invention. This layer configuration can be formed, for example, by providing an in-line coating process during the extrusion coating of the extruded resin layer.

[0018] From the viewpoint of further improving the adhesion described above, it is preferable that the extruded resin layer and the coating layer be a combination of specific materials. In other words, it is preferable that the extruded resin layer consists of at least one selected from the group consisting of polyolefin resin, polyolefin elastomer, chloroprene rubber, and vinyl chloride resin, and that the coating layer contains at least one selected from the group consisting of epoxy resin, urethane resin, silicone resin, fluororesin, and acrylic resin.

[0019] Furthermore, from the viewpoint of minimizing the generation of toxic gases when electric wires and cables are burned and thus ensuring high safety, it is preferable that the coating layer be made of an acrylic resin paint or urethane resin paint that does not contain halogens.

[0020] In addition, the thickness of the coating layer is uniform in a cross-section along the outer circumference of the extruded resin layer. This eliminates weak points in the outermost layer of the electric wires and cables of the present invention and prevents the formation of entry points for oily components. As a result, even when exposed to oily components for extended periods, the electric wires and cables of the present invention are less prone to swelling of the extruded resin layer and the resulting change in outer diameter, thus extending their service life.

[0021] As a measure of the "uniformity" of the coating film thickness of the aforementioned coating layer, it is preferable that the ratio (tmin / ta) of the minimum thickness (tmin) to the average thickness (ta) at each measurement point, based on the measurement method described below, is in the range of 0.8 to 1.0. The ratio (tmin / ta) of the minimum thickness (tmin) to the average thickness (ta) between each measurement point is preferably 0.8 or higher, more preferably 0.83 or higher, even more preferably 0.85 or higher, and particularly preferably 1.

[0022] (Method for measuring the uniformity of the coating layer) The extruded resin layer and the outermost layer are peeled off as a single unit from the electric wire / cable. The circumferential cross-section of the electric wire / cable is observed with a microscope, and the average thickness of the coating film at each of the four points obtained by dividing the outer circumference into four sections is defined as ta, and the minimum thickness as tmin.

[0023] The aforementioned coating layer can be formed by various methods commonly used in the coating process. Examples include dipping, spraying, and brush application. Among these methods, spraying is preferred. This allows for further improvement of the uniformity of the coating film thickness. Furthermore, from the viewpoint of further improving the uniformity of the coating thickness, it is preferable that the viscosity of the paint applied in the coating process be low. However, from the viewpoint of maintaining a constant concentration of resin in the paint and ensuring sufficient coating thickness of the coating layer, it is preferable not to use too much solvent, and it is preferable that the viscosity of the paint be above a certain level. From this viewpoint, the viscosity of the paint to be applied is preferably 0.02 Pa·s or more and 0.10 Pa·s or less, more preferably 0.03 Pa·s or more and 0.07 Pa·s or less, and even more preferably 0.03 Pa·s or more and 0.06 Pa·s or less.

[0024] By applying the coating under the conditions described above, the coating layer can be formed with a more uniform thickness than conventional coatings. Furthermore, it is preferable to have a hot air drying step after the coating step in order to stably form the coating layer in the longitudinal direction.

[0025] The electric wires and cables of this invention have a low rate of outer diameter expansion due to the migration of oily components from the outside. Specifically, it is preferable that the outer diameter expansion ratio is 5% or less. Furthermore, it is more preferable that the outer diameter expansion ratio is 3% or less. The aforementioned outer diameter expansion ratio is a value measured by the following method.

[0026] (Illegal measurement of the outer diameter expansion rate of electric wires and cables due to the migration of oily components from external sources) A 30cm cable sample was bent into a U-shape and held in place. The central 20cm section was immersed in an oily substance for a predetermined period. The thickness before and after immersion was measured with calipers and defined as the outer diameter expansion ratio.

[0027] In the measurement of the outer diameter expansion ratio, the oily component transferred from the outside is preferably at least one selected from the group consisting of JIS No. 2 oil, light oil, naphthenic oil, trimellitic acid ester oil, and naphthenic ester oil.

[0028] In addition, the electric wires and cables of the present invention have excellent surface slipperiness due to the presence of the outermost coating layer. Specifically, the coefficient of dynamic friction between the electric wires and cables of the present invention is preferably 0.7 or less, more preferably 0.5 or less, and even more preferably 0.4 or less.

[0029] Furthermore, the electric wires and cables of the present invention are excellent not only in oil resistance but also in water resistance. In other words, the electric wires and cables of the present invention have low wettability to aqueous liquids, and the rate of outer diameter expansion due to water absorption is suppressed to a smaller extent than in conventional products. [Examples]

[0030] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0031] (Examples 1-6) A cable body with an outer diameter of 15-16 mm was fabricated by extruding a resin shown in Table 1 onto a seven-strand insulated core wire, which consisted of copper conductors with a strand diameter of 1.6 mm coated with an insulating material. Specifically, the extruded resin layer was formed to a thickness of 1.5 mm. Next, the cable body was immersed in a tank filled with acrylic resin-based paint (halogen-free) (paint viscosity: 0.05 Pa·s, paint temperature: 30°C) at a linear speed of 1 m / s, and immediately afterward, it underwent a continuous drying process at 90°C for 10 minutes to produce cable samples for each of Examples 1-6.

[0032] (Examples 7-12) Cable samples for Examples 7 to 12 were prepared in the same manner as in Examples 1 to 6, except that a urethane resin-based paint (containing halogen) was sprayed onto the samples. The viscosity of the paint was 0.03 Pa·s, and the temperature of the paint was 30°C.

[0033] (Examples 13 and 14) Cable samples for Examples 13 and 14 were prepared in the same manner as in Examples 1 and 3, except that the viscosity of the paint was set to 0.01 to 0.02 Pa·s.

[0034] (Comparative Examples 1-6) As shown in Table 2, cable samples for Comparative Examples 1 to 6 were prepared in the same manner as in Examples 1 to 6, except that a coating layer was not formed.

[0035] (Example 15) As shown in Table 3, the cable sample for Example 15 was prepared in the same manner as in Example 1, except that the resin material used for the extruded resin layer was polyvinyl chloride resin.

[0036] (Comparative Example 7) As shown in Table 3, the cable sample for Comparative Example 7 was prepared in the same manner as in Example 15, except that a coating layer was not formed.

[0037] <Testing Method> (1) Coating thickness (average thickness) and uniformity of the coating layer The extruded resin layer and the outermost layer were peeled off as a single unit from each cable sample, and the average thickness of the coating layer was measured by observing them with a microscope from the direction of the cable cross-section. At the same time, the uniformity of the film thickness of the coating layer was measured based on the above-mentioned method for measuring the uniformity of the coating layer. (2) Slipperiness Three 30cm cable samples were stacked horizontally in a sack-like fashion. The two lower cables were fixed from the left and right, and an 1130g weight was placed on the upper cable only so that the load was applied to that cable only. Next, the kinetic friction force was determined when the upper cable was pulled out horizontally at a speed of 50mm per minute, and the coefficient of kinetic friction μ' was calculated according to the formula F'=μ'N. A coefficient of kinetic friction μ' of 0.7 or less was considered acceptable. (3) Resistance to migration of oily components (oil resistance) The aforementioned cable was held in place to prevent oily components from flowing in from the terminal end, and a test sample was prepared as follows. Next, the aforementioned 30 cm cable sample was held in a U-shape, and 20 cm of it was immersed in an oily component for a predetermined period of time as described below. The percentage increase in outer diameter before and after immersion was then measured. Examples 1, 7, 13, Comparative Example 1: For each test sample, the outer diameter expansion rate was calculated before and after immersion in an oily component (JIS No. 2 oil) at room temperature for 4 hours, followed by immersion at 70°C for 4 hours. Examples 2, 8, Comparative Example 2: The percentage increase in outer diameter of each test sample was calculated before and after immersion in an oily component (diesel fuel) at room temperature for 4 hours. Examples 3, 9, 14, Comparative Example 3: For each test sample, the percentage increase in outer diameter was calculated before and after immersion in an oily component (naphthenic oil) at room temperature for 4 hours, followed by immersion at 70°C for 4 hours. Examples 4, 10, Comparative Example 4: For each test sample, the percentage increase in outer diameter was calculated before and after immersion in an oily component (diesel fuel) at room temperature for 4 hours, followed by immersion at 70°C for 4 hours. Examples 5, 11, Comparative Example 5: For each test sample, the percentage increase in outer diameter was calculated before and after immersion in an oily component (naphthenic oil) at room temperature for 4 hours, followed by immersion at 70°C for 4 hours. Examples 6, 12, Comparative Example 6: The outer diameter expansion rate of each test sample was calculated before and after immersion in an oily component (trimellitic acid ester oil) at room temperature for 4 hours, followed by immersion at 70°C for 4 hours. Example 15, Comparative Example 7: For each test sample, the percentage increase in outer diameter was calculated before and after immersion in an oily component (phthalate ester oil) at room temperature for 4 hours, followed by immersion at 70°C for 4 hours.

[0038] [Table 1]

[0039] [Table 2]

[0040] [Table 3]

[0041] As shown in Tables 1 and 2, Examples 1 to 14 showed a smaller outer diameter expansion rate compared to Comparative Examples 1 to 6. In addition, among the examples, Examples 1 to 12 had higher uniformity of the average thickness of the coating layer than Examples 13 and 14, and thus the outer diameter expansion rate was kept even lower. Note that in Examples 2, 8, and Comparative Example 2, outer diameter expansion was observed in Comparative Examples 2 and 8 with only immersion at room temperature for 4 hours, so immersion at 70°C for 4 hours was not performed. As shown in Table 3, Example 15 exhibited a smaller outer diameter expansion ratio compared to Comparative Example 7. In addition, Examples 1 to 15 met the passing criteria with a dynamic friction coefficient of 0.7 or less, demonstrating superior sliding performance compared to Comparative Examples 1 to 7. [Explanation of symbols]

[0042] 1, 4A, 7A conductor 4B, 7B insulating layer 4, 7 Insulated core wire 2, 5, 8 Extruded resin layer 3, 6, 9 Coating layer

Claims

1. A conductor, or an insulated core wire having an insulating layer on a conductor, An extruded resin layer is disposed around the conductor in contact with the conductor, or around the insulating core wire in contact with the insulating core wire. The outermost layer, which is placed in contact with the extruded resin layer, is a coating layer coated with a thickness of 7 to 20 μm, which contains at least one resin selected from the group consisting of epoxy resin, urethane resin, silicone resin, fluororesin, and acrylic resin. Electric wires and cables, wherein the thickness of the coating layer is uniform in a cross-section along the outer circumference of the extruded resin layer.

2. The electric wire / cable according to claim 1, wherein the uniformity of the coating film thickness of the coating layer is such that the ratio of the minimum thickness (tmin) to the average thickness (ta) at each measurement point (tmin / ta), as measured by the following measurement method, is in the range of 0.8 to 1.

0. (Method for measuring the uniformity of the coating layer) The extruded resin layer and the outermost layer are peeled off as a single unit from the electric wire / cable. The circumferential cross-section of the electric wire / cable is observed with a microscope, and the average thickness of the coating film at each of the four points on the outer circumference is defined as ta, and the minimum thickness as tmin.

3. The electric wire / cable according to claim 1, wherein the extruded resin layer is made of at least one selected from the group consisting of polyolefin resin, polyolefin elastomer, chloroprene rubber, and vinyl chloride resin.

4. The electric wire and cable according to claim 1, wherein the coating layer is made of an acrylic resin paint or a urethane resin paint that does not contain halogens.

5. The electric wire / cable according to claim 1, wherein the coefficient of dynamic friction between the electric wires / cables is 0.7 or less.

Images