Electrical wires and cables

Abstract

To provide an electric wire cable with good peeling performance between the nonwoven fabric layer and the sheath layer. [Solution] The electric wire cable 1 of the present invention comprises a nonwoven fabric layer 20 having an embossed surface 20a on its outer circumference, and a synthetic resin sheath layer 30 covering the embossed surface 20a, characterized in that the embossed area ratio, which is the ratio of the embossed area to the total area, is less than 15% on the embossed surface 20a.

Description

Technical Field

[0001] The present invention relates to an electric wire cable, and particularly to an electric wire cable having good peeling performance between a non-woven fabric layer and a sheath layer.

Background Art

[0002] An electric wire cable is a cable designed for power supply or transmission of communication signals, and has a multi-layer structure composed of a conductor, an insulating layer, a non-woven fabric layer, a sheath layer, etc. The electric wire cable is manufactured by winding a holding tape around a core wire group (a bundle of a conductor and an insulating layer) to form a non-woven fabric layer, and extruding and coating a synthetic resin on the outside of the non-woven fabric layer. The holding tape constituting the non-woven fabric layer mainly employs a long fiber non-woven fabric such as a polyester-based resin. The long fiber non-woven fabric such as a polyester-based resin is excellent in heat resistance, flexibility, and strength, is easy to handle, and is effective in that it can ensure the necessary mechanical strength while minimizing the increase in the weight of the entire electric wire cable. Patent Document 1 discloses an electric wire cable using a holding tape made of a polytrimethylene terephthalate (PTT) long fiber non-woven fabric.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When connecting an electric wire cable to a device, performing repair and maintenance work, or disposing and recycling, an operation of peeling off the sheath layer from the electric wire cable occurs in order to expose the conductor inside the cable. In this case, if the adhesive strength between the sheath layer and the nonwoven fabric layer is too strong, a large force will be required to peel off the sheath layer, reducing work efficiency. Also, when peeling off the sheath layer, cohesive failure may occur on the surface of the nonwoven fabric layer, potentially causing nonwoven fabric fibers to scatter and worsening the working environment. [Means for solving the problem]

[0005] The electric wire cable of the present invention comprises a nonwoven fabric layer having an embossed surface on its outer circumference and a synthetic resin sheath layer covering the embossed surface, characterized in that the embossed area ratio, which is the ratio of the embossed area to the total area, is less than 15%.

[0006] In the electric wire cable of the present invention, the embossed surface may have an embossed area ratio of more than 2.5%. [Effects of the Invention]

[0007] The electric wire cable of the present invention has good peeling performance between the nonwoven fabric layer and the sheath layer, resulting in high workability during the sheath layer stripping process and reduced scattering of fibers during stripping. [Brief explanation of the drawing]

[0008] [Figure 1] Diagram explaining electrical wires and cables [Modes for carrying out the invention]

[0009] The electric wire cable of the present invention will be described in detail below.

[0010] <1> Electrical wires and cables (Figure 1) The electric wire cable of the present invention is a multi-layered cable used for power supply and transmission of communication signals. Here, the electric wire cable includes power cables, fire-resistant cables, and communication cables, and its use is not limited as long as it has the structure specified in the present invention. The electric wire cable 1 has a multi-layer structure centered on a conductor, and comprises, in order from the inside out, a conductor cable structure 10 containing the conductor, a nonwoven fabric layer 20, and a sheath layer 30. The electric wire cable 1 can be manufactured by winding a nonwoven fabric fastening tape around the outer circumference of a conductor cable structure 10 to form a nonwoven fabric layer 20, and then extruding a synthetic resin coating onto the outer circumference of the nonwoven fabric layer 20 to form a sheath layer 30. However, the method of manufacturing the electric wire cable 1 is not limited to this, and it may be manufactured by other known manufacturing methods. The conductor cable structure 10 may be either a single core wire (single-core type) in which the conductor is covered with an insulating layer, or a combination of multiple core wires and interlining material (double-core type).

[0011] <2> non-woven layer The nonwoven fabric layer 20 is a layer for fixing the twist of the conductor cable structure 10, and is constructed by wrapping a nonwoven fabric fastening tape around the outer circumference of the conductor cable structure 10. The nonwoven fabric layer 20 has an embossed surface 20a on its outer surface due to embossing. In this example, a polyester (PET) long-fiber nonwoven fabric produced by the spunbond method is used as the nonwoven fabric constituting the nonwoven layer 20. Other materials that can be used as raw materials for the nonwoven fabric include polypropylene (PP), polyethylene (PE), rayon, nylon, and wool. Furthermore, various manufacturing methods such as meltblowing, chemical bonding, thermal bonding, needle punching, and spunlacing can be employed. The fiber diameter (μm), cross-sectional shape of the fibers, and basis weight (g / m²) of the nonwoven fabric are also specified. 2 The thickness (mm), etc., can be arbitrarily set according to the required performance of the electric wire cable 1. The embossing that constitutes the embossed surface 20a can be either concave or convex, and its shape can be arbitrarily selected from circular, elliptical, square, rectangular, rhombus, T-shaped, etc.

[0012] <2.1> Embossing Area Ratio One feature of the electric wire cable 1 of the present invention is that the embossed area ratio on the embossed surface 20a is optimized in order to ensure good peeling performance of the nonwoven fabric layer 20 and the sheath layer 30. In the manufacturing process of the electric wire cable 1, during the step of coating the nonwoven fabric layer 20 with molten synthetic resin, the synthetic resin penetrates into the embossing of the nonwoven fabric. Subsequently, as the synthetic resin cools and hardens, cohesive force is generated, and the synthetic resin within the embossing forms physical bonds, thereby increasing the adhesive strength between the nonwoven fabric layer 20 and the sheath layer 30. Therefore, by setting an upper limit on the embossed area ratio, it becomes possible to suppress the adhesive strength between the nonwoven fabric layer 20 and the sheath layer 30 and ensure good peel performance. In this invention, the embossed area ratio of the embossed surface 20a is less than 15%. Furthermore, considering the processing suitability of the electric wire cable 1, it is desirable that the embossed area ratio be greater than 2.5%. Here, "embossed area ratio" refers to the ratio of the embossed area to the total area within the measurement range. "Embossed area" refers to the sum of the flat areas occupied by the recesses within the measurement range. That is, if the embossing is concave, it refers to the sum of the flat areas of the embossing; if the embossing is convex, it refers to the sum of the flat areas of the areas excluding the embossing. The embossed area can be calculated by measuring the flat area of ​​each emboss using an optical microscope with a 2x objective lens magnification, and then multiplying the flat area per embossing by the number of embossing areas within the measurement range. However, the measurement method for the embossed area is not limited to the above; it can be measured at any magnification. It can also be measured using a microscope or similar device.

[0013] <3> sheath layer The sheath layer 30 is a layer for protecting the conductor cable structure 10 from the external environment, and is constructed by covering the outer periphery of the nonwoven fabric layer 20 with synthetic resin. In this example, polyethylene (PE) is adopted as the synthetic resin constituting the sheath layer 30. In addition, as raw materials for the sheath layer 30, polypropylene (PP), cross-linked polyethylene (XLPE), other polyolefin resins, polyvinyl chloride (PVC) and other vinyl resins, polyurethane (PU) and other urethane resins, polyamide (PA), ethylene propylene rubber (EPR), silicone rubber, etc. can be adopted. Also, the thickness of the sheath layer 30 and various surface treatments can be arbitrarily set in relation to heat insulation, waterproofness, mechanical strength, etc.

Example

[0014] <1>Peel test Test pieces of the non-woven fabric layer and the sheath layer were prepared and a peel test was conducted.

[0015] <1.1>Preparation of test pieces (1) Two sheets of polyethylene sheets (peel layers) were used to sandwich a polyester long fiber non-woven fabric (non-woven fabric layer) to form a laminate, and the laminate was cut out to a predetermined size. ·Width × length: 10 mm × 40 mm (2) The laminate was heated for a predetermined time while applying pressure in the stacking direction to fuse the sheath layer to the non-woven fabric layer. ·Compressive load: 24.5 N (mass conversion: 2.5 kg) ·Heating temperature: 170 °C ·Heating time: 3 minutes (3) Six test pieces numbered 1 to 6 were prepared by changing the embossed area ratio of the test pieces.

[0016] <1.2>Test and evaluation A 90-degree peel test was conducted on the test pieces and the peeled surface was observed. (1) The lower sheath layer of the test piece was fixed to the test plate (2) The end of the upper sheath layer was fixed to the pulling jig and pulled upward at 10 mm / s and peeled at 90° with respect to the test plate (3) The peeled surface was visually observed and evaluated by the naked eye [Evaluation criteria] 〇: Interface failure... Failure at the bonding interface between the non-woven fabric layer and the sheath layer ×: Cohesive failure... Destruction of the nonwoven fabric layer

[0017] <1.3> Test Results The results of the peel test are shown in Table 1.

[0018] [Table 1]

[0019] <1.4> Analysis of test results In test specimens 1 and 2, with an embossed area ratio of 15.0 or higher, cohesive failure within the nonwoven fabric layer was observed, resulting in nonwoven fabric fibers adhering to the inner surface of the sheath layer. On the other hand, in test specimens 3 to 6, with an embossed area ratio of less than 15.0, the nonwoven fabric layer and the sheath layer were separated due to interfacial failure, and almost no nonwoven fabric fibers adhered to the surface of the sheath layer. From the above, it was confirmed that there is a correlation between the embossed area ratio and peel performance, that peel performance is better as the embossed area ratio decreases, and that the embossed area ratio needs to be less than 15.0%.

[0020] <2> Tensile test Tensile tests were performed on each nonwoven fabric corresponding to the test specimens used in the peel test. • Test method: In accordance with JIS L1913 (General Nonwoven Fabric Test Methods): 2010

[0021] <2.1> Test Results The results of the tensile test are shown in Table 2. During the manufacturing of electric wires and cables, there is a process in which nonwoven fabric is wrapped around the outer circumference of the conductor cable structure. If the tensile strength of the nonwoven fabric falls below a specified value, there is a risk that the nonwoven fabric may break during the wrapping process. Therefore, it is desirable to ensure that the tensile strength of the nonwoven fabric is 100 MPa.

[0022] [Table 2]

[0023] <2.2> Analysis of Test Results Nonwoven fabrics 1-5 all had an embossed area ratio of over 2.5 and maintained a tensile strength of 100 MPa or more. On the other hand, nonwoven fabric 6 had an embossed area ratio of 2.5 and a tensile strength of less than 100 MPa. Based on the above, it was confirmed that an embossed area ratio of over 2.5% is desirable to ensure suitable processing during manufacturing. [Explanation of symbols]

[0024] 1. Electric wires and cables 10 Conductor Cable Structure 20 non-woven layer 20a Embossed surface 30 Sheath Layers

Claims

1. A nonwoven fabric layer having an embossed surface on its outer edge, The embossed surface is covered by a synthetic resin sheath layer, The embossed surface is characterized in that the embossed area ratio, which is the ratio of the embossed area to the total area, is less than 15%. Electrical wires and cables.

2. The embossed surface is characterized in that the embossed area ratio is greater than 2.5%. The electric wire cable according to claim 1.

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