CN-113921171-B - Power transmission cable and method for manufacturing power transmission cable

Abstract

The invention provides a power transmission cable and a manufacturing method thereof, which can inhibit a gap between a sheath layer and an insulating layer and improve drawing strength on the inner side of the sheath layer. The power transmission cable is provided with (a) a core having a conductor (2) and an insulating layer (4) on the outer periphery thereof, and (b) a sheath layer (9) formed on the outer periphery of the core, and has the following constitution. The sheath layer is formed from a resin composition containing a matrix polymer, a silane coupling agent, and a peroxide, wherein the content of the silane coupling agent is 2 parts by mass or more, the content of the peroxide is 4 parts by mass or more, and the pullout strength of the sheath layer is 10kgf or more, based on 100 parts by mass of the matrix polymer. By adding the silane coupling agent and the peroxide as the crosslinking agents in the above-described ranges, crosslinking can be performed at a relatively low temperature, and even when the insulating layer is thick and the coefficient of linear expansion is large and the influence of thermal expansion and contraction is large, occurrence of gaps between the insulating layer and the jacket layer can be suppressed, and the drawing strength can be ensured.

Inventors

• FUJIWARA TOMOYA
• NAKAMURA KOSUKE

Assignees

• 日立金属株式会社

Dates

Publication Date

20260512

Application Date

20210707

Priority Date

20200708

Claims (9)

1. 1. An electric power transmission cable, comprising: (a) A core having a conductor and an insulating layer formed on the outer periphery of the conductor, and (B) A sheath layer formed on an outer periphery of the core; The insulating layer is thicker than the jacket layer, The insulating layer has a larger linear expansion coefficient than the sheath layer, The sheath layer is formed of a halogen-free flame retardant resin composition containing a matrix polymer, a silane coupling agent and a peroxide, The content of the silane coupling agent is 2 to 6 parts by mass based on 100 parts by mass of the matrix polymer, The content of the peroxide is 4 to 10 parts by mass based on 100 parts by mass of the matrix polymer, The drawing strength of the sheath layer is 10kgf or more.
2. 2. The power transmission cable of claim 1, wherein, The tensile strength of the sheath layer is more than 10MPa, and the oil-resistant tensile strength retention rate is more than 60%.
3. 3. The power transmission cable of claim 1, wherein, The thickness of the insulating layer is more than 3 times of the thickness of the sheath layer, The ratio of the linear expansion coefficients of the sheath layer and the insulating layer, i.e., the linear expansion coefficient of the insulating layer/the linear expansion coefficient of the sheath layer, is 1.3 or more.
4. 4. The power transmission cable of claim 1, wherein, A shielding layer is provided between the sheath layer and the insulating layer.
5. 5. The power transmission cable of claim 4, wherein, A push belt layer is provided between the sheath layer and the shield layer.
6. 6. The power transmission cable of claim 1, wherein, The matrix polymer comprises an ethylene vinyl acetate copolymer, The metal hydroxide is contained in an amount of 100 to 150 parts by mass per 100 parts by mass of the matrix polymer.
7. 7. The power transmission cable of claim 1, wherein, The core is formed of a resin core having a conductor, an inner semiconductive layer, an insulating layer, and an outer semiconductive layer.
8. 8. A method of manufacturing a power transmission cable, comprising: (a) A step of coating a core having a conductor and an insulating layer formed on the outer periphery of the conductor with a halogen-free flame-retardant resin composition as a sheath layer, and (B) A step of crosslinking by heating the sheath layer; The insulating layer is thicker than the jacket layer, The insulating layer has a larger linear expansion coefficient than the sheath layer, The sheath layer is formed of a halogen-free flame retardant resin composition containing a matrix polymer, a silane coupling agent and a peroxide, The content of the silane coupling agent is 2 to 6 parts by mass based on 100 parts by mass of the matrix polymer, The content of the peroxide is 4 parts by mass to 10 parts by mass relative to 100 parts by mass of the matrix polymer.
9. 9. The method for manufacturing a power transmission cable according to claim 8, wherein, In the step (b), the jacket layer is heated in a state of being covered with a coating material.

Description

Power transmission cable and method for manufacturing power transmission cable Technical Field The present invention relates to a power transmission cable and a method for producing a power transmission cable, and more particularly, to a power transmission cable using a halogen-free flame retardant resin composition and a method for producing the same. Background In order to reduce damage to cables used in railway vehicles and the like in a fire, characteristics such as flame retardancy and low smoke generation are required. In order to obtain high flame retardancy, a material is used in which a halogen flame retardant such as chlorine or bromine is added to polyolefin. However, a large amount of these halogen-based flame retardants may generate a large amount of toxic and harmful gases during combustion, and may generate extremely toxic substances depending on the combustion conditionsAnd (5) an English (English). Therefore, from the viewpoints of safety in fire and reduction of environmental load, cables using halogen-free materials (halogen-free materials) containing no halogen substance as a coating material have been widely used. For example, patent document 1 discloses a power transmission cable in which a matrix polymer containing an ethylene-vinyl acetate copolymer having a vinyl acetate content of 50 wt% or more and a halogen-free flame-retardant resin composition containing 100 parts by mass or more and 180 parts by mass or less of a metal hydrate and silica in total relative to 100 parts by mass of the matrix polymer are used as a sheath layer in order to achieve high flame retardance and low smoke generation. Patent document 2 discloses a power transmission cable including an inner semiconductive layer formed on the outer periphery of a conductor, an insulating layer formed on the outer periphery of the inner semiconductive layer, an outer semiconductive layer formed on the outer periphery of the insulating layer, a semiconductive belt layer formed by winding a semiconductive belt around the outer periphery of the outer semiconductive layer, a shielding layer formed by winding a wire around the outer periphery of the semiconductive belt layer, and a sheath layer formed on the outer periphery side of the shielding layer. In the power transmission cable, the recession of the outer semiconductive layer and the insulating layer is suppressed by the metal wire constituting the shielding layer. Prior art literature Patent literature Patent document 1 Japanese patent laid-open publication 2016-100140 Patent document 2 Japanese patent laid-open publication 2016-100148 Disclosure of Invention Problems to be solved by the invention The power transmission cable is formed by coating a halogen-free flame-retardant resin composition as a sheath layer on a core having a conductor and an insulating layer formed on the outer periphery of the conductor, and then crosslinking the resin material by heating after coating the halogen-free flame-retardant resin composition. At this time, when the halogen-free flame retardant resin composition serving as the jacket layer is heated, the insulating layer and the jacket layer in the inside thermally expand, respectively, and shrink, respectively, in the cooling step. At this time, an excessive gap between the insulating layer and the sheath layer may be caused by a difference in shrinkage rates of the insulating layer and the sheath layer. This excessive gap may cause a problem in connection reliability at a connection portion between the power transmission cable and other components. For example, an excessive gap is generated between the core (insulating layer) and the sheath layer, and thus either one of the members between the core (insulating layer) and the sheath layer moves in the longitudinal direction of the power transmission cable, and the sheath is displaced. When such a sheath misalignment occurs, connection reliability between the power transmission cable and other components is hindered. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power transmission cable and a method for manufacturing the power transmission cable, which can suppress occurrence of an excessive gap between a sheath layer and an insulating layer, improve the drawing strength on the inner side of the sheath layer, and improve the connection reliability between the power transmission cable and other members. Means for solving the problems [1] The power transmission cable according to one embodiment of the present invention comprises (a) a core portion having a conductor and an insulating layer formed on the outer periphery of the conductor, and (b) a sheath layer formed on the outer periphery of the core portion, wherein the insulating layer is thicker than the sheath layer, the insulating layer has a linear expansion coefficient larger than that of the sheath layer, the sheath layer is formed of a halogen-free fl