JP6065333B2 - Watertight insulated wire and method for producing watertight insulated wire - Google Patents

Description

  The present invention relates to a watertight insulated wire and a method for producing a watertight insulated wire.

  In an insulated wire for overhead wiring, in order to suppress corrosion of a conductor due to intrusion of rainwater, a watertight insulated wire in which a watertight material is provided between conductor wires of a conductor and between a conductor and an insulating layer is used. Out of the watertight material of the watertight insulated wire, the outer layer watertight material provided between the conductor and the insulation layer is watertight (prevents rainwater intrusion or prevents water running) and strips the insulation layer from the conductor without any residue. Therefore, it is required to have both the peelability (peelability) and the adhesiveness for bringing the conductor and the insulating layer into close contact with each other. Until now, an ethylene ethyl acrylate copolymer (EEA) has been used as a base resin of an outer layer watertight material having these characteristics (for example, Patent Document 1).

Japanese Patent No. 3688319

  However, since EEA, which has been used as a base resin for outer layer watertight materials, has been difficult to obtain in recent years, a base resin for outer layer watertight materials instead of EEA has been demanded.

  The objective of this invention is providing the manufacturing method of the watertight insulated wire which has an outer layer watertight material provided with the characteristic more than the outer layer watertight material containing an ethylene ethyl acrylate copolymer, and a watertight insulated wire.

According to one aspect of the invention,
A conductor provided by twisting a plurality of conductor strands;
An inner layer watertight material filled between the plurality of conductor wires;
An outer layer watertight material provided so as to cover the conductor and the outer periphery of the inner layer watertight material;
An insulating layer provided so as to cover the outer periphery of the outer layer watertight material,
The outer layer watertight material is
A first resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 18% by weight or more and less than 22% by weight;
A second resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 22% by weight or more and less than 28% by weight, and a base resin obtained by mixing
A watertight insulated wire in which the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin is 1/4 or more and 4 or less is provided.

According to another aspect of the invention,
Forming a conductor by twisting a plurality of conductor wires; and
Filling an inner layer watertight material between the plurality of conductor strands;
Forming an outer layer watertight material so as to cover an outer periphery of the conductor and the inner layer watertight material;
Forming an insulating layer so as to cover the outer periphery of the outer layer watertight material,
In the step of forming the outer layer watertight material,
A first resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 18% by weight or more and less than 22% by weight;
Forming the outer layer watertight material with a base resin obtained by mixing a second resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 22 wt% or more and less than 28 wt%,
There is provided a method for producing a watertight insulated wire in which the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin is ¼ or more and 4 or less.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the watertight insulated wire which has the outer layer watertight material provided with the characteristic more than the outer layer watertight material containing an ethylene ethyl acrylate copolymer, and a watertight insulated wire is provided.

It is sectional drawing orthogonal to the axial direction of the insulated wire which concerns on one Embodiment of this invention. It is the schematic which shows the manufacturing method of the insulated wire which concerns on one Embodiment of this invention.

<One Embodiment of the Present Invention>
(1) Watertight insulated wire The watertight insulated wire which concerns on one Embodiment of this invention is demonstrated using FIG. FIG. 1 is a cross-sectional view orthogonal to the axial direction of the insulated wire according to the present embodiment.

  As shown in FIG. 1, a watertight insulated wire (hereinafter referred to as insulated wire) 10 according to the present embodiment is configured to be used as an electric wire for outdoor power distribution. For example, the conductor 100 and the inner layer watertight from the center side toward the outside. It has a material 220, an outer layer watertight material 240, and an insulating layer (insulator, insulating coating layer) 300.

  The conductor 100 is provided by twisting a plurality of conductor wires 110. The conductor wire 110 is made of, for example, a hard copper wire, a hard copper stranded wire, a hard aluminum stranded wire, a steel core aluminum stranded wire (ACSR), or the like. The plurality of conductor strands 110 are, for example, concentric strands, and the number of conductor strands 110 is, for example, 19.

  The inner layer watertight material 220 is filled between the plurality of conductor strands 110. The inner layer watertight material 220 is configured to improve watertightness between the plurality of conductor wires 110. Details of the inner layer watertight material 220 will be described later.

  The outer layer watertight material 240 is provided so as to cover the outer periphery of the conductor 100 and the inner layer watertight material 220. The outer layer watertight material 240 is also mainly configured to improve the watertightness between the conductor 100 and the insulating layer 300. Details of the outer layer watertight material 240 will be described later together with the inner layer watertight material 220.

  The insulating layer 300 is provided so as to cover the outer periphery of the outer layer watertight material 240 (and the conductor 100). The insulating layer 300 includes, for example, polyethylene or cross-linked polyethylene. When the insulating layer 300 contains crosslinked polyethylene, for example, the insulating layer 300 is configured to be crosslinked by a silane graft / water crosslinking method, and includes a silane coupling agent, a crosslinking agent (free radical generator), and a catalyst (silanol). Condensation catalyst). In addition, the insulating layer may contain a color batch and an anti-aging agent.

(Each dimension etc.)
The outer diameter of the conductor wire 110 is, for example, not less than 1 mm and not more than 5 mm. The cross-sectional area of the conductor 100 is, for example, 14 mm ² or more and 200 mm ² or less. The thickness of the outer layer watertight material 240 is, for example, not less than 0.1 mm and not more than 2 mm. The thickness of the insulating layer 300 is, for example, 1 mm or more and 5 mm or less. The nominal voltage of the insulated wire 10 is, for example, not less than 6.6 kV and not more than 33 kV.

(2) Watertight material (outer layer watertight material)
Next, the outer layer watertight material 240 will be described.

  As described above, the outer-layer water-tight material 240 is required to have both water-tightness (prevention of rainwater intrusion or prevention of running water), peelability (peelability), and adhesion. The water tightness is a characteristic for suppressing the propagation of rainwater between the conductor wires 110 and between the conductor 100 and the insulating layer 300 and suppressing the corrosion of the conductor 100 due to rainwater. The peelability is a characteristic for stripping the insulating layer 300 from the conductor 100 without any residue at the end of the insulated wire 10 when the insulated wire 10 is connected (when a sleeve is compression-connected to the conductor 100). The adhesion is a characteristic for preventing the insulating layer 300 from shifting or breaking when the conductor 100 and the insulating layer 300 are brought into close contact with each other and the insulated wire 10 is pulled by an electric wire gripper called a camler.

  Here, the water-tightness and the adhesiveness have characteristics similar to each other because it is necessary to strongly bond the conductor wires 110 or the conductor 100 and the insulating layer 300 to each other. On the other hand, if the conductor 100 and the insulating layer 300 are strongly bonded, it is difficult to peel the insulating layer 300 from the conductor 100, and the peelability is reduced. Therefore, watertightness and peelability are in a contradictory relationship.

  From the viewpoint of mechanical properties, the softer the outer layer watertight material 240, the easier it is for the outer layer watertight material 240 to penetrate between the conductor strands 110 or between the conductor 100 and the insulating layer 300. Adhesion is improved. On the other hand, the softer the outer layer watertight material 240, the more the outer layer watertight material 240 penetrates into the details of the conductor 100. Therefore, the outer layer watertight material 240 becomes harder to peel off from the conductor 100, and the peelability decreases. On the other hand, the harder the outer layer watertight material 240, the easier it is to peel off the insulating layer 300 from the conductor 100, so the peelability is improved. On the other hand, the harder the outer layer watertight material 240 is, the more difficult it is for the outer layer watertight material 240 to enter between the conductor strands 110 or between the conductor 100 and the insulating layer 300, resulting in lower watertightness and adhesion. .

  Therefore, the outer layer watertight material 240 is required to have desired mechanical properties (such as hardness) so as to develop an adhesive property to be appropriately bonded to the conductor 100.

  Therefore, the outer layer watertight material 240 of the present embodiment is configured as follows, for example.

  In the outer layer watertight material 240 of this embodiment, ethylene methyl methacrylate (EMMA) is used as the base resin. EMMA has a structure represented by the following formula (1).

  EMMA has characteristics similar to EEA. Specifically, EMMA has the same flexibility as ethylene vinyl acetate copolymer (EVA), elasticity similar to rubber, excellent low temperature characteristics, and excellent electrical characteristics. Further, EMMA is configured so as not to be corroded by an acid such as EVA.

  Further, the base resin of the outer layer watertight material 240 of the present embodiment is configured by mixing two resins (first resin and second resin) including EMMA and having different characteristics from each other. The first resin has high mechanical strength, hard properties, good peelability, and low adhesion. On the other hand, the second resin has low mechanical strength, soft properties, good water tightness and good adhesion, but poor peelability. In this embodiment, the outer layer watertight material 240 includes a base resin formed by mixing the first resin and the second resin, so that the watertightness, peelability, and adhesion of the insulated wire 10 can be improved in a well-balanced manner. It becomes.

  Here, the details of the first resin and the second resin will be described.

The first resin has the following characteristics, for example.
MMA content: 18 wt% or more and less than 22 wt% Melt flow rate: 1 g / 10 min or more and less than 3 g / 10 min Durometer hardness at Type A: 75 or more and less than 92 Vicat softening temperature: 54 ° C. or more and 66 ° C. or less Melting temperature: 77 ° C or higher and lower than 95 ° C

  MMA means methyl methacrylate. The melt flow rate (MFR) is a value measured in accordance with JIS K7210, when the measurement temperature is 190 ° C. and the load is 2.12 N. The durometer hardness of type A is measured according to JIS K7215. The Vicat softening temperature is measured according to JIS K7206. The melting temperature is measured by a differential scanning calorimeter (DSC) according to JIS K7121.

On the other hand, the second resin has the following characteristics, for example.
MMA content: 22 wt% or more and less than 28 wt% Melt flow rate: 6 g / 10 min or more and less than 8 g / 10 min Durometer hardness at Type A: 70 or more and less than 86 Vicat softening temperature: 42 ° C. or more and 52 ° C. or less Melting temperature: 72 ° C or higher and lower than 88 ° C

  In this embodiment, the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer watertight material 240 is ¼ or more and 4 or less (A: B = 80: 20 to 20:80). When the ratio B / A of the weight B of the second resin to the weight A of the first resin is less than ¼, that is, when the weight B of the second resin is smaller than the weight A of the first resin at a predetermined ratio. The outer-layer watertight material 240 is excessively hard, so that the peelability is improved while the adhesion is lowered. On the other hand, when the ratio B / A of the weight B of the second resin to the weight A of the first resin is 1/4 or more, the outer layer watertight material 240 is suppressed from becoming excessively hard, and the peelability is improved. While maintaining, water tightness and adhesion can be improved. On the other hand, when the ratio B / A of the weight B of the second resin to the weight A of the first resin is more than 4, that is, when the weight B of the second resin is larger than the weight A of the first resin at a predetermined ratio. Since the outer layer watertight material 240 becomes excessively soft, the watertightness and adhesion are improved, while the peelability is lowered. On the other hand, when the ratio B / A of the weight B of the second resin to the weight A of the first resin is 4 or less, the outer layer watertight material 240 is suppressed from being excessively soft, and the watertightness and adhesiveness are reduced. The peelability can be improved while keeping

  Furthermore, in this embodiment, the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer watertight material 240 is preferably 1 or more and 7/3 or less (A : B = 50: 50 to 30:70). In this way, in the base resin of the outer layer watertight material 240, by mixing a relatively soft second resin more than the first resin, it is possible to stably improve the watertightness and adhesion while keeping the peelability. it can. Moreover, the manufacturing cost of the outer-layer watertight material 240 of this embodiment can be made equivalent to the manufacturing cost of the outer-layer watertight material including the EEA base resin.

  In addition to the base resin described above, various additives are added to the outer layer watertight material 240 as follows.

  The outer layer watertight material 240 is configured to be colored, and includes, for example, a color batch. The color batch includes, for example, a color batch base resin made of EMMA, carbon black, and a dispersant. For example, the content of the color batch base resin is 50 parts by weight, the content of carbon black is 20 parts by weight, and the content of the dispersant is 30 parts by weight. The content of the color batch in the outer layer watertight material 240 is 0.5 parts by weight or more and 5 parts by weight or less when the base resin (outer layer watertight material 240) is 100 parts by weight. When the outer layer water-tight material 240 contains a predetermined amount of color batch, the outer layer water-tight material 240 can be colored to make it easy to visually recognize the peelability, and the deterioration of the outer layer water-tight material 240 over time can be suppressed.

  The outer layer watertight material 240 is configured to be crosslinked by a silane graft / water crosslinking method. For example, a silane coupling agent, a crosslinking agent (free radical generator), a catalyst (silanol condensation catalyst), And an anti-aging agent. An alkoxysilane compound is used as the silane coupling agent. Specifically, the silane coupling agent is, for example, vinyltrimethoxysilane. The content of the silane coupling agent in the outer layer watertight material 240 is 0.5 parts by weight or more and 5 parts by weight or less when the base resin is 100 parts by weight. An organic peroxide is used as the crosslinking agent. Specifically, the crosslinking agent is, for example, dicumyl peroxide (DCP). The content of the crosslinking agent in the outer layer watertight material 240 is 0.05 parts by weight or more and 0.5 parts by weight or less when the base resin is 100 parts by weight. Moreover, as a catalyst, carboxylate of metals, such as tin, zinc, iron, lead, cobalt, an organic base, an inorganic acid, an organic acid, etc. are used. Specifically, the catalyst is, for example, dibutyltin dilaurate. The content of the catalyst in the outer layer watertight material 240 is 0.01 part by weight or more and 0.1 part by weight or less when the base resin is 100 parts by weight. Moreover, as an anti-aging agent, a phenol type anti-aging agent is used, for example. Specifically, the antioxidant is, for example, thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. The content of the anti-aging agent in the outer layer watertight material 240 is 0.01 parts by weight or more and 0.3 parts by weight or less when the base resin is 100 parts by weight.

(Inner watertight material)
Next, the inner layer watertight material 220 will be described.

  The inner layer watertight material 220 is filled between the conductor wires 110 and is not in contact with the insulating layer 300. For this reason, the inner layer water-tight material 220 is not required to be peelable like the outer layer water-tight material 240. Therefore, the inner layer watertight material 220 is preferably made of a soft material so as to easily penetrate between the conductor strands 110.

  Specifically, for example, the inner layer watertight material 220 includes an inner layer watertight material base resin made of EEA as usual, and the melt flow rate of the inner layer watertight material 220 is higher than the melt flow rate of the outer layer watertight material 240, for example. Is also getting bigger. Moreover, it is preferable that the ethyl acrylate (EA) content of EEA used as the inner layer watertight material base resin of the inner layer watertight material 220 is not less than 32% by weight and not more than 38% by weight.

  The inner layer watertight material 220 also includes a color batch.

  For reference, EEA used as the inner layer watertight material base resin of the inner layer watertight material 220 has mechanical properties different from those of the EEA conventionally used as the base resin of the outer layer watertight material 240. For this reason, since EEA used as the inner layer watertight material base resin of the inner layer watertight material 220 could not be used as the base resin of the outer layer watertight material 240, the base resin of the outer layer watertight material 240 is changed as in this embodiment. Was needed.

(3) Manufacturing method of watertight insulated wire Next, the manufacturing method of the insulated wire 10 which concerns on this embodiment is demonstrated using FIG. FIG. 2 is a schematic diagram illustrating a method for manufacturing an insulated wire according to the present embodiment.

(Conductor wire forming process)
First, a predetermined number of conductor strands 110 made of, for example, hard copper wire are formed by a wire drawing machine (not shown).

(Conductor formation process and inner layer watertight material formation process)
Next, as shown in FIG. 2, the inner layer watertight material base resin made of EEA and the color batch are mixed and put into a hopper of the inner layer watertight material extruder 510. Then, the inner layer watertight material 220 is filled between the conductor wires 110 by the inner layer watertight material extruder 510 while the conductor 100 is formed by twisting a predetermined number of conductor wires 110.

(Outer layer watertight material formation process)
Next, the pellets of the first resin and the pellets of the second resin are set so that the ratio B / A of the weight B of the second resin to the weight A of the first resin is 1/4 or more and 4 or less by the metering mixer 530. Mix. Using the mixed first resin and second resin as a base resin, the base resin and predetermined additives (color batch, silane coupling agent, cross-linking agent, catalyst, anti-aging agent) are mixed to form an outer layer It puts in the hopper of the watertight material extruder 540. In addition, the silane coupling agent etc. which are added to base resin are injected | thrown-in by the injection system in the hopper lower part. Then, the outer layer watertight material extruder 540 extrudes the outer layer watertight material 240 so as to cover the outer periphery of the conductor 100 and the inner layer watertight material 220.

(Insulating layer forming process)
Next, for example, polyethylene and predetermined additives (color batch, silane coupling agent, cross-linking agent, catalyst, anti-aging agent) are mixed and put into a hopper of the insulating layer extruder 560. When the insulating layer 300 is non-crosslinked polyethylene, no silane coupling agent or the like is added. Then, the insulating layer 300 is extruded by the insulating layer extruder 560 so as to cover the outer periphery of the outer layer watertight material 240. Thereby, the intermediate body 10a of an insulated wire is formed.

(Crosslinking process)
Next, the whole drum around which the intermediate body 10a of the insulated wire is wound is immersed in warm water for a predetermined time. As a result, the inner layer watertight material 220 and the outer layer watertight material 240 are made to conform between the conductor wires 110 and between the conductor 100 and the insulating layer 300, and the outer layer watertight material 240 and the insulating layer 300 are cross-linked. When the insulating layer 300 is non-crosslinked polyethylene, the intermediate 10a is immersed in warm water in order to crosslink only the outer layer watertight material 240. In this case, the process may be simply called a heating process, not a crosslinking process.

  At this time, the crosslinking temperature in the crosslinking step is set to a temperature between the melting temperature of the first resin and the melting temperature of the second resin. For example, the crosslinking temperature is 85 ° C. Thereby, the crosslinking temperature can be brought close to the melting temperature of the resin in which the first resin and the second resin are mixed (that is, the melting temperature of the outer layer watertight material 240). As a result, the outer layer watertight material 240 can be sufficiently melted in the cross-linking step, and the outer layer watertight material 240 can be stably adapted between the conductor 100 and the insulating layer 300.

  The insulated wire 10 of this embodiment is manufactured by the above.

(4) Effects according to the present embodiment According to the present embodiment, the following one or more effects are achieved.

(A) According to the present embodiment, the base resin of the outer layer watertight material 240 of the present embodiment is configured by mixing two resins (first resin and second resin) including EMMA and having different characteristics from each other. Yes. The first resin has high mechanical strength, hard properties, good peelability, and low adhesion. On the other hand, the second resin has low mechanical strength, soft properties, good water tightness and good adhesion, but poor peelability. In this embodiment, the outer layer watertight material 240 includes a base resin formed by mixing the first resin and the second resin, so that the watertightness, peelability, and adhesion of the insulated wire 10 can be improved in a well-balanced manner. It becomes.

(B) According to the present embodiment, the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer watertight material 240 is not less than 1/4 and not more than 4 (A: B = 80: 20-20: 80). When the ratio B / A of the weight B of the second resin to the weight A of the first resin is ¼ or more, the outer layer watertight material 240 is prevented from becoming excessively hard, and the watertightness is maintained while keeping the peelability. In addition, adhesion can be improved. In addition, when the ratio B / A of the weight B of the second resin to the weight A of the first resin is 4 or less, the outer layer watertight material 240 is suppressed from being excessively soft, while maintaining watertightness and adhesion. , Skin peelability can be improved. As a result, it is possible to make the characteristics of the outer layer watertight material 240 of the present embodiment equal to or more than the characteristics of the outer layer watertight material including EEA.

(C) According to this embodiment, the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer watertight material 240 is preferably 1 or more and 7/3 or less ( A: B = 50: 50 to 30:70). In this way, in the base resin of the outer layer watertight material 240, by mixing a relatively soft second resin more than the first resin, it is possible to stably improve the watertightness and adhesion while keeping the peelability. it can. Moreover, the manufacturing cost of the outer-layer watertight material 240 of this embodiment can be made equivalent to the manufacturing cost of the outer-layer watertight material including the EEA base resin.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment and modification of this invention were described concretely, this invention is not limited to the above-mentioned embodiment and modification, and can be variously changed in the range which does not deviate from the summary.

  In the embodiment described above, the case where the number of conductor strands 110 is 19 has been described. However, the number of conductor strands is not limited to this number, and may be, for example, 7.

  In the above-described embodiment, the case where the outer layer watertight material 240 includes vinyltrimethoxysilane as a silane coupling agent has been described. However, the outer layer watertight material may include other materials as the silane coupling agent.

  In the above-described embodiment, the case where the outer layer watertight material 240 includes dicumyl peroxide as a crosslinking agent has been described, but the outer layer watertight material may include other materials as a crosslinking agent.

  In the above-described embodiment, the case where the outer layer watertight material 240 includes dibutyltin dilaurate as a catalyst has been described. However, the outer layer watertight material may include other materials as a catalyst.

  In the above-described embodiment, the case where the outer-layer watertight material 240 includes thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] as an anti-aging agent has been described. The watertight material may contain other materials as an anti-aging agent.

  In the above-described embodiment, the case where the inner layer watertight material base resin of the inner layer watertight material 220 includes EEA has been described. However, the inner layer watertight material base resin may include other materials.

  In the above-described embodiment, the case where the conductor forming step and the inner layer watertight material forming step are performed simultaneously has been described. However, after the conductor forming step is performed, the inner layer watertight material may be press-fitted from the outside of the conductor.

  In the above-described embodiment, the case of mixing the pellets of the first resin and the pellets of the second resin with the metering mixer 530 in the outer-layer water-tight material forming step has been described. A resin pellet in which the second resin is mixed at a predetermined ratio may be prepared in advance.

  Next, examples according to the present invention will be described together with comparative examples.

(1) Production of insulated wires The insulated wires according to Examples 1 to 6 and Comparative Examples 1 and 2 were produced as follows.

(conductor)
Conductor strand: Hard copper wire Conductor strand outer diameter: 2.00mm
Number of conductor wires: 19 Conductor cross-sectional area: 80 mm ²
(Inner watertight material)
Base resin: second resin (see Table 1)
Additives are the same as the following outer layer watertight materials (outer layer watertight materials)
Base resin: See Table 2 (100 parts by weight)
Color batch: PE-M 10H397 (1.2 parts by weight) manufactured by Dainichi Seika Kogyo Co., Ltd.
Silane coupling agent: Shin-Etsu Chemical Co., Ltd. KBM-1003 (1.25 parts by weight)
Crosslinking agent: NOF Corporation DCP (0.094 parts by weight)
Catalyst: Neostan (registered trademark) U-100 (0.05 parts by weight) manufactured by Nitto Kasei Co., Ltd.
Anti-aging agent: Irganox (registered trademark) 1035 (0.15 parts by weight) manufactured by BASF
Outer layer watertight material thickness: 0.2mm
(Insulating layer)
Material: Crosslinked polyethylene Insulation layer thickness: 2.5mm

  In addition, the 1st resin used for the base resin of the outer-layer watertight material of Examples 1-6 and Comparative Examples 1 and 2 is Sumitomo Chemical Co., Ltd. Aklift (registered trademark) WH206, and the second resin is manufactured by Sumitomo Chemical Co., Ltd. There is ACLIFT (registered trademark) WK307. The characteristics of the first resin and the second resin are shown in Table 1 below.

  Table 2 below shows the composition of the base resin of the outer layer watertight material in Examples 1 to 6 and Comparative Examples 1 and 2, and the evaluation results in Examples 1 to 6 and Comparative Examples 1 and 2. As a reference example, Table 2 also shows the evaluation results of an insulated wire having an outer layer watertight material containing EEA as a base resin.

(2) Evaluation (Rainwater penetration test)
Samples prepared by cutting the insulated wires of Examples 1 to 6 and Comparative Examples 1 and 2 by a predetermined length (for example, 0.8 m) are prepared. Water pressure of 0.5 atm was applied to one end of this sample for 24 hours, and the penetration distance of water from one end was measured. As a result of the rainwater infiltration test, the case where there was no water leakage from the other end was evaluated as ◯, and the case where there was water leakage from the other end was evaluated as x.

(Adhesion test (camlar tensile test))
The tensile test was performed under the conditions where the insulated wires of Examples 1 to 6 and Comparative Examples 1 and 2 were gripped by the camler, the temperature was normal temperature and 40 ° C., the tensile load was 4.17 kN, and the application time was 10 minutes. went. As a result of the Kamler tensile test, the case where there was no displacement of the insulating layer was evaluated as ◯, the case where the displacement of the insulating layer was more than 0 mm and 50 mm or less, Δ, and the case where the displacement of the insulating layer was more than 50 mm.

(Peeling test)
In the insulated wires of Examples 1 to 6 and Comparative Examples 1 and 2, the peelability test was performed by stripping the outer layer watertight material and the insulating layer with a knife under the conditions of 0 ° C., room temperature, and 40 ° C. As a result of the peel test, the case where the outer layer water-tight material was peeled off from the conductor without any residue was evaluated as ◯, and the case where at least a part of the outer layer water-tight material remained on the conductor surface was evaluated as x.

(Heating deformation characteristics test)
From the finished products of the insulated wires of Examples 1 to 6 and Comparative Examples 1 and 2, a test piece having a specified length made of an insulating layer containing an outer layer watertight material was collected, and the temperature was set to 120 ° C. with respect to this test piece. The weight loss rate was measured under the condition where the time was 30 minutes.

(3) Results First, the results of Examples 1 to 6, the results of Comparative Examples 1 and 2, and the results of the reference example are compared.

  In the comparative example 1 in which the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer watertight material is less than 1/4 (A: B = 100: 0), The insulation layer was misaligned. In Comparative Example 1, since the base resin of the outer layer water-tight material was composed only of the relatively hard first resin, it is considered that the outer layer water-tight material became excessively hard and the adhesion was lowered. Further, in Comparative Example 2 in which the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer watertight material was more than 4 (A: B = 0: 100), the temperature was 40 ° C. In the peelability test, a part of the outer layer watertight material remained on the conductor surface. In Comparative Example 2, since the base resin of the outer layer watertight material was composed only of the relatively soft second resin, it is considered that the outer layer watertight material became excessively soft and the peelability was reduced.

  In the reference example using EEA as the base resin for the outer layer watertight material, the results of rainwater infiltration, room temperature adhesion, peelability, and heat deformation characteristics were good. There was a misalignment.

  On the other hand, the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer watertight material is 1/4 or more and 4 or less (A: B = 80: 20 to 20:80). In Examples 1 to 6, rainwater infiltration, adhesion, peelability, and heat deformation characteristics were all good. Moreover, the result of Examples 1-6 was equivalent to the result of the reference example which used EEA for the base resin of the outer layer watertight material in all characteristics.

  Therefore, as a base resin for the outer layer watertight material, by mixing two resins (first resin and second resin) that include EMMA and have different characteristics from each other, the watertightness, peelability, and adhesion of the insulated wire are balanced. It was confirmed that it could be improved. Further, by setting the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer water-tight material to be not less than 1/4 and not more than 4, the characteristics of the outer-layer water-tight material can be changed to It was confirmed that it can be equal to or better than the characteristics of the watertight material.

  Next, Examples 3 to 5 are compared with other examples.

  Example 3 in which the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin of the outer layer watertight material was 1 or more and 7/3 or less (A: B = 50: 50 to 30:70) In ˜5 (details are not shown in Table 2), rainwater infiltration, adhesion, and peelability were stable and good compared to other examples. Therefore, by setting the ratio B / A of the second resin weight B to the first resin weight A in the base resin of the outer layer water-tight material to be 1 or more and 7/3 or less, water-tightness and adhesiveness are maintained while keeping the peelability. It was confirmed that can be improved stably.

<Preferred embodiment of the present invention>
Hereinafter, preferred embodiments of the present invention will be additionally described.

(Appendix 1)
According to one aspect of the invention,
A conductor provided by twisting a plurality of conductor strands;
An inner layer watertight material filled between the plurality of conductor wires;
An outer layer watertight material provided so as to cover the conductor and the outer periphery of the inner layer watertight material;
An insulating layer provided so as to cover the outer periphery of the outer layer watertight material,
The outer layer watertight material is
A first resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 18% by weight or more and less than 22% by weight;
A second resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 22% by weight or more and less than 28% by weight, and a base resin obtained by mixing
A watertight insulated wire in which the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin is 1/4 or more and 4 or less is provided.

(Appendix 2)
The watertight insulated wire according to appendix 1, preferably,
The ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin is 1 or more and 7/3 or less.

(Appendix 3)
The watertight insulated wire according to appendix 1 or 2, preferably,
The melt flow rate of the first resin is 1 g / 10 min or more and less than 3 g / 10 min when the measurement temperature is 190 ° C. and the load is 2.12 N.
The melt flow rate of the second resin is 6 g / 10 min or more and less than 8 g / 10 min when the measurement temperature is 190 ° C. and the load is 2.12 N.

(Appendix 4)
The watertight insulated wire according to any one of appendices 1 to 3, preferably,
The durometer hardness of the first resin type A is 75 or more and less than 92,
The durometer hardness of Type A of the second resin is 70 or more and less than 86.

(Appendix 5)
The watertight insulated wire according to any one of appendices 1 to 4, preferably,
The melting temperature of the first resin measured in accordance with JISK7121 is 77 ° C or higher and lower than 95 ° C,
The melting temperature of the second resin measured in accordance with JISK7121 is 72 ° C. or higher and lower than 88 ° C.

(Appendix 6)
The watertight insulated wire according to any one of appendices 1 to 5, preferably,
The insulating layer includes polyethylene or cross-linked polyethylene.

(Appendix 7)
The watertight insulated wire according to any one of appendices 1 to 6, preferably,
The inner layer watertight material includes an inner layer watertight material base resin made of an ethylene ethyl acrylate copolymer.

(Appendix 8)
According to another aspect of the invention,
Forming a conductor by twisting a plurality of conductor wires; and
Filling an inner layer watertight material between the plurality of conductor strands;
Forming an outer layer watertight material so as to cover an outer periphery of the conductor and the inner layer watertight material;
Forming an insulating layer so as to cover the outer periphery of the outer layer watertight material,
In the step of forming the outer layer watertight material,
A first resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 18% by weight or more and less than 22% by weight;
Forming the outer layer watertight material with a base resin obtained by mixing a second resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 22 wt% or more and less than 28 wt%,
There is provided a method for producing a watertight insulated wire in which the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin is ¼ or more and 4 or less.

(Appendix 9)
The method for producing a watertight insulated wire according to appendix 8, preferably,
The step of forming the conductor and the step of forming the inner layer watertight material are simultaneously performed.

(Appendix 10)
The method for producing a watertight insulated wire according to any one of appendices 8 and 9, preferably,
After the step of forming the insulating layer, the inner layer watertight material, the outer layer watertight material, and a crosslinking step of crosslinking the insulating layer,
In the crosslinking step,
The crosslinking temperature is a temperature between the melting temperature of the first resin and the melting temperature of the second resin.

10 Insulated wire (Watertight insulated wire)
DESCRIPTION OF SYMBOLS 100 Conductor 110 Conductor strand 220 Inner layer watertight material 240 Outer layer watertight material 300 Insulating layer (insulator, insulating coating layer)
510 inner layer watertight material extruder 530 metering mixer 540 outer layer watertight material extruder 560 insulating layer extruder

Claims (6)

A conductor provided by twisting a plurality of conductor strands;
An inner layer watertight material filled between the plurality of conductor wires;
An outer layer watertight material provided so as to cover the conductor and the outer periphery of the inner layer watertight material;
An insulating layer provided so as to cover the outer periphery of the outer layer watertight material,
The outer layer watertight material is
A first resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 18% by weight or more and less than 22% by weight;
A second resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 22% by weight or more and less than 28% by weight, and a base resin obtained by mixing
The watertight insulated wire in which the ratio B / A of the weight B of the second resin to the weight A of the first resin in the base resin is 1/4 or more and 4 or less.   The watertight insulated wire according to claim 1, wherein a ratio B / A of a weight B of the second resin to a weight A of the first resin in the base resin is 1 or more and 7/3 or less. The melt flow rate of the first resin is 1 g / 10 min or more and less than 3 g / 10 min when the measurement temperature is 190 ° C. and the load is 2.12 N.
The watertight insulated wire according to claim 1 or 2, wherein the melt flow rate of the second resin is 6 g / 10 min or more and less than 8 g / 10 min when the measurement temperature is 190 ° C and the load is 2.12 N. The durometer hardness of the first resin type A is 75 or more and less than 92,
The watertight insulated wire according to any one of claims 1 to 3, wherein the durometer hardness of the second resin type A is 70 or more and less than 86. The melting temperature of the first resin is 77 ° C. or higher and lower than 95 ° C.,
The watertight insulated wire according to any one of claims 1 to 4, wherein a melting temperature of the second resin is 72 ° C or higher and lower than 88 ° C. Forming a conductor by twisting a plurality of conductor wires; and
Filling an inner layer watertight material between the plurality of conductor strands;
Forming an outer layer watertight material so as to cover an outer periphery of the conductor and the inner layer watertight material;
Forming an insulating layer so as to cover the outer periphery of the outer layer watertight material,
In the step of forming the outer layer watertight material,
A first resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 18% by weight or more and less than 22% by weight;
Forming the outer layer watertight material with a base resin obtained by mixing a second resin containing an ethylene methyl methacrylate copolymer having a methyl methacrylate content of 22 wt% or more and less than 28 wt%,
The manufacturing method of the watertight insulated wire which makes ratio B / A of the weight B of the said 2nd resin with respect to the weight A of the said 1st resin in the said base resin 1/4 or more and 4 or less.

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