JP2013201070A - Watertight insulated cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a watertight insulated cable having a conductor, an insulator formed on and covering the conductor, and a watertight material filled between the conductor and the insulator, and improved in both the high-temperature adhesion between the conductor and the watertight material and the easiness of the insulator being peeled.SOLUTION: The watertight insulated cable has: a rust inhibitor applied onto a conductor and including 0.4-2 mass% of a benzotriazole-based compound and 0.1-5 mass% of an epoxy-based plasticizer; and a watertight material which includes 0.1-1.0 pt.mass of magnesium stearate to 100 pts.mass of resin components including an ethylene ethyl acrylate copolymer.

Description

  The present invention relates to a watertight insulated electric wire that prevents rainwater from entering, and more particularly, to a watertight insulated electric wire that achieves both improved adhesion and peelability between a conductor and a watertight material.

  An insulated wire for outdoor wiring is a conductor in which a plurality of strands are twisted and covered with an insulator. The conductor in which these strands are twisted is a conductor to prevent rainwater from entering. A watertight material is filled between the strands and around the conductor.

  A rust preventive agent is applied to the conductor, and those containing a benzotriazole compound are known as the rust preventive agent for this purpose (Patent Documents 1 and 2).

  The watertight material is mainly composed of a resin such as ethylene / ethyl acrylate copolymer or ethylene / vinyl acetate copolymer, and stearic acid or a metal salt of stearic acid should be added to improve the peelability. It has been known. Among them, it is known that zinc stearate is preferable since a high peeling effect can be obtained with a small amount (Patent Documents 3 to 5), and it has been put into practical use.

  However, the adhesion with the insulator and the peelability are inherently incompatible with each other, and when a watertight material containing zinc stearate is used for the conductor coated with the rust preventive agent as described above, a high temperature (40 There was a problem that the adhesiveness at a temperature of ℃ or higher was inferior, and the conductor was discolored due to corrosion in the heat and water resistance test.

  The present inventors have found that adhesiveness and peelability can be made compatible by using magnesium stearate as a release agent for watertight materials, and based on this finding, each characteristic required for watertight insulated wires is improved in a well-balanced manner. The development was progressed to provide the electric wire.

  In this regard, Patent Document 4 lists metal stearates that can be used as a release agent, and includes magnesium stearate. However, it is stated that zinc stearate is preferred among them, and only zinc stearate is used in the examples.

  As described above, specific means for obtaining a watertight insulated electric wire having both adhesiveness and peelability using magnesium stearate has not yet been disclosed.

Japanese Patent Publication No. 3-71516 Japanese Examined Patent Publication No. 3-71515 JP 2007-35456 A JP-A-8-203343 JP-A-1-95148

  The present invention has been made in view of the above, and an object of the present invention is to provide a watertight insulated electric wire that achieves both adhesion and peelability between a conductor and a watertight material, and is excellent in watertightness and heat waterproofness.

  The watertight insulated wire of the present invention is a watertight insulated wire in which an insulator is coated on a conductor formed by twisting a plurality of strands, and a watertight material is filled between the plurality of strands and between the conductor and the insulator. And in order to solve said subject, the rust inhibitor which contains a benzotriazole type compound 0.4-2 mass% and epoxy-type plasticizer 0.1-5 mass% in a conductor, and the remainder is a solvent. It is assumed that the applied watertight material contains 0.1 to 1.0 parts by mass of magnesium stearate with respect to 100 parts by mass of the ethylene / ethyl acrylate copolymer.

  In the above, the melt flow rate of the resin containing the ethylene / ethyl acrylate copolymer is preferably 110 to 250.

  Moreover, as the epoxy plasticizer, epoxidized soybean oil can be suitably used.

  According to the present invention, the problems of adhesion and heat waterproofing of conventional watertight insulated wires using zinc stearate or the like as the watertight material are solved, and not only the high temperature adhesion and peelability are excellent, but also watertightness and A watertight insulated wire with improved heat waterproofness in a well-balanced manner can be obtained.

It is a schematic cross section of a watertight insulated wire for explanation of a peelability test method. It is a side view of a watertight insulated wire for explanation of a watertightness test method. It is a side view of the strand wire conductor for description of the peelability test method.

  Hereinafter, the watertight insulated wire of the present invention will be described in detail.

  The rust preventive agent used in the present invention contains a benzotriazole compound, and as the benzotriazole compound, in addition to benzotriazole, benzotriazole monoethanolamine salt, benzotriazole diethylamine salt, benzotriazole cyclohexylamine salt, Examples thereof include benzotriazole derivatives such as benzotriazole morpholine salt, bezotriazole diisopropylamine salt, and methylbenzotriazole cyclohexylamine salt. Of these, benzotriazole is preferred because it is inexpensive. Any one of these can be used alone or in admixture of two or more.

  Examples of epoxy plasticizers contained in rust inhibitors include epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized unsaturated fats such as epoxidized oil, epoxidized linseed oil fatty acid Butyl, octyl epoxy stearate, epoxy butyl stearate, epoxidized fatty acid monoester, epoxidized oleic octyl ester, epoxidized oleic decyl ester, epoxy monoester, alkyl epoxy stearate, n-alkyl epoxy stearate, isoalkyl Epoxy cyclohexane derivatives such as epoxidized unsaturated fatty acid esters such as epoxy stearate, di-2-ethylhexyl epoxy hexahydrophthalate, diisodecyl epoxy hexahydrophthalate, and cycloalkyl epoxy stearate Fine epichlorohydrin derivatives, and the like. Among them, epoxidized soybean oil is preferable because the rust prevention effect is greatly improved by addition of a small amount. These plasticizers can also be used alone or in combination of two or more.

  As content of each said component in a rust preventive agent, it is preferable that content of a benzotriazole type compound is 0.4-2 mass%, and it is more preferable that it is 0.5-1.5 mass%. . When the benzotriazole-based compound is less than 0.4% by mass, it is difficult to obtain a desired rust preventive effect. On the other hand, when it exceeds 2 mass%, there is no problem in terms of performance, but the rust prevention effect is saturated, which is economically disadvantageous.

  The content of the epoxy plasticizer is preferably 0.1 to 5% by mass. If the plasticizer is less than 0.1% by mass, problems such as peeling of the rust preventive film and partial formation of the rust preventive film occur, and sufficient rust preventive effect cannot be obtained. There is a risk that sufficient adhesion to the material may not be obtained.

  To dissolve the benzotriazole compound and the epoxy plasticizer, for example, dissolve the benzotriazole compound in an alcohol solvent such as methanol or isopropyl alcohol in advance, add the epoxy plasticizer, and mix and stir uniformly. Can be dissolved.

  The specific method for applying the rust inhibitor to the conductor is not particularly limited, and usual means such as dipping and spraying can be used. Moreover, the state of the conductor at the time of application may be a strand before twisting or a conductor in which a plurality of strands are twisted (twisted conductor), and if necessary, twist these after applying to the strand. You may apply | coat on the put together conductor.

  Next, the watertight material used in the present invention is obtained by blending at least magnesium stearate with a resin component mainly composed of an ethylene / ethyl acrylate copolymer.

  By using an ethylene / ethyl acrylate copolymer as a main component of the resin component, compatibility with polyethylene insulation and adhesion with a conductor can be obtained. However, as long as it does not deviate from the object of the present invention, other resin such as ethylene-methyl acrylate (EMA), ethylene-butyl acrylate (EBA) can be used in combination as the resin component of the watertight material. The blending ratio of the ethylene / ethyl acrylate copolymer is preferably 40% by mass or more. In the present invention, when ethylene vinyl acetate copolymer (EVA) is used in combination, corrosion may occur due to the generation of acid, so it is preferable not to use it.

  The ethyl acrylate content of the ethylene / ethyl acrylate copolymer is preferably 20 to 35% by weight. If it is less than 20% by weight, the adhesion to the conductor is lowered, and if it exceeds 35% by weight, it is difficult to process.

  The melt flow rate (MFR) of the ethylene / ethyl acrylate copolymer is preferably 110 to 250. If it is less than 110, the watertight material is not partially filled, and if it exceeds 250, the filled watertight material comes off.

  In this invention, 0.1-1.0 mass part is preferable with respect to 100 mass parts of said resin components, and, as for content of magnesium stearate of a watertight material, 0.3-0.7 mass part is more preferable. If the amount is less than 0.1 parts by mass, it is difficult to obtain a desired peeling effect, and if it exceeds 1.0 parts by mass, the heat waterproof property becomes insufficient.

  Moreover, compounding agents, such as antioxidant, a crosslinking agent, a crosslinking adjuvant, can be added to the said watertight material as needed.

  The method for producing the watertight insulated wire of the present invention is not particularly limited except that the above-described rust preventive and watertight material are used, and a known method can be used. For example, a watertight material in which the above components are mixed is prepared, filled between conductor wires, and then an insulator is extruded and coated to perform a crosslinking treatment.

  In the above, the method of filling the watertight material is not particularly limited, and a method of press-fitting or applying to a target object using an extruder or a gear pump is usually used.

  As an insulator, the material conventionally used for the watertight insulated wire can be used without particular limitation, and for example, cross-linked polyethylene or the like can be used.

Examples of the present invention are shown below, but the present invention is not limited to the following examples. In addition, unless otherwise specified in the following, content etc. shall be based on mass (mass part, mass%, etc.) [Examples and Comparative Examples]
A watertight material having the composition shown in Table 1 (parts by mass, converted to solid content) is prepared, and a watertight insulated electric wire is prepared using the watertight material, and the adhesion and watertightness of the wire are measured. Evaluated. Details of the watertight material, rust inhibitor, watertight insulated wire, and measurement / evaluation method are as follows. The evaluation results are shown in Table 1.

<Watertight material>
EEA1: Ethylene / ethyl acrylate copolymer (NUC-6070 manufactured by Dow Chemical Japan Co., Ltd.)
EEA2: Ethylene / ethyl acrylate copolymer (NUC-6570 manufactured by Dow Chemical Japan Co., Ltd.)
DCP: Dicumyl peroxide (Nippon Yushi Co., Ltd. Park Mill D)
Magnesium stearate: (manufactured by Sakai Chemical Industry Co., Ltd.)
Stearic zinc: (manufactured by Sakai Chemical Industry Co., Ltd.)

<Rust preventive>
Benzotriazole 1.5%
Epoxy plasticizer (Eposizer W-100-EL manufactured by DIC Corporation) 0.1%
Isopropyl alcohol 98.4%

<Watertight insulated wire>
19 conductors, which are copper wires having a diameter of 2.0 mm, were twisted to create a stranded conductor, and the rust inhibitor was applied to the surface of the stranded conductor by spraying. After the rust preventive agent is dried, the watertight material shown in Table 1 is press-fitted between the strands of the stranded wire conductor by an extruder, and the stranded wire conductor filled with the watertight material is made of crosslinked polyethylene (PE). After coating with an insulator (thickness 2.5 mm), steam crosslinking was performed to obtain a crosslinked PE insulated wire having a diameter of 15 mm.

  The MFR (190 ° C., 2.16 kg) of the watertight material was measured according to JIS K7210 “Plastics—Melt mass flow rate of thermoplastics”.

<Measurement and evaluation method>
1. Adhesion degree Cross-linked PE insulated wire is held with a special jig (Hifukumura 600) and a tensile load is applied for 10 minutes. The maximum tensile load (kgf) where the slip between the conductor and the insulator is 5 mm or less and the insulator is free of cracks and bumps. ) Was measured. The case where the maximum tensile load is less than 500 kgf is unacceptable. The test result was described as the maximum tensile load (kgf) as the degree of adhesion. The test was performed on three samples under the same conditions, and each result was shown.

2. Watertightness After stripping 500 mm of insulation from one end of cross-linked PE insulated wire, 5 reciprocating bends in a drum whose radius is 10 times the outer diameter of the wire, centering on the boundary between exposed conductor 4 and insulator 5 Then, 1000 mm of one end of the crosslinked PE insulated wire was immersed in water at 23 ° C. as shown in FIG. 2, and the water pressure was adjusted to 0.05 MPa. A water pressure application region is denoted by reference numeral 6. After maintaining for 24 hours in that state, the penetration distance (mm) of water from the end 7 of the insulator 5 was measured and described as a test result. The case where it penetrates 2000 mm or more is considered as a failure. The test was performed on three samples under the same conditions, and each result was shown.

3. Peeling property At an ambient temperature of −20 ° C., 20 ° C., and 60 ° C., peeling was performed using a dedicated tool (GS peeler), and the presence or absence of watertight material on the conductor was visually observed. As shown in FIG. 3, the case where no watertight material remains over the adjacent three conductor wires 1, 2, 3 under any of the three temperature conditions is indicated by “◯”, and the three conductors Watertight material remains across the strands, but “△” indicates that the watertight material can be completely removed within 5 seconds when rubbed with a finger. Watertight material is completely removed within 5 seconds even when rubbed with a finger. The case where peeling was not possible was indicated by “x”. In addition, the result showed the lowest thing in the evaluation obtained through each temperature.

4). Heat-resistant test After immersing the cross-linked PE insulated wire in water for 30 cm or more and heating as a heat cycle for 8 hours (4 hours or more at 90 ° C.) and 16 hours for non-heat treatment as 60 cycles, visually The discolored state of the conductor was observed. The case where no discoloration was observed was indicated by “◯”, the case where slight discoloration was observed was indicated by “Δ”, and the case where obvious brown or purple discoloration was observed was indicated by “X”.

  As can be seen from Table 1, in Examples 1 to 8, water tightness was improved with increasing amount of magnesium stearate, and peelability was also good. However, when the amount of magnesium stearate added is 0.8 parts by mass or more (Examples 5 and 6), there is a tendency for the heat and waterproof test to decrease, and when the amount added is 0.3 to 0.7 parts by mass (implementation). In Examples 2 to 4, 7, and 8), all the evaluation results were the best in balance. On the other hand, Comparative Example 1 in which no stearate was used was clearly inferior in peelability, and Comparative Example 2 in which zinc stearate was used had good peelability, but there was a problem with heat waterproofing properties. In addition, it was confirmed that the adhesion test under high temperature was greatly reduced as compared with the formulation to which magnesium stearate was added.

  The watertight insulated wire of the present invention is mainly used for outdoor wiring.

1, 2, 3 ... Conductor strand 4 ... Conductor exposed part, 5 ... Insulator, 6 ... End part of insulator 7 ... Water pressure application area of 0.05 MPa

Claims (3)

A watertight insulated electric wire in which an insulator is formed on a conductor obtained by twisting a plurality of strands, and a watertight material is filled between the plurality of strands and between the conductor and the insulator,
A rust inhibitor containing 0.4 to 2% by mass of a benzotriazole compound and 0.1 to 5% by mass of an epoxy plasticizer is applied to the conductor,
The watertight material contains 0.1 to 1.0 parts by mass of magnesium stearate with respect to 100 parts by mass of a resin component containing an ethylene / ethyl acrylate copolymer. The watertight insulated wire according to claim 1, wherein the melt flow rate of the resin containing the ethylene / ethyl acrylate copolymer is 110 to 250. The watertight insulated wire according to claim 1 or 2, wherein the epoxy plasticizer is epoxidized soybean oil.

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