JP4812333B2 - Watertight material and outdoor cross-linked polyethylene insulated wire using the same - Google Patents

Description

  The present invention relates to a cross-linked polyethylene insulated wire used for outdoor wiring, and a watertight material used for preventing flooding of the cross-linked polyethylene insulated wire.

Insulated wires used for outdoor wiring are formed by extruding and covering an insulating layer on a conductor in which a plurality of strands are twisted, in order to prevent intrusion of rainwater or the like into the conductor in which the plurality of strands are twisted In addition, a watertight treatment is performed between the conductor wires. For example, when twisting the strands, after filling the jelly-like resin admixture and curable liquid rubber, or twisting the strands into a conductor, a water-tight resin composition with low viscosity is obtained. This is done by press-fitting. Furthermore, a tape-like or string-like body made of a resin composition in which a water-absorbing material such as calcium chloride is blended with a thermoplastic resin is twisted together with the strands, or the above-mentioned resin composition is extrusion coated onto the strands. After that, a method of compressing with a die or the like and filling between the wires is performed. Further, as the watertight material, not only the adhesion between the conductor and the insulator but also the peelability is required so that the watertight material does not remain on the conductor when the insulator is peeled off. For this reason, a watertight material mainly composed of an ethylene-based resin and a hot-melt resin as described in Patent Document 1 has been proposed. As the ethylene-based resin and hot melt resin, an ethylene / acrylic acid ester copolymer is described, but the characteristics of the ethylene / acrylic acid ester copolymer are not specified. The material has a problem that it is difficult to adjust the balance with the watertight property because there are many additives. Further, Patent Document 2 discloses a watertight material in which maleic anhydride-modified polyolefin and carbon black are blended with an olefin resin. An ethylene-ethyl acrylate copolymer is described as the olefin resin. However, even in this Patent Document 2, the characteristics of the ethylene-ethyl acrylate copolymer are not specified, and there are problems that it is difficult to adjust the balance with the watertight characteristics due to the large amount of additives. Therefore, there has been a demand for a watertight material and a watertight insulated electric wire that improve these problems.
Japanese Patent Laid-Open No. 2001-23450 JP 2002-175730 A

  Accordingly, the problem to be solved by the present invention is to provide a watertight material that maintains sufficient watertightness and has excellent peelability when used as a watertight insulated wire, and a cross-linked polyethylene insulated wire for outdoor use having the above characteristics. It is to provide.

The problem to be solved is an ethylene / ethyl acrylate copolymer or ethylene / ethyl acrylate copolymer having a melt mass flow rate (190 ° C., 2.16 kg) of 57 to 275 g / 10 min as described in claim 1. The mixture of the coalescence is solved by forming a watertight material composed of a reaction product crosslinked with dicumyl peroxide (hereinafter referred to as DCP) to a degree of crosslinking of 80 to 86%. Further, as described in claim 2, the water-tight material according to claim 1 is solved by using an outdoor cross-linked polyethylene insulated wire filled between conductor wires.

  The present invention relates to an ethylene / ethyl acrylate copolymer (hereinafter referred to as EEA) or a mixture of ethylene / ethyl acrylate copolymers (hereinafter referred to as EEA) having a melt mass flow rate (190 ° C., 2.16 kg) (hereinafter referred to as MFR) of 57 to 275 g / 10 min. EEA mixture) is a watertight material that is chemically cross-linked by DCP to a degree of cross-linking of 80 to 86%, so that the adhesion between the conductor and the insulator layer is good and the water-tightness is excellent, and the conductor wires are sufficiently filled. be able to. Moreover, since it bridge | crosslinks and uses for a specific bridge | crosslinking degree, when it uses for a watertight insulated electric wire, the peelability is favorable. And by using the above-mentioned cross-linked polyethylene insulated wire (hereinafter referred to as cross-linked PE insulated wire) filled with the above-mentioned water-tight material between conductor strands, it functions as a water-tight insulated wire having excellent water-tightness, such as during laying work. Has moderate peelability.

  The present invention is described in detail below. The water-tight resin composition described in claim 1 is an EEA or EEA mixture having an MFR (190 ° C., 2.16 kg) of 57 to 275 g / 10 min, and is chemically crosslinked by DCP to a degree of crosslinking of 80 to 86%. It is a watertight material used. As described above, since EEA having a large MFR is used as the base resin, it is excellent in water tightness, and is used after being crosslinked to a specific degree of crosslinking. An insulated wire is obtained.

  As described above, EEA is frequently used as a watertight material for watertight insulated wires, but EEA having a large MFR is considered preferable because it has high watertightness. However, when such a base resin is used as a watertight material, there is a problem that the watertight material remains on the conductor when the watertight insulated wire is peeled off. This is because the EEA is soft and breaks without being able to withstand the force applied when the skin is peeled off. For this reason, it is conceivable to use a resin having a high breaking strength, but it is generally known that the breaking strength decreases as the MFR increases. Therefore, a watertight material having a large MFR and excellent watertightness and sufficient breaking strength was examined. That is, using an EEA having an MFR (190 ° C., 2.16 kg) of 275 g / 10 min and examining how the peelability changes by cross-linking the EEA to various degrees of cross-linking was examined by experimental examples. For crosslinking, DCP was used, and watertight materials having a degree of crosslinking of 72%, 81%, 86%, (88%) were produced. Furthermore, an uncrosslinked watertight material was also prepared. Subsequently, the watertight material was molded on 19 twisted conductors, and then peelability was examined. As shown in Table 1, it was confirmed that when a watertight material having a degree of crosslinking by DCP of about 80 to 86% was used, the watertight material did not remain on the conductor, which was preferable. That is, when the degree of crosslinking was 72%, a slight amount of watertight material remained, and when it was not crosslinked, a considerable amount of residue was observed. In addition, when the degree of crosslinking was 88%, the peelability was acceptable, but water tightness became a problem because the degree of crosslinking was too large.

  From the above experimental results, when EEA is used as a base resin for a watertight material, it is possible to obtain a watertight material with excellent peelability by chemical crosslinking using DCP at a crosslinking degree of 80 to 86%. Since it was understood, the MFR range, water tightness and peelability of EEA alone or EEA mixture were examined. The MFR (190 ° C., 2.16 kg) value was adjusted to the desired value by mixing various MFR EEAs in various proportions. That is, a crosslinked PE insulated wire was prepared using the compositions of Examples and Comparative Examples shown in Table 2, and the MFR (190 ° C., 2.16 kg) range, water tightness and peelability of EEA or EEA mixture were confirmed. did.

Using EEAs with different MFRs listed in Table 2, EEA alone or a mixture thereof (expressed in% by mass) is used as a base resin with a different MFR, and a crosslinking aid (of Nippon Kasei Co., Ltd.) is added to 100 parts by mass of this base resin. TAIC) 3.2 parts by mass, as an anti-aging agent, 0.5 parts by mass of Nocrack 300 from Ouchi Shinko Chemical Industry Co., Ltd. and DCP were added as required to obtain a watertight material. EEA is A-707 (ethylene acrylate content: 25 mass%, 190 ° C., MFR: 275 g / 10 min at 2.16 kg) and A-713 (ethylene ethyl acrylate content: 25) manufactured by Mitsui DuPont Polychemical Co., Ltd. Mass%, 190 ° C., MFR at 2.16 kg is 20 g / 10 min). Next, this watertight material is filled between 19 stranded conductors (conductor size 60 cm ² ) coated with uncrosslinked polyethylene blend (hereinafter referred to as PE blend) to which DCP has been added, and then the PE blend is subjected to a crosslinking treatment. As a result, watertight materials having different degrees of crosslinking were obtained.

  Using the crosslinked PE insulated wire produced as described above, watertightness and peelability tests were performed. First, after the above-mentioned cross-linked PE insulated wire was subjected to 5 reciprocal bending at a 10-fold diameter, as a water tightness test, it was placed in water at 23 ° C. so that one end 50 mm of the cross-linked PE insulated wire had a water pressure of 0.05 MPa. It is immersed for 24 hours and the water penetration distance (mm) is measured. The case where it penetrates 2000 mm or more is unacceptable. In the test results, the penetration distance of water was described as the immersion length (mm). Also, the peelability is indicated by ○ when the case where the skin is peeled off using a tool GS peeler and the watertight material does not remain on the three conductors is passed, and the watertight material remains on the three conductors. The result in which the evaluation is seen as “failed” is indicated by “x”, and the case where the evaluation varies is indicated by “Δ”. The degree of cross-linking of the watertight material conformed to the rubber / plastic insulated wire test method of JIS C3005, 4.25. Further, MFR (190 ° C., 2.16 kg) conformed to JIS K7210 plastic-thermoplastic melt mass flow rate (MFR) and melt volume flow rate (MVR) test methods. The results are shown in Table 2.

  As is apparent from Table 2, as in the present invention, the MFR (190 ° C., 2.16 kg) is 57 to 275 g / 10 min of EEA or EEA mixture, and the degree of crosslinking is 80 to 86% by chemical crosslinking with DCP. As shown in Examples 1 to 7, the crosslinked PE insulated wire using the watertight material was practically excellent in watertightness and peelability. On the other hand, the cross-linked PE insulated wire using the watertight material outside the scope of the present invention described in Comparative Examples 1 to 7 has a problem in either watertightness or peelability. This will be described in more detail. As shown in Example 1, when using a watertight material obtained by crosslinking EEA with an MFR of 275 g / 10 min to a crosslinking degree of 86%, the water immersion length is 900 mm or less, the watertightness is excellent, and the peelability is also good. It turns out that it is a good thing. Further, as shown in Examples 2 to 4, when a watertight material having an EEA mixture with an MFR of 187 g / 10 min and a crosslinking degree of 80 to 86% is used, the water immersion length is 1000 mm or less and is sufficiently watertight. It can be seen that it has good peelability and workability. Further, as shown in Examples 5 and 6, when a watertight material having an EEA mixture with an MFR of 74 g / 10 min and a crosslinking degree of 84 and 86% was used, the water immersion length was 700 mm or less and the watertightness was sufficient. It can be seen that it has good peelability and workability. In addition, as shown in Example 7, when a watertight material obtained by crosslinking EEA having an MFR of 57 g / 10 min to a crosslinking degree of 86% is used, the water immersion length is 700 mm or less and the watertightness is excellent, and the peelability is also good. It can be seen that the workability is good.

  On the other hand, as in Comparative Example 1, even when the MFR was 275 g / 10 min, when uncrosslinked, when the skin was peeled off, a watertight material remained on the conductor and there was a problem in the peelability. Further, even when the MFR is 275 to 57 g / 10 min as in Comparative Examples 2 to 6, when the degree of crosslinking is as low as 70%, 78%, 73%, 75% and 76%, there is a problem in the peelability. there were. Further, as in Comparative Example 7, even when the MFR was 57 g / 10 min, when the degree of crosslinking was as high as 88%, there were some cases where the water immersion length reached 2000 mm and there was a problem in water tightness. Based on the above results, a watertight material having an MFR (190 ° C., 2.16 kg) of 57 to 275 g / 10 min of EEA or EEA mixture and subjected to chemical crosslinking by DCP to a degree of crosslinking of 80 to 86% is obtained. It can be seen that it is preferable.

  As for EEA or EEA mixture, various grades can be used as long as MFR (190 ° C., 2.16 kg) is in the above-mentioned range, but ethyl acrylate amount (hereinafter referred to as EA amount) is about 10 to 35 wt%. Is preferred. EEA is used alone or as a mixture as described above. As specific products, A-704, A-713, A-709 manufactured by Mitsui-DuPont Polychemical Co., Ltd., NUC-6570, NUC-6070 manufactured by Nippon Unicar Co., Ltd., and the like can be used. In addition, the watertight material includes cross-linking aids such as TAIC of Nippon Kasei Co., Ltd., thiobisphenol-based antioxidants such as NOCRACK 300 (Ouchi Shinsei Chemical Industry Co., Ltd.) and trade names of Irganox 1010 (Ciba Specialty Chemicals) and other hindered phenol antioxidants, carbon black such as FEF carbon (made by Tokai Carbon), neutralizers such as magnesium oxide (MgO), and other necessary additives can be blended. . And the said watertight material can be produced by well-known means, such as a pressure kneader and a twin-screw kneader, for example.

  Next, the bridge | crosslinking PE insulated wire described in Claim 2 using the said watertight material is demonstrated. An example is shown in FIG. This cross-linked PE insulated wire is used as a watertight insulated wire for outdoor use. A conductor 2 is formed by twisting a plurality of strands 1, and the watertight material 3 is filled and covered with the watertight material 3 between the strands 1. It keeps sex. And PE blend is extrusion-coated on it, it is bridge | crosslinked, the crosslinked insulator layer 4 which consists of crosslinked polyethylene is formed, and it becomes a crosslinked PE insulated wire. A specific method for producing a watertight insulated electric wire will be described. Between a stranded wire conductor made of a copper wire or the like, an MFR (190 ° C., 2.16 kg) is 57 to 275 g / 10 min in an EEA or EEA mixture having a specific amount A watertight material to which DCP is added is pressed and uncrosslinked PE blend containing a crosslinking agent is extruded and coated, and then the PE blend is chemically crosslinked, and at the same time, the watertight material has a degree of crosslinking of 80 to 86%. To be crosslinked. Thus, since it can be set as the watertight material of the target bridge | crosslinking degree simultaneously with the bridge | crosslinking process of a bridge | crosslinking PE insulator layer, the bridge | crosslinking PE insulated wire for outdoors can be produced efficiently.

  The water-tight material of the present invention is excellent in water-tightness and peelability, so that watertightness is sufficiently maintained as a cross-linked PE insulated wire for outdoor use, and it is practical because it has excellent skin-peeling properties during laying work etc. Used as a typical outdoor watertight insulated wire.

It is a schematic sectional drawing of the watertight insulated wire which shows an example of this invention.

Explanation of symbols

1 Wire 2 Conductor 3 Watertight Material 4 Insulator Layer

Claims (2)

Dicumyl peroxide having a melt mass flow rate (190 ° C., 2.16 kg) of 57 to 275 g / 10 min of ethylene / ethyl acrylate copolymer or a mixture of ethylene / ethyl acrylate copolymers has a degree of crosslinking of 80 to 86%. A water-tight material comprising a reaction product chemically cross-linked by   A cross-linked polyethylene insulated wire for outdoor use, wherein the watertight material according to claim 1 is filled between conductor wires.

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