JPH0133635Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a metal laminate tape. [Conventional technology and its problems] In rubber-plastic insulated power cables, moisture infiltrates the insulator from the outside through the cable's plastic anti-corrosion layer, and eventually forms water trees, boat trees, etc. in the insulator layer. This can cause water absorption and deterioration, which can significantly reduce the insulation performance of the cable. For this reason, so-called water-shielding cables or chemical-resistant cables have been developed in which a water-shielding layer is provided with a metal laminate tape directly under the plastic anti-corrosion layer. The structure of the metal laminate tape used for this purpose is such that a metal foil and a reinforcing layer are bonded together using a thermosetting resin, and the surface of the tape is further coated with a thermoplastic resin. Here, the reinforcing layer is polyester, nylon, hard
It is made of PVC etc. The thermoplastic resin coated on the surface has good compatibility with adherends such as cables, and adhesive resins modified from olefin resins such as polyvinyl chloride and polyethylene are used. The thermoplastic resin melts due to the heat generated during cable manufacturing, thereby bonding the metal laminate tape and the adherend. As metal foil,
Lead foil with excellent corrosion resistance and a thickness of about 20 to 100 μm is used. When an offset test is performed on a rubber-plastic insulated power cable with a water-blocking layer made of metal laminate tape, cracks occur in the lead foil that makes up the metal laminate tape relatively early in the test, causing the cable to break. Ta. Here, the offset test is a heat cycle of 90°C RT (room temperature
This is a test in which the cable is repeatedly stretched and contracted while applying a certain room temperature. The present invention has been made in view of these points, and has developed a metal laminate tape that can improve the fatigue characteristics of the water-blocking layer of rubber-plastic insulated power cables. We investigated the high-temperature expansion and contraction characteristics of the cable by intensively examining the fatigue deterioration of the metal laminate tape in the offset test described above. As a result, when a thermosetting resin is used as the adhesive layer between the metal foil and the reinforcing layer, the anticorrosive layer becomes soft and has almost no strength, whereas the metal laminate tape is integrated with the reinforcing layer. It has become clear that the metal foil does not lose its strength at all, and as a result, stress concentration increases, which accelerates fatigue deterioration of the metal foil. That is, at high temperatures of 50 to 90°C, the strength of the anticorrosion layer made of polyethylene, polyvinyl chloride, etc. decreased significantly, but the strength of the metal laminate tape bonded to the anticorrosion layer showed almost no decrease in strength. For this reason, the stress concentration force in the metal laminate tape became large, and as a result, the lead foil suffered early fatigue failure. This is because in conventional laminated tapes, the melting point of the adhesive layer on the reinforcing layer is the lowest than that of the other adhesive layers, so when subjected to expansion and contraction at high temperatures in the offset test, the adhesive layer partially becomes protective. It is thought that the metal foil peels off from the food layer, stress concentration occurs in the peeled part, and cracks occur in the metal foil. [Means for Solving the Problems] In the present invention, a reinforcing layer and a third adhesive layer are sequentially formed on one side of a metal foil via a first adhesive layer, while the other side of the metal foil is In a metal laminate tape having a second adhesive layer formed on a surface thereof, the first,
Both of the second and third adhesive layers are formed of thermoplastic resin, and the melting points of the first, second, and third adhesive layers are such that the melting points of the first adhesive layer are lower than the third adhesive layer. <Second
This is a metal laminate tape characterized by having adhesive layers of increasing height in order of height. Here, as the reinforcing material layer, polyester, nylon, polypropylene, hard vinyl, etc., which have excellent heat resistance and high strength, are used, and the thickness thereof is 20~20 mm.
Set to a range of 120μm. The type of thermoplastic resin in the reinforcing material layer and the adhesive layer on the metal foil is desirably set appropriately depending on the material (for example, polyethylene or polyvinyl chloride) of the anticorrosive layer that is the adherend. [Function of the invention] According to the metal laminate tape according to the invention,
All the adhesive layers are made of thermoplastic resin, and the melting point of the adhesive layer between the metal foil and the reinforcing material layer is the lowest than other adhesive layers, so when subjected to high temperature expansion and contraction in the offset test, the reinforcing material layer and the metal The area between the foils is the first to peel. However, since the melting point of the adhesive layer attached to the metal foil side is 100°C or higher, no peeling occurs between the adhesive layer and the metal foil. In addition, since the adhesive layer attached to the reinforcing material layer has a higher melting point than the adhesive layer between the reinforcing material layer and the metal foil, the reinforcing material layer adheres to the anticorrosion layer, and the stress is mainly applied to the reinforcing material layer. The anticorrosive layer takes care of this. Plastic materials do not deteriorate due to fatigue and therefore do not deteriorate under stress. On the other hand, on the metal foil side, since the thickness of the metal foil is extremely thin at 10 to 100 μm, almost no stress concentration occurs at the stage where the adhesive layer between the reinforcing layer and the metal foil is separated. In addition, this adhesive layer is made of thermoplastic resin and has a low melting point of 70 to 100°C.
When the temperature returns from high temperature to room temperature due to the cable heat cycle, the reinforcing material layer and the metal foil are bonded together. [Effects of the invention] As described above, according to the metal laminate tape according to the invention, the reinforcing material layer and the metal foil peel off at high temperatures, and the reinforcing material layer remains on the anticorrosion layer side, sharing stress,
At low temperatures, they become integrated. For this reason, metal foil hardly experiences fatigue at high temperatures. As a result, the metal foil does not deteriorate even when subjected to repeated expansion and contraction during offset testing. [Example] Next, an example of the present invention and a comparative example conducted for comparison with the example will be described. Examples 1 and 2 Comparative Examples 1 to 4 As shown in the figure, a reinforcing material layer 2 made of a polyester film 100 μm thick and a first adhesive layer 3 were applied on one side of a metal foil 1 made of lead foil 50 μm thick. A second adhesive layer 4 is bonded to the other surface of the metal foil 1.
A third adhesive layer 5 was provided on the reinforcing material layer 2 to obtain a metal laminate tape 10 . Here, as the first adhesive layer 3, one based on EAA (ethylene/acrylic acid copolymer) was used (as shown in Table 1 below for Examples 1 and 2 and Comparative Examples 1 to 4). , with different melting points). The second adhesive layer 4 is based on EEA (ethylene/ethyl acrylate copolymer) (with different melting points as shown in Table 1 below for Examples 1 and 2 and Comparative Examples 1 to 4). ), and the third adhesive layer 5 is EVA (ethylene/vinyl acetate copolymer).
(Examples 1 and 2, Comparative Examples 1-
4 had different melting points as shown in Table 1 below. ) were used respectively.

[Table] Using the metal laminate tapes of Examples 1 and 2 and Comparative Examples 1 to 4 produced as described above, water-shielding 66K VCV cables were produced in the following manner.
A metal shielding layer made of copper wire is provided on the outside of the cable core, and a holding tape is wrapped around the outside of the metal shielding layer, and then the metal laminate tapes of Examples 1 and 2 and Comparative Examples 1 to 4 are placed on the second adhesive layer side of the cable core. Place it on the side and wrap it vertically. After heat-sealing the lap part, place it on top of this.
Extrude the anticorrosion layer made of PVC composition at 200℃,
Using the heat generated at that time, the PVC anticorrosive layer and metal laminate tape were bonded together to obtain six types of water-shielding CV cables. For each of the six types of water-shielded CV cables obtained in this way, the conductor was heated by energizing the conductor,
While applying a heat cycle at 90°C RT, one end was fixed and expansion and contraction was applied from the other end. The amount of expansion and contraction was set to 40 mm, and the cycles were applied 7300 times, 18250 times, and 36500 times.Then, the water-shielding CV cable was taken out and disassembled, and the metal foil 1 of the metal laminate tape was examined for cracks, as shown in Table 2 below. The results shown are obtained.

[Table] As is clear from Table 2, when the metal laminate tapes of Examples 1 and 2 were used, there was no expansion or contraction.
No cracks were observed in Metal Foil 1 even after 36,500 times of expansion and contraction, but when the metal laminate tapes of Comparative Examples 1 to 4 were used, the metal foil 1 had already broken down after 18,250 times of expansion and contraction in all cases. Cracks were observed in Foil 1.

[Brief explanation of drawings]

The figure is an explanatory diagram showing the structure of a metal laminate tape. DESCRIPTION OF SYMBOLS 1... Metal foil, 2... Reinforcing material layer, 3... First adhesive layer, 4... Second adhesive layer, 5... Third adhesive layer, 10 ... Metal laminate tape.

Claims (1)

[Claims for Utility Model Registration] (1) A reinforcing layer and a third adhesive layer are sequentially formed on one side of the metal foil with a first adhesive layer interposed therebetween,
On the other hand, in the metal laminate tape in which a second adhesive layer is formed on the other surface of the metal foil, the first,
Both of the second and third adhesive layers are formed of thermoplastic resin, and the melting points of the first, second, and third adhesive layers are such that the first adhesive layer is less than the third adhesive layer. A metal laminate tape characterized in that the layers are successively higher in the order of <second adhesive layer. (2) the melting point of the first adhesive layer is 70 to 100°C;
The metal laminate tape according to claim 1, wherein the second adhesive layer has a melting point of 100° C. or higher. (3) The metal laminate tape according to claim 1, wherein the metal foil is a lead foil or lead alloy foil with a thickness of 10 to 100 μm.