JPH0461443B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to electric wires and cables provided with termite-proof properties. [Conventional technology] Control, power, communication, etc. electrical cables buried underground in termite habitats or laid underground conduits.
Accidents have occurred where cables have been damaged by termites, causing major problems in energy and information transmission.
As a countermeasure against such accidents, termite-proof wires and cables having a structure in which nylon is provided in the outermost sheath of wires and cables have been put into practical use in recent years. [Problems to be solved by the invention] The termite-proofing properties of nylon are said to have a greater effect on its physical hardness than on its chemical composition, and in fact, epoxy,
Rigid plastics such as polycarbonate and polyacetal have been proven to have excellent termite resistance. In this way, the termite-proofing properties of nylon are certain.
This nylon is applied as the outermost sheath of electric wires and cables by extrusion or tape wrapping. Electric wires and cables made of nylon over a sheath made of polyethylene or polyvinyl chloride, etc., have defects on the surface where stress tends to concentrate, such as minute foreign objects, irregularities, scratches, etc., because nylon is a rigid polymer. If it exists, there is a problem in that it becomes a starting point and easily cracks not only at room temperature but also at a high temperature of about 50° C. due to the so-called notch effect. The present invention is based on the above, and aims to provide electric wires and cables that have significantly improved crack resistance and termite resistance. [Means for Solving the Problems] The electric wire/cable of the present invention has an extruded coating layer of a composition containing only internally plasticized polyamide as a resin component formed on the outer periphery of a rubber or plastic sheath. Shore D hardness of the layer is 60
It is characterized by the above. In the present invention, internally plasticized polyamides include polyether amide block copolymers, polyester amide block copolymers, polyether ester amide block copolymers, copolymers of amide and olefin, etc., with hard segments of amide components. The material is not limited to the above, as long as it is made of a soft segment of a rubber component. Any method may be used as long as the rigidity of polyamide is improved not by a liquid softener or a blend of polymers, but by a so-called internal plasticization method such as copolymerization. Internally plasticized polyamide has superior cold resistance and impact resistance compared to, for example, an externally plasticized method using a liquid softener or a polymer blend, and is less prone to cracking even when there are notches or the like. The internally plasticized polyamide used in the present invention has a Shore D hardness of 60 or more; anything less than this is too soft and susceptible to attack by termites. Naturally, the harder the material, the better its resistance to termites. It is also possible to make internally plasticized polyamide flame retardant by adding a flame retardant or flame retardant aid, and to impart conductivity by adding a conductivity imparting agent, as long as the above-mentioned hardness, cold resistance, and impact resistance are not impaired. be. Such internally plasticized polyamide is extruded and coated on the outer periphery of a sheath of polyethylene, polyvinyl chloride, chloroprene rubber, ethylene propylene rubber, etc. to form an anti-termite layer. This thickness varies depending on the structure and dimensions of the wire/cable, but is generally around 1 mm, with small wires being thinner than this, and large wires and cables being thicker. [Example] Example 1 OF is a 1000 mm ² copper conductor wrapped in insulating paper, an aluminum sheath is applied to the periphery of the core impregnated with insulating oil, and the outer periphery is covered with a polyvinyl chloride sheath with a thickness of 7 mm.
used cable. A block copolymer of polylaurinlactam and rubber component is applied to the outer circumference of the polyvinyl chloride sheath.
A coating layer having a shore D hardness of 70 was formed by extrusion coating to a thickness of 1.2 mm. Example 2 The same OF cable as in Example 1 was used. A copolymer made of polylaurinlactam and propylene is coated around the outer circumference of the polyvinyl chloride sheath.
A coating layer having a shore D hardness of 75 was formed by extrusion coating to a thickness of 1.2 mm. Comparative Example 1 The same OF cable as in Example 1 was used. The outer periphery of the polyvinyl chloride sheath was extruded and coated with nylon 11 to a thickness of 1.2 mm. Comparative Example 2 The same OF cable as in Example 1 was used. The outer periphery of the polyvinyl chloride sheath was coated with nylon 6 to a thickness of 1.2 mm by extrusion. Comparative Example 3 The same OF cable as in Example 1 was used. Nylon 12 is placed around the outer circumference of the PVC sheath.
Externally plasticized polyamide containing 100 parts by weight and 30 parts by weight of EP rubber was extrusion coated to a thickness of 1.2 mm. The evaluation results for each cable of the example and comparative example are shown in Table 1.

【table】

[Table] [Effects of the Invention] As explained above, according to the present invention, electric wires and cables with significantly improved impact resistance and cold resistance can be realized without impairing characteristics such as termite resistance and workability. become.

Claims (1)

[Claims] 1. On the outer periphery of the rubber or plastic sheath,
A termite-proof electric wire/cable, characterized in that an extruded coating layer of a composition containing only internally plasticized polyamide as a resin component is formed, and the extruded coating layer has a Shore D hardness of 60 or more.