JPS6117088B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a shock-resistant cable whose shock-resistant layer is easily removed. Conventionally, cables used for applications that require impact resistance, such as cab tire cables and cables directly buried in concrete, have been coated with intermediate sheaths.
Providing an impact-resistant layer with a rubber coating has been practiced. However, a conventional impact-resistant cable using a thermoplastic elastomer as an impact-resistant layer has been disclosed (Japanese Utility Model Publication No. 52-85183). This cushioning body made of thermoplastic elastomer has excellent elasticity and permanent set characteristics, but it is also tough, so it is difficult to peel off the impact-resistant layer during terminal processing, and the insulation of the insulated wire is often caused by mishandling the knife. The problem was that it could even damage the coating. In order to solve these difficulties, the present inventors conducted research on the material of the impact-resistant layer, and found that a composition whose base polymer is a mixture of polyvinyl chloride and ethylene/propylene rubber or chlorinated polyethylene was developed. When extruded as an impact-resistant layer,
While having sufficient tensile strength and elongation in the length direction,
It can be easily torn with your fingertips, and
It has been found that sufficient impact resistance can be imparted to the cable as an impact resistant cable. The present invention was made based on this knowledge, and includes 100 parts by weight of polyvinyl chloride and 5 to 5 parts of ethylene/propylene rubber or chlorinated polyethylene as an olefin elastomer to the outer periphery of the insulated wire core.
The object of the present invention is to provide an impact-resistant cable in which the impact-resistant layer is easily removed, which comprises an impact-resistant layer formed by extrusion coating of a composition containing 60 parts by weight as a base polymer, and a protective coating, which is sequentially provided. As the olefin elastomer used to form the impact-resistant layer in the present invention, ethylene/propylene rubber such as ethylene/propylene copolymer, ethylene/propylene/diene terpolymer, or chlorinated polyethylene is suitable. The blending amount of these olefin elastomers to polyvinyl chloride is per 100 parts by weight of polyvinyl chloride.
The amount is 5 to 60 parts by weight, preferably 10 to 55 parts by weight.
If it is less than 5 parts by weight, the effect of improving impact resistance and tearing effect will be insufficient, and if it exceeds 60 parts by weight, tensile strength and other mechanical properties will be poor, so both are not preferred. Therefore, the composition used in the present invention includes the above blend as a base polymer, a plasticizer such as dioctyl phthalate (DOP) and dioctyl azelate (DOZ), a processing aid such as stearic acid, Additives such as stabilizers and fillers can be added. It is thought that the tearability of the impact-resistant layer in the present invention is expressed in the following manner. In other words, since there is a large difference in SP value between polyvinyl chloride and olefin elastomer, when they are simply blended, as shown in Figure 1,
The polyolefin elastomer 2 exists in a dispersed state in the polyvinyl chloride 1, and when this is extruded from an extruder, the olefin elastomer 2 is stretched as shown in Figure 2 at the exit of the extruder. . Even in this state, polyvinyl chloride and olefin elastomer do not adhere closely, so the tear strength of the extruded molded product is low, but the tensile strength in the longitudinal direction and the mechanical strength of the surface are low. Due to the properties of polyvinyl chloride, the impact resistance does not deteriorate much, and in the radial direction, the impact resistance is significantly improved due to the influence of the polyolefin elastomer. The details of Examples will be explained below. As shown in FIG. 3, on insulated wire cores 3 and 3' having insulation coatings made of general-purpose soft vinyl chloride resin, a solid impact-resistant layer 4 is extruded and coated with a composition having the composition shown in the table below. Further, a protective coating 5 made of soft vinyl chloride was extruded around the outer periphery. As shown in the same table, the impact-resistant layer of the resulting impact-resistant cable 6 has excellent mechanical properties, and
As shown in FIG. 4, it could be easily torn in the length direction with a fingernail and had sufficient impact resistance.

【table】

[Table] In the above example, a soft vinyl chloride resin was used as the protective coating, but it is also possible to add impact resistance to the protective coating itself by blending an appropriate amount of chlorinated polyethylene with the soft vinyl chloride resin. It is also possible to do so.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the dispersion state of the olefin elastomer when polyvinyl chloride is added and blended with the olefin elastomer.
The figure is an explanatory diagram showing the state of the olefin elastomer when it is extruded by adding the olefin elastomer to polyvinyl chloride, FIG. 3 is a perspective view showing an embodiment of the present invention, and FIG. FIG. 4 is a perspective view showing a state in which the impact-resistant layer of the example shown in FIG. 3 is torn. DESCRIPTION OF SYMBOLS 1...Polyvinyl chloride, 2...Olefin elastomer, 3,3'...Insulated wire core, 4...Shock-resistant layer, 5...Protective coating.

Claims (1)

[Claims] 1. On the outer periphery of the insulated wire core, an impact-resistant layer and a protective coating are sequentially applied by extrusion coating of a composition whose base polymer is 100 parts by weight of polyvinyl chloride and 5 to 60 parts by weight of ethylene/propylene rubber or chlorinated polyethylene. A shock-resistant cable made of