JP2002208316A - Cable filling-up inclusion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cable filling-up inclusion in which the quantity of inclusion can be reduced even if the inclusion is filled up without leaving any gap without changing the filling-up rate, and the filling-in rate can be reduced by improving flexibility of the inclusion itself and removal of the inclusion at the execution of cable works can be made easy, thereby reducing the cost. SOLUTION: The thermoplastic resin is foamed at a foaming rate of 10-80% in the structure of the cable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid interposition used for electric wires and cables, and more particularly to a solid interposition for a cable which is lightweight, has excellent flexibility, and has good productivity.

[0002]

2. Description of the Related Art As shown in FIG. 1, a conventional insulated power cable has a conductor 1 made of soft copper wire covered with an insulator 2 made of a composition such as polyvinyl chloride resin or polyethylene or cross-linked polyethylene. A plurality of (three in FIG. 1) insulated conductors 3 are twisted, formed into a round shape with an intervening member 4 interposed therebetween, wrapped with a holding tape 5, and covered with a sheath 6. There is a cable 7. Conventionally, a jute, paper, unraveling thread, or the like is used for the interposition 4 and is bundled without a gap.

In such a conventional insulated power cable, jute, paper, unwound yarn and the like are not easy to handle. Thermoplastic resin compositions suitable for coating and forming on conductors and insulated wires as sheaths and sheaths have been used as intervening materials. And, as the thermoplastic resin composition, the withstand voltage and the insulation resistance are relatively high, the production cost is low, and the flame retardancy alone is excellent. Have been. However, such a polyvinyl chloride resin composition generates corrosive hydrogen chloride gas when electric wires and cables are incinerated and disposed of. Therefore, in recent years, non-halide olefin-based resin compositions such as polyethylene have been used as cables.

[0004]

In such a conventional insulated power cable, since the interpositions 4 are tightly packed without gaps, the weight and bulkiness of the insulated power cable are increased. There is a problem that it is not good and the cost increases.

[0005] An object of the present invention is to reduce the amount of intervening used even if the intervening is constructed without gaps without changing the enrichment rate, to improve the flexibility of the intervening itself and to reduce the filling rate. An object of the present invention is to provide a cable-enhanced intervention which can facilitate the removal of the intervention during construction and can reduce the cost.

[0006]

In order to achieve the above-mentioned object, a solid interposition for a cable according to the first aspect is made by foaming a thermoplastic resin in a foaming ratio of 10 to 80%. .

As the thermoplastic resin, polypropylene (P
P), polyethylene (PE), polystyrene (PS),
Polyvinyl chloride (PVC), polyethylene terephthalate (PET), rubber, ethylene acrylate copolymer (EEA), ethylene vinyl acetate copolymer (EV
A). The ethylene acrylate copolymer (EEA) is a resin having an appearance similar to low-density polyethylene and having elastomer properties similar to rubber and soft vinyl. These thermoplastic resins have a foaming ratio of 10
Foamed in the range of ~ 80%.

[0008] The foaming method of the thermoplastic resin includes a mechanical foaming method and a foaming agent decomposition method. The mechanical foaming method is a mechanical method, for example, a method of foaming a thermoplastic resin by publishing carbon dioxide gas during molding. The foaming agent decomposition method utilizes a gas generated by the decomposition of a chemical agent, and is a method in which a decomposable foaming agent is mixed in a thermoplastic resin and foamed by heat decomposition. Examples of the foaming agent include an azo type (ADCA, AIBN, etc.), a hydrazine type (OBSH, TSH, etc.), nitrosated azide compounds, sodium bicarbonate, hydrogen peroxide, carbonate and the like. As this azo foaming agent, azodicarbonamide (ADCA) is well known. This azodicarbonamide (ADCA) is a foaming agent for a thermoplastic resin (such as an olefin resin) having a decomposition temperature of 100 ° C., and is an aliphatic azo compound widely used as a chemical foaming agent in polyolefin resins and the like.

[0009] When the thermoplastic resin is foamed, the foaming rate can be easily adjusted by using a thermoplastic resin foam masterbatch. Such a thermoplastic resin foaming masterbatch composition is compounded in an extruder together with a thermoplastic resin and the like, and heated and mixed in the extruder with the thermoplastic resin. A foaming gas is generated from a foaming agent contained in the composition, and is dispersed in a base resin (for example, EEA) of the master batch composition. The thermoplastic resin is melted by heating when extruded by an extruder, and is compatible with the base resin of the foamed master batch composition. The particulate foam cells achieved by the base resin of the masterbatch composition are dispersed throughout the thermoplastic. As described above, the thermoplastic resin has a fine foamed structure by being dispersed throughout the fine particle foamed cells. Since the thermoplastic resin has a fine foam structure, the flexibility of the entire thermoplastic resin is improved, and when used as an interposition of a cable, the filling rate of the interposition can be reduced, and the flexibility of the cable is improved ( Softened). Further, when used as an intervening cable, the filling rate does not change, so that the amount of intervening used as a whole is reduced, and the weight of the cable can be reduced. Further, when a thermoplastic resin having a fine foam structure is used as an intervening cable, removal of the intervening at the time of constructing the cable becomes easy, and the workability can be improved.

As described above, when the thermoplastic resin foam masterbatch method is used, the thermoplastic resin masterbatch composition is blended with the thermoplastic resin, and the foaming agent is blended with the masterbatch composition. When the resin is kneaded and extruded and coated, the foaming agent contained in the coated thermoplastic resin master batch composition is decomposed by the heat of the extrusion coating to foam the thermoplastic resin. In foaming the thermoplastic resin, the higher the foaming ratio, the higher the flexibility, and the higher the flexibility (the softer). Therefore,
The amount of the foamed masterbatch is preferably determined according to the degree of the property of the thermoplastic resin to be obtained by blending.

Such an azodicarbonamide (ADC)
A, an organic chemical foaming agent) is for foaming a thermoplastic resin (for example, an olefin-based resin) that constitutes an interposition, and azodicarbonamide (ADCA, organic) is added to the thermoplastic resin (for example, an olefin-based resin). Chemical foaming agent) is compounded and extruded by an extruder. When extruded, azodicarbonamide (ADCA, organic chemical foaming agent) acts and foams due to the heat at the time of extrusion. It diffuses throughout the composition and becomes a state in which the whole is foamed. This azodicarbonamide (ADCA,
The foaming rate of the thermoplastic resin composition constituting the interposition by the organic chemical foaming agent) exhibits its effectiveness at 10 to 80%. The foaming rate of the thermoplastic resin constituting this interposition is 10 to
The reason for setting it to 80% is that if the foaming rate of the thermoplastic resin constituting the intervening material is less than 10%, the weight of the insulated power cable cannot be reduced, the flexibility (bending characteristics) as the cable cannot be obtained, and When the foaming rate of the thermoplastic resin constituting the intervening foam exceeds 80%, it is too soft and easily broken at the time of production, so that the production of the cable can be efficiently performed. This is because it will not be possible. When a thermoplastic resin composition having a foaming rate of 10% is used for the interposition, the weight can be reduced by 10% as long as the filling rate does not change. Similarly, when a thermoplastic resin composition having a foaming rate of 80% is used for the interposition, 8% as long as the filling rate does not change.
0% weight can be reduced. That is, when a thermoplastic resin composition having a foaming ratio of 80% is used for the interposition,
Conventional insulated power cables can be reduced to about 1/5 the weight.

[0012] In addition, the foaming method of the thermoplastic resin includes a solvent diffusion method, a chemical reaction method, and a syntactic foam.
In addition, as a method for producing a thermoplastic resin having a fine foamed structure, there are an inflation, a calender, a film die and the like, and a foam and the like. That is, the intervention of the fine foam structure of the thermoplastic resin is not limited to the extruded cord-like foam,
A film-like foam using a calendar or the like can also be formed.

According to the first aspect of the present invention, the amount of interposition can be reduced even if the interposition is enhanced without any gap without changing the enrichment ratio.
The flexibility of the interposition itself can be improved, the filling rate can be reduced, and the interposition can be easily removed during construction.
Costs can be reduced.

In order to achieve the above object, a solid interposition for a cable according to a second aspect of the present invention is such that the solid interposition for a cable is constituted by an extruded cord-like foam or a film-like foam. With this configuration, according to the second aspect of the present invention, any thermoplastic resin can be used as an intervening foam, and the outer shape of the cable can be stably obtained. it can.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric wire cable using a solid cable interposition according to the present invention as a cable interposition will be described below. The insulated power cable using the cable-enhanced intermediate according to the present invention as a cable intermediate is
It has the same configuration as the conventional insulated power cable 7 shown in FIG. That is, an insulator 2 made of a composition such as a polyvinyl chloride resin or polyethylene is coated on a conductor 1 made of an annealed copper wire to form an insulated conductor 3. A plurality of the insulated conductors 3 (three in FIG. 1) are twisted and formed into a round shape with an intervening member 4 interposed therebetween, and a holding tape 5 is wound thereon. The sheath 6 is covered to form the insulated power cable 7.

The interposition 4 is constituted by a thermoplastic resin foaming intermediate obtained by blending a thermoplastic resin with a thermoplastic resin foam master batch composition and foaming the mixture. That is, this interposition 4 mixes at least a thermoplastic resin and a foamed masterbatch composition in which an organic chemical foaming agent is blended,
In addition, if necessary, blend processing aids, antioxidants, etc.
It is formed by foaming to a foaming ratio of 10 to 80%.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solid cable interposition according to the present invention will be described in comparison with an interposition in which a thermoplastic resin (non-foamed) is formed in a cord.

According to the present invention, the content of the thermoplastic resin not having a fine foamed structure is defined as 100% and 10% to 8%.
Table 1 shows the weight of the interposition, the cable bending load, and the intervening cutting load in comparison with the solid interposition with a foaming rate of 0%.
Is shown in

[0019]

[Table 1] In Table 1, the present invention shows that the conventional thermoplastic resin
It is foamed at a foaming ratio of ~ 80%.

In Table 1, the intervening weight is a comparison of the weight of the same volume, and is 10%
Foaming at ~ 80% foaming rate indicates that the weight is 90% -20% of conventional intervention. The term "intermediate weight of 90% with respect to the conventional interposition of the present invention" means that 10% foaming was performed on the conventional interposition (thermoplastic tree). It shows that 80% foaming was performed on the conventional intervention (thermoplastic tree), respectively.

In Table 1, the cable bending load is 10% to 10% of the conventional bending force when the load required to bend a cable using a conventional thermoplastic resin (non-foamed) as an interposition is 100%. It shows the ratio of the load required to bend a cable of the same diameter using the interposition according to the present invention foamed at a foaming ratio of 80% to the bending load of the cable using the conventional interposition. In Table 1, the cable bending load using the interposition according to the present invention is 95% to 30% of the cable bending load using the conventional thermoplastic resin (non-foaming). That is, it can be seen that the cable using the interposition according to the present invention has improved flexibility as compared with the cable using the conventional thermoplastic resin (non-foamed) for the interposition. Since the interposition according to the present invention is not so crushed when the foam cell is filled, the interposition filling portion has a so-called honeycomb shape, and the bending (flexibility) is improved while maintaining the cable shape, and the cutting is easily performed. can do.

In Table 1, the intervening cutting load refers to the cutting load of the cutter when the blade is inserted into the cable and cut open in the longitudinal direction. That is, in Table 1, the cable bending load is 10% of the conventional interposition when the load when the blade is inserted into the interposition of the cable using the conventional thermoplastic resin (non-foamed) is 100%. ~
It shows the ratio of the load of inserting a blade to the interposition of a cable of the same diameter using the interposer according to the present invention foamed at a foaming ratio of 80% to the intervening cutting load of a cable using the conventional interposer. In Table 1, the intervening cutting load of the cable using the interposition according to the present invention is 85% of the intervening cutting load of the cable using the conventional thermoplastic resin (non-foaming).
It is about 20%. That is, it can be seen that the cable using the interposition according to the present invention has improved cutability as compared with the cable using the conventional thermoplastic resin (non-foamed).

[0023]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, the amount of intervening used can be reduced even if the intervening is formed without gaps without changing the enrichment ratio, and the flexibility of the intervening itself is improved. ,
The filling rate can be reduced, the removal of the intervention during construction can be facilitated, and the cost can be reduced.

According to the second aspect of the present invention, any thermoplastic resin can be used as an intervening foam, and the outer shape of the cable can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multi-core insulated power cable using a thermoplastic resin as an interposition.

[Explanation of symbols]

 1 Conductor 2 Insulator 3 Insulated conductor 4 Interposed 5 Holding tape 6 Sheath 7 Sheath 7 …… Insulated power cable

Claims (2)

[Claims] 1. A cable-filled solid body obtained by foaming a thermoplastic resin at a foaming rate of 10 to 80%. 2. The solid filling for a cable according to claim 1, wherein the solid filling for a cable is an extruded cord-like foam or a film-like foam.