JPH03141511A - Semiconductive resin composite - Google Patents

Abstract

PURPOSE:To obtain a power cable allowing to be stripped in any direction as much as required, when a semiconductive layer to be stripped from an insulated layer in terminal processing by providing a semiconductive layer consisting of a resin composite, where conductive carbon black is blended with stylene elastomer singly, or blended polymer with ethylene polymer. CONSTITUTION:A periphery of a conductor 1 is coated with an inner semiconductive layer 2. This inner semiconductive layer 2 is a bonded type semiconductive layer. An insulated layer 3 on this inner semiconductive layer 2 is consisting of a resin composite bridged by heating after the pasted coating with polyolefin resin. This insulated layer 3 is coated with an outer semiconductive layer 4 consisting of semiconductive resin composite, a shielding layer 5 and a sheath 6 by turns for being made a power cable. As a resin composite forming the outer semiconductive layer 4, a substance, wherein conductive carbon black 10 to 100wt.% is blended with stylene elastomer simplex, or blended polymer 100wt.% of stylene elastomer and ethylene polymer, is used.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductive resin that is mainly used for semiconductive layers of electrical cables such as cross-linked polyethylene insulated cables and that improves the releasability of the semiconductive layer. Regarding the composition.

[Conventional technology]

For power cables such as cross-linked polyethylene insulated cables (C cables), insulating layers made of cross-linked polyethylene or cross-linked ethylene propylene rubber, etc. are It is necessary to make the semiconductive layer easy to peel off. At the same time, it is also necessary that interfacial separation between the insulating layer and the semiconducting layer does not occur when an external bending force is applied to the power cable. Therefore, the semiconducting layer needs to have both appropriate releasability and appropriate adhesion to the insulating layer.

For this reason, conventionally, polar polymers such as polyvinyl chloride, chlorinated polyethylene, and ethylene-vinyl acetate copolymers, fluororesins, silicone resins, etc. are blended with an appropriate amount of polyolefin resins such as polyethylene to form a base polymer, and this is made into a base polymer. The semiconductive layer is made of a resin composition containing carbon black, and is designed to have appropriate peelability and adhesion to an insulating layer made of a polyolefin resin such as crosslinked polyethylene or crosslinked ethylene propylene rubber.

[Problem to be solved by the invention]

However, in the case of a semiconducting layer made of the above-mentioned resin composition, since this resin composition is a blend of a polyolefin resin and a polar polymer that is inherently poor in compatibility with this polyolefin resin, it is difficult to uniformly conduct wires when cross-wired. It is difficult to disperse (therefore, when the semiconducting layer obtained from this resin composition is peeled from the insulating layer, directionality is expressed,
There was a problem in that the cable could not be peeled off in any direction, and the end treatment of the electrical cable could not be easily performed.

[Means to solve the problem]

In this invention, the resin composition forming the semiconductive layer is a composition in which 10 to 100 parts by weight of conductive carbon black is blended with 100 parts by weight of a styrene elastomer alone or a blend polymer of a styrene elastomer and an ethylene polymer. The above problem was solved by using .

The present invention will be explained in detail below.

FIG. 1 shows an example of an electrical cable in which the semiconductive resin composition according to the present invention is used as a semiconductive layer, and the reference numeral 1 in the figure represents a conductor. An internal semiconducting layer 2 is formed on the outer periphery of this conductor l.
is covered. This internal semiconductive layer 2 is a bond type semiconductive layer, and is different in type from the semiconductive resin composition of the present invention having good releasability. Furthermore, this internal semiconducting layer 2 is coated with an insulating layer 3. The insulating layer 3 is made of a resin composition obtained by extrusion coating a polyolefin resin such as crosslinked polyethylene or crosslinked ethylene propylene rubber, and then crosslinking it by heating. Further, on this insulating layer 3, an external semiconductive layer 4 made of the semiconductive resin composition of the present invention, a shielding layer 5, and a sheath 6 are sequentially coated to form a power cable.

The outer semiconductive layer 4 is composed of 5% by weight or more of a styrene elastomer alone or a copolymer thereof and 95% of an ethylene polymer.
It is formed by extrusion coating the insulating layer 3 with a resin composition in which 10 to 100 parts by weight of conductive carbon black is blended with 100 parts by weight of the blended polymer. The styrenic elastomer, which is one component of the base polymer constituting the semiconductive resin composition used for the external semiconductive layer, is as follows.

That is, Table 1 shows the structural classification of styrenic elastomers, Figure 2 (a) (b'), Figure 3 Ca) (b)
As shown in the structural concepts of L1near type and Radial type, respectively, styrenic elastomer has a polystyrene crystal phase as a hard segment, and polybutadiene or polyisoprene is block copolymerized as a soft segment. , the bonding mode is also that the polystyrene part and polybutadiene part are L 1
A type that takes a near bonding style (typical example: Nijinil's Califlex) and a radial type that couples butadiene moieties together (typical example: Philips, Inc.)
It is roughly divided into two types (Tsurprene).

5EBS is commercialized and produced only by Shell Chemical Company, and is obtained by highly hydrogenating the butadiene portion of the SBS system to saturate the double bond portion in the main chain.

Table 1 However, SBS: Styrene-butadiene-styrene block copolymer 818: Styrene-isoprene-styrene block copolymer-8EBS: Styrene-ethylene-butylene-styrene block copolymer In both SBS and 5EBS, the ratio of styrene part to butadiene part is styrene part. is approximately 40% or less of the total, and the basic structure is that the butadiene portion has a continuous phase. When the styrene portion increases, the mechanical strength increases, but the hardness increases and the rubber elasticity tends to be lost.On the other hand, when the styrene portion decreases, the opposite tendency occurs. The styrene content of 40% or less is determined by these relationships. The polystyrene portion and the polybutadiene portion are incompatible with each other, so that the polystyrene portion can easily form a clear domain structure, and the polystyrene phase can be uniformly dispersed in the polybutadiene sea. At room temperature, this polystyrene moiety fixes the end of the butadiene moiety, forming a kind of physical crosslinking structure, but at high temperatures, the polystyrene domain melts and exhibits thermoplasticity.

Further, as the ethylene polymer which is the other component of the base polymer of the semiconductive resin composition according to the present invention, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-ethyl acrylate copolymer, etc. Examples include ethylene-α-olefin copolymers such as ethylene-vinyl acetate copolymers, and blend polymers of two or more of these, including ethylene-vinyl acetate copolymers and ethylene-ethyl acrylate copolymers. is particularly suitable. The ethylene-vinyl acetate copolymer preferably has a vinyl acetate content of about 10 to 35% by weight and a melt fluoride of 1 to 20.

This ethylene-vinyl acetate copolymer improves the processability of the base polymer and facilitates the dispersion of carbon black into the base polymer. Further, as the ethylene-dityl acrylate copolymer, one having an ethyl acrylate content of about 10 to 25% by weight is preferable since it imparts appropriate flexibility to the base polymer.

In addition, when using a blend polymer of the above-mentioned styrene-based elastomer and ethylene-based polymer as the base polymer, the mixing ratio is 5% by weight of the styrene-based elastomer.
In the above, the proportion of the polyolefin polymer is 95% by weight or less, preferably the styrene elastomer is 30% by weight or more, and the ethylene polymer is 70% by weight or less.

If the styrene elastomer content is less than 5% by weight, it will be difficult to separate the outer semiconducting layer 4 from the insulating layer 3, resulting in inconvenience.

Conductive carbon black is added to such a base polymer to impart conductivity. As the conductive carbon black here, well-known carbon blacks such as acetylene black and furnace black can be used. The amount of conductive carbon black to be mixed with the base polymer is determined in consideration of the conductivity required for the outer semiconductive layer 4, and is 10 to 10 parts by weight based on 100 parts by weight of the base polymer.
It can be determined within a range of 100 parts by weight.

Further, a crosslinking agent, a crosslinking aid, an anti-aging agent, etc. can be added to the resin composition made of the mixture of the base polymer and carbon black, if necessary. As a crosslinking agent, dicumyl peroxide (DCP), 2.5-
Common peroxide crosslinking agents such as dimethyl-2,5-di(1-butylperoxy)hexyne-3 can be suitably used.

The blending amount of the crosslinking agent is approximately 0.2 to 3 parts by weight per 100 parts by weight of the base polymer. In addition, as a crosslinking aid, triallyl isocyanurate, triallyl cyanurate, tetraallyloxyethane, NlN'-m-phinidine bismaleimide, p, p dibenzoylquinone dioxime, p-quinone dioxime etc., and can be blended in an amount of about 0.5 to 3 parts by weight per 100 parts by weight of the base polymer. These crosslinking agents and crosslinking aids may be used in combination, or either one may be used alone. When a crosslinking aid is used alone, a portion of the crosslinking agent in the insulator migrates to the semiconductive layer during crosslinking and reacts with the migrated crosslinking agent to cause crosslinking.

In addition, as an anti-aging agent, 4°4°-thiobis(6-
t-butyl-3-methylphenol), etc., and zinc stearate, zinc oxide, magnesia, etc. can also be added as required.

In order to form the outer semiconductive layer 4 using such a semiconductive resin composition, an extrusion coating method can be applied in the same manner as the conventional method. The extrusion temperature during this extrusion coating is approximately 120 to 140°C.

In such an electric cable, the outer semiconductive layer 4 is made of a styrene elastomer or a resin composition mainly composed of a styrene elastomer and an ethylene polymer, so it may be made of crosslinked polyethylene or 'ARIA ethylene propylene rubber. In addition to having appropriate adhesion and appropriate peelability to the insulating layer 3, the base polymer itself becomes a uniformly dispersed system, and there are no inconveniences such as easy peeling in a specific direction when peeling the semiconductive layer. It can be easily peeled off in any direction as needed. Hereinafter, the effects of this invention will be clarified by showing examples.

〔Example〕

A resin composition having the formulation shown in Table 2 was prepared as an outer semiconductive layer. The conductor (500+n+a") was coated with an inner semiconducting layer (thickness IInI+1), an insulating layer (cross-linked polyethylene, thickness ll), and an outer semiconducting layer (thickness 0, 5111 m) by three-layer extrusion coating. Then, a shielding layer and a sheath were sequentially applied to produce an electric cable.

Regarding the obtained electrical cable, the presence or absence of directionality during peeling of the external semiconductive layer was investigated. Separately, a sheet piece with a two-layer structure made of this resin composition and crosslinked polyethylene was extruded and its peel force was determined.

The results are also shown in Table 2.

As is clear from Table 2, in the case of the electric capule in which the outer semiconductive layer is made of the semiconductive resin composition of the present invention, there is no directionality when the semiconductive layer is peeled off, and it can be peeled off in any direction. It can be seen that the film can be peeled off quickly, and that the peeling force and adhesion force to the insulating layer are well balanced.

〔Effect of the invention〕

As explained above, the electrical capule contains 10 to 100 ffi of conductive carbon black per 100 parts by weight of a styrene elastomer alone or a blend polymer with an ethylene polymer. Since it has a semiconductive layer made of a resin composition containing 1 part of the semiconductive layer, it can be peeled off as much as necessary in any direction when peeling the semiconductive layer from the insulating layer during terminal processing work, etc. Terminal processing work can be easily performed. Further, this semiconductive layer has appropriate adhesiveness and appropriate releasability to an insulating layer made of crosslinked polyethylene or the like.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing an example of the electric cable of the present invention, Figs. (b) is a diagram of a type in which the polystyrene moiety and polybutadiene moiety take an L 1near bonding mode, and FIGS. 3(a) and (b) are diagrams of a type in which butadiene moieties are coupled together. 4...Outer semiconducting layer.

Claims (2)

[Claims] (1) 1 part by weight of conductive carbon black per 100 parts by weight of styrene elastomer alone or a blend of styrene elastomer and ethylene polymer
A semiconductive resin composition containing 0 to 100 parts by weight. (2) The semiconductive resin composition according to claim (1), wherein the blend polymer of a styrene elastomer and an ethylene polymer is a blend polymer containing 5% by weight or more of the styrene elastomer and 95% by weight or less of the polyolefin polymer. .