JPS61114408A - Vulcanized ep rubber insulated power cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a vulcanized EP rubber insulating power cable having an outer semiconducting layer on a vulcanized EPP rubber edge.

[Prior art] When connecting or processing the terminals of a power cable having an external semiconductive layer, the external semiconductive layer must be removed without damaging the insulator, and conventionally, this requires a skilled worker to remove the external semiconductive layer without damaging the insulator. and relied on labor.

Therefore, the development of an easy-to-peel external semiconductor layer that is easy to install has been an important issue for cable manufacturers.

Regarding electrical cables using cross-linked polyethylene as an insulator, cross-linked polyethylene itself is non-polar and has the property of resisting adhesion to other materials, so it is relatively easy to develop an external semiconductive layer that is easy to peel off.

However, in the case of vulcanized EP rubber insulation capacity capacitors made of ethylene-propylene copolymer or ethylene-propylene-diene terpolymer, vulcanized FPP rubber has many fillers,
Because it contains additives, it has polarity and has the property of adhering well to other materials, making it extremely difficult to develop an external semiconducting layer that is easy to peel off.

Conventionally, the use of highly polar polymer materials such as chloroprene rubber, lorosulfonated polyethylene, and ethylene-vinyl acetate copolymers with extremely high vinyl acetate concentrations have been proposed, but they have difficulties in heat resistance stability and extrusion processability. There were a lot of things that I wanted to do, but I didn't find anything that was completely satisfying.

[Problems to be Solved by the Invention] The object of the present invention is to provide a vulcanized EP rubber insulating power cable whose outer semiconductive layer is extremely easy to peel off during construction.

[Means for solving the problems] The vulcanized EP rubber insulating capacity capeple of the present invention, ethylene-
A vulcanized EP rubber insulating power cape- ture with an insulator formed of a resin composition mainly composed of a propylene copolymer or an ethylene-propylene-diene terpolymer, and an outer semiconductive layer on the outer periphery of the insulator. The outer semiconductive layer contains conductive carbon black in a mixture of a styrene-methyl methacrylate block copolymer and an ethylene-vinyl acetate copolymer containing m3o to 60% by weight of vinyl acetate; Formed from a resin composition in which the content Q1 of the styrene-methyl methacrylate block copolymer is 10 to 10% by weight and the content of conductive carbon black in the composition is 30% by weight or less. It is characterized by this.

The inventors conducted various studies over a long period of time in order to create an external semiconducting layer that has no problems with heat resistance stability or extrusion processability and is easy to peel from an insulator, and as a result, they developed a styrene-methyl methacrylate block copolymer. It has been found that a composition mainly containing a mixture of ethylene-vinyl acetate copolymer and ethylene-vinyl acetate copolymer meets the purpose.

Styrene-methyl methacrylate block copolymer has excellent releasability for vulcanized EPP rubber, but when used as a single composition, it has low flexibility, so ethylene-methyl methacrylate block copolymer
A vinyl acetate copolymer is also used to improve flexibility. The content of styrene-methyl methacrylate block copolymer in the mixture of styrene-methacrylate metal block copolymer and ethylene-vinyl acetate copolymer is:
It is necessary to set it at 10 to 40% by weight; if it is less than 10% by weight, the releasability will not be sufficient, and if it exceeds 40% by weight, the flexibility will not be sufficient.

In the present invention, the amount of vinyl acetate in the ethylene-vinyl acetate copolymer must be in the range of 30 to 60% by weight; if it is less than 30% by weight, the peelability will be poor, and if it exceeds 60% by weight, it will be heat resistant. In addition, deacetic acid reaction tends to occur during the high-temperature vulcanization process during cable manufacturing, and corrosion occurs in the metal arc (for example, copper tape) for shielding the insulator. In order to impart conductivity, conductive carbon blacks such as acetylene black, furnace black, and Ketjen black can be used alone or in combination. The content thereof in the entire composition needs to be 30% by weight or more, and if it is less than this, sufficient conductivity cannot be imparted.

As described above, a composition containing a styrene-methyl methacrylate block copolymer, an ethylene-vinyl acetate copolymer, and conductive carbon black as essential components contains an organic peroxide, and is crosslinked after molding. It is preferable. In this case, the crosslinking agents include dicumyl peroxide, 1,3-bis-(t-butylperoxy-improvil)-benzene, 2,5-dimethyl-2,5-di(t-butylperoxy) -hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3, and the like.

In the present invention, other lubricants such as stearic acid and its metal salts and paraffin wax, and zinc white are used.

Crosslinking aids such as triallyl isocyanurate, trimethylolpropane trimethacrylate, 4.4-monothiobis(3-methyl-6-tbutylphenol), 2.2.4
Antioxidants for rubbers or polyolefins such as -trimethyl-dihydroquinoline polymer, N,N--diphenyl-p-phenylenediamine, and 2-mercabutobenzimidazole zinc salt may be added as appropriate. . In the present invention, the vulcanized EPP rubber rim is not particularly limited, but it is preferably based on ethylene/propylene rubber with an ethylene content of 60:4% or more, which is commonly used for electric wires and cables.

Vulcanization of the EP rubber is preferably carried out with dicumyl peroxide, and inorganic fillers such as clay, other vulcanization aids, antioxidants, processing aids, etc. may be blended as appropriate.

[Example 1] The compositions shown in Table 1 were kneaded in a Banbury mixer, and then a crosslinking agent was added to prepare a conductive composition.

EP rubber with a thickness of 5 on a copper stranded conductor with a conductor area of 150 gates 2
The above-mentioned electroconductive composition was extrusion coated to a thickness of 0.7 tm on the circumference of the insulator formed by extrusion coating on the shoe, and then vulcanization was performed in a dry crosslinking cylinder using nitrogen gas as a heating medium. . After that, the cable was completed by adding copper tape for shielding the insulator, a plastic sheath, etc.

Table 1 shows the evaluation results for the cable thus obtained.

Note that the evaluation was performed as follows.

The ease of peeling of the outer semiconducting layer was determined by measuring the peel strength according to the Etc standard, and the peel strength was determined to be 1.8 (1/1/2" to 4.0 g/
If it is within the range of 1/2", it is passed.

Flexibility is judged from the degree of elongation of the outer semiconducting layer peeled from the cable, and if the elongation is 100% or more, it is passed.

The volume resistivity is measured at room temperature and is passed if it is 5×10 2 Ωcm or less.

Corrosion of copper tape for insulation shielding can be prevented by energizing the cable and subjecting it to a heat cycle of 10°C from room temperature to 105°C.
The test was carried out for 10 days with the time ON and 10 hours OFF, and then the cable was disassembled (] and judged by visual observation.

Examples 1-5 within the scope of the present invention all have good peelability, flexibility, deposition resistivity, and no corrosion of the copper tape.

Comparative Example 1 is an example in which an ethylene-vinyl acetate copolymer having a vinyl acetate gold ratio exceeding the range specified in the present invention was used, and no peeling occurred. Comparative Example 2 is an example containing a styrene-methyl methacrylate block copolymer in a content below the range specified in the present invention, and has poor releasability.

Comparative Example 3 is an example containing a styrene-methacrylic acid metal block copolymer in an amount exceeding the range defined by the present invention, and has low elongation and almost no flexibility. Comparative Example 4 is an example in which an ethylene-vinyl acetate copolymer having a vinyl acetate content exceeding the range specified by M in the present invention was used, and corrosion of the shielding copper arp was observed.

In Comparative Example 5, the gold cycle of carbon black was less than the amount prescribed in the present invention, and the volume resistivity was poor.

[Effects of the Invention] As explained above, according to the present invention, the peeling N
It is possible to realize a vulcanized FP rubber insulated power tar that has properties such as flexibility, conductivity, and a well-balanced external semiconducting layer that does not corrode the copper tape for shielding the insulator.

Claims (1)

[Claims] (1) Vulcanized EP rubber insulated power cable whose insulator is formed from a resin composition mainly composed of ethylene-propylene copolymer or ethylene-propylene-diene terpolymer and has an external semiconductive layer on its outer periphery. In the above, the outer semiconductive layer contains conductive carbon black in a mixture of a styrene-methyl methacrylate block copolymer and an ethylene-vinyl acetate copolymer having a vinyl acetate content of 30 to 60% by weight; It is characterized by being formed from a resin composition in which the content of the styrene-methyl methacrylate block copolymer is 10 to 40% by weight, and the content of conductive carbon black in the composition is 30% by weight or more. Vulcanized EP rubber insulated power cable.