JPH0482108A - Electric insulator for wire, cable and their accessories - Google Patents

Abstract

PURPOSE:To prevent the occurrence of scorching in fusing and molding a wire, a cable and their accessories, and enable a bridge structure to be applied with polyolefine of high fusion point by using a resin composite containing a cross linking agent. CONSTITUTION:A pellet comprising the prescribed composite is introduced in an extruding machine, and extruded as an insulation layer 3 onto a soft copper stranded wire 1 conductor, together with an inner semiconducting layer 2 and an outer semiconducting layer 4. Then, an extruded product is immediately bridged in the dry bridging tube where nitrogen gas is used as a heating medium, and thereafter cooled, thereby completing a cable 5. In this case, dialkylperoxide and the molecule thereof are made to contain 0.01 to 10 weight parts of monocyclic hydrocarbon having at least two or more double bonds for 100 weight parts of polyolefine, and subjected to a bridging process. Also, 0.01 to 10 weight parts of unsaturated dimers of dialkylperoxide and aromatic alpha-methylalkenyl monomers are respectively contained for 100 weight parts of polyolefine, and subjected to a bridging process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrical insulator useful for electric wires/cables and their accessories.

[Prior Art] Polyolefin, particularly so-called crosslinked polyethylene, which is obtained by crosslinking polyethylene, has excellent electrical insulation and heat resistance, and is therefore widely used as an insulating material for electric wires, cables, and their accessories.

The crosslinking agent used to mold this crosslinked polyethylene is generally dicumyl peroxide (D CP
), 1,3-bis-(t-butylperoxy-isopropyl)benzene, etc. are used.

[Problem to be solved by the invention] Molding of a resin composition containing a crosslinking agent is usually carried out at around 130°C, but there is an increasing demand for higher molding temperatures, shorter molding times, and faster molding speeds. It's coming. However, when these crosslinking agents are used alone, there are problems in that some of the crosslinking agents decompose during molding, resulting in scorch (burning) and lowering the AC breakdown voltage.

Furthermore, when forming electric wires, cables, and their accessories using medium-density polyethylene, high-density polyethylene, linear extremely low-density polyethylene, or linear low-density polyethylene with a high melting point, the forming temperature is also high. Due to the large amount of scorch generated, resin compositions containing crosslinking agents could not be molded into these resins, and it was difficult to crosslink electric wires, cables, and accessories using these resins.

In view of the above-mentioned circumstances, an object of the present invention is to prevent scorch when melt-molding electric wires/cables and their accessories with a resin composition containing a cross-linking agent, and to prevent scorch by using a polyolefin with a high melting point. The present invention aims to provide an electrical insulator for electric wires/cables and their accessories that can be cross-linked.

[Means for Solving the Problems] First, the present invention provides 100 parts by weight of polyolefin with 0% each of dialkyl peroxide and a monocyclic hydrocarbon having at least two or more double bonds in the molecule. .01
-10 parts by weight of polyolefin, which is cross-linked.Secondly, based on 100 parts by weight of polyolefin,
It contains 0.01 to 10 parts by weight of dialkyl peroxide and an unsaturated dimer of aromatic α-methylalkenyl monomer, and is crosslinked.

In the present invention, polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and linear very low-density polyethylene, as well as ethylene-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, Examples include ethylene copolymers containing ethylene in the majority, such as α-olefin copolymers with ethyl acrylate copolymers, ethylene-propylene copolymers, ethylene-butene copolymers, etc. Two or more types can be used in combination.

In the present invention, a monocyclic hydrocarbon having at least two or more double bonds in its molecule is represented by the following formula, for example.

Such compounds include 1,3-cyclohexadiene, 1-methyl-1,3-cyclohexadiene, 1,4
-dimethyl-cyclohexadiene, 1-methyl-4-isopropylidene-cyclohexene, 1-ethyl-4-isopropylidene-cyclohexene, 1-methyl-4-isobutylidene-cyclohexene, 1-ethyl-4-isobutylidene-cyclohexene, etc. can be mentioned.

Furthermore, in the present invention, the aromatic α-methylalkenyl monomer is represented by the following formula.

CH.

C=CH2 where R is an allyl group, an alkaryl group, a halogen-substituted allyl group, or a halogen-substituted alkaryl group.

Unsaturated dimers include α-methylstyrene, paramethyl-
α-methylstyrene, para-ethyl α-methylstyrene, para-isopropyl-α-methylstyrene, meta-ethyl-α-methylstyrene, meta-methyl-α-methylstyrene, ardimethyl-α-methylstyrene, ar-
Unsaturated dimers such as chlor-α-methylstyrene, ar-chloro-ar-methyl-α-methylstyrene, ar-diethyl-α-methylstyrene, ar-methyl-ar-isopropyl-α-methylstyrene are included. Ru. Furthermore, these dimers may be used alone or in combination of two or more.

It can be considered that each of the above-mentioned cross-adding agents acts to donate hydrogen radicals when the dialkyl peroxide undergoes radical decomposition, and has the effect of delaying scorch during molding.

Note that the amount of each added is preferably 0.01 to 10 parts by weight, and if it is less than this, the effect is insufficient;
If the amount exceeds 1 part by weight, the crosslinking reaction will be significantly inhibited, and it will also precipitate on the surface, reducing the insulation performance.

Additives such as antioxidants, lubricants, and colorants may be added to the resin composition of the present invention.

[Example code] The present invention will be described below with reference to Examples.

The compositions shown in Tables 1 to 4 were kneaded using a 22-inch mixing roll to form a sheet, which was then pelletized using a pelletizer. This pellet is then introduced into the extruder and 6011I! as shown in the figure. 0.0 on the annealed copper strand 1 of l12.
It was extruded as an insulating layer 3 with a thickness of 4 mm together with an inner semiconducting layer 2 and an outer semiconducting layer 4 with a thickness of 7 mm. After this, it is immediately crosslinked in a dry crosslinking pipe using nitrogen gas as a heat medium.
Thereafter, the cable 5 was completed by cooling under pressure and used as a sample.

The evaluation was based on the following.

Extrusion processability The cable was evaluated based on its appearance after extrusion at an extrusion temperature of 145°C, that is, the presence or absence of burns.

All of Examples 1 to 8 in Table 1 have good extrusion processability. On the other hand, Comparative Examples 1, 2.3 have poor extrusion processability and low AC breaking strength. Moreover, in Comparative Examples 4 to 6, extrusion processing was difficult.

In addition, all of Examples 9 to 16 had good extrusion processability. On the other hand, Comparative Examples 7 and 8 had poor extrusion processability (burning occurred. This may be the reason why the AC breakdown voltage showed a small value. Furthermore, Comparative Examples 9 to 11 had poor extrusion processability. It was difficult to measure the AC breakdown voltage.

[Effects of the Invention] As explained above, according to the present invention, scorch can be prevented when electric wires/cables and their accessories are melt-molded with a resin composition containing a crosslinking agent, and a polyolefin with a high melting point can be used. It is possible to provide electric wires/cables and their accessories that can be crosslinked when used, and they have extremely high industrial value.

[Brief explanation of the drawing]

FIG. ·conductor, : internal semiconducting layer, :Insulator, ・Outer semiconducting layer, cable. conductor

Claims (1)

[Scope of Claims] (1) 0.01 to 10 parts by weight of a dialkyl peroxide and a monocyclic hydrocarbon having at least two or more double bonds in the molecule are contained per 100 parts by weight of the polyolefin. , electrical insulators for electric wires, cables, and their accessories made by crosslinking the same. (2) An electric wire made by crosslinking 0.01 to 10 parts by weight of dialkyl peroxide and an unsaturated dimer of aromatic α-methylalkenyl monomer per 100 parts by weight of polyolefin. Electrical insulation for cables and their accessories.