JPH11329081A - Manufacture of electrical insulating composition, electrical insulating composition, electric wire and cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for an electrical insulating composition having an initial high breakdown voltage and excellent the electrical insulating composition, an electric wire and a cable. SOLUTION: As for a polyethylene electrical insulating composition bridged by styrene maleic anhydride copolymer blend and a manufacturing method for it, after producing a maleic anhydride graft substance blended by a maleic anhydride copolymer with high concentration by blending a large amount of the styrene maleic anhydride copolymer in meleic anhydride graft polyethylene, meleic anhydride graft ethylene copolymer or a mixture of them, polyethylene, ethylene copolymer or a mixture of them and an other blending agent are blended in the styrene maleic graft substance blended by the meleic anhydride copolymer with high concentration. An electric wire and a cable are formed by coating the above composition or other insulating material directly on a conductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrically insulating composition, an electrically insulating composition, and electric wires and cables.

[0002]

2. Description of the Related Art Since polyolefins are typical hydrocarbon polymers, they have excellent electrical properties and are widely used as insulating materials for electric wires and cables. In particular, cross-linked polyethylene formed by cross-linking polyethylene is widely used as an insulating material for high-voltage electric wires / cables and their accessories because of their excellent heat resistance in addition to electric properties.

[0003] However, it is known that a cross-linked polyethylene-coated electric wire / cable generates water trees in a cross-linked polyethylene insulator when used for a long period of time under conditions where wetness, a humid atmosphere, high temperature, high voltage and the like overlap. I have. It has also been found that dielectric breakdown occurs when the water tree grows severely.

[0004] Therefore, electric wire / cable manufacturers are studying various measures for effectively suppressing such water trees.

The present inventors have previously proposed the following crosslinked polyethylene electrical insulating composition as an electrical insulating composition capable of effectively suppressing such water trees (resistance to bow title).

[0006] A crosslinked polyethylene electrical insulating composition comprising a styrene / maleic anhydride copolymer blended with polyethylene or a polyethylene-based copolymer (Japanese Patent Laid-Open No. 5-32)
No. 5652) Maleic anhydride-grafted polyethylene or maleic anhydride-grafted polyethylene-based copolymer is added with styrene.
Crosslinked polyethylene electrical insulating composition containing maleic anhydride copolymer (JP-A-8-339717). Polyethylene or polyethylene copolymer or mixture thereof and maleic anhydride-grafted polyethylene or maleic anhydride-grafted polyethylene Crosslinked polyethylene electrical insulating composition comprising a copolymer or a blend of a mixture thereof and a styrene / maleic anhydride copolymer (JP-A-8-339717)

[0007]

However, the crosslinked polyethylene electrical insulating composition obtained in the above (1) is excellent in bow titley resistance, but has a drawback that the initial electrical breakdown voltage is low.

Therefore, the present inventors diligently studied the cause. As a result, the blended styrene / maleic anhydride copolymer exists in the crosslinked polyethylene electrical insulating composition as particles agglomerated to an outer diameter of several μm or more, and the styrene / maleic anhydride copolymer is present. It has been determined that the large particles of the coalescence act as defects in the polyethylene electrical insulating composition, thereby reducing the initial electrical breakdown voltage of the polyethylene electrical insulating composition.

The present invention has been made in view of such a point, and an object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a high initial electric breakdown voltage and excellent bow titleability. An object of the present invention is to provide a method for producing an electric insulating composition, an electric insulating composition, and an electric wire / cable.

[0010]

The gist of the present invention is that a maleic anhydride-grafted polyethylene, a maleic anhydride-grafted ethylene copolymer or a mixture thereof is mixed with a large amount of a styrene-maleic anhydride copolymer. After blending, a styrene / maleic anhydride copolymer high concentration blended maleic anhydride graft is prepared, and then the styrene / maleic anhydride copolymer high concentration blended maleic anhydride graft is mixed with a polyethylene or ethylene copolymer or A method for producing a styrene-maleic anhydride copolymer blend crosslinked polyethylene-based electrical insulating composition, characterized by mixing these mixtures and other compounding agents, and a styrene-maleic anhydride blend-crosslinked polyethylene-based electrical insulating composition Insulating composition and applying it directly or other insulating material on the conductor And in wire and cable made by covering it.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for producing an electric insulating composition of the present invention, an electric insulating composition, and electric wires and cables of the present invention will be described.

In the present invention, it is preferable that the maleic anhydride-grafted polyethylene, the maleic anhydride-grafted ethylene copolymer or a mixture thereof has a maleic anhydride content of 1% by weight or more.

Here, the maleic anhydride content of the maleic anhydride-grafted polyethylene, the maleic anhydride-grafted ethylene-based copolymer or a mixture thereof is set to 1% by weight or more when the maleic anhydride content is 1% by weight or more.
If the amount is less than about 10% by weight, the dispersibility of the styrene / maleic anhydride copolymer when the styrene / maleic anhydride copolymer is blended cannot be improved.

That is, the styrene / maleic anhydride copolymer has poor dispersibility in polyolefin. However, the styrene / maleic anhydride copolymer can be well dispersed in maleic anhydride-grafted polyethylene, maleic anhydride-grafted ethylene-based copolymer, or a mixture thereof. The dispersibility improves as the maleic anhydride graft concentration increases.

Accordingly, in the present invention, a maleic anhydride-grafted polyethylene or a maleic anhydride-grafted ethylene-based copolymer having a maleic anhydride content of 1% by weight or more or a mixture thereof is used as a base polymer to obtain styrene / anhydride. This increased compatibility with the maleic acid copolymer, thereby effectively preventing large aggregation of the styrene / maleic anhydride copolymer when the styrene / maleic anhydride copolymer was blended.

In the present invention, the content of maleic anhydride in the styrene / maleic anhydride copolymer blend crosslinked polyethylene-based electrical insulating composition is 0.02-5.
It is preferably at least 00% by weight.

In the present invention, the styrene / maleic anhydride content in the styrene / maleic anhydride copolymer blend crosslinked polyethylene-based electrical insulating composition is 0.0
It is preferably from 5 to 10.00% by weight.

[0018]

EXAMPLES Next, examples of the method for producing the electric insulating composition, the electric insulating composition, and the electric wires and cables according to the present invention will be described together with conventional comparative examples.

(Weighted Electrical Insulating Composition) First, materials were weighed and collected in accordance with each composition table to obtain a weighed electrical insulating composition of a comparative example.

The weighed electrical insulating compositions of the examples were divided as follows.

First, maleic anhydride-grafted polyethylene, maleic anhydride-grafted ethylene copolymer or a mixture thereof was weighed and collected.

Next, the styrene / maleic anhydride copolymer to be blended was weighed and sampled.

Next, the polyethylene or ethylene-based copolymer to be blended or a mixture thereof and other blending agents were weighed and collected.

(Electrically Insulating Composition Sheet) The weighed electrical insulating composition of the comparative example was kneaded with a kneading roll, and then pulled out into a sheet to obtain an electrically insulating composition sheet of the comparative example.

On the other hand, in the embodiment, the following was carried out.

First, maleic anhydride-grafted polyethylene, maleic anhydride-grafted ethylene-based copolymer, or a mixture thereof was kneaded with a kneading roll.

Next, the styrene / maleic anhydride copolymer collected in the above manner is kneaded with the maleic anhydride-grafted polyethylene or the maleic anhydride-grafted ethylene-based copolymer or a mixture thereof kneaded on the kneading roll. did.

Next, the polyethylene or ethylene-based copolymer or a mixture thereof and the other compounding agents, which were separately collected as described above, were kneaded, and the resultant mixture was drawn out into a sheet, thereby obtaining a sheet of the electrically insulating composition of Example. And

(Electrically Insulating Composition Pellets) Next, the electrically insulating composition sheets of Examples and Comparative Examples were pelletized by using a pelletizer to obtain electrical insulating composition pellets of Examples and Comparative Examples.

(Extrusion of polyethylene-coated cable)
Prepare an electric wire extruder, and set its conductor outlet to 1
A copper conductor stranded wire of 00 mm ^{2 and} the insulating material pellets of the examples and comparative examples obtained above in the insulating material charging port,
Then, an inner semiconductive layer material is provided in the inner semiconductive layer material input port, and an outer semiconductive layer material is provided in the outer semiconductive layer material input port. A polyethylene-coated cable was obtained.

(Manufacture of cross-linked polyethylene coated cable)
Next, the polyethylene-coated cables of Examples and Comparative Examples obtained above were passed through a dry-type crosslinking apparatus containing a high-temperature nitrogen gas as a heat medium to obtain a crosslinked polyethylene-coated cable.

FIG. 1 shows a cross-sectional view of the crosslinked polyethylene-coated cable of Example 1 thus obtained.

In FIG. 1, 1 is a stranded copper conductor, 2 is an inner semiconductive layer, 3 is a crosslinked polyethylene coating layer, and 4 is an outer semiconductive layer.

(Characteristic test of cross-linked polyethylene-coated cable) a. Initial Electrical Breakdown Voltage Test A test crosslinked polyethylene-coated cable was sampled for a length of several meters and its outer semiconductive layer was grounded. Then, an AC voltage was applied to the copper conductor stranded wire from 170 kv, and thereafter, the voltage was increased by 5 kv every 10 minutes, and the electric breakdown voltage was measured.

B. First, a few m length of the test crosslinked polyethylene-coated cable was sampled, immersed in hot water at 90 ° C., and an alternating current of 9 kv was applied between the stranded copper conductor and the hot water. Left for 500 days.

Next, after 500 days, the test crosslinked polyethylene-coated cable was taken out, and then the crosslinked polyethylene-coated layer was peeled off.

Next, the peeled crosslinked polyethylene coating layer was thinly sliced.

Next, the crosslinked polyethylene slice was immersed in an aqueous methylene blue solution, and then boiled and dyed.

Next, the stained crosslinked polyethylene slices were observed under an optical microscope to determine the number of bow title trees having a size of 0.2 mm or more.

Table 1 shows the test results of the crosslinked polyethylene compositions and the crosslinked polyethylene coated cables of these Examples and Comparative Examples.

[0041]

[Table 1]

As can be seen from Table 1, the crosslinked polyethylene-coated cable of Comparative Example 1 has one bow title tree.
4, which is the lowest, but the half-side initial breakdown voltage is 200
The lowest with kv.

The crosslinked polyethylene-coated cable of Comparative Example 2 had the largest number of bow title trees, 19, and also had a low initial dielectric breakdown voltage, 205 kv.

The crosslinked polyethylene-coated cable of Comparative Example 3 has a small number of bow title trees as low as 15, but has the lowest half-surface initial dielectric breakdown voltage of 200 kv.

On the other hand, the crosslinked polyethylene-coated cables of Examples 1 to 4 had a small number of bow title trees and had high initial dielectric breakdown voltage of 345 kv or more.

[0046]

Industrial Applicability The method for producing the electrical insulating composition, the electrical insulating composition, and the wires and cables of the present invention exhibit excellent bow titleries and a remarkably high initial dielectric breakdown voltage, and are industrially useful. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a crosslinked polyethylene-coated cable according to a first embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 stranded copper conductor 2 inner semiconductive layer 3 crosslinked polyethylene coating layer 4 outer semiconductive layer

Claims (8)

[Claims] 1. A high concentration of a styrene / maleic anhydride copolymer by blending a large amount of a styrene / maleic anhydride copolymer with a maleic anhydride-grafted polyethylene, a maleic anhydride-grafted ethylene copolymer, or a mixture thereof. After preparing a blended maleic anhydride graft, a polyethylene or ethylene-based copolymer or a mixture thereof and other blending agents are mixed with the styrene / maleic anhydride copolymer high concentration blended maleic anhydride graft. For producing a styrene / maleic anhydride copolymer blend crosslinked polyethylene-based electrical insulating composition. 2. The maleic anhydride-grafted polyethylene, the maleic anhydride-grafted ethylene copolymer or a mixture thereof has a maleic anhydride content of 1% by weight.
2. The method for producing a styrene / maleic anhydride copolymer blend crosslinked polyethylene-based electrical insulating composition according to claim 1, wherein 3. A high concentration styrene / maleic anhydride copolymer comprising a large amount of a styrene / maleic anhydride copolymer blended with maleic anhydride-grafted polyethylene or maleic anhydride-grafted ethylene copolymer or a mixture thereof. 1. A styrene / maleic anhydride copolymer blended crosslinked polyethylene-based electrical insulating composition comprising a grafted product of maleic anhydride and polyethylene or an ethylene copolymer or a mixture thereof and a crosslinking agent. 4. The maleic anhydride-grafted polyethylene, the maleic anhydride-grafted ethylene-based copolymer or a mixture thereof has a maleic anhydride content of 1% by weight.
The styrene / maleic anhydride copolymer blend crosslinked polyethylene-based electrical insulating composition according to claim 3, which is the above. 5. The method according to claim 1, wherein the maleic anhydride content in the styrene / maleic anhydride copolymer blend crosslinked polyethylene-based insulating composition is 0.02 to 5.00% by weight or more. Item 4. A styrene / maleic anhydride copolymer blend crosslinked polyethylene electric insulating composition according to item 3. 6. The styrene / maleic anhydride content of the styrene / maleic anhydride copolymer blend crosslinked polyethylene-based insulating composition is 0.05 to 10.00% by weight. Styrene according to item 3
A maleic anhydride copolymer blend crosslinked polyethylene-based electrical insulating composition. 7. An electric wire or cable comprising a conductor and a styrene / maleic anhydride copolymer blend crosslinked polyethylene-based electric insulating composition coated directly or via another insulating layer, wherein the styrene / maleic anhydride copolymer The polymer blend crosslinked polyethylene-based electrical insulating composition is a maleic anhydride-grafted polyethylene or a maleic anhydride-grafted ethylene-based copolymer or a mixture of these with a large amount of a styrene-maleic anhydride copolymer. An electric wire or cable comprising a mixture of a maleic anhydride graft containing a high concentration of an acid copolymer and a polyethylene or ethylene-based copolymer or a mixture thereof and a crosslinking agent. 8. The maleic anhydride-grafted polyethylene, the maleic anhydride-grafted ethylene copolymer or a mixture thereof has a maleic anhydride content of 1% by weight.
The electric wire / cable according to claim 7, wherein: