JPH07288032A - Semi-conductive resin composition for electric wires and cables - Google Patents

Abstract

(57) [Summary] [Structure] A polyolefin or olefin-based copolymer, or a mixture thereof, a conductivity-imparting agent, and the following formula: (Wherein R ¹ and R ² represent a group selected from hydrogen or a hydrocarbon group excluding a phenyl group and a substituted phenyl group), or a quaternary salt thereof for an electric wire / cable Semi-conductive resin composition. The amount of the conductivity-imparting agent and acrylamide added is 40 parts by weight or more and 0.005 to 0.005 to 100 parts by weight of the polyolefin or the olefin copolymer or the mixture thereof.
It is preferably 1.0 part by weight. [Effect] It becomes possible to realize a semiconductive resin composition for electric wires / cables in which generation of water trees can be significantly suppressed and blooming does not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is effective for forming inner and outer semi-conductive layers of cross-linked polyethylene insulated power cables and is capable of significantly suppressing the generation of water trees at the interface with the insulator. The present invention relates to a conductive resin composition.

[0002]

2. Description of the Related Art The smoothness and adhesion of the interface between a semiconductive layer of a cross-linked polyethylene insulated wire / cable and an insulator are important for improving the reliability of the wire / cable, and the presence of interface irregularity causes local defects. A high electric field is formed, and corona discharge or electrochemical deterioration called water tree that occurs when used in a lubricated environment causes a significant decrease in electrical insulation performance.

As a result of studies on both the structure and the material of the semiconductive layer, an extrusion type semiconductive layer has been developed as an alternative to the semi-conductive cloth tape having a lot of fuzz. As a raw material resin for the extrusion type semiconductive layer, generally, an ethylene-vinyl acetate copolymer or an ethylene-ethyl acrylate copolymer is mainly used.

Further, the electric wire / cable manufacturing technology has been improved such as meticulous quality control of the raw material resin, making the manufacturing line a clean room, and coextruding the insulator and the inner and outer semiconductive layers, and steadily suppressing the generation of water trees. It's starting.

[0005]

However, in spite of repeated efforts in the above-mentioned various fields,
Today's technology has not reached the stage where the generation of water trees can be completely eliminated. For this reason, the actual situation is that studies are being conducted earnestly to prevent such occurrence.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductive resin composition for electric wires / cables which can significantly suppress the generation of water trees in the electric wires / cables.

[0007]

In order to achieve the above object, the semiconductive resin composition for electric wire / cable of the present invention comprises:
Polyolefin or olefin-based copolymer, or a mixture thereof and a conductivity-imparting agent and the following formula

[0008]

[Chemical 1]

(In the formula, R ¹ and R ² represent a group selected from hydrogen or a hydrocarbon group excluding a phenyl group and a substituted phenyl group. Note that some of the structures of R ¹ and R ² include It is composed of acrylamide having an atom such as oxygen, nitrogen, sulfur, silicon, or an atomic group composed of these, and quaternary salts thereof.

Further, with respect to 100 parts by weight of a polyolefin or an olefin-based copolymer, or a mixture thereof,
A composition obtained by adding 0.005 to 1.0 parts by weight of acrylamide having the formula of the above formula 1 or a quaternary salt thereof in an amount of 40 parts by weight or more to the crosslinking agent.

Further, a polyolefin or an olefin-based copolymer, or a mixture thereof, a conductivity-imparting agent and the following formula

[0012]

[Chemical 2]

(In the formula, R ³ represents a hydrocarbon group, and R ⁴ and R ⁵ represent hydrogen or a group selected from hydrocarbon groups excluding a phenyl group and a substituted phenyl group. R ⁴ and R ⁵ In the structure of, there is no problem even if some atoms such as oxygen, nitrogen, sulfur, silicon, or atomic groups consisting of these atoms are included.), Or a quaternary salt thereof. .

Furthermore, with respect to 100 parts by weight of the polyolefin or the olefin-based copolymer, or a mixture thereof, 40 parts by weight or more of the conductivity-imparting agent and an aminoalkyl acrylate having the formula (2) or a quaternary salt thereof are added.
A composition obtained by adding 0.005 to 1.0 part by weight is crosslinked.

[0015]

By adding acrylamide, aminoalkyl acrylate or a quaternary salt thereof to the semiconductive resin composition, the amino group in the compound such as acrylamide or aminoalkyl acrylate has the effect of suppressing the generation of water tree. Since it has, it becomes possible to sufficiently suppress the generation of water trees.

The raw material resin (polyolefin or olefin-based copolymer, or a mixture thereof) used in the present invention is a polyolefin containing ethylene in the majority, such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, or These include low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene copolymer, and the like, or a blend of two or more thereof in combination.

Carbon black such as furnace black and acetylene black is suitable as the conductivity-imparting agent, and the required conductivity can be obtained unless 40 parts by weight or more is added to 100 parts by weight of the raw material resin. Absent.

Specific examples of the acrylamide having the formula 1 above, the aminoalkyl acrylate having the formula 2 above or the quaternary salt thereof include N-methyl acrylamide, N-isopropyl acrylamide and N, N-dimethyl acrylamide. , N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminoethyl acrylate and the like. Moreover, you may use these compounds in combination of several types.

Compounds in which phenyl group and substituted phenyl group are introduced into R ¹ , R ² , R ⁴ and R ⁵ are excluded here because these compounds have weak effect of amino group and sufficient water tree generation occurs. This is because the deterrent effect cannot be obtained. In addition,
The upper limit of the total number of carbons is not specified, but it is desirable that the upper limit is about 30.

The amount of acrylamide, aminoalkyl acrylate or a quaternary salt thereof added is preferably 0.005 to 0.1 part by weight based on 100 parts by weight of the raw material resin.
If the addition amount of these is less than 0.005 parts by weight, the intended effect of suppressing the generation of water trees is insufficient, and if it exceeds 1.0 parts by weight, it precipitates on the surface of the compounded pellets from the upper limit of compatibility (this phenomenon That is, the storage stability and handleability of the pellets are reduced.

Crosslinking methods include chemical crosslinking with organic peroxides, silane water crosslinking, and ionizing radiation. As the cross-linking agent, dicumyl peroxide, 1,3-bis- (tert-butylperoxy-
Isopropyl) benzene, 2,5-dimethyl-2,5-di- (tert-butylperoxy) -hexyne-3 and the like.

In the present invention, a lubricant, a coloring agent, a filler, a crosslinking accelerator, etc. may be added in addition to the above components, if necessary.

[0023]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples.

First, Examples 1 to 6 and Comparative Examples 1 to 1 in Table 1
Various semiconductive resin compositions for electric wires and cables were produced according to the compounding components shown in each column of 6. These compositions, 1
The mixture was kneaded by a hot roll heated to 20 ° C. and formed into a sheet, which was then pelletized using a pelletizer.

This is a low density polyethylene (density 0.920
g / cm ³ , melt index 1.0 g / 10 min) 100 parts by weight, dicumyl peroxide 2.0 parts by weight and 4,4′-thiobis (6-
Tertiary butyl-3-methyl) phenol 0.2 parts by weight, together with an insulating layer composition, a semiconductive layer thickness of 0.5 mm and an insulating layer thickness of 2 mm on a conductor with an outer diameter of 3 mm. As described above, extrusion coating was performed by the coextrusion method, and the inner semiconductive layer 2, the insulating layer 3, and the outer semiconductive layer 4 were formed on the conductor 1 as shown in FIG. Subsequently, continuous cross-linking was performed in the cross-linking tube by a dry cross-linking method using nitrogen gas as a heating medium, and this was pressure-cooled to obtain a cross-linked polyethylene insulated cable.

Next, the following evaluations (number of water trees generated, bloom, volume resistivity) were carried out on the various cables thus produced, and the results are shown in the lower column of Table 1.

Regarding the evaluation of the number of generated water trees, the sample (cable) prepared as described above was immersed in warm water at 90 ° C., and an alternating voltage of 50 Hz, 3 kV was applied between the conductor and water for 500 days. After that, the vicinity of the interface between the inner semiconductive layer and the insulating layer was thinly sliced and boiled and stained with an aqueous solution of methylene blue, and the presence or absence of water tree generation and the number thereof were counted using an optical microscope.

The presence or absence of bloom was evaluated by visually observing the surface of the pellets, which had been prepared before making the cable, in a thermostat at 80 ° C. for 10 days.

The volume resistivity was measured using the prepared cable and was 5.0 × 10 ³ Ω · cm or less at room temperature and 90 ° C.
Those with a value of 5.0 × 10 ⁴ Ω · cm or less were evaluated as ○, and those exceeding these values were evaluated as ×.

[0030]

[Table 1]

Table 1 shows Examples 1 to 6 and Comparative Examples 1 to 6 according to the present invention shown in the claims.
The composition of each test material and the evaluation result are shown.

As is clear from Table 1, in each of the samples of Examples 1 to 6 according to the present invention, the generation of water trees was sufficiently suppressed and the generation of bloom was not observed.

On the other hand, Comparative Example 1 containing no acrylamide, aminoalkyl acrylate, or a quaternary salt thereof, or Comparative Examples 2 and 4 in which the amount of the compound added was less than the specified amount, generated a large number of water trees. . In addition, bloom was observed in Comparative Examples 3 and 5 in which the added amount of these compounds exceeded the specified amount. Furthermore, Comparative Example 6 in which the added amount of the conductivity-imparting agent was less than the specified amount was evaluated as x in the volume resistivity evaluation.

[0034]

As described above, according to the present invention, it is possible to realize a semiconductive resin composition for electric wires / cables in which generation of water trees can be sufficiently suppressed and blooming does not occur.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a power cable using the semiconductive resin composition of the present invention.

[Explanation of symbols]

 1 conductor 2 inner semiconductive layer 3 insulating layer 4 outer semiconductive layer

Claims (4)

[Claims] 1. A polyolefin or an olefin-based copolymer, or a mixture thereof, a conductivity-imparting agent and the following formula: (Wherein R ¹ and R ² represent a group selected from hydrogen or a phenyl group and a hydrocarbon group excluding a substituted phenyl group), or a quaternary salt thereof. A semi-conductive resin composition for electric wires and cables. 2. A conductivity-imparting agent of 40 parts by weight or more and a compound represented by the following formula: (Wherein R ¹ and R ² represent a group selected from hydrogen or a hydrocarbon group excluding a phenyl group and a substituted phenyl group), or a quaternary salt thereof.
A semiconductive resin composition for electric wires and cables, which is obtained by subjecting a composition obtained by adding 0.005 to 1.0 part by weight to a crosslinking treatment. 3. A polyolefin or an olefin-based copolymer, or a mixture thereof, a conductivity-imparting agent and the following formula: (Wherein R ³ represents a hydrocarbon group, R ⁴ and R ⁵ represent a group selected from hydrogen or a hydrocarbon group excluding a phenyl group and a substituted phenyl group), or 4 A semiconductive resin composition for electric wires and cables, characterized in that it comprises a graded salt. 4. A polyolefin or olefin-based copolymer, or 100 parts by weight of a mixture thereof and 40 parts by weight or more of a conductivity-imparting agent and the following formula: (Wherein R ³ represents a hydrocarbon group, R ⁴ and R ⁵ represent a group selected from hydrogen or a hydrocarbon group excluding a phenyl group and a substituted phenyl group), or 4 A semiconductive resin composition for electric wires and cables, which is obtained by subjecting a composition obtained by adding 0.005 to 1.0 part by weight of a graded salt to a crosslinking treatment.