JPS60260637A - Semiconducting plastic mixture - Google Patents

Abstract

PURPOSE:The titled mixture which has low water absorptivity and excellent adhesiveness to a crosslinked PE and releasability, is useful as an external semiconducting layer of a crosslinked PE cable for extra-high tension, and consists of three specified types of ethylene polymers and an agent giving electrical conductivity. CONSTITUTION:100pts.wt. mixed resin composed of 10-90pts.wt. ethylene-vinyl acetate-alkyl acrylate terpolymer obtained by copolymerizing 10-90pts.wt. long- chain alkyl acrylate compound of formula I (where R1 is H or methyl; R2 is H or a group of formula II; 4<n<=13) with 100pts.wt. ethylene-vinyl acetate copolymer and 90-10pts.wt. ethylene-vinyl acetate copolymer containing 15- 70wt% vinyl acetate is blended with 5-60pts.wt. ethylene-vinyl acetate-vinyl chloride terpolymer containing 30-70wt% ethylene-vinyl acetate copolymer which contains 10-80wt% vinyl acetate, 30-100pts.wt. agent giving electrical conductivity, and 0.5-10pts.wt. crosslinking agent.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a semiconductive plastic mixture with low water absorption. This article relates to a plastic mixture excellent for use in the outer semiconductive layer of high-voltage cross-linked polyethylene cables by JiK%.

<Prior Art> Semiconductive plastic mixtures are widely used as materials for the external and internal conductive layers and planar heating elements of special high-voltage crosslinked Bolier fV:/cables.

Conventionally, semiconductive plastic mixtures used for fillet applications include ethylene-vinyl acetate copolymer (vinyl acetate content 15-5!s weight), as an example in a typical book.
) 10 to 90 parts by weight and 90 to 10 parts by weight of ethylene/vinyl acetate/vinyl chloride terpolymer) are blended with a conductivity imparting agent such as carbon black (e.g. , Special Publication No. 49-19907).

When used as the outer semiconducting layer of a cross-linked polyethylene cable, this semi-conductive plastic mixture has excellent adhesion to the cross-linked polyethylene insulation, and its adhesive strength is not very strong, so it can be used as an external semi-conductive layer for the cable. It has excellent properties such as being able to be peeled off relatively easily and without leaving any residue in the work of peeling off the external semiconducting layer from the insulator during terminal treatment or connection treatment.

<Problems to be Solved by the Invention> However, the above-mentioned semiconductive mixture, which has excellent properties in terms of releasability, does not have a good affinity with resin, but has a slight affinity with water. When it encounters water or moisture, it adsorbs or absorbs it. In particular, in the case of special high-voltage cross-linked polyethylene couples, if the outer semiconducting layer absorbs even a small amount of moisture, that moisture will eventually transfer to the cross-linked polyethylene insulation layer, causing dielectric breakdown (water tree). Therefore, the semiconducting mixture mentioned above also had a point to be solved in terms of affinity with water.

The present invention aims to solve such problems, and has excellent adhesion to cross-linked polyethylene, and at the same time, it can be removed relatively easily and without leaving any residue, and is compatible with water. It provides a small semi-conductive plastic mixture.

<Means for Solving the Problems> Surprisingly, the above problems can be solved simply by adding an ethylene-vinyl acetate ambiguous alkyl acrylate terpolymer to the above-mentioned known mixture. I can do it.

That is, the semiconductive plastic mixture according to the present invention is: 1. A mixture consisting of 10 to 90 parts by weight of an ethylene/vinyl acetate/alkyl acrylate terpolymer and 90 to 10 parts by weight of an ethylene/vinyl acetate copolymer. Resin: 100 heavy lid parts, 1: 5 to 60 fftit parts of ethylene/vinyl acetate/vinyl chloride terpolymer.
1. (,11, 30 to 100 parts by weight of conductivity imparting agent,
.

From 1 to 1, add the mixture and the crosslinking agent to 0.5 to io:r.
i part of the mixture.

-31 The mixed resin in the present invention is an ethylene/vinyl acetate/alkyl acrylate terpolymer (hereinafter referred to as gVAA). ) 1 part by weight of 10 to 901j and the remainder ethylene/vinyl acetate copolymer C or less NVA such that the total is 100 parts by weight
That's what it means. ).

Here, MVAA is an ethylene-vinyl acetate copolymer K (in the formula, %R1 represents hydrogen or a methyl group, and R2 represents water. For example, Epanuren G-41 $12, manufactured by Dainippon Ink & Chemicals Co., Ltd., is popular. In addition, Ev, which constitutes the queen mixed resin, is a random copolymer of ethylene and vinyl acetate, and has a vinyl acetate (hereinafter referred to as 7) content of 15 to 70 LII, such as 4-polymers. Chemical c stock) Il! , Evaflex, etc. are examples of this. If the amount of WVAA in 100 parts by weight of the mixed resin is less than 10 parts by weight, the water absorption of the mixed resin will not be reduced, and the sufficient effectiveness of the present invention will not be obtained. Both of these are not desirable.

The semiconductive plastic mixture of the present invention is composed of an ethylene/acetic acid vinyl chloride terpolymer (hereinafter mv*
It's called vc. ) is a random copolymer of ethylene/vinyl acetate (BVA) and vinyl chloride (hereinafter referred to as VC), and gvA (MA-=1o to 80%): VC is 30 to 70 near 0 to 30. For example, Sumitomo Chemical Co., Ltd.)

Migraft, etc. is a common cause.

In the mixture of the present invention, if the amount of RVAVC is less than 5 weight parts per 100 parts by weight of the mixed resin, the peelability will be poor. (However, if it exceeds 60 parts by weight, extrusion processability deteriorates.) If the amount exceeds 60 parts by weight, it becomes unsuitable for manufacturing cables, and both are undesirable.

FIG. 1 shows the relationship between resin composition and peeling force for the mixture of the present invention and the conventional mixture.

The horizontal axis represents the resin composition, and the vertical axis represents the peeling force.
Curve a shows the blend of the present invention and curve 2 shows the conventional blend.

As can be seen from FIG. 1, the mixture of the present invention has superior peelability compared to conventional mixtures, and can be used as a material for the outer semiconductor layer of cross-linked polyethylene cables. is clearly demonstrated.

The above peeling force was determined by forming the sample mixture into a sheet with a thickness of 1 mm, which was prepared separately, and overlaid on an uncrosslinked polyethylene sheet with a thickness of 2 μm at a general crosslinking temperature (200 mm).
℃) to prepare a paste sample.

Next, the peel force of each sample was measured using a tensile strength tester at a tensile rate of 500 wt/min.

Also, in the sample is 1/2 inch.

Examples of the conductivity imparting agent to be added to the mixture of the present invention include metal powder, graphite, and various types of carbon black. Commonly used. The amount of this conductivity imparting agent is based on 100 parts by weight of the mixed resin.
If the weight is less than 30 parts, the conductivity required for semiconducting layers of power cables, planar heating elements, etc. cannot be obtained;
If it exceeds 0 parts by weight, the elongation will be less than 100%, and when the flexibility of the cable is taken into consideration, the cable will not be easily compressed.

The mixture of the present invention is prepared by mixing the components consisting of the mixed resin, ]j:VAVc, and a conductivity imparting agent under normal conditions using a normal mixer such as a two-roll mixer or a mixer. In addition, if necessary, as appropriate,
Antioxidants, crosslinking agents, ultraviolet absorbers, etc. may be added. In particular, those to which a crosslinking agent (for example, an organic peroxide such as dichloromethane) can be added impart heat resistance to the molded article and preferably provide a %A wire article.・ , ]〈Example and 2〉 Ethylene-vinyl acetate lylacrylate, carbon black, cross-linking agent, and other additives to resins such as ethylene-vinyl acetate, ethylene-vinyl acetate, and vinyl chloride as shown in Table 1. The semiconductive mixture of the present invention was obtained by blending the mixture in the proportion shown in the blending amount and kneading it with a bumper equalizer.

A nine-crosslinked polyethylene power cable was manufactured using the semiconductive mixture obtained above as an outer semiconductive layer, and
After immersing it in warm water at ℃ for 2 days, its water absorption tX was measured, and the results shown in the water absorption column of Table 1 were obtained.

The comparative examples were conducted under the same conditions as the examples except for the resin composition.

-8- <Effects of the Invention> The present invention has improved heat resistance and peelability by replacing a part of EVA in a conventional semiconductive mixture whose resin components are EVA and MVAVC with EVAA. For example, this semiconducting mixture can be used as a semiconducting layer material of a cross-linked polyethylene power cable. By using it as a cross-linked polyethylene electric cable, it is possible to obtain a cross-linked polyethylene electric cable with high water resistance.

[Brief explanation of the drawing]

The first N indicates the relationship between the amount of eVAVc (in the semiconductive plastic mixture of the present invention) and the peeling force. a-axis/semiconductive plastic mixture of the present invention. beO Conventional semiconducting plastic admixture. Patent applicant Fujikura Electric Wire Co., Ltd. 10-

Claims (2)

[Claims] (1), mixed resin consisting of 10 to 90 parts by weight of ethylene-vinyl acetate/alkyl arylate terpolymer and 90 to 10 parts by weight of ethylene/vinyl acetate copolymer 10031 lid part, ethylene/vinyl acetate/chloride A semiconductive plastic mixture comprising 5 to 60 parts by weight of a vinyl terpolymer and 30 to 100 parts by weight of a conductivity imparting agent. (2) 100 parts by weight of a mixed resin consisting of 10 to 90 parts by weight of ethylene/vinyl acetate realkyl acrylate terpolymer and 90 to 10 parts by weight of ethylene/vinyl acetate copolymer, ethylene/vinyl acetate chlorinated vinyl A semiconductive plastic mixture containing 5 to 1 parts of a ternary copolymer, 30 to 100 parts of a conductivity imparting agent, and 0.5 to 10 parts by weight of a crosslinking agent.