JP2002302577A - Semiconductive resin composition and power cable produced by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductive resin composition usable as a coating material for power cable and having improved blocking resistance while keeping the processability electrical conductivity, etc., a semiconductive resin composition obtained by adding a peeling agent to the above composition and an (easily peelable) power cable coated with the semiconductive resin composition. SOLUTION: The semiconductive resin composition is produced by compounding (A) 100 pts.wt. of a base resin composed mainly of a ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer and ethylene-butyl acrylate copolymer or a mixture of two or more of the above copolymers with (B) 10-400 pts.wt. of carbon black and (C) 0.01-10 pts.wt. of a surfactant. The composition is further compounded with (D) 2-50 pts.wt. of a peeling agent. The (easily peelable) power cable is produced by coating with the above resin compositions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductive resin composition and a power cable using the same in a semiconductive layer or an external semiconductive layer. More specifically, a semiconductive resin composition used as a covering material of a power cable having improved blocking properties while ensuring workability and conductivity, and a semiconductive resin composition further containing a release agent ,
And made by coating their semiconductive resin composition,
(Easily peelable) The present invention relates to a power cable.

[0002]

2. Description of the Related Art Conventionally, a crosslinked polyethylene insulated power cable has a conductor, an inner semiconductive layer, an insulating layer, and an outer semiconductive layer from the inside to the outside. -Vinyl acetate copolymer, ethylene-
A semiconductive resin composition is used in which carbon black is blended with a base resin mainly composed of an ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, or a mixture of two or more thereof. The reason for this is that if a base resin with a high comonomer content such as vinyl acetate, ethyl acrylate, and butyl acrylate is used, and a high melt mass flow rate is used, the compatibility with carbon black and the molding process when coating power cables This is because the adhesiveness between the semiconductive layer and the conductor or insulating layer of the manufactured power cable can be further improved. However, when the content of comonomer such as vinyl acetate, ethyl acrylate, and butyl acrylate is high, and a base resin having a high melt mass flow rate is used, the higher the comonomer content, the higher the melt mass flow rate, It was confirmed that the adhesion between the pellets, that is, the blocking easily occurred. Since the pellet has the above copolymer as a main component, it generally has a low melting point, low crystallinity, and a polar group such as a vinyl acetate group, an ethyl acrylate group, and a butyl acrylate group. When stored under conditions of high outside air temperature, conditions of large temperature change, and conditions under pressure, the pellets are liable to temporarily adhere, adhere or adhere to each other to form large blocks (blocks). This phenomenon is called blocking.

[0003] Pellets made of the semiconductive resin composition made of the base resin described above are made of a moisture-proof paper bag capable of containing 25 kg of pellets and a flexible container having a polyethylene inner bag capable of containing 1 to 5 tons of pellets. It is filled in an aluminum container or the like that can hold 1-5 tons of pellets, stored in a warehouse, and transported by truck to an electric wire manufacturing plant. During this time, blocking easily occurs, and pellets are removed from the container. Difficult, blocking occurs when pellets are sent by pneumatic transportation pipeline, or blocking occurs between pellets on the hopper of the molding machine during coating processing during power cable production, forming a so-called bridge at the supply port to the molding machine Supply of pellets is irregular or interrupted That problem occurs that the semi-conductive layer as standards will have is not formed there has been a problem. As a countermeasure, when blocking or bridging occurs in each step, it may be performed manually and the blocking or bridge is released to return to the pellet, but this is not a costly and economical measure.

[0004] The blocking problem of pellets of ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, etc. is also a problem in applications such as hot melts, films, and general-purpose molded products. However, it has been solved by thinly coating the surface of the pellets with wax in a wet or dry manner, or by blending an anti-blocking agent such as silica, talc, or zeolite. Wet or dry thin wax coating, aluminosilicate, kaolin, silica, talc,
When an inorganic anti-blocking agent such as zeolite is blended with polymer particles such as polymethacrylate, the interface between the semiconductive layer and the insulating layer may not be a uniform flat surface, or projections may be formed. There is a problem that water tree is generated and the life of the electric wire is shortened.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is used as a covering material for a power cable having improved blocking properties while ensuring workability and conductivity. An object of the present invention is to provide a semiconductive resin composition, a semiconductive resin composition further blended with a release agent, and a (easy peeling) power cable formed by coating the semiconductive resin composition. And

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer and ethylene-butyl acrylate copolymer. For a base resin mainly composed of a polymer or a mixture of two or more of these,
After conducting many experiments to mix various compounds with carbon black, surprisingly, in the plastics industry, antistatic (static), antifogging effects by water vapor, and dispersing effects of plastic compounding agents, etc. The present inventors have found that a surfactant used in anticipation of the above is effective in preventing pellet blocking, and completed the present invention.

That is, according to the first aspect of the present invention,
An ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, or a mixture of two or more thereof, based on 100 parts by weight of the base resin (A), 10 to 400 parts by weight of carbon black (B) and surfactant (C)
A semiconductive resin composition is provided, wherein the surfactant (C) is contained in an amount of from 0.1 to 10 parts by weight. A semiconductive resin composition characterized by being a polyoxyethylene alkyl ether represented by the following chemical formula 1 is provided.

[0008]

Embedded image

Further, according to the third aspect of the present invention, the first aspect is provided.
Alternatively, there is provided a semiconductive resin composition characterized in that 2 to 50 parts by weight of a release agent (D) is added to the semiconductive resin composition of any of the second inventions.

According to the fourth aspect of the present invention, the third aspect is provided.
In the invention, a semiconductive resin composition is provided, wherein the release agent (D) is a nitrile butadiene rubber.

According to a fifth aspect of the present invention, the first aspect is provided.
Alternatively, there is provided a power cable using the semiconductive resin composition according to any one of the second inventions for a semiconductive layer.

According to a sixth aspect of the present invention, the third aspect
Alternatively, there is provided a power cable using the semiconductive resin composition according to any one of the fourth inventions for an external semiconductive layer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a semiconductive resin composition of the present invention, a semiconductive resin composition further mixed with a release agent,
And made by coating their semiconductive resin composition,
(Easy peeling) The power cable will be described in detail for each item. First, the components used in the present invention will be described.

1. Base Resin (A) The base resin (A) used in the present invention is an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, or two or more of these. Are mainly used. The base resin is not particularly limited, but preferably has a comonomer content of vinyl acetate, ethyl acrylate and butyl acrylate of 5 to 45% by weight, more preferably 15 to 45% by weight.
Those in the range of ３０30% by weight are used. When the comonomer content is less than 5% by weight, the adhesiveness to the insulating layer is too strong when used for the outer semiconductive layer, and the peelability is reduced, making the peeling operation difficult. On the other hand, if it exceeds 45% by weight, its melting point (softening temperature) is greatly reduced, the mechanical properties of the semiconductive layer are weakened, and it is too tight with the insulating layer at room temperature or higher,
Inconvenience occurs. The base resin (A) has a melt mass flow rate of 2 to 1000 g / 10 minutes,
A range of 10 to 400 g / 10 minutes is desirable from the viewpoint of workability and mechanical properties as a semiconductive layer. The base resin (A) used in the present invention includes:
Other olefin-based resins can be blended in accordance with the purpose of use such as heat resistance and high mechanical properties as long as the effects of the present invention are not impaired. Other olefin resins include high-pressure low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density ethylene-α polymerized with a multi-site catalyst or a single-site catalyst.
-Olefin copolymer, linear ultra-low density ethylene-α-
Olefin copolymers and the like can be exemplified. As the α-olefin, propylene, butene-1, hexene-1, 4-methyl-pentene-1, octene-1, nonene-1, decene-1 and the like are selectively used.

2. Carbon Black (B) The carbon black (B) used in the present invention acts as a conductive material and imparts semiconductivity to the semiconductive resin composition of the present invention. The carbon black (B) may be any known carbon black, and is not particularly limited. Examples thereof include graphitized carbon, furnace black, acetylene black, and Ketjen black. The amount of the carbon black (B) is 10 to 400 parts by weight, preferably 30 to 400 parts by weight, based on 100 parts by weight of the base resin.
It is 150 parts by weight, more preferably 40 to 120 parts by weight. If the compounding amount of the carbon black (B) is less than 10 parts by weight, it is not possible to impart conductivity required as a semiconductive layer of a power cable. On the other hand, if it exceeds 400 parts by weight, the extrudability at the time of coating is inferior, and the mechanical properties of the semiconductive layer become inappropriate.

3. Surfactant (C) The surfactant (C) used in the present invention is compounded to improve blocking properties, and is a nonionic,
There is no particular limitation as long as it is an anionic or cationic surfactant. For example, alkyl naphthalene sulfonate,
Sodium salt of naphthalene sulfonic acid formaldehyde condensate, sodium salt of cresol-shepheric acid formaldehyde condensate, sodium salt of alkyl diphenyl ether sulfonic acid, calcium salt of lignin sulfonic acid, sodium salt of melamine resin sulfonic acid, special polyacrylic acid salt, gluconate , Olefin-maleic acid copolymer, carboxymethylcellulose sodium salt,
Metallic soaps (zinc, aluminum, sodium, potassium), potassium oleate, sodium oleate, potassium stearate, sodium stearate, potassium tallowate, sodium tallowate, and tristearate Examples thereof include sulfonic or carboxylic acid type anionic surfactants such as ethanolamine salts.

Furthermore, fatty acid monoglyceride, sorbitan fatty acid ester, sugar fatty acid partial ester, polyglycerin fatty acid partial ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene sorbitan fatty acid partial ester, polyoxyethylene sorbitol fatty acid partial Ester, polyoxyethylene glycerin fatty acid partial ester, polyoxyethylene fatty acid amine, polyoxyethylene (hardened) castor oil, polyoxyethylene glycol fatty acid ester, polyoxyethylene polyoxypropylene block polymer, hydroxyethyl cellulose, polyvinyl alcohol, polyvinyl Pyrrolidone,
And nonionic surfactants such as methylcellulose. One or two of these surfactants (C) may be used.
A mixture of more than one species can be used.

It is preferable to use a nonionic surfactant because of its affinity with the base resin (A), and more preferably a nonionic surfactant having a polyoxyethylene structure. Specifically preferred surfactant (C) is a polyoxyethylene alkyl ether represented by the following chemical formula 1.

[0019]

Embedded image R in the above chemical formula 1 is an alkyl group having 7 to 19 carbon atoms, which may be linear or branched (branched chain), and R has 7 to 19 carbon atoms. Range is desirable. When the carbon number of R is less than 7, the improvement of the blocking property is insufficient, and when it exceeds 19, the amount of the polyoxyethylene alkyl ether migrating (bleeding) to the pellet surface decreases, and the improvement of the blocking property is reduced. Insufficient and undesirable. The range of n representing the number of ethylene oxide is 2 to 30, and if it is less than 2, polyoxyethylene alkyl ether migrates to the pellet surface (bleed).
If the amount is less than 30, the moisture absorption in the polyethylene oxide portion becomes too large, the amount of water in the semiconductive layer becomes too large, and the electrical characteristics are deteriorated. As a result, the life of the wire is shortened, which is not desirable.

The amount of the surfactant (C) is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the base resin. Department. If the amount of the surfactant (C) is less than 0.01 part by weight, the effect of improving the blocking property cannot be provided. On the other hand, when the amount exceeds 10 parts by weight, the discharge amount is not constant during the extrusion, the extrudability is reduced, and the obtained pellets are rather sticky and the handling becomes difficult.

4. Release Agent (D) The release agent (D) used in the present invention is blended as necessary when the semiconductive resin composition of the present invention is used for an external semiconductive layer. There are two types of external semiconductive layers of power cables: types that are easy to peel off from the insulating layer, and types that are difficult.
The release agent (D) imparts releasability to the outer semiconductive layer,
It is blended in order to impart an effect of facilitating the peeling operation. The release agent (D) to be used is not particularly limited as long as it is a known one. As the release agent (D), nitrile butadiene rubber, polyorganopolysiloxane,
Examples thereof include polypropylene, styrene butadiene rubber, polystyrene, and nylon. Of these, nitrile-butadiene rubber is particularly desirable because of its good compatibility with the base resin (A) and its excellent effect of imparting releasability. The compounding amount of the release agent (D) is 2 to 50 parts by weight, preferably 4 to 20 parts by weight, based on 100 parts by weight of the base resin (A). If the amount of the release agent (D) is less than 2 parts by weight, an effective release property cannot be provided. On the other hand, when the amount exceeds 50 parts by weight, the release agent (D) is difficult to be uniformly dispersed in the resin composition, and the extrudability is reduced.

5. Additives In the present invention, in addition to the above-mentioned components, various other additives may be blended as long as the object of the present invention is not impaired.
Various additives include stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, lubricants, fillers, dispersants, metal deactivators, flame retardants, processing aids, mold release agents, and sterilizers. Agents, fungicides, air bubble inhibitors, foaming agents, conductive agents, nucleating agents, and the like. The semiconductive resin composition of the present invention preferably contains a stabilizer, particularly an antioxidant. Examples of the antioxidant include a phenolic antioxidant, a phosphorus-based antioxidant, an amine-based antioxidant, and a sulfur-based antioxidant, which may be used alone or in combination of two or more. The amount is preferably about 0.001 to 5 parts by weight based on 100 parts by weight of the olefin resin.

6. Preparation of semiconductive resin composition The semiconductive resin composition of the present invention is the above-mentioned ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer,
And a base resin (A) 1 mainly comprising an ethylene-butyl acrylate copolymer or a mixture of two or more thereof
A predetermined amount of carbon black (B), a surfactant (C), a release agent (D), an additive, and the like are added to 00 parts by weight, and a general method such as a kneader, a Banbury mixer, Using a new mixer or a single- or twin-screw extruder, uniformly, for example, from 110 to 200
It can be prepared by melt-kneading at ℃. In addition, carbon black (B), release agent (D), additives, etc. can of course be prepared by preparing a masterbatch using an ethylene-based resin containing a base resin used in the present invention, and blending and melt-kneading. Good. In the present invention, these methods are simply referred to as melt kneading.

In a preferred embodiment of the present invention, a semiconductive resin composition is prepared in the same manner as described above except for the surfactant (C), and pellets obtained by granulating the same are placed in a closed container. A fixed amount of the surfactant (C) or a solution in which a predetermined amount of the surfactant (C) is dissolved in a solvent (including water) is charged into the same container, and the container is sealed.
Heat to about 0 ° C. to coat the surface of the surfactant (C) on the pellet surface or impregnate the pellet with the surfactant (C) from the surface of the pellet.
The semiconductive resin composition of the present invention can also be prepared.
In the present invention, this preferred embodiment is simply referred to as surface coating. Since the semiconductive resin composition of the present invention is coated as a semiconductive layer of a crosslinked polyethylene insulated power cable, it is preferably a pellet having an average particle diameter of 2 to 7 mm from the viewpoint of workability.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples of the present invention, but the present invention is not limited to these examples. The physical property values used in the present specification and the evaluated physical property values evaluated in Examples and the like are based on the measurement methods summarized below.

[Measurement method]

1. Melt mass flow rate (MFR) Measured according to JIS K 7210. For base resin (A), load 2.16 kg, measurement temperature 190
It is a value measured at a temperature of 190 ° C. at a load of 21.6 kg for a semiconductive resin composition.

2. Density was performed in accordance with JIS K 7112.

3. Processability Pellets of the semiconductive resin composition were extruded from a mold having a diameter of 3 mm at 130 ° C. using a single screw extruder, and the surface state of the obtained cord-like molded product was visually observed and evaluated. When the surface condition was rough and protrusions were observed, the workability was poor and evaluated as "x". When the protrusions were smooth and no protrusions were observed, the workability was evaluated as good and evaluated as "O". did.

4. Blocking test 200 g of the pellet of the semiconductive resin composition was weighed and placed in a plastic bag, and then placed in a cylinder having an opening of the upper surface and the lower surface of 100 cm ² each, and a load of 7 kg weight was applied from the outer upper surface. And left at 40 ° C. for 24 hours. After cooling to 0 ° C. and allowing to stand for 72 hours, the blocking property was evaluated according to the following criteria. Those having a blocking property of 3 or less were judged to be acceptable. Blocking property 1: The pellet mass (columnar shape) is separated and collapsed by the operation of opening the plastic bag or immediately after opening. Blocking property 2: Disintegrates when a single finger is pressed lightly on a lump of pellets (columnar shape). Blocking property 3: Disintegrates when the pellet mass (columnar shape) is strongly pressed with one finger. Blocking property 4: Disintegrates when a lump of pellets (cylindrical shape) is pressed with one hand while being twisted. Blocking property 5: Disintegrates when pressing the pellet mass (columnar shape) with both hands while twisting. Blocking property 6: Does not break down even if the pellet mass (columnar shape) is twisted and held with both hands.

[0031]Example 1, Comparative Example 1  Ethylene-vinyl acetate copolymer (vinyl acetate content 34
Weight%, melt mass flow rate 37g / 10min, Japan
NUC-3166 manufactured by Unicar Corporation) as the base resin,
This 100 parts by weight and the carbon bra shown in the composition of Table 1 were used.
(Furnace black, HT manufactured by Nippon Carbon Chemical
C- # 100) 95 parts by weight, an antioxidant tetrakis [me
Tylene-3- (3 ', 5'-di-t-butyl-4'-h
Droxyphenyl) propionate] methane (chivaspe
Irganox 1010) 1 manufactured by Charity Chemical
Add parts by weight to a Banbury mixer and add 1 part at 180 ° C.
After kneading for 0 minutes, granulate and pelletize with an average particle size of about 4mm.
I got it. The obtained pellet was the semiconductive tree of Comparative Example 1.
It was evaluated as a fat composition. Seal the obtained pellets
Transfer to a container and add polyoxyethylene lauryl ether
Degree n = 23) per 100 parts by weight of the base resin
Add 1 part by weight, shake well at room temperature after sealing, and mix well.
The surfactant is uniformly coated on the pellet surface,
The obtained semiconductive resin composition of the present invention
It was evaluated as a conductive resin composition. The evaluation results are shown in Table 1.
However, both showed good processability, but the surfactant
In the blocking property test of Comparative Example 1 having no surface coating,
The blocking property was 4, but in Example 1, this was 2
Semi-conductive with significantly reduced blocking resistance
It was a resin composition.

[0032]Example 2  Other than putting the surfactant directly into the Banbury mixer,
In the same manner as in Example 1, the surfactant was melted and kneaded, and
A light semiconductive resin composition was obtained. The composition and evaluation results
As shown in Table 1, the second embodiment is similar to the first embodiment.
It has good anti-blocking properties with king property of 2.
Was.

[0033]Examples 3 and 4  Add the amount of surfactant per 100 parts by weight of base resin
Except for 0.05 parts by weight and 8 parts by weight, respectively.
A semiconductive resin composition of the present invention was obtained in the same manner as in Example 1.
Was. The results are shown in Table 1.
Example 3 was 3 and Example 4 was 1, which were good values.

[0034]Comparative Example 2  Example 1 except that the amount of the surfactant was changed to 20 parts by weight.
In the same manner as in Example 1, a semiconductive resin composition was obtained. Example 2
Although the blocking resistance was good, the workability evaluation
The condition is rough and protrusions are observed.
Sometimes the discharge rate was not constant.

[0035]Example 5  Nitrile butadiene rubber (manufactured by JSR, N
241) was added in an amount of 10 parts by weight and melt-kneaded.
A semiconductive resin composition of the present invention was obtained in the same manner as in Example 1.
Was. The results are shown in Table 1.
Semi-conductive resin set for external semi-conductive layer with excellent kingness of 2
It was an adult.

[0036]Comparative Example 3  Except that no surfactant is blended, the same as in Example 5
The semiconductive resin composition of the present invention was obtained. The results are shown in Table 1.
However, the workability was passed, but the blocking resistance was
4 and semiconductive resin for external semiconductive layer with blocking property
It was a composition.

[0037]

[Table 1]

[0038]

As described in detail above, the present invention provides
Ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-butyl acrylate copolymer, or a base resin mainly containing a mixture of two or more thereof, a specific amount of carbon black and Since the surfactant is incorporated, the blocking property can be significantly improved while maintaining the workability, so the wire can be used as a semiconductive layer even when stored under conditions of high external temperature or large temperature change. A semiconductive resin composition that does not cause blocking during the coating operation is obtained. Even when the semiconductive resin composition is coated on a cable as a semiconductive layer, a power cable can be obtained efficiently. The semiconductive resin composition obtained by further adding a release agent to the semiconductive resin composition can be coated as an external semiconductive layer of the electric wire, and has an effect of obtaining an electric wire having an easily peelable external semiconductive layer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // (C08L 23/08 C08L 71:00 Z 71:00) 9:02 (C08L 23/08 9:02 (72) Inventor Makoto Okazawa 6-13, Kaminomachi, Sakae-ku, Yokohama-shi, Kanagawa Prefecture (72) Mamoru Yoshida 29-18 Torigaoka, Totsuka-ku, Yokohama-shi, Kanagawa F-term (reference) 4J002 AC073 BB061 BB071 CH052 CH052 DA036 ED037 5G301 DA18 DA42 DA43 DA45 DD04

Claims (6)

[Claims] 1. A base resin (A) having 100% by weight of an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, or a mixture of two or more thereof. A semiconductive resin composition comprising 10 to 400 parts by weight of carbon black (B) and 0.01 to 10 parts by weight of a surfactant (C) per part by weight. 2. The semiconductive resin composition according to claim 1, wherein the surfactant (C) is a polyoxyethylene alkyl ether represented by the following chemical formula 1. Embedded image 3. The semiconductive resin composition according to claim 1, further comprising 2 to 50 parts by weight of a release agent (D). 4. The semiconductive resin composition according to claim 3, wherein the release agent (D) is a nitrile butadiene rubber. 5. A power cable using the semiconductive resin composition according to claim 1 for a semiconductive layer. 6. A power cable using the semiconductive resin composition according to claim 3 for an external semiconductive layer.