JPH09204818A - Electrical insulating member, power cable, and connecting member for power cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance AC characteristic and withstand voltage characteristic by using a resin composition, containing a syndiotactic polypropylene whose syndiotactic pentad rate is a specific value or more and an ethylene-α-olefin copolymer, for an electrical insulating member or an insulating layer. SOLUTION: 50 to 95wt.% syndiotactic polypropylene(s-PP) with a syndiotactic pentad rate of 0.7 or more is prepared. The polypropylene and 5 to 50wt.% ethylene-α-olefin copolymer in which the α-olefin has 4 to 12 carbons are kneaded together at 180 deg.C using a roll mill to obtain a resin composition. The resin composition is melted and molded at 180 deg.C for fifteen minutes in a compression molding machine and is continuously extruded by an electrical insulating member of a predetermined thickness or by an extruder onto a copper stranded conductor at about 180 deg.C to cover the conductor to form a cable, or is extrusion molded to form a reinforcement insulator used for connecting cable. Thus an insulating member is obtained which has high AC characteristic and impulse withstand voltage characteristic and is excellent in low-temperature brittleness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical insulating member, a power cable using the same, and a cable connecting member. More specifically, it relates to an electrical insulating member containing syndiotactic polypropylene, and a power cable and a connecting member for a power cable using the same as an insulating layer or an insulator.

[0002]

2. Description of the Related Art Isotactic polypropylene (hereinafter, also referred to as "i-PP") which has been conventionally used as an electrically insulating material is essentially rigid, and therefore is used as a bulk material. In addition to being limited to the electrical insulation applications of the above, it is often inadequate in terms of rigidity and low temperature brittleness (prone to cracking) even in the form of a thin sheet or in a composite state with other materials. Met.

When a power cable made of a material having a low temperature brittleness is used, especially in a cold region, mechanical breakdown of the cable is likely to occur. That is, the installation environment of the power cable may be, for example, −20 ° C. or lower in the severe winter season. In such a case, the insulating layer using i-PP is likely to be cracked, which may cause a problem such as stopping the energization. Also, when laying a power cable in a narrow place, it is necessary to bend the cable according to the laying place, but since i-PP is rigid, it is difficult to bend, and laying is difficult, and there is an unnecessary laying space. The problem of "etc." The same problem as described above occurs when a material having a problem of rigidity and low temperature brittleness is used for the insulating portion in the intermediate connection structure of the power cable.

Other commonly used materials for electrical insulating members include low density polyethylene (LDPE) and ethylene propylene rubber (EP rubber). However, the insulating member using these is not always satisfactory in recent power cables and the like, which are required to have high electrical characteristics and physical properties. Particularly when used as an insulator of a power cable and a connection portion of the power cable, more excellent AC characteristics and impulse withstand voltage characteristics are required.

[0005]

The inventors of the present invention have investigated the applicability of various materials to electrical insulating materials, and found that syndiotactic polypropylene (hereinafter referred to as "s-
(Hereinafter also referred to as “PP”) and an ethylene-α-olefin copolymer, a conventional general-purpose electrical insulating material is LDP.
It has higher electrical properties than E and EP rubbers, and has i-P
It has been found that a member having lower low temperature brittleness than P can be provided. Furthermore, the power cable and the insulating material for connecting cables, which use this as an insulating layer and an insulating material, have high AC.
It was confirmed that the characteristics and impulse withstand voltage characteristics were exhibited.

That is, the present invention provides a resin composition containing 50 to 95% by weight of syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more and 5 to 50% by weight of an ethylene-α-olefin copolymer. And an electric insulating member comprising

The present invention further provides a resin composition containing 50 to 95% by weight of syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more and 5 to 50% by weight of an ethylene-α-olefin copolymer. The present invention relates to a power cable having an electrical insulating layer made of, and a connecting member for a power cable.

The s-PP used in the present invention is a concept including not only a homopolymer of polypropylene having a syndiotactic structure but also a copolymer of propylene and other olefins. In the following description, , S-PP including the copolymer. In the present invention, s-PP, which is a homopolymer, is preferred.

The s-PP used in the present invention must have a syndiotactic pentad fraction of 0.7 or more. Here, the syndiotactic pentad fraction refers to 20.2 based on tetramethylsilane in a 13 C-NMR spectrum measured at 1,78,2, 1,2,4-trichlorobenzene solution at 135 ° C.
It refers to the ratio of the peak intensity attributed to all methyl groups of the propylene unit of the peak intensity observed in ppm (peak intensity of methyl group attributed to syndiotactic pentad chain). Syndiotactic pentad fraction 0.7
S-PP of less than 5% has a low melting point and also lowers electric breakdown strength and mechanical properties, and therefore should not be used as a material for producing the electrically insulating member of the present invention. The syndiotactic pentad fraction is preferably 0.8 to 0.95 from the viewpoint of electric field resistance, and more preferably 0.86 to 0.95 from the viewpoint of workability.

Further, s-PP is ASTM-D-1.
Melt flow rate (MFR) defined by 238 (load: 10 kgf, temperature: 230 ° C.) is 0.1 to 20 g.
Those having a range of / 10 minutes are preferred. s-PP MF
When R is in the above range, the fluidity does not become excessively high at a high temperature and the fluidity does not become excessively low at the high temperature, and any of them becomes an electrically insulating member having excellent workability. . A more preferable range of the MFR is 0.3 to 15 g / 10 minutes from the viewpoint of high temperature fluidity, and a particularly preferable range is 0.5 to 10 g from the viewpoint of extrusion processability and molding processability.
/ 10 minutes.

There is no particular limitation on the method for producing the s-PP. That is, as the polymerization catalyst to be used, an organometallic complex catalyst having a symmetric or asymmetric molecular structure, for example, a stereospecific polymerization catalyst such as a metallocene compound or the like can be used. The polymerization conditions are also not particularly limited, and for example, bulk polymerization method, gas phase polymerization method, solution polymerization method using an inert solvent, and the like can be used for production. In particular, a polymer obtained by an ionic polymerization method using a metallocene compound as a catalyst is preferable.

Examples of the ethylene-α-olefin copolymer used in the present invention include a copolymer of an α-olefin having 3 to 12 carbon atoms and ethylene. The α-olefin may be linear or branched, and examples thereof include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-pentene, 1-heptene and 1-octene. The method for producing the ethylene-α-olefin copolymer is not particularly limited, but ethylene and other α-olefin are not limited.
A catalyst system having a good copolymerization property with an olefin is preferably used, and examples thereof include organometallic complex catalysts having a symmetrical or asymmetrical molecular structure, vanadium-based and titanium-based transition metal catalyst systems. Among them, those produced by using a metallocene compound which is a transition metal catalyst as a catalyst are particularly preferable from the viewpoint of low temperature brittleness. The MFR (190 ° C.) of the ethylene-α-olefin copolymer is usually 0.01 to 10 g /
It is about 10 minutes, preferably about 0.3 to 5 g / 10 minutes.
The elongation at break [elongation at break / original length × 100 (%)] specified by JIS-K-6301 is usually 5
It is about 50 to 950%, preferably about 650 to 900%. Specific examples of the ethylene-α-olefin copolymer include ethylene-propylene copolymer and ethylene-propylene-diene copolymer. These ethylene-α-olefin copolymers can be used alone or as a mixture of two or more. Examples of the diene include ethylidene norbornene, dicyclopentadiene, and 1,4-hexadiene.
Among these, the number of carbon atoms is 4 to 12 from the viewpoint of low temperature brittleness,
Particularly, a copolymer of ethylene with an α-olefin having 4, 6 or 8 carbon atoms is preferable. More preferably, it is a copolymer of an α-olefin having 4, 6 or 8 carbon atoms and ethylene, having an MFR of 0.01 to 10 g / 10 min, an ethylene content of 90 to 20% by weight, and an elongation at break. Is 750
900%, among them, a copolymer of α-olefin having 8 carbon atoms and ethylene from the viewpoint of low temperature brittleness,
Moreover, it is preferable that the MFR is 0.3 to 5.0 g / 10 minutes and the elongation at break is 750 to 900%.

Examples of commercially available ethylene-α-olefin copolymers include Sumikasen-L manufactured by Sumitomo Chemical Co., Ltd.
FA101-1 (MFR: 0.8 g / 10 minutes), Sumitomo Chemical's Excellen VL-100 (MFR: 0.8 g / 1)
0 min, elongation at break: 900%), Sumitomo Chemical Co., Ltd. Excellen EUL-130 (MFR: 0.8 g / 10 min, elongation at break: 770%), Mitsui Petrochemical Tuffmer A-
4090 (MFR: 3.6 g / 10 minutes, elongation at break:
700%), Engage CL800 manufactured by Dow Chemical Company
1 (MFR: 0.5 g / 10 minutes, elongation at break: 880
%), Engage CL8002 (M
FR: 1.0 g / 10 minutes, elongation at break: 800%),
Exxon Exact, Mitsubishi Chemical Kernel, Mitsui Petrochemical Super Polyethylene and the like can be mentioned. Among these, especially Engage CL manufactured by Dow Chemical Company
8002 is preferred.

The mixing ratio of s-PP and ethylene-α-olefin copolymer is such that s-PP is s-PP and ethylene-
The ethylene-α-olefin copolymer is 5 to 95% by weight with respect to the total amount of α-olefin copolymer, and the ethylene-α-olefin copolymer is 5 to 5% with respect to the total amount of s-PP and ethylene-α-olefin copolymer.
50% by weight. If the mixing ratio of s-PP exceeds 95% by weight, the low temperature brittleness resistance decreases, and the mixing ratio of s-PP is 5%.
If it is less than 0% by weight, the electric breakdown property is deteriorated. A preferable mixing ratio is 60 to 90% by weight of s-PP and 10 to 40% by weight of an ethylene-α-olefin copolymer from the viewpoint of low temperature brittleness resistance and electrical breakdown characteristics, and a more preferable mixing ratio is s. -PP is 75 to 85% by weight, and ethylene-α-olefin copolymer is 15 to 25% by weight.

In the resin composition containing s-PP and the ethylene-α-olefin copolymer, a hindered phenol type, amine type, thioether type antioxidant or stabilizer, amide, Copper damage inhibitors such as hydrazide-based, benzophenone-based, benzoin-based ultraviolet protection, higher fatty acid-based or metal salt-based lubricants, processing aids, organic / inorganic pigments, organic / inorganic flame retardants, and You may add the additive normally used for plastics, such as a filler such as silica and clay.

The term "electrically insulating member" as used in the present invention means electrically insulating paper, oil-impregnated insulator, tape, sheet, spacer, plug, socket, pipe, insulating rod, various electrical component moldings, circuit components, sealing materials and the like. Each of these members is molded by a known method.

There is no particular limitation on the method of manufacturing the power cable, and the power cable is formed by a method known per se. For example, it is formed by continuous coating on a conductor by an extrusion coating method. Examples of the structure of the cable of the present invention include a conductor coated with an insulator in a single layer, a sheath layer coated, and a conductor coated with a separator.
Further, a semiconductive layer may be provided on a conductor and an insulator.

As the insulating portion of the cable connecting member according to the present invention, the insulating portion is continuously extruded and filled in a mold cavity having a preset shape by an extruder in a molten state to form an insulating portion of the connecting structure. Extruded mold type connection part (EMJ) constituting the first, the insulator is first preformed into a preset shape, and once cooled, the premolded insulator obtained is fitted into the connection part,
This is melted and heated under pressure to complete the insulation part of the connection structure, the block mold type connection part (BMJ), the insulator is first processed into a tape shape, and wound up according to a preset shape, and then externally A mold is attached to the tape, the tape is melted and heated under pressure, the tape connection part (TMJ) for molding the insulating part of the connection structure, all the connection part components are molded in advance, and they are connected The prefabricated connection part (PMJ) and the like assembled in step 1 can be exemplified.

The insulating member produced from the resin composition containing s-PP and the ethylene-α-olefin copolymer of the present invention has an impulse breakdown electric field strength at room temperature higher than that of conventional low density polyethylene (LDPE). 14-19% higher, AC breakdown electric field strength at room temperature is 3-17% than LDPE
high. Furthermore, the brittleness temperature is lower than i-PP by 39 to 95 ° C.

The above-mentioned electrical insulating member of the present invention is excellent in electrical characteristics (AC breakdown electric field strength, impulse breakdown electric field strength) and has a very low embrittlement temperature of -10 ° C. or less.
It is also excellent in low temperature brittleness.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0022]

【Example】

Examples 1 to 8 and Comparative Examples 1 to 9 The polymers shown in Tables 1 and 2 (the numbers are parts by weight) were kneaded at 180 ° C. using a roll mill, and then 180 in a compression molding machine.
Melt molding for 15 minutes at a temperature of 0.3 ° C and a thickness of 10.
A 0 mm sheet was obtained. The 0.3 mm thick sheet was subjected to an impulse breakdown test and an AC breakdown test at room temperature.
The 0 mm thick sheet was subjected to an embrittlement temperature test.

[0023]

[Table 1]

[0024]

[Table 2]

The polymers in Tables 1 and 2 are as follows. s-PP (1): Syndiotactic pentad fraction: 0.95 MFR: 14.00 g / 10 minutes s-PP (2): Syndiotactic pentad fraction: 0.80 MFR: 8.90 g / 10 minutes Ethylene-α-olefin copolymer (3): α-olefin: carbon number 4 (1-butene) Sumitomo Chemical Co., Sumikasen-L FA101-1 MFR: 0.8 g / 10 minutes Ethylene-α-olefin Copolymer (4): α-olefin: carbon number 6 manufactured by Sumitomo Chemical Co., Sumikasen-α FZ102-0 MFR: 0.8 g / 10 min Ethylene-α-olefin copolymer (5): α-olefin: carbon Sumitomo Chemical Co., Ltd., Sumikasen-α FZ102-0 MFR: 0.8 g / 10 minutes: elongation at break: 770% ethylene-α-olefin copolymer (6): α-olefin: carbon number 4 Mitsui Petrochemical Co., Ltd., Tuffmer A-4090 MFR: 3.6 g / 10 minutes: elongation at break: 770% ethylene-α-olefin copolymer (7): α-olefin: carbon number 8 (1-octene) Dow Chemical Co., Engage CL8001 MFR: 0.5 g / 10 min: Elongation at break: 880% Polymerization using metallocene catalyst Ethylene-α-olefin copolymer (8): α-olefin: carbon number 8 (1-octene), manufactured by Dow Chemical Co., Engage CL8002 MFR: 1.0 g / 10 min: elongation at break: 800% polymerization using a metallocene catalyst s-PP (10): syndiotactic pentad fraction : 0.60 MFR: 1.20 g / 10 minutes i-PP (11): Mitsui Petrochemical, J600 MFR: 7.0 g / 10 minutes LDPE (12): Mitsubishi Chemical Manufactured by ZF-30, MFR: 1.1 g / 10 minutes, elongation at break: 740%

(Impulse Destruction Test) Improved McKeo
A negative impulse standard wave of 1 × 40 μsec was applied to the wn electrode system by a step-up boosting method of applying 5 kV / 3 times at room temperature with an initial value of 70% of the expected breakdown voltage. The data of 10 samples was collected for each condition, and after Weibull analysis, the breakdown value at a breakdown probability of 63.3% was taken as the impulse withstand voltage value of the sample. ○: 300 kV / mm or more ×: less than 300 kV / mm

(AC Breakdown Test) With an improved McKeown electrode system, an initial value was 70% of the expected breakdown voltage, and the voltage was applied by a step-up boosting method of applying 1 kV / 1 minute at room temperature. In addition, data of 10 samples are collected for each condition,
After the Weibull analysis, the breakdown value at a breakdown probability of 63.3% was taken as the AC withstand voltage value of the sample. ○: 30 kV / mm or more ×: less than 30 kV / mm

(Brittle temperature test) Using a brittle temperature tester,
After placing the test piece in a test temperature atmosphere for 3 ± 0.1 minutes, an impact was applied once at a speed of 2 ± 0.2 m / s by an impact hammer to examine the presence or absence of breakage. The temperature at which all five test pieces were not destroyed was taken as the embrittlement temperature. It should be noted that the case where the test piece was completely separated into two or more was considered to be a fracture, and the formation of a crack and a crack was not considered to be a fracture. ◎: -20 ° C or less ○: -20 ° C or more and -10 ° C or less ×: -10 ° C or more

The results are shown in Tables 3 and 4.

[0030]

[Table 3]

[0031]

[Table 4]

Example 9 The composition used in Example 5 was processed by a 30 mmφ extruder.
A cable was prepared by continuously extrusion-coating a copper stranded wire conductor (diameter: 2 mm) to a thickness of 1 mm (extrusion temperature condition: C ₁ : 1).
80 ° C, C ₂ : 185 ° C, C ₃ : 181 ° C, D: 180
° C). According to JISC 3005, an impulse breakdown test, an AC breakdown test and an embrittlement temperature test were performed. The results were an impulse breakdown test: ◯, an AC breakdown test: ◯, and an embrittlement temperature test: ◎.

Example 10 The composition used in Example 5 was processed by a 90 mmφ extruder.
Extrusion molding was performed on the cable connection portion to create a reinforced insulating material for cable connection (extrusion temperature condition: C ₁ : 180 ° C,
_{C 2: 185 ℃, C 3} : 181 ℃, D: 180 ℃). J
Impulse destructive test, A according to IS C 3005
A C fracture test and an embrittlement temperature test were performed. The results were an impulse breakdown test: ◯, an AC breakdown test: ◯, and an embrittlement temperature test: ◎.

[0034]

The electrical insulating member of the present invention containing s-PP and ethylene-α-olefin has excellent electrical characteristics, and also has a low brittle temperature and excellent low temperature brittleness. Therefore, when this is used as an insulating layer of a power cable or in an insulating portion of a power cable connecting portion, the power cable and the cable connecting portion have excellent electric characteristics and low temperature brittleness.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kato 8 Nishinomachi, Higashimukaijima, Amagasaki City, Hyogo Prefecture Mitsubishi Electric Wire & Cable Co., Ltd. (72) Inventor Shigenori Maeda 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Chemicals Co., Ltd. (72) Inventor Susumu Uchikawa 3-5 Kasumigaseki, Chiyoda-ku, Tokyo Mitsui Toatsu Chemicals Co., Ltd.

Claims (7)

[Claims] 1. A syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more.
95% by weight and ethylene-α-olefin copolymer 5 to 5
An electrical insulating member comprising a resin composition containing 0% by weight. 2. An α of an ethylene-α-olefin copolymer
-The electrically insulating member according to claim 1, wherein the olefin has 4 to 12 carbon atoms. 3. The electrical insulating member according to claim 2, wherein the α-olefin has 4, 6 or 8 carbon atoms. 4. The electrical insulating member according to claim 1, wherein the ethylene-α-olefin copolymer is a copolymer polymerized by a transition metal catalyst. 5. The electrical insulating member according to claim 4, wherein the transition metal catalyst is a metallocene compound. 6. A syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more.
95% by weight and ethylene-α-olefin copolymer 5 to 5
A power cable having an electrical insulation layer made of a resin composition containing 0% by weight. 7. A syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more.
95% by weight and ethylene-α-olefin copolymer 5 to 5
A connecting member for a power cable made of a resin composition containing 0% by weight.