JP2000256422A - Power cable and extrusion molded connection part thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the impulse breaking strength and the mechanical strength without deteriorating the extrusion processibility of the insulant of a power cable or the insulant of an extrusion molded connecting part of a power cable. SOLUTION: As these insulants, an ethylene copolymer, which is a copolymer of ethylene and a 3-20Cα-olefin wherein the density is within the range of from 890 to 940 kg/m2, the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), Mw/Mn, is within the range of from 3.5 to 10.0, the melt tension (MT(g)) at 190 deg.C and the melt flow rate (MFR(g/10 min)) at 190 deg.C under a load of 2.16 kg satisfy the formula MT >4.0×MFR0.56 and the flow index (FI(sec-1)) and the melt flow rate (MFR(g/10 min)) at 190 deg.C under a load of 2.16 kg satisfy the formula FI>150×MFR, or a crosslined product thereof, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power cable and an extrusion-molded connection thereof, and more particularly to a power cable used in power transmission and distribution and having excellent mechanical strength and impulse breakdown resistance, and an extrusion-molded connection thereof.

[0002]

2. Description of the Related Art Conventionally, cables having polyethylene or an insulator obtained by cross-linking the polyethylene as necessary have been widely used for power transmission and distribution. The structure is simple, with polyethylene coated directly on the copper conductor,
A semiconductive layer (an internal semiconductive layer made of a semiconductive resin composition) was applied on the conductor, polyethylene was coated thereon as an insulator, and a semiconductive layer (an external semiconductive layer) was applied thereon. There are up to three layers. In some cases, a shielding layer, a water shielding layer, and a sheath are further provided on the outside as necessary.

The polyethylene used here is a low-density polyethylene (HP-L) polymerized by a high-pressure method.
DPE). HP-LDPE has a wide molecular weight distribution,
It is also characterized by a large number of branches in the molecular chain. Representative examples of these polyethylenes include Mirason 9 manufactured by Mitsui Chemicals, Inc. and NUCV-9026 manufactured by Nippon Unicar Co., Ltd. These HP-LDPEs are excellent in extrusion processability and hardly cause roughening or melt fracture when covering a cable. In particular, HP-LDPE containing a crosslinking agent
When extruding is used, the processing temperature is limited by the decomposition temperature of the cross-linking agent, but even in such a case, the processability is extremely good, and a power cable having excellent appearance can be obtained.

[0004] However, while HP-LDPE has excellent workability, its mechanical strength (tensile rupture strength, elongation, etc.)
And low impulse breakdown strength. By the way, as low-density polyethylene having excellent mechanical strength as compared with HP-LDPE, linear low-density polyethylene (L) polymerized using a Ziegler catalyst or a metallocene catalyst is used.
LDPE). LLDPE has a linear molecule, HP
Compared with LDPE, the lamella which is the crystal part is thicker, and the lamella which is the amorphous part has a large number of tie chains connecting the lamella with each other.
Further, among these LLDPEs, LLDPE polymerized with a metallocene catalyst is characterized by having excellent impulse breakdown strength. However, since LLDPE has a narrow molecular weight distribution and is extremely inferior in extrudability to HP-LDPE, cables coated with LLDPE have hardly been put to practical use. Further, in order to solve this problem, it has been proposed to use LLDPE mixed with HP-LDPE having excellent processability.
The excellent mechanical strength of LDPE is impaired, and the cost is poorly feasible.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to form an insulator for a power cable and an extruded mold connecting portion without impairing the extrudability thereof.
Moreover, the object is to improve the impulse breakdown strength and mechanical strength of the insulator.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an insulator for a power cable and an extruded mold connecting portion, which is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms and has a density of 890 to 890. 940 kg / m ³ , and the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 3.5 to 10.0;
Melt tension (MT (g)) at 0 ° C. and 190
° C, melt flow rate at 2.16 kg load (M
FR (g / 10 min)), MT> 4.0 × MFR
^The relationship represented by ^0.56 is satisfied, and the flow index (F
I (sec ^-1 )) and a melt flow rate (MFR (g / 10 min)) at 190 ° C. under a load of 2.16 kg satisfying a relation of FI> 150 × MFR or crosslinked ethylene copolymer. Solved by using things.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Ethylene copolymer constituting the insulator in the present invention,
It consists of a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, and the ethylene copolymer is
It is obtained by random copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms.

The above-mentioned C3-C20 α-olefin is, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-octene.
Nonene, 1-tesene, 1-utesene, 1-dotecene, tridecene, 1-tetradecene, 1-pentadecene, 1-
Hexadecene, 1-heptadecene, 1-octadecene,
1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-
Hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dotecene, 12
-Ethyl-1-tetradecene, and combinations thereof. Of these, α- having 3 to 10 carbon atoms.
Olefins are preferred, especially propylene, 1-butene,
1-pentene, 1-hexene, 1-octene and the like are preferably used.

The component ratio of ethylene to the α-olefin having 3 to 20 carbon atoms in the ethylene copolymer is 5% by weight.
5: 45-99: 1, preferably 65: 35-98:
2, more preferably 70:30 to 97: 3. Further, this ethylene copolymer has a density of 890 to 94.
0 kg / m ^3, preferably be in the range of 895~935kg / m ^3, the ratio Mw / Mn of more weight average molecular weight (Mw) to number average molecular weight (Mn) is 3.5 to 10.
It is in the range of 0. When the density is 890 to 940 kg / m ³ , a cable having excellent impulse resistance and excellent flexibility can be obtained. If Mw / Mn is outside the above range, the appearance becomes poor or the mechanical strength decreases. The density was measured with a density gradient tube after heat-treating a strand obtained at a melt flow rate measurement at 190 ° C. and a load of 2.16 kg at 120 ° C. for 1 hour, gradually cooling it to room temperature over 1 hour.

The Mw / Mn of the ethylene copolymer was measured as follows using GPC-150C manufactured by Millipore. The separation column was TSK GNH HT, the column size was 7.2 mm in diameter and 600 mm in length, the column temperature was 140 ° C., and the mobile phase was o-dichlorobenzene (Wako Pure Chemical Industries) and an antioxidant. Using BHT (Takeda Pharmaceutical) 0.025% by weight, moving at 1.0 ml / min, the sample concentration was 0.1% by weight, and the sample injection amount was 5%.
The volume was set to 00 microliter, and a differential refractometer was used as a detector. Standard polystyrene has a molecular weight Mw <1000.
And for Mw> 4 × 10 ⁶ , manufactured by Tosoh Corporation,
For 1000 <Mw <4 × 10 ⁶ , a product manufactured by Pressure Chemical Company was used.

The above ethylene copolymer has a temperature of 190 ° C.
Melt tension (MT (g)) at 190 ° C.
2. Melt flow rate at 16 kg load (MFR
(G / 10 min)) and MT> 4.0 × MFR
^-0.56 , preferably MT> 6.
It is desirable to satisfy the relationship ^represented by 0 × MFR ^-0.56 . MT and MFR do not satisfy the above relationship, that is, M
When T is small, drawdown tends to occur during extrusion molding. The melt flow rate was determined according to ASTM D12
Measurement temperature 190 ° C, load 2.
It is measured under the condition of 16 kg.

The melt tension is determined by measuring the stress when the molten resin is stretched at a constant speed. That is, the produced resin powder is melted by a usual method and then pelletized to obtain a measurement sample. Using an MT measuring device manufactured by Toyo Seiki Seisakusho, resin temperature 190 ° C., extrusion speed 15 mm / min, winding speed 15 m / min, nozzle The test was performed under the conditions of a diameter of 2.09 mmφ and a nozzle length of 8 mm. At the time of pelletization, 4,4′thio-bis (3-methyl-6-t) was previously added to the ethylene copolymer as a heat stabilizer.
0.2% by weight of -butylphenol was added. further,
Flow index (FI (sec ^-1 )) and 190 ° C,
2. Melt flow rate at 16 kg load (MFR
(G / 10 min)) satisfies the relationship represented by FI> 150 × MFR, and preferably FI> 200 × MFR
It is desirable to satisfy the relationship indicated by. If the MFR does not satisfy the above relationship, that is, if the FI is small, the extrudability is reduced, resin heat is likely to occur, and skin roughness is likely to occur.

The FI is defined as the shear rate at which the shear stress at 190 ° C. reaches 2.4 × 10 ⁶ dyc / cm ² . The ethylene copolymer was extruded from the capillary while changing the FI shear rate, and the stress at that time was determined. That is, using the same sample as in the MT measurement, using a capillary type flow characteristic tester manufactured by Toyo Seiki Seisaku-sho, a resin temperature of 190 ° C. and a shear stress range of 5 × 10
It is measured at about ^{4 to} 3 × 10 ⁵ dny / cm ² . The diameter of the nozzle (capillary) is measured as follows according to the MFR of the ethylene copolymer to be measured.

0.5 mm when MFR> 20 1.0 mm when 20 ≧ MFR> 3 2.0 mm when 3 ≧ MFR> 0.8 3.0 mm when 0.8 ≧ MFR

The ethylene copolymer having the above-mentioned properties comprises (A) a transition metal compound, (B) an organoaluminum oxy compound, and a particulate carrier.
It can be produced by using a solid catalyst comprising a transition metal compound and / or (B) an organoaluminum oxy compound supported on a fine particle carrier.

The transition metal compound (A) in the catalyst is represented by the following formula (I). M ¹ L ¹ _X (I) In the formula, M ¹ represents a transition metal atom, specifically, preferably zirconium, titanium, hafnium, chromium or vanadium, and particularly preferably zirconium or hafnium. Is preferred. x is the valence of the transition metal atom.

L ¹ represents a ligand which coordinates to a transition metal atom, and at least two L ¹ are ligands having a cyclopentadienyl skeleton. The ligand having two cyclopentadienyl skeletons is bonded via a carbon-containing group or a silicon-containing group. As the ligand having a cyclopentadienyl skeleton, for example, a cyclopentadienyl group, a methylcyclopentadienyl group, an ethylcyclopentadienyl group, an n-butylcyclopentadienyl group, a dimethylcyclopentadienyl group, Examples thereof include an alkyl-substituted cyclopentadienyl group such as a pentamethylcyclopentadienyl group, an indenyl group, a 4,5,6,7-tetrahydroindenyl group, and a fluorenyl group.

Examples of the carbon-containing group linking the two ligands having a cyclopentadienyl skeleton include an alkylene group having 1 to 3 carbon atoms such as ethylene and propylene, isopropylidene and diphenyl. Examples include a substituted alkylene group such as methylene, and examples of the silicon-containing group include a substituted silylene group such as a silylene group and dimethylsilylene.

L ¹ other than a ligand having a cyclopentadienyl skeleton is a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, a halogen atom or a hydrogen atom. Examples of the hydrocarbon group having 1 to 12 atoms include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and the like. Specifically, examples of the alkyl group include methyl, ethyl, propyl, and isopropyl. , Butyl, etc., as the cycloalkyl group, cyclopentyl, cyclohexyl, etc., as an aryl group, phenyl, tolyl, etc., as an aralkyl group, penzyl, neophyl, etc., as an alkoxy group Is exemplified by methoxy, ethoxy, butoxy, etc., and the aryloxy group is pheno. Sheet and the like are exemplified.

Examples of the halogen atom include fluorine, chlorine, bromine and iodine. x is the valence of the transition metal atom. Hereinafter, specific examples of the transition metal compound represented by the above formula (I) wherein M ¹ is zirconium are shown. Ethylene bis (indenyl) dimethyl zirconium, ethylene bis (indenyl) diethyl zirconium, ethylene bis (indenyl) diphenyl zirconium monochloride, ethylene bis (indenyl) methyl zirconium monochloride, ethylene bis (indenyl) ethyl zirconium monochloride, ethylene bis (indenyl) ) Methyl zirconium monopromide, ethylene bis (indenyl) zirconium dichloride, ethylene bis (indenyl) zirconium dipromide, ethylene bis {1- (4,5,6,7-tetrahydroindenyl)} dimethyl zirconium, ethylene bis −
(4,5,6,7-tetrahydroindenyl) {methylzirconium monochloride, ethylenebis} 1- (4
5,6,7-tetrahydroindenyl) {zirconium dichloride, ethylenebis {1- (4,5,6,7-tetrahydroindenyl)} zirconium dipromide, ethylenebis {1- (2-methylindenyl)} Zirconium dichloride, ethylene bis {1- (4-methylindenyl)} zirconium dichloride, ethylene bis
-(5-methylindenyl) zirconium dichloride, ethylenebis {1- (7-methylindenyl)} zirconium dichloride, ethylenebis {1- (5-methoxyindenyl)} zirconium dichloride, ethylenebis {1- ( 2,3-dimethylindenyl) zirconium dichloride, ethylenebis {1- (4,7-dimethoxyindenyl)} zirconium dichloride, ethylenebis {1- (2-methyl-4n-propylindenyl)} zirconium dichloride, Ethylenebis ｛1-
(2-ethyl-4-isopropylindenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-2,7-di-)
t-butylfluoronyl) zirconium dichloride, isopropylidene (cyclopentadienyl-methylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (cyclopentadienyl) zirconium dichloride, dimethylsilylenebis (methylcyclopentadienyl) zirconium dichloride, dimethyl Silylene bis (dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride, diphenylsilylenebis (indenyl) zirconium dichloride, and the like.

In the above-mentioned zirconium compound, a transition metal compound in which zirconium metal is replaced by titanium metal, hafnium metal, chromium metal or panadium metal can also be used.

Further, together with a transition metal compound in which a ligand having two cyclopentadienyl skeletons represented by the above formula (I) is bonded by a bonding group, the compound is represented by the following formula (II). Such a transition metal compound in which a ligand having two cyclopentadienyl skeletons is not bonded by a bonding group can be used in combination. M ¹ L ² X (II) In the formula, M ¹ represents a transition metal atom similarly to M ^{1 in the} formula (I), and is preferably zirconium or hafnium. x is the valence of the transition metal atom. L ² represents a ligand coordinated to a transition metal atom, and at least one L ² is a ligand having the same cyclopentadienyl skeleton as L ^1, and a ligand having a cyclopentadienyl skeleton. L ² other than a child is a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, a halogen atom, or a hydrogen atom as in L ¹ described above.

One or more ligands having a cyclopentadienyl skeleton are coordinated to the transition metal M ¹ , and preferably two are coordinated. Hereinafter, represented by the above formula (II),
Specific examples of the transition metal compound in which M ¹ is zirconium are shown below. Bis (diclopentadienyl) zirconium monochloride monohydride, bis (diclopentadienyl) zirconium monopromide monohydride, bis (dichloropentadienyl) methyl zirconium hydride, bis (diclopentadienyl) ethyl zirconium hydride, bis (Diclopentadienyl) phenyl zirconium hydride, bis (diclopentadienyl) benzyl zirconium hydride, bis (diclopentadienyl) neopentyl zirconium hydride, bis (methylcyclopentadienyl) zirconium monochloride hydride, bis (indenyl) ) Zirconium monochloride monohydride, bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zyl Niumujipuromido, bis (cyclopentadienyl) methyl zirconium monochloride, bis (cyclopentadienyl)
Ethyl zirconium monochloride, bis (cyclopentadienyl) cyclohexyl zirconium monochloride, bis (cyclopentadienyl) phenyl zirconium monochloride, bis (cyclopentadienyl) pencil zirconium monochloride, bis (methylcyclopentadienyl) Zirconium chloride, bis (dimethylcyclopentadienyl) zirconium dichloride, bis (n-butylcyclopentadienyl) zirconium dichloride,
Bis (methylethylcyclopentadienyl) zirconium dichloride, bis (methyl n-butylcyclopentadienyl) zirconium dichloride, bis (indenyl)
Zirconium dichloride, bis (indenyl) zirconium dipromide, bis (cyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) zirconium diphenyl, bis (cyclopentadienyl) zirconium dibenzyl, bis (cyclopentadienyl) zirconium Methoxy chloride, bis (cyclopentadienyl) zirconium ethoxycyclolide, bis (methylcyclopentadienyl) zirconium ethoxycyclolide,
Bis (cyclopentadienyl) zirconium phenoxycyclolide, bis (fluorenyl) zirconium dichloride and the like.

In the above-mentioned zirconium compound, a transition metal compound in which zirconium metal is replaced by titanium metal, hafnium metal, chromium metal or panadium metal can also be used.

The organoaluminum oxy compound (B) in the catalyst may be a conventionally known aluminoxane or a benzene-insoluble organoaluminum oxy compound as exemplified in JP-A-2-78687. Is also good.

In producing the ethylene copolymer, (C) an organoaluminum compound can be used, if necessary, in addition to the above-mentioned (A) transition metal compound and (B) organoaluminum oxy compound. As the organoaluminum compound (C), for example, an organoaluminum compound represented by the following formula can be exemplified. R ¹ _n AlX _{(3-n) In the} formula, R ¹ represents a hydrocarbon group having 1 to 12 carbon atoms such as an alkyl group, a cycloalkyl group, and an aryl group;
Represents a halogen atom or a hydrogen atom, and n is 1 to 3.

Examples of such organoaluminum compounds include trialkylaluminum, alkenylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, alkylaluminum dihalide, and alkylaluminum hydride, and in particular, triethylaluminum and triisobutylaluminum. preferable.

As the organoaluminum compound, the following
A compound represented by the formula can also be used. R¹ _n AlY_(3-n) Where R¹Is the same as above, and Y is -OR_TwoGroup, -OS
iR_ThreeGroup, -OSiR_FourGroup, -NR_FiveGroup, -SiR₆Base
Is -N (R₇) AlR₈N is 1-2, and R
_Two, R_Three, R_FourAnd R₈Is a methyl group, an ethyl group,
Pill, isoptyl, cyclohexyl, phenyl
R5 represents hydrogen, methyl group, ethyl group, isoprene
Propyl, phenyl, trimethylsilyl, etc.
R ₆And R₇Represents a methyl group, an ethyl group or the like.

[0029] Among such organic aluminum compounds include compounds represented by _{^{R l n Al (OAlR 4)}} 3-n, e.g., _{Et 2 AlOAlEt 2, (iso-} Bu) 2 AlOAl
(Iso-Bu) ₂ or the like is preferable. Among the above organoaluminum compounds of the general formula R ¹ a compound represented by ₃ Al it is preferred, and compounds where R ¹ is isoalkyl group. These organoaluminum compounds can be used as a mixture of two or more kinds.

Further, the fine particle carrier is inorganic.
Or an organic compound having a particle size of 10 to 300 μm,
Preferably 20 to 200 μm granular or fine particles
Solids are used. Of these, porous acids are used as inorganic carriers.
Are preferred, especially SiO 2 _TwoAnd Al_TwoO_ThreeFrom herd
With at least one selected from the main components
Is preferred. Olefin (co) as organic compound carrier
To mention granular or particulate solid such as polymer
Can be. The transition metal compound or the like is
Is prepolymerized on the supported solid catalyst
A pre-polymerization catalyst can also be used. Used in the present invention
Ethylene copolymer in the presence of a catalyst as described above,
Ethylene and an α-olefin having 3 to 20 carbon atoms
Is obtained by copolymerizing This copolymer smells
And ethylene and α-olefin having 3 to 20 carbon atoms.
The copolymerization with the resin is carried out in a gas phase or slurry.
In slurry polymerization, an inert hydrocarbon is used as a medium.
Alternatively, the olefin itself may be used as the medium.

In carrying out the slurry polymerization method, the polymerization temperature is usually in the range of -50 to 100 ° C, up to 120 ° C, preferably 20 to 100 ° C. The polymerization pressure is usually from normal pressure to 100 kg / cm ² , preferably ² to 50 kg / cm ² .
The polymerization can be performed in any of a batch system, a semi-continuous system, and a continuous system under a pressurized condition of cm ² . Further, the polymerization can be performed in two or more stages having different reaction conditions. When polymerizing by the slurry polymerization method or the gas phase polymerization method, the transition metal compound (A) is usually 10 ⁻⁸ to 10 ⁻⁸ in terms of transition metal atoms per liter of polymerization volume.
It is used in an amount of 10 ^-2 mmol, preferably 10 ^-7 to 10 ^-3 mmol. Organic aluminum oxy compound (B)
Is generally used in an amount of about 1 to 10,000 mol, preferably 10 to 5,000 mol, in terms of aluminum atom per 1 mol of transition metal compound atom. The organoaluminum compound (C) is generally used in an amount of about 0 to 200 mol, preferably about 0 to 10 mol, per 1 mol of aluminum atoms in the organoaluminum oxy compound (B).
It is used as needed in such an amount that it becomes 0 mol.

Such an ethylene copolymer may be used, if necessary, as long as the object of the present invention is not impaired, such as an antioxidant, a heat stabilizer, a weather stabilizer, carbon black, a pigment, a lubricant, and a crosslinking accelerator. And various additives usually added to polyolefins, such as antistatic agents, antifogging agents, antiblocking agents, slip agents, dyes, droplets, and fillers.

In order to form an insulator for a power cable from such an ethylene copolymer, use is made of this copolymer or an insulating composition obtained by adding a crosslinking agent, a crosslinking accelerator or the like thereto.
It is performed by a usual extrusion coating method. At this time, the insulator may be extrusion-coated together with the inner semiconductive layer and the outer semiconductive layer by a coextrusion method. It goes without saying that the crosslinked insulator is further sent to a crosslinked cylinder, heated and crosslinked. Also, to form the insulator of the extrusion mold connection, the conductor of the above-described power cable is pressed and connected using a conductor connection pipe to form a conductor connection, and an internal semiconductive layer is attached thereto, and then This is accommodated in a mold, the above-mentioned insulating composition is melt-extruded from an extruder, injected into the mold, filled, and then an external semiconductive layer is attached. This is performed by a method such as heating to crosslink. Hereinafter, the operation and effect will be clarified by showing specific examples. The present invention is not limited to these specific examples.

(Examples 1 to 3 and Comparative Examples 1 to 5) In this example and comparative examples, the impulse resistance, the tensile properties, and the extrudability were measured as follows. [Impulse Breakdown Strength] Resin pellets were washed with acetone to remove foreign substances, a 200 μm-thick recess sheet was prepared, and measured by applying 5 kV steps three times. The impulse breakdown strength is based on HP-LDPE A,
Those showing a value of 5% or more were indicated by ◎. [Tensile strength] A presheet having a thickness of 2 mm was prepared at a temperature of 165 ° C, and measured at 23 ° C according to ASTM D638. [Extrusion workability] The minimum extrusion amount per unit time at which skin roughness occurs at an extrusion temperature of 140 ° C was measured. The greater the minimum extrusion amount at which the surface roughness occurs, the less the resin is likely to be roughened and the better the workability. With an extruder of φ25mm, L / D = 25,
The strand was extruded using a φ3 mm die. HP
-Within ± 10% based on the LDPE A value.
Up to 30% was indicated by Δ, and below that was indicated by ×.

[0035]

[Table 1]

(Examples 4 to 6, Comparative Examples 6 to 10) To 100 parts by weight of resin pellets having the physical properties shown in Table 2, 2 parts by weight of dicumyl peroxide as a cross-linking agent and Nocrack 300 as an antioxidant were added. After adding 2 parts by weight and kneading with a roll, the mixture was pressed at 180 ° C. for 40 minutes to reduce the thickness of the recessed portion to 20%.
A crosslinked recess sheet of 0 μm was formed. Using this recess sheet, the impulse fracture strength, tensile properties, and gel fraction were measured. The gel fraction was measured according to JIS C300
In accordance with 5, the crosslinked sheet was put into xylene at a temperature of 110 ° C. to dissolve it, the insoluble residue was filtered, and the weight ratio was calculated from the weight ratio. Table 2 shows the results.

[0037]

[Table 2]

From the results shown in Tables 1 and 2, it can be seen that this ethylene copolymer is superior in extrudability as compared with conventional LLDPE. Further, it is apparent that the power cable and the extruded mold connection having the insulator made of the ethylene copolymer have excellent impulse resistance and mechanical strength.

[0039]

As described above, the power cable and the extruded mold connecting portion of the present invention are a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, and have a density of 890 to 940 kg /. in the range of m ^3, the ratio Mw / M of the weight-average molecular weight (Mw) to number average molecular weight (Mn)
n is in the range of 3.5 to 10.0, and the melt tension (MT (g)) at 190 ° C. and 190 ° C., 2.16
Melt flow rate at kg load (MFR (g / 1
0 min)) satisfies the relationship expressed by MT> 4.0 × MFR ^0.56 , and the flow index (FI (se
c ⁻¹ )) and the melt flow rate (MFR (g / 10 min)) at 190 ° C. and a load of 2.16 kg are FI
Since it has an insulator made of an ethylene copolymer or a cross-linked ethylene copolymer satisfying the relationship of> 150 × MFR, the insulator has good extrudability and excellent impulse resistance and mechanical strength. It becomes what has.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Miyata 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Shinichi Nagano 3rd Chigusa Kaigan, Ichihara-shi, Chiba Mitsui Chemicals, Inc. F term (reference) 4F070 AA13 AB21 AB22 AB24 AC56 AE08 GA05 GC05 GC07 4J100 AA02P AA03Q AA04Q AA07Q AA09Q AA15Q AA16Q AA17Q AA18Q AA19Q AA21Q CA04 DA04 DA13 DA14 DA42 HA53 HC36 A14 AB04 AB05 A305

Claims (5)

[Claims] 1. A copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, wherein (1) the density (d) is in the range of 890 to 940 kg / m ³ ,
(2) Weight average molecular weight (Mw) and number average molecular weight (Mn)
And Mw / Mn in the range of 3.0 to 10.0,
(3) Melt tension at 190 ° C. (MT
(G)) and the melt flow rate (MFR (g / 10 min)) at 190 ° C. under a load of 2.16 kg satisfy the relationship of MT> 4.0 × MFR ^0.56 , and (4) the flow index (Fl ( sec ^-1 )) and a melt flow rate (MFR (g / 10 mi) at 190 ° C. and a load of 2.16 kg.
n)) is a power cable having an insulator made of an ethylene copolymer satisfying a relationship represented by Fl> 150 × MFR. 2. The power cable according to claim 1, wherein the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the ethylene copolymer is in the range of 3.5 to 10.0. 3. The power cable according to claim 1, wherein the insulator is cross-linked. 4. It is obtained by a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, and (1) the density (d) is in the range of 890 to 940 kg / m ³ ,
(2) Weight average molecular weight (Mw) and number average molecular weight (Mn)
And Mw / Mn in the range of 3.0 to 10.0,
(3) Melt tension at 190 ° C. (MT
(G)) and the melt flow rate (MFR (g / 10 min)) at 190 ° C. under a load of 2.16 kg satisfy the relationship of MT> 4.0 × MFR ^0.56 , and (4) the flow index (Fl ( sec ^-1 )) and a melt flow rate (MFR (g / 10 mi) at 190 ° C. and a load of 2.16 kg.
n)) is an extrusion-molded connection portion having an insulator made of an ethylene copolymer satisfying a relationship represented by Fl> 150 × MFR. 5. The extrusion mold connection according to claim 4, wherein the insulator is cross-linked.