JPH0925373A - Electrical insulating material and power cable wherein it is used - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrical insulating material high in vol. resistance and little in dependence of vol. resistance on temp. SOLUTION: This electrical insulating material consists of a resin comprising an ethylene (co)polymer of at most 0.4eV in electric activation energy satisfying the below-cited physical properties (A) to (D) and obtd. by (co)polymn. of ethylene or ethylene and a 3-20C α-olefin in the presence of a catalyst contg. at least one of transition metal compds. contg. a ligand having a cyclopentadienyl skeleton with the transition metal belonging to the group IV in the periodic table. (A) density: 0.86 to 0.97g/cm<3> . (B) melt flow rate(MFR): 0.01 to 100g/10min. (C) mol.wt. distribution (Mw/Mn): 1.5 to 5.0. (D) composition distribution parameter Cb: at most 1.15.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrical insulating material comprising a novel ethylene (co) polymer and a composition of the same and another polyolefin and having a high volume resistance and excellent electrical characteristics, and a high voltage power using the same. Regarding cables.

[0002]

2. Description of the Related Art Conventionally, high-voltage polyethylene and cross-linked polyethylene have been widely used as insulators for high-voltage power cables because of their excellent electrical characteristics. One of the problems of high voltage power cables is power loss during high voltage power transmission, and reducing it is an important issue. One means of reducing this power loss can be achieved by increasing the high voltage characteristics of the insulating material, especially the volume resistance. However, in the insulator for a power cable, the temperature is high (about 90 ° C.) near the inner conductor due to Joule heat due to current, but the temperature is the outside air (about 20 ° C.) near the outer conductor. With conventional polyethylene, the volume resistance decreases significantly with increasing temperature, so the volume resistance near the inner conductor where current is flowing decreases significantly, and the electric field concentrates near the outer conductor-insulator interface, causing a breakdown value. Is reduced. This phenomenon becomes a serious problem especially in DC power cables. For this reason, a material whose volume resistance has a small temperature dependence is desired. The use of high-voltage polyethylene as a high-voltage cable insulator has a drawback that it has a low melting point and poor electrical characteristics at high temperatures. On the other hand, the conventional low-pressure polyethylene having a high melting point has the drawback that it is not affected by the catalyst residue and does not have excellent electrical characteristics, and is inferior in flexibility. A method of grafting and improving maleic anhydride in order to improve the electrical properties of low-pressure polyethylene has been proposed (for example, Japanese Patent Application Laid-Open No. 2-10610), but it is not always satisfactory including the problem of flexibility. Not going. Furthermore, as a material having excellent heat resistance and flexibility and high volume resistance, low density polyethylene having a density of 0.92 g / cm ³ and density of 0.
An insulator (Japanese Patent Laid-Open No. 5-266723) obtained by blending 0.5 parts by weight or more and 20 parts by weight or less of linear low-density polyethylene of 91 to less than 0.94 g / cm ³ is disclosed. However, the above composition is still not sufficiently satisfactory because the volume resistance near the inner conductor has a large temperature dependency.

[0003]

[Problems to be Solved by the Invention] To provide an insulating material comprising an ethylene (co) polymer alone or a composition of the same and another polyolefin, which has a high volume resistance and a small volume resistance temperature dependence. is there.

[0004]

Means for Solving the Problems As a result of intensive studies in view of the above objects, the present inventors have found that an ethylene (co) polymer polymerized by a specific catalyst and having a low electric activation energy, and The above object has been achieved by using a composition with another polyolefin.

That is, the first aspect of the present invention is to provide ethylene or ethylene and carbon number in the presence of a catalyst containing at least one transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton. (A) ethylene (co) which is obtained by (co) polymerizing with 3 to 20 α-olefin and satisfies the following (A) to (D) and has an electrical activation energy of 0.4 eV or less. ) An electrical insulating material comprising a resin containing a polymer. (A) Density 0.86 to 0.97 g / cm ³ (B) Melt flow rate (MFR) 0.01 to 100 g / 10 min (C) Molecular weight distribution (Mw / Mn) 1.5 to 5.0 (D) Composition distribution parameter Cb 1.15 or less

A second aspect of the present invention is the electrical insulating material according to claim 1, wherein the (a) ethylene (co) polymer and (b) another polyolefin up to 98% by weight are contained.

A third aspect of the present invention is the above electrical insulating material, wherein the (b) another polyolefin is polyethylene by a high pressure radical polymerization method.

A fourth aspect of the present invention is a power cable characterized by using the electrical insulating material made of the resin described in any one of the first to third aspects.

A fifth aspect of the present invention is the power cable according to the fourth aspect, wherein the power cable is a DC power cable. The electrically insulating material referred to in the present invention also includes a material obtained by crosslinking the resin.

The present invention will be described in detail below. The ethylene (co) polymer in the present invention is present in the presence of a catalyst containing a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentanyl skeleton and, if necessary, a promoter, an organoaluminum compound and a carrier. Is obtained by copolymerizing ethylene or ethylene and an α-olefin having 3 to 20 carbon atoms. Further, the catalyst obtained by preliminarily polymerizing ethylene and / or the α-olefin with the above catalyst may be used as the catalyst. The α-olefin has 3 to 20 carbon atoms, preferably 3 to 12 carbon atoms.
Specifically, propylene, butene-1, 4,
-Methylpentene-1, hexene-1, octene-1,
Examples thereof include decene-1 and dodecene-1. The content of these α-olefins is usually 30 mol% or less, preferably 0.5 to 25 mol%.

The cyclopentadienyl skeleton of a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, which is a catalyst for producing the ethylene (co) polymer of the present invention, is Examples thereof include a cyclopentadienyl group and a substituted cyclopentadienyl group. Examples of the substituted cyclopentadienyl group include a hydrocarbon group having 1 to 10 carbon atoms, a silyl group, a silyl-substituted alkyl group, a silyl-substituted aryl group,
And a substituted cyclopentadienyl group having at least one substituent selected from a cyano group, a cyanoalkyl group, a cyanoaryl group, a halogen group, a haloalkyl group, a halosilyl group, and the like. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may be bonded to each other to form a ring.

Examples of the hydrocarbon group having 1 to 10 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and the like. Specific examples include a methyl group, an ethyl group, an n-propyl group and isopropyl. Group, n-butyl group,
Alkyl groups such as isobutyl group, sec-butyl group, t-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group and decyl group; cycloalkyl groups such as cyclopentyl group and cycloalkyl group; phenyl group and tolyl And an aralkyl group such as a benzyl group and a neofuyl group. Among these, an alkyl group is preferable. Preferred examples of the substituted cyclopentadienyl group include a methylcyclopentadienyl group, an ethylcyclopentadienyl group, an n-hexylcyclopentadienyl group, a 1,3-dimethylcyclopentadienyl group,
3-n-butylmethylcyclopentadienyl group, 1,3
Specific examples thereof include -n-propylmethylethylcyclopentadienyl group. Among these, the substituted cyclopentadienyl group of the present invention is preferably a cyclopentadienyl group substituted with an alkyl group having 3 or more carbon atoms,
A 1,3-substituted cyclopentadienyl group is particularly preferable.
The substituted cyclopentadienyl group in the case where the substituents, ie, the hydrocarbons, are bonded to each other to form one or more rings, an indenyl group, a hydrocarbon group having 1 to 8 carbon atoms (such as an alkyl group), etc. A substituted naphthyl group substituted with a substituent such as a substituted indenyl group substituted with a substituent of, a naphthyl group, a hydrocarbon group having 1 to 8 carbon atoms (such as an alkyl group), a hydrocarbon group having 1 to 8 carbon atoms ( Substituted fluorenyl groups substituted by a substituent such as an alkyl group) are preferable.

Examples of the transition metal of the group IV transition metal compound containing a ligand having a cyclopentadienyl skeleton include zirconium, titanium and hafnium, with zirconium being particularly preferred. The transition metal compound usually has 1 to 3 ligands having a cyclopentadienyl skeleton, and when they have 2 or more ligands, they may be bonded to each other by a bridging group. Examples of the cross-linking group include an alkylene group having 1 to 4 carbon atoms, an alkylsilanediyl group, and a silanediyl group.

As a ligand other than the ligand having a cyclopentadienyl skeleton in the transition metal compound of Group IV of the periodic table, hydrogen and C 1 to C 2 are typical.
And a hydrocarbon group of 0 (alkyl group, alkenyl group, aryl group, alkylaryl group, aralkyl group, polyenyl group, etc.), halogen, metaalkyl group, metaaryl group and the like.

Specific examples of these are as follows. As dialkyl metallocenes, bis (cyclopentadienyl) titanium dimethyl, bis (cyclopentadienyl) titanium diphenyl, bis (cyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) zirconium diphenyl, bis (cyclopentadienyl) ) Hafnium dimethyl, bis (cyclopentadienyl) hafnium diphenyl and the like. Monoalkyl metallocenes include bis (cyclopentadienyl)
Examples include titanium methyl chloride, bis (cyclopentadienyl) titanium phenyl chloride, bis (cyclopentadienyl) zirconium methyl chloride, and bis (cyclopentadienyl) zirconium phenyl chloride. In addition, monocyclopentadienyl titanocene such as pentamethylcyclopentadienyl titanium trichloride, pentaethylcyclopentadienyl titanium trichloride), and bis (pentamethylcyclopentadienyl) titanium diphenyl are exemplified.

The substituted bis (cyclopentadienyl) titanium compound includes bis (indenyl) titanium diphenyl or dichloride, bis (methylcyclopentadienyl) titanium diphenyl or dichloride, dialkyl, trialkyl, tetraalkyl, and pentaalkylcyclo Examples of the pentadienyl titanium compound include bis (1,2-dimethylcyclopentadienyl) titanium diphenyl or dichloride, bis (1,2-diethylcyclopentadienyl) titanium diphenyl or dichloride or other dihalide complex, silicon, amine Alternatively, as the carbon-linked cyclopentadiene complex, dimethylsilyldicyclopentadienyl titanium diphenyl or dichloride, methylenedicyclopentadienyl complex Data iodonium diphenyl or dichloride, and other dihalide complexes.

As the zirconocene compound, pentamethylcyclopentadienyl zirconium trichloride,
Pentaethylcyclopentadienyl zirconium trichlorite, bis (pentamethylcyclopentadienyl)
Examples of zirconium diphenyl and alkyl-substituted cyclopentadiene include bis (ethylcyclopentadienyl) zirconium dimethyl, bis (methylcyclopentadienyl) zirconium dimethyl, bis (n-butylcyclopentadienyl) zirconium dimethyl, haloalkyl or dihalide thereof. As the complex, dialkyl, trialkyl, tetraalkyl or pentaalkylcyclopentadiene, bis (pentamethylcyclopentadienyl) zirconium dimethyl, bis (1,2-dimethylcyclopentadienyl) zirconium dimethyl, and dihalide complexes thereof, silicon As the carbon-linked cyclopentadiene complex, dimethylsilyldicyclopentadienylzirconium dimethyl or dihalide, methylenedicyclopentene Dienyl zirconium dimethyl or dihalide, such as methylene dicyclopentadienyl zirconium dimethyl or dihalide, and the like.

Examples of other metallocenes include bis (cyclopentadienyl) hafnium dichloride, bis (siccopentadienyl) hafnium dimethyl and bis (cyclopentadienyl) vanadium dichloride.

As another example of the transition metal compound of Group IV of the periodic table of the present invention, a ligand having a cyclopentadienyl skeleton represented by the following general formula (1) and other ligands and transitions The thing in which a metal atom forms a ring is also mentioned.

[0020]

(Equation 1)

In the formula, CP is a ligand having the cyclopentadienyl skeleton, X is hydrogen, halogen, and having 1 to 2 carbon atoms.
0 represents an alkyl group, an arylsilyl group, an aryloxy group, an alkoxy group, an amido group, a silyloxy group, etc., and Y represents —O—, —S—, —NR—, —PR— or O.
A divalent neutral ligand selected from the group consisting of R, SR, NR ₂ , and PR ₂ , Z is SiR ₂ , CR ₂ , SiR ₂ SiR
₂ , CR ₂ CR ₂ , CR = CR, SiR ₂ CR ₂ , BR
₂ represents a divalent group selected from the group consisting of BR. Here, R is hydrogen or an alkyl group having 1 to 20 carbon atoms, an aryl group, a silyl group, a halogenated alkyl group, a halogenated aryl group, or Y, Z or 2 from both Y and Z.
One or more R groups form a fused ring system. M represents a transition metal atom of Group IV of the periodic table.

As an example of the compound represented by the formula 1, (t
-Butylamide) (tetramethylcyclopentadienyl) -1,2-ethanediylzirconium dichloride, (t-butylamide) (tetramethylcyclopentadienyl) -1,2-ethanediyltitanium dichloride, (methylamide) (tetramethyl Cyclopentadienyl) -1,2-ethanediylzirconium dichloride, (methylamide) (tetramethylcyclopentadienyl) -1,2-ethanediyltitanium dichloride,
(Ethylamide) (tetramethylcyclopentadienyl) methylene titanium dichloride, (t-butylamido) dimethyl (tetramethylcyclopentadienyl) silanetitanium dichloride, (t-butylamido) dimethyl (tetramethylcyclopentadienyl) silanezirconiumdichloride Benzyl, (benzylamido) dimethyl (tetramethylcyclopentadienyl) silanetitanium dichloride, (phenylphosphido) dimethyl (tetramethylcyclopentadienyl) silanetitanium dichloride and the like.

As the co-catalyst in the present invention, the transition metal compound of Group IV of the periodic table can be effectively used as a polymerization catalyst, or the ionic charge in a catalytically activated state can be balanced. Say something. Examples of the co-catalyst used in the present invention include benzene-soluble aluminoxane, benzene-insoluble organic aluminum oxy compound, boron compound, lanthanide salts such as lanthanum oxide, and tin oxide of the organic aluminum oxy compound. Of these, aluminoxane is most preferable.

The catalyst may be used by supporting it on an inorganic or organic compound carrier. Specifically, SiO ₂ , A
l ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , C
Examples thereof include aO, ZnO, BaO, ThO _{2 and the} like, or a mixture thereof, such as SiO ₂ —Al ₂ O ₃ and SiO ₂ —V _2.
O ₅ , SiO ₂ —TiO ₂ , SiO ₂ —MgO, SiO
₂ -Cr ₂ O ₃ and the like. Among them, SiO
It is preferable that the main component is at least one component selected from the group consisting of ₂ and Al ₂ O ₃ .

Examples of the organic aluminum compound include trialkyl aluminum such as triethyl aluminum and triisopropyl aluminum; dialkyl aluminum halide; alkyl aluminum sesquihalide; alkyl aluminum dihalide; alkyl aluminum hydride and organic aluminum alkoxide.

The (a) ethylene (co) polymer production method of the present invention is produced by a gas phase polymerization method, a slurry polymerization method, a solution polymerization method or the like in the presence of the above-mentioned catalyst, in which substantially no solvent is present. Are preferably produced by a gas phase method. The polymerization is
In a state where oxygen, water, etc. are substantially turned off, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; aromatic hydrocarbons such as benzene, toluene, and xylene; and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane It is produced in the presence or absence of an inert hydrocarbon solvent exemplified as above. The polymerization conditions are not particularly limited, but the polymerization temperature is usually 15 to 350 ° C, preferably 20 to 200 ° C,
More preferably, it is 50 to 110 ° C., the polymerization pressure is usually normal pressure to 70 kg / cm ² G, preferably normal pressure to 20 kg / cm ² G in the case of the low and medium pressure method, and 1500 kg / cm ^{2 in} the case of the high pressure method. G or less is desirable. The polymerization time is usually from 3 minutes to 10 hours, preferably from 5 minutes to 5 hours in the case of the low and medium pressure method.
Time is desirable. In the case of the high pressure method, usually 1 minute to 30 minutes
Minutes, preferably about 2 to 20 minutes. In addition, the polymerization is not only a one-stage polymerization method, but also a hydrogen concentration, a monomer concentration,
There is no particular limitation on a multi-stage polymerization method of two or more stages in which polymerization conditions such as polymerization pressure, polymerization temperature, and catalyst are different from each other.

The (A) density of the (a) ethylene (co) polymer of the present invention is 0.86 to 0.97 g / cm ³ , preferably 0.88 to 0.95 g / cm ³ , and more preferably 0. The range is from 0.90 to 0.94 g / cm ³ . When the density is less than 0.86 g / cm ³ , the heat resistance is poor and the volume resistance is not improved in the high temperature region, and when it exceeds 0.97 g / cm ³ , the flexibility is insufficient.

The (B) MFR of the (a) ethylene (co) polymer of the present invention is 0.01 to 100 g / 10 min, preferably 0.1 to 50 g / 10 min, more preferably 0.5 to 40 g / 10 min. It is desirable to be in the range. If the MFR is less than 0.01 g / 10 min, the moldability will be poor, and if it exceeds 100 g / 10 min, the mechanical strength will be reduced.

The method of calculating the (C) molecular weight distribution Mw / Mn of the (a) ethylene (co) polymer of the present invention is to calculate the weight average molecular weight (Mw) and the number average molecular weight (Mw) by gel permeation chromatography (GPC). Mn) is obtained and this ratio Mw / Mn is obtained. The Mw / Mn obtained by the catalyst of the present invention is 1.5 to 5.0, preferably 1.6 to 4.8, and more preferably 1.8 to 4.5. If Mw / Mn is less than 1.5, the moldability is poor, and if it exceeds 5.0, the impact resistance is poor.

The (D) composition distribution parameter Cb of the (a) ethylene (co) polymer obtained by the catalyst of the present invention is 1.15 or less.

The method for measuring the composition distribution parameter Cb of the ethylene / α-olefin copolymer of the present invention is as follows.

A heat resistance stabilizer was added to the sample, and the sample was dissolved in orthodichlorobenzene (ODCB) by heating at 135 ° C. so that the sample concentration would be 0.2% by weight. This heated solution is transferred to a column packed with diatomaceous earth (Celite 545), filled and cooled to 25 ° C at 0.1 ° C / min to deposit and deposit a sample on the surface of Celite. Next, while flowing ODCB through the column at a constant flow rate, the column temperature was increased by 12 ° C. every 5 ° C.
While gradually increasing the temperature to 0 ° C., a solution in which the sample is dissolved is collected at each temperature. After cooling the solution, the sample is reprecipitated with methanol, filtered and dried to obtain samples at each elution temperature. The weight fraction and the degree of branching (the number of branches per 1000 carbon atoms) of the separated sample are measured. The degree of branching is measured by 13C-NMR.

For each fraction collected at 30 ° C. to 90 ° C. by the above method, the branching degree is corrected as follows. That is, the degree of branching measured against the elution temperature is plotted, and the correlation is approximated to a straight line by the least square method,
Create a calibration curve. The correlation coefficient of this approximation is large enough.
The value obtained from this calibration curve is defined as the degree of branching of each fraction. Note that, for a fraction collected at an elution temperature of 95 ° C. or higher, this correction is not performed because a linear relationship is not always established between the elution temperature and the degree of branching.

Next, the weight fraction wi of each fraction is calculated by the change amount (b) of the branching degree b _i per elution temperature of 5 ° C.
_i- b _i-1 ) to obtain the relative concentration ci, and plot the relative concentration against the branching degree to obtain a composition distribution curve. This composition distribution curve is divided by a certain width, and the composition distribution parameter Cb is calculated from the following equation.

[0035]

(Equation 2)

Here, c _j and b _j are the relative density and branching degree of the j-th section, respectively. Composition distribution parameter C
b becomes 1.0 when the composition of the sample is uniform, and becomes larger as the composition distribution becomes wider.

Many methods have been proposed for describing the composition distribution of ethylene / α-olefin copolymers. For example, in Japanese Patent Application Laid-Open No. 60-88016, numerical processing is performed on the assumption that the cumulative weight fraction has a specific distribution (log normal distribution) with respect to the number of branches of each separated sample obtained by solvent separation of the sample. The ratio between the weight average branching degree (Cw) and the number average branching degree (Cn) is determined. The accuracy of this approximate calculation is low when the number of branches of the sample and the cumulative weight fraction deviate from the lognormal distribution, and the correlation coefficient R ₂ is considerably low when the measurement is performed on commercially available LLDPE, and the accuracy of the value is not sufficient. This Cw
/ Cn and Cb of the present invention have different definitions and measurement methods.

The electrical activation energy of the (a) ethylene (co) polymer of the present invention must be 0.4 eV or less, preferably 0.3 eV or less. Those having a voltage of more than 0.4 eV have a large temperature dependence of volume resistance.

The activation energy is one of the constants included in the Arrhenius equation representing the temperature change of the rate constant in the process of transport phenomenon, and transitions in the process of transition from the original system to the transition system to the production system. It corresponds to the energy difference between the state and the state of the original system. In particular, electrical activation energy is used in the Arrhenius equation that shows the temperature dependence of current. Here, the small activation energy indicates that the temperature dependence of the current is small. The method of measuring activation energy according to the present invention is as follows. The activation energy can be obtained from the following equation (Arrhenius equation). I ∝ exp (-U / kT) (I: current, U: activation energy, k: Boltzmann's constant, T: absolute temperature) In the above formula, when measuring the volume resistance at room temperature (20 ° C) and 90 ° C. It can be obtained by substituting the current value at. The method for measuring the volume resistance will be described later.

The (b) other polyolefin in the present invention means a hydrocarbon homo- or copolymer represented by the general formula CnH2n. Specific examples of the hydrocarbon include ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene and 2-methyl-1-.
Butene, 3-methyl-1-butene, 2-methyl-2-butene, 2,3-dimethyl-2-butene, 4-methyl-1
-Pentene, 1-heptene, 1-octene, 1-nonene, 1-decene and the like.

Specific examples of the above (b) other polyolefins include high / medium density polyethylene, linear low density polyethylene, ultra low density polyethylene, polypropylene, polybutene, poly-4-methyl-1-pentene, and ethylene / α-.
Examples thereof include olefin copolymer rubber, ethylene-propylene copolymer rubber (EPR), high pressure radical method low density polyethylene, and high pressure radical method ethylene copolymer. Among the above-mentioned polyolefins, the high-pressure radical method low-density polyethylene is particularly preferable because it has excellent electrical properties, processability and flexibility.

The high-pressure radical method low-density polyethylene is a branched low-density polyethylene (LDPE), which is generally used in a tank reactor or a tubular reactor in the presence of a radical initiator at a normal pressure of 500 to 3000 kg. /
It is obtained by polymerizing ethylene at cm ² and a temperature of 150 to 330 ° C. Its MFR is 0.1
100g / 10min, preferably 0.2-50g / 1
It is 0 min. Those in this range have high melt tension and are easy to mold.

The blending amount of the other polyolefin (b) with respect to the ethylene (co) polymer (a) is 0 to 98% by weight. (A) When it is desired to maintain the excellent electrical characteristics of the ethylene (co) polymer, (A) is 100 to 70% by weight. Further, (b) when it is desired to utilize the processability and economy of other polyolefins, it is desirable to add (a) 70 to 2% by weight.

When used after cross-linking, which will be described later,
(A) Ethylene (co) polymer 30 to 10% by weight, (b)
It is desirable that 70 to 90% by weight of other polyolefin is blended.

In the present invention, the composition may be used as it is when it is used as an electric insulating material, but it is preferably crosslinked to improve heat resistance. The method of cross-linking is not particularly limited, and a method using a radical generator such as an organic peroxide, a method of performing electron beam cross-linking, a silane cross-linking or the like can be mentioned, but it is economically inexpensive. Therefore, the method using a radical generator such as an organic peroxide is preferable.

Radical generators used include benzoyl peroxide, lauryl peroxide, dicumyl peroxide, t-butyl hydroxyperoxide, α, α-bis (t-butylperoxydiisopropyl) benzene, di-t-butyl. Peroxide, 2,5
-Di-methyl-2,5-di- (t-butylperoxy)
Hexine, 2,5-di-methyl-2,5-di- (t-butylperoxy) hexane, peroxides such as azobisisobutyronitrile, 2,3-dimethyl-2,3-diphenylbutane , 2,3-diethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-di (p-methylphenyl) butane, 2,3-diethyl-2,3-di (bromophenyl) butane, etc. Is mentioned.

Among the above radical generators, 2,5-di-
Methyl-2,5-di (t-butylperoxy) hexine, 2,5-di-methyl-2,5-di- (t-putylperoxy) hexane, dicumyl peroxide and the like are preferably used. The blending amount is 0.01 to 5 parts by weight, preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the resin component.
Used in the range of 3 parts by weight.

The electric insulating material of the present invention is used as an electric wire cable and a power cable. In addition, it is also used as an insulating material for capacitors, insulation of high voltage parts such as an X-ray generator, various measuring equipment, containers for dry and wet batteries. Insulation, various printed boards,
Used as various connectors, power distribution coats, gloves for working with high-voltage current, and insulating materials for jigs and tools.

The power cable of the present invention is composed of an insulating layer, which is preferably crosslinked using the resin composition. A specific example of the power cable is a power cable in which an insulating layer is formed by coating a conductor with at least a cross-linked electrical insulating material of the present invention, and if necessary, the conductor portion may be a bundled wire or insulated from the conductor. A semiconductive layer can be provided between the layers, or a flame-retardant resin layer can be formed outside the insulating layer.
The electrical insulating material of the present invention is particularly effective for high-voltage electricity.

In the power cable of the present invention, it is preferable to crosslink during coating. The radical generator may be blended in advance and crosslinked by heating, or it may be crosslinked by using radiation or the like.

Cooling after molding is optional such as natural cooling and cooling in a water tank, but it is desirable to cool relatively slowly for the reason of not generating a defective portion (void) inside.

The crosslinked resin composition for an insulating material of the present invention is excellent in insulating property and also has elasticity so that it is most suitable for coating electric wires, but it can be widely used without being limited to DC / AC power sources. However, it has a small temperature dependence of volume resistance and excellent electric characteristics, and can be suitably used especially as a power cable for high-voltage DC.

[0053]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

(Preparation of Volume Resistance Measurement Sample) 1. Preparation of Volume Resistance Measurement Sample The blend of the ethylene (co) polymer and the polyolefin to be measured is kneaded with a plastomill at 160 ° C. for 5 minutes,
A sheet having a thickness of 0.3 mm was formed by hot pressing. The conditions for hot pressing were as follows: ・ The uncrosslinked sample was molded under the following conditions by sandwiching the sample between aluminum sheets. 1) Preheat the sample at 140 ° C for 5 minutes 2) Press at 140 ° C and 100 kg / cm ² for 5 minutes 3) Cool under pressure from 140 ° C to 30 ° C for 5 minutes A sample prepared by kneading 2 parts by weight of oxide was sandwiched between Teflon sheets and molded under the following conditions. 1) Preheat the sample at 120 ° C for 5 minutes 2) Pressurize at 120 ° C and 100 kg / cm ² for 5 minutes 3) Cool under pressure from 120 ° C to 30 ° C for 5 minutes, excluding the sample containing voids at this time 4) Preheat again at 120 ° C for 5 minutes 5) Pressurize at 120 ° C for 5 minutes at 100 kg / cm ² 6) Increase temperature from 120 ° C to 160 ° C under pressure 7) Crosslink at 160 ° C for 30 minutes under pressure 8) Cool under pressure from 120 ° C to 30 ° C in 5 minutes Blended product with polyolefin is 160 in Plastomill
It was prepared by kneading at 5 ° C for 5 minutes. A sheet having a thickness of 0.3 mm was formed by hot pressing.

(Measurement of Volume Resistance) FIGS. 1 (a) and 1 (b)
The electrode system shown in was used. FIG. 1A is a plan view of FIG.
(B) is a side view thereof, and is numbered 11 in the figure.
Is the main electrode (50 mmφ), 12 is the guard electrode (inner diameter 75
mmφ, outer diameter 80 mmφ), 13 is a sample, 14 is a high-voltage electrode (80 mmφ), a main electrode is connected to an oscillating capacitance type ammeter, and a high-voltage electrode is connected to a high-voltage source by a cable. The electrode material was a stainless steel plate, and the surface in contact with the sample was polished to a mirror surface state with a buffing machine. In addition, the measurement was carried out by placing the sample in an electrode system as shown in FIGS. 1 (a) and (b), short-circuiting the upper and lower electrodes for 5 minutes to remove the charges charged on the sample surface, and then at room temperature and 90 ° C. It was performed under a nitrogen atmosphere. What was measured at 90 ° C. was short-circuited for 7 minutes so that the temperature in the sample became 90 ° C. uniformly. The applied voltage is 3300 V DC from the battery. A vibrating capacitance type ammeter (TR8411 manufactured by Advantest) was used as a measuring instrument. The cable connecting the measuring instrument and the electrodes was a pipe cable to remove extraneous noise. In this measurement system,
3 × ^{10 17} Ω at room temperature, can be measured stably to 90 ° C. In 3 × ^{10 16} Ω. The thickness of each sample was about 0.3 mm, and each sample was used by measuring up to two decimal places. The effective electrode area is 19.6 cm ² . From the examination of the current-time characteristics, it was set after 10 minutes that after the voltage application, the current decrease due to the absorption current disappeared and the current could be stably measured. Therefore, the current value after 10 minutes of voltage application is taken as the measured value, but if the current is not stable even after 10 minutes, measurement is waited for about 2 minutes until it stabilizes. Excluded from measurement. The volume resistance was determined based on the current value obtained from the measurement. Each measurement was performed 10 times, and the average value was used as data.

Samples A1 and A2 used in Examples 1 and 2 were polymerized by the following method.

(Polymerization of Sample A1) (1) Preparation of Catalyst Under a nitrogen atmosphere, 150 ml of purified toluene was added to a 500 ml eggplant type flask equipped with an electromagnetic induction stirrer, and then a toluene solution of bisindenyl zirconium dimethyl (concentration: 1 mmo).
2.5 ml of 1 / ml) and 200 ml of a toluene solution of methylalumoxane (concentration 1 mmol / ml) were added and reacted at room temperature for 1 hour. Next, silica was preliminarily fired at 600 ° C. for 5 hours in a 1.5-liter three-necked flask equipped with a stirrer under nitrogen (manufactured by Fuji Devison Co., grade # 952, surface area 300).
After adding 50 g of m ² / g), the whole amount of the solution was added and stirred at room temperature for 2 hours. Then, the solvent was removed by nitrogen blowing to obtain a powder having good fluidity. (2) Polymerization Using a continuous fluidized bed gas phase polymerization apparatus, polymerization temperature 70
Ethylene and butene-1 at 20 ℃ and total pressure of 20kgf / cm ² G
Was copolymerized. The gas composition in the system was such that the butene-1 / ethylene molar ratio was 0.08 and the ethylene concentration was 60 mol%. In order to maintain the gas composition in the system constant by continuously supplying the catalyst, polymerization was performed while each gas was continuously supplied. The MFR was prepared by adjusting the hydrogen concentration in the system. Table 1 shows the physical properties of the produced polymer.

(Polymerization of Sample A2) (1) Preparation of Catalyst Under a nitrogen atmosphere, 150 ml of purified toluene was added to a 500 ml eggplant type flask equipped with an electromagnetic induction stirrer, and then a toluene solution of bisindenyl zirconium dichloride (concentration: 1 m).
(ml / ml) (2.5 ml) and a toluene solution of methylalumoxane (concentration: 1 mmol / ml) (180 ml) were added, and the mixture was reacted at room temperature for 1 hour. Then under nitrogen 1.5 with stirrer
Silica pre-calcined in a three-necked flask at 600 ° C. for 5 hours (manufactured by Fuji Devison Co., grade # 952, surface area 30
After adding 50 g (0 m ² / g), the whole amount of the solution was added, and the mixture was stirred at room temperature for 2 hours. Then, the solvent was removed by nitrogen blowing to obtain a powder having good fluidity. (2) Polymerization Polymerization was performed under the same conditions as for sample Al. Table 1 shows the physical properties of the produced polymer.

(B1) is a linear low density polyethylene using Ziegler catalyst. Titanium tetrachloride and triethylaluminum catalyst are used.
Obtained by copolymerizing ethylene and 1-butene. Density 0.92
3 g / cm ³ and MFR 3.0 g / 10 min (B2) are low-density polyethylene produced by high-pressure radical polymerization (trade name: Nippon Petrochemical (manufactured) Nisseki Lexron W200).
0 density 0.919 g / cm ³ , MFR 1.0 / 10 m
in. The physical properties of the above sample are shown in Table 1.

[Examples 1 and 2, Comparative Examples 1 and 2] Table 2 compares the volume resistance and activation energy of uncrosslinked samples. Examples 1 and 2 are measured values of the samples (A1, A2).

[Comparative Example 1] The measured values of linear low density polyethylene (B1) using a Ziegler catalyst are shown in Table 2.
High activation energy and high temperature dependence, especially 90
Low volume resistance at ℃.

Comparative Example 2 These are the measured values of low density polyethylene (B2) by the high pressure radical polymerization method and are shown in Table 2. It has low volume resistance, high activation energy, and high temperature dependence.

[Examples 3 to 10] In Table 3, the sample (B1) was mixed with the sample (A1) and the volume resistance was measured without being crosslinked. The results were also compared with Example 1 and Comparative Example 2.

[Example 11] In Example 11 of Table 4, the volume resistance was measured for a mixture of 10% by weight of the sample (A2) and 90% by weight of the sample (B2).

Comparative Example 3 10% by weight of the sample (B1) was mixed with 90% by weight of the sample (B2), and the results are shown in Table 4. Low volume resistance.

Example 12 Table 5 shows measured values of crosslinked samples. The composition of 10% by weight of the sample (A1) of Example 9 and 90% by weight of (B2) was crosslinked by the above method.

[Comparative Example 4] This is the value of the volume resistance of the crosslinked product of Comparative Example 2. As shown in Table 5, the volume resistance is low.

FIG. 2 is a graph showing the examples and comparative examples shown in Table 3 among the above experimental examples.

[0069]

[Table 1]

[0070]

[Table 2]

[0071]

[Table 3]

[0072]

[Table 4]

[0073]

[Table 5]

[0074]

EFFECT OF THE INVENTION The electrical insulating material containing ethylene (co) polymer as a main component polymerized by the specific catalyst of the present invention has a large volume resistance and a small temperature dependence, and further has flexibility and processability. It is also a material having excellent electrical characteristics even after cross-linking and is suitable as an electrical insulating material. Further, when used as an insulating layer of a power cable, it is possible to reduce power loss during high voltage power transmission without thickening the insulating layer.

[Brief description of drawings]

[Figure 1] Volume resistance measuring device

FIG. 2 is a graph of Examples and Comparative Examples shown in Table 3.

[Explanation of symbols]

 11: Main electrode 12: Guard electrode 13: Sample 14: High voltage electrode

Claims (5)

[Claims] 1. In the presence of a catalyst containing at least one transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, ethylene or ethylene and α- having 3 to 20 carbon atoms is used. A resin containing an ethylene (co) polymer obtained by copolymerizing with an olefin, which satisfies the following (A) to (D) and has an electrical activation energy of 0.4 eV or less (a): An electrical insulating material characterized in that (A) Density 0.86 to 0.97 g / cm ³ (B) Melt flow rate (MFR) 0.01 to 100 g / 10 min (C) Molecular weight distribution (MW / Mn) 1.5 to 5.0 (D) Composition distribution parameter Cb 1.15 or less 2. The electrical insulating material according to claim 1, wherein the resin contains the (a) ethylene (co) polymer and (b) another polyolefin up to 98% by weight. 3. The electrical insulating material according to claim 1, wherein the other polyolefin (b) is polyethylene produced by a high-pressure radical polymerization method. 4. A power cable comprising the electrical insulating material made of the resin according to claim 1. 5. The power cable according to claim 4, wherein the power cable is a DC power cable.