JP3345737B2 - Electrical insulation and power cable using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric insulating material comprising a novel ethylene (co) polymer and a composition of the same with another polyolefin and having a high volume resistance and excellent electric properties, and a high-voltage electric power using the same. About the cable.

[0002]

2. Description of the Related Art Hitherto, high-pressure polyethylene and cross-linked polyethylene have been widely used as insulators for high-voltage power cables because of their excellent electrical properties. One of the problems with high-voltage power cables is power loss during high-voltage transmission, and reducing this is an important issue. One means of reducing the power loss can be achieved by increasing the high voltage characteristics of the insulating material, particularly the volume resistance. However, in an insulator for a power cable, the temperature near the inner conductor is high (about 90 ° C.) due to Joule heat due to current, whereas the temperature near the outer conductor is the temperature of the outside air (about 20 ° C.). In conventional polyethylene, the volume resistance decreases significantly with increasing temperature, so that the volume resistance near the inner conductor through which current flows decreases significantly, and an electric field concentrates near the interface between the outer conductor and the insulator, resulting in a dielectric breakdown value. Decrease. This phenomenon is a serious problem particularly in DC power cables. For this reason, a material having low temperature dependence of volume resistance is desired. The use of high-pressure polyethylene as a high-voltage cable insulator has the disadvantage that the melting point is low and the electrical properties at high temperatures are poor. On the other hand, the conventional low-pressure polyethylene having a high melting point also has the drawback that the influence of the catalyst residue has no excellent electrical properties and the flexibility is poor. In order to improve the electrical properties of low-pressure polyethylene, a method has been proposed in which maleic anhydride is grafted to improve the properties (for example, Japanese Patent Application Laid-Open No. 2-10610). It doesn't work. Furthermore, low-density polyethylene having a density of 0.92 g / cm ³ and density of 0.
An insulator (JP-A-5-266723) is disclosed in which a linear low-density polyethylene of 91 to less than 0.94 g / cm ^{3 is} blended in an amount of 0.5 to 20 parts by weight. However, the above composition is still not sufficiently satisfactory because of the large temperature dependence of the volume resistance near the internal conductor.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an insulating material composed of an ethylene (co) polymer alone or a composition of the same with another polyolefin, which has a high volume resistance and a small temperature dependence of the volume resistance. is there.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies in view of the above-mentioned object, and as a result, have found that an ethylene (co) polymer which is polymerized by a specific catalyst and has 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 a catalyst containing at least one transition metal compound belonging to Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, in the presence of ethylene or ethylene and carbon atoms. (A) Ethylene which satisfies the following (A) to (D) and has an electric activation energy of 0.4 eV or less, which is obtained by (co) polymerizing 3 to 20 α-olefins, (2) An electric 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, characterized in that it contains said (a) ethylene (co) polymer and (b) other polyolefin up to 98% by weight.

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

According to a fourth aspect of the present invention, there is provided a power cable using an 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. In addition, the electrically insulating material referred to in the present invention includes those obtained by cross-linking the resin.

Hereinafter, the present invention will be described in detail. The ethylene (co) polymer in the present invention is prepared in the presence of a catalyst containing a transition metal compound belonging to Group IV of the periodic table containing a ligand having a cyclopentanyl skeleton and, if necessary, a cocatalyst, an organoaluminum compound and a carrier. And ethylene or ethylene and an α-olefin having 3 to 20 carbon atoms. Further, a catalyst obtained by prepolymerizing ethylene and / or the α-olefin in advance on the catalyst may be used as the catalyst. The α-olefin has 3 to 20, preferably 3 to 12 carbon atoms.
And specifically, propylene, butene-1, 4
-Methylpentene-1, hexene-1, octene-1,
Decene-1, dodecene-1 and the like. It is desirable that the content of these α-olefins is selected usually in the range of 30 mol% or less, preferably in the range of 0.5 to 25 mol%.

The cyclopentadienyl skeleton of the 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, And 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 combine with 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 an isopropyl group. 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 include -n-propylmethylethylcyclopentadienyl group. As the substituted cyclopentadienyl group of the present invention, among these, a cyclopentadienyl group substituted by an alkyl group having 3 or more carbon atoms is preferable,
Particularly, a 1,3-substituted cyclopentadienyl group is preferred.
When the substituents, that is, the hydrocarbons are bonded to each other to form one or more rings, the substituted cyclopentadienyl group includes an indenyl group, a hydrocarbon group having 1 to 8 carbon atoms (such as an alkyl group), and the like. A substituted indenyl group, a naphthyl group, a substituted naphthyl group substituted with a substituent such as a C1-C8 hydrocarbon group (such as an alkyl group), a C1-C8 hydrocarbon group ( Preferred examples thereof include a substituted fluorenyl group substituted by a substituent such as an alkyl group.

The transition metal of the transition metal compound belonging to Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton includes zirconium, titanium, hafnium and the like, with zirconium being particularly preferred. The transition metal compound generally has 1 to 3 ligands having a cyclopentadienyl skeleton, and when having 2 or more ligands, they may be bonded to each other by a crosslinking group. In addition, examples of such a crosslinking group include an alkylene group having 1 to 4 carbon atoms, an alkylsilanediyl group, and a silanediyl group.

As the ligands other than the ligands having a cyclopentadienyl skeleton in the transition metal compounds belonging to Group IV of the periodic table, typical ligands include hydrogen and C1 to C2.
0 hydrocarbon group (alkyl group, alkenyl group, aryl group, alkylaryl group, aralkyl group, polyenyl group, etc.), halogen, methalkyl group, metaaryl group and the like.

The following are specific examples of these. 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. As the monoalkyl metallocene, 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.

Examples of the substituted bis (cyclopentadienyl) titanium compound include 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 Or, as the carbon-linked cyclopentadiene complex, dimethylsilyldicyclopentadienyltitanium diphenyl or dichloride, methylenedicyclopentadienyl Data iodonium diphenyl or dichloride, and other dihalide complexes.

Examples of the zirconocene compound include 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, and haloalkyl or dihalide thereof. Examples of the complex, dialkyl, trialkyl, tetraalkyl or pentaalkylcyclopentadiene include bis (pentamethylcyclopentadienyl) zirconium dimethyl, bis (1,2-dimethylcyclopentadienyl) zirconium dimethyl, and dihalide complexes thereof, silicon Examples of the carbon-linked cyclopentadiene complex include dimethylsilyldicyclopentadienylzirconium dimethyl or dihalide, methylenedicyclopentene. Dienyl zirconium dimethyl or dihalide, such as methylene dicyclopentadienyl zirconium dimethyl or dihalide, and the like.

Still other metallocenes include bis (cyclopentadienyl) hafnium dichloride, bis (cyclopentadienyl) hafnium dimethyl, bis (cyclopentadienyl) vanadium dichloride and the like.

Examples of other transition metal compounds belonging to Group IV of the periodic table of the present invention include a ligand having a cyclopentadienyl skeleton represented by the following general formula (1) and other ligands and transitions: Also included are those in which a metal atom forms a ring.

[0020]

(Equation 1)

In the formula, CP is a ligand having the above-mentioned cyclopentadienyl skeleton, X is hydrogen, halogen, and C 1 -C 2.
0 represents an alkyl group, an arylsilyl group, an aryloxy group, an alkoxy group, an amide group, a silyloxy group or the like, and Y represents -O-, -S-, -NR-, -PR- or O
Z is a divalent neutral ligand selected from the group consisting of R, SR, NR ₂ , and PR ₂ , and Z is SiR ₂ , CR ₂ , SiR ₂ SiR
₂ , CR ₂ CR ₂ , CR = CR, SiR ₂ CR ₂ , BR
_{And 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.

Examples of the compound represented by Formula 1 include (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 it can balance ionic charges in a catalytically activated state. A thing. 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, aluminoxanes are most preferred.

The catalyst may be used by being supported 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
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
Those with ₂ and composed mainly of at least one component selected from the group consisting of Al ₂ O ₃ is preferred.

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 process for producing the ethylene (co) polymer (a) of the present invention is carried out 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. Is 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,
The polymerization pressure is more preferably 50 to 110 ° C., and 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-to-medium pressure method, and is usually 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. it is in the range of .90~0.94g / cm ^3. When the density is less than 0.86 g / cm ³ , the heat resistance is poor, and the volume resistance in a high temperature region is not improved. When the density exceeds 0.97 g / cm ³ , the flexibility is not sufficient.

The ethylene (co) polymer (B) of the present invention has an MFR of (B) 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 within the range. If the MFR is less than 0.01 g / 10 min, the moldability is poor, and if it exceeds 100 g / 10 min, the mechanical strength is reduced.

The method of calculating the molecular weight distribution (Mw / Mn) of the (C) ethylene (co) polymer of the present invention is as follows. The weight average molecular weight (Mw) and the number average molecular weight (Mw) are determined by gel permeation chromatography (GPC). Mn) and the ratio Mw / Mn. 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 formability is poor, and if it exceeds 5.0, the impact resistance is poor.

The (A) ethylene (co) polymer obtained by the catalyst of the present invention has a (D) composition distribution parameter Cb of 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 stabilizer is added to the sample, and the sample is heated and dissolved in orthodichlorobenzene (ODCB) at 135 ° C. so that the sample concentration becomes 0.2% by weight. The heated solution is transferred to a column filled with diatomaceous earth (Celite 545), filled and cooled to 25 ° C. at a rate of 0.1 ° C./min, and the sample is deposited on the celite surface. 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 such a method, the degree of branching 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.

[0034] The weight fraction wi of each fraction to the next, the change amount of the branching degree b _i per the elution temperature 5 ° C. (b
_i− b _i−1 ) to determine the relative concentration ci, and plot the relative concentration against the degree of branching 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 proposals have been made for a method of describing the composition distribution of the ethylene / α-olefin copolymer. 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 approximation calculation accuracy is lowered when the number of branches and cumulative weight fraction of the sample deviate from the logarithmic normal distribution, correlation coefficient R ₂ to perform measurements on commercially available LLDPE is fairly low, the accuracy of the values 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. If it exceeds 0.4 eV, the temperature dependence of the volume resistance is large.

The activation energy is one of the constants included in the Arrhenius equation representing the temperature change of the rate constant in the course of the transport phenomenon. The activation energy is the transition energy from the original system to the production system through the transition state. It corresponds to the energy difference between the state and the original state. In particular, the electrical activation energy is used in the Arrhenius equation showing the temperature dependence of current. Here, a small activation energy indicates that the temperature dependence of the current is small. The method for measuring the 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 equation, when measuring the volume resistance at room temperature (20 ° C.) and 90 ° C. Can be obtained by substituting the current value at. The method of measuring the volume resistance will be described later.

The (b) other polyolefin in the present invention means a homo- or copolymer of a hydrocarbon 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 (ii) other polyolefins include high / medium density polyethylene, linear low density polyethylene, ultra low density polyethylene, polypropylene, polybutene, poly-4-methyl-1-pentene, ethylene / α-
Olefin copolymer rubber, ethylene-propylene copolymer rubber (EPR), high pressure radical method low density polyethylene, high pressure radical method ethylene copolymer, and the like. Among the above-mentioned polyolefins, high-pressure radical-process low-density polyethylene is particularly preferable because of its excellent electrical properties, processability and flexibility.

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

The blending amount of the above (b) other polyolefin with respect to the (a) ethylene (co) polymer is from 0 to 98% by weight. (A) When it is desired to maintain the excellent electrical properties of the ethylene (co) polymer, the content of (A) is 100 to 70% by weight. (B) When it is desired to make use of the processability and economic efficiency of other polyolefins, it is desirable to mix (a) at 70 to 2% by weight.

When used after crosslinking as described below,
(A) 30 to 10% by weight of ethylene (co) polymer, (b)
It is desirable to mix 70 to 90% by weight of another polyolefin.

In the present invention, when the composition is used as an electric insulating material, the composition may be used as it is, but it is desirable to crosslink the composition in order to further improve heat resistance. The method of crosslinking is not particularly limited, and examples thereof include a method using a radical generator such as an organic peroxide, a method using electron beam crosslinking, and a method using silane crosslinking, but are economically inexpensive. Therefore, a method using a radical generator such as an organic peroxide is preferable.

Examples of the radical generator used include benzoyl peroxide, lauryl peroxide, dicumyl peroxide, t-butylhydroxy peroxide, α, α-bis (t-butylperoxydiisopropyl) benzene, and di-t-butyl. Peroxide, 2,5
-Di-methyl-2,5-di- (t-butylperoxy)
Hexine, peroxides such as 2,5-di-methyl-2,5-di- (t-butylperoxy) hexane, azobisisobutyronitrile, and 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 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-butylperoxy) hexane, dicumyl peroxide and the like are preferably used. The compounding amount is 0.01 to 5 parts by weight, preferably 0.1 to 5 parts by weight based on 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, the insulating material of a capacitor, the insulation of a high voltage portion such as an X-ray generator, various measuring equipment, a container for a dry battery and a wet battery can be used. Insulation, various printed boards,
It is used as an insulator for various connectors, power distribution coats, gloves for working with high voltage currents and jigs and tools.

The power cable of the present invention comprises an insulating layer which is preferably crosslinked using the resin composition. A specific example of the power cable is a power cable in which a conductor is covered with at least a crosslinked electric insulating material of the present invention to constitute an insulating layer. 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 preferred that the power cable be crosslinked at the time of coating. The radical generator may be blended in advance and crosslinked by heating, or crosslinked using radiation or the like.

The cooling after the molding is optional, such as natural cooling or cooling in a water tank. However, it is preferable to cool the molding relatively slowly for the purpose of preventing the occurrence of voids (voids) inside.

The crosslinked resin composition for an insulating material of the present invention is excellent in insulating properties and has elasticity, so that it is most suitable for covering electric wires. However, it is not limited to a DC / AC power supply and can be used widely. However, it has a small temperature dependency of volume resistance and has excellent electrical characteristics, and can be suitably used particularly as a power cable for high-voltage DC.

[0053]

The present invention will be described in more detail with reference to the following examples, which, however, are not intended to restrict the scope of the present invention.

(Preparation of Sample for Volume Resistance Measurement) 1. Preparation of Sample for Volume Resistance Measurement The blend of an ethylene (co) polymer and a polyolefin to be measured was kneaded with a plast mill at 160 ° C. for 5 minutes.
It was formed into a sheet having a thickness of 0.3 mm by hot pressing. The hot pressing conditions were as follows: The uncrosslinked sample was molded under the following conditions with the sample sandwiched between aluminum sheets. 1) Preheat the sample at 140 ° C for 5 minutes 2) Press at 140 ° C for 5 minutes at 100 kg / cm ² 3) Cool under pressure from 140 ° C to 30 ° C for 5 minutes A sample in which 2 parts by weight of the oxide was kneaded was sandwiched between Teflon sheets and molded under the following conditions. 1) Preheat the sample at 120 ° C for 5 minutes 2) Press at 120 ° C, 100 kg / cm ² for 5 minutes 3) Cool under pressure from 120 ° C to 30 ° C for 5 minutes, excluding samples containing voids at this time 4) Preheating again at 120 ° C for 5 minutes 5) Pressing at 120 ° C, 100 kg / cm ² for 5 minutes 6) Heating from 120 ° C to 160 ° C under pressure 7) Cross-linking at 160 ° C under pressure for 30 minutes 8) Cooled under pressure from 120 ° C to 30 ° C in 5 minutes.
C. for 5 minutes. It was formed into a sheet having a thickness of 0.3 mm by hot pressing.

(Volume Resistance Measurement) FIGS. 1A and 1B
The electrode system shown in FIG. FIG. 1A is a plan view, and FIG.
(B) shows a side view thereof, and numeral 11 in the figure.
Is a main electrode (50 mmφ), 12 is a guard electrode (inner diameter 75 mm).
mmφ, outer diameter 80 mmφ), 13 is a sample, 14 is a high voltage electrode (80 mmφ), the main electrode is connected to a vibration capacitance type ammeter, and the 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 by a buff polisher to a mirror surface. In the measurement, the sample was placed on the electrode system as shown in FIGS. 1 (a) and 1 (b), and the upper and lower electrodes were short-circuited for 5 minutes to remove the electric charge charged on the sample surface. The test was performed under a nitrogen atmosphere. In addition, what was measured at 90 ° C. was short-circuited for 7 minutes so that the temperature in the sample was uniformly 90 ° C. The applied voltage is 3300 V DC by a battery. As a measuring device, a vibration capacitance type ammeter (TR8411 manufactured by Advantest) was used. 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 the sample was about 0.3 mm, and each sample was measured up to two decimal places and used. The effective electrode area is 19.6 cm ² . From the investigation of the current-time characteristics, it was found that after the voltage application, the current did not decrease due to the absorption current, and the current could be measured stably after 10 minutes. Therefore, the current value after 10 minutes of voltage application is used as a measured value. If the current is not stable even after 10 minutes, wait for about 2 minutes to stabilize. 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.

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

(Polymerization of Sample A1) (1) Preparation of Catalyst 150 ml of purified toluene was added to a 500 ml eggplant type flask equipped with an electromagnetic induction stirrer under nitrogen, and then a toluene solution of bisindenylzirconium dimethyl (concentration: 1 mmol) was added.
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 (Fuji Devison, grade # 952, surface area 300) previously calcined at 600 ° C. for 5 hours in a 1.5-liter three-necked flask equipped with a stirrer under nitrogen.
After adding 50 g of (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 A continuous fluidized-bed gas-phase polymerization apparatus was used.
Ethylene and butene-1 at 20 ° C and a total pressure of 20 kgf / cm ² G
Was copolymerized. The gas composition in the system was a butene-1 / ethylene molar ratio of 0.08 and an ethylene concentration of 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 150 ml of purified toluene was added to a 500 ml eggplant type flask equipped with an electromagnetic induction stirrer under nitrogen, and then a toluene solution of bisindenyl zirconium dichloride (concentration: 1 m) was added.
(mol / ml) and 180 ml of a toluene solution of methylalumoxane (concentration: 1 mmol / ml) were added and reacted at room temperature for 1 hour. Then, with a stirrer under nitrogen 1.5
l Silica previously calcined in a three-necked flask at 600 ° C. for 5 hours (Fuji Devison, grade # 952, surface area 30
(0 m ² / g), and the whole amount of the solution was added, followed by stirring 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 method using a linear low-density polyethylene tetrachloride using a Ziegler catalyst and a triethylaluminum catalyst.
It was obtained by copolymerizing ethylene and 1-butene. Density 0.92
3 g / cm ³ , MFR 3.0 g / 10 min (B2) is a low-density polyethylene produced by a high-pressure radical polymerization method (trade name: Nippon Petrochemical Co., Ltd. Nisseki Lexlon W200)
0 Density 0.919 g / cm ³ , MFR 1.0 / 10 m
in. Table 1 shows the physical properties of the samples.

[Examples 1 and 2 and Comparative Examples 1 and 2] Table 2 compares the volume resistance and the activation energy of the uncrosslinked sample. 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 Ziegler catalyst are shown in Table 2.
High activation energy, high temperature dependence, especially 90
Low volume resistance at ℃.

Comparative Example 2 Table 2 shows the measured values of low-density polyethylene (B2) by a high-pressure radical polymerization method. Low volume resistance, high activation energy and high temperature dependence.

Examples 3 to 10 Table 3 shows the results obtained by mixing the sample (A1) with the sample (B2) and measuring the volume resistance without crosslinking. In addition, Example 1 and Comparative Example 2 were compared.

Example 11 In Example 11 of Table 4, the volume resistance of a sample obtained by mixing 90% by weight of the sample (B2) with 10% by weight of the sample (A2) was measured.

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

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

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

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

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[Table 1]

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[Table 2]

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[Table 3]

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[Table 4]

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[Table 5]

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According to the present invention, the electrical insulating material mainly composed of an ethylene (co) polymer polymerized with the specific catalyst of the present invention has a large volume resistance and a small temperature dependency, and further has flexibility and workability. It is a material having excellent electrical characteristics even after crosslinking, and is suitable as an electrical insulating material. Furthermore, when used as an insulating layer of a power cable, power loss during high-voltage power transmission can be reduced without increasing the thickness of the insulating layer.

[Brief description of the drawings]

Fig. 1 Volume resistance measuring device

FIG. 2 is a graph of an example and a comparative example shown in Table 3.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C08F 10/02 C08F 110/02 C08F 210/02 C08L 23/04-23/08 C08L 23/16 EUROPAT (QUESTEL )

Claims (5)

(57) [Claims] 1. A method comprising the steps of: (a) providing a catalyst containing at least one transition metal compound belonging to Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton; It comprises a resin obtained by copolymerizing an olefin, which satisfies the following (A) to (D) and has an electric activation energy of 0.4 eV or less: (a) an ethylene (co) polymer-containing resin. 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 up to 98% by weight of said (a) ethylene (co) polymer and (b) another polyolefin. 3. The electrical insulating material according to claim 1, wherein the (b) other polyolefin is polyethylene produced by a high-pressure radical polymerization method. 4. A power cable using an electric 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.