JPS61206110A - Insulating material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an electrical insulating material having excellent breakdown strength against impact voltage.

(B) Prior Art Various plastic materials have been used as electrical insulating materials for electrical cables and the like. In particular, olefin polymers have excellent properties such as electrical properties, mechanical properties, and chemical stability. Among them, low-density polyethylene produced by high-pressure radical polymerization is inexpensive, has low dielectric loss, has good processability, and can be crosslinked to greatly improve its heat resistance. It is widely used for electric wires and cables because it has many advantages such as less concern about tree phenomenon due to contamination.

The current problem with insulating materials for power cables is that as the power transmission voltage rises due to the expected future increase in power transmission capacity, the thickness of the insulator must be increased to match the increased voltage. It is. That is, with current materials such as polyethylene, dielectric breakdown will occur if the insulating layer is not made very thick in response to high voltages.

Various improvement methods have been proposed to address this problem.

For example, several methods have been proposed in which styrene is graft-polymerized to polyethylene in order to improve the breakdown strength against impact voltage, especially in a high temperature range. Special Public Service 1977-18
One such method is disclosed in Japanese Patent No. 760, but this method has the problem that crosslinking of polyethylene is unavoidable and the in-glue strength in the low temperature range is reduced. JP-A-57-'80605 proposes a method of impregnating and polymerizing ethylene polymer particles with an aromatic vinyl monomer in an aqueous suspension; have

Also, a method of blending aromatic polymers such as polystyrene with polyethylene or olefin polymers (Japanese Patent Publication No. 38-20
No. 717, JP-A-50-142651, JP-A-52-
No. 54187) has been proposed, but it has the drawback of poor compatibility between polyethylene or olefin polymers and styrene polymers.

A method of blending a block copolymer of styrene and conjugated dienes with polyethylene has also been proposed (Japanese Patent Application Laid-open No. 52-41884), but this method results in a decrease in heat resistance and extrusion processability.

Other methods include impregnating polyethylene with electrical insulating oil (
% Kaiun No. 49-33938) has been proposed, but
This method has the disadvantage that the insulated electrical insulating oil bleeds out when used for a long time or due to changes in the environment, impairing its effectiveness.

(c) Problems to be Solved by the Invention As a result of intensive studies to solve the above-mentioned problems, the present invention does not have the drawbacks of the prior art as described above, and has an electric It provides an insulating material.

(2) Means for Solving the Problem The gist of the present invention is to provide compounds selected from 2-3 aromatic compounds having one carbon-carbon double bond in one molecule (excluding compounds a to e below). ethylene or a mixture of ethylene and other monomers in the presence of at least one monomer at a polymerization pressure of 500-4000 Kr/>2 and a polymerization temperature of 50-4000 Kr/>2.
A polymer component obtained by high-pressure lasocal polymerization under conditions of 400°C contains 0 units derived from the aromatic compound.
．． An electrical insulating material made of an ethylene polymer characterized by containing 0.005 to 1 mol.

H One carbon-carbon double bond and two benzene rings in one molecule
Various kinds of aromatic compounds having ~3 can be preferably used. Representative compounds are illustrated below, but the present invention is not limited thereto.

First, mention may be made of olefins having a fused or non-fused two-ring aromatic ring.

These olefins include cyclic olefin derivatives such as cyclotetraentene and cyclohexene, and chain olefin derivatives. For example, such olefins include compounds represented by the following general formulas (1) to IV). There is.

General formula General formula (elementary atom or alkyl group - General formula % formula % (3) R in the above formula (1), alkenylene group or cycloalkenylene group c, ethylene, propylene, butene, isobutyne, pentene, Methylpentene, hexene,
It is a divalent substituent obtained by removing two hydrogen atoms from cyclopentene, cyclohexene, or alkylcyclohexeno, and the alkyl groups Rz and R3 are methyl,
These include ethyl, propyl, inglovir, n-butyl, isobutyl, 5ec-butyl, tert-butyl and amyl groups.

Specific compounds of formula (1) include stilbene, 4-
'frustilbene, 1.2-cyphenylgrope 7.1.
3-diphenylzolo-4, 1,4-diphenylbutene-
1,1,4-diphenylbutene-2,1,1-diphenylketone-1.2,3-diphenylpropene, 1.2-
diphenylbutene-2,1,3-diphenylbutene-1
,2,4-nophenyl-4-methyl-1,1,
Examples include 2-diphenylcyclohexene and phenylpennorcyclohexene.

These can be produced by acid-catalyzed dimerization or co-dimerization of styrene or styrenes such as α-methylstyrene and vinyltoluene.

1.2-diphenylethylene sodium chloride can be obtained by reacting benzaldehyde with benzylmagnesium bromide and dehydrated. The same can be said of 1.2-diphenylpropene. Further, 1,1-diphenylethylene can be obtained by reacting diphenyl ketone with a Grignard reagent such as methylmagnesium iodide and dehydrating it.

R4 in the compound of formula (■) is an alkenyl group or cycloalkenyl group such as vinyl, zorobenyl, inglonylated, allyl, butenyl, cyfuroy/tenyl, cyclohexenyl, and R5 is a chain saturated aliphatic hydrocarbon or It is a divalent straight radical obtained by removing two hydrogen atoms from a saturated alicyclic hydrocarbon such as cyclointane, cyclohexane, and cycloheptane. Further, R2 and R3, which are alkyl groups, are the same as R2 and R3 in formula (1).

Specific compounds of the formula (10 include ■-phenyl-1
-(4-vinylphenyl)ethane, 1-(4-methylphenyl-1-(4-vinylphenyl)ethane, l-phenyl-1-(4-1sopronylphenyl)ethane, phenyl-(4-vinyl) phenyl)methane, phenyl-(
cyclohexenylphenyl)methane, etc.

These can be synthesized by various synthetic chemical methods.
Phenyl-(vinylphenyl)ethane etc. are produced by reacting nophenylethane with acetyl chloride using a Friedel-Krach catalyst to produce phenyl-(acetylphenyl).
It is obtained by first obtaining ethane, reducing it with sodium borohydride, etc., and then dehydrating it. Phenyl-(isopropenylphenyl)ethane can be obtained by reacting phenyl-(formylphenyl)ethane with a Niyard reagent such as methylmagnesium iodide, followed by dehydration.

Furthermore, R4, which is an alkenyl group or a cycloalkenyl group in formula (Ill), is the same as R2 in formula (n), and R2 and R3, which are alkyl groups, are also the same as R2 and R3 in formula (II). be.

Specific compounds of this formula (III) include 2-isoglonylbiphenyl, 4-isoglonylbiphenyl,
2-improbenyl-4'-ingrobilbiphenyl,
Examples include cyclohexenyl biphenyl and cyclopentenyl biphenyl. Among these, it can be obtained, for example, by dehydrogenation of inglobenylbiphenyl and inzolobylbiphenyl.

Furthermore, R4 as an alkenyl group or a cycloalkenyl group in formula (cup) is also the same as R4 in formula (ff), and R2 and R3 as an alkyl group are also the same as R2 and R3 in formula (■). be.

Specific compounds of formula (IV) include α-vinylnaphthalene, inzorobenylnaphthalene, allylnaphthalene, and l-cyclobent-2-enylnaphthalene. Among these, for example, vinylnaphthalene can be obtained by reacting formylnaphthalene with a Grignard reagent such as methylmagnesium iodide and then dehydrating it.

Examples of other two-ring aromatic olefins include arylindenes, aralkylindenes, and acenaphthylenes.

As an example of 3-ring aromatic olefin/, the following general formula (V) ~
(Some examples include those shown as powder.

Specific examples of compounds represented by the general formula (V) include:
1-vinyl anthracene/, 2-viny anthracene, 9
-vinyl anthracene, 2-inzorobenylanthracene, 9-f lobenyl to -f ropylanthracene, and the like.

As an example of a specific compound represented by the general formula (to), H1
2-vinylphenanthrene, 3-17-globinylphenanthrene, 3-vinylphenanthrene,
9-Vinylphenanthrenate is very effective.

Specific examples of compounds represented by general formula (4) include 1-phenyl-2-(1-naphthyl)ethylene, 1-phenyl-2-(2-1-phthyl)ethylene, 1- Phenyl-1-(1-naphthyl)ethylene, 1-phenyl-1
-(2-naphthyl)ethylene, l-phenyl-1-(1
-naphthyl) cloyne, 1-phenyl-1-(2-naphthyl)floine, I-phenyl-2-(2-naphthyl)
Examples include cloine, 1-(1-su7tyl)-2-0-tolylethylene, and the like.

General formula Examples of specific compounds represented by the above general formula (b) and Ll
-j, 2-phenylstilbene, 4-phenylstilbene, ■-phenyl-1-biphenylethylene, 4-benzylstilbene, 1-biphenyl-4-yl-1-p-
Tolylethylene, ■-bia x = 4- (2-phenylzorobey, 1-7x = 2- (4-hentsulfenyl)flopen, 1-phenyl-1-(pennorphenyl)ethylene, 1-tolyl -1-(pennorphenyl)ethylene, l-phenyl-1-(phenylethyl-
phenyl) ethylene, etc.

General Formula Specific examples of compounds represented by the above general formula ((a) include 1,1.2-triphenylethylene, 1,1.
2-) IJ phenylpropylene % Ll, 3-toI
J 7 x = nylbutene 1. l-diphenyl-2-o-
Tolylethylene, 1,1-nophenyl-2-p-1
-IJ-ruethylene and 3,3.3- )riphenylnoropene-1.

The above-mentioned compounds are exemplified as those that can be used in the production of the electrically insulating material of the present invention, and the present invention is not limited thereto.

These aromatic olefins can be synthesized by various synthetic chemical methods,
For example, it can be obtained by producing alcohol using the Grignard reaction and dehydrating it.

Example id', l-phenyl-1-su7thylethylene is
It is obtained by reacting the Grignard reagent from bromonaphthalene with acetophenone and dehydrating the obtained 1-phenyl-1-naphthylethanol. Furthermore, vinyl anthracene can be obtained by reacting Grignard from bromo anthracene with acetaldehyde and dehydrating the obtained hydroxyethyl anthracene.

Furthermore, the above-mentioned aromatic olefins can also be produced by dehydrogenating aromatic hydrocarbons that are saturated, ie, do not have ethylenic double bonds.

That is, as a method using a dehydrogenation reaction, it is possible to produce a saturated aromatic hydrocarbon having three or more fused or non-fused aromatic rings by dehydrogenating it using an appropriate dehydrogenation catalyst. can.

Note that diolefin can also be produced from monoolefin. During dehydrogenation, side reactions such as polymerization are suppressed, but if an aromatic hydrocarbon having three fused or non-fused aromatic rings is produced, side reactions such as decomposition reactions may occur. .

The dehydrogenation catalyst is not particularly limited and any catalyst can be used. For example, Or, Fe, Cu, K, M
Examples include one or a mixture of two or more metal oxides such as G, Ca, etc., noble metals such as Pt and Pd, and dehydrogenation catalysts in which these metal oxides or noble metals are supported on a carrier such as alumina.

The temperature of the dehydrogenation reaction is 350 to 650°C, preferably 400 to 600°C. LHi9V is 0.2~l
O1 is preferably 0.5 to 3.0. Further, during dehydrogenation, a gas such as water vapor, nitrogen, or hydrogen may be present in order to lower the partial pressure or to prevent carbon precipitation. Further, an appropriate diluent can be used as necessary. However, it is usually advantageous if the dehydrogenation rate is not increased so much because the raw material itself can act as a diluent.

By the above dehydrogenation, vinyl anthracene is produced from ethyl anthracene, phenylnaphthyl ethylene is produced from phenylnaphthylethane, and U-phenylstilbene is produced from phenyl biphenylylethane.

In addition to the above examples, examples of the three-ring aromatic olefin include noarylindenes, dialkylindenes, and terphenyls. .

Derivatives of the above-mentioned 2- to 3-ring aromatic olefins include chlorine, bromine, etc. Examples include oxygen-containing derivatives having a sulfur atom, and derivatives having a sulfur atom and a nitrogen atom.

In addition to the aromatic olefins/and derivatives thereof of the above formulas (1) to (1), unsaturated caldenyl compounds such as acrylic, methacrylic, maleic acid, and fumaric acid, or double bonds such as vinyl ester, etc. One group having 2- to 3-substituted aromatic ring units such as biphenyl, naphthalene, diarylalkane, triarylalkane, triarylsialkane, anthracene, phenanthrene/, arylnaphthalene/, aralkylnaphthalene, terphenyl, or these Aromatic compounds with attached derivatives can also be used.

All of the above-mentioned aromatic compounds have structural features that can be included as polymer components in the polymer chain produced by high-pressure lasocal polymerization of ethylene or a mixture with other monomers containing ethylene as the main component. have.

Note that the compounds (a) to (8) above are excluded from the various compounds described above. The inventor first developed the front 6 pins (a) to (e).
Patent application 1982-2 regarding ethylene polymer using the compound and electrical insulating material made from the ethylene polymer
No. 07595-207598, No. 217924, No. 2
Although applications have been filed as Nos. 33950 to 233951,
In addition to these specific compounds (-) to (θ), the present invention was completed by discovering aromatic compounds that can improve dielectric strength.

Polyethylene, which has traditionally been widely used as an insulating material for power cables, etc., decreases in its breakdown strength against impact voltage (innosolus breakdown strength) when its degree of crystallinity decreases, and deteriorates workability when its degree of crystallinity increases. It has some drawbacks.

It is generally said that when other components are introduced into the polyethylene chain, the degree of crystallinity decreases due to steric hindrance. However, the present inventors have discovered that when a specific ratio of units derived from a specific aromatic compound is contained in a polymer chain, there is a range in which the in-solution fracture strength increases even if the degree of crystallinity decreases. I found something to do. The present invention is based on the unexpected finding that by introducing a very small amount of aromatic units into an ethylene polymer, it is possible to achieve an improvement in in-solution fracture strength. This improvement effect is observed in a wide temperature range from low to high temperatures.
This is particularly noticeable in high temperature ranges.

In the ethylene polymer of the present invention, the content of units derived from the above-mentioned aromatic compound to be included as a polymer component is 0.
005 to 1.0 mol, preferably ido, 01 to
It is 0.7 molti. When the amount is less than 0.005 mol%, almost no improvement effect is observed, and when the amount exceeds 1.0 mol%, the innosol fracture strength is only lower than when it does not contain units derived from the aromatic compound. However, it is uneconomical due to the large consumption of high-pressure radical polymerization initiators and the use of large amounts of expensive aromatic compounds, and the chain transfer reaction becomes intense, resulting in a decrease in the molecular weight of the ethylene polymer. This makes the polymer extremely unsuitable as an electrical insulating material.

The density of the ethylene polymer of the present invention is 0.890 to 0.890.
A range of 950 f/3 is preferred. In addition, the melt index (hereinafter abbreviated as M) is preferably 0.05 to
507/10 minutes, more preferably 0.1-2OS'/
It is in the range of 10 minutes.

The ethylene polymer of the present invention may contain other unsaturated monomers in addition to ethylene, and examples of the unsaturated monomers include zolopyrene, butene-1, pentene-1, hexene-1, Examples include 4-methyl 4-ten-1, octene-11-decene-1, d-vinyl acetate, ethyl acrylate, methacrylic acid or its ether, and mixtures thereof.

The content of unsaturated monomer in the above ethylene system 1 coalescence is O~
3 molti, especially 1 molti or less is preferred.

The ethylene polymer of the present invention can be used in combination with an ethylene polymer that does not contain other aromatic units. Compositions containing other ethylene polymers are also preferred embodiments of the present invention, and by having the aromatic unit content in the composition within the above range, the in-glass fracture strength of the composition is improved. Ru.

Other ethylene polymers to be blended with the ethylene polymer of the present invention include ethylene homopolymer, ethylene tochloride/, butene-1% nonten-1 hexene-1/4
- Copolymers with α-olefins having carbon Ij of 1.3 to 12, such as methyl 1-1, 1-octene, and 1-decene,
Ethylene and vinyl acetate, acrylic acid, ethyl acrylate, methacrylic acid, ethyl methacrylate, maleic acid,
Copolymers with polar group-containing monomers such as maleic anhydride,
Alternatively, the ethylene homopolymer or ethylene and α
- Polymers obtained by modifying an olefin copolymer with unsaturated cardan or its conductor such as acrylic acid or maleic acid, and mixtures thereof.

The ethylene polymer of the present invention is produced by a radical polymerization method under high pressure. That is, the radical polymerization method under high pressure is 9/c at a polymerization pressure of 500 to 4000.
rn2, preferably 1000-3500 Kq/cm2
, reaction temperature 50-400°C1 preferably 100-35
ethylene and aromatics, and optionally other monomers, simultaneously in a seed or tube reactor in the presence of a free radical catalyst and a chain transfer agent, if necessary auxiliaries, under conditions of 0'C; Alternatively, (refers to a method of contacting and polymerizing in stages. If the aromatic compound is solid, it is dissolved in a suitable solvent and supplied.

The free-radical catalysts include customary initiators such as dihydroxide, hydrochloride, azo compounds, amine oxide compounds, oxygen, and the like.

In addition, as a chain transfer agent, hydrogen, zolopyrene, butene-1
,01-02G or higher saturated aliphatic hydrocarbons and halogen-substituted hydrocarbons, such as methane, ethane,
Furonoyan, butane, isobutane, n-hexane, n-
Hezotan, cyclo i? Roughins, chloroform and carbon tetrachloride, C1-C20 or higher saturated aliphatic alcohols such as me1/-#, ethanol, pronognols and isozolo-gunols, C1-C20 or higher saturated aliphatic alcohols. ? Examples include acetone and methyl ethyl ketone, as well as other aromatic compounds such as side-lighting compounds such as toluene, noethylbenzene and xylene.

(E) Actions and Effects of the Invention The ethylene polymer of the present invention produced as described above or the ethylene polymer composition obtained by blending the ethylene polymer with another ethylene polymer can be used as an electrical insulating material. It has excellent dielectric strength and particularly excellent breakdown strength against impact voltage in the high temperature range, making it very useful as an insulating material for ultra-high voltage electrical cables.

Further, the present invention is very superior in that it can be produced by a relatively simple process of high-pressure radical polymerization, and does not require conventional complicated grafting and blending steps.

In the present invention, olefin polymers (including copolymers) other than the above-mentioned ethylene polymers, 4-reacrylonitrile, Polyamide, polycarbanate, ABSm(IIl&, polystyrene,
Polyphenylene oxide, polyvinyl alcohol-based resin, vinyl chloride-based resin, vinyl chloride/vinyl chloride resin, thermoplastic resin such as polyester resin, petroleum resin, coumaron-y f” y k4 Mk, ethylene-propylene copolymer comb (TJiP R, KPDM, etc.), 8B
It can be used in combination with at least one synthetic rubber or natural rubber such as R%NBR, butanoene rubber, AE R1 chloroprene rubber, isoprene rubber, and styrene-butadiene-styrene block copolymer.

On the other hand, in the present invention, organic/inorganic Ficy-1 antioxidants, lubricants, various organic/inorganic pigments, ultraviolet inhibitors, dispersants, copper damage inhibitors, neutralizing agents, blowing agents, plasticizers, Additives such as antifoaming agents, flame retardants, crosslinking agents, flowability improvers, weld strength improvers, nucleating agents, and the like may be added to the extent that they do not significantly impair the effects of the present invention.

Further, the ethylene polymer of the present invention or a composition containing the same may be used in an uncrosslinked state, or may be subjected to a crosslinking treatment if necessary.

A normal crosslinking method is applied to the crosslinking method.

(f) Example Examples are shown below.

Approximately 1.70 m
Of ethylene, the aromatic compound shown in Table 1, and a predetermined amount of n-hexane were charged, and di-tertiary-butyl peroxide as a polymerization initiator was added. Polymerization was carried out for various polymerization times to prepare various ethylene polymers containing units derived from aromatic compounds as shown in Table 1.

A part of the produced polymer was bath-dissolved in heated carbon tetrachloride, and reprecipitated by pouring it into multilevel acetone. This operation was repeated several times to purify and then vacuum dry.

Purified. j? IJ Mama - Thickness 500 by heat compression
/jm sheet, and the units derived from aromatic compounds in each produced polymer were determined by infrared spectroscopy using a compensation method using a sheet of ethylene polymer of the same thickness without aromatic compounds as a control. I did it regularly.

The amount of units derived from the aromatic compound contained in each produced polymer was determined mainly from the absorbance of the absorption attributed to the aromatic ring around 1600 cm-'.

In addition, the melt index of each produced polymer was measured by J
The test was conducted in accordance with Engineering SK-6760.

The impulse rupture strength of the valley-forming polymer was measured at 20°C and 60°C, and the results are shown in Table 1.

Incidentally, the impulse breaking strength was measured by the following method. The sample was made into a sheet with a thickness of micrometers by heat compression molding. A fixed electrode, a so-called Matskeon electrode (Fig. 1), was used as the electrode system. The electrode system substrate 4 is made of polymethyl methacrylate and has a hole with a diameter of 1/2 inch in its center. A 1/2 inch stainless steel bulb 1 was used as the electrode. Sample 2 was cut into about 8 to 10 squares and placed between the electrodes.

The space between the sample 2 and the electrode was filled with degassed resin 3 and cured. Immerse such a Matsukeon electrode in a container filled with silicone oil and heat it at 20°C and 8°C.
It was placed in a constant temperature bath at 0°C and measured. The voltage waveform used for destruction was a negative polarity, 1×40 μs in-force waveform. The waveform was observed with an oscilloscope, and the data that broke at the wave front was taken as data, and the average value of the points above was taken.

Comparative Examples 1 to 3 Ethylene polymers shown in Table 1 were prepared under the same polymerization conditions as in Example 1, and their in-glass fracture strengths were measured, and the results are shown in Table 1.

As is clear from Table 1 of the evaluation results, Examples 1 to 5 show that the ethylene polymer of the present invention is superior to the ethylene homopolymer (Comparative Example 1) in fracture resistance, especially in the high temperature range. It is.

On the other hand, in Comparative Examples 2 and 3, no improvement effect was observed when the aromatic content was entirely outside the specified range.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing a Mackeon electrode for impulse disruption testing according to the present invention. 1...Stainless steel bulb 2...Sample 3...Epoquin resin 11...Polymethyl methacrylate substrate patent applicant Japan Petrochemical Co., Ltd.

Claims (1)

[Claims] (1) 2~ having one carbon-carbon double bond in one molecule
It is a 3-ring aromatic compound and has the general formula (a) ▲Mathematical formulas, chemical formulas, tables, etc.▼ (b) ▲Mathematical formulas, chemical formulas, tables, etc.▼ (c) ▲Mathematical formulas, chemical formulas, tables, etc.▼ (d) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (e) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1 is an alkylene group with 1 or 2 carbon atoms,
R_2 and R_3 are hydrogen atom, chlorine atom, or carbon number 1-
4 straight-chain or branched alkyl group, R_4 and R_5 each represent a hydrogen atom or a methyl group] In the presence of at least one selected from the two- to three-ring aromatic compounds excluding the compounds shown in Ethylene or a mixture of ethylene and other monomers is polymerized at a polymerization pressure of 500~
It is characterized by containing 0.005 to 1 mol% of units derived from the aromatic compound as a polymer component obtained by high-pressure radical polymerization under conditions of 4000 Kg/cm^2 and a polymerization temperature of 50 to 400°C. An electrical insulating material made of ethylene polymer.