JPS6228816B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an insulating layer forming composition. More specifically, the present invention relates to a novel insulating layer forming composition containing a special polyolefin obtained by a specific method as a material for forming an insulating layer for power cables, electric wires, etc. Insulating layers for power cables, electric wires, and the like are generally obtained by extrusion molding a composition in which a crosslinking agent is blended with low-density polyethylene obtained by a high-pressure method. However, insulating layers molded using high-pressure polyethylene have insufficient heat resistance and are easily deformed by heating, so improvements have been desired. Furthermore, even better properties such as extrusion processability and electrical properties were required. As a result of intensive research, the present inventors have discovered that the above technical problems can be solved all at once by using a special polyolefin obtained by a specific method. That is, the present invention provides ethylene and α-carbon atoms having 3 to 12 carbon atoms in a gaseous state substantially free of solvent in the presence of a catalyst consisting of a solid substance containing magnesium, titanium, and/or vanadium, and an organoaluminium. The density obtained by copolymerizing olefin is 0.890~
The present invention relates to an insulating layer forming composition characterized by containing 100 parts by weight of an ethylene/α-olefin copolymer having a melt index of 0.945 and a melt index of 0.1 to 20 and 0.1 to 5 parts by weight of a crosslinking agent. The insulating layer obtained using the special polyolefin produced by the specific method of the present invention has a very high gel fraction, and therefore has a small thermal deformation rate at high temperatures and has significantly improved heat resistance. Furthermore, the impulse breakdown voltage of the cable is high, and the electrical tree resistance is also significantly improved. Further, the composition of the present invention has excellent advantages such as extremely good extrusion processability and excellent crosslinking speed. The special polyolefin in the present invention refers to ethylene and carbon atoms having 3 to 3 carbon atoms in the presence of a catalyst consisting of a solid substance containing magnesium, titanium, and/or vanadium, and an organoaluminum compound in a gas phase substantially free of solvent. It is obtained by copolymerizing 12 α-olefins, and its density is
It is an ethylene/α-olefin copolymer having a melt index of 0.890 to 0.945, preferably 0.910 to 0.940, and a melt index of 0.1 to 20, preferably 0.5 to 7. Below, ethylene used in the present invention and α-
A method for producing an olefin copolymer will be explained. The catalyst system used is a combination of a solid substance containing magnesium, titanium and/or vanadium, and an organoaluminium compound, such as magnesium metal, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, etc. Magnesium, etc., as well as double salts, double oxides, carbonates, chlorides, hydroxides, etc. containing magnesium atoms and metals selected from silicon, aluminum, and calcium. Examples include those in which a titanium compound and/or vanadium compound is supported by a known method on an inorganic solid carrier, such as one treated or reacted with a sulfur compound, an aromatic hydrocarbon, or a halogen-containing substance. Examples of the above oxygen-containing compounds include organic oxygen-containing compounds such as water, alcohol, phenol, ketone, aldehyde, carboxylic acid, ester, and acid amide, and inorganic oxygen-containing compounds such as metal alkoxides and metal oxychlorides. be able to. Examples of sulfur-containing compounds include organic sulfur-containing compounds such as thiols and thioethers, sulfur dioxide, sulfur trioxide,
Examples include inorganic sulfur compounds such as sulfuric acid. Examples of aromatic hydrocarbons include various monocyclic and polycyclic aromatic hydrocarbon compounds such as benzene, toluene, xylene, anthracene, and phenanthrene. Examples of the halogen-containing substance include compounds such as chlorine, hydrogen chloride, metal chlorides, and organic halides. Examples of the titanium compound and/or vanadium compound include halides, alkoxy halides, alkoxides, and halogenated oxides of titanium and/or vanadium. As the titanium compound, a tetravalent titanium compound and a trivalent titanium compound are suitable, and the tetravalent titanium compound specifically has the general formula Ti(OR) _o X _4-o
(Here, R represents an alkyl group, aryl group, or aralkyl group having 1 to 20 carbon atoms, and X represents a halogen atom. n is 0≦n≦4.) Titanium tetrachloride is preferable. , titanium tetrabromide,
Titanium tetraiodide, monomethoxytrichlorotitanium, dimethoxydichlorotitanium, trimethoxymonochlorotitanium, tetramethoxytitanium, monoethoxytrichlorotitanium, diethoxydichlorotitanium, triethoxymonochlorotitanium, tetraethoxytitanium, monoisopropoxytrichlorotitanium, diiso Propoxydichlorotitanium, triisopropoxymonochlorotitanium, tetraisopropoxytitanium, monobutoxytrichlorotitanium,
Examples include dibutoxydichlorotitanium, monobenxytrichlorotitanium, monophenoxytrichlorotitanium, diphenoxydichlorotitanium, triphenoxymonochlorotitanium, and tetraphenoxytitanium. Examples of trivalent titanium compounds include titanium trihalides obtained by reducing titanium tetrahalides such as titanium tetrachloride and titanium tetrabromide with hydrogen, aluminum, titanium, or organometallic compounds of group metals of the periodic table. It will be done. Also, the general formula Ti(OR _{) n}
<m<4. ) A trivalent titanium compound obtained by reducing a tetravalent alkoxy titanium halide represented by the following formula with an organometallic compound of a group metal of the periodic table is exemplified. Examples of vanadium compounds include tetravalent vanadium compounds such as vanadium tetrachloride, vanadium tetrabromide, and vanadium tetraiodide;
Examples include pentavalent vanadium compounds such as vanadium oxytrichloride and orthoalkylvanadate, and trivalent vanadium compounds such as vanadium trichloride and vanadium triethoxide. Among these titanium compounds and vanadium compounds, tetravalent titanium compounds are particularly preferred. Specific examples of these catalysts include, for example, MgO-RX-TiCl ₄ system (Japanese Patent Publication No. 51-3514),
Mg- _SiCl4 -ROH- _TiCl4 system
), MgCl ₂ −Al(OR) ₃ −TiCl ₄ system (Special Publication No. 51-
152, Special Publication No. 52-15111), MgCl ₂ −SiCl ₄ −
ROH-TiCl ₄ system (JP-A-49-106581), Mg
(OOCR) ₂ −Al(OR) ₃ −TiCl ₄ system (Special Publication 1977-
11710), Mg-POCl ₃ -TiCl ₄ system (Special Publication No. 1171-
No. 153), MgCl ₂ −AlOCl−TiCl ₄ system (Special Publication No. 154-
15316) (in the above formula,
An example of a preferable catalyst system is one in which R represents an organic residue and X represents a halogen atom) in combination with an organoaluminum compound. As an example of another catalyst system, a reaction product of an organomagnesium compound such as a so-called Grignard compound and a titanium compound and/or a vanadium compound is used as a solid substance, and an organoaluminum compound is combined with this. I can do it. Examples of organomagnesium compounds include organomagnesium compounds with the general formula RMgX, R ₂ Mg, RMg (OR) (where R is 1 carbon number).
~20 organic residues, X represents a halogen) and their ether complexes, and also these organomagnesium compounds can be further combined with other organometallic compounds such as organosodium, organolithium, organopotassium, organoboron, organocalium, Those modified by adding various compounds such as organic zinc can be used. Specific examples of these catalyst systems include, for example:
RMgX-TiCl ₄ series (Special Publication No. 50-39470), RMgX
-Phenol-TiCl ₄ system (Special Publication No. 12953/1983),
Examples include combinations of organic aluminum compounds with solid substances such as RMgX-halogenated phenol-TiCl ₄ system (Japanese Patent Publication No. 12954/1983). In these catalyst systems, a titanium compound and/or a vanadium compound can also be used as an adduct with an organic carboxylic acid ester, and after contacting the above-mentioned magnesium-containing inorganic compound solid support with an organic carboxylic acid ester. You can also use Moreover, there is no problem in using an organoaluminum compound as an adduct with an organic carboxylic acid ester. Furthermore, in all cases it is also possible to use catalyst systems prepared in the presence of organic carboxylic esters without any problems. As the organic carboxylic acid ester, various aliphatic, alicyclic, and aromatic carboxylic acid esters are used, and aromatic carboxylic acids having 7 to 12 carbon atoms are preferably used. Specific examples include alkyl esters of benzoic acid, anisic acid, toluic acid, such as methyl and ethyl. A specific example of an organoaluminum compound to be combined with the above solid substance is the general formula
R ₃ Al, R ₂ AlX, RAlX ₂ , R ₂ AlOR, RAl(OR)X
and an organoaluminum compound of R _{3 Al 2}
may be the same or different), and examples thereof include triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, and mixtures thereof. The amount of organoaluminum compound used is not particularly limited, but is usually 0.1 to 0.1 to the amount of transition metal compound.
1000 mole times can be used. In addition, by bringing the above catalyst system into contact with α-olefin and then using it in a gas phase polymerization reaction, the polymerization activity can be greatly improved and the operation can be made more stable than in the case of no treatment. . Various α-olefins can be used as the α-olefin used at this time, but α-olefins having 3 to 12 carbon atoms are preferable, and α-olefins having 3 to 8 carbon atoms are more preferable.
α-olefin is preferred. Examples of these α-olefins include propylene, butene-1, pentene-1, 4-methylpentene-1,
Examples include heptene-1, hexene-1, octene-1, decene-1, dodecene-1, and mixtures thereof. The temperature and time during contact between the catalyst system and the α-olefin can be selected within a wide range, for example 0 to 200°C, preferably 0 to 200°C.
Contact treatment can be carried out at 110°C for 1 minute to 24 hours. The amount of α-olefin to be brought into contact can be selected within a wide range, but it is usually 1 g to 1 g per 1 g of the solid substance.
50000g, preferably about 5g to 30000g of α-olefin, and 1g to 1g per 1g of the solid material.
It is desirable to react 500 g of alpha-olefin. At this time, the pressure at the time of contact can be arbitrarily selected, but it is usually desirable to contact under a pressure of -1 to 100 kg/cm ² ·G. During the α-olefin treatment, the entire amount of the organoaluminum compound used may be combined with the solid substance and then brought into contact with the α-olefin,
In addition, after combining a part of the organoaluminum compound used with the solid substance, it is possible to form a gaseous α
- The polymerization reaction may be carried out by contacting with the olefin and adding the remaining organoaluminum compound separately during gas phase polymerization. Further, when the catalyst system and the α-olefin are brought into contact, there is no problem even if hydrogen gas coexists, and there is no problem even if other inert gases such as nitrogen, argon, helium, etc. coexist. The special polyolefin in the present invention is produced by copolymerizing ethylene and α-olefin in the gas phase in the presence of a solid material containing magnesium and a titanium compound and/or a vanadium compound and a catalyst consisting of an organoaluminum compound. The essence is to use a copolymer having a predetermined melt index and density obtained by the above method, and the α-olefin used in the copolymerization reaction is
Those having 3 to 12 carbon atoms are used. Specifically, propylene, butene-1, pentene-1, 4-methylpentene-1, heptene-1, hexene-1,
Octene-1, decene-1, dodecene-1, etc. can be mentioned. The polymerization reaction is carried out in a gas phase substantially free of solvent. As the reactor used, known reactors such as a fluidized bed and a stirring tank can be used. The polymerization reaction temperature is usually 0 to 110°C, preferably
The temperature is 20 to 80°C, and the pressure is normal pressure to 70 kg/cm ² ·G, preferably 2 to 60 kg/cm ² ·G. Although the molecular weight can be controlled by adjusting the polymerization temperature, the molar ratio of the catalyst, the amount of comonomer, etc., it is effectively carried out by adding hydrogen to the polymerization system. Of course, a two-stage or more multi-stage polymerization reaction may be carried out using different polymerization conditions such as hydrogen concentration, comonomer concentration, and polymerization temperature. As described above, in the presence of a catalyst consisting of a solid substance containing magnesium, titanium and/or vanadium, and an organoaluminium, ethylene and α of 3 to 12 carbon atoms are produced in a gas phase substantially free of a solvent. - An insulating layer forming composition containing an ethylene/α-olefin copolymer obtained by copolymerizing olefin and having a density of 0.890 to 0.945 and a melt index of 0.1 to 20, and a crosslinking agent in an amount necessary for crosslinking. It is. That is, in the present invention, the characteristics of the crosslinked polyolefin insulating layer can be significantly improved by extrusion coating and crosslinking treatment on a conductor with a composition obtained by blending a crosslinking agent with the special polyolefin obtained as described above. was completely unexpected. If a polyolefin obtained by a method other than the method of the present invention is used, an insulating layer having excellent properties as in the present invention cannot be obtained. Polyolefins produced by methods other than those of the present invention include, for example, polyolefins obtained by high-pressure polyethylene or solution polymerization by medium- or low-pressure methods. Known crosslinking agents can be used in the present invention, and organic peroxides are preferred. Specific examples of these include dicumyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-dibutylperoxy-3,3,5-trimethylhexane, and 3,3-bis(t-butylperoxyisopropyl)benzene. -t
-butylperoxybutanecarboxylic acid n-butyl ester and the like. The insulating layer forming composition of the present invention is prepared by mixing the required amount of crosslinking agent with the special polyolefin of the present invention at a temperature below the decomposition temperature of the crosslinking agent. At this time, it goes without saying that it does not deviate from the scope of the present invention to appropriately incorporate other auxiliary agents such as anti-aging agents, cross-linking aids, scorch inhibitors, voltage stabilizers, fillers, etc., if necessary. . The proportion of the crosslinking agent used is usually 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the special polyolefin of the present invention. In addition, in the present invention, it is possible to appropriately blend polyolefins obtained by other methods with the special polyolefins obtained by the specific method of the present invention.
There is no problem as long as the properties of the special polyolefin of the present invention are not impaired. Examples of these other polyolefins include high-pressure polyethylene, ethylene/vinyl acetate copolymers, and polyolefins obtained by medium- or low-pressure solution polymerization or slurry polymerization. The blending ratio of these is preferably 100 parts by weight or less based on 100 parts by weight of the special polyolefin of the present invention. The insulating layer forming composition of the present invention thus obtained has extremely good extrusion processability, and the molded insulating layer not only has a high gel fraction and extremely low heat deformation rate, but also has excellent heat resistance. It has a high impulse breakdown voltage and extremely good electrical tree resistance. The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto. Example 1 1000 g of anhydrous magnesium chloride, 50 g of 1,2-dichloroethane, and 170 g of titanium tetrachloride were ball milled at room temperature in a nitrogen atmosphere for 16 hours to support the titanium compound on the carrier. 1g of this solid substance
Contains 40mg of titanium per serving. A stainless steel autoclave was used as the apparatus for gas phase polymerization, and a loop was formed with a blower, a flow control valve, and a dry cyclone for separating the produced polymer, and the temperature of the autoclave was controlled by flowing hot water through the jacket. The polymerization temperature was 80°C, the above solid substance was fed into the autoclave at a rate of 250 mg/hr, and triethylaluminum was fed at a rate of 50 m-mol/hr, and the composition of ethylene and butene-1 in the gas fed to the autoclave with a blower ( molar ratio) respectively
Ethylene and butene-1 were copolymerized while adjusting the pressure to be 90% and 10%, and adjusting the hydrogen pressure to be 19% of the total pressure. The produced ethylene-butene-1 copolymer had a melt index of 2.0 and a density of 0.925. To 100 parts by weight of the above ethylene-butene-1 copolymer, 2 parts by weight of dicumyl peroxide and 4.
A composition obtained by adding 0.2 parts by weight of 4'-thiobis(6-t-butyl-4-hydroxybenzyl) was mixed at a temperature of 80 to 90°C, and then an extruder was used to extrude a copper material with a diameter of 2 m/m. An insulating layer with a thickness of 1 m/m was formed on the body by extrusion at about 130°C. It was then crosslinked in a vulcanization tube heated to 200°C. Table 1 shows various properties of the obtained crosslinked cable. As is clear from the table, the insulating layer obtained using the composition of the present invention had a high gel fraction, a low thermal deformation rate, and an improved impulse breakdown voltage. Example 2 In Example 1, the composition of the gas supplied to the autoclave was changed to 90 mol% ethylene and 1 butene-1.
Copolymerization of ethylene and butene-1 was carried out in the same manner as in Example 1 except that the hydrogen content was 10 mol % and the hydrogen content was 25% of the total pressure. The melt index of the produced ethylene-butene-1 copolymer was 4.0,
The density was 0.925. Next, the melt index used in Example 1
2.0, density 0.925 ethylene-butene-1 copolymer, the above melt index 4.0, density
A crosslinked cable was obtained in the same manner as in Example 1, except that a 0.925 ethylene/butene-1 copolymer was used. The characteristic results are also listed in Table 1. Example 3 In Example 1, the composition of the gas supplied to the autoclave was changed to 97 mol% ethylene and hexane.
Copolymerization of ethylene and hexene-1 was carried out in the same manner as in Example 1, except that the copolymerization was carried out at 85 DEG C. and hydrogen was 33% of the total pressure. The produced ethylene/hexene-1 copolymer had a melt index of 5.0 and a density of 0.935. Next, the melt index used in Example 1
In place of the ethylene-butene-1 copolymer with a melt index of 5.0 and a density of 0.925,
A crosslinked cable was obtained in the same manner as in Example 1, except that a 0.935 ethylene/hexene-1 copolymer was used. The characteristic results are also listed in Table 1. Example 4 In Example 1, the composition of the gas supplied to the autoclave was changed to 70 mol% ethylene and propylene.
Copolymerization of ethylene and propylene was carried out in the same manner as in Example 1 except that the amount of hydrogen was 30 mol % and the amount of hydrogen was 3% of the total pressure. The produced ethylene-propylene copolymer had a melt index of 1.0 and a density of 0.920. Next, the melt index used in Example 1
Instead of the ethylene-butene-1 copolymer having a melt index of 1.0 and a density of 0.925,
A crosslinked cable was obtained in the same manner as in Example 1, except that a 0.920 ethylene/propylene copolymer was used. The characteristic results are also listed in Table 1. Comparative Example 1 Melt index 1.0 manufactured by high pressure method,
A crosslinked cable was obtained in the same manner as in Example 1, except that low-density polyethylene with a density of 0.919 (trade name: Nisseki Rexron W2000) was used. The characteristic results are also listed in Table 1.

[Table] Rate

Claims (1)

[Claims] 1 Copolymerizing ethylene and an α-olefin having 3 to 12 carbon atoms in a gas phase substantially free of solvent in the presence of a catalyst consisting of a solid substance containing magnesium, titanium, and/or vanadium, and organoaluminium. The density obtained is 0.890~0.945
An insulating layer forming composition characterized in that it contains 100 parts by weight of an ethylene/α-olefin copolymer having a melt index of 0.1 to 20 and 0.1 to 5 parts by weight of a crosslinking agent.