JP2017002218A - High dielectric insulation silicone rubber composition - Google Patents

Abstract

SOLUTION: A high dielectric silicone rubber composition contains (A) organopolysiloxane represented by the following average composition formula (1) of 100 pts.mass, RSiO, where Ris same or different unsubstituted/substituted monovalent hydrocarbon group, n is a positive number of 1.98 to 2.02, (B) two or more kinds of multiple oxide of 5 to 300 pts.mass and (C) a curing agent of 0.01 to 5 pts.mass.EFFECT: The silicon rubber composition provide a high dielectric insulation rubber by curing, the rubber can alleviate concentration of electrical field efficiently and suitable for a powder cable connection part because excellent in weather resistance as well. Also a power cable connecting with a stress cone containing a cured article of the composition can avoid concentration of electrical filed and is excellent in weather resistance.SELECTED DRAWING: None

Description

  The present invention relates to a high dielectric insulating silicone rubber composition used for a rubber stress cone that forms an intermediate connection portion and a terminal connection portion of a power cable.

When connecting CV cables (Cross-Linked Polyethylene Insulated Cable) to CV cables, transformers, overhead wires, etc., it is necessary to remove the external semiconductive layer at the end of the CV cable to a predetermined length. However, simply removing the external semiconductive layer concentrates the electric field at the end of the external semiconductive layer and impairs the electrical characteristics. Therefore, a normal stress cone is provided to alleviate the concentration of the electric field. Conventional rubber stress cones are, for example, an insulating rubber member to which a double oxide mainly composed of EPDM or the like is added, and an elastic high dielectric material provided between the insulating rubber member and a cable shielding layer of an inserted cable. It is comprised by the cylindrical member which consists of a rate insulating rubber (patent document 1: Unexamined-Japanese-Patent No. 8-50807).
In addition, as a rubber composition having an improved relative dielectric constant, polyolefin, ethylene-propylene rubber, acrylic rubber, and nitrile rubber (Patent Document 2: Japanese Patent Laid-Open No. 2015-76168) are used as a base polymer, and metal oxide, titanium Examples thereof include compositions containing a high dielectric substance such as dielectric ceramics such as barium acid and carbon black. Since the stress cone is often exposed outdoors, a high dielectric material in which a high dielectric substance is blended with a silicone rubber having excellent weather resistance has also been developed (Patent Document 3: JP 2013-177558 A).

  For rubber, a π electron transfer conductive material such as carbon black or carbon fiber is often used as a conductivity imparting material. However, when ordinary carbon black is used, it is known that the relationship between current and voltage does not follow Ohm's law and becomes nonlinear due to the tunnel effect due to the carbon structure (Non-Patent Document 1: L. H.). K. van Beekand and B. I. C. F. van Pul, J. Appl. Polymer Sci., 1962, 6, 51.). For this reason, the non-linearity between these currents and voltages is not preferable in power applications such as power cable connection portions and electric field relaxation agents at the end portions that require resistance management.

  When the blending amount of the conductive filler is increased in order to improve the relative dielectric constant, the electrical insulation is lowered with the increase. Further, since the rubber hardness increases and the elongation at the time of cutting decreases, the moldability / workability and strength of the elastic body may be deteriorated.

JP-A-8-50807 JP, 2015-76168, A JP 2013-177558 A

L. H. K. van Beekand and B.M. I. C. F. van Pul, J.M. Appl. Polymer Sci. , 1962, 6, 51.

  The present invention has been made in view of the above circumstances, and provides a high dielectric insulating rubber cured product having a high relative dielectric constant and suitable for power cable connection, and a cured product thereof. An object is to provide a stress cone provided with a high dielectric insulating member.

  The inventors of the present invention diligently studied about the dielectric constant and electrical insulation of the high dielectric silicone rubber composition, and found that an ionic conductive agent obtained by blending a double oxide having a low specific resistance value and a double oxide having a high specific resistance value. In this case, it is found that a high dielectric insulating silicone rubber composition suitable for a power cable connecting portion can be obtained by preferably curing the silicone rubber composition with an alkyl peroxide. It came to make.

Accordingly, the present invention provides the following high dielectric insulating silicone rubber composition and stress cone.
[1]
(A) 100 parts by mass of an organopolysiloxane represented by the following average composition formula (1):
R ¹ _n SiO _{(4-n) / 2} (1)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 1.98 to 2.02.)
(B) 5 to 300 parts by mass of two or more types of double oxides,
(C) A high dielectric insulating silicone rubber composition comprising 0.01 to 5 parts by mass of a curing agent.
[2]
The component (B) is a double oxide selected from a solid solution of zinc oxide and aluminum oxide, a solid solution of tin oxide and antimony oxide, and a solid solution of titanium oxide, tin oxide and antimony oxide, and has a specific resistance value of 1,000 to It is a blend of a double oxide (a) less than 10,000 Ωm and a double oxide (b) having a specific resistance value of 10,000 to 50,000 Ωm, and the mass ratio of the double oxides (a) and (b) is ( The high dielectric insulating silicone rubber composition according to [1], wherein a) / (b) = 5/95 to 95/5.
[3]
The high dielectric insulating silicone rubber composition according to [1] or [2], wherein the component (C) is an alkyl peroxide.
[4]
The high dielectric insulating silicone rubber according to any one of [1] to [3], further comprising 0.05 to 5 parts by mass of an ionic conductivity imparting agent as component (D) with respect to 100 parts by mass of component (A). Composition.
[5]
The high dielectric insulating silicone rubber composition according to any one of [1] to [4], further comprising (E) reinforcing silica in an amount of 1 to 70 parts by weight per 100 parts by weight of component (A).
[6]
The high dielectric insulating silicone rubber composition according to any one of [1] to [5], wherein the cured product of the silicone rubber composition has a relative dielectric constant of 25 or more and a volume resistivity of 10 ¹¹ to 10 ¹⁷ Ωm.
[7]
The high dielectric insulating silicone rubber composition according to any one of [1] to [6], which is used for relaxing an electric field that relaxes an electric field concentrated on a terminal portion of a power cable.
[8]
The stress cone provided with the high dielectric insulating member which consists of hardened | cured material of the high dielectric insulating silicone rubber composition in any one of [1]-[6].

  The silicone rubber composition of the present invention provides a high dielectric insulating rubber by curing, and this rubber can effectively reduce electric field concentration and is excellent in weather resistance. It is. Moreover, the power cable connected by the stress cone containing the hardened | cured material of this composition can avoid concentration of electric power, and is excellent also in weather resistance.

Hereinafter, the present invention will be described in detail.
The rubber composition of the present invention comprises the following components (A) to (C) and, if necessary, components (D) and (E).
(A) Organopolysiloxane (B) Double oxide (C) Curing agent (D) Ionic conductivity imparting agent (E) Reinforcing silica

[(A) Organopolysiloxane]
The organopolysiloxane of the component (A) is represented by the following average composition formula (1).
R ¹ _n SiO _{(4-n) / 2} (1)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 1.98 to 2.02.)

Here, in the above formula, the unsubstituted or substituted monovalent hydrocarbon group represented by R ¹ is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group, or a cycloalkyl such as a cyclohexyl group. Group, vinyl group, allyl group, butenyl group, alkenyl group such as hexenyl group, aryl group such as phenyl group, tolyl group, etc., and some or all of the hydrogen atoms bonded to carbon atoms of these groups are halogen atoms, cyano Examples thereof include a chloromethyl group, a trifluoropropyl group, a cyanoethyl group and the like substituted with a group, preferably an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms. It is. A methyl group, a vinyl group, a phenyl group, and a trifluoropropyl group are preferable, and 50 mol% or more, particularly 80 mol% or more of R ¹ is preferably a methyl group. Moreover, it is preferable to have two or more alkenyl groups in the molecule. A plurality of R ¹ may be the same or different.

The organopolysiloxane of component (A) is preferably basically linear, but may have some branching as long as the rubber elasticity of the resulting cured product is not impaired. Or a mixture of two or more types of organopolysiloxanes having different degrees of polymerization. Further, the organopolysiloxane preferably has an average degree of polymerization of 100 to 20,000, particularly 3,000 to 10,000.
In addition, an average degree of polymerization can be calculated | required as a number average degree of polymerization of polystyrene conversion by gel permeation chromatography (GPC).

[(B) Double oxide]
The composition of the present invention contains two or more kinds of double oxides as the component (B).
The double oxide is a metal oxide in which two or more kinds of metals coexist as an oxide or a metal element, and includes both a substitution type and an intrusion type.

Accordingly, examples of such a double oxide include a solid solution compound of zinc oxide (ZnO) and aluminum oxide (Al ₂ O ₃ ), and a solid solution of tin oxide (SnO ₂ ) and antimony oxide (Sb ₂ O ₅ ). A compound of solid solution of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ), a compound of solid solution of zinc oxide (ZnO) and titanium oxide (TiO ₂ ), magnesium oxide (MgO) and aluminum oxide A solid solution compound of (Al ₂ O ₃ ), a solid solution compound of titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ) and antimony oxide (Sb ₂ O ₅ ), titanium oxide (TiO ₂ ) and tin oxide ( SnO ₂₎ and ne compound of solid solution of antimony oxide (Sb ₂ O ₅₎ with a compound of the solid solution of potassium oxide (K ₂ O) and iron oxide (FeO) and titanium oxide (TiO ₂₎ And the like. These can be used alone or in combination of two or more. Among these, preferred are a solid solution compound of zinc oxide and aluminum oxide, a solid solution compound of tin oxide and antimony oxide, and a solid solution compound of titanium oxide, tin oxide and antimony oxide, and particularly conductive zinc oxide doped with aluminum atoms. Is preferred. The reason for this is that it has good dispersibility and high processability with respect to polymer dispersions such as resins, and the hardness of the powder itself, such as Mohs hardness, is relatively low. Therefore, there are advantages in that the selection range is wide in terms of particle system, dispersibility, and shape, and the cost is stable.

As an example of a method for producing a double oxide, one kind or two or more kinds of different metal ions are dispersed in a certain metal oxide crystal particle and fired in a reducing atmosphere. For example, in the case of a double oxide of zinc oxide and aluminum oxide, the zinc oxide and aluminum salt are treated in an aqueous ammonium salt solution and dehydrated and fired in a hydrogen atmosphere (Japanese Patent Publication No. 62-41171). reference).
In addition, a commercial item can be used as said complex oxide, for example, as the conductive zinc white thru | or zinc oxide which doped the aluminum atom to zinc oxide, the thing by Honjo Chemical Co., Ltd. KN or the like can be used.

  Many of such double oxides have conductivity as an n-type semiconductor, and the conductivity is characterized by being hardly influenced by humidity or environmental factors. The mechanism of conductivity is considered to be that a surplus or a deficient electron pair of metal atoms having different valences, which are partly substituted by doping, cause semiconductor conductivity.

  (B) The compounding quantity of the double oxide of a component is 5-300 mass parts with respect to 100 mass parts of (A) component, Preferably it is 30-280 mass parts, More preferably, it is 50-250 mass parts. (A) If the amount is less than 5 parts by mass per 100 parts by mass of the component, the intended high dielectric constant characteristics may not be obtained. If it exceeds 300 parts by mass, the cured rubber obtained by curing the composition Rubber strength and rubber elasticity may be reduced.

The double oxide of component (B) is a blend of a double oxide (a) having a specific resistance of less than 1,000 to 10,000 Ωm and a double oxide (b) having a specific resistance of 10,000 to 50,000 Ωm. The relative dielectric constant of the composition can be 25 or more and the volume resistivity can be 10 ¹¹ Ωm or more. If the relative dielectric constant is less than 25, the electric field relaxation effect that disperses the electric field concentrated on the terminal portion of the high-voltage power cable is not sufficient. When the volume resistivity is less than 10 ¹¹ Ωm, the insulation is insufficient, which may cause dielectric breakdown due to electric field concentration. A blend of a double oxide (a) having a specific resistance value of less than 1,000 to 10,000 Ωm and a double oxide (b) having a specific resistance value of 10,000 to 50,000 Ωm, with a mass ratio of (a) / (b) = 5/95 to 95/5, more preferably 7/93 to 93/7, still more preferably 10/90 to 90/10. When trying to obtain a relative dielectric constant of 25 or more with only the double oxide (a) having a specific resistance value of less than 1,000 to 10,000 Ωm, the compounding amount exceeds 300 parts by mass, and the rubber strength and rubber elasticity of the cured rubber. Will fall. A dielectric constant of only a double oxide (b) having a specific resistance value of 10,000 to 50,000 Ωm increases, but there is a problem in that it exhibits semiconductivity and the insulating property is lowered.

[(C) Curing agent]
In the present invention, the alkyl peroxide is preferable as the curing agent for the component (C), and is used in an appropriate amount effective for curing. When cured with an acyl peroxide, the dielectric constant may be lowered due to the carboxylic acid as a decomposition residue. Moreover, even if it hardens | cures by the combination of a platinum-type catalyst and organohydrogenpolysiloxane, sufficient dielectric constant may not be obtained.

  Examples of the alkyl peroxide include 2,4-dicumyl peroxide, 2,5-dimethyl-bis (2,5-t-butylperoxy) hexane, di-t-butyl peroxide, and the like. The addition amount of the alkyl peroxide may be 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass with respect to 100 parts by mass of the component (A). If the addition amount is less than 0.01 parts by mass, the crosslinking reaction does not proceed sufficiently, and physical properties such as hardness reduction and insufficient rubber strength may be deteriorated. If it exceeds 5 parts by mass, it is economically disadvantageous. In some cases, a decomposition product of the curing agent is generated so much that a sufficient dielectric constant cannot be obtained.

[(D) Ionic conductivity imparting agent]
The ionic conductivity imparting agent which is the component (D) of the present invention is for imparting conductivity to the obtained cured product and stabilizing the relative dielectric constant. The ion conductivity imparting agent is an alkali metal or alkaline earth metal salt or an ionic liquid. Here, the ionic liquid is a molten salt that is liquid at room temperature, and is also called a room temperature molten salt, and has a melting point of 50 ° C. or less, preferably −100 to 30 ° C., more preferably −50 to The one at 20 ° C. Such an ionic liquid has characteristics such as no vapor pressure (nonvolatile), high heat resistance, nonflammability, and chemical stability.

Examples of the alkali metal or alkaline earth metal salt include alkali metal salts such as lithium, sodium, and potassium; alkaline earth metal salts such as calcium and barium. Specific examples thereof include LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiAsF ₆ , LiCl, NaSCN, KSCN, NaCl, NaI, KI and other alkali metal salts; Ca (ClO ₄ ) ₂ And alkaline earth metal salts such as Ba (ClO ₄ ) ₂ . From the viewpoint of solubility, LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiAsF ₆ and LiCl are preferable, and LiCF ₃ SO ₃ and LiN (CF ₃ SO ₂ ) ₂ are particularly preferable.

The ionic liquid consists of a quaternary ammonium cation and an anion. This quaternary ammonium cation is either imidazolium, pyridinium or a cation represented by the formula: R ^X ₄ N ⁺ [wherein R ^X is a hydrogen atom or an organic group having 1 to 20 carbon atoms]. It is a form.
In the above formula, examples of the organic group represented by R ^X include a monovalent hydrocarbon group having 1 to 20 carbon atoms and an alkoxyalkyl group. More specifically, for example, alkyl groups such as methyl group, pentyl group, hexyl group, heptyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cyclooctyl group, phenyl group, tolyl group, xylyl group, An aryl group such as a naphthyl group; an aralkyl group such as a benzyl group and a phenethyl group; and an alkoxyalkyl group such as an ethoxyethyl group (—CH ₂ CH ₂ OCH ₂ CH ₃ ). Further, two of the organic groups represented by R ^X may be bonded to form a cyclic structure, and in this case, two R ^X are combined to form a divalent organic group. The main chain of the divalent organic group may be composed only of carbon, or may contain a hetero atom such as an oxygen atom or a nitrogen atom. Specifically, for example, a divalent hydrocarbon group [e.g., an alkylene group having 3 to 10 carbon atoms, wherein _{:-( CH 2) a -O- (CH} 2) b - [ wherein, a is 1 5 is an integer of 5, b is an integer of 1 to 5, and a + b is an integer of 4 to 10.].
Specific examples of the cation represented by the formula: R ^X ₄ N ⁺ include a methyltri n-octylammonium cation, an ethoxyethylmethylpyrrolidinium cation, and an ethoxyethylmethylmorpholinium cation.
The anion is not particularly limited. For example, AlCl ₄ ⁻ , Al ₃ Cl ₈ ⁻ , Al ₂ Cl ₇ ⁻ , ClO ₄ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ and (CF ₃ SO ₂ ) ₃ C ⁻ are preferable, and PF ₆ ⁻ , BF ₄ ⁻ , CF ₃ SO ₃ ⁻ and (CF ₃ SO ₂ ) ₂ N ⁻ are more preferable.

  The ion conductive compounds can be used singly or in combination of two or more.

  (D) The compounding quantity of a component is 0.05-5 mass parts normally with respect to 100 mass parts of (A) component, Preferably it is 0.07-3 mass parts. When the blending amount is less than 0.05 parts by mass, the movement of ions is too small, so that the relative dielectric constant is difficult to stabilize and the effect is small. If it exceeds 5 parts by mass, there will be a problem in terms of cost.

[Other ingredients]
In addition to the above essential components, other components can be added to the composition of the present invention as necessary within a range that does not interfere with the effects of the present invention.

[(E) Reinforcing silica fine powder]
It is preferable to add reinforcing silica fine powder to the composition of the present invention. Silica fine powder is to impart mechanical strength such as silicone rubber, BET specific surface area for this purpose 10 m ² / g or more, preferably preferred those 50 to 400 m ² / g. Examples of the silica fine powder include fumed silica (dry silica) and precipitated silica (wet silica), and fumed silica (dry silica) is preferable. Examples of commercially available reinforcing silicas that can be used include Aerosil 130, 200, 300, 380 (trade name, manufactured by Nippon Aerosil Co., Ltd.), Cab-O-sil MS-5, MS-7, HS-5, HS. -7 (trade name, manufactured by Cabot Corporation), Santocel FRC, CS (trade name, manufactured by Monsanto Corporation), Nipsil VN-3 (trade name, manufactured by Nippon Silica Industry Co., Ltd.), and the like. Further, these surfaces may be hydrophobized with organopolysiloxane, organopolysilazane, chlorosilane, organohydrogenpolysiloxane, alkoxysilane or the like. These silicas may be used alone or in combination of two or more.

  The amount of reinforcing silica fine powder added is preferably 1 to 70 parts by weight, particularly 5 to 50 parts by weight, per 100 parts by weight of the organopolysiloxane of component (A). When the amount is more than 70 parts by mass per 100 parts by mass of the organopolysiloxane (A), the processability of the composition may be lowered.

  Another optional component is a filler, for example, silicone rubber powder, bengara, ground quartz, calcium carbonate and the like.

  Furthermore, if necessary, various additives such as a colorant and a heat resistance improver, a reaction control agent, a release agent, a filler dispersant, and the like can be added. Diphenylsilanediol, various alkoxysilanes, carbon functional silanes, silanol group-containing low molecular siloxanes, and the like used as a dispersant for the filler are preferably kept to a minimum amount so as not to impair the effects of the present invention. .

In order to impart or enhance flame resistance and fire resistance, platinum-containing materials, platinum compounds and titanium dioxide, platinum and manganese carbonate, platinum and γ-Fe ₂ O ₃ , ferrite, mica, glass fiber, glass flakes, etc. Known additives may be added.

[Preparation and use of composition]
In the silicone rubber composition according to the present invention, for example, required components are uniformly mixed using a rubber kneader such as a two-roll roll, a Banbury mixer, or a dough mixer (kneader), and heat-treated as necessary. Can be obtained. In this case, for example, the (A) component organopolysiloxane may be mixed with the (B) component double oxide and further processed by a three-roll treatment or the like. They can be added and mixed.

  The silicone rubber composition thus obtained can be molded and cured into a power cable connecting rubber member, that is, a rubber stress cone, by various molding methods such as mold pressure molding and extrusion molding. The power cable is connected using the rubber stress cone thus obtained. Specifically, the rubber stress cone is used as an electric field relaxation layer for a connection jig in an intermediate connection portion or a terminal connection portion of a power cable.

  In addition, the curing conditions of the silicone rubber composition according to the present invention can be set to 100 to 200 ° C., particularly 110 to 180 ° C. for 1 to 60 minutes, particularly 5 to 45 minutes. In this case, post-cure (secondary vulcanization) can be performed at 100 to 300 ° C., particularly 120 to 250 ° C. for 1 to 12 hours, particularly 2 to 8 hours, if necessary.

In addition, the obtained cured silicone rubber has a relative dielectric constant of 25 or more, more preferably 25 to 100, still more preferably 25 to 50, and a volume resistivity of 10 ^{11 in} the measurement method described later. 10 ¹⁷ Ωm, more preferably 10 ¹¹ to 10 ¹⁶ Ωm, and still more preferably 10 ¹² to 10 ¹⁵ Ωm.

  EXAMPLES Hereinafter, although a preparation example, an Example, and a comparative example are given and this invention is demonstrated concretely, this invention is not restrict | limited to these Examples. In the following description, “part” means “part by mass” unless otherwise specified.

Preparation Example 1: Base compound A
The main chain is composed of dimethylsiloxane units and methylvinylsiloxane units, the ends are blocked with dimethylvinylsiloxane units, and the vinyl group content is about 0.17 with respect to all monovalent organic groups bonded to silicon atoms contained in the molecule. 100 parts by weight of raw rubber-like organopolysiloxane having an average degree of polymerization of about 5,000, 8 parts of silanol group-containing dimethylpolysiloxane (degree of polymerization n = 10) as a dispersant, and wet silica as a filler (trade name: 40 parts of Nipsil VN-3, a product manufactured by Nippon Silica Industry Co., Ltd.) was added and heat treated for 2 hours to prepare Compound A.

Preparation Example 2: Base compound B
The main chain is composed of dimethylsiloxane units and methylvinylsiloxane units, the ends are blocked with dimethylvinylsiloxane units, and the vinyl group content is about 0.17 with respect to all monovalent organic groups bonded to silicon atoms contained in the molecule. Conductive zinc white (Honjo Chemical Co., Ltd., specific resistance value) in which 100 parts of a raw rubber-like organopolysiloxane having an average degree of polymerization of about 5,000 mol% is doped with aluminum atoms in zinc oxide as a double oxide. 5,350 Ωm, average particle size 1.44 μm) 203 parts and conductive zinc oxide 23-KN (manufactured by Hakusui Tech Co., Ltd., specific resistance value 31,900 Ωm, average particle size 0.18 μm) 22 parts were added, 30 minutes Compound B was prepared by mixing.

Preparation Example 3: Base compound C
The main chain is composed of dimethylsiloxane units and methylvinylsiloxane units, the ends are blocked with dimethylvinylsiloxane units, and the vinyl group content is about 0.17 with respect to all monovalent organic groups bonded to silicon atoms contained in the molecule. Conductive zinc white (Honjo Chemical Co., Ltd., specific resistance value) in which 100 parts of a raw rubber-like organopolysiloxane having an average degree of polymerization of about 5,000 mol% is doped with aluminum atoms in zinc oxide as a double oxide. 5,350 Ωm, average particle size 1.44 μm) 203 parts and conductive zinc oxide 23-KN (manufactured by Hux Itec Corp., specific resistance 31,900 Ωm, average particle size 0.18 μm) 22 parts, LiN (CF ₃ SO ₂ ) Compound C was prepared by adding 0.19 part of adipic acid ester containing 20% by mass of ₂ and mixing for 30 minutes.

Preparation Example 4: Base compound D
The main chain is composed of dimethylsiloxane units and methylvinylsiloxane units, the ends are blocked with dimethylvinylsiloxane units, and the vinyl group content is about 0.17 with respect to all monovalent organic groups bonded to silicon atoms contained in the molecule. Conductive zinc white (Honjo Chemical Co., Ltd., specific resistance value) in which 100 parts of a raw rubber-like organopolysiloxane having an average degree of polymerization of about 5,000 mol% is doped with aluminum atoms in zinc oxide as a double oxide. 180 parts of 5,350 Ωm, average particle size 1.44 μm) and 45 parts of conductive zinc oxide 23-KN (manufactured by Hux Itec Co., Ltd., specific resistance 31,900 Ωm, average particle size 0.18 μm) are added and mixed for 30 minutes Compound D was prepared.

Preparation Example 5: Base compound E
The main chain is composed of dimethylsiloxane units and methylvinylsiloxane units, the ends are blocked with dimethylvinylsiloxane units, and the vinyl group content is about 0.17 with respect to all monovalent organic groups bonded to silicon atoms contained in the molecule. Conductive zinc white (Honjo Chemical Co., Ltd., specific resistance value) in which 100 parts of a raw rubber-like organopolysiloxane having an average degree of polymerization of about 5,000 mol% is doped with aluminum atoms in zinc oxide as a double oxide. 180 parts of 5,350 Ωm, average particle size 1.44 μm) and 45 parts of conductive zinc oxide 23-KN (manufactured by Hux Itec Co., Ltd., specific resistance value 31,900 Ωm, average particle size 0.18 μm), LiN (CF ₃ SO ₂ ) Compound E was prepared by adding 0.19 part of adipic acid ester containing 20% by mass of ₂ and mixing for 30 minutes.

Preparation Example 6: Base compound F
The main chain is composed of dimethylsiloxane units and methylvinylsiloxane units, the ends are blocked with dimethylvinylsiloxane units, and the vinyl group content is about 0.17 with respect to all monovalent organic groups bonded to silicon atoms contained in the molecule. Conductive zinc white (Made by Honjo Chemical Co., Ltd., specific resistance value 5) in which 100 parts of raw rubber-like organopolysiloxane having an average degree of polymerization of about 5,000 mol% and zinc oxide as a double oxide are doped with aluminum atoms. , 350 Ωm, average particle size 1.44 μm) 225 parts was added and mixed for 30 minutes to prepare Compound F.

Preparation Example 7: Base compound G
The main chain is composed of dimethylsiloxane units and methylvinylsiloxane units, the ends are blocked with dimethylvinylsiloxane units, and the vinyl group content is about 0.17 with respect to all monovalent organic groups bonded to silicon atoms contained in the molecule. Conductive zinc white (Made by Honjo Chemical Co., Ltd., specific resistance value 5) in which 100 parts of raw rubber-like organopolysiloxane having an average degree of polymerization of about 5,000 mol% and zinc oxide as a double oxide are doped with aluminum atoms. , 350 Ωm, average particle size 1.44 μm) 225 parts, 0.19 part of adipic acid ester containing 20% by mass of LiN (CF ₃ SO ₂ ) ₂ was added and mixed for 30 minutes to prepare Compound G.

Example 1
Compound A is obtained by blending 15 parts of Compound A and 85 parts of Compound B and kneading 0.5 part of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a curing agent. Using this, a 100 mm square, 5 mm thick sheet-like elastic body was molded under heating and pressure. The molding was performed at 165 ° C. for 10 minutes, and the molding pressure was 7.8 MPa (80 kgf / cm ² ). Thereafter, secondary crosslinking (post-cure) was performed at 200 ° C. for 4 hours to prepare a sample for measuring relative permittivity. The rubber physical properties were measured according to JIS K6249.

(Example 2)
A sample for measuring relative permittivity and a sample for measuring physical properties of rubber were prepared in the same manner as in Example 1 except that Compound C was used instead of Compound B.

(Example 3)
A sample for measuring a relative dielectric constant and a sample for measuring physical properties of rubber were prepared in the same manner as in Example 1 except that Compound D was used instead of Compound B.

Example 4
A sample for measuring relative permittivity and a sample for measuring physical properties of rubber were prepared in the same manner as in Example 1 except that Compound E was used instead of Compound B.

(Comparative Example 1)
A sample for measuring a relative dielectric constant and a sample for measuring physical properties of rubber were prepared in the same manner as in Example 1 except that Compound F was used instead of Compound B.

(Comparative Example 2)
A sample for measuring a relative dielectric constant and a sample for measuring physical properties of rubber were prepared in the same manner as in Example 1 except that Compound G was used instead of Compound B.

[Measurement of relative permittivity]
About the sample for relative dielectric constant measurement obtained by said Example and comparative example, the relative dielectric constant was measured using Soken Denki Co., Ltd. automatic sharing bridge (device name DAC-1M-D1). The electrodes were a main electrode 50 mmφ, a guard electrode 54 × 80 mmφ, and a counter electrode 80 mmφ, and the measurement frequency was 50 Hz. The measured value at an applied voltage of 500V was read. The results are shown in Table 1.

[Measurement of volume resistivity]
The volume resistivity was measured according to JIS K6249.

Claims (8)

(A) 100 parts by mass of an organopolysiloxane represented by the following average composition formula (1):
R ¹ _n SiO _{(4-n) / 2} (1)
(In the formula, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 1.98 to 2.02.)
(B) 5 to 300 parts by mass of two or more types of double oxides,
(C) A high dielectric insulating silicone rubber composition comprising 0.01 to 5 parts by mass of a curing agent.   The component (B) is a double oxide selected from a solid solution of zinc oxide and aluminum oxide, a solid solution of tin oxide and antimony oxide, and a solid solution of titanium oxide, tin oxide and antimony oxide, and has a specific resistance value of 1,000 to It is a blend of a double oxide (a) less than 10,000 Ωm and a double oxide (b) having a specific resistance value of 10,000 to 50,000 Ωm, and the mass ratio of the double oxides (a) and (b) is ( The high dielectric insulating silicone rubber composition according to claim 1, wherein a) / (b) = 5/95 to 95/5.   The high dielectric insulating silicone rubber composition according to claim 1, wherein the component (C) is an alkyl peroxide.   The high dielectric insulating silicone rubber composition according to any one of claims 1 to 3, further comprising 0.05 to 5 parts by mass of an ionic conductivity imparting agent as component (D) with respect to 100 parts by mass of component (A). object.   The high dielectric insulating silicone rubber composition according to any one of claims 1 to 4, further comprising (E) reinforcing silica in an amount of 1 to 70 parts by mass with respect to 100 parts by mass of the component (A). The high dielectric insulating silicone rubber composition according to any one of claims 1 to 5, wherein the cured product of the silicone rubber composition has a relative dielectric constant of 25 or more and a volume resistivity of 10 ¹¹ to 10 ¹⁷ Ωm.   The high dielectric insulating silicone rubber composition according to any one of claims 1 to 6, which is used for relaxing an electric field that relieves an electric field concentrated on a terminal portion of a power cable.   The stress cone provided with the high dielectric insulating member which consists of a hardened | cured material of the high dielectric insulating silicone rubber composition of any one of Claims 1-6.