JP6345012B2 - High dielectric constant rubber composition and power cable parts - Google Patents

Description

  The present invention relates to a high dielectric constant rubber composition and a power cable component.

  In order to relax the electric field, power cable components such as a tape and a tube are usually arranged in a portion where the electric field irregularity portion such as a connection portion or a termination portion of the power cable is likely to become. These parts are generally composed of a high dielectric constant rubber composition, and this high dielectric constant rubber composition is required to have a high relative dielectric constant in order to increase the electric field relaxation effect.

  As a high dielectric constant rubber composition used to form such a power cable component, for example, in Patent Document 1 below, a high dielectric constant filler such as barium titanate powder and process oil are blended with EPDM rubber. A dielectric constant rubber composition is disclosed.

JP 2003-174719 A

  However, the high dielectric constant rubber composition described in Patent Document 1 has the following problems.

  That is, the high dielectric constant rubber composition described in Patent Document 1 has room for improvement in terms of the electrical characteristics of power cable components by moisture absorption obtained using the high dielectric constant rubber composition.

  This invention is made | formed in view of the said situation, and it aims at providing the high dielectric constant rubber composition and power cable component which can fully suppress the fall of the electrical property of the power cable component by moisture absorption.

  The present inventor has studied to solve the above problems. First, in order to increase the relative dielectric constant of the high dielectric constant rubber composition described in Patent Document 1, it was considered to add a large amount of high dielectric filler. However, in this case, in a power cable component obtained by using a high dielectric constant rubber composition, an increase in dielectric loss tangent (tan δ), a decrease in insulation resistance, and the like may occur. In other words, the electrical characteristics of power cable components may be reduced. Here, the inventor considered this cause as follows. That is, since EP rubber and silicone rubber are non-polar, the familiarity between the interface of non-polar rubber such as EP rubber and silicone rubber and the interface of high dielectric filler such as polar barium titanate powder is poor. For this reason, a gap is easily generated between the high dielectric constant filler and the nonpolar rubber. Therefore, when an AC voltage is applied to the power cable component, the polar component of the filler follows the AC voltage. As a result, the present inventor thought that tan δ would increase or the insulation resistance would decrease. Therefore, as a result of further earnest research, the present inventor has obtained a titanate and a silane compound having an alkoxyl group in a base resin containing a nonpolar hydrocarbon rubber and a polar group-containing resin having a polar group. It has been found that the above-mentioned problems can be solved by blending, and the present invention has been completed.

That is, the present invention provides hydrocarbon rubber, and a base resin containing a polar group-containing resin having a polar group, and titanate, viewed contains a silane compound having an alkoxyl group, the polar group-containing resin anhydrous It is a high dielectric constant rubber composition which is maleic acid-modified polyethylene .

  The high dielectric constant rubber composition of the present invention can sufficiently suppress a decrease in electrical characteristics of power cable components due to moisture absorption.

  In addition, this inventor estimates as follows about the reason for which the said effect is acquired.

  That is, a polar group-containing resin can be interposed between the polar titanate and the nonpolar hydrocarbon rubber, and the interface between the polar titanate and the nonpolar hydrocarbon rubber Is improved by the polar group contained in the polar group-containing resin. In addition, when the alkoxyl group of the silane compound is hydrolyzed when the high dielectric constant rubber composition is kneaded, the silane compound can bind the titanate and the hydrocarbon rubber. For this reason, the gap between the titanate interface and the hydrocarbon rubber interface can be made sufficiently small. Therefore, even if an AC voltage is applied to the power cable component, the polar component of titanate is sufficiently suppressed from following the AC voltage. For this reason, an increase in tan δ is suppressed and a decrease in insulation resistance is suppressed. As a result, the inventor presumes that the high dielectric constant rubber composition of the present invention can sufficiently suppress the deterioration of the electrical characteristics of the power cable component due to moisture absorption.

  In the high dielectric constant rubber composition, the content of the hydrocarbon-based rubber in the base resin is 10 to 80% by mass, and the polar group-containing resin in the base resin is 20 to 90% by mass. It is preferable.

  In this case, in this case, compared with the case where either the content of the hydrocarbon rubber or the content of the polar group-containing resin in the base resin is out of the above range, the electrical characteristics of the power cable component are deteriorated due to moisture absorption. Can be sufficiently suppressed, and moderate processability can be obtained.

  In the high dielectric constant rubber composition, it is preferable that the base resin further includes a liquid hydrocarbon in a liquid state at a temperature of at least 20 to 30 ° C.

  In this case, the high dielectric constant rubber composition can have more excellent processability than when the base resin does not contain the liquid hydrocarbon.

  In the high dielectric constant rubber composition, the content of the hydrocarbon-based rubber in the base resin is 10 to 80% by mass, and the polar group-containing resin in the base resin is 10 to 80% by mass. The content of the liquid hydrocarbon in the base resin is preferably 10 to 70% by mass.

  In this case, compared with the case where any of the hydrocarbon-based rubber content, the polar group-containing resin content, and the liquid hydrocarbon content in the base resin is out of the above range, the electric power of the power cable component is absorbed by moisture absorption. The deterioration of characteristics can be more sufficiently suppressed and moderate processability can be obtained.

  In the said high dielectric constant rubber composition, it is preferable that the said titanate is mix | blended in the ratio of 50-500 mass parts with respect to 100 mass parts of said base resins.

  In this case, the electric field relaxation effect of the electric field relaxation unit 7 is further improved as compared with the case where the amount of titanate is less than 50 parts by mass with respect to 100 parts by mass of the base resin. Moreover, compared with the case where the compounding quantity of the titanate with respect to 100 mass parts of base resins exceeds 500 mass parts, a powder component will not increase too much and a moldability will improve more.

  In the said high dielectric constant rubber composition, it is preferable that the said silane compound is mix | blended in the ratio of 0.9-10.0 mass parts with respect to 100 mass parts of said base resins.

  In this case, compared with the case where the compounding quantity of the silane compound with respect to 100 parts by mass of the base resin is out of the above range, it is possible to more sufficiently suppress the deterioration of the electrical characteristics of the power cable component due to moisture absorption.

  Moreover, this invention is components for electric power cables obtained by heat-crosslinking the high dielectric constant rubber composition mentioned above.

  According to the power cable component of the present invention, when it is provided so as to cover a portion where electric field mismatching occurs such as a connection portion connecting the power cables, tan δ is sufficiently increased due to moisture absorption and insulation resistance is decreased due to moisture absorption. Therefore, it is possible to sufficiently suppress a decrease in electrical characteristics due to moisture absorption.

  ADVANTAGE OF THE INVENTION According to this invention, the high dielectric constant rubber composition and power cable component which can fully suppress the fall of the electrical property of the power cable component by moisture absorption are provided.

It is a fragmentary sectional view which shows one Embodiment of the components for electric power cables of this invention.

  Hereinafter, an embodiment of a power cable component of the present invention will be described with reference to FIG. FIG. 1 is a partial sectional view showing an embodiment of a power cable component of the present invention, and shows a state where two cables are connected by a cable connecting portion including the power cable component.

  As shown in FIG. 1, the cable connection unit 100 connects two power cables 10. Each of the two power cables 10 includes a central conductor 1, an internal semiconductive layer 2 covering the central conductor 1, an external semiconductive layer 3 covering the internal semiconductive layer 2, and a sheath 4 covering the external semiconductive layer 3. have. More specifically, the power cable 10 is composed of a main body portion and a tip portion provided at one end of the main body portion. Here, the main body is composed of a central conductor 1, an inner semiconductive layer 2, an outer semiconductive layer 3, and a sheath 4. The tip portion is composed of a first portion, a second portion, and a third portion that are sequentially provided in a direction away from the main body portion. The first part is composed of a central conductor 1, an internal semiconductive layer 2 and an external semiconductive layer 3, and the second part is composed of a central conductor 1 and an internal semiconductive layer 2. The third portion is composed only of the central conductor 1.

  The cable connection portion 100 includes a tubular conductive connection tube 5 that compressively connects the central conductor 1 of the third portion at the distal end portions of the two power cables 10, and covers the connection tube 5 and of the distal end portions of the power cable 10. An internal electrode 6 in contact with the internal semiconductive layer 2 of the second portion, an electric field relaxation portion 7 as a power cable component that covers the internal electrode 6 and relaxes the electric field from the internal electrode 6, and an electric field relaxation portion 7 The insulating part 8 to cover and the external electrode 9 which covers the insulating part 8 and contacts the external semiconductive layer 3 which is the first part of the tip part of the power cable 10 are provided.

  Here, the electric field relaxation part 7 is obtained by heat-crosslinking a high dielectric constant rubber composition. This high dielectric constant rubber composition is composed of a base resin, a titanate, and a silane compound having an alkoxyl group. And a crosslinking agent. The base resin contains a hydrocarbon rubber and a polar group-containing resin having a polar group.

  According to this electric field relaxation part 7, the fall of the electrical property of the cable connection part 100 by moisture absorption can fully be suppressed. That is, an increase in tan δ and a decrease in insulation resistance due to moisture absorption can be sufficiently suppressed. For this reason, according to the cable connection part 100, even if it puts in environments, such as the outdoors, a dielectric breakdown becomes difficult to occur.

  Next, the high dielectric constant rubber composition will be described in detail.

  As described above, the high dielectric constant rubber composition includes a base resin, a titanate, a silane compound having an alkoxyl group, and a crosslinking agent. The base resin includes a hydrocarbon rubber and a polar group-containing resin.

<Base resin>
(Hydrocarbon rubber)
The hydrocarbon rubber is a rubber made of hydrocarbon that is in a solid state at least at 20 to 30 ° C. Examples of such rubbers include rubbers containing ethylene as a structural unit such as ethylene propylene diene (EPDM) rubber and ethylene propylene terpolymer (EPT), isoprene rubber (IR), butadiene rubber (BR), butyl rubber (IIR), and the like. Is mentioned. These may be used alone or in combination of two or more. Among these, EPDM rubber is preferable because it has good electrical characteristics and can sufficiently reduce the viscosity.

(Polar group-containing resin)
The polar group-containing resin is not particularly limited as long as it is a resin having a polar group. As such a polar group-containing resin, for example, a main chain containing a hydrocarbon as a structural unit, a resin in which a functional group containing a polar group is provided as a side chain, or a part of the main chain containing a hydrocarbon as a structural unit And those containing a polar group. Examples of the hydrocarbon include ethylene, propylene, and butadiene. Examples of the polar group include a carbonyl group (—CO—). The functional group may have only one polar group or a plurality of functional groups. Examples of the functional group having such a polar group include a maleic anhydride group, a carboxylic acid group (—COOH), an ester group (—COOR), and an acid anhydride group (—CO—O—OC) represented by the following formula. -).

  The contents of the hydrocarbon-based rubber and polar group-containing resin in the base resin are not limited respectively, but when the base resin is composed of a hydrocarbon-based rubber and a polar group-containing resin, The content of the hydrocarbon-based rubber is 10 to 80% by mass, and the content of the polar group-containing resin in the base resin is preferably 20 to 90% by mass.

  In this case, compared with the case where either the hydrocarbon rubber content or the polar group-containing resin content in the base resin is out of the above range, the electrical characteristics of the power cable components are more sufficiently deteriorated due to moisture absorption. Moderate processability can be obtained.

  The content of the hydrocarbon-based rubber in the base resin is preferably 30 to 60% by mass, more preferably 30 to 50% by mass.

  The content of the polar group-containing resin in the base resin is preferably 40 to 70% by mass, and the content of the polar group-containing resin in the base resin is more preferably 50 to 70% by mass.

  In this case, compared with the case where either the hydrocarbon rubber content or the polar group-containing resin content in the base resin is out of the above range, the electrical characteristics of the power cable components are more sufficiently deteriorated due to moisture absorption. Moderate processability can be obtained.

(Liquid hydrocarbon)
The base resin preferably further contains a hydrocarbon that is in a liquid state at least at 20 to 30 ° C. In this case, the high dielectric constant rubber composition can have more excellent processability than when the base resin does not contain the liquid hydrocarbon. Examples of such liquid hydrocarbons include liquid EPDM, process oil, polybutene, and the like. These may be used alone or in combination of two or more. Among these, liquid EPDM is preferable. In this case, when the high dielectric constant rubber composition is subjected to a crosslinking treatment, the liquid EPDM is chemically combined with the hydrocarbon rubber to form a part of the hydrocarbon rubber. Can be improved.

  When the base resin further contains liquid hydrocarbon in addition to the hydrocarbon rubber and polar group-containing resin, the content of the hydrocarbon rubber in the base resin is 10 to 80% by mass, and the polar group in the base resin It is preferable that the content resin is 10 to 80% by mass and the liquid hydrocarbon content in the base resin is 10 to 70% by mass.

  In this case, compared with the case where any of the hydrocarbon-based rubber content, the polar group-containing resin content, and the liquid hydrocarbon content in the base resin is out of the above range, the electric power of the power cable component is absorbed by moisture absorption. The deterioration of characteristics can be more sufficiently suppressed and moderate processability can be obtained.

<Titanate>
Examples of titanates include titanates having a relative dielectric constant of 200 or more, such as calcium titanate and strontium titanate. You may use these individually or in combination of 2 or more types. Here, the relative dielectric constant refers to a relative dielectric constant measured when an alternating voltage of 10 kHz and 1 V is applied at 30 ° C.

  Of the titanates, calcium titanate is particularly preferred. In this case, compared with the case where a titanate other than calcium titanate is used, the relative permittivity of the electric field relaxation portion 7 can be reduced even if the base resin is blended in the same mass ratio as the titanate other than calcium titanate. Can be higher. In other words, when the titanate is calcium titanate, the relative permittivity of the electric field relaxation portion 7 can be efficiently increased with a small amount as compared with a case where the titanate is a titanate other than calcium titanate.

  The average particle size of the titanate is not particularly limited, but is preferably 0.5 to 5.0 μm because it is easily dispersed uniformly in the base resin, and 0.5 to 2.0 μm. It is more preferable that

  It is preferable that the compounding quantity of the titanate with respect to 100 mass parts of base resins is 50-500 mass parts. In this case, the electric field relaxation effect of the electric field relaxation unit 7 is further improved as compared with the case where the blending amount of titanate with respect to 100 parts by mass of the base resin is less than 50 parts by mass. Moreover, compared with the case where the compounding quantity of the titanate with respect to 100 mass parts of base resins exceeds 500 mass parts, a powder component will not increase too much and a moldability will improve more.

  The compounding amount of titanate with respect to 100 parts by mass of the base resin is more preferably 100 to 500 parts by mass, and particularly preferably 250 to 400 parts by mass.

上記式中、Ｒ^１〜Ｒ^３はそれぞれ独立にアルキル基を表し、Ｙは炭化水素基を表し、ｎは１以上の整数を表す。 <Silane compound>
The silane compound may have an alkoxyl group, but is preferably represented by the following structural formula.

In the above formula, R ^{1 to} R ³ each independently represents an alkyl group, Y represents a hydrocarbon group, and n represents an integer of 1 or more.

Examples of the hydrocarbon group include a vinyl group (—CH═CH ₂ ) and an alkyl group.

The alkyl group represented by R ^{1 to} R ³ is not particularly limited, but is preferably an alkyl group having 1 to 2 carbon atoms such as a methyl group and an ethyl group.

  The alkyl group as an example of the hydrocarbon group represented by Y is not particularly limited, but is preferably an alkyl group having 1 to 10 carbon atoms. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group.

  Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, hexyltriethoxysilane, vinylsilane oligomer, 5-hexenyltrimethoxysilane, and the like.

  It is preferable that the compounding quantity of the silane compound with respect to 100 mass parts of base resins is 0.9-10.0 mass parts. In this case, compared with the case where the compounding quantity of the silane compound with respect to 100 mass parts of base resins is less than 0.9 mass part, the fall of the electrical property of the components for electric power cables by moisture absorption can be suppressed more fully. Moreover, the advantage that a silane compound becomes difficult to bleed compared with the case where the compounding quantity of the silane compound with respect to 100 mass parts of base resins exceeds 10.0 mass parts is acquired.

<Crosslinking agent>
The crosslinking agent contained in the high dielectric constant rubber composition is not particularly limited as long as it can crosslink the base resin. Examples of such crosslinking agents include organic peroxides such as dialkyl peroxides, diacyl peroxides, ketone peroxides, hydroperoxides, peroxyketals, alkyl peresters, and carbonates, And sulfur.

  Specific examples of the organic peroxide include dicumyl peroxide (DCP), 1,3-bis (t-butylperoxyisopropyl) benzene, and 2,5-dimethyl-2,5- (t-butyl). Peroxy) -3-hexyne, 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2 , 5-Dibenzoylperoxyhexane, n-butyl-4,4-bis (t-butylperoxy) valerate, t-butylperoxybenzoate, 1,4-bis [(t-butylperoxy) isopropyl] Benzene, t-butylcumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, di-t-butylper Kisaido, and the like. These may be used alone or in combination of two or more.

  Although the compounding quantity of a crosslinking agent is not specifically limited, It is preferable that it is 0.5-4.0 mass parts with respect to a total of 100 mass parts of base resin. When the blending amount of the crosslinking agent with respect to 100 parts by mass of the base resin is within the above range, the degree of crosslinking is increased and the heat resistance is further improved as compared with the case of less than 0.5 parts by mass. On the other hand, when the blending amount of the crosslinking agent with respect to 100 parts by mass of the base resin is within the above range, moderate elongation and hardness can be obtained as compared with the case where it exceeds 4.0 parts by mass.

  The high dielectric constant rubber composition further comprises an anti-aging agent, a stabilizer, a flame retardant, a filler, a surface treatment agent, an anti-drip agent, a processing aid, an activator, a crosslinking aid, an anti-scorch agent, etc. as necessary. May be included.

  The high dielectric constant rubber composition is obtained by kneading a base resin, titanate, silane compound and, if necessary, additives other than the crosslinking agent to obtain a kneaded product, and then adding the crosslinking agent to the kneaded product. And kneading. The kneading can be performed with a kneading machine such as a Banbury mixer, a tumbler, a pressure kneader, a kneading extruder, a twin screw extruder, a mixing roll, and the like.

  Next, an example of the manufacturing method of the cable connection part 100 mentioned above is demonstrated.

  First, two power cables 10 and a connecting pipe 5 are prepared. As described above, the power cable 10 includes a main body portion and a tip portion. Then, the central conductor 1 of the third portion at the tip of the two power cables 10 is inserted into the connecting pipe 5 and the connecting pipe 5 is compressed to compress the tip of the two power cables 10 into the connecting pipe 5. The center conductor 1 is fixed.

  Next, a tape made of the internal semiconductive resin composition is wound around the connection pipe 5. At this time, the tape is also wound around the inner semiconductive layer 2 at the second portion of the tip of the power cable 10 so as to be in contact with the inner semiconductive layer 2. The internal electrode 6 is obtained by crosslinking the tape as necessary, and the internal semiconductive layers 2 of the two power cables 10 are connected to each other by the internal electrode 6.

  Next, a tape made of the above-described high dielectric constant rubber composition is wound around the internal electrode 6. At this time, this tape is also wound around the inner semiconductive layer 2 of the second portion at the tip of the power cable 10. And the electric field relaxation part 7 is obtained by bridge | crosslinking this tape. At this time, the crosslinking treatment temperature of the tape may be 150 to 200 ° C., for example, and the crosslinking treatment time may be 0.25 to 1 hour, for example.

  Next, a tape made of an insulating material is wound around the electric field relaxation portion 7. At this time, this tape is also wound around the inner semiconductive layer 2 of the second portion at the tip of the power cable 10. And the insulating part 8 is obtained by bridge | crosslinking a tape as needed.

  Finally, a tape made of an external semiconductive resin composition is wound around the insulating portion 8. At this time, the tape is also wound around the outer semiconductive layer 3 which is the first portion of the tip of the power cable 10 so as to be in contact with the outer semiconductive layer 3. Then, the external electrode 9 is obtained by crosslinking the tape as necessary, and the external semiconductive layers 3 of the two power cables 10 are connected to each other by the external electrode 9.

  The cable connection part 100 is obtained as described above.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the high dielectric constant rubber composition contains a crosslinking agent, but the crosslinking agent is not necessarily required. For example, when the base resin is crosslinked by electron beam irradiation or the like, the high dielectric constant rubber composition may not contain a crosslinking agent.

  Moreover, in the said embodiment, although the high dielectric constant rubber composition of this invention is used as an electric field relaxation part in the cable connection part which connects two electric power cables, the high dielectric constant rubber composition of this invention is Any portion can be used as long as it easily becomes an electric field irregular portion of the power cable as the electric field relaxation portion. For example, since the terminal portion of the power cable tends to be an electric field irregularity portion, the high dielectric constant rubber composition of the present invention can also be applied as an electric field relaxation portion in the terminal portion of the power cable.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

The following materials were used as raw materials for the high dielectric constant rubber composition.
(1) Hydrocarbon rubber EPDM (manufactured by Mitsui Chemicals, trade name “EPT X4010M”, solid state at 20-30 ° C.)
(2) Polar group-containing resin maleic anhydride modified polyethylene (Mitsui Chemicals, trade name “Tuffmer MA9015”)
(3) Liquid hydrocarbon (3-1) polybutene (manufactured by JX Nippon Mining & Energy Corporation, trade name “Nisshi Polybutene HV-300”, liquid state at 20-30 ° C.)
(3-2) Liquid EP (Mitsui Chemicals, trade name “Liquid EPT PX-68”, liquid state at 20-30 ° C.)
(4) Calcium titanate titanate (Fuji Titanium Industry Co., Ltd., trade name “Calcium titanate CT”, average particle size 2 μm)
(5) Silane compound (5-1) Silane compound 1
Vinyltrimethoxysilane (trade name “KBM-1003”, manufactured by Shin-Etsu Silicone Co., Ltd.)
(5-2) Silane compound 2
Vinyltriethoxysilane (manufactured by Shin-Etsu Silicone, trade name “KBE-1003”)
(5-3) Silane compound 3
Hexatriethoxysilane (manufactured by Shin-Etsu Silicone, trade name “KBE-3063”)
(5-4) Silane compound 4
Vinylsilane oligomer (manufactured by EVONIC, trade name “Dynasylan 6498”,
(6) Cross-linking agent dicumyl peroxide: Park Mill D (manufactured by NOF Corporation)

(Examples 1-15 and Comparative Examples 1-3)
The above-mentioned hydrocarbon rubber, polar group-containing resin, liquid hydrocarbon, titanate and silane compound were blended in the proportions shown in Tables 1 to 5, and roll kneading was performed at 100 ° C. Next, a crosslinking agent was added to the kneaded material at a ratio shown in Tables 1 to 5, and roll kneading was performed at 80 ° C. Thus, high dielectric constant rubber compositions of Examples 1 to 15 and Comparative Examples 1 to 3 were obtained. In Tables 1-5, the unit of the compounding quantity of hydrocarbon rubber, polar group containing resin, liquid hydrocarbon, titanate, a silane compound, and a crosslinking agent is a mass part.

<Characteristic evaluation>
(Electrical characteristics)
(1) Decrease rate of volume resistivity due to moisture absorption First, a test piece was prepared as follows.

  First, the high dielectric constant rubber compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 3 were subjected to a crosslinking treatment by pressing at 160 ° C. for 40 minutes using a press machine, and had a thickness of 1 mm and a width. A sheet having a length of 100 mm and a length of 100 mm was produced.

  Next, tin foil was affixed with the petrolatum thinly extended on both surfaces of this sheet | seat, and the electrode was formed. A test piece was thus obtained.

A super insulation meter was connected to the test piece, a DC voltage of 500 V was applied at 30 ° C. for 1 minute, and the volume resistivity of the test piece was measured. And based on the following formula, the rate of decrease in volume resistivity due to moisture absorption was calculated. The results are shown in Tables 1-5.

Reduction rate of volume resistivity due to moisture absorption (%)
= 100 × (volume resistivity before moisture absorption−volume resistivity after moisture absorption) / volume resistivity before moisture absorption

(2) Increasing rate of dielectric loss tangent due to moisture absorption The sheet is sandwiched between a pair of electrodes, an AC voltage is applied using a dielectric constant measuring device (product name “E4980A” manufactured by Agilent Technologies), and the relative dielectric constant at 30 ° C. And the dielectric loss tangent were measured. At this time, the amplitude of the AC voltage applied to the sheet was 1 V, and the frequency was 10 kHz. And based on the following formula, the increase rate of the dielectric loss tangent by moisture absorption was computed. The results are shown in Tables 1-5.

Rate of increase in dielectric loss tangent due to moisture absorption (%)
= 100 × (dielectric loss tangent after moisture absorption−dielectric loss tangent before moisture absorption) / dielectric loss tangent before moisture absorption

(3) Acceptance criteria for electrical characteristics The acceptance criteria for electrical characteristics were as follows.

(Acceptance criteria) Volume resistivity decrease rate due to moisture absorption is 80% or less and dielectric loss tangent increase rate due to moisture absorption is 200% or less

(Processability)
The Mooney viscosity (ML1 + 4, 120 ° C.) at 120 ° C. of the high dielectric constant rubber compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 3 was used as an index of workability. Here, Mooney viscosity was measured based on JISK6300-1. The results are shown in Tables 1-5.

  As shown in each of Tables 1 to 5, the high dielectric constant rubber compositions of Examples 1 to 15 reached the acceptance criteria in terms of the increase rate of dielectric loss tangent due to moisture absorption and the decrease rate of volume resistivity due to moisture absorption. I understood that. On the other hand, it was found that the high dielectric constant rubber compositions of Comparative Examples 1 to 3 did not reach the acceptance criteria in terms of the increase rate of dielectric loss tangent due to moisture absorption and the decrease rate of volume resistivity due to moisture absorption.

  From the above, it was confirmed that the high dielectric constant rubber composition of the present invention can sufficiently suppress a decrease in electrical characteristics of power cable components due to moisture absorption.

  7 ... Electric field relaxation part (components for power cables)

Claims (7)

A base resin containing a hydrocarbon-based rubber and a polar group-containing resin having a polar group;
Titanate,
Look containing a silane compound having an alkoxyl group,
A high dielectric constant rubber composition , wherein the polar group-containing resin is maleic anhydride-modified polyethylene .   The high dielectric constant rubber according to claim 1, wherein the content of the hydrocarbon rubber in the base resin is 10 to 80% by mass, and the polar group-containing resin in the base resin is 20 to 90% by mass. Composition.   The high dielectric constant rubber composition according to claim 1, wherein the base resin further comprises a liquid hydrocarbon in a liquid state at a temperature of at least 20 to 30 ° C. The content of the hydrocarbon rubber in the base resin is 10 to 80% by mass,
The content of the polar group-containing resin in the base resin is 10 to 80% by mass,
The high dielectric constant rubber composition according to claim 3, wherein a content of the liquid hydrocarbon in the base resin is 10 to 70 mass%.   The high dielectric constant rubber composition according to any one of claims 1 to 4, wherein the titanate is blended at a ratio of 50 to 500 parts by mass with respect to 100 parts by mass of the base resin.   The high dielectric constant rubber composition according to any one of claims 1 to 5, wherein the silane compound is blended at a ratio of 0.9 to 10.0 parts by mass with respect to 100 parts by mass of the base resin. . The component for electric power cables obtained by carrying out heat bridge | crosslinking of the high dielectric constant rubber composition as described in any one of Claims 1-6 .

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